The masses of ${}_{}{}^{77}{}_{}{}^{}\mathrm{Kr}$ and ${}_{}{}^{75}{}_{}{}^{}\mathrm{Kr}$ were determined by measuring the Q values of the ${}_{}{}^{80}{}_{}{}^{}\mathrm{Kr}$${(}^3$He${,}^6$He${)}^{77}$Kr, ${}_{}{}^{78}{}_{}{}^{}\mathrm{Kr}$(d,t${)}^{77}$Kr, and ${}_{}{}^{78}{}_{}{}^{}\mathrm{Kr}$${(}^3$He${,}^6$He${)}^{75}$Kr reactions. We find that the ${}_{}{}^{77}{}_{}{}^{}\mathrm{Kr}$ and ${}_{}{}^{75}{}_{}{}^{}\mathrm{Kr}$ mass excesses are -70.160(10) and -64.231(16) MeV, respectively. These new results are integrated into the total scheme of mass measurements in the light rubidium and krypton isotopes. Comparisons with several mass formulae are presented.

• Received 18 August 1986

DOI:https://doi.org/10.1103/PhysRevC.35.1275