The CRAYFIS project is a novel approach to observing cosmic ray particles at the highest energies.

It uses the world-wide array of existing smartphones instead of building an expensive dedicated detector.

Cosmic Rays

When cosmic rays strike the atmosphere, they produce a huge number of lower-energy particles in an an extensive air shower, which can stretch to many kilometers across. The very high-energy cosmic rays produce the largest showers, but unfortunately they are also the rarest. Only a detector with large surface area can observe these mysterious particles.

The idea

The current state of the art is large-scale arrays of custom-designed dedicated detectors. To see the highest-energy cosmic rays, we need a very large detector array of exisiting commodity hardware: the smartphones in everyone's pockets

Your phone is a detector

Modern smartphones contain high-resolution cameras with digital sensors which are sensitive to the particles in a cosmic ray shower. They know where they are (GPS) and can upload their data (wi-fi). Most importantly, there are 1.5 billion active smartphones spread across the planet. Essentially, this detector has already been deployed; all that is missing is the app to collect the data

The app

The CRAYFIS app operates in a manner similar to a screensaver. When the phone is connected to a power source and the screen goes to sleep, the app begins data-taking. No active participation is required on the part of the user after the initial download and installation.

The science

Read the paper.

Observing cosmic rays at higher energies and higher rates than ever before will let us:

Be an astrophysicist

In addition to learning about astrophysics, you get to actually be an astrophysicist, by joining our collaboration and expanding our detector. Anyone whose phone collects enough data has the option to be made an author of at least one scientific paper.