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 (IGISOL) facility has been used to measure the atomic masses of 13 neutron-rich rare-earth isotopes. Eight of the nuclides, ${}^{161}$Pm, ${}^{163}$Sm, ${}^{164,165}$Eu, ${}^{167}$Gd, and ${}^{165,167,168}$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 $A\approx 165$.

15 pages, 17 figures