Radiations from Arsenic 77 and Germanium 71

The radionuclide ${\mathrm{As}}^{77}$ has been shown by scintillation spectrometry to emit gamma rays of energies 32, 87, 160, 247, 270, and 520 kev. It is estimated that these quanta are associated with beta-ray branches totaling about 2.5 percent of the total beta radiation. The continuous gamma-ray spectrum accompanying orbital electron capture in ${\mathrm{Ge}}^{71}$ has been shown to have an end point at 225±12 kev. $\mathrm{Log}\mathrm{ft}$ is calculated to be $4.4(\Delta I=0, 1; \mathrm{no})$, consistent with an assignment of spin ½ to the ground state of ${\mathrm{Ge}}^{71}$ in accord with the theory of the shell model.