The behavior of two type-4013 Bendix Channeltrons as single particle detectors has been investigated and the efficiency of detection for protons and electrons has been measured in a vacuum of 10-6 Torr. It has been established that under electron bombardment the gain decreases with time approaching an asymptotic value G∞ which depends only on the intensity of the incident flux. An empirical formula for the dependency of G∞ on the flux in the range 103 to 106 electrons/sec has been derived, G∞ = (1.3×10 10)/J, where J is the incident flux measured in electrons per second and the high voltage applied to the Channeltron is 3 kV. When the bombarding beam is turned off the gain is always found to recover its initial value. The efficiency for electrons and protons does not show any dependency on the gain or on the particular Channeltron used. © 1969 The American Institute of Physics.
