A HIGH-SENSITIVITY MOMENTUM DISPERSIVE MULTICHANNEL ELECTRON MOMENTUM SPECTROMETER FOR STUDIES IN EXPERIMENTAL QUANTUM-CHEMISTRY

The design and characterization of a high sensitivity multichannel momentum dispersive electron momentum spectrometer is reported. Electron pair coincidences are detected over a +/- 30 degrees range of azimuthal angle at the exit slit of a cylindrical mirror analyzer configured to measure symmetric (theta = 45 degrees) noncoplanar (e,2e) scattering. A position sensitive microchannel plate/resistive anode encoder electron detector and a channeltron electron multiplier are employed in a novel multichannel coincidence detection system based upon detection of ''pile-up'' of pairs of timing pulses from the detectors. Proof-of-concept results, exhibiting significantly higher coincidence count rates and statistical precision than have been previously observed in electron momentum spectroscopy, are presented for argon.