Inelastic collisions between hydrogen and helium atoms

A study is made of the excitation of atomic hydrogen to the 2s, 2p, 3s, 3p and 3d states by collision with helium and of excitation of the 2 1 S and 2 1 P states of helium by collision with atomic hydrogen. The first Born approximation is employed to calculate total cross sections (with full account taken of double transitions) for 3s, 3p and 3d excitation and to calculate the polarization of Lyman alpha radiation emitted from H(2p). The effect of coupling of states is investigated for single transition reactions (the target atom remaining in its ground state) occurring in all the above excitations by employing the impact parameter method and including ten states.