Mass measurements towards doubly magic 78Ni: Hydrodynamics versus nuclear mass contribution in core-collapse supernovae

We report the first high-precision mass measurements of the neutron-rich nuclei Ni-74,Ni-75 and the clearly identified ground state of Cu-76, along with a more precise mass-excess value of Cu-78, performed with the double Penning trap JYFLTRAP at the Ion Guide Isotope Separator On-Line (IGISOL) facility. These new results lead to a quantitative estimation of the quenching for the N = 50 neutron shell gap. The impact of this shell quenching on core-collapse supernova dynamics is specifically tested using a dedicated statistical equilibrium approach that allows a variation of the mass model independent of the other microphysical inputs. We conclude that the impact of nuclear masses is strong when implemented using a fixed trajectory as in the previous studies, but the effect is substantially reduced when implemented self-consistently in the simulation. (C) 2022 The Authors. Published by Elsevier B.V.

Automated summary

This study reports the first high-precision mass measurements of neutron-rich nuclei Ni-74, Ni-75, and the ground state of Cu-76 using the double Penning trap JYFLTRAP at the Ion Guide Isotope Separator On-Line (IGISOL) facility. The results lead to a quantitative estimation of the quenching for the N = 50 neutron shell gap. The impact of this shell quenching on core-collapse supernova dynamics is tested using a statistical equilibrium approach.