Scientists Michael Mulhearn at UC Davis and Daniel Whiteson of UC Irvine have led an effort to develop a new smartphone app than may provide insight into cosmic rays, UCI News reports. The app uses the silicon-based sensors within smartphones as an array to detect cosmic ray activity over an unprecedented area. In a paper submitted earlier to arXiv, these scientists propose that with 1 million users, the app may rival the power of current state-of-the-art observatories.

Little is known about the source of ultra high-energy cosmic rays, with energy above 10¹⁸ electron volts. At such high energies, these particles are minimally impacted by the magnetic fields they traverse traveling from their source to the Earth. In studying their dispersal, scientists hope to finally understand where these particles are coming from, and what type of mechanism accelerates them to such high energy.

As ultra high-energy cosmic rays collide with the Earth’s atmosphere, they produce air showers of particles including muons, photons and electrons. These ‘showers’ have been detected in the past via the particle flux on the ground, the fluorescence in the air, or in radio and acoustic signatures.

“Whole square kilometers can be drenched in these particles for a few milliseconds,” said Whiteson, associate professor of physics & astronomy at UCI. “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.”

Having a detector covering a large area is crucial in collecting information on a particle shower caused by cosmic rays.

The developed app, called CRAYFIS (Cosmic RAYs Found In Smartphones), can independently detect ionizing radiation from photons or muons. A million smartphones working in unison can reconstruct the source particle initiating the ‘shower’, helping scientists pinpoint the energy and direction of the original high-energy particle.

The app only works when the phone is charging and will not disclose any of the user’s photos. As an incentive to participate in the study, the collaborators are offering authorship to anyone whose smartphone contributes analyzable data, Tech Times reports.