THE ISPA-TUBE AND THE HPMT, 2 EXAMPLES OF A NEW CLASS OF PHOTODETECTORS - THE HYBRID PHOTO DETECTORS

A new class of photodetectors, the Hybrid Photo Detectors (HPD), is co ming up as a major breakthrough in photodetection. The principle of th e HPD is to couple a fully depleted silicon diode or silicon diode arr ay to a photocathode in a vacuum tube. At present HPD's with one diode or a few diodes (Hybrid Photo Multiplier Tubes, HPMT) are commerciall y available (DEP, The Netherlands, and Hamamatsu, Japan) and a positio n sensitive photon detector (the Imaging Silicon Pixel Array tube, ISP A tube) is under development in our group (in collaboration with the R D-19 collaboration at CERN). We shall present the main features of HPD 's and then our main results-and applications for both HPMT's and ISPA tubes on photon counting, on imaging and on high energy physics appli cations.