Photoneutron cross sections for samarium isotopes: Toward a unified understanding of (gamma, n) and (n,gamma) reactions in the rare earth region

Photoneutron cross sections were measured for the seven stable samarium isotopes Sm-144,Sm-147,Sm-148,Sm-149,Sm-150,Sm-152,Sm-154 near the neutron threshold with quasi-monochromatic laser-Compton scattering gamma rays. Our photoneutron cross sections are found to be low by 20%-37% relative to existing data. The photoneutron data are analyzed with the TALYS reaction code by considering the Skyrme Hartree-Fock-Bogoliubov (HFB) plus quasiparticle random phase approximation (QRPA) model and the axially symmetric deformed Gogny HFB plus QRPA model of the E1 gamma-ray strength. Using the gamma-ray strength function constrained by the present photoneutron data, we made a thorough analysis of the reverse (n,gamma) cross sections including the radioactive nucleus Sm-151 with a half-life of 90 yr. The radiative neutron capture cross section for Sm-153 with the half-life of 1.928 d is deduced with the gamma-ray strength function method.