Decay of the 9.4-Min and 8.7-Day Isomers ofSn125

Abstract

The decay schemes of the 9.4-min and 9.7-day isomers of ${\mathrm{Sn}}^{125}$ have been studied using scintillation spectrometers and coincidence techniques. Gamma rays of energies 325, 585, 640, 830, 1070, 1390, 1470, 1610, 1720, and 1940 keV with relative intensities 130, 0.75, 0.40, 0.16, 0.17, 1.0, 0.58, 0.28, 0.08, and 0.07, respectively, were observed in the decay of the 9.4-min isomer while the decay of the 9.7-day isomer gives rise to gamma rays of energies 330, 470, 810, 910, 1075, 1165, 1410, 1985, and 2230 keV with relative intensities 0.23, 0.28, 1.0, 0.92, 2.81, 0.09, 0.09, 0.41, and 0.03, respectively. On the basis of the coincidences between the various gamma rays it is concluded that the 9.4-min isomer excites levels in ${\mathrm{Sb}}^{125}$ at 325, 640, 910, 1470, 1720, and 1940 keV, whereas levels at 1075, 1410, 1885, 1985, and 2230 keV are excited in the decay of the 9.7-day isomer. Further evidence in support of these levels from total-absorption gamma spectra is also presented. Plausible spin and parity assignments to these levels have been made on the basis of the $log\mathrm{ft}$ values of the beta groups feeding these levels and also their decay modes.