Spin-allowed and spin-forbidden transitions in excited He atoms induced by electron impact

Cross sections sigma and the corresponding maxwellian rate coefficients <v sigma> have been calculated for spin-allowed and spin-forbidden n - n' transitions between excited states with the principal quantum numbers n, n' = 2, 3 and 4 in He induced by electron impact. Calculations have been performed using the Coulomb-Born approximation with exchange (CBE) in the partial wave representation with orthogonalized wavefunctions of the initial and final states for the incident electron energies from threshold up to 2000 eV for spin-allowed transitions (Delta S=0) and up to 200 eV for spin-forbidden (intercombination, Delta S=1) transitions where the corresponding cross sections are still relatively large. The fitting parameters for sigma and <v sigma> of spin-allowed transitions have been calculated as well. The results are compared with experimental data and other calculations available.