Total cross sections of positron-helium collision at intermediate energies

A modified Glauber amplitude, in which the eikonal approximation is considered from the third order of scattering onwards (instead of from the second order as in the conventional Glauber method), is applied to the analysis of e+-He elastic scattering. In particular, the method of calculating the scattering amplitude in the forward direction is emphasised and the total cross sections of the e+-He collision are derived via the optical theorem. Comparison with experimental data measured by various research groups is made and good agreement is obtained. (author)