Pairing within the self-consistent quasiparticle random-phase approximation at finite temperature
- Heavy-Ion Nuclear Physics Laboratory, RIKEN Nishina Center for Accelerator-Based Science, 2-1 Hirosawa, Wako City, 351-0198 Saitama (Japan)
An approach to pairing in finite nuclei at nonzero temperature is proposed, which incorporates the effects due to the quasiparticle-number fluctuation (QNF) around Bardeen-Cooper-Schrieffer (BCS) mean field and dynamic coupling to quasiparticle-pair vibrations within the self-consistent quasiparticle random-phase approximation (SCQRPA). The numerical calculations of pairing gap, total energy, and heat capacity were carried out within a doubly folded multilevel model as well as realistic nuclei {sup 56}Fe and {sup 120}Sn. The results obtained show that, under the effect of QNF, in the region of moderate and strong couplings, the sharp transition between the superconducting and normal phases is smoothed out, resulting in a thermal pairing gap, which does not collapse at the BCS critical temperature, but has a tail, which extends to high temperature. The dynamic coupling of quasiparticles to SCQRPA vibrations significantly improves the agreement with the results of exact calculations and those obtained within the finite-temperature quantal Monte Carlo method for the total energy and heat capacity. It also causes a deviation of the quasiparticle occupation numbers from the Fermi-Dirac distributions for free fermions.
- OSTI ID:
- 21191943
- Journal Information:
- Physical Review. C, Nuclear Physics, Vol. 77, Issue 6; Other Information: DOI: 10.1103/PhysRevC.77.064315; (c) 2008 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2813
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BCS THEORY
COUPLING
CRITICAL TEMPERATURE
DISTRIBUTION
FERMIONS
FLUCTUATIONS
IRON 56
MEAN-FIELD THEORY
MONTE CARLO METHOD
PAIRING ENERGY
PAIRING INTERACTIONS
QUASI PARTICLES
RANDOM PHASE APPROXIMATION
SIMULATION
SPECIFIC HEAT
TEMPERATURE RANGE 0400-1000 K
TIN 120