Computer Aided Radioactive Particle

As a result of slow (thermal) neutron irradiation, a sample composed of stable atoms of a variety of elements will produce several radioactive isotopes of these activated elements. For a nuclear reaction to be useful analytically in the delayed NAA mode the element of interest must be capable of undergoing a nuclear reaction of some sort, the product of which must be radioactively unstable. The daughter nucleus must have a half-life of the order of days or months (so that it can be conveniently measured), and it should emit a particle which has a characteristic energy and is free from interference from other particles which may be produced by other elements within the sample. The induced radioactivity is complex as it comprises a summation of all the active species present. Individual species are identified by computer-aided de-convolution of the data. Parry (1991 42-9) and Glascock (1998) summarize the relevant decay schemes, and Alfassi (1990 3) and Glascock (1991 Table 3) list y ray energy spectra and percentage abundances for a number of isotopes useful in NAA. 

The radioactive-tracer technique was perfected for. fluidized-bed application through the development of a computer-aided particle-tracking facility (CAPTF) (Lin, Chen, and Chao, 1985 Moslemian, 1987 Sun, 1989). Considerable effort was expended to develop the efficient photoncounting instrumentation and automated data reduction and processing schemes. In Section 9.2, the principle of radiation detection and a theoretical model of the CAPTF is presented. The instrumentation of the CAPTF and the data reduction schemes are described in Section 9.3. Sample results obtained by the CAPTF are presented in Sections 9.4 and 9.5, and a conclusion is presented in Section 9.6. 

A computer-aided particle-tracking facility (CAPTF) has been developed to measure the motion of radioactive tracers in fluidized beds. This achievement was the first successful attempt to use the radioactive tracer technique to obtain detailed quantitative information on solids dynamic data in fluidized beds. The CAPTF makes use of one or more radioactive tracer particles that are dynamically identical to the bed particles under study. In... 

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