De Corte F, Umans H, Vandenberghe D, De Wispelaere A, Van den Haute P. Direct gamma-spectrometric measurement of the 226Ra 186.2keV line for detecting 238U/226Ra disequilibrium in determining the environmental dose rate for the luminescence dating of sediments.
Appl Radiat Isot 2005;
63:589-98. [PMID:
15990322 DOI:
10.1016/j.apradiso.2005.05.008]
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Abstract
In the age determination of sediments according to the luminescence method, it is important to know whether there was secular equilibrium in the Th and U decay series during accumulation of the environmental radiation dose in geological times. This can be investigated via gamma-ray spectrometry, whereby--in the (238)U series--(214)Pb and (214)Bi are considered as the indicators for (226)Ra-mobility, and (210)Pb as the indicator for (226)Rn-emanation. In the present work, the direct measurement of (226)Ra--which can give extra information on the interpretation of the radioactive equilibrium--is investigated as to its precision and accuracy. Since there is a serious spectral interference on its 186.2keV gamma-line (by (235)U at 185.7keV), various correction procedures were outlined and their performance was checked via the analysis of (certified) reference materials, leading to the recommendation of a "method of choice".
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