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

Systematics of high-spin isomers in 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. Sagawa<sup>7

1</sup>  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 , 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 and 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 - .

© Società Italiana di Fisica, Springer-Verlag 2002