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Author Yokoyama, R. et al; Tain, J.L.; Algora, A.; Agramunt, J.; Domingo-Pardo, C.; Morales, A.I.; Rubio, B.; Tolosa-Delgado, A. doi  openurl
  Title β-delayed neutron emissions from N > 50 gallium isotopes Type Journal Article
  Year 2023 Publication Physical Review C Abbreviated Journal Phys. Rev. C  
  Volume 108 Issue 6 Pages (down) 064307 - 15pp  
  Keywords  
  Abstract beta-delayed gamma-neutron spectroscopy has been performed on the decay of A=84 to 87 gallium isotopes at the RI-beam Factory at the RIKEN Nishina Center using a high-efficiency array of 3He neutron counters (BRIKEN). beta-2n-gamma events were measured in the decays of all of the four isotopes for the first time, which is direct evidence for populating the excited states of two-neutron daughter nuclei. Detailed decay schemes with the gamma branching ratios were obtained for these isotopes, and the neutron emission probabilities (P-xn) were updated from the previous study. Hauser-Feshbach statistical model calculations were performed to understand the experimental branching ratios. We found that the P-1n and P-2n values are sensitive to the nuclear level densities of 1n daughter nuclei and showed that the statistical model reproduced the P-2n/P-1n ratio better when experimental levels plus shell-model level densities fit by the Gilbert-Cameron formula were used as the level-density input. We also showed the neutron and gamma branching ratios are sensitive to the ground-state spin of the parent nucleus. Our statistical model analysis suggested J <= 3 for the unknown ground-state spin of the odd-odd nucleus Ga-86, from the I gamma(4(+)-> 2(+))/I-gamma(2(+)-> 0(+)) ratio of Ga-84 and the P-2n/P-1n ratio. These results show the necessity of detailed understanding of the decay scheme, including data from neutron spectroscopy, in addition to gamma measurements of the multineutron emitters.  
  Address [Yokoyama, R.; Grzywacz, R.; Rasco, B. C.; Brewer, N.; Heideman, J.; King, T. T.; Madurga, M.; Singh, M.] Univ Tennessee, Dept Phys & Astron, Knoxville, TN 37996 USA, Email: yokoyama@cns.s.u-tokyo.ac.jp  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2469-9985 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:001159167500001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 5939  
Permanent link to this record
 
 
Author Blank, B. et al; Agramunt, J.; Algora, A.; Guadilla, V.; Montaner-Piza, A.; Morales, A.I.; Orrigo, S.E.A.; Rubio, B. url  doi
openurl 
  Title New neutron-deficient isotopes from Kr-78 fragmentation Type Journal Article
  Year 2016 Publication Physical Review C Abbreviated Journal Phys. Rev. C  
  Volume 93 Issue 6 Pages (down) 061301 - 5pp  
  Keywords  
  Abstract In an experiment with the RIKEN projectile fragment separator called BigRIPS at the RIKEN Nishina Center, the fragmentation of a Kr-78 beam allowed the observation of new neutron-deficient isotopes at the proton drip line. Clean identification spectra could be produced and Se-63, Kr-67, and Kr-68 were identified for the first time. In addition, Ge-59 was also observed. Three of these isotopes, Ge-59, Se-63, and Kr-67, are potential candidates for ground-state two-proton radioactivity. In addition, the isotopes Ge-58, Se-62, and Kr-66 were also sought but without success. The present experiment also allowed the determination of production cross sections for some of the most exotic isotopes. These measurements confirm the trend already observed that the empirical parametrization of fragmentation cross sections, EPAX, significantly overestimates experimental cross sections in this mass region.  
  Address [Blank, B.; Goigoux, T.; Ascher, P.; Gerbaux, M.; Giovinazzo, J.; Grevy, S.; Nieto, T. Kurtukian; Magron, C.] Univ Bordeaux, Ctr Etud Nucl Bordeaux Gradignan, UMR CNRS 5797, IN2P3, 19 Chemin Solarium,CS 10120, F-33175 Gradignan, France  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2469-9985 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000376997700001 Approved no  
  Is ISI yes International Collaboration no  
  Call Number IFIC @ pastor @ Serial 2701  
Permanent link to this record
 
 
Author IDS Collaboration (Lica, R. et al); Morales, A.I. doi  openurl
  Title beta decay studies of n-rich Cs isotopes with the ISOLDE Decay Station Type Journal Article
  Year 2017 Publication Journal of Physics G Abbreviated Journal J. Phys. G  
  Volume 44 Issue 5 Pages (down) 054002 - 14pp  
  Keywords beta decay; exotic nuclei; nuclear deformation; ISOLDE  
  Abstract Neutron-rich Ba isotopes are expected to exhibit octupolar correlations, reaching their maximum in isotopes around mass A = 146. The odd-A neutron-rich members of this isotopic chain show typical patterns related to non-axially symmetric shapes, which are however less marked compared to even-A ones, pointing to a major contribution from vibrations. In the present paper we present results from a recent study focused on Cs148-150 beta-decay performed at the ISOLDE Decay Station equipped with fast-timing detectors. A detailed analysis of the measured decay half-lives and decay scheme of Ba-149 is presented, giving a first insight in the structure of this neutron-rich nucleus.  
  Address [Lica, R.; Borge, M. J. G.; Madurga, M.; Kurcewicz, J.] CERN, CH-1211 Geneva 23, Switzerland, Email: giovanna.benzoni@mi.infn.it  
  Corporate Author Thesis  
  Publisher Iop Publishing Ltd Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0954-3899 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000398756400002 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 3053  
Permanent link to this record
 
 
Author IDS Collaboration (Lica, R. et al); Morales, A.I. doi  openurl
  Title Fast-timing study of the l-forbidden 1/2(+) -> 3/2(+) M1 transition in Sn-129 Type Journal Article
  Year 2016 Publication Physical Review C Abbreviated Journal Phys. Rev. C  
  Volume 93 Issue 4 Pages (down) 044303 - 7pp  
  Keywords  
  Abstract The levels in Sn-129 populated from the beta(-) decay of In-129 isomers were investigated at the ISOLDE facility of CERN using the newly commissioned ISOLDE Decay Station (IDS). The lowest 1/2(+) state and the 3/2(+) ground state in 129Sn are expected to have configurations dominated by the neutron s(1/2) (l = 0) and d(3/2) (l = 2) single-particle states, respectively. Consequently, these states should be connected by a somewhat slow l-forbidden M1 transition. Using fast-timing spectroscopy we havemeasured the half-life of the 1/2(+) 315.3-keV state, T-1/2 = 19(10) ps, which corresponds to a moderately fast M1 transition. Shell-model calculations using the CD-Bonn effective interaction, with standard effective charges and g factors, predict a 4-ns half-life for this level. We can reconcile the shell-model calculations to the measured T-1/2 value by the renormalization of the M1 effective operator for neutron holes.  
  Address [Lica, R.; Borge, M. J. G.; Kurcewicz, J.; Madurga, M.; Rapisarda, E.] CERN, CH-1211 Geneva 23, Switzerland  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2469-9985 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000373574200003 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 2619  
Permanent link to this record
 
 
Author Pedersen, L.G. et al; Morales, A.I. doi  openurl
  Title First spectroscopic study of odd-odd 78Cu Type Journal Article
  Year 2023 Publication Physical Review C Abbreviated Journal Phys. Rev. C  
  Volume 107 Issue 4 Pages (down) 044301 - 10pp  
  Keywords  
  Abstract Nuclei in the vicinity of 78Ni are important benchmarks for nuclear structure, which can reveal changes in the shell structure far from stability. Spectroscopy of the odd-odd isotope 78Cu was performed for the first time in an experiment with the EURICA setup at the Radioactive Isotope Beam Factory at RIKEN Nishina Center. Excited states in the neutron-rich isotope were populated following the beta decay of 78Ni produced by in-flight fission and and separated by the BigRIPS separator. A level scheme based on the analysis of γ−γ coincidences is presented. Tentative spin and parity assignments were made when possible based on the β-decay feeding intensities and γ-decay properties of the excited states. Time correlations between β and γ decay show clear indications of an isomeric state with a half-life of 3.8(4) ms. Large-scale Monte Carlo shell-model calculations were performed using the A3DA-m interaction and a valence space comprising the full fp shell and the 1g9/2 and 2d5/2 orbitals for both protons and neutrons. The comparison of the experimental results with the shell-model calculations allows interpreting the excited states in terms of spin multiplets arising from the proton-neutron interaction. The results provide further insight into the evolution of the proton single-particle orbitals as a function of neutron number, and quantitative information about the proton-neutron interaction outside the doubly magic 78Ni core.  
  Address [Pedersen, L. G.; Sahin, E.; Gorgen, A.; Garrote, F. L. Bello; Modamio, V.] Univ Oslo, Dept Phys, NO-0316 Oslo, Norway, Email: l.g.pedersen@fys.uio.no;  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2469-9985 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000998180300003 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 5572  
Permanent link to this record
 
 
Author Bello Garrote, F.L. et al; Morales, A.I. doi  openurl
  Title beta decay of Ni-75 and the systematics of the low-lying level structure of neutron-rich odd-A Cu isotopes Type Journal Article
  Year 2020 Publication Physical Review C Abbreviated Journal Phys. Rev. C  
  Volume 102 Issue 3 Pages (down) 034314 - 13pp  
  Keywords  
  Abstract Background: Detailed spectroscopy of neutron-rich odd-A Cu isotopes is of great importance for studying the shell evolution in the region of Ni-78. While there is experimental information on excited states in 69-73,77,79CU isotopes, the information concerning Cu-75 is very limited. Purpose: Experimentally observed single-particle, core-coupling, and proton-hole intruder states in Cu-75, will complete the systematics of these states in the chain of isotopes. Method: Excited states in Cu-75 were populated in the beta decay of Ni-75 isotopes. The Ni nuclei were produced by the in-flight fission of U-238 projectiles, and were separated, identified, and implanted in a highly segmented Si detector array for the detection of the beta-decay electrons. The beta-delayed gamma rays were detected in a HPGe cluster array. Monte Carlo shell model calculations were performed using the A3DA interaction built on the pf g(9/2)d(5/2) model space for both neutrons and protons. Results: A level scheme of Cu-75 was built up to approximate to 4 MeV by performing a gamma-gamma coincidence analysis. The excited states below 2 MeV were interpreted based on the systematics of neutron-rich odd-A Cu isotopes and the results of the shell model calculations. Conclusions: The evolution of the single-particle, core-coupling, and proton-hole intruder states in the chain of neutron-rich odd-A Cu isotopes is discussed in the present work, in connection with the newly observed level structure of Cu-75.  
  Address [Garrote, F. L. Bello; Sahin, E.; Gorgen, A.; Modamio, V] Univ Oslo, Dept Phys, N-0316 Oslo, Norway, Email: eda.sahin@fys.uio.no  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0556-2813 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000572427100002 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 4540  
Permanent link to this record
 
 
Author Yokoyama, R. et al; Tain, J.L.; Algora, A.; Agramunt, J.; Domingo-Pardo, C.; Morales, A.I.; Rubio, B.; Tolosa-Delgado, A. doi  openurl
  Title Strong one-neutron emission from two-neutron unbound states in beta decays of the r-process nuclei Ga-86,Ga-87 Type Journal Article
  Year 2019 Publication Physical Review C Abbreviated Journal Phys. Rev. C  
  Volume 100 Issue 3 Pages (down) 031302 - 6pp  
  Keywords  
  Abstract beta-delayed one-neutron and two-neutron branching ratios (P-1n and P-2n) have been measured in the decay of A = 84 to 87 Ga isotopes at the Radioactive-Isotope Beam Factory (RIBF) at the RIKEN Nishina Center using a high-efficiency array of He-3 neutron counters (BRIKEN). Two-neutron emission was observed in the decay of Ga-84,Ga-85,Ga-87 for the first time and the branching ratios were measured to be P-2n = 1.6(2)%, 1.3(2)%, and 10.2(28)(stat)(5)(sys)%, respectively. One-neutron branching ratio of Ga-87 (P-1n = 81(9)(stat)(8)(sys)%) and half-life of 29(4) ms were measured for the first time. The branching ratios of Ga-86 were also measured to be P-1n = 74(2)(stat)(8)(sys)% and 16.2(9)(stat)(6)(sys)% with better precision than a previous study. The observation that P-1n > P-2n for both Ga-86,Ga-87 was unexpected and is interpreted as a signature of dominating one-neutron emission from the two-neutron unbound excited states in Ge-86,Ge-87. In order to interpret the experimental results, shell-model and Hauser-Feshbach statistical model calculations of delayed particle and gamma-ray emission probabilities were performed. This model framework reproduces the experimental results. The shell model alone predicts P-2n significantly larger than P-1n for the Ga-87 decay, and it is necessary to invoke a statistical description to successfully explain the observation that P-1n > P-2n. Our new results demonstrate the relevance and importance of a statistical description of neutron emission for the prediction of the decay properties of multineutron emitters and that it must be included in the r-process modeling.  
  Address [Yokoyama, R.; Grzywacz, R.; Rasco, B. C.; Brewer, N.; Heideman, J.; King, T. T.; Madurga, M.; Singh, M.] Univ Tennessee, Dept Phys & Astron, Knoxville, TN 37996 USA, Email: ryokoyam@utk.edu  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2469-9985 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000486641000001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 4145  
Permanent link to this record
 
 
Author IDS Collaboration (Heideman, J. et al); Algora, A.; Morales, A.I. doi  openurl
  Title Evidence of nonstatistical neutron emission following beta decay near doubly magic Sn-132 Type Journal Article
  Year 2023 Publication Physical Review C Abbreviated Journal Phys. Rev. C  
  Volume 108 Issue 2 Pages (down) 024311 - 9pp  
  Keywords  
  Abstract Models of the beta-delayed neutron emission (beta n) assume that neutrons are emitted statistically via an intermediate compound nucleus post beta decay. Evidence to the contrary was found in an In-134 beta-decay experiment carried out at ISOLDE CERN. Neutron emission probabilities from the unbound states in Sn-134 to known low-lying, single-particle states in Sn-133 were measured. The neutron energies were determined using the time-of-flight technique, and the subsequent decay of excited states in Sn-133 was studied using gamma-ray detectors. Individual beta n probabilities were determined by correlating the relative intensities and energies of neutrons and gamma rays. The experimental data disagree with the predictions of representative statistical models which are based upon the compound nucleus postulate. Our results suggest that violation of the compound nucleus assumption may occur in beta-delayed neutron emission. This impacts the neutron-emission probabilities and other properties of nuclei participating in the r-process. A model of neutron emission, which links the observed neutron emission probabilities to nuclear shell effects, is proposed.  
  Address [Heideman, J.; Grzywacz, R.; Xu, Z. Y.; Madurga, M.; Halverson, C.; King, T. T.; Singh, M.; Yokoyama, R.] Univ Tennessee, Dept Phys & Astron, Knoxville, TN 37996 USA  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2469-9985 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:001053419100001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 5620  
Permanent link to this record
 
 
Author IDS Collaboration (Lica, R. et al); Morales, A.I. doi  openurl
  Title Evolution of deformation in neutron-rich Ba isotopes up to A=150 Type Journal Article
  Year 2018 Publication Physical Review C Abbreviated Journal Phys. Rev. C  
  Volume 97 Issue 2 Pages (down) 024305 - 12pp  
  Keywords  
  Abstract The occurrence of octupolar shapes in the Ba isotopic chain was recently established experimentally up to N = 90. To further extend the systematics, the evolution of shapes in the most neutron-rich members of the Z = 56 isotopic chain accessible at present, Ba-148,Ba-150, has been studied via beta decay at the ISOLDE Decay Station. This paper reports on the first measurement of the positive-and negative-parity low-spin excited states of 150Ba and presents an extension of the beta-decay scheme of Cs-148. Employing the fast timing technique, half-lives for the 2(1)(+) level in both nuclei have been determined, resulting in T-1/2 = 1.51(1) ns for Ba-148 and T-1/2 = 3.4(2) ns for Ba-150. The systematics of low-spin states, together with the experimental determination of the B(E2 : 2(+) -> 0(+)) transition probabilities, indicate an increasing collectivity in Ba148-150, towards prolate deformed shapes. The experimental data are compared to symmetry conserving configuration mixing (SCCM) calculations, confirming an evolution of increasingly quadrupole deformed shapes with a definite octupolar character.  
  Address [Lica, R.; Borge, M. J. G.; Madurga, M.; Kurcewicz, J.; Rapisarda, E.] CERN, ISOLDE EP, CH-1211 Geneva 23, Switzerland, Email: giovanna.benzoni@mi.infn.it  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2469-9985 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000424089400005 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 3471  
Permanent link to this record
 
 
Author Morales, A.I.; Algora, A.; Molina, F.; Rubio, B. doi  openurl
  Title Half-Life Systematics across the N=126 Shell Closure: Role of First-Forbidden Transitions in the beta Decay of Heavy Neutron-Rich Nuclei Type Journal Article
  Year 2014 Publication Physical Review Letters Abbreviated Journal Phys. Rev. Lett.  
  Volume 113 Issue 2 Pages (down) 022702 - 5pp  
  Keywords  
  Abstract This Letter reports on a systematic study of beta-decay half-lives of neutron-rich nuclei around doubly magic Pb-208. The lifetimes of the 126-neutron shell isotone Pt-204 and the neighboring Ir200-202, Pt-203, Au-204 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 beta strength reveal significant deviations for most of the nuclei with N < 126. In contrast, theories including a fully microscopic treatment of allowed and first-forbidden transitions reproduce more satisfactorily the trend in the measured half-lives for the nuclei in this region, where the r-process pathway passes through during beta decay back to stability.  
  Address [Morales, A. I.; Benlliure, J.; Kurtukian-Nieto, T.; Verma, S.; Casarejos, E.; Alvarez-Pol, H.; Estevez-Aguado, M. E.] Univ Santiago de Compostela, E-15782 Santiago De Compostela, Spain, Email: anaisabel.morales@mi.infn.it  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0031-9007 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000341315100007 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 1913  
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