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For example, gamma rays that require 1 cm (0.4 inch) of lead to reduce their intensity by 50% will also have their intensity reduced in half by 4.1 cm of granite rock, 6 cm (2.5 inches) of concrete, or 9 cm (3.5 inches) of packed soil. However, the mass of this much concrete or soil is only 20–30% greater than that of lead with the same ...
Gamma-ray astronomy is a subfield of astronomy where scientists observe and study celestial objects and phenomena in outer space which emit cosmic electromagnetic radiation in the form of gamma rays, [nb 1] i.e. photons with the highest energies (above 100 keV) at the very shortest wavelengths.
No gamma-ray bursts from within our own galaxy, the Milky Way, have been observed, [161] and the question of whether one has ever occurred remains unresolved. In light of evolving understanding of gamma-ray bursts and their progenitors, the scientific literature records a growing number of local, past, and future GRB candidates.
A gamma ray burst (GRB) is the most powerful form of explosion in the known universe. They are produced when massive stars die, right before they turn into black holes, and were originally ...
The ratio of primary cosmic ray hadrons to gamma rays also gives a clue as to the origin of cosmic rays. Although gamma rays could be produced near the source of cosmic rays, they could also be produced by interactions with the cosmic microwave background by way of the Greisen–Zatsepin–Kuzmin limit cutoff above 50 EeV. [9]
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 ...
Such a gamma-ray burst may have been the cause of the Ordovician–Silurian extinction events. This scenario is unlikely in the foreseeable future. [ 136 ] Astroengineering projects proposed to mitigate the risk of gamma-ray bursts include shielding the Earth with ionised smartdust and star lifting of nearby high mass stars likely to explode in ...
Artist's conception of gamma-ray flash and related phenomena. The red dots show some of the ~500 terrestrial gamma-ray flashes daily detected by the Fermi Gamma-ray Space Telescope through 2010. A terrestrial gamma-ray flash (TGF), also known as dark lightning, is a burst of gamma rays produced in Earth's atmosphere.