Spiral Electron Multiplier Operation Characteristics Using Positive Ions

Operational characteristics of a spiral electron multiplier are discussed, and measurements of gains and detection efficiencies using positive ions are presented. These parameters were observed during lifetime tests on two multipliers. Gains above 107 were found up to 1011 accumulated counts. The detection efficiencies for ions in the mass region from 4 to 40 amu varied between approximately 60% and 90% for incident energies of 3–4.5 keV.