78Kr高自旋态的形状共存

用熔合蒸发反应 58Ni(2 3Na,3p) (Ein=70 Me V)和 58Ni(2 8Si,α4p) (Ein=1 30 Me V)研究了78Kr的高自旋态 ,用美国劳伦斯伯克利国家实验室的γ球测量了实验中产生的瞬时符合事件,对新发现的一个负宇称带用多普勒位移衰减法对 1 0 0 4 ke V(1 0 -→ 8-)和 873ke V(8-→ 6-)作了多普勒展宽谱线形状测量 .得到了负宇称带 1 0 -态能级的寿命τ=(2 .2± 0 .3) ps,8-态能级的寿命τ=(1 .6± 0 .2 ) ps.故可知此负宇称带呈现长椭形变 ,与正宇称带的扁椭形变形状共存. Doppler shift attenuation lifetime measurements were performed in the 58 Ni( 23 Na,3p) reaction at 70 MeV and 58 Ni( 28 Si, α4p) reaction at 130 MeV. By analyzing the Doppler broadened line shapes of the 1 004 keV(10 -→8 -) negative parity transition in coincidence with depopulating transitions, the lifetime of the 10 - state has been deduced as τ =(2.2±0.3) ps. A similar analysis of 873 keV(8 -→6 -)transition gave values of τ =(1.6±0.2)...

Prolate and Oblate Shapes Coexist in 78Kr

Doppler-shift-attenuation lifetime measurements were performed in the 58Ni(23Na, 3p) reac tion at 70 MeV and 58Ni(28Si, α4p) reaction at 130 MeV. By analyzing the Doppler-broadened line shapes of the 1 004 keV (10-→8-) negative-parity transition in coincidence with depopulating transitions, the lifetime of the 10 state has been deduced as τ=(2.2±0.3) ps. A similar analysis of 873 keV (8￣→6￣)transi-tion gave values of τ＝(1. 6±0. 2) ps for the 8-state. The measured level lifetimes support the nearly prolate shape of the negative-parity band. In contrast to an oblate shape for the yrast band, we suggest that prolate and oblate shapes coexist in 78Kf.