Nuclear Seminar

Pairing in hot rotating nuclei

Dr. N. Quang Hung
RIKEN Nishina Center for Accelerator-Based Science, Saitama, Japan

Monday, November 3, 2008   *3:00 p.m.   NSH 124
(Refreshments served prior to seminar in NSH 124)

Nuclear pairing properties are studied within an approach that includes the quasiparticle-number fluctuation (QNF) and coupling to the quasiparticle-pair vibrations within the self-consistent quasiparticle random-phase approximation (SQRPA) at finite temperature and angular momentum. The numerical calculations are performed within a doubly-folded equidistant multilevel model as well as several realistic nuclei. The results obtained for the pairing gap, total energy and heat capacity show that the QNF smoothes out the sharp super fluid-normal phase transition. As the result, the pairing gaps obtained at various angular momenta do not collapse as predicted by the BCS theory, but decrease monotonously with increasing temperature. The appearance of a thermally assisted pairing gap in rotating nuclei at finite temperature is analyzed. The corrections due to the dynamic coupling to SCQRPA vibrations at different temperatures and angular momenta are found to be significant in light systems, and negligible in medium and heavy systems. The effect of back bending of the momentum of inertia as a function of the square of angular velocity is also discussed.

*PLEASE NOTE DIFFERENT TIME