New concepts for the design of large area gas proportional scintillation counters

New concepts are presented that allow the design of gas proportional scintillation counters with the large areas and medium-size photomultipliers. These designs are based on the compensation of the radial decrease of the scintillation light collected in the photomultiplier due to solid angle and reflection effects, with a radial increase of the light production due to a nonuniform electric field produced by a properly shaped curved grid. An implementation of these concepts based on a 2-in-diameter photomultiplier is presented. It shows a pulse amplitude variation along the radial position (0 to 10 mm) of less than 0.5%, and an energy resolution of 8.0% for a broad 5.9-keV X-ray beam entering the detector through the full 25-mm-diameter window.<
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