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1. Shell evolution beyond Z=28 and N=50: Spectroscopy of 81,82,83,84Zn

Author

C.M. Shand, Zs. Podolyák, M. Górska, P. Doornenbal, A. Obertelli, F. Nowacki, T. Otsuka, K. Sieja, J.A. Tostevin, Y. Tsunoda, G. Authelet, H. Baba, D. Calvet, A. Château, S. Chen, A. Corsi, A. Delbart, J.M. Gheller, A. Giganon, A. Gillibert, T. Isobe, V. Lapoux, M. Matsushita, S. Momiyama, T. Motobayashi, M. Niikura, H. Otsu, N. Paul, C. Péron, A. Peyaud, E.C. Pollacco, J.-Y. Roussé, H. Sakurai, C. Santamaria, M. Sasano, Y. Shiga, D. Steppenbeck, S. Takeuchi, R. Taniuchi, T. Uesaka, H. Wang, K. Yoneda, T. Ando, T. Arici, A. Blazhev, F. Browne, A.M. Bruce, R.J. Carroll, L.X. Chung, M.L. Cortés, M. Dewald, B. Ding, Zs. Dombrádi, F. Flavigny, S. Franchoo, F. Giacoppo, A. Gottardo, K. Hadyńska-Klęk, A. Jungclaus, Z. Korkulu, S. Koyama, Y. Kubota, J. Lee, M. Lettmann, B.D. Linh, J. Liu, Z. Liu, C. Lizarazo, C. Louchart, R. Lozeva, K. Matsui, T. Miyazaki, K. Moschner, M. Nagamine, N. Nakatsuka, S. Nishimura, C.R. Nita, C.R. Nobs, L. Olivier, S. Ota, R. Orlandi, Z. Patel, P.H. Regan, M. Rudigier, E. Şahin, T. Saito, P.-A. Söderström, I. Stefan, T. Sumikama, D. Suzuki, Zs. Vajta, V. Vaquero, V. Werner, K. Wimmer, J. Wu, and Z.Y. Xu

Subjects
Physics, QC1-999
Abstract

We report on the measurement of new low-lying states in the neutron-rich 81,82,83,84Zn nuclei via in-beam γ-ray spectroscopy. These include the 41+→21+ transition in 82Zn, the 21+→0g.s.+ and 41+→21+ transitions in 84Zn, and low-lying states in 81,83Zn were observed for the first time. The reduced E(21+) energies and increased E(41+)/E(2+1) ratios at N=52, 54 compared to those in 80Zn attest that the magicity is confined to the neutron number N=50 only. The deduced level schemes are compared to three state-of-the-art shell model calculations and a good agreement is observed with all three calculations. The newly observed 2+ and 4+ levels in 84Zn suggest the onset of deformation towards heavier Zn isotopes, which has been incorporated by taking into account the upper sdg orbitals in the Ni78-II and the PFSDG-U models.

Published
2017
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2. The role of core excitations in the structure and decay of the 16+ spin-gap isomer in 96Cd

Author

P.J. Davies, H. Grawe, K. Moschner, A. Blazhev, R. Wadsworth, P. Boutachkov, F. Ameil, A. Yagi, H. Baba, T. Bäck, M. Dewald, P. Doornenbal, T. Faestermann, A. Gengelbach, J. Gerl, R. Gernhäeuser, S. Go, M. Górska, E. Gregor, T. Isobe, D.G. Jenkins, H. Hotaka, J. Jolie, I. Kojouharov, N. Kurz, M. Lewitowicz, G. Lorusso, L. Maier, E. Merchan, F. Naqvi, H. Nishibata, D. Nishimura, S. Nishimura, F. Nowacki, N. Pietralla, H. Schaffner, P.-A. Söderström, H.S. Jung, K. Steiger, T. Sumikama, J. Taprogge, P. Thöle, N. Warr, H. Watanabe, V. Werner, Z.Y. Xu, K. Yoshinaga, and Y. Zhu

Subjects
β-decay, βp-decay, γ-ray spectroscopy, Half-life, Shell-model, WKB, Physics, QC1-999
Abstract

The first evidence for β-delayed proton emission from the 16+ spin gap isomer in 96Cd is presented. The data were obtained from the Rare Isotope Beam Factory, at the RIKEN Nishina Center, using the BigRIPS spectrometer and the EURICA decay station. βp branching ratios for the ground state and 16+ isomer have been extracted along with more precise lifetimes for these states and the lifetime for the ground state decay of 95Cd. Large scale shell model (LSSM) calculations have been performed and WKB estimates made for ℓ=0,2,4 proton emission from three resonance-like states in 96Ag, that are populated by the β decay of the isomer, and the results compared to the new data. The calculations suggest that ℓ=2 proton emission from the resonance states, which reside ∼5 MeV above the proton separation energy, dominates the proton decay. The results highlight the importance of core-excited wavefunction components for the 16+ state.

Published
2017
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3. Sequential Nature of (p,3p) Two-Proton Knockout from Neutron-Rich Nuclei

Author

Megumi Niikura, K. Yoneda, Tomohiro Uesaka, T. Miyazaki, J.-Y. Roussé, A. Jungclaus, I. G. Stefan, Masaki Sasano, A. Gillibert, Jian Liu, Hiroyoshi Sakurai, David Steppenbeck, Zs. Dombradi, K. Moschner, M. Gómez-Ramos, Satoshi Takeuchi, D. Calvet, T. Isobe, Shunji Nishimura, T. Saito, V. Lapoux, H. Wang, T. Motobayashi, L. Olivier, R. Lozeva, A. Gottardo, S. Franchoo, C. Péron, H. Baba, Jinguang Wu, G. Authelet, A. Delbart, A. Blazhev, J. M. Gheller, Hideaki Otsu, F. Château, Masafumi Matsushita, Zs. Vajta, Zena Patel, Victor Vaquero, Kathrin Wimmer, M. L. Cortés, K. Matsui, Shuichi Ota, C. Santamaria, E. C. Pollacco, M. Dewald, Alessandra Corsi, F. Browne, C. R. Nita, M. Rudigier, Z. Korkulu, Jenny Lee, Yoshiaki Shiga, K. Hadynska-Klek, S. Nagamine, Satoru Momiyama, A. Frotscher, T. Arici, Ryo Taniuchi, Noritaka Shimizu, C. R. Nobs, Toshiyuki Sumikama, Alison Bruce, C. Louchart, E. Sahin, Toshiaki Ando, Zhenci Xu, F. Giacoppo, Y. Kubota, L. X. Chung, B. D. Linh, P. Doornenbal, F. Flavigny, A. Giganon, N. Paul, C. M. Shand, Noritsugu Nakatsuka, Zi Hong Liu, V. Werner, M. Górska, Si-Ge Chen, P. A. Söderström, D. Suzuki, M. Lettmann, R. Orlandi, C. Lizarazo, A. Obertelli, Raymond J. Carroll, Bing Ding, Zs. Podolyák, Shoko Koyama, and Alan Peyaud

Subjects
Physics, Hydrogen, Proton, Projectile, Nuclear Theory, General Physics and Astronomy, chemistry.chemical_element, 01 natural sciences, Coincidence, Nuclear physics, medicine.anatomical_structure, chemistry, MINOS, 0103 physical sciences, medicine, Neutron, Nuclear Experiment, 010306 general physics, Nucleon, Nucleus
Abstract

Twenty-one two-proton knockout (p; 3p) cross sections from neutron-rich nuclei at ~ 250 MeV/nucleon were measured. For the first time, the angular distribution of the three emitted protons were measured in coincidence with the tracker and hydrogen target MINOS, demonstrating that the (p; 3p) kinematics is consistent with two sequential proton-proton collisions within the projectile nucleus. Ratios of (p; 3p) over (p; 2p) inclusive cross sections follow the trend of other many-proton (neutron) removal reactions, further reinforcing the sequential nature of (p; 3p) in neutron-rich nuclei.

Published
2020
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4. Metastable States of Se92,94 : Identification of an Oblate K Isomer of Se94 and the Ground-State Shape Transition between N=58 and 60

Author

L. Olivier, I. Kojouharov, G. Authelet, J. M. Gheller, V. Lapoux, Jenny Lee, J.-Y. Roussé, J. Gerl, C. Lizarazo, N. Paul, Noritsugu Nakatsuka, Hiroyoshi Sakurai, H. Schaffner, P. M. Walker, Zi Hong Liu, V. Werner, David Steppenbeck, T. Motobayashi, A. Blazhev, P. Doornenbal, Shunji Nishimura, I. Stefan, M. L. Cortés, T. Arici, J. J. Liu, Tomás R. Rodríguez, Alison Bruce, A. Giganon, C. Santamaria, F. Château, Megumi Niikura, Zhengyu Xu, F. Browne, Tomohiro Uesaka, M. Rudigier, C. R. Niţă, P. A. Söderström, Zena Patel, T. Saito, N. Kurz, M. Górska, S. Franchoo, A. Gillibert, G. X. Dong, A. Gottardo, C. M. Shand, Satoru Momiyama, L. X. Chung, C. R. Nobs, B. D. Linh, S. Nagamine, Ryo Taniuchi, A. Obertelli, M. Dewald, K. Moschner, Kathrin Wimmer, H. Baba, R. J. Caroll, D. Calvet, F. Flavigny, Bing Ding, Zs. Podolyák, Furong Xu, Toshiaki Ando, Si-Ge Chen, Victor Vaquero, M. Lettmann, A. Corsi, Norbert Pietralla, and A. Delbart

Subjects
Physics, 010308 nuclear & particles physics, General Physics and Astronomy, chemistry.chemical_element, Germanium, 01 natural sciences, Hafnium, medicine.anatomical_structure, chemistry, Atomic orbital, Metastability, 0103 physical sciences, Physics::Atomic and Molecular Clusters, medicine, Neutron, Atomic physics, Nuclear Experiment, 010306 general physics, Ground state, Spectroscopy, Nucleus
Abstract

Here we present new information on the shape evolution of the very neutron-rich ^{92,94}Se nuclei from an isomer-decay spectroscopy experiment at the Radioactive Isotope Beam Factory at RIKEN. High-resolution germanium detectors were used to identify delayed γ rays emitted following the decay of their isomers. New transitions are reported extending the previously known level schemes. The isomeric levels are interpreted as originating from high-K quasineutron states with an oblate deformation of β∼0.25, with the high-K state in ^{94}Se being metastable and K hindered. Following this, ^{94}Se is the lowest-mass neutron-rich nucleus known to date with such a substantial K hindrance. Furthermore, it is the first observation of an oblate K isomer in a deformed nucleus. This opens up the possibility for a new region of K isomers at low Z and at oblate deformation, involving the same neutron orbitals as the prolate orbitals within the classic Z∼72 deformed hafnium region. From an interpretation of the level scheme guided by theoretical calculations, an oblate deformation is also suggested for the ^{94}Se_{60} ground-state band.

Published
2020
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5. Shell evolution beyond Z = 28 and N = 50: Spectroscopy of 81,82,83,84 Zn

Author

L. Olivier, K. Moschner, Kathrin Wimmer, E. C. Pollacco, A. Gillibert, C. R. Nita, C. M. Shand, J.-Y. Roussé, Satoru Momiyama, M. Lettmann, Jian Liu, A. Jungclaus, Hideaki Otsu, Z. Korkulu, Ryo Taniuchi, C. Péron, David Steppenbeck, A. Blazhev, Tsuyoshi Miyazaki, G. Authelet, K. Matsui, Satoshi Takeuchi, A. Château, A. Obertelli, F. Nowacki, S. Franchoo, Kamila Sieja, Toshiaki Ando, J. M. Gheller, Alan Peyaud, Jin Wu, L. X. Chung, Shuichi Ota, C. R. Nobs, B. D. Linh, Zs. Vajta, Y. Kubota, Megumi Niikura, M. Rudigier, I. Stefan, H. Wang, R. Orlandi, J. A. Tostevin, Takaharu Otsuka, Si-Ge Chen, P. A. Söderström, Tomohiro Uesaka, C. Lizarazo, S. Nishimura, Zs. Dombradi, Toshiyuki Sumikama, K. Hadynska-Klek, M. Nagamine, Yusuke Tsunoda, T. Isobe, E. Sahin, C. Louchart, Hiroyoshi Sakurai, V. Lapoux, C. Santamaria, T. Motobayashi, Victor Vaquero, F. Giacoppo, T. Arici, A. Corsi, Zena Patel, P. Doornenbal, Masafumi Matsushita, A. Delbart, P. H. Regan, M. Dewald, Zsolt Podolyak, A. Giganon, A. Gottardo, Jenny Lee, F. Flavigny, M. Górska, N. Paul, Noritsugu Nakatsuka, M. L. Cortés, Zi Hong Liu, V. Werner, Raymond J. Carroll, Daisuke Suzuki, D. Calvet, M. Sasano, Bing Ding, Shoko Koyama, Zhengyu Xu, T. Saito, Alison Bruce, R. Lozeva, K. Yoneda, F. Browne, H. Baba, Yoshiaki Shiga, SCOAP, RIKEN Nishina Center for Accelerator-Based Science, Science and Technology Facilities Council (UK), European Commission, European Research Council, Vietnam Academy of Science and Technology, Federal Ministry of Education and Research (Germany), Ministerio de Economía y Competitividad (España), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut Pluridisciplinaire Hubert Curien (IPHC), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique Nucléaire d'Orsay (IPNO), 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), Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), 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), Université de Strasbourg (UNISTRA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), 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, Nuclear and High Energy Physics, Isotope, 010308 nuclear & particles physics, SHELL model, Analytical chemistry, Shell (structure), [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 7. Clean energy, 01 natural sciences, lcsh:QC1-999, Atomic orbital, Neutron number, 0103 physical sciences, ddc:530, Atomic physics, 010306 general physics, Spectroscopy, lcsh:Physics
Abstract

C.M. Shand et al. -- 6 pags., 3 figs., tab. --Open Access funded by Creative Commons Atribution Licence 4.0, We report on the measurement of new low-lying states in the neutron-rich Zn nuclei via in-beam γ-ray spectroscopy. These include the 4 →2 transition in Zn, the 2 →0 and 4 →2 transitions in Zn, and low-lying states in Zn were observed for the first time. The reduced E(2 ) energies and increased E(4 )/E(2 ) ratios at N=52, 54 compared to those in Zn attest that the magicity is confined to the neutron number N=50 only. The deduced level schemes are compared to three state-of-the-art shell model calculations and a good agreement is observed with all three calculations. The newly observed 2 and 4 levels in Zn suggest the onset of deformation towards heavier Zn isotopes, which has been incorporated by taking into account the upper sdg orbitals in the Ni78-II and the PFSDG-U models., All UK authors are supported by the Science and Technology Facilities Council (STFC). The development of MINOS and the core MINOS team have been supported by the European Research Council through the ERC Grant No. MINOS-258567. A. Jungclaus was supported by the Spanish Ministerio de Economía y Competitividad under contract FPA2014-57196-C5-4-P. Authors from Cologne were supported by German BMBF Grant No. 05P15PKFNA. Authors from TU Darmstadt were supported by German BMBF Grant No. 05P12RDFN8 and 05P15RDFN1. L.X. Chung and B.D. Linh would like to acknowledge Vietnam Ministry of Science and Technology for the support, and Radioactive Isotope Physics Laboratory of the RIKEN Nishina Center for supporting their stay during the experiments.

Published
2017
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6. Properties of γ -decaying isomers in the Sn100 region populated in fragmentation of a Xe124 beam

Author

V. Werner, Torbjörn Bäck, Toshiyuki Sumikama, H. Grawe, K. Moschner, N. Warr, N. Kurz, T. Isobe, Giuseppe Lorusso, M. Górska, M. Dewald, P. J. Davies, F. Ameil, P. Doornenbal, A. Gengelbach, J. Gerl, Hyo Soon Jung, Shin-Ichiro Nishimura, H. Baba, F. Naqvi, E. Gregor, K. Steiger, P. A. Söderström, M. Lewitowicz, Daiki Nishimura, T. Faestermann, D. G. Jenkins, Jan Taprogge, Zhengyu Xu, H. Hotaka, P. Thöle, P. Boutachkov, Ayumi Yagi, H. Watanbe, R. Wadsworth, H. Schaffner, A. Blazhev, G. Häfner, R. Lozeva, Norbert Pietralla, J. Jolie, K. Yoshinaga, I. Kojouharov, E. Merchan, Hiroki Nishibata, Roman Gernhäuser, Shintaro Go, and Y. Zhu

Subjects
Physics, Microsecond, Ion beam, Fragmentation (mass spectrometry), 010308 nuclear & particles physics, 0103 physical sciences, Physics::Accelerator Physics, Atomic physics, Nuclear Experiment, 010306 general physics, 01 natural sciences
Abstract

A systematic study was performed of microsecond γ-decaying isomers around Sn100 produced in a fragmentation reaction of a Xe124 beam at 345 MeV/u at the Radioactive Ion Beam Factory of the RIKEN Nishina Center in Saitama, Japan. Half-lives of isomeric states in that region were remeasured allowing us to improve the currently available experimental information. Reduced transition probabilities were deduced and compared to shell-model calculations in various model spaces. The recently reported low-energy transitions in Rh92 and Ag96 were remeasured with improved precision. Additionally, experimental information on isomeric ratios, including five new ones, were extracted and compared to a previous experimental study and the sharp cutoff model of fragmentation reaction.

Published
2019
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7. Prominence of Pairing in Inclusive (p,2p) and (p,pn) Cross Sections from Neutron-Rich Nuclei

Author

A. Corsi, V. Lapoux, Zs. Dombradi, K. Matsui, David Steppenbeck, A. Gillibert, Alan Peyaud, Shoko Koyama, Toshiaki Ando, C. M. Shand, Hiroyoshi Sakurai, M. Rudigier, F. Browne, L. Olivier, Raymond J. Carroll, K. Yoneda, E. Sahin, Yoshiaki Shiga, Bing Ding, F. Château, Pieter Doornenbal, Hidetada Baba, Tomoyuki Saito, Tohru Motobayashi, Zs. Podolyák, Satoru Momiyama, F. Giacoppo, C. R. Nita, T. Sumikama, H. Wang, Megumi Niikura, A. Gottardo, Jenny Lee, M. Dewald, Zs. Vajta, R. Orlandi, Shuichi Ota, E. C. Pollacco, K. Hadynska-Klek, F. Flavigny, P. A. Söderström, Daisuke Suzuki, Yuya Kubota, C. Lizarazo, D. Calvet, S. Nagamine, C. Péron, Tomohiro Uesaka, R. Lozeva, Hideaki Otsu, N. Paul, Shenjian Chen, G. Authelet, Noritsugu Nakatsuka, Ryo Taniuchi, A. Delbart, Carlos A. Bertulani, J. M. Gheller, Zi Hong Liu, V. Werner, T. Arici, M. Matsushita, Masaki Sasano, M. Lettmann, B. D. Linh, C. Santamaria, Alison Bruce, J. L. Rodriguez-Sanchez, Satoshi Takeuchi, I. Stefan, M. Górska, S. Franchoo, C. Louchart, Zhengyu Xu, Zena Patel, J.-Y. Roussé, Tadaaki Isobe, S. Nishimura, A. Jungclaus, Victor Vaquero, T. Miyazaki, M. L. Cortés, A. Obertelli, K. Moschner, Kathrin Wimmer, Z. Korkulu, Jin Wu, L. X. Chung, C. R. Nobs, Jian Liu, A. Blazhev, and A. Giganon

Subjects
Physics, Hydrogen, Proton, Nuclear Theory, General Physics and Astronomy, chemistry.chemical_element, 01 natural sciences, 7. Clean energy, Nuclear physics, chemistry, Cascade, Pairing, 0103 physical sciences, Bound state, Physics::Accelerator Physics, Neutron, Nuclear Experiment, 010306 general physics, Nucleon, Beam (structure)
Abstract

Fifty-five inclusive single nucleon removal cross sections from medium mass neutron-rich nuclei impinging on a hydrogen target at � 250 MeV/nucleon were measured at the RIKEN Radioactive Isotope Beam Factory. Systematically higher cross sections are found for proton removal from nuclei with an even number of protons compared to odd-proton number projectiles for a given neutron separation energy. Neutron removal cross sections display no even-odd splitting contrary to nuclear cascade model predictions. Both effects are understood through simple considerations of neutron separation energies and bound state level densities originating in pairing correlations in the daughter nuclei. These conclusions are supported by comparison with semi-microscopic model predictions,highlighting the enhanced role of low-lying level densities in nucleon removal cross sections from loosely-bound nuclei.

Published
2019
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8. Properties of $\gamma $-decaying Isomers in the $^{100}$Sn Region Revisited

Author

Giuseppe Lorusso, M. Dewald, Hiroki Nishibata, H. Baba, E. Gregor, Shin-Ichiro Nishimura, A. Gengelbach, P. Thöle, H. Schaffner, V. Werner, T. Isobe, A. Blazhev, J. Gerl, F. Naqvi, P. J. Davies, Shintaro Go, Y. Zhu, Ayumi Yagi, K. Moschner, Toshiyuki Sumikama, Torbjörn Bäck, J. Jolie, T. Faestermann, D. G. Jenkins, P. Doornenbal, E. Merchan, M. Górska, M. Lewitowicz, N. Warr, Roman Gernhäuser, K. Steiger, Jan Taprogge, Zhengyu Xu, F. Ameil, H. Hotaka, K. Yoshinaga, I. Kojouharov, H. Grawe, N. Kurz, P. A. Söderström, Norbert Pietralla, Hirofumi Watanabe, R. Wadsworth, Daiki Nishimura, G. Haefner, P. Boutachkov, Hyo Soon Jung, Grand Accélérateur National d'Ions Lourds (GANIL), Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), RIKEN Nishina Center for Accelerator-Based Science, University of Tokyo, Federal Ministry of Education and Research (Germany), Department of Energy (US), Bonn-Cologne Graduate School of Physics and Astronomy, and SCOAP

Subjects
Physics, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], Nuclear Theory, Astrophysics::Instrumentation and Methods for Astrophysics, Nuclear structure, General Physics and Astronomy, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 7. Clean energy, 01 natural sciences, Nuclear physics, medicine.anatomical_structure, 0103 physical sciences, medicine, Nuclear Experiment, 010306 general physics, 010303 astronomy & astrophysics, Nucleus
Abstract

7 pags., 4 figs. -- Presented at the Zakopane Conference on Nuclear Physics “Extremes of the Nuclear Landscape”, Zakopane, Poland, August 26–September 2, 2018. -- Open Access funded by Creative Commons Atribution Licence 4.0, The study of nuclei in the region around the N = Z doubly-magic nucleus 100Sn has been of long standing interest for the nuclear structure and nuclear astrophysics. Recently, Park et al. have reported on properties of γ-decaying isomers and isomeric ratios in the vicinity of 100Sn. That experiment was performed at the Radioactive Ion Beam Factory (RIBF) of the RIKEN Nishina Center in Japan as a part of the EURICA campaign. Neutron-deficient nuclei were produced in a fragmentation reaction of a 124Xe primary beam on a 9Be target at an energy of 345 MeV/A. Secondary ions were separated and identified in the BigRIPS fragment separator and implanted in the silicon detector array WAS3ABi. The data presented here were obtained in another experiment performed at the RIBF using the same reaction but slightly different separator settings. New results of ratios of isomeric population and half-lives of γ-decaying isomers populated in the experiment are presented., This work was carried out at the RIBF operated by the RIKEN Nishina Center, RIKEN and CNS, University of Tokyo. The authors acknowledge the EUROBALL Owners Committee for the loan of germanium detectors and the PreSpec Collaboration for the readout electronics of cluster detectors. This work was partly supported by the German BMBF under contract No. 05P12PKFNE and No. 05P15PKFNA and by the U.S. DOE under grant No. DE-FG02-91ER-40609. G.H. is supported by the Bonn–Cologne Graduate School of Physics and Astronomy.

Published
2018
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9. Signatures of triaxiality in low-spin spectra of $^{86}$Ge

Author

I. Stefan, Alessandra Corsi, C. M. Shand, L. Olivier, M. Dewald, Satoru Momiyama, Megumi Niikura, Norbert Pietralla, Tomohiro Uesaka, A. Gillibert, Jian Liu, R. J. Caroll, Bing Ding, Victor Vaquero, A. Gottardo, S. Nagamine, F. Browne, Tomás R. Rodríguez, A. Delbart, D. Calvet, Zs. Podolyák, Ryo Taniuchi, A. Blazhev, C. R. Nobs, T. Arici, T. Saito, C. Lizarazo, G. Authelet, Zena Patel, M. L. Cortés, J.-Y. Roussé, C. R. Nita, Zhenci Xu, J. M. Gheller, David Steppenbeck, A. Jungclaus, M. Lettmann, A. Giganon, A. Obertelli, F. Château, Pieter Doornenbal, Alison Bruce, Kamila Sieja, Toshiaki Ando, M. Górska, Si-Ge Chen, N. Paul, Noritsugu Nakatsuka, M. Rudigier, P. A. Söderström, Zi Hong Liu, V. Werner, C. Santamaria, L. X. Chung, Hiroyoshi Sakurai, T. Motobayashi, K. Moschner, Hidetada Baba, Kathrin Wimmer, B. D. Linh, Jenny Lee, V. Lapoux, S. Franchoo, F. Flavigny, Département de Physique Nucléaire (ex SPhN) (DPHN), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut Pluridisciplinaire Hubert Curien (IPHC), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique Nucléaire d'Orsay (IPNO), 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), Federal Ministry of Education and Research (Germany), SCOAP, European Commission, Ministerio de Economía y Competitividad (España), Vietnam Academy of Science and Technology, Science and Technology Facilities Council (UK), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), 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), Département de Physique Nucléaire (ex SPhN) ( DPHN ), Institut de Recherches sur les lois Fondamentales de l'Univers ( IRFU ), Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Université Paris-Saclay, Institut Pluridisciplinaire Hubert Curien ( IPHC ), Centre National de la Recherche Scientifique ( CNRS ) -Université de Strasbourg ( UNISTRA ), Institut de Physique Nucléaire d'Orsay ( IPNO ), 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 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, History, Time projection chamber, Spectrometer, 010308 nuclear & particles physics, Fission, State (functional analysis), [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, Spectral line, Computer Science Applications, Education, Nuclear physics, MINOS, 0103 physical sciences, [ PHYS.NEXP ] Physics [physics]/Nuclear Experiment [nucl-ex], 010306 general physics, Spectroscopy, Spin (physics)
Abstract

7 pags., 4 figs. -- XXII International School on Nuclear Physics, Neutron Physics and Applications. -- Open Access funded by Creative Commons Atribution Licence 3.0, Low-spin states of neutron-rich Ge-84,Ge-86,Ge-88 were measured by in-flight gamma-ray spectroscopy at 270 MeV/u at the RIKEN-RIBF facility. The exotic beams have been produced by primary U-238 in-flight fission reactions and impinged on the MINOS device. MINOS combines a 10-cm long LH2 target with a Time Projection Chamber (TPC) to reconstruct the reaction vertices. The reactions were selected by the BigRIPS and the ZeroDegree spectrometers for the incoming and outgoing channels, respectively. Emitted gamma radiation was detected by the NaI-array DALI2. De-excitations from the 6(1)(+), 4(1,2)(+), and 2(1,2)(+) states of Ge-84,Ge- 86 and 4(1)(+) and 26 states of Ge-88 were observed. The data are compared to state-of-the-art shell model and beyond-mean-field calculations. Furthermore, a candidate for a 3(1)(+) state of Ge-86 was identified. This state plays a key role in the discussion of ground-state triaxiality of Ge-86, along with other features of the low-energy level scheme., We acknowledge support from the German BMBF Grant Nos. 05P12RDFN1, 05P12RDFN8 and 05P15PKFNA, the ERC Grant No. MINOS258567, the Spanish Ministerio de Economıa y Competitividad under contracts FPA2014-57196-C5-4-P and FIS−2014−53434, the Vietnam Ministry of Science and Technology, as well as from the Science and Technology Facilities Council (STFC). We further thank GSI for providing computing facilities

Published
2017
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10. Triaxiality of neutron-rich Ge84,86,88 from low-energy nuclear spectra

Author

L. Olivier, Megumi Niikura, Alison Bruce, Tomohiro Uesaka, I. Stefan, M. Rudigier, Z. Patel, A. Giganon, A. Obertelli, C. R. Nita, Tomás R. Rodríguez, C. M. Shand, Satoru Momiyama, N. Paul, Noritsugu Nakatsuka, S. Nagamine, F. Château, Ryo Taniuchi, Bing Ding, J.-Y. Roussé, Zs. Podolyák, C. R. Nobs, K. Moschner, Zhengyu Xu, T. Arici, Zi Hong Liu, V. Werner, A. Jungclaus, Hiroyoshi Sakurai, Kathrin Wimmer, M. Górska, David Steppenbeck, C. Lizarazo, F. Flavigny, H. Baba, T. Saito, G. Authelet, Kamila Sieja, Toshiaki Ando, M. Dewald, Si-Ge Chen, P. A. Söderström, R. J. Caroll, D. Calvet, Tohru Motobayashi, P. Doornenbal, J. M. Gheller, L. X. Chung, A. Gillibert, Jian Liu, A. Blazhev, Victor Vaquero, Andrea Corsi, M. Lettmann, F. Browne, A. Gottardo, Jenny Lee, M. L. Cortés, S. Franchoo, C. Santamaria, B. D. Linh, V. Lapoux, Norbert Pietralla, and A. Delbart

Subjects
Physics, Low energy, 010308 nuclear & particles physics, Excited state, 0103 physical sciences, Neutron, Atomic physics, 010306 general physics, Spectroscopy, 01 natural sciences, Spectral line
Abstract

ray transitions between low-spin states of the neutron-rich 84;86;88Ge were measured by means of in-flight -ray spectroscopy at 270 MeV/u. Excited 6+ 1 , 4+ 1;2 and 2+ 1;2 states of 84;86Ge and 4+ 1 and 2+ 1;2 states of 88Ge were observed. Furthermore a candidate for a 3+ 1 state of 86Ge was identified. This state plays a key role in the discussion of ground-state triaxiality of 86Ge, along with other features of its low-energy level scheme. A new region of triaxially deformed nuclei is proposed in the Ge isotopic chain.

Published
2017
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11. Shape Evolution in Neutron-Rich Krypton Isotopes Beyond N=60 : First Spectroscopy of Kr98,100

Author

J.-Y. Roussé, Hiroyoshi Sakurai, A. Jungclaus, T. Motobayashi, A. Corsi, Jian Liu, A. Delbart, Victor Vaquero, A. Blazhev, R. Orlandi, C. Lizarazo, J. Libert, G. Authelet, F. Château, Toshiaki Ando, K. Moschner, Zhengyu Xu, N. Paul, Noritsugu Nakatsuka, J. M. Gheller, T. Arici, I. Stefan, C. Santamaria, Zi Hong Liu, V. Werner, T. Saito, Si-Ge Chen, Kathrin Wimmer, Zena Patel, P. A. Söderström, A. Obertelli, S. Nagamine, M. Górska, M. L. Cortés, Alison Bruce, M. Girod, A. Giganon, Raymond J. Carroll, B. Ding, Zs. Podolyák, B. D. Linh, V. Lapoux, Megumi Niikura, Tomohiro Uesaka, L. X. Chung, C. R. Nobs, F. Browne, A. Gottardo, Jenny Lee, P. Doornenbal, A. Gillibert, C. M. Shand, F. Flavigny, H. Baba, C. R. Nita, J.-P. Delaroche, S. Franchoo, Ryo Taniuchi, David Steppenbeck, M. Dewald, L. Olivier, D. Calvet, Tomás R. Rodríguez, Satoru Momiyama, M. Lettmann, and M. Rudigier

Subjects
Physics, Isotope, 010308 nuclear & particles physics, Nuclear Theory, General Physics and Astronomy, Isotopes of krypton, 01 natural sciences, Neutron number, 0103 physical sciences, Isotopes of zirconium, Neutron, Gamma spectroscopy, Atomic physics, Nuclear Experiment, 010306 general physics, Spectroscopy, Nucleon
Abstract

We report on the first γ-ray spectroscopy of low-lying states in neutron-rich 98,100Kr isotopes obtained from 99,101Rb(p,2p) reactions at ∼ 220 MeV/nucleon. A reduction of the 2+ 1 state energies beyond N = 60 demonstrates a significant increase of deformation, shifted in neutron number compared to the sharper transition observed in strontium and zirconium isotopes. State-of-theart beyond-mean-field calculations using the Gogny D1S interaction predict level energies in good agreement with experimental results. The identification of a low-lying (0+ 2 , 2+ 2 ) state in 98Kr provides the first experimental evidence of a competing configuration at low energy in neutron-rich krypton isotopes consistent with the oblate-prolate shape coexistence picture suggested by theory

Published
2017
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12. Are There Signatures of Harmonic Oscillator Shells Far from Stability? First Spectroscopy of Zr110

Author

A. Giganon, M. Girod, T. Arici, J.-Y. Roussé, S. Franchoo, Toshiaki Ando, Ryo Taniuchi, A. Jungclaus, B. Ding, Si-Ge Chen, Jian Liu, P. A. Söderström, A. Gillibert, V. Lapoux, Zena Patel, B. D. Linh, Hiroyoshi Sakurai, C. M. Shand, A. Blazhev, C. R. Nita, A. Gottardo, Jenny Lee, T. Motobayashi, J. Libert, B. Bally, F. Château, A. Corsi, A. Delbart, H. Baba, F. Browne, Alison Bruce, Tomoaki Togashi, Megumi Niikura, Zhengyu Xu, J.-P. Delaroche, Tomohiro Uesaka, Tomás R. Rodríguez, P. Doornenbal, M. Rudigier, C. Santamaria, A. Obertelli, T. Saito, Satoru Momiyama, R. Orlandi, M. Lettmann, M. Górska, F. Flavigny, N. Paul, Noritsugu Nakatsuka, M. L. Cortés, Zi Hong Liu, V. Werner, Raymond J. Carroll, V. Vaquero, Paul-Henri Heenen, Zs. Podolyák, I. Stefan, Michaël Bender, C. Lizarazo, L. X. Chung, Yusuke Tsunoda, C. R. Nobs, K. Moschner, G. Authelet, J. M. Gheller, Kathrin Wimmer, David Steppenbeck, Takaharu Otsuka, M. Dewald, D. Calvet, Noritaka Shimizu, L. Olivier, and S. Nagamine

Subjects
Physics, Proton, 010308 nuclear & particles physics, General Physics and Astronomy, 01 natural sciences, 7. Clean energy, 0103 physical sciences, Isotopes of zirconium, Rigid rotor, Atomic physics, 010306 general physics, Nucleon, Ground state, Spectroscopy, Harmonic oscillator, Excitation
Abstract

The first measurement of the low-lying states of the neutron-rich 110 Zr and 112 Mo was performed via in-beam γ -ray spectroscopy after one proton removal on hydrogen at ∼ 200 MeV / nucleon . The 2 + 1 excitation energies were found at 185(11) keV in 110 Zr , and 235(7) keV in 112 Mo , while the R 42 = E ( 4 + 1 ) / E ( 2 + 1 ) ratios are 3.1(2), close to the rigid rotor value, and 2.7(1), respectively. These results are compared to modern energy density functional based configuration mixing models using Gogny and Skyrme effective interactions. We conclude that first levels of 110 Zr exhibit a rotational behavior, in agreement with previous observations of lighter zirconium isotopes as well as with the most advanced Monte Carlo shell model predictions. The data, therefore, do not support a harmonic oscillator shell stabilization scenario at Z = 40 and N = 70 . The present data also invalidate predictions for a tetrahedral ground state symmetry in 110 Zr .

Published
2017
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13. The role of core excitations in the structure and decay of the 16(+) spin-gap isomer in Cd-96

Author

K. Moschner, H. Baba, Toshiyuki Sumikama, Y. Zhu, E. Gregor, M. Lewitowicz, Torbjörn Bäck, J. Jolie, T. Faestermann, D. G. Jenkins, Frédéric Nowacki, N. Warr, Shunji Nishimura, E. Merchan, K. Yoshinaga, Roman Gernhaeuser, H. Schaffner, A. Blazhev, N. Kurz, P. Boutachkov, F. Ameil, Hiroki Nishibata, Ayumi Yagi, I. Kojouharov, Jan Taprogge, J. Gerl, L. Maier, P. Doornenbal, Shintaro Go, D. Nishimura, H. Grawe, M. Górska, K. Steiger, H. Hotaka, T. Isobe, Ziye Xu, V. Werner, P. J. Davies, P. A. Söderström, A. Gengelbach, F. Naqvi, Hiroshi Watanabe, H. S. Jung, P. Thöle, Giuseppe Lorusso, M. Dewald, Norbert Pietralla, R. Wadsworth, Grand Accélérateur National d'Ions Lourds (GANIL), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut Pluridisciplinaire Hubert Curien (IPHC), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), Federal Ministry of Education and Research (Germany), SCOAP, Department of Energy (US), Science and Technology Facilities Council (UK), Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), Université de Strasbourg (UNISTRA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), 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
Nuclear and High Energy Physics, Proton decay, Nuclear Theory, βp-decay, γ -ray spectroscopy, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Shell-model, 01 natural sciences, 7. Clean energy, WKB approximation, Nuclear physics, Subatomär fysik, 0103 physical sciences, Subatomic Physics, ddc:530, Proton emission, 010306 general physics, Wave function, Nuclear Experiment, Physics, WKB, Spectrometer, Isotope, 010308 nuclear & particles physics, β-decay, Half-life, βp-decayγ-ray spectroscopy, beta p-decay, lcsh:QC1-999, β -decay, 3. Good health, gamma-ray spectroscopy, 13. Climate action, γ-ray spectroscopy, Physics::Accelerator Physics, Atomic physics, Ground state, βp -decay, lcsh:Physics, beta-decay
Abstract

P. J. Davies et al. -- 6 pags., 4 figs., 3 tabs.-- Open Access funded by Creative Commons Atribution Licence 4.0, The first evidence for β-delayed proton emission from the 16 spin gap isomer in Cd is presented. The data were obtained from the Rare Isotope Beam Factory, at the RIKEN Nishina Center, using the BigRIPS spectrometer and the EURICA decay station. βp branching ratios for the ground state and 16 isomer have been extracted along with more precise lifetimes for these states and the lifetime for the ground state decay of Cd. Large scale shell model (LSSM) calculations have been performed and WKB estimates made for ℓ=0,2,4 proton emission from three resonance-like states in Ag, that are populated by the β decay of the isomer, and the results compared to the new data. The calculations suggest that ℓ=2 proton emission from the resonance states, which reside ∼5 MeV above the proton separation energy, dominates the proton decay. The results highlight the importance of core-excited wavefunction components for the 16 state., This work was partially supported by the German BMBF grant 05P12PKFNE, the UK Science and Technology Facilities Council(STFC) grants ST/J000124/1 and ST/L005727/1, and the U.S. DOE grant DE-FG02-91ER40609.

Published
2017
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14. Lifetime measurement of neutron-rich even-even molybdenum isotopes

Author

Torbjörn Bäck, M. Labiche, M. Zielińska, M. Reese, A. Gadea, B. Million, T. Hüyük, F. Camera, R. Knoebel, T. Alexander, E. Gregor, N. Alkhomashi, Maria Doncel, A. Prochazka, A. Atac, D. Mengoni, L. J. Harkness-Brennan, Pushpendra Singh, A. Givechev, A. Gottardo, H. J. Wollersheim, T. Arici, Tomás R. Rodríguez, Alberto Pullia, D. Curien, E. Merchan, L. Sengele, C. Domingo-Pardo, Helmut Weick, A. Jungclaus, Herbert Hess, M. Dewald, P. Thoele, I. Kojouharov, G. Duchêne, S. Pietri, G. de Angelis, F. Didierjean, O. Stezowski, J. S. Winfield, N. Kurz, M. Hackstein, N. Goel, B. Birkenbach, P. Reiter, D. S. Judson, C. Stahl, E. Clément, F. Ameil, Pavel Golubev, P. Boutachkov, M. Górska, B. Bruyneel, A. Korichi, H. Schaffner, C. Scheidenberger, R. Avigo, F. Recchia, T. Goigoux, D. Bazzacco, Bo Cederwall, Vicente González, M. D. Salsac, P. Désesquelles, A. I. Morales, Zs. Podolyák, J. Gerl, J. J. Valiente Dobon, T. Habermann, Dirk Rudolph, Alison Bruce, D. Ralet, Luis Sarmiento, J. Jolie, D. R. Napoli, C. Louchart-Henning, Johan Nyberg, G. Guastalla, B. S. Nara Singh, Enrique Sanchis, M. Alaqeel, Oliver Wieland, G. Rainovski, J. Eberth, Norbert Pietralla, Hans Geissel, F. Ghazi Moradi, Anna Wendt, M. L. Cortés, S. Ceruti, N. Lalović, G. Henning, Begoña Quintana, F. Naqvi, W. Korten, Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM), 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), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Grand Accélérateur National d'Ions Lourds (GANIL), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut Pluridisciplinaire Hubert Curien (IPHC), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique Nucléaire de Lyon (IPNL), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Generalitat Valenciana, Ministerio de Economía y Competitividad (España), Science and Technology Facilities Council (UK), Federal Ministry of Education and Research (Germany), Swedish Research Council, European Commission, Helmholtz International Center for FAIR, 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), Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), 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
chemistry.chemical_element, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 7. Clean energy, 01 natural sciences, Nuclear physics, Subatomic Physics, 0103 physical sciences, Neutron, ddc:530, 010306 general physics, Mass number, Physics, Isotope, 010308 nuclear & particles physics, relativistic projectile fragmentation, 3. Good health, secondary fragmentation, gamma-ray spectroscopy, chemistry, Molybdenum, Excited state, Quadrupole, Física nuclear, AGATA, Atomic physics, Energy (signal processing)
Abstract

D. Ralet et al. -- 11 pags., 10 figs., 3 tabs., Background: In the neutron-rich A≈100 mass region, rapid shape changes as a function of nucleon number as well as coexistence of prolate, oblate, and triaxial shapes are predicted by various theoretical models. Lifetime measurements of excited levels in the molybdenum isotopes allow the determination of transitional quadrupole moments, which in turn provides structural information regarding the predicted shape change. Purpose: The present paper reports on the experimental setup, the method that allowed one to measure the lifetimes of excited states in even-even molybdenum isotopes from mass A=100 up to mass A=108, and the results that were obtained. Method: The isotopes of interest were populated by secondary knock-out reaction of neutron-rich nuclei separated and identified by the GSI fragment separator at relativistic beam energies and detected by the sensitive PreSPEC-AGATA experimental setup. The latter included the Lund-York-Cologne calorimeter for identification, tracking, and velocity measurement of ejectiles, and AGATA, an array of position sensitive segmented HPGe detectors, used to determine the interaction positions of the γ ray enabling a precise Doppler correction. The lifetimes were determined with a relativistic version of the Doppler-shift-attenuation method using the systematic shift of the energy after Doppler correction of a γ-ray transition with a known energy. This relativistic Doppler-shift-attenuation method allowed the determination of mean lifetimes from 2 to 250 ps. Results: Even-even molybdenum isotopes from mass A=100 to A=108 were studied. The decays of the low-lying states in the ground-state band were observed. In particular, two mean lifetimes were measured for the first time: τ=29.7-9.1+11.3 ps for the 4+ state of Mo108 and τ=3.2-0.7+0.7 ps for the 6+ state of Mo102. Conclusions: The reduced transition strengths B(E2), calculated from lifetimes measured in this experiment, compared to beyond-mean-field calculations, indicate a gradual shape transition in the chain of molybdenum isotopes when going from A=100 to A=108 with a maximum reached at N=64. The transition probabilities decrease for Mo108 which may be related to its well-pronounced triaxial shape indicated by the calculations., This work was supported by the BMBF under Grants No. 05P09RDFN4, No. 05P12RDFN8, and No. 05P12PKFNE and by the LOEWE center HIC for FAIR. Part of this work was supported by the P2IO excellence center. This work was also supported by the European Community FP7–Capacities, ENSAR Contract No. 262010, by the Swedish Research Council under Contracts No. 2010-147, No. 2010-3694, No. 2011-5253, No. 2011-6127, and No. 2014-5558, by the IN2P3- GSI No. 02-42 collaboration, by the Science and Technology Facilities Council (STFC) and by MINECO, Spain, under Grant No. FPA2014-57196-C5, and Generalitat Valenciana, Spain, under Grant No. PROMETEOII/2014/019

Published
2017
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15. Study of ground and excited state decays inN≈ZAg nuclei

Author

V. Werner, Torbjörn Bäck, J. Gerl, M. Lewitowicz, Jan Taprogge, H. Baba, E. Gregor, Zhengyu Xu, Daiki Nishimura, Hyo Soon Jung, H. Hotaka, Hirofumi Watanabe, K. Yoshinaga, R. Wadsworth, D. G. Jenkins, K. Steiger, A. Blazhev, Giuseppe Lorusso, P. Thöle, K. Moschner, M. Dewald, I. Kojouharov, P. A. Söderström, Norbert Pietralla, Toshiyuki Sumikama, Shintaro Go, H. Schaffner, Y. Zhu, N. Warr, H. Grawe, N. Kurz, M. Górska, P. Doornenbal, A. Gengelbach, P. Boutachkov, F. Naqvi, J. Jolie, S. Nishimura, Roman Gernhäuser, T. Isobe, P. J. Davies, Ayumi Yagi, E. Merchan, Hiroki Nishibata, F. Ameil, and Thomas Faestermann

Subjects
Physics, QC1-999, Excited state, Particle, Atomic physics, Spectroscopy
Abstract

A decay spectroscopy experiment was performed within the EURICA campaign at RIKEN in 2012. It aimed at the isomer and particle spectroscopy of excited states and ground states in the mass region below the doubly magic 100Sn. The N = Z nuclei 98In, 96Cd and 94Ag were of particular interest for the present study. Preliminary results on the neutron deficient nuclei 93Ag and 94Ag are presented. In 94Ag a more precise value for the half-life of the ground state’s superallowed Fermi transition was deduced. In addition the energy spectra of the mentioned decay could be reproduced through precise Geant4 simulations of the used active stopper SIMBA. This will enable us to extract Qβ values from the measured data. The decay of 93Ag is discussed based on the observed implantation-decay correlation events.

Published
2015
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