Pixel Detectors for Tracking and their Spin-off in Imaging Applications

To detect tracks of charged particles close to the interaction point in high energy physics experiments of the next generation colliders, hybrid pixel detectors, in which sensor and read-out IC are separate entities, constitute the present state of the art in detector technology. Three of the LHC detectors as well as the BTeV detector at the Tevatron will use vertex detectors based on this technology. A development period of almost 10 years has resulted in pixel detector modules which can stand the extreme rate and timing requirements as well as the very harsh radiation environment at the LHC for its full life time and without severe compromises in performance. From these developments a number of different applications have spun off, most notably for biomedical imaging. Beyond hybrid pixels, a number of trends and possibilities with yet improved performance in some aspects have appeared and presently developed to greater maturity. Among them are monolithic or semi-monolithic pixel detectors which do not require complicated hybridization but come as single sensor/IC entities. The present state in hybrid pixel detector development for the LHC experiments as well as for some imaging applications is reviewed and new trends towards monolithic or semi-monolithic pixel devices are summarized.