Analysis of phase transitions in hot ^160−164Dy nuclei

Abstract Phase transitions in hot 160−164 Dy isotopes are analyzed using a classification scheme based on the distribution of zeros of the canonical ensemble (CE) partition function in the complex inverse temperature plane. Semi-empirical nuclear level densities (NLD), which are obtained by combining experimental data in the excitation-energy region below the neutron binding energy and the back-shifted Fermi gas model prediction for the high excitation-energy up to 250 MeV, are utilized to determine the CE partition function. Results obtained show that two phase transitions can appear in 160−164 Dy isotopes, namely the pairing phase transition and the shape phase transition. The pairing phase transition is found to be of first-order and its critical temperature is ∼0.5 MeV, while the shape phase transition is found to be also of first-order but it occurs at higher temperatures, i.e. around 2.2–2.5 MeV. A comparison between this work and previous ones that involve the same classification scheme but employ purely theoretical NLD has shown a considerable inconsistency. However, our findings should be more conclusive due to various supports from previous theoretical and experimental studies.