Radiations from Molybdenum (99) and Technetium (99)

Abstract

The 67-hour activity was induced in ${\mathrm{Mo}}_2$ ${\mathrm{O}}_3$ irradiated by slow neutrons in the Clinton pile. ${\mathrm{Mo}}^{99}$ emits two beta-ray spectra, one of low energy, having an end point at 0.057 g/${\mathrm{cm}}^2$ in aluminum, the other having a maximum energy of 1.03 Mev. The beta-rays of the low energy group are coupled with gamma-radiation, whereas those of the spectrum ending at 1.03 Mev are not. The gamma-rays of ${\mathrm{Mo}}^{99}$ have a maximum energy of 0.71 Mev as measured by coincidence absorption, and a small gamma-gamma coincidence rate, 0.085×${10}^{-3\mathrm{}}$ coincidence per gammaray, was detected in ${\mathrm{Mo}}^{99}$. The electrons of the highly converted gamma-ray of the 6-hour metastable state of ${\mathrm{Tc}}^{99}$, separated from ${\mathrm{Mo}}^{99}$, are non-coincident with gamma-radiation. No gamma-gamma coincidences were observed in the technetium fraction. The conversion electrons have a range of 0.022 g/${\mathrm{cm}}^2$ in aluminum.