Single Photon Counting X-Ray Imaging System Using a Micro Hole and Strip Plate

A Xe-based single photon counting X-ray imaging system, based on a micro-hole & strip plate (MHSP), using a resistive charge division method was implemented. The MHSP is a hybrid microstructure that combines in a single element the features of the gas electron multiplier (GEM) and the micro-strip gas chamber (MSGC), presenting two charge multiplication stages. For 2D-imaging, the GEM-like side (top side) is structured with strips orthogonal to the MSGC-like strips at the bottom side. Two thin orthogonal resistive lines of about 100 Omega, between the strips (top side) and between the anode strips (bottom side) allows us to obtain the actual position in both x and y directions. The four signals collected from the edges of the resistive lines are then digitized and processed with a computer. Charge gains of 10⁴ are obtained with the MHSP. Position resolutions of sigma_x = 130 mum and sigma_y = 250 mum were achieved for 8-keV X-rays, making it suitable for many applications in single photon X-ray imaging. First X-ray images produced by the system are presented together with a discussion of the image quality and future prospects.