Disintegration ofTe129

The disintegration of ${\mathrm{Te}}^{129}$ has been investigated with the help of a magnetic lens spectrometer, permanent field spectrometer with photographic recording, and scintillation counters. The half-lives of the isomeric states in the parent were found to be 41 days and 74 minutes, respectively. The 74-minute state decays to ${\mathrm{I}}^{129}$ with the emission of beta-ray groups whose end-point energies and relative abundances are 1.453 Mev (71%), 0.989 Mev (15%), 0.69 Mev (4%), and 0.29 Mev (10%). Gamma rays of 0.027, 0.21, 0.475, 0.72, and 1.12 Mev were found. The 41-day state decays, for the most part, to the 74-minute state of ${\mathrm{Te}}^{129}$ with the emission of a highly internally converted gamma ray of energy 106.3±0.1 kev for which the $\frac{K}{L}$ ratio is unity. A beta-ray transition, of low intensity, from the 41-day state of ${\mathrm{Te}}^{129}$ to the ground state of the product is postulated. Gamma-gamma and beta-gamma coincidence experiments using scintillation spectrometers served to indicate the probable level scheme of ${\mathrm{I}}^{129}$. A discussion of the disintegration scheme is given suggesting probable spins and parities of the levels.