Recent Advances in Large Area Avalanche Photodiodes

We have demonstrated the potential of large area avalanche photodiodes to complement photomultiplier tubes and conventional photodiodes in numerous applications. In particular, they are compatible with BGO scintillator crystals in important applications such as positron emission tomography and high energy physics research. The photodiodes described here have overcome the limitations in size and sensitivity which had previously prevented the use of avalanche devices in these applications. As scintillation sensors in radiation detectors, one inch diameter avalanche photodiodes have been used to obtain Cs-137, 662 keV spectra with 8.5% FWHM resolution coupled to NaI at room temperature and 24% FWHM coupled to BGO at 0°C. As low energy x-ray sensors, small devices have a 10% FWHM for 5.9 keV Mn, k x-rays. The devices are also extremely sensitive to beta particles. These attributes make them useful for detecting ionizing radiation in a wide variety of applications.