Absolute Efficiency Measurements for Channel Electron Multipliers Utilizing a Unique Electron Source

A unique low energy (0–50 keV) electron accelerator has been developed which provides a broad, parallel, low intensity electron beam with excellent long term stability. The beam intensity is approximately 106 electrons·cm−2 ·sec−1 and the long term stability is better than 2%/day. A prototype of this accelerator is described and the results of its application to instrument calibration and channel electron multiplier (CEM) efficiency measurements are presented. The absolute electron detection efficiency for CEM's was found to vary from approximately 90% at 1 keV to 73% at 14 keV with a probable error of ±10%. The large disagreement among the various published measurements of CEM detection efficiency is discussed.