Properties of CsI-based gaseous secondary emission X-ray imaging detectors

Abstract

Secondary emission detectors based on a thin solid photoconvertor coupled to a low-pressure gaseous electron multiplier provide subnanosecond, parallax-free, high accuracy X-ray imaging. The application of CsI photoconvertors was studied over a broad photon energy range. At normal incidence, detector quantum efficiencies of 5-0.6% and localization accuracies of 200–500 μm (FWHM) were recorded with respective photon energies of 6–60 keV and CsI layers 200–4000 nm thick. At grazing incidence an improvement of the order of 1/sin ϑ was demonstrated in localization accuracy and detection efficiency. Some preliminary indications on the CsI stability are reported and radiographic images of small objects are presented. Possible future applications of these devices are discussed.