Development of 2cm-square Hamamatsu avalanche photodiodes for high-resolution X-rays and -rays detection

Abstract: The avalanche photodiodes (APDs) have attracted considerable attention in various field of experimental physics, but their uses are still limited in only a few experiments, possibly due to their small surface areas. Here, we report the development of the large-area ( square) APDs, for future applications to high-resolution X-rays and -rays detection. We have made two prototypes of reverse-type APDs based on different concepts, one consists of a array of pixels (APD1) and the other is a monolithic pixel of size (APD2) to achieve a large effective area. By comparing the dark current and gain characteristics at room temperature and lightly cooled environment (), we quantitatively discussed the origin of predominant noise source at different temperatures. As a performance demonstration of newly developed APDs, we made a scintillation -ray detector consisting of a CsI(Tl) crystal and a 2cm-square APD. The best FWHM energy resolution of 5.5 were obtained for -rays at room temperature. Similarly, the best FWHM energy resolution of were obtained for 122keV -rays at lightly cooled environment. We showed that the minimum detectable energy for scintillation light was 15keV at and less than 5keV at . [Copyright &y& Elsevier]