Pygmy resonances and radiative nucleon captures for stellar nucleosynthesis

The impact of low-energy multipole excitations and pygmy resonances on radiative neutron and proton capture cross sections in nuclei close to the -stability line is investigated. For this purpose, a microscopic theoretical approach based on self-consistent density functional theory and QRPA formalism extended with multi-phonon degrees of freedom, is implemented in a statistical reaction model. The advantage of the method is the fully microscopic nuclear structure input for unified description of low-energy multi-phonon excitations, pygmy and giant resonances. This is found important for the understanding of the fine structure and dynamics of nuclear response functions at low energies which strongly influence nuclear reaction rates of astrophysical significance. Calculations of the radiative capture cross sections of the reactions 85Kr(n,)86Kr, 87Sr(n,)88Sr and 89Y(p,)90Zr are discussed in comparison with the experiment. For the reactions 89Zr(n,)90Zr and 91Mo(n,)92Mo theoretical predictions of the reaction cross sections are made.