A multidetection, multicoincidence spectrometer for (e,2e) and (e,3e) electron impact ionization measurements

A new spectrometer for the coincidence study of (e, 2e) single ionization, and e,(3-1) e or (e, 3e) double ionization by electron impact is described. The system is based on two double toroidal analyzers for the ejected electrons and a cylindrical electrostatic analyzer for the scattered electrons. It allows angular and energy distributions of the ejected electrons to be measured over almost the totality of the collision plane, using dual two-dimensional position sensitive detectors. The design and operation of the spectrometer is described with a special emphasis on the imaging properties of the system. The performance (energy and angular resolutions,...) and the calibration of the spectrometer are discussed and sample results for ( e, 2e), e,( 3-1) e and (e, 3e) experiments on the rare gases are presented. (C) 1998 American Institute of Physics. [S0034-6748(98)03310-3].