Monitor cosmic rays with your phone

There’s now an app which allows one to monitor for cosmic rays via a phone’s camera sensor. When I first read the article I thought it was about gamma rays which are the highest-energy form of light in the electromagnetic spectrum. Cosmic rays are totally different and often come from highly cataclysmic events outside the solar system. In fact gamma rays are also produced in cataclysmic events (such as the well-known gamma ray bursts which are routinely observed in astronomy).

Cosmic rays are weirder. They are not electromagnetic energy but actual particles of matter that travel at extremely high velocities. Some rare cosmic ray detection events have occurred over the years including the famous “Oh My God” particle which had a mind-blowingly high level of energy.

Smartphone cameras use silicon chips that work through what is called the photoelectric effect, in which particles of light, or photons, hit a silicon surface and release an electric charge. The same is true for muons. When a muon strikes the semiconductor that underpins a smartphone camera, it liberates an electric charge and creates a signature in pixels that can be logged, stored and analyzed.

source: news.wisc.edu “Physicist turns smartphones into pocket cosmic ray detectors”