PROPERTIES OF CSI-BASED GASEOUS SECONDARY-EMISSION X-RAY-IMAGING DETECTORS

Secondary emission detectors based on a thin solid photoconvertor coup led to a low-pressure gaseous electron multiplier provide subnanosecon d, parallax-free, high accuracy X-Tay imaging. The application of CsI photoconvertors was studied over a broad photon energy range. At norma l incidence, detector quantum efficiencies of 5-0.6% and localization accuracies of 200-500 mum (FWHM) were recorded with respective photon energies of 6-60 keV and CsI layers 200-4000 nm thick. At grazing inci dence an improvement of the order of 1/sin 1theta was demonstrated in localization accuracy and detection efficiency. Some preliminary indic ations on the CsI stability are reported and radiographic images of sm all objects are presented. Possible future applications of these devic es are discussed.