Silicon Photomultiplier

Definition: The silicon photomultiplier (SiPM) is a type of sensor/detector with compactness, wide dynamic range, fast timing, and high gain factors. SiPMs are solid-state photodetectors made of an array of hundreds or thousands of integrated single-photon avalanche diodes (SPADs), called microcells or pixels whose outputs are merged into one, and therefore result in high sensitivity, wide dynamic range, and gain factors of 105 to 106, while allowing small construction sizes to even 1.1 x 1.1 mm2 frame sizes. Upon detecting a photon, the SPAD generates a large electrical output signal due to internal avalanche multiplication. The SiPM allows one to detect and count photons with high resolution and single photon sensitivity. The internal avalanche amplification is also fast enough to obtain excellent timing information on the arrival time of the detected photons within several tens of picoseconds. However, the supply voltage depends on the APD technology used. It typically varies between 20 V and 100 V, thus being from 15 to 75 times lower than the voltage required for a photomultiplier tube’s (PMT) operation but also 5 to 20 times higher than for a SiPD. These high voltages require additional safety measures for applications on the human head. Furthermore, like APDs, SiPMs have a high temperature sensitivity and increased noise components. However, SiPMS have a smaller dynamic range and saturation occurs at lower light levels when compared to APDs

Alternative definition:

Synonym: solid-state photomultiplier (SSPM), or multi-pixel photon counter (MPPC)


Related terms: avalanche photodiode, APD, silicone photodiode, SiPD, detector, sensor, single photon avalanche diodes, SPAD, PMT, photomultiplier tube  

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