The Pulsed Electron Beam Time-of-flight Method for Measuring Absolute Total Cross Sections: Atomic Helium

Abstract

Improvements in a previously reported experimental method have made it possible to obtain absolute total electron-scattering cross sections with a predicted accuracy of better than ± 2 % (10') for certain electron kinetic energies. As a first example of the application of the new procedures the cross section for helium is reported from O' 8 to 50· 0 eV. Error estimates for all known sources of uncertainty are discussed in detail. The results confirm the earlier work of Kennerly and Bonham and the agreement is, on the average, better than 1 % with no changes in the cross-section shape.