Negative heat capacity for hot nuclei using formulation from the microcanonical ensemble INDRA Collaboration

TL;DR

This study investigates the heat capacity of hot nuclei during multifragmentation, revealing negative heat capacity indicative of a first-order phase transition, using a microcanonical ensemble approach based on experimental data.

Contribution

It applies a microcanonical formulation to experimental data to demonstrate negative heat capacity in hot nuclei, confirming phase transition evidence with a new method.

Findings

Negative heat capacity observed in hot nuclei.

Confirms first-order phase transition in finite nuclear systems.

Validates previous results with an alternative approach.

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 signs a first order phase transition for finite systems is observed and confirms previous results using a different method.