Emission of forward neutrons by 158A GeV indium nuclei in collisions with Al, Cu, Sn and Pb

TL;DR

This study measures the cross sections for forward neutron emission in 158A GeV indium collisions with various targets, comparing results with models to understand electromagnetic and hadronic fragmentation processes.

Contribution

It provides new experimental cross section data for neutron emission in high-energy indium collisions and compares these with theoretical models, highlighting differences in fragmentation mechanisms.

Findings

Measured neutron emission cross sections align with RELDIS model predictions.

In-Al collisions show larger cross sections due to hadronic fragmentation.

Results improve understanding of electromagnetic versus hadronic fragmentation in heavy-ion collisions.

Abstract

The cross sections of forward emission of one, two and three neutrons by 158A GeV 115In nuclei in collisions with Al, Cu, Sn and Pb targets are reported. The measurements were performed in the framework of the ALICE-LUMI experiment at the SPS facility at CERN. Various corrections accounting for the absorption of beam nuclei and produced neutrons in target material and surrounding air were introduced. The corrected cross section data are compared with the predictions of the RELDIS model for electromagnetic fragmentation of 115In in ultraperipheral collisions, as well as with the results of the abrasion-ablation model for neutron emission in hadronic interactions. The measured neutron emission cross sections well agree with the RELDIS results, with the exception of In-Al collisions where the measured cross sections are larger compared to RELDIS. This is attributed to a relatively large contribution of hadronic fragmentation of In on Al target with respect to electromagnetic fragmentation, on the contrary to similar measurements performed earlier with 30A GeV 208Pb colliding with Al.