The tracks left in a cloud chamber by low energy protons were observed in the absence of a magnetic field. Measurements of the curvature of the tracks due to multiple scattering verified quantitatively the results predicted by H. A. Bethe and W. T. Scott. For 1.08-Mev protons in air under a pressure of one atmosphere, the mean square curvature ${〈C^2〉}_{\mathrm{Av}}$ of the measured tracks was found to be ${〈C^2〉}_{\mathrm{Av}}=0.323\mathrm{}\times {10}^{-3\mathrm{}}$ ${\mathrm{cm}}^{-2\mathrm{}}$, for 1.05-Mev protons in argon ${〈C^2〉}_{\mathrm{Av}}=0.935\mathrm{}\times {10}^{-3\mathrm{}}$ ${\mathrm{cm}}^{-2\mathrm{}}$. For helium only qualitative results were obtained; they indicated smaller curvatures than for the other gases.

Close

PrevNext

View figure in article