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In astrophysics, gamma rays are conventionally defined as having photon energies above 100 keV and are the subject of gamma-ray astronomy, while radiation below 100 keV is classified as X-rays and is the subject of X-ray astronomy. Gamma rays are ionizing radiation and are thus hazardous to life.
Iodine-131 is another important gamma-emitting radionuclide produced as a fission product. With a short half-life of 8 days, this radioisotope is not of practical use in radioactive sources in industrial radiography or sensing. However, since iodine is a component of biological molecules such as thyroid hormones, iodine-131 is of great ...
Electromagnetic spectrum. The electromagnetic spectrum is the full range of electromagnetic radiation, organized by frequency or wavelength. The spectrum is divided into separate bands, with different names for the electromagnetic waves within each band. From low to high frequency these are: radio waves, microwaves, infrared, visible light ...
Astronomy is a natural science that studies celestial objects and the phenomena that occur in the cosmos. It uses mathematics, physics, and chemistry in order to explain their origin and their overall evolution. Objects of interest include planets, moons, stars, nebulae, galaxies, meteoroids, asteroids, and comets.
Electron capture is the primary decay mode for isotopes with a relative superabundance of protons in the nucleus, but with insufficient energy difference between the isotope and its prospective daughter (the isobar with one less positive charge) for the nuclide to decay by emitting a positron. Electron capture is always an alternative decay ...
Cobalt-60, produced by neutron irradiation of ordinary cobalt metal in a reactor, is a high activity gamma-ray emitter, emitting 1.17 and 1.33 MeV gamma rays with an activity of 44 TBq/g (1,200 Ci/g). The main reason for its wide use in radiotherapy is that it has a longer half-life, 5.27 years, than many other gamma emitters. However, this ...
Nuclear densitometry is a technique used in civil construction and the petroleum industry, as well as for mining and archaeology purposes, to measure the density and inner structure of the test material. The processes uses a nuclear density gauge, which consists of a radiation source that emits particles and a sensor that counts the received ...
Discovery. Gamma-ray bursts were discovered in the late 1960s by the U.S. Vela nuclear test detection satellites. The Velas were built to detect gamma radiation pulses emitted by nuclear weapon tests in space. The United States suspected that the USSR might attempt to conduct secret nuclear tests after signing the Nuclear Test Ban Treaty in 1963.