Build Your Own Muon Detector for Under $100

Inspired by Nobel laureate Luis Alvarez's muon-based pyramid exploration, the author built a muon detector for around $100. Using two Geiger counters and an Arduino Nano, the device cleverly distinguishes cosmic-ray muons from lower-energy particles through a coincidence method. Experiments verified its ability to detect muon flux variations with angle and successfully measured rock thickness changes deep within a gold mine, even sensing a vertical shaft. This demonstrates the feasibility of exploring Earth's inner structure with simple equipment.