Minimization of channel electron multiplier background counting rate

In this paper we discuss background counting rate minimization of a channel electron multiplier (CEM) using it in simple pulse counting mode. The minimization was investigated by a variable additional bias voltage applied to an aluminium source carrier set in front of a CEM entrance tube. For an optimal bias voltage of -20 V we found the background counting rate to be reduced to one twenty fifth of its value with no additional bias voltage applied. (C) 2001 Elsevier Science Ltd. All rights reserved.