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

Abstract

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 g-ray detector, whose setup has been already completed, and the second one with large area Silicon a-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 g-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 234Th and 230Th in Materials n. 312, 313 and 314.