How to make a gamma ray

Pion production and decay animation. A proton travelling to the speed of light strikes a slower-moving proton. The protons survive the collision, but their interaction creates an unstable particle — a pion — with only 14 percent of the proton's mass. In 10 millionths of a billionth of a second, the pion decays into a pair of gamma-ray photons.

Inverse Compton scattering animation. An electron travelling at close the speed of light has a head-on collision with a lower-energy photon (from microwave to ultraviolet). The photon picks up energy from the electron and becomes a gamma ray.

Pair production animation. A gamma ray grazes an atom and interacts with it. The reaction annihilates the gamma-ray photon and creates a matter/antimatter pair of an electron and a positron.

Electron bremsstrahlung animation. An electron traveling close to the speed of light is deflected by the electric field of an atomic nucleus. It emits gamma rays as its path bends.