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WHAT DO WE KNOW ABOUT GAMMA RADIATION?

Gamma rays are a form of electromagnetic radiation (EMR), similar to X-rays, that are emitted from the excited nucleus of an atom. 

All EMR takes the form of a stream of photons, massless particles each travelling in a wave-like pattern and moving at the speed of light. 

Each photon contains a certain amount - a package or bundle - of energy, and all EMR consists of these photons. 

Gamma-ray photons have the highest energy in the EMR spectrum and their waves have the shortest wavelength.

Scientists measure the energy of photons in electron volts (ev). X-ray photons have energies in the range 100 ev to 100,000 ev (or 100 kev). Gamma-ray photons generally have energies greater than 100 kev. 

For comparison, the ultraviolet radiation that causes your skin to tan or burn has energy that falls in the range from a few electron volts to about 100 eV.

The high energy of gamma rays mean they can pass through many kinds of materials, including human tissue. 

Very dense materials, such as lead, are commonly used as shielding to slow or stop gamma rays.

Gamma radiation is released from many of the radioisotopes found in the natural radiation decay series of uranium, thorium and actinium.

It also emitted by the naturally occurring radioisotopes potassium-40 and carbon-14. 

These are found in all rocks and soil and even in our food and water.

Artificial sources of gamma radiation are produced in fission in nuclear reactors, high energy physics experiments, nuclear explosions and accidents.

Huge bursts of gamma rays have been detected out in the universe and are though to come from black holes that form when stars explode or when two neutron stars collide.

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