Persistence of Vibrational Collectivity in Nuclear Level Densities

Abstract

By applying the particle-number projection to the finite-temperature BCS theory to the state densities in the rare-earth nuclei and comparing its results to the SMMC ones, we investigate effects of the particle-number conservation on the collective enhancement factor for the state densities. Once we restore the particle-number conservation, the rapid decay of vibrational enhancement disappears. This suggests that the vibrational collectivity may survive up to higher energy and the relevant enhancement factor is insensitive to the excitation energy.