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Hadrons and Nuclei
Eur. Phys. J. A 1, 125-135

High spin states and evidence for octupole correlations in 117Xe

Z. Liu1 - X. Sun1 - X. Zhou1 - X. Lei1 - Y. Guo1 - Y. Zhang1 - X. Chen1 - H. Jin1 - Y. Luo1 - S.X. Wen2 - C.X. Yang2 - G.J. Yuan2 - G.S. Li2 - X.A. Liu2 - W.D. Luo2 - Y.S. Chen2

1 Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, People's Republic of China
2 China Institute of Atomic Energy, Beijing 102413, People's Republic of China

Received: 17 June 1997 / Revised version: 29 September 1997 Communicated by B. Herskind

Abstract
High-spin states of 117Xe were investigated by means of in-beam $\gamma
-$ray spectroscopic techniques via the reaction of 28Si bombarding a 92Mo target at beam energies of 100-120 MeV. A positive-parity rotational band decaying into the yrast negative-parity band by a series of enhanced E1 transitions was observed for the first time, implying the existence of octupole correlations in 117Xe. The B(E1) values increase with spin. The $\nu $d5/2 band was firmly established up to 27/2+ and the B(M1)/B(E2) ratios were extracted from the relative intensities of $\gamma $-rays in this band. The previously known $\nu $h11/2 and $\nu $g7/2 [413]5/2+ $\alpha =-$1/2 bands were confirmed and extended up to high spins and two bandcrossings are observed in the latter at $\hbar
\omega $=0.33 and 0.44 MeV, respectively. The bandcrossings and configurations of these bands are discussed by TRS and CSM calculations. In a $\gamma -\gamma -t$ measurement, the 11/2- and 7/2- levels were identified as two isomers with half-lives of 59.4$\pm $20 ns and 16.5$\pm $8.0 ns, respectively.

PACS
21.10.Re Collective levels and giant resonances - 23.20.Lv Gamma transitions and level energies - 27.60.+j $90 \leq A \leq 149$


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