Resonance phenomena in the disintegration of fluorine by protons

Abstract

The bombardment of fluorine with protons gives rise to a strong emission of γ -radiation of quantum energy about 6.0 x 10 6 eV. The excitation function for this process shows a series of sharp resonances for proton energies up to about 2 x 10 6 eV (Hafstad, Heydenburg and Tuve 1936; Bernet, Herb and Parkinson 1938; Curran, Dee and Petržilka 1938). If the γ -rays are attributed to a simple capture process according to the scheme 19 F + 1 H→ 20 Ne*→ 20 Ne + hv , (1) maximum quantum energy of the γ -radiation would be 13.1 x 10 6 eV according to accepted mass values, whereas measurements of the γ -ray spectrum show the presence of only one line of energy between 6.0 and 6.5 x 10 6 eV (Delsasso, Fowler and Lauritsen 1937; Dee, Curran and Strothers 1939). This discrepancy might be explained in several ways: (1) The γ -ray emission from the excited state of 20 Ne formed as the compound nucleus in reaction (1) might occur by the successive emission of two quanta, each of energy about 6.5 x 10 6 eV. (2) The emission of a single γ -ray quantum of energy 6.5 x 10 6 eV might result in the formation of a less excited Ne nucleus which might then disintegrate into 16 O and an α -particle. * The symbol 20 Ne* used in this paper denotes a 20 Ne nucleus in an excited state.