xray

X-ray refers to a form of electromagnetic radiation with wavelengths from about 0.01 to 10 nanometers, placing it between ultraviolet light and gamma rays. X-rays carry enough energy to ionize atoms and can penetrate many materials, with absorption depending on density and atomic number. They were discovered in 1895 by Wilhelm Conrad Röntgen, who observed a glow from a phosphor screen near a cathode ray tube and named the radiation for its unknown nature.

X-rays are produced primarily in X-ray tubes by accelerating electrons and colliding them with a metal target, usually tungsten. The resulting spectrum consists of a broad Bremsstrahlung continuum and, for certain target materials, characteristic lines. When X-rays pass through matter, they interact mainly through photoelectric absorption and Compton scattering, with Rayleigh scattering contributing to small-angle deflections. The degree of attenuation increases with material thickness, density, and atomic number.

Applications are extensive. In medicine, X-rays are used for radiography and computed tomography to image bones and soft tissues. In industry, they enable nondestructive testing of components. In science, X-ray crystallography determines molecular structures, and X-ray diffraction studies contribute to materials science and chemistry. In astronomy, X-ray telescopes observe high-energy phenomena such as black holes and hot interstellar gas.

Safety and regulation emphasize that X-rays are ionizing radiation and pose health risks with sufficient exposure. Protective shielding (often lead), exposure minimization, and monitoring are standard practices, governed by occupational and medical guidelines to keep doses as low as reasonably achievable.