A group of people from CERN is using their spare time to build Cosmic Pi, a cosmic ray detector based on a Raspberry Pi. Their goal is to crowdsource the world’s largest cosmic ray telescope by getting the devices into the hands of people and organisations around the globe, collecting data that will help astrophysicists understand more about these rays, several of which have passed through your body in the time it has taken you to read this paragraph. A video the team made last year explains the idea nicely:

You can take a look at details of the team’s current Cosmic Pi prototype hardware and software, all available online. The cosmic-ray-detecting part consists of a scintillator, made of a material that absorbs energy from cosmic rays passing through it and then emits some of that energy in the form of photons; an optic fibre to trap these photons and carry them to the edges of the scintillator material; and a silicon photomultiplier at each end of the fibre to convert this light into an electrical signal that can be analysed by the computer. A blog post from the end of last year has more detail about the prototyping process and the current design.

http://cosmicpi.org/2015/11/02/from-a-hackathon-to-another-a-year-of-cosmicpi-evolution/

Because atmospheric conditions influence the flux of cosmic rays at the Earth’s surface, the team decided that it would be worthwhile including temperature, pressure and humidity sensors to monitor the weather. They also added a GPS module to allow devices to log their location (allowing altitude, another factor influencing flux, to be recorded too), and an accelerometer and magnetometer to provide additional information about the device’s orientation and position. Currently, an Arduino Due microcontroller reads the sensor data and passes them to the Raspberry Pi, which pre-processes and stores them; the Cosmic Pi team is prototyping a HAT to combine as many components as possible in a single PCB.

Cosmic Pi HAT prototype and Raspberry Pi, with banana for scale. Photo by James Devine.

You can sign up to get notified when Cosmic Pi launches, which the team hope will happen with a Kickstarter campaign later in 2016, and they also intend to publish the design under an open source licence. They’re aiming to keep the cost of the whole package under $500, or about £350. While this is likely to be a bit steep for some individuals, we’d love to see organisations and groups like hackspaces using devices like this to contribute to what could be an amazingly valuable citizen science project. Keep an eye on the Cosmic Pi blog for updates!