Bimodality in spectator fragmentation

This work has been motivated by the presently ongoing discussion of whether bimodality in the thermodynamic sense can be observed in fragmentation reactions and whether one can argue in favour of its providing direct evidence for the first-order character of the nuclear liquid-gas phase transition [1]. Bimodality occurs if non-negligible surface interactions at the phase boundary lead to a convex entropy function in the transition region. Canonical sampling near the transition temperature will then produce two distinct event classes with large differences in the order parameter of the transition [2, 3].