Electric-dipole transition probabilities between yrast bands in Gd-157

摘要

High-spin states of the stable Gd-157 nucleus were studied by a gamma-gamma coincidence measurement using multiple Coulomb excitation with a Xe-136 beam. Two rotational bands of the opposite parity coexisting along the yrast line were extended up to 29/2(-) and 29/2(+), respectively, one of which was of a nuh(9/2) configuration and the other was of a nui(13/2) configuration. Fifteen E1 transitions from the nuh(9/2) band to the vi(13/2) band were observed. Absolute reduced transition probabilities, B(E1), of these transitions were derived from the branching ratios obtained in this experiment and the lifetimes measured in our previous experiment. The B(E1) values ranged between 0.36 x 10(-4) and 5.2 x 10(-4) [e(2)fm(2)]. This enhancement could be explained by introducing a parameter which effectively takes into account the octupole softness. It was also found that the matrix elements of the E1 transitions had a term proportional to I-f (I-f + 1) - I-i (I-i + 1) understood in terms of Coriolis mixing. (C) 2002 Elsevier Science B.V. All rights reserved. [References: 36]