Absolute detection efficiencies of low energy H, H −, H +, H 2+ and H 3+ incident on a multichannel plate detector

Abstract

Measured absolute detection efficiencies are presented for H, H − and H n + ( n=1,2,3) impacting a commercially available, dual multichannel plate (MCP) electron multiplier at kinetic energies ranging from 30 to 1000 eV. Measurements involving isotopic substitutions (D, D −, D n +) and Ar + are also presented. In addition, atomic hydrogen detection efficiencies relative to those of H + and H − are given, as they may have a more universal application. For the three charge states, H, H + and H −, the absolute detection efficiencies are markedly different at low energies and converge to a nearly uniform value of ∼70% with increasing projectile energy. The energy dependence is strongest for H +, varying nearly three orders of magnitude over the energy range studied, and weakest for H −, varying by less than one order of magnitude. In general, for the low energy positive ions at a given energy, the lighter the incident particle mass, the greater the probability of its detection.