Peeling away neutron skin in ultracentral collisions of relativistic nuclei

Abstract

In heavy nuclei the ratio between local densities of neutrons and protons increases towards the nuclear periphery. The excess of neutrons is known as the neutron skin (NS) with a subtle difference ($<0.5$~fm) between the r.m.s radii of the distributions of neutrons and protons. We show that the presence of NS in ${}^{208}$Pb leads to extra spectator neutrons in ultracentral ${}^{208}$Pb--${}^{208}$Pb collisions at the CERN SPS and LHC. The yields of spectator neutrons and protons were calculated within a new version of Abrasion-Ablation Monte Carlo for Colliders model (AAMCC-MST) taking into account NS and pre-equilibrium clustering of spectator matter. While the average numbers of spectator neutrons and protons in ultracentral collisions vary insignificantly, the cross sections of emission of certain numbers of spectator neutrons in events with 0,1,...5 spectator protons are changed by 50--250\%, depending on the thickness of NS. These cross sections are less sensitive to other parameters in calculations, and their measurements in the ALICE experiment at the LHC will make it possible to restrict the existing variety of neutron density parameterizations in ${}^{208}$Pb.

arXiv comment23 pages, 14 figures, 5 tables

References in corpus (23)

• Isospin Asymmetry in Nuclei and Neutron Stars
• Neutron Star Structure and the Neutron Radius of 208Pb
• Accurate Determination of the Neutron Skin Thickness of ${}^{208}$Pb through Parity-Violation in Electron Scattering
• Centrality determination of Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV with ALICE
• Neutron skin of ${}^{208}$Pb from Coherent Pion Photoproduction
• Glauber modeling of high-energy nuclear collisions at sub-nucleon level
• Measurement of the cross section for electromagnetic dissociation with neutron emission in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV
• Origin of the neutron skin thickness of 208Pb in nuclear mean-field models
• Analysis of bulk and surface contributions in the neutron skin of nuclei
• A Monte Carlo generator of nucleon configurations in complex nuclei including Nucleon-Nucleon correlations
• Probing the neutron skin with ultrarelativistic isobaric collisions
• Peeling off neutron skins from neutron-rich nuclei: Constraints on the symmetry energy from neutron-removal cross sections
• Initial state anisotropies and their uncertainties in ultrarelativistic heavy-ion collisions from the Monte Carlo Glauber model
• Probing neutron-skin thickness with free spectator neutrons in ultracentral high-energy isobaric collisions
• Neutron skin and centrality classification in high-energy heavy-ion collisions at the LHC
• Neutron skins as laboratory constraints on properties of neutron stars and on what we can learn from heavy ion fragmentation reactions
• Beam Fragmentation in Heavy Ion Collisions with Realistically Correlated Nuclear Configurations
• Neutron removal cross section as a measure of neutron skin
• Spin-isospin correlated configurations in complex nuclei and neutron skin effect in W${}^{\pm }$ production in high-energy proton-lead collisions
• Evolution of the statistical disintegration of finite nuclei toward high energy
• Nuclear expansion with excitation
• The effect of neutron skin on inclusive prompt photon production in Pb~+~Pb collisions at the LHC
• On the performance of Zero Degree Calorimeters in detecting multinucleon events

Cited by in corpus (1)

• Proton emission in ultraperipheral Pb-Pb collisions at $\sqrt{{\text{s}}_{\text{NN}}}=5.02$ TeV