Fano effect on neutron elastic scattering by open-shell nuclei

摘要

By focusing on the asymmetric shape of cross section, we analyze pairing effect on the partial wave components of cross section for neutron elastic scattering off stable and unstable nuclei within the Hartree-Fock-Bogoliubov framework. Explicit expressions for Fano parameters q(lj) and epsilon(lj) have been derived and pairing effects have been analyzed in terms of these parameters, and the Fano effect was found on the neutron elastic scattering off the stable nucleus in terms of the pairing correlation. The Fano effect appeared as the asymmetric line shape of the cross section caused by small absolute value of q(lj) due to small pairing effect on the deep-lying hole state of stable nucleus. In the case of unstable nuclei, the large q(lj) value is expected because of small absolute value of Fermi energy. The quasiparticle resonance with large q(lj) forms Breit-Wigner-type shape in elastic-scattering cross section.