3. Elusive Ghostly Neutrinos - ELUSIVE GHOSTLY NEUTRINOS M...

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ELUSIVE GHOSTLY NEUTRINOS M. Ragheb 2/15/2007 INTRODUCTION At every second of time, hundreds of billions of neutrinos pass through each square inch of our bodies. They come from above us during the day and from below us at night when the sun is shining on the other side of the Earth. The neutrinos can reveal information about the sun, the nature of dark matter, and the large scale structure of the universe. The sun is a large neutrino factory, and the neutrinos that it produces proceed through matter without significant interaction: a single neutrinos out of 10 11 passing through the whole Earth interacts with it. The sun releases 200 trillion trillion trillion or 2 x 10 38 neutrinos every second in all directions. Cosmic neutrinos also reach us from a recently observed Black Hole at the center of our galaxy. Particle accelerators are used to produce terrestrial neutrinos. Neutron fission reactors also generate terrestrial antineutrinos in the radioactive decay of the fission products generated by the fission process. In fact they carry 5 percent of the fission energy produced. If the fission energy release per reaction is 200 MeV, the fission antineutrinos carry about 10 MeV. From that perspective nuclear fission reactors are beacons radiating antineutrinos to the rest of the Universe announcing the presence of humanity to possible observers as an intelligent civilization that has mastered the control of fission energy. They do emit a high flux rate of antineutrinos: 10 21 antineutrinos/sec. The imbalance of matter and antimatter in the universe suggests a theory contending that its mass may have been produced from the decay of neutrinos and antineutrinos during the Big Bang. If that was the case, then they may have been the origin of everything around us and that we are descendants of the neutrinos. NEUTRINOS IN THE STANDARD MODEL According to the Standard Model of the constitution of matter, neutrinos are a type of lepton. Possessing no electrical or strong charge they almost never interact with any other particles. Most neutrinos pass right through the Earth without interaction. Neutrinos are produced in a variety of interactions, especially in particle decays. In fact, it was through a careful study of radioactive decays that physicists represented by Wolfgang Pauli hypothesized the neutrino's existence along the following line of reasoning: 1. In a neutron rich radioactive nucleus, a neutron at rest with zero momentum decays, releasing a proton and an electron. 2. Because of the law of conservation of momentum, the resulting products of the decay must have a total momentum of zero, which the observed proton and electron clearly do not.
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3. Therefore, we need to infer the presence of another particle with appropriate momentum to balance the event.
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