Measuring deformed neutron skin with free spectator nucleons in relativistic heavy-ion collisions

Abstract

The neutron skin in deformed nuclei is generally not uniformly distributed but has an angular distribution, depending on both the spin-dependent nuclear interaction and the nuclear symmetry energy. To extract the information of the deformed neutron skin, we have explored the possibility of using free spectator nucleons in central tip-tip and body-body collisions at top RHIC energy with four typical deformed nuclei. The density distributions of neutrons and protons are consistently obtained from the Skyrme-Hartree-Fock-Bogolyubov calculation, and the angular distribution of the neutron skin can be varied by adjusting the strength of the nuclear spin-orbit coupling. With the information of spectator nucleons obtained based on a Monte-Carlo Glauber model, the free spectator nucleons are generated from a multifragmentation process. By investigating the results from different systems and with different collision configurations, we found that although it is difficult to probe the deformed neutron skin in ${}^{96}$Zr and ${}^{238}$U by their collisions, it is promising to extract the polar angular distributions of the neutron skin in ${}^{96}$Ru and ${}^{197}$Au by comparing the yield ratios of free spectator neutrons to protons in their central tip-tip and body-body collisions. The proposed observables can be measured by dedicated zero-degree calorimeters in heavy-ion collision experiments that have been carried out in recent years by RHIC.

7 pages, 6 figures

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Cited by in corpus (3)

• Evidence of Hexadecapole Deformation in Uranium-238 at the Relativistic Heavy Ion Collider
• Directly probing existence of $\alpha$-cluster structure in ${}^{20}$Ne by relativistic heavy-ion collisions
• Investigating the possibility of extracting neutron-skin thickness in nuclei by their collisions at intermediate energies