Pair Production

Interactive simulation of gamma-ray pair production: a high-energy photon near a nucleus transforms into an electron-positron pair, demonstrating E = mc². Adjustable photon energy slider (0.2–10 MeV) with real-time physics calculations and visual animation. Threshold check: pair production requires minimum 1.022 MeV (2 × 0.511 MeV electron rest mass). Energy budget bar shows decomposition into electron rest energy, positron rest energy, and kinetic energy shared equally between pair. Real-time readouts: photon frequency (Hz) and wavelength (pm), total kinetic energy, Lorentz factor γ, and particle speed (%c). Canvas animation shows incoming gamma ray, nucleus recoil, pair creation flash, and diverging electron and positron tracks. Optional magnetic field (into page) toggle shows curved tracks curving in opposite senses due to opposite charges, with spiral inward due to ionisation energy loss. Auto-repeat toggle. Playback speed control (0.25×–2×). Educational theory section covers mass-energy equivalence, why nucleus is needed for momentum conservation, charge conservation, magnetic field behaviour, and connection to historical bubble-chamber positron discovery (Anderson 1932) and modern PET imaging.