Photoneutrons from 19F

Abstract

The 19F(γ,n) reaction was studied by irradiating teflon with bremsstrahlung of energy increasing from 13 MeV to 21 MeV in 1 MeV steps. Photoneutron spectra were measured by the time-of-flight method. Excited states of 19F at 12.10, 12.38, 13.82, and 16.24 MeV were observed. The total integrated cross section between 11.9 and 17.9 MeV was found to be (14.4 ± 2.2) MeV mb. Branching ratios to the first group of excited states of 18F compared to the ground state were measured, along with resonance widths and approximate radiative widths. They are consistent with the interpretation that all four states arise from electric dipole d → f valence transitions, with the first two states having Jπ = 1/2−, and the second two having 3/2−.