Reducibility and Thermal and Mass Scaling in Angular Correlations from Multifragmentation Reactions.

Abstract

Intermediate-mass-fragment (IMF, 3 {le} Z {le} 20) emission probabilities and IMF charge distributions were recently shown to be reducible to the corresponding one fragment quantities. Furthermore, a strong thermal scaling was shown to control the energy dependence of the same quantities. The multifragmentation scenario painted by these experimental observations is that of a process controlled by a largely independent emission of individual fragments, which, in turn is dominated by phase space. Fragment-fragment angular correlations have been used to study the space-time extension of the emitting source. In particular, small angle repulsion (the Coulomb hole) has been interpreted in terms of the Coulomb repulsion of fragments emitted near each other, both in space and time. We will show in this paper that, except at small angles, the particle-particle angular correlations and their dependence on excitation energy are interpretable in terms of nearly independently emitted fragments whose angular distributions are controlled by phase space. Thus we show that the angular correlations are reducible and thermally scalable. A mass scaling of the angular correlations will also be demonstrated and its possible implications discussed.