Low-energy elastic scattering of electrons and positrons from helium atoms

In this paper we calculate the electron-helium atom pseudopotential, and from that pseudopotential the cross section for low-energy elastic scattering of electrons from helium atoms. The agreement between experiment and theory is good. In addition, the scattering of low-energy positrons from helium atoms is considered. The case of electron-helium atom scattering is chosen only as an example of the use of the pseudopotential as a natural tool for the study of scattering problems. The numerical calculations demonstrate that the results obtained in this way are of comparable accuracy with the results of more tedious and less instructive approaches. In particular, the use of pseudopotential arguments leads to an easily understood physical description. Moreover, because the pseudopotential approach permits the use of variational procedures, even in the presence of bound (i.e., core) states, the necessary calculations are not difficult to carry through.