Neutron-capture gamma rays from the 9.47-eV resonance inXe129(n,γ)Xe130

The $\gamma$-ray spectrum from neutron capture in the 9.47-eV resonance in ${}_{}{}^{129}{}_{}{}^{}\mathrm{Xe}$ has been studied. A target of ${\mathrm{Na}}_4$Xe${\mathrm{O}}_6$ was irradiated in a thermal neutron beam and in a monochromatic neutron beam of 5.16-, 9.47-, and 14.1-eV energy from a crystal diffraction neutron monochromator. The resulting $\gamma$-ray spectra were studied with Ge(Li) detectors of $\simeq 20$-, $\simeq 25$-, $\simeq 30$-, and $\simeq 40$-${\mathrm{cm}}^3$ active volume. $\gamma$ rays were assigned to the ${}_{}{}^{129}{}_{}{}^{}\mathrm{Xe}\left(n \gamma \right){}_{}{}^{130}{}_{}{}^{}\mathrm{Xe}$ reaction by a comparison of these spectra. Ge(Li)-Ge(Li) coincidence measurements were carried out on resonance with the 20- and 30-${\mathrm{cm}}^3$ Ge(Li) detectors in combination. Only a few very intense transitions were observed in coincidence. The data obtained in the present work together with the information from earlier radioactive-decay studies indicate the population of levels in ${}_{}{}^{130}{}_{}{}^{}\mathrm{Xe}$ by neutron capture in the 9.47-eV resonance with energies 536.1 ± 0.2, 1122.1 ± 0.3, 1204.4 ± 0.5, 1631.8 ± 0.7, 1785.9 ± 0.8, 1792.1 ± 0.6, 1807.9 ± 0.4, 2017.0 ± 0.5, 2058.7 ± 0.9, 2081.4 ± 0.9, 2171.0 ± 1.3, 2222.6 ± 0.6, 2241.5 ± 0.6, 2385.1 ± 0.5, 2501.9 ± 0.5, 2544.4 ± 0.9, 2632.4 ± 1.7, (2762.7 ± 0.5), 2885.6 ± 1.1, 2953.5 ± 0.5, 2977.5 ± 1.0, 3071.1 ± 0.8, 3150.1 ± 0.7, 3188.8 ± 0.6, (3243.2 ± 1.3), 3298.0 ± 1.2, 3325.1 ± 0.8, 3405.2 ± 0.7, 3534.2 ± 0.6, 3621.9 ± 0.7, 3685.6 ± 1.0, 3780.0 ± 1.2, 3892.2 ± 1.5, (3960.1 ± 1.0), 3976.3 ± 1.5, and 3985.6 ± 1.0 keV. The neutron separation energy of ${}_{}{}^{130}{}_{}{}^{}\mathrm{Xe}$ is 9254.7 ± 1.3 keV. The observation of the 9254.2 ± 2.1 keV primary-capture $\gamma$ ray to the 0+ ground state of ${}_{}{}^{130}{}_{}{}^{}\mathrm{Xe}$ clearly establishes the spin of the 9.47-eV resonance in ${}_{}{}^{129}{}_{}{}^{}\mathrm{Xe}$ as 1+.