HpXe gas VUV photosensors operating face-to-face

The operation of two photosensors operating face-to-face, having a high pressure xenon medium in between is investigated. Each photosensor consists on a CsI- MicroHole and Strip Plate (MHSP) operating within the pure xenon medium. A cluster of 7 stainless steel grids, with a 1:3mm gap between them, is placed between the photosensors. Applying a high voltage difference between consecutive grids, an electric field above xenon excitation threshold is established in the detection volume. The primary electrons resulting from x- or γ-ray -absorptions drift towards the anode grids, producing a large amount of VUV photons along their path. The position of the x- or γ-ray interactions along the direction perpendicular to the photosensors can be determined by weighing the signal amplitude of both photosensors. Experimental studies of the interaction position resolution and energy resolution as a function of gas pressure will be presented.