Determination of227Ac in geological materials through neutron activation and alpha-spectrometric assay of induced228Th

A new route has been developed for the micro-determination ofAc 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 ofTh, the β-decay product of the 6.1 hrsAc 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 gAc/g sample. The method is successfully applied for age determination of five uranium containing materials and old uranium glass from Bohemia, CSSR.