Monte Carlo calculation of high-energy heavy-ion interactions

Abstract

A relativistic Monte Carlo model for high-energy heavy-ion collisions is presented. The interaction process is described as a sequence of classical, binary, on-shell baryon-baryon collisions. Pion production is taken into account by allowing $\ensuremath{\Delta}$ resonance formation. The latter are given a definite mass and a lifetime larger than the collision time. They are, however, allowed to scatter or disappear by collisions with the nucleons. The results of the calculations are compared with experimental results for the inclusive proton and pion cross sections and two-proton correlations in the $^{12}\mathrm{C}$+$^{12}\mathrm{C}$, $^{20}\mathrm{Ne}$+NaF, and $^{40}\mathrm{Ar}$+KCl systems at 800 MeV per nucleon. The predictions of the model agree fairly well with the experimental measurements, except for the low-energy pion cross section, which is underestimated. The relation of this feature to the zero-width mass spectrum of the $\ensuremath{\Delta}$ resonances is briefly discussed. The model is used to separate the direct knockout and the thermal contributions to the proton inclusive cross section. Attention is drawn to the fact that these two contributions are not unambiguously defined.NUCLEAR REACTIONS High-energy heavy-ion collisions; Monte Carlo simulation; calculated proton and pion spectra for $^{12}\mathrm{C}$+$^{12}\mathrm{C}$, $^{20}\mathrm{Ne}$+NaF, and $^{40}\mathrm{Ar}$+KCl at $\frac{E}{A}=800$ MeV.