Inelastic Scattering of Iron-Capture Gamma Rays from the 7.64-MeV Level ofCd112

Abstract

In the resonant-scattering experiment of the monochromatic iron-capture gamma rays from natural cadmium, five inelastically scattered photon groups were observed in addition to the 7.64-MeV elastic group. The spectrum of the low-energy cascade photons in coincidence with the scattered photons identifies the inelastic groups to be the transitions to the low-lying levels of ${\mathrm{Cd}}^{112}$, including the three $2^{+}$ vibrational levels at 0.61, 1.29, and 1.46 MeV. Angular-distribution measurements show that the 7.64-MeV resonance level in ${\mathrm{Cd}}^{112}$ has angular momentum 1. The average elastic-scattering cross section and the branching ratio for the ground-state transitions are $〈{\sigma }_{\gamma \gamma }〉=0.17\mathrm{}\pm 0.02$ b and $\frac{{\Gamma }_0}{\Gamma }=0.48\mathrm{}\pm 0.06$, respectively. Using these values, the self-absorption measurements determined the ground-state transition width to be ${\Gamma }_0={{0.6}_{-0.1\mathrm{}}}^{+0.2\mathrm{}}$ eV.