Radiative strength in the compound nucleus [sup 157]Gd

The distribution of [ital E]1 and [ital M]1 strength in [sup 157]Gd compound nucleus has been studied. An investigation of capture of 2 and 24 keV neutrons in a [sup 156]Gd target resulted in resonance-averaged intensities of primary gamma rays between 3.7 and 6.4 MeV. From these intensities the gamma-ray strength functions have been derived for [ital E]1 and [ital M]1 radiation. We compare several formulations of strength functions to these resonance capture and/or photoabsorption data. Further we use these prescriptions in calculations of the total average radiation width, radiative capture cross sections, and gamma-ray spectra, and compare them to available experimental information. By analyzing these results strong evidence was found for an [ital E]1 strength function which is based on a generalized Lorentzian, enhanced compared to spherical nuclei, with an energy-dependent spreading width and a nonzero limit as the energy tends to zero. For [ital M]1 radiation the giant resonance spin-flip mode is favored.