γ-Ray Strength Functions and GDR Cross Sections in the IAEA Photonuclear Data Project

Abstract

We present the latest development of measuring (γ, n) cross sections and giant dipole resonance (GDR) cross sections in the IAEA photonuclear data project. Photoneutron cross sections were measured for 21 isotopes below 2n threshold to construct the γ-ray strength function (γSF) with the γSF method; (γ, n) cross sections are used as experimental constraints on the model E1 and M1 γSFs from the Hartree–Fock–Bogolyubov plus quasi-particle random phase approximation based on the Gogny D1M interaction supplemented with the M1 upbend. GDR cross sections were measured for 11 nuclei from 9Be to 209Bi by direct neutron-multiplicity sorting with a flat-efficiency neutron detector toward a goal of resolving the long-standing discrepancy between the Livermore and Saclay data. We present γSFs for the Ni isotopic chain and GDR cross sections for 159Tb as well as those updated for 209Bi.