A study has been made of neutron deficient radioactive isotopes of rhenium. Using the 60-inch Crocker Laboratory cyclotron, bombardments have been made of tantalum with 38, 30, and 19 Mev $\alpha$-particles, of wolfram with 10-Mev protons, and of rhenium with fast neutrons.

The radiation characteristics of four new radioactive isotopes and of the previously known 50-day ${\mathrm{Re}}^{184}$ isotope have been studied.

• Received 16 August 1949

DOI:https://doi.org/10.1103/PhysRev.77.314