Beta-decay probability

The beta decay probabilities calculated using the exact wavefunctions are shown in Fig. 74 as a function of Vf.. The superallowed decay of Ne is not a sharp function of the interaction potential, since there is no change of supermultiplet, but the 0 decays give an estimate of which agrees fairly well with that 0 —obtained from the level spectrum. 

Most gamma-rays are a consequence of beta decay. Gamma-emission probabilities are not necessarily the same as beta decay probabilities because of internal conversion. This latter can result in X-radiation. 

Perturbation theory was applied to the ionization of atoms accompanying alpha and beta decay soon after the advent of quantum theory (Migdal, 1941). Migdal concluded that the probability for... 

The conversion of muonium (y+e ) to its antiatom antimuonium (y e+) would be an example of a muon number violating process,2 and like neutrinoless double beta decay would involve ALe=2. The M-M system also bears some relation to the K°-K7r system, since the neutral atoms M and M are degenerate in the absence of an interaction which couples them. In Table III a four-Fermion Hamiltonian term coupling M and M is postulated, and the probability that M formed at time t=0 will decay from the M mode is given. Present experimental limits22 23 for the coupling constant G are indicated and are larger than the Fermi constant Gp. 

Positron emission and electron capture are conq>eting processes with the probability of the latter increasing as the atomic number increases. Beta decay is properly used to designate all three processes, 0, /, and EC. (The term "beta decay" without any specification usually only refers to /3 emission.)... 

Notice we have replaced v by P, which is the designation of the antineutrino. Beta-decay theory has shown that antineutrinos P are emitted in electron decay, and "regular" neutrinos V in positron decay. We can consider the particles identical cf. 10.4. Because of the extremely low probability of interaction or neutrinos with matter, they are unfortunately often omitted in writing /3-decay reactions. 

If a neutron penetrated a uranium nucleus, for example, the result might be fission. But if the neutron happened to be traveling at the appropriate energy when it penetrated—somewhere aroimd 25 eV—the nucleus would probably capture it without fissioning. Beta decay would follow, increasing the nuclear charge by one unit the result should be a new, as-yet-unnamed transuranic element of atomic number 93. That was one of Plac-zek s points. It would prove in time to be crucial. 

The parameter ajK may also be deduced from the intermediate-coupling calculations of reduced width, beta-decay lifetime, and M1 transition probability given by Lane . Of these quantities the reduced width is most sensitive to... 

No levels of the proton-unstable nucleus are known. levels are obtained from the (dp), (den) and (hol) reactions. The beta decay of to the 0 ground state is first forbidden, but transitions to the 7.12 and 6.14 MeV negative parity states are allowed, and the subsequent gamma radiation has been detected. The spin of is therefore probably 2". The isotopic spin allowed transition between the 7.12 and 6.14 MeV levels was not observed and the difference in intensity between the beta-spectrum components and the subsequent radiations is attributed to experimental uncertainties in the measurement of the former. 

The beta decay of is a simple allowed (unfavoured) transition to the 2 excited state of Ne o at I.63 MeV again it is not clear why the equivalent ground state transition does not take place, but the reason probably lies in the particular configurations. Thus if the F o and Ne states were described by a particularly complex set of configurations while the Ne ground state was simply s, the results might be explained. The Na o decay may contain a weak superallowed component to the first T — i level of Ne . 

The nuclide SP was found by Lindner in the spallation products of chlorine bombarded by high energy protons and by Turkevich and Samuels in neutron irradiated quartz. The beta decay energy is found to be about 100 keV, and the lifetime about 700 years. This locates the lowest T — 2 level of at an excitation of 11.23 MeV. The decay is probably to the ground state of P transition... 

Antineutrinos are detected through interactions with quasi-free protons, with electrons, or with nuclei. Proton targets are well suited for detecting antineutrinos with energies in the MeV range because of the relatively high probability and low energy threshold of the interaction. Li the proton-antineutrino interaction, referred to as inverse beta decay, the antineutrino converts the proton into a neutron and a positron, as shown in equation 2. 

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... 

The shell model of deformed nuclei was verified for hundreds of nuclei and proved to be very successful. It can account for level schemes, moments, electromagnetic transition probabilities, single-particle transfer reactions, beta-decay properties, etc. in the deformed regions (A a 25, 150 < A < 190, A > 220). 

Still, the Fermi integral function f Z, p) is very useful even in the general case, because it can help visualize the overall dependence of the decay constant 1 on the beta energy and the atomic number Z For instance, Figs. 42A and B in Chap. 2 (as well as Fig. 7.15) show that (1) the probability for beta decay steeply increases with beta energy (this is equally true for positive and negative beta decay), (2) negative beta decay becomes more probable as the atomic number increases, (3) positive beta decay becomes less probable as the atomic number increases. 

Nuclide Half life Positron energy in MeV) Probability of positive beta decay (%) Application... 

The general layout of the Karlsruhe Chart of the Nuclides has been described it has been used to explain beta decay and parts have been illustrated in Figures 1.3 and 1.16. In this section, I discuss its use in diagnosis, firstly as a data source, and then as an indicator of the location of probable nuclides. There are other versions of this chart, but none have made it onto the walls of counting rooms as often as the Karlsruhe Chart. 

All of the plutonium isotopes, with one exception, decay by alpha particle emission. The exception - " Pu beta-decays to " Am. It follows that uranium which has been reprocessed, and materials contaminated by it, may contain all of these transuranic nuclides. Because of their low gamma-ray emission probabilities, low levels of the plutonium isotopes are not easily measured by gamma spectrometry. 

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). 

Laboratory. The isotope produced was the 20-hour Fm. During 1953 and early 1954, while discovery of elements 99 and 100 was withheld from publication for security reasons, a group from the Nobel Institute of Physics in Stockholm bombarded with O ions, and isolated a 30-min a-emitter, which they ascribed to 100, without claiming discovery of the element. This isotope has since been identified positively, and the 30-min half-life confirmed. The chemical properties of fermium have been studied solely with tracer amounts, and in normal aqueous media only the (III) oxidation state appears to exist. The isotope and heavier isotopes can be produced by intense neutron irradiation of lower elements such as plutonium by a process of successive neutron capture interspersed with beta decays until these mass numbers and atomic numbers are reached. Twenty isotopes and isomers of fermium are known to exist. Fm, with a half-life of about 100.5 days, is the longest lived. °Fm, with a half-life of 30 min, has been shown to be a product of decay of Element 102. It was by chemical identification of Fm that production of Element 102 (nobelium) was confirmed. Fermium would probably have chemical properties resembling erbium. 

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