The Disintegration of Fluorine by Protons

Citation

Streib, John Fredrick (1941) The Disintegration of Fluorine by Protons. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/0d3y-e127. https://resolver.caltech.edu/CaltechTHESIS:02242025-233007118

Abstract

The excitation functions for the production of long-range alpha particles, gamma rays, and electron pairs by the bombardment of F¹⁹ with protons were measured to 1.5 mev bombarding energy. To permit the identification of coinciding resonances in different types of radiation, the three types were observed simultaneously. The excitation functions are plotted. Approximate coincidence in two instances of pair and alpha resonances suggests that the same state of Ne²⁰ may decay in such a way as to give rise to both types of radiation; the slight separation of the nearly coincident peaks might be explained as a displacement of the alpha peak from the true energy value due to an interference between the resonant process and the continuous rise upon which it is superimposed. If this conclusion is accepted, it follows that the state of O¹⁶ which gives rise to electron pairs has even parity, and it is possible to describe the production of pairs without assuming other than electromagnetic forces between the nuclear particles and the pair field. There is no coincidence of gamma-ray resonances with those of the pairs or long-range alpha particles.

The yields of the three modes of disintegration were estimated. At 0.334 mev resonance the intensity of gamma rays agrees within 20 per cent with a direct measurement of short-range alpha-particle production by Van Allen and Smith, giving additional evidence in favor of the accepted disintegration scheme.

A scheme of energy levels accounts for the existence of the various resonances, but not for their relative intensities. It is especially difficult to explain the high intensity of the gamma rays compared with the pairs and alpha particles.

Thesis Files