Measurements of Beta Ray Emitters in LSC Using Efficiency Tracing CIEMAT/NIST Method

摘要

The main impediment in liquid scintillation counting (the most suitable technique for the quantitative analysis of the β-emitting radionuclides) is the influence of quench phenomenon, which causes a reduction in the counting efficiency. Usually, the correction of the efficiency due to quenching requires the appropriate quenched standards of the same radionuclide whose activity is to be determined, but these might not be readily available. To overcome this difficulty, a relative or tracing method, such as 4πβ Liquid Scintillation Spectrometry Method with 3 H-Standard Efficiency Tracing (also known as CIEMAT/NIST method) may be used. The paper presents the results obtained in the implementation and validation processes of this method on a Packard TriCarb 2100TR LSA (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.