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1. Three-quasiparticle isomers in odd-even Pm159,161 : Calling for modified spin-orbit interaction for the neutron-rich region

Author

Tetsuro Komatsubara, Toshiyuki Kubo, Long-Jun Wang, I. Kojouharov, H. Baba, Y. F. Fang, Giuseppe Lorusso, Jan Taprogge, F. L. Bello Garrote, I. Nishizuka, Hirofumi Watanabe, Masafumi Matsushita, Shunji Nishimura, S. Inabe, A. Gottardo, H. Schaffner, Z. H. Li, Motoki Kobayashi, L. Sinclair, F. Browne, G. Benzoni, Nori Aoi, M. Tanaka, D. Kameda, E. Sahin, Gary Simpson, Cui Juan Lv, Zhengyu Xu, Toshiyuki Sumikama, Guillaume Gey, Shintaro Go, Chang-Bum Moon, P. Doornenbal, Hiroyuki Takeda, Zena Patel, T. Isobe, Hiroshi Suzuki, Atsuko Odahara, R. Yokoyama, N. Kurz, Naoki Fukuda, Stephen Rice, Zs. Vajta, Yang Sun, Hiroyoshi Sakurai, Shin'ichiro Michimasa, P. A. Söderström, Ayumi Yagi, Eiji Ideguchi, Yan Xin Liu, István Kuti, K. Kobayashi, R. Daido, Jinguang Wu, and Hiroki Nishibata

Subjects
Physics, Isotope, 010308 nuclear & particles physics, Fission, Spin–orbit interaction, 01 natural sciences, Ion, 0103 physical sciences, Quasiparticle, Neutron, Atomic physics, 010306 general physics, Spectroscopy, Nucleon
Abstract

Neutron-rich Pm ( Z = 61 ) isotopes were studied by delayed γ -ray spectroscopy at RIBF, RIKEN Nishina Center using the in-flight fission of a 345 MeV/nucleon U 238 beam. A cluster-type Ge detector array, EURICA, was used to measure the delayed γ rays from stopped ions. Isomeric γ decays were observed in Pm 159 and Pm 161 with half-lives of 4.97(12) μ s and 0.79(4) μ s , respectively. Level schemes for Pm 159 and Pm 161 were constructed in this study. The isomeric states of Pm 159 and Pm 161 could be interpreted as two quasiparticle excitations of neutrons with the configurations of ν ( 7 / 2 [ 633 ] ⊗ 5 / 2 [ 523 ] ) and ν ( 7 / 2 [ 633 ] ⊗ 1 / 2 [ 521 ] ) , respectively. They are analogous to the isomers that have been observed systematically in other even-mass N = 98 and N = 100 isotones in this region. A projected shell model calculation was performed and it reproduced the order of three-quasiparticle states only if new Nilsson parameters with an N -dependent spin-orbit interaction were used. This work demonstrates that the strength of spin-orbit interactions in standard Nilsson parameters needs to be modified to study the properties of neutron-rich rare-earth nuclei around A = 165 , and provides new evidence supporting the existence of the deformed N = 98 subshell gap in odd-mass nuclei for the first time.

Published
2021

2. Observation of new neutron-rich isotopes in the vicinity of Zr 110

Author

Takashi Kubo, Zena Patel, H. Takeda, Eiji Ideguchi, F. Didierjean, G. Lorusso, Zhengyu Xu, T. Isobe, Raymond J. Carroll, Jan Taprogge, Y. F. Fang, Naoki Fukuda, Zs. Podolyák, Kenichi Yoshida, R. Daido, O. Wieland, Toshiyuki Sumikama, R. Lozeva, H. Baba, Z. H. Li, F. Browne, Ayumi Yagi, Hiroyoshi Sakurai, D. Kameda, Shin-Ichiro Nishimura, Guillaume Gey, Hiroshi Suzuki, P. Doornenbal, S. Lalkovski, P. H. Regan, Atsuko Odahara, Stephen Rice, L. Sinclair, Momoko Tanaka, I. Nishizuka, Nobuyuki Chiga, Gary Simpson, Y. Shimizu, Alison Bruce, P. A. Söderström, Naohito Inabe, Hirofumi Watanabe, Hiroki Nishibata, Oliver J. Roberts, V. Werner, Jin Wu, RIKEN Nishina Center for Accelerator-Based Science, University of Tokyo, Japan Society for the Promotion of Science, National Research Foundation of Korea, Science and Technology Facilities Council (UK), Department of Energy (US), Federal Ministry of Education and Research (Germany), Ministerio de Ciencia e Innovación (España), Department for Business, Energy and Industrial Strategy (UK), National Measurement System (UK), Institut Pluridisciplinaire Hubert Curien (IPHC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Institut Laue-Langevin (ILL), ILL, Laboratoire de Physique des 2 Infinis Irène Joliot-Curie (IJCLab), and Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, Nuclear reaction, Isotope, Spectrometer, 010308 nuclear & particles physics, Fission, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, 7. Clean energy, Nuclear physics, Time of flight, 0103 physical sciences, Nuclear Reactions, Physics::Accelerator Physics, Neutron, 010306 general physics, Nucleon, Nuclear Experiment, Beam (structure)
Abstract

5 pags., 3 figs., 2 tabs., Neutron-rich radioactive isotope (RI) beams in the vicinity of Zr110 were produced using the in-flight fission of a 345-MeV/nucleon U238 beam at the RIKEN Radioactive Isotope Beam Factory. The RI beams were separated in flight by the large-acceptance two-stage fragment separator BigRIPS. Isotopes were clearly identified in a low-background particle-identification plot, which was obtained from the measurements of time of flight, magnetic rigidity, and energy loss using beam-line detectors placed in the BigRIPS separator and the ZeroDegree spectrometer. Nine new isotopes, Br101, Kr102, Rb105,106, Sr108, Y110,111, Zr114, and Nb117, are reported for the first time, with their measured production cross sections compared with the extrapolations of lighter isotopes down to the femtobarn regime., This experiment was carried out at the RIBF operated by the RIKEN Nishina Center, and the Center for Nuclear Study, the University of Tokyo. The authors acknowledge the RIBF accelerator staffs for their efforts in delivering an intense 238U beam. This work was supported by JSPS KAKENHI Grants No. 2301752, No. 24740188, No. 25247045, No. 26800117, and No. 16K17680, NRF Grant No. 2016K1A3A7A09005575, STFC Grants No. ST/J000132/1, No. ST/J000051/1, No. ST/K502431/1, No. ST/L005743/1, No. ST/P003885/1, No. ST/P003982/1, and No. ST/P005314/1, DOE Grant No. DE-FG02-91ER 40609, BMBF Grant No. 05P19RDFN1, and Spanish Ministerio de Ciencia e Innovación under Contracts No. FPA2009- 13377-C02 and No. FPA2011-29854-C04. P.H.R. and G.L. acknowledge additional support from the UK Department for Business, Energy and Industrial Strategy (BEIS) via funding for the UK National Measurement System. P.-A.S. was financed by the RIKEN Foreign Postdoctoral Researcher Program

Published
2021

3. Nuclear structure of Te isotopes beyond neutron magic number N=82

Author

Y. Shimizu, Giuseppe Lorusso, F. L. Bello Garrote, I. Nishizuka, T. Isobe, Chang-Bum Moon, A. Jungclaus, S. Morimoto, Naohito Inabe, Y. F. Fang, Zs. Vajta, Hiroshi Watanabe, Roman Gernhäuser, C. S. Lee, Hiroshi Suzuki, Toshiyuki Sumikama, Shunji Nishimura, H. Schaffner, M. Si, D. Mücher, Hiroyuki Takeda, Daichi Murai, F. Browne, Hiroki Nishibata, Atsuko Odahara, Anna Wendt, J. M. Daugas, Guillaume Gey, L. Sinclair, Hiroyoshi Sakurai, I. Kojouharov, P. A. Söderström, Ayumi Yagi, S. Bönig, Byung-Sik Hong, Gary Simpson, R. Orlandi, Younghun Kwon, A. Montaner-Pizá, Stephen Rice, D. Kameda, J. M. Keatings, Eiji Ideguchi, Rin Yokoyama, K. Moschner, A. Gargano, S. Ilieva, Jan Taprogge, K. Yoshinaga, Hyo Soon Jung, B. Moon, R. Daido, Zena Patel, D. S. Ahn, P. Doornenbal, Jin Wu, H. Naïdja, K. Tshoo, N. Kurz, K. Steiger, Naoki Fukuda, Megumi Niikura, P. Lee, F. Didierjean, Tetsuro Komatsubara, Toshiyuki Kubo, T. Kröll, R. Lozeva, F. Drouet, Z. H. Li, H. Baba, Zhengyu Xu, T. Ishigaki, RIKEN Nishina Center for Accelerator-Based Science, University of Tokyo, Institute for Basic Science (South Korea), National Research Foundation of Korea, Ministerio de Economía y Competitividad (España), Japan Society for the Promotion of Science, National Research, Development and Innovation Office (Hungary), Institut Pluridisciplinaire Hubert Curien (IPHC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique des 2 Infinis Irène Joliot-Curie (IJCLab), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Institut Laue-Langevin (ILL), ILL, Direction des Applications Militaires (DAM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), and Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, Isotope, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], 010308 nuclear & particles physics, Nuclear Theory, Nuclear structure, Nuclear Structure, 7. Clean energy, 01 natural sciences, Nuclear physics, Fragmentation (mass spectrometry), Excited state, 0103 physical sciences, Neutron, 010306 general physics, Nucleon, Nuclear Experiment, Beam (structure), Magic number (physics)
Abstract

15 pags., 10 figs., 4 tabs., Newly observed decay schemes of the nuclei Sb137 and Sb138 are reported. The neutron-rich Sb isotopes were produced by the in-flight fragmentation of a U238 primary beam with an energy of 345 MeV/nucleon. Several new excited states of Te137 with tentatively assigned spin-parities of (5/2-), (9/2-), and (7/2) have been established which play an important role in the evolution of neutron levels beyond N=82. The study of the ß decay of Sb138 led to a considerable extension of the level scheme of Te138 including the identification of several nonyrast states. The structure of Te137 and Te138 is discussed on the basis of large-scale shell-model calculations performed using two different effective interactions., This work was carried out at the RIBF operated by RIKEN Nishina Center and CNS, University of Tokyo. Part of the WAS3ABi was supported by the Rare Isotope Science Project (RISP) of the Institute for Basic Science (IBS) funded by the Ministry of Science, ICT and Future Planning (MSIP) and National Research Foundation (NRF) of the Republic of Korea (Grant No. 2013M7A1A1075764). This research was supported by NRF of the Republic of Korea (Grants No. 2019R1A6A3A03031564 and No. 2018R1A5A1025563), IBS of the Republic of Korea (Grants No. IBS-R031-D1 and No. IBS-R031-Y1), the Spanish Ministerio de Economía y Competitividad (Grant No. FPA2017-84756-C4-2-P), and JSPS KAKENHI of Japan (Grant No. 25247045). The support from FR-JP LIA is also acknowledged. C.S.L. acknowledges the support from NRF of the Republic of Korea (Grants No. 2017M2A2A6A02071071 and No. 2016R1D1A1A09917463). Z.V. acknowledges the supports from the National Research, Development and Innovation Fund of Hungary, financed under the K18 funding scheme with Project No. K128947 and by the European Regional Development Fund (Grant No. GINOP-2.3.3-15-2016- 00034), as well as by the National Research, Development and Innovation Office NKFIH (Grant No. PD 124717).

Published
2021

4. Impact of shell evolution on Gamow-Teller β decay from a high-spin long-lived isomer in 127Ag

Author

Hirofumi Watanabe, Young-Ki Kim, Chang-Bum Moon, A. Jungclaus, Younghun Kwon, A. Montaner-Pizá, Anna Wendt, Shunji Nishimura, Hiroshi Suzuki, F. Naqvi, Megumi Niikura, K. Yoshinaga, Ayumi Yagi, Z. H. Li, G. J. Lane, Giuseppe Lorusso, Hyo Soon Jung, F. Browne, D. Kameda, Hiroki Nishibata, Gary Simpson, P. Doornenbal, K. Steiger, Guillaume Gey, T. Isobe, F. G. Kondev, I. Kojouharov, Toshiyuki Sumikama, Zs. Vajta, R. Orlandi, Toshiyuki Kubo, Hiroyuki Takeda, Naohito Inabe, Atsuko Odahara, Jin Wu, G. D. Kim, H.K. Wang, Jan Taprogge, Roman Gernhäuser, G. Benzoni, F. C. L. Crespi, H. Schaffner, K. Moschner, H. Baba, Naoki Fukuda, Zs. Podolyák, K. Y. Chae, N. Kurz, Zhengyu Xu, P. A. Söderström, Daiki Nishimura, Hiroyoshi Sakurai, Zena Patel, Cenxi Yuan, Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Ministry of Science and Technology (South Korea), Department of Energy (US), National Research Foundation of Korea, Ministerio de Economía y Competitividad (España), Federal Ministry of Education and Research (Germany), Japan Society for the Promotion of Science, National Natural Science Foundation of China, National Key Research and Development Program (China), and Science and Technology Facilities Council (UK)

Subjects
Nuclear and High Energy Physics, QC1-999, Nuclear Theory, Shell (structure), Shell evolution, Ag, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, 7. Clean energy, decay, Gamow-Teller, 0103 physical sciences, medicine, Physics::Atomic and Molecular Clusters, Neutron, 010306 general physics, Spin (physics), Physics, 010308 nuclear & particles physics, Gamow-Teller β decay, Parity (physics), 127Ag, ddc, Isomer, medicine.anatomical_structure, 13. Climate action, Atomic nucleus, 127 Ag, Atomic physics, Radioactive isotope beam, Nucleus, Excitation
Abstract

6 pags., 4 figs., 2 tabs., The change of the shell structure in atomic nuclei, so-called “nuclear shell evolution”, occurs due to changes of major configurations through particle-hole excitations inside one nucleus, as well as due to variation of the number of constituent protons or neutrons. We have investigated how the shell evolution affects Gamow-Teller (GT) transitions that dominate the β decay in the region below 132Sn using the newly obtained experimental data on a long-lived isomer in 127Ag. The T1/2=67.5(9) ms isomer has been identified with a spin and parity of (27/2+) at an excitation energy of 1942−20+14 keV, and found to decay via an internal transition of an E3 character, which competes with the dominant β-decay branches towards the high-spin states in 127Cd. The underlying mechanism of a strong GT transition from the 127Ag isomer is discussed in terms of configuration-dependent optimization of the effective single-particle energies in the framework of a shell-model approach., Part of the WAS3ABi was supported by the Rare Isotope Science Project which is funded by MSIP and NRF of Korea. This work was supported by the Priority Centers Research Program in Korea (2009-0093817), OTKA contract number K100835, the U.S. DOE, Office of Nuclear Physics (Contract No. DE-AC02-06CH11357), NRF2016R1A5A1013277 and NRF-2013M7A1A1075764, the Spanish Ministerio de Economía y Competitividad under contract FPA2017- 84756-C4-2-P, the European Commission through the Marie Curie Actions call FP7-PEOPLE-2011-IEF (Contract No. 300096), German BMBF under Contract No: 05P12PKFNE, JSPS KAKENHI Grant No. 24740188 and 25247045, the National Natural Science Foundation of China (Nos. 11505302, 11575112, 11775316), the National Key Program for S&T Research and Development (No. 2016YFA0400501), and STFC (UK).

Published
2021

5. Evolution of proton single-particle states in neutron-rich Sb isotopes beyond N=82

Author

A. Jungclaus, Y. Shimizu, H. Schaffner, Hiroshi Suzuki, T. Isobe, I. Kojouharov, Hiroshi Watanabe, G. D. Kim, J. M. Daugas, Hiroki Nishibata, Jinguang Wu, Hiroyoshi Sakurai, D. Kameda, Toshiyuki Kubo, Shunji Nishimura, A. Gargano, Gary Simpson, P. Doornenbal, Atsuko Odahara, H. Baba, K. Moschner, Roman Gernhäuser, F. Browne, Z. H. Li, Z Vajta, Ayumi Yagi, Naohito Inabe, S. Bönig, Marcus Scheck, Guillaume Gey, T. Kröll, K. Yoshinaga, S. Ilieva, N. Kurz, Jan Taprogge, Naoki Fukuda, K. Steiger, Hyo Soon Jung, R. Orlandi, J. M. Keatings, Young-Ki Kim, P. A. Söderström, Younghun Kwon, A. Montaner-Pizá, Giuseppe Lorusso, Anna Wendt, D. Mücher, Toshiyuki Sumikama, Hiroyuki Takeda, H. Naïdja, Zhengyu Xu, Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Institut Laue-Langevin (ILL), Direction des Applications Militaires (DAM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), ILL, RIKEN Nishina Center for Accelerator-Based Science, Ministerio de Economía y Competitividad (España), Science and Technology Facilities Council (UK), and National Research, Development and Innovation Office (Hungary)

Subjects
Physics, Proton, Isotope, 010308 nuclear & particles physics, Astrophysics::High Energy Astrophysical Phenomena, Nuclear structure, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Structure, 7. Clean energy, 01 natural sciences, Beta decay, Nuclear physics, Neutron number, Excited state, 0103 physical sciences, Neutron, Nuclear Experiment, 010306 general physics, Excitation
Abstract

11 pags., 8 figs., 2 tabs., The β decay of the semimagic Sn isotopes Sn136,137,138 has been studied at the Radioactive Isotope Beam Factory at the RIKEN Nishina Center. The first experimental information on excited states was obtained for Sb137 while, in the case of Sb136, the established excitation scheme could be extended by ten previously unidentified levels. In the decay of the most-neutron-rich isotope Sn138, two γ rays were observed for the first time. The new experimental results, in combination with state-of-the-art shell-model calculations, provide the first information with respect to the evolution of the 0g7/2 and 1d5/2 proton single-particle states with increasing neutron number beyond N=84., We thank the staff of the RIKEN Nishina Center accelerator complex for providing high-intensity beams to the experiment. This work was supported by the Spanish Ministerio de Ciencia e Innovación under contracts FPA2014-57196-C5-4-P and FPA2017-84756-C4-2-P and the UK Science and Technology Facilities Council under Grant No. ST/P005101/1. Zs.V. was supported by the European Regional Development Fund (Contract No. GINOP-2.3.3- 15-2016-00034), the National Research Development and Innovation Fund of Hungary (Grant No. K128947), and by RIKEN as short-term International Program Associate.

Published
2020

6. New isomers in $^{125}$Pd$_{79}$ and $^{127}$Pd$_{81}$: Competing proton and neutron excitations in neutron-rich palladium nuclides towards the $N = 82$ shell closure

Author

Gary Simpson, Naohito Inabe, Hirofumi Watanabe, G. D. Kim, Chang-Bum Moon, A. Jungclaus, Ayumi Yagi, Megumi Niikura, Toshiyuki Sumikama, T. Isobe, Hiroshi Suzuki, Toshiyuki Kubo, Hyo Soon Jung, Shunji Nishimura, Hiroyuki Takeda, Atsuko Odahara, Jan Taprogge, G. Benzoni, F. C. L. Crespi, K. Yoshinaga, H. Baba, G. J. Lane, Giuseppe Lorusso, F. Browne, F. G. Kondev, I. Kojouharov, Guillaume Gey, H.K. Wang, Roman Gernhäuser, R. Orlandi, Z. H. Li, Hiroki Nishibata, Anna Wendt, H. Schaffner, Zs. Vajta, Zhengyu Xu, Young-Ki Kim, Younghun Kwon, A. Montaner-Pizá, Hiroyoshi Sakurai, Zena Patel, Daiki Nishimura, Yang Sun, Jin Wu, K. Moschner, K. Steiger, Naoki Fukuda, D. Kameda, Zs. Podolyák, P. A. Söderström, P. Doornenbal, F. Naqvi, K. Y. Chae, N. Kurz, Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)

Subjects
Physics, Nuclear and High Energy Physics, Isotope, Proton, 010308 nuclear & particles physics, Fission, Astrophysics::High Energy Astrophysical Phenomena, Nuclear Theory, chemistry.chemical_element, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, lcsh:QC1-999, chemistry, Nucleosynthesis, Excited state, 0103 physical sciences, Neutron, Nuclide, Atomic physics, 010306 general physics, Nuclear Experiment, lcsh:Physics, Palladium
Abstract

The neutron-rich isotopes of palladium have attracted considerable interest in terms of the evolution of the N=82 neutron shell closure and its influence on the r-process nucleosynthesis. In this Letter, we present the first spectroscopic information on the excited states in Pd and Pd studied using the EURICA γ-ray spectrometer, following production via in-flight fission of a high-intensity U beam at the RIBF facility. New isomeric states with half-lives of 144(4) ns and 39(6) μs have been assigned spins and parities of (23/2 ) and (19/2 ) in Pd and Pd, respectively. The observed level properties are compared to a shell-model calculation, suggesting the competition between proton excitations and neutron excitations in the proton-hole and neutron-hole systems in the vicinity of the doubly magic nucleus Sn.

Published
2019

7. Observation of new neutron-rich Mn, Fe, Co, Ni, and Cu isotopes in the vicinity of $^{78}$Ni

Author

Naohito Inabe, Shin-Ichiro Nishimura, Takashi Kubo, Atsuko Odahara, H. S. Jung, Jan Taprogge, P. Morfouace, I. Matea, Ryo Taniuchi, H. Takeda, Hiroki Nishibata, P. A. Söderström, G. I. Stefan, K. Matsui, Toshiyuki Sumikama, Hiroyoshi Sakurai, D. Mengoni, K. Yoshinaga, Zhengyu Xu, Naoki Fukuda, Hiroshi Suzuki, Z. H. Li, Zs. Vajta, F. Browne, Guillaume Gey, Megumi Niikura, S. Franchoo, T. Isobe, V. Werner, P. R. John, Ayumi Yagi, Giuseppe Lorusso, D. R. Napoli, H. Baba, D. Kameda, E. Sahin, P. Doornenbal, Daisuke Suzuki, Jin Wu, Hirofumi Watanabe, Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Institut Laue-Langevin (ILL), ILL, Japan Society for the Promotion of Science, Ministerio de Ciencia e Innovación (España), Hungarian Scientific Research Fund, National Research Foundation of Korea, Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)

Subjects
Physics, Nuclear and High Energy Physics, Isotope, 010308 nuclear & particles physics, Fission, Qualitative evidence, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 7. Clean energy, 01 natural sciences, Weak binding, 0103 physical sciences, Neutron, Production (computer science), Atomic physics, 010306 general physics, Nuclear Experiment, Beam (structure), Energy (signal processing)
Abstract

5 pags., 3 figs., 2 tabs., Neutron-rich nuclei in the vicinity of Ni78 were produced using a U238 beam at the RIKEN Radioactive Isotope Beam Factory. The particle-identification plot for the in-flight fission fragments highlights the first observation of eight new isotopes: Mn73, Fe76, Co77,78, Ni80,81,82, and Cu83. Although the β-decay half-lives of Co77 and Ni80 were recently reported by Xu [Phys. Rev. Lett. 113, 032505 (2014)]PRLTAO0031-900710.1103/PhysRevLett.113.032505 using data from the same experiment, the current work provides the first direct, quantitative evidence for the existence of these isotopes. The experimental production cross sections are reproduced in a satisfactory manner by theoretical predictions. An odd-even staggering of the cross sections was observed, and the effect appears to become more pronounced for the most exotic nuclei that were investigated. The staggering effect was interpreted as an increase of the neutron-evaporation probability for odd-N isotopes, owing to the decrease of the neutron-separation energy, Sn. The predicted cross section for Ni80 is significantly overestimated, which may be related to a weak binding of the neutron pair above the N=50 shell closure., This work was supported by JSPS KAKENHI (25247045, 25800130), the Spanish Ministerio de Ciencia e Innovación under Contracts No. FPA2009-13377-C02 and No. FPA2011- 29854-C04, OTKA Contract No. K-100835, U.S. DOE Contract No. DE-FG02-91ER40609, and the Priority Centers Research Program in Korea (2009-0093817).

Published
2017

8. First observation ofγrays emitted from excited states south-east ofSn132: Theπg9/2−1⊗νf7/2multiplet ofIn83132

Author

H. Baba, Ayumi Yagi, S. Bönig, Young-Ki Kim, Toshiyuki Sumikama, Younghun Kwon, A. Montaner-Pizá, Shunji Nishimura, Hiroyuki Takeda, H. S. Jung, Z. H. Li, A. Jungclaus, Giuseppe Lorusso, Jan Taprogge, Roman Gernhäuser, D. Mücher, Hiroki Nishibata, A. Gargano, D. Kameda, Z Vajta, Hiroshi Suzuki, A. Gadea, F. Drouet, G. D. Kim, Hiroyoshi Sakurai, Anna Wendt, Gary Simpson, J. M. Daugas, T. Isobe, K. Yoshinaga, Jin Wu, P. Doornenbal, Hiroshi Watanabe, K. Moschner, R. Orlandi, S. Ilieva, I. Kojouharov, Zhengyu Xu, F. Browne, L. Coraggio, Guillaume Gey, K. Steiger, Nunzio Itaco, Toshiyuki Kubo, Naoki Fukuda, Y. Shimizu, H. Grawe, N. Kurz, Naohito Inabe, P. A. Söderström, H. Schaffner, Atsuko Odahara, and T. Kröll

Subjects
Physics, Radionuclide, 010308 nuclear & particles physics, Fission, Projectile, Neutron emission, 01 natural sciences, Nuclear physics, Excited state, 0103 physical sciences, Neutron, Atomic physics, Nuclear Experiment, 010306 general physics, Multiplet, Scaling
Abstract

For the first time, the γ decay of excited states has been observed in a nucleus situated in the quadrant south-east of doubly magic Sn132, a region in which experimental information so far is limited to ground-state properties. Six γ rays with energies of 50, 86, 103, 227, 357, and 602 keV were observed following the β-delayed neutron emission from Cd85133, populated in the projectile fission of a U238 beam at the Radioactive Isotope Beam Factory at RIKEN within the EURICA project. The new experimental information is compared to the results of a modern realistic shell-model calculation, the first one in this region very far from stability, focusing in particular on the π0g9/2-1 - ν1f7/2 particle-hole multiplet in In83132. In addition, theoretical estimates based on a scaling of the two-body matrix elements for the πh11/2-1 - νg9/2 analog multiplet in Tl127208, one major proton and one major neutron shell above, are presented. © 2016 American Physical Society.

Published
2016

9. Isomers of Pm Isotopes on the Neutron-Rich Frontier of the Deformed Z ~ 60 Region

Author

Y. F. Fang, N. Fukuda, Daisuke Kameda, Mana Tanaka, Simon Rice, Gary Simpson, F. Browne, Giuseppe Lorusso, Laura C. Sinclair, Rin Yokoyama, Guillaume Gey, Masafumi Matsushita, Jan Taprogge, Shunji Nishimura, Kazuma Kobayashi, Naohiro Inabe, István Kuti, Hiroki Nishibata, Toshiyuki Sumikama, Tetsuro Komatsubara, Toshiyuki Kubo, Hiroyuki Takeda, Zhihuan Li, Zs. Vajta, Atsuko Odahara, Zhengyu Xu, Frank Bello, Pär-Anders Söderström, Motoki Kobayashi, Nori Aoi, Tadaaki Isobe, Chang-Bum Moon, Shin'ichiro Michimasa, Ayumi Yagi, I. Nishizuka, R. Daido, Jin Wu, Hidetada Baba, Shintaro Go, Hiroshi Watanabe, Eiji Ideguchi, Zena Patel, E. Sahin, H. Suzuki, and Pieter Doornnbal

Subjects
Nuclear physics, Physics, Frontier, Isotope, Neutron
Published
2015

10. β-Decay Half-Lives of 110 Neutron-Rich Nuclei across theN=82Shell Gap: Implications for the Mechanism and Universality of the AstrophysicalrProcess

Author

H. Baba, Toshiyuki Kubo, Megumi Niikura, Zena Patel, Shunji Nishimura, Hiroki Nishibata, Atsuko Odahara, Hiroyoshi Sakurai, D. Kameda, Tadaaki Isobe, P. Schury, Naohiro Inabe, A. Jungclaus, Hyo Soon Jung, Anna Wendt, Pieter Doornenbal, G. D. Kim, Young-Ki Kim, Hiroshi Suzuki, Toshiyuki Sumikama, F. C. L. Crespi, Bradley S. Meyer, Roman Gernhäuser, Hiroyuki Takeda, K. Steiger, Younghun Kwon, A. Montaner-Pizá, Giuseppe Lorusso, F. G. Kondev, F. Browne, R. Orlandi, Y. Shimizu, P. A. Söderström, Zs. Vajta, Guillaume Gey, Ayumi Yagi, Jan Taprogge, Hiroshi Watanabe, Z. H. Li, Jin Wu, F. Naqvi, I. Kojouharov, G. Benzoni, K. Moschner, S. Shibagaki, Zhengyu Xu, Toshitaka Kajino, Gary Simpson, H. Schaffner, K. Yoshinaga, Gregory Lane, K. Y. Chae, Naoki Fukuda, Zs. Podolyák, and N. Kurz

Subjects
Nuclear physics, Physics, Stars, Isotope, Double beta decay, General Physics and Astronomy, r-process, Neutron, 7. Clean energy, Universality (dynamical systems)
Abstract

The $\ensuremath{\beta}$-decay half-lives of 110 neutron-rich isotopes of the elements from $_{37}\mathrm{Rb}$ to $_{50}\mathrm{Sn}$ were measured at the Radioactive Isotope Beam Factory. The 40 new half-lives follow robust systematics and highlight the persistence of shell effects. The new data have direct implications for $r$-process calculations and reinforce the notion that the second ($A\ensuremath{\approx}130$) and the rare-earth-element ($A\ensuremath{\approx}160$) abundance peaks may result from the freeze-out of an $(n,\ensuremath{\gamma})\ensuremath{\rightleftarrows}(\ensuremath{\gamma},n)$ equilibrium. In such an equilibrium, the new half-lives are important factors determining the abundance of rare-earth elements, and allow for a more reliable discussion of the $r$ process universality. It is anticipated that universality may not extend to the elements Sn, Sb, I, and Cs, making the detection of these elements in metal-poor stars of the utmost importance to determine the exact conditions of individual $r$-process events.

Published
2015

11. Yrast 6+Seniority Isomers of136,138Sn

Author

Hiroyoshi Sakurai, Shunji Nishimura, D. Mücher, Atsuko Odahara, Naohiro Inabe, Toshiyuki Sumikama, Zs. Vajta, J. M. Daugas, H. Naïdja, Hiroyuki Takeda, T. Kröll, I. Kojouharov, G. D. Kim, Giuseppe Lorusso, K. Steiger, F. Drouet, Pieter Doornenbal, Zhengyu Xu, Young-Ki Kim, R. Orlandi, Y. Shimizu, Younghun Kwon, Ayumi Yagi, Toshiyuki Kubo, A. Montaner-Pizá, Anna Wendt, K. Yoshinaga, Jin Wu, F. Browne, G. S. Simpson, Jan Taprogge, D. Kameda, H. Baba, K. Moschner, Tadaaki Isobe, Hiroki Nishibata, S. Ilieva, Guillaume Gey, H. Schaffner, Z. H. Li, A. Jungclaus, N. Kurz, Pär-Anders Söderström, Hyo Soon Jung, Naoki Fukuda, Hiroshi Suzuki, Roman Gernhäuser, S. Bönig, Hiroshi Watanabe, F. Nowacki, and Kamila Sieja

Subjects
Physics, Isotope, 010308 nuclear & particles physics, Fission, Yrast, Nuclear Theory, General Physics and Astronomy, 01 natural sciences, 7. Clean energy, Nuclear physics, Matrix (mathematics), Seniority (financial), Excited state, 0103 physical sciences, Neutron, Nuclear Experiment, 010306 general physics, Beam (structure)
Abstract

Delayed γ-ray cascades, originating from the decay of (6⁺) isomeric states, in the very neutron-rich, semimagic isotopes (136,138)Sn have been observed following the projectile fission of a ²³⁸U beam at RIBF, RIKEN. The wave functions of these isomeric states are proposed to be predominantly a fully aligned pair of f(7/2) neutrons. Shell-model calculations, performed using a realistic effective interaction, reproduce well the energies of the excited states of these nuclei and the measured transition rates, with the exception of the B(E2;6⁺→4⁺) rate of ¹³⁶Sn, which deviates from a simple seniority scheme. Empirically reducing the νf(7/2)(2) orbit matrix elements produces a 4₁⁺ state with almost equal seniority 2 and 4 components, correctly reproducing the experimental B(E2;6⁺→4⁺) rate of ¹³⁶Sn. These data provide a key benchmark for shell-model interactions far from stability.

Published
2014

12. Isomers inPd128andPd126: Evidence for a Robust Shell Closure at the Neutron Magic Number 82 in Exotic Palladium Isotopes

Author

F. Browne, Shunji Nishimura, Guillaume Gey, Atsuko Odahara, Pieter Doornenbal, Naohiro Inabe, Pär-Anders Söderström, Hiroki Nishibata, Ayumi Yagi, I. Kojouharov, Roman Gernhäuser, F. C. L. Crespi, Daiki Nishimura, Jan Taprogge, K. Moschner, F. G. Kondev, H. Schaffner, H. S. Jung, Toshiyuki Kubo, F. Naqvi, G. Benzoni, Hiroyoshi Sakurai, Zs. Vajta, Zhengyu Xu, Zhenping Li, Anna Wendt, N. Fukuda, K. Yoshinaga, R. Orlandi, Zena Patel, D. Kameda, Gary Simpson, K. Steiger, G. J. Lane, Giuseppe Lorusso, Tadaaki Isobe, Chang-Bum Moon, A. Jungclaus, Hiroshi Suzuki, G. D. Kim, Toshiyuki Sumikama, Young-Ki Kim, Hiroyuki Takeda, Younghun Kwon, A. Montaner-Pizá, Jin Wu, Hiroshi Watanabe, H. Baba, Zs. Podolyák, N. Kurz, M. Niikura, and K. Y. Chae

Subjects
Physics, 010308 nuclear & particles physics, Yrast, Isotone, Nuclear Theory, General Physics and Astronomy, 01 natural sciences, Magic number (programming), Isotopes of palladium, Neutron number, 0103 physical sciences, Quadrupole, Level structure, Neutron, Atomic physics, 010306 general physics
Abstract

The level structures of the very neutron-rich nuclei $^{128}\mathrm{Pd}$ and $^{126}\mathrm{Pd}$ have been investigated for the first time. In the $r$-process waiting-point nucleus $^{128}\mathrm{Pd}$, a new isomer with a half-life of $5.8(8)\text{ }\text{ }\ensuremath{\mu}\mathrm{s}$ is proposed to have a spin and parity of ${8}^{+}$ and is associated with a maximally aligned configuration arising from the ${g}_{9/2}$ proton subshell with seniority $\ensuremath{\upsilon}=2$. For $^{126}\mathrm{Pd}$, two new isomers have been identified with half-lives of 0.33(4) and $0.44(3)\text{ }\text{ }\ensuremath{\mu}\mathrm{s}$. The yrast ${2}^{+}$ energy is much higher in $^{128}\mathrm{Pd}$ than in $^{126}\mathrm{Pd}$, while the level sequence below the ${8}^{+}$ isomer in $^{128}\mathrm{Pd}$ is similar to that in the $N=82$ isotone $^{130}\mathrm{Cd}$. The electric quadrupole transition that depopulates the ${8}^{+}$ isomer in $^{128}\mathrm{Pd}$ is more hindered than the corresponding transition in $^{130}\mathrm{Cd}$, as expected in the seniority scheme for a semimagic, spherical nucleus. These experimental findings indicate that the shell closure at the neutron number $N=82$ is fairly robust in the neutron-rich Pd isotopes.

Published
2013

13. Promptγ-ray spectroscopy of the neutron-rich124Cd

Author

C. Scholey, G. Thiamova, Sami Rinta-Antila, Paul Greenlees, Panu Ruotsalainen, M. Ramdhane, Jan Sarén, Andrej Herzan, R. Julin, Grégoire Kessedjian, S. Juutinen, T. Malkiewicz, Peter M. Jones, A. Lopez-Martens, Guillaume Gey, Juha Sorri, Pauli Peura, Ulrika Jakobsson, Mikael Sandzelius, K. Hauschild, C. Sage, F. Drouet, Juha Uusitalo, P. Rahkila, T. Grahn, Steffen Ketelhut, Paivi Nieminen, Gary Simpson, A. Vancraeyenest, Laboratoire de Physique Subatomique et de Cosmologie (LPSC), and Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, Triple coincidence, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], ta114, 010308 nuclear & particles physics, Fission, QC1-999, Astrophysics::High Energy Astrophysical Phenomena, Nuclear Theory, 7. Clean energy, 01 natural sciences, Engineering physics, Semiconductor detector, Nuclear physics, Isotopes of cadmium, 0103 physical sciences, Neutron, Nuclear Experiment, 010306 general physics, Spectroscopy, ComputingMilieux_MISCELLANEOUS
Abstract

Prompt γ -ray spectroscopy of neutron-rich cadmium isotopes has been performed. The nuclei of interest have been populated via a 25-MeV, proton-induced fission of the 238 U thick target and prompt γ -rays measured using the multi-detector HPGe array JUROGAM II. New high-spin decays have been observed and placed in the level scheme using triple coincidence gates. The experimental results are compared to shell-model calculations and show good agreement.

Published
2013

14. Gamma Spectroscopy of Low-energy Isomeric States in Neutron-rich Nuclei: 75Cu

Author

Georgi P. Georgiev, G. S. Simpson, F. Negoita, C. Petrone, R. Borcea, L. Gaudefroy, O. Sorlin, L. Caceres, R. Chevrier, C. Plaisir, O. Kamalou, Guillaume Gey, J. M. Daugas, S. Calinescu, M. Stanoiu, C. Borcea, F. Rotaru, and J. C. Thomas

Subjects
Nuclear physics, Physics, Low energy, 010308 nuclear & particles physics, 0103 physical sciences, General Physics and Astronomy, Gamma spectroscopy, Neutron, 010306 general physics, 01 natural sciences
Published
2013

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