The yield ratios of neutron-proton $\left[R\right(n/p\left)\right]$ and ${}^3\mathrm{H}\text{−}{}^3\mathrm{He}$ $\left[R\right(t/{}^3\mathrm{He}\left)\right]$ with reduced rapidity from 0 to 0.5 are simulated for 50 MeV/u ${}^{48,50,52,54,56,58}\mathrm{Ni}+{}^{58}\mathrm{Ni}$ neutron-deficient systems at all reduced impact parameters by using the isospin-dependent quantum molecular dynamics (IQMD) model. Neutron and proton density distributions (used for the phase-space initialization of the reaction system in IQMD) and the proton skin thickness $\mathrm{\Delta }{R}_{pn}$ of different neutron-deficient Ni isotopes are given by the Skyrme-Hartree-Fock model. The results show that both $R(n/p)$ and $R(t/{}^3\mathrm{He})$ from different centralities are strongly linear with $N/Z$ of different Ni projectiles, but are exponentially dependent on $\mathrm{\Delta }{R}_{pn}$ with better fitting. It is therefore suggested that $R(n/p)$ and $R(t/{}^3\mathrm{He})$ from any same centrality (peripheral collisions are much better, with bigger yield ratios and curve slopes) could be treated as possible experimental probes to extract the proton skin thickness of neutron-deficient isotopes from isotopes near the $\beta$-stability line.

• Received 16 February 2020
• Accepted 22 April 2020

DOI:https://doi.org/10.1103/PhysRevC.101.054601