By measuring the radioactivity produced when ${\mathrm{F}}^{19}$ is bombarded with monoenergetic neutrons, the excitation functions and absolute cross sections have been obtained for the ${\mathrm{F}}^{19}(n, \alpha ){\mathrm{N}}^{16}$ and ${\mathrm{F}}^{19}(n, p){\mathrm{O}}^{19}$ reactions from energies at which the respective activities were first observed to 8.0 Mev. The occurrence of the ($n, \alpha$) reaction was first observed at a bombarding energy of 3.1 Mev; the ($n, p$) reaction was first observed at 4.7 Mev. Several resonances were found in the ($n, \alpha$) excitation function, while the ($n, p$) excitation function showed a single maximum at 7.5 Mev. For neutron energies up to 8.0 Mev, the ($n, \alpha$) reaction cross section is larger than that for the ($n, p$) reaction by a factor of 2 or greater.

• Received 13 June 1955

DOI:https://doi.org/10.1103/PhysRev.100.69