Proton Shell Evolution below Sn 132: First Measurement of Low-Lying β -Emitting Isomers in Ag 123,125

Z. Q. Chen, Z. H. Li, H. Hua, H. Watanabe, C. X. Yuan, S. Q. Zhang, G. Lorusso, S. Nishimura, H. Baba, F. Browne, G. Benzoni, K. Y. Chae, F. C.L. Crespi, P. Doornenbal, N. Fukuda, G. Gey, R. Gernhäuser, N. Inabe, T. Isobe, D. X. JiangA. Jungclaus, H. S. Jung, Y. Jin, D. Kameda, G. D. Kim, Y. K. Kim, I. Kojouharov, F. G. Kondev, T. Kubo, N. Kurz, Y. K. Kwon, X. Q. Li, J. L. Lou, G. J. Lane, C. G. Li, D. W. Luo, A. Montaner-Pizá, K. Moschner, C. Y. Niu, F. Naqvi, M. Niikura, H. Nishibata, A. Odahara, R. Orlandi, Z. Patel, Zs Podolyák, T. Sumikama, P. A. Söderström, H. Sakurai, H. Schaffner, G. S. Simpson, K. Steiger, H. Suzuki, J. Taprogge, H. Takeda, Zs Vajta, H. K. Wang, J. Wu, A. Wendt, C. G. Wang, H. Y. Wu, X. Wang, C. G. Wu, C. Xu, Z. Y. Xu, A. Yagi, Y. L. Ye, K. Yoshinaga

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3 Citations (Scopus)

Abstract

The β-delayed γ-ray spectroscopy of neutron-rich Ag123,125 isotopes is investigated at the Radioactive Isotope Beam Factory of RIKEN, and the long-predicted 1/2- β-emitting isomers in Ag123,125 are identified for the first time. With the new experimental results, the systematic trend of energy spacing between the lowest 9/2+ and 1/2- levels is extended in Ag isotopes up to N=78, providing a clear signal for the reduction of the Z=40 subshell gap in Ag towards N=82. Shell-model calculations with the state-of-the-art VMU plus M3Y spin-orbit interaction give a satisfactory description of the low-lying states in Ag123,125. The tensor force is found to play a crucial role in the evolution of the size of the Z=40 subshell gap. The observed inversion of the single-particle levels around Ag123 can be well interpreted in terms of the monopole shift of the π1g9/2 orbitals mainly caused by the increasing occupation of ν1h11/2 orbitals.

Original languageEnglish
Article number212502
JournalPhysical review letters
Volume122
Issue number21
DOIs
Publication statusPublished - May 28 2019
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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