The Internally Converted Gamma-Rays of Several Radioactive Elements

The conversion electron spectra of a number of radioactive elements produced by proton and deuteron bombardment in the cyclotron have been investigated. The beta-ray spectrograph was designed to allow rapid replacement of the source and photographic film so that successive fresh samples of short period activities could be used for a single exposure. The results may be summarized as follows: ${\mathrm{Br}}^{80}$ (4.4 hr.) three conversion lines observed corresponding to two gamma-rays, one of 48.9±0.4 kev and a second of either 37.1 or 25.3 kev, both arising in the isomeric transition to the 18-min. state. ${\mathrm{Br}}^{78}$ (6.3 min., $e^{+}$) $K$ and $L_1$ conversions in Se of two gamma-rays of 45.8±0.4 and 107.7±0.9 kev; ${\mathrm{Cd}}^{107\mathrm{o}\mathrm{r}109}$ (6.4 hr., $K$ capture) $K$, $L_1$ and $M_1$ conversions of a gamma-ray of 92.6±0.8 kev. In this case there is an anomalously high ${\mathrm{L}}_1$ conversion since the $K$ and $L_1$ lines have nearly equal intensity. Also a 530-kev gamma-ray, possibly annihilation radiation, although no positrons are observed. ${\mathrm{Ga}}^{67}$ (78 hr., $K$ capture) $K$ and $L_1$ conversions of a gamma-ray of 92.5±0.8 kev; ${\mathrm{Ga}}^{70}$ (18.5 min., $e^{-}$ and possible $K$ capture) $K$ and $L_1$ conversions of a gamma-ray of 53.8±0.5 kev and probably a second line of about 117 kev.