Investigating nuclear shell structure in the vicinity of Ni 78: Low-lying excited states in the neutron-rich isotopes Zn 80,82

Y. Shiga, K. Yoneda, D. Steppenbeck, N. Aoi, P. Doornenbal, J. Lee, H. Liu, M. Matsushita, S. Takeuchi, H. Wang, H. Baba, P. Bednarczyk, Zs Dombradi, Zs Fulop, S. Go, T. Hashimoto, M. Honma, E. Ideguchi, K. Ieki, K. KobayashiY. Kondo, R. Minakata, T. Motobayashi, D. Nishimura, T. Otsuka, H. Otsu, H. Sakurai, N. Shimizu, D. Sohler, Y. Sun, A. Tamii, R. Tanaka, Z. Tian, Y. Tsunoda, Zs Vajta, T. Yamamoto, X. Yang, Z. Yang, Y. Ye, R. Yokoyama, J. Zenihiro

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Abstract

The low-lying level structures of nuclei in the vicinity of Ni78 were investigated using in-beam γ-ray spectroscopy to clarify the nature of the nuclear magic numbers Z=28 and N=50 in systems close to the neutron drip line. Nucleon knockout reactions were employed to populate excited states in Zn80 and Zn82. A candidate for the 41+ level in Zn80 was identified at 1979(30) keV, and the lifetime of this state was estimated to be 136-67+92 ps from a line-shape analysis. Moreover, the energy of the 21+ state in Zn82 is reported to lie at 621(11) keV. The large drop in the 21+ energy at Zn82 indicates the presence of a significant peak in the E(21+) systematics at N=50. Furthermore, the E(41+)/E(21+) and B(E2;41+→21+)/B(E2;21+→0g.s.+) ratios in Zn80 were deduced to be 1.32(3) and 1.12-60+80, respectively. These results imply that Zn80 can be described in terms of two-proton configurations with a Ni78 core and are consistent with a robust N=50 magic number along the Zn isotopic chain. These observations, therefore, indicate a persistent N=50 shell closure in nuclei far from the line of β stability, which in turn suggests a doubly magic structure for Ni78.

Original languageEnglish
Article number024320
JournalPhysical Review C
Volume93
Issue number2
DOIs
Publication statusPublished - Feb 24 2016

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All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics

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