6533b854fe1ef96bd12afc8e

RESEARCH PRODUCT

Mass of astrophysically relevantCl31and the breakdown of the isobaric multiplet mass equation

subject

description

The mass of $^{31}\mathrm{Cl}$ has been measured with the JYFLTRAP double-Penning-trap mass spectrometer at the Ion Guide Isotope Separator On-Line (IGISOL) facility. The determined mass-excess value, $\ensuremath{-}7034.7(34)$ keV, is 15 times more precise than in the Atomic Mass Evaluation 2012. The quadratic form of the isobaric multiplet mass equation for the $T=3/2$ quartet at $A=31$ fails $({\ensuremath{\chi}}_{n}^{2}=11.6)$ and a nonzero cubic term, $d=\ensuremath{-}3.5(11)$ keV, is obtained when the new mass value is adopted. $^{31}\mathrm{Cl}$ has been found to be less proton-bound, with a proton separation energy of ${S}_{p}=264.6(34)$ keV. Energies for the excited states in $^{31}\mathrm{Cl}$ and the photodisintegration rate on $^{31}\mathrm{Cl}$ have been determined with significantly improved precision by using the new ${S}_{p}$ value. The improved photodisintegration rate helps to constrain astrophysical conditions where $^{30}\mathrm{S}$ can act as a waiting point in the rapid proton capture process in type-I x-ray bursts.