Determination of 227Ac in geological materials through neutron activation and alpha-spectrometric assay of induced 228Th

A new route has been developed for the micro-determination of 227Ac in geological materials by neutron activation. The method is based on intense neutron irradiation of the analysed samples followed by separation and α-spectrometric determination of 228Th, the β-decay product of the 6.1 hrs 228Ac isotope formed. Two alternatives are considered for analysis related to the origin of the analysed matrix. The high sensitivity of the method is documented by the determination of 10-17g 227Ac/g sample. The method is successfully applied for age determination of five uranium containing materials and old uranium glass from Bohemia, CSSR. (T.G.)