Decay ofSn125(9.7-Day and 9.4-Minute)

Abstract

The beta and gamma radiations of the 9.7-day and 9.4-minute radioactive decays of ${\mathrm{Sn}}^{125}$ have been studied by scintillation methods using multichannel coincidence spectrometers. Sources were prepared by thermal-neutron irradiation of metallic tin foil enriched in ${\mathrm{Sn}}^{124}$, followed by chemical purification. In the 9.7-day activity, seven gamma rays of energies 0.342, 0.468, 0.811, 0.904, 1.068, 1.41, and 1.97 Mev are observed. Their intensities, expressed in percent of the total decay to excited states, are 9, 10, 20, 18, 73, 3, and 24 respectively. The presence of four beta-ray components is deduced; their energies are 2.35, 1.28, 0.47, and 0.38 Mev, with $log\mathrm{ft}$ values of 8.9, 9.8, 7.9, and 7.7 respectively. There is a possible weak fifth component of 0.94 Mev with $log\mathrm{ft}$ about 10.4. The coincidence data define a decay scheme involving excited states in ${\mathrm{Sb}}^{125}$ at 1.07, 1.41, 1.88, and 1.97 Mev, with the strong (∼95%) 2.35-Mev beta ray proceeding directly to the ground state. All these excited states surely have spins of at least $\frac{9}{2}$, and all probably have positive parity.