The Transmutation of Fluorine by Protons

The excitation functions for the production of long range alpha-particles, gamma-rays, and electron pairs by the bombardment of ${\mathrm{F}}^{19}$ by protons have been observed simultaneously up to a bombarding energy of 1.5 Mev. The long range alpha and pair curves exhibit resonance peaks superimposed on a background of increasing intensity with increasing bombarding energy. Approximate coincidence in two instances of pair and alpha-resonances suggests that full range alphas and the short range alphas preceding pair emission can be products of competing modes of decay of the same intermediate states of ${\mathrm{Ne}}^{20}$. This in turn suggests that the state of ${\mathrm{O}}^{16}$ which decays by pair emission has the same parity (even) as the ground states of ${\mathrm{O}}^{16}$ and thus that the pair emission can be due to ordinary electromagnetic forces. The absolute yields of the various processes have been measured and a discussion of the measurement of high energy gamma-ray and pair yields by means of electroscopes is given. The large ratio of gamma-ray yields to long range alpha and pair yields previously observed has been confirmed.