Thermal properties of N=40 isotones

摘要

Using the shell-model Monte Carlo method, we study the thermal properties of four N = 40 medium-mass nuclei: Ni-68, a substantially spherical and weakly paired nucleus; Zn-70, a superfluid spherical nucleus; Ge-72, a superfluid deformed nucleus which exhibits shape-coexistence; and the well-deformed, weakly-paired nucleus Zr-80. We investigate the competition between shape deformations and pairing correlations as a function of temperature. We find that shape and pairing changes contribute to the specific heat of the nucleus in a different way. While the superfluid-to-normal transition manifests itself as a pronounced peak in the specific heat around T = 0.6-0.7 MeV, the deformed-to-spherical transition is more gradual. (c) 2005 Elsevier B.V. All rights reserved.