Determine the neutron skin type by relativistic isobaric collisions

Understand

The effects of neutron skin on the multiplicity ($N_{\rm ch}$) and eccentricity($\epsilon_2$) in relativistic $^{96}_{44}$Ru+$^{96}_{44}$Ru and $^{96}_{40}$Zr+$^{96}_{40}$Zr collisions at $\sqrt{s_{_{\rm NN}}}=200$ GeV are investigated with the Trento model.

• It is found that the Ru+Ru/Zr+Zr ratios of the $N_{\rm ch}$ distributions and $\epsilon_{2}$ in mid-central collisions are exquisitely sensitive to the neutron skin type (skin vs.~halo).
• The state-of-the-art calculations by energy density functional theory (DFT) favor the halo-type neutron skin and can soon be confronted by experimental data.
• It is demonstrated that the halo-type density can serve as a good surrogate for the DFT density, and thus can be efficiently employed to probe nuclear deformities by using elliptic flow data in central collisions.