Radiation: 1. Rays of energy. Gamma rays and X-rays are two of the types of energy waves often used in medicine. 2. The use of energy waves to diagnose or. Radiation consists of very small particles of a radioactive substance. If the cancer returns, radiation therapy is successful in 90 per cent of cases. energy emitted as electromagnetic waves, as gamma or X-rays, or as energetic nuclear particles, as neutrons, alpha and beta. Definition of radiation: Direct transmission of heat or electromagnetic energy through space or another medium. It is the 'non-ionizing' type of radiation that does.


Author: Albin Emmerich II
Country: Monaco
Language: English
Genre: Education
Published: 25 July 2016
Pages: 233
PDF File Size: 45.64 Mb
ePub File Size: 12.86 Mb
ISBN: 192-7-24052-474-5
Downloads: 9617
Price: Free
Uploader: Albin Emmerich II


When a positron slows to speeds similar to those of electrons in the material, the positron will annihilate an electron, releasing two gamma photons of keV radiation definition the process.

Those two gamma photons will be traveling in approximately opposite direction. The gamma radiation from positron annihilation radiation definition of high energy photons, and is also ionizing.

Neutron radiation Main articles: Neutron radiation consists of free neutrons. These neutrons may be emitted during either spontaneous or induced nuclear fission. Neutrons are rare radiation particles; they are produced in large numbers only where chain reaction fission or fusion reactions are radiation definition this happens for about 10 microseconds in a thermonuclear explosion, or continuously inside an operating nuclear reactor; production of the neutrons stops almost immediately in the reactor when it goes non-critical.

Neutrons are the only type of ionizing radiation that can make other objects, or material, radioactive. This process, called neutron activationis the primary method used to produce radioactive sources for use in medical, academic, and industrial applications.

Even comparatively low speed thermal neutrons cause neutron radiation definition in fact, they cause it more efficiently. Neutrons do not ionize atoms in the same way that charged particles such as protons and electrons do by the excitation of an electronbecause neutrons have no charge.

It is through their absorption by nuclei which then become unstable that they cause radiation definition.


Hence, neutrons are said to be "indirectly ionizing. Not all materials are capable of neutron activation; in water, for example, the most common isotopes of both types atoms present hydrogen radiation definition oxygen capture neutrons radiation definition become heavier but remain stable forms of those atoms.

Only the absorption of more than one neutron, a statistically rare occurrence, can activate a hydrogen atom, while oxygen requires two additional absorptions.

Thus water is only very weakly capable of activation. The sodium in salt radiation definition in sea wateron the other hand, need only absorb a single neutron to become Na, a very intense source of beta decay, with half-life of 15 hours.

In addition, high-energy high-speed neutrons have the ability to directly ionize radiation definition.

What is radiation? definition and meaning -

One mechanism by which high energy neutrons ionize atoms is to strike the nucleus of an atom and knock the atom out of a molecule, leaving one or more electrons behind as the chemical bond is broken. This leads to production of radiation definition free radicals. In addition, very high energy neutrons can cause ionizing radiation by "neutron spallation" or knockout, wherein neutrons cause emission of high-energy protons from atomic nuclei especially hydrogen nuclei on impact.

The last process imparts most of the neutron's energy to the proton, much like one billiard ball striking another. The charged protons and other products from such reactions are directly ionizing. High-energy neutrons are very penetrating and can travel great distances in air hundreds or even thousands of meters and moderate distances several radiation definition in common solids.

They typically require hydrogen rich shielding, such as concrete or water, to block them within distances of less than a meter.

A common source radiation definition neutron radiation occurs inside a nuclear reactorwhere a meters-thick water layer is used as effective shielding. Cosmic radiation Main article: Cosmic rays There are two sources of high energy particles entering the Earth's atmosphere from outer space: The sun continuously emits particles, primarily free protons, in the solar wind, and occasionally augments the flow hugely with coronal mass ejections CME.

  • Radiation - Wikipedia
  • Radiation - Wikipedia
  • Radiation | Definition of Radiation by Merriam-Webster

The particles from radiation definition space inter- and extra-galactic are much less frequent, but of much higher energies. It is sometimes used therapeutically in radiotherapy to treat superficial tumors.

What is Radiation? - Definition, Causes & Effects

When a positron slows to radiation definition similar to those of electrons in the material, radiation definition positron will annihilate an electron, releasing two gamma photons of keV in the process. Those two gamma photons will be traveling in approximately opposite direction. The gamma radiation from positron annihilation consists of high energy photons, and is also ionizing.