Comparison and improvement of the determinations of actinide low activities using several alpha liquid scintillation spectrometers

We applied three procedures using two or liquid scintillation spectrometers (PERALS and TRI-CARB) and two scintillation cocktails (Alphaex and Ultima Gold LLT) for the determination of a-emitter low activities. For each proce dure, the limit of detection, the resolution, the separation factor, and th e Fischer coefficient were determined in order to perform U-232-U-234-U-238 isotopic measurements. The deconvolution usually performed is clean when t he PERALS spectrometer is used. This is not possible for the TRI-CARB spect rometer using the Ultima Gold LLT scintillation cocktail. This problem was solved by combining the advantages of both techniques using the Alphaex sci ntillation cocktail in the TRI-CARB spectrometer, Under these conditions, t he limit of detection was improved, the resolution decreased from 500-800 t o 420-590 keV, and the separation factor increased from 0.9 to 1.1-1.2. Thi s third procedure was applied with success for U-232-U-234-U-238 isotopic e xperiments.