HIGH-RESOLUTION GE(LI) STUDY OF DECAY OF 129GTE AND 129MTE

The decay of 129mTe and 129gTe to levels in 129I has been studied using Ge(Li) detectors for high-resolution γ-ray spectroscopy with some supporting data from NaI(Tl) detectors in coincidence. A total of 46 gamma rays is accounted for by 16 excited states (one tentative) in 129I up to 1401.6 keV. These include ten new gamma rays not previously reported, a new level in 129I at 1282.1 keV ( 5 2+) and a probable new level at 1204.2 keV ( 3 2+, 5 2+) (values of Jπ in parentheses). The decay scheme was arrived at primarily on the basis of precise γ-ray energy determinations (to ±50 eV in many cases and never worse than ±200 eV). Beta-decay log f{hook}t values were determined from our γ-ray intensity balances coupled with published β-branchings. Most-probable spins and parities were deduced based on the γ-ray branching, the log f{hook}t value and published angular correlations of other workers. The Jπ = 1 2+ state predicted by Kisslinger and Sorensen in the region of 200 eV and observed in 125I and 127I is not seen; we find log f{hook}t≧10.6 for the allowed β-decay from 129gTe to such a level. We likewise find no evidence for the 11 2- state at ≈ 930 keV as predicted by Kisslinger and Sorensen; the allowed β-decay to this state would have log f{hook}t ≧ 11.0. © 1969.