Beta decay processes

Two of these isotopes, carbon-12, the most abundant, and carbon-13 are stable. Carbon-14, on the other hand, is an unstable radioactive isotope, also known as radiocarbon, which decays by the beta decay process a beta particle is emitted from the decaying atomic nucleus and the carbon-14 atom is transformed into an isotope of another element, nitrogen-14, N-14 for short (chemical symbol 14N), the most common isotope of nitrogen ... 

Beta particles A beta particle is a very fast-moving electron that is emitted when a neutron in an unstable nucleus converts into a proton. Beta particles are represented by the symbol (3 or e. They have a 1 — charge. Their mass is so small compared with the mass of nuclei involved in nuclear reactions that it can be approximated to zero. Beta radiation consists of a stream of fast-moving electrons. An example of the beta decay process is the decay of iodine-131 into xenon-131 by beta-particle emission, as shown in Figure 24.4. Note that the mass number of the product nucleus is the same as that of the original nucleus (they are both 131), but its atomic number has increased by 1 (54 instead of 53). This change in atomic number occurs because a neutron is converted into a proton, as shown by the following equation. 

The second beta-decay process is positron (fi ) emission. Positron decay is illustrated by the symbolic equation... 

These expressions are complicated but simplify in many practical applications, particularly when spinless particles only are concerned. The interpretation of angular distribution patterns is also simplified by a number of general results for unpolarised beams and non-relativistic reactions. These are now listed and apply equally to particle-particle, particle-quantum or quantum-quantum correlations angular correlations in beta-decay processes are not considered here. 

These early results were confirmed in further experiments which measured the lifetime and electron emitting power of /i-mesons captured in different elements the early experiments are listed by Sigurgiersson and Yamakawa. The quantitative interpretation of these experiments has been given by Tiomno and Wheeler. They estimate that the coupling constants for the beta decay process and / -meson capture process, Eq. (50.1b) agree with one another within the limits of error of experiment and theory. 

Water detectors measure the Cerenkov light produced as the positron from the inverse beta decay process (equation 2) slows in the medium. The most probable positron energy is about two MeV, corresponding to the peak antineutrino energy of about 3.8 MeV. A two MeV positron travels about 1 cm through H2O, producing about 270 Cerenkov photons in the 350 to 550 nm range which may be detected by phototubes. For... 

Neutrino nil- tre-( )no, nyti- n [It, fr. neutro neutral, neuter, fr. L neutr-, neuter] (1935) An electrically neutral particle of very small (probably zero) rest mass and of spin quantum number When the spin is oriented parallel to the linear momentum the particle is the antineutrino. When the spin is oriented antiparallel to the linear momentum the particle is the neutrino. Postulated by Pauli in explaining the beta decay process. Whenever a beta (positron) particle is created in a radioactive decay so is an antineutrino (neutrino). 

Neutrinos are created in nuclear processes and in various elementary particle interactions. The most familiar process is nuclear beta-decay, in which an unstable nucleus simultaneously emits an electron (beta-ray) and a neutrino. This process may be visualized as an unstable nucleus radiating its energy by creating a pair of leptons a neutrino and an electron. It is referred to as beta-minus decay when an electron (e ) is emitted with an antineutrino Ve) or beta-plus decay when a positron (e+) is emitted with a neutrino (Vg). In another beta-decay process, called electron capture, one of the orbital electrons in an atom is absorbed by the nucleus and a neutrino is emitted. Examples of these processes are... 

Neutrinos may be absorbed in nuclei with the emission of an electron, a muon, or a tauon, depending on the incident neutrino type. These are called inverse-beta-decay processes because they are, in the case of the electron neutrino, the inverse of normal radioactive beta-decay. Neu-... 

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