Gogny-HFB+QRPA dipole strength function and its application to radiative nucleon capture cross section

Abstract

Valuable theoretical predictions of nuclear dipole excitations in the whole nuclear chart are of great interest for different applications, including in particular nuclear astrophysics. Here we extend our large-scale calculations of the $E1$ and $M1$ absorption $\ensuremath{\gamma}$-ray strength function obtained in the framework of the axially symmetric deformed quasiparticle random-phase approximation (QRPA) based on the finite-range D1M Gogny force to the deexcitation strength function. To do so, shell-model calculations of the deexcitation dipole strength function are performed and their limit at low $\ensuremath{\gamma}$ energies used to complement phenomenologically the QRPA calculations. We compare our final prediction of the $E1$ and $M1$ strength with available experimental data at low energies and show that a fairly good agreement is obtained. Predictions of the dipole strength function for spherical and deformed nuclei within the valley of $\ensuremath{\beta}$ stability as well as in the neutron-rich region are discussed and compared with traditional Lorentzian-type prescriptions. Its impact on the total radiative width as well as radiative neutron and proton capture cross sections is studied.