Philip Walker

Professor Philip Walker


Emeritus Professor of Physics
BA (1973, Cambridge), PhD (1978, Australian National University)

Academic and research departments

Department of Physics.

Biography

Research

Research interests

My publications

Publications

X Y Watanabe, PHILIP MALZARD WALKER, Y Hirayama, M Mukai, H Watanabe, G.J. Lane, M. Ahmed, MATTHEW HENRY BRUNET, T Hashimoto, S Ishizawa, S Kimura, F. G. Kondev, Yu. A. Litvinov, H Miyatake, J Y Moon, T Niwase, M. Oyaizu, J. H. Park, ZSOLT PODOLYAK, M Rosenbusch, P Schury, M Wada (2021)First direct observation of isomeric decay in neutron-rich odd-odd 186Ta, In: Physical Review C104024330 American Physical Society

De-excitation γ rays associated with an isomeric state of 186 Ta were investigated. The isomers were produced in multinucleon transfer reactions between a 136 Xe beam and a natural W target, and were collected and separated by the KEK Isotope Separation System. Two γ transitions with energies of 161.1(2) and 186.8(1) keV associated with an isomeric decay were observed for the first time. The half-life of the isomeric state of the neutral atom 186m Ta was deduced as 17(2) s. Based on the comparison with the previous measurements of the isomeric state using the ESR storage ring at GSI Darmstadt and the coupling of angular momenta of individual particle orbitals in odd-odd nuclei, a decay scheme of 186m Ta was proposed.

F-Q Chen, Y-X Liu, Y Sun, PM Walker, GD Dracoulis (2012)Residual interactions and the K-mixing-induced fast decay of the three-quasiparticle isomer in Tm-171, In: Physical Review C (Nuclear Physics)85(2)024324pp. ?-? American Physical Society

The anomalously fast decay of a 19/2+ three-quasiparticle isomer in 171Tm was interpreted recently as an example of K mixing induced by a very small mixing matrix element but a (random) close proximity to a collective state. To understand the source of the residual interaction we have generalized the projected shell model by introducing two-body octupole and hexadecupole forces into the Hamiltonian and expanding the model space with inclusion of specific three-quasiparticle configurations. It is found that the K mixing is built up from small interactions transferred through numerous highly excited configurations that contain high-j orbitals. While the chance near-degeneracy enhances the transition strength, the octupole correlation and Coriolis coupling produce the mixing matrix element.

F-Q Chen, Y Sun, JA Sheikh, PM Walker, GD Dracoulis, YR Shimizu (2013)Mixing effects on K-forbidden transition rates from the 6 isomers in the N = 104 isotones, In: Journal of Physics G: Nuclear and Particle Physics40(1)

The problem of the very different E2 decay rates from the two-quasineutron K = 6 isomers in the N = 104 isotones Er, Yb, Hf, and W is investigated using the triaxial projected shell model with inclusion of multi-quasiparticle configurations. It is demonstrated that the highly K-forbidden transition from the 6 isomer to the ground-state band is sensitive to mixing with the 6 state of the γ-vibrational band. Thus the inter-band transitions, and lifetimes, depend on the relative position of the γ-band and the isomeric state in each isotone. © 2013 IOP Publishing Ltd.

S Myalski, A Maj, Z Podolyak, M Kmiecik, P Bednarczyk, J Grebosz, PH Regan, AB Garnsworthy, S Pietri, D Rudolph, SJ Steer, F Becker, J Gerl, M Gorska, H Grawe, I Kojouharov, H Schaffner, HJ Wollersheim, W Prokopowicz, G Benzoni, B Blank, C Brandau, AM Bruce, L Caceres, F Camera, WN Catford, IJ Cullen, Z Dombradi, P Doornenbal, E Estevez, H Geissel, W Gelletly, A Heinz, R Hoischen, G Ilie, GA Jones, A Jungclaus, A Kelic, FG Kondev, T Kurtukian-Nieto, N Kurz, S Lalkovski, Z Liu, F Montes, M Pfuetzner, T Saito, T Shizuma, AJ Simons, S Schwertel, S Tachenov, PM Walker, E Werner-Malento, O Wieland (2012)STUDY OF ISOMER PRODUCTION RATES FOR A=142-152 AND Z=62-67 IN FRAGMENTATION OF A RELATIVISTIC Pb-208 BEAM, In: ACTA PHYSICA POLONICA B43(2)pp. 253-259 WYDAWNICTWO UNIWERSYTETU JAGIELLONSKIEGO
CS PURRY, PM WALKER, GD DRACOULIS, T KIBEDI, S BAYER, AM BRUCE, AP BYRNE, M DASGUPTA, W GELLETLY, F KONDEV, PH REGAN, C THWAITES (1995)ROTATION OF AN 8-QUASI-PARTICLE ISOMER, In: PHYSICAL REVIEW LETTERS75(3)pp. 406-409 AMERICAN PHYSICAL SOC
Y Shi, PM Walker, FR Xu (2012)High-K isomers in neutron-rich zirconium isotopes, In: PHYSICAL REVIEW C85027307 American Physical Society
N Alkhomashi, PH Regan, Z Podolyák, S Pietri, AB Garnsworthy, SJ Steer, J Benlliure, E Caserejos, RF Casten, J Gerl, HJ Wollersheim, J Grebosz, G Farrelly, M Górska, I Kojouharov, H Schaffner, A Algora, G Benzoni, A Blazhev, P Boutachkov, AM Bruce, AMD Bacelar, IJ Cullen, L Cáceres, P Doornenbal, ME Estevez, Y Fujita, W Gelletly, R Hoischen, R Kumar, N Kurz, S Lalkovski, Z Liu, C Mihai, F Molina, AI Morales, D Mücher, W Prokopowicz, B Rubio, Y Shi, A Tamii, S Tashenov, JJ Valiente-Dobón, PM Walker, PJ Woods, FR Xu (2009)β - Dcopy of neutron-rich tantalum nuclei: Shape evolution in neutron-rich tungsten isotopes, In: Physical Review C - Nuclear Physics80(6)064308pp. 1-12
RS Chakrawarthy, PM Walker, JJ Ressler, EF Zganjar, GC Ball, MB Smith, AN Andreyev, SF Ashley, RAE Austin, D Bandyopadhyay, JA Becker, JJ Carroll, DS Cross, D Gohlke, JJ Daoud, PE Garrett, GF Grinyer, G Hackman, GA Jones, R Kanungo, WD Kulp, Y Litvinov, AC Morton, WJ Mills, CJ Pearson, R Propri, CE Svensson, R Wheeler, SJ Williams (2006)K-pi=0(+) 2.29 s isomer in neutron-rich Tm-174, In: PHYSICAL REVIEW C73(2)ARTN 0pp. ?-? AMERICAN PHYSICAL SOC
D T Scholes, D M Cullen, F G Kondev, R V Janssens, M P Carpenter, D J Hartley, M K Djongolov, G Sletten, G Hagemann, C Wheldon, P M Walker, K Abu Saleem, I Ahmad, D L Balabanski, P Chowdhury, M Danchev, G D Dracoulis, H M El-Masri, J Goon, A Heinz, R A Kaye, T L Khoo, T Lauritsen, C J Lister, E F Moore, L L Riedinger, M.A. Riley, D Seweryniak, I Shestakova, I Wiedenhover, O Zeidan, J Y Zhang (2004)Highly Deformed Bands in Hf-175, In: Physical Review C70(5)

Two high-spin regularly spaced rotational bands with large dynamical moments of inertia have been identified in Hf-175 with the Gammasphere spectrometer. These new bands are very similar to the previously identified triaxial superdeformed bands in the hafnium nuclei. However, the new bands in Hf-175 have been linked into the known level scheme and thereby provide the first firm spin assignments for these structures in this region. In order to understand the new bands, theoretical calculations have been performed based on the ULTIMATE CRANKER code. The new bands in Hf-175 are deduced to be built upon highly deformed structures. No experimental evidence for triaxiality was established and this work suggests that the structure of the so-called "triaxial" superdeformed bands in the Hf nuclei may be quite different from those identified in the lighter mass Lu nuclei. Since the two highly deformed bands in Hf-175 are associated with different deformations, this work also identifies the role of the intruder orbits in polarizing the nuclear shape.

D. A. Eastham, P. M. Walker, J. A. R. Griffith, D. E. Evans, Jonathan England, I. S. Grant (1984)Optical isotope shifts of 146Sm and 151Sm, In: Zeitschrift fur Physik A Atoms and Nuclei318(2)pp. 243-244 Springer-Verlag

We have measured the optical isotope shifts of146Sm and151Sm by laser resonance fluorescence. From these measurements the changes in the mean square nuclear radii are: Δ〈r2〉 (A=144 to 146)=0.266(10) fm2, and Δ〈r2〉 (A=151 to 152)=0.262(10) fm2. These results, together with those of the stable isotopes, show that the average nuclear expansion of samarium can be accounted for by the liquid drop model with deformations.

MW Reed, PM Walker, IJ Cullen, YA Litvinov, D Shubina, GD Dracoulis, K Blaum, F Bosch, C Brandau, JJ Carroll, DM Cullen, AY Deo, B Detwiler, C Dimopoulou, GX Dong, F Farinon, H Geissel, E Haettner, M Heil, RS Kempley, R Knoebel, C Kozhuharov, J Kurcewicz, N Kuzminchuk, S Litvinov, Z Liu, R Mao, C Nociforo, F Nolden, WR Plass, Z Podolyak, A Prochazka, C Scheidenberger, M Steck, T Stoehlker, B Sun, TPD Swan, G Trees, H Weick, N Winckler, M Winkler, PJ Woods, FR Xu, T Yamaguchi (2012)Long-lived isomers in neutron-rich Z=72-76 nuclides, In: PHYSICAL REVIEW C86(5)ARTN 0pp. ?-? AMER PHYSICAL SOC

A study of neutron-rich isotopes in the A=185 region of the nuclear chart has uncovered long-lived (>1s) isomers in several isotopes of hafnium, tantalum, tungsten, rhenium, and osmium. The region was accessed via the use of projectile fragmentation with the UNILAC-SIS accelerators at GSI. Fragmentation products of 197Au were passed through the fragment separator (FRS) and injected into the experimental storage ring (ESR), where single-ion identifications could be made. Evidence is presented for isomers in 183184 186Hf, 186187Ta,186W, 190192 194Re, and 195Os with excitation energies in the range of 0.13.0 MeV. The lightest of these nuclides have well deformed prolate shapes, while the heaviest are transitional and susceptible to shape changes. Their properties are interpreted with the help of multi-quasiparticle and potential-energy- surface calculations. ©2012 American Physical Society.

XL Tu, A Kelic-Heil, Y Litvinov, Zsolt Podolyak, YH Zhang, WJ Huang, HS Xu, K Blaum, F Bosch, RJ Chen, Philip Walker (2017)Application of Isochronous Mass Spectrometry for the study of angular momentum population in projectile fragmentation reactions, In: Physical Review C: Nuclear Physics95(1)014610 American Physical Society

Isochronous mass spectrometry was applied to measure isomeric yield ratios of fragmentation reaction prod- ucts. This approach is complementary to conventional g -ray spectroscopy in particular for measuring yield ratios for long-lived isomeric states. Isomeric yield ratios for the high-spin I = 19=2¯h states in the mirror nuclei 53Fe and 53Co are measured to study angular momentum population following the projectile fragmentation of 78Kr at energies of 480 A MeV on a beryllium target. The 19/2 state isomeric ratios of 53Fe produced from different projectiles in literature have also been extracted as a function of mass number difference between projectile and fragment (mass loss). The results are compared to ABRABLA07 model calculations. The isomeric ratios of 53Fe produced using different projectiles suggest that the theory underestimates not only the previously reported dependence on the spin but also the dependence on the mass loss.

E. Ngijoi-Yogo, S. K. Tandel, G. Mukherjee, I. Shestakova, P. Chowdhury, C. Y. Wu, D. Cline, A. B. Hayes, R. Teng, R. M. Clark, P. Fallon, A. O. Macchiavelli, K. Vetter, F. G. Kondev, S. Langdown, P. M. Walker, C. Wheldon, D. M. Cullen (2007)Collective rotation and vibration in neutron-rich 180,182Hf nuclei, In: Physical Review C75(034305)
P Walker (2011)NUCLEAR ASTROPHYSICS Star bursts pinned down, In: NAT PHYS7(4)pp. 281-282 NATURE PUBLISHING GROUP
H Watanabe, G Zhang, K Yoshida, Philip Walker, J Liu, J Wu, Patrick Regan, PA Soderstrom, H Kanaoka, Z Korkulu, PS Lee, S Nishimura, A Yagi, DS Ahn, T Alharbi, H Baba, F Browne, AM Bruce, RJ Fukuda, C Griffin, E Ideguchi, N Inabe, T Isobe, S Kanaya, I Kojouharov, FG Kondev, T Kubo, S Kubono, N Kurz, I Kuti, S Lalkovski, GJ Lane;, CS Lee, EJ Lee, G Lorusso, Gavin Lotay, CB Moon, I Nishizuka, CR Nita, A Odahara, Z Patel, VH Phong, Zsolt Podolyak, OJ Roberts, H Sakurai, H Schaffner, Callum Shand, Y Shimizu, T Sumikama, H Suzuki, H Takeda, S Terashima, Z Vajta;, JJ Valiente-Dobon, ZY Xu (2016)Long-lived K isomer and enhanced gamma vibration in the neutron-rich nucleus 172Dy: Collectivity beyond double midshell, In: Physics Letters B760(Sept)pp. 641-646 Elsevier

The level structure of 172Dy has been investigated for the first time by means of decay spectroscopy following in-flight fission of a 238U beam. A long-lived isomeric state with T1/2 = 0.71(5) s and K π = 8 − has been identified at 1278 keV, which decays to the ground-state and γ-vibrational bands through hindered electromagnetic transitions, as well as to the daughter nucleus 172Ho via allowed β decays. The robust nature of the K π = 8 − isomer and the ground-state rotational band reveals an axially-symmetric structure for this nucleus. Meanwhile, the γ-vibrational levels have been identified at unusually low excitation energy compared to the neighboring well-deformed nuclei, indicating the significance of the microscopic effect on the non-axial collectivity in this doubly mid-shell region. The underlying mechanism of enhanced γ vibration is discussed in comparison with the deformed Quasiparticle Random-Phase Approximation based on a Skyrme energy-density functional.

L Chen, WR Plaß, H Geissel, R Knöbel, C Kozhuharov, Y Litvinov, Z Patyk, C Scheidenberger, K Siegień-Iwaniuk, B Sun, H Weick, K Beckert, P Beller, F Bosch, D Boutin, L Caceres, JJ Carroll, DM Cullen, IJ Cullen, B Franzke, J Gerl, M Górska, GA Jones, A Kishada, J Kurcewicz, SA Litvinov, Z Liu, S Mandal, F Montes, G Münzenberg, F Nolden, T Ohtsubo, Z Podolyák, R Propri, S Rigby, N Saito, T Saito, M Shindo, M Steck, PM Walker, S Williams, M Winkler, H-J Wollersheim, T Yamaguchi (2012)New results on mass measurements of stored neutron-rich nuclides in the element range from Pt to U with the FRS-ESR facility at 360-400MeV/u, In: Nuclear Physics A882pp. 71-89 Elsevier

Masses of 238U projectile fragments have been measured with time-resolved Schottky Mass Spectrometry (SMS) at the FRS-ESR facility at GSI. The exotic nuclei were created in the production target at the entrance of the fragment separator FRS, spatially separated in flight and injected into the storage-cooler ring ESR at about 70% light velocity. This means the ions were mainly bare or carried only a few electrons, e.g., the population of Li-like ions was below 1% for Pt fragments. Accurate newmass values of 33 neutron-rich, stored exotic nuclei in the element range from platinum to uranium have been obtained for the first time. In total more than 150 nuclides including references with well-known masses have been covered in this large-area SMS measurement. A novel data analysis has been applied which reduces the systematic errors by taking into account the velocity profile of the cooler electrons and the residual ion-optical dispersion in this part of the storage ring. The experiment, the data analysis, and the mass values are presented. The experimental data are compared with theoretical predictions demonstrating systematic deviations of up to 1500 keV from modern mass models.

M DASGUPTA, PM WALKER, GD DRACOULIS, AP BYRNE, PH REGAN, T KIBEDI, GJ LANE, KC YEUNG (1994)YRAST ISOMERS, MULTI-QUASI-PARTICLE STATES AND BLOCKING IN TA-176 AND TA-177, In: PHYSICS LETTERS B328(1-2)pp. 16-21 ELSEVIER SCIENCE BV
F. R. Xu, P. M. Walker, R. Wyss (2000)Limit to high-spin isomerism in hafnium isotopes, In: Physical Review C62(014301)
Z Podolyak, PH Regan, PM Walker, M Caamano, K Gladnishki, J Gerl, M Hellstrom, P Mayet, M Pfutzner, M Mineva (2003)Heavy nuclei studied in projectile fragmentation, In: NUCLEAR PHYSICS A722pp. 273C-278C
F Sarazin, J S Al-Khalili, G C Ball, G Hackman, P M Walker, R A Austin, B Eshpeter, P Finlay, P E Garrett, G F Grinyer, K A Koopmans, W D Kulp, J R Leslie, D Melconian, C J Osborne, M A Schumaker, H C Scraggs, J Schwarzenberg, M B Smith, C E Svensson, J C Waddington, J L Wood (2004)Halo Neutrons and the Beta Decay of Li-11, In: Physical Review C70(3)

The beta decay of Li-11 has been investigated at TRIUMF-ISAC using a high-efficiency array of Compton suppressed HPGe detectors. From a line-shape analysis of the Doppler-broadened peaks observed in the Be-10 gamma spectrum, both the half-lives of states in Be-10 and the energies of the beta-delayed neutrons feeding those states were obtained. Furthermore, it was possible to determine the excitation energies of the parent states in Be-11 with uncertainties comparable to those obtained from neutron spectroscopy experiments. These data suggest that the beta decay to the 8.81 MeV state in Be-11 occurs in the Li-9 core and that one neutron comprising the halo of Li-11 survives in a halolike configuration after the beta-delayed neutron emission from this level.

P.-A. Söderström, Philip Walker, J. Wu, H. L. Liu, Patrick Regan, H. Watanabe, P. Doornenbal, Z. Korkulu, P. Lee, J. J. Liu, G. Lorusso, S. Nishimura, V. H. Phong, T. Sumikama, F. R. Xu, A. Yagi, G. X. Zhang, D. S. Ahn, T. Alharbi, H. Baba, F. Browne, A. M. Bruce, R. J. Carroll, K. Y. Chae, Zs. Dombradi, A. Estrade, N. Fukuda, C. Griffin, E. Ideguchi, N Inabe, T. Isobe, H. Kanaoka, S. Kanaya, I. Kojouharov, F. G. Kondev, T. Kubo, S. Kubono, N. Kurz, I. Kuti, S. Lalkovski, G. J. Lane, E. J. Lee, C. S. Lee, GAVIN JAMES LOTAY, C.-B. Moon, I. Nishizuka, C. R. Nita, A. Odahara, Z. Patel, Zsolt Podolyak, O. J. Roberts, H. Sakurai, H. Schaffner, C. M. Shand, H. Suzuki, H. Takeda, S. Terashima, Zs. Vajta, J. J. Valiente-Dòbon, Z. Y. Xui (2016)Collective And Single-particle Structures In The Neutron-rich Doubly Mid-shell Nucleus 170Dy, In: Proceedings of Science: The 26th International Nuclear Physics Conference

One of the most successful descriptions of the structure of atomic nuclei is the spherical shell model. It, however, becomes impractical when moving away from closed-shell nuclei. Instead, it is the interplay between the macroscopic shape degrees of freedom and the microscopic nature of the underlying single-particle structure in a deformed basis that determines the nuclear structure. Being the heaviest nucleus precisely in the middle of, known, closed proton and neutron shells, 170Dy has become a central calibration point for tests of collective models of nuclear physics. However, besides one candidate transition from a previous experiment in Legnaro, Italy, no experimental information is available for this nucleus. Using the EURICA setup at RIKEN, which couples the worlds highest intensity in-flight fission facility with a high-efficiency HPGe array, an experiment in November 2014 produced 170Dy nuclei by in-flight fission of a 238U beam. The results from this experiment provide a wealth of information on this elusive nucleus, including the evolution of quadrupole collectivity, rigidity and higher order deformations, as well as the long sought for isomeric K = 6+ state, predicted to be exceptionally pure at mid-shell. These results provide us with a rich level scheme for discussing both single-particle and collective structures at mid-shell.

B Sun, R Knoebel, H Geissel, YA Litvinov, PM Walker, K Blaum, F Bosch, D Boutin, C Brandau, L Chen, IJ Cullen, A Dolinskii, B Fabian, M Hausmann, C Kozhuharov, J Kurcewicz, SA Litvinov, Z Liu, M Mazzocco, J Meng, F Montes, G Muenzenberg, A Musumarra, S Nakajima, C Nociforo, F Nolden, T Ohtsubo, A Ozawa, Z Patyk, WR Plass, C Scheidenberger, M Steck, T Suzuki, H Weick, N Winckler, M Winkler, T Yamaguchi (2010)Direct measurement of the 4.6 MeV isomer in stored bare Sb-133 ions, In: PHYSICS LETTERS B688(4-5)pp. 294-297 ELSEVIER SCIENCE BV
E Wilson, Z Podolyak, B Fornal, RVF Janssens, M Bowry, M Bunce, MP Carpenter, CJ Chiara, N Cieplicka, AY Deo, GD Dracoulis, H Grawe, CR Hoffman, RS Kempley, FG Kondev, GJ Lane, T Lauritsen, MW Reed, PH Regan, CR Triguero, B Szpak, PM Walker, S Zhu, S Lunardi, PG Bizzeti, S Kabana, C Bucci, M Chiari, A Dainese, P DiNezza, R Menegazzo, A Nannini, C Signorini, JJ ValienteDobon (2014)Study of (TI126)-T-207 Produced in Deep-Inelastic Reactions, In: INPC 2013 - INTERNATIONAL NUCLEAR PHYSICS CONFERENCE, VOL. 166ARTN 0pp. ?-? E D P SCIENCES
AY Deo, Z Podolyak, PM Walker, A Algora, B Rubio, J Agramunt, LM Fraile, N Al-Dahan, N Alkhomashi, JA Briz, E Estevez, G Farrelly, W Gelletly, A Herlert, U Koester, A Maira, S Singla (2010)Structures of Po-201 and Rn-205 from EC/beta(+)-decay studies, In: PHYSICAL REVIEW C81(2)ARTN 0pp. ?-? AMER PHYSICAL SOC
A Gottardo, JJ Valiente-Dobon, G Benzoni, A Gadea, S Lunardi, P Boutachkov, AM Bruce, M Gorska, J Grebosz, S Pietri, Z Podolyak, M Pfuetzner, PH Regan, H Weick, J Alcantara Nunez, A Algora, N Al-Dahan, G de Angelis, Y Ayyad, N Alkhomashi, PRP Allegro, D Bazzacco, J Benlliure, M Bowry, A Bracco, M Bunce, F Camera, E Casarejos, ML Cortes, FCL Crespi, A Corsi, AMD Bacelar, AY Deo, C Domingo-Pardo, M Doncel, Z Dombradi, T Engert, K Eppinger, GF Farrelly, F Farinon, E Farnea, H Geissel, J Gerl, N Goel, E Gregor, T Habermann, R Hoischen, R Janik, PR John, S Klupp, I Kojouharov, N Kurz, SM Lenzi, S Leoni, S Mandal, R Menegazzo, D Mengoni, B Million, V Modamio, AI Morales, DR Napoli, F Naqvi, R Nicolini, C Nociforo, A Prochazka, W Prokopowicz, F Recchia, RV Ribas, MW Reed, D Rudolph, E Sahin, H Schaffner, A Sharma, B Sitar, D Siwal, K Steiger, P Strmen, TPD Swan, I Szarka, CA Ur, PM Walker, O Wieland, H-J Wollersheim, S Lunardi, PG Bizzeti, S Kabana, C Bucci, M Chiari, A Dainese, P DiNezza, R Menegazzo, A Nannini, C Signorini, JJ ValienteDobon (2014)New Isomers in the Neutron-Rich Region Beyond Pb-208, In: INPC 2013 - INTERNATIONAL NUCLEAR PHYSICS CONFERENCE, VOL. 166ARTN 0pp. ?-? E D P SCIENCES
P M Walker, F R Xu (2006)Shapes of Neutron-Rich A Approximate to 190 Odd-Odd Nuclei, In: Physical Review C74(6)

The occurrence of oblate and prolate shapes is investigated theoretically for odd-odd neutron-rich nuclei with A approximate to 190. Using the cranked Woods-Saxon-Strutinsky method, including configuration constraints, it is found that collective oblate rotation coexists with high-K prolate rotation, for tantalum and rhenium isotopes with N=115 and 117.

PM Walker, S Lalkovski, PD Stevenson (2010)Configuration dependence of K-forbidden transition rates from three-quasiparticle isomers, In: PHYSICAL REVIEW C81(4)ARTN 0pp. ?-? AMER PHYSICAL SOC
PM Walker (2010)High-spin isomers: structure and applications, In: NUCLEAR PHYSICS A834(1-4)pp. 22C-27C
M Nakhostin, PM Walker (2010)Determination of gas amplification factor by digital waveform analysis of avalanche counter signals, In: NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT615(1)pp. 53-56 ELSEVIER SCIENCE BV
M Nakhostin, Z Podolyak, PH Regan, PM Walker (2010)A digital method for separation and reconstruction of pile-up events in germanium detectors, In: REVIEW OF SCIENTIFIC INSTRUMENTS81(10)ARTN 1pp. ?-? AMER INST PHYSICS
J Sethi, R Palit, S Saha, T Trivedi, R Donthi, S Jadhav, HC Jain, BS Naidu, GH Bhat, JA Sheikh, P Datta, JJ Carroll, MS Litz, D Mehta, S Chattopadhyay, U Garg, S Karamian, S Kumar, S Sihotra, Z Naik, PM Walker (2014)Study of the level structure of Ag, In: EPJ Web of Conferences66

The high spin structure of Ag nucleus has been studied using the reaction B + Mo at 39 MeV with Indian National Gamma Array (INGA) at TIFR-BARC accelerator facility. From the two- and higher-fold coincidence analysis of the emitted γ-rays, the level structure of the nucleus is built, with addition of around ∼ 60 new transitions. A new positive parity dipole band has been observed and significant additions have been made in the low spin region. A pair of nearly degenerate, negative parity, dipole bands is established, which is studied using the triaxial projected shell model (TPSM). © Owned by the authors, published by EDP Sciences, 2014.

H Watanabe, T Sumikama, S Nishimura, K Yoshinaga, Z Li, Y Miyashita, K Yamaguchi, H Baba, JS Berryman, N Blasi, A Bracco, F Camera, J Chiba, P Doornenbal, S Go, T Hashimoto, S Hayakawa, C Hinke, E Ideguchi, T Isobe, Y Ito, DG Jenkins, Y Kawada, N Kobayashi, Y Kondo, R Krücken, S Kubono, G Lorusso, T Nakano, M Kurata-Nishimura, A Odahara, HJ Ong, S Ota, Z Podolyák, H Sakurai, H Scheit, Y Shi, K Steiger, D Steppenbeck, K Sugimoto, K Tajiri, S Takano, A Takashima, T Teranishi, Y Wakabayashi, PM Walker, O Wieland, FR Xu, H Yamaguchi (2011)Low-lying level structure of the neutron-rich nucleus 109Nb: A possible oblate-shape isomer, In: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics696(3)pp. 186-190 Elsevier
Laila Gurgi, Patrick Regan, P-A Söderström, H Watanabe, Philip Walker, Zsolt Podolyak, S Nishimura, Thomas Berry, P Doornenbal, G Lorusso, T Isobe, H Baba, ZY Xu, H Sakurai, T Sumikama, Wilton Catford, AM Bruce, F Browne, GJ Lane, FG Kondev, A Odahara, J Wu, HL Liu, FR Xu, Z Korkulu, P Lee, JJ Liu, VH Phong, A Yag, GX Zhang, T Alharbi, RJ Carroll, KY Chae, Zs Dombradi, A Estrade, N Fukuda, C Griffin, E Ideguchi, N Inabe, H Kanaoka, I Kojouharov, T Kubo, S Kubono, N Kurz, I Kuti, S Lalkovski, EJ Lee, CS Lee, Gavin Lotay, C-B Moon, I Nishizuka, CR Nita, Z Patel, OJ Roberts, H Schaffner, Callum Shand, H Suzuki, H Takeda, S Terashima, Zs Vajta, S Yoshida, JJ Valiente-Dòbon (2016)Isomer spectroscopy of neutron-rich 168Tb103, In: Radiation Physics and Chemistry140pp. 493-496 Elsevier

In-flight fission of a 345 MeV per nucleon 238U primary beam on a 2 mm thick 9Be target has been used to produce and study the decays of a range of neutron-rich nuclei centred around the doubly mid-shell nucleus 170Dy at the RIBF Facility, RIKEN, Japan. The produced secondary fragments of interest were identified eventby- event using the BigRIPS separator. The fragments were implanted into the WAS3ABI position sensitive silicon active stopper which allowed pixelated correlations between implants and their subsequent β-decay. Discrete γ-ray transitions emitted following decays from either metastable states or excited states populated following beta decay were identified using the 84 coaxial high-purity germanium (HPGe) detectors of the EURICA spectrometer, which was complemented by 18 additional cerium-doped lanthanum bromide (LaBr3)

M Caamano, PM Walker, PH Regan, CJ Pearson, Z Podolyak, P Mayet, J Gerl, C Schlegel, M Hellstrom, M Mineva, M Pfutzner (2001)Isomeric decays in Pt-200, In: ACTA PHYSICA POLONICA B32(3)pp. 763-766
P. H. Regan, T. M. Menezes, C. J. Pearson, W. Gelletly, C. S. Purry, P. M. Walker, S. Juutinen, R. Julin, K. Helariutta, A. Savelius, P. Jones, P. Jämsen, M. Muikku, P. A. Butler, G. Jones, P. Greenlees (1997)Observation of (h11/2)2 neutron alignments in 100Mo, 104Ru, and 108Pd using deep inelastic reactions, In: Physical Review C55(2305)pp. 2305-2313
K. Andgren, Zs. Podolyák, A. Dewald, F. R. Xu, A. Algora, M. Axiotis, D. Bazzacco, P. G. Bizzeti, A. M. Bizzeti-Sona, B. Cederwall, G. de Angelis, E. Farnea, A. Fitzler, A. Gadea, W. Gelletly, S. Lunardi, O. HASH(0xa160c18) Möller, N. Marginean, T. Martinez, T. Pissulla, C. Rusu, C. A. Ur, R. VenturellI, P. M. Walker, C. Wheldon (2005)Lifetime measurements of normal deformed states in 71165Lu, In: Physical Review C71(014312)
P. M. Walker, F. R. Xu (2006)Shapes of neutron-rich A ≈ 190 odd-odd nuclei, In: Physical Review C74(067303)
GA Jones, PH Regan, PM Walker, Z Podolyak, PD Stevenson, MP Carpenter, JJ Carroll, RS Chakrawarthy, P Chowdhury, AB Garnsworthy, RVF Janssens, TL Khoo, FG Kondev, GJ Lane, Z Liu, D Seweryniak, NJ Thompson, S Zhu, SJ Williams (2007)Identification of a high-spin isomer in (99)Mo, In: PHYSICAL REVIEW C76(4)ARTN 0pp. ?-? AMER PHYSICAL SOC
H. L. Liu, F. R. Xu, S. W. Xu, R. Wyss, P. M. Walker (2007)High-spin isomeric structures in exotic odd-odd nuclei: Exploration of the proton drip line and beyond, In: Physical Review C76(034313)

We investigate the role of two-quasiparticle isomeric states along the proton drip line, using configuration-constrained potential-energy-surface calculations. In contrast to even-even nuclei, odd-odd nuclei can have coexisting low-lying two-quasiparticle states. The low excitation energy and high angular momentum can lead to long-lived isomers. Also, because of the hindrance by spin selection, the probabilities of beta and proton decays from high-spin isomers can be reduced significantly. The present calculations reproduce reasonably well the available data for observed isomers in such nuclei. Unobserved high-spin isomers are predicted, which could be useful for future experimental studies of exotic nuclei at and beyond the proton drip line.

Sareh D. Al-Garni, P. H. Regan, P. M. Walker, E. Roeckl, R. Kirchner, F. R. Xu, L. Batist, A. Blazhev, R. Borcea, D. M. Cullen, J. Döring, H. M. El-Masri, J. R. Garces Narro, H. Grawe, M. La Commara, C. Mazzocchi, I. Mukha, C. J. Pearson, C. Plettner, K. Schmidt, W. -D. Schmidt-Ott, Y. Shimbara, C. Wheldon, R. Wood, S. C. Wooding (2004)Evidence for a high-spin beta-decaying isomer in 177Lu, In: Physical Review C69(024320)
PM Walker, A Woehr, A Aprahamian (2006)Nuclear isomers: stepping stones to the unknown, In: Capture Gamma-Ray Spectroscopy and Related Topics819pp. 16-23
Alexandros Giatzoglou, Tanapoom Poomaradee, Ilkka Pohjalainen, Sami Rinta-Antila, Iain D. Moore, Philip M. Walker, Luca Marmugi, Ferruccio Renzoni (2018)A facility for production and laser cooling of cesium isotopes and isomers, In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment908pp. 367-375 Elsevier

We report on the design, installation, and test of an experimental facility for the production of ultra-cold atomic isotopes and isomers of cesium. The setup covers a broad span of mass numbers and nuclear isomers, allowing one to directly compare chains of isotopes and isotope/isomer pairs. Cesium nuclei are produced by fission or fusion-evaporation reactions using primary proton beams from a 130 MeV cyclotron impinging upon a suitable target. The species of interest is ejected from the target in ionic form, electrostatically accelerated, mass separated, and routed to a science chamber. Here, ions are neutralized by implantation in a thin foil, and extracted by thermal diffusion. A neutral vapor at room temperature is thus formed and trapped in a magneto-optical trap. Real-time fluorescence imaging and destructive absorption imaging provide information on the number of trapped atoms, their density, and their temperature. Tests with a dedicated beam of 133Cs + ions at 30 KeV energy confirm neutralization, evaporation, and laser cooling to 150 μ K, with an average atomic density of 1010 cm−3. Availability of cold and dense atomic samples of Cs isotopes and isomers opens new avenues for high-precision measurements of isotopic and isomeric shifts thereby gaining deeper insight into the nuclear structure, as well as for sensitive measurements of isotopes’ concentration ratios in trace quantities. The facility also constitutes the core for future experiments of many-body physics with nuclear isomers.

PH REGAN, GD DRACOULIS, AP BYRNE, GJ LANE, T KIBEDI, PM WALKER, AM BRUCE (1995)HIGH-K STRUCTURES IN SM-136, In: PHYSICAL REVIEW C51(4)pp. 1745-1753 AMERICAN PHYSICAL SOC
N Al-Dahan, PH Regan, Z Podolyák, PM Walker, N Alkhomashi, GD Dracoulis, G Farrelly, J Benlliure, SB Pietri, RF Casten, PD Stevenson, W Gelletly, SJ Steer, AB Garnsworthy, E Casarejos, J Gerl, HJ Wollersheim, J Grebosz, M Górska, I Kojouharov, H Schaffner, A Algora, G Benzoni, A Blazhev, P Boutachkov, AM Bruce, IJ Cullen, AM Denis Bacelar, AY Deo, ME Estevez, Y Fujita, R Hoischen, R Kumar, S Lalkovski, Z Liu, PJ Mason, C Mihai, F Molina, D Mücher, B Rubio, A Tamii, S Tashenov, JJ Valiente-Dobón, PJ Woods (2012)Multiple β - Decaying states in 194Re: Shape evolution in neutron-rich osmium isotopes, In: Physical Review C - Nuclear Physics85(3)034301pp. ?-? American Physical Society

decays from heavy, neutron-rich nuclei with A∼190 have been investigated following their production via the relativistic projectile fragmentation of an E/A=1 GeV 208Pb primary beam on a ∼2.5 g/cm2 9Be target. The reaction products were separated and identified using the GSI FRagment Separator (FRS) and stopped in the RISING active stopper. γ decays were observed and correlated with these secondary ions on an event-by-event basis such that γ-ray transitions following from both internal (isomeric) and β decays were recorded. A number of discrete, β-delayed γ-ray transitions associated with β decays from 194Re to excited states in 194Os have been observed, including previously reported decays from the yrast Iπ=(6+) state. Three previously unreported γ-ray transitions with energies 194, 349, and 554 keV are also identified; these transitions are associated with decays from higher spin states in 194Os. The results of these investigations are compared with theoretical predictions from Nilsson multi-quasiparticle (MQP) calculations. Based on lifetime measurements and the observed feeding pattern to states in 194Os, it is concluded that there are three β−-decaying states in 194Re.

GA Jones, PM Walker, Z Podoydk, PH Regan, SJ Williams, MP Carpentert, JJ Carroll, RS Chakrawarthy, P Chowdhury, IJ Cullen, GD Dracoulis, AB Gamsworthy, G Hackman, RVF Janssens, TL Khoo, FG Kondev, GJ Lane, Z Liu, D Seweryniak, NJ Thompson, S Zhu (2006)Microsecond and nanosecond isomers populated in fission reactions, In: FUSION06: Reaction Mechanisms and Nuclear Structure at the Coulomb Barrier853pp. 342-349
P M Walker, J J Carroll (2005)Ups and Downs of Nuclear Isomers, In: Physics Today58(6)
J. A. Sheikh, Y. Sun, P. M. Walker (1998)Projected shell model analysis of tilted rotation, In: Physical Review C57

An alternative description of tilted rotation, observed in deformed nuclei, is presented using the projected shell model approach. It is shown that a strong configuration mixing among the projected states is responsible for the appearance of the tilted bands near to, but slightly above, the yrast line in even-even tungsten isotopes. Various tilted bands in 184Os are also predicted.

Z Patel, Z Podolyak, PM Walker, PH Regan, P-A Söderström, H Watanabe, E Ideguchi, GS Simpson, S Nishimura, F Browne, P Doornenbal, P Lorusso, S Rice, L Sinclair, T Sumikama, J Wu, ZY Xu, N Aoi, H Baba, FL Bello Garrote, G Benzoni, R Daido, Z Dombrádi, Y Fang, N Fukuda, G Gay, S Go, A Gottardo, N Inabe, T Isobe, K Kameda, K Kobayashi, M Kobayashi, T Komatsubara, I Kojouharov, T Kubo, N Kurz, I Kuti, Z Li, HL Liu, M Matsushita, S Michimasa, CB Moon, H Nishibata, I Nishizuka, A Odahara, E Sahin, H Sakurai, H Schaffner, H Suzuki, H Takeda, J Taprogge, Z Vajta, FR Xu, A Yagi, R Yokoyama (2016)β-decay spectroscopy of neutron-rich 160,161,162Sm isotopes, In: EPJ Web of Conferences123 (2

Neutron-rich 160,161,162Sm isotopes have been populated at the RIBF, RIKEN via β first time. β-coincident γ rays were observed in all three isotopes including γ rays from the isomeric decay of 160Sm and 162Sm. The isomers in 160Sm and 162Sm have previously been observed but have been populated via β decay for the first time. The isomeric state in 162Sm is assigned a configuration based on the decay pattern. The level schemes of 160Sm and 162Sm are presented. The ground states in the parent nuclei 160Pm and 162Pm are both assigned a configuration based on the population of states in the daughter nuclei. Blocked BCS calculations were performed to further investigate the spin-parities of the ground states in 160Pm, 161Pm, and 162Pm, and the isomeric state in 162Sm

T Shizuma, T Ishii, H Makii, T Hayakawa, S Shigematsu, M Matsuda, E Ideguchi, Y Zheng, M Liu, T Morikawa, PM Walker, M Oi (2006)Excited states in neutron-rich W-188 produced by an O-18-induced 2-neutron transfer reaction, In: EUROPEAN PHYSICAL JOURNAL A30(2)pp. 391-396 SPRINGER
CF Jiao, Y Shi, FR Xu, FR Xu, Y Sun, Y Sun, PM Walker, PM Walker (2012)Competition between collective oblate rotation and non-collective prolate K isomerism in neutron-rich tungsten isotopes, In: Science China: Physics, Mechanics and Astronomy55(9)pp. 1613-1617

Recent experiments open up the possibility to investigate oblate rotation-aligned states and prolate high-K isomers in neutron-rich tungsten isotopes. In the present work, we perform the projected-shell-model calculations for A ̃ 190 tungsten nuclei. The W results are compared with experimental data. The observed 8+ isomer is assigned as a two-quasiproton Kφ = 8 configuration. Low-lying high-K four-quasiparticle states are predicted. Of particular interest is the prediction of the Kφ = 20+ state in 190,192W, which may form a long-lived spin trap. In competition with the prolate high-K states, rotational alignment leads to near-yrast collective oblate rotation. © Science China Press and Springer-Verlag Berlin Heidelberg 2012.

SJ Steer, ZS PodolyÁk, S Pietri, M GÓrska, GF Farrelly, PH Regan, D Rudolph, AB Garnsworthy, R Hoischen, J Gerl, HJ Wollersheim, H Grawe, KH Maier, F Becker, P Bednarczyk, L CÁceres, P Doornenbal, H Geissel, J Grbosz, A Kelic, I Kojouharov, N Kurz, F Montes, W Prokopowicz, T Saito, H Schaffner, S Tashenov, A Heinz, T Kurtukian-Nieto, G Benzoni, M PfÜtzner, A Jungclaus, DL Balabanski, C Brandau, A Brown, AM Bruce, WN Catford, IJ Cullen, Z DombrÁdi, ME Estevez, W Gelletly, G Ilie, J Jolie, GA Jones, M Kmiecik, FG Kondev, R KrÜcken, S Lalkovski, Z Liu, A Maj, S Myalski, S Schwertel, T Shizuma, PM Walker, E Werner-Malento, O Wieland (2009)Isomeric decay studies in neutron-rich N ≈ 126 nuclei, In: International Journal of Modern Physics E18(4)pp. 1002-1007

Heavy neutron-rich nuclei were populated via relativistic energy fragmentation of a E/A=1 GeV 208Pb beam. The nuclei of interest were selected and identified by a fragment separator and then implanted in a passive plastic stopper. Delayed rays following internal isomeric decays were detected by the RISING array. Experimental information was obtained on a number of nuclei with Z=73-80 (Ta-Hg), providing new information both on the prolate-oblate transitional region as well as on the N=126 closed shell nuclei.

T. L. Shaw, V. R. Green, C. J. Ashworth, J. Rikovska, N. J. Stone, P. M. Walker, I. S. Grant (1987)On-line nuclear orientation of cesium isotopes and the magnetic moment of 118Csm, In: Physical Review C36(413)pp. 413-415
C. Thwaites, C. Wheldon, A. M. Bruce, P. M. Walker, G. D. Dracoulis, A. P. Byrne, T. Kibédi, F. G. Kondev, C. J. Pearson, C. S. Purry (2002)Persistence of |K isomerism in the N=104 isotones: Observation of a high-seniority isomer in 75179Re, In: Physical Review C66(054309)
PM Walker, DM Cullen, CS Purry, DE Appelbe, AP Byrne, GD Dracoulis, T Kibedi, FG Kondev, LY Lee, AO Macchiavelli, AT Reed, PH Regan, F Xu (1997)K-forbidden transitions from multi-quasiparticle states, In: PHYSICS LETTERS B408(1-4)pp. 42-46 ELSEVIER SCIENCE BV
P. H. Regan, F. R. Xu, P. M. Walker, M. Oi, A. K. Rath, P. D. Stevenson (2002)Structure of the doubly midshell nucleus 66170Dy104, In: Physical Review C65(037302)
Z Podolyak, GF Farrelly, PH Regan, AB Garnsworthy, SJ Steer, M Gorska, J Benlliure, E Casarejos, S Pietri, J Gerl, HJ Wollersheim, R Kumar, F Molina, A Algora, N Alkhomashi, G Benzoni, A Blazhev, P Boutachkov, AM Bruce, L Caceres, IJ Cullen, AMD Bacelar, P Doornenbal, ME Estevez, Y Fujita, W Gelletly, H Geissel, H Grawe, J Grebosz, R Hoischen, I Kojouharov, S Lalkovski, Z Liu, KH Maier, C Mihai, D Muecher, B Rubio, H Schaffner, A Tamii, S Tashenov, JJ Valiente-Dobon, PM Walker, PJ Woods (2009)Proton-hole excitation in the closed shell nucleus Au-205, In: PHYSICS LETTERS B672(2)pp. 116-119 ELSEVIER SCIENCE BV
C. Wheldon, P. M. Walker, P. Chowdhury, I. Shestakova, R. D'Alarcao, I. Ahmad, M. P. Carpenter, D. M. Cullen, R. V. F. Janssens, T. L. Khoo, F. G. Kondev, C. J. Lister, C. J. Pearson, Zs. PodolyàK, D. SeweryniaK, I. Wiedenhoever (2000)Inelastic excitation of new high-spin yrast isomers in 180Ta, In: Physical Review C62(057301)
D. L. Balabanski, K. Vyvey, G. Neyens, N. Coulier, R. Coussement, G. Georgiev, A. Lèpine-Szily, S. Ternier, S. Teughels, M. Mineva, P. M. Walker, P. Blaha, D. Almehed, S. Frauendorf (2001)Static Quadrupole Moment of the Five-Quasiparticle K = 35/2 Isomer in 179W Studied with the Level-Mixing Spectroscopy Method, In: Physical Review Letters86(604)pp. 604-607
P. D. Stevenson, M. P. Brine, Zs. Podolyak, P. H. Regan, P. M. Walker, J. Rikovska Stone (2005)Shape evolution in the neutron-rich tungsten region, In: Physical Review C72(047303)
GA Jones, SJ Williams, PM Walker, Z Podolyak, S Zhu, MP Carpenter, JJ Carroll, RS Chakrawarthy, P Chowdhury, IJ Cullen, GD Dracoulis, AB Garnsworthy, G Hackman, RVF Janssens, TL Khoo, FG Kondev, GJ Lane, Z Liu, D Seweryniak, NJ Thompson (2008)High-spin, multiparticle isomers in (121,123)Sb, In: PHYSICAL REVIEW C77(3)ARTN 0pp. ?-? AMER PHYSICAL SOC
SJ Steer, Z Podolyak, S Pietri, M Gorska, PH Regan, D Rudolph, E Werner-Malento, AB Garnsworthy, R Hoischen, J Gerl, HJ Wollersheim, KH Maier, H Grawe, F Becker, P Bednarczyk, L Caceres, P Doornenbal, H Geissel, J Greabosz, A Kelic, I Kojouharov, N Kurz, F Montes, W Prokopowicz, T Saito, H Schaffner, S Tashenov, A Heinz, M Pfuetzner, T Kurtukian-Nieto, G Benzoni, A Jungclaus, DL Balabanski, C Brandau, BA Brown, AM Bruce, WN Catford, IJ Cullen, Z Dombradi, ME Estevez, W Gelletly, G Ilie, J Jolie, GA Jones, M Kmiecik, FG Kondev, R Kruecken, S Lalkovski, Z Liu, A Maj, S Myalski, S Schwertel, T Shizuma, PM Walker, O Wieland (2008)Single-particle behavior at N=126: Isomeric decays in neutron-rich Pt-204, In: PHYSICAL REVIEW C78(6)ARTN 0pp. ?-? AMER PHYSICAL SOC
CM Petrache, Y Sun, D Bazzacco, S Lunardi, CR Alvarez, G Falconi, R Venturelli, G Maron, DR Napoli, Z Podolyak, PM Walker (1997)High-K bands and oblate-prolate coexistence in Nd-134, In: NUCLEAR PHYSICS A617(2)pp. 249-264 ELSEVIER SCIENCE BV
M Caamãno, PM Walker, PH Regan, CJ Pearson, ZS Podolyak, P Mayet, J Gerl, C Schlegel, M Hellström, M Mlneva, M Pfützner (2001)Isomeric decays in200Pt, In: Acta Physica Polonica B32(3)pp. 763-766

A projectile fragmentation experiment has been performed to populate the neutron-rich A ∼ 190 mass region, approaching the Z = 82, N = 126 closed shell. A previously unreported isomer is found in 200Pt, being the first new example, from fragmentation reactions, of a seniority 4 state established from γ-γ coincidences.

P. M. Walker, G. D. Dracoulis, J. J. Carroll (2001)Interpretation of the excitation and decay of 180Tam through a Kπ = 5+ band, In: Physical Review C64(061302) American Physical Society
S Lalkovski, AM Bruce, AMD Bacelar, M Gorska, S Pietri, Z Podolyak, P Bednarczyk, L Caceres, E Casarejos, IJ Cullen, P Doornenbal, GF Farrelly, AB Garnsworthy, H Geissel, W Gelletly, J Gerl, J Grebosz, C Hinke, G Ilie, D Ivanova, G Jaworski, S Kisyov, I Kojouharov, N Kurz, N Minkov, S Myalski, M Palacz, P Petkov, W Prokopowicz, PH Regan, H Schaffner, S Steer, S Tashenov, PM Walker, HJ Wollersheim (2013)Submicrosecond isomer in Rh-117(45)72 and the role of triaxiality in its electromagnetic decay rate, In: PHYSICAL REVIEW C88(2)ARTN 0pp. ?-? AMER PHYSICAL SOC
M. Rudigier, P. M. Walker, R.L. Canavan, Zs. Podolyak, P. H. Regan, P.-A. Söderström, M. Lebois, J.N. Wilson, N. Jovancevic, A. Blazhev, J. Benito, S. Bottoni, M. Brunet, N. Cieplicka-Orynczak, S. Courtin, D. T. Doherty, L.M. Fraile, K. Hadynska-Klek, M. Heine, Ł.W. Iskra, J. Jolie, V. Karayonchev, A. R. Kennington, P. Koseoglou, G. Lotay, G. Lorusso, M. Nakhostin, C.R. Nita, S. Oberstedt, L. Qi, J.-M. Régis, V. Sánchez-Tembleque, R. Shearman, W. Witt, V. Vedia, K.O. Zell (2020)Multi-quasiparticle sub-nanosecond isomers in 178W, In: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics801135140 Elsevier

We report on the first measurement of the half-lives of and four-quasiparticle states in the even-even nucleus 178W. The sub-nanosecond half-lives were measured by applying the centroid shift method to data taken with LaBr3(Ce) scintillator detectors of the NuBall array at the ALTO facility in Orsay, France. The half-lives of these states only became experimentally accessible by the combination of several experimental techniques - scintillator fast timing, isomer spectroscopy with a pulsed beam, and the event-by-event calorimetry information provided by the NuBall array. The measured half-lives are and for the and states, respectively. The decay transitions include weakly hindered E1 and E2 branches directly to the ground-state band, bypassing the two-quasiparticle states. This is the first such observation for an E1 transition. The interpretation of the small hindrance hinges on mixing between the ground-state band and the t-band.

J Sethi, R Palit, S Saha, T Trivedi, R Donthi, S Jadhav, HC Jain, BS Naidu, GH Bhat, JA Sheikh, P Datta, JJ Carroll, MS Litz, S Chattopadhyay, U Garg, S Karamian, S Kumar, D Mehta, S Sihotra, Z Naik, PM Walker (2013)Structure of nearly degenerate dipole bands in Ag, In: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics725(1-3)pp. 85-91

The high spin negative parity states of Ag have been investigated with the B+Mo reaction at 39 MeV beam energy using the INGA facility at TIFR, Mumbai. From the γ-γ coincidence analysis, an excited negative parity band has been established and found to be nearly degenerate with the ground state band. The spin and parity of the levels are assigned using angular correlation and polarization measurements. This pair of degenerate bands in Ag is studied using the recently developed microscopic triaxial projected shell model approach. The observed energy levels and the ratio of the electromagnetic transition probabilities of these bands in this isotope are well reproduced by the present model. Further, it is shown that the partner band has a different quasiparticle structure as compared to the yrast band. © 2013 Elsevier B.V.

PE Garrett, CE Svensson, C Andreoiu, D Bandyopadhyay, P Finlay, GF Grinyer, B Hyland, E Illes, AA Phillips, MA Schumaker, JJ Valiente-dobón, J Wong, GC Ball, G Hackman, A Andreyev, S Chan, H Coombes, R Churchman, RS Chakrawarthy, AC Morton, CJ Pearson, MB Smith, EF Zganjar, SF Ashley, GA Jones, PH Regan, PM Walker, SJ Williams, RAE Austin, JA Becker, WD Kulp, JL Wood, JR Leslie, C Mattoon, F Sarazin, JJ Ressler, J Schwarzenberg, JC Waddington, LM Watters (2006)Gamma-ray spectroscopy at TRIUMF-ISAC, In: AIP Conference Proceedings819pp. 249-253

The 8π spectrometer at TRIUMF-ISAC consists of 20 Compton-suppressed germanium detectors and various auxiliary devices. The Ge array, once used for studies of nuclei at high angular momentum, has been transformed into the world's most powerful device dedicated to radioactive-decay studies. Many improvements in the spectrometer have been made, including a high-throughput data acquisition system, installation of a moving tape collector, incorporation of an array of 20 plastic scintillators for β-particle tagging, 5 Si(Li) detectors for conversion electrons, and 10 BaF detectors for fast-lifetime measurements. Experiments can be performed where data from all detectors are collected simultaneously, resulting in a very detailed view of the nucleus through radioactive decay. A number of experimental programmes have been launched that take advantage of the versatility of the spectrometer, and the intense beams available at TRIUMF-ISAC. © 2006 American Institute of Physics.

F. Sarazin, J. S. Al-Khalili, G. C. Ball, G. Hackman, P. M. Walker, R. A. E. Austin, B. Eshpeter, P. Finlay, P. E. Garrett, G. F. Grinyer, K. A. Koopmans, W. D. Kulp, J. R. Leslie, D. Melconian, C. J. Osborne, M. A. Schumaker, H. C. Scraggs, J. Schwarzenberg, M. B. Smith, C. E. Svensson, J. C. Waddington, J. L. Wood (2004)Halo neutrons and the beta decay of 11Li, In: Physical Review C70(031302)
B Sun, F Bosch, D Boutin, C Brandau, L Chen, C Dimopoulou, B Fabian, H Geissel, R Knoebel, C Kozhuharov, J Kurcewicz, SA Litvinov, YA Litvinov, J Meng, G Muenzenberg, C Nociforo, F Nolden, WR Plass, C Scheidenberger, M Steck, PM Walker, H Weick, N Winckler, M Winkler (2010)Precise measurement of nuclear isomers in the storage ring at GSI, In: NUCLEAR PHYSICS A834(1-4)pp. 476C-478C
G. A. Jones, S. J. Williams, P. M. Walker, Zs. Podolyák, S. Zhu, M. P. Carpenter, J. J. Carroll, R. S. Chakrawarthy, P. Chowdhury, I. J. Cullen, G. D. Dracoulis, A. B. Garnsworthy, G. Hackman, R. V. F. Janssens, T. L. Khoo, F. G. Kondev, G. J. Lane, Z. Liu, D. Seweryniak, N. J. Thompson (2008)High-spin, multiparticle isomers in 121,123Sb, In: Physical Review C77(034311)
I. Shestakova, G. Mukherjee, P. Chowdhury, R. D'Alarcao, C. J. Pearson, Zs. Podolyák, P. M. Walker, C. Wheldon, D. M. Cullen, I. Ahmad, M. P. Carpenter, R. V. F. Janssens, T. L. Khoo, F. G. Kondev, C. J. Lister, D. SeweryniaK, I. Wiedenhoever (2001)Yrast three-quasiparticle K isomers in neutron-rich 181Hf, In: Physical Review C64(054307)
Z Podolyak, J Gerl, M Hellstrom, F Becker, KA Gladnishki, M Gorska, A Kelic, Y Kopatch, S Mandal, PH Regan, KH Schmidt, PM Walker, HJ Wollersheim, A Banu, G Benzoni, H Boardman, E Casarejos, J Ekman, H Geissel, H Grawe, D Hohn, I Kojouharov, J Leske, R Lozeva, MN Mineva, G Neyens, RD Page, CJ Pearson, M Portillo, D Rudolph, N Saito, H Schaffner, D Sohler, K Summerer, JJ Valiente-Dobon, C Wheldon, H Weick, M Winkler (2006)High angular momentum states populated in fragmentation reactions, In: PHYSICS LETTERS B632(2-3)pp. 203-206 ELSEVIER SCIENCE BV
MW Reed, PM Walker, IJ Cullen, AY Deo, RS Kempley, TPD Swan, YA Litvinov, F Bosch, C Brandau, D Shubina, N Winckler, YA Litvinov, K Blaum, C Dimopoulou, F Farinon, H Geissel, M Heil, R Knöbel, C Kozhuharov, J Kurcewicz, N Kuzminchuk, S Litvinov, C Nociforo, F Nolden, A Prochazka, C Scheidenberger, M Steck, T Stöhlker, B Sun, H Weick, N Winckler, M Winkler, C Brandau, JJ Carroll, DM Cullen, B Detwiler, G Trees, GD Dracoulis, H Geissel, E Haettner, WR Pla, C Scheidenberger, Z Liu, PJ Woods, R Mao, T Stöhlker, T Yamaguchi (2012)Technique for resolving low-lying isomers in the experimental storage ring (ESR) and the occurrence of an isomeric state in Re, In: Journal of Physics: Conference Series381(1) IOP

A recent experiment using projectile fragmentation of a Au beam on a Be target, combined with the fragment recoil separator and experimental storage ring at ring at GSI, has uncovered an isomeric state in Re at 267(10) keV with a half-life of ∼60 s. The data analysis technique used to resolve the isomeric state from the ground state is discussed. © Published under licence by IOP Publishing Ltd.

AM Bruce, AMD Bacelar, G Benzoni, A Gottardo, R Nicolini, E Sahin, A Gadea, A Algora, M Górska, S Pietri, P Boutachkov, ML Cortés, C Domingo-Prado, F Farinon, H Geissel, J Gerl, N Goel, E Gregor, T Haberman, R Hoischen, I Kojouharov, N Kurz, C Nociforo, A Prochazka, W Prokopowicz, H Schaffner, A Sharma, H Weick, H-J Wollersheim, JJ Valiente-Dobón, D Mengoni, Z Podolyák, N Al-Dahan, N Alkhomashi, M Bowry, M Bunce, AY Deo, GF Farrelly, PH Regan, PM Walker, JA Alcántara-Núñez, Y Ayyad, PRP Allegro, E Casarejos, M Doncel, K Eppinger, S Klupp, K Steiger, J Grȩbosz, D Rudolph, R Janik, B Sitar, P Strmen, I Szarka, S Lunardi, R Menegazzo, S Mandal, D Siwal, F Naqvi, T Pissulla (2012)β decay of Y produced in projectile fission of U, In: Journal of Physics: Conference Series381(1)

The population of Zr following the β decay of Y produced in the projectile fission of U at the GSI facility in Darmstadt, Germany has been studied. Y is known to decay into Zr via two states, one of high spin and the other low spin. These states preferentially populate different levels in the Zr daughter. In this paper the intensities of transitions in Zr observed are compared with those from the decay of the low-spin level studied at the TRISTAN facility at Brookhaven National Laboratory and of the high-spin level studied at the JOSEF separator at the Kernforschungsanlage Jülich. © Published under licence by IOP Publishing Ltd.

S Pietri, PH Regan, Z Podolyak, D Rudolph, S Steer, AB Garnsworthy, E Werner-Malento, R Hoischen, M Gorska, J Gerl, HJ Wollersheim, I Kojouharov, H Schaffner, F Becker, P Bednarczyk, L Caceres, P Doornenbal, H Geissel, J Grebosz, A Kelic, N Kurz, F Montes, W Prokopowicz, T Saito, S Tashenov, A Heinz, M Pfuetzner, T Kurtukian-Nieto, G Benzoni, M Hellstrom, A Jungclaus, J Simpson, L-L Andersson, L Atanasova, D Balabanski, MA Bentley, B Blank, A Blazhev, C Brandau, JR Brown, AM Bruce, F Camera, WN Catford, IJ Cullen, Z Dombradi, E Estevez, C Fahlander, W Gelletly, G Ilie, EK Johansson, J Jolie, GA Jones, M Kmiecik, FG Kondev, S Lalkovski, Z Liu, A Maj, S Myalski, T Shizuma, AJ Simons, S Schwertel, PM Walker, O Wieland (2007)Recent results in fragmentation isomer spectroscopy with rising, In: NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS261(1-2)pp. 1079-1083
PM Walker, PM Walker, FR Xu, HL Liu, FR Xu, Y Sun, HL Liu, Y Sun, HL Liu (2012)On the possibility of enhanced fission stability for broken-pair excitations, In: Journal of Physics G: Nuclear and Particle Physics39(10) Institute of Physics

The fission of high-K, two-quasiparticle isomers is considered, with specific reference to No, No and Fm. The published experimental evidence is discussed in relation to configuration-constrained potential-energy-surface calculations, which suggest that the high-K isomers should be less susceptible to fission than their corresponding ground states. © 2012 IOP Publishing Ltd.

PM Walker (2007)Angular momentum orientation at bandcrossings in rotating nuclei, In: JOURNAL OF PHYSICS G-NUCLEAR AND PARTICLE PHYSICS34(1)pp. 123-127 IOP PUBLISHING LTD
S Mohammadi, Z Podolyák, G De Angelis, M Axiotis, D Bazzacco, PG Bizzeti, F Brandolini, R Broda, D Bucurescu, E Farnea, W Gelletly, A Gadea, M Ionescu-Bujor, A Iordachescu, T Kröll, S Longdown, S Lunardi, N Marginean, T Martinez, NH Medina, B Quintana, PH Regan, B Rubio, CA Ur, JJ Valiente Dobón, PM Walker, YH Zhang (2004)High-spin states populated in deep-inelastic reactions, In: Brazilian Journal of Physics34(3 A)pp. 792-795

High spin states in the neutron rich 188Os and 190Os nuclei have been populated using the 82Se + 192Os deep-inelastic reaction. The level schemes are extended up to spin I ≈21. The observed new structures are tentatively interpreted as fragments of rotational bands built on multi-quasiparticle configurations.

D Rudolph, S Pietri, Z Podolyak, PH Regan, AB Garnsworthy, R Hoischen, SJ Steer, F Becker, P Bednarczyk, L Caceres, P Doornenbal, H Geissel, J Gerl, M Gorska, J Grebosz, A Kelic, I Kojouharov, N Kurz, F Montes, W Prokopowicz, T Saito, H Schaffner, S Tashenov, E Werner-Malento, HJ Wollersheim, L-L Andersson, L Atanasova, DL Balabanski, MA Bentley, G Benzoni, B Blank, A Blazhev, C Brandau, JR Brown, AM Bruce, F Camera, WN Catford, IJ Cullen, Z Dombradi, E Estevez, C Fahlander, W Gelletly, A Heinz, M Hellstrom, G Ilie, EK Johansson, J Jolie, GA Jones, A Jungclaus, M Kmiecik, FG Kondev, T Kurtukian-Nieto, S Lalkovski, Z Liu, A Maj, S Myalski, M Pfutzner, T Shizuma, AJ Simons, S Schwertel, PM Walker, O Wieland (2007)Exciting isomers from the first stopped-beam RISING campaign, In: EUROPEAN PHYSICAL JOURNAL-SPECIAL TOPICS150pp. 173-176
AI Morales, J Benlliure, T Kurtukian-Nieto, K-H Schmidt, S Verma, PH Regan, Z Podolyak, M Gorska, S Pietri, R Kumar, E Casarejos, N Al-Dahan, A Algora, N Alkhomashi, H Alvarez-Pol, G Benzoni, A Blazhev, P Boutachkov, AM Bruce, LS Caceres, IJ Cullen, AMD Bacelar, P Doornenbal, ME Estevez-Aguado, G Farrelly, Y Fujita, AB Garnsworthy, W Gelletly, J Gerl, J Grebosz, R Hoischen, I Kojouharov, N Kurz, S Lalkovski, Z Liu, C Mihai, F Molina, D Muecher, B Rubio, H Shaffner, SJ Steer, A Tamii, S Tashenov, JJ Valiente-Dobon, PM Walker, HJ Wollersheim, PJ Woods (2014)Half-Life Systematics across the N=126 Shell Closure: Role of First-Forbidden Transitions in the beta Decay of Heavy Neutron-Rich Nuclei, In: PHYSICAL REVIEW LETTERS113(2)ARTN 0pp. ?-? AMER PHYSICAL SOC
R. S. Chakrawarthy, P. M. Walker, J. J. Ressler, E. F. Zganjar, G. C. Ball, M. B. Smith, A. N. Andreyev, S. F. Ashley, R. A. E. Austin, D. Bandyopadhyay, J. A. Becker, J. J. Carroll, D. S. Cross, D. Gohlke, J. J. Daoud, P. E. Garrett, G. F. Grinyer, G. Hackman, G. A. Jones, R. Kanungo, W. D. Kulp, Y. Litvinov, A. C. Morton, W. J. Mills, C. J. Pearson, R. Propri, C. E. Svensson, R. Wheeler, S. J. Williams (2006)Kπ = 0+ 2.29 s isomer in neutron-rich 174Tm, In: Physical Review C73(024306)
M Nakhostin, PM Walker (2010)Application of digital zero-crossing technique for neutron-gamma discrimination in liquid organic scintillation detectors, In: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment621(1-3)pp. 498-501 Elsevier

An algorithm for digital implementation of the zero-crossing method for n/γ discrimination in liquid organic scintillators is described. The method exhibits good performance at low energies and requires little computational effort, which makes it suitable for compact real-time neutron detectors.

S Pietri, PH Regan, Z Podolyak, D Rudolph, M Gorska, A Jungclaus, M Pfuetzner, AB Garnsworthy, SJ Steer, L Caceres, E Werner-Malento, R Hoischen, J Gerl, I Kojouharov, H Schaffner, HJ Wollersheim, F Becker, P Bednarczyk, P Doornenbal, H Geissel, J Grebosz, A Kelic, N Kurz, F Montes, W Prokopowicz, T Saito, S Tashenov, A Heinz, T Kurtukian-Nieto, G Benzoni, M Hellstrom, L-L Andersson, L Atanasova, DL Balabanski, MA Bentley, B Blank, A Blazhev, C Brandau, JR Brown, AM Bruce, F Camera, WN Catford, IJ Cullen, Z Dombradi, E Estevez, C Fahlander, W Gelletly, G Ilie, EK Johansson, J Jolie, GA Jones, M Kmiecik, FG Kondev, S Lalkovski, Z Liu, A Maj, S Myalski, T Shizuma, AJ Simons, S Schwertel, PM Walker, O Wieland (2007)First results from the stopped beam isomer rising campaign at GSI, In: ACTA PHYSICA POLONICA B38(4)pp. 1255-1264
M Dasgupta, GD Dracoulis, PM Walker, AP Byrne, T Kibédi, FG Kondev, GJ Lane, PH Regan (2000)Competition between high-K states and rotational structures in 177Ta, In: Physical Review C - Nuclear Physics61(4)pp. 443211-4432133

High-spin states in 177Ta have been studied using the 170Er(11B,4n) reaction. New intrinsic states have been observed corresponding to 3-, 5-, and 7-quasiparticle high-K structures. Rotational bands built on most of the 3-and 5-quasiparticle states and some transitions above the 7-quasiparticle states have been identified. Several isomers have been found, the longest lived being the 49/2-, 7-quasiparticle state with a meanlife of 192 μs. Configurations for the observed intrinsic states have been assigned on the basis of gK values, alignments, and decay properties. While the properties of most of the bands are consistent with their proposed configurations, the behavior of some, including the one built on Kπ = 21/2- 3-quasiparticle isomer, is not well understood. Multiquasiparticle blocking calculations based on the Lipkin-Nogami method, are in good agreement with the excitation energies of the experimentally observed states and all the predicted states close to the yrast line up to spin 49/2 have been observed experimentally. The calculations predict the existence of a 9-quasiparticle 67/2- yrast trap at ∼ 8.5 MeV.

PH Regan, AB Gamsworthy, SJ Steer, S Pletri, Z Podolyak, D Rudolph, M Gorska, L Caceres, E Wemer-Malento, J Gerl, HJ Wollersheim, F Becker, P Bednarczyk, PD Doornenbal, H Geissel, H Grawe, J Grebosz, R Hoischen, A Kelic, I Kojouharov, N Kurz, F Montes, W Prokopowicz, T Saito, H Schaffner, S Tashenov, A Heinz, M Pfuetzner, T Kurtukian-Nieto, G Benzoni, M Hellstroem, A Jungclaus, L-L Andersson, L Atanasova, DL Balabanski, MA Bentley, B Blank, A Blazhev, C Brandau, J Brown, AM Bruce, F Camera, WN Catford, IJ Cullen, Z Dombradi, E Estevez, C Fahlander, W Gelletly, G Ilie, EK Johansson, J Jolie, GA Jones, M Kmiecik, G Kondev, S Lalkovski, Z Liu, A Maj, S Myalski, S Schwertel, T Shizuma, AJ Simons, PM Walker, O Wieland (2007)First results from the stopped RISING campaign at GSI: The mapping of isomeric decays in highly exotic nuclei, In: Six International Conference of the Balkan Physical Union899pp. 19-22
TR Saitoh, N Saitoh-Hashimoto, G Sletten, RA Bark, M Bergström, P Regan, S Törmänen, PG Varmette, PM Walker, C Wheldon (2000)Erratum to "collective and intrinsic structures in 183W" [nucl. Phys. A 660 (1999) 171-196] *, In: Nuclear Physics A669(3-4)pp. 381-406

The structure of 183W has been studied by employing the 176Yb(14C,α 3n) reaction at 68 MeV. Five previously known rotational structure with one-quasiparticle configurations have been extended to higher spin states, and five new rotational bands with three- and five-quasiparticle configurations and a γ-vibration of a one-quasiparticle structure have been newly identified. In the ν7/2-[503] and ν11/2+[615] rotational structures, a signal of an admixture of an octupole- vibrational structure has been observed in their in-band B(M1)/B(E2) ratios and gΚ factors. In the Κπ = 19-M rotational band, a Coriolis effect on the ν1/2-[510] neutron has been identified. In all, 17 Κ-forbidden transitions have been observed. Energies of intrinsic states below 4 MeV have been calculated based on the Blocked BCS theory, and they are used in support of the configuration assignments. © 2000 Elsevier Science B.V. All rights reserved. PACS: 21.10.Re; 21.10.Tg; 23.20.En; 23.20.Lv; 27.70.+q.

YA Litvinov, K Blaum, N Winckler, X Ma, PM Walker (2010)Mass and lifetime measurements of stored exotic nuclei, In: Proceedings of Science

Knowledge of atomic masses is indispensable in nuclear structure and nuclear astrophysics. In the last two decades, majority of experimental data on nuclear masses stems from measurements of stored ions. The ions can be stored at low energies in a Penning trap or at significantly higher energies in a storage ring. In both cases revolution frequencies of ions trapped in a confining magnetic field are determined which enables high-precision mass measurements. In this contribution we sketch the experimental techniques and recent results. Future perspectives at the new generation radioactive beam facilities are outlined. © Copyright owned by the author(s).

P. M. Walker, G. D. Dracoulis, A. P. Byrne, T. Kibédi, A. E. Stuchbery (1994)Kπ= 6+ and 8- Isomer Decays in 172Hf and ΔK = 8 E1 Transition Rates, In: Physical Review C49pp. 1718-1721
F Wang, BH Sun, Z Liu, RD Page, C Qi, C Scholey, SF Ashley, L Bianco, IJ Cullen, IG Darby, S Eeckhaudt, AB Garnsworthy, William Gelletly, MB Gomez-Hornillos, T Grahn, PT Greenlees, DG Jenkins, GA Jones, P Jones, DT Joss, R Julin, S Juutinen, S Ketelhut, S Khan, A Kishada, M Leino, M Niikura, M Nyman, J Pakarinen, S Pietri, Zsolt Podolyak, P Rahkila, S Rigby, J Saren, T Shizuma, J Sorri, S Steer, NJ Thompson, J Uusitalo, Philip Walker, S Williams, HF Zhang, WQ Zhang, L Zhu (2017)Spectroscopic factor and proton formation probability for the d3/2 proton emitter 151mLu, In: Physics Letters B770pp. 83-87 Elsevier

The quenching of the experimental spectroscopic factor for the proton decay of 151mLu from the short-lived d3=2 isomeric state has been a long standing problem. In the present work, the proton energy value and half-life of this isomer were remeasured to be 1295(5) keV and 15.4 0.8 s, respectively, in an experiment at the Accelerator Laboratory of the University of Jyvaskyla. The re ned experimental data can resolve the discrepancy in the spectroscopic factor with the WKB approximation. It is also found that the proton formation probability extracted from the present measurements is much larger than that from the adopted data before, indicating no signi cant hindrance for the proton decay of 151mLu.

G. A. Jones, P. H. Regan, P. M. Walker, Zs. Podolyák, P. D. Stevenson, M. P. Carpenter, J. J. Carroll, R. S. Chakrawarthy, P. Chowdhury, A. B. Garnsworthy, R. V. F. Janssens, T. L. Khoo, F. G. Kondev, G. J. Lane, Z. Liu, D. Seweryniak, N. J. Thompson, S. Zhu, S. J. Williams (2007)Identification of a high-spin isomer in 99Mo, In: Physical Review C76(047303)
K A Gladnishki, Z Podolyak, P H Regan, J Gerl, M Hellstrom, Y Kopatch, S Mandal, M Gorska, R D Page, H J Wollersheim, A Banu, G Benzoni, H Boardman, M La Commara, J Ekman, C Fahlander, H Geissel, H Grawe, E Kaza, A Korgul, M Matos, M N Mineva, C J Pearson, C Plettner, D Rudolph, C Scheidenberger, K H Schmidt, V Shishkin, D Sohler, K Summerer, J J Valiente-Dobon, P M Walker, H Weick, M Winkler, O Yordanov (2004)Angular Momentum Population in the Projectile Fragmentation of U-238 at 750 MeV/nucleon, In: Physical Review C69(2)

A systematic study of the population probabilities of nanosecond and microsecond isomers produced following the projectile fragmentation of U-238 at 750 MeV/nucleon has been undertaken at the SIS/FRS facility at GSI. Approximately 15 isomeric states in neutron-deficient nuclei around A similar to 190 were identified and the corresponding. isomeric ratios determined. The results are compared with a model based on the statistical abrasion-ablation description of relativistic fragmentation and simple assumptions concerning gamma cascades in the final nucleus (sharp cutoff). This model represents an upper limit for the population of isomeric states in relativistic projectile fragmentation. When the decay properties of the states above the isomer are taken into account, as opposed to the sharp cutoff approximation, a good agreement between the experimental and calculated angular momentum population is obtained.

N Al-Dahan, Z Podolyak, PH Regan, M Gorska, H Grawe, KH Maier, J Gerl, SB Pietri, HJ Wollersheim, N Alkhomashi, AY Deo, AMD Bacelar, G Farrelly, SJ Steer, AM Bruce, P Boutachkov, C Domingo-Pardo, A Algora, J Benlliure, A Bracco, E Calore, E Casarejos, IJ Cullen, P Detistov, Z Dombradi, M Doncel, F Farinon, W Gelletly, H Geissel, N Goel, J Grebosz, R Hoischen, I Kojouharov, N Kurz, S Lalkovski, S Leoni, F Molina, D Montanari, AI Morales, A Musumarra, DR Napoli, R Nicolini, C Nociforo, A Prochazka, W Prokopowicz, B Rubio, D Rudolph, H Schaffner, P Strmen, I Szarka, T Swan, JS Thomas, JJ Valiente-Dobon, S Verma, PM Walker, H Weick (2009)Nuclear structure "southeast" of Pb-208: Isomeric states in Hg-208 and Tl-209, In: PHYSICAL REVIEW C80(6)ARTN 0pp. ?-? AMER PHYSICAL SOC
N Cieplicka, B Fornal, KH Maier, B Szpak, R Broda, W Krolas, T Pawlat, J Wrzesinski, RVF Janssens, MP Carpenter, CJ Chiara, CR Hoffman, FG Kondev, T Lauritsen, S Zhu, Z Podolyak, M Bowry, M Bunce, W Gelletly, R Kempley, M Reed, P Regan, P Walker, E Wilson, AY Deo, G Dracoulis, G Lane, C Rodriguez-Triguero (2014)ANGULAR DISTRIBUTIONS OF gamma RAYS FROM Bi-210 PRODUCED IN Pb-208+Pb-208 DEEP-INELASTIC REACTIONS, In: ACTA PHYSICA POLONICA B45(2)pp. 205-210
WN Catford, S Mohammadi, PH Regan, CS Purry, W Gelletly, PM Walker, GJ Gyapong, J Simpson, DD Warner, T Davinson, R Neal, RD Page, AC Shotter, IM Hibbert, R Wadsworth, SA Forbes, AM Bruce, C Thwaites, P Thirolf, P VanDuppen, W Galster, A Ninane, J Vervier, P Decrock, M Huyse, J Szerypo, J Wauters (1997)High resolution gamma-ray spectroscopy with a radioactive beam, In: NUCLEAR PHYSICS A616(1-2)pp. C303-C310
Y Sun, PM Walker, F-R Xu, Y-X Liu (2008)Rotation-driven prolate-to-oblate shape phase transition in W-190: A projected shell model study, In: PHYSICS LETTERS B659(1-2)pp. 165-169 ELSEVIER SCIENCE BV
D. T. Scholes, D. M. Cullen, F. G. Kondev, R. V. F. Janssens, M. P. Carpenter, D. J. Hartley, M. K. Djongolov, G. Sletten, G. Hagemann, C. Wheldon, P. M. Walker, K. Abu Saleem, I. Ahmad, D. L. Balabanski, P. Chowdhury, M. Danchev, G. D. Dracoulis, H. M. El-Masri, J. Goon, A. Heinz, R. A. Kaye, T. L. Khoo, T. Lauritsen, C. J. Lister, E. F. Moore, L. L. Riedinger, M.A. Riley, M. Seweryniak, I. Shestakova, I. Wiedenhöver, O. Zeidan, Jing-ye Zhang (2004)Highly deformed Bands in 175Hf, In: Physical Review C70(054314)
J. N. Orce, A. M. Bruce, A. Emmanouilidis, A. P. Byrne, G. D. Dracoulis, T. Kibédi, M. Caamano, H. El-Masri, C. J. Pearson, Zs. Podolyák, P. D. Stevenson, P. M. Walker, F. R. Xu, D. M. Cullen, C. Wheldon (2006)Shape-driving effects in the triaxial nucleus, 128Xe, In: Physical Review C74(034318)
PM Walker, N Minkov (2010)High-K isomers as probes of octupole collectivity in heavy nuclei, In: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics694(2)pp. 119-122 Elsevier

The influence of the octupole deformation on the structure of high-K isomeric states in the region of heavy even-even actinide nuclei is studied through a reflection asymmetric deformed shell model (DSM). Two-quasiparticle states with high-K val- ues are constructed by taking into account the pairing effect through a DSM+BCS procedure with constant pairing interaction. The behaviour of two-quasiparticle ener- gies and magnetic dipole moments of K = 6+, 6− and 8− configurations, applicable to mass numbers in the range A = 234 − 252, was examined over a wide range of quadrupole and octupole deformations. A pronounced sensitivity of the magnetic moments to the octupole deformation is found. The result suggests a possibly im- portant role for high-K isomers in determining the degree of octupole deformation in heavy actinide nuclei.

X-Y Wu, S Ghorui, L-J Wang, Y Sun, M Guidry, Philip Walker (2017)Systematic study of multi-quasiparticle K-isomeric bands in tungsten isotopes by the extended projected shell model, In: Physical Review C95(6)064314 American Physical Society

Background: The interplay between collective and single-particle degrees of freedom is an important structure aspect to study. The nuclei in theA ≈ 180 mass region are often denoted as good examples to study such problems because these nuclei are known to exhibit many rotational bands based on multi-quasiparticle K isomers. Purpose: A large set of high-quality experimental data on high-K isomeric states in the A ≈ 180 mass region has accumulated. A systematic description of them is a theoretical challenge as it requires a method going beyond the usual mean field with multi-quasiparticle configurations built in the shell-model basis. The K-isomer data provide an ideal testing ground for theoretical models. Method: The recently extended projected shell model (PSM) by the Pfaffian method is employed with a sufficiently large configuration space including up to 10 quasiparticles. The restoration of rotational symmetry which is broken in the deformed mean field is obtained by means of angular-momentum projection. With axial symmetry in the basis deformation, each multi-quasiparticle state, classified by a K quantum number, represents the major component of a rotational K band. Shell-model diagonalization in such a projected basis defines the K mixing, which is the key ingredient of the present method. Results: Quasiparticle structure and rotational properties of high-K isomers in even-even neutron-rich 174−186W isotopes are described. The rotational evolution of the yrast and near-yrast bands is discussed with successive band crossings. Multi-quasiparticle K isomers and associated rotational bands in each W isotope are studied with detailed quasiparticle configurations given. Electromagnetic transition properties are also studied and the calculated B(E2), B(M1), and g-factors are compared with experiment if data exist. Conclusions: Many nuclei of the A ≈ 180 mass region exhibit properties of an axially symmetric shape and K is approximately a good quantum number. For such nuclei, the extended PSM assuming an axially symmetric basis but including K mixing through diagonalization of the two-body Hamiltonian is an appropriate method to study multi-quasiparticle K isomers and K violations in these states. For special examples where one finds highly K-forbidden transitions the present model needs to be further improved.

J Sethi, R Palit, JJ Carroll, S Karamian, S Saha, S Biswas, Z Naik, T Trivedi, MS Litz, P Datta, S Chattopadhyay, R Donthi, U Garg, S Jadhav, HC Jain, S Kumar, D Mehta, BS Naidu, GH Bhat, JA Sheikh, S Sihotra, PM Walker (2015)SPECTROSCOPY OF THE LOW-LYING STATES NEAR THE HIGH SPIN ISOMER IN Ag-108, In: ACTA PHYSICA POLONICA B46(3)pp. 703-707 WYDAWNICTWO UNIWERSYTETU JAGIELLONSKIEGO

A comprehensive study of the low-lying states of 108Ag, near the isomeric state at Ei = 110 keV with Jπ = 6+ and T1/2 = 438 y, has been presented. Spectroscopy of these states has been carried out using the reaction 100Mo(11B, 3nγ)108Ag at 39 MeV beam energy using INGA. The multipolarities and electromagnetic nature of the transitions have been assigned based on the angular correlation and polarization measurements. The experimentally identified states have been compared to the results of the Projected Hartree-Fock calculations to understand the configurations involved in these states.

Mohammad Nakhostin, Philip Walker, Paul Sellin (2010)Time walk correction of CdTe detectors using depth sensing technique, In: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment621(1-3)pp. 506-512 Elsevier

A digital timing method aiming to minimize the time walk caused by the depth-dependent pulse shape variations in CdTe detectors has been developed. Detector pulses are digitized at the preamplifier stage and a full digital process is carried out to deduce and correct the time walk according to the interaction depth. A time resolution of 6.52 ns FWHM at an energy threshold of 150 keV with a CdTe detector (10×10×1 mm3) is achieved, which is close to the intrinsic resolution of the detector. The method improves the time resolution with no loss of detection efficiency and it is easy to implement. It is confirmed that the slow mobility and the short lifetime of the holes are major obstacles for further improvement in the timing performance of the CdTe detectors. The method is applicable to any semiconductor detector.

MM Rajabali, ML Bissell, S De Schepper, K Dewolf, G Neyens, J Papuga, KM Lynch, J Billowes, KT Flanagan, TJ Procter, AJ Smith, TE Cocolios, F Le Blanc, I Matea, D Verney, BA Marsh, S Rothe, PJR Mason, PM Walker, RT Wood, K Wendt, GS Simpson, HH Stroke (2013)A dedicated decay-spectroscopy station for the collinear resonance ionization experiment at ISOLDE, In: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment707pp. 35-39 Elsevier

A new decay-spectroscopy station (DSS) has been developed to be coupled to the collinear resonance ionization spectroscopy (CRIS) beam line at CERN-ISOLDE. The system uses a rotatable wheel with ten 20μg/ carbon foils as beam implantation sites for the efficient measurement of charged decay products. Silicon detectors are placed on either side of the carbon foil in an optimal geometry to cover a large solid angle for detecting these charged particles. In addition to the silicon detectors at the on-beam axis position, a second pair of off-beam axis detectors are placed at the wheel position 108° away, allowing longer-lived species to be studied. Up to three high purity germanium detectors can be placed around the chamber for particle-gamma correlated measurement. The radioactive beam is transported through the CRIS beam line before implantation into a carbon foil at the DSS. All materials used in the DSS are UHV-compatible to maintain high vacuum conditions required by the CRIS beam line. This paper describes the DSS and presents the first data collected at the setup during the commissioning run with Fr. © 2012 Elsevier B.V.

MB Smith, PM Walker, RS Chakrawarthy, RAE Austin, GC Ball, JJ Carroll, E Cunningham, P Finlay, PE Garrett, GF Grinyer, G Hackman, B Hyland, K Koopmans, WD Kulp, JR Leslie, AA Phillips, R Propri, PH Regan, F Sarazin, MA Schumaker, HC Scraggs, T Shizuma, CE Svensson, J von Schwarzenberg, JC Waddington, D Ward, JL Wood, B Washbrook, EF Zganjar (2004)Studies of high-K isomers at TRIUMF-ISAC, In: Nuclear Physics A746(1-4 SP)

The properties of high-K isomers have been investigated by measuring γ rays from a source of the 31-year 178Hfm2 isomer and from the decay of implanted 178,179Lu beams. Low-intensity transitions have been identified in the decay of 178Hfm2, demonstrating a consistent extension of K-hindrance systematics to higher multipolarities, and elucidating the spin-dependence of the mixing between the two Kπ = 8- bands. A search is underway for new isomers in 178,179Lu and the preliminary results of the analysis are reported. © 2004 Elsevier B.V. All rights reserved.

Z Podolyak, PM Walker, DM Cullen, GD Dracoulis, P Fallon, B Fairchild, K Hauschild, AO Macchiavelli, DP McNabb, A Savelius, D Ward, C Wheldon (2000)Search for very long-lived isomers in the hafnium-tungsten region, In: PHYSICAL REVIEW C62(3)ARTN 03430 AMERICAN PHYSICAL SOC
AB Garnsworthy, PH Regan, S Pietri, D Rudolph, L Caceres, M Gorska, Z Podolyak, SJ Steer, A Heinz, F Becker, P Bednarczyk, P Doornenbal, H Geissel, J Gerl, H Grawe, J Grebosz, A Kelic, I Kojouharov, N Kurz, F Montes, W Prokopwicz, T Saito, H Schaffner, S Tachenov, E Werner-Malento, HJ Wollersheim, G Benzoni, B Blank, C Brandau, AM Bruce, F Camera, WN Catford, IJ Cullen, Z Dombradi, E Estevez, W Gelletly, R Hoischen, G Ilie, J Jolie, GA Jones, A Jungclaus, M Kmiecik, FG Kondev, T Kurtukian-Nieto, S Lalkovski, Z Liu, A Maj, S Myalski, M Pfutzner, T Shizuma, AJ Simons, S Schwertel, PM Walker, O Wieland (2007)Isomeric states in the light Tc isotopes, In: ACTA PHYSICA POLONICA B38(4)pp. 1265-1269
A. M. Bruce, A. P. Byrne, G. D. Dracoulis, W. Gelletly, T. Kibedi, F. G. Kondev, C. S. Purry, P. H. Regan, C. Thwaites, P. M. Walker (1997)Systematics of Kπ = 8- isomers in N = 74 nuclei, In: Physical Review C55(620)pp. 620-624
T Alexander, Z Podolyak, ML Cortes, J Gerl, D Rudolph, LG Sarmiento, F Ameil, T Arici, D Bazzacco, C Bauer, MA Bentley, A Blazhev, M Bowry, P Boutachkov, R Carroll, C Fahlander, A Gadea, J Gellanki, W Gelletly, A Givechev, N Goel, P Golubev, M Gorska, A Gottardo, E Gregor, G Guastalla, T Habermann, M Hackstein, A Jungclaus, I Kojouharov, W Korten, S Kumar, N Kurz, N Lalovic, M Lettmann, C Lizarazo, C Louchart, S Mandal, E Merchan, C Michelagnoli, T Moeller, K Moschner, Z Patel, N Pietralla, S Pietri, D Ralet, M Reese, PH Regan, P Reiter, H Schaffner, P Singh, C Stahl, R Stegmann, O Stezowksi, J Taprogge, P Thoele, PM Walker, O Wieland, A Wendt, E Wilson, R Wood, H-J Wollersheim (2015)ISOMERIC RATIOS IN Hg-206, In: ACTA PHYSICA POLONICA B46(3)pp. 601-605 WYDAWNICTWO UNIWERSYTETU JAGIELLONSKIEGO

206Hg was populated in the fragmentation of an E∕A = 1 GeV 208Pb beam at GSI. It was part of a campaign to study nuclei around 208Pb via relativistic Coulomb excitation. The observation of the known isomeric states confirmed the identification of the fragmentation products. The isomeric decays were also used to prove that the correlations between beam identification detectors and the AGATA γ-ray tracking array worked properly and that the tracking efficiency was independent of the time relative to the prompt flash.

H Mach, PM Walker, R Julin, M Leino, S Juutinen, M Stanoiu, Z Podolyak, R Wood, AM Bruce, T Back, JA Cameron, B Cederwall, J Ekman, B Fogelberg, PT Greenless, M Hellstrom, P Jones, W Klamra, K Lagergren, AP Leppanen, P Nieminen, R Orlandi, J Pakarinen, P Rahkila, D Rudolph, G Simpson, J Uusitalo, C Wheldon (2005)Application of ultra-fast timing techniques to the study of exotic and weakly produced nuclei, In: JOURNAL OF PHYSICS G-NUCLEAR AND PARTICLE PHYSICS31(10)pp. S1421-S1426
AB Garnsworthy, PH Regan, L Caceres, S Pietri, Y Sun, D Rudolph, M Gorska, Z Podolyak, SJ Steer, R Hoischen, A Heinz, F Becker, P Bednarczyk, P Doornenbal, H Geissel, J Gerl, H Grawe, J Grebosz, A Kelic, I Kojouharov, N Kurz, F Montes, W Prokopowicz, T Saito, H Schaffner, S Tachenov, E Werner-Malento, HJ Wollersheim, G Benzoni, BB Blank, C Brandau, AM Bruce, F Camera, WN Catford, IJ Cullen, Z Dombradi, E Estevez, W Gelletly, G Ilie, J Jolie, GA Jones, A Jungclaus, M Kmiecik, FG Kondev, T Kurtukian-Nieto, S Lalkovski, Z Liu, A Maj, S Myalski, M Pfutzner, S Schwertel, T Shizuma, AJ Simons, PM Walker, O Wielandi, FR Xu (2008)Neutron-proton pairing competition in N = Z nuclei: Metastable state decays in the proton dripline nuclei Nb-82(41) and Tc-86(43), In: PHYSICS LETTERS B660(4)pp. 326-330 ELSEVIER SCIENCE BV
Z Patel, Philip Walker, Zsolt Podolyak, Patrick Regan, Thomas Berry, P-A Söderström, H Watanabe, E Ideguchi, GS Simpson, S Nishimura, Q Wu, FR Xu, F Browne, P Doornenbal, G Lorusso, S Rice, L Sinclair, T Sumikama, J Wu, ZY Xu, N Aoi, H Baba, FL Bello Garrote, G Benzoni, R Daido, Zs Dombrádi, Y Fang, N Fukuda, G Gey, S Go, A Gottardo, N Inabe, T Isobe, D Kameda, K Kobayashi, M Kobayashi, T Komatsubara, I Kojouharov, T Kubo, N Kurz, I Kuti, Z Li, M Matsushita, S Michimasa, C-B Moon, H Nishibata, I Nishizuka, A Odahara, E Sahin, H Sakurai, H Schaffner, H Suzuki, H Takeda, M Tanaka, J Taprogge, Zs Vajta, A Yagi, R Yokoyama (2017)Isomer-delayed -ray spectroscopy of A = 159 - 164 midshell nuclei and the variation of K-forbidden E1 transition hindrance factors, In: Physical Review C96(3)034305 American Physical Society

Excited states have been studied in ____iso{159}{Sm}, ____iso{161}{Sm}, ____iso{162}{Sm} (Z~=~62), ____iso{163}{Eu} (Z~=~63), and ____iso{164}{Gd} (Z~=~64), populated by isomeric decay following 238U projectile fission at RIBF, RIKEN. The isomer half-lives range from 50 ns to 2.6 ____mus. In comparison with other published data, revised interpretations are proposed for ____iso{159}{Sm} and ____iso{163}{Eu}. The first data for excited states in ____iso{161}{Sm} are presented, where a 2.6 ____mus isomer is assigned a three-quasiparticle, K^____pi = 17/2^- structure. The interpretation is supported by multi-quasiparticle Nilsson-BCS calculations, including the blocking of pairing correlations. A consistent set of reduced E1 hindrance factors is obtained. Limited evidence is also reported for isomeric decay in 163Sm, 164Eu and 165Eu.

Z Podolyak, S Mohammadi, G De Angelis, YH Zhang, M Axiotis, D Bazzacco, PG Bizzeti, F Brandolini, R Broda, D Bucurescu, E Farnea, W Gelletly, A Gadea, M Ionescu-Bujor, A Iordachescu, T Kroll, SD Langdown, S Lunardi, N Marginean, T Martinez, NH Medina, B Quintana, PH Regan, B Rubio, CA Ur, JJ Valiente-Dobon, PM Walker (2004)Structure of neutron-rich nuclei from deep-inelastic reactions, In: INTERNATIONAL JOURNAL OF MODERN PHYSICS E-NUCLEAR PHYSICS13(1)pp. 123-126
GA Jones, Z Podolyak, PM Walker, PH Regan, G de Angelis, M Axiotis, D Bazzacco, PG Bizzeti, F Brandolini, R Broda, D Bucurescu, E Farnea, W Gelletly, A Gadea, M Ionescu-Bujor, A Iordachescu, T Kroll, SD Langdown, S Lunardi, N Marginean, T Martinez, NH Medina, B Quintana, B Rubio, CA Ur, JJ Valiente-Dobon, SJ Williams, YH Zhang (2005)Population of yrast states in Os-191 using deep-inelastic reactions, In: JOURNAL OF PHYSICS G-NUCLEAR AND PARTICLE PHYSICS31(10)pp. S1891-S1894
L Chen, WR Plaß, H Geissel, R Knöbel, C Kozhuharov, YA Litvinov, Z Patyk, C Scheidenberger, K Siegień-Iwaniuk, B Sun, H Weick, K Beckert, P Beller, F Bosch, D Boutin, L Caceres, JJ Carroll, DM Cullen, IJ Cullen, B Franzke, J Gerl, M Górska, GA Jones, A Kishada, J Kurcewicz, SA Litvinov, Z Liu, S Mandal, F Montes, G Münzenberg, F Nolden, T Ohtsubo, Z Podolyák, R Propri, S Rigby, N Saito, T Saito, M Shindo, M Steck, P Ugorowski, PM Walker, S Williams, M Winkler, H-J Wollersheim, T Yamaguchi (2010)Discovery and investigation of heavy neutron-rich isotopes with time-resolved Schottky spectrometry in the element range from thallium to actinium, In: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics691(6)pp. 234-237 Elsevier

238U projectile fragments have been created at the entrance of the fragment separator FRS, spatially separated in flight within 0.45 μs and injected into the storage-cooler ring ESR at 7.9 Tm corresponding to about 70% light velocity. Accurate new mass values and lifetime information of the stored exotic nuclei in the element range from platinum to uranium have been obtained with single-particle Schottky spectrometry. In this experiment the new isotopes of 236Ac, 224At, 221Po, 222Po, and 213Tl were discovered. The isotopes were unambiguously identified and their masses measured. In addition, the time-correlated data have provided information on the lifetime of the new nuclides. The discovery of isotopes along with accurate mass measurement has been achieved for the first time at the FRS-ESR facility. The results will contribute to the knowledge of the decay products from the r-process nuclei and enable a crucial test of the predictive power of modern nuclear mass and half-life models.

G Mukherjee, P Chowdhury, FG Kondev, PM Walker, GD Dracoulis, R D'Alarcao, I Shestakova, K Abu Saleem, I Ahmad, MP Carpenter (2010)K-hindered decay of a six-quasiparticle isomer in Hf176, In: Physical Review C - Nuclear Physics82(5)054316 American Physical Society
Z Podolyak, SJ Steer, S Pietri, M Gorska, PH Regan, D Rudolph, AB Garnsworthy, R Hoischen, J Gerl, HJ Wollersheim, H Grawe, KH Maier, F Becker, P Bednarczyk, L Caceres, P Doornenbal, H Geissel, J Grebosz, A Kelic, I Kojouharov, N Kurz, F Montes, W Prokopowicz, T Saito, H Schaffner, S Tashenov, A Heinz, T Kurtukian-Nieto, G Benzoni, M Pfuetzner, A Jungclaus, DL Balabanski, C Brandau, BA Brown, AM Bruce, WN Catford, IJ Cullen, Z Dombradi, ME Estevez, W Gelletly, G Ilie, J Jolie, GA Jones, M Kmiecik, FG Kondev, R Kruecken, S Lalkovski, Z Liu, A Maj, S Myalski, S Schwertel, T Shizuma, PM Walker, E Werner-Malento, O Wieland (2009)Structure of neutron-rich nuclei around the N=126 closed shell; the yrast structure of Au-205(126) up to spin-parity I-pi = (19/2(+)), In: EUROPEAN PHYSICAL JOURNAL A42(3)pp. 489-493
T. A. Berry, Zs. Podolyak, R. J. Carroll, R. Lică, B. A. Brown, H. Grawe, Ch. Sotty, N. K. Timofeyuk, T. Alexander, A. N. Andreyev, S. Ansari, M. J. G. Borge, M. Brunet, J. R. Cresswell, C. Fahlander, L. M. Fraile, H. O. U. Fynbo, E. Gamba, W. Gelletly, R.-B. Gerst, M. Górska, A. Gredley, P. Greenlees, L. J. Harkness-Brennan, M. Huyse, S. M. Judge, D. S. Judson, J. Konki, M. Kowalska, J. Kurcewicz, I. Kuti, S. Lalkovski, I. Lazarus, M. Lund, M. Madurga, N. Mărginean, R. Mărginean, I. Marroquin, C. Mihai, R. E. Mihai, E. Nácher, A. Negret, S. Nae, C. Niţă, S. Pascu, R. D. Page, Z. Patel, A. Perea, J. Phrompao, M. Piersa, V. Pucknell, P. Rahkila, E. Rapisarda, P. H. Regan, F. Rotaru, M. Rudigier, C. M. Shand, R. Shearman, E. C. Simpson, S. Stegemann, T. Stora, O. Tengblad, A. Turturica, P. Van Duppen, V. Vedia, P. M. Walker, N. Warr, F. P. Wearing, H. De Witte (2020)Octupole states in 207Tl studied through β decay, In: Physical Review C101(5)054311 American Physical Society

The β decay of 207Hg into the single-proton-hole nucleus 207Tl has been studied through γ-ray spectroscopy at the ISOLDE Decay Station (IDS) with the aim of identifying states resulting from coupling of the πs−11/2, πd−13/2, and πh−111/2 shell model orbitals to the collective octupole vibration. Twenty-two states were observed lying between 2.6 and 4.0 MeV, eleven of which were observed for the first time, and 78 new transitions were placed. Two octupole states (s1/2-coupled) are identified and three more states (d3/2-coupled) are tentatively assigned using spin-parity inferences, while further h11/2-coupled states may also have been observed for the first time. Comparisons are made with state-of-the-art large-scale shell model calculations and previous observations made in this region, and systematic underestimation of the energy of the octupole vibrational states is noted. We suggest that in order to resolve the difference in predicted energies for collective and noncollective t=1 states (t is the number of nucleons breaking the 208Pb core), the effect of t=2 mixing may be reduced for octupole-coupled states. The inclusion of mixing with t=0,2,3 excitations is necessary to replicate all t=1 state energies accurately.

HM El-Masri, PM Walker, Z Podolyak, M Caamano, GD Dracoulis, AP Byrne, T Kibedi, AM Baxter, J Hazel, AM Bruce, JN Orce, A Emmanoulidis, DM Cullen, C Wheldon (2003)High-K states in Re-180, In: ACTA PHYSICA POLONICA B34(4)pp. 2301-2304
M Caamano, PM Walker, PH Regan, M Pfutzner, Z Podolyak, J Gerl, M Hellstrom, P Mayet, MN Mineva, A Aprahamian, J Benlliure, AM Bruce, PA Butler, DC Gil, DM Cullen, J Doring, T Enqvist, C Fox, JG Narro, H Geissel, W Gelletly, J Giovinazzo, M Gorska, H Grawe, R Grzywacz, A Kleinbohl, W Korten, M Lewitowicz, R Lucas, H Mach, CD O'Leary, F De Oliveira, CJ Pearson, F Rejmund, M Rejmund, M Sawicka, H Schaffner, C Schlegel, K Schmidt, KH Schmidt, PD Stevenson, C Theisen, F Vives, DD Warner, C Wheldon, HJ Wollersheim, S Wooding, F Xu, O Yordanov (2005)Isomers in neutron-rich A approximate to 190 nuclides from Pb-208 fragmentation, In: EUROPEAN PHYSICAL JOURNAL A23(2)pp. 201-215 SPRINGER
S Myalski, A Maj, Z Podolyak, F Becker, P Bednarczyk, G Benzoni, B Blank, C Brandau, AM Bruce, L Caceres, F Camera, WN Catford, IJ Cullen, Z Dombradi, P Doornenbal, E Estevez, AB Garnsworthy, H Geissel, W Gelletly, J Gerl, M Corska, H Grawe, J Grebosz, A Heinz, R Hoischen, G Ilie, GA Jones, A Jungclaus, A Kelic, M Kmiecik, I Kojouharov, FG Kondev, T Kurtukian-Nieto, N Kurz, S Lalkovski, Z Liu, F Montes, M Pfuetzner, S Pietri, W Prokopowicz, PH Regan, D Rudolph, T Saito, H Schaffner, S Schwertel, T Shizuma, AJ Simon, SJ Steer, S Tashenov, PM Walker, E Werner-Malento, O Wieland, HJ Wollersheim (2009)ISOMERIC RATIOS FOR NUCLEI WITH Z=62-67 AND A=142-152 PRODUCED IN THE RELATIVISTIC FRAGMENTATION OF Pb-208, In: ACTA PHYSICA POLONICA B40(3)pp. 879-883
T. Shizuma, P. D. Stevenson, P. M. Walker, Y. Toh, T. Hayakawa, M. Oshima, K. Furuno, T. Komatsubar (2002)High-K negative parity states in 184Os, In: Physical Review C65(064310)
X Chen, MS Sanjari, P Hülsmann, Y Litvinov, F Nolden, J Piotrowski, M Steck, T Stöhlker, Philip Walker (2016)Intensity-sensitive and position-resolving cavity for heavy-ion storage rings, In: Nuclear Inst. and Methods in Physics Research, A826pp. 39-47 Elsevier

A heavy-ion storage ring can be adapted for use as an isochronous mass spectrometer if the ion velocity matches the transition energy of the ring. Due to the variety of stored ion species, the isochronous condition cannot be fulfilled for all the ions. In order to eliminate the measurement uncertainty stemming from the velocity spread, an intensity-sensitive and position-resolving cavity is proposed. In this article we first briefly discuss the correction method for the anisochronism effect in the measurement with the cavity. Then we introduce a novel design, which is operated in the monopole mode and offset from the central beam orbit to one side. The geometrical parameters were optimized by analytic and numerical means in accordance with the beam dynamics of the future Collector Ring at FAIR. Afterwards, the electromagnetic properties of scaled prototypes were measured on a test bench. The results were in good agreement with the predictions.

C Yuan, Z Liu, F Xu, PM Walker, Z Podolyak, C Xu, ZZ Ren, B Ding, XY Liu, HS Xu, YH Zhang, XH Zhou, W Zuo (2016)Isomerism in the “south-east” of 132Sn and a predicted neutron-decaying isomer in 129Pd, In: Physics Letters B762pp. 237-242

Excited states in neutron-rich nuclei located south-east of 132Sn are investigated by shell-model calculations. A new shell-model Hamiltonian is constructed for the present study. The proton–proton and neutron–neutron interactions of the Hamiltonian are obtained through the existing CD-Bonn G matrix results, while the proton–neutron interaction across two major shells is derived from the monopole based universal interaction plus the M3Y spin–orbit force. The present Hamiltonian can reproduce well the experimental data available in this region, including one-neutron separation energies, level energies and the experimental B(E2)B(E2) values of isomers in 134,136,138Sn, 130Cd, and 128Pd. New isomers are predicted in this region, e.g. in 135Sn, 131Cd, 129Pd, 132,134In and 130Ag, in which almost no excited states are known experimentally yet. In the odd–odd 132,134In and 130Ag, the predicted very long E 2 life-times of the low-lying 5−5− states are discussed, demanding more information on the related proton–neutron interaction. The low-lying states of 132In are discussed in connection with the recently observed γ rays. The predicted 19/2−19/2− isomer in 129Pd could decay by both electromagnetic transitions and neutron emission with comparable partial life-times, making it a good candidate for neutron radioactivity, a decay mode which is yet to be discovered.

AI Morales, J Benlliure, PH Regan, Z Podolyak, M Gorska, N Alkhomashi, S Pietri, R Kumar, E Casarejos, J Agramunt, A Algora, H Alvarez-Pol, G Benzoni, A Blazhev, P Boutachkov, AM Bruce, LS Caceres, IJ Cullen, AMD Bacelar, P Doornenbal, D Dragosavac, ME Estevez, G Farrelly, Y Fujita, AB Garnsworthy, W Gelletly, J Gerl, J Grebosz, R Hoischen, I Kojouharov, N Kurz, S Lalkovski, Z Liu, D Perez-Loureiro, W Prokopowicz, C Mihai, F Molina, D Muecher, B Rubio, H Schapffner, SJ Steer, A Tamii, S Tashenov, JJV Dobon, S Verma, PM Walker, HJ Wollersheim, PJ Woods (2009)beta-DELAYED gamma-RAY SPECTROSCOPY OF HEAVY NEUTRON RICH NUCLEI "SOUTH" OF LEAD, In: ACTA PHYSICA POLONICA B40(3)pp. 867-870
Z Patel, Z Podolyak, PM Walker, PH Regan, P-A Soederstroem, H Watanabe, E Ideguchi, GS Simpson, S Nishimura, F Browne, R Doornenbal, G Lorusso, S Rice, L Sinclair, T Sumikama, J Wu, ZY Xu, N Aoi, H Baba, FLB Garrote, G Benzoni, R Daido, Z Dombradi, Y Fang, N Fukuda, G Gey, S Go, A Gottardo, N Inabe, T Isobe, D Kameda, K Kobayashi, M Kobayashi, T Komatsubara, I Kojouharov, T Kubo, N Kurz, I Kuti, Z Li, HL Liu, M Matsushita, S Michimasa, C-B Moony, H Nishibata, I Nishizuka, A Odahara, E Sahin, H Sakurai, H Schaffner, H Suzuki, H Takeda, M Tanaka, J Taprogge, Z Vajta, FR Xu, A Yagi, R Yokoyama (2016)Decay spectroscopy of Sm-160: The lightest four-quasiparticle K isomer, In: PHYSICS LETTERS B753pp. 182-186 ELSEVIER SCIENCE BV
AMD Bacelar, AM Bruce, Z Podolyak, S Lalkovski, S Pietri, N Al-Dahan, M Gorska, A Algora, N Alkhomashi, J Benlliure, P Boutachkov, A Bracco, E Calore, E Casarejos, IJ Cullen, AY Deo, P Detistov, Z Dombradi, C Domingo-Pardo, M Doncel, F Farinon, GF Farrelly, H Geissel, W Gelletly, J Gerl, N Goel, J Grebosz, R Hoischen, I Kojouharov, N Kurz, S Leoni, F Molina, AI Morales, D Montanari, A Musumarra, R Nicolini, DR Napoli, C Nociforo, A Prochazka, W Prokopowicz, PH Regan, B Rubio, D Rudolph, S Verma, SJ Steer, P Strmen, TPD Swan, I Szarka, JJ Valiente-Dobon, PM Walker, H Weick, HJ Wollersheim (2009)ANGULAR MOMENTUM POPULATION IN FRAGMENTATION REACTIONS, In: ACTA PHYSICA POLONICA B40(3)pp. 889-892
M. Dasgupta, G. D. Dracoulis, P. M. Walker, A. P. Byrne, T. Kibédi, F. G. Kondev, G. J. Lane, P. H. Regan (2000)Competition between high-K states and rotational structures in 177Ta, In: Physical Review C61(044321)
A Gottardo, JJ Valiente-Dobón, G Benzoni, R Nicolini, JA Núñez, A Algora, N Al-Dahan, GD Angelis, Y Ayyad, N Alkhomashi, PRP Allegro, J Benlliure, P Boutachkov, M Bowry, A Bracco, AM Bruce, M Bunce, E Casarejos, L Cortes, FCL Crespi, F Camera, A Corsi, AMD Bacelar, A Deo, C Domingo-Pardo, M Doncel, Z Dombradi, T Engert, K Eppinger, GF Farrelly, F Farinon, A Gadea, H Geissel, J Gerl, N Goel, M Górska, J Grebosz, E Gregor, T Haberman, R Hoischen, R Janik, S Klupp, I Kojouharov, N Kurz, S Leoni, S Lunardi, S Mandal, R Menegazzo, D Mengoni, B Million, DR Napoli, F Naqvi, C Nociforo, M Pfützner, S Pietri, Z Podolyak, A Prochazka, W Prokopowicz, F Recchia, RV Ribas, MW Reed, PH Regan, D Rudolph, E Sahin, H Schaffner, A Sharma, B Sitar, D Siwal, K Steger, P Strmen, TPD Swan, I Szarka, PM Walker, O Wieland, H Weick, H-J Wollersheim (2011)Isomers in neutron-rich lead isotopes populated via the fragmentation of 238U at 1 GeV A, In: Journal of Physics: Conference Series: International Nuclear Physics Conference312(Sectio)pp. 092019-?

Neutron-rich nuclei beyond N = 126 in the lead region were populated by fragmenting a 238U beam at 1 GeV A on a Be target and then separated by the Fragment Separator (FRS) at GSI. Their isomeric decays were observed, enabling study of the shell structure of neutron-rich nuclei around the Z=82 shell closure. Some preliminary results are reported in this paper.

WN Catford, S Mohammadi, PH Regan, CS Purry, W Gelletly, PM Walker, GJ Gyapong, J Simpson, DD Warner, T Davinson, R Neal, RD Page, AC Shotter, IM Hibbert, R Wadsworth, SA Forbes, AM Bruce, C Thwaites, P Thirolf, P VanDuppen, W Galster, A Ninane, J Vervier, P Decrock, M Huyse, J Szerypo, J Wauters (1996)High resolution gamma-ray spectroscopy with a radioactive beam, In: NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT371(3)pp. 449-459 ELSEVIER SCIENCE BV
Z Podolyak, PH Regan, M Pfutzner, J Gerl, M Hellstrom, M Caamano, P Mayet, C Schlegel, A Aprahamian, J Benlliure, AM Bruce, PA Butler, DC Gil, DM Cullen, J Doring, T Enqvist, F Rejmund, C Fox, JG Narro, H Geissel, W Gelletly, J Giovinazzo, M Gorska, H Grawe, R Grzywacz, A Kleinbohl, W Korten, M Lewitowicz, R Lucas, H Mach, M Mineva, CD O'Leary, F De Oliveira, CJ Pearson, M Rejmund, M Sawicka, H Schaffner, K Schmidt, C Theisen, PM Walker, DD Warner, C Wheldon, HJ Wollersheim, SC Wooding, FR Xu (2000)Isomer spectroscopy of neutron rich W-190(116), In: PHYSICS LETTERS B491(3-4)pp. 225-231 ELSEVIER SCIENCE BV
T Sumikama, K Yoshinaga, H Watanabe, S Nishimura, Y Miyashita, K Yamaguchi, K Sugimoto, J Chiba, Z Li, H Baba, JS Berryman, N Blasi, A Bracco, F Camera, P Doornenbal, S Go, T Hashimoto, S Hayakawa, C Hinke, E Ideguchi, T Isobe, Y Ito, DG Jenkins, Y Kawada, N Kobayashi, Y Kondo, R Kruecken, S Kubono, G Lorusso, T Nakano, M Kurata-Nishimura, A Odahara, HJ Ong, S Ota, Z Podolyak, H Sakurai, H Scheit, K Steiger, D Steppenbeck, S Takano, A Takashima, K Tajiri, T Teranishi, Y Wakabayashi, PM Walker, O Wieland, H Yamaguchi (2011)Structural Evolution in the Neutron-Rich Nuclei Zr-106 and Zr-108, In: PHYSICAL REVIEW LETTERS106(20)ARTN 2pp. ?-? AMER PHYSICAL SOC
HL Liu, FR Xu, Y Sun, PM Walker, R Wyss (2011)On the stability of high-K isomers in the second well of actinide nuclei, In: European Physical Journal A47(11)pp. 1-5 Springer Verlag

Actinide nuclei are found to be good candidates for the formation of high angular momentum, broken-pair excitations in the second minimum of the potential-energy surface. Configuration-constrained calculations of the energy surfaces, including reflection asymmetry, give predictions of the properties of high-K states in the second well. In addition to excitation energies, spins and parities, the calculations indicate increased barriers towards fission, consistent with the extended half-lives observed experimentally.

S Mohammadi, G De Angelis, M Axiotis, D Bazzacco, PG Bizzeti, F Brandolini, R Broda, D Bucurescu, E Farnea, W Gelletly, A Gadea, M Ionescu-Bujor, A Iordachescu, T Kroll, S Longdown, S Lunardi, N Marginean, T Martinez, N Medina, Z Podolyak, B Quintana, PH Regan, B Rubio, CA Ur, J-JV Dobon, PM Walker, YH Zhang (2006)Yrast states in Os-188,Os-190 nuclei, In: INTERNATIONAL JOURNAL OF MODERN PHYSICS E-NUCLEAR PHYSICS15(8)pp. 1797-1802
K. A. Gladnishki, Zs. Podolyák, P. H. Regan, J. Gerl, M. Hellström, Y. Kopatch, S. Mandal, M. Górska, R. D. Page, H. J. Wollersheim, A. Banu, G. Benzoni, H. Boardman, M. La Commara, J. Ekman, C. Fahlander, H. Geissel, H. Grawe, E. Kaza, A. Korgul, M. Matos, M. N. Mineva, C. J. Pearson, C. Plettner, D. Rudolph, Ch. Scheidenberger, K. -H. Schmidt, V. Shishkin, D. Sohler, K. Sümmerer, J. J. Valiente-Dobón, P. M. Walker, H. Weick, M. Winkler, O. Yordanov (2004)Angular momentum population in the projectile fragmentation of 238U at 750 MeV/nucleon, In: Physical Review C69(024617)
N Alkhomashi, PH Regan, Z Podoyak, SB Pietri, AB Garnsworthy, SJ Steer, J Benlliure, E Caserejos, M Gorska, J Gerl, HJ Wollersheim, J Grebosz, N Kurz, I Kojouharov, H Schaffner, A Alcora, G Benzoni, A Blazhev, P Boutachkov, AM Bruce, L Caceres, P Doornenbal, AMD Bacelar, IJ Cullen, ME Estevez, G Farrelly, Y Fujita, W Gelletly, R Hoischen, R Kumar, S Lalkovski, Z Liu, C Mihai, F Molina, D Muecher, B Rubio, A Tamii, S Tashenov, JJ Valiente-Dobon, PM Walker, PJ Woods (2009)beta(-)-DELAYED AND ISOMER SPECTROSCOPY OF NEUTRON-RICH Ta AND W ISOTOPES, In: ACTA PHYSICA POLONICA B40(3)pp. 875-878
S. Frauendorf, K. Neergard, J. A. Sheikh, P. M. Walker (2000)Moments of inertia for multiquasiparticle configurations, In: Physical Review C61(064324)
DM Cullen, LK Pattison, JF Smith, AM Fletcher, PM Walker, HM El-Masri, Z Podolyak, RJ Wood, C Scholey, C Wheldon, G Mukherjee, D Balabanski, M Djongolov, T Dalsgaard, H Thisgaard, G Sletten, F Kondev, D Jenkins, GD Dracoulis, GJ Lane, IY Lee, AO Macchiavelli, F Xu (2003)High-spin states, lifetime measurements and isomers in Os-181, In: NUCLEAR PHYSICS A728(3-4)pp. 287-338 ELSEVIER SCIENCE BV
P. M. Walker, G. D. Dracoulis, A. P. Byrne, B. Fabricius, T. Kibédi, A. E. Stuchbery (1991)Resolution of the 179isomer anomaly: Exposure of a Fermi-aligned s band, In: Physical Review Letters67(433)pp. 433-436
JN Orce, AM Bruce, A Emmanouilidis, C Wheldon, FR Xu, PM Walker, M Caamano, Z Podolyak, H El-Masri, PD Stevenson, AP Byrne, GD Dracoulis, JC Hazel, T Kibedi, DM Cullen (2003)Interplay between K-isomerism and gamma-softness in Xe-128, In: ACTA PHYSICA POLONICA B34(4)pp. 2253-2256
Philip Walker (2017)Shape Effects in E2 Transition Rates from Z ≈ 76 High-Spin Isomers, In: Bulgarian Journal of Physics44(4)pp. 427-433 Heron Press

It is well known that high-K isomers have strongly hindered electromagnetic decay rates. However, the situation is more subtle in shape-transition regions, where there are competing high-spin isomers associated with shape changes. Nevertheless, a previous analysis of E2 decay rates from isomers in N ≈ 76 (A ≈ 130) nuclides enabled a degree of separation to be made between high-K prolate states and low-K oblate states. The analysis exploited the dependence of E2 reduced hindrance factors, fν, on the product of the valence nucleon numbers, NpNn. The present work investigates the application of these ideas to data for neutron-rich Z ≈ 76 (A ≈ 180) nuclides. Despite few such isomer data being available, it is found that the reduced hindrance factors can be used to help in distinguishing between three different $E2$-transition types. In particular, the decays from high-K prolate isomers to the ground-state band are more hindered than the corresponding decays from low-K oblate isomers. Other decays from low-K oblate isomers have collective E2 transition rates. These features may be helpful in future studies of nuclides in the neutron-rich Z ≈ 76 region.

L Marmugi, Philip Walker, F Renzoni (2017)Coherent gamma photon generation in a Bose–Einstein condensate of135mCs, In: Physics Letters B777pp. 281-285 Elsevier

We have identified a mechanism of collective nuclear de-excitation in a Bose–Einstein condensate of 135Cs atoms in their isomeric state, 135mCs, suitable for the generation of coherent gamma photons. The process described here relies on coherence transfer from the Bose–Einstein condensate to the photon field, leading to collective decay triggered by spontaneous emission of a gamma photon. The mechanism differs from single-pass amplification, which cannot occur in atomic systems due to the nuclear recoil and the associated large shift between absorption and emission lines, nor does it require the large densities necessary for standard Dicke super-radiance. This overcomes the limitations that have been hindering the production of coherent gamma photons in many systems. Therefore, we propose an approach for generation of coherent gamma rays, which relies on a combination of well established techniques of nuclear and atomic physics, and can be realized with currently available technology.

Y. H. Qiang, C. M. Petrache, S. Guo, P.M. Walker, D. Mengoni, Q. B. Chen, B. F. Lv, A. Astier, E. Dupont, M. L. Liu, X. H. Zhou, J. G. Wang, D. Bazzacco, A. Boso, A. Goasduff, F. Recchia, D. Testov, F. Galtarossa, G. Jaworski, D. R. Napoli, S. Riccetto, M. Siciliano, J. J. Valiente-Dobon, C. Andreoiu, F. H. Garcia, K. Ortner, K. Whitmore, B. Cederwall, E. A. Lawrie, I. Kuti, D. Sohler, T. Marchlewski, J. Srebrny, A. Tucholski, A. C. Dai, F. R. Xu (2019)Identification of high- K rotation in Ba130 : Testing the consistency of electromagnetic observables, In: Physical Review C99(1)014307 American Physical Society

The band built on the Kπ = 8−, T1/2 = 9.4 ms isomer of 130Ba has been identified, filling the gap in the systematics of the dipole bands built on the 8− isomers in the N = 74 isotones from 128Xe to 138Gd. The use of the GALILEO array in conjunction with its ancillaries EUCLIDES and Neutron Wall, helped to firmly place the newly identified transitions on top of the long-lived isomer. The extracted gK and gR gyromagnetic factors are in agreement with the 7/2+[404] ⊗ 9/2−[514] two-neutron Nilsson configuration. Particle-rotor model calculations give an understanding of the limited degree of K mixing. The experimental information on the Kπ = 8− isomer of 130Ba is now the most complete among the K isomers of the N = 74 isotones.

P-A Soederstroem, PH Regan, PM Walker, H Watanabe, P Doornenbal, Z Korkulu, P Lee, HL Liu, JJ Liu, G Lorusso, S Nishimura, T Sumikama, VH Phong, J Wu, FR Xu, A Yagi, GX Zhang, T Alharbi, H Baba, F Browne, AM Bruce, R Carroll, KY Chae, Z Dombradi, A Estrade, N Fukuda, C Griffin, E Ideguchi, N Inabe, T Isobe, H Kanaoka, I Kojouharov, FG Kondev, T Kubo, S Kubono, N Kurz, I Kuti, S Lalkovski, GJ Lane, CS Lee, EJ Lee, G Lotay, C-B Moon, I Nishizuka, CR Nita, A Odahara, Z Patel, Z Podolyak, OJ Roberts, H Sakurai, H Schaffner, CM Shand, H Suzuki, H Takeda, S Terashima, Z Vajta, JJ Valiente-Dobon, ZY Xu, S Yoshida (2015)Heavy Rotation - Evolution of quadrupole collectivity centred at the neutron-rich doubly mid-shell nucleus Dy-170, In: NUCLEAR STRUCTURE AND DYNAMICS '151681
SJ Steer, Z Podolyak, S Pietri, PH Regan, D Rudolph, E Werner-Malento, AB Garnsworthy, R Hoischen, M Gorska, J Gerl, HJ Wollersheim, F Becker, P Bednarczyk, L Caceres, P Doornenbal, H Geissel, J Grebosz, A Kelic, N Kurz, F Montes, W Prokopowicz, T Saito, H Schaffner, S Tachenov, A Heinz, M Pfuetzner, T Kurtukian-Nieto, G Benzoni, A Jungclaus, DL Balabanski, C Brandau, AM Bruce, WN Catford, IJ Cullen, Z Dombradi, E Estevez, W Gelletly, G Ilie, J Jolie, GA Jones, M Kmiecik, FG Kondev, S Lalkovski, Z Liu, A Maj, S Myalski, T Shizuma, S Schwertel, PM Walker, O Wieland (2007)Identification of isomeric states 'south' of Pb-208 via projectile fragmentation, In: ACTA PHYSICA POLONICA B38(4)pp. 1283-1286
PM Walker (2006)Isomer beams, In: INTERNATIONAL JOURNAL OF MODERN PHYSICS E-NUCLEAR PHYSICS15(7)pp. 1637-1644
Z Podolyak, PM Walker, H Mach, G de France, G Sletten, F Azaiez, JM Casandjian, B Cederwall, DM Cullen, Z Dombradi, GD Dracoulis, LM Fraile, S Franchoo, H Fynbo, M Gorska, Y Kopatch, GJ Lane, S Mandal, L Milechina, J Molnar, C O'Leary, W Plociennik, V Pucknell, P Raddon, N Redon, E Ruchowska, M Stanoiu, O Tengblad, C Wheldon, R Wood (2003)gamma-ray spectroscopy with a He-8 beam, In: NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT511(3)pp. 354-359 ELSEVIER SCIENCE BV
B Sun, R Knoebel, YA Litvinov, S Nakajima, H Geissel, J Meng, K Beckert, F Bosch, D Boutin, C Brandau, L Chen, IJ Cullen, C Dimopoulou, B Fabian, M Hausmann, O Klepper, C Kozhuharov, J Kurcewicz, SA Litvinov, M Mazzocco, F Montes, G Muenzenberg, A Musumarra, C Nociforo, F Nolden, T Ohtsubo, A Ozawa, Z Patyk, WR Plass, C Scheidenberger, M Steck, T Suzuki, PM Walker, H Weick, N Winckler, M Winkler, T Yamaguchi (2009)LARGE-SCALE MASS MEASUREMENTS OF SHORT-LIVED NUCLIDES WITH THE ISOCHRONOUS MASS SPECTROMETRY AT GSI, In: INTERNATIONAL JOURNAL OF MODERN PHYSICS E-NUCLEAR PHYSICS18(2)pp. 346-351
PH Regan, AB Garnsworthy, S Pietri, L Caceres, M Gorska, D Rudolph, Z Podolyak, SJ Steer, R Hoischen, J Gerl, HJ Wollersheim, J Grebosz, H Schaffner, W Prokopwicz, I Kojouharov, F Becker, P Bednarczyk, P Doornenball, H Geissel, H Grawe, A Kelic, N Kurz, F Montes, T Saito, S Tashenov, E Werner-Malento, A Heinz, L Atanasova, D Balabanski, G Benzoni, B Blank, A Blazhev, C Brandau, AM Bruce, F Camera, IJ Cullen, ME Estevez, C Fahlander, W Gelletly, G Ilie, A Jungclaus, J Jolie, T Kurtukian-Nieto, Z Liu, M Kmiecik, A Maj, S Myalski, S Schwertel, T Shizuma, AJ Simons, PM Walker, O Wieland (2007)Isomer spectroscopy using relativistic projectile fragmentation at the N=Z line for A similar to 80 -> 90., In: NUCLEAR PHYSICS A787pp. 491C-498C ELSEVIER SCIENCE BV

The preliminary results from the RISING Stopped Beam Isomer Campaign are presented, with specific focus on results of the initial experiment to investigate isomeric decays along the N=Z line around A similar to 80-90 following the projectile fragmentation of a Ag-107 primary beam at an energy of 750 MeV per nucleon. A description of the technical aspects behind the design of the RISING array is presented, together with evidence for previously unreported isomeric decays in Tc-87,Tc-88 and the N=Z nuclei Nb-82(41) and Tc-86(43).

R. D'Alarcao, P. Chowdhury, E. H. Seabury, P. M. Walker, C. Wheldon, I. Ahmad, M. P. Carpenter, G. Hackman, R. V. F. Janssens, T. L. Khoo, C. J. Lister, D. Nisius, P. Reiter, D. Seweryniak, I. Wiedenhoever (1999)High-K isomers in neutron-rich hafnium nuclei at and beyond the stability line, In: Physical Review C59(3)
A Gottardo, JJ Valiente-Dobon, G Benzoni, S Lunardi, A Gadea, A Algora, N Al-Dahan, G de Angelis, Y Ayyad, D Bazzacco, J Benlliure, P Boutachkov, M Bowry, A Bracco, AM Bruce, M Bunce, F Camera, E Casarejos, ML Cortes, FCL Crespi, A Corsi, AMD Bacelar, AY Deo, C Domingo-Pardo, M Doncel, T Engert, K Eppinger, GF Farrelly, F Farinon, E Farnea, H Geissel, J Gerl, N Goel, M Gorska, J Grebosz, E Gregor, T Habermann, R Hoischen, R Janik, PR John, S Klupp, I Kojouharov, N Kurz, SM Lenzi, S Leoni, S Mandal, R Menegazzo, D Mengoni, B Million, V Modamio, AI Morales, DR Napoli, F Naqvi, R Nicolini, C Nociforo, M Pfuetzner, S Pietri, Z Podolyak, A Prochazka, W Prokopowicz, F Recchia, PH Regan, MW Reed, D Rudolph, E Sahin, H Schaffner, A Sharma, B Sitar, D Siwal, K Steiger, P Strmen, TPD Swan, I Szarka, CA Ur, PM Walker, H Weick, O Wieland, H-J Wollersheim (2014)Isomeric decay spectroscopy of the Bi-217 isotope, In: PHYSICAL REVIEW C90(3)ARTN 0pp. ?-? AMER PHYSICAL SOC
B Sun, R Knoebel, YA Litvinov, H Geissel, J Meng, K Beckert, F Bosch, D Boutin, C Brandau, L Chen, IJ Cullen, C Dimopoulou, B Fabian, M Hausmann, C Kozhuharov, SA Litvinov, M Mazzocco, F Montes, G Muenzenberg, A Musumarra, S Nakajima, C Nociforo, F Nolden, T Ohtsubo, A Ozawa, Z Patyk, WR Plass, C Scheidenberger, M Steck, T Suzuki, PM Walker, H Weick, N Winckler, M Winkler, T Yamaguchi (2008)Nuclear structure studies of short-lived neutron-rich nuclei with the novel large-scale isochronous mass spectrometry at the FRS-ESR facility, In: NUCLEAR PHYSICS A812pp. 1-12 ELSEVIER SCIENCE BV
M. B. Smith, P. M. Walker, G. C. Ball, J. J. Carroll, P. E. Garrett, G. Hackman, R. Propri, F. Sarazin, H. C. Scraggs (2003)γ- rays emitted in the decay of 31-yr 178Hf m2, In: Physical Review C68(3)
F. R. Xu, P. M. Walker, R. Wyss (2002)Oblate stability of A≈110 nuclei near the r-process path, In: Physical Review C65(021303)
F.C. Ozturk, B. Akkus, D. Atanasov, H. Beyer, F. Bosch, D. Boutin, C. Brandau, P. Bühler, R.B. Cakirli, R.J. Chen, W.D. Chen, X.C. Chen, I. Dillmann, C. Dimopoulou, W. Enders, H.G. Essel, T. Faestermann, O. Forstner, B.S. Gao, H. Geissel, R. Gernhäuser, R.E. Grisenti, A. Gumberidze, S. Hagmann, T. Heftrich, M. Heil, M.O. Herdrich, P.-M. Hillenbrand, T. Izumikawa, P. Kienle, C. Klaushofer, C. Kleffner, C. Kozhuharov, R.K. Knöbel, O. Kovalenko, S. Kreim, T. Kühl, C. Lederer-Woods, M. Lestinsky, S.A. Litvinov, Yu.A. Litvinov, Z. Liu, X.W. Ma, L. Maier, B. Mei, H. Miura, I. Mukha, A. Najafi, D. Nagae, T. Nishimura, C. Nociforo, F. Nolden, T. Ohtsubo, Y. Oktem, S. Omika, A. Ozawa, N. Petridis, J. Piotrowski, R. Reifarth, J. Rossbach, R. Sánchez, M.S. Sanjari, C. Scheidenberger, R.S. Sidhu, H. Simon, U. Spillmann, M. Steck, Th. Stöhlker, B.H. Sun, L.A. Susam, F. Suzaki, T. Suzuki, S.Yu. Torilov, C. Trageser, M. Trassinelli, S. Trotsenko, X.L. Tu, P.M. Walker, M. Wang, G. Weber, H. Weick, N. Winckler, D.F.A. Winters, P.J. Woods, T. Yamaguchi, X.D. Xu, X.L. Yan, J.C. Yang, Y.J. Yuan, Y.H. Zhang, X.H. Zhou (2019)New test of modulated electron capture decay of hydrogen-like 142Pm ions: Precision measurement of purely exponential decay, In: PHYSICS LETTERS B797134800 ELSEVIER SCIENCE BV

An experiment addressing electron capture (EC) decay of hydrogen-like 142Pm60+ions has been conducted at the experimental storage ring (ESR) at GSI. The decay appears to be purely exponential and no modulations were observed. Decay times for about 9000 individual EC decays have been measured by applying the single-ion decay spectroscopy method. Both visually and automatically analysed data can be described by a single exponential decay with decay constants of 0.0126(7)s−1for automatic analysis and 0.0141(7)s−1for manual analysis. If a modulation superimposed on the exponential decay curve is assumed, the best fit gives a modulation amplitude of merely 0.019(15), which is compatible with zero and by 4.9 standard deviations smaller than in the original observation which had an amplitude of 0.23(4).

Z Podolyak, CM Shand, E Wilson, BA Brown, H Grawe, CJ Chiara, S Zhu, B Fornal, RVF Janssens, M Bowry, M Bunce, MP Carpenter, N Cieplicka, AY Deo, GD Dracoulis, CR Hoffman, RS Kempley, FG Kondev, GJ Lane, T Lauritsen, G Lotay, MW Reed, PH Regan, CR Triguero, D Seweryniak, B Szpak, PM Walker, A Gargano, L Coraggio, N Itaco (2015)Octupole transitions in the Pb-208 region, In: 11TH INTERNATIONAL SPRING SEMINAR ON NUCLEAR PHYSICS: SHELL MODEL AND NUCLEAR STRUCTURE - ACHIEVEMENTS OF THE PAST TWO DECADES580ARTN 0pp. ?-? IOP PUBLISHING LTD
M Oi, PH Regan, FR Xu, PM Walker, AK Rath, PD Stevenson (2002)Cranked-Hartree-Fock-Bogoliubov analysis at the valence maximum: Yrast behaviour of Dy-170(66)104, In: PROGRESS OF THEORETICAL PHYSICS SUPPLEMENT(146)pp. 609-610
C Wheldon, PM Walker, P Chowdhury, I Shestakova, R D'Alarcao, I Ahmad, MP Carpenter, DM Cullen, RVF Janssens, TL Khoo, FG Kondev, CJ Lister, CJ Pearson, Z Podolyak, D Seweryniak, I Wiedenhoever (2001)First observation of a rotational band in neutron-rich Lu-180, In: JOURNAL OF PHYSICS G-NUCLEAR AND PARTICLE PHYSICS27(2)pp. L13-L17 IOP PUBLISHING LTD
Y Shi, FR Xu, HL Liu, PM Walker (2010)Multi-quasiparticle excitation: Extending shape coexistence in A similar to 190 neutron-deficient nuclei, In: PHYSICAL REVIEW C82(4)ARTN 0pp. ?-? AMER PHYSICAL SOC
P. M. Walker (2005)High-K Structures Under Extreme Conditions, In: Acta Physica Polonica B36pp. 1055-1061

High-K isomer decay rates are compared and interpreted, with an emphasis on the spin degree of freedom. It is argued that high-K values do not in themselves lead to K mixing. Rather, evidence is presented that the most important consideration is the isomer energy relative to a rotor whose moment of inertia is approximately 85____% of the rigid-body value. The high-spin limit to the occurrence of high-K isomers is then discussed in connection with predictions of competing oblate rotation-aligned structures. Finally, some observations are made regarding the use of K isomers as a tool to access exotic nuclei, including superheavy elements, and exotic nuclear structures.

MB Smith, PM Walker, RS Chakrawarthy, RAE Austin, GC Ball, JJ Carroll, E Cunningham, P Finlay, PE Garrett, GF Grinyer, G Hackman, B Hyland, K Koopmans, WD Kulp, JR Leslie, AA Phillips, R Propri, PH Regan, F Sarazin, MA Schumaker, HC Scraggs, T Shizuma, CE Svensson, J von Schwarzenberg, JC Waddington, D Ward, JL Wood, B Washbrook, EF Zganjar (2004)Studies of high-K isomers at TRIUMF-ISAC, In: NUCLEAR PHYSICS A746pp. 617C-620C
C Wheldon, PM Walker, PH Regan, T Saitoh, N Hashimoto, G Sletten, FR Xu (1999)High-K structures and triaxiality in Os-186, In: NUCLEAR PHYSICS A652(2)pp. 103-131 ELSEVIER SCIENCE BV
XL Tu, B Mei, YH Zhang, HS Xu, YA Litvinov, WJ Huang, Z Podolyak, A Kelic-Heil, W Zhang, SA Litvinov, K Blaum, XH Zhou, P Shuai, M Wang, BS Gao, XC Chen, YJ Yuan, JW Xia, JC Yang, ZG Hu, XW Ma, BH Sun, XL Yan, RS Mao, ZY Sun, GQ Xiao, X Xu, PM Walker, T Yamaguchi, F Bosch, N Winckler, RJ Chen, YM Xing, CY Fu, DW Liu, Q Zeng, Z Ge, Y Sun, HW Zhao, TC Zhao (2015)Study of projectile fragmentation reaction with isochronous mass spectrometry, In: PHYSICA SCRIPTAT166ARTN 01400 IOP PUBLISHING LTD
C.M. Petrache, P.M. Walker, S. Guo, Q.B. Chen, S. Frauendorf, Y.X. Liu, R.A. Wyss, D. Mengoni, Y.H. Qiang, A. Astier, E. Dupont, R. Li, B.F. Lv, K.K. Zheng, D. Bazzacco, A. Boso, A. Goasduff, F. Recchia, D. Testov, F. Galtarossa, G. Jaworski, D.R. Napoli, S. Riccetto, M. Siciliano, J.J. Valiente-Dobon, M.L. Liu, X.H. Zhou, J.G. Wang, C. Andreoiu, F.H. Garcia, K. Ortner, K. Whitmore, T. Bäck, B. Cederwall, E.A. Lawrie, I. Kuti, D. Sohler, J. Timár, T. Marchlewski, J. Srebrny, A. Tucholski (2019)Diversity of shapes and rotations in the γ-soft 130Ba nucleus: First observation of a t-band in the A = 130 mass region, In: PHYSICS LETTERS B795pp. 241-247 ELSEVIER SCIENCE BV

Several new bands have been identified in 130Ba, among which there is one with band-head spin 8+. Its properties are in agreement with the Fermi-aligned νh211/2, 7/2−[523] ⊗9/2−[514]Nilsson configuration. This is the first observation of a two-quasiparticle t-band in the A =130mass region. The t-band is fed by a dipole band involving two additional h11/2protons. The odd-spin partners of the proton and neutron S-bands and the ground-state band at high spins are also newly identified. The observed bands are discussed using several theoretical models, total Routhians surfaces (TRS), tilted axis cranking (TAC), particle rotor model (PRM) and projected shell model (PSM), which strongly suggest the coexistence of prolate and oblate shapes polarized by rotation aligned two-proton and two-neutron configurations, as well as prolate collective rotations around axes with different orientations. With the new results, 130Ba presents one of the best and most complete sets of collective excitations that a γ-soft nucleus can manifest at medium and high spins, revealing a diversity of shapes and rotations for the nuclei in the A =130mass region.

A. Tucholski, Ch. Droste, J. Srebrny, C. M. Petrache, J. Skalski, P. Jachimowicz, M. Fila, T. Abraham, M. Kisieliński, A. Kordyasz, M. Kowalczyk, J. Kownacki, T. Marchlewski, P. J. Napiorkowski, L. Próchniak, J. Samorajczyk-Pyśk, A. Stolarz, A. Astier, B. F. Lv, E. Dupont, S. Lalkovski, P. Walker, E. Grodner, Z. Patyk (2019)Lifetime of the recently identified 10+ isomeric state at 3279 keV in the Nd136 nucleus, In: Physical Review C100(1)014330 American Physical Society

Background: The γ softness of 136Nd makes it possible to study the shape changes induced by two-proton or two-neutron excitation. Purpose: We measure the lifetimes of two-quasiparticle states of the bands based on the 10+ states at 3296 and 3279 keV to investigate the shape change induced by the alignment of two protons or two neutrons in the h11/2 orbital. Methods: The recoil-distance Doppler shift method was used for the study of 136Nd studies, which was formed by the fusion reaction 120Sn(20Ne, 4n)136Nd, at Ebeam = 85 MeV. Calculations were performed within the microscopic-macroscopic approach, based on the deformed Woods-Saxon single-particle potential and the Yukawa-plus-exponential macroscopic energy. Results: The lifetime of the 10+ state at 3279 keV of 136Nd was measured to be T 10+1/2 = 1.63(9) ns. The lifetimes of the 2+ state at 374 keV and of the 12+ state at 3686 keV of the ground band were also measured to be T 2+1/2 = 26.5(14) ps and T 12+1/2 = 22.5(14) ps. Conclusions: The measured lifetime of 10+ the state at 3279 keV together with other observables confirm the structure change in 136Nd. A rather small reduced hindrance of the electromagnetic decay of the 10+ state at 3279 keV would be consistent with its K-mixed character.

A. Gottardo, J. J. Valiente-Dobón, G. Benzoni, A. I. Morales, A. Gadea, S. Lunardi, P. Boutachkov, A. M. Bruce, M. Górska, J. Grebosz, S. Pietri, Zs. Podolyak, M. Pfützner, P. H. Regan, D. Rudolph, H. Weick, J. Alcántara Núñez, A. Algora, N. Al-Dahan, G. de Angelis, Y. Ayyad, N. Alkhomashi, P. R. P. Allegro, D. Bazzacco, J. Benlliure, M. Bowry, A. Bracco, M. Bunce, F. Camera, E. Casarejos, M. L. Cortes, F. C. L. Crespi, A. Corsi, A. M. Denis Bacelar, A. Y. Deo, C. Domingo-Pardo, M. Doncel, Zs. Dombradi, T. Engert, K. Eppinger, G. F. Farrelly, F. Farinon, H. Geissel, J. Gerl, N. Goel, E. Gregor, T. Habermann, R. Hoischen, R. Janik, S. Klupp, I. Kojouharov, N. Kurz, S. M. Lenzi, S. Leoni, S. Mandal, R. Menegazzo, D. Mengoni, B. Million, D. R. Napoli, F. Naqvi, C. Nociforo, A. Prochazka, W. Prokopowicz, F. Recchia, R. V. Ribas, M. W. Reed, E. Sahin, H. Schaffner, A. Sharma, B. Sitar, D. Siwal, K. Steiger, P. Strmen, T. P. D. Swan, I. Szarka, C. A. Ur, P.M. Walker, O. Wieland, H-J. Wollersheim, F. Nowacki, E. Maglione (2019)New spectroscopic information on 211;213Tl A changing structure beyond the N=126 shell closure, In: Physical Review C99(5)pp. 054326-1 American Physical Society

The neutron-rich isotopes 211;213Tl, beyond the N = 126 shell-closure, have been studied for the first time in isomer γ-ray decay, exploiting the fragmentation of a primary uranium beam at the FRS-RISING (FRagment Separator-Rare ISotopes INvestigation at GSI) setup at GSI. The observed isomeric states in 211;213Tl show a deviation from the seniority-like scheme of 209Tl. The possible interpretation of the data is discussed on the basis of energy-level systematics and shell-model calculations.

A Gottardo, JJ Valiente-Dobón, G De Angelis, DR Napoli, E Sahin, A Gottardo, S Lunardi, SM Lenzi, E Maglione, G Benzoni, R Nicolini, A Bracco, F Camera, FCL Crespi, A Corsi, S Leoni, B Million, AI Morales, O Wieland, R Nicolini, A Bracco, F Camera, A Corsi, S Leoni, A Gadea, A Algora, S Lunardi, D Bazzacco, E Farnea, SM Lenzi, R Menegazzo, D Mengoni, F Recchia, CA Ur, E Maglione, P Boutachkov, M Górska, S Pietri, H Weick, ML Cortes, C Domingo-Pardo, T Engert, F Farinon, H Geissel, J Gerl, N Goel, E Gregor, T Habermann, R Hoischen, I Kojouharov, N Kurz, F Naqvi, C Nociforo, A Prochazka, W Prokopowicz, H Schaffner, A Sharma, H-J Wollersheim, AM Bruce, M Bunce, AM Denis Bacelar, J Grebosz, Z Podolyák, PH Regan, N Al-Dahan, M Bowry, AY Deo, GF Farrelly, MW Reed, TPD Swan, PM Walker, M Pfützner, J Alcántara Núñez, Y Ayyad, J Benlliure, N Alkhomashi, PRP Allegro, RV Ribas, E Casarejos, M Doncel, Z Dombradi, K Eppinger, S Klupp, K Steiger, R Hoischen, D Rudolph, R Janik, B Sitar, P Strmen, I Szarka, S Mandal, D Siwal, F Naqvi, PM Walker, F Nowacki, AP Zuker (2012)New isomers in the full seniority scheme of neutron-rich lead isotopes: The role of effective three-body forces, In: Physical Review Letters109(16) American Physical Society

The neutron-rich lead isotopes, up to Pb216, have been studied for the first time, exploiting the fragmentation of a primary uranium beam at the FRS-RISING setup at GSI. The observed isomeric states exhibit electromagnetic transition strengths which deviate from state-of-the-art shell-model calculations. It is shown that their complete description demands the introduction of effective three-body interactions and two-body transition operators in the conventional neutron valence space beyond Pb208. © 2012 American Physical Society.

P M Walker, Y Hirayama, G J Lane, H Watanabe, G D Dracoulis, M Ahmed, M Brunet, T Hashimoto, S Ishizawa, F G Kondev, Yu A Litvinov, H Miyatake, J Y Moon, M Mukai, T Niwase, J H Park, Zs Podolyák, M Rosenbusch, P Schury, M Wada, X Y Watanabe, W Y Liang, ZSOLT PODOLYAK, F R Xu (2020)Properties of 187 Ta Revealed through Isomeric Decay, In: Physical Review Letters125(19) American Physical Society

Mass-separated 187Ta114 in a high-spin isomeric state has been produced for the first time by multinucleon transfer reactions, employing an argon gas-stopping cell and laser ionization. Internal γ rays revealed a T1/2 = 7.3 ± 0.9     s isomer at 1778 ± 1     keV , which decays through a rotational band with perturbations associated with the approach to a prolate-oblate shape transition. Model calculations show less influence from triaxiality compared to heavier elements in the same mass region. The isomer-decay reduced E 2 hindrance factor fν = 27 ± 1 supports the interpretation that axial symmetry is approximately conserved.

S Akkoyun, A Algora, B Alikhani, F Ameil, G De Angelis, L Arnold, A Astier, A Ataç, Y Aubert, C Aufranc, A Austin, S Aydin, F Azaiez, S Badoer, DL Balabanski, D Barrientos, G Baulieu, R Baumann, D Bazzacco, FA Beck, T Beck, P Bednarczyk, M Bellato, MA Bentley, G Benzoni, R Berthier, L Berti, R Beunard, G Lo Bianco, B Birkenbach, PG Bizzeti, AM Bizzeti-Sona, F Le Blanc, JM Blasco, N Blasi, D Bloor, C Boiano, M Borsato, D Bortolato, AJ Boston, HC Boston, P Bourgault, P Boutachkov, A Bouty, A Bracco, S Brambilla, IP Brawn, A Brondi, S Broussard, B Bruyneel, D Bucurescu, I Burrows, A Bürger, S Cabaret, B Cahan, E Calore, F Camera, A Capsoni, F Carrió, G Casati, M Castoldi, B Cederwall, J-L Cercus, V Chambert, M El Chambit, R Chapman, L Charles, J Chavas, E Clément, P Cocconi, S Coelli, PJ Coleman-Smith, A Colombo, S Colosimo, C Commeaux, D Conventi, RJ Cooper, A Corsi, A Cortesi, L Costa, FCL Crespi, JR Cresswell, DM Cullen, D Curien, A Czermak, D Delbourg, R Depalo, T Descombes, P Désesquelles, P Detistov, C Diarra, F Didierjean, MR Dimmock, QT Doan, C Domingo-Pardo, M Doncel, F Dorangeville, N Dosme, Y Drouen, G Duchêne, B Dulny, J Eberth, P Edelbruck, J Egea, T Engert, MN Erduran, S Ertürk, C Fanin, S Fantinel, E Farnea, T Faul, M Filliger, F Filmer, C Finck, G De France, A Gadea, W Gast, A Geraci, J Gerl, R Gernhäuser, A Giannatiempo, A Giaz, L Gibelin, A Givechev, N Goel, V González, A Gottardo, X Grave, J Grȩbosz, R Griffiths, AN Grint, P Gros, L Guevara, M Gulmini, A Görgen, HTM Ha, T Habermann, LJ Harkness, H Harroch, K Hauschild, C He, A Hernández-Prieto, B Hervieu, H Hess, T Hüyük, E Ince, R Isocrate, G Jaworski, A Johnson, J Jolie, P Jones, B Jonson, P Joshi, DS Judson, A Jungclaus, M Kaci, N Karkour, M Karolak, A Kaşkaş, M Kebbiri, RS Kempley, A Khaplanov, S Klupp, M Kogimtzis, I Kojouharov, A Korichi, W Korten, T Kröll, R Krücken, N Kurz, BY Ky, M Labiche, X Lafay, L Lavergne, IH Lazarus, S Leboutelier, F Lefebvre, E Legay, L Legeard, F Lelli, SM Lenzi, S Leoni, A Lermitage, D Lersch, J Leske, SC Letts, S Lhenoret, RM Lieder, D Linget, J Ljungvall, A Lopez-Martens, A Lotodé, S Lunardi, A Maj, J Van Der Marel, Y Mariette, N Marginean, R Marginean, G Maron, AR Mather, W Mȩczyński, V Mendéz, P Medina, B Melon, R Menegazzo, D Mengoni, E Merchan, L Mihailescu, C Michelagnoli, J Mierzejewski, L Milechina, B Million, K Mitev, P Molini, D Montanari, S Moon, F Morbiducci, R Moro, PS Morrall, O Möller, A Nannini, DR Napoli, L Nelson, M Nespolo, VL Ngo, M Nicoletto, R Nicolini, Y Le Noa, PJ Nolan, M Norman, J Nyberg, A Obertelli, A Olariu, R Orlandi, DC Oxley, C Özben, M Ozille, C Oziol, E Pachoud, M Palacz, J Palin, J Pancin, C Parisel, P Pariset, G Pascovici, R Peghin, L Pellegri, A Perego, S Perrier, M Petcu, P Petkov, C Petrache, E Pierre, N Pietralla, S Pietri, M Pignanelli, I Piqueras, Z Podolyak, P Le Pouhalec, J Pouthas, D Pugnére, VFE Pucknell, A Pullia, B Quintana, R Raine, G Rainovski, L Ramina, G Rampazzo, G La Rana, M Rebeschini, F Recchia, N Redon, M Reese, P Reiter, PH Regan, S Riboldi, M Richer, M Rigato, S Rigby, G Ripamonti, AP Robinson, J Robin, J Roccaz, J-A Ropert, B Rossé, C Rossi Alvarez, D Rosso, B Rubio, D Rudolph, F Saillant, E Şahin, F Salomon, M-D Salsac, J Salt, G Salvato, J Sampson, E Sanchis, C Santos, H Schaffner, M Schlarb, DP Scraggs, D Seddon, M Şenyiǧit, M-H Sigward, G Simpson, J Simpson, M Slee, JF Smith, P Sona, B Sowicki, P Spolaore, C Stahl, T Stanios, E Stefanova, O Stézowski, J Strachan, G Suliman, P-A Söderström, JL Tain, S Tanguy, S Tashenov, C Theisen, J Thornhill, F Tomasi, N Toniolo, R Touzery, B Travers, A Triossi, M Tripon, KMM Tun-Lanoë, M Turcato, C Unsworth, CA Ur, JJ Valiente-Dobon, V Vandone, E Vardaci, R Venturelli, F Veronese, C Veyssiere, E Viscione, R Wadsworth, PM Walker, N Warr, C Weber, D Weisshaar, D Wells, O Wieland, A Wiens, G Wittwer, HJ Wollersheim, F Zocca, NV Zamfir, M Ziȩbliński, A Zucchiatti (2012)AGATA - Advanced GAmma Tracking Array, In: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment668pp. 26-58 Elsevier
T Sumikama, K Yoshinaga, H Watanabe, S Nishimura, Y Miyashita, K Yamaguchi, K Sugimoto, J Chiba, Z Li, H Baba, JS Berryman, N Blasi, A Bracco, F Camera, P Doornenbal, S Go, T Hashimoto, S Hayakawa, C Hinke, E Ideguchi, T Isobe, Y Ito, DG Jenkins, Y Kawada, N Kobayashi, Y Kondo, R Krücken, S Kubono, G Lorusso, T Nakano, M Kurata-Nishimura, A Odahara, HJ Ong, S Ota, Z Podolyák, H Sakurai, H Scheit, K Steiger, D Steppenbeck, S Takano, A Takashima, K Tajiri, T Teranishi, Y Wakabayashi, PM Walker, O Wieland, H Yamaguchi (2012)Search for spin-orbit-force reduction at 106,108Zr around r-process path, In: AIP Conference Proceedings1484pp. 156-160

Shell gap at the magic number N = 82 is important to reproduce the 2nd peak of r-process abundance. If a spin-orbit force is reduced in a very neutron-rich region, a shell quenching at N = 82 and a new shell closure at N = 70 are predicted. A shell evolution by the spin-orbit-force reduction can be searched for through the shape evolution of Zr isotopes around an expected double magic nuclei, 110Zr(Z=40,N=70). We performed β-γ and isomer spectroscopy at RIBF to observe low-lying states in 106,108Zr. The present results indicate a well deformed shape for 106,108Zr. The drastic reduction of the spin-orbit force most likely does not occur around 110Zr on an r-process path. © 2012 American Institute of Physics.

CM Mattoon, F Sarazin, G Hackman, ES Cunningham, RAE Austin, GC Ball, RS Chakrawarthy, P Finlay, PE Garrett, GF Grinyer, B Hyland, KA Koopmans, JR Leslie, AA Phillips, MA Schumaker, HC Scraggs, J Schwarzenberg, MB Smith, CE Svensson, JC Waddington, PM Walker, B Washbrook, E Zganjar (2007)beta decay of Na-32, In: PHYSICAL REVIEW C75(1)ARTN 0pp. ?-? AMERICAN PHYSICAL SOC
AI Morales, G Benzoni, A Gottardo, JJ Valiente-Dobon, N Blasi, A Bracco, F Camera, FCL Crespi, A Corsi, S Leoni, B Million, R Nicolini, O Wieland, A Gadea, S Lunardi, M Gorska, PH Regan, Z Podolyak, M Pfuetzner, S Pietri, P Boutachkov, H Weick, J Grebosz, AM Bruce, J Alcantara Nunez, A Algora, N Al-Dahan, Y Ayyad, N Alkhomashi, PRP Allegro, D Bazzacco, J Benlliure, M Bowry, M Bunce, E Casarejos, ML Cortes, AMD Bacelar, AY Deo, G de Angelis, C Domingo-Pardo, M Doncel, Z Dombradi, T Engert, K Eppinger, GF Farrelly, F Farinon, E Farnea, H Geissel, J Gerl, N Goel, E Gregor, T Habermann, R Hoischen, R Janik, S Klupp, I Kojouharov, N Kurz, S Mandal, R Menegazzo, D Mengoni, DR Napoli, F Naqvi, C Nociforo, A Prochazka, W Prokopowicz, F Recchia, RV Ribas, MW Reed, D Rudolph, E Sahin, H Schaffner, A Sharma, B Sitar, D Siwal, K Steiger, P Strmen, TPD Swan, I Szarka, CA Ur, PM Walker, H-J Wollersheim (2014)beta-decay studies of neutron-rich Tl, Pb, and Bi isotopes, In: PHYSICAL REVIEW C89(1)ARTN 0pp. ?-? AMER PHYSICAL SOC
F. R. Xu, P. M. Walker, R. Wyss (1999)Shape polarizations of two-quasiparticle Kπ = 8- isomeric configurations, In: Physical Review C59pp. 731-734
J.J Valiente-Dobón, A Gottardo, G Benzoni, A Gadea, S Lunardi, A Algora, G de Angelis, D Bazzacco, J Benlliure, A.M Bruce, F Camera, E Casarejos, M.L Cortés, F. C. L Crespi, A Corsi, C Domingo-Pardo, M Doncel, T Engert, H Geissel, J Gerl, A Goasduff, N Goel, M Górska, J Grebosz, E Gregor, T Habermann, S Klupp, I Kojouharov, N Kurz, S. M Lenzi, S Leoni, S Mandal, R Menegazzo, D Mengoni, B Million, A. I Morales, D.R Napoli, F Naqvi, C Nociforo, M Pfützner, S Pietri, ZSOLT PODOLYAK, A Prochazka, F Recchia, P.H Regan, D Rudolph, E Sahin, H Schaffner, A Sharma, B Sitar, D Siwal, P Strmen, I Szarka, C.A Ur, P.M Walker, H Weick, O Wieland, H.‐J Wollersheim, P Van Isacker (2021)Manifestation of the Berry phase in the atomic nucleus 213Pb, In: Physics Letters. B816136183 Elsevier

The neutron-rich 213Pb isotope was produced in the fragmentation of a primary 1 GeV A 238U beam, separated in FRS in mass and atomic number, and then implanted for isomer decay γ-ray spectroscopy with the RISING setup at GSI. A newly observed isomer and its measured decay properties indicate that states in 213Pb are characterized by the seniority quantum number that counts the nucleons not in pairs coupled to angular momentum J=0. The conservation of seniority is a consequence of a geometric phase associated with particle-hole conjugation, which becomes observable in semi-magic nuclei where nucleons half-fill the valence shell. The γ-ray spectroscopic observables in 213Pb are thus found to be driven by two mechanisms, particle-hole conjugation and seniority conservation, which are intertwined through a Berry phase.

E Rapisarda, R Shearman, M Rudigier, M Huyse, M Piersa, T Alexander, P Van Duppen, D S Judson, R Marginean, T Stora, R Lică, P M Walker, R E Mihai, S Stegemann, M Madurga, A Gredley, R D Page, L J Harkness-Brennan, F Rotaru, R Wadsworth, M Brunet, P Rahkila, V Vedia, H O U Fynbo, M Lund, L M Fraile, J R Creswell, T Berry, S Lalkovski, S Ansari, F Wearing, N Warr, S M Judge, V Pucknell, E R Gamba, C Nita, C M Shand, P H Regan, Ch Sotty, A Perea, R J Carroll, Z Patel, A N Andreyev, N Marginean, I H Lazarus, I Marroquin, O Tengblad, M Górska, Zs Podolyák, C Mihai, H Grawe, R B Gerst, M J G Borge, C Fahlander, A Negret, P T Greenlees, J Phrompao, H De Witte, I Kuti, J Kurcewicz, E Nácher, J Konki, S Pascu, W Gelletly, ZSOLT PODOLYAK (2020)Competition between Allowed and First-Forbidden β Decay: The Case of 208Hg → 208Tl, In: Physical review letters125192501 American Physical Society

The β decay of 208Hg into the one-proton hole, one neutron-particle 20881Tl127 nucleus was investigated at CERN-ISOLDE. Shell-model calculations describe well the level scheme deduced, validating the proton-neutron interactions used, with implications for the whole of the N>126, Z

AB Garnsworthy, PH Regan, L Caceres, Y Pietri, Y Sun, D Rudolph, M Gorska, Z Podolyak, SJ Steer, R Hoischen, A Heinz, F Becker, R Bednarczyk, P Doornenbal, H Geissel, J Gerl, H Grawe, J Grebosz, A Kelic, I Kojouharov, N Kurz, F Montes, W Prokopowicz, T Saito, H Schaffner, S Tachenov, E Werner-Malento, HJ Wollersheim, G Benzoni, BB Blank, C Brandau, AM Bruce, F Camera, WN Catford, IJ Cullen, Z Dornbradi, E Estevez, W Gelletly, G Ilie, J Jolie, GA Jones, A Jungclaus, M Kmiecik, FG Kondev, T Kurtukian-Nieto, S Lalkovski, Z Liu, A Maj, S Myalski, M Pfutzner, S Schwertel, T Shizuma, AJ Simons, PM Walker, O Wieland, FR Xu (2008)Neutron-proton pairing competition in N = Z nuclei: Metastable state decays in the proton dripline nuclei (82)(41)Nb and (86)(43)TC (vol 660, pg 326, 2008), In: PHYSICS LETTERS B668(5)pp. 460-460 ELSEVIER SCIENCE BV
PH Regan, N Alkhomashi, N Al-Dahan, Z PodolyÁk, SB Pietri, SJ Steer, AB Garnsworthy, EB Suckling, PD Stevenson, G Farrelly, IJ Cullen, W Gelletly, PM Walker, J Benlliure, AI Morales, E Casajeros, ME Estevez, J Gerl, M GÓrska, HJ Wollersheim, P Boutachkov, S Tashenov, I Kojouharov, H Schaffner, N Kurz, R Kumar, B Rubio, A Algora, F Molina, J Grebosz, G Benzoni, D MÜcher, AM Bruce, AMD Bacelar, S Lalkovski, Y Fujita, A Tamii, R Hoischen, Z Liu, PJ Woods, C Mihai, JJ Valiente-DobÓn (2008)First results with the rising active stopper, In: International Journal of Modern Physics E17(SUPPL.)pp. 8-20
F R Xu, E G Zhao, R Wyss, P M Walker (2004)Enhanced Stability of Superheavy Nuclei Due to High-Spin Isomerism, In: Physical Review Letters92(25)

Configuration-constrained calculations of potential-energy surfaces in even-even superheavy nuclei reveal systematically the existence at low excitation energies of multiquasiparticle states with deformed axially symmetric shapes and large angular momenta. These results indicate the prevalence of long-lived, multiquasiparticle isomers. In a quantal system, the ground state is usually more stable than the excited states. In contrast, in superheavy nuclei the multiquasiparticle excitations decrease the probability for both fission and alpha decay, implying enhanced stability. Hence, the systematic occurrence of multiquasiparticle isomers may become crucial for future production and study of even heavier nuclei. The energies of multiquasiparticle states and their alpha decays are calculated and compared to available data.

P M Walker, F R Xu, D M Cullen (2005)Prolate-Oblate Shape Coexistence at High Spin in Hf-175, In: Physical Review C71(6)

The recent experimental observation of collective rotational bands up to I > 60h in Hf-175 presents theoretical challenges. It is shown here that total Routhian surface calculations are able to explain the yrast high-spin behavior, with collective oblate states favored at I similar to 35h and strongly deformed prolate states at the highest spins. The collective oblate rotation terminates in noncollective prolate states. Comparisons are made with ultimate cranker calculations, and theoretical quadrupole moments are evaluated.

CF Jiao, Y Shi, HL Liu, FR Xu, PM Walker (2015)Shape-coexisting rotation in neutron-deficient Hg and Pb nuclei, In: PHYSICAL REVIEW C91(3)ARTN 0 AMER PHYSICAL SOC
Austyn G. Griffiths, Christopher J. Ashworth, J. Rikovska, N. J. Stone, J. P. White, I. S. Grant, P. M. Walker, W. B. Walters (1992)Magnetic moments and shape coexistence in the light Br isotopes, In: Physical Review C46(2228)pp. 2228-2240
L. K. Pattison, D. M. Cullen, J. F. Smith, A. M. Fletcher, P. M. Walker, H. M. El-Masri, Zs. Podolyák, R. J. Wood, C. Scholey, C. Wheldon, G. Mukherjee, D. Balabanski, M. Djongolov, Th. Dalsgaard, H. Thisgaard, G. Sletten, F. Kondev, D. Jenkins, G. J. Lane, I. -Y. Lee, A. O. Macchiavelli, S. Frauendorf, D. Almehed (2003)Multiphonon Vibrations at High Angular Momentum in 182Os, In: Physical Review Letters91(182501)
P. M Walker, P. D Stevenson (2021)Configuration mixing and K -forbidden E2 decays, In: Physical Review C103(6)064305 American Physical Society

Hindrance factors for K-forbidden E2 decays from multiquasiparticle isomers are analyzed in relation to mixing matrix elements that are often associated with chance near degeneracies, and a functional relationship is established. Focusing on effective matrix elements for ΔK=6 decays from three-quasiparticle isomers, significant configuration dependence is demonstrated.

R.J Carroll, Philip M Walker, Gregory Lane, Matthew Reed, Aqeel Akber, H.M Albers, J.J Carroll, D M Cullen, A.C Dai, C Fahlander, Matthew Gerathy, Sankha Hota, G Lotay, Tibor Kibedi, V Margerin, Alan John Mitchell, Nyaladzi Palalani, Thomas Palazzo, Z Patel, Andrew Stuchbery (2020)γ-ray spectroscopy of a four-quasiparticle isomer band in 174Re, In: Physical Review C101054314 American Physical Society

Excited states in 174Re have been populated in fusion-evaporation reactions at the Australian National University, and γ-ray spectroscopy has been used to determine the level structure and to deduce the underlying nucleon configurations. The half-life of the bandhead of the Kπ=8−band has been measured to be 2.7(4) ns. A band built on an isomeric state of spin-parity (14−) and a half-life of 53(5) ns has been observed here for the first time, and has been determined to have a four-quasiparticle structure. Contrasting reduced-hindrance values for its decay are discussed in terms of deformation and configuration changes, as indicated by configuration-constrained potential energy surface calculations. The technical staff at the ANU 14UD accelerator facility are thanked for their excellent support. Funding is acknowledged from the UK Science and Technology Facilities Council under Grant No. ST/P005314/1Support for the ANU Heavy Ion Accelerator Facility operations through the Australian National Collaborative Research Infrastructure Strategy (NCRIS) program is acknowledged.

F Amirzadeh, A Kardan, P. M Walker, Hai-Liang Ma (2020)Isomeric and collective structures in neutron-rich hafnium isotopes, In: Physical Review. C102(3)

The structures of isomeric and collective states in neutron-rich hafnium isotopes have been investigated within the paired cranked Nilsson-Strutinsky-Bogoliubov (CNSB), and the unpaired cranked Nilsson-Strutinsky (CNS) formalisms. We show that by combining these two models, a good understanding of the formation of multiquasiparticle prolate isomers is achieved. The calculations show at angular momenta I≥35, well-deformed oblate collective rotation strongly competes energetically with the prolate noncollective states. Comparison is made with experimental data, where available, and with other model calculations.

TPD Swan, PM Walker, Z Podolyak, MW Reed, GD Dracoulis, GJ Lane, T Kibedi, ML Smith (2012)Hindered decays from a non-yrast four-quasiparticle isomer in Er-164, In: PHYSICAL REVIEW C86(4)ARTN 0pp. ?-? AMER PHYSICAL SOC
J. J Liu, J Lee, H Watanabe, S Nishimura, G. X Zhang, J Wu, P. M Walker, P. H Regan, P. -A Söderström, H Kanaoka, Z Korkulu, P. S Lee, A Yagi, A. C Dai, F. R Xu, D. S Ahn, T Alharbi, H Baba, F Browne, A. M Bruce, R. J Carroll, K. Y Chae, Zs Dombradi, P Doornenbal, A Estrade, N Fukuda, C Griffin, E Ideguchi, N Inabe, T Isobe, S Kanaya, I Kojouharov, F. G Kondev, T Kubo, S Kubono, N Kurz, I Kuti, S Lalkovski, G. J Lane, C. S Lee, E. J Lee, G Lorusso, G Lotay, C. -B Moon, I Nishizuka, C. R Nita, A Odahara, Z Patel, V. H Phong, Zs Podolyák, O. J Roberts, H Sakurai, H Schaffner, C. M Shand, Y Shimizu, T Sumikama, H Suzuki, H Takeda, S Terashima, Zs Vajta, J. J Valiente-Dobón, Z. Y Xu (2020)Isomeric and beta-decay spectroscopy of 173,174Ho, In: Physical Review. C, Nuclear Physics102(2) American Physical Society (APS)

β-decay spectroscopy of 173,174Ho (Z = 67, N = 106,107) was conducted at Radioactive Isotope Beam Factory at RIKEN by using in-flight fission of a 345-MeV/u 238U primary beam. A previously unreported isomeric state at 405 keV with half-life of 3.7(12) μs and a spin and parity of (3/2+) is identified in 173Ho. Moreover, a new state with a spin and parity of 9- was discovered in 174Er. The experimental log ft values of 5.84(20) and 5.25(18) suggest an allowed-hindered β decay from the ground state of 174Ho to the Kπ = 8- isomeric state in 174Er. Configuration-constrained potential energy surface (PES) calculations were performed and the predictions are in reasonable agreement with the experimental results.

PM Walker, FR Xu (2006)Prediction and possible observation of an oblate shape isomer in W-190, In: PHYSICS LETTERS B635(5-6)pp. 286-289 ELSEVIER SCIENCE BV
A. M. Bruce, P. M. Walker, P. H. Regan, G. D. Dracoulis, A. P. Byrne, T. Kibedi, G. J. Lane, K. C. Yeung (1994)A Kπ=8- isomer in 136Sm, In: Physical Review C50(480)pp. 480-482
N Orce, AM Bruce, A Emmanouilidis, AP Byrne, GD Dracoulis, JC Hazel, T Kibedi, PM Walker, Z Podolyak, M Caamano, H El-Masri, C Wheldon, DM Cullen (2002)Study of the K-pi=8(-) isomeric decay in the N=74 isotone Xe-128, In: PROGRESS OF THEORETICAL PHYSICS SUPPLEMENT(146)pp. 611-612
Zs. Podolyák, S. Al-Garni, R. F. Casten, J. R. Cooper, D. M. Cullen, A. Dewald, R,. Krucken, H. Newman, J. N. Orce, C. J. Pearson, C. Ur, R. Venturelli, S. Vincent, C. Wheldon, P. M. Walker, F. R. Xu, A. Yamamoto, N. V. Zamfir (2002)Deviations from axial symmetry in 181Os, In: Physical Review C66(011304)

H L Liu, F R Xu, S W Xu, R Wyss, P M Walker (2007)High-Spin Isomeric Structures in Exotic Odd-Odd Nuclei: Exploration of the Proton Drip Line and Beyond, In: Physical Review C76(3)

We investigate the role of two-quasiparticle isomeric states along the proton drip line, using configuration-constrained potential-energy-surface calculations. In contrast to even-even nuclei, odd-odd nuclei can have coexisting low-lying two-quasiparticle states. The low excitation energy and high angular momentum can lead to long-lived isomers. Also, because of the hindrance by spin selection, the probabilities of beta and proton decays from high-spin isomers can be reduced significantly. The present calculations reproduce reasonably well the available data for observed isomers in such nuclei. Unobserved high-spin isomers are predicted, which could be useful for future experimental studies of exotic nuclei at and beyond the proton drip line.

Yang Sun, G.X. Zhang, H. Watanabe, F.G. Kondev, G.J. Lane, P.H. Regan, P.-A. Söderström, P.M. Walker, H. Kanaoka, Z. Korkulu, P.S Lee, J.J Liu, S. Nishimura, J. Wu, A. Yagi, D.S. Ahn, T. Alharbi, H. Baba, F. Browne, A.M. Bruce, R.J. Carroll, K.Y. Chae, Zs. Dombradi, P. Doornenbal, A. Estrade, N. Fukuda, C. Griffin, E. Ideguchi, N. Inabe, T. Isobe, S. Kanaya, I. Kojouharov, T. Kubo, S. Kubono, N. Kurz, I. Kuti, S. Lalkovski, C.S. Lee, E.J. Lee, G. Lorusso, G. Lotay, C.-B Moon, I. Nishizuka, C.R. Nita, A. Odahara, Z. Patel, V.H. Phong, Zs. Podolyak, O.J. Roberts, H. Sakurai, H. Schaffner, C.M. Shand, Y. Shimizu, T. Sumikama, H. Suzuki, H. Takeda, S. Terashima, Zs. Vajta, J.J. Valiente-Dóbon, Z.Y. Xu (2018)β-γ and isomeric decay spectroscopy of 168Dy, In: EPJ Web of Conferences178pp. 02023-1 EDP Sciences

This contribution will report on the experimental work on the level structure of 168Dy. The experimental data have been taken as part of the EURICA decay spectroscopy campaign at RIBF, RIKEN in November 2014. In the experiment, a 238U primary beam is accelerated up to 345 MeV/u with an average intensity of 12 pnA. The nuclei of interest are produced by in-flight fission of 238U impinging on Be target with a thickness of 5 mm. The excited states of 168Dy have been populated through the decay from a newly identified isomeric state and via the β decay from 168Tb. In this contribution, scientific motivations, experimental procedure and some preliminary results for this study are presented.

N Al-Dahan, Z Podolyák, PH Regan, SJ Steer, AMD Bacelar, N Alkhomashi, M Górska, J Gerl, HJ Wollersheim, SB Pietri, H Grawe, AY Deo, G Farrelly, P Boutachkov, C Domingo-Pardo, A Algora, J Benlliure, A Bracco, AM Bruce, E Calore, E Casarejos, IJ Cullen, P Detistov, Z Dombrádi, M Doncel, F Farinon, H Geissel, W Gelletly, N Goel, J Grebosz, R Hoischen, I Kojouharov, N Kurz, S Lalkovski, S Leoni, F Molina, D Montanari, AI Morales, A Musumarra, DR Napoli, R Nicolini, C Nociforo, A Prochazka, W Prokopowicz, B Rubio, D Rudolph, H Schaffner, P Strmen, I Szarka, T Swan, JJ Valiente-Dobon, S Verma, PM Walker, H Weick (2009)Isomeric states in 208Hg and 209Tl populated in fragmentation of 238U, In: Acta Physica Polonica B40(3)pp. 871-874 Jagellonian University

The nuclear structure of neutron-rich N > 126 nuclei has been investigated following their production via relativistic projectile fragmentation of a E/A = 1 GeV (238)U beam on a Be target. The preliminary analysis indicates the presence of previously unreported isomeric states in the N = 128 isotones (208)Hg and (209)Tl.

P. M. Walker, F. R. Xu, D. M. Cullen (2005)Prolate-oblate shape coexistence at high spin in 175Hf, In: Physical Review C71(067303)
S Lalkovski, AM Bruce, A Jungclaus, M Gorska, M Pfuetzner, L Caceres, F Naqvi, S Pietri, Z Podolyak, GS Simpson, K Andgren, P Bednarczyk, T Beck, J Benlliure, G Benzoni, E Casarejos, B Cederwall, FCL Crespi, JJ Cuenca-Garcia, IJ Cullen, AMD Bacelar, P Detistov, P Doornenbal, GF Farrelly, AB Garnsworthy, H Geissel, W Gelletly, J Gerl, J Grebosz, B Hadinia, M Hellstrom, C Hinke, R Hoischen, G Ilie, G Jaworski, J Jolie, A Khaplanov, S Kisyov, M Kmiecik, I Kojouharov, R Kumar, N Kurz, A Maj, S Mandal, V Modamio, F Montes, S Myalski, M Palacz, W Prokopowicz, P Reiter, PH Regan, D Rudolph, H Schaffner, D Sohler, SJ Steer, S Tashenov, J Walker, PM Walker, H Weick, E Werner-Malento, O Wieland, HJ Wollersheim, M Zhekova (2013)Core-coupled states and split proton-neutron quasiparticle multiplets in Ag122-126, In: PHYSICAL REVIEW C87(3)ARTN 0pp. ?-? AMER PHYSICAL SOC
L Chen, PM Walker, H Geissel, YA Litvinov, K Beckert, P Beller, F Bosch, D Boutin, L Caceres, JJ Carroll, DM Cullen, IJ Cullen, B Franzke, J Gerl, M Gorska, GA Jones, A Kishada, R Knoebel, C Kozhuharov, J Kurcewicz, SA Litvinov, Z Liu, S Mandal, F Montes, G Muenzenberg, F Nolden, T Ohtsubo, Z Patyk, WR Plass, Z Podolyak, S Rigby, N Saito, T Saito, C Scheidenberger, EC Simpson, M Shindo, M Steck, B Sun, SJ Williams, H Weick, M Winkler, H-J Wollersheim, T Yamaguchi (2013)Direct Observation of Long-Lived Isomers in Bi-212, In: PHYSICAL REVIEW LETTERS110(12)ARTN 1pp. ?-? AMER PHYSICAL SOC
J N Orce, A M Bruce, A Emmanouilidis, A P Byrne, G D Dracoulis, T Kibedi, M Caamano, H El-Masri, C J Pearson, Z Podolyak, P D Stevenson, P M Walker, F R Xu, D M Cullen, C Wheldon (2006)Shape-Driving Effects in the Triaxial Nucleus, Xe-128, In: Physical Review C74(3)

An extended decay scheme for Xe-128 has been constructed by using data from the Sn-124(Be-9, 5n)Xe-128 reaction at a beam energy of 58 MeV. Bands have been identified as being built on several intrinsic states, including a proposed 9/2(-)[514] circle times 1/2(+)[400] two-quasineutron configuration that forms the K-pi=5(-) intrinsic state at 2228 keV, and on a previously assigned K-pi=8(-) intrinsic state at 2786 keV. A half-life of 73(3) ns has been measured for the latter. Theoretical calculations have been performed by using the configuration-constrained blocking method based on a nonaxial Woods-Saxon potential. Large gamma deformation and gamma softness are predicted for the ground state and the K-pi=5(-) intrinsic state, whereas a nearly axially symmetric shape is predicted for the K-pi=8(-) two-quasiparticle configuration. The low value of the hindrance factor for the E1 transition depopulating the K-pi=8(-) intrinsic state is discussed in the context of analogous transitions in neighbouring N=74 isotones.

F. R. Xu, R. Wyss, P. M. Walker (1999)Mean-field and blocking effects on odd-even mass differences and rotational motion of nuclei, In: Physical Review C60(051301)

The odd-even differences of nuclear masses are strongly influenced by mean-field and odd-nucleon blocking effects. When such effects are taken into account, the determination of the pairing interaction strength needs to be modified, resulting in larger pairing gaps. This method leads to an improved description for both moments of inertia and backbending frequencies of rotational bands, with no additional parameters.

Y. Sun, X.-R. Zhou, G. - L. Long, En.-G. Zhao, P. M. Walker (2004)Nuclear structure of 178Hf related to the spin-16, 31-year isomer, In: Physics Letters B589(3-4)pp. 83-88

The projected shell model is used to study the multi-quasiparticle and collective excitations of 178Hf. With an axially symmetric basis, the spin-16 isomer at 2.4 MeV appears to be well separated in energy/spin space from other configurations. However, projected energy surface calculations suggest that 178Hf has significant softness to axially asymmetric shapes, which can strongly modify the level distribution. The implications for photodeexcitation of the isomer are discussed.

G A Jones, P H Regan, P M Walker, Z Podolyak, P D Stevenson, M P Carpenter, J J Carroll, R S Chakrawarthy, P Chowdhury, A B Garnsworthy, R V Janssens, T L Khoo, F G Kondev, G J Lane, Z Liu, D Seweryniak, N J Thompson, S Zhu, S J Williams (2007)Identification of a High-Spin Isomer in Mo-99, In: Physical Review C76(4)

A previously unreported isomer has been identified in Mo-99 at an excitation energy of E-x = 3010 keV, decaying with a half-life of T-1/2 = 8(2) ns. The nucleus of interest was produced following fusion-fission reactions between a thick Al-27 target frame and a Hf-178 beam at a laboratory energy of 1150 MeV. This isomeric state is interpreted as an energetically favored, maximally aligned configuration of nu h (11/2) circle times pi(g (9/2))(2).

M Lestinsky, V Andrianov, B Aurand, V Bagnoud, D Bernhardt, H Beyer, S Bishop, K Blaum, A Bleile, A Borovik, F Bosch, CJ Bostock, C Brandau, A Braeuning-Demian, I Bray, T Davinson, B Ebinger, A Echler, P Egelhof, A Ehresmann, M Engstroem, C Enss, N Ferreira, D Fischer, A Fleischmann, E Foerster, S Fritzsche, R Geithner, S Geyer, J Glorius, K Goebel, O Gorda, J Goullon, P Grabitz, R Grisenti, A Gumberidze, S Hagmann, M Heil, A Heinz, F Herfurth, R Hess, P-M Hillenbrand, R Hubele, P Indelicato, A Kaellberg, O Kester, O Kiselev, A Knie, C Kozhuharov, S Kraft-Bermuth, T Kuehl, G Lane, YA Litvinov, D Liesen, XW Ma, R Maertin, R Moshammer, A Mueller, S Namba, P Neumeyer, T Nilsson, W Noertershaeuser, G Paulus, N Petridis, M Reed, R Reifarth, P Reiss, J Rothhardt, R Sanchez, MS Sanjari, S Schippers, HT Schmidt, D Schneider, P Scholz, R Schuch, M Schulz, V Shabaev, A Simonsson, J Sjoholm, O Skeppstedt, K Sonnabend, U Spillmann, K Stiebing, M Steck, T Stohlker, A Surzhykov, S Torilov, E Trabert, M Trassinelli, S Trotsenko, XL Tu, I Uschmann, PM Walker, G Weber, DFA Winters, PJ Woods, HY Zhao, YH Zhang (2016)Physics book: CRYRING@ESR, In: EUROPEAN PHYSICAL JOURNAL-SPECIAL TOPICS225(5)pp. 797-882 SPRINGER HEIDELBERG
P. M. Walker, G. Sletten, N. L. Gjorup, M. A. Bentley, J. Borggreen, B. Fabricius, A. Holm, D. Howe, J. Pedersen, J. W. Roberts, J. F. Sharpey-Schafer (1990)High-K barrier penetration in 174Hf: A challenge to K selection, In: Physical Review Letters65(416)pp. 416-419
PM Walker, KC Yeung, GD Dracoulis, PH Regan, GJ Lane, PM Davidson, AE Stuchbery (1993)Backbending in 180W: a t-band crossing, In: Physics Letters B309(1-2)pp. 17-22

A Fermi-aligned (i 13 2)2 rotational band, with K≈8, has been observed in an even-even nucleus, 180W. Its structure corresponds to a t-band in the tilted-cranking representation. It crosses the ground-state band at I = 16 h {combining short stroke overlay}, giving rise to backbending in the yrast sequence. Contrary to the usual interpretation, backbending in this case is not caused by the s-band. Comparison is made with other possible t-band crossings in the A ≈ 180 region. © 1993.

D. M. Cullen, S. L. King, A. T. Reed, J. A. Sampson, P. M. Walker, C. Wheldon, F. R. Xu, G. D. Dracoulis, I. -Y. Lee, A. O. Macchiavelli, R. W. MacLeod, A. N. Wilson, C. Barton (1999)High-K multiquasiparticle configurations and limiting moments of inertia in 178W, In: Physical Review C60(064301)
MW Reed, PM Walker, IJ Cullen, YA Litvinov, K Blaum, F Bosch, C Brandau, JJ Carroll, DM Cullen, AY Deo, B Detwiler, C Dimopoulou, GD Dracoulis, F Farinon, H Geissel, E Haettner, M Heil, RS Kempley, R Knoebel, C Kozhuharov, J Kurcewicz, N Kuzminchuk, S Litvinov, Z Liu, R Mao, C Nociforo, F Nolden, WR Plass, A Prochazka, C Scheidenberger, D Shubina, M Steck, T Stoehlker, B Sun, TPD Swan, G Trees, H Weick, N Winckler, M Winkler, PJ Woods, T Yamaguchi, S Freeman, A Andreyev, A Bruce, A Deacon, D Jenkins, D Joss, D MacGregor, P Regan, J Simpson, G Tungate, R Wadsworth, D Watts (2012)Technique for Resolving Low-lying Isomers in the Experimental Storage Ring (ESR) and the Occurrence of an Isomeric State in Re-192, In: RUTHERFORD CENTENNIAL CONFERENCE ON NUCLEAR PHYSICS, 2011381pp. ?-?
GD Dracoulis, Philip Walker, FG Kondev (2016)Review of Metastable States in Heavy Nuclei, In: Reports on Progress in Physics79(7) IOP Publishing

The structure of nuclear isomeric states is reviewed in the context of their role in contemporary nuclear physics research. Emphasis is given to high-spin isomers in heavy nuclei, with A & 150. The possibility to exploit isomers to study some of the most exotic nuclei is a recurring theme. In spherical nuclei, the role of octupole collectivity is discussed in detail, while in deformed nuclei the limitations of the K quantum number are addressed. Isomer targets and isomer beams are considered, along with applications related to energy storage, astrophysics, medicine, and experimental advances.

PM Walker, FR Xu (2016)High-K isomerism in rotational nuclei, In: PHYSICA SCRIPTA91(1)ARTN 01301 IOP PUBLISHING LTD
AB Garnsworthy, NJ Thompson, Z Podolyak, PM Walker, SJ Williams, GD Dracoulis, G de France, GJ Lane, K Andgren, AM Bruce, AP Byrne, WN Catford, B Cederwall, GA Jones, B McGuirk, S Mandal, ES Paul, V Pucknell, N Redon, B Rosse, RJ Senior, G Sletten (2005)Spectroscopy of Po-212 and At-213 using a He-8 radioactive beam and EXOGAM, In: JOURNAL OF PHYSICS G-NUCLEAR AND PARTICLE PHYSICS31(10)pp. S1851-S1854
TR Saitoh, N Saitoh-Hashimoto, G Sletten, RA Bark, M Bergstrom, P Regan, S Tormanen, PG Varmette, PM Walker (1999)Collective and intrinsic structures in W-183, In: NUCLEAR PHYSICS A660(2)pp. 171-196 ELSEVIER SCIENCE BV
A Akber, MW Reed, PM Walker, YA Litvinov, GJ Lane, T Kibedi, K Blaum, F Bosch, C Brandau, JJ Carroll, DM Cullen, IJ Cullen, AY Deo, B Detwiler, C Dimopoulou, GD Dracoulis, F Farinon, H Geissel, E Haettner, M Heil, RS Kempley, R Knoebel, C Kozhuharov, J Kurcewicz, N Kuzminchuk, S Litvinov, Z Liu, R Mao, C Nociforo, F Nolden, WR Plass, Z Podolyak, A Prochazka, C Scheidenberger, D Shubina, M Steck, T Stoehlker, B Sun, TPD Swan, G Trees, H Weick, N Winckler, M Winkler, PJ Woods, T Yamaguchi (2015)Increased isomeric lifetime of hydrogen-like Os-192m, In: PHYSICAL REVIEW C91(3)ARTN 0pp. ?-? AMER PHYSICAL SOC
G A Jones, S J Williams, P M Walker, Z Podolyak, S Zhu, M P Carpenter, J J Carroll, R S Chakrawarthy, P Chowdhury, I J Cullen, G D Dracoulis, A B Garnsworthy, G Hackman, R V Janssens, T L Khoo, F G Kondev, G J Lane, Z Liu, D Seweryniak, N J Thompson (2008)High-Spin, Multiparticle Isomers in Sb-121,Sb-123, In: Physical Review C77(3)

Isomers in near-spherical Z = 51, antimony isotopes are reported here for the first time using fusion-fission reactions between Al-27 and a pulsed Hf-178 beam of energy, 1150 MeV. gamma rays were observed from the decay of isomeric states with half-lives, T-1/2 = 200(30) and 52(3) mu s, and angular momenta I = (25/2) and I-pi = 23(+)/2, in Sb-121,Sb-123, respectively. These states are proposed to correspond to nu(h(11/2))(2) configurations, coupled to an odd d(5/2) or g(7/2) proton. Nanosecond isomers were also identified at I-pi = 19(-)/2 [T-1/2 = 8.5(5) ns] in Sb-121 and I-pi = (15(-)/2) [T-1/2 = 37(4) ns] in Sb-123. Information on spins and parities of states in these nuclei was obtained using a combination of angular correlation and intensity-balance measurements. The configurations of states in these nuclei are discussed using a combination of spin/energy systematics and shell-model calculations for neighboring tin isotones and antimony isotopes.

E Wilson, Z Podolyak, H Grawe, BA Brown, CJ Chiara, S Zhu, B Fornal, RVF Janssens, CM Shand, M Bowry, M Bunce, MP Carpenter, N Cieplicka-Orynczak, AY Deo, GD Dracoulis, CR Hoffman, RS Kempley, FG Kondev, GJ Lane, T Lauritsen, G Lotay, MW Reed, PH Regan, CR Triguero, D Seweryniak, B Szpak, PM Walker (2015)Core excitations across the neutron shell gap in Tl-207, In: PHYSICS LETTERS B747pp. 88-92 ELSEVIER SCIENCE BV

The single closed-neutron-shell, one proton-hole nucleus 207Tl was populated in deep-inelastic collisions of a 208Pb beam with a 208Pb target. The yrast and near-yrast level scheme has been established up to high excitation energy, comprising an octupole phonon state and a large number of core excited states. Based on shell-model calculations, all observed single core excitations were established to arise from the breaking of the N=126 neutron core. While the shell-model calculations correctly predict the ordering of these states, their energies are compressed at high spins. It is concluded that this compression is an intrinsic feature of shell-model calculations using two-body matrix elements developed for the description of two-body states, and that multiple core excitations need to be considered in order to accurately calculate the energy spacings of the predominantly three-quasiparticle states.

TR Saitoh, N Saitoh-Hashimoto, G Sletten, RA Bark, M Bergstrom, P Regan, S Tormanen, PG Varmette, PM Walker, C Wheldon (2000)Collective and intrinsic structures in W-183 (vol 660, pg 171, 1999), In: NUCLEAR PHYSICS A669(3-4)pp. 381-406 ELSEVIER SCIENCE BV
Laila Gurgi, Patrick Regan, P-A Söderström, H Watanabe, Philip Walker, Zsolt Podolyak, S Nishimura, Thomas Berry, P Doornenbal, G Lorusso, T Isobe, H Baba, ZY Xu, H Sakurai, T Sumikama, Wilton Catford, AM Bruce, F Browne, GJ Lane, FG Kondev, A Odahara, J Wu, HL Liu, FR Xu, Z Korkulu, P Lee, JJ Liu, VH Phong, A Yagi, GX Zhang, T Alharbi, RJ Carroll, KY Chae, Z Dombradi, A Estrade, N Fukuda, C Griffin, E Ideguchi, N Inabe, H Kanaoka, I Kojouharov, T Kubo, S Kubono, N Kurz, I Kuti, S Lalkovski, EJ Lee, CS Lee, Gavin Lotay, CB Moon, I Nishizuka, CR Nita, Z Patel, OJ Roberts, H Schaffner, Callum Shand, H Suzuki, H Takeda, S Terashima, Z Vajta, S Kanaya, J-J Valiente-Dobón (2017)Isomer Spectroscopy of Neutron-rich 165,167Tb, In: Acta Physica Polonica B48(3)pp. 601-608

We present information on the excited states in the prolate-deformed, neutron-rich nuclei 165;167Tb100;102. The nuclei of interest were synthesised following in-flight fission of a 345 MeV per nucleon 238U primary beam on a 2 mm 9Be target at the Radioactive Ion-Beam Factory (RIBF), RIKEN, Japan. The exotic nuclei were separated and identified event-by-event using the BigRIPS separator, with discrete energy gamma-ray decays from isomeric states with half-lives in the s regime measured using the EURICA gamma-ray spectrometer. Metastable-state decays are identified in 165Tb and 167Tb and interpreted as arising from hindered E1 decay from the 7 2 [523] single quasi-proton Nilsson configuration to rotational states built on the 3 2 [411] single quasi-proton ground state. These data correspond to the first spectroscopic information in the heaviest, odd-A terbium isotopes reported to date and provide information on proton Nilsson configurations which reside close to the Fermi surface as the 170Dy doubly-midshell nucleus is approached.

N Alkhomashi, PH Regan, Z Podolyak, S Pietri, AB Garnsworthy, SJ Steer, J Benlliure, E Caserejos, RF Casten, J Gerl, HJ Wollersheim, J Grebosz, G Farrelly, M Gorska, I Kojouharov, H Schaffner, A Algora, G Benzoni, A Blazhev, P Boutachkov, AM Bruce, AMD Bacelar, IJ Cullen, L Caceres, P Doornenbal, ME Estevez, Y Fujita, W Gelletly, R Hoischen, R Kumar, N Kurz, S Lalkovski, Z Liu, C Mihai, F Molina, AI Morales, D Muecher, W Prokopowicz, B Rubio, Y Shi, A Tamii, S Tashenov, JJ Valiente-Dobon, PM Walker, PJ Woods, FR Xu (2009)beta(-)-delayed spectroscopy of neutron-rich tantalum nuclei: Shape evolution in neutron-rich tungsten isotopes, In: PHYSICAL REVIEW C80(6)ARTN 0pp. ?-? AMER PHYSICAL SOC
H M El-Masri, P M Walker, G D Dracoulis, T Kibedi, A P Byrne, A M Bruce, J N Orce, A Emmanouilidis, D M Cullen, C Wheldon, F R Xu (2005)High-K States in the Odd-Odd Nuclide Re-180, In: Physical Review C72(5)

The structure of the deformed, doubly odd nuclide Re-180 has been studied by gamma-ray and conversion-electron spectroscopy using the Yb-174(B-11,5n) reaction with a pulsed 71 MeV beam of B-11 ions. Several of the previously known intrinsic states have been given revised spin and parity assignments. Rotational bands are observed with K-pi=(4(+)),(5(-)),(7(+)),8(+),9(-),13(+),14(-),15(-),16(+),21(-), and (22(+)). Among these, a four-quasiparticle t band is identified, which is already energetically favored at its bandhead compared to the corresponding two-quasiparticle band; and two six-quasiparticle bands are identified and associated with a tau=13 mu s isomer. The observed structures, including g factors and alignments, are interpreted with the aid of Nilsson-plus-BCS calculations and configuration-constrained potential energy surface calculations. Reduced-hindrance values are obtained for K-forbidden transitions, illustrating the important role of the K quantum number for near-yrast isomers.

B Sun, YA Litvinov, PM Walker, K Beckert, P Beller, F Bosch, D Boutin, C Brandau, L Chen, C Dimopoulou, H Geissel, R Knoebel, C Kozhunharov, J Kurcewicz, SA Litvinov, M Mazzocco, J Meng, C Nociforo, F Nolden, WR Plass, C Scheidenberger, M Steck, H Weick, M Winkler (2007)Discovery of a new long-lived isomeric state in Ce-125, In: EUROPEAN PHYSICAL JOURNAL A31(3)pp. 393-394 SPRINGER
AK Rath, PM Walker, CR Praharaj, FR Xu (2006)K=6(+) isomers in Hf, Yb and W nuclei, In: INTERNATIONAL JOURNAL OF MODERN PHYSICS E-NUCLEAR PHYSICS15(7)pp. 1653-1663
Philip Walker (2017)Isomer building blocks and K-forbidden decays, In: Physica Scripta92(5)054001 IOP Publishing

High-K isomers are long-lived excitations of deformed atomic nuclei. Their structure is built from broken nucleon pairs that generate high angular momentum, K, along the nuclear symmetry axis. The partial conservation of this quantity leads to strong inhibition of electromagnetic decay, and hence to isomerism. The present work examines the hindrance factors for a range of multipole orders, with a focus on highly K-forbidden E1 transitions from multi-quasiparticle isomers in the A ~ 170 region of nuclei. Allowing for a general 104 inhibition of E1 transitions, there is good accord with other multipole orders. A key feature is that the inhibition declines for isomers that are more highly excited, relative to a rigid rotor of the same total angular momentum. Comparison is also made with K-forbidden E1 transitions in the quasicontinuum, and similar inhibition properties are found.

N Al-Dahan, Z Podolyak, PH Regan, SJ Steer, N Alkhomashi, AMD Bacelar, M Gorska, SB Pietri, W Gelletly, PM Walker, G Farrelly, AI Morales, AY Deo, IJ Cullen, J Gerl, C Domingo-Pardo, S Verma, T Swan, HJ Wollersheim, AM Bruce, S Lalkovski, J Benlliure, A Algora, P Boutachkov, A Bracco, E Calore, E Casarejos, P Detistov, Z Dombradi, M Doncel, F Farinon, H Geissel, N Goel, J Grebosz, R Hoischen, I Kojouharov, S Leoni, F Molina, D Montanari, A Musumarra, R Nicolini, DR Napoli, C Nociforo, B Rubio, A Prochazka, D Rudolph, P Strmen, I Szarka, JJ Valiente-Dobon, H Weick, A Blazhev, J Jolie, N Warr, A Zilges (2009)Structure of N >= 126 nuclei produced in fragmentation of (238)U, In: CAPTURE GAMMA-RAY SPECTROSCOPY AND RELATED TOPICS1090pp. 145-148
E Wilson, Z Podolyak, B Fornal, RVF Janssens, M Bowry, M Bunce, MP Carpenter, CJ Chiara, N Cieplicka, AY Deo, GD Dracoulis, H Grawe, CR Hoffman, RS Kempley, FG Kondev, GJ Lane, T Lauritsen, MW Reed, PH Regan, CR Triguero, B Szpak, PM Walker, S Zhu (2013)CORE EXCITATIONS ACROSS THE NEUTRON SHELL GAP IN Tl-207, In: ACTA PHYSICA POLONICA B44(3)pp. 381-385 WYDAWNICTWO UNIWERSYTETU JAGIELLONSKIEGO

Deep-inelastic collisions of a 208Pb beam on a 208Pb target were performed using the ATLAS accelerator at Argonne National Laboratory. Prompt and delayed γ-rays from the reaction products were detected using the GAMMASPHERE detector array. The cross-coincidence method was used to identify transitions in 207Tl, by gating on γ-rays from its better-characterised reaction partner 209Bi. A number of new transitions were found in 207Tl.

Rachael Wood, Philip Walker, GJ Lane, RJ Carroll, DM Cullen, GD Dracoulis, SS Hota, T Kibédi, N Palalani, Zsolt Podolyak, MW Reed, K Schiffl, AM Wright (2017)Three-quasiparticle isomer in 173Ta and the excitation energy dependence of K-forbidden transition rates, In: Physical Review C95054308 American Physical Society

Using the 168Er(10B,5n) reaction at a beam energy of 68 MeV, new data have been obtained for the population and decay of a T1/2 = 148 ns, Kπ = 21/2− three-quasiparticle isomer at 1717 keV in 173Ta. Revised decay energies and intensities have been determined, together with newly observed members of a rotational band associated with the isomer. By comparison with other isomers in the A ≈ 180 deformed region, the 173Ta isomer properties help to specify the key degrees of freedom that determine K-forbidden transition rates. In particular, when all three quasiparticles are of the same nucleon type, there is a strong dependence of the E2 reduced hindrance factor on the isomer excitation energy.

YA Litvinov, H Geissel, K Beckert, P Beller, F Bosch, D Boutin, C Brandau, L Chen, I Cullen, C Dimopoulou, B Fabian, M Hausmann, O Klepper, R Knobel, C Kozhuharov, J Kurcewicz, SA Litvinov, Z Liu, M Mazzocco, F Montes, G Munzenberg, A Musumarra, S Nakajima, C Nociforo, F Nolden, T Ohtsubo, A Ozawa, Z Patyk, W Plass, C Scheidenberger, M Steck, B Sun, T Suzuki, PM Walker, H Weick, C Scheidenberger, M Steck, B Sun, T Suzuki, PM Walker, H Weick, N Winckler, M Winckler, T Yamaguchi (2007)Status of the experimental program on mass measurements of stored exotic nuclei at the FRS-ESR facility, In: NUCLEAR PHYSICS A787pp. 315C-320C ELSEVIER SCIENCE BV

Schottky Mass Spectrometry (SMS) and Isochronous Mass Spectrometry (IMS) have been successfully applied for direct mass measurements of exotic nuclides at FRS-ESR facility at GSI. Both experimental methods are sensitive to single stored ions and can cover very efficiently a large number of nuclides in one run. Presently, more than 1100 masses of different nuclides have been covered by SMS and IMS in several FRS-ESR experiments whereby about 350 of them have been determined for the first time. In this paper, we present the status of our experimental program and use the experimental mass values to test the predictive power of modern mass models.

M. Riley, MK Djongolov, AO Evans, DJ Hartley, RVF Janssens, ES Paul, A Pipidis, J Simpson, AA Aguilar, DE Appelbe, CR Bingham, DB Campbell, MP Carpenter, P Chowdhury, PTW Choy, RM Clark, M Cromaz, DM Cullen, M Danchev, GD Dracoulis, P Fallon, A Gorgen, GB Hagemann, DT Joss, J Goon, RA Kaye, TL Khoo, FG Kondev, RW Laird, K Lagergren, T Lauritsen, AO Macchiavelli, B McClain, EF Moore, G Mukherjee, E Ngijoi-Yogo, PJ Nolan, HI Park, LL Riedinger, G Sletten, SK Tandel, PM Walker, D Ward, I Ragnarsson, F Saric, JY Zhang (2006)Observation of states beyond band termination in Er-156,Er-157,Er-158 and strongly deformed structures in Hf-173,Hf-174,Hf-175, In: PHYSICA SCRIPTAT125pp. 123-126 ROYAL SWEDISH ACAD SCIENCES

High-spin terminating bands in heavy nuclei were first identified in nuclei around Er-158(90). While examples of terminating states have been identified in a number of erbium isotopes, almost nothing is known about the states lying beyond band termination. In the present work, the high-spin structure of Er-156,Er-157,Er-158 has been studied using the Gammasphere spectrometer. The subject of triaxial superdeformation and 'wobbling' modes in Lu nuclei has rightly attracted a great deal of attention. Very recently four strongly or superdeformed (SD) sequences have been observed in Hf-174, and cranking calculations using the Ultimate Cranker code predict that such structures may have significant triaxial deformation. We have performed two experiments in an attempt to verify the possible triaxial nature of these bands. A lifetime measurement was performed to confirm the large (and similar) deformation of the bands. In addition, a high-statistics, thin-target experiment took place to search for linking transitions between the SD bands, possible wobbling modes, and new SD band structures.

PM Walker, FR Xu (2006)Isomers in the region of neutron-rich Hf-188, In: ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY231
C. Lizarazo, P.A Soderstrom, V. Werner, N. Pietralla, P. Walker, G.X Dong, F.R Xu, T.R Rodriguez, F. Browne, P. Doornenbal, S. Nishimura, C.R Nita, A. Obertelli, T. Ando, T. Arici, G. Authelet, H. Baba, A. Blazhev, A.M Bruce, D. Calvet, R.J Caroll, F. Chateau, S. Chen, L.X Chung, A. Corsi, M.L Cortes, A. Delbart, M. Dewald, B. Ding, F. Flavigny, S. Franchoo, J. Gerl, J.M Gheller, A. Giagnon, A. Gillibert, M. Gorska, A. Gottardo, I. Kojouharov, N. Kurz, V. Lapoux, J. Lee, M. Lettmann, B.D Linh, J.J Liu, Z. Liu, S. Momiyama, K. Moschner, T. Motobayashi, S. Nagamine, N. Nakatsuka, M. Niikura, C. Nobs, L. Olivier, Z. Patel, N. Paul, Zsolt Podolyak, J.Y Rousse, M. Rudigier, T.Y Saito, H. Sakurai, C. Santamaria, H. Schaffner, C. Shand, I. Stefan, D. Steppenbeck, R. Taniuchi, T. Uesaka, V. Vaquero, K. Wimmer, Z. Xu (2020)Identification of an oblate K-isomer of 94Se60 and implications for a ground-state shape transition between N = 58 - 60, In: Physical Review Letters American Physical Society

In this letter we report on new information on the shape evolution of the very neutron-rich 92;94Se nuclei from an isomer-decay spectroscopy experiment at the Radioactive Isotope Beam Factory at RIKEN. High-resolution germanium detectors were used to identify delayed -rays emitted following the decay of these nuclei. New transitions are reported extending the previously known level schemes. The isomeric levels are interpreted as originating from high-K quasi-neutron states with an oblate deformation of B ~ - 0:25, with the high-K state in 94Se being metastable and K hindered. Following this, 94Se is the lowest-mass nucleus known to date with K-forbidden decay and a substantial K hindrance. Furthermore, it is the first observation of an oblate K isomer in a deformed nucleus. From the decay patterns, an oblate deformation is suggested for the 94Se60 ground-state band, in line with the predictions of recent beyond-mean-field calculations.

P Walker, A Stuchbery, F Kondev (2014)George Dionisios Dracoulis obituary, In: PHYSICS TODAY67(11)pp. 66-66 AMER INST PHYSICS
PM Walker, RC Johnson (2007)Two-proton radioactivity - Caught in the act, In: NATURE PHYSICS3(12)pp. 836-837 NATURE PUBLISHING GROUP
R Knöbel, SA Litvinov, B Sun, K Beckert, P Beller, F Bosch, D Boutin, C Brandau, L Chen, IJ Cullen, C Dimopoulou, A Dolinskii, B Fabian, H Geissel, M Hausmann, C Kozhuharov, J Kurcewicz, YA Litvinov, Z Liu, M Mazzocco, F Montes, G Münzenberg, A Musumarra, S Nakajima, C Nociforo, F Nolden, T Ohtsubo, A Ozawa, Z Patyk, WR Plaß, C Scheidenberger, M Shindo, M Steck, T Suzuki, PM Walker, H Weick, N Winckler, M Winkler, T Yamaguchi (2007)New developments for isochronous mass measurements of short-lived nuclei, In: AIP Conference Proceedings891pp. 199-204

The combination of the in-flight separator FRS and the storage-ring ESR at GSI offers unique possibilities for high accuracy mass and lifetime measurements of bare and few-electron fragments. Operating the ESR in the isochronous mode allows for measurements of revolution frequencies of stored ions without cooling. Isochronous Mass Spectrometry (IMS) can be applied to fragments with half-lives as short as several tens of microseconds. Newly developed magnetic rigidity tagging increases the resolving power of IMS to about 500000. IMS can be used to measure masses of nuclei with rates even lower than one ion per day, a property also needed for the purpose of the ILIMA project at the future facility FAIR. © 2007 American Institute of Physics.

GA Jones, Z Podolyak, N Schunck, PM Walker, G De Angelis, YH Zhang, M Axiotis, D Bazzacco, PG Bizzeti, F Brandolini, R Broda, D Bucurescu, E Farnea, W Gelletly, A Gadea, M Ionescu-Bujor, A Iordachescu, T Kroll, SD Langdown, S Lunardi, N Marginean, T Martinez, NH Medina, B Quintana, PH Regan, B Rubio, CA Ur, JJ Valiente-Dobon, SJ Williams (2005)Oblate collectivity in the yrast structure of Pt-194, In: ACTA PHYSICA POLONICA B36(4)pp. 1323-1327
FR Xu, HL Liu, HL Wang, JC Pei, Y Shi, PM Walker, S Frauendorf (2013)New studies on the aspects of nuclear shapes, In: Acta Physica Polonica B44(3)pp. 271-282

Using the pairing-deformation-frequency self-consistent total-Routhiansurface and configuration-constrained potential-energy-surface calculations, we have studied nuclear deformation and its effect on the structure of nuclei. It was found that the high-order multipolarity-six (β6) deformation plays a significant role in superheavy nuclei. Possible non-collective highspin isomeric states which locate in the second well of actinide nuclei have been investigated with the predictions of excitation energies and configurations. High-spin isomers can extend shape coexistence in A ∼ 190 neutrondeficient nuclei. Triaxiality with γ 30 is found in the ground and excited rotational states of the A ∼ 70 germanium isotopes. Octupole correlations have also been discussed in different mass regions. In recent experiments, the textbook nucleus 158Er has been reached at ultrahigh spins around 65∼. We have studied 158Er ultrahigh-spin states by means of the self-consistent tilted-axis-cranking method based on the Nilsson shell correction and the Skyrme-Hartree-Fock model. The calculation with a ≈ 12 ° triaxialstrongly-deformed (TSD) excited configuration can well reproduce the observed large transitional quadrupole moment. It is demonstrated that the TSD minimum at negative γdeformation which appears in the principalaxis-cranking approach is a saddle point if allowing the rotational axis to change direction.

PH Regan, N Alkhomashi, N Al-Dahan, Z Podolyak, EB Suckling, PD Stevenson, SB Pietri, SJ Steer, AB Garnsworthy, W Gelletly, J Benlliure, AI Morales, J Gerl, M Gorska, HJ Wollersheim, R Kumar, J Grebosz, A Algora, G Benzoni, P Boutachkov, AM Bruce, E Casarejos, IJ Cullen, AMD Bacelar, A Blazhev, ME Estevez, G Farrelly, Y Fujita, R Hoischen, S Lalkovski, Z Liu, I Kojouharov, N Kurz, C Mihai, F Molina, D Muecher, B Rubio, H Schaffner, S Tashenov, A Tamii, JJV Dobon, PM Walker, PJ Woods, A Blazhev, J Jolie, N Warr, A Zilges (2009)New Insights into the Structure of Exotic Nuclei Using the RISING Active Stopper, In: CAPTURE GAMMA-RAY SPECTROSCOPY AND RELATED TOPICS1090pp. 122-129
Philip M. Walker, Zsolt Podolyak (2020)100 years of nuclear isomers - then and now., In: Physica Scripta95(4) IOP Publishing

The suggestion that some atomic nuclei would be able to exist in more than one stable or metastable configuration was proposed by Soddy in 1917. Subsequently, the first experimental example of such an isomeric pair was reported by Hahn in 1921, in the form of two metastable states of 234Pa, then known as UZ and UX2. Nowadays, of the 3437 nuclides listed in the most recent NUBASE evaluation, 1318 have at least one metastable excited state with a half-life of 100 ns or longer. The present work reviews historical aspects of nuclear isomers, and the dfferent physical mechanisms that lead to their formation. Selected frontiers of contemporary isomer research are discussed, with an emphasis on remote regions of the nuclear landscape. Some possibilities for the electromagnetic manipulation of isomers are included.

N Minkov, PM Walker (2016)Octupole deformations in high-K isomeric states of heavy and superheavy nuclei, In: INTERNATIONAL CONFERENCE ON NUCLEAR STRUCTURE AND RELATED TOPICS (NSRT15)107
T.A. Berry, Zs. Podolyak, R.J. Carroll, R. Lică, H. Grawe, N.K. Timofeyuk, T. Alexander, A.N. Andreyev, S. Ansari, M.J.G. Borge, J. Creswell, C. Fahlander, L.M. Fraile, H.O.U. Fynbo, W. Gelletly, R.-B. Gerst, M. Górska, A. Gredley, P. Greenlees, L.J. Harkness-Brennan, M. Huyse, S.M. Judge, D.S. Judson, J. Konki, J. Kurcewicz, I. Kuti, S. Lalkovski, I. Lazarus, M. Lund, M. Madurga, N. Mărginean, R. Mărginean, I. Marroquin, C. Mihai, R.E. Mihai, E. Nácher, S. Nae, A. Negret, C. Niţă, R.D. Page, S. Pascu, Z. Patel, A. Perea, V. Pucknell, P. Rahkila, E. Rapisarda, P.H. Regan, F. Rotaru, C.M. Shand, E.C. Simpson, Ch. Sotty, S. Stegemann, T. Stora, O. Tengblad, A. Turturica, P. Van Duppen, V. Vedia, R. Wadsworth, P.M. Walker, N. Warr, F. Wearing, H. De Witte (2019)Investigation of the Δn = 0 selection rule in Gamow-Teller transitions: The β-decay of 207Hg, In: Physics Letters B793pp. 271-275 Elsevier

Gamow-Teller β decay is forbidden if the number of nodes in the radial wave functions of the initial and final states is different. This Δn=0 requirement plays a major role in the β decay of heavy neutron-rich nuclei, affecting the nucleosynthesis through the increased half-lives of nuclei on the astrophysical r-process pathway below both Z=50 (for N ˃ 82) and Z = 82 (for N ˃ 126). The level of forbiddenness of the Δn=1v1g9/2 → π0g7/2 transition has been investigated from the β decay of the ground state of 207Hg into the single-proton-hole nucleus 207Tl in an experiment at the ISOLDE Decay Station. From statistical observational limits on possible γ-ray transitions depopulating the π0g-17/2 state in 207Tl, an upper limit of 3.9 x 10-3% was obtained for the probability of this decay, corresponding to log ft ˃ 8.8 within a 95% confidence limit. This is the most stringent test of the Δn=0 selection rule to date.

PM Walker (2007)Rare modes of decay from high-spin isomers, In: PROTON EMITTING NUCLEI AND RELATED TOPICS961pp. 273-277
Z Podolyak, SJ Steer, S Pietri, E Werner-Malento, PH Regan, D Rudolph, AB Garnsworthy, R Hoischen, M Gorska, J Gerl, HJ Wollersheim, T Kurtukian-Nieto, G Benzoni, F Becker, P Bednarczyk, L Caceres, P Doornenbal, H Geissel, J Grebosz, A Kelic, I Kojouharov, N Kurz, F Montes, W Prokopowicz, T Saito, H Schaffner, S Tashenov, A Heinz, M Pfutzner, M Hellstrom, A Jungclaus, LL Andersson, L Atanasova, DL Balabanski, A Bentley, B Blank, A Blazhev, C Brandau, J Brown, AM Bruce, F Camera, WN Catford, IJ Cullen, Z Dombradi, E Estevez, C Fahlander, W Gelletly, G Ilie, EK Johansson, J Jolie, GA Jones, M Kmiecik, FG Kondev, S Lalkovski, Z Liu, A Maj, S Myalski, T Shizuma, AJ Simons, S Schwertel, PM Walker, O Wieland, BA Brown (2007)Isomeric decay studies around Pt-204 and Tb-148, In: EUROPEAN PHYSICAL JOURNAL-SPECIAL TOPICS150pp. 165-168 EDP SCIENCES S A

Relativistic energy projectile fragmentation of Pb-208 has been used to produce a range of exotic nuclei. The nuclei of interest were studied by detecting delayed gamma rays following the decay of isomeric states. Experimental information on the excited states of the neutron-rich N = 126 nucleus, Pt-204, following internal decay of two isomeric states, was obtained for the first time. In addition, decays from the previously reported isomeric I=27h and I=(49/2)h states in Tb-148 and Gd-147, respectively, have been observed. These isomeric decays represent the highest spin discrete states observed to date following a projectile fragmentation reaction, and opens further the possibility of doing 'high-spin physics' using this technique.

PM Walker (2008)Nuclear physics - A neutrino's wobble?, In: NATURE453(7197)pp. 864-865 NATURE PUBLISHING GROUP
GC Ball, C Andreoiu, RAE Austin, D Bandyopadhyay, JA Becker, P Bricault, N Brown, S Chan, R Churchman, S Colosimo, H Coombes, D Cross, G Demand, TE Drake, M Dombsky, S Ettenauer, P Finlay, D Furse, A Garnsworthy, PE Garrett, KL Green, GF Grinyer, B Hyland, G Hackman, R Kanungo, WD Kulp, J Lassen, KG Leach, JR Leslie, C Mattoon, D Melconian, AC Morton, CJ Pearson, AA Phillips, E Rand, F Sarazin, CE Svensson, S Sumithrarachchi, MA Schumaker, S Triambak, JC Waddington, PM Walker, SJ Wilhams, JL Wood, J Wong, EF Zganjar, TIGRESS Collaboration (2009)Gamma-ray spectroscopy at TRIUMF-ISAC: The new frontier of radioactive ion beam research, In: AIP Conference Proceedings: First Ulaanbaatar Conference on Nuclear Physics and Applications1109pp. 19-26

High‐resolution gamma‐ray spectroscopy is essential to fully exploit the unique scientific opportunities at the next generation radioactive ion beam facilities such as the TRIUMF Isotope Separator and Accelerator (ISAC). At ISAC the 8π spectrometer and its associated auxiliary detectors is optimize for β‐decay studies while TIGRESS an array of segmented clover HPGe detectors has been designed for studies with accelerated beams. This paper gives a brief overview of these facilities and also presents recent examples of the diverse experimental program carried out at the 8π spectrometer.

TPD Swan, PM Walker, Z Podolyak, MW Reed, GD Dracoulis, GJ Lane, T Kibedi, ML Smith (2011)Discovery of a nonyrast K-pi=8(+) isomer in Dy-162, and the influence of competing K-mixing mechanisms on its highly forbidden decay, In: PHYSICAL REVIEW C83(3)ARTN 0pp. ?-? AMER PHYSICAL SOC
AM Denis Bacelar, AM Bruce, S Lalkovski, Z Podolyák, N Al-Dahan, N Alkhomashi, IJ Cullen, AY Deo, GF Farrelly, W Gelletly, PH Regan, SJ Steer, TPD Swan, PM Walker, M Górska, S Pietri, MV Ricciardi, P Boutachkov, C Domingo-Pardo, F Farinon, H Geissel, J Gerl, N Goel, J Grȩbosz, R Hoischen, I Kojouharov, N Kurz, C Nociforo, A Prochazka, W Prokopowicz, K-H Schmidt, H Schaffner, H Weick, HJ Wollersheim, P Detistov, A Algora, F Molina, B Rubio, Z Dombradi, J Benlliure, AI Morales, S Verma, A Bracco, S Leoni, D Montanari, R Nicolini, E Calore, DR Napoli, JJ Valiente-Dobón, E Casarejos, M Doncel, D Rudolph, A Musumarra, K Steiger, P Strmen, I Szarka (2013)The population of metastable states as a probe of relativistic-energy fragmentation reactions, In: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics723(4-5)pp. 302-306 Elsevier

Isomeric ratios have been measured for high-spin states in Po84198,200,206,208, At85208,209,210,211, Rn86210,211,212,213,214, Fr87208,211,212,213,214, Ra88210,211,212,214,215, and Ac89215 following the projectile fragmentation of a 1 AGeV U beam by a Be target at GSI Helmholtzzentrum für Schwerionenforschung. The fragments were separated in the fragment separator (FRS) and identified by means of energy loss and time-of-flight techniques. They were brought to rest at the centre of the RISING gamma-ray detector array and intensities of gamma rays emitted in the decay of isomeric states with half-lives between 100 ns and 40 μs and spin values up to 55/2ℏ were used to obtain the corresponding isomeric ratios. The data are compared to theoretical isomeric ratios calculated in the framework of the abrasion-ablation model. Large experimental enhancements are obtained for high-spin isomers in comparison to expected values. © 2013 Elsevier B.V.

S Myalski, M Kmiecik, A Maj, PH Regan, AB Garnsworthy, S Pietri, D Rudolph, Z Podolyak, SJ Steer, F Becker, P Bednarczyk, J Gerl, M Gorska, H Grawe, I Kojouharov, H Schaffner, HJ Wollersheim, W Prokopowicz, J Grebosz, G Benzoni, B Blank, C Brandau, AM Bruce, L Caceres, F Camera, WN Catford, IJ Cullen, Z Dombradi, P Doornenbal, E Estevez, H Geissel, W Gelletly, A Heinz, R Hoischen, G Ilie, GA Jones, A Jungclaus, A Kelic, FG Kondev, T Kurtukian-Nieto, N Kurz, S Lalkovski, Z Liu, F Montes, M Pfutzner, T Saito, T Shizuma, AJ Simons, S Schwertel, S Tachenov, PM Walker, E Werner-Malento, O Wieland (2007)Isomeric ratio for the I-pi=8(+) yrast state in Pd-96 produced in the relativistic fragmentation of Ag-107, In: ACTA PHYSICA POLONICA B38(4)pp. 1277-1282 ACTA PHYSICA POLONICA B, JAGELLONIAN UNIV, INST PHYSICS

We report on the preliminary results from a study of the decay of the I-pi = 8(+) T-1/2 = 2 mu s isomer in Pd-96 performed as part of the Stopped-Beam RISING campaign within the Rare Isotope Investigation at GSI (RISING). The Pd-96 ions were produced following the projectile fragmentation of a 750 MeV per nucleon Ag-107 primary beam. The reaction products were separated and identified by the in-flight method using the GSI Fragment Separator. The residues of interest were stopped in a perspex stopper surrounded by an array of 15, seven-element germanium Cluster detectors. One of the goals of the current work is to investigate the population of high-spin states produced projectile fragmentation reactions using isomeric ratio measurements to infer information on the angular momentum population distribution. In this short contribution the method and results of determining the isomeric ratio for the I-pi = 8(+) microsecond isomer in Pd-96 nucleus are presented.

HL Liu, FR Xu, PM Walker, CA Bertulani (2011)Deformation and its influence on K isomerism in neutron-rich Hf nuclei, In: PHYSICAL REVIEW C83(6)ARTN 0pp. ?-? AMER PHYSICAL SOC
TE Cocolios, J Billowes, KT Flanagan, KM Lynch, TJ Procter, AJ Smith, I Strashnov, HH Al Suradi, I Budinčević, RP De Groote, S De Schepper, RF Garcia Ruiz, H Heylen, G Neyens, J Papuga, MM Rajabali, VN Fedosseev, BA Marsh, RE Rossel, S Rothe, S Franchoo, F Le Blanc, D Verney, PJR Mason, PM Walker, RT Wood, KDA Wendt, GS Simpson, HH Stroke (2013)The Collinear Resonance Ionization Spectroscopy (CRIS) experimental setup at CERN-ISOLDE, In: Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms317(PART B)pp. 565-569

The CRIS setup at CERN-ISOLDE is a laser spectroscopy experiment dedicated to the high-resolution study of the spin, hyperfine structure and isotope shift of radioactive nuclei with low production rates (a few per second). It combines the Doppler-free resolution of the in-flight collinear geometry with the high detection efficiency of resonant ionisation. A recent commissioning campaign has demonstrated a 1% experimental efficiency, and as low as a 0.001% non-resonant ionisation. The current status of the experiment and its recent achievements with beams of francium isotopes are reported. The first identified systematic effects are discussed.© 2013 The Authors. Published by Elsevier B.V. All rights reserved.

MA Schumaker, AM Hurst, CE Svensson, CY Wu, JA Becker, D Cline, G Hackman, CJ Pearson, MA Stoyer, A Andreyev, RAE Austin, GC Ball, D Bandyopadhyay, CJ Barton, AJ Boston, HC Boston, L Buchmann, R Churchman, F Cifarelli, SJ Colosimo, RJ Cooper, DS Cross, D Dashdorj, GA Demand, MR Dimmock, M Djongolov, TE Drake, P Finlay, AT Gallant, PE Garrett, C Gray-Jones, KL Green, AN Grint, GF Grinyer, LJ Harkness, AB Hayes, R Kanungo, KG Leach, WD Kulp, AF Lisetskiy, G Lee, S Lloyd, R Maharaj, J-P Martin, BA Millar, F Moisan, AC Morton, S Mythili, L Nelson, O Newman, PJ Nolan, JN Orce, DC Oxley, E Padilla-Rodal, AA Phillips, M Porter-Peden, JJ Ressler, SV Rigby, R Roy, C Ruiz, F Sarazin, DP Scraggs, CS Sumithrarachchi, S Triambak, JC Waddington, PM Walker, J Wan, A Whitbeck, SJ Williams, J Wong, JL Wood (2009)First results with TIGRESS and accelerated radioactive ion beams from ISAC: Coulomb excitation of20,21,29Na, In: AIP Conference Proceedings: 20th International Conference on Application of Accelerators in Research and Industry1099pp. 754-759

The TRIUMF‐ISAC Gamma‐Ray Escape Suppressed Spectrometer (TIGRESS) is a state‐of‐the‐art γ‐ray spectrometer being constructed at the ISAC‐II radioactive ion beam facility at TRIUMF. TIGRESS will be comprised of twelve 32‐fold segmented high‐purity germanium (HPGe) clover‐type γ‐ray detectors, with BGO∕CsI(Tl) Compton‐suppression shields, and is currently operational at ISAC‐II in an early‐implementation configuration of six detectors. Results have been obtained for the first experiments performed using TIGRESS, which examined the A  =  20, 21, and 29 isotopes of Na by Coulomb excitation.

YA Litvinov, F Bosch, I Dillmann, P Egelhof, H Geissel, RE Grisenti, S Hagmann, M Heil, R Knöbel, C Kozhuharov, M Lestinsky, F Nolden, MS Sanjari, H Simon, M Steck, T Stöhlker, XL Tu, H Weick, N Winckler, S Bishop, K Blaum, C Brandau, LX Chen, R Reifarth, A Heinz, T Nilsson, N Kalantar-Nayestanaki, XW Ma, HS Xu, YH Zhang, A Ozawa, R Raabe, MW Reed, D Schneider, BH Sun, T Uesaka, M Wakasugi, Y Yamaguchi, PM Walker, PJ Woods, T Yamaguchi (2013)Nuclear physics experiments with ion storage rings, In: Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms317(PART B)pp. 603-616 Elsevier

In the last two decades a number of nuclear structure and astrophysics experiments were performed at heavy-ion storage rings employing unique experimental conditions offered by such machines. Furthermore, building on the experience gained at the two facilities presently in operation, several new storage ring projects were launched worldwide. This contribution is intended to provide a brief review of the fast growing field of nuclear structure and astrophysics research at storage rings. © 2013 Elsevier B.V. All rights reserved.

R Knoebel, M Diwisch, F Bosch, D Boutin, L Chen, C Dimopoulou, A Dolinskii, B Franczak, B Franzke, H Geissel, M Hausmann, C Kozhuharov, J Kurcewicz, SA Litvinov, G Martinez-Pinedo, M Matos, M Mazzocco, G Muenzenberg, S Nakajima, C Nociforo, F Nolden, T Ohtsubo, A Ozawa, Z Patyk, WR Plass, C Scheidenberger, J Stadlmann, M Steck, B Sun, T Suzuki, PM Walker, H Weick, M-R Wu, M Winkler, T Yamaguchi (2016)First direct mass measurements of stored neutron-rich Cd-129,Cd-130,Cd-131 isotopes with FRS-ESR, In: PHYSICS LETTERS B754pp. 288-293 ELSEVIER SCIENCE BV
N Minkov, P Walker (2014)Influence of the octupole mode on nuclear high-K isomeric properties, In: Physica Scripta89(5)

The influence of quadrupole-octupole deformations on the energy and magnetic properties of high-K isomeric states in even-even actinide (U, Pu, Cm, Fm, No), rare-earth (Nd, Sm and Gd), and superheavy ( nuclei is examined within a deformed shell model with pairing interaction. The neutron two-quasiparticle (2qp) isomeric energies and magnetic dipole moments are calculated over a wide range in the plane of quadrupole and octupole deformations. In most cases the magnetic moments exhibit a pronounced sensitivity to the octupole deformation. At the same time, the calculations outline three different groups of nuclei: with pronounced, shallow, and missing minima in the 2qp energy surfaces with respect to the octupole deformation. The result indicates regions of nuclei with octupole softness as well as with possible octupole deformation in the high-K isomeric states. These findings show the need for further theoretical analysis as well as of detailed experimental measurements of magnetic moments in heavy deformed nuclei. © 2014 The Royal Swedish Academy of Sciences.

EF Zganjar, T Achtzehn, D Albers, C Andreoiu, AN Andreyev, RAE Austin, GC Ball, JA Behr, GC Biosvert, P Bricault, S Bishop, RS Chakrawarthy, R Churchman, D Cross, E Cunningham, JM D'Auria, M Dombsky, P Finlay, PE Garrett, GF Grinyer, G Hackman, V Hanemaayer, JC Hardy, DF Hodgson, B Hyland, V Iacob, P Klages, KA Koopmans, WD Kulp, J Lassen, JP Lavoie, JR Leslie, T Linder, JA Macdonald, H-B Mak, D Melconian, AC Morton, WE Ormand, CJ Osborne, CJ Pearson, MR Pearson, AA Phillips, A Piechaczek, J Ressler, F Sarazin, G Savard, MA Schumaker, HC Scraggs, CE Svensson, JJ Valiente-Dobon, IS Towner, JC Waddington, PM Walker, K Wendt, JL Wood (2007)Superallowed beta decay studies at TRIUMF - Nuclear structure and fundamental symmetries, In: ACTA PHYSICA POLONICA B38(4)pp. 1179-1194
M. Rudigier, R.L. Canavan, P.H. Regan, P.-A. Söderström, M. Lebois, J.N. Wilson, N. Jovancevic, S. Bottoni, M. Brunet, N. Cieplicka-Orynczak, S. Courtin, D.T. Doherty, K. Hadynska-Klek, M. Heine, W. Iskra, V. Karayonchev, A. Kennington, P. Koseoglou, G. Lotay, G. Lorusso, M. Nakhostin, C.R. Nita, S. S. Oberstedt, Zs. Podolyak, L. Qi, J.-M. Régis, R. Shearman, P.M. Walker, W. Witt (2019)Isomer spectroscopy and sub-nanosecond half-live determination in 178w using the NuBall array, In: Acta Physica Polonica B50(3)pp. 661-667 Jagiellonian University

The reaction of a pulsed 18O beam on a 164Dy target was studied in the first experiment with the NuBall array at the IPN Orsay, France. Excited state half-lives were measured using the fast timing method with 20 LaBr3(Ce) detectors. The timing characteristics of the fully digital acquisition system is briefly discussed. A value for the previously unknown half-life of the first excited 4+ state in 178W is presented.

GF Farrelly, Z Podolyak, SJ Steer, S Pietri, FR Xu, E Werner-Malento, T Shizuma, PH Regan, D Rudolph, AB Garnsworthy, R Hoischen, M Gorska, J Gerl, HJ Wollersheim, T Kurtukian-Nieto, G Benzoni, F Becker, P Bednarczyk, L Caceres, P Doornenbal, H Geisserl, J Grebosz, A Kelic, I Kojouharov, N Kurz, F Montes, W Prokopowicz, T Saito, H Schaffner, S Tashenov, A Heinz, M Pfuezner, A Jungclaus, DL Balabanski, C Brandau, AM Bruce, WN Catford, IJ Cullen, Z Dombradi, E Estevez, W Gelletly, G Ilie, J Jolie, GA Jones, M Kmiecik, FG Kondev, R Kruecken, S Lalkovski, HL Liu, Z Liu, A Maj, S Myalski, S Schwerrel, PM Walker, O Wieland (2009)REVISION OF THE K-ISOMER IN W-190(116), In: ACTA PHYSICA POLONICA B40(3)pp. 885-888
I Shestakova, G Mukherjee, P Chowdhury, R D'Alarcao, CJ Pearson, Z Podolyak, PM Walker, C Wheldon, DM Cullen, I Ahmad, MP Carpenter, RVF Janssens, TL Khoo, FG Kondev, CJ Lister, D Seweryniak, I Wiedenhoever (2001)Yrast three-quasiparticle K isomers in neutron-rich Hf-181, In: PHYSICAL REVIEW C64(5)ARTN 05430 AMERICAN PHYSICAL SOC
S Muto, NJ Stone, CR Bingham, JR Stone, PM Walker, Z Podolyak, G Audi, C Gaulard, L Risegari, U Köster, J Nikolov, M Veskovic, K Nishimura, T Ohtsubo, GS Simpson, WB Walters (2014)Magnetic properties of Hf 177 and Hf 180 in the strong-coupling deformed model, In: Physical Review C - Nuclear Physics89(4)

This paper reports NMR measurements of the magnetic dipole moments of two high-K isomers, the 37/2-, 51.4 m, 2740 keV state in Hf177 and the 8-, 5.5 h, 1142 keV state in Hf180 by the method of on-line nuclear orientation. Also included are results on the angular distributions of γ transitions in the decay of the Hf177 isotope. These yield high precision E2/M1 multipole mixing ratios for transitions in bands built on the 23/2+, 1.1 s, isomer at 1315 keV and on the 9/2+, 0.663 ns, isomer at 321 keV. The new results are discussed in the light of the recently reported finding of systematic dependence of the behavior of the gR parameter upon the quasiproton and quasineutron make up of high-K isomeric states in this region. © 2014 American Physical Society.

C. M. Mattoon, F. Sarazin, G. Hackman, E. S. Cunningham, R. A. E. Austin, G. C. Ball, R. S. Chakrawarthy, P. Finlay, P. E. Garrett, G. F. Grinyer, B. Hyland, K. A. Koopmans, J. R. Leslie, A. A. Phillips, M. A. Schumaker, H. C. Scraggs, J. Schwarzenberg, M. B. Smith, C. E. Svensson, J. C. Waddington, P. M. Walker, B. Washbrook, E. Zganjar (2007)Beta decay of 32Na, In: Physical Review C75(017302)
MW Reed, IJ Cullen, PM Walker, YA Litvinov, K Blaum, F Bosch, C Brandau, JJ Carroll, DM Cullen, AY Deo, B Detwiller, C Dimopoulou, GD Dracoulis, F Farinon, H Geissel, E Haettner, M Heil, RS Kempley, R Knoebel, C Kozhuharov, J Kurcewicz, N Kuzminchuk, S Litvinov, Z Liu, R Mao, C Nociforo, F Nolden, WR Plass, A Prochazka, C Scheidenberger, M Steck, T Stoehlker, B Sun, TPD Swan, G Trees, H Weick, N Winckler, M Winkler, PJ Woods, T Yamaguchi (2010)Discovery of Highly Excited Long-Lived Isomers in Neutron-Rich Hafnium and Tantalum Isotopes through Direct Mass Measurements, In: PHYSICAL REVIEW LETTERS105(17)ARTN 1pp. ?-? AMER PHYSICAL SOC
AB Garnsworthy, PH Regan, S Pietri, Y Sun, FR Xu, D Rudolph, M Gorska, L Caceres, Z Podolyak, SJ Steer, R Hoischen, A Heinz, F Becker, P Bednarczyk, P Doornenbal, H Geissel, J Gerl, H Grawe, J Grebosz, A Kelic, I Kojouharov, N Kurz, F Montes, W Prokopwicz, T Saito, H Schaffner, S Tachenov, E Werner-Malento, HJ Wollersheim, G Benzoni, B Blank, C Brandau, AM Bruce, F Camera, WN Catford, IJ Cullen, Z Dombradi, E Estevez, W Gelletly, G Ilie, J Jolie, GA Jones, A Jungclaus, M Kmiecik, FG Kondev, T Kurtukian-Nieto, S Lalkovski, Z Liu, A Maj, S Myalski, M Pfuetzner, S Schwertel, T Shizuma, AJ Simons, PM Walker, O Wieland (2009)Isomeric states in neutron-deficient A similar to 80-90 nuclei populated in the fragmentation of Ag-107, In: PHYSICAL REVIEW C80(6)ARTN 0pp. ?-? AMER PHYSICAL SOC
AM Hurst, CY Wu, JA Becker, MA Stoyer, CJ Pearson, G Hackman, MA Schumaker, CE Svensson, RAE Austin, GC Ball, D Bandyopadhyay, CJ Barton, AJ Boston, HC Boston, R Churchman, D Cline, SJ Colosimo, DS Cross, G Demand, M Djongolov, TE Drake, PE Garrett, C Gray-Jones, KL Green, AN Grint, AB Hayes, KG Leach, WD Kulp, G Lee, S Lloyd, R Maharaj, JP Martin, BA Millar, S Mythili, L Nelson, PJ Nolan, DC Oxley, E Padilla-Rodal, AA Phillips, M Porter-Peden, SV Rigby, F Sarazin, CS Sumithrarachchi, S Triambak, PM Walker, SJ Williams, J Wong, JL Wood (2009)Narrowing of the neutron sd-pf shell gap in Na-29, In: PHYS LETT B674(3)pp. 168-171 ELSEVIER SCIENCE BV

The wave-function composition for the low-lying states in Na-29 was explored by measuring their electromagnetic properties using the Coulomb-excitation technique. A beam of Na-29 ions, postaccelerated to 70 MeV, bombarded a Pd-110 target with a rate of up to 600 particles per second at the recently commissioned ISAC-II facility at TRIUMF. Six segmented HPGe clover detectors of the TIGRESS gamma-ray spectrometer were used to detect deexcitation gamma rays in coincidence with scattered or recoiling charged particles in the segmented silicon detector, BAMBINO. The reduced transition matrix element vertical bar < 5/2(1)(+)vertical bar vertical bar E2 vertical bar vertical bar 3/2(gs)(+)>vertical bar in Na-29 was derived to be 0.237(21) e b from the measured gamma-ray yields for both projectile and target. This first-time measured value is consistent with the most recent Monte Carlo shell-model calculation, indicating a significant admixture of both sd and pf components in the wave function, and also providing evidence for the narrowing of the neutron sd-pf shell gap from similar to 6 MeV for stable nuclei to similar to 3 MeV for Na-29. (C) 2009 Elsevier B.V. All rights reserved.

Y Shi, FR Xu, PM Walker, GD Dracoulis (2012)Superdeformed multi-quasiparticle high-K states and possible isomers in Pb and Po isotopes, In: PHYSICAL REVIEW C85(6)ARTN 0pp. ?-? AMER PHYSICAL SOC
Zs. Podolyák, P. M. Walker, D. M. Cullen, G. D. Dracoulis, P. Fallon, B. Fairchild, K. Hauschild, A. O. Macchiavelli, D. P. McNabb, A. Savelius, D. Ward, C. Wheldon (2000)Search for very long-lived isomers in the hafnium-tungsten region, In: Physical Review C62(034303)
KM Lynch, J Billowes, TE Cocolios, KT Flanagan, TJ Procter, AJ Smith, I Strashnov, ML Bissell, I Budincevic, RP De Groote, S De Schepper, RF Garcia Ruiz, H Heylen, G Neyens, VN Fedosseev, BA Marsh, RE Rossel, S Rothe, S Franchoo, PJR Mason, PM Walker, RT Wood, KDA Wendt, GS Simpson, HH Stroke (2013)CRIS: A new method in isomeric beam production, In: EPJ Web of Conferences63

The Collinear Resonance Ionization Spectroscopy (CRIS) experiment at ISOLDE, CERN, uses laser radiation to stepwise excite and ionize an atomic beam for the purpose of ultra-sensitive detection of rare isotopes, and hyperfine-structure measurements. The technique also offers the ability to purify an ion beam that is heavily contaminated with radioactive isobars, including the ground state of an isotope from its isomer, allowing decay spectroscopy on nuclear isomeric states to be performed. The isomeric ion beam is selected by resonantly exciting one of its hyperfine structure levels, and subsequently ionizing it. This selectively ionized beam is deflected to a decay spectroscopy station (DSS). This consists of a rotating wheel implantation system for alpha- and beta-decay spectroscopy, and up to three germanium detectors around the implantation site for gamma-ray detection. Resonance ionization spectroscopy and the new technique of laser assisted nuclear decay spectroscopy have recently been performed at the CRIS beam line on the neutron-deficient francium isotopes. Here an overview of the two techniques will be presented, alongside a description of the CRIS beam line and DSS. © Owned by the authors, published by EDP Sciences, 2013.

C. Scholey, D. M. Cullen, E. S. Paul, A. J. Boston, P. A. Butler, T. Enqvist, C. Fox, H. C. Scraggs, S. L. Shepherd, O. Stezowsk, A. M. Bruce, P. M. Walker, m. Caamano, J. Garcés Narro, M. A. Bentley, D. T. Joss, O. Dorvaux, P. T. Greenlees, K. Helariutta, P. M. Jones, R. Julin, S. Juutinen, H. Kankaanpää, H. Kettunen, P. Kuusiniemi, M. Leino, M. Muikku, P. Nieminen, P. Rahkila, J. Uusitalo (2001)Recoil isomer tagging in the proton-rich odd-odd N=77 isotones,  65142Tb and  67144Ho, In: Physical Review C63(034321)

S Lalkovski, S Kisyov, M Zhekova, AM Bruce, AMD Bacelar, M Górska, S Pietri, P Bednarczyk, L Caceres, P Doornenbal, H Geissel, J Gerl, J Grȩbosz, I Kojouharov, N Kurz, W Prokopowicz, H Schaffner, S Tashenov, HJ Wollersheim, Z Podolyák, IJ Cullen, GF Farrelly, AB Garnsworthy, W Gelletly, PH Regan, S Steer, PM Walker, E Casarejos, S Myalski, C Hinke, G Ilie, G Jaworski, M Palacz (2012)Single-particle isomeric states in Pd and Ru, In: Journal of Physics: Conference Series366(1)

Neutron-rich nuclei were populated in a relativistic fission of U. Gamma-rays with energies of 135 keV and 184 keV were associated with two isomeric states in Pd and Ru. Half-lives of 0.63(5) μs and 2.0(3) μs were deduced and the isomeric states were interpreted in terms of prolate deformed single-particle states.

P Chowdhury, I Shestakova, R D'Alarcao, CJ Pearson, Z Podolyak, PM Walker, C Wheldon, DM Cullen, I Ahmad, MP Carpenter, RVF Janssens, TL Khoo, FG Kondev, CJ Lister, D Seweryniak, I Wiedenhoever (2001)Harvesting new isomers in neutron-rich hafnium nuclei, In: NUCLEAR PHYSICS A682pp. 65C-70C
L Chen, YA Litvinov, WR Plass, K Beckert, P Beller, F Bosch, D Boutin, L Caceres, RB Cakirli, JJ Carroll, RF Casten, RS Chakrawarthy, DM Cullen, IJ Cullen, B Franzke, H Geissel, J Gerl, M Gorska, GA Jones, A Kishada, R Knoebel, C Kozhuharov, SA Litvinov, Z Liu, S Mandal, F Montes, G Muenzenberg, F Nolden, T Ohtsubo, Z Patyk, Z Podolyak, R Propri, S Rigby, N Saito, T Saito, C Scheidenberger, M Shindo, M Steck, P Ugorowski, PM Walker, S Williams, H Weick, M Winkler, H-J Wollersheim, T Yamaguchi (2009)Schottky Mass Measurement of the Hg-208 Isotope: Implication for the Proton-Neutron Interaction Strength around Doubly Magic Pb-208, In: PHYSICAL REVIEW LETTERS102(12)ARTN 1pp. ?-? AMER PHYSICAL SOC
Z Patel, P-A Soederstroem, Z Podolyak, PH Regan, PM Walker, H Watanabe, E Ideguchi, GS Simpson, HL Liu, S Nishimura, Q Wu, FR Xu, F Browne, P Doornenbal, G Lorusso, S Rice, L Sinclair, T Sumikama, J Wu, ZY Xu, N Aoi, H Baba, FLB Garrote, G Benzoni, R Daido, Y Fang, N Fukuda, G Gey, S Go, A Gottardo, N Inabe, T Isobe, D Kameda, K Kobayashi, M Kobayashi, T Komatsubara, I Kojouharov, T Kubo, N Kurz, I Kuti, Z Li, M Matsushita, S Michimasa, C-B Moon, H Nishibata, I Nishizuka, A Odahara, E Sahin, H Sakurai, H Schaffner, H Suzuki, H Takeda, M Tanaka, J Taprogge, Z Vajta, A Yagi, R Yokoyama (2014)Isomer Decay Spectroscopy of Sm-164 and Gd-166: Midshell Collectivity Around N=100, In: PHYSICAL REVIEW LETTERS113(26)ARTN 2pp. ?-? AMER PHYSICAL SOC
PM Walker, RJ Wood, GD Dracoulis, T Kibedi, RA Bark, AM Bruce, AP Byrne, PM Davidson, HM El-Masri, GJ Lane, C Moon, JN Orce, FMP Estevez, C Wheldon, AN Wilson (2009)Fast decay of a three-quasiparticle isomer in Tm-171, In: PHYSICAL REVIEW C79(4)ARTN 0pp. ?-? AMER PHYSICAL SOC
G. D. Dracoulis, F. G. Kondev, A. P. Byrne, T. Kibédi, S. Bayer, P. M. Davidson, P. M. Walker, C. Purry, C. J. Pearson (1996)Structure and decay of a four-quasiparticle 15- isomer in 180Ta, In: Physical Review C53pp. 1205-1209
P Walker (2014)Nuclear physics: Track it to the limit, In: Nature Physics10(5)pp. 338-339
Z Podolyak, J Gerl, M Hellstrom, F Becker, KA Gladnishki, M Gorska, A Kelic, Y Kopatch, S Mandal, PH Regan, KH Schmidt, PM Walker, HJ Wollersheim, A Banu, G Benzoni, H Boardman, E Casarejos, J Ekman, H Geissel, H Grawe, D Hohn, I Kojouharov, J Leske, R Lozeva, MN Mineva, G Neyens, RD Page, CJ Pearson, M Portillo, D Rudolph, N Saito, H Schaffner, D Sohler, K Summerer, JJ Valiente-Dobon, C Wheldon, H Weick, M Winkler (2006)Neutron-deficient N approximate to 126 nuclei produced in U-238 fragmentation: Population of high-spin states, In: Frontiers in Nuclear Structure Astrophysics, and Reactions: FINUSTAR831pp. 114-118 AMER INST PHYSICS

The population of metastable states produced in relativistic-energy fragmentation of a U-238 beam has been measured. For states with high angular momentum, I=17h and I=21.5h, a higher population than expected has been observed, with the discrepancy increasing with angular momentum. By considering two sources for the angular momentum, related to single-particle and collective motions, a much improved description of the experimental results can be obtained. In addition, new results on the structure of Fr-208, Ra-211 and Ac-216 are reported.

Z Podolyak, SJ Steer, S Pietri, FR Xu, HL Liu, PH Regan, D Rudolph, AB Garnsworthy, R Hoischen, M Gorska, J Gerl, HJ Wollersheim, T Kurtukian-Nieto, G Benzoni, T Shizuma, F Becker, P Bednarczyk, L Caceres, P Doornenbal, H Geissel, J Grebosz, A Kelic, I Kojouharov, N Kurz, F Montes, W Prokopowicz, T Saito, H Schaffner, S Tashenov, A Heinz, M Pfutzner, A Jungclaus, DL Balabanski, C Brandau, AM Bruce, WN Catford, IJ Cullen, Z Dombradi, E Estevez, W Gelletly, G Ilie, J Jolie, GA Jones, M Kmiecik, FG Kondev, R Kruecken, S Lalkovski, Z Liu, A Maj, S Myalski, S Schwertel, PM Walker, E Werner-Malento, O Wieland (2009)Weakly deformed oblate structures in Os-198(76)122, In: PHYSICAL REVIEW C79(3)ARTN 0pp. ?-? AMER PHYSICAL SOC
AB Hayes, D Cline, CY Wu, AM Hurst, MP Carpenter, JP Greene, RVF Janssens, T Lauritsen, D Seweryniak, S Zhu, SA Karamian, PM Walker, TPD Swan, SV Rigby, DM Cullen, NM Lumley, P Mason, JJ Carroll, B Detwiler, T Harle, I Mills, G Trees (2011)NEW STRUCTURES IN (HF)-H-178 AND COULOMB EXCITATION OF ISOMERS, In: INTERNATIONAL JOURNAL OF MODERN PHYSICS E-NUCLEAR PHYSICS20(2)pp. 474-481 WORLD SCIENTIFIC PUBL CO PTE LTD
H Watanabe, K Yamaguchi, A Odahara, T Sumikama, S Nishimura, K Yoshinaga, Z Li, Y Miyashita, K Sato, L Prochniak, H Baba, JS Berryman, N Blasi, A Bracco, F Camera, J Chiba, P Doornenbal, S Go, T Hashimoto, S Hayakawa, C Hinke, N Hinohara, E Ideguchi, T Isobe, Y Ito, DG Jenkins, Y Kawada, N Kobayashi, Y Kondo, R Kruecken, S Kubono, G Lorusso, T Nakano, T Nakatsukasa, M Kurata-Nishimura, HJ Ong, S Ota, Z Podolyak, H Sakurai, H Scheit, K Steiger, D Steppenbeck, K Sugimoto, K Tajiri, S Takano, A Takashima, T Teranishi, Y Wakabayashi, PM Walker, O Wieland, H Yamaguchi (2011)Development of axial asymmetry in the neutron-rich nucleus Mo-110, In: PHYSICS LETTERS B704(4)pp. 270-275 ELSEVIER SCIENCE BV
M Pfutzner, PH Regan, PM Walker, Z Podolyak, M Caamano, J Gerl, M Hellstrom, P Mayet, MN Mineva (2001)Population of high spin states in relativistic fragmentation, In: ACTA PHYSICA POLONICA B32(9)pp. 2507-2518
AM Bruce, S Lalkovski, AMD Bacelar, M Gorska, S Pietri, Z Podolyak, Y Shi, PM Walker, FR Xu, P Bednarczyk, L Caceres, E Casarejos, IJ Cullen, P Doornenbal, GF Farrelly, AB Garnsworthy, H Geissel, W Gelletly, J Gerl, J Grebosz, C Hinke, G Ilie, G Jaworski, I Kojouharov, N Kurz, S Myalski, M Palacz, W Prokopowicz, PH Regan, H Schaffner, S Steer, S Tashenov, HJ Wollersheim (2010)Shape coexistence and isomeric states in neutron-rich Tc-112 and Tc-113, In: PHYSICAL REVIEW C82(4)ARTN 0pp. ?-? AMER PHYSICAL SOC
HL Liu, FR Xu, PM Walker (2012)Understanding the different rotational behaviors of No-252 and No-254, In: PHYSICAL REVIEW C86(1)ARTN 0pp. ?-? AMER PHYSICAL SOC
HL Liu, PM Walker, FR Xu (2014)Favored configurations for four-quasiparticle K isomerism in the heaviest nuclei, In: PHYSICAL REVIEW C89(4)ARTN 0pp. ?-? AMER PHYSICAL SOC
TPD Swan, PM Walker, Z Podolyak, MW Reed, GD Dracoulis, GJ Lane, T Kibedi, ML Smith (2012)Discovery of isomers in dysprosium, holmium, and erbium isotopes with N=94 to 97, In: PHYSICAL REVIEW C85024313 American Physical Society
LS Caceres, M Gorska, A Jungclaus, PH Regan, AB Garnsworthy, S Pietri, Z Podolyak, D Rudolph, SJ Steer, H Grawe, DL Balabanski, F Becker, P Bednarczyk, G Benzoni, B Blank, C Brandau, AM Bruce, F Camera, WN Catford, IJ Cullen, Z Dombradi, P Doornenbalal, E Estevez, H Geissel, W Gelletly, J Gerl, J Grebosz, A Heinz, R Hoischen, G Ilie, J Jolie, GA Jones, M Kmiecik, I Kojouharov, FG Kondev, T Kurtukian-Nieto, N Kurz, S Lalkowski, L Liu, A Maj, S Myalsk, F Montes, M Pfuetzner, W Prokopowicz, T Saito, H Schatfner, S Schwertel, T Shizuma, AJ Simons, S Tashenov, PM Walker, E Werner-Malento, O Wielandh, HJ Wollersheim (2007)Identification of excited states in the N = Z nucleus Nb-82, In: ACTA PHYSICA POLONICA B38(4)pp. 1271-1275
J Wu, S Nishimura, G Lorusso, P Moller, E Ideguchi, Patrick Regan, GS Simpson, P-A Soderstrom, Philip Walker, H Watanabe, ZY Xu, H Baba, F Browne, R Daido, P Doornenbal, YF Fang, G Gey, T Isobe, PS Lee, JJ Liu, Z Li, Z Korkulu, Z Patel, V Phong, S Rice, H Sakurai, L Sinclair, T Sumikama, M Tanaka, A Yagi, YL Ye, R Yokoyama, GX Zhang, T Alharbi, N Aoi, FL Bello Garrote, G Benzoni, AM Bruce, RJ Carroll, KY Chae, Z Dombradi, A Estrade, A Gottardo, CJ Griffin, H Kanaoka, I Kojouharov, FG Kondev, S Kubono, N Kurz, I Kuti, S Lalkovski, GJ Lane, EJ Lee, T Lokotko, Gavin Lotay, C-B Moon, H Nishibata, I Nishizuka, CR Nita, A Odahara, Zsolt Podolyak, OJ Roberts, H Schaffner, Callum Shand, J Taprogge, S Terashima, Z Vajta, S Yoshida (2017)94 -Decay Half-lives of Neutron-Rich 55Cs to 67Ho: Experimental Feedback and Evaluation of the r-Process Rare-Earth Peak Formation, In: Physical Review Letters118(7)072701 American Physical Society

The -decay half-lives of 94 neutron-rich nuclei 144−151Cs, 146−154Ba, 148−156La, 150−158Ce, 153−160Pr, 156−162Nd, 159−163Pm, 160−166Sm, 161−168Eu, 165−170Gd, 166−172Tb, 169−173Dy, 172−175Ho and two isomeric states 174mEr, 172mDy were measured at Radioactive Isotope Beam Factory (RIBF), providing a new experimental basis to test theoretical models. Striking, large drops of -decay half-lives are observed at neutron-number N = 97 for 58Ce, 59Pr, 60Nd, 62Sm, and N = 105 for 63Eu, 64Gd, 65Tb, 66Dy. Features in the data mirror the interplay between pairing effects and microscopic structure. r-Process network calculations performed for a range of mass models and astrophysical conditions show that the 57 half-lives measured for the first time play an important role in shaping the abundance pattern of rare-earth elements in the solar system.

M Pfutzner, PH Regan, PM Walker, M Caamano, J Gerl, M Hellstrom, P Mayet, KH Schmidt, Z Podolyak, MN Mineva, A Aprahamian, J Benlliure, AM Bruce, PA Butler, DC Gil, DM Cullen, J Doring, T Enquist, C Fox, J Garces Narro, H Geissel, W Gelletly, J Giovinazzo, M Gorska, H Grawe, R Grzywacz, A Kleinbohl, W Korten, M Lewitowicz, R Lucas, H Mach, CD O'Leary, F De Oliveira, CJ Pearson, F Rejmund, M Rejmund, M Sawicka, H Schaffner, C Schlegel, K Schmidt, C Theisen, F Vives, DD Warner, C Wheldon, HJ Wollersheim, S Wooding (2002)Angular momentum population in the fragmentation of Pb-208 at 1 GeV/nucleon, In: PHYSICAL REVIEW C65(6)ARTN 0pp. ?-? AMERICAN PHYSICAL SOC
K Andgren, Z Podolyak, A Dewald, F R Xu, A Algora, M Axiotis, D Bazzacco, P G Bizzeti, A M Bizzeti-Sona, B Cederwall, G de Angelis, E Farnea, A Fitzler, A Gadea, W Gelletly, S Lunardi, O Moller, N Marginean, T Martinez, T Pissulla, C Rusu, C A Ur, R Venturelli, P M Walker, C Wheldon (2005)Lifetime Measurements of Normal Deformed States in Lu-165(71), In: Physical Review C71(1)

Picosecond lifetimes of medium spin states in Lu-165 were measured for the first time. The reaction used to populate the nucleus of interest was La-139(Si-30,4n)Lu-165 at a beam energy of 135 MeV. The beam was provided by the XTU-tandem accelerator of Laboratori Nazionali di Legnaro, Italy. By using the differential decay curve method, lifetimes of 19 states in four different rotational bands were obtained. Therefrom the B(E2) values and the transitional quadrupole moments were deduced. The obtained Q(t) for the different bands are compared with total Routhian surface (TRS) calculations and particle-rotor-model calculations. The TRS calculations predict different axial symmetric shapes for the bands built on the 9/2(-)[514], 9/2(+)[404], and 1/2(-)[541] configurations, with a gamma softness for the 9/2(-)[514] configuration. This band has also been studied using the particle-rotor model, the results of which, however, are consistent with a triaxial shape with a gamma value of -15(p).

NJ Stone, JR Stone, CR Bingham, PM Walker (2013)Quasi-particle and collective magnetism: Rotation, pairing and blocking in high-K isomers, In: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics726(4-5)pp. 675-679

For the first time, a wide range of collective magnetic g-factors g, obtained from a novel analysis of experimental data for multi-quasi-particle configurations in high-K isomers, is shown to exhibit a striking systematic variation with the relative number of proton and neutron quasi-particles, N-N. Using the principle of additivity, the quasi-particle contribution to magnetism in high-K isomers of Lu-Re, Z=71-75, has been estimated. Based on these estimates, band-structure branching ratio data are used to explore the behavior of the collective contribution as the number and proton/neutron nature (N, N), of the quasi-particle excitations, change. Basic ideas of pairing, its quenching by quasi-particle excitation and the consequent changes to moment of inertia and collective magnetism are discussed. Existing model calculations do not reproduce the observed g variation adequately. The paired superfluid system of nucleons in these nuclei, and their excitations, present properties of general physics interest. The new-found systematic behavior of g in multi-quasi-particle excitations of this unique system, showing variation from close to zero for multi-neutron states to above 0.5 for multi-proton states, opens a fresh window on these effects and raises the important question of just which nucleons contribute to the 'collective' properties of these nuclei. © 2013 Elsevier B.V.

C. J. Pearson, P. M. Walker, C. S. Purry, G. D. Dracoulis, S. Bayer, A. P. Byrne, T. Kibédi, F. G. Kondev, T. Shizuma, R. A. Bark, G. Sletten, S. Frauendorf (1997)Tilted Rotation and Backbending in an Odd-Proton Nucleus, In: Physical Review Letters79(4)pp. 605-608

Tilted-axis rotation, arising from Fermi-aligned configurations, has been observed for the first time to cause backbending in an odd-proton nucleus. In 181Re, two t-bands are found to be energetically favored relative to the usual rotation-aligned s-bands, presenting an alternative form of cold nuclear rotation. Interactions between the bands are weak, and unambiguous comparisons with tilted-axis-cranking calculations can be made.

C Wheldon, PM Walker, PH Regan, T Saitoh, N Hashimoto, G Sletten, FR Xu (1999)Triaxial nuclear shapes at high angular momentum, In: PHYSICAL REVIEW C59(5)pp. R2334-R2338 AMERICAN PHYSICAL SOC
S Mohammadi, Z Podolyak, G de Angelis, M Axiotis, D Bazzacco, PG Bizzeti, F Brandolini, R Broda, D Bucurescu, E Farnea, W Gelletly, A Gadea, M Ionescu-Bujor, A Iordachescu, T Kroll, S Longdown, S Lunardi, N Marginean, T Martinez, NH Medina, B Quintana, PH Regan, B Rubio, CA Ur, JJV Dobon, PM Walker, YH Zhang (2004)High-spin states populated in deep-inelastic reactions, In: BRAZILIAN JOURNAL OF PHYSICS34(3A)pp. 792-795
N Minkov, PM Walker (2012)Magnetic moments of K isomers as indicators of octupole collectivity, In: EUROPEAN PHYSICAL JOURNAL A48(6)ARTN 8pp. ?-? SPRINGER
CM Shand, E Wilson, Z Podolyak, H Grawe, BA Brown, B Fornal, RVF Janssens, M Bowry, M Bunce, MP Carpenter, RJ Carroll, CJ Chiara, N Cieplicka-Orynczak, AY Deo, GD Dracoulis, CR Hoffman, RS Kempley, FG Kondev, GJ Lane, T Lauritsen, G Lotay, MW Reed, PH Regan, C Rodriguez-Triguero, D Seweryniak, B Szpak, PM Walker, S Zhu (2015)STRUCTURE OF Pb-207 POPULATED IN Pb-208+Pb-208 DEEP-INELASTIC COLLISIONS, In: ACTA PHYSICA POLONICA B46(3)pp. 619-622 WYDAWNICTWO UNIWERSYTETU JAGIELLONSKIEGO

The yrast structure of 207Pb above the 13=2+ isomeric state has been investigated in deep-inelastic collisions of 208Pb and 208Pb at ATLAS, Argonne National Laboratory. New and previously observed transitions were measured using the Gammasphere detector array. The level scheme of 207Pb is presented up to ∼ 6 MeV, built using coincidence and γ-ray intensity analyses. Spin and parity assignments of states were made, based on angular distributions and comparisons to shell model calculations.

M Grieser, YA Litvinov, R Raabe, K Blaum, Y Blumenfeld, PA Butler, F Wenander, PJ Woods, M Aliotta, A Andreyev, A Artemyev, D Atanasov, T Aumann, D Balabanski, A Barzakh, L Batist, A-P Bernardes, D Bernhardt, J Billowes, S Bishop, M Borge, I Borzov, F Bosch, AJ Boston, C Brandau, W Catford, R Catherall, J Cederkäll, D Cullen, T Davinson, I Dillmann, C Dimopoulou, G Dracoulis, CE Düllmann, P Egelhof, A Estrade, D Fischer, K Flanagan, L Fraile, MA Fraser, SJ Freeman, H Geissel, J Gerl, P Greenlees, RE Grisenti, D Habs, R von Hahn, S Hagmann, M Hausmann, JJ He, M Heil, M Huyse, D Jenkins, A Jokinen, B Jonson, DT Joss, Y Kadi, N Kalantar-Nayestanaki, BP Kay, O Kiselev, H-J Kluge, M Kowalska, C Kozhuharov, S Kreim, T Kröll, J Kurcewicz, M Labiche, RC Lemmon, M Lestinsky, G Lotay, XW Ma, M Marta, J Meng, D Mücher, I Mukha, A Müller, AS Murphy, G Neyens, T Nilsson, C Nociforo, W Nörtershäuser, RD Page, M Pasini, N Petridis, N Pietralla, M Pfützner, Z Podolyák, P Regan, MW Reed, R Reifarth, P Reiter, R Repnow, K Riisager, B Rubio, MS Sanjari, DW Savin, C Scheidenberger, S Schippers, D Schneider, R Schuch, D Schwalm, L Schweikhard, D Shubina, E Siesling, H Simon, J Simpson, J Smith, K Sonnabend, M Steck, T Stora, T Stöhlker, B Sun, A Surzhykov, F Suzaki, O Tarasov, S Trotsenko, XL Tu, P Van Duppen, C Volpe, D Voulot, PM Walker, E Wildner, N Winckler, DFA Winters, A Wolf, HS Xu, A Yakushev, T Yamaguchi, YJ Yuan, YH Zhang, K Zuber (2012)Storage ring at HIE-ISOLDE: Technical design report: Technical design report, In: European Physical Journal: Special Topics207(1)pp. 1-117 EDP Sciences/Springer

We propose to install a storage ring at an ISOL-type radioactive beam facility for the first time. Specifically, we intend to setup the heavy-ion, low-energy ring TSR at the HIE-ISOLDE facility in CERN, Geneva. Such a facility will provide a capability for experiments with stored secondary beams that is unique in the world. The envisaged physics programme is rich and varied, spanning from investigations of nuclear ground-state properties and reaction studies of astrophysical relevance, to investigations with highly-charged ions and pure isomeric beams. The TSR might also be employed for removal of isobaric contaminants from stored ion beams and for systematic studies within the neutrino beam programme. In addition to experiments performed using beams recirculating within the ring, cooled beams can also be extracted and exploited by external spectrometers for high-precision measurements. The existing TSR, which is presently in operation at the Max-Planck Institute for Nuclear Physics in Heidelberg, is well-suited and can be employed for this purpose. The physics cases as well as technical details of the existing ring facility and of the beam and infrastructure requirements at HIE-ISOLDE are discussed in the present technical design report.

Jonathan England, I.S. Grant, J.A.R. Griffith, D.E. Evans, D.A. Eastham, G.W.A. Newton, P.M. Walker (1990)Isotope shifts and hyperfine splitting in144-154Sm I, In: Journal of Physics G: Nuclear and Particle Physics16(1)pp. 105-123 IOP Publishing

The isotope shifts and hyperfine splitting have been measured in 144-154Sm I using the crossed-beam laser fluorescence method. Transitions at 598.98 nm and 570.68 nm were investigated for all isotopes except 146Sm and 153Sm, in which measurements were only obtained at 570.68 nm. Laser-induced fluorescence has not previously been reported for 145Sm: the hyperfine structure for the ground state of this isotope leads to mu =1.123 mu N, Q(spectroscopic)=-0.60e2b2 and delta (r2) (144-145)=0.11 fm2. The magnetic dipole and electric quadrupole moments of the odd isotopes and the changes in mean square radii of the even ones are shown to be consistent with the information obtained from nuclear spectroscopy.

S D Al-Garni, P H Regan, P M Walker, E Roeckl, R Kirchner, F R Xu, L Batist, A Blazhev, R Borcea, D M Cullen, J Doring, H M El-Masri, J G Narro, H Grawe, M La Commara, C Mazzoechi, I Mukha, C J Pearson, C Plettner, K Schmidt, W D Schmidt-Ott, Y Shimbara, C Wheldon, R Wood, S C Wooding (2004)Evidence for a High-Spin Beta-Decaying Isomer in Lu-177, In: Physical Review C69(2)

Nuclei in the A similar to 180 region have been populated and investigated in a series of multinucleon transfer and deep-inelastic reactions involving an 11.4 MeV per nucleon Xe-136 beam produced by the GSI UNILAC accelerator, impinging on a selection of tantalum and tungsten targets. The reaction products were released from a thermal ion source and subsequently mass selected using the GSI on-line mass separator. The unexpectedly high yield of gamma rays associated with the decay of the well established K-pi=37/2(-),t(1/2)=51.4 min isomer in Hf-177(72) and anomalous half-life characteristics associated with this decay lead to these data being interpreted as the beta(-) decay of a high-K isomer in the mother nucleus, Lu-177. By comparing the experimental findings with the predictions obtained from multi-quasiparticle blocked-BCS-Nilsson calculations, the proposed decay is suggested to be from a K-pi=39/2(-) five-quasiparticle state in Lu-177(71). A half-life of 7 +/- 2 min is determined for this beta-decay path which is estimated to have an excitation energy of approximate to3.9 MeV above the Lu-177 ground state.

S Al-Garni, PM Walker, PH Regan, JG Narro, HM El-Masri, E Roeckl, R Kirchner, M La Commara, C Mazzocchi, H Grawe, R Borcea, J Doring, SC Wooding, K Schmidt, C Wheldon, DM Cullen, WD Schmidt-Ott (2002)Evidence for a K approximate to.139/2 beta-decaying isomer in Lu-177, In: NUCLEAR PHYSICS IN THE 21ST CENTURY610pp. 854-858
Z Podolyak, M Caamano, PH Regan, PM Walker, P Mayet, J Gerl, C Schlegel, M Hellstrom, M Mineva, M Pfutzner (2002)Isomeric decays in neutron-rich W, Os and Pt nuclei, In: PROGRESS OF THEORETICAL PHYSICS SUPPLEMENT(146)pp. 467-472
G Benzoni, AI Morales, A Bracco, F Camera, FCL Crespi, AM Corsi, S Leoni, B Million, R Nicolini, O Wieland, JJ Valiente-Dobón, A Gottardo, G de Angelis, DR Napoli, E Sahin, A Gottardo, S Lunardi, A Bracco, F Camera, FCL Crespi, AM Corsi, S Leoni, R Nicolini, A Gadea, A Algora, S Lunardi, D Bazzacco, E Farnea, R Menegazzo, D Mengoni, F Recchia, CA Ur, P Boutachkov, M Górska, S Pietri, H Weick, ML Cortes, C Domingo-Pardo, T Engert, F Farinon, H Geissel, J Gerl, N Goel, E Gregor, T Habermann, R Hoischen, I Kojouharov, N Kurz, F Naqvi, C Nociforo, A Prochazka, W Prokopowicz, H Schaffner, A Sharma, H-J Wollersheim, AM Bruce, AM Denis Bacelar, J Grebosz, Z Podolyak, PH Regan, N Al-Dahan, M Bowry, M Bunce, AY Deo, GF Farrelly, MW Reed, TPD Swan, PM Walker, M Pfützner, J Alcántara Núñez, Y Ayyad, J Benlliure, N Alkhomashi, PRP Allegro, RV Ribas, E Casarejos, M Doncel, Z Dombradi, K Eppinger, S Klupp, K Steiger, R Hoischen, D Rudolph, R Janik, B Sitar, P Strmen, I Szarka, S Mandal, D Siwal, F Naqvi, AM Corsi, N Al-Dahan, PM Walker (2012)First measurement of beta decay half-lives in neutron-rich Tl and Bi isotopes, In: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics715(4-5)pp. 293-297 Elsevier

Neutron-rich isotopes around lead, beyond N= 126, have been studied exploiting the fragmentation of an uranium primary beam at the FRS-RISING setup at GSI. For the first time β-decay half-lives of Bi and Tl isotopes have been derived. The half-lives have been extracted using a numerical simulation developed for experiments in high-background conditions. Comparison with state of the art models used in r-process calculations is given, showing a systematic underestimation of the experimental values, at variance from close-lying nuclei. © 2012 Elsevier B.V.

P-A Söderström, Philip Walker, J Wu, HL Liu, Patrick Regan, H Watanabe, P Doornenbal, Z Korkulu, P Lee, JJ Liu, G Lorusso, S Nishimura, VH Phong, T Sumikama, FR Xu, S Lalkovski, Gavin Lotay, Z Patel, Zsolt Podolyak, Callum Shand (2016)K-mixing in the doubly mid-shell nuclide 170Dy and the role of vibrational degeneracy, In: Physics Letters B762pp. 404-408 Elsevier

A detailed study of the structure of the doubly mid-shell nucleus View the MathML source has been carried out, following isomeric and β decay. We have measured the yrast band up to the spin-parity Jπ=6+ state, the K=2γ -vibration band up to the 5+ state, a low-lying negative-parity band based on a 2− state that could be a candidate for the lowest energy octupole vibration state within this nucleus, and a candidate for the Kπ=6+ two quasi-particle isomer. This state was determined to have an excitation energy of 1643.91(23) keV and a half life of 0.99(4) μs, with a reduced hindrance for its decay to the ground-state band an order of magnitude lower than predicted by NpNn systematics. This is interpreted as being due to γ -vibrational mixing from a near degeneracy of the isomer and the 6+ state of the γ band. Furthermore, the parent nucleus 170Tb has been determined to have a half-life of View the MathML source s with a possible spin-parity of 2−.

F. R. Xu, E. G. Zhao, R. Wyss, P. M. Walker (2004)Enhanced Stability of Superheavy Nuclei Due to High-Spin Isomerism, In: Physical Review Letters92(252501)
G.X. Zhang, H. Watanabe, G.D. Dracoulis, F.G. Kondev, G.J. Lane, P.H. Regan, P.-A. Söderström, P.M. Walker, K. Yoshida, H. Kanaoka, Z. Korkulu, P.S. Lee, J.J. Liu, S. Nishimura, J. Wu, A. Yagi, D.S. Ahn, T. Alharbi, H. Baba, F. Browne, A.M. Bruce, M.P. Carpenter, R.J. Carroll, K.Y. Chae, C.J. Chiara, Zs. Dombradi, P. Doornenbal, A. Estrade, N. Fukuda, C. Griffin, E. Ideguchi, N. Inabe, T. Isobe, S. Kanaya, I. Kojouharov, T. Kubo, S. Kubono, N. Kurz, I. Kuti, S. Lalkovski, T. Lauritsen, C.S. Lee, E.J. Lee, C.J. Lister, G. Lorusso, G. Lotay, E.A. McCutchan, C.-B. Moon, I. Nishizuka, C.R. Nita, A. Odahara, Z. Patel, V.H. Phong, Zs. Podolyak, O.J. Roberts, H. Sakurai, H. Schaffner, D. Seweryniak, C.M. Shand, Y. Shimizu, T. Sumikama, H. Suzuki, H. Takeda, S. Terashima, Zs. Vajta, J.J. Valiente-Dóbon, Z.Y. Xu, S. Zhu (2019)Interplay of quasiparticle and vibrational excitations: First observation of isomeric states in ¹⁶⁸Dy and ¹⁶⁹Dy, In: Physics Letters B799135036pp. 1-7 Elsevier

The neutron-rich dysprosium isotopes ¹⁶⁸Dy₁₀₂ and ¹⁶⁹Dy₁₀₃ have been investigated using the EURICA γ-ray spectrometer, following production via in-flight fission of a high-intensity uranium beam in conjunction with isotope separation through the BigRIPS separator at RIBF in RIKEN Nishina Center. For ¹⁶⁸Dy, a previously unreported isomer with a half-life of 0.57(7) μs has been identified at an excitation energy of 1378 keV, and its presence affirmed independently using γ-γ-γ coincidence data taken with Gammasphere via two-proton transfer from an enriched ¹⁷⁰Er target performed at Argonne National Laboratory. This isomer is assigned Jπ = Kπ = (4⁻) based on the measured transition strengths, decay patterns, and the energy systematics for two-quasiparticle states in N = 102 isotones. The underlying mechanism of two-quasiparticle excitations in the doubly midshell region is discussed in comparison with the deformed QRPA and multi-quasiparticle calculations. In ¹⁶⁹Dy, the B(E2) value for the transition de-exciting the previously unreported Kπ = (1/2⁻) isomeric state at 166 keV to the Kπ = (5/2⁻) ground state is approximately two orders of magnitude larger than the E2 strength for the corresponding isomeric-decay transition in the N = 103 isotone ¹⁷³Yb, suggesting the presence of a significant γ-vibrational admixture with a dominant neutron one-quasiparticle component in the isomeric state.

S Nishimura, Z Li, H Watanabe, K Yoshinaga, T Sumikama, T Tachibana, K Yamaguchi, M Kurata-Nishimura, G Lorusso, Y Miyashita, A Odahara, H Baba, JS Berryman, N Blasi, A Bracco, F Camera, J Chiba, P Doornenbal, S Go, T Hashimoto, S Hayakawa, C Hinke, E Ideguchi, T Isobe, Y Ito, DG Jenkins, Y Kawada, N Kobayashi, Y Kondo, R Krücken, S Kubono, T Nakano, HJ Ong, S Ota, Z Podolyák, H Sakurai, H Scheit, K Steiger, D Steppenbeck, K Sugimoto, S Takano, A Takashima, K Tajiri, T Teranishi, Y Wakabayashi, PM Walker, O Wieland, H Yamaguchi (2011)β-Decay half-lives of very neutron-rich Kr to Tc isotopes on the boundary of the r-process path: An indication of fast r-matter flow, In: Physical Review Letters106(5)052502 American Physical Society

The β-decay half-lives of 38 neutron-rich isotopes from 36Kr to 43Tc have been measured; the half-lives of 100Kr, 103–105Sr, 106–108Y, 108–110Zr, 111,112Nb, 112–115Mo, and 116,117Tc are reported here. The results when compared with previous standard models indicate an overestimation in the predicted half-lives by a factor of 2 or more in the A≈110 region. A revised model based on the second generation gross theory of β decay better predicts the measured half-lives and suggests a more rapid flow of the rapid neutron-capture process (r-matter flow) through this region than previously predicted.

AI Morales, J Benlliure, M Gorska, H Grawe, S Verma, PH Regan, Z Podolyak, S Pietri, R Kumar, E Casarejos, A Algora, N Alkhomashi, H Alvarez-Pol, G Benzoni, A Blazhev, P Boutachkov, AM Bruce, LS Caceres, IJ Cullen, AMD Bacelar, P Doornenbal, ME Estevez-Aguado, G Farrelly, Y Fujita, AB Garnsworthy, W Gelletly, J Gerl, J Grebosz, R Hoischen, I Kojouharov, N Kurz, S Lalkovski, Z Liu, C Mihai, F Molina, D Muecher, W Prokopowicz, B Rubio, H Schaffner, SJ Steer, A Tamii, S Tashenov, JJ Valiente-Dobon, PM Walker, HJ Wollersheim, PJ Woods (2013)beta-delayed gamma-ray spectroscopy of Au-203,Au-204 and Pt200-202, In: PHYSICAL REVIEW C88(1)ARTN 0pp. ?-? AMER PHYSICAL SOC
X.Y. Liu, Z. Liu, B. Ding, P. Doornenbal, A. Obertelli, S.M. Lenzi, P.M. Walker, L.X. Chung, B.D. Linh, G. Authelet, H. Baba, D. Calvet, F. Château, A. Corsi, A. Delbart, J.-M. Gheller, A. Gillibert, T. Isobe, V. Lapoux, M. Matsushita, S. Momiyama, T. Motobayashi, M. Niikura, F. Nowacki, H. Otsu, C. Péron, A. Peyaud, E.C. Pollacco, J.-Y. Roussé, H. Sakurai, M. Sasano, Y. Shiga, S. Takeuchi, R. Taniuchi, T. Uesaka, H. Wang, K. Yoneda, Y.H. Lam, T.H. Huang, M.D. Sun, W.Q. Zhang, H.Y. Lu, D.S. Hou, F. Browne, Zs. Dombradi, S. Franchoo, F. Giacoppo, A. Gottardo, K. Hadynska-Klek, Z. Korkulu, S. Koyama, Y. Kubota, J. Lee, M. Lettmann, R. Lozeva, K. Matsui, T. Miyazaki, S. Nishimura, C. Louchart, L. Olivier, S. Ota, Z. Patel, E. Sahin, C. Santamaria, C. Shand, P.-A. Söderström, G.L. Stefan, D. Steppenbeck, T. Sumikama, D. Suzuki, Zs. Vajta, V. Werner, J. Wu, Z. Xu, X.H. Zhou, Y.H. Zhang, H.S. Xu, F.S. Zhang (2018)Spectroscopy of 2565,67Mn: Strong coupling in the N = 40 “island of inversion”, In: Physics Letters B784pp. 392-396 Elsevier

Excited states in 63,65,67Mn were studied via in-beam γ-ray spectroscopy following knockout reactions from 68Fe. Similar level schemes, consisting of the 11/2−, 9/2−, 7/2− and 5/2 g.s.− level sequence, connected by I→I−1 transitions, were established, the first time for 65,67Mn. Their level structures show features consistent with strongly-coupled rotational bands with K=5/2 . State-of-the-art shell-model calculations with the modified LNPS effective interaction reproduce the observed levels remarkably well and suggest the dominance of 4-particle-4-hole neutron configurations for all the states. The data on the low-lying excited states of odd-mass 53−67Mn provide a textbook example of nuclear structure evolution from weak coupling through decoupling to strong coupling along a single isotopic chain on the n-rich side of the β stability line. These results help to deepen our understanding of the N=40 “island of inversion”.

HL Liu, FR Xu, PM Walker, CA Bertulani (2011)Effects of high-order deformation on high-K isomers in superheavy nuclei, In: Physical Review C - Nuclear Physics83(1)011303 American Physical Society

Using, for the first time, configuration-constrained potential-energy-surface calculations with the inclusion of β6 deformation, we find remarkable effects of the high-order deformation on the high-K isomers in 254No, the focus of recent spectroscopy experiments on superheavy nuclei. For shapes with multipolarity six, the isomers are more tightly bound and, microscopically, have enhanced deformed shell gaps at N=152 and Z=100. The inclusion of β6 deformation significantly improves the description of the very heavy high-K isomers.

P D Stevenson, M P Brine, Z Podolyak, P H Regan, P M Walker, J R Stone (2005)Shape Evolution in the Neutron-Rich Tungsten Region, In: Physical Review C72(4)

Recent experimental data on the low-lying states in W-190 show a change in the E(4(1)(+))/E(2(1)(+)) behavior compared to less neutron-rich neigbors. Self-consistent axially-deformed Hartree-Fock calculations, using a separable monopole interaction, of nuclei in the vicinity of W-190 are performed to systematically examine the evolution of ground state quadrupole deformations. It is found that the neutron number N=116 causes a coexistence of oblate and prolate shapes, with a weak dependence on proton number, thereby hindering the development of these isotones as well-deformed rotors.

PM Walker, YA Litvinov, H Geissel (2013)The ILIMA project at FAIR, In: International Journal of Mass Spectrometry349-35pp. 247-254 Elsevier

The Isomeric beams, LIfetimes and MAsses (ILIMA) collaboration will exploit heavy-ion storage rings at the Facility for Antiproton and Ion Research (FAIR) for the study of exotic nuclei. Single-ion sensitivity and exceptional production rates of bare or few-electron radioactive ions, with atomic numbers up to Z = 92, promise access to a wide range of short-lived nuclides for the first time. Measuring the masses, lifetimes and decay modes of ground and isomeric states with t > 10 μs will reveal key features of nuclear structure and nuclear astrophysics, extending, for example, to r-process waiting-point nuclides in the Pb region. © 2013 Elsevier B.V. All rights reserved.

R Knobel, M Diwisch, H Geissel, YA Litvinov, Z Patyk, WR Plaß, C Scheidenberger, B Sun, H Weick, F Bosch, D Boutin, L Chen, C Dimopoulou, A Dolinskii, B Franczak, B Franzke, M Hausmann, C Kozhuharov, J Kurcewicz, SA Litvinov, M Matos, M Mazzocco, G Munzenberg, S Nakajima, C Nociforo, F Nolden, T Ohtsubo, A Ozawa, J Stadlmann, M Steck, T Suzuki, PM Walker, M Winkler, T Yamaguchi (2016)New results from isochronous mass measurements of neutron-rich uranium fission fragments with the FRS-ESR-facility at GSI, In: European Physical Journal A: Hadrons and Nuclei52 Springer

Masses of uranium fission fragments have been measured with the FRagment Separator (FRS) combined with the Experimental Storage Ring (ESR) at GSI. A 410-415 MeV/u 238U projectile beam was fast extracted from the synchrotron SIS-18 with an average intensity of 109/spill. The projectiles were focused on a 1g/cm2 beryllium target at the entrance of the FRS to create neutron-rich isotopes via abrasion-fission. The fission fragments were spatially separated with the FRS and injected into the isochronous storage ring ESR for fast mass measurements without applying cooling. The Isochronous Mass Spectrometry (IMS) was performed under two different experimental conditions, with and without B ____(____rho____)-tagging at the high-resolution dispersive central focal plane of the FRS. The evaluation has been done for the combined data sets from both experiments with a new method of data analysis. The use of a correlation matrix has provided experimental mass values for 23 different neutron-rich isotopes for the first time and 6 masses with improved values. The new masses were obtained for nuclides in the element range from Se to Ce. The applied analysis has given access even to rare isotopes detected with an intensity of a few atoms per week. The novel data analysis and systematic error determination are described and the results are compared with extrapolations of experimental values and theoretical models.

D Atanasov, K Blaum, F Bosch, C Brandau, P Buehler, X Chen, I Dillmann, T Faestermann, B Gao, H Geissel, R Gernhaeuser, S Hagmann, T Izumikawa, P-M Hillenbrand, C Kozhuharov, J Kurcewicz, SA Litvinov, YA Litvinov, X Ma, G Muenzenberg, MA Najafi, F Nolden, T Ohtsubo, A Ozawa, FC Ozturk, Z Patyk, M Reed, R Reifarth, MS Sanjari, D Schneider, M Steck, T Stoehlker, B Sun, F Suzaki, T Suzuki, C Trageser, X Tu, T Uesaka, P Walker, M Wang, H Weick, N Winckler, P Woods, H Xu, T Yamaguchi, X Yan, Y Zhang (2015)Between atomic and nuclear physics: radioactive decays of highly-charged ions, In: JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS48(14)ARTN 1pp. ?-? IOP PUBLISHING LTD
AI Morales, G Benzoni, N Al-Dahan, S Vergani, Z Podolyak, PH Regan, TPD Swan, JJ Valiente-Dobon, A Bracco, P Boutachkov, FCL Crespi, J Gerl, M Gorska, S Pietri, PM Walker, H-J Wollersheim (2015)First measurement of the beta-decay half-life of Au-206, In: EPL111(5)ARTN 52001 EPL ASSOCIATION, EUROPEAN PHYSICAL SOCIETY
E Ngijoi-Yogo, S K Tandel, G Mukherjee, I Shestakova, P Chowdhury, C Y Wu, D Cline, A B Hayes, R Teng, R M Clark, P Fallon, A O Macchiavelli, K Vetter, F G Kondev, S Langdown, P M Walker, C Wheldon, D M Cullen (2007)Collective Rotation and Vibration in Neutron-Rich Hf-180,Hf-182 Nuclei, In: Physical Review C75(3)

High-spin states in neutron-rich Hf-180 and Hf-182 nuclei were populated through inelastic and transfer reactions with a Xe-136 beam incident on a thin Hf-180 target, and investigated using particle-gamma coincidence techniques. New collective band structures were observed, and previously known rotational and vibrational bands in these nuclei were extended to higher angular momenta. No obvious nucleon alignment was observed in the ground state band of either nucleus up to h omega=0.43 MeV, a significant delay compared to lighter even-even Hf isotopes. Woods-Saxon cranking calculations were performed to predict the nature of the first band crossings and shape evolution in Hf-180,Hf-182.

CS Purry, PM Walker, GD Dracoulis, T Kibedi, FG Kondev, S Bayer, AM Bruce, AP Byrne, W Gelletly, PH Regan, C Thwaites, O Burglin, N Rowley (1998)Multi-quasiparticle isomers and rotational bands in W-178, In: NUCLEAR PHYSICS A632(2)pp. 229-274 ELSEVIER SCIENCE BV
H. M. El-Masri, P. M. Walker, G. D. Dracoulis, T. Kibédi, A. P. Byrne, A. M. Bruce, J. N. Orce, A. Emmanouilidis, D. M. Cullen, C. Wheldon, F. R. Xu (2005)High-K states in the odd-odd nuclide 180Re, In: Physical Review C72(054306)
C Schlegel, PH Regan, M Pfutzner, J Gerl, M Hellstrom, Z Podolyak, M Caamano, P Mayet, A Aprahamian, J Benlliure, AM Bruce, PA Butler, DC Gil, DM Cullen, J Doring, T Enquist, E Farget, C Fox, JG Narro, W Gelletly, J Giovinazzo, M Gorska, H Grawe, R Grzywacz, A Kleinbohl, W Korten, M Lewitowicz, R Lucas, H Mach, M Mineva, C O'Leary, F De Oliveira, CJ Pearson, M Rejmund, M Sawicka, H Schaffner, K Schmidt, C Theisen, PM Walker, DD Warner, C Wheldon, HJ Wollersheim, S Wooding, F Xu (2000)K-isomers in very neutron-rich nuclei around mass 180, In: PHYSICA SCRIPTAT88pp. 72-76
D Shubina, RB Cakirli, YA Litvinov, K Blaum, C Brandau, F Bosch, JJ Carroll, RF Casten, DM Cullen, IJ Cullen, AY Deo, B Detwiler, C Dimopoulou, F Farinon, H Geissel, E Haettner, M Heil, RS Kempley, C Kozhuharov, R Knoebel, J Kurcewicz, N Kuzminchuk, SA Litvinov, Z Liu, R Mao, C Nociforo, F Nolden, Z Patyk, WR Plass, A Prochazka, MW Reed, MS Sanjari, C Scheidenberger, M Steck, T Stoehlker, B Sun, TPD Swan, G Trees, PM Walker, H Weick, N Winckler, M Winkler, PJ Woods, T Yamaguchi, C Zhou (2013)Schottky mass measurements of heavy neutron-rich nuclides in the element range 70 <= Z <= 79 at the GSI Experimental Storage Ring, In: PHYSICAL REVIEW C88(2)ARTN 0pp. ?-? AMER PHYSICAL SOC
A Gottardo, JJ Valiente-Dobón, G de Angelis, V Modamio, DR Napoli, E Sahin, S Lunardi, A Algora, PR John, SM Lenzi, G Benzoni, A Bracco, F Camera, FCL Crespi, A Corsi, S Leoni, B Million, AI Morales, R Nicolini, O Wieland, A Gadea, D Bazzacco, E Farnea, R Menegazzo, D Mengoni, F Recchia, CA Ur, P Boutachkov, M Górska, S Pietri, H Weick, ML Cortes, C Domingo-Pardo, T Engert, F Farinon, H Geissel, J Gerl, N Goel, E Gregor, T Habermann, R Hoischen, I Kojouharov, N Kurz, F Naqvi, C Nociforo, A Prochazka, W Prokopowicz, H Schaffner, A Sharma, H-J Wollersheim, AM Bruce, M Bunce, AM Denis Bacelar, J Grebosz, Z Podolyák, PH Regan, N Al-Dahan, M Bowry, AY Deo, GF Farrelly, MW Reed, TPD Swan, PM Walker, M Pfützner, Y Ayyad, J Benlliure, J Alcántara Núñez, N Alkhomashi, PRP Allegro, RV Ribas, E Casarejos, M Doncel, Z Dombradi, K Eppinger, S Klupp, K Steiger, D Rudolph, R Janik, B Sitar, P Strmen, I Szarka, S Mandal, D Siwal (2013)New μs isomers in the neutron-rich Hg nucleus, In: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics725(4-5)pp. 292-296

Neutron-rich nuclei in the lead region, beyond N=126, have been studied at the FRS-RISING setup at GSI, exploiting the fragmentation of a primary uranium beam. Two isomeric states have been identified in Hg: the 8 isomer expected from the seniority scheme in the νg shell and a second one at low spin and low excitation energy. The decay strength of the 8 isomer confirms the need of effective three-body forces in the case of neutron-rich lead isotopes. The other unexpected low-lying isomer has been tentatively assigned as a 3 state, although this is in contrast with theoretical expectations. © 2013 Elsevier B.V..

J Sethi, R Palit, JJ Carroll, S Karamian, S Saha, S Biswas, Z Naik, T Trivedi, MS Litz, P Datta, S Chattopadhyay, R Donthi, U Garg, S Jadhav, HC Jain, S Kumar, D Mehta, BS Naidu, GH Bhat, JA Sheikh, S Sihotra, PM Walker (2016)Low-lying states near the I-pi=6(+) isomer in Ag-108, In: JOURNAL OF PHYSICS G-NUCLEAR AND PARTICLE PHYSICS43(1)ARTN 01510 IOP PUBLISHING LTD
D A Eastham, Jonathan England, D E Evans, M J Fawcett, I S Grant, J A R Griffith, G W A Newton, P M Walker (1984)Optical isotope shift and hyperfine structure of153Sm, In: Journal of Physics G: Nuclear Physics10(12)pp. L271-L274

Measurements of the optical isotope shift and hyperfine structure of 153Sm are described. The quadrupole moments and mean square charge radii of samarium isotopes are discussed qualitatively in relation to nuclear deformation.