Muon

Unstable elementary subatomic particle similar to electron but 207 times heavier.

Core Principles & Analysis

• Discovered in cosmic rays by Carl Anderson and Seth Neddermeyer in 1936.
• Decays with a mean lifetime of 2.2 microseconds; time dilation lets cosmic-ray muons reach sea level.
• Fermilab's Muon g−2 experiment measured its magnetic anomaly to 127 parts per billion in 2025.

Specifications & Metrics

• MASS: 105.66 MeV/c²
• SPIN: 1/2
• SYMBOL: μ⁻