Negative heat capacity for hot nuclei: confirmation with formulation from the microcanonical ensemble

Abstract

By using freeze-out properties of multifragmenting hot nuclei produced in quasifusion central ${}^{129}$Xe+${}^{nat}$Sn collisions at different beam energies (32, 39, 45 and 50 AMeV) which were estimated by means of a simulation based on experimental data collected by the $4\pi$ INDRA multidetector, heat capacity in the thermal excitation energy range 4 - 12.5 AMeV was calculated from total kinetic energies and multiplicities at freeze-out. The microcanonical formulation was employed. Negative heat capacity which indicates a first order phase transition for finite systems is observed and confirms previous results using a different method.

Comments: 7 pages with 5 figures. arXiv admin note: substantial text overlap with arXiv:2010.02736