gamma-ray strength function and pygmy resonance in rare earth nuclei - art. no. 044313

The gamma -ray strength function for gamma energies in the 1-7 MeV region h as been measured for Dy-161,Dy-162 and Yb-171,Yb-172 using the (He-3, alpha gamma) reaction. Various models are tested against the observed gamma -ray strength functions. The best description is based on the Kadmenskii, Marku shev, and Furman E1 model with constant temperature and the Lorentzian M1 m odel. A gamma -ray bump observed at E(gamma)similar to3 MeV is interpreted as the so-called pygmy resonance, which has also been observed previously i n (n, gamma) experiments. The parameters for this resonance have been deter mined and compared to the available systematics.