Development of a multi-pixel hybrid photodetector with high quantum efficiency and gain

A hybrid photo-detector (HPD) consisting of a photocathode and a multi-pixel avalanche diode (MP-AD) has been developed for these years. One of the features of the HPD is a good energy resolution, and it was shown in our previous study that the further improvement would be possible by reducing the fluctuation of charge loss in the dead layer at the entrance of the MP-AD. In this paper, we report on the result of the improvement with the newly developed HPD whose MP-AD encapsulated has a thinner dead layer than before. It is demonstrated that the new HPD has a much better energy resolution which enables the clear counting up to nine photoelectrons. Other features like a uniformity among the pixels or a photocathode sensitivity of the HPD are also presented.