From coincidence measurements on $\gamma -\gamma$ cascades following the decay of ${}_{}{}^{129}{}_{}{}^{}\mathrm{Te}_{}^m{}_{}{}^{}$ the existence of a 1047-keV level in ${}_{}{}^{129}{}_{}{}^{}\mathrm{I}$ is well established. Angular correlation measurements for several cascades give the following values: $\{281-251-\mathrm{k}\mathrm{e}\mathrm{V}\mathrm{c}\mathrm{a}\mathrm{s}\mathrm{c}\mathrm{a}\mathrm{d}\mathrm{e}:,A_{22}= 0.238\pm 0.015,,A_{44}= 0.014\pm 0.026;\}\{209-251-\mathrm{k}\mathrm{e}\mathrm{V}\mathrm{c}\mathrm{a}\mathrm{s}\mathrm{c}\mathrm{a}\mathrm{d}\mathrm{e}:,A_{22}= 0.234\pm 0.012,,A_{44}= 0.011\pm 0.022;\}\{281-278-\mathrm{k}\mathrm{e}\mathrm{V}\mathrm{c}\mathrm{a}\mathrm{s}\mathrm{c}\mathrm{a}\mathrm{d}\mathrm{e}:,A_{22}=-0.048\mathrm{}\pm 0.014,,A_{44}=-0.014\mathrm{}\pm 0.023;\}\{209-278-\mathrm{k}\mathrm{e}\mathrm{V}\mathrm{c}\mathrm{a}\mathrm{s}\mathrm{c}\mathrm{a}\mathrm{d}\mathrm{e}:,A_{22}=-0.059\mathrm{}\pm 0.011,,A_{44}= 0.018\pm 0.018;\}\{624-209-\mathrm{k}\mathrm{e}\mathrm{V}\mathrm{c}\mathrm{a}\mathrm{s}\mathrm{c}\mathrm{a}\mathrm{d}\mathrm{e}:,A_{22}=-0.270\mathrm{}\pm 0.065,,A_{44}= 0.047\pm 0.095;\}\{624-460-\mathrm{k}\mathrm{e}\mathrm{V}\mathrm{c}\mathrm{a}\mathrm{s}\mathrm{c}\mathrm{a}\mathrm{d}\mathrm{e}:,A_{22}= 0.151\pm 0.009,,A_{44}= 0.003\pm 0.012;\}\{624-478-\mathrm{k}\mathrm{e}\mathrm{V}\mathrm{c}\mathrm{a}\mathrm{s}\mathrm{c}\mathrm{a}\mathrm{d}\mathrm{e}:,A_{22}=-0.290\mathrm{}\pm 0.025,,A_{44}=-0.002\mathrm{}\pm 0.036;\}\{343-460-\mathrm{k}\mathrm{e}\mathrm{V}\mathrm{c}\mathrm{a}\mathrm{s}\mathrm{c}\mathrm{a}\mathrm{d}\mathrm{e}:,A_{22}=-0.341\mathrm{}\pm 0.058,,A_{44}= 0.033\pm \mathrm{0.080.}\}$ These values, together with nuclear orientation data, uniquely determine the spin of the excited states at 278 keV ($\frac{3}{2}$) and 860 keV ($\frac{3}{2}$). The mixing ratios $\delta \left(\frac{E2\mathrm{}}{M1\mathrm{}}\right)$ for the different transitions are obtained.

[RADIOACTIVITY ${}_{}{}^{129}{}_{}{}^{}\mathrm{Te}$ from ${}_{}{}^{128}{}_{}{}^{}\mathrm{Te}(n,\gamma )$; measured $\gamma \gamma$ coin, $\gamma \gamma \left(\theta \right)$. ${}_{}{}^{129}{}_{}{}^{}\mathrm{I}$ deduced levels, $J$, $\gamma$-mixing ratios. Enriched target, Ge(Li), Na(Tl) detectors.]

• Received 22 January 1974

DOI:https://doi.org/10.1103/PhysRevC.9.2391