QUPID, a single photon sensor for extremely low radioactivity

We have successfully developed a new photon sensor, the Quartz Photon Intensifying Detector (QUPID), for experiments such as dark matter searches and observation of double beta decay. The QUPID is a type of hybrid-photo-detector (HPD), consisting of a special bialkali photocathode considering the operation under extremely low temperature such as the temperature of liquid xenon, −108°C, and a special avalanche photodiode for electron bombardment. The QUPID is constructed solely from extremely low radioactive materials, such as quartz and Si-avalanche photodiodes (APDs), which allows it to reach radiation levels of less than 1mBq while being able to detect single photons. In this paper, we report superior characteristics of the QUPID confirmed by the evaluation.