The radiations from ${\mathrm{Mo}}^{99}$ (67 hours) and its metastable daughter ${\mathrm{Tc}}^{99m}$ (6 hours) have been measured in a magnetic lens spectrograph. The beta-ray spectrum consists of a group with an end-point energy of 1.23 Mev, one of 0.445 Mev and possibly a third lower energy group. The relative intensities of the 1.23-Mev to 0.445-Mev groups are 4:1. Gamma-rays have been found at 0.040, 0.140, 0.181, 0.367, 0.741, and 0.780 Mev. The gamma-rays at 0.040, 0.140, and 0.181 Mev are internally converted. The spectrum of ${\mathrm{Tc}}^{99}$ consists of one internally converted gamma-ray at 0.140 Mev. A disintegration scheme is proposed.

• Received 24 July 1950

DOI:https://doi.org/10.1103/PhysRev.80.961