Atomic and molecular processes, especially electron and positron scattering; Plasma physics.
I carry out theoretical research on the scattering of electrons and positrons from atoms and simple molecules. I am particularly interested in scattering from heavy atoms, and use the relativistic Dirac equations as the basis for computation of scattering parameters. Collaborating with graduate students and international co-workers, we perform large scale numerical computations of these processes and develop theoretical and numerical methods to carry them out. For example, we have developed the very successful Relativistic Distorted-Wave Method for evaluating the scattering cross sections as well as the spin polarization parameters for the scattered electrons and the Stokes parameters for the light emitted from atoms excited during the scattering interactions. I am also involved in projects which make use of the atomic data we generate. Much of our work is of use in plasma physics, particularly in the modeling of low pressure plasmas. One example is a large-scale Monte Carlo simulation of gas-filled X-ray detectors. I maintain close contact with various experimental groups and often publish joint papers with these groups where theory and experiment can be directly compared.