Effects of proton momentum gap on the cluster production in heavy ion collisions at low energies

Abstract The proton momentum gap effect on the fragment production in the 197 Au + 197 Au reaction at an incident energy of 50 MeV/nucleon with impact parameter b = 5 fm is studied using the isospin-dependent Boltzmann–Uehling–Uhlenbeck transport model coupled with the phase-space coalescence after-burner. The detailed results show that, the proton momentum gap significantly enhances triton yields over 3 He and has a stronger effect on triton elliptic flow. This influence on the differential and relative elliptic flows of triton and 3 He becomes more pronounced at higher kinetic energies. Furthermore, the proton momentum gap increases the average neutron-to-proton ratio and enhances the isotope yields, particularly for heavier fragments. The study suggest that experimental measurements of the relative elliptic flow of triton and 3 He at high kinetic energies, along with the isotopic distributions of heavy fragments or the neutron-to-proton ratio, may serve as effective experimental signatures for probing the existence of proton momentum gap in asymmetric nuclear matter.