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

Akkoyun S, Algora A, Alikhani B, Ameil F, De Angelis G, Arnold L, Astier A, Ataç A, Aubert Y, Aufranc C, Austin A, Aydin S, Azaiez F, Badoer S, Balabanski DL, Barrientos D, Baulieu G, Baumann R, Bazzacco D, Beck FA, Beck T, Bednarczyk P, Bellato M, Bentley MA, Benzoni G, Berthier R, Berti L, Beunard R, Lo Bianco G, Birkenbach B, Bizzeti PG, Bizzeti-Sona AM, Le Blanc F, Blasco JM, Blasi N, Bloor D, Boiano C, Borsato M, Bortolato D, Boston AJ, Boston HC, Bourgault P, Boutachkov P, Bouty A, Bracco A, Brambilla S, Brawn IP, Brondi A, Broussard S, Bruyneel B, Bucurescu D, Burrows I, Bürger A, Cabaret S, Cahan B, Calore E, Camera F, Capsoni A, Carrió F, Casati G, Castoldi M, Cederwall B, Cercus J-L, Chambert V, El Chambit M, Chapman R, Charles L, Chavas J, Clément E, Cocconi P, Coelli S, Coleman-Smith PJ, Colombo A, Colosimo S, Commeaux C, Conventi D, Cooper RJ, Corsi A, Cortesi A, Costa L, Crespi FCL, Cresswell JR, Cullen DM, Curien D, Czermak A, Delbourg D, Depalo R, Descombes T, Désesquelles P, Detistov P, Diarra C, Didierjean F, Dimmock MR, Doan QT, Domingo-Pardo C, Doncel M, Dorangeville F, Dosme N, Drouen Y, Duchêne G, Dulny B, Eberth J, Edelbruck P, Egea J, Engert T, Erduran MN, Ertürk S, Fanin C, Fantinel S, Farnea E, Faul T, Filliger M, Filmer F, Finck C, De France G, Gadea A, Gast W, Geraci A, Gerl J, Gernhäuser R, Giannatiempo A, Giaz A, Gibelin L, Givechev A, Goel N, González V, Gottardo A, Grave X, Gr)bosz J, Griffiths R, Grint AN, Gros P, Guevara L, Gulmini M, Görgen A, Ha HTM, Habermann T, Harkness LJ, Harroch H, Hauschild K, He C, Hernández-Prieto A, Hervieu B, Hess H, Hüyük T, Ince E, Isocrate R, Jaworski G, Johnson A, Jolie J, Jones P, Jonson B, Joshi P, Judson DS, Jungclaus A, Kaci M, Karkour N, Karolak M, Ka_ka_ A, Kebbiri M, Kempley RS, Khaplanov A, Klupp S, Kogimtzis M, Kojouharov I, Korichi A, Korten W, Kröll T, Krücken R, Kurz N, Ky BY, Labiche M, Lafay X, Lavergne L, Lazarus IH, Leboutelier S, Lefebvre F, Legay E, Legeard L, Lelli F, Lenzi SM, Leoni S, Lermitage A, Lersch D, Leske J, Letts SC, Lhenoret S, Lieder RM, Linget D, Ljungvall J, Lopez-Martens A, Lotodé A, Lunardi S, Maj A, Van Der Marel J, Mariette Y, Marginean N, Marginean R, Maron G, Mather AR, M)czyDski W, Mendéz V, Medina P, Melon B, Menegazzo R, Mengoni D, Merchan E, Mihailescu L, Michelagnoli C, Mierzejewski J, Milechina L, Million B, Mitev K, Molini P, Montanari D, Moon S, Morbiducci F, Moro R, Morrall PS, Möller O, Nannini A, Napoli DR, Nelson L, Nespolo M, Ngo VL, Nicoletto M, Nicolini R, Le Noa Y, Nolan PJ, Norman M, Nyberg J, Obertelli A, Olariu A, Orlandi R, Oxley DC, Özben C, Ozille M, Oziol C, Pachoud E, Palacz M, Palin J, Pancin J, Parisel C, Pariset P, Pascovici G, Peghin R, Pellegri L, Perego A, Perrier S, Petcu M, Petkov P, Petrache C, Pierre E, Pietralla N, Pietri S, Pignanelli M, Piqueras I, Podolyak Z, Le Pouhalec P, Pouthas J, Pugnére D, Pucknell VFE, Pullia A, Quintana B, Raine R, Rainovski G, Ramina L, Rampazzo G, La Rana G, Rebeschini M, Recchia F, Redon N, Reese M, Reiter P, Regan PH, Riboldi S, Richer M, Rigato M, Rigby S, Ripamonti G, Robinson AP, Robin J, Roccaz J, Ropert J-A, Rossé B, Rossi Alvarez C, Rosso D, Rubio B, Rudolph D, Saillant F, ^ahin E, Salomon F, Salsac M-D, Salt J, Salvato G, Sampson J, Sanchis E, Santos C, Schaffner H, Schlarb M, Scraggs DP, Seddon D, ^enyiçit M, Sigward M-H, Simpson G, Simpson J, Slee M, Smith JF, Sona P, Sowicki B, Spolaore P, Stahl C, Stanios T, Stefanova E, Stézowski O, Strachan J, Suliman G, Söderström P-A, Tain JL, Tanguy S, Tashenov S, Theisen C, Thornhill J, Tomasi F, Toniolo N, Touzery R, Travers B, Triossi A, Tripon M, Tun-Lanoë KMM, Turcato M, Unsworth C, Ur CA, Valiente-Dobon JJ, Vandone V, Vardaci E, Venturelli R, Veronese F, Veyssiere C, Viscione E, Wadsworth R, Walker PM, Warr N, Weber C, Weisshaar D, Wells D, Wieland O, Wiens A, Wittwer G, Wollersheim HJ, Zocca F, Zamfir NV, Zi)bliDski M, Zucchiatti A (2012) AGATA - Advanced GAmma Tracking Array,Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 668 pp. 26-58 Elsevier
Söderström P, Walker PM, Wu J, Liu H, Regan PH, Watanabe H, Doornenbal P, Korkulu Z, Lee P, Liu J, Lorusso G, Nishimura S, Phong V, Sumikama T, Xu F, Lalkovski S, Lotay GJ, Patel Z, Podolyak Z, Shand CM (2016) K-mixing in the doubly mid-shell nuclide 170Dy and the role of vibrational degeneracy,Physics Letters B 762 pp. 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 ² decay. We have measured the yrast band up to the spin-parity JÀ=6+ state, the K=2³ -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 KÀ=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) ¼s, 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 ³ -vibrational mixing from a near degeneracy of the isomer and the 6+ state of the ³ 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?.
Watanabe H, Zhang G, Yoshida K, Walker PM, Liu J, Wu J, Regan PH, Soderstrom P, Kanaoka H, Korkulu Z, Lee P, Nishimura S, Yagi A, Ahn D, Alharbi T, Baba H, Browne F, Bruce A, Fukuda R, Griffin C, Ideguchi E, Inabe N, Isobe T, Kanaya S, Kojouharov I, Kondev F, Kubo T, Kubono S, Kurz N, Kuti I, Lalkovski S, Lane; G, Lee C, Lee E, Lorusso G, Lotay GJ, Moon C, Nishizuka I, Nita C, Odahara A, Patel Z, Phong V, Podolyak Z, Roberts O, Sakurai H, Schaffner H, Shand CM, Shimizu Y, Sumikama T, Suzuki H, Takeda H, Terashima S, Vajta; Z, Valiente-Dobon J, Xu Z (2016) Long-lived K isomer and enhanced gamma vibration in the neutron-rich nucleus 172Dy: Collectivity beyond double midshell,Physics Letters B 760 (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 À = 8 ? has been identified at 1278 keV, which decays to the ground-state and ³-vibrational bands through hindered electromagnetic transitions, as well as to the daughter nucleus 172Ho via allowed ² decays. The robust nature of the K À = 8 ? isomer and the ground-state rotational band reveals an axially-symmetric structure for this nucleus. Meanwhile, the ³-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 ³ vibration is discussed in comparison with the deformed Quasiparticle Random-Phase Approximation based on a Skyrme energy-density functional.
Podolyak Z, Farrelly GF, Regan PH, Garnsworthy AB, Steer SJ, Gorska M, Benlliure J, Casarejos E, Pietri S, Gerl J, Wollersheim HJ, Kumar R, Molina F, Algora A, Alkhomashi N, Benzoni G, Blazhev A, Boutachkov P, Bruce AM, Caceres L, Cullen IJ, Bacelar AMD, Doornenbal P, Estevez ME, Fujita Y, Gelletly W, Geissel H, Grawe H, Grebosz J, Hoischen R, Kojouharov I, Lalkovski S, Liu Z, Maier KH, Mihai C, Muecher D, Rubio B, Schaffner H, Tamii A, Tashenov S, Valiente-Dobon JJ, Walker PM, Woods PJ (2009) Proton-hole excitation in the closed shell nucleus Au-205,PHYSICS LETTERS B 672 (2) pp. 116-119 ELSEVIER SCIENCE BV
Wilson E, Podolyák Z, Fornal B, Janssens RVF, Bowry M, Bunce M, Carpenter MP, Chiara CJ, Cieplicka N, Deo AY, Dracoulis GD, Grawe H, Hoffman CR, Kempley RS, Kondev FG, Lane GJ, Lauritsen T, Reed MW, Regan PH, Rodríguez Triguero C, Szpak B, Walker PM, Zhu S (2013) Core excitations across the neutron shell gap in 207Tl, Acta Physica Polonica B 44 (3) pp. 381-385
Deep-inelastic collisions of a 208Pb beam on a 208Pb target were performed using the ATLAS accelerator at Argonne National Laboratory. Prompt and delayed »-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 »-rays from its bettercharacterised reaction partner 209Bi. A number of new transitions were found in 207Tl.
Ngijoi-Yogo E, Tandel SK, Mukherjee G, Shestakova I, Chowdhury P, Wu CY, Cline D, Hayes AB, Teng R, Clark RM, Fallon P, Macchiavelli AO, Vetter K, Kondev FG, Langdown S, Walker PM, Wheldon C, Cullen DM (2007) Collective rotation and vibration in neutron-rich Hf-180,Hf-182 nuclei, PHYSICAL REVIEW C 75 (3) ARTN 034305 AMERICAN PHYSICAL SOC
Reed MW, Walker PM, Cullen IJ, Deo AY, Kempley RS, Swan TPD, Litvinov YA, Bosch F, Brandau C, Shubina D, Winckler N, Litvinov YA, Blaum K, Dimopoulou C, Farinon F, Geissel H, Heil M, Knöbel R, Kozhuharov C, Kurcewicz J, Kuzminchuk N, Litvinov S, Nociforo C, Nolden F, Prochazka A, Scheidenberger C, Steck M, Stöhlker T, Sun B, Weick H, Winckler N, Winkler M, Brandau C, Carroll JJ, Cullen DM, Detwiler B, Trees G, Dracoulis GD, Geissel H, Haettner E, Pla WR, Scheidenberger C, Liu Z, Woods PJ, Mao R, Stöhlker T, Yamaguchi T (2012) Technique for resolving low-lying isomers in the experimental storage ring (ESR) and the occurrence of an isomeric state in
Re
,
Journal of Physics: Conference Series 381 (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
Tu XL, Mei B, Zhang YH, Xu HS, Litvinov YA, Huang WJ, Podolyak Z, Kelic-Heil A, Zhang W, Litvinov SA, Blaum K, Zhou XH, Shuai P, Wang M, Gao BS, Chen XC, Yuan YJ, Xia JW, Yang JC, Hu ZG, Ma XW, Sun BH, Yan XL, Mao RS, Sun ZY, Xiao GQ, Xu X, Walker PM, Yamaguchi T, Bosch F, Winckler N, Chen RJ, Xing YM, Fu CY, Liu DW, Zeng Q, Ge Z, Sun Y, Zhao HW, Zhao TC (2015) Study of projectile fragmentation reaction with isochronous mass spectrometry,PHYSICA SCRIPTA T166 ARTN 01400 IOP PUBLISHING LTD
Minkov N, Walker PM (2016) Octupole deformations in high-K isomeric states of heavy and superheavy nuclei, INTERNATIONAL CONFERENCE ON NUCLEAR STRUCTURE AND RELATED TOPICS (NSRT15) 107 E D P SCIENCES
Gottardo A, Valiente-Dobón JJ, Benzoni G, Gadea A, Lunardi S, Boutachkov P, Bruce AM, Górska M, Grebosz J, Pietri S, Podolyák Z, Pfützner M, Regan PH, Weick H, Núñez JA, Algora A, Al-Dahan N, De Angelis G, Ayyad Y, Alkhomashi N, Allegro PRP, Bazzacco D, Benlliure J, Bowry M, Bracco A, Bunce M, Camera F, Casarejos E, Cortes ML, Crespi FCL, Corsi A, Bacelar AMD, Deo AY, Domingo-Pardo C, Doncel M, Dombradi Z, Engert T, Eppinger K, Farrelly GF, Farinon F, Farnea E, Geissel H, Gerl J, Goel N, Gregor E, Habermann T, Hoischen R, Janik R, John PR, Klupp S, Kojouharov I, Kurz N, Lenzi SM, Leoni S, Mandal S, Menegazzo R, Mengoni D, Million B, Modamio V, Morales AI, Napoli DR, Naqvi F, Nicolini R, Nociforo C, Prochazka A, Prokopowicz W, Recchia F, Ribas RV, Reed MW, Rudolph D, Sahin E, Schaffner H, Sharma A, Sitar B, Siwal D, Steiger K, Strmen P, Swan TPD, Szarka I, Ur CA, Walker PM, Wieland O, Wollersheim HJ (2014) New isomers in the neutron-rich region beyond 208Pb,EPJ Web of Conferences 66
The region of neutron-rich nuclei beyond 208Pb has been very difficult to explore due to its high mass and exoticity. However, recent experimental improvements allowed one to perform a quite extended isomer decay spectroscopy of these nuclei. © Owned by the authors, published by EDP Sciences, 2014.
Nakhostin M, Walker PM (2010) Application of digital zero-crossing technique for neutron-gamma discrimination in liquid organic scintillation detectors,Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 621 (1-3) pp. 498-501 Elsevier
An algorithm for digital implementation of the zero-crossing method for n/³
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.
Nakhostin M, Walker PM (2010) Determination of gas amplification factor by digital waveform analysis of avalanche counter signals,NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT 615 (1) pp. 53-56 ELSEVIER SCIENCE BV
Patel Z, Podolyak Z, Walker PM, Regan PH, Soederstroem P-A, Watanabe H, Ideguchi E, Simpson GS, Nishimura S, Browne F, Doornenbal R, Lorusso G, Rice S, Sinclair L, Sumikama T, Wu J, Xu ZY, Aoi N, Baba H, Garrote FLB, Benzoni G, Daido R, Dombradi Z, Fang Y, Fukuda N, Gey G, Go S, Gottardo A, Inabe N, Isobe T, Kameda D, Kobayashi K, Kobayashi M, Komatsubara T, Kojouharov I, Kubo T, Kurz N, Kuti I, Li Z, Liu HL, Matsushita M, Michimasa S, Moony C-B, Nishibata H, Nishizuka I, Odahara A, Sahin E, Sakurai H, Schaffner H, Suzuki H, Takeda H, Tanaka M, Taprogge J, Vajta Z, Xu FR, Yagi A, Yokoyama R (2016) Decay spectroscopy of Sm-160: The lightest four-quasiparticle K isomer,PHYSICS LETTERS B 753 pp. 182-186 ELSEVIER SCIENCE BV
Jiao CF, Shi Y, Xu FR, Xu FR, Sun Y, Sun Y, Walker PM, Walker PM (2012) Competition between collective oblate rotation and non-collective prolate K isomerism in neutron-rich tungsten isotopes, Science China: Physics, Mechanics and Astronomy 55 (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 KÆ = 8
configuration. Low-lying high-K four-quasiparticle states are predicted. Of particular interest is the prediction of the KÆ = 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.
Sun B, Litvinov YA, Walker PM, Beckert K, Beller P, Bosch F, Boutin D, Brandau C, Chen L, Dimopoulou C, Geissel H, Knoebel R, Kozhunharov C, Kurcewicz J, Litvinov SA, Mazzocco M, Meng J, Nociforo C, Nolden F, Plass WR, Scheidenberger C, Steck M, Weick H, Winkler M (2007) Discovery of a new long-lived isomeric state in Ce-125, EUROPEAN PHYSICAL JOURNAL A 31 (3) pp. 393-394 SPRINGER
Alkhomashi N, Regan PH, Podolyak Z, Pietri S, Garnsworthy AB, Steer SJ, Benlliure J, Caserejos E, Casten RF, Gerl J, Wollersheim HJ, Grebosz J, Farrelly G, Gorska M, Kojouharov I, Schaffner H, Algora A, Benzoni G, Blazhev A, Boutachkov P, Bruce AM, Bacelar AMD, Cullen IJ, Caceres L, Doornenbal P, Estevez ME, Fujita Y, Gelletly W, Hoischen R, Kumar R, Kurz N, Lalkovski S, Liu Z, Mihai C, Molina F, Morales AI, Muecher D, Prokopowicz W, Rubio B, Shi Y, Tamii A, Tashenov S, Valiente-Dobon JJ, Walker PM, Woods PJ, Xu FR (2009) beta(-)-delayed spectroscopy of neutron-rich tantalum nuclei: Shape evolution in neutron-rich tungsten isotopes,PHYSICAL REVIEW C 80 (6) ARTN 064308 AMER PHYSICAL SOC
Regan PH, Gamsworthy AB, Steer SJ, Pletri S, Podolyak Z, Rudolph D, Gorska M, Caceres L, Wemer-Malento E, Gerl J, Wollersheim HJ, Becker F, Bednarczyk P, Doornenbal PD, Geissel H, Grawe H, Grebosz J, Hoischen R, Kelic A, Kojouharov I, Kurz N, Montes F, Prokopowicz W, Saito T, Schaffner H, Tashenov S, Heinz A, Pfuetzner M, Kurtukian-Nieto T, Benzoni G, Hellstroem M, Jungclaus A, Andersson L-L, Atanasova L, Balabanski DL, Bentley MA, Blank B, Blazhev A, Brandau C, Brown J, Bruce AM, Camera F, Catford WN, Cullen IJ, Dombradi Z, Estevez E, Fahlander C, Gelletly W, Ilie G, Johansson EK, Jolie J, Jones GA, Kmiecik M, Kondev G, Lalkovski S, Liu Z, Maj A, Myalski S, Schwertel S, Shizuma T, Simons AJ, Walker PM, Wieland O (2007) First results from the stopped RISING campaign at GSI: The mapping of isomeric decays in highly exotic nuclei, Six International Conference of the Balkan Physical Union 899 pp. 19-22 AMER INST PHYSICS
Jones GA, Walker PM, Podoydk Z, Regan PH, Williams SJ, Carpentert MP, Carroll JJ, Chakrawarthy RS, Chowdhury P, Cullen IJ, Dracoulis GD, Gamsworthy AB, Hackman G, Janssens RVF, Khoo TL, Kondev FG, Lane GJ, Liu Z, Seweryniak D, Thompson NJ, Zhu S (2006) Microsecond and nanosecond isomers populated in fission reactions, FUSION06: Reaction Mechanisms and Nuclear Structure at the Coulomb Barrier 853 pp. 342-349 AMER INST PHYSICS
Shi Y, Xu FR, Walker PM, Dracoulis GD (2012) Superdeformed multi-quasiparticle high-K states and possible isomers in Pb and Po isotopes,PHYSICAL REVIEW C 85 (6) ARTN 064304 AMER PHYSICAL SOC
Podolyak Z, Gerl J, Hellstrom M, Becker F, Gladnishki KA, Gorska M, Kelic A, Kopatch Y, Mandal S, Regan PH, Schmidt KH, Walker PM, Wollersheim HJ, Banu A, Benzoni G, Boardman H, Casarejos E, Ekman J, Geissel H, Grawe H, Hohn D, Kojouharov I, Leske J, Lozeva R, Mineva MN, Neyens G, Page RD, Pearson CJ, Portillo M, Rudolph D, Saito N, Schaffner H, Sohler D, Summerer K, Valiente-Dobon JJ, Wheldon C, Weick H, Winkler M (2006) High angular momentum states populated in fragmentation reactions, PHYSICS LETTERS B 632 (2-3) pp. 203-206 ELSEVIER SCIENCE BV
Sumikama T, Yoshinaga K, Watanabe H, Nishimura S, Miyashita Y, Yamaguchi K, Sugimoto K, Chiba J, Li Z, Baba H, Berryman JS, Blasi N, Bracco A, Camera F, Doornenbal P, Go S, Hashimoto T, Hayakawa S, Hinke C, Ideguchi E, Isobe T, Ito Y, Jenkins DG, Kawada Y, Kobayashi N, Kondo Y, Kruecken R, Kubono S, Lorusso G, Nakano T, Kurata-Nishimura M, Odahara A, Ong HJ, Ota S, Podolyak Z, Sakurai H, Scheit H, Steiger K, Steppenbeck D, Takano S, Takashima A, Tajiri K, Teranishi T, Wakabayashi Y, Walker PM, Wieland O, Yamaguchi H (2011) Structural Evolution in the Neutron-Rich Nuclei Zr-106 and Zr-108,PHYSICAL REVIEW LETTERS 106 (20) ARTN 202501 AMER PHYSICAL SOC
Mukherjee G, Chowdhury P, Kondev FG, Walker PM, Dracoulis GD, D'Alarcao R, Shestakova I, Abu Saleem K, Ahmad I, Carpenter MP (2010) K-hindered decay of a six-quasiparticle isomer in Hf176,Physical Review C - Nuclear Physics 82 (5) 054316 American Physical Society
Knöbel R, Litvinov SA, Sun B, Beckert K, Beller P, Bosch F, Boutin D, Brandau C, Chen L, Cullen IJ, Dimopoulou C, Dolinskii A, Fabian B, Geissel H, Hausmann M, Kozhuharov C, Kurcewicz J, Litvinov YA, Liu Z, Mazzocco M, Montes F, Münzenberg G, Musumarra A, Nakajima S, Nociforo C, Nolden F, Ohtsubo T, Ozawa A, Patyk Z, Plaß WR, Scheidenberger C, Shindo M, Steck M, Suzuki T, Walker PM, Weick H, Winckler N, Winkler M, Yamaguchi T (2007) New developments for isochronous mass measurements of short-lived nuclei, AIP Conference Proceedings 891 pp. 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.
Litvinov YA, Geissel H, Beckert K, Beller P, Bosch F, Boutin D, Brandau C, Chen L, Cullen I, Dimopoulou C, Fabian B, Hausmann M, Klepper O, Knoebel R, Kozhuharov C, Kurcewicz J, Litvinov SA, Liu Z, Mazzocco M, Montes F, Muenzenberg G, Musumarra A, Nakajima S, Nociforo C, Nolden F, Ohtsubo T, Ozawa A, Patyk Z, Plass W, Scheidenberger C, Steck M, Sun B, Suzuki T, Walker PM, Weick H, Scheidenberger C, Steck M, Sun B, Suzuki T, Walker PM, Weick H, Winckler N, Winckler M, Yamaguchi T (2007) Status of the experimental program on mass measurements of stored exotic nuclei at the FRS-ESR facility, NUCLEAR PHYSICS A 787 pp. 315C-320C ELSEVIER SCIENCE BV
Chen L, Litvinov YA, Plass WR, Beckert K, Beller P, Bosch F, Boutin D, Caceres L, Cakirli RB, Carroll JJ, Casten RF, Chakrawarthy RS, Cullen DM, Cullen IJ, Franzke B, Geissel H, Gerl J, Gorska M, Jones GA, Kishada A, Knoebel R, Kozhuharov C, Litvinov SA, Liu Z, Mandal S, Montes F, Muenzenberg G, Nolden F, Ohtsubo T, Patyk Z, Podolyak Z, Propri R, Rigby S, Saito N, Saito T, Scheidenberger C, Shindo M, Steck M, Ugorowski P, Walker PM, Williams S, Weick H, Winkler M, Wollersheim H-J, Yamaguchi T (2009) Schottky Mass Measurement of the Hg-208 Isotope: Implication for the Proton-Neutron Interaction Strength around Doubly Magic Pb-208,PHYSICAL REVIEW LETTERS 102 (12) ARTN 122503 AMER PHYSICAL SOC
Liu HL, Walker PM, Xu FR (2014) Favored configurations for four-quasiparticle K isomerism in the heaviest nuclei,Physical Review C - Nuclear Physics 89 (4)
Configuration-constrained potential-energy-surface calculations are performed including ²6 deformation to investigate high-K isomeric states in nuclei around 254No and 270Ds, the heaviest nuclei where there have been some observations of two-quasiparticle isomers, while data for four-quasiparticle isomers are scarce. We predict the prevalent occurrence of four-quasiparticle isomeric states in these nuclei, together with their favored configurations. The most notable examples, among others, are KÀ=20+ states in 266,268Ds and 268,270Cn having very high K value, relatively low excitation energy, and well-deformed axially symmetric shape. The predicted isomeric states, with hindered spontaneous fission and ± decay, could play a significant role in the future study of superheavy nuclei. © 2014 American Physical Society.
Pietri S, Regan PH, Podolyak Z, Rudolph D, Gorska M, Jungclaus A, Pfuetzner M, Garnsworthy AB, Steer SJ, Caceres L, Werner-Malento E, Hoischen R, Gerl J, Kojouharov I, Schaffner H, Wollersheim HJ, Becker F, Bednarczyk P, Doornenbal P, Geissel H, Grebosz J, Kelic A, Kurz N, Montes F, Prokopowicz W, Saito T, Tashenov S, Heinz A, Kurtukian-Nieto T, Benzoni G, Hellstrom M, Andersson L-L, Atanasova L, Balabanski DL, Bentley MA, Blank B, Blazhev A, Brandau C, Brown JR, Bruce AM, Camera F, Catford WN, Cullen IJ, Dombradi Z, Estevez E, Fahlander C, Gelletly W, Ilie G, Johansson EK, Jolie J, Jones GA, Kmiecik M, Kondev FG, Lalkovski S, Liu Z, Maj A, Myalski S, Shizuma T, Simons AJ, Schwertel S, Walker PM, Wieland O (2007) First results from the stopped beam isomer rising campaign at GSI, ACTA PHYSICA POLONICA B 38 (4) pp. 1255-1264 ACTA PHYSICA POLONICA B, JAGELLONIAN UNIV, INST PHYSICS
Sethi J, Palit R, Saha S, Trivedi T, Bhat GH, Sheikh JA, Datta P, Carroll JJ, Chattopadhyay S, Donthi R, Garg U, Jadhav S, Jain HC, Karamian S, Kumar S, Litz MS, Mehta D, Naidu BS, Naik Z, Sihotra S, Walker PM (2014) Study of the level structure of 108Ag,EPJ Web of Conferences 66
The high spin structure of 108Ag nucleus has been studied using the reaction 11B + 100Mo 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 ³-rays, the level structure of the nucleus is built, with addition of around
Cocolios TE, Al Suradi HH, Billowes J, Budin
evi? I, De Groote RP, De Schepper S, Fedosseev VN, Flanagan KT, Franchoo S, Garcia Ruiz RF, Heylen H, Le Blanc F, Lynch KM, Marsh BA, Mason PJR, Neyens G, Papuga J, Procter TJ, Rajabali MM, Rossel RE, Rothe S, Simpson GS, Smith AJ, Strashnov I, Stroke HH, Verney D, Walker PM, Wendt KDA, Wood RT
(2013) The Collinear Resonance Ionization Spectroscopy (CRIS) experimental setup at CERN-ISOLDE,Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms 317 (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.
Shizuma T, Ishii T, Makii H, Hayakawa T, Shigematsu S, Matsuda M, Ideguchi E, Zheng Y, Liu M, Morikawa T, Walker PM, Oi M (2006) Excited states in neutron-rich W-188 produced by an O-18-induced 2-neutron transfer reaction,EUROPEAN PHYSICAL JOURNAL A 30 (2) pp. 391-396 SPRINGER
Grieser M, Litvinov YA, Raabe R, Blaum K, Blumenfeld Y, Butler PA, Wenander F, Woods PJ, Aliotta M, Andreyev A, Artemyev A, Atanasov D, Aumann T, Balabanski D, Barzakh A, Batist L, Bernardes A-P, Bernhardt D, Billowes J, Bishop S, Borge M, Borzov I, Bosch F, Boston AJ, Brandau C, Catford W, Catherall R, Cederkäll J, Cullen D, Davinson T, Dillmann I, Dimopoulou C, Dracoulis G, Düllmann CE, Egelhof P, Estrade A, Fischer D, Flanagan K, Fraile L, Fraser MA, Freeman SJ, Geissel H, Gerl J, Greenlees P, Grisenti RE, Habs D, von Hahn R, Hagmann S, Hausmann M, He JJ, Heil M, Huyse M, Jenkins D, Jokinen A, Jonson B, Joss DT, Kadi Y, Kalantar-Nayestanaki N, Kay BP, Kiselev O, Kluge H-J, Kowalska M, Kozhuharov C, Kreim S, Kröll T, Kurcewicz J, Labiche M, Lemmon RC, Lestinsky M, Lotay G, Ma XW, Marta M, Meng J, Mücher D, Mukha I, Müller A, Murphy AS, Neyens G, Nilsson T, Nociforo C, Nörtershäuser W, Page RD, Pasini M, Petridis N, Pietralla N, Pfützner M, Podolyák Z, Regan P, Reed MW, Reifarth R, Reiter P, Repnow R, Riisager K, Rubio B, Sanjari MS, Savin DW, Scheidenberger C, Schippers S, Schneider D, Schuch R, Schwalm D, Schweikhard L, Shubina D, Siesling E, Simon H, Simpson J, Smith J, Sonnabend K, Steck M, Stora T, Stöhlker T, Sun B, Surzhykov A, Suzaki F, Tarasov O, Trotsenko S, Tu XL, Van Duppen P, Volpe C, Voulot D, Walker PM, Wildner E, Winckler N, Winters DFA, Wolf A, Xu HS, Yakushev A, Yamaguchi T, Yuan YJ, Zhang YH, Zuber K (2012) Storage ring at HIE-ISOLDE: Technical design report: Technical design report,European Physical Journal: Special Topics 207 (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.
Walker PM (2007) Rare modes of decay from high-spin isomers, PROTON EMITTING NUCLEI AND RELATED TOPICS 961 pp. 273-277 AMER INST PHYSICS
Walker PM, Xu FR (2006) Shapes of neutron-rich AH190 odd-odd nuclei, Physical Review C - Nuclear Physics 74 (6)
The occurrence of oblate and prolate shapes is investigated theoretically for odd-odd neutron-rich nuclei with AH190. 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. © 2006 The American Physical Society.
Walker PM, Xu FR (2006) Prediction and possible observation of an oblate shape isomer in W-190,PHYSICS LETTERS B 635 (5-6) pp. 286-289 ELSEVIER SCIENCE BV
Jiao CF, Shi Y, Liu HL, Xu FR, Walker PM (2015) Shape-coexisting rotation in neutron-deficient Hg and Pb nuclei, Physical Review C - Nuclear Physics 91 (3)
© 2015 American Physical Society.For a shape-soft nucleus, the deformation change with increasing angular momentum of rotation can be significant. Total-Routhian-surface (TRS) calculations include the shape changes, but angular momentum is not conserved (neither is it a good quantum number, nor is it kept unchanged in the whole TRS mesh). In the projected shell model (PSM), the angular momentum appears as a good quantum number, but calculations have usually been performed with fixed deformation. In the present work, by performing angular-momentum projection on the mean-field potential-energy surface (PES), we can obtain an angular-momentum-conserved PES which gives deformation for a rotational state at a given spin. In order to investigate the shape-changing effect, we have chosen neutron-deficient Hg and Pb isotopes in which shape coexistence occurs. We interpret the irregular rotational behavior of the oblate bands at low spin as arising from deformation changes which are induced by collective rotation. At higher spin, the oblate rotational spectrum can also be influenced by the crossing between the K=0 ground-state band and a low-K two-quasineutron band. Calculated g factors for the states of oblate bands are given for future experimental testing, and the intrinsic structures of high-K oblate states are investigated.
Chen F-Q, Sun Y, Sheikh JA, Walker PM, Dracoulis GD, Shimizu YR (2013) Mixing effects on K-forbidden transition rates from the 6 isomers in the N = 104 isotones,Journal of Physics G: Nuclear and Particle Physics 40 (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 ³-vibrational band. Thus the inter-band transitions, and lifetimes, depend on the relative position of the ³-band and the isomeric state in each isotone. © 2013 IOP Publishing Ltd.
Akber A, Reed MW, Walker PM, Litvinov YA, Lane GJ, Kibedi T, Blaum K, Bosch F, Brandau C, Carroll JJ, Cullen DM, Cullen IJ, Deo AY, Detwiler B, Dimopoulou C, Dracoulis GD, Farinon F, Geissel H, Haettner E, Heil M, Kempley RS, Knoebel R, Kozhuharov C, Kurcewicz J, Kuzminchuk N, Litvinov S, Liu Z, Mao R, Nociforo C, Nolden F, Plass WR, Podolyak Z, Prochazka A, Scheidenberger C, Shubina D, Steck M, Stoehlker T, Sun B, Swan TPD, Trees G, Weick H, Winckler N, Winkler M, Woods PJ, Yamaguchi T (2015) Increased isomeric lifetime of hydrogen-like Os-192m,PHYSICAL REVIEW C 91 (3) ARTN 031301 AMER PHYSICAL SOC
Benzoni G, Morales AI, Bracco A, Camera F, Crespi FCL, Corsi AM, Leoni S, Million B, Nicolini R, Wieland O, Valiente-Dobón JJ, Gottardo A, de Angelis G, Napoli DR, Sahin E, Gottardo A, Lunardi S, Bracco A, Camera F, Crespi FCL, Corsi AM, Leoni S, Nicolini R, Gadea A, Algora A, Lunardi S, Bazzacco D, Farnea E, Menegazzo R, Mengoni D, Recchia F, Ur CA, Boutachkov P, Górska M, Pietri S, Weick H, Cortes ML, Domingo-Pardo C, Engert T, Farinon F, Geissel H, Gerl J, Goel N, Gregor E, Habermann T, Hoischen R, Kojouharov I, Kurz N, Naqvi F, Nociforo C, Prochazka A, Prokopowicz W, Schaffner H, Sharma A, Wollersheim H-J, Bruce AM, Denis Bacelar AM, Grebosz J, Podolyak Z, Regan PH, Al-Dahan N, Bowry M, Bunce M, Deo AY, Farrelly GF, Reed MW, Swan TPD, Walker PM, Pfützner M, Alcántara Núñez J, Ayyad Y, Benlliure J, Alkhomashi N, Allegro PRP, Ribas RV, Casarejos E, Doncel M, Dombradi Z, Eppinger K, Klupp S, Steiger K, Hoischen R, Rudolph D, Janik R, Sitar B, Strmen P, Szarka I, Mandal S, Siwal D, Naqvi F, Corsi AM, Al-Dahan N, Walker PM (2012) First measurement of beta decay half-lives in neutron-rich Tl and Bi isotopes,Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 715 (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 ²-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.
Morales AI, Benzoni G, Gottardo A, Valiente-Dobón JJ, Blasi N, Bracco A, Camera F, Crespi FCL, Corsi A, Leoni S, Million B, Nicolini R, Wieland O, Gadea A, Lunardi S, Górska M, Regan PH, Podolyák Z, Pfützner M, Pietri S, Boutachkov P, Weick H, Grebosz J, Bruce AM, Núñez JA, Algora A, Al-Dahan N, Ayyad Y, Alkhomashi N, Allegro PRP, Bazzacco D, Benlliure J, Bowry M, Bunce M, Casarejos E, Cortes ML, Bacelar AMD, Deo AY, De Angelis G, Domingo-Pardo C, Doncel M, Dombradi Z, Engert T, Eppinger K, Farrelly GF, Farinon F, Farnea E, Geissel H, Gerl J, Goel N, Gregor E, Habermann T, Hoischen R, Janik R, Klupp S, Kojouharov I, Kurz N, Mandal S, Menegazzo R, Mengoni D, Napoli DR, Naqvi F, Nociforo C, Prochazka A, Prokopowicz W, Recchia F, Ribas RV, Reed MW, Rudolph D, Sahin E, Schaffner H, Sharma A, Sitar B, Siwal D, Steiger K, Strmen P, Swan TPD, Szarka I, Ur CA, Walker PM, Wollersheim HJ (2014) ² -decay studies of neutron-rich Tl, Pb, and Bi isotopes,Physical Review C - Nuclear Physics 89 (1)
The fragmentation of relativistic uranium projectiles has been exploited at the Gesellschaft für Schwerionenforschung laboratory to investigate the ² decay of neutron-rich nuclei just beyond 208Pb. This paper reports on ²-delayed ³ decays of 211-213Tl, 215Pb, and 215-219Bi de-exciting states in the daughters 211-213Pb, 215Bi, and 215-219Po. The resulting partial level schemes, proposed with the help of systematics and shell-model calculations, are presented. The role of allowed Gamow-Teller and first-forbidden ² transitions in this mass region is discussed. © 2014 American Physical Society.
Lynch KM, Billowes J, Bissell ML, Budincevic I, Cocolios TE, De Groote RP, De Schepper S, Fedosseev VN, Flanagan KT, Franchoo S, Garcia Ruiz RF, Heylen H, Marsh BA, Mason PJR, Neyens G, Procter TJ, Rossel RE, Rothe S, Simpson GS, Smith AJ, Strashnov I, Stroke HH, Walker PM, Wendt KDA, Wood RT (2013) CRIS: A new method in isomeric beam production,EPJ Web of Conferences 63
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.
Shubina D, Cakirli RB, Litvinov YA, Blaum K, Brandau C, Bosch F, Carroll JJ, Casten RF, Cullen DM, Cullen IJ, Deo AY, Detwiler B, Dimopoulou C, Farinon F, Geissel H, Haettner E, Heil M, Kempley RS, Kozhuharov C, Knoebel R, Kurcewicz J, Kuzminchuk N, Litvinov SA, Liu Z, Mao R, Nociforo C, Nolden F, Patyk Z, Plass WR, Prochazka A, Reed MW, Sanjari MS, Scheidenberger C, Steck M, Stoehlker T, Sun B, Swan TPD, Trees G, Walker PM, Weick H, Winckler N, Winkler M, Woods PJ, Yamaguchi T, Zhou C (2013) Schottky mass measurements of heavy neutron-rich nuclides in the element range 70 ,PHYSICAL REVIEW C 88 (2) ARTN 024310 AMER PHYSICAL SOC
Mohammadi S, De Angelis G, Axiotis M, Bazzacco D, Bizzeti PG, Brandolini F, Broda R, Bucurescu D, Farnea E, Gelletly W, Gadea A, Ionescu-Bujor M, Iordachescu A, Kroll T, Longdown S, Lunardi S, Marginean N, Martinez T, Medina N, Podolyak Z, Quintana B, Regan PH, Rubio B, Ur CA, Dobon J-JV, Walker PM, Zhang YH (2006) Yrast states in Os-188,Os-190 nuclei, INTERNATIONAL JOURNAL OF MODERN PHYSICS E-NUCLEAR PHYSICS 15 (8) pp. 1797-1802 WORLD SCIENTIFIC PUBL CO PTE LTD
Sethi J, Palit R, Saha S, Trivedi T, Bhat GH, Sheikh JA, Datta P, Carroll JJ, Chattopadhyay S, Donthi R, Garg U, Jadhav S, Jain HC, Karamian S, Kumar S, Litz MS, Mehta D, Naidu BS, Naik Z, Sihotra S, Walker PM (2013) Structure of nearly degenerate dipole bands in 108Ag,Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 725 (1-3) pp. 85-91
The high spin negative parity states of 108Ag have been investigated with the 11B+100Mo reaction at 39 MeV beam energy using the INGA facility at TIFR, Mumbai. From the ³-³ 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 108Ag 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.
Jones GA, Regan PH, Walker PM, Podolyak Z, Stevenson PD, Carpenter MP, Carroll JJ, Chakrawarthy RS, Chowdhury P, Garnsworthy AB, Janssens RVF, Khoo TL, Kondev FG, Lane GJ, Liu Z, Seweryniak D, Thompson NJ, Zhu S, Williams SJ (2007) Identification of a high-spin isomer in (99)Mo,PHYSICAL REVIEW C 76 (4) ARTN 047303 AMER PHYSICAL SOC
Sumikama T, Yoshinaga K, Watanabe H, Nishimura S, Miyashita Y, Yamaguchi K, Sugimoto K, Chiba J, Li Z, Baba H, Berryman JS, Blasi N, Bracco A, Camera F, Doornenbal P, Go S, Hashimoto T, Hayakawa S, Hinke C, Ideguchi E, Isobe T, Ito Y, Jenkins DG, Kawada Y, Kobayashi N, Kondo Y, Krücken R, Kubono S, Lorusso G, Nakano T, Kurata-Nishimura M, Odahara A, Ong HJ, Ota S, Podolyák Z, Sakurai H, Scheit H, Steiger K, Steppenbeck D, Takano S, Takashima A, Tajiri K, Teranishi T, Wakabayashi Y, Walker PM, Wieland O, Yamaguchi H (2012) Search for spin-orbit-force reduction at 106,108Zr around r-process path, AIP Conference Proceedings 1484 pp. 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 ²-³ 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.
Chakrawarthy RS, Walker PM, Ressler JJ, Zganjar EF, Ball GC, Smith MB, Andreyev AN, Ashley SF, Austin RAE, Bandyopadhyay D, Becker JA, Carroll JJ, Cross DS, Gohlke D, Daoud JJ, Garrett PE, Grinyer GF, Hackman G, Jones GA, Kanungo R, Kulp WD, Litvinov Y, Morton AC, Mills WJ, Pearson CJ, Propri R, Svensson CE, Wheeler R, Williams SJ (2006) K-pi=0(+) 2.29 s isomer in neutron-rich Tm-174,PHYSICAL REVIEW C 73 (2) ARTN 024306 AMERICAN PHYSICAL SOC
Nishimura S, Li Z, Watanabe H, Yoshinaga K, Sumikama T, Tachibana T, Yamaguchi K, Kurata-Nishimura M, Lorusso G, Miyashita Y, Odahara A, Baba H, Berryman JS, Blasi N, Bracco A, Camera F, Chiba J, Doornenbal P, Go S, Hashimoto T, Hayakawa S, Hinke C, Ideguchi E, Isobe T, Ito Y, Jenkins DG, Kawada Y, Kobayashi N, Kondo Y, Krücken R, Kubono S, Nakano T, Ong HJ, Ota S, Podolyák Z, Sakurai H, Scheit H, Steiger K, Steppenbeck D, Sugimoto K, Takano S, Takashima A, Tajiri K, Teranishi T, Wakabayashi Y, Walker PM, Wieland O, Yamaguchi H (2011) ²-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,Physical Review Letters 106 (5) 052502 pp. --- American Physical Society
The ²-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 AH110 region. A revised model based on the second generation gross theory of ² 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.
Al-Dahan N, Podolyák Z, Regan PH, Steer SJ, Bacelar AMD, Alkhomashi N, Górska M, Gerl J, Wollersheim HJ, Pietri SB, Grawe H, Deo AY, Farrelly G, Boutachkov P, Domingo-Pardo C, Algora A, Benlliure J, Bracco A, Bruce AM, Calore E, Casarejos E, Cullen IJ, Detistov P, Dombrádi Z, Doncel M, Farinon F, Geissel H, Gelletly W, Goel N, Grebosz J, Hoischen R, Kojouharov I, Kurz N, Lalkovski S, Leoni S, Molina F, Montanari D, Morales AI, Musumarra A, Napoli DR, Nicolini R, Nociforo C, Prochazka A, Prokopowicz W, Rubio B, Rudolph D, Schaffner H, Strmen P, Szarka I, Swan T, Valiente-Dobon JJ, Verma S, Walker PM, Weick H (2009) Isomeric states in 208Hg and 209Tl populated in fragmentation of 238U, Acta Physica Polonica B 40 (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.
Walker PM (2006) Isomer beams,INTERNATIONAL JOURNAL OF MODERN PHYSICS E-NUCLEAR PHYSICS 15 (7) pp. 1637-1644 WORLD SCIENTIFIC PUBL CO PTE LTD
Morales AI, Benzoni G, Al-Dahan N, Vergani S, Podolyak Z, Regan PH, Swan TPD, Valiente-Dobon JJ, Bracco A, Boutachkov P, Crespi FCL, Gerl J, Gorska M, Pietri S, Walker PM, Wollersheim H-J (2015) First measurement of the beta-decay half-life of Au-206,EPL 111 (5) ARTN 52001 EPL ASSOCIATION, EUROPEAN PHYSICAL SOCIETY
Garrett PE, Svensson CE, Ball GC, Hackman G, Zganjar EF, Andreoiu C, Andreyev A, Ashley SF, Austin RAE, Bandyopadhyay D, Becker JA, Chan S, Coombes H, Churchman R, Chakrawarthy RS, Finlay P, Grinyer GF, Hyland B, Illes E, Jones GA, Kulp WD, Leslie JR, Mattoon C, Morton AC, Pearson CJ, Phillips AA, Regan PH, Ressler JJ, Sarazin F, Schumaker MA, Schwarzenberg J, Smith MB, Valiente-dobón JJ, Walker PM, Williams SJ, Waddington JC, Watters LM, Wong J, Wood JL (2006) Gamma-ray spectroscopy at TRIUMF-ISAC,AIP Conference Proceedings 819 pp. 249-253
The 8À 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 ²-particle tagging, 5 Si(Li) detectors for conversion electrons, and 10 BaF2 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.
Sethi J, Palit R, Carroll JJ, Karamian S, Saha S, Biswas S, Naik Z, Trivedi T, Litz MS, Datta P, Chattopadhyay S, Donthi R, Garg U, Jadhav S, Jain HC, Kumar S, Mehta D, Naidu BS, Bhat GH, Sheikh JA, Sihotra S, Walker PM (2015) Spectroscopy of the low-lying states near the high spin isomer in <sup>108</sup>Ag, Acta Physica Polonica B 46 (3) pp. 703-707
A comprehensive study of the low-lying states of 108Ag, near the isomeric state at Ei = 110 keV with JÀ = 6+ and T1/2 = 438 y, has been presented. Spectroscopy of these states has been carried out using the reaction 100Mo(11B, 3n³)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.
Cieplicka N, Fornal B, Maier KH, Szpak B, Broda R, Krolas W, Pawlat T, Wrzesinski J, Janssens RVF, Carpenter MP, Chiara CJ, Hoffman CR, Kondev FG, Lauritsen T, Zhu S, Podolyak Z, Bowry M, Bunce M, Gelletly W, Kempley R, Reed M, Regan P, Walker P, Wilson E, Deo AY, Dracoulis G, Lane G, Rodriguez-Triguero C (2014) ANGULAR DISTRIBUTIONS OF gamma RAYS FROM Bi-210 PRODUCED IN Pb-208+Pb-208 DEEP-INELASTIC REACTIONS,ACTA PHYSICA POLONICA B 45 (2) pp. 205-210 WYDAWNICTWO UNIWERSYTETU JAGIELLONSKIEGO
Lalkovski S, Bruce AM, Jungclaus A, Gorska M, Pfuetzner M, Caceres L, Naqvi F, Pietri S, Podolyak Z, Simpson GS, Andgren K, Bednarczyk P, Beck T, Benlliure J, Benzoni G, Casarejos E, Cederwall B, Crespi FCL, Cuenca-Garcia JJ, Cullen IJ, Bacelar AMD, Detistov P, Doornenbal P, Farrelly GF, Garnsworthy AB, Geissel H, Gelletly W, Gerl J, Grebosz J, Hadinia B, Hellstrom M, Hinke C, Hoischen R, Ilie G, Jaworski G, Jolie J, Khaplanov A, Kisyov S, Kmiecik M, Kojouharov I, Kumar R, Kurz N, Maj A, Mandal S, Modamio V, Montes F, Myalski S, Palacz M, Prokopowicz W, Reiter P, Regan PH, Rudolph D, Schaffner H, Sohler D, Steer SJ, Tashenov S, Walker J, Walker PM, Weick H, Werner-Malento E, Wieland O, Wollersheim HJ, Zhekova M (2013) Core-coupled states and split proton-neutron quasiparticle multiplets in Ag122-126,PHYSICAL REVIEW C 87 (3) ARTN 034308 AMER PHYSICAL SOC
Al-Dahan N, Podolyak Z, Regan PH, Gorska M, Grawe H, Maier KH, Gerl J, Pietri SB, Wollersheim HJ, Alkhomashi N, Deo AY, Bacelar AMD, Farrelly G, Steer SJ, Bruce AM, Boutachkov P, Domingo-Pardo C, Algora A, Benlliure J, Bracco A, Calore E, Casarejos E, Cullen IJ, Detistov P, Dombradi Z, Doncel M, Farinon F, Gelletly W, Geissel H, Goel N, Grebosz J, Hoischen R, Kojouharov I, Kurz N, Lalkovski S, Leoni S, Molina F, Montanari D, Morales AI, Musumarra A, Napoli DR, Nicolini R, Nociforo C, Prochazka A, Prokopowicz W, Rubio B, Rudolph D, Schaffner H, Strmen P, Szarka I, Swan T, Thomas JS, Valiente-Dobon JJ, Verma S, Walker PM, Weick H (2009) Nuclear structure "southeast" of Pb-208: Isomeric states in Hg-208 and Tl-209,PHYSICAL REVIEW C 80 (6) ARTN 061302 AMER PHYSICAL SOC
Myalski S, Kmiecik M, Maj A, Regan PH, Garnsworthy AB, Pietri S, Rudolph D, Podolyak Z, Steer SJ, Becker F, Bednarczyk P, Gerl J, Gorska M, Grawe H, Kojouharov I, Schaffner H, Wollersheim HJ, Prokopowicz W, Grebosz J, Benzoni G, Blank B, Brandau C, Bruce AM, Caceres L, Camera F, Catford WN, Cullen IJ, Dombradi Z, Doornenbal P, Estevez E, Geissel H, Gelletly W, Heinz A, Hoischen R, Ilie G, Jones GA, Jungclaus A, Kelic A, Kondev FG, Kurtukian-Nieto T, Kurz N, Lalkovski S, Liu Z, Montes F, Pfuetzner M, Saito T, Shizuma T, Simons AJ, Schwertel S, Tachenov S, Walker PM, Werner-Malento E, Wieland O (2007) Isomeric ratio for the I-pi=8(+) yrast state in Pd-96 produced in the relativistic fragmentation of Ag-107, ACTA PHYSICA POLONICA B 38 (4) pp. 1277-1282 ACTA PHYSICA POLONICA B, JAGELLONIAN UNIV, INST PHYSICS
Riley M., Djongolov MK, Evans AO, Hartley DJ, Janssens RVF, Paul ES, Pipidis A, Simpson J, Aguilar AA, Appelbe DE, Bingham CR, Campbell DB, Carpenter MP, Chowdhury P, Choy PTW, Clark RM, Cromaz M, Cullen DM, Danchev M, Dracoulis GD, Fallon P, Gorgen A, Hagemann GB, Joss DT, Goon J, Kaye RA, Khoo TL, Kondev FG, Laird RW, Lagergren K, Lauritsen T, Macchiavelli AO, McClain B, Moore EF, Mukherjee G, Ngijoi-Yogo E, Nolan PJ, Park HI, Riedinger LL, Sletten G, Tandel SK, Walker PM, Ward D, Ragnarsson I, Saric F, Zhang JY (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,PHYSICA SCRIPTA T125 pp. 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.
Sun B, Bosch F, Boutin D, Brandau C, Chen L, Dimopoulou C, Fabian B, Geissel H, Knoebel R, Kozhuharov C, Kurcewicz J, Litvinov SA, Litvinov YA, Meng J, Muenzenberg G, Nociforo C, Nolden F, Plass WR, Scheidenberger C, Steck M, Walker PM, Weick H, Winckler N, Winkler M (2010) Precise measurement of nuclear isomers in the storage ring at GSI, NUCLEAR PHYSICS A 834 (1-4) pp. 476C-478C ELSEVIER SCIENCE BV
Shi Y, Walker PM, Xu FR (2012) High-K isomers in neutron-rich zirconium isotopes,PHYSICAL REVIEW C 85 027307 American Physical Society
Swan TPD, Walker PM, Podolyak Z, Reed MW, Dracoulis GD, Lane GJ, Kibedi T, Smith ML (2012) Discovery of isomers in dysprosium, holmium, and erbium isotopes with N=94 to 97,PHYSICAL REVIEW C 85 024313 American Physical Society
Jones GA, Williams SJ, Walker PM, Podolyak Z, Zhu S, Carpenter MP, Carroll JJ, Chakrawarthy RS, Chowdhury P, Cullen IJ, Dracoulis GD, Garnsworthy AB, Hackman G, Janssens RVF, Khoo TL, Kondev FG, Lane GJ, Liu Z, Seweryniak D, Thompson NJ (2008) High-spin, multiparticle isomers in (121,123)Sb,PHYSICAL REVIEW C 77 (3) ARTN 034311 AMER PHYSICAL SOC
Patel Z, Podolyak Z, Walker PM, Regan PH, Söderström P-A, Watanabe H, Ideguchi E, Simpson GS, Nishimura S, Browne F, Doornenbal P, Lorusso P, Rice S, Sinclair L, Sumikama T, Wu J, Xu ZY, Aoi N, Baba H, Bello Garrote FL, Benzoni G, Daido R, Dombrádi Z, Fang Y, Fukuda N, Gay G, Go S, Gottardo A, Inabe N, Isobe T, Kameda K, Kobayashi K, Kobayashi M, Komatsubara T, Kojouharov I, Kubo T, Kurz N, Kuti I, Li Z, Liu HL, Matsushita M, Michimasa S, Moon CB, Nishibata H, Nishizuka I, Odahara A, Sahin E, Sakurai H, Schaffner H, Suzuki H, Takeda H, Taprogge J, Vajta Z, Xu FR, Yagi A, Yokoyama R (2016) ²-decay spectroscopy of neutron-rich 160,161,162Sm isotopes,EPJ Web of Conferences 123 (2016) EDP Sciences
Neutron-rich 160,161,162Sm isotopes have been populated at the RIBF, RIKEN via ² first time. ²-coincident ³ rays were observed in all three isotopes including ³ rays from the isomeric decay of 160Sm and 162Sm. The isomers in 160Sm and 162Sm have previously been observed but have been populated via ² 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
Denis Bacelar AM, Bruce AM, Lalkovski S, Podolyák Z, Al-Dahan N, Alkhomashi N, Cullen IJ, Deo AY, Farrelly GF, Gelletly W, Regan PH, Steer SJ, Swan TPD, Walker PM, Górska M, Pietri S, Ricciardi MV, Boutachkov P, Domingo-Pardo C, Farinon F, Geissel H, Gerl J, Goel N, Gr)bosz J, Hoischen R, Kojouharov I, Kurz N, Nociforo C, Prochazka A, Prokopowicz W, Schmidt K-H, Schaffner H, Weick H, Wollersheim HJ, Detistov P, Algora A, Molina F, Rubio B, Dombradi Z, Benlliure J, Morales AI, Verma S, Bracco A, Leoni S, Montanari D, Nicolini R, Calore E, Napoli DR, Valiente-Dobón JJ, Casarejos E, Doncel M, Rudolph D, Musumarra A, Steiger K, Strmen P, Szarka I (2013) The population of metastable states as a probe of relativistic-energy fragmentation reactions,Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 723 (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 ¼s and spin values up to 55/2? 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.
Myalski S, Maj A, Podolyák Z, Kmiecik M, Bednarczyk P, Grebosz J, Regan PH, Garnsworthy AB, Pietri S, Rudolph D, Steer SJ, Becker F, Gerl J, Górska M, Grawe H, Kojouharov I, Schaffner H, Wollersheim HJ, Prokopowicz W, Benzoni G, Blank B, Brandau C, Bruce AM, Cáceres L, Camera F, Catford WN, Cullen IJ, Dombradi Z, Doornenbal P, Estevez E, Geissel H, Gelletly W, Heinz A, Hoischen R, Ilie G, Jones GA, Jungclaus A, Kelic A, Kondev FG, Kurtukian-Nieto T, Kurz N, Lalkovski S, Liu Z, Montes F, Pfützner M, Saito T, Shizuma T, Simons AJ, Schwertel S, Tachenov S, Walker PM, Werner-Malento E, Wieland O (2012) Study of isomer production rates for A = 142-152 and Z = 62-67 in fragmentation of a relativistic 208Pb beam, Acta Physica Polonica B 43 (2) pp. 253-259
We have investigated nuclear fragmentation reactions of a relativistic 208Pb beam.Ten isomeric states for nuclei with A = 142-152 and Z = 62-67 were observed. Measured isomeric ratios were compared, together with values from other experiments, with prediction of theoretical models. The discrepancies between the experimental and theoretical values were discussed in terms of transitions by-passing the isomer that are not included in the models.
Zganjar EF, Achtzehn T, Albers D, Andreoiu C, Andreyev AN, Austin RAE, Ball GC, Behr JA, Biosvert GC, Bricault P, Bishop S, Chakrawarthy RS, Churchman R, Cross D, Cunningham E, D'Auria JM, Dombsky M, Finlay P, Garrett PE, Grinyer GF, Hackman G, Hanemaayer V, Hardy JC, Hodgson DF, Hyland B, Iacob V, Klages P, Koopmans KA, Kulp WD, Lassen J, Lavoie JP, Leslie JR, Linder T, Macdonald JA, Mak H-B, Melconian D, Morton AC, Ormand WE, Osborne CJ, Pearson CJ, Pearson MR, Phillips AA, Piechaczek A, Ressler J, Sarazin F, Savard G, Schumaker MA, Scraggs HC, Svensson CE, Valiente-Dobon JJ, Towner IS, Waddington JC, Walker PM, Wendt K, Wood JL (2007) Superallowed beta decay studies at TRIUMF - Nuclear structure and fundamental symmetries, ACTA PHYSICA POLONICA B 38 (4) pp. 1179-1194 ACTA PHYSICA POLONICA B, JAGELLONIAN UNIV, INST PHYSICS
Sun B, Knoebel R, Litvinov YA, Geissel H, Meng J, Beckert K, Bosch F, Boutin D, Brandau C, Chen L, Cullen IJ, Dimopoulou C, Fabian B, Hausmann M, Kozhuharov C, Litvinov SA, Mazzocco M, Montes F, Muenzenberg G, Musumarra A, Nakajima S, Nociforo C, Nolden F, Ohtsubo T, Ozawa A, Patyk Z, Plass WR, Scheidenberger C, Steck M, Suzuki T, Walker PM, Weick H, Winckler N, Winkler M, Yamaguchi T (2008) Nuclear structure studies of short-lived neutron-rich nuclei with the novel large-scale isochronous mass spectrometry at the FRS-ESR facility, NUCLEAR PHYSICS A 812 pp. 1-12 ELSEVIER SCIENCE BV
Walker PM (2008) Nuclear physics - A neutrino's wobble?, NATURE 453 (7197) pp. 864-865 NATURE PUBLISHING GROUP
Walker PM (2010) High-spin isomers: structure and applications,NUCLEAR PHYSICS A 834 (1-4) pp. 22C-27C ELSEVIER SCIENCE BV
Walker P (2011) THE ATOMIC NUCLEUS, NEW SCIENTIST 211 (2832) pp. I-VIII
Walker PM, Walker PM, Xu FR, Liu HL, Xu FR, Sun Y, Liu HL, Sun Y, Liu HL (2012) On the possibility of enhanced fission stability for broken-pair excitations,Journal of Physics G: Nuclear and Particle Physics 39 (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.
Stone NJ, Stone JR, Walker PM, Bingham CR (2013) Quasi-particle and collective magnetism: Rotation, pairing and blocking in high-K isomers,Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 726 (4-5) pp. 675-679
For the first time, a wide range of collective magnetic g-factors gR, 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, Np-Nn. 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 (Np, Nn), 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 gR 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 gR 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.
Walker PM, Lalkovski S, Stevenson PD (2010) Configuration dependence of K-forbidden transition rates from three-quasiparticle isomers,PHYSICAL REVIEW C 81 (4) ARTN 041304 AMER PHYSICAL SOC
Walker P (2011) NUCLEAR ASTROPHYSICS Star bursts pinned down, NAT PHYS 7 (4) pp. 281-282 NATURE PUBLISHING GROUP
Swan TPD, Walker PM, Podolyák Z, Reed MW, Dracoulis GD, Lane GJ, Kibédi T, Smith ML (2012) Hindered decays from a non-yrast four-quasiparticle isomer in 164Er,Physical Review C - Nuclear Physics 86 (4)
The half-life of a KÀ=12 + isomer in 164Er has been measured to be 68(2) ns, and new decay pathways have been identified. These include highly K-forbidden ³-ray transitions directly to the ground-state rotational band, with reduced hindrance values that can be compared with those found for heavier nuclides. The new data support the interpretation that the level density is a key variable in determining K-forbidden transition rates. © 2012 American Physical Society.
Litvinov YA, Blaum K, Winckler N, Ma X, Walker PM (2010) Mass and lifetime measurements of stored exotic nuclei,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).
Wilson E, Podolyák Z, Fornal B, Janssens RVF, Bowry M, Bunce M, Carpenter MP, Chiara CJ, Cieplicka N, Deo AY, Dracoulis GD, Grawe H, Hoffman CR, Kempley RS, Kondev FG, Lane GJ, Lauritsen T, Reed MW, Regan PH, Rodríguez Triguero C, Szpak B, Walker PM, Zhu S (2014) Study of 207Tl126 produced in deep-inelastic reactions,EPJ Web of Conferences 66
Deep-inelastic collisions of a 208Pb beam on a 208Pb target were performed using the ATLAS accelerator at Argonne National Laboratory. The Gammasphere detector array was used for the detection of prompt and delayed gamma-rays of the reaction products.207Tl is one proton away from the 208Pb doubly-magic nucleus. Its low-energy level structure is dominated by the single proton-hole states Às1/2-1, Àd3/2-1 and Àh11/2-1. The 11/2- state is isomeric with T1/2 = 1.33(11) s. The reaction partner of 207Tl is 209Bi, which has arelatively well established level scheme compared to 207Tl. Cross-coincidences between these two nuclei were used to confirm or establish levels above the 11/2- isomeric state in 207Tl. These states are obtained via breaking of the neutron core. Angular correlation analysis was performed on known transitions in 208Pb, proving the applicability of this method for multipolarity assignment. © Owned by the authors, published by EDP Sciences, 2014.
Shi Y, Xu FR, Liu HL, Walker PM (2010) Multi-quasiparticle excitation: Extending shape coexistence in A similar to 190 neutron-deficient nuclei,PHYSICAL REVIEW C 82 (4) ARTN 044314 AMER PHYSICAL SOC
Steer SJ, PodolyÁk ZS, Pietri S, GÓrska M, Farrelly GF, Regan PH, Rudolph D, Garnsworthy AB, Hoischen R, Gerl J, Wollersheim HJ, Grawe H, Maier KH, Becker F, Bednarczyk P, CÁceres L, Doornenbal P, Geissel H, Grbosz J, Kelic A, Kojouharov I, Kurz N, Montes F, Prokopowicz W, Saito T, Schaffner H, Tashenov S, Heinz A, Kurtukian-Nieto T, Benzoni G, PfÜtzner M, Jungclaus A, Balabanski DL, Brandau C, Brown A, Bruce AM, Catford WN, Cullen IJ, DombrÁdi Z, Estevez ME, Gelletly W, Ilie G, Jolie J, Jones GA, Kmiecik M, Kondev FG, KrÜcken R, Lalkovski S, Liu Z, Maj A, Myalski S, Schwertel S, Shizuma T, Walker PM, Werner-Malento E, Wieland O (2009) Isomeric decay studies in neutron-rich N H 126 nuclei,International Journal of Modern Physics E 18 (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.
Bacelar AMD, Bruce AM, Podolyak Z, Lalkovski S, Pietri S, Al-Dahan N, Gorska M, Algora A, Alkhomashi N, Benlliure J, Boutachkov P, Bracco A, Calore E, Casarejos E, Cullen IJ, Deo AY, Detistov P, Dombradi Z, Domingo-Pardo C, Doncel M, Farinon F, Farrelly GF, Geissel H, Gelletly W, Gerl J, Goel N, Grebosz J, Hoischen R, Kojouharov I, Kurz N, Leoni S, Molina F, Morales AI, Montanari D, Musumarra A, Nicolini R, Napoli DR, Nociforo C, Prochazka A, Prokopowicz W, Regan PH, Rubio B, Rudolph D, Verma S, Steer SJ, Strmen P, Swan TPD, Szarka I, Valiente-Dobon JJ, Walker PM, Weick H, Wollersheim HJ (2009) ANGULAR MOMENTUM POPULATION IN FRAGMENTATION REACTIONS,ACTA PHYSICA POLONICA B 40 (3) pp. 889-892 POLISH ACAD SCIENCES INST PHYSICS
Soederstroem P-A, Regan PH, Walker PM, Watanabe H, Doornenbal P, Korkulu Z, Lee P, Liu HL, Liu JJ, Lorusso G, Nishimura S, Sumikama T, Phong VH, Wu J, Xu FR, Yagi A, Zhang GX, Alharbi T, Baba H, Browne F, Bruce AM, Carroll R, Chae KY, Dombradi Z, Estrade A, Fukuda N, Griffin C, Ideguchi E, Inabe N, Isobe T, Kanaoka H, Kojouharov I, Kondev FG, Kubo T, Kubono S, Kurz N, Kuti I, Lalkovski S, Lane GJ, Lee CS, Lee EJ, Lotay G, Moon C-B, Nishizuka I, Nita CR, Odahara A, Patel Z, Podolyak Z, Roberts OJ, Sakurai H, Schaffner H, Shand CM, Suzuki H, Takeda H, Terashima S, Vajta Z, Valiente-Dobon JJ, Xu ZY, Yoshida S (2015) Heavy Rotation - Evolution of quadrupole collectivity centred at the neutron-rich doubly mid-shell nucleus Dy-170, NUCLEAR STRUCTURE AND DYNAMICS '15 1681 AMER INST PHYSICS
Watanabe H, Sumikama T, Nishimura S, Yoshinaga K, Li Z, Miyashita Y, Yamaguchi K, Baba H, Berryman JS, Blasi N, Bracco A, Camera F, Chiba J, Doornenbal P, Go S, Hashimoto T, Hayakawa S, Hinke C, Ideguchi E, Isobe T, Ito Y, Jenkins DG, Kawada Y, Kobayashi N, Kondo Y, Kruecken R, Kubono S, Lorusso G, Nakano T, Kurata-Nishimura M, Odahara A, Ong HJ, Ota S, Podolyak Z, Sakurai H, Scheit H, Shi Y, Steiger K, Steppenbeck D, Sugimoto K, Tajiri K, Takano S, Takashima A, Teranishi T, Wakabayashi Y, Walker PM, Wieland O, Xu FR, Yamaguchi H (2011) Low-lying level structure of the neutron-rich nucleus Nb-109: A possible oblate-shape isomer,PHYSICS LETTERS B 696 (3) pp. 186-190 ELSEVIER SCIENCE BV
Sun Y, Walker PM, Xu F-R, Liu Y-X (2008) Rotation-driven prolate-to-oblate shape phase transition in W-190: A projected shell model study,PHYSICS LETTERS B 659 (1-2) pp. 165-169 ELSEVIER SCIENCE BV
Walker PM (2007) Angular momentum orientation at bandcrossings in rotating nuclei,JOURNAL OF PHYSICS G-NUCLEAR AND PARTICLE PHYSICS 34 (1) pp. 123-127 IOP PUBLISHING LTD
Gottardo A, Valiente-Dobón JJ, De Angelis G, Napoli DR, Sahin E, Gottardo A, Lunardi S, Lenzi SM, Maglione E, Benzoni G, Nicolini R, Bracco A, Camera F, Crespi FCL, Corsi A, Leoni S, Million B, Morales AI, Wieland O, Nicolini R, Bracco A, Camera F, Corsi A, Leoni S, Gadea A, Algora A, Lunardi S, Bazzacco D, Farnea E, Lenzi SM, Menegazzo R, Mengoni D, Recchia F, Ur CA, Maglione E, Boutachkov P, Górska M, Pietri S, Weick H, Cortes ML, Domingo-Pardo C, Engert T, Farinon F, Geissel H, Gerl J, Goel N, Gregor E, Habermann T, Hoischen R, Kojouharov I, Kurz N, Naqvi F, Nociforo C, Prochazka A, Prokopowicz W, Schaffner H, Sharma A, Wollersheim H-J, Bruce AM, Bunce M, Denis Bacelar AM, Grebosz J, Podolyák Z, Regan PH, Al-Dahan N, Bowry M, Deo AY, Farrelly GF, Reed MW, Swan TPD, Walker PM, Pfützner M, Alcántara Núñez J, Ayyad Y, Benlliure J, Alkhomashi N, Allegro PRP, Ribas RV, Casarejos E, Doncel M, Dombradi Z, Eppinger K, Klupp S, Steiger K, Hoischen R, Rudolph D, Janik R, Sitar B, Strmen P, Szarka I, Mandal S, Siwal D, Naqvi F, Walker PM, Nowacki F, Zuker AP (2012) New isomers in the full seniority scheme of neutron-rich lead isotopes: The role of effective three-body forces,Physical Review Letters 109 (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.
Sun B, Knoebel R, Litvinov YA, Nakajima S, Geissel H, Meng J, Beckert K, Bosch F, Boutin D, Brandau C, Chen L, Cullen IJ, Dimopoulou C, Fabian B, Hausmann M, Klepper O, Kozhuharov C, Kurcewicz J, Litvinov SA, Mazzocco M, Montes F, Muenzenberg G, Musumarra A, Nociforo C, Nolden F, Ohtsubo T, Ozawa A, Patyk Z, Plass WR, Scheidenberger C, Steck M, Suzuki T, Walker PM, Weick H, Winckler N, Winkler M, Yamaguchi T (2009) LARGE-SCALE MASS MEASUREMENTS OF SHORT-LIVED NUCLIDES WITH THE ISOCHRONOUS MASS SPECTROMETRY AT GSI, INTERNATIONAL JOURNAL OF MODERN PHYSICS E-NUCLEAR PHYSICS 18 (2) pp. 346-351 WORLD SCIENTIFIC PUBL CO PTE LTD
Gottardo A, Valiente-Dobón JJ, Benzoni G, Lunardi S, Gadea A, Algora A, Al-Dahan N, De Angelis G, Ayyad Y, Bazzacco D, Benlliure J, Boutachkov P, Bowry M, Bracco A, Bruce AM, Bunce M, Camera F, Casarejos E, Cortes ML, Crespi FCL, Corsi A, Denis Bacelar AM, Deo AY, Domingo-Pardo C, Doncel M, Engert T, Eppinger K, Farrelly GF, Farinon F, Farnea E, Geissel H, Gerl J, Goel N, Górska M, Grebosz J, Gregor E, Habermann T, Hoischen R, Janik R, John PR, Klupp S, Kojouharov I, Kurz N, Lenzi SM, Leoni S, Mandal S, Menegazzo R, Mengoni D, Million B, Modamio V, Morales AI, Napoli DR, Naqvi F, Nicolini R, Nociforo C, Pfützner M, Pietri S, Podolyák Z, Prochazka A, Prokopowicz W, Recchia F, Regan PH, Reed MW, Rudolph D, Sahin E, Schaffner H, Sharma A, Sitar B, Siwal D, Steiger K, Strmen P, Swan TPD, Szarka I, Ur CA, Walker PM, Weick H, Wieland O, Wollersheim HJ (2014) Isomeric decay spectroscopy of the Bi 217 isotope,Physical Review C - Nuclear Physics 90 (3)
© 2014 American Physical Society.The structure of the neutron-rich bismuth isotope Bi217 has been studied for the first time. The fragmentation of a primary U238 beam at the FRS-RISING setup at GSI was exploited to perform ³-decay spectroscopy, since ¼s isomeric states were expected in this nucleus. Gamma rays following the decay of a t1/2=3 ¼s isomer were observed, allowing one to establish the low-lying structure of Bi217. The level energies and the reduced electric quadrupole transition probability B(E2) from the isomeric state are compared to large-scale shell-model calculations.
Regan PH, Alkhomashi N, Al-Dahan N, PodolyÁk Z, Pietri SB, Steer SJ, Garnsworthy AB, Suckling EB, Stevenson PD, Farrelly G, Cullen IJ, Gelletly W, Walker PM, Benlliure J, Morales AI, Casajeros E, Estevez ME, Gerl J, GÓrska M, Wollersheim HJ, Boutachkov P, Tashenov S, Kojouharov I, Schaffner H, Kurz N, Kumar R, Rubio B, Algora A, Molina F, Grebosz J, Benzoni G, MÜcher D, Bruce AM, Bacelar AMD, Lalkovski S, Fujita Y, Tamii A, Hoischen R, Liu Z, Woods PJ, Mihai C, Valiente-DobÓn JJ (2008) First results with the rising active stopper, International Journal of Modern Physics E 17 (SUPPL. 1) pp. 8-20
Walker PM, Wood RJ, Dracoulis GD, Kibedi T, Bark RA, Bruce AM, Byrne AP, Davidson PM, El-Masri HM, Lane GJ, Moon C, Orce JN, Estevez FMP, Wheldon C, Wilson AN (2009) Fast decay of a three-quasiparticle isomer in Tm-171,PHYSICAL REVIEW C 79 (4) ARTN 044321 AMER PHYSICAL SOC
Lestinsky M, Andrianov V, Aurand B, Bagnoud V, Bernhardt D, Beyer H, Bishop S, Blaum K, Bleile A, Borovik A, Bosch F, Bostock CJ, Brandau C, Braeuning-Demian A, Bray I, Davinson T, Ebinger B, Echler A, Egelhof P, Ehresmann A, Engstroem M, Enss C, Ferreira N, Fischer D, Fleischmann A, Foerster E, Fritzsche S, Geithner R, Geyer S, Glorius J, Goebel K, Gorda O, Goullon J, Grabitz P, Grisenti R, Gumberidze A, Hagmann S, Heil M, Heinz A, Herfurth F, Hess R, Hillenbrand P-M, Hubele R, Indelicato P, Kaellberg A, Kester O, Kiselev O, Knie A, Kozhuharov C, Kraft-Bermuth S, Kuehl T, Lane G, Litvinov YA, Liesen D, Ma XW, Maertin R, Moshammer R, Mueller A, Namba S, Neumeyer P, Nilsson T, Noertershaeuser W, Paulus G, Petridis N, Reed M, Reifarth R, Reiss P, Rothhardt J, Sanchez R, Sanjari MS, Schippers S, Schmidt HT, Schneider D, Scholz P, Schuch R, Schulz M, Shabaev V, Simonsson A, Sjoholm J, Skeppstedt O, Sonnabend K, Spillmann U, Stiebing K, Steck M, Stohlker T, Surzhykov A, Torilov S, Trabert E, Trassinelli M, Trotsenko S, Tu XL, Uschmann I, Walker PM, Weber G, Winters DFA, Woods PJ, Zhao HY, Zhang YH (2016) Physics book: CRYRING@ESR,EUROPEAN PHYSICAL JOURNAL-SPECIAL TOPICS 225 (5) pp. 797-882 SPRINGER HEIDELBERG
Watanabe H, Yamaguchi K, Odahara A, Sumikama T, Nishimura S, Yoshinaga K, Li Z, Miyashita Y, Sato K, Prochniak L, Baba H, Berryman JS, Blasi N, Bracco A, Camera F, Chiba J, Doornenbal P, Go S, Hashimoto T, Hayakawa S, Hinke C, Hinohara N, Ideguchi E, Isobe T, Ito Y, Jenkins DG, Kawada Y, Kobayashi N, Kondo Y, Kruecken R, Kubono S, Lorusso G, Nakano T, Nakatsukasa T, Kurata-Nishimura M, Ong HJ, Ota S, Podolyak Z, Sakurai H, Scheit H, Steiger K, Steppenbeck D, Sugimoto K, Tajiri K, Takano S, Takashima A, Teranishi T, Wakabayashi Y, Walker PM, Wieland O, Yamaguchi H (2011) Development of axial asymmetry in the neutron-rich nucleus Mo-110,PHYSICS LETTERS B 704 (4) pp. 270-275
Caceres LS, Gorska M, Jungclaus A, Regan PH, Garnsworthy AB, Pietri S, Podolyak Z, Rudolph D, Steer SJ, Grawe H, Balabanski DL, Becker F, Bednarczyk P, Benzoni G, Blank B, Brandau C, Bruce AM, Camera F, Catford WN, Cullen IJ, Dombradi Z, Doornenbalal P, Estevez E, Geissel H, Gelletly W, Gerl J, Grebosz J, Heinz A, Hoischen R, Ilie G, Jolie J, Jones GA, Kmiecik M, Kojouharov I, Kondev FG, Kurtukian-Nieto T, Kurz N, Lalkowski S, Liu L, Maj A, Myalsk S, Montes F, Pfuetzner M, Prokopowicz W, Saito T, Schatfner H, Schwertel S, Shizuma T, Simons AJ, Tashenov S, Walker PM, Werner-Malento E, Wielandh O, Wollersheim HJ (2007) Identification of excited states in the N = Z nucleus Nb-82, ACTA PHYSICA POLONICA B 38 (4) pp. 1271-1275 ACTA PHYSICA POLONICA B, JAGELLONIAN UNIV, INST PHYSICS
Steer SJ, Podolyak Z, Pietri S, Gorska M, Regan PH, Rudolph D, Werner-Malento E, Garnsworthy AB, Hoischen R, Gerl J, Wollersheim HJ, Maier KH, Grawe H, Becker F, Bednarczyk P, Caceres L, Doornenbal P, Geissel H, Greabosz J, Kelic A, Kojouharov I, Kurz N, Montes F, Prokopowicz W, Saito T, Schaffner H, Tashenov S, Heinz A, Pfuetzner M, Kurtukian-Nieto T, Benzoni G, Jungclaus A, Balabanski DL, Brandau C, Brown BA, Bruce AM, Catford WN, Cullen IJ, Dombradi Z, Estevez ME, Gelletly W, Ilie G, Jolie J, Jones GA, Kmiecik M, Kondev FG, Kruecken R, Lalkovski S, Liu Z, Maj A, Myalski S, Schwertel S, Shizuma T, Walker PM, Wieland O (2008) Single-particle behavior at N=126: Isomeric decays in neutron-rich Pt-204,PHYSICAL REVIEW C 78 (6) ARTN 061302 AMER PHYSICAL SOC
Garnsworthy AB, Regan PH, Caceres L, Pietri S, Sun Y, Rudolph D, Gorska M, Podolyak Z, Steer SJ, Hoischen R, Heinz A, Becker F, Bednarczyk P, Doornenbal P, Geissel H, Gerl J, Grawe H, Grebosz J, Kelic A, Kojouharov I, Kurz N, Montes F, Prokopowicz W, Saito T, Schaffner H, Tachenov S, Werner-Malento E, Wollersheim HJ, Benzoni G, Blank BB, Brandau C, Bruce AM, Camera F, Catford WN, Cullen IJ, Dombradi Z, Estevez E, Gelletly W, Ilie G, Jolie J, Jones GA, Jungclaus A, Kmiecik M, Kondev FG, Kurtukian-Nieto T, Lalkovski S, Liu Z, Maj A, Myalski S, Pfutzner M, Schwertel S, Shizuma T, Simons AJ, Walker PM, Wielandi O, Xu FR (2008) Neutron-proton pairing competition in N = Z nuclei: Metastable state decays in the proton dripline nuclei Nb-82(41) and Tc-86(43),PHYSICS LETTERS B 660 (4) pp. 326-330 ELSEVIER SCIENCE BV
Wilson E, Podolyák Z, Grawe H, Brown BA, Chiara CJ, Zhu S, Fornal B, Janssens RVF, Shand CM, Bowry M, Bunce M, Carpenter MP, Cieplicka-OryDczak N, Deo AY, Dracoulis GD, Hoffman CR, Kempley RS, Kondev FG, Lane GJ, Lauritsen T, Lotay G, Reed MW, Regan PH, Rodríguez Triguero C, Seweryniak D, Szpak B, Walker PM (2015) Core excitations across the neutron shell gap in <sup>207</sup>Tl,Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 747 pp. 88-92
© 2015 The Authors.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.
Hurst AM, Wu CY, Becker JA, Stoyer MA, Pearson CJ, Hackman G, Schumaker MA, Svensson CE, Austin RAE, Ball GC, Bandyopadhyay D, Barton CJ, Boston AJ, Boston HC, Churchman R, Cline D, Colosimo SJ, Cross DS, Demand G, Djongolov M, Drake TE, Garrett PE, Gray-Jones C, Green KL, Grint AN, Hayes AB, Leach KG, Kulp WD, Lee G, Lloyd S, Maharaj R, Martin J-P, Millar BA, Mythili S, Nelson L, Nolan PJ, Oxley DC, Padilla-Rodal E, Phillips AA, Porter-Peden M, Rigby SV, Sarazin F, Sumithrarachchi CS, Triambak S, Walker PM, Williams SJ, Wong J, Wood JL (2009) Narrowing of the neutron sd-pf shell gap in Na-29,PHYSICS LETTERS B 674 (3) pp. 168-171 ELSEVIER SCIENCE BV
Rajabali MM, Bissell ML, De Schepper S, Dewolf K, Neyens G, Papuga J, Lynch KM, Billowes J, Flanagan KT, Procter TJ, Smith AJ, Cocolios TE, Le Blanc F, Matea I, Verney D, Marsh BA, Rothe S, Mason PJR, Walker PM, Wood RT, Wendt K, Simpson GS, Stroke HH (2013) A dedicated decay-spectroscopy station for the collinear resonance ionization experiment at ISOLDE,Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 707 pp. 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 20¼g/ 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.
Muto S, Stone NJ, Bingham CR, Stone JR, Walker PM, Audi G, Gaulard C, Köster U, Nikolov J, Nishimura K, Ohtsubo T, Podolyak Z, Risegari L, Simpson GS, Veskovic M, Walters WB (2014) Magnetic properties of Hf 177 and Hf 180 in the strong-coupling deformed model,Physical Review C - Nuclear Physics 89 (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 ³ 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.
Walker PM, Xu FR (2006) Shapes of neutron-rich A approximate to 190 odd-odd nuclei, PHYSICAL REVIEW C 74 (6) ARTN 067303 AMERICAN PHYSICAL SOC
Bruce AM, Lalkovski S, Bacelar AMD, Gorska M, Pietri S, Podolyak Z, Shi Y, Walker PM, Xu FR, Bednarczyk P, Caceres L, Casarejos E, Cullen IJ, Doornenbal P, Farrelly GF, Garnsworthy AB, Geissel H, Gelletly W, Gerl J, Grebosz J, Hinke C, Ilie G, Jaworski G, Kojouharov I, Kurz N, Myalski S, Palacz M, Prokopowicz W, Regan PH, Schaffner H, Steer S, Tashenov S, Wollersheim HJ (2010) Shape coexistence and isomeric states in neutron-rich Tc-112 and Tc-113,PHYSICAL REVIEW C 82 (4) ARTN 044312 AMER PHYSICAL SOC
Minkov N, Walker PM (2012) Magnetic moments of K isomers as indicators of octupole collectivity,European Physical Journal A 48 (6) pp. 1-12
The relation between the quadrupole-octupole deformation and the structure of high-K isomers in heavy even-even nuclei is studied through a reflection asymmetric deformed shell model including a BCS procedure with constant pairing interaction. Two-quasiparticle states with KÀ = 4-, 5-, 6-, 6+ and 7- are considered in the region of actinide nuclei (U, Pu and Cm) and rare-earth nuclei (Nd, Sm and Gd). The behaviour of two-quasiparticle energies and magnetic dipole moments of these configurations is examined over a wide range in the plane of quadrupole and octupole deformations (²2 and ²3. In all considered actinide nuclei, the calculations show that there is pronounced sensitivity of the magnetic moments to the octupole deformation. In the rare-earth nuclei, the calculations for 154, 156Gd show stronger sensitivity of the magnetic moment to the octupole deformation than in the other considered cases. © 2012 SIF, Springer-Verlag Berlin Heidelberg.
Shand CM, Wilson E, Podolyák Z, Grawe H, Brown BA, Fornal B, Janssens RVF, Bowry M, Bunce M, Carpenter MP, Carroll RJ, Chiara CJ, Cieplicka-OryDczak N, Deo AY, Dracoulis GD, Hoffman CR, Kempley RS, Kondev FG, Lane GJ, Lauritsen T, Lotay G, Reed MW, Regan PH, Rodriguez-Triguero C, Seweryniak D, Szpak B, Walker PM, Zhu S (2015) Structure of <sup>207</sup>Pb populated in <sup>208</sup>Pb + <sup>208</sup>Pb deep-inelastic collisions, Acta Physica Polonica B 46 (3) pp. 619-622
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
Liu HL, Xu FR, Sun Y, Walker PM, Wyss R (2011) On the stability of high-K isomers in the second well of actinide nuclei,European Physical Journal A 47 (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.
Walker PM, Minkov N (2010) High-K isomers as probes of octupole collectivity in heavy nuclei,Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 694 (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.
Gottardo A, Valiente-Dobón JJ, Benzoni G, Gadea A, Lunardi S, Boutachkov P, Bruce AM, Górska M, Grebosz J, Pietri S, Podolyák Z, Pfützner M, Regan PH, Weick H, Alcántara Núñez J, Algora A, Al-Dahan N, de Angelis G, Ayyad Y, Alkhomashi N, Allegro PRP, Bazzacco D, Benlliure J, Bowry M, Bracco A, Bunce M, Camera F, Casarejos E, Cortes ML, Crespi FCL, Corsi A, Denis Bacelar AM, Deo AY, Domingo-Pardo C, Doncel M, Dombradi Z, Engert T, Eppinger K, Farrelly GF, Farinon F, Farnea E, Geissel H, Gerl J, Goel N, Gregor E, Habermann T, Hoischen R, Janik R, John PR, Klupp S, Kojouharov I, Kurz N, Lenzi SM, Leoni S, Mandal S, Menegazzo R, Mengoni D, Million B, Modamio V, Morales AI, Napoli DR, Naqvi F, Nicolini R, Nociforo C, Prochazka A, Prokopowicz W, Recchia F, Ribas RV, Reed MW, Rudolph D, Sahin E, Schaffner H, Sharma A, Sitar B, Siwal D, Steiger K, Strmen P, Swan TPD, Szarka I, Ur CA, Walker PM, Wieland O, Wollersheim HJ (2013) New ¼s isomers in the neutron-rich 210Hg nucleus,Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 725 (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 210Hg: the 8+ isomer expected from the seniority scheme in the ½g9/2 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..
Garnsworthy AB, Regan PH, Cáceres L, Pietri S, Sun Y, Rudolph D, Górska M, Podolyák Z, Steer SJ, Hoischen R, Heinz A, Becker F, Bednarczyk P, Doornenbal P, Geissel H, Gerl J, Grawe H, Gr)bosz J, Kelic A, Kojouharov I, Kurz N, Montes F, Prokopowicz W, Saito T, Schaffner H, Tachenov S, Werner-Malento E, Wollersheim HJ, Benzoni G, Blank BB, Brandau C, Bruce AM, Camera F, Catford WN, Cullen IJ, Dombrádi Z, Estevez E, Gelletly W, Ilie G, Jolie J, Jones GA, Jungclaus A, Kmiecik M, Kondev FG, Kurtukian-Nieto T, Lalkovski S, Liu Z, Maj A, Myalski S, Pfützner M, Schwertel S, Shizuma T, Simons AJ, Walker PM, Wieland O, Xu FR (2008) Erratum to: "Neutron-proton pairing competition in N = Z nuclei: Metastable state decays in the proton dripline nuclei 82 41Nb and 86 43Tc", Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 668 (5) pp. 460-460
Lalkovski S, Bruce AM, Bacelar AMD, Górska M, Pietri S, Podolyák Z, Bednarczyk P, Caceres L, Casarejos E, Cullen IJ, Doornenbal P, Farrelly GF, Garnsworthy AB, Geissel H, Gelletly W, Gerl J, Gr)bosz J, Hinke C, Ilie G, Jaworski G, Kisyov S, Kojouharov I, Kurz N, Myalski S, Palacz M, Prokopowicz W, Regan PH, Schaffner H, Steer S, Tashenov S, Walker PM, Wollersheim HJ, Zhekova M (2012) Single-particle isomeric states in 121Pd and 117Ru,Journal of Physics: Conference Series 366 (1)
Neutron-rich nuclei were populated in a relativistic fission of 238U. Gamma-rays with energies of 135 keV and 184 keV were associated with two isomeric states in 121Pd and 117Ru. Half-lives of 0.63(5) ¼s and 2.0(3) ¼s were deduced and the isomeric states were interpreted in terms of prolate deformed single-particle states.
Sun B, Knoebel R, Geissel H, Litvinov YA, Walker PM, Blaum K, Bosch F, Boutin D, Brandau C, Chen L, Cullen IJ, Dolinskii A, Fabian B, Hausmann M, Kozhuharov C, Kurcewicz J, Litvinov SA, Liu Z, Mazzocco M, Meng J, Montes F, Muenzenberg G, Musumarra A, Nakajima S, Nociforo C, Nolden F, Ohtsubo T, Ozawa A, Patyk Z, Plass WR, Scheidenberger C, Steck M, Suzuki T, Weick H, Winckler N, Winkler M, Yamaguchi T (2010) Direct measurement of the 4.6 MeV isomer in stored bare Sb-133 ions,PHYSICS LETTERS B 688 (4-5) pp. 294-297 ELSEVIER SCIENCE BV
Morales AI, Benlliure J, Regan PH, Podolyak Z, Gorska M, Alkhomashi N, Pietri S, Kumar R, Casarejos E, Agramunt J, Algora A, Alvarez-Pol H, Benzoni G, Blazhev A, Boutachkov P, Bruce AM, Caceres LS, Cullen IJ, Bacelar AMD, Doornenbal P, Dragosavac D, Estevez ME, Farrelly G, Fujita Y, Garnsworthy AB, Gelletly W, Gerl J, Grebosz J, Hoischen R, Kojouharov I, Kurz N, Lalkovski S, Liu Z, Perez-Loureiro D, Prokopowicz W, Mihai C, Molina F, Muecher D, Rubio B, Schapffner H, Steer SJ, Tamii A, Tashenov S, Dobon JJV, Verma S, Walker PM, Wollersheim HJ, Woods PJ (2009) beta-DELAYED gamma-RAY SPECTROSCOPY OF HEAVY NEUTRON RICH NUCLEI "SOUTH" OF LEAD,ACTA PHYSICA POLONICA B 40 (3) pp. 867-870 POLISH ACAD SCIENCES INST PHYSICS
Yuan C, Liu Z, Xu F, Walker PM, Podolyak Z, Xu C, Ren ZZ, Ding B, Liu XY, Xu HS, Zhang YH, Zhou XH, Zuo W (2016) Isomerism in the ?south-east? of 132Sn and a predicted neutron-decaying isomer in 129Pd, Physics Letters B 762 pp. 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 ³ 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.
Al-Dahan N, Regan PH, Podolyák Z, Walker PM, Alkhomashi N, Dracoulis GD, Farrelly G, Benlliure J, Pietri SB, Casten RF, Stevenson PD, Gelletly W, Steer SJ, Garnsworthy AB, Casarejos E, Gerl J, Wollersheim HJ, Grebosz J, Górska M, Kojouharov I, Schaffner H, Algora A, Benzoni G, Blazhev A, Boutachkov P, Bruce AM, Cullen IJ, Denis Bacelar AM, Deo AY, Estevez ME, Fujita Y, Hoischen R, Kumar R, Lalkovski S, Liu Z, Mason PJ, Mihai C, Molina F, Mücher D, Rubio B, Tamii A, Tashenov S, Valiente-Dobón JJ, Woods PJ (2012) Multiple ² - Decaying states in 194Re: Shape evolution in neutron-rich osmium isotopes,Physical Review C - Nuclear Physics 85 (3) 034301 American Physical Society
decays from heavy, neutron-rich nuclei with A
Rath AK, Walker PM, Praharaj CR, Xu FR (2006) K=6(+) isomers in Hf, Yb and W nuclei, INTERNATIONAL JOURNAL OF MODERN PHYSICS E-NUCLEAR PHYSICS 15 (7) pp. 1653-1663 WORLD SCIENTIFIC PUBL CO PTE LTD
Chen L, Walker PM, Geissel H, Litvinov YA, Beckert K, Beller P, Bosch F, Boutin D, Caceres L, Carroll JJ, Cullen DM, Cullen IJ, Franzke B, Gerl J, Górska M, Jones GA, Kishada A, Knöbel R, Kozhuharov C, Kurcewicz J, Litvinov SA, Liu Z, Mandal S, Montes F, Münzenberg G, Nolden F, Ohtsubo T, Patyk Z, Plaß WR, Podolyák Z, Rigby S, Saito N, Saito T, Scheidenberger C, Simpson EC, Shindo M, Steck M, Sun B, Williams SJ, Weick H, Winkler M, Wollersheim HJ, Yamaguchi T (2013) Direct observation of long-lived isomers in Bi212,Physical Review Letters 110 (12)
Long-lived isomers in Bi212 have been studied following U238 projectile fragmentation at 670 MeV per nucleon. The fragmentation products were injected as highly charged ions into a storage ring, giving access to masses and half-lives. While the excitation energy of the first isomer of Bi212 was confirmed, the second isomer was observed at 1478(30) keV, in contrast to the previously accepted value of >1910 keV. It was also found to have an extended Lorentz-corrected in-ring half-life >30 min, compared to 7.0(3) min for the neutral atom. Both the energy and half-life differences can be understood as being due a substantial, though previously unrecognized, internal decay branch for neutral atoms. Earlier shell-model calculations are now found to give good agreement with the isomer excitation energy. Furthermore, these and new calculations predict the existence of states at slightly higher energy that could facilitate isomer deexcitation studies. © 2013 American Physical Society.
Podolyak Z, Gerl J, Hellstroem M, Becker F, Gladnishki KA, Gorska M, Kelic A, Kopatch Y, Mandal S, Regan PH, Schmidt K-H, Walker PM, Wollersheim HJ, Banu A, Benzoni G, Boardman H, Casarejos E, Ekman J, Geissel H, Grawe H, Hohn D, Kojouharov I, Leske J, Lozeva R, Mineva MN, Neyens G, Page RD, Pearson CJ, Portillo M, Rudolph D, Saito N, Schaffner H, Sohler D, Summerer K, Valiente-Dobon JJ, Wheldon C, Weick H, Winkler M (2006) Neutron-deficient N approximate to 126 nuclei produced in U-238 fragmentation: Population of high-spin states,Frontiers in Nuclear Structure Astrophysics, and Reactions: FINUSTAR 831 pp. 114-118 AMER INST PHYSICS
Litvinov YA, Bosch F, Dillmann I, Egelhof P, Geissel H, Grisenti RE, Hagmann S, Heil M, Knöbel R, Kozhuharov C, Lestinsky M, Nolden F, Sanjari MS, Simon H, Steck M, Stöhlker T, Tu XL, Weick H, Winckler N, Bishop S, Blaum K, Brandau C, Chen LX, Reifarth R, Heinz A, Nilsson T, Kalantar-Nayestanaki N, Ma XW, Xu HS, Zhang YH, Ozawa A, Raabe R, Reed MW, Schneider D, Sun BH, Uesaka T, Wakasugi M, Yamaguchi Y, Walker PM, Woods PJ, Yamaguchi T (2013) Nuclear physics experiments with ion storage rings,Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms 317 (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.
Walker PM, Litvinov YA, Geissel H (2013) The ILIMA project at FAIR,International Journal of Mass Spectrometry 349-350 pp. 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 ¼s 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.
Gottardo A, Valiente-Dobón JJ, Benzoni G, Nicolini R, Núñez JA, Algora A, Al-Dahan N, Angelis GD, Ayyad Y, Alkhomashi N, Allegro PRP, Benlliure J, Boutachkov P, Bowry M, Bracco A, Bruce AM, Bunce M, Casarejos E, Cortes L, Crespi FCL, Camera F, Corsi A, Bacelar AMD, Deo A, Domingo-Pardo C, Doncel M, Dombradi Z, Engert T, Eppinger K, Farrelly GF, Farinon F, Gadea A, Geissel H, Gerl J, Goel N, Górska M, Grebosz J, Gregor E, Haberman T, Hoischen R, Janik R, Klupp S, Kojouharov I, Kurz N, Leoni S, Lunardi S, Mandal S, Menegazzo R, Mengoni D, Million B, Napoli DR, Naqvi F, Nociforo C, Pfützner M, Pietri S, Podolyak Z, Prochazka A, Prokopowicz W, Recchia F, Ribas RV, Reed MW, Regan PH, Rudolph D, Sahin E, Schaffner H, Sharma A, Sitar B, Siwal D, Steger K, Strmen P, Swan TPD, Szarka I, Walker PM, Wieland O, Weick H, Wollersheim H-J (2011) Isomers in neutron-rich lead isotopes populated via the fragmentation of 238U at 1 GeV A,Journal of Physics: Conference Series: International Nuclear Physics Conference 312 (Section 9) Institute of Physics
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.
Garnsworthy AB, Regan PH, Pietri S, Rudolph D, Caceres L, Gorska M, Podolyak Z, Steer SJ, Heinz A, Becker F, Bednarczyk P, Doornenbal P, Geissel H, Gerl J, Grawe H, Grebosz J, Kelic A, Kojouharov I, Kurz N, Montes F, Prokopwicz W, Saito T, Schaffner H, Tachenov S, Werner-Malento E, Wollersheim HJ, Benzoni G, Blank B, Brandau C, Bruce AM, Camera F, Catford WN, Cullen IJ, Dombradi Z, Estevez E, Gelletly W, Hoischen R, Ilie G, Jolie J, Jones GA, Jungclaus A, Kmiecik M, Kondev FG, Kurtukian-Nieto T, Lalkovski S, Liu Z, Maj A, Myalski S, Pfutzner M, Shizuma T, Simons AJ, Schwertel S, Walker PM, Wieland O (2007) Isomeric states in the light Tc isotopes, ACTA PHYSICA POLONICA B 38 (4) pp. 1265-1269 ACTA PHYSICA POLONICA B, JAGELLONIAN UNIV, INST PHYSICS
Mohammadi S, De Angrlis G, Axiotis M, Bazzacco D, Bizzeti PG, Brandolini F, Broda R, Bucurescu D, Farnea E, Gelletly W, Gadea A, Ionescu-Bujor M, Iordachescu A, Kröll T, Longdown S, Lunardi S, Marginean N, Martinez T, Medina N, Podolyák Z, Quintana B, Regan PH, Rubio B, Ur CA, Valiente Dobon JJ, Walker PM, Zhang YH (2006) Yrast states in 188,190 Os nuclei, International Journal of Modern Physics E 15 (8) pp. 1797-1802
Yrast states in neutron rich nuclei 188Os and 190Os have been populated using the deep-inelastic reaction 82Se + 192Os at 460 MeV beam bombarding energy. A thick 192Os target (>50 mg/cm2) with 0.2 mm Ta backing was used to stop all of the recoils in the target, minimising the broadening of the lines due to Doppler shift. High fold ³-³ coincidences were aquired with the 4À spectrometer GASP detector array. Three and two dimensional gamma-ray matrices were used to construct level schemes of the nuclei of interest up to an yrast state of 22. © World Scientific Publishing Company.
Podolyak Z, Steer SJ, Pietri S, Werner-Malento E, Regan PH, Rudolph D, Garnsworthy AB, Hoischen R, Gorska M, Gerl J, Wollersheim HJ, Kurtukian-Nieto T, Benzoni G, Becker F, Bednarczyk P, Caceres L, Doornenbal P, Geissel H, Grebosz J, Kelic A, Kojouharov I, Kurz N, Montes F, Prokopowicz W, Saito T, Schaffner H, Tashenov S, Heinz A, Pfutzner M, Hellstrom M, Jungclaus A, Andersson L-L, Atanasova L, Balabanski DL, Bentley A, Blank B, Blazhev A, Brandau C, Brown J, Bruce AM, Camera F, Catford WN, Cullen IJ, Dombradi Z, Estevez E, Fahlander C, Gelletly W, Ilie G, Johansson EK, Jolie J, Jones GA, Kmiecik M, Kondev FG, Lalkovski S, Liu Z, Maj A, Myalski S, Shizuma T, Simons AJ, Schwertel S, Walker PM, Wieland O, Brown BA (2007) Isomeric decay studies around Pt-204 and Tb-148, EUROPEAN PHYSICAL JOURNAL-SPECIAL TOPICS 150 pp. 165-168 EDP SCIENCES S A
Walker PM (2006) Nuclear isomers: stepping stones to the unknown,Capture Gamma-Ray Spectroscopy and Related Topics 819 pp. 16-23 AMER INST PHYSICS
Reed MW, Walker PM, Cullen IJ, Litvinov YA, Shubina D, Dracoulis GD, Blaum K, Bosch F, Brandau C, Carroll JJ, Cullen DM, Deo AY, Detwiler B, Dimopoulou C, Dong GX, Farinon F, Geissel H, Haettner E, Heil M, Kempley RS, Knoebel R, Kozhuharov C, Kurcewicz J, Kuzminchuk N, Litvinov S, Liu Z, Mao R, Nociforo C, Nolden F, Plass WR, Podolyak Z, Prochazka A, Scheidenberger C, Steck M, Stoehlker T, Sun B, Swan TPD, Trees G, Weick H, Winckler N, Winkler M, Woods PJ, Xu FR, Yamaguchi T (2012) Long-lived isomers in neutron-rich Z=72-76 nuclides,PHYSICAL REVIEW C 86 (5) ARTN 054321 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.
Liu HL, Xu FR, Xu SW, Wyss R, Walker PM (2007) High-spin isomeric structures in exotic odd-odd nuclei: Exploration of the proton drip line and beyond, PHYSICAL REVIEW C 76 (3) ARTN 034313 AMER PHYSICAL SOC
Regan PH, Alkhomashi N, Al-Dahan N, Podolyak Z, Suckling EB, Stevenson PD, Pietri SB, Steer SJ, Garnsworthy AB, Gelletly W, Benlliure J, Morales AI, Gerl J, Gorska M, Wollersheim HJ, Kumar R, Grebosz J, Algora A, Benzoni G, Boutachkov P, Bruce AM, Casarejos E, Cullen IJ, Bacelar AMD, Blazhev A, Estevez ME, Farrelly G, Fujita Y, Hoischen R, Lalkovski S, Liu Z, Kojouharov I, Kurz N, Mihai C, Molina F, Muecher D, Rubio B, Schaffner H, Tashenov S, Tamii A, Dobon JJV, Walker PM, Woods PJ (2009) New Insights into the Structure of Exotic Nuclei Using the RISING Active Stopper,CAPTURE GAMMA-RAY SPECTROSCOPY AND RELATED TOPICS 1090 pp. 122-129 AMER INST PHYSICS
Al-Dahan N, Podolyak Z, Regan PH, Steer SJ, Alkhomashi N, Bacelar AMD, Gorska M, Pietri SB, Gelletly W, Walker PM, Farrelly G, Morales AI, Deo AY, Cullen IJ, Gerl J, Domingo-Pardo C, Verma S, Swan T, Wollersheim HJ, Bruce AM, Lalkovski S, Benlliure J, Algora A, Boutachkov P, Bracco A, Calore E, Casarejos E, Detistov P, Dombradi Z, Doncel M, Farinon F, Geissel H, Goel N, Grebosz J, Hoischen R, Kojouharov I, Leoni S, Molina F, Montanari D, Musumarra A, Nicolini R, Napoli DR, Nociforo C, Rubio B, Prochazka A, Rudolph D, Strmen P, Szarka I, Valiente-Dobon JJ, Weick H (2009) Structure of N >= 126 nuclei produced in fragmentation of (238)U,CAPTURE GAMMA-RAY SPECTROSCOPY AND RELATED TOPICS 1090 pp. 145-148 AMER INST PHYSICS
Ball GC, Andreoiu C, Austin RAE, Bandyopadhyay D, Becker JA, Bricault P, Brown N, Chan S, Churchman R, Colosimo S, Coombes H, Cross D, Demand G, Drake TE, Dombsky M, Ettenauer S, Finlay P, Furse D, Garnsworthy A, Garrett PE, Green KL, Grinyer GF, Hyland B, Hackman G, Kanungo R, Kulp WD, Lassen J, Leach KG, Leslie JR, Mattoon C, Melconian D, Morton AC, Pearson CJ, Phillips AA, Rand E, Sarazin F, Svensson CE, Sumithrarachchi S, Schumaker MA, Triambak S, Waddington JC, Walker PM, Wilhams SJ, Wood JL, Wong J, Zganjar EF, Collaboration T (2009) Gamma-ray spectroscopy at TRIUMF-ISAC: The new frontier of radioactive ion beam research, AIP Conference Proceedings: First Ulaanbaatar Conference on Nuclear Physics and Applications 1109 pp. 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 8À spectrometer and its associated auxiliary detectors is optimize for ²?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 8À spectrometer.
Steer SJ, Podolyak Z, Pietri S, Gorska M, Grawe H, Maier KH, Regan PH, Rudolph D, Garnsworthy AB, Hoischen R (2011) Isomeric states observed in heavy neutron-rich nuclei populated in the fragmentation of a (208)Pb beam,PHYSICAL REVIEW C 84 (4) ARTN 044313 American Physical Society
Alexander T, Podolyák Z, Cortes ML, Gerl J, Rudolph D, Sarmiento LG, Ameil F, Arici T, Bazzacco D, Bauer C, Bentley MA, Blazhev A, Bowry M, Boutachkov P, Carroll R, Fahlander C, Gadea A, Gellanki J, Gelletly W, Givechev A, Goel N, Golubev P, Górska M, Gottardo A, Gregor E, Guastalla G, Habermann T, Hackstein M, Jungclaus A, Kojouharov I, Korten W, Kumar S, Kurz N, Lalovic N, Lettmann M, Lizarazo C, Louchart C, Mandal S, Merchán E, Michelagnoli C, Möller T, Moschner K, Patel Z, Pietralla N, Pietri S, Ralet D, Reese M, Regan PH, Reiter P, Schaffner H, Singh P, Stahl C, Stegmann R, Stezowksi O, Taprogge J, Thöle P, Walker PM, Wieland O, Wendt A, Wilson E, Wood R, Wollersheim HJ (2015) Isomeric ratios in <sup>206</sup>Hg, Acta Physica Polonica B 46 (3) pp. 601-605
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-ray tracking array worked properly and that the tracking efficiency was independent of the time relative to the prompt flash.
Walker P (2014) Nuclear physics: Track it to the limit, Nature Physics 10 (5) pp. 338-339
Liu HL, Xu FR, Walker PM, Bertulani CA (2011) Effects of high-order deformation on high-K isomers in superheavy nuclei,Physical Review C - Nuclear Physics 83 (1) 011303(R) pp. --- American Physical Society
Using, for the first time, configuration-constrained potential-energy-surface calculations with the inclusion of ²6 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 ²6 deformation significantly improves the description of the very heavy high-K isomers.
Myalski S, Maj A, Podolyak Z, Becker F, Bednarczyk P, Benzoni G, Blank B, Brandau C, Bruce AM, Caceres L, Camera F, Catford WN, Cullen IJ, Dombradi Z, Doornenbal P, Estevez E, Garnsworthy AB, Geissel H, Gelletly W, Gerl J, Corska M, Grawe H, Grebosz J, Heinz A, Hoischen R, Ilie G, Jones GA, Jungclaus A, Kelic A, Kmiecik M, Kojouharov I, Kondev FG, Kurtukian-Nieto T, Kurz N, Lalkovski S, Liu Z, Montes F, Pfuetzner M, Pietri S, Prokopowicz W, Regan PH, Rudolph D, Saito T, Schaffner H, Schwertel S, Shizuma T, Simon AJ, Steer SJ, Tashenov S, Walker PM, Werner-Malento E, Wieland O, Wollersheim HJ (2009) ISOMERIC RATIOS FOR NUCLEI WITH Z=62-67 AND A=142-152 PRODUCED IN THE RELATIVISTIC FRAGMENTATION OF Pb-208,ACTA PHYSICA POLONICA B 40 (3) pp. 879-883 WYDAWNICTWO UNIWERSYTETU JAGIELLONSKIEGO
Bruce AM, Bacelar AMD, Benzoni G, Gadea A, Górska M, Gottardo A, Pietri S, Podolyák Z, Valiente-Dobón JJ, Alcántara-Núñez JA, Al-Dahan N, Algora A, Alkhomashi N, Allegro PRP, Ayyad Y, Boutachkov P, Bowry M, Bunce M, Casarejos E, Cortés ML, Deo AY, Domingo-Prado C, Doncel M, Eppinger K, Farinon F, Farrelly GF, Geissel H, Gerl J, Goel N, Gr)bosz J, Gregor E, Haberman T, Hoischen R, Janik R, Klupp S, Kojouharov I, Kurz N, Lunardi S, Mandal S, Menegazzo R, Mengoni D, Naqvi F, Nicolini R, Nociforo C, Pissulla T, Prochazka A, Prokopowicz W, Regan PH, Rudolph D, Sahin E, Schaffner H, Sharma A, Sitar B, Siwal D, Steiger K, Strmen P, Szarka I, Walker PM, Weick H, Wollersheim HJ (2012) ² decay of 102Y produced in projectile fission of 238U,Journal of Physics: Conference Series 381 (1)
The population of 102Zr following the ² decay of 102Y produced in the projectile fission of 238U at the GSI facility in Darmstadt, Germany has been studied. 102Y is known to decay into 102Zr via two states, one of high spin and the other low spin. These states preferentially populate different levels in the 102Zr daughter. In this paper the intensities of transitions in 102Zr 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.
Alkhomashi N, Regan PH, Podoyak Z, Pietri SB, Garnsworthy AB, Steer SJ, Benlliure J, Caserejos E, Gorska M, Gerl J, Wollersheim HJ, Grebosz J, Kurz N, Kojouharov I, Schaffner H, Alcora A, Benzoni G, Blazhev A, Boutachkov P, Bruce AM, Caceres L, Doornenbal P, Bacelar AMD, Cullen IJ, Estevez ME, Farrelly G, Fujita Y, Gelletly W, Hoischen R, Kumar R, Lalkovski S, Liu Z, Mihai C, Molina F, Muecher D, Rubio B, Tamii A, Tashenov S, Valiente-Dobon JJ, Walker PM, Woods PJ (2009) beta(-)-DELAYED AND ISOMER SPECTROSCOPY OF NEUTRON-RICH Ta AND W ISOTOPES,ACTA PHYSICA POLONICA B 40 (3) pp. 875-878 WYDAWNICTWO UNIWERSYTETU JAGIELLONSKIEGO
Walker P, Stuchbery A, Kondev F (2014) George Dionisios Dracoulis obituary, PHYSICS TODAY 67 (11) pp. 66-66 AMER INST PHYSICS
Walker PM, Xu FR (2006) Isomers in the region of neutron-rich Hf-188, ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY 231 AMER CHEMICAL SOC
Swan TPD, Walker PM, Podolyak Z, Reed MW, Dracoulis GD, Lane GJ, Kibedi T, Smith ML (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,PHYSICAL REVIEW C 83 (3) ARTN 034322 AMER PHYSICAL SOC
Farrelly GF, Podolyak Z, Steer SJ, Pietri S, Xu FR, Werner-Malento E, Shizuma T, Regan PH, Rudolph D, Garnsworthy AB, Hoischen R, Gorska M, Gerl J, Wollersheim HJ, Kurtukian-Nieto T, Benzoni G, Becker F, Bednarczyk P, Caceres L, Doornenbal P, Geisserl H, Grebosz J, Kelic A, Kojouharov I, Kurz N, Montes F, Prokopowicz W, Saito T, Schaffner H, Tashenov S, Heinz A, Pfuezner M, Jungclaus A, Balabanski DL, Brandau C, Bruce AM, Catford WN, Cullen IJ, Dombradi Z, Estevez E, Gelletly W, Ilie G, Jolie J, Jones GA, Kmiecik M, Kondev FG, Kruecken R, Lalkovski S, Liu HL, Liu Z, Maj A, Myalski S, Schwerrel S, Walker PM, Wieland O (2009) REVISION OF THE K-ISOMER IN W-190(116),ACTA PHYSICA POLONICA B 40 (3) pp. 885-888 WYDAWNICTWO UNIWERSYTETU JAGIELLONSKIEGO
Walker PM, Johnson RC (2007) Two-proton radioactivity - Caught in the act, NATURE PHYSICS 3 (12) pp. 836-837 NATURE PUBLISHING GROUP
Chen F-Q, Liu Y-X, Sun Y, Walker PM, Dracoulis GD (2012) Residual interactions and the K-mixing-induced fast decay of the three-quasiparticle isomer in Tm-171,Physical Review C (Nuclear Physics) 85 (2) 024324 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.
Chen L, Plaß WR, Geissel H, Knöbel R, Kozhuharov C, Litvinov YA, Patyk Z, Scheidenberger C, SiegieD-Iwaniuk K, Sun B, Weick H, Beckert K, Beller P, Bosch F, Boutin D, Caceres L, Carroll JJ, Cullen DM, Cullen IJ, Franzke B, Gerl J, Górska M, Jones GA, Kishada A, Kurcewicz J, Litvinov SA, Liu Z, Mandal S, Montes F, Münzenberg G, Nolden F, Ohtsubo T, Podolyák Z, Propri R, Rigby S, Saito N, Saito T, Shindo M, Steck M, Ugorowski P, Walker PM, Williams S, Winkler M, Wollersheim H-J, Yamaguchi T (2010) Discovery and investigation of heavy neutron-rich isotopes with time-resolved Schottky spectrometry in the element range from thallium to actinium,Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 691 (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 ¼s 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.
Deo AY, Podolyak Z, Walker PM, Algora A, Rubio B, Agramunt J, Fraile LM, Al-Dahan N, Alkhomashi N, Briz JA, Estevez E, Farrelly G, Gelletly W, Herlert A, Koester U, Maira A, Singla S (2010) Structures of Po-201 and Rn-205 from EC/beta(+)-decay studies,PHYSICAL REVIEW C 81 (2) ARTN 024322 AMER PHYSICAL SOC
Schumaker MA, Hurst AM, Svensson CE, Wu CY, Becker JA, Cline D, Hackman G, Pearson CJ, Stoyer MA, Andreyev A, Austin RAE, Ball GC, Bandyopadhyay D, Barton CJ, Boston AJ, Boston HC, Buchmann L, Churchman R, Cifarelli F, Colosimo SJ, Cooper RJ, Cross DS, Dashdorj D, Demand GA, Dimmock MR, Djongolov M, Drake TE, Finlay P, Gallant AT, Garrett PE, Gray-Jones C, Green KL, Grint AN, Grinyer GF, Harkness LJ, Hayes AB, Kanungo R, Leach KG, Kulp WD, Lisetskiy AF, Lee G, Lloyd S, Maharaj R, Martin J-P, Millar BA, Moisan F, Morton AC, Mythili S, Nelson L, Newman O, Nolan PJ, Orce JN, Oxley DC, Padilla-Rodal E, Phillips AA, Porter-Peden M, Ressler JJ, Rigby SV, Roy R, Ruiz C, Sarazin F, Scraggs DP, Sumithrarachchi CS, Triambak S, Waddington JC, Walker PM, Wan J, Whitbeck A, Williams SJ, Wong J, Wood JL (2009) First results with TIGRESS and accelerated radioactive ion beams from ISAC: Coulomb excitation of20,21,29Na, AIP Conference Proceedings: 20th International Conference on Application of Accelerators in Research and Industry 1099 pp. 754-759
The TRIUMF?ISAC Gamma?Ray Escape Suppressed Spectrometer (TIGRESS) is a state?of?the?art ³?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 ³?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.
Podolyak Z, Steer SJ, Pietri S, Xu FR, Liu HL, Regan PH, Rudolph D, Garnsworthy AB, Hoischen R, Gorska M, Gerl J, Wollersheim HJ, Kurtukian-Nieto T, Benzoni G, Shizuma T, Becker F, Bednarczyk P, Caceres L, Doornenbal P, Geissel H, Grebosz J, Kelic A, Kojouharov I, Kurz N, Montes F, Prokopowicz W, Saito T, Schaffner H, Tashenov S, Heinz A, Pfutzner M, Jungclaus A, Balabanski DL, Brandau C, Bruce AM, Catford WN, Cullen IJ, Dombradi Z, Estevez E, Gelletly W, Ilie G, Jolie J, Jones GA, Kmiecik M, Kondev FG, Kruecken R, Lalkovski S, Liu Z, Maj A, Myalski S, Schwertel S, Walker PM, Werner-Malento E, Wieland O (2009) Weakly deformed oblate structures in Os-198(76)122,PHYSICAL REVIEW C 79 (3) ARTN 031305 AMER PHYSICAL SOC
Reed MW, Walker PM, Cullen IJ, Litvinov YA, Blaum K, Bosch F, Brandau C, Carroll JJ, Cullen DM, Deo AY, Detwiler B, Dimopoulou C, Dracoulis GD, Farinon F, Geissel H, Haettner E, Heil M, Kempley RS, Knoebel R, Kozhuharov C, Kurcewicz J, Kuzminchuk N, Litvinov S, Liu Z, Mao R, Nociforo C, Nolden F, Plass WR, Prochazka A, Scheidenberger C, Shubina D, Steck M, Stoehlker T, Sun B, Swan TPD, Trees G, Weick H, Winckler N, Winkler M, Woods PJ, Yamaguchi T (2012) Technique for Resolving Low-lying Isomers in the Experimental Storage Ring (ESR) and the Occurrence of an Isomeric State in Re-192, RUTHERFORD CENTENNIAL CONFERENCE ON NUCLEAR PHYSICS, 2011 381 IOP PUBLISHING LTD
Lalkovski S, Bruce AM, Bacelar AMD, Gorska M, Pietri S, Podolyak Z, Bednarczyk P, Caceres L, Casarejos E, Cullen IJ, Doornenbal P, Farrelly GF, Garnsworthy AB, Geissel H, Gelletly W, Gerl J, Grebosz J, Hinke C, Ilie G, Ivanova D, Jaworski G, Kisyov S, Kojouharov I, Kurz N, Minkov N, Myalski S, Palacz M, Petkov P, Prokopowicz W, Regan PH, Schaffner H, Steer S, Tashenov S, Walker PM, Wollersheim HJ (2013) Submicrosecond isomer in Rh-117(45)72 and the role of triaxiality in its electromagnetic decay rate,PHYSICAL REVIEW C 88 (2) ARTN 024302 AMER PHYSICAL SOC
Atanasov D, Blaum K, Bosch F, Brandau C, Buehler P, Chen X, Dillmann I, Faestermann T, Gao B, Geissel H, Gernhaeuser R, Hagmann S, Izumikawa T, Hillenbrand P-M, Kozhuharov C, Kurcewicz J, Litvinov SA, Litvinov YA, Ma X, Muenzenberg G, Najafi MA, Nolden F, Ohtsubo T, Ozawa A, Ozturk FC, Patyk Z, Reed M, Reifarth R, Sanjari MS, Schneider D, Steck M, Stoehlker T, Sun B, Suzaki F, Suzuki T, Trageser C, Tu X, Uesaka T, Walker P, Wang M, Weick H, Winckler N, Woods P, Xu H, Yamaguchi T, Yan X, Zhang Y (2015) Between atomic and nuclear physics: radioactive decays of highly-charged ions, JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS 48 (14) ARTN 144024 IOP PUBLISHING LTD
Liu HL, Xu FR, Walker PM, Bertulani CA (2011) Deformation and its influence on K isomerism in neutron-rich Hf nuclei,PHYSICAL REVIEW C 83 (6) ARTN 067303 AMER PHYSICAL SOC
Morales AI, Benlliure J, Górska M, Grawe H, Verma S, Regan PH, Podolyák Z, Pietri S, Kumar R, Casarejos E, Algora A, Alkhomashi N, Álvarez-Pol H, Benzoni G, Blazhev A, Boutachkov P, Bruce AM, Cáceres LS, Cullen IJ, Denis Bacelar AM, Doornenbal P, Estévez-Aguado ME, Farrelly G, Fujita Y, Garnsworthy AB, Gelletly W, Gerl J, Grebosz J, Hoischen R, Kojouharov I, Kurz N, Lalkovski S, Liu Z, Mihai C, Molina F, Mücher D, Prokopowicz W, Rubio B, Schaffner H, Steer SJ, Tamii A, Tashenov S, Valiente-Dobón JJ, Walker PM, Wollersheim HJ, Woods PJ (2013) ²-delayed ³-ray spectroscopy of 203,204Au and 200-202Pt,Physical Review C - Nuclear Physics 88 (1)
The ² decay of five heavy, neutron-rich nuclei, 203,204Pt and 200-202Ir, has been investigated following relativistic cold fragmentation reactions of lead projectiles using the FRS+RISING setup at GSI. This paper reports on the study of the low-lying states in the decay daughter nuclei 203,204Au and 200-202Pt. The characteristic ³ rays for each nucleus have been determined using ²-delayed ³-ray spectroscopy. Tentative level schemes, relative intensities, and apparent ² feedings are provided. These data are compared with shell-model calculations, which indicate a substantial contribution to the total ² strength from high-energy first-forbidden ²-decay transitions in this mass region. © 2013 American Physical Society.
Nakhostin M, Podolyak Z, Regan PH, Walker PM (2010) A digital method for separation and reconstruction of pile-up events in germanium detectors,REVIEW OF SCIENTIFIC INSTRUMENTS 81 (10) ARTN 103507 AMER INST PHYSICS
Rudolph D, Pietri S, Podolyak Z, Regan PH, Garnsworthy AB, Hoischen R, Steer SJ, Becker F, Bednarczyk P, Caceres L, Doornenbal P, Geissel H, Gerl J, Gorska M, Grebosz J, Kelic A, Kojouharov I, Kurz N, Montes F, Prokopowicz W, Saito T, Schaffner H, Tashenov S, Werner-Malento E, Wollersheim HJ, Andersson L-L, Atanasova L, Balabanski DL, Bentley MA, Benzoni G, Blank B, Blazhev A, Brandau C, Brown JR, Bruce AM, Camera F, Catford WN, Cullen IJ, Dombradi Z, Estevez E, Fahlander C, Gelletly W, Heinz A, Hellstrom M, Ilie G, Johansson EK, Jolie J, Jones GA, Jungclaus A, Kmiecik M, Kondev FG, Kurtukian-Nieto T, Lalkovski S, Liu Z, Maj A, Myalski S, Pfutzner M, Shizuma T, Simons AJ, Schwertel S, Walker PM, Wieland O (2007) Exciting isomers from the first stopped-beam RISING campaign, EUROPEAN PHYSICAL JOURNAL-SPECIAL TOPICS 150 pp. 173-176 EDP SCIENCES S A
Podolyak Z, Steer SJ, Pietri S, Gorska M, Regan PH, Rudolph D, Garnsworthy AB, Hoischen R, Gerl J, Wollersheim HJ, Grawe H, Maier KH, Becker F, Bednarczyk P, Caceres L, Doornenbal P, Geissel H, Grebosz J, Kelic A, Kojouharov I, Kurz N, Montes F, Prokopowicz W, Saito T, Schaffner H, Tashenov S, Heinz A, Kurtukian-Nieto T, Benzoni G, Pfuetzner M, Jungclaus A, Balabanski DL, Brandau C, Brown BA, Bruce AM, Catford WN, Cullen IJ, Dombradi Z, Estevez ME, Gelletly W, Ilie G, Jolie J, Jones GA, Kmiecik M, Kondev FG, Kruecken R, Lalkovski S, Liu Z, Maj A, Myalski S, Schwertel S, Shizuma T, Walker PM, Werner-Malento E, Wieland O (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(+)),EUROPEAN PHYSICAL JOURNAL A 42 (3) pp. 489-493 SPRINGER
Patel Z, Söderström PA, Podolyák Z, Regan PH, Walker PM, Watanabe H, Ideguchi E, Simpson GS, Liu HL, Nishimura S, Wu Q, Xu FR, Browne F, Doornenbal P, Lorusso G, Rice S, Sinclair L, Sumikama T, Wu J, Xu ZY, Aoi N, Baba H, Bello Garrote FL, Benzoni G, Daido R, Fang Y, Fukuda N, Gey G, Go S, Gottardo A, Inabe N, Isobe T, Kameda D, Kobayashi K, Kobayashi M, Komatsubara T, Kojouharov I, Kubo T, Kurz N, Kuti I, Li Z, Matsushita M, Michimasa S, Moon CB, Nishibata H, Nishizuka I, Odahara A, ^ahin E, Sakurai H, Schaffner H, Suzuki H, Takeda H, Tanaka M, Taprogge J, Vajta Z, Yagi A, Yokoyama R (2014) Isomer decay spectroscopy of Sm 164 and Gd 166: Midshell collectivity around N=100,Physical Review Letters 113 (26)
© 2014 American Physical Society.Excited states in the N=102 isotones Gd166 and Sm164 have been observed following isomeric decay for the first time at RIBF, RIKEN. The half-lives of the isomeric states have been measured to be 950(60) and 600(140) ns for Gd166 and Sm164, respectively. Based on the decay patterns and potential energy surface calculations, including ²6 deformation, a spin and parity of 6- has been assigned to the isomeric states in both nuclei. Collective observables are discussed in light of the systematics of the region, giving insight into nuclear shape evolution. The decrease in the ground-band energies of Gd166 and Sm164 (N=102) compared to Gd164 and Sm162 (N=100), respectively, presents evidence for the predicted deformed shell closure at N=100.
Xu FR, Liu HL, Wang HL, Pei JC, Shi Y, Walker PM, Frauendorf S (2013) New studies on the aspects of nuclear shapes, Acta Physica Polonica B 44 (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 (²6) 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
Chen L, Plaß WR, Geissel H, Knöbel R, Kozhuharov C, Litvinov Y, Patyk Z, Scheidenberger C, SiegieD-Iwaniuk K, Sun B, Weick H, Beckert K, Beller P, Bosch F, Boutin D, Caceres L, Carroll JJ, Cullen DM, Cullen IJ, Franzke B, Gerl J, Górska M, Jones GA, Kishada A, Kurcewicz J, Litvinov SA, Liu Z, Mandal S, Montes F, Münzenberg G, Nolden F, Ohtsubo T, Podolyák Z, Propri R, Rigby S, Saito N, Saito T, Shindo M, Steck M, Walker PM, Williams S, Winkler M, Wollersheim H-J, Yamaguchi T (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,Nuclear Physics A 882 pp. 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.
Orce JN, Bruce AM, Emmanouilidis A, Byrne AP, Dracoulis GD, Kibedi T, Caamano M, El-Masri H, Pearson CJ, Podolyak Z, Stevenson PD, Walker PM, Xu FR, Cullen DM, Wheldon C (2006) Shape-driving effects in the triaxial nucleus, Xe-128, PHYSICAL REVIEW C 74 (3) ARTN 034318 AMERICAN PHYSICAL SOC
Pietri S, Regan PH, Podolyak Z, Rudolph D, Steer S, Garnsworthy AB, Werner-Malento E, Hoischen R, Gorska M, Gerl J, Wollersheim HJ, Kojouharov I, Schaffner H, Becker F, Bednarczyk P, Caceres L, Doornenbal P, Geissel H, Grebosz J, Kelic A, Kurz N, Montes F, Prokopowicz W, Saito T, Tashenov S, Heinz A, Pfuetzner M, Kurtukian-Nieto T, Benzoni G, Hellstrom M, Jungclaus A, Simpson J, Andersson L-L, Atanasova L, Balabanski D, Bentley MA, Blank B, Blazhev A, Brandau C, Brown JR, Bruce AM, Camera F, Catford WN, Cullen IJ, Dombradi Z, Estevez E, Fahlander C, Gelletly W, Ilie G, Johansson EK, Jolie J, Jones GA, Kmiecik M, Kondev FG, Lalkovski S, Liu Z, Maj A, Myalski S, Shizuma T, Simons AJ, Schwertel S, Walker PM, Wieland O (2007) Recent results in fragmentation isomer spectroscopy with rising, NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS 261 (1-2) pp. 1079-1083 ELSEVIER SCIENCE BV
Walker PM, Xu FR (2016) High-K isomerism in rotational nuclei,PHYSICA SCRIPTA 91 (1) ARTN 01301 IOP PUBLISHING LTD
Knoebel R, Diwisch M, Bosch F, Boutin D, Chen L, Dimopoulou C, Dolinskii A, Franczak B, Franzke B, Geissel H, Hausmann M, Kozhuharov C, Kurcewicz J, Litvinov SA, Martinez-Pinedo G, Matos M, Mazzocco M, Muenzenberg G, Nakajima S, Nociforo C, Nolden F, Ohtsubo T, Ozawa A, Patyk Z, Plass WR, Scheidenberger C, Stadlmann J, Steck M, Sun B, Suzuki T, Walker PM, Weick H, Wu M-R, Winkler M, Yamaguchi T (2016) First direct mass measurements of stored neutron-rich Cd-129,Cd-130,Cd-131 isotopes with FRS-ESR,PHYSICS LETTERS B 754 pp. 288-293 ELSEVIER SCIENCE BV
Liu HL, Xu FR, Walker PM (2012) Understanding the different rotational behaviors of No-252 and No-254,PHYSICAL REVIEW C 86 (1) ARTN 011301 AMER PHYSICAL SOC
Morales AI, Benlliure J, Kurtukián-Nieto T, Schmidt KH, Verma S, Regan PH, Podolyák Z, Górska M, Pietri S, Kumar R, Casarejos E, Al-Dahan N, Algora A, Alkhomashi N, Álvarez-Pol H, Benzoni G, Blazhev A, Boutachkov P, Bruce AM, Cáceres LS, Cullen IJ, Denis Bacelar AM, Doornenbal P, Estévez-Aguado ME, Farrelly G, Fujita Y, Garnsworthy AB, Gelletly W, Gerl J, Grebosz J, Hoischen R, Kojouharov I, Kurz N, Lalkovski S, Liu Z, Mihai C, Molina F, Mücher D, Rubio B, Shaffner H, Steer SJ, Tamii A, Tashenov S, Valiente-Dobón JJ, Walker PM, Wollersheim HJ, Woods PJ (2014) Half-life systematics across the N=126 shell closure: role of first-forbidden transitions in the ² decay of heavy neutron-rich nuclei.,Phys Rev Lett 113 (2)
This Letter reports on a systematic study of ²-decay half-lives of neutron-rich nuclei around doubly magic (208)Pb. The lifetimes of the 126-neutron shell isotone (204)Pt and the neighboring (200-202)Ir, (203)Pt, (204)Au are presented together with other 19 half-lives measured during the "stopped beam" campaign of the rare isotope investigations at GSI collaboration. The results constrain the main nuclear theories used in calculations of r-process nucleosynthesis. Predictions based on a statistical macroscopic description of the first-forbidden ² strength reveal significant deviations for most of the nuclei with N
Hayes AB, Cline D, Wu CY, Hurst AM, Carpenter MP, Greene JP, Janssens RVF, Lauritsen T, Seweryniak D, Zhu S, Karamian SA, Walker PM, Swan TPD, Rigby SV, Cullen DM, Lumley NM, Mason P, Carroll JJ, Detwiler B, Harle T, Mills I, Trees G (2011) NEW STRUCTURES IN (HF)-H-178 AND COULOMB EXCITATION OF ISOMERS,INTERNATIONAL JOURNAL OF MODERN PHYSICS E-NUCLEAR PHYSICS 20 (2) pp. 474-481 WORLD SCIENTIFIC PUBL CO PTE LTD
Steer SJ, Podolyak Z, Pietri S, Regan PH, Rudolph D, Werner-Malento E, Garnsworthy AB, Hoischen R, Gorska M, Gerl J, Wollersheim HJ, Becker F, Bednarczyk P, Caceres L, Doornenbal P, Geissel H, Grebosz J, Kelic A, Kurz N, Montes F, Prokopowicz W, Saito T, Schaffner H, Tachenov S, Heinz A, Pfuetzner M, Kurtukian-Nieto T, Benzoni G, Jungclaus A, Balabanski DL, Brandau C, Bruce AM, Catford WN, Cullen IJ, Dombradi Z, Estevez E, Gelletly W, Ilie G, Jolie J, Jones GA, Kmiecik M, Kondev FG, Lalkovski S, Liu Z, Maj A, Myalski S, Shizuma T, Schwertel S, Walker PM, Wieland O (2007) Identification of isomeric states 'south' of Pb-208 via projectile fragmentation, ACTA PHYSICA POLONICA B 38 (4) pp. 1283-1286 ACTA PHYSICA POLONICA B, JAGELLONIAN UNIV, INST PHYSICS
Minkov N, Walker P (2014) Influence of the octupole mode on nuclear high-K isomeric properties, Physica Scripta 89 (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.
Garnsworthy AB, Regan PH, Pietri S, Sun Y, Xu FR, Rudolph D, Gorska M, Caceres L, Podolyak Z, Steer SJ, Hoischen R, Heinz A, Becker F, Bednarczyk P, Doornenbal P, Geissel H, Gerl J, Grawe H, Grebosz J, Kelic A, Kojouharov I, Kurz N, Montes F, Prokopwicz W, Saito T, Schaffner H, Tachenov S, Werner-Malento E, Wollersheim HJ, Benzoni G, Blank B, Brandau C, Bruce AM, Camera F, Catford WN, Cullen IJ, Dombradi Z, Estevez E, Gelletly W, Ilie G, Jolie J, Jones GA, Jungclaus A, Kmiecik M, Kondev FG, Kurtukian-Nieto T, Lalkovski S, Liu Z, Maj A, Myalski S, Pfuetzner M, Schwertel S, Shizuma T, Simons AJ, Walker PM, Wieland O (2009) Isomeric states in neutron-deficient A similar to 80-90 nuclei populated in the fragmentation of Ag-107,PHYSICAL REVIEW C 80 (6) ARTN 064303 AMER PHYSICAL SOC
Reed MW, Cullen IJ, Walker PM, Litvinov YA, Blaum K, Bosch F, Brandau C, Carroll JJ, Cullen DM, Deo AY, Detwiller B, Dimopoulou C, Dracoulis GD, Farinon F, Geissel H, Haettner E, Heil M, Kempley RS, Knoebel R, Kozhuharov C, Kurcewicz J, Kuzminchuk N, Litvinov S, Liu Z, Mao R, Nociforo C, Nolden F, Plass WR, Prochazka A, Scheidenberger C, Steck M, Stoehlker T, Sun B, Swan TPD, Trees G, Weick H, Winckler N, Winkler M, Woods PJ, Yamaguchi T (2010) Discovery of Highly Excited Long-Lived Isomers in Neutron-Rich Hafnium and Tantalum Isotopes through Direct Mass Measurements,PHYSICAL REVIEW LETTERS 105 (17) ARTN 172501 AMER PHYSICAL SOC
Sethi J, Palit R, Carroll JJ, Karamian S, Saha S, Biswas S, Naik Z, Trivedi T, Litz MS, Datta P, Chattopadhyay S, Donthi R, Garg U, Jadhav S, Jain HC, Kumar S, Mehta D, Naidu BS, Bhat GH, Sheikh JA, Sihotra S, Walker PM (2016) Low-lying states near the I-pi=6(+) isomer in Ag-108,JOURNAL OF PHYSICS G-NUCLEAR AND PARTICLE PHYSICS 43 (1) ARTN 01510 IOP PUBLISHING LTD
Regan PH, Garnsworthy AB, Pietri S, Caceres L, Gorska M, Rudolph D, Podolyak Z, Steer SJ, Hoischen R, Gerl J, Wollersheim HJ, Grebosz J, Schaffner H, Prokopwicz W, Kojouharov I, Becker F, Bednarczyk P, Doornenball P, Geissel H, Grawe H, Kelic A, Kurz N, Montes F, Saito T, Tashenov S, Werner-Malento E, Heinz A, Atanasova L, Balabanski D, Benzoni G, Blank B, Blazhev A, Brandau C, Bruce AM, Camera F, Cullen IJ, Estevez ME, Fahlander C, Gelletly W, Ilie G, Jungclaus A, Jolie J, Kurtukian-Nieto T, Liu Z, Kmiecik M, Maj A, Myalski S, Schwertel S, Shizuma T, Simons AJ, Walker PM, Wieland O (2007) Isomer spectroscopy using relativistic projectile fragmentation at the N=Z line for A similar to 80 -> 90., NUCLEAR PHYSICS A 787 pp. 491C-498C ELSEVIER SCIENCE BV
Podolyák Z, Shand CM, Wilson E, Brown BA, Grawe H, Chiara CJ, Zhu S, Fornal B, Janssens RVF, Bowry M, Bunce M, Carpenter MP, Cieplicka N, Deo AY, Dracoulis GD, Hoffman CR, Kempley RS, Kondev FG, Lane GJ, Lauritsen T, Lotay G, Reed MW, Regan PH, Triguero CR, Seweryniak D, Szpak B, Walker PM (2015) Octupole transitions in the 208Pb region, Journal of Physics: Conference Series 580 (1)
© Published under licence by IOP Publishing Ltd.The 208Pb region is characterised by the existence of collective octupole states. Here we populated such states in 208Pb + 208Pb deep-inelastic reactions. ³-ray angular distribution measurements were used to infer the octupole character of several E3 transitions. The octupole character of the 2318 keV 17- 14+ in 208Pb, 2485 keV 19/2- 13/2+ in 207Pb, 2419 keV 15/2- 9/2+ in 209Pb and 2465 keV 17/2+ 11/2- in 207Tl transitions was demonstrated for the first time. In addition, shell model calculations were performed using two different sets of two-body matrix elements. Their predictions were compared with emphasis on collective octupole states.
Mattoon CM, Sarazin F, Hackman G, Cunningham ES, Austin RAE, Ball GC, Chakrawarthy RS, Finlay P, Garrett PE, Grinyer GF, Hyland B, Koopmans KA, Leslie JR, Phillips AA, Schumaker MA, Scraggs HC, Schwarzenberg J, Smith MB, Svensson CE, Waddington JC, Walker PM, Washbrook B, Zganjar E (2007) beta decay of Na-32,PHYSICAL REVIEW C 75 (1) ARTN 017302 AMERICAN PHYSICAL SOC
Söderström P, Walker PM, Wu J, Liu H, Regan PH, Watanabe H, Doornenbal P, Korkulu Z, Lee P, Liu J, Lorusso G, Nishimura S, Phong V, Sumikama T, Xu F, Yagi A, Zhang G, Ahn D, Alharbi T, Baba H, Browne F, Bruce A, Carroll R, Chae K, Dombradi Z, Estrade A, Fukuda N, Griffin C, Ideguchi E, Inabe N, Isobe T, Kanaoka H, Kanaya S, Kojouharov I, Kondev F, Kubo T, Kubono S, Kurz N, Kuti I, Lalkovski S, Lane G, Lee E, Lee C, G. Lotay G, Moon C, Nishizuka I, Nita C, Odahara A, Patel Z, Podolyak Z, Roberts O, Sakurai H, Schaffner H, Shand C, Suzuki H, Takeda H, Terashima S, Vajta Z, Valiente-Dòbon J, Xui Z (2016) Collective And Single-particle Structures In The Neutron-rich Doubly Mid-shell Nucleus 170Dy,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.
Wu J, Nishimura S, Lorusso G, Moller P, Ideguchi E, Regan PH, Simpson G, Soderstrom P, Walker PM, Watanabe H, Xu Z, Baba H, Browne F, Daido R, Doornenbal P, Fang Y, Gey G, Isobe T, Lee P, Liu J, Li Z, Korkulu Z, Patel Z, Phong V, Rice S, Sakurai H, Sinclair L, Sumikama T, Tanaka M, Yagi A, Ye Y, Yokoyama R, Zhang G, Alharbi T, Aoi N, Bello Garrote F, Benzoni G, Bruce A, Carroll R, Chae K, Dombradi Z, Estrade A, Gottardo A, Griffin C, Kanaoka H, Kojouharov I, Kondev F, Kubono S, Kurz N, Kuti I, Lalkovski S, Lane G, Lee E, Lokotko T, Lotay GJ, Moon C, Nishibata H, Nishizuka I, Nita C, Odahara A, Podolyak Z, Roberts O, Schaffner H, Shand CM, Taprogge J, Terashima S, Vajta Z, Yoshida S (2017) 94 -Decay Half-lives of Neutron-Rich 55Cs to 67Ho: Experimental Feedback and Evaluation of the r-Process Rare-Earth Peak Formation,Physical Review Letters 118 (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.
Tu X, Kelic-Heil A, Litvinov Y, Podolyak Z, Zhang Y, Huang W, Xu H, Blaum K, Bosch F, Chen R, Walker PM (2017) Application of Isochronous Mass Spectrometry for the study of angular momentum population in projectile fragmentation reactions,Physical Review C: Nuclear Physics 95 (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.
Pragati, Deo A, Podolyak Z, Walker PM, Algora A, Rubio B, Agramunt J, Fraile L, Al-Dahan N, Alkhomashi N, Briz J, Estevez Aguado M, Farrelly G, Gelletly W, Herlert A, Köster U, Maira A (2016) On the decay of the N = 126, 213Fr nucleus,Physical Review C: Nuclear Physics 94 (6) 064316 American Physical Society
Gamma rays following the EC= + and alpha decay of the N = 126, 213Fr nucleus have been observed at the CERN isotope separator on-line (ISOLDE) facility with the help of gamma-ray and conversion electron spectroscopy. These gamma rays establish several hitherto unknown excited states in 213Rn. Also, ve new -decay branches from the 213Fr ground state have been discovered. Shell model calculations have been performed to understand the newly observed states in 213Rn.
Wang F, Sun B, Liu Z, Page R, Qi C, Scholey C, Ashley S, Bianco L, Cullen I, Darby I, Eeckhaudt S, Garnsworthy A, Gelletly W, Gomez-Hornillos M, Grahn T, Greenlees P, Jenkins D, Jones G, Jones P, Joss D, Julin R, Juutinen S, Ketelhut S, Khan S, Kishada A, Leino M, Niikura M, Nyman M, Pakarinen J, Pietri S, Podolyak Z, Rahkila P, Rigby S, Saren J, Shizuma T, Sorri J, Steer S, Thompson N, Uusitalo J, Walker PM, Williams S, Zhang H, Zhang W, Zhu L (2017) Spectroscopic factor and proton formation probability for the d3/2 proton emitter 151mLu,Physics Letters B 770 pp. 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.
Gurgi LA, Regan PH, Söderström P, Watanabe H, Walker PM, Podolyak Z, Nishimura S, Berry TA, Doornenbal P, Lorusso G, Isobe T, Baba H, Xu Z, Sakurai H, Sumikama T, Catford WN, Bruce A, Browne F, Lane G, Kondev F, Odahara A, Wu J, Liu H, Xu F, Korkulu Z, Lee P, Liu J, Phong V, Yagi A, Zhang G, Alharbi T, Carroll R, Chae K, Dombradi Z, Estrade A, Fukuda N, Griffin C, Ideguchi E, Inabe N, Kanaoka H, Kojouharov I, Kubo T, Kubono S, Kurz N, Kuti I, Lalkovski S, Lee E, Lee C, Lotay GJ, Moon C, Nishizuka I, Nita C, Patel Z, Roberts O, Schaffner H, Shand CM, Suzuki H, Takeda H, Terashima S, Vajta Z, Kanaya S, Valiente-Dobón J (2017) Isomer Spectroscopy of Neutron-rich 165,167Tb,Acta Physica Polonica B 48 (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.
Chen X, Sanjari M, Hülsmann P, Litvinov Y, Nolden F, Piotrowski J, Steck M, Stöhlker T, Walker PM (2016) Intensity-sensitive and position-resolving cavity for heavy-ion storage rings,Nuclear Inst. and Methods in Physics Research, A 826 pp. 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.
Dracoulis G, Walker PM, Kondev F (2016) Review of Metastable States in Heavy Nuclei,Reports on Progress in Physics 79 (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.
Chen X, Zeng Q, Litvinov Y, Tu X, Walker P, Wang M, Wang Q, Yue K, Zhang Y (2017) Statistical approaches to lifetime measurements with restricted observation times,Physical Review C 96 (3) 034302 American Physical Society
Two generic methods based on frequentism and Bayesianism are presented in this work aiming to adequately
estimate decay lifetimes from measured data, while accounting for restricted observation times in the
measurements. All the experimental scenarios that can possibly arise from the observation constraints are
treated systematically and formulas are derived. The methods are then tested against the decay data of bare
isomeric 94mRu44+, which were measured using isochronous mass spectrometry with a timing detector at the
CSRe in Lanzhou, China. Applying both methods in three distinct scenarios yields six different but consistent
lifetime estimates. The deduced values are all in good agreement with a prediction based on the neutral-atom
value modified to take the absence of internal conversion into account. Potential applications of such methods
are discussed.
Patel Z, Walker P, Podolyak Z, Regan P, Berry T, Söderström P, Watanabe H, Ideguchi E, Simpson G, Nishimura S, Wu Q, Xu F, Browne F, Doornenbal P, Lorusso G, Rice S, Sinclair L, Sumikama T, Wu J, Xu Z, Aoi N, Baba H, Bello Garrote F, Benzoni G, Daido R, Dombrádi Z, Fang Y, Fukuda N, Gey G, Go S, Gottardo A, Inabe N, Isobe T, Kameda D, Kobayashi K, Kobayashi M, Komatsubara T, Kojouharov I, Kubo T, Kurz N, Kuti I, Li Z, Matsushita M, Michimasa S, Moon C, Nishibata H, Nishizuka I, Odahara A, Sahin E, Sakurai H, Schaffner H, Suzuki H, Takeda H, Tanaka M, Taprogge J, Vajta Z, Yagi A, Yokoyama R (2017) Isomer-delayed
-ray spectroscopy of A = 159 - 164 midshell nuclei and the variation of
K-forbidden E1 transition hindrance factors
,
Physical Review C 96 (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.
Wood R, Walker P, Lane G, Carroll R, Cullen D, Dracoulis G, Hota S, Kibédi T, Palalani N, Podolyak Z, Reed M, Schiffl K, Wright A (2017) Three-quasiparticle isomer in 173Ta and the excitation energy dependence of K-forbidden transition rates,Physical Review C 95 054308 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, KÀ = 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 H 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.
Nakhostin M, Walker PM, Sellin PJ (2010) Time walk correction of CdTe detectors using depth sensing technique,Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 621 (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.
Walker P (2017) Isomer building blocks and K-forbidden decays,Physica Scripta 92 (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.
Gurgi Laila, Regan Patrick, Söderström P-A, Watanabe H, Walker Philip, Podolyak Zsolt, Nishimura S, Berry Thomas, Doornenbal P, Lorusso G, Isobe T, Baba H, Xu ZY, Sakurai H, Sumikama T, Catford Wilton, Bruce AM, Browne F, Lane GJ, Kondev FG, Odahara A, Wu J, Liu HL, Xu FR, Korkulu Z, Lee P, Liu JJ, Phong VH, Yag A, Zhang GX, Alharbi T, Carroll RJ, Chae KY, Dombradi Zs, Estrade A, Fukuda N, Griffin C, Ideguchi E, Inabe N, Kanaoka H, Kojouharov I, Kubo T, Kubono S, Kurz N, Kuti I, Lalkovski S, Lee EJ, Lee CS, Lotay Gavin, Moon C-B, Nishizuka I, Nita CR, Patel Z, Roberts OJ, Schaffner H, Shand Callum, Suzuki H, Takeda H, Terashima S, Vajta Zs, Yoshida S, Valiente-Dòbon JJ (2016) Isomer spectroscopy of neutron-rich 168Tb103,Radiation Physics and Chemistry 140 pp. 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 ²-decay.
Discrete ³-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)
Walker PM, Dracoulis G, Byrne A, Fabricius B, Kibédi T, Stuchbery A (1991) Resolution of the 179isomer anomaly: Exposure of a Fermi-aligned s band,Physical Review Letters 67 (433) pp. 433-436
Walker Philip (2017) Shape Effects in E2 Transition Rates from Z H 76 High-Spin Isomers,Bulgarian Journal of Physics 44 (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 H 76 (A H 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, f½, on the product of the valence nucleon numbers, NpNn. The present work investigates the application of these ideas to data for neutron-rich Z H 76 (A H 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 H 76 region.
Marmugi L, Walker P, Renzoni F (2017) Coherent gamma photon generation in a Bose?Einstein condensate of135mCs,Physics Letters B 777 pp. 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.
Wu X-Y, Ghorui S, Wang L-J, Sun Y, Guidry M, Walker Philip (2017) Systematic study of multi-quasiparticle K-isomeric bands in tungsten isotopes by the extended
projected shell model
,
Physical Review C 95 (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 H 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 H 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 H 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.

Liu H L, Xu F R, Xu S W, Wyss R, Walker P M (2007) High-Spin Isomeric Structures in Exotic Odd-Odd Nuclei: Exploration of the Proton Drip Line and Beyond,Physical Review C 76 (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.

Stevenson P D, Brine M P, Podolyak Z, Regan P H, Walker P M, Stone J R (2005) Shape Evolution in the Neutron-Rich Tungsten Region,Physical Review C 72 (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.

Jones G A, Regan P H, Walker P M, Podolyak Z, Stevenson P D, Carpenter M P, Carroll J J, Chakrawarthy R S, Chowdhury P, Garnsworthy A B, Janssens R V, Khoo T L, Kondev F G, Lane G J, Liu Z, Seweryniak D, Thompson N J, Zhu S, Williams S J (2007) Identification of a High-Spin Isomer in Mo-99,Physical Review C 76 (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).

Stevenson P. D., Brine M. P., Podolyak Zs., Regan P. H., Walker P. M., Stone J. Rikovska (2005) Shape evolution in the neutron-rich tungsten region,Physical Review C 72 (047303)
Xu F R, Zhao E G, Wyss R, Walker P M (2004) Enhanced Stability of Superheavy Nuclei Due to High-Spin Isomerism,Physical Review Letters 92 (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.

Sun Y, Zhang G, Watanabe H, Kondev F, Lane G, Regan P, Söderström P, Walker P, Kanaoka H, Korkulu Z, Lee P, Liu J, Nishimura S, Wu J, Yagi A, Ahn D, Alharbi T, Baba H, Browne F, Bruce A, Carroll R, Chae K, Dombradi Z, Doornenbal P, Estrade A, Fukuda N, Griffin C, Ideguchi E, Inabe N, Isobe T, Kanaya S, Kojouharov I, Kubo T, Kubono S, Kurz N, Kuti I, Lalkovski S, Lee C, Lee E, Lorusso G, Lotay G, Moon C, Nishizuka I, Nita C, Odahara A, Patel Z, Phong V, Podolyak Z, Roberts O, Sakurai H, Schaffner H, Shand C, Shimizu Y, Sumikama T, Suzuki H, Takeda H, Terashima S, Vajta Z, Valiente-Dóbon J, Xu Z (2018) ²-³ and isomeric decay spectroscopy of 168Dy,EPJ Web of Conferences 178 pp. 02023-1 - 02023-3 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 ² decay from 168Tb. In this contribution, scientific motivations, experimental procedure and some preliminary results for this study are presented.
Podolyák Zs., Walker P. M., Cullen D. M., Dracoulis G. D., Fallon P., Fairchild B., Hauschild K., Macchiavelli A. O., McNabb D. P., Savelius A., Ward D., Wheldon C. (2000) Search for very long-lived isomers in the hafnium-tungsten region,Physical Review C 62 (034303)
Xu F. R., Zhao E. G., Wyss R., Walker P. M. (2004) Enhanced Stability of Superheavy Nuclei Due to High-Spin Isomerism,Physical Review Letters 92 (252501)
Jones G A, Williams S J, Walker P M, Podolyak Z, Zhu S, Carpenter M P, Carroll J J, Chakrawarthy R S, Chowdhury P, Cullen I J, Dracoulis G D, Garnsworthy A B, Hackman G, Janssens R V, Khoo T L, Kondev F G, Lane G J, Liu Z, Seweryniak D, Thompson N J (2008) High-Spin, Multiparticle Isomers in Sb-121,Sb-123,Physical Review C 77 (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.

Liu H. L., Xu F. R., Xu S. W., Wyss R., Walker P. M. (2007) High-spin isomeric structures in exotic odd-odd nuclei: Exploration of the proton drip line and beyond,Physical Review C 76 (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.

An experiment to gather spectroscopic information on a newly discovered isomer in
Hf was performed using the ISOLDE facility at CERN. Protons from the PSBooster
were incident on a Ta/W/Ir target and fluorination using a CF 4 leak allowed the 184 Hf to be
extracted from the ion source. The beam was then accelerated to 30 keV and mass separated
using the General Purpose Separator (GPS). The data was analysed but it was found that
the method used to produce the beam introduced too much contamination for the isomer
to be positively identified. It was possible, however, to verify the successful production of
184
Hf.
184
Another experiment was performed at ANU, Canberra, this time to look at a high-lying
isomer in 173 Ta. A 10 B ? beam was produced using the Multi-Cathode SNICS ion source.
The beam was then accelerated to 68 M eV in the 14UD pelletron. This 10 B ? beam was
then incident on a 168 Er target and the CAESAR Array, which surrounds the target, was
used to detect ³ rays from the reaction products. The isomer was positively identified and
its decay ³ rays were measured to be E = 351 keV , 604 keV and 835 keV . The half-life
of this isomer was measured to be 148 ns with K À = 21/2 ? and f ½ = 18.1, 19.3 and 12.5.
Information about the structure above the isomer was also gathered, along with g K values
associated with these bands. Multi-quasiparticle Nilsson-model calculations were performed
in order to understand the observed structures, and a consistent interpretation was found.
Giatzoglou Alexandros, Poomaradee Tanapoom, Pohjalainen Ilkka, Rinta-Antila Sami, Moore Iain D., Walker Philip M., Marmugi Luca, Renzoni Ferruccio (2018) A facility for production and laser cooling of cesium isotopes and isomers,Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 908 pp. 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
¼
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.
Liu X.Y., Liu Z., Ding B., Doornenbal P., Obertelli A., Lenzi S.M., Walker P.M., Chung L.X., Linh B.D., Authelet G., Baba H., Calvet D., Château F., Corsi A., Delbart A., Gheller J.-M., Gillibert A., Isobe T., Lapoux V., Matsushita M., Momiyama S., Motobayashi T., Niikura M., Nowacki F., Otsu H., Péron C., Peyaud A., Pollacco E.C., Roussé J.-Y., Sakurai H., Sasano M., Shiga Y., Takeuchi S., Taniuchi R., Uesaka T., Wang H., Yoneda K., Lam Y.H., Huang T.H., Sun M.D., Zhang W.Q., Lu H.Y., Hou D.S., Browne F., Dombradi Zs., Franchoo S., Giacoppo F., Gottardo A., Hadynska-Klek K., Korkulu Z., Koyama S., Kubota Y., Lee J., Lettmann M., Lozeva R., Matsui K., Miyazaki T., Nishimura S., Louchart C., Olivier L., Ota S., Patel Z., Sahin E., Santamaria C., Shand C., Söderström P.-A., Stefan G.L., Steppenbeck D., Sumikama T., Suzuki D., Vajta Zs., Werner V., Wu J., Xu Z., Zhou X.H., Zhang Y.H., Xu H.S., Zhang F.S. (2018) Spectroscopy of 2565,67Mn: Strong coupling in the N = 40 ?island of inversion?,Physics Letters B 784 pp. 392-396 Elsevier
Excited states in 63,65,67Mn were studied via in-beam ³-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 ² stability line. These results help to deepen our understanding of the
N=40
?island of inversion?.
Berry T.A., Podolyak Zs., Carroll R.J., Lic? R., Grawe H., Timofeyuk N.K., Alexander T., Andreyev A.N., Ansari S., Borge M.J.G., Creswell J., Fahlander C., Fraile L.M., Fynbo H.O.U., Gelletly W., Gerst R.-B., Górska M., Gredley A., Greenlees P., Harkness-Brennan L.J., Huyse M., Judge S.M., Judson D.S., Konki J., Kurcewicz J., Kuti I., Lalkovski S., Lazarus I., Lund M., Madurga M., M?rginean N., M?rginean R., Marroquin I., Mihai C., Mihai R.E., Nácher E., Nae S., Negret A., Nic? C., Page R.D., Pascu S., Patel Z., Perea A., Pucknell V., Rahkila P., Rapisarda E., Regan P.H., Rotaru F., Shand C.M., Simpson E.C., Sotty Ch., Stegemann S., Stora T., Tengblad O., Turturica A., Van Duppen P., Vedia V., Wadsworth R., Walker P.M., Warr N., Wearing F., De Witte H. (2019) Investigation of the ”n = 0 selection rule in Gamow-Teller transitions: The ²-decay of 207Hg,Physics Letters B 793 pp. 271-275 Elsevier
Gamow-Teller ² decay is forbidden if the number of nodes in the radial wave functions of the initial and final states is different. This ”n=0 requirement plays a major role in the ² 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 à 82) and Z = 82 (for N à 126). The level of forbiddenness of the ”n=1v1g9/2 ’ À0g7/2 transition has been investigated from the ² 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 ³-ray transitions depopulating the À0g-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 à 8.8 within a 95% confidence limit. This is the most stringent test of the ”n=0 selection rule to date.
Rudigier M., Canavan R.L., Regan P.H., Söderström P.-A., Lebois M., Wilson J.N., Jovancevic N., Bottoni S., Brunet M., Cieplicka-Orynczak N., Courtin S., Doherty D.T., Hadynska-Klek K., Heine M., Iskra W., Karayonchev V., Kennington A., Koseoglou P., Lotay G., Lorusso G., Nakhostin M., Nita C.R., S. Oberstedt S., Podolyak Zs., Qi L., Régis J.-M., Shearman R., Walker P.M., Witt W. (2019) Isomer spectroscopy and sub-nanosecond half-live determination in 178w using the NuBall array,Acta Physica Polonica B 50 (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.
Gottardo A., Valiente-Dobón J. J., Benzoni G., Morales A. I., Gadea A., Lunardi S., Boutachkov P., Bruce A. M., Górska M., Grebosz J., Pietri S., Podolyak Zs., Pfützner M., Regan P. H., Rudolph D., Weick H., Alcántara Núñez J., Algora A., Al-Dahan N., de Angelis G., Ayyad Y., Alkhomashi N., Allegro P. R. P., Bazzacco D., Benlliure J., Bowry M., Bracco A., Bunce M., Camera F., Casarejos E., Cortes M. L., Crespi F. C. L., Corsi A., Denis Bacelar A. M., Deo A. Y., Domingo-Pardo C., Doncel M., Dombradi Zs., Engert T., Eppinger K., Farrelly G. F., Farinon F., Geissel H., Gerl J., Goel N., Gregor E., Habermann T., Hoischen R., Janik R., Klupp S., Kojouharov I., Kurz N., Lenzi S. M., Leoni S., Mandal S., Menegazzo R., Mengoni D., Million B., Napoli D. R., Naqvi F., Nociforo C., Prochazka A., Prokopowicz W., Recchia F., Ribas R. V., Reed M. W., Sahin E., Schaffner H., Sharma A., Sitar B., Siwal D., Steiger K., Strmen P., Swan T. P. D., Szarka I., Ur C. A., Walker P.M., Wieland O., Wollersheim H-J., Nowacki F., Maglione E. (2019) New spectroscopic information on 211;213Tl A changing structure beyond the N=126
shell closure
,
Physical Review C 99 (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 ³-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.
Tucholski A., Droste Ch., Srebrny J., Petrache C. M., Skalski J., Jachimowicz P., Fila M., Abraham T., KisieliDski M., Kordyasz A., Kowalczyk M., Kownacki J., Marchlewski T., Napiorkowski P. J., Próchniak L., Samorajczyk-Py[k J., Stolarz A., Astier A., Lv B. F., Dupont E., Lalkovski S., Walker P., Grodner E., Patyk Z. (2019) Lifetime of the recently identified 10+ isomeric state at 3279 keV in the Nd136 nucleus,Physical Review C 100 (1) 014330 American Physical Society

Background:

The ³ 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.

Petrache C.M., Walker P.M., Guo S., Chen Q.B., Frauendorf S., Liu Y.X., Wyss R.A., Mengoni D., Qiang Y.H., Astier A., Dupont E., Li R., Lv B.F., Zheng K.K., Bazzacco D., Boso A., Goasduff A., Recchia F., Testov D., Galtarossa F., Jaworski G., Napoli D.R., Riccetto S., Siciliano M., Valiente-Dobon J.J., Liu M.L., Zhou X.H., Wang J.G., Andreoiu C., Garcia F.H., Ortner K., Whitmore K., Bäck T., Cederwall B., Lawrie E.A., Kuti I., Sohler D., Timár J., Marchlewski T., Srebrny J., Tucholski A. (2019) Diversity of shapes and rotations in the ³-soft 130Ba nucleus: First observation of a t-band in the A = 130 mass region,PHYSICS LETTERS B 795 pp. 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 ½h211/2, 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 ³-soft nucleus can manifest at medium and high spins, revealing a diversity of shapes and rotations for the nuclei in the A =130mass region.
Qiang Y. H., Petrache C. M., Guo S., Walker P.M., Mengoni D., Chen Q. B., Lv B. F., Astier A., Dupont E., Liu M. L., Zhou X. H., Wang J. G., Bazzacco D., Boso A., Goasduff A., Recchia F., Testov D., Galtarossa F., Jaworski G., Napoli D. R., Riccetto S., Siciliano M., Valiente-Dobon J. J., Andreoiu C., Garcia F. H., Ortner K., Whitmore K., Cederwall B., Lawrie E. A., Kuti I., Sohler D., Marchlewski T., Srebrny J., Tucholski A., Dai A. C., Xu F. R. (2019) Identification of high- K rotation in Ba130 : Testing the consistency of electromagnetic observables,Physical Review C 99 (1) 014307 American Physical Society
The band built on the KÀ = 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 KÀ = 8? isomer of 130Ba is now the most complete among the K isomers of the N = 74 isotones.
Ozturk F.C., Akkus B., Atanasov D., Beyer H., Bosch F., Boutin D., Brandau C., Bühler P., Cakirli R.B., Chen R.J., Chen W.D., Chen X.C., Dillmann I., Dimopoulou C., Enders W., Essel H.G., Faestermann T., Forstner O., Gao B.S., Geissel H., Gernhäuser R., Grisenti R.E., Gumberidze A., Hagmann S., Heftrich T., Heil M., Herdrich M.O., Hillenbrand P.-M., Izumikawa T., Kienle P., Klaushofer C., Kleffner C., Kozhuharov C., Knöbel R.K., Kovalenko O., Kreim S., Kühl T., Lederer-Woods C., Lestinsky M., Litvinov S.A., Litvinov Yu.A., Liu Z., Ma X.W., Maier L., Mei B., Miura H., Mukha I., Najafi A., Nagae D., Nishimura T., Nociforo C., Nolden F., Ohtsubo T., Oktem Y., Omika S., Ozawa A., Petridis N., Piotrowski J., Reifarth R., Rossbach J., Sánchez R., Sanjari M.S., Scheidenberger C., Sidhu R.S., Simon H., Spillmann U., Steck M., Stöhlker Th., Sun B.H., Susam L.A., Suzaki F., Suzuki T., Torilov S.Yu., Trageser C., Trassinelli M., Trotsenko S., Tu X.L., Walker P.M., Wang M., Weber G., Weick H., Winckler N., Winters D.F.A., Woods P.J., Yamaguchi T., Xu X.D., Yan X.L., Yang J.C., Yuan Y.J., Zhang Y.H., Zhou X.H. (2019) New test of modulated electron capture decay of hydrogen-like 142Pm ions: Precision measurement of purely exponential decay,PHYSICS LETTERS B 797 134800 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).
Zhang G.X., Watanabe H., Dracoulis G.D., Kondev F.G., Lane G.J., Regan P.H., Söderström P.-A., Walker P.M., Yoshida K., Kanaoka H., Korkulu Z., Lee P.S., Liu J.J., Nishimura S., Wu J., Yagi A., Ahn D.S., Alharbi T., Baba H., Browne F., Bruce A.M., Carpenter M.P., Carroll R.J., Chae K.Y., Chiara C.J., Dombradi Zs., Doornenbal P., Estrade A., Fukuda N., Griffin C., Ideguchi E., Inabe N., Isobe T., Kanaya S., Kojouharov I., Kubo T., Kubono S., Kurz N., Kuti I., Lalkovski S., Lauritsen T., Lee C.S., Lee E.J., Lister C.J., Lorusso G., Lotay G., McCutchan E.A., Moon C.-B., Nishizuka I., Nita C.R., Odahara A., Patel Z., Phong V.H., Podolyak Zs., Roberts O.J., Sakurai H., Schaffner H., Seweryniak D., Shand C.M., Shimizu Y., Sumikama T., Suzuki H., Takeda H., Terashima S., Vajta Zs., Valiente-Dóbon J.J., Xu Z.Y., Zhu S. (2019) Interplay of quasiparticle and vibrational excitations: First observation of isomeric states in ¹vxDy and ¹vyDy,Physics Letters B 799 135036 pp. 1-7 Elsevier
The neutron-rich dysprosium isotopes ¹vxDy€‚ and ¹vyDy€ƒ have been investigated using the EURICA ³-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 ¹vxDy, a previously unreported isomer with a half-life of 0.57(7) ¼s has been identified at an excitation energy of 1378 keV, and its presence affirmed independently using ³-³-³ coincidence data taken with Gammasphere via two-proton transfer from an enriched ¹wpEr target performed at Argonne National Laboratory. This isomer is assigned JÀ = KÀ = (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 ¹vyDy, the B(E2) value for the transition de-exciting the previously unreported KÀ = (1/2{) isomeric state at 166 keV to the KÀ = (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 ¹w³Yb, suggesting the presence of a significant ³-vibrational admixture with a dominant neutron one-quasiparticle component in the isomeric state.
Rudigier M., Walker P. M., Canavan R.L., Podolyak Zs., Regan P. H., Söderström P.-A., Lebois M., Wilson J.N., Jovancevic N., Blazhev A., Benito J., Bottoni S., Brunet M., Cieplicka-Orynczak N., Courtin S., Doherty D. T., Fraile L.M., Hadynska-Klek K., Heine M., Iskra A.W., Jolie J., Karayonchev V., Kennington A. R., Koseoglou P., Lotay G., Lorusso G., Nakhostin M., Nita C.R., Oberstedt S., Qi L., Régis J.-M., Sánchez-Tembleque V., Shearman R., Witt W., Vedia V., Zell K.O. (2020) Multi-quasiparticle sub-nanosecond isomers in 178W,Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 801 135140 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.
Walker Philip M., Podolyak Zsolt (2020) 100 years of nuclear isomers - then and now.,Physica Scripta 95 (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.
Berry T. A., Podolyak Zs., Carroll R. J., Lic? R., Brown B. A., Grawe H., Sotty Ch., Timofeyuk N. K., Alexander T., Andreyev A. N., Ansari S., Borge M. J. G., Brunet M., Cresswell J. R., Fahlander C., Fraile L. M., Fynbo H. O. U., Gamba E., Gelletly W., Gerst R.-B., Górska M., Gredley A., Greenlees P., Harkness-Brennan L. J., Huyse M., Judge S. M., Judson D. S., Konki J., Kowalska M., Kurcewicz J., Kuti I., Lalkovski S., Lazarus I., Lund M., Madurga M., M?rginean N., M?rginean R., Marroquin I., Mihai C., Mihai R. E., Nácher E., Negret A., Nae S., Nic? C., Pascu S., Page R. D., Patel Z., Perea A., Phrompao J., Piersa M., Pucknell V., Rahkila P., Rapisarda E., Regan P. H., Rotaru F., Rudigier M., Shand C. M., Shearman R., Simpson E. C., Stegemann S., Stora T., Tengblad O., Turturica A., Van Duppen P., Vedia V., Walker P. M., Warr N., Wearing F. P., De Witte H. (2020) Octupole states in 207Tl studied through ² decay,Physical Review C 101 (5) 054311 American Physical Society
The ² decay of 207Hg
into the single-proton-hole nucleus 207Tl
has been studied through ³-ray spectroscopy at the ISOLDE Decay Station (IDS) with the aim of identifying states resulting from coupling of the Às?11/2, Àd?13/2, and Àh?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.
Lizarazo C., Soderstrom P.A, Werner V., Pietralla N., Walker P., Dong G.X, Xu F.R, Rodriguez T.R, Browne F., Doornenbal P., Nishimura S., Nita C.R, Obertelli A., Ando T., Arici T., Authelet G., Baba H., Blazhev A., Bruce A.M, Calvet D., Caroll R.J, Chateau F., Chen S., Chung L.X, Corsi A., Cortes M.L, Delbart A., Dewald M., Ding B., Flavigny F., Franchoo S., Gerl J., Gheller J.M, Giagnon A., Gillibert A., Gorska M., Gottardo A., Kojouharov I., Kurz N., Lapoux V., Lee J., Lettmann M., Linh B.D, Liu J.J, Liu Z., Momiyama S., Moschner K., Motobayashi T., Nagamine S., Nakatsuka N., Niikura M., Nobs C., Olivier L., Patel Z., Paul N., Podolyak Zsolt, Rousse J.Y, Rudigier M., Saito T.Y, Sakurai H., Santamaria C., Schaffner H., Shand C., Stefan I., Steppenbeck D., Taniuchi R., Uesaka T., Vaquero V., Wimmer K., Xu Z. (2020) Identification of an oblate K-isomer of 94Se60 and implications for a ground-state
shape transition between N = 58 - 60
,
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.
Scholes D. T., Cullen D. M., Kondev F. G., Janssens R. V. F., Carpenter M. P., Hartley D. J., Djongolov M. K., Sletten G., Hagemann G., Wheldon C., Walker P. M., Saleem K. Abu, Ahmad I., Balabanski D. L., Chowdhury P., Danchev M., Dracoulis G. D., El-Masri H. M., Goon J., Heinz A., Kaye R. A., Khoo T. L., Lauritsen T., Lister C. J., Moore E. F., Riedinger L. L., Riley M.A., Seweryniak M., Shestakova I., Wiedenhöver I., Zeidan O., Zhang Jing-ye (2004) Highly deformed Bands in 175Hf,Physical Review C 70 (054314)
Scholes D T, Cullen D M, Kondev F G, Janssens R V, Carpenter M P, Hartley D J, Djongolov M K, Sletten G, Hagemann G, Wheldon C, Walker P M, Abu Saleem K, Ahmad I, Balabanski D L, Chowdhury P, Danchev M, Dracoulis G D, El-Masri H M, Goon J, Heinz A, Kaye R A, Khoo T L, Lauritsen T, Lister C J, Moore E F, Riedinger L L, Riley M.A., Seweryniak D, Shestakova I, Wiedenhover I, Zeidan O, Zhang J Y (2004) Highly Deformed Bands in Hf-175,Physical Review C 70 (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.