Download or read book Differential and Integral Cross Sections for Excitation of the 2 Singlet S State of Helium by Electron Impact written by David C. Cartwright and published by . This book was released on 1971 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experimental measurements of the differential scattering cross sections for excitation of helium by electron impact from its ground state to its 2 singlet S state are given at four incident electron energies in the range 26-55.5 eV for scattering angles between 10 and 70 deg and at 81.6 eV for scattering angles between 10 and 80 deg. These experimental cross sections and cross section ratios are compared with results predicted by the Born approximation, the polarized Born approximation, and several other first-order approximations in which direct excitation is calculated in the Born approximation and exchange scattering in various Ochkur-like approximations. Calculations based on these approximations are also compared to the data of other experimenters. The effect on the small-angle scattering of several nonadiabatic dipole-polarization potentials is examined. (Author).