Applications of Glauber approximation to charted-particle-neutral-atom collisions

The recently proposed analytic methods of Thomas and Chan, which reduce the Glauber amplitude for charged-particle neutral-atom collisions to a one-dimensional integral representation involving modified Lommel functions, are used to study atomic collision problems. The individual n = 3 cross sections of atomic hydrogen by electron impact and the Balmer - α cross section predicted by the Glauber theory in the range 18 less than or equal to E/sub i/ less than or equal to 500 eV are compared with experiments and with other calculations. The polarization fractions of 3p-2s, 3d-2p, and of the Balmer - α line are also calculated in the Glauber approximation (GA), and comparison is made with the existing experimental data and with the Born predictions. The collision parameters (lambda,chi) predicted by the Glauber approximation are also given. The cross sections for the direct excitation of 31D and 41D states of helium by electron impact with incident energies from 40 to 1000 eV are evaluated and compared with the Born, Ochkur, and Woollings-McDowell results. The polarization fraction of the 6678-A helium line emitted in e--He collisions is calculated in the Glauber approximation too. The agreement between Glauber predictions and experimental data is fairly good except excitations to d (or D) states. Minima and maxima of the generalized oscillator strength for the 2s-3p transition of atomic hydrogen are found using the Glauber approximation. In contrast to the first-Born approximation, the number of extrema and their positions are found to vary with the energy of the incident particle, and the values at the minima do not vanish and vary as the incident energy is changed