Precision Mass Measurement ofC9,O13, andMg21and the Isobaric-Multiplet Mass Equation

Abstract

The ground-state masses of ${}_{}{}^9{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{13}{}_{}{}^{}\mathrm{O}$, and ${}_{}{}^{21}{}_{}{}^{}\mathrm{Mg}$ have been determined through measurement of the $Q$ values of the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(${}_{}{}^3{}_{}{}^{}\mathrm{He}$, ${}_{}{}^6{}_{}{}^{}\mathrm{He}$)${}_{}{}^9{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$(${}_{}{}^3{}_{}{}^{}\mathrm{He}$, ${}_{}{}^6{}_{}{}^{}\mathrm{He}$)${}_{}{}^{13}{}_{}{}^{}\mathrm{O}$, and ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$(${}_{}{}^3{}_{}{}^{}\mathrm{He}$, ${}_{}{}^6{}_{}{}^{}\mathrm{He}$)${}_{}{}^{21}{}_{}{}^{}\mathrm{Mg}$ reactions. The measurements were made with 68-70-MeV ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ beams using a split-pole magnetic spectrograph. A new method for obtaining a precise calibration for the beam analyzer and magnetic spectrograph at these high bombarding energies is presented.