Low Energy Charged Particle Detection using the Continuous Channel Electron Multiplier

It has been found to be possible to operate the continuous channel electron multiplier, a recently developed type of windowless electron multiplier, in a gain saturated mode such than single charged particles entering the input mouth of the channel will initiate output pulses whose amplitude and shape are both uniform and independent of the character of the excitation radiation. By suitable design of the channel this saturated pulse can be made stable against changes in such operating conditions as ambient pressure and applied voltage. Some degradation in the pulse height distribution is noted at very high count rates but operation for short periods at count rates of at least 105 per second is possible. When operated in this mode the efficiency of the channel for the detection of electrons over the energy range 250 eV to 10 keV is estimated to be greater than 50%. The channel multiplier has been used as the detector in rocket borne low energy electron spectrometers to obtain the energy spectrum of the auroral electrons. Data indicate that the operation of the detectors was as expected.