High-gain imaging electron multiplier

Abstract

The chevron-shaped channel electron multiplier is a device which combines the high-gain pulse-counting operation of single channel electron multipliers with the imaging capabilities of microchannel arrays. It produces charge pulses averaging more than 107 electrons and these gain magnitudes fall into a quasi-Gaussian distribution with a full width at half-maximum FWHM of approximately 130%. Suppression of ion feedback makes possible both imaging and low noise counting applications over large areas. Dark count rates are typically 1 count/sec cm2, and the dynamic range of operation covers 5–6 decades. Active areas over 45 mm diam have been fabricated, with uniform characteristics. Limiting resolution has been measured at 5 line pairs per millimeter. Because of the short length of each channel electron multiplier, the rise time and width of the output charge pulses are extremely short; large signal pulses have been detected with rise times as short as 400 psec.