Researchers are using phone cameras to study and analyse rare cosmic rays

Smartphone cameras are now helping Russian researchers analyse rare ultra-high energy cosmic rays (UHECR). According to a team from the Laboratory of Methods for **Big Data** Analysis (LAMBDA) at the National Research University Higher School of Economics, mobile phone cameras use technology similar to that in particle detectors. [caption id=“attachment_3991129” align=“alignleft” width=“380”] Camera sensor on smartphone[/caption] The UHECR emanate from supernovae and black holes and, upon interacting with air particles, form cascades of secondary particles with lower energy. These are known as “Extended Atmospheric Showers” (EAS). Mobile phone cameras use technology similar to that in particle detectors and hence they are able to detect EAS, the team noted. The particles interact with the CMOS camera and leave traces of weakly activated pixels, which can be difficult to distinguish from interference and random noise. As part of the experiment, volunteers were asked to install the application on their smartphones and leave the phone, with the camera facing down, overnight, so that normal light doesn’t fall on it. The smartphone scanned megapixel images at a speed of 5-15 frames per second and sent the necessary information to the server. Scientists expect signals from the interaction of cosmic rays to occur in less than 1 of the 500 image frames. Owing to the fact that millions of phones will potentially participate in the experiment, a problem arises in separating those images on which “muon” tracks are recorded, from all the others. “A trigger algorithm is required to eliminate background data. We created a neural network for the detection of ‘muon’ signals, which can be used on any mobile phone fast enough to process a video stream,” said Andrei Ustyuzhanin, head of LAMBDA at HSE. “A special feature makes it possible to use the algorithm on something as simple as a mobile phone, meaning that they can now analyze responses to cosmic rays,” Ustyuzhanin added. Researchers hope that, if the project is successful, the information obtained will enable astrophysicists around the world to clarify where ultra-high energy cosmic rays come from, and to develop theories around their properties.