LINEARITY IN ELECTRON COUNTING AND DETECTION SYSTEMS

An analysis is presented, with supporting experimental measurements, of the non-linear effects in electron intensity measurements using channel electron multipliers (CEMs) in both the analogue amplification and pulse counting modes. It is shown that for Auger electron spectroscopy, where the CEMs may be used in the analogue mode, the output current should not exceed 0.8r% of the CEM wall current for the linearity to be maintained within r%. In the pulse counting mode, used more generally, simple dead time corrections are possible over a limited range of counting rates. This range is defined theoretically and experimental procedures are demonstrated to show how the range may be defined, and the necessary corrections made, to retain accurate linearity within 0.5%.