Post breakup dynamical evolution of fragments produced in nuclear multifragmentation

Abstract

The deexcitation of the primary hot fragments, produced in the breakup of an excited nuclear source, during their propagation under the influence of their mutual Coulomb repulsion is studied in the framework of a recently developed hybrid model. The latter is based on the Statistical Multifragmentation Model (SMM), describing the prompt breakup of the source, whereas the particle emission from the hot fragments, that decay while traveling away from each other, is treated by the Weisskopf-Ewing evaporation model. Since this treatment provides an event by event description of the process, in which the classical trajectories of the fragments are followed using molecular dynamics techniques, it allows one to study observables such as two-particle correlations and infer the extent to which the corresponding observables may provide information on the multifragment production mechanisms. Our results suggest that the framework on which these treatments are based may be considerably constrained by such analyses. Furthermore, they imply that information obtained from these model calculations may provide feedback to the theory of nuclear interferometry. We also found that neutron deficient fragments should hold information more closely related to the breakup region than neutron rich ones, as they are produced in much earlier stages of the post breakup dynamics than the latter.

Isoscaling constraining sources' sizes

“…To this end, we employ the decay model described in Refs. [34,35], based on the Weisskopf-Ewing treatment [36]. In order to attenuate the statistical fluctuations, 50 million primary events have been generated with SMM [13] and the corresponding fragments allowed to deexcite through this Monte Carlo treatment on an event by event basis.…”

Isoscaling in central Sn+Sn collisions at 270 MeV/u

“…In order to check the extent to which the isoscaling properties observed experimentally may be understood in a scenario in which a thermal equilibrated source is formed and undergoes a prompt breakup, we employ the canonical version of the SMM model described in Refs. [16,55]. Many different sources contribute to the actual data whereas a single source is employed in the calculation due to the computational effort needed to generate a source distribution.…”

Isobar correlations bearing information on the properties of hot disassembling nuclear sources

“…A continuous fragment production, during a short time span in the expansion phase, is suggested by other dynamical calculations [12,39] as an alternative view. These two frameworks have also been merged into a hybrid treatment [40,41] in which excited fragments are created in a prompt breakup within a breakup volume and slowly deexcite as they travel away from each other due to their initial thermal and (possibly) flow velocities, besides the Coulomb repulsion among them.…”