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Challenge of nuclear transmutation in heavy-ion colliders

I. A. Pshenichnov, S. D. Savenkov, A. O. Svetlichnyi

TL;DR

This work investigates secondary-nucleus production from nuclear transmutation in relativistic heavy-ion collisions by comparing hadronic fragmentation and electromagnetic dissociation (EMD) across light and heavy systems. Using the AAMCC-MST framework for hadronic fragmentation and the RELDIS model for EMD, it quantifies cross sections and momentum distributions for light systems such as $^{16}$O and $^{20}$Ne at LHC, and for $^{124}$Xe at NICA, highlighting a crossover: hadronic fragmentation dominates for light nuclei while EMD dominates for very heavy systems. For $^{20}$Ne--$^{20}$Ne, forward-going fragments with $Z/A=1/2$ (e.g., $^4$He, $^{12}$C, $^{14}$N, $^{16}$O) carry non-negligible cross sections and could contaminate $^{20}$Ne data, whereas in $^{208}$Pb--$^{208}$Pb and $^{124}$Xe--$^{124}$Xe the secondary products do not share an exact $Z/A$ with the beam, reducing contamination risk. The results inform beam-control and collimation strategies by clarifying when and how transmutation products may influence collider operations at LHC and NICA.

Abstract

We investigate the production of secondary nuclei in the hadronic fragmentation and electromagnetic dissociation (EMD) of $^{20}$Ne beams at the LHC and $^{124}$Xe beams at NICA. For light nuclei at LHC energies, our calculations show that hadronic interactions are the dominant channel for nuclear transmutation. This contrasts with the previously established dominance of EMD in $^{208}$Pb-$^{208}$Pb collisions. For $^{20}$Ne-$^{20}$Ne collisions at $\sqrt{s_{\rm NN}}=5.36$ TeV, we provide calculated cross sections and momentum distributions of produced nuclei such as $^4$He, $^{12}$C, $^{14}$N, and $^{16}$O. These results are essential for assessing potential contamination of the $^{20}$Ne-$^{20}$Ne event sample by collisions involving other nuclear species. Secondary nuclei will be also produced in the EMD of $^{124}$Xe beams at NICA, but they will not contaminate $^{124}$Xe-$^{124}$Xe data.

Challenge of nuclear transmutation in heavy-ion colliders

TL;DR

This work investigates secondary-nucleus production from nuclear transmutation in relativistic heavy-ion collisions by comparing hadronic fragmentation and electromagnetic dissociation (EMD) across light and heavy systems. Using the AAMCC-MST framework for hadronic fragmentation and the RELDIS model for EMD, it quantifies cross sections and momentum distributions for light systems such as O and Ne at LHC, and for Xe at NICA, highlighting a crossover: hadronic fragmentation dominates for light nuclei while EMD dominates for very heavy systems. For Ne--Ne, forward-going fragments with (e.g., He, C, N, O) carry non-negligible cross sections and could contaminate Ne data, whereas in Pb--Pb and Xe--Xe the secondary products do not share an exact with the beam, reducing contamination risk. The results inform beam-control and collimation strategies by clarifying when and how transmutation products may influence collider operations at LHC and NICA.

Abstract

We investigate the production of secondary nuclei in the hadronic fragmentation and electromagnetic dissociation (EMD) of Ne beams at the LHC and Xe beams at NICA. For light nuclei at LHC energies, our calculations show that hadronic interactions are the dominant channel for nuclear transmutation. This contrasts with the previously established dominance of EMD in Pb-Pb collisions. For Ne-Ne collisions at TeV, we provide calculated cross sections and momentum distributions of produced nuclei such as He, C, N, and O. These results are essential for assessing potential contamination of the Ne-Ne event sample by collisions involving other nuclear species. Secondary nuclei will be also produced in the EMD of Xe beams at NICA, but they will not contaminate Xe-Xe data.
Paper Structure (5 sections, 2 figures, 1 table)

This paper contains 5 sections, 2 figures, 1 table.

Table of Contents

  1. Introduction
  2. Modeling hadronic fragmentation and EMD of relativistic nuclei
  3. $^{208}$Pb--$^{208}$Pb Collisions at the LHC
  4. $^{20}$Ne--$^{20}$Ne collisions at the LHC
  5. $^{124}$Xe--$^{124}$Xe Collisions at NICA

Figures (2)

  • Figure 1: Longitudinal momentum distributions of secondary $^4$He and $^{16}$O nuclei produced in hadronic fragmentation in $^{20}$Ne--$^{20}$Ne collisions at $\sqrt{s_{\rm NN}}=5.36$ TeV.
  • Figure 2: Cross sections to produce secondary nuclei with a given charge-to-mass ratio $Z/A$ in EMD of $^{124}$Xe nuclei in their ultraperipheral collisions at $\sqrt{s_{\rm NN}}=9.5$ GeV at NICA. The $Z/A$ ratio for $^{124}$Xe beam nuclei is marked by a dashed line