Marked disequilibrium between ~(234)Th and ~(230)Th of the ~(238)U natural radioactive decay chain in IAEA reference materials n. 312, 313 and 314

摘要

A new laboratory for the spectroscopy of natural radioactivity with a good energy resolution is presented. It consists of two distinct parts equipped, respectively, the first one with a HpGe γ-ray detector, whose setup has been already completed, and the second one with large area Silicon α-ray detectors and a radiochemical section for thin a-samples preparation, whose setup is yet in progress and will be the argument of a separate work. The γ-ray spectrometer was calibrated by means of IAEA Reference Materials n. 312,313, 314 and 375. A large difference from the predictions of secular equilibrium emerged between the activities of ~(234)Th and ~(230)Th in Materials n. 312, 313 and 314.