Multiple-Scattering Model for Inclusive Proton Production in Heavy Ion Collisions

A formalism is developed for evaluating the momentum distribution for proton production in nuclear abrasion during heavy ion collisions using the Glauber multiple-scattering series. Several models for the onebody density matrix of nuclei are considered for performing numerical calculations. Calculations for the momentum distribution of protons in abrasion are compared with experimental data for inclusive proton production. Introduction The prediction of the secondary distribution of particles produced in heavy ion collisions is required for performing cosmic-ray transport calculations (ref. 1). The fragmentation cross sections in heavy ion reactions may be described in the abrasionablation models in which abrasion describes the knockout of nucleons and clusters during the projectile and target overlap and ablation describe the deexcitation of the projectile or target remnants. The abrasion cross sections are typically described using a geometric model (ref. 2) or semiclassical methods based on the Glauber or eikonal approximation (refs. 3{5). In this report we consider the use of the Glauber multiple-scattering model for formulating the proton momentum distribution from abrasion. This formalism will be useful for obtaining both a better understanding of the physics of nuclear abrasion and estimates of secondary yields of light particles from direct processes. We will also relate the inclusive nucleon scattering observables to the internal nuclear density matrix that di ers from the intranuclear cascade (ref. 6) or hydrodynamic model (ref. 7) descriptions of these observables. The calculations may then provide tests on nuclear structure calculations for the internal momentum distribution when all secondary nucleon mechanisms are considered. The same formalism describes proton or neutron production from nuclear abrasion; however, because of increased multiplicity for evaporation neutrons as compared with that of protons, we present calculations for proton production in this report. Several mechanisms for proton (or neutron) production occur in heavy ion collisions. Figure 1 illustrates the mechanisms for proton production in nucleon-induced reactions. The contributions from the scattering of the incident nucleon from the target ground and low-lying excited states are close to the beam energy. Below the beam energy we nd, rst, the quasi-elastic peak where the projectile has knocked target nucleons into continuum states, and this is followed by the nucleon excitation peak which Quasi-elastic Elastic scattering Nucleon resonances Evaporations and cascades 104