Nuclear pairing at finite temperature and angular momentum

Abstract

We propose an approach to nuclear pairing at finite temperature and angular momentum. This approach includes the effects due to the quasiparticle‐number fluctuation and dynamic coupling to pair vibrations within the self‐consistent quasiparticle random‐phase approximation. The pairing gaps, total energies, and heat capacities are calculated within a doubly folded multilevel model as well as several realistic nuclei. The results obtained show that, in the region of moderate and strong couplings, the sharp transition between the superconducting and normal phases is smoothed out. This is manifested in a thermal pairing gap, which does not collapse at a critical temperature predicted by the conventional Bardeen‐Cooper‐Schrieffer’s (BCS) theory, but has a tail extended to high temperatures. Moreover, this approach also predicts the appearance of a thermally assisted pairing at finite angular momentum. The effect of backbending of the momentum of inertia as a function of the square of angular velocity is also discussed.