Research on Measurement of ¹⁸²Hf with HI-13 AMS System

Abstract: ¹⁸²Hf with half-life of about (8.90±0.09) Ma is an extinct radionuclide and can only be produced by a supernova explosion in nature. Therefore ¹⁸²Hf is an ideal candidate nuclide for the study on possible supernova explosions in the vicinity of the earth within the last 100 million years. In addition, ¹⁸²Hf is a long-lived radionuclide of particular interest for nuclear engineering. Accurate measurement of ultra-trace ¹⁸²Hf is very important for reactor design，studies on nuclear cosmo-physics and other fields. With an accelerator mass spectrometry (AMS), it is possible to detect the trace amounts of ¹⁸²Hf. In this paper, the detection method of ¹⁸²Hf with HI-13 AMS system at China Institute of Atomic Energy (CIAE) and the chemical procedures to reduce ¹⁸²W interference are presented. The energy and TOF two-dimension spectra of ¹⁸²Hf and ¹⁸³W for blank and a series of standard samples have been obtained, respectively. The ¹⁸²W contribution to the counts in ¹⁸²Hf peak was corrected by ¹⁸³W normalization. The detection sensitivity of this AMS facility for ¹⁸²Hf/¹⁸⁰Hf ratio measurement is about 4.15±10^－11 at present.