Multifragmentation in Reactions of 1-GeV Protons with Iron Nuclei

Abstract

We use combinations of cascade and nuclear de-excitation models to assess the importance of the inclusion of a multifragmentation stage for the quantitative description of the 1-GeV p + 56 Fe spallation reaction. We discuss the sensitivity of several exclusive physical observables to the de-excitation mechanism in the attempt to identify which of them can be considered suitable probes for a multifragmentation stage. The calculations show that the inclusion of a multifragmentation stage is not necessary to construct an accurate description of the observed data.

Formation and decay of a hot compound nucleus

“…Experimental spallation cross sections have also been found to be well described by a fast but sequential emission process. [30] One can show that a dynamical sequential decay model can also produce the fragment-fragment correlations expected from simultaneous multifragmentation. [31] Here, at least, the decay of a hot equilibrated compound nucleus could be considered to take place through a fast sequential emission process.…”

“…where we take j to be the thermal excitation energy, given by the difference between the total excitation energy and its collective rotational component, 30) with I j the moment of inertia, cA j is the level density parameter, with c ≈ 1/7-1/8 Mev −1 and T j the effective temperature, given by…”