Caballero-Folch R, Domingo-Pardo C, Agramunt J, Algora A, Ameil F, Ayyad Y, Benlliure J, Bowry M, Calvino F, Cano-Ott D, Cortes G, Davinson T, Dillmann I, Estrade A, Evdokimov A, Faestermann T, Farinon F, Galaviz D, Garcia AR, Geissel H, Gelletly William, Gernhauser R, Gomez-Hornillos MB, Guerrero C, Heil M, Hinke C, Knobel R, Kojouharov I, Kurcewicz J, Kurz N, Litvinov Yu A, Maier L, Marganiec J, Marta M, Martinez T, Montes F, Mukha I, Napoli DR, Nociforo C, Paradela C, Pietri S, Podolyak Zsolt, Prochazka A, Rice S, Riego A, Rubio B, Schaffner H, Scheidenberger Ch, Smith K, Sokol E, Steiger K, Sun B, Tain JL, Takechi M, Testov D, Weick H, Wilson E, Winfield JS, Wood Rachael, Woods PJ, Yeremin A (2017) Beta-decay half-lives and Beta-delayed neutron emission probabilities for several isotopes of
Au, Hg, Tl, Pb and Bi, beyond N=126,PHYSICAL REVIEW C95(6)064322
AMER PHYSICAL SOC
Background: Previous measurements of Beta-delayed neutron emitters comprise around 230 nuclei,
spanning from the 8He up to 150La. Apart from 210Tl, with a minuscule branching ratio of 0.07%,
no other neutron emitter is measured yet beyond A = 150. Therefore new data are needed,
particularly in the heavy mass region around N=126, in order to guide theoretical models and to
understand the formation of the third r-process peak at A 195.
Purpose: To measure both, Beta-decay half-lives and neutron branching ratios of several neutron-rich
Au, Hg, Tl, Pb and Bi isotopes beyond N = 126.
Method: Ions of interest are produced by fragmentation of a 238U beam, selected and identifed
via the GSI-FRS fragment separator. A stack of segmented silicon detectors (SIMBA) is used to
measure ion-implants and -decays. An array of 30 3He tubes embedded in a polyethylene matrix
(BELEN) is used to detect neutrons with high efficiency and selectivity. A self-triggered digital
system is employed to acquire data and to enable time-correlations. The latter are analyzed with
an analytical model and results for the half-lives and neutron-branching ratios are derived using
the binned Maximum-Likelihood method.
Results: Twenty new Beta-decay half-lives are reported for 204
Valencia E, Tain JL, Algora A, Agramunt J, Estevez E, Jordan MD, Rubio B, Rice S, Regan Patrick, Gelletly William, Podolyak Zsolt, Bowry M, Mason P, Farrelly GF, Zakari-Issoufou A, Fallot M, Porta A, Bui VM (2017) Total absorption ³ -ray spectroscopy of the ²-delayed neutron emitters 87Br, 88Br, and 94Rb,Physical Review C: Nuclear Physics024320
American Physical Society
We investigate the decay of 87,88Br and 94Rb using total absorption ³ -ray spectroscopy. These important fission products are ²-delayed neutron emitters. Our data show considerable ²³ intensity, so far unobserved in high-resolution ³ -ray spectroscopy, from states at high excitation energy. We also find significant differences with the ² intensity that can be deduced from existing measurements of the ² spectrum. We evaluate the impact of the present data on reactor decay heat using summation calculations. Although the effect is relatively small it helps to reduce the discrepancy between calculations and integral measurements of the photon component for 235U fission at cooling times in the range 1?100 s. We also use summation calculations to evaluate the impact of present data on reactor antineutrino spectra. We find a significant effect at antineutrino energies in the range of 5 to 9 MeV. In addition, we observe an unexpected strong probability for ³ emission from neutron unbound states populated in the daughter nucleus. The ³ branching is compared to Hauser-Feshbach calculations, which allow one to explain the large value for bromine isotopes as due to nuclear structure. However the branching for 94Rb, although much smaller, hints of the need to increase the radiative width ³ by one order of magnitude. This increase in ³ would lead to a similar increase in the calculated (n,³ ) cross section for this very neutron-rich nucleus with a potential impact on r process abundance calculations.
Rice S, Algora A, Tain J, Valencia E, Agramunt J, Rubio B, Gelletly W, Regan P, Zakari-Issoufou A, Fallot M, Porta A, Rissanen J, Eronen T, Aysto J, Batist L, Bowry M, Bui V, Caballero-Folch R, Cano-Ott D, Elomaa V, Estevez E, Farrelly G, Garcia A, Gomez-Hornillos B, Gorlychev V, Hakala J, Jordan M, Jokinen A, Kolhinen V, Kondev F, Martinez T, Mendoza E, Moore I, Penttila H, Podolyak Z, Reponen M, Sonnenschein V, Sonzogni A, Sarriguren P (2017) Total Absorption Spectroscopy Study of the Beta Decay of 86Br and 91 1 Rb,Physical Review C96014320
American Physical Society
The beta decays of 86Br and 91Rb have been studied using the total absorption spectroscopy
technique. The radioactive nuclei were produced at the IGISOL facility in Jyvaskyla and further
purified using the JYFLTRAP. 86Br and 91Rb are considered high priority contributors to the decay
heat in reactors. In addition 91Rb was used as a normalization point in direct measurements of
mean gamma energies released in the beta decay of fission products by Rudstam et al. assuming
that this decay was well known from high-resolution measurements. Our results shows that both
decays were suffering from the Pandemonium effect and that the results of Rudstam et al. should
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 Physics94(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.
Mason P, Podolyak Z, Marginean N, Regan PH, Stevenson PD, Werner V, Alexander T, Algora A, Alharbi T, Bowry M, Britton R, Bruce A, Bucurescu D, Bunce M, Cata-Danil G, Cata-Danil I, Cooper N, Deleanu D, Delion D, Filipescu D, Gelletly W, Ghita D, Gheorghe I, Glodariu T, Ilie G, Ivanova D, Kisyov S, Lalkovski S, Lica R, Liddick S, Marginean R, Mihai C, Mulholland K, Nita C, Negret A, Pascu S, Rice S, Roberts O, Sava T, Smith J, Soederstroem P, Stroe L, Suliman G, Suvaila R, Toma S, Townsley C, Wilson E, Wood RT, Zhekova M, Zhou C (2013) Half-life of the yrast 2(+) state in W-188: Evolution of deformation and collectivity in neutron-rich tungsten isotopes,PHYSICAL REVIEW C88(4)044301
AMER PHYSICAL SOC
The half-life of the yrast I À = 2+ state in the neutron-rich nucleus 188W has been measured using fast-timing
techniques with the HPGe and LaBr3:Ce array at the National Institute of Physics and Nuclear Engineering,
Bucharest. The resulting value of t1/2 = 0.87(12) ns is equivalent to a reduced transition probability of
1 ) = 85(12) W.u. for this transition. The B(E2; 2+
1 ) is compared to neighboring tungsten
isotopes and nuclei in the Hf, Os, and Pt isotopic chains. Woods-Saxon potential energy surface (PES) calculations
have been performed for nuclei in the tungsten isotopic chain and predict prolate deformed minima with rapidly
increasing ³ softness for 184?192W and an oblate minimum for 194W.
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 B770pp. 83-87
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.
Caballero-Folch1 R, Domingo-Pardo C, Agramunt J, Algora A, Ameil F, Arcones A, Ayyad Y, Benlliure J, Borzov I, Bowry M, Calvino F, Cano-Ott D, Cortes G, Davinson T, Dillmann I, Estrade A, Evdokimov A, Faestermann T, Farinon F, Galaviz D, Garc1a A, Geissel H, Gelletly W, Gernhauser R, Gomez-Hornillos M, Guerrero C, Heil M, Hinke C, Knobel R, Kojouharov I, Kurcewicz J, Kurz N, Litvinov Y, Maier L, Marganiec J, Marketin T, Marta M, Mart1nez T, Mart1nez-Pinedo G, Montes F, Mukha I, Napoli D, Nociforo C, Paradela C, Pietri S, Podolyak Z, Prochazka A, Rice S, Riego A, Rubio B, Schaffner H, Scheidenberger C, Smith K, Sokol E, Steiger K, Sun B, Ta1n J, Takechi M, Testov D, Weick H, Wilson E, Winfield J, Wood RT, Woods P, Yeremin A (2017) First measurement of several ²-delayed neutron emitting isotopes beyond N=126,Physical Review Letters.117(1)012501
American Physical Society
The ²-delayed neutron emission probabilities of neutron rich Hg and Tl nuclei have been measured together with ²-decay half-lives for 20 isotopes of Au, Hg, Tl, Pb and Bi in the mass region N&126. These are the heaviest species where neutron emission has been observed so far. These measurements provide key information to evaluate the performance of nuclear microscopic and phenomenological models in reproducing the high-energy part of the ²-decay strength distribution. This provides important constraints to global theoretical models currently used in r-process nucleosynthesis.
Rice S, Algora A, Tain J, Valencia E, Agramunt J, Rubio B, Gelletly W, Regan PH, Zakari-Issoufou A, Fallot M, Porta A, Rissanen J, Eronen T, Äystö J, Batist L, Bowry M, Bui V, Caballero-Folch R, Cano-Ott D, Elomaa V, Estevez E, Farrelly G, Garcia A, Gomez-Hornillos B, Gorlychev V, Hakala J, Jordan M, Jokinen A, Kolhinen V, Kondev F, Martínez T, Mason P, Mendoza E, Moore I, Penttilä H, Podolyak Z, Reponen M, Sonnenschein V, Sonzogni A, Sarriguren P (2017) Total absorption spectroscopy study of the ² decay of 86Br and 91Rb,Physical Review C96(1)014320
American Physical Society
The beta decays of 86Br and 91Rb have been studied using the total absorption spectroscopy technique. The
radioactive nuclei were produced at the Ion Guide Isotope Separator On-Line facility in Jyväskylä and further
purified using the JYFLTRAP. 86Br and 91Rb are considered to be major contributors to the decay heat in reactors.
In addition, 91Rb was used as a normalization point in direct measurements of mean gamma energies released in
the beta decay of fission products by Rudstam et al. assuming that this decay was well known from high-resolution
measurements. Our results show that both decays were suffering from the Pandemonium effect and that the results
of Rudstam et al. should be renormalized. The relative impact of the studied decays in the prediction of the decay
heat and antineutrino spectrum from reactors has been evaluated
Bucurescu D, Rusu C, Marginean N, Ur C A, de Angelis G, Corradi L, Bazzacco D, Beghini S, Della Vedova F, Duchene G, Farnea E, Faul T, Fioretto E, Gadea A, Gelletly W, Guiot B, Ionescu-Bujor M, Lordachescu A, Landown S D, Lenzi S M, Lunardi S, Mason P, Mihai C, Marginean R, Menegazzo R, Montagnoli G, Napoli D, Podolyak Z, Regan P H, Scarlassara F, Stefanini A M, Suliman G, Szilner S, Trotta M, Valiente-Dobon J J, Zhang Y H (2007) Gamma-ray Spectroscopy of the Neutron-Rich Nuclei Rb-89, Y-92, and Y-93 with Multinucleon Transfer Reactions,Physical Review C76(6)
The positive-parity yrast states in the Rb-89, Y-92, and Y-93 nuclei were studied using gamma-ray spectroscopy with heavy-ion induced reactions. In the multinucleon transfer reactions Pb-208+Zr-90 (590 MeV) and U-238+Se-82 (505 MeV), several gamma-ray transitions were identified in these nuclei by means of coincidences between recoiling ions identified with the PRISMA spectrometer and gamma rays detected with the CLARA gamma-ray array in thin target experiments. Level schemes were subsequently determined from triple-gamma coincidences recorded with the GASP array in a thick target experiment, in the reactions produced by a 470 MeV Se-82 beam with a Os-192 target. The observed level schemes are compared to shell-model calculations.
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 B793pp. 271-275
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 Ã 82) and Z = 82 (for N Ã 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 Ã 8.8 within a 95% confidence limit. This is the most stringent test of the n=0 selection rule to date.