An Automated Retarding Potential Difference Technique Using a Multichannel Scaler

Abstract

A commercially available multichannel analyzer, used in the multiscaling mode, has been adapted so as to accumulate automatically data from electron beam experiments employing the retarding potential difference (RPD) technique for improving the electron energy resolution. The electron accelerating voltage is generated by digital‐to‐analog conversion of the ``live'' channel address, the lower and upper limits of the sweep being adjustable over a wide range. The analyzer is swept alternately in the add and subtract modes with a period which is short compared to possible drifts in electron current, collision chamber pressure, multiplier sensitivity, etc. The tedious labor involved in obtaining RPD data by conventional means, and its subsequent arithmetic reduction, is all performed automatically by the analyzer. Examples of data obtained by the technique are presented, showing the improvement in signal to noise obtainable by operating for a suitably large number of sweeps.