Multifragmentation vs. Evaporation vs. Binary-Decay in Fragment Production

Abstract

This paper presents part of an internal LANL Progress Report on completion of the "S" and "G" versions of the improved Cascade-Exciton Model (CEM03.01) and the Los Alamos Quark-Gluon String Model (LAQGSM.03.01) codes. The "S" versions consider fragmentation of compound nuclei produced after the preequilibrium stage of reactions for excitation energies above 2A MeV using the Statistical Multifragmentation Model (SMM) by Botvina et al. ("S" stands for SMM), while the "G" versions describe evaporation/fission stages of reactions using the fission-like binary-decay model GEMINI of Charity et al. ("G" stands for GEMINI) instead of using the the Generalized Evaporation Model GEM2 of Furihata incorporated into the standard versions of these codes. We present here an analysis of the recent 660 MeV p + 129I and 3.65 GeV p + 112Sn JINR measurements, of the new COSY data on 1.2 GeV p + (13 nuclei from Al to Th), of the 300 MeV and 1 GeV p + 56Fe data measured at GSI in inverse kinematics, and of the new GSI data on 1 GeV/nucleon 124Xe and 136Xe + Pb. To better understand the mechanisms of fragment production, we discuss several calculated but not-yet-measured kinematic characteristics of products of these reactions, which are predicted to be quite different by SMM, GEMINI, and GEM2. We find these kinematic quantities to be potentially useful in differentiating these reaction mechanisms if they can be measured in future experiments.