Nuclear (multi-)fragmentation

10th International Conference on Clustering Aspects of Nuclear Structure and Dynamics

Raduta, Adriana R.^1

National Institute for Nuclear Physics and Engineering (IFIN-HH), RO-077125 Bucharest, Romania^1

关键词: Coherent understanding;    Finite size effect;    First-order phase transitions;    Intermediate mass fragments;    Liquid-gas phase transition;    Nuclear equation of state;    Second-order phase transition;    Statistical ensembles;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/436/1/012076/pdf
DOI  :  10.1088/1742-6596/436/1/012076

来源: IOP

【 摘 要 】

Nuclear (multi-)fragmentation, defined as the nuclear decay mechanism in which at least three intermediate mass fragments (Z ≥ 3) are produced, is the disassembly phenomenon specific to hot nuclear matter produced in nuclear collisions at beam energies of 20-100 MeV/nucleon. Considered as the manifestation of the liquid-gas phase transition predicted by nuclear matter mean-field models or an instrument to address the nuclear equation of state, it enjoys for thirty years a vivid scientific interest and motivates the construction of more and more high-performance 4π-detectors allowing for almost complete reaction characterisation on an event-by-event basis. Over the years, many experimental signatures of first- and second-order phase transitions have been proposed and identified in both central and peripheral collisions. Despite their seemingly puzzling messages, coherent understanding of multifragmentation is possible accounting for statistical ensemble inequivalence and finite size effects. Two particular situations will be discussed in detail. The first one corresponds to a multifragmenting medium size nucleus where the expected first-order phase transition is blurred by surface effects. The second one corresponds to an infinitely large system, the clusterized nuclear matter thought to constitute the main sector of baryonic matter in (proto-)neutron stars, where the first-order phase transition is quenched by Coulomb effects. In both cases statistical models with cluster degrees of freedom have been employed.