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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 2:11 |
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Conference: Bucharest University Faculty of Physics 2010 Meeting
Section: Applied Nuclear Physics
Title:
The use of the Efficiency Tracing CIEMAT/NIST method for quantification of the beta-emitters in LSC
Authors:
Relu Dobrin (1), Margarit Pavelescu (2) and Cristian Dulama (1)
Affiliation:
(1) Institute for Nuclear Research, Pitesti, Romania
(2) Academy of Romanian Scientists, Bucharest, Romania
E-mail
relu.dobrin@gmail.com
Keywords:
CIEMAT/NIST method, efficiency tracing, theoretical counting efficiency, figure of merit
Abstract:
The Liquid Scintillation Counting is the most suitable technique for the quantitative analysis of the β-emitting radionuclides. The main problem in this technique consists in the influence of the quench phenomenon, which finally causes a reduction in the counting efficiency. Conventionally, the correction of the efficiency requires the use of the appropriate quenched standards of the same radionuclide whose activity is to be determined. Whenever, adequate standards might not be available in the laboratory (e.g. when the activity of the short-lived radionuclides, for which standards are not normally available, is to be determined). This difficulty may be overcome using the 4πβ Liquid Scintillation Spectrometry Method with 3H-Standard Efficiency Tracing, known as CIEMAT/NIST method. To measure the activity of a certain beta-emitter, the method requires only to know the experimental counting efficiency of one tracer radionuclide (tritium is the most suitable) for different degrees of quench and to compute the theoretical counting efficiency both for tracer and radionuclide under study at the photocathode output for different values of a free parameter (called figure of merit), defined as mean number of photoelectrons per keV. The paper presents the results obtained in the implementation and validation processes of the CIEMAT/NIST method on a Packard TriCarb 2100TR Liquid Scintillation Analyzer, using as tracer the set of quenched tritium standards supplied along with the analyzer. The influence of quenching degree and level of activity has been studied using samples of known activity and the results were found to agree within ±2% with the beta activity.
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