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

Abstract

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> A Xe-based single photon counting x-ray imaging system, based on a Micro-Hole &amp; 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 <formula formulatype="inline"><tex Notation="TeX">$\Omega$</tex></formula>, between the strips (top side) and between the anode strips (bottom side) allows us to obtain the actual position in both <formula formulatype="inline"><tex Notation="TeX">$x$</tex> </formula> and <formula formulatype="inline"><tex Notation="TeX">$y$</tex> </formula> directions. The four signals collected from the edges of the resistive lines are then digitized and processed with a computer. Charge gains of <formula formulatype="inline"><tex Notation="TeX">$10^{4}$</tex></formula> are obtained with the MHSP. Position resolutions of <formula formulatype="inline"><tex Notation="TeX">$\sigma_{x}=130\ \mu{\rm m}$</tex></formula> and <formula formulatype="inline"> <tex Notation="TeX">$\sigma_{y}=250\ \mu{\rm m}$</tex></formula> 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. </para>