Development of HPDs for applications in physics and medical imaging

We discuss the design, 1 CIMA = Computer Imaging for Medical Applications, www.cima-collabortion.org. GT = CERN to Gulf of Taranto. uction and first results of two Hybrid Photon Detectors (HPDs) under development for applications in neutrino physics and Positron Emission Tomography (PET). The concept of a large almost spherical HPD is being developed as instrumentation for a next generation underwater Cherenkov detector array. Its main advantages compared to a conventional hemispherical PMT are the considerably increased viewing angle, minimum transit time spread, high gain stability and immunity to the Earthʹs magnetic field, intrinsic to the design. A proximity focused ceramic HPD with a flat sapphire entrance window has been developed in the framework of a conceptual design study of a novel 3D Axial PET scanner. The PET–HPD is equipped with custom-designed fast front-end electronics, allowing sequential and sparse mode readout of its 208 pads. Prototypes of both HPDs are being built in a dedicated vacuum deposition facility at CERN.