Distributions of the largest fragment size in multifragmentation: Traces of a phase transition

TL;DR

This paper analyzes the largest fragment size distributions in nuclear multifragmentation, using statistical measures and a percolation model to identify phase transition signatures in experimental data.

Contribution

It introduces the use of skewness and kurtosis of fluctuations to detect phase transition points and validates a bond percolation model against experimental fragmentation data.

Findings

Identification of the transition point via skewness and kurtosis measures

Percolation model accurately reproduces fragmentation distributions

Evidence of pseudocritical and critical points in data

Abstract

Distributions of the largest fragment charge are studied using the ALADIN data on fragmentation of $^{197}$Au projectiles at relativistic energies. The statistical measures skewness and kurtosis of higher-order fluctuations provide a robust indication of the transition point, linked to a phase transition in the thermodynamic limit. Extensive comparisons with predictions of a bond percolation model corroborate the high accuracy of this model in reproducing the distributions as well as the whole fragmentation pattern as represented by the measured charge correlations. In analogy to percolation, the pseudocritical and critical points are identified in the fragmentation data. Questions concerning the distinction between different models and between first- and second-order phase transitions are discussed.