Improvements in microchannel plate operating characteristics

Abstract

Studies have been carried out to overcome two disadvantages of multichannel plates (MCPs): (1) saturation effects in the count rate at high incident particle/photon fluxes, which may be further complicated by the presence of fusion neutron/gamma radiation, and (2) extraneous noise generated by gyroelectrons originating from the negatively biased input surface of the MCP when the detector is operated in an external magnetic field (B=100 G), which is parallel to the input surface of the plate. A hot MCP is presently under investigation. This detector supports an increased strip current, which is expected to yield at least an order of magnitude improvement in count rate before saturation occurs. Initial attempts to eliminate the spurious noise problems due to gyroelectrons were focused on shielding the MCP from external magnetic fields by enclosing the detector in a soft iron shield. The current concept entails a method to ground the input surface of the MCP and bias the exit anode pad (previously at ground potential) to +2100 V. This method requires capacitive coupling of the anode pad to the signal processing electronics.<>