Development of Sealed Tube Microchannel Plate Detectors with Cross Strip Readouts

Abstract

Cross strip readout anodes provide a novel high spatial resolution image encoding system for microchannel plate sensors. We have developed cross strip readouts with metal & ceramic layers for 50 mm format sealed tubes based on the "Planacon" concept. These have next generation atomic layer deposited microchannel plates for amplification and selected photocathodes covering the UV and optical regimes. These devices will be relevant for the next generation of moderate and large NASA astrophysics instruments that are baselining 50 mm to 200 mm format detectors. The critical elements of the sensors are high QE, high spatial resolution and large event rate limits, with long lifetimes. Our photocathode work includes customization of bialkali semitransparent cathodes with response from 120 nm to 320 nm and a sharp 360 nm cutoff. Opaque alkali halide photocathodes on the atomic layer deposited microchannel plates have shown high quantum efficiencies (50% @ 115 nm) and could be used simultaneously with bialkali photocathodes. The atomic layer deposited microchannel plates have borosilicate substrates which are robust and can be be produced in large formats (20 × 20 cm) with high open area ratios (~73%). These MCPs have very low intrinsic background (<;0.06 events/sec/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ), high gain, and very good lifetime stability. With the cross strip readout and encoding electronics we achieve high spatial resolutions (<;20 μm FWHM) over both 50 mm and 100 mm formats at event rates exceeding 5 MHz, providing a powerful baseline for future NASA UV/optical instruments.