Absolute detection efficiencies of low energy H, H-, H+, H+ and
H+ incident on a multichannel plate detector
B.L. Peko and T.M. Stephen
Measured absolute detection efficiencies are presented for H, H- and Hy (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+) 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 r70% 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.
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Nuclear Instruments and Methods in Physics Research B 171, 597-604, 2000