Patent ID: 8618457
Filing Date: 2013-12-31
Classification: H01J

Abstract:
1. A method of measuring an anode current in an electron multiplier device having a cathode at or near circuit ground potential, an anode at a relatively high positive potential, a series of discrete dynodes at successive intermediate potentials, and a voltage divider comprising a string of transistors connecting the dynodes to respective points in a resistor string of the voltage divider, the method comprising: passing at least some of the dynode currents successively through the string of transistors; summing currents flowing in the dynodes and optionally also a cathode current, and deriving the measured current from the summed currents; and subtracting from the summed dynode currents a standing current in the voltage divider to measure substantially at ground potential a current representative of the anode current and derived from current flowing in the dynodes, without taking a measurement of a current between the anode and the dynode adjacent to the anode.