Nuclide analysis of a tantalum target irradiated with high-energy protons

Abstract

First results of γ-spectrometric measurements of radionuclides produced in a tantalum target irradiated for 500 days with 800 MeV protons are presented. The activities of the γ-ray-emitting nuclides measured after a cooling period of 2–4 years differ by more than four orders of magnitude. Within this cooling period about 95% of the activity of the target is determined by¹⁷²Lu,¹⁷³Lu,¹⁷⁴Lu,¹⁷²Hf (daughter nuclide of¹⁷²Lu) and¹⁸²Ta nuclides. These highly active nuclides, together with some other medium-active nuclides, were measured with good precision by γ-ray spectrometry directly in the sample solution. Weakly active nuclides could not be measured in this way because of the high Compton background in the γ-ray spectrum. For the sensitive measurement of many other nuclides present in weaker activities a simple chemical separation procedure was developed to separate Lu, Hf and Ta. With the separation of these elements and simultaneously of the high-active nuclides, the Compton background in the γ-ray spectra could be drastically reduced and many weakly active nuclides additionally measured.