First observation of the electron capture of $^{76}$As

Abstract

For a variety of radionuclides which decay via β − and a weak β + -channel the electron-capture (EC) is not observed yet. As the interest of exact decay characteristica increased again, not least with the need of reliable data for experiments on investigation of the neutrinoless double-beta-decay, an experiment for the investigation of the 76 As -EC was performed. The first time observation of the EC of 76 As by this experiment resulted in a total branching-ratio for the EC / β + -channel of pEC = 0.0269 ± (0.0080(stat.) ± 0.0029(sys.)) and pEC = 0.0263 ± (0.0077(stat.) ± 0.0047(sys.)) according to two different methods. For the branching of this decay-channel into the first excitedand the ground state of 76 Ge a limit was obtained.