Evidence for abnormal M1 transition in 187Pt

Abstract

Gamma-gamma angular correlation measurements have been performed in 187Pt in order to determine the spin values of the states connected by the highly converted transitions. For one of these transitions, we have determined that the spin values of the initial and final states are different, which implies abnormal M1 multipolarity for this highly converted transition. In that case the deduced penetration parameters have especially high absolute values. Moreover we have determined uniquely the spin value of most of the excited states below 800 keV. The occurence of highly converted transitions in 187Pt is examined and the low-spin negative-parity levels are discussed in terms of shape coexistence.