Basic properties of ionizing radiations

Abstract

X-rays and gamma-rays are forms of electromagnetic radiation having wavelengths roughly in the range 10^2212;9–10⁻¹³ m. X-rays are produced by allowing a stream of high-energy electrons to strike a metal target, and they originate in the extra-nuclear structure of the target atoms. Gamma-rays are emitted from the nucleus of radioactive elements. Both X- and gamma-rays travel at the speed of light (c = 3 × 10⁸ m s⁻¹). They travel in straight lines and are invisible. The essential difference between light, ultra-violet, infra-red, radio-waves and X-rays is one of wavelength and frequency. X-rays and gamma-rays have the property of being able to penetrate matter which is opaque to light and they have a photographic action very similar to that of light. They pass through material of low density more readily than through high density material, and their penetrating ability depends on their wavelength.