Beta emissions detecting

Write nuclear equations for (a) alpha emission by plutonium-239, one of the substances formed in nuclear power plants, (b) beta emission by sodium-24, used to detect blood clots, (c) positron emission by oxygen-15, used to assess the efficiency of the lungs, and (d) electron capture by copper-64, used to diagnose lung disease. 

Phosphorus-32, which is used to detect breast cancer, undergoes beta emission. Write the nuclear equation for this reaction. 

With proper safety procedures, radiation can be useful in many scientific experiments and industrial applications. For instance, neutron activation analysis is used to detect trace amounts of elements present in a sample. Computer-chip manufacturers use this technique to analyze the composition of highly purified silicon wafers. In the process, the sample is bombarded with a beam of neutrons from a radioactive source, causing some of the atoms in the sample to become radioactive. The type and amount of radiation emitted by the sample is used to determine the types and quantities of elements present. Neutron activation analysis is a highly sensitive measurement technique capable of detecting quantities of less than 1 x 10 atoms in a sample. Beta emission is another application of radiation. It is used to measure paper thickness, as shown in Figure 24.26. 

It is impossible for us to improve on this review however, to maintain continuity in our presentation, we have selected some references to illustrate the diverse nature of small-mammal tagging applications. It is obvious that selection of the appropriate radionuclide for a specific study is determined by characteristics already discussed in this chapter, e.g., physical and biological half-life, high-energy gamma emissions and low beta emissions, characteristics of the animal being studied, and the detection equipment available. 

To their delight, they detected beta emission following neutron bombardment of uranium and thought they had perhaps synthesized the first man-made element. 

The simplest method for detection is by direct exposure (autoradiography) produced by intimate contact of the developed plate with a photographic or x-ray film. Direct exposure is useful for all of the beta emitters, with the possible exception of low-level tritium-labeled samples. A variety of films have been examined for use in autoradiography (5,18,19,21-24,29-33). For maximum sensitivity, the film emulsion must be efficiently penetrated and interact with the radioactive emission. Low-energy isotopes, especially tritium, require the use of film that does not have the normal protective emulsion coating, which would prevent the beta emissions from being detected (21,33). 

Liquid scintillation spectrometers. Also known as liquid scintillation counters, these instruments are in widespread use in biomedical laboratories. They possess high efficiencies at detecting low-energy beta emissions, and the electronic spectrometer can be adjusted to identify counts resulting primarily from a selected isotope. Thus these units can also be used to identify unknown contaminants. They operate on the principle similar to the scintillation probe, except a liquid scintillator solution is used in place of a crystal detector. 

Sodium-24 (atomic mass = 23.99096) decays by beta emission. One of its uses is in the detection of leaks in water pipes. 

The methods for detection and quantitation of radiolabeled tracers are deterrnined by the type of emission, ie, y-, or x-rays, the tracer affords the energy of the emission and the efficiency of the system by which it is measured. Detection of radioactivity can be achieved in all cases using the Geiger counter. However, in the case of the radionucHdes that emit low energy betas such as H, large amounts of isotopes are required for detection and accurate quantitation of a signal. This is in most cases undesirable and impractical. Thus, more sensitive and reproducible methods of detection and quantitation have been developed. 

A phosphor screen can be used like an autoradiography film to detect radioactive zones on PLC plates. The available screens are sensitive to x-rays and beta and gamma emissions from isotopes such as H, bij 32p 33p -pjjg screen captures... 

These are unstable forms of elements which decay by the emission of radiation. A radioactive isotope of an element behaves chemically in the same way as the non-radioactive form, but its radiation may be detected and measured by a suitable instrument. In the rubber industry radioactive isotopes are used in beta ray thickness gauges, in studying the precise role of sulphur in vulcanisation, in the speedy determination of tread wear in tyres, etc. See Beta Rays. 

Some substances, known as fluors or scintillants, respond to the ionizing effects of alpha and beta particles by emitting flashes of light (or scintillations). While they do not respond directly to gamma rays, they do respond to the secondary ionization effects that gamma rays produce and, as a result, provide a valuable detection system for all emissions. 

Promethium is identified by x-ray emission spectra, spark spectrum, and other spectroscopic methods. At extremely low concentrations, the element can be measured by ICP-MS. Also promethium and its salts can be detected from their pale—blue or greenish glow in the dark due to their radioactivity. Highly sensitive beta probes can be used for monitoring radioactive Pm-147. 

In 1899 he identified two forms of radioactivity, which he called alpha and beta particles. As we saw earlier, he deduced that alpha particles are helium nuclei. Beta particles are electrons - but, strangely, they come from the atomic nucleus, which is supposed to be composed only of protons and neutrons. Before the discovery of the neutron this led Rutherford and others to believe that the nucleus contained some protons intimately bound to electrons, which neutralized their charge. This idea became redundant when Chadwick first detected the neutron in 1932 but in fact it contains a deeper truth, because beta-particle emission is caused by the transmutation ( decay ) of a neutron into a proton and an electron. 

Since the radioactive sample material from most methods of sample preparation is in intimate contact or in actual solution with the phosphor, the detection of emitted particles or radiation is highly efficient and may even approach 100%. Problems of self-absorption of the emissions are thus absent, or considerably smaller than those associated with planchette counting of solid samples. This is of particular importance for the measurement of low energy beta emitters such as tritium and carbon-14. On the other hand, the measurement method has intrinsic drawbacks such as quenching and chemiluminescence. 

Carbon-14, the radioactive isotope of carbon, has been widely used in mechanistic studies with organic hydrocarbons but not in kinetic studies. decays to with the emission of a beta particle and has an extremely long half life (5568 30 years). The emitted radiation can be detected by an ionisation chamber,... 

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