The Disintegration ofLi7Bombarded by Slow Protons

Abstract

The number of ${\mathrm{Li}}^7$ atoms disintegrated by protons of energies from 23.6 to 72.5 electron kilovolts has been determined. Oppenheimer's integration of Gamow's equation giving the probability of the lithium-proton disintegration as $n=bV{e}^{\frac{-a}{V^{\frac{1}{2}}}}$ has been compared with the experimental data by plotting $logn-logV$ against $\frac{1}{V^{\frac{1}{2}}}$. The agreement is within the experimental error. The results of the present experiment have been compared with other observer's data taken at higher voltages; the slopes of the lines have been found to vary somewhat. No indications of resonance nor of a minimum voltage required for disintegration were observed. Considerable difficulty was encountered as regards surface contamination of the target and also the formation of a highly insulating layer of lithium oxide. The latter effect made necessary the frequent use of a Faraday chamber for recording the proton current. An FP-54 pliotron in a modified form of the DuBridge-Brown balanced circuit was used in photographic recording of the alpha-particles.