Rotational bands in Odd-Odd $^{180}$Ir

Y.H. Zhang; T. Hayakawa; M. Oshima; J. Katakura; Y. Hatsukawa; M. Matsuda; H. Kusakari; M. Sugawara; T. Komatsubara

EPJ

Rotational bands in Odd-Odd ¹⁸⁰Ir

Y.H. Zhang^1,2 - T. Hayakawa¹ - M. Oshima¹ - J. Katakura¹ - Y. Hatsukawa¹ - M. Matsuda¹ - H. Kusakari³ - M. Sugawara⁴ - T. Komatsubara⁵

¹ Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195, Japan
² Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, P.R.China
³ Chiba University, Inage-ku, Chiba 263-8512, Japan
⁴ Chiba Institute of Technology, Narashino, Chiba 275-0023, Japan
⁵ Institute of Physics and Tandem Accelerator Center, University of Tsukuba, Ibaraki 305-0006, Japan

Received: 26 April 1999 / Revised version: 24 May 1999 Communicated by B. Herskind

Abstract
High spin states in ¹⁸⁰Ir have been studied via ¹⁵⁴Sm(³¹P,5n $\gamma$ )¹⁸⁰Ir reaction through excitation functions, X- $\gamma$ and $\gamma$ - $\gamma$ -t coincidence measurements. Three rotational bands are identified including a doubly decoupled band, a semi-decoupled one, and a coupled structure up to (26⁺). The quasiparticle configurations associated with these bands are suggested according to in-band B(M1)/B(E2) ratios and band structures of neighboring odd-odd nuclei. Signature inversion in the semidecoupled band is discussed relying on systematics.

PACS
21.10.Re Collective levels - 23.20.Lv Gamma transitions and level energies - 27.70.+q $150\!\leq\!A\!\leq\!189$