Modeling fragmentation of ²⁰Ne nuclei at the LHC

Fragmentation of relativistic neon nuclei was studied with the Abrasion-Ablation Monte Carlo for Colliders model (AAMCC-MST), which incorporates pre-equilibrium clustering of spectator matter via a Minimum Spanning Tree (MST) algorithm, subsequent decays of the excited clusters, and Coulomb repulsion between final fragments. After validating the model against data on ²⁰Ne and ²²Ne fragmentation on various targets, the production of spectator nuclear fragments, neutrons, and protons in ²⁰Ne-²⁰Ne collisions at the LHC was modeled at √sNN=5.36 TeV. The production cross sections, transverse and longitudinal momentum distributions for ²H, ⁴He, ⁶Li, ¹⁰B, ¹²C, ¹⁴N, and ¹⁶O fragments were calculated as these fragments may contaminate ²⁰Ne beams circulating in the LHC. A simple parametrization describing relative width of the longitudinal momentum distributions calculated for these fragment species was constructed. To study the sensitivity of results to $α$-clustering and nuclear density distributions in neon nuclei, two density profiles for ²⁰Ne and ²²Ne were used: a deformed Woods-Saxon, and a five-$α$ bi-pyramidal configuration. In addition, a spherical profile was considered for ²⁰Ne. Comparing results obtained with these profiles and with or without MST clustering shows that the calculated yields of spectator nucleons and fragments, their momentum distributions are sensitive to the details of nuclear structure of 20,22Ne and fragmentation modeling. The results provide the input for simulations of the transport of secondary forward nuclei in the LHC to estimate their interaction rates with circulating ²⁰Ne beam nuclei, and also for calculations of responses of neutron and proton Zero Degree Calorimeters to ²⁰Ne-²⁰Ne events.