ESTIMATION OF TRUE COINCIDENCE CORRECTIONS FOR VOLUMINOUS SOURCES

Citation
Vp. Kolotov et al., ESTIMATION OF TRUE COINCIDENCE CORRECTIONS FOR VOLUMINOUS SOURCES, Journal of radioanalytical and nuclear chemistry, 210(1), 1996, pp. 183-196
Citations number
20
Categorie Soggetti
Chemistry Analytical","Nuclear Sciences & Tecnology","Chemistry Inorganic & Nuclear
ISSN journal
02365731
Volume
210
Issue
1
Year of publication
1996
Pages
183 - 196
Database
ISI
SICI code
0236-5731(1996)210:1<183:EOTCCF>2.0.ZU;2-R
Abstract
To analyze a voluminous radioactive source with the highest possible s ensitivity, it is necessary to use both a high efficiency detector and an optimal measurement geometry. The ''optimal'' geometry implies pos itioning the source as close to the detector as possible. It also impl ies selection of the shape of the source in order to reach the highest efficiency possible (e.g., Marinelli beaker). Under such conditions o f measurements, true coincidences may cause systematic errors that can reach levels of more than ten percent for some radionuclides. A metho d for estimation of the effect of these coincidences was developed. It is based on direct computation of the effect by means of integration of a function which involves the experimentally obtained detection eff iciency for the place around the detector it was found that for the te sted detector with a relative efficiency of 15%, the so-called intrins ic peak-to-total calibration may be used in the course of such an inte gration: It has been shown that the P/T-ratio for the given energy in the working space around the detector may be considered a constant val ue. Some results from a peak-to-total calibration study in the presenc e of scattering material are also given.