Eur. Phys. J. A (2020) 56: 101
https://doi.org/10.1140/epja/s10050-020-00109-9

Letter to the Editor

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

¹ Institut de Physique Nucléaire, CNRS/IN2P3, Univ. Paris-Sud, Université Paris-Saclay, Orsay, France
² INFN, Sezione di Firenze, Sesto Fiorentino, Italy
³ SUBATECH, IMT Atlantique, Université de Nantes, CNRS-IN2P3, Nantes, France
⁴ Normandie Univ., ENSICAEN, UNICAEN, CNRS/IN2P3, LPC Caen, Caen, France
⁵ GANIL, (CEA/DRF-CNRS/IN2P3), Caen, France
⁶ Conservatoire National des Arts et Métiers, Paris, France
⁷ Dipartimento di Fisica ‘E. Pancini’ and Sezione INFN, Università di Napoli “Federico II”, Naples, Italy
⁸ INFN, Sezione di Catania, Catania, Italy
⁹ Ecole des Applications Militaires de l’Energie Atomique, Cherbourg, France
¹⁰ Hulubei National Institute for R & D in Physics and Nuclear Engineering (IFIN-HH), Bucharest-Mágurele, Romania
¹¹ Université Laval, Québec, Canada

^* e-mail: borderie@ipno.in2p3.fr

Received: 19 December 2019
Accepted: 1 March 2020
Published online: 1 April 2020

Abstract

By using freeze-out properties of multifragmenting hot nuclei produced in quasifusion central 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 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.