Since the electron is a much lighter particle, it was expected that it would carry away most of the released energy, which would have a unique value T e. To demonstrate the energetics of two-body beta decay, consider the beta decay in which an electron is emitted and the parent nucleus rest. It would seem reasonable to suppose that the beta particles would also form a monoenergetic beam. Because only the electron and the recoiling daughter nucleus were observed beta decay, the process was initially assumed to be a two-body process, very much like alpha decay. It was expected that the same considerations would hold for a parent nucleus breaking down to a daughter nucleus and a beta particle. In other words, the beam of alpha particles should be monoenergetic. Since the same particles appear as products at every breakdown of a particular parent nucleus, the mass difference should always be the same, and the kinetic energy of the alpha particles should also always be the same. As a result of the law of conservation of energy, this difference appears in the form of the kinetic energy of the alpha particle. For example, in the case of alpha decay, when a parent nucleus breaks down spontaneously to yield a daughter nucleus and an alpha particle, the sum of the mass of the two products does not quite equal the mass of the original nucleus (see Mass Defect). The particle carries the energy from the difference between the initial and final nuclear states. The resulting particle ( alpha particle or photon) has a narrow energy distribution in both alpha and gamma decay. The discovery of the neutrino is based on the law of conservation of energy during beta decay. The study of beta decay provided the first physical evidence for the existence of the neutrino. See also: Nuclear Reactor as the Antineutrino Source. Reference: Griffiths, David, Introduction to Elementary Particles, Wiley, 1987. It is estimated neutrino cross-section for interaction increases linearly with the energy of the incident neutrino. It is estimated neutrinos have interaction cross-sections about 20 orders of magnitude less than typical cross-sections of scattering of two nucleons (~10 -47m2 = 10 -19barn). Therefore, neutrinos are the most penetrating subatomic particles, capable of passing through Earth without any interaction. Neutrinos are subject to the weak force, which is of a much shorter range than the electromagnetic force and gravity force. Since neutrinos belong to the family of leptons, they are not subject to strong force. Currently (2015), it is not resolved whether the neutrino and its antiparticle are not identical particles.Ĭarrying no electric charge, they are not affected by electromagnetic forces that act on other charged leptons, such as electrons. The second-generation consist of the muon (μ −) and muon neutrino (ν μ) The third generation consist of the tau (τ −) and the tau neutrino (ν τ). Each type of neutrino is associated with an antimatter particle, called an antineutrino, which also has a neutral electric charge and 1/2 spin. The first generation consists of the electron (e −) and electron-neutrino (ν e). There are three types of charged leptons, each associated with neutrino, forming three generations (between generations, particles differ by their quantum number and mass). The term neutrino comes from Italian, meaning “little neutral one,” and neutrinos are denoted by the Greek letter ν (nu). Neutrinos are weakly interacting subatomic particles with ½ units of spin. Neutrinos belong to the family of leptons, which means they do not interact via strong nuclear force. A neutrino is an elementary subatomic particle with infinitesimal mass (less than 0.3 eV.?) and no electric charge.
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