View source for Compton's phenomenon - what it proves, the benefit

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[[File:Compton scattering 600x225 cs.png|preview|400x175px|Scheme of the Compton effect]]
== Compton effect ==
The Compton effect ([[Compton scattering]] or also incoherent scattering) is the interaction of a photon '''[[Gamma radiation|γ radiation]]''' with a '''free''' or '''weakly bound [[electron] ]em''', during which part of the [[photon]]'s energy is transferred to the electron. During this interaction, the electron acquires [[wikipedia:en:Kinetic energy|kinetic energy]] and starts to move in a direction deviated from the original direction of the path of the primary photon by the angle '''φ'''. The scattered photon (secondary photon) with lower energy (ie with a larger [[Wavelength|wavelength]]) is deflected by the angle '''ψ'''. The event can be repeated several times until the photon loses so much energy that the probability of its extinction [[Photoelectric effect|photoelectric effect]] prevails.

It mostly does not depend on the proton number of the material of the substance. It depends on the electron density (the number of electrons per cm<sup>3</sup>).

Compton scattering is the predominant interaction at energies from 0.1 to 10 MeV.

=== What the Compton Effect Proves ===
The Compton phenomenon, or [[Compton scattering]], cannot be explained on the basis of the wave properties of radiation (from this point of view, the [[wavelength]] of the scattered radiation should be the same as the original one). It is therefore one of the phenomena proving the existence of '''[[photon]]u''''. The experiment proving the Compton effect also confirmed that photons can behave both as [[Wave-corpuscular dualism|'''particles''' and as '''waves'''.]]

=== History and contribution ===
Compton scattering was discovered in '''1922''' by [[wikipedia:en:Arthur Holly Compton|Arthur Holly Compton]] (1892-1962) while conducting research on the scattering of [[X-rays|X-rays]] by particles [[Visible light |lights]]. In 1922, he published his experimental and theoretical results, and in '''1927''' he received the [[wikipedia:cs:Nobel Prize|Nobel Prize]] for this discovery. His theoretical explanation of the phenomenon now known as [[Compton scattering]] differs from classical theories and requires the use of [[wikipedia:en:Special relativity|special relativity]] and [[wikipedia:en:Quantum mechanics| quantum mechanics]], which were barely comprehensible in his time. At first his results were considered very controversial, but later his work was recognized and had a strong influence on the development of [[wikipedia:en:Quantum physics|quantum theory]].

=== Using the Compton effect ===
[[File:Radiation therapy.jpg|preview|550x250px|Radiation therapy]]
* '''Use in radiotherapy'''
:Compton scattering is used in '''[[Radiotherapy|radiotherapy]]''' (irradiation), where living matter interacts with high-energy radiation ([[gamma radiation]], [[RTG]]). When photons affect tissues, energy is lost in one of three ways: [[photoelectric effect|photoelectric effect]], [[Compton effect|Compton scattering]] or the formation of [[electron-positron pairs|electron-positron pairs]]. In clinical radiotherapy, the most common and therefore the most important of these mechanisms is Compton scattering, in which photons interact with [[wikipedia:en:Valence electron|valence electrons]] of tissue atoms. During such an interaction, not only photons are scattered, but at the same time (thanks to the supplied energy) an electron is torn from the valence layer, i.e. [[Ionization|ionization]].
:The biological effects of radiotherapy consist in the targeted damage of [[DNA (nucleic acid)|DNA]] e.g. formed [[wikipedia:cs:Radical|free radicals]] (primarily hydroxyl radicals formed by ionization of molecules [[Physical and chemical properties of water|water]]).

* [[File:Compt. jev.jpg|thumb|Compton scattering]]'''Use in Spectroscopy'''
:The Compton effect is used in the detection of [[Ionizing radiation|ionizing radiation]]. It is used in [[wikipedia:en:Scintillation detector|scintillation detectors]] to detect [[Gamma radiation|gamma radiation]].

* '''Usage in Astronomy'''
:Compton scattering is also used in '''[[wikipedia:cs:Astronomy|astronomy]]'''. An example is the Compton Gamma Ray Observatory(Compton Gamma Ray Observatory, abbreviated Compton GRO or CGRO), this observatory took pictures of the most energetic processes in the universe, such as solar flare, gamma ray burst, pulsary, nova and supernova explosions, black holes etc. CGRO was equipped with a set of sensors, one of which was the ''Compton Imaging Telescope'' (Imaging Compton Telescope, COMPTEL), which used Compton scattering to study and analyze gamma rays in the energy range of 1 to 30,000,000 eV. This device made it possible to determine with great accuracy the direction and energy of the original gamma photon, as well as the reconstruction of the image and energy spectrum of the source of the given radiation.
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== Links ==
=== Related Articles ===
* [[Compton phenomenon - what is it]]
* [[Compton scattering]]
* [[Photoelectric effect]]
* [[Wave-corpuscular dualism]]

=== External links ===
* [[wikipedia:en:Compton Gamma Observatory|Compton Gamma Observatory]]
* [https://heasarc.gsfc.nasa.gov/docs/cgro/cossc/ Compton Gamma Ray Observatory Science Support Center]
* [http://www.thymic.org/uploads/reference_sub/02radtherapy.pdf Principles of radiation therapy]
* [http://www.phys.utk.edu/labs/modphys/Compton%20Scattering%20Experiment.pdf The Compton Effect - Compton Scattering and Gamma Ray Spectroscopy]
* [https://is.muni.cz/th/78026/prif_m/IV.3.pdf Compton's effect (muni)]
=== References ===
* Navrátil, Leoš; Rosina, Jozef and the team: Medical Biophysics, 1st edition, Prague, Grada, 2005 ISBN 978-80-247-1152-2<br />
* Amler E, Blažek T, Heřmanská J, Koláčná L, Kotyk A, Vackářová J, Varga F. Practical problems in biophysics I. Department of Biophysics UK, 2nd Faculty of Medicine, Prague, 2006<br />
* Jeffrey A. Norton: Surgery: Basic Science and Clinical Evidence

[[Category:Significantly Changed Reviewed Articles]]
[[Category:Biophysics]]
[[Category:Nuclear Medicine]]
[[Category:Radiodiagnostics]]