Disintegration Scheme ofI131

Abstract

The radiations of ${\mathrm{I}}^{131}$ (8-day) have been studied in a pair of lens beta-ray spectrometers placed end to end, with coincidence counting of the focused radiations from a single source. Coincidence beta-spectra are shown with end points at 608±5 kev (87.2 percent), 335±6 kev (9.3 percent), and 250±7 kev (2.8 percent). A weak 812±15 kev beta-spectrum (0.7 percent) apparently leads to the 12-day isomer of ${\mathrm{X}}^{131}$. Relative intensities of the three main beta-components are obtained from gamma-ray measurements alone. All gamma-rays have their multipolarities assigned on the basis of measured $K$-conversion coefficients and $\frac{K}{L}$ ratios. A consistent disintegration scheme is proposed which is an extension of that of Metzger and Deutsch. Single-particle orbital assignments are made to the lower excited states of ${\mathrm{Xe}}^{131}$ which agree with shell theory.