Statistical Fluctuations on Energy Deposited in Low-Atomic-Number Materials by 43.7-MeV Protons

The frequency distribution of energy losses in a He-C${\mathrm{O}}_2$ mixture by 43.7-MeV protons was investigated by means of a proportional-counter technique. The distributions corresponding to mean energy losses of 1.64, 8.22, 16.4, and 49.5 keV were examined. Relatively good agreement was found between experimental data and Vavilov's formulation of the Landau effect for the 49.5-keV distribution. For the other distributions, corresponding to smaller mean energy losses, the discrepancy between experiment and theory increased as the mean energy loss decreased. Correction of the Vavilov distributions by use of the Blunck-Leisegang factor gave good agreement with the experimental data.