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 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.<>