II-1. Nuclear Physics

RIKEN Accel. Prog. Rep. 54 (2021)

RIKEN Accel. Prog. Rep. 54 (2021)

Evolution of proton single-particle states in neutron-rich Sb isotopes
beyond N = 82†
A. Jungclaus,∗1 J. M. Keatings,∗2 G. S. Simpson,∗3 H. Naïdja,∗4 A. Gargano,∗5 S. Nishimura,∗6 P. Doornenbal,∗6G. Gey,∗3,∗7,∗6 G. Lorusso,∗6 P. -A. Söderström,∗6 T. Sumikama,∗8 J. Taprogge,∗1,∗9,∗6 Z. Y. Xu,∗6 H. Baba,∗6F. Browne,∗10,∗6 N. Fukuda,∗6 N. Inabe,∗6 T. Isobe,∗6 H. S. Jung,∗11 D. Kameda,∗6 G. D. Kim,∗12Y. -K. Kim,∗12,∗13 I. Kojouharov,∗14 T. Kubo,∗6 N. Kurz,∗14 Y. K. Kwon,∗12 Z. Li,∗15 H. Sakurai,∗6,∗16H. Schaﬀner,∗14 Y. Shimizu,∗6 H. Suzuki,∗6 H. Takeda,∗6 Z. Vajta,∗17 H. Watanabe,∗6 J. Wu,∗15,∗6 A. Yagi,∗18
K. Yoshinaga,∗19 S. Bönig,∗20 J. -M. Daugas,∗21 R. Gernhäuser,∗22 S. Ilieva,∗20 T. Kröll,∗20 A. Montaner-Piza,∗23
K. Moschner,∗24 D. Mücher,∗22 H. Nishibata,∗18 A. Odahara,∗18 R. Orlandi,∗25 M. Scheck,∗26 K. Steiger,∗22 andA. Wendt∗24
The chain of Sb isotopes, with a single proton outside
the closed Z = 50 proton shell, has attracted for many
years a special interest since it oﬀers the unique possibility to study the evolution of the proton single-particle
states in the Z = 50–82 major shell over a wide rangeof neutron number. Prior to this work, excited-state information was available from the very neutron-deﬁcientisotope 105 Sb, close to the presumably doubly-magic
100
Sn, up to the neutron-rich isotope 135 Sb. Above theN = 82 neutron shell gap, when the neutrons start ﬁlling the 1f7/2 orbital, a dramatic decrease of the energy
133
Sb to 281 keV inof the 5/2+
1 state from 962 keV in1351,2)
Sb was observed.
The present work aimed for an extension of the exFig. 1. Excitation energy diﬀerence between the 5/2+
1 and7/2+
1 states in the odd Sb isotopes. Experimental values
are shown as open (literature) and ﬁlled (present work)
diamonds while solid blue (green) lines represent the results of SM calculations employing the Napoli (N3LOP)
interactions. The diﬀerences between the eﬀective SPEof the 1d5/2 and 0g7/2 orbitals are shown by dashed lines(adopted from Fig. 7 of the original article).

Condensed from the article in Phys. Rev. C 102, 034324(2020)∗1 IEM-CSIC∗2 School of Computing, Engineering, and Physical Sciences,
University of the West of Scotland∗3 LPSC, Université Joseph Fourier Grenoble 1, CNRS/IN2P3,
Institut National Polytechnique de Grenoble∗4 Laboratoire de Physique Mathematique et Subatomique,
Constantine University∗5 INFN Sezione di Napoli∗6 RIKEN Nishina Center∗7 Institut Laue-Langevin∗8 Department of Physics, Tohoku University∗9 Departamento de Física Teórica, Universidad Autónoma deMadrid∗10 School of Computing, Engineering and Mathematics, University of Brighton∗11 Department of Physics, Chung-Ang University∗12 Rare Isotope Science Project, Institute for Basic Science(IBS)∗13 Department of Nuclear Engineering, Hanyang University∗14 GSI Helmholtzzentrum für Schwerionenforschung GmbH
∗15 School of Physics and State key Laboratory of Nuclear
Physics and Technology, Peking University∗16 Department of Physics, University of Tokyo∗17 Atomki∗18 Department of Physics, Osaka University∗19 Department of Physics, Faculty of Science and Technology,
Tokyo University of Science∗20 Institut für Kernphysik, Technische Universität Darmstadt∗21 CEA, DAM∗22 Physik Department E12, Technische Universität München∗23 IFIC, CSIC-Univ. Valencia∗24 IKP, University of Cologne∗25 Advanced Science Research Center, Japan Atomic EnergyAgency∗26 School of Engineering, University of the West of Scotland†

perimental information towards more neutron-rich Sb
isotopes. Excited states in 136, 137, 138 Sb, populated inthe β decay of the semi-magic Sn isotopes 136, 137, 138 Sn,
were studied within the EURICA campaign. The clean
ion identiﬁcation and high γ-ray detection eﬃciency allowed to observe for the ﬁrst time the decay of excitedstates in the N = 86 isotope 137 Sb, which is considered as one of the key nuclei to pin down the evolutionof the single-particle structure beyond N = 82. As
shown in Fig. 1, the experimental energy of the 5/2+
1state, Ex = 84 keV, lies in the middle between the results of shell-model calculations performed using two
diﬀerent realistic eﬀective interactions, labeled Napoli
and N3LOP. Together with a similar comparison for136, 138Sb, the new experimental information thus allows to trace the evolution of the single-particle energies
above the N = 82 shell closure.
References

1) M. Sanchez-Vega et al., Phys. Rev. C 60, 024303 (1999).
2) J. Shergur et al., Phys. Rev. C 71, 064321 (2005).

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