Enhanced Radiative Strength in the Quasicontinuum of Sn117

The radiative strength function of Sn117 has been measured up to the neutron separation energy using the (He3, He'3γ) reaction. An increase in the slope of the strength function around E_γ=4.5MeV indicates the onset of a resonancelike structure, giving a significant enhancement of the radiative strength function compared to standard models in the energy region 4.5≤E_γ≤8.0MeV. For the first time, the functional form of this resonancelike structure has been measured in an odd tin nucleus below neutron threshold in the quasicontinuum region.