Gamma rays are like x-rays, but the waves are smaller in wavelength. Both gamma rays and x-rays are photons with very high energies, and gamma have even more energy. They are also a type of ionizing radiation. Gamma rays can travel through thicker materials than x-rays can.
Gamma rays are produced by some types of radioactive atoms. Cobalt-60 and potassium-40 are two isotopes that emit gamma rays. Cobalt-60 is created in accelerators and is used in hospitals. Potassium-40 occurs naturally. Small amounts of potassium-40 are in all plants and animals. Gamma rays from potassium-40 each have an energy of 1460 thousand electron volts (keV).
Gamma rays in medicine
Gamma rays can also go through the skin to kill cells, such as cancerous cells. Doctors can use radiation therapy machines which produce gamma rays in hospitals to treat people with some types of cancer.
Doctors also use gamma rays to find disease. In hospitals, doctors can give patients radioactive medicine which emits gamma rays. Doctors can find some types of disease by measuring gamma rays which come from a patient afterward. Hospitals can also use gamma rays to sterilise (clean) things as disinfectants do.
Images for kids
The Moon as seen by the Compton Gamma Ray Observatory, in gamma rays of greater than 20 MeV. These are produced by cosmic ray bombardment of its surface. The Sun, which has no similar surface of high atomic number to act as target for cosmic rays, cannot usually be seen at all at these energies, which are too high to emerge from primary nuclear reactions, such as solar nuclear fusion (though occasionally the Sun produces gamma rays by cyclotron-type mechanisms, during solar flares). Gamma rays have higher energy than X-rays.
A hypernova. Artist's illustration showing the life of a massive star as nuclear fusion converts lighter elements into heavier ones. When fusion no longer generates enough pressure to counteract gravity, the star rapidly collapses to form a black hole. Theoretically, energy may be released during the collapse along the axis of rotation to form a long duration gamma-ray burst.
Gamma ray Facts for Kids. Kiddle Encyclopedia.