Abstract
The multi-anode microchannel array (MAMA) is a photon counting detector which decodes the position of an event through coincidence discrimination. The decoding algorithm which associates a given event with the appropriate pixel is determined by the geometry of the array. In a standard MAMA detector, the pixel size is determined by the spacing of the anode array; however, the actual limiting factor to the pixel resolution is the spacing of the channels in the microchannel plate. The analog amplitude of charge amplifier pulses can be converted to digital quantities and employed for increasing the resolution of the detector by calculating the centroid position of each event in real time. This centroiding procedure can be implemented as an independent module of the decoder, operating in parallel with the standard digital decoding circuitry and providing the least significant bit(s) of the pixel address. Decoding hardware and techniques for enhanced pixel resolution are discussed in light of speed and complexity issues. A space-based realization of the MAMA detector requires that the decoding circuit be a single-chip monolithic or hybrid integrated circuit because of power, size and weight constraints. A single-chip CMOS gate array version of the decoder is discussed and contrasted with existing multi-chip decoders in terms of size, speed and power.