Beta energy spectrum

Figure 3.8 A typical beta energy spectrum (shows shape only does not mean that p is more intense than...

Figure 13.12 A typical beta energy spectrum (solid line) and its Kurie plot (dashed line).

In the last decade, neutrino experiments have demonstrated that neutrinos are massive particles which may oscillate among three autostates. Such experiments [77-82] have evidenced the mass difference between the autostates, but not the neutrino mass scale value. The only way to determine the neutrino mass is the knowledge of the shape of the end point of energy spectrum in beta decays. In the hypothesis of the Majorana neutrino (neutrino coincides with antineutrino and its rest mass is different from zero), the measure of the decay half-life in the neutrinoless double-beta decay (DBD) would be necessary. A number of recent theoretical interpretations of neutrino oscillation experiments data imply that the effective Majorana mass of the electron neutrino (as measured in neutrinoless DBD) could be in the range 0.01 eV to the present bounds. 

In this experiment, tritiated water is purified by simple distillation, and the tritium beta particles in the condensate are measured with a liquid scintillation (LS) counter. Such distillation also can collect tritiated water samples from solids. Tritium in other forms must be processed before it can be counted like tritium in water for example, tritiated hydrogen gas and tritiated organic substances can be oxidized to form water. Additional separations may be needed if the liquid or solid sample contains radioactive gases or volatile substances other than tritium that may be collected with the distilled tritiated water. Such radioactive impurities can be identified in the data output from the LS counter of an energy spectrum that differs from that of pure tritium, or of counts in energy regions where tritium counts are not found. 

It has been assumed that the chemical procedure used to isolate the element after the addition of carrier has been successful, and the final product is free from all extraneous activity. Frequently the reliability of this assumption can be verified without a great deal of difficulty, by the application of some or all of the following checks (1) determination of the half-life (2) determination of the maximum beta energy (3) examination of the gamma spectrum. 

The sensitivity of analytical methods for trace elements needs to be high, and ideally the reaction or property utilized should be entirely specific. The sensitivity of activation analysis is dependent on the element estimated and in many cases it is extremely high. Specificity is covered by three parameters, half-life of the nuclide produced, its maximum beta energy, and its gamma spectrum. 

There is an infinite number of combinations of kinetic energies and momenta that satisfy these two equations and as a result, the energy spectrum of the betas is continuous. 

Beta particles have a continuous energy spectrum extending from zero energy up to maximum kinetic energy (see Sec. 3.7.3). If the transmission experiment shown in Fig. 4.5 is repeated with an incident beam of jS particles, the result will look as shown in Fig. 4.11. The number of betas N(t) transmitted through a thickness t is very closely represented by... 

Pure beta-emitting isotopes exist and may be used for calibration, but only after the energy spectrum is cast into a form called the Kurie plot. The beta spectrum is continuous and extends from zero energy up to a maximum end point kinetic energy (see Fig. 13.12). Because of the shape of the spectrum, it is impossible to accurately determine the end point energy. However, from the... 

The division between electrons and betas is necessary (although beta particles are electrons) because an electron beam consists of monoenergetic electrons a beam of beta particles consists of electrons emitted by the beta decay of a nucleus. Therefore, as explained in Chap. 3, these particles have an energy spectrum with a maximum energy and an average energy... 

The energy spectrum of a beta-particle group takes the form of a continuum that has different shapes for different radionuclides three are shown in Fig. 2.5. Because of the energy distribution of beta particles, the relationships observed for the interaction of beta particles with matter are not as simple as those of alpha particles. 

The energy spectrum presented by the LS system does not exactly reflect the beta-particle spectrum because some energy is not deposited or is lost in... 

As an example, the information in Table 8.6 summarizes the data collected for a C standard (134,900 dpm) in six energy regions of the beta-particle spectrum. The table also includes the data from a simulated unknown sample with °Sr and in secular equilibrium with a total beta-particle-activity of 1037 dpm. 

Figure 4 The energy spectrum of antineutrinos produced by the fission of Pusagand U235 multipiied by the inverse beta decay cross section. The interaction threshoid is 1.8 MeV.

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