Performance of 1-${\hbox {mm}}^{2}$ Silicon Photomultiplier

A silicon photomultiplier (SPM) is a large area detector consisting of a parallel array of photon counting microcells. Each microcell consists of a Geiger Mode photodiode with an integrated quenching element. Each microcell is then connected to a common output. The microcells have a uniform gain of up to 10 and provide an identical charge output signal for each photon detected. Under illumination the summed output of the detector is proportional to the number of Geiger pulses and hence proportional to the incident photon flux. This combination gives extremely high performance comparable to that of a conventional photomultiplier tube (PMT). We report on the characterization of two different 1 mm
²
SPM detector designs with 620 and 920 microcells at room temperature (20 deg) and down to . We assess detection efficiency, breakdown voltage, gain, dark rate, crosstalk, timing jitter and dynamic range. The SPM detector operates over the visible region of the spectrum, characterized here from 400 to 800 nm. The peak photon detection efficiency of 15% occurs at 500 nm with a cooled () dark rate of 600 at a bias voltage of 31 V. In a test for positron emission tomography (PET), an energy resolution of 25% was recorded for the detection of 511 keV gamma radiation using 1 mm1 mm15 mm LYSO scintillator crystal. The SPM has many applications such as medical imaging, microscopy, high-energy physics, and homeland security.