Photoneutron Cross Sections for Au Revisited: Measurements with Laser Compton Scattering γ-Rays and Data Reduction by a Least-Squares Method

Photoneutron cross section measurements were made for Au in the entire energy range of the (γ,n) channel based on a direct neutron counting with quasi-monochromatic γ-rays produced in inverse Compton scattering of laser photons with relativistic electrons. The data were analyzed by a least-squares method to deduce photoneutron cross sections. The analysis significantly reduced experimental uncertainties compared with those resulting from the photon difference method. The result is compared with the previous data by direct neutron counting with γ-rays produced in positron annihilation in flight and by photoactivation with bremsstrahlung. The present data are in good agreement with the previous data near the neutron threshold, while there remain some discrepancies between the present and the previous data above 10 MeV.