A study of inelastic electron scattering in He covering the complete angular range from to

Abstract

Differential cross sections for electron impact excitation of the first four excited states of helium have been measured for electron impact energies of 30, 40 and 50 eV. A novel `magnetic angle-changing' technique has been used which allows the full angular range from to to be covered for the first time. Serious discrepancies between theory and experiment have been found at angles that were previously inaccessible experimentally.