Sullivan, JamesMarler, Joan PGilbert, Stephen JBuckman, StephenSurko, Clifford M2015-12-080031-9007http://hdl.handle.net/1885/33430An accumulator, and an apparatus for low energy collision studies were used to measure absolute collision cross sections for selected electronic excited states of Ar, H2, and N2. For Ar and H2, comparison was made with theoretical calculations. Results obtained in the H2 measurements resolve the discrepancy between the available calculations.Keywords: Argon; Atoms; Electronic structure; Energy absorption; Hole traps; Hydrogen; Molecular structure; Nitrogen; Electronic excitation; Penning-Malmberg trap; Positron impact; Positrons20012015-12-08