cosmic rays definition of cosmic rays in the Free Online Encyclopedia.

cosmic rays, charged particles moving at nearly the speed of light reaching the earth from outer space. Primary cosmic rays consist mostly of protons (nuclei of hydrogen atoms), some alpha particles (helium nuclei), and lesser amounts of nuclei of carbon, nitrogen, oxygen, and heavier atoms. These nuclei collide with nuclei in the upper atmosphere, producing secondary cosmic rays of protons, neutrons, mesons, electrons, and gamma rays of high energy, which in turn hit nuclei lower in the atmosphere to produce more particles (see elementary particles elementary particles, the most basic physical constituents of the universe.

Basic Constituents of Matter

Molecules are built up from the atom , which is the basic unit of any chemical element .
..... Click the link for more information. ). These cascade processes continue until all the energy of the primary particle is dissipated. The secondary particles shower down through the atmosphere in diminishing intensity to the earth's surface and even penetrate it. The size of the shower indicates the energy of the primary ray, which may be as high as 10²⁰ electron volts (eV) or more, almost a billion times higher than the highest energy yet produced in a man-made particle accelerator; however, cosmic rays of lower energy predominate. Cosmic rays were long used as a source of high-energy particles in the study of nuclear reactions. The positron, the muon muon (my
..... Click the link for more information. , the pion pion (pī`ŏn) or pi meson, lightest of the meson family of elementary particles .
..... Click the link for more information. (or pi meson meson (mē`zŏn) [Gr.,=middle (i.e.
..... Click the link for more information. ), and some of the so-called strange particles were initially discovered in studies of this radiation. Cosmic rays were first found to be of extraterrestrial origin by Victor F. Hess Hess, Victor Francis, 1883–1964, American physicist, b. Austria, Ph.D. Univ. of Graz, 1906. After teaching at the universities of Graz and Innsbruck, he came to the United States in 1938 and was later naturalized. He became professor of physics at Fordham Univ.
..... Click the link for more information. (c.1912) when he recorded them with electrometers carried to high altitudes in balloons, an achievement for which he won the Nobel Prize in 1936. They were so named in 1925 by R. A. Millikan Millikan, Robert Andrews (mĭl`ĭkən), 1868–1953, American physicist and educator, b. Morrison, Ill., grad.
..... Click the link for more information. , who did extensive research on them. Since then much pertinent information has been collected that have been of use in studying the chemical composition of the universe, but the origin of cosmic rays remains a mystery. However, when they react with interstellar gases, the result is a gamma ray that can be traced back. Spacecraft results indicate that many of the gamma rays appear to come from the direction of supernova remnants. The nature of the acceleration processes by which the primary particles achieve great velocities (very nearly the speed of light) is also still highly speculative. Modern electronic detectors called charge coupled devices (CCDs) are effective cosmic ray detectors; a ray can strike a single pixel, making it much brighter than the surrounding ones. Cosmic rays play a significant role in the natural mutation mutation, in biology, a sudden, random change in a gene , or unit of hereditary material, that can alter an inheritable characteristic. Most mutations are not beneficial, since any change in the delicate balance of an organism having a high level of adaptation to its
..... Click the link for more information. and evolution evolution, concept that embodies the belief that existing animals and plants developed by a process of gradual, continuous change from previously existing forms. This theory, also known as descent with modification, constitutes organic evolution.
..... Click the link for more information. of life on earth.

Bibliography

See B. B. Rossi, Cosmic Rays (1964); L. I. Dorman, Cosmic Rays (1974); M. W. Friedlander, Cosmic Rays (1989).

cosmic rays [′käz·mik ′rāz]

(nuclear physics)

Electrons and the nuclei of atoms, largely hydrogen, that impinge upon the earth from all directions of space with nearly the speed of light. Also known as cosmic radiation; primary cosmic rays.

cosmic rays - Notionally, the cause of bit rot. However, this is a semi-independent usage that may be invoked as a humorous way to handwave away any minor randomness that doesn't seem worth the bother of investigating. "Hey, Eric - I just got a burst of garbage on my tube, where did that come from?" "Cosmic rays, I guess." Compare sunspots, phase of the moon. The British seem to prefer the usage "cosmic showers"; "alpha particles" is also heard, because stray alpha particles passing through a memory chip can cause single bit errors (this becomes increasingly more likely as memory sizes and densities increase).

Factual note: Alpha particles cause bit rot, cosmic rays do not (except occasionally in spaceborne computers). Intel could not explain random bit drops in their early chips, and one hypothesis was cosmic rays. So they created the World's Largest Lead Safe, using 25 tons of the stuff, and used two identical boards for testing. One was placed in the safe, one outside. The hypothesis was that if cosmic rays were causing the bit drops, they should see a statistically significant difference between the error rates on the two boards. They did not observe such a difference. Further investigation demonstrated conclusively that the bit drops were due to alpha particle emissions from thorium (and to a much lesser degree uranium) in the encapsulation material. Since it is impossible to eliminate these radioactives (they are uniformly distributed through the earth's crust, with the statistically insignificant exception of uranium lodes) it became obvious that one has to design memories to withstand these hits.