Free energy and criticality in the nucleon pair breaking process

Abstract

Experimental level densities for 171,172Yb, 166,167Er, 161,162Dy, and 148,149Sm are analyzed within the microcanonical ensemble. In the even isotopes at excitation energies E < 2 MeV, the Helmholtz free energy F signals the transition from zero to two quasiparticles. For E > 2 MeV, the odd and even isotopes reveal a surprisingly constant F at a critical temperature Tc of appr. 0.5 MeV, indicating the continuous melting of nucleon Cooper pairs as function of excitation energy.

11 pages, including 6 figures, to be published in Physical Review C

Cited by in corpus (5)

• Thermodynamics of pairing in mesoscopic systems
• Thermodynamics of nuclei in thermal contact
• Evidence for the pair-breaking process in 116,117Sn
• Influence of complete energy sorting on the characteristics of the odd-even effect in fission-fragment element distributions
• Diagrammatic calculation of thermodynamical quantities in nuclear matter