Mass measurements of {sup 70}Se, {sup 71}Se, {sup 72}Br, and {sup 73}Br

The path and termination point for the rapid proton-capture (rp) process above {sup 56}Ni is uncertain due to a lack of knowledge of nuclear properties, especially masses, near the proton drip line. To address this need we have begun a program to measure masses along the rp-process path in the A{approx}60--80 region using {beta}-{gamma} coincidence spectroscopy. Q{sub EC} values derived from {beta}{sup +} spectrum end points were used to calculate mass excess values for {sup 70}Se, {sup 71}Se, {sup 72}Br, and {sup 73}Br. The results are compared to predictions of mass models and to estimates based on systematic trends in this region.