Extensive air shower tracker using Cherenkov detection

Abstract

Cosmic rays continuously bombard Earth’s atmosphere triggering cascades of secondary particles. Many constituents progress to reach the surface and capturing these events can intrigue and awe young curious minds, opening them to the amazing world of physics. Cloud chambers are an established method of revealing the subatomic world; frequently used by universities to introduce cosmic rays to visitors and prospective students, they provide a fascinating real-time display of the ‘ghostly’ particles showering upon those viewing. Using the Cherenkov radiation detection technique, we have developed a novel, compact, Extensive Air Shower (EAS) particle tracking method that enhances the cloud chamber visualisation of cosmic ray interactions towards a digital audience. Once digital, live event interaction can be streamed to multiple display devices presenting an immediate illustration of the event that showered in that location. Our instrument hardware is built around Cherenkov-optimised silicon photomultiplier sensors. Each single detection unit monitors particle event rate and tracks incident angle by measuring Cherenkov intensity. By operating multiple detection units in one location, we can record time correlated air shower events to monitor and collate information on the primary cosmic rays. We introduce first results, illustrating instrument response and EAS rate variations, compiled from the initial running period of our development instruments. We present intensity spectra, compare with simulation, and describe the instrument response due to sensor location, Cherenkov intensity, mean muon energy and detector acceptance angle. With further development towards low-cost readout electronics, we aim to build a networked array of trackers, located around the campus, to expand data gathering ability and scientific potential.