{"id":12003,"date":"2016-05-07T13:01:42","date_gmt":"2016-05-07T13:01:42","guid":{"rendered":"http:\/\/sitepourvtc.com\/?page_id=12003"},"modified":"2022-10-31T08:42:36","modified_gmt":"2022-10-31T08:42:36","slug":"antineutrino","status":"publish","type":"page","link":"https:\/\/sitepourvtc.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/antineutrino\/","title":{"rendered":"Antineutrino"},"content":{"rendered":"
Antineutrinos<\/strong> are the antiparticles of neutrinos<\/a>. The\u00a0antineutrino is an elementary subatomic particle<\/a> with infinitesimal mass (less than 0.3eV..?) and no electric charge. Antineutrinos are produced in the negative beta decay<\/strong>. <\/div><\/div>\n
\"beta<\/a>
Beta-decay of C-14 nucleus.<\/figcaption><\/figure>\n

Neutrinos and antineutrinos belong to the family of leptons<\/strong>, which means they do not interact via strong nuclear force. Neutrinos are gravitational and weakly interacting<\/strong> subatomic particles with \u00bd unit of spin. Also, antineutrinos (as neutrinos) are very penetrating subatomic particles, capable of passing through Earth without any interaction. Currently (2015), it is not resolved whether the neutrino and its antiparticle are not identical particles.<\/p>\n

\"Neutrino<\/a>
Source: wikipedia.org<\/figcaption><\/figure>\n

Antineutrinos are produced in the negative beta decay<\/strong>. A nuclear reactor<\/a> occurs especially the \u03b2\u2212<\/sup> decay because the common feature of the fission products<\/a> is an excess of neutrons (see Nuclear Stability<\/a>). An unstable fission fragment with the excess of neutrons<\/a> undergoes \u03b2\u2212<\/sup> decay, where the neutron is converted into a proton, an electron, and an electron antineutrino<\/strong>. Therefore each nuclear reactor is a very powerful source of antineutrinos, and researchers worldwide investigate the possibilities of using antineutrinos for reactor monitoring.<\/p>\n

On the other hand, the most powerful source of neutrinos<\/strong> in the solar system is doubtless the Sun itself. Billions of solar neutrinos<\/strong> per second pass (mostly without any interaction) through every square centimeter (~6 x 1010<\/sup> cm-2<\/sup>s-1<\/sup>) on the Earth\u2019s surface. In the Sun, neutrinos are produced after the fusion reaction of two protons during positive beta decay<\/strong> of helium-2 nucleus.<\/p>\n

\"_{2}^{2}\\textrm{He}\\rightarrow<\/p>\n

\n

Detection of Antineutrinos<\/h2>\n
\"Antineutrino<\/a>
Before being filled with a clear liquid scintillator, the inside of a cylindrical antineutrino detector reveals antineutrino interactions by the very faint flashes of light they emit. Sensitive photomultiplier tubes line the detector walls, ready to amplify and record the telltale flashes.
Photo: Roy Kaltschmidt, LBNL
Source: Daya Bay Reactor Neutrino Experiment<\/figcaption><\/figure>\n

Since neutrinos do not ionize<\/strong>\u00a0matter,\u00a0they cannot be detected directly. The antineutrino detection (1995 Nobel Prize for Frederick Reines and Clyde Cowan)<\/strong> is \u00a0based on the reaction:<\/p>\n

\"\"<\/p>\n

This interaction is symmetrical to the beta decay of the free neutron<\/a>. Therefore it is sometimes referred to as inverse beta decay<\/strong>. All detection methods require the neutrinos to carry minimum threshold energy of 1.8 MeV<\/strong>. Only antineutrinos with an energy above the threshold of 1.8 MeV can cause interactions with the protons in the water, producing positrons<\/a> and neutrons<\/a>.<\/p>\n

Nuclear Reactor as the Antineutrino Source<\/h2>\n

Nuclear reactors<\/a> are the major source of human-generated antineutrinos. This is because antineutrinos are produced in negative beta<\/a> decay. A nuclear reactor occurs especially the \u03b2\u2212<\/sup> decay because the common feature of the fission fragments<\/a> is an excess of neutrons<\/a> (see Nuclear Stability<\/a>).<\/p>\n

\"antineutrino\"<\/a><\/p>\n

An unstable fission fragment with the excess of neutrons undergoes \u03b2\u2212<\/sup> decay, where the neutron is converted into a proton, an electron, and an electron antineutrino<\/strong>. The existence of emission of antineutrinos and their very low cross-section<\/strong> for any interaction leads to a very interesting phenomenon. Roughly about 5%<\/strong> (or about 12 MeV of 207 MeV) of released energy per one fission<\/a> is radiated away<\/strong> from the reactor in the form of antineutrinos. For a typical nuclear reactor with thermal power of 3000 MWth<\/sub> (~1000MWe<\/sub> of electrical power), the total power produced is higher, approximately 3150 MW, of which 150 MW is radiated away into space antineutrino radiation. This amount of energy is forever lost since antineutrinos can penetrate all reactor materials without any interaction. A common statement in physics texts is that the mean free path of a neutrino is approximately a light-year of lead<\/strong>. Moreover, a neutrino of moderate energy can easily penetrate a thousand light-years of lead (according to\u00a0J. B. Griffiths<\/em>).<\/p>\n

Please note that billions of solar neutrinos per second pass<\/strong> (mostly without any interaction) through every square centimeter (~6×1010<\/sup>) on the Earth\u2019s surface and antineutrino radiation\u00a0is by no means dangerous.<\/p>\n

\"antineutrino<\/a>
Source: Slides – Dr. Blucher, Enrico Fermi Institute<\/figcaption><\/figure>\n

Example – Amount of antineutrinos produced:<\/h2>\n

Stable nuclei<\/strong> with most likely mass number A from U-235<\/strong> fission are \"_{40}^{94}\\textrm{Zr}\"\u00a0and \"_{58}^{140}\\textrm{Ce}\". These nuclei have together 98 protons<\/strong> and 136 neutrons<\/strong>, while fission fragments<\/strong> (parent nuclei<\/strong>) have together 92 protons<\/strong> and 142 neutrons<\/strong>. This means the fission fragments must undergo on average 6 negative beta decays<\/strong> (6 neutrons must decay to 6 protons<\/strong>) after each U-235 fission, and therefore 6 antineutrinos must be produced per each fission<\/strong>. The typical nuclear reactor therefore produces approximately 6 x 1020<\/sup> antineutrinos per second<\/strong> (~200 MeV\/fission; ~6 antineutrinos\/fission; 3000 MWth<\/sub>; 9.375 x 1019<\/sup> fissions\/sec).<\/p>\n

Reference: Griffiths, David, Introduction to Elementary Particles, Wiley, 1987.<\/strong><\/p>\n<\/div>\n

<\/div>\n
\n

See previous:<\/h2>\n

Neutrino<\/i> <\/span><\/a><\/p><\/div><\/div>

\n

See above:<\/h2>\n

Fundamental Particles<\/i> <\/span><\/a><\/p><\/div><\/div>

\n

See next:<\/h2>\n<\/div><\/div>\n","protected":false},"excerpt":{"rendered":"

Neutrinos and antineutrinos belong to the family of leptons, which means they do not interact via strong nuclear force. Neutrinos are gravitational and weakly interacting subatomic particles with \u00bd unit of spin. Also, antineutrinos (as neutrinos) are very penetrating subatomic particles, capable of passing through Earth without any interaction. Currently (2015), it is not resolved … Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"parent":11285,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"generate_page_header":""},"_links":{"self":[{"href":"https:\/\/sitepourvtc.com\/wp-json\/wp\/v2\/pages\/12003"}],"collection":[{"href":"https:\/\/sitepourvtc.com\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/sitepourvtc.com\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/sitepourvtc.com\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/sitepourvtc.com\/wp-json\/wp\/v2\/comments?post=12003"}],"version-history":[{"count":4,"href":"https:\/\/sitepourvtc.com\/wp-json\/wp\/v2\/pages\/12003\/revisions"}],"predecessor-version":[{"id":33700,"href":"https:\/\/sitepourvtc.com\/wp-json\/wp\/v2\/pages\/12003\/revisions\/33700"}],"up":[{"embeddable":true,"href":"https:\/\/sitepourvtc.com\/wp-json\/wp\/v2\/pages\/11285"}],"wp:attachment":[{"href":"https:\/\/sitepourvtc.com\/wp-json\/wp\/v2\/media?parent=12003"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}