SHAPE AND DYNAMICS OF THE 3(3)D STATE OF HELIUM EXCITED BY 40-EV ELECTRONS

Experimental and theoretical studies of excitation of the 3(3)D state of helium by 40 eV electrons are reported. Experimentally, electron-ph oton polarization correlations are measured in the scattering plane de fined by the incident and scattered electron momenta These are combine d with previously reported linear and circular polarization measuremen ts perpendicular to the scattering plane. After allowing for the effec ts of fine structure depolarization, parameters describing the shape a nd dynamics of the excited state produced in the collision are determi ned. Theoretically, the measured polarizations and excited state param eters are predicted using the convergent close coupling (ccc) theory. Excellent agreement is obtained between the experimental and theoretic al results.