Cross section for the reaction 16O(γ,n0)15O at giant resonance energies

Abstract

The cross section for that photoneutron reaction in 16O which leaves 15O in its ground state has been measured for photon energies ranging from 17 to 30 MeV, i.e. at energies corresponding to giant resonance excitations in 16O. Time-of-flight methods, yielding resolutions equal to 100 keV at a neutron energy of 6 MeV, were used to measure neutron spectra emitted at an angle of 98° when targets of ordinary and heavy water were irradiated with pulsed bremsstrahlung. The differential cross section at 22.3 MeV excitation was found to be 1.00 ±.05 mb/sr, assuming a photodisintegration cross section at 98° equal to 55.3 μb/sr (laboratory system) for deuterium, this latter value having been derived from calculations which have been substantiated experimentally to within ± 10%. The results are discussed with reference to other photodisintegration experiments and to recent theoretical work.