Effects of geometric constraints on the nuclear multifragmentation process

TL;DR

This paper investigates how geometric constraints in nuclear multifragmentation influence fragment production, collective flow, and temperature, revealing complex correlations and effects not captured by unconstrained models.

Contribution

It introduces finite size and volume constraints into statistical models, showing their significant impact on fragmentation modes and observable properties.

Findings

Constraints suppress collective flow energy.

Nontrivial correlation between temperature and expansion velocity.

Fragmenting temperature can increase with expansion velocity.

Abstract

We include in statistical model calculations the facts that in the nuclear multifragmentation process the fragments are produced within a given volume and have a finite size. The corrections associated with these constraints affect the partition modes and, as a consequence, other observables in the process. In particular, we find that the favored fragmenting modes strongly suppress the collective flow energy, leading to much lower values compared to what is obtained from unconstrained calculations. This leads, for a given total excitation energy, to a nontrivial correlation between the breakup temperature and the collective expansion velocity. In particular we find that, under some conditions, the temperature of the fragmenting system may increase as a function of this expansion velocity, contrary to what it might be expected.