Cosmic ray spallation 2447137 219675614 2008-06-16T10:51:38Z Necros.uy 4591170 {{Nucleosynthesis}} '''Cosmic ray spallation '''is a form of naturally occurring [[nuclear fission ]] and [[nucleosynthesis]]. It refers to the formation of [[chemical element|elements ]] from the impact of [[cosmic rays ]] on an object. Cosmic rays are highly energetic charged [[Subatomic particle|particles ]] from outside of [[Earth ]] ranging from stray [[electrons ]] to [[alpha particles ]]. These cause [[spallation ]] when a cosmic ray (e.g. a [[proton]]) impacts with [[matter]], including other cosmic rays. The result of the collision is the expulsion of large members of [[nucleons ]] (protons and neutrons) from the object hit. This process goes on not only in deep space, but in our upper atmosphere due to the impact of cosmic rays. Cosmic ray spallation produces some light elements such as [[lithium ]] and [[boron]]. This process was discovered somewhat by accident during the 1970s. Models of [[big bang nucleosynthesis ]] suggested that the amount of [[deuterium ]] was too large to be consistent with the expansion rate of the universe and there was therefore great interest in processes that could generate [[deuterium ]] after the big bang. Cosmic ray spallation was investigated as a possible process to generate deuterium. As it turned out, spallation could not generate much deuterium, and the excess deuterium in the universe could be explained by assuming the existence of non-[[baryonic ]][[dark matter]]. However, studies of spallation showed that it could generate lithium and boron. [[Isotopes ]] of [[aluminum]], [[beryllium]], [[carbon ]] ([[carbon-14]]), [[chlorine]], [[iodine ]] and [[neon]], are also formed through cosmic ray spallation. == See also == * [[Astrophysics]] * [[Cosmic rays]] * [[Nuclear fission]] * [[Nucleosynthesis]] * [[Spallation]] == External links == * [http://www.srl.caltech.edu/ACE/CRIS_SIS/cris.htmlCosmic Ray Isotope Spectrometer] * [http://sd-www.jhuapl.edu/VOYAGER/images/spec_req_ext/ICRC_26th_1999_Proc/root/VOL4/O3_2_10.PDF#search='cosmic%20ray%20spallation' University of Leeds paper] * [http://sd-www.jhuapl.edu/VOYAGER/images/spec_req_ext/ICRC_26th_1999_Proc/root/VOL4/O3_2_49.PDF#search='cosmic%20ray%20spallation'Ultra Heavy Cosmic Ray propagation Using New Spallation Cross-Section Expressions] * [http://www.nature.com/nature/journal/v325/n6102/abs/325335a0.html Evidence for cosmic ray spallation production of helium and neon found in volcanoes] [[Category:Cosmic rays]] [[Category:Nucleosynthesis]] [[es:Espalación de rayos cósmicos]] [[ko:우주선 파쇄]] [[zh:宇宙射線散裂]]