Characteristics of a Funnel Type Electron Channel Multiplier with a Grid Entrance Window

The response uniformity across the entrance window of a 1 cm diam funnel electron channel multiplier has been increased by installing a high transparency grid in front of the multiplier and operating at the same potential. The funnel surface was scanned by a 1/8 diam 1-20 keV hydrogen atom beam. With either a negative potential applied to the front edge or positive potential to the collector, the response as indicated by the counting rate, was flat over the central 8-9 mm multiplier aperture. Measurements of the multiplier gain indicated maximum gain near the outer edge and minimum gain in the channel region.