XCIV. Observations on the multiple scattering of ionizing particles in photographic emulsions.-Part II. The scattering of positrons at 105 and 185 MeV

Abstract

The coordinate method has been used to measure the multiple scattering in Ilford G5 emulsions of positrons of nominal energy 113 and 196 MeV. The energies of the positrons corrected for loss by ionization and radiation are calculated to be 105 and 185 MeV. respectively. The experimental distributions of second differences have been compared with those predicted by the theory of Molire (1947, 1948) and the agreement found to be very satisfactory. Methods of minimizing the effects of spurious scattering and of taking into account the influence of distortion are discussed. Values are found for the scattering constant which are in good agreement with those calculated from the theory of Molire. A discussion of these results has been given in a previous paper of this series (Gottstein et al. 1951). A mathematical treatment is given in the Appendices: (I.) the correlation existing between successive second differences, (II.) the distribution of second differences when measured in the presence of spurious scattering, and (III.) a possible method for correcting second differences which have been affected by a large angle scattering.