Probing the statistical decay and alpha-clustering effects in 12c+12c and 14n+10b reactions

TL;DR

This study investigates statistical decay and alpha-clustering effects in light nuclei through fusion-evaporation reactions, revealing out-of-equilibrium emissions and persistent cluster correlations above decay thresholds.

Contribution

It provides new experimental data and analysis on nuclear level densities and clustering phenomena in light nuclei, enhancing understanding of nuclear structure at high excitation energies.

Findings

Evidence of out-of-equilibrium emission linked to entrance channel effects

Persistence of cluster correlations above Mg decay threshold

Constraints on nuclear level density for light systems

Abstract

An experimental campaign has been undertaken at INFN Laboratori Nazionali di Legnaro, 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. A first reaction 12C+12C at 7.9 AMeV beam energy has been measured, using the GARFIELD+Ring Counter experimental setup. Fusion-evaporation events have been exclusively selected. 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 emission has been evidenced and attributed both to entrance channel effects 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 alphas decay. The 24Mg compound nucleus has been studied with a new measurement 14N + 10B at 5.7 AMeV. The comparison between the two datasets would allow us to further constrain the level density of light nuclei. Deviations from a statistical behaviour can be analyzed to get information on nuclear clustering.