Probing the Statistical Decay and α-clustering effects in ¹²C + ¹²C and ¹⁴N + ¹⁰B reactions

¹ Dipartimento di Fisica e Astronomia dell’Università and INFN, Sezione di Bologna, Bologna, Italy
² Dipartimento di Fisica dell’Università and INFN, sezione di Pavia, Pavia, Italy
³ CNRS, UMR6534, LPC, Caen, France and ENSICAEN, UMR6534, LPC, Caen, France
⁴ INFN, Laboratori Nazionali di Legnaro, Legnaro (Padova), Italy
⁵ University of Nevsehir, Science and Art Faculty, Physics Department, Nevsehir, Turkey
⁶ INFN, Sezione di Padova„ Padova, Italy
⁷ Dipartimento di Fisica dell’Università and INFN, Sezione di Firenze, Firenze, Italy

^a e-mail: luca.morelli@bo.infn.it

Published online: 20 March 2014

Abstract

An experimental campaign has been undertaken at Laboratori Nazionali di Legnaro (LNL INFN), Italy, in order to progress in our understanding of the statistical properties of light nuclei at excitation energies above particle emission threshold, by measuring exclusive data from fusion-evaporation reactions. On the experimental side, a first reaction: ¹²C+¹²C at 95 MeV beam energy has been measured, using the GARFIELD + Ring Counter (RCo) apparatuses. Fusion-evaporation events have been exclusively selected out of the entire data set. The comparison to a dedicated Hauser-Feshbach calculation allows us to give constraints on the nuclear level density at high excitation energy for light systems ranging from C up to Mg. Out-of-equilibrium aα emission has been evidenced and attributed both to an entrance channel effect (favoured by the cluster nature of reaction partners), and, in more dissipative events, to the persistence of cluster correlations well above the ²⁴Mg threshold for 6 α’s decay. In order to study the same ²⁴Mg compound nucleus at similar excitation energy with respect to this first reaction a new measurement, ¹⁴N + ¹⁰B at 5.7 A.MeV, was performed at LNL laboratories with the same experimental setup. The comparison between the two systems would allow us to further constrain the level density of light nuclei in the mass-excitation energy range of interest. In this perspective, deviations from a statistical behaviour can be used as a tool to get information on nuclear clustering, both in the ground-state for projectile and target and in the hot source formed in the collision.