Development of single-particle detectors for keV ions

Abstract

A series of three single‐particle detectors for the detection of ions with keV energies has been built and investigated by experiment and by computer simulation. The incident ions hit a converter electrode and produce secondary electrons which are accelerated onto the funnel of a channel electron multiplier (CEM). Experimental information was obtained for secondary electron yields, γ, of slow multiply charged ions and the influence of γ on the detector efficiency ε is discussed. Efficiencies ε near unity have been achieved for ions incident on an effective area of more than 20 mm diameter. ε is greater than 90% for all ions and for count rates up to 3×10⁴ s⁻¹. The performance at higher count rates can probably be improved with a CEM of lower resistance.