Speaker
Description
The first experimental results from the ALICE Collaboration on the emission of forward protons accompanied by neutrons in ultraperipheral $^{208}$Pb–$^{208}$Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV are presented. While electromagnetic dissociation (EMD) events with low neutron multiplicities are predominant at the LHC energies, the cross sections for the emission of one, two, and three protons are comparable to or exceed the total hadronic cross section. These cross sections were measured using the ALICE Zero Degree Calorimeters (ZDCs). According to the Relativistic ELectromagnetic DISsociation (RELDIS) model, these proton emission cross sections serve as upper limits for the production of the respective secondary nuclei, Tl, Hg, and Au, in the EMD of $^{208}$Pb. The cross sections of the emission of a single proton along with one, two, or three neutrons were also measured, which correspond to the production of specific thallium isotopes,$^{206,205,204}$Tl. These results provide novel information for tuning and validating various EMD models. Ultimately, a comprehensive understanding of the production of secondary nuclei delivers crucial insights into beam intensity decay and beam losses at the LHC and future ion colliders.
| Track | Heavy Ions |
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