Multipole mixing ratios of transitions out of high spin gamma vibrational states in neutron rich Mo, Ru isotopes

Abstract

Current models of nuclear structure describe nuclear states in terms of collective vibrations and rotations of a ground state. - One such quadrupole vibrational band is the gamma-band formed by vibrations of the short sides of a deformed nucleus. - When a nucleus that is in this mode decays to its ground state, the electromagnetic radiation is predicted to be entirely quadrupole in nature. - This prediction has been well documented in a wide range of nuclei. - However, a recent study of neutron rich molybdenum and ruthenium isotopes found a few gamma-band to ground-band transitions that contained almost no quadrupole radiation. - This work utilizes the Gammasphere detector array to examine the angular correlations in the de-excitations of the secondary fission fragments of 252Cf in order to make independent measurements of these results. - This work also uses the same technique to measure the multipole mixing ratios of gamma-band to ground-band transitions originating in states with spin-parity as high as 9+. - The results demonstrate that in these nuclei, electric quadrupole radiation is strongly favored in gamma to ground band transitions as has been predicted by theory.