PPD (Compound-eye sensor made of semiconductors)
In experimental equipment for detecting radiation, as well as in that of elementary particles and atomic nuclei, weak-light detection devices (photo sensors) are needed. Because of their high performance and high reliability, photomultipliers introduced previously have been used in front line experimental facilities such as the Super-Kamiokande. However, as photomultipliers need a relatively large space and large-scale peripherals, they are difficult to use for applications requiring a lot of photo-sensors.
An epoch-making semiconductor photo-sensor is currently being developed in Russia, which can accomplish a dream of researchers, “High resolution experiments with 100,000 photo-sensors.” This sensor, called the “silicon photo-multiplier (SiPM),” can be operated near strong magnets and at several tens of volts, and thus researchers of all nationalities have paid attention.
Joining with Universities (Kyoto University, Kobe University, Shinshu University, University of Tsukuba, Nagoya University, Niigta University, and the National Defense Academy) and manufacturers, who have worked toward practical use in elementary particle experiments, KEK DTP has developed innovative photo-sensors (Figure 3)
Figure 3. New semiconductor photo-sensor: The size is almost comparable to that of transistors. The photosensitive part is 1 mm in diameter, which consists of fine pixels like the compound-eyes of insects.