2D-sensitive HpXe gas proportional scintillation counter

The operation of a detector working in Gas Proportional Scintillation Counter (GPSC) mode, with pure xenon, envisaging medical imaging is presented. The GPSC uses a CsI-Micro-Hole and Strip Plate (MHSP) based photosensor for scintillation readout. To define the scintillation region, a pair of stainless steel meshes is placed above the photosensor. A voltage is applied between meshes to establish an electric field with a value above the xenon excitation threshold but below the ionization threshold. The voltage difference between the radiation window and the first mesh establishes an electric field in the drift region, set below the xenon excitation threshold. The resulting scintillation is generated when the electron cloud, produced in xenon, following x- or ??-ray interactions, crosses the gap between the meshes. The interaction position of the x- or ??-photons in the xenon medium can be found by determining the centroid of the resulting photosensor illumination. In the CsI-MHSP photosensor the 2D capability is achieved by using two orthogonal resistive lines interconnecting the strips patterned on both surfaces. Preliminary studies of the detector imaging response using 59.6 ??-photons are presented.