Space

Turn Your Phone Into A Cosmic Ray Detector

October 14, 2014 | by Janet Fang

Photo credit: Air showers from very high energy cosmic rays / Simon Swordy (U. Chicago), NASA

Did you know that your phone is capable of detecting high-energy particles from the farthest regions of space? Oh yeah. And now, physicists studying the origin of exotic space particles have developed a new app called CRAYFIS that could turn our global network of smartphones into the world’s largest telescope. 

Cosmic rays are ultra-high-energy particles from space that rain down on Earth. When they crash into our atmosphere, the particles break up and fall on us as even smaller particles: electrons, photons, and muons. Even though they were discovered decades ago, cosmic rays are rare and we still don’t know their source. And since they arrive so infrequently, a very large detector -- say, a global network of phones -- is needed to pinpoint where in the universe they originate.

“Whole square kilometers can be drenched in these particles for a few milliseconds,” says Daniel Whiteson from University of California at Irvine in a news release. “The mystery is nobody knows where these crazy, high-energy particles are coming from or what’s making them so energetic. But they can be captured by technology in smartphones’ cameras.”

The silicon-based, digital sensors in our camera phones aren’t all that different in principle from the particle detectors at CERN. The sensors we carry in our pockets and bags can all detect visible light, Gizmodo explains, turning it into an image on the screen for us to see, and as it turns out, they’re also sensitive to the particles in a cosmic ray shower. 

Whiteson’s team conducted tests with radioactive isotopes of radium, cobalt, and cesium, and found that smartphone cameras can easily pick up gamma rays -- even when they’re not pointed at the source, Ars Technica reports. Their paper was posted on arXiv last week. 

There are already 1.5 billion active smartphones pre-positioned around the world. Just 1,000 active phones within a square kilometer could detect nearly all of the high energy cosmic rays striking the atmosphere above it, Ars Technica explains, despite the low efficiency of each.

Called CRAYFIS for Cosmic Rays Found in Smartphones, the app records when and where the GPS-equipped camera on your phone senses high-energy particles and their levels. The app works like a screensaver reminiscent of SETI@home. So as not to interfere with normal phone usage or drain the battery, the app collects data when your Android or iOS device is connected to a power source and hasn’t been used for several minutes. That means that after you install the app, you don’t really need to actively participate much. Data will be sent to the researchers over wi-fi, and if your phone helped gather data that are ultimately used in a scientific paper, you could be a study author. Or if you prefer, the app can also run in anonymous mode.

Image: Simon Swordy (U. Chicago), NASA

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