Radiations from Radioactive Cobalt

Abstract

A cloud chamber has been built and is briefly described. It has been used for measuring the energies of the radiations from the long-lived cobalt isotopes, ${\mathrm{Co}}^{56,\phantom{\rule{0ex}{0ex}}58}$, formed by deuteron bombardment of iron. A positron spectrum with a maximum energy of 1.36\ifmmode\pm\else\textpm\fi{}0.10 Mev was observed on the histogram. The K-U plot of the data suggests also another spectrum with an energy end point near 0.5 Mev. One internally converted $\ensuremath{\gamma}$-ray near 0.1 Mev was observed in the cloud chamber and resolved into two lines at 117 kev and 130 kev, respectively, by a magnetic spectrograph. Still higher energy $\ensuremath{\gamma}$-rays less intensely internally converted are suggested.The histogram from a sample of ${\mathrm{Co}}^{58}$ produced by bombarding manganese with $\ensuremath{\alpha}$-particles definitely assigns the higher energy positron spectrum to the isotope ${\mathrm{Co}}^{58}$.