ON THE CONVERGENCE OF R-MATRIX CALCULATIONS FOR N = 2 EXCITATION OF HELIUM BY 29.6 EV ELECTRON

The 29-state R-matrix calculation of Fon et al is now extended to elec tron impact energy 29.6 eV to obtain differential cross sections and e lectron-photon coincidence parameters lambda and \chi\ for the n = 2 e xcitation. The results of this calculation are shown to make significa nt improvement over the 19-state calculation of Fon et al in getting c loser agreement with the latest experiments and the CCC calculation of Bray et al. The importance of the ionization continuum effects at 29. 6 eV is examined in the context of convergence of the R-matrix calcula tions and in comparison with the new experiments and theories.