Handheld device democratizes study of cosmic particles from supernovae

University of Delaware physics professor Spencer Axani has developed CosmicWatch, a handheld, low-cost muon detector designed to democratize the study of high-energy cosmic particles produced by phenomena like supernovae and gamma-ray bursts. CosmicWatch detects muons—secondary particles created when cosmic rays collide with atoms in Earth’s atmosphere—and costs approximately $100 to build, making it accessible to both research institutions and high school students. The device, roughly the size of a small box, lights up and records data each time a muon passes through, enabling affordable and portable physics experiments that were previously limited to large, expensive equipment. Originally created as an educational tool during Axani’s graduate work at MIT, CosmicWatch has evolved into a valuable instrument for international astrophysics research and outreach. The latest third version, detailed in the Journal of Instrumentation, offers faster data collection, environmental monitoring, and radiation resistance. It is also being adapted for use aboard rockets and spacecraft to measure primary cosmic rays. With thousands of units