Wednesday 16 April 2025
Scientists have made a fascinating discovery about silicon photomultipliers (SiPMs), devices used in telescopes and other instruments to detect light. For years, researchers have been studying the dark current of SiPMs, which is the current that flows through them when no light is present. They’ve found that this current can be unpredictable and fluctuate wildly, sometimes even jumping up or down by as much as 0.1 milliamperes.
At first glance, this might not seem like a big deal. After all, telescopes are designed to detect tiny changes in the universe, so a little bit of noise shouldn’t matter too much. But SiPMs are used in some pretty sensitive instruments, and these fluctuations could be causing problems for scientists trying to collect accurate data.
The researchers decided to investigate further, monitoring the dark current of 128 individual channels on two different SiPM modules over the course of several months. They found that about half of the channels exhibited unusual behavior, with their dark currents jumping up or down by large amounts at seemingly random intervals.
But here’s the really interesting part: when they looked closely at one of these channels, they noticed something strange. The channel was emitting a tiny amount of light – just enough to be detected by a special camera. This light wasn’t coming from anywhere else in the module; it was definitely coming from this one specific channel.
The scientists think that this might be related to defects in the silicon itself. They believe that some areas of the silicon could be more prone to producing random, high-voltage pulses – which would cause the dark current to fluctuate wildly. These pulses might also be responsible for the light emission they observed.
This discovery has important implications for scientists who use SiPMs in their research. If these fluctuations are causing problems with data accuracy, then researchers need to know about it so they can take steps to correct for it. The findings could also lead to new ways of designing and building more sensitive instruments.
For now, the researchers are continuing to study this phenomenon, trying to understand exactly how it works and what causes it. But one thing is clear: the strange behavior of SiPMs has opened up a whole new area of research, and scientists are excited to explore its possibilities.
Cite this article: “Mysterious Dark Current Shifts Uncovered in Gamma-Ray Detectors”, The Science Archive, 2025.
Silicon Photomultipliers, Dark Current, Noise, Telescopes, Instruments, Sensors, Fluctuations, Defects, Silicon, Light Emission
