A detector module composed of pixellated crystals coupled to SiPM strips

A detector based on a pixellated scintillator crystal coupled on two opposite sides to Silicon Photomultiplier (SiPM) strips is presented. In one direction the width of the SiPM strips matches the crystal pitch, while in the other direction the strip length is equal to the crystal pitch times the number of pixels in a row. The SiPM strips on one side are orthogonal to the strips on the other side. The crystal position can be identified using a row-column coding method. As a proof of concept, a small prototype using an array of 88 LYSO crystals, each one 1.5 mm 1:5 mm 10 mm in dimensions, has been built. The crystal is coupled on both sides to monolithic matrices composed of 8 SiPM strips, each one 1.5 mm wide (pitch) and 12 mm long by means of silicon grease. SiPMs strips have been obtained connecting in parallel single pixels belonging to a monolithic matrix, where each pixel has the same pitch of the scintillating crystal coupled to it. This arrangement allows a reduction from N2 to 2N of the number of analog channels needed to read-out the entire crystal array. Furthermore, this method provides the information about the Depth of Interaction of the primary particles impinging on the detector. The results of the prototype characterization in terms of energy and Depth Of Interaction resolution capabilities are presented here.