Artificial activation of tellurium and iodine by deuterons and neutrons yields four radioactive isotopes of iodine. The momentum distributions of the beta-particles emitted by these isotopes were examined in a large hydrogen-filled cloud chamber placed in a uniform magnetic field. Applications of the Fermi theory of beta-decay and of the Konopinski-Uhlenbeck modification were made and the extrapolated end points were compared to the inspection end points. Gamma-radiation was found with each activity. An estimate of energies of the gamma-radiation associated with ${\mathrm{I}}^{130}$ and ${\mathrm{I}}^{131}$ was determined from the electrons ejected from a lead absorber placed in the cloud chamber. The following results were obtained: The original Fermi theory is in better agreement with the experimental data, the Kurie plots being linear over a considerable range to the end-point.

• Received 5 September 1939

DOI:https://doi.org/10.1103/PhysRev.56.965