The multiple scattering theories of Williams. and Moliere have been adapted to give the r.m.s. lateral deflection of protons which lose all their energy in nuclear emul� sions. Measurements of 1-5 MeV proton tracks show significant differences from the former theory at low energies and from the latter at higher energies. The introduction of alternative expressions for the minimum angle due to screening does not give a satisfactory explanation of the observed results. It is found, however, that the experi. mental r.m.s. deflections display the same dependence on maximum single scattering angle as is calculated.
Multiple Scattering of Fast Electrons