Calling all Cosmic Ray Detectors

by | Nov 14, 2014 | Citizen Science | 0 comments

Are you the proud owner of an Android OS phone? If so, it turns out that you’ve got much more than a simple instagram and social media machine in your pocket—you have the makings of a cosmic ray detector.

DECO, or the “Distributed Electronic Cosmic-ray Observatory,” is a citizen science project and mobile app designed to turn your ordinary smartphone into a cosmic ray detector. The project intends to record secondary particles, called muons, that occur when cosmic rays hit the Earth’s atmosphere.

Using just the camera on your mobile device, DECO takes a “sample,” or an image, of particles bouncing off the camera every 1-2 seconds. The app then analyzes these images, determining which pixels are fairly bright in the image. If enough pixels are bright, it is considered a candidate for a high-energy particle interaction.

The Wisconsin IceCube Particle Astrophysics Center’s researchers admit that cosmic ray particles can be confusing to physicists. Their paths are changed and manipulated by magnetic fields, creating difficulties for scientists searching for other events. This is where they hope that a study using smartphones will prove helpful.

“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,” said the University of Wisconsin-Madison in a press release. “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.”

The app is simple to use—you simply cover your camera lens and leave your phone face-up, running idle. For best results, you’ll want to tape over your lens and place your device camera down, to minimize background light. The app will image periodically, and record its results in a central database.

Many events the app records are due to cosmic-ray muons, but DECO can also detect electrons, gamma rays, and alpha particles—some of which are produced by the simple materials in your phone. Just a tiny number of the samples turn out to be candidates, and only a fraction of these are classified as “events.”

According to the DECO page, for a typical device, you need to run the app for around 24 hours to get a few events. If you’ve only dreamed about doing citizen science in the past, now is your chance—just plug your phone in and set it on your nightstand before bed, and the app will collect data while you’re asleep!

Currently, DECO is only available for Android OS devices, but the DECO team hopes to roll out an iOS version some time in 2015.


For more information on DECO and how to get started, visit their webpage. Happy ray detecting!


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