gammafoton

A gamma photon is the quantum of gamma radiation, an electromagnetic wave with very high energy. Like all photons, it has zero rest mass and travels at the speed of light. Gamma photons are typically defined as photons with energies above about 100 keV, though the exact boundary with X-rays is not fixed. Their energies span from tens of keV to well beyond GeV in some astrophysical and laboratory sources.

Gamma photons are produced in a variety of processes. In atomic nuclei, excited states can decay by emitting a gamma photon, a mechanism known as gamma decay. Positron annihilation yields pairs of 511 keV photons traveling in opposite directions. In high-energy particle interactions, neutral pion decay and other processes generate gamma rays. Astrophysical sources include gamma-ray bursts, active galactic nuclei, pulsars, and supernova remnants, while laboratories produce gamma rays with nuclear reactors and particle accelerators.

Interactions with matter vary with energy. At gamma-ray energies, the dominant processes are Compton scattering, photoelectric absorption at lower energies, and pair production in the vicinity of nuclei at higher energies. These interactions inform shielding design, detector choice, and interpretation of spectra. Common detectors include scintillation counters and high-purity germanium detectors for spectroscopy, as well as specialized telescopes and Cherenkov detectors for high-energy gamma rays.

Applications span medicine, industry, and science. In medicine, gamma rays are used for imaging (gamma cameras) and radiotherapy. Industrial uses include non-destructive testing and sterilization. In science, gamma-ray astronomy probes extreme environments and fundamental processes. The term gamma photon is used interchangeably with gamma ray photon, reflecting its nature as a single quantum of high-energy electromagnetic radiation.