Decay ofXe137

Abstract

The decay of ${\mathrm{Xe}}^{137}$ was studied by means of scintillation techniques. The radioactive samples were produced by means of neutron irradiation of natural xenon, which contains 8.87% ${\mathrm{Xe}}^{136}$. The half-life of ${\mathrm{Xe}}^{137}$ was found to be 3.95\ifmmode\pm\else\textpm\fi{}0.11 min. One gamma ray of 0.455\ifmmode\pm\else\textpm\fi{}0.003 MeV was attributed to ${\mathrm{Xe}}^{137}$. An upper limit of 0.03 of the intensity of this gamma ray is placed on any other gamma ray due to the decay of ${\mathrm{Xe}}^{137}$. The end-point energy of the beta spectrum was found to be 4.06\ifmmode\pm\else\textpm\fi{}0.06 MeV using ${\mathrm{K}}^{42}$ as a calibration check. A beta ray was found to be in coincidence with the 0.46-MeV gamma ray. A Kurie plot of the beta-gamma coincidence spectrum as well as a subtraction method of the singles Kurie plot were both in agreement with 3.60\ifmmode\pm\else\textpm\fi{}0.06 MeV for the lower-energy beta group. In order to get the intensity of the two beta transitions, two independent methods were utilized. These indicated a relative intensity of about 0.33\ifmmode\pm\else\textpm\fi{}0.03 for the 3.60-MeV beta-ray group and 0.67\ifmmode\pm\else\textpm\fi{}0.03 for the 4.06-MeV beta-ray group. $\mathrm{Log}\mathrm{ft}$ values indicate first-forbidden beta-ray selection rules for both transitions. This is found to be in accord with shell-model predictions. A decay scheme is proposed on the basis of these results.