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Hadrons and Nuclei


Eur. Phys. J. A 13, 5-8 (2002)

Systematics of high-spin isomers in $\mth{N=83}$ isotones and a high-spin isomer beam

Y. Gono1, A. Odahara2, T. Fukuchi1, E. Ideguchi3, T. Kishida4, T. Kubo4, H. Watanabe1, S. Motomura1, K. Saito1, O. Kashiyama1, T. Morikawa1, B. Cederwall5, Y.H. Zhang6, X.H. Zhou6, M. Ishihara4 and H. Sagawa7

1  Department of Physics, Kyushu University, Fukuoka 812-8581, Japan
2  Nishinippon Institute of Technology, Kanda, Fukuoka 800-03, Japan
3  Department of Chemistry, Washington University, St. Louis 63130, USA
4  RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
5  Royal Institute of Technology, S-104 05 Stockholm, Sweden
6  Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China
7  University of Aizu, Fukushima 965-8580, Japan

(Received: 1 May 2001 / Revised version: 14 December 2001)

Abstract
Isomers in N=83 isotones of $Z=60\mbox{--}66$, were studied systematically. Their spins and parities are 49/2 + and 27 + for odd and odd-odd nuclei, respectively. Nearly constant excitation energies of these isomers indicated a decrease of a Z=64 shell gap energy as Z decreases from 64 to 60 within the framework of a deformed independent-particle model (DIPM). Their configurations are $[\nu (f_{7/2} h_{9/2} i_{13/2}), \pi (h_{11/2})^{2}]_{49/2^+}$ and $[\nu (f_{7/2} h_{9/2} i_{13/2}), \pi (h_{11/2})^{2}(d_{5/2})^{-1}]_{27^+}$ for odd and odd-odd nuclei, respectively. The shape of the yrast states changes suddenly at spin 49/2(odd) and 27(odd-odd) from a near spherical to an oblate shape. Transitions from isomers are highly hindered because of the shape changes. They may be categorized to be shape isomers. The development of a secondary beam produced by using these high-spin isomers is also described.

PACS
21.10.-k - Properties of nuclei; nuclear energy levels.
27.60.+j - $90 \leq A \leq 149$ .

© Società Italiana di Fisica, Springer-Verlag 2002