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| [[File:Proton proton cycle.svg|350px|thumb|Solar neutrinos ([[Proton-proton chain reaction|proton-proton chain]]) in the [[Standard Solar Model]]]][[Electron neutrino]]s are produced in the [[Sun]] as a product of [[nuclear fusion]]. By far the largest fraction of neutrinos passing through the Earth are Solar neutrinos.
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| The main contribution comes from the [[proton-proton reaction]]. The reaction is:
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| : <math>p + p = \text{d} + e^{+} + \nu_e \!\ </math>
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| or in words:
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| : 2 [[protons]] = [[deuterium]] + [[positron]] + [[electron neutrino]].
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| From this reaction, 86% of all solar neutrinos are produced. As seen in figure, Solar neutrinos (proton-proton chain) in the Standard Solar Model, the deuterium will fuse with another proton to create a <sup>3</sup>He atom and a gamma ray. This reaction can be seen as:
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| : <math>d + p = ^{3}He + \gamma\ </math>
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| The isotope <sup>4</sup>He can be produced by using the <sup>3</sup>He in the previous reaction which is seen below.
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| : <math>^{3}He + ^{3}He = ^{4}He + 2 p </math>
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| With both helium-3 and helium-4 in the system now, beryllium can be fused by the reaction of one of each helium atom as seen in the reaction:
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| : <math>^{3}He + ^{4}He = ^{7}Be + \gamma\ </math>
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| Since there are four protons and only three neutrons, the beryllium can go down two different paths from here. The beryllium could capture an electron and produce a lithium-7 atom and an electron neutrino. It can also capture a proton due to the abundance in a star. This will create boron-8. Both reactions are as seen below respectfully:
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| : <math>^{7}Be + e^{-} = ^{7}Li + \nu_e\ </math>
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| This reaction produces 14% of the solar neutrinos. The lithium-7 will combine with a proton to produce 2 atoms of helium-4.
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| : <math>^{7}Be + p = ^{8}B + \gamma\ </math>
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| The boron-8 will beta(+) decay into beryllium-8 due to the extra proton which can be seen below:
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| : <math>^{8}B = ^{8}Be + e^{+} + \nu_e\ </math>
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| The reaction produces about 0.02% of the solar neutrinos. These few solar neutrinos have the larger energies.<ref>{{Citation |first=Claus |last=Grupen |title=Astroparticle Physics |publisher=Springer |year=2006 |isbn=3-540-25312-2}}{{page needed|date=October 2013}}</ref>
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| The highest flux of solar neutrinos come directly from the proton-proton interaction, and have a low energy, up to 400 keV. There are also several other significant production mechanisms, with energies up to 18 MeV.<ref>{{Citation |first=A. |last=Bellerive |url=http://arxiv.org/abs/hep-ex/0312045 |title=Review of solar neutrino experiments |journal=Int. J. Mod. Phys. |volume=A19 |year=2004 |pages=1167-1179 |arxiv=hep-ex/0312045 |doi=10.1142/S0217751X04019093}}</ref> From the Earth, the amount of neutrino flux at Earth is around 7·10<sup>10</sup> particles/(cm<sup>2</sup>/s).<ref>{{harvnb|Grupen|2006}}{{page needed|date=October 2013}}</ref>
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| The number of neutrinos can be predicted by the [[Standard Solar Model]]. The detected number of electron neutrinos was only 1/3 of the predicted number, and this was known as the [[solar neutrino problem]]. It led to the idea of [[neutrino oscillation]] and the fact that neutrinos can change flavour. This was confirmed when the total flux of solar neutrinos of all types was measured and it agreed with the earlier predictions of expected electron neutrino flux, as seen by [[Sudbury Neutrino Observatory]], and thus confirmed that neutrinos have mass.
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| The energy spectrum of solar neutrinos is also predicted by solar models.<ref>[http://www.sns.ias.edu/~jnb/SNviewgraphs/snviewgraphs.html Solar Neutrino Viewgraphs]</ref> It is essential to know this energy spectrum because different neutrino detection experiments are sensitive to different neutrino energy ranges. The [[Homestake Experiment]] used chlorine and was most sensitive to solar neutrinos produced by the decay of the [[Isotopes of beryllium|beryllium isotope]] <sup>7</sup>Be. The [[Sudbury Neutrino Observatory]] is most sensitive to solar neutrinos produced by <sup>8</sup>B. The detectors that use [[gallium]] are most sensitive to the solar neutrinos produced by the proton-proton chain reaction process. In 2012 the collaboration known as [[Borexino]] reported detecting low-energy neutrinos for the proton-electron-proton ([[Proton-proton_chain_reaction#The_pep_reaction|pep reaction]]) that produces 1 in 400 deuterium nuclei in the sun.<ref>{{citation |first=G. |last=Bellini |last2=et al |title=First Evidence of pep Solar Neutrinos by Direct Detection in Borexino |arxiv= |journal=Phys. Rev. Lett. |volume=108 |issue=5 |id=051302 |year=2012 |doi=10.1103/PhysRevLett.108.051302}}. 6 pages; preprint on arXiv</ref><ref>{{citation |first=Alexandra |last=Witze |title=Elusive solar neutrinos spotted, detection reveals more about reaction that powers sun |journal=Science News |volume=181 |issue=5 |date=March 10, 2012 |page=14 |doi=}}</ref> The detector contained 100 metric tons of liquid and saw on average 3 events each day (due to [[Isotopes_of_carbon#Carbon-11|carbon 11 production]]) from this relatively uncommon [[thermonuclear]] reaction.
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| Neutrinos can trigger nuclear reactions. By looking at ancient ores of various ages that have been exposed to solar neutrinos over geologic time, it may be possible to interrogate the luminosity of the Sun over time,<ref>http://adsabs.harvard.edu/abs/1990PhRvL..65..809H</ref> which, according to the [[Standard Solar Model]], has changed with time.
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| ==See also==
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| * [[Neutrino oscillations]]
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| * [[Solar neutrino problem]]
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| * [[Neutrino detector]]
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| ==References==
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| {{reflist|30em}}
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| [[Category:Nuclear fusion]]
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The author is known by the name of Numbers Wunder. Doing ceramics is what love doing. My working day occupation is a meter reader. South Dakota is exactly where I've always been residing.
my blog ... Cerveja.st