The Radiations Emitted from Artificially Produced Radioactive Substances IV. Further Studies on the Gamma-Rays from Several Elements

Further studies on the gamma-radiation from ${\mathrm{V}}^{48}$, ${\mathrm{N}}^{13}$, ${\mathrm{Cu}}^{64}$, ${\mathrm{Mg}}^{27}$, and ${\mathrm{Na}}^{24}$ have been carried out using a large hydrogen-filled cloud chamber and with several improvements in technique. The most striking feature of the spectra, is the presence of a large amount of 1 Mev radiation from ${\mathrm{V}}^{48}$. Comparison with the ordinary annihilation radiation indicates that there are four 1 Mev quanta emitted per positron. The possible origin of this radiation is discussed. A difference in the gamma-radiation emitted from ${\mathrm{N}}^{13}$ and ${\mathrm{Cu}}^{64}$ is noted, the latter having a more pronounced high energy tail. A small number of tracks from ${\mathrm{Mg}}^{27}$ have been measured and indicate a monochromatic line at 0.88±0.05 Mev. The radiation from ${\mathrm{Na}}^{24}$ has been re-examined. The results indicate that the quantum energy of the high energy line is 3.00±0.05 Mev. The two other lines with energies of 2 Mev and 1 Mev are confirmed.