Xradiation

X-radiation, or X-rays, is a form of electromagnetic radiation with wavelengths from about 0.01 to 10 nanometers, corresponding to photon energies roughly 0.1 to 100 keV. X-radiation is highly penetrating and ionizing, properties that enable diagnostic use and biological risk. It was discovered by Wilhelm Röntgen in 1895, when a fluorescent screen glowed despite the tube being shielded from visible light.

X-radiation is produced in X-ray tubes by accelerating high-energy electrons toward a metal target, usually tungsten, and in large facilities such as synchrotrons and X-ray free-electron lasers. The emitted spectrum spans soft to hard X-rays, depending on source conditions. Interaction with matter occurs mainly through the photoelectric effect at lower energies, Compton scattering at intermediate energies, and pair production at higher energies. Attenuation in matter follows an exponential law and increases with atomic number and density; shielding designers use materials like lead to reduce exposure.

Applications are broad: medical imaging (radiography and computed tomography), industrial nondestructive testing, crystallography and structural biology, materials analysis, security screening, and radiation therapy for cancer. Detection relies on detectors such as photographic film, scintillation detectors, and semiconductor devices, often with image-processing systems. Safety is a central concern because X-radiation can damage living tissue; exposure is minimized through shielding, distance, and controlled dosing in accord with the ALARA principle. Doses are expressed in grays for absorbed energy and sieverts for biological effect, and clinical or occupational use is regulated.