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Description
Understanding the momentum distributions of the spectator fragments in relativistic nuclear collisions, such as those in the BM@N experiment (NICA), helps to estimate the acceptance of the zero-degree calorimeters and other forward detectors. BM@N is equipped with FHCal and SciWall, which can detect spectator nucleons and at least some spectator fragments [1]. In order to simulate this response, one needs the model which provides realistic momentum distributions of the spectator fragments.
In this work we use the Abrasion-Ablation Monte Carlo for Colliders (AAMCC-MST) model [2] with and without MST clustering as the pre-equilibrium fragmentation model to simulate the production of spectator fragments [3]. The Goldhaber model [4] is used to account for the intranuclear motion of the removed nucleons. The momentum distributions of the spectator fragments were simulated and validated with data from the KLMM collaboration [5, 6]. Then, the momentum distributions of spectator neutrons, protons, hydrogen and helium fragments, light and heavy fragments in 124Xe+CsI collisions at BM@N were calculated for different centrality ranges. It was found that accounting for pre-equilibrium fragmentation increases the mean transverse momentum pT of the spectator fragments and improves agreement with the experimental data.
References
1. M. Kapishin et al., Studies of baryonic matter at the BM@N experiment (JINR). Nuclear Physics A. 982, 967-970 (2019)
2. Svetlichnyi, A.O., Pshenichnov, I.A. Formation of Free and Bound Spectator Nucleons in Hadronic Interactions between Relativistic Nuclei. Bull. Russ. Acad. Sci. Phys. 84, 911–916 (2020)
3. Nepeivoda R, Svetlichnyi A, Kozyrev N, Pshenichnov I. Pre-Equilibrium Clustering in Production of Spectator Fragments in Collisions of Relativistic Nuclei. Particles. 2022; 5(1):40-51
4. A.S. Goldhaber, Statistical models of fragmentation processes. Physics Letters B. 53, 306-308 (1974)
5. M. L. Cherry et al., Fragmentation of the Pb projectile at 158 GeV/nucleon in Pb–Pb interaction. Acta Physica Polonica B. 29, 2155 – 2175 (1998)
6. KLMM Collaboration., Cherry, M.L., Dąbrowska, A. et al. Interactions of 10.6 GeV/nucleon gold nuclei in nuclear emulsion. Z. Phys. C - Particles and Fields 62, 25–29 (1994)
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