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 ionizat ion, 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 th e ejected electrons and a cylindrical electrostatic analyzer for the s cattered electrons. It allows angular and energy distributions of the ejected electrons to be measured over almost the totality of the colli sion plane, using dual two-dimensional position sensitive detectors. T he design and operation of the spectrometer is described with a specia l emphasis on the imaging properties of the system. The performance (e nergy and angular resolutions,...) and the calibration of the spectrom eter 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 In stitute of Physics. [S0034-6748(98)03310-3].