Selective population of states in fission fragments from the 32S+24Mg reaction.

Abstract

The symmetric and near-symmetric mass fission yields from the $^{32}\mathrm{S}$${+}^{24}$Mg reaction have been studied in a particle-particle-\ensuremath{\gamma} coincidence measurement. Evidence is presented for a selective population of states in $^{28}\mathrm{Si}$ fragments arising from the symmetric fission of the $^{56}\mathrm{Ni}$ compound nucleus. A statistical-model calculation of the expected strength to specific mutual excitations of the fission fragments is presented and compared to the experimental results. This calculation is found to describe the structures observed at high excitation energy in the fission Q-value spectra quite well. Analysis of the \ensuremath{\gamma}-ray spectra indicates, however, that a specific set of states in $^{28}\mathrm{Si}$, corresponding to a highly deformed prolate band, is populated more strongly than expected based on a purely spin-weighted, statistical decay of the compound nucleus. It is suggested that the population pattern of states in the fission fragments may reflect nuclear structure effects at the point of scission.