Pairing phase transition in an odd-even hot Zn-69 nucleus

The pairing phase transition in an odd-even hot-rotating Zn-69 nucleus has been investigated by using the reported nuclear level density (NLD) data, which were experimentally extracted from the gamma-gated particle spectra. The experimental NLDs have been compared with those obtained within the microscopic exact pairing plus independent-particle model at finite temperature (EP+IPM) along with the results of other microscopic calculations such as the Hartree-Fock BCS (HFBCS) and Hartree-Fock-Bogoliubov plus combinational (HFBC) methods. It is found that the experimental NLDs can be well described by the EP+IPM using the recommended quadrupole deformation parameter beta (2) = -0.164. Intriguingly, the heat capacity calculated using the EP+IPM NLD exhibits a sharp S-shape, which is not expected in such odd-even hot or hot-rotating system as reported earlier. Changing the deformation parameter beta (2) does not change much this S-shape. However, increasing or decreasing the pairing gaps could enhance or destroy the S-shaped heat capacity. Therefore, the S-shaped heat capacity in odd-even Zn-69 nucleus is explained due to the deformation-induced pairing correlation.