Multiple scattering of protons in thick gas targets

Abstract

Small angle multiple scattering distributions of 9.9 and 13.9 MeV protons were measured in thick gas targets of H 2, D 2, He, N 2 and Ar. The target thicknesses ranged between 13 and 26 mg/cm 2. The data were compared with theoretical predictions of Molière, Bethe, Fano and Marion and Zimmermann, which differ substantially in the case of hydrogen. Only the predictions of Fano are in good agreement with the experimental results. The simple formula of the Particle Data Group for the 1/e widths yields predictions which deviate less than 10% from the data. Theoretical expressions are summarized for easy application.