Long Period Activity of Indium Produced by Slow Neutrons

Abstract

Indium was irradiated with slow neutrons from a radium-beryllium source for a period of several months. A period of 45±3 days was produced quite strongly. It is shown that this period is produced when ${\mathrm{In}}^{113}$ captures a neutron to form ${\mathrm{In}}^{114}$. The ratio of the activity of the long period to that of 54 minutes, due to ${\mathrm{In}}^{116}$, is approximately the same as the isotope ratio ${\mathrm{In}}^{113}$/${\mathrm{In}}^{115}$. The capture cross sections for the two processes are given by the relation ${\sigma }_{113}=0.56\mathrm{}{\sigma }_{115}$.