Gamma Rays from theAs75(n, γ)As76Reaction

Neutron capture $\gamma$ rays from ${}_{}{}^{76}{}_{}{}^{}\mathrm{As}$ have been studied. In this study 2 kg of ${}_{}{}^{75}{}_{}{}^{}\mathrm{As}$ were irradiated with thermal neutrons from a 5-Ci Pu-Be source. Graphite and paraffin were used to thermalize the fast neutrons. The As nearly surrounded an encapsulated Ge-Li detector, which detected the high-energy $\gamma$ rays from the As with an energy resolution of 12 keV. Several centimeters of lead and bismuth between the Pu-Be source and the detector attenuated the $\gamma$ radiation emitted from the Pu-Be source. Energies and intensities of 38 $\gamma$ rays were measured in the region between 5.2 and 7.3 MeV. The 5.718-, 6.114-, and 6.632-MeV $\gamma$ rays of ${}_{}{}^{36}{}_{}{}^{}\mathrm{Cl}$ were used as energy and intensity standards. The highest-energy $\gamma$ ray observed has an energy of 7344±10 keV. Assuming this to be the transition from the capture state to the ground state and the others to de-excite the capture state also, 37 energy levels are found from the ground state up to 2100 keV. Additionally, two previously unresolved energy regions in the ${}_{}{}^{35}{}_{}{}^{}\mathrm{Cl}(n, \gamma ){}_{}{}^{36}{}_{}{}^{}\mathrm{Cl}$ spectrum are resolved.