Exploring the mass surface near the rare-earth abundance peak via precision mass measurements at JYFLTRAP

Abstract

The JYFLTRAP double Penning trap at the Ion Guide Isotope Separator On-Line facility has been used to measure the atomic masses of 13 neutron-rich rare-earth isotopes. Eight of the nuclides, $^{161}\mathrm{Pm}, ^{163}\mathrm{Sm}, ^{164,165}\mathrm{Eu}, ^{167}\mathrm{Gd}$, and $^{165,167,168}\mathrm{Tb}$, were measured for the first time. The systematics of the mass surface has been studied via one- and two-neutron separation energies as well as neutron pairing-gap and shell-gap energies. The proton-neutron pairing strength has also been investigated. The impact of the new mass values on the astrophysical rapid neutron capture process has been studied. The calculated abundance distribution results in a better agreement with the solar abundance pattern near the top of the rare-earth abundance peak at around $A\ensuremath{\approx}165$.