High-resolution imaging x-ray detector

We describe an x-ray detector using microchannel plates as a photocathode surface and imaging photoelectron multiplier, and a crossed wire grid as a two-dimensional position-sensitive detector. The position resolution is σ=10 μ. The crossed wire grid consists of 100-μ-diam wires on 200-μ centers. Position sensing is accomplished by electronic interpolation to 1/20 of the wire spacing. The quantum efficiency of the microchannel plates varies from 29% at 0.28 keV to 5% at 3 keV. This detector will provide second-of-arc x-ray imaging in the focal plane of the 342.9-cm focal length grazing incidence telescope now being prepared for the HEAO-B observatory. By addition of suitable photocathodes, it can be used for single-photon imaging light detection in uv, visible, and near ir as well. In all cases, it gives a very low dark counting rate, allows timing of individual events to 1 μsec or less, and can handle counting rates up to 104 sec−1.