Use of the (γ,γ′) Reaction for Studying the Energy Levels ofAs75

Abstract

Elastic and inelastic nuclear resonant scattering of monochromatic photons from ${}_{}{}^{75}{}_{}{}^{}\mathrm{As}$ have been studied using a 47-cc Ge (Li) detector. The $\gamma$ source was provided by thermal-neutron capture in iron. The energy of the resonance level in ${}_{}{}^{75}{}_{}{}^{}\mathrm{As}$ was found to be 7.646 MeV. Assuming the high-energy lines to be primary transitions deexciting the resonance level, 25 energy levels were found from the ground state up to 2.6 MeV, seven of which may be identified with recently reported levels. By measuring the angular distribution of the scattered radiation, the spin of the scattering level was determined to be ½ and the spins of 14 low-lying levels were thus found to be either ½ or $\frac{3}{2}$. The total radiative width of the resonance level was determined and was found to be $\Gamma =0.36\mathrm{}\pm 0.10$ eV and $\frac{{\Gamma }_0}{\Gamma }=0.11\mathrm{}$. The ${}_{}{}^{75}{}_{}{}^{}\mathrm{As}$ levels are compared with the predictions of the Coriolis coupling model.