Transmission Measurement of the Absolute CMA; Simulation and Experiments

Abstract

  We measured the transmission of the cylindrical mirror analyzer (CMA) by using a mini-electron gun consisting of a tungsten hairpin cathode set at the sample position. The electron beam current (i_in) entering the CMA was measured using a retractable Faraday cup and an electrometer. The electrons get through the CMA and finally the detected current (i_out) representing only a fraction of the input current was measured using another Faraday cup (normally used for detecting Auger electrons) and another electrometer. The ratio of the i_out to i_in gives the transmission of the CMA. Besides the experiment, we simulated the transmission characteristics, i.e., peak heights, position, and full width at half maximum, assuming thermionic emission and Gaussian peak shape. The simulation revealed characteristics that the experiments would not show explicitly. An optical transmission measurement was performed as well providing a good agreement with the results of the present electron beam measurements.