gammastraling

Gammastraling, also known as gamma radiation, is electromagnetic radiation of very high energy emitted by atomic nuclei during radioactive decay or nuclear reactions. Gamma photons have no electric charge, move at the speed of light, and typically carry energies from tens of keV to several MeV. Because gamma rays are highly penetrating, they can traverse most materials and several centimeters of lead may be needed for shielding; their interaction with matter occurs mainly through photoelectric absorption, Compton scattering, and, at higher energies, pair production.

Natural sources include decay chains such as uranium-238, thorium-232, and potassium-40, as well as radon progeny; artificial sources include medical isotopes (for example technetium-99m, cobalt-60), industrial radiography sources, and reactor-produced isotopes. Gamma rays are used in medical imaging and therapy, industrial nondestructive testing, and research.

Exposure to gamma radiation is ionizing and can damage DNA, increasing cancer risk with sufficient dose. Doses are measured in grays for absorbed energy and sieverts for the effective dose, which accounts for tissue sensitivity; protection relies on minimizing exposure, maximizing distance, and using shielding materials such as lead or concrete. Safety guidelines are governed by national and international radiation-protection bodies.

Detection and measurement employ gamma spectrometry, scintillation detectors, and dosimeters; imaging devices include gamma cameras and SPECT systems. In nuclear medicine, gamma tracers enable functional imaging, while radiotherapy uses targeted gamma emissions to destroy malignant tissue.

History: gamma radiation was discovered by Paul Villard in 1900, named by Ernest Rutherford in 1903, and subsequently characterized by researchers including Becquerel and the Curies.