Comparative study of four reactions at onset of pre-equilibrium emission

M Cicerchia ,V L Kravchuk ,G Pasquali ,C Frosin ,N Cieplicka-Oryńczak ,A Olmi ,M Cinausero ,B Fornal ,S Piantelli ,D Gruyer ,G Poggi ,D Mengoni ,S Barlini ,G Collazuol ,M Bruno ,A Caciolli ,M Bini ,I Lombardo ,A Camaiani ,M Dʼagostino ,L Morelli ,T Marchi ,D Dell’aquila ,G Casini ,D Fabris ,N Gelli ,P Ottanelli ,M Degerlier ,G Mantovani ,F Gramegna ,S Leoni ,S Valdré

doi:10.1051/epjconf/201922301010

Abstract

The study of the emitted particles, comparing pre-equilibrium and thermal components, is a useful tool to examine the nuclear structure of emitters. Possible clustering effects, which may change the expected decay chain probability, could be highlighted on the competition between different reaction mechanisms. The NUCL-EX collaboration (INFN, Italy) has carried out an extensive research campaign on pre-equilibrium emission of light charged particles from hot nuclei. In this framework, the reactions 16O+30Si, 18O+28Si, 19F+27Al at 7 AMeV and 16O+30Si at 8 AMeV have been carried out using the GARFIELD+RCo array at Legnaro National Laboratories. Some anomalies in the α-particle emission channels have been evidenced in the measurement reported above, showing in an exclusive way the observed effects related to the entrance channels. The experimental results are compared to model prediction, for which the same filtering and complete event selection have been applied.

Highlights

Improvements in the knowledge of the incomplete fusion reactions have been achieved [1,2,3]; a complete understanding of reaction mechanisms associated with the emission of the particles prior the thermalization, like break-up and preequilibrium emissions, is still missing
The term incomplete fusion has been employed to indicate that, somehow, particles are lost from the projectile and/or target before complete thermalization, which occurs up to the fusion of the remnants
Even in the energy region 5-10 AMeV, fast emission processes have been observed when the structure of the projectile plays an important role in the interaction with the target

Summary

Introduction

Improvements in the knowledge of the incomplete fusion reactions have been achieved [1,2,3]; a complete understanding of reaction mechanisms associated with the emission of the particles prior the thermalization, like break-up and preequilibrium emissions, is still missing. Even in the energy region 5-10 AMeV, fast emission processes have been observed when the structure of the projectile plays an important role in the interaction with the target. This projectile break-up mechanism [6,7,8,9], as well as the pre-equilibrium, influences the following formation and decay of the hot source. The NUCL-EX collaboration (INFN, Italy) has carried out an extensive research campaign on pre-equilibrium emission of light charged particles from hot nuclei [10,11,12,13,14]

The Experiment

The Data Analysis

The Statistical Code

Conclusion