Gamma Ray

Gamma Ray

Gamma radiation, also known as gamma rays or hyphenated as gamma-rays and denoted as γ, is electromagnetic radiation of high frequency and therefore high energy. Gamma rays are ionizing radiation and are thus biologically hazardous. They are classically produced by the decay from high energy states of atomic nuclei (gamma decay), but are also created by other processes. Paul Villard, a French chemist and physicist, discovered gamma radiation in 1900, while studying radiation emitted from radium during its gamma decay. Villard's radiation was named "gamma rays" by Ernest Rutherford in 1903.

Natural sources of gamma rays on Earth include gamma decay from naturally occurring radioisotopes, and secondary radiation from atmospheric interactions with cosmic ray particles. Rare terrestrial natural sources produce gamma rays that are not of a nuclear origin, such as lightning strikes and terrestrial gamma-ray flashes. Gamma rays are produced by a number of astronomical processes in which very high-energy electrons are produced, that in turn cause secondary gamma rays by the mechanisms of bremsstrahlung, inverse Compton scattering and synchrotron radiation. A large fraction of such astronomical gamma rays are screened by Earth's atmosphere and must be detected by spacecraft.

Gamma rays typically have frequencies above 10 exahertz (or >1019 Hz), and therefore have energies above 100 keV and wavelengths less than 10 picometers (less than the diameter of an atom). However, this is not a hard and fast definition, but rather only a rule-of-thumb description for natural processes. Gamma rays from radioactive decay are defined as gamma rays no matter what their energy, so that there is no lower limit to gamma energy derived from radioactive decay. Gamma decay commonly produces energies of a few hundred keV, and almost always less than 10 MeV. In astronomy, gamma rays are defined by their energy, and no production process need be specified. The energies of gamma rays from astronomical sources range over 10 TeV, at a level far too large to result from radioactive decay. A notable example is extremely powerful bursts of high-energy radiation normally referred to as long duration gamma-ray bursts, which produce gamma rays by a mechanism not compatible with radioactive decay. These bursts of gamma rays, thought to be due to the collapse of stars called hypernovas, are the most powerful events so far discovered in the cosmos.

Read more about Gamma Ray:  Sources of Gamma Rays, General Characteristics, Naming Conventions and Overlap in Terminology, Units of Measure and Exposure, Health Effects, Uses, History of Discovery

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... Firefly, by NASA's Goddard Space Flight Center and Siena College Terrestrial gamma-ray flashes have been detected from the Compton Gamma Ray Observatory ... This, in turn, will allow scientists to better determine if lightning is the source of the gamma-ray bursts ...
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List Of Space Telescopes - Gamma Ray
... Further information Gamma ray astronomy Gamma ray telescopes collect and measure individual, high energy gamma rays from astrophysical sources ... Gamma rays can be generated by supernovae, neutron stars, pulsars and black holes ... Gamma ray bursts, with extremely high energies, have also been detected but have yet to be identified ...
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... pulsar, PSR B1937+21 The brightest millisecond pulsar, PSR J0437-4715 The first X-ray pulsar, Cen X-3 The first accreting millisecond X-ray pulsar, SAX J1808.4-3658 The ... remnant (4U 0000+72, in Cassiopeia) was found by the Fermi Gamma-ray Space Telescope to emit pulsations only in gamma ray radiation, the first recorded of ... PSR J1311–3430, the first millisecond pulsar discovered via gamma-ray pulsations and part of a binary system with the shortest orbital period ...

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