Characteristics of Gamma Rays / Radiation

Key features of gamma rays are summarized in the following few points:

  • Gamma rays are high-energy photons (about 10 000 times as much energy as the visible photons),
  • The same photons as the photons forming the visible range of the electromagnetic spectrum – light.
  • Photons (gamma rays and X-rays) can ionize atoms directly (despite they are electrically neutral) through the Photoelectric effect and the Compton effect, but secondary (indirect) ionization is much more significant.
  • Gamma rays ionize matter primarily via indirect ionization.
  • Although many possible interactions are known, there are three key interaction mechanisms with the matter.
  • Gamma rays travel at the speed of light, and they can travel thousands of meters in the air before spending their energy.
  • Since gamma radiation is very penetrating, it must be shielded by very dense materials, such as lead or uranium.
  • The distinction between X-rays and gamma rays is not so simple and has changed in recent decades.  According to the currently valid definition, X-rays are emitted by electrons outside the nucleus, while the nucleus emits gamma rays.
  • Gamma rays frequently accompany the emission of alpha and beta radiation.

 

Comparison of particles in a cloud chamber. Source: wikipedia.org
Comparison of particles in a cloud chamber. Source: wikipedia.org

 

Attenuation coefficients.
Total photon cross-sections.
Source: Wikimedia Commons
Image: The relative importance of various processes of gamma radiation interactions with matter.
Gamma rays attuenuation
The relative importance of various processes of gamma radiation interaction with matter.
Basic Principles of Shielding of Gamma Rays
radiation protection pronciples - time, distance, shielding
Principles of Radiation Protection – Time, Distance, Shielding

See also: Shielding of Gamma Rays

See previous:

Discovery of Gamma Rays

See above:

Gamma Ray

See next:

Photoelectric Effect