Rhm103production by inelastic gamma scattering in the giant dipole resonance region

The cross section of the ${}_{}{}^{103}{}_{}{}^{}\mathrm{Rh}$(γ,γ’ ${)}^{103}$ ${\mathrm{Rh}}^{\mathit{m}}$ reaction as a function of energy has been studied in the giant dipole resonance region. Natural rhodium was irradiated with bremsstrahlung of an electron beam on a platinum converter for electron energies of 14, 15, 17, 19, 20, and 30 MeV. Induced isomeric activities as a function of beam energy were measured with γ-ray spectrometry using a high-purity Ge detector. The integral cross section obtained from the yield curve was found to be uniformly 22.6±4.0 mb MeV for all of the beam energies. The experimental data have been compared with the predictions of a γ-ray cascade model calculation where competing open nucleon emission channels were considered and a spin-dependent preequilibrium correction was applied in addition to the equilibrium transition probabilities. The calculation provided one pronounced peak in the cross section–at the (γ,n) threshold–with an integral of 24.3 mb MeV. Neither the experiments nor the calculation confirmed the existence of a comparable second peak observed in earlier experiments.