  We have developed and successfully tested a prototype of a new type of high
position resolution hybrid X-ray detector. It contains a thin wall lead glass
capillary plate converter of X-rays combined with a microgap parallel-plate
avalanche chamber filled with gas at 1 atm. The operation of these converters
was studied in a wide range of X-ray energies (from 6 to 60 keV) at incident
angles varying from 0-90 degree. The detection efficiency, depending on the
geometry, photon energy, incident angle and the mode of operation, was between
5-30 percent in a single step mode and up to 50 percent in a multi-layered
combination. Depending on the capillary geometry, the position resolution
achieved was between 0.050-0.250 mm in digital form and was practically
independent of the photon energy or gas mixture. The usual lead glass capillary
plates operated without noticeable charging up effects at counting rates of 50
Hz/mm2, and hydrogen treated capillaries up to 10E5 Hz/mm2. The developed
detector may open new possibilities for medical imaging, for example in
mammography, portal imaging, radiography (including security devices),
crystallography and many other applications.
