A neutron threshold technique involving observations of the gamma rays from the de-excitation of the residual excited states is described. A study of the ${\mathrm{O}}^{18}(d, n\gamma ){\mathrm{F}}^{19}$ reaction with this technique has resulted in the observation of neutron thresholds at bombarding energies of 346±8, 525±8, and 584±10 kev. These thresholds correspond to states at 6.048±0.014, 6.210±0.014, and 6.262±0.015 Mev in the ${\mathrm{F}}^{19}$ nucleus, respectively. A detailed gamma-ray spectrum was obtained at a bombarding energy of 1.00 Mev using a single-crystal spectrometer, and another detailed spectrum was obtained at 1.40 Mev using a three-crystal pair spectrometer. Coincidence measurements were made for several of the cascade gamma rays.

• Received 19 June 1958

DOI:https://doi.org/10.1103/PhysRev.112.461