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  2. Gamma ray - Wikipedia

    en.wikipedia.org/wiki/Gamma_ray

    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.

  3. Gamma-ray burst - Wikipedia

    en.wikipedia.org/wiki/Gamma-ray_burst

    In gamma-ray astronomy, gamma-ray bursts (GRBs) are immensely energetic explosions that have been observed in distant galaxies, being the brightest and most extreme explosive events in the entire universe, [ 1 ][ 2 ][ 3 ] as NASA describes the bursts as the "most powerful class of explosions in the universe". [ 4 ]

  4. Electromagnetic spectrum - Wikipedia

    en.wikipedia.org/wiki/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, ultraviolet, X-rays, and ...

  5. GRB 221009A - Wikipedia

    en.wikipedia.org/wiki/GRB_221009A

    Related media on Commons. [edit on Wikidata] GRB 221009A was an extraordinarily bright and very energetic gamma-ray burst (GRB) jointly discovered by the Neil Gehrels Swift Observatory and the Fermi Gamma-ray Space Telescope on October 9, 2022. The gamma-ray burst was ten minutes long, [1] but was detectable for more than ten hours following ...

  6. Commonly used gamma-emitting isotopes - Wikipedia

    en.wikipedia.org/wiki/Commonly_used_gamma...

    It has a half-life of 30 years, and decays by beta decay without gamma ray emission to a metastable state of barium-137 (137m Ba). Barium-137m has a half-life of a 2.6 minutes and is responsible for all of the gamma ray emission in this decay sequence. The ground state of barium-137 is stable. The photon energy (energy of a single gamma ray) of ...

  7. Gamma-ray astronomy - Wikipedia

    en.wikipedia.org/wiki/Gamma-ray_astronomy

    The Moon as seen by the Energetic Gamma Ray Experiment Telescope (EGRET), in gamma rays of greater than 20 MeV. These are produced by cosmic ray bombardment of its surface. [1] Gamma-ray astronomy is a subfield of astronomy where scientists observe and study celestial objects and phenomena in outer space which emit cosmic electromagnetic ...

  8. Gamma ray cross section - Wikipedia

    en.wikipedia.org/wiki/Gamma_ray_cross_section

    A gamma ray cross section is a measure of the probability that a gamma ray interacts with matter. The total cross section of gamma ray interactions is composed of several independent processes: photoelectric effect, Compton (incoherent) scattering, electron-positron pair production in the nucleus field and electron-positron pair production in the electron field (triplet production).

  9. Decay scheme - Wikipedia

    en.wikipedia.org/wiki/Decay_scheme

    Decay scheme. The decay scheme of a radioactive substance is a graphical presentation of all the transitions occurring in a decay, and of their relationships. Examples are shown below. It is useful to think of the decay scheme as placed in a coordinate system, where the vertical axis is energy, increasing from bottom to top, and the horizontal ...