182Hf, a new isotope for AMS

The neutron-rich isotope Hf-182 with its half-life of 9 +/- 2 million years was alive in the early solar system and has been used to study the early development of the Earth and the Moon through isotopic anomalies of its stable decay product W-182. In addition, Hf-182 may also complement a few other radionuclides in the million-year half-life range to trace relatively recent stellar events with high neutron fluxes in the vicinity of the Earth. This may be accomplished by finding measurable traces of live Hf-182 in suitable terrestrial archives. With accelerator mass spectrometry (AMS) it should be possible to detect minute amounts of Hf-182. We will show that the main interference for the detection, the stable isobar W-182, can be significantly reduced by using HfF5- ions. The AMS detection method of Hf-182 and first results from Hf control rods of a recently retired research reactor are presented, which encourage us to search for naturally produced traces of Hf-182 on Earth. (C) 2004 Elsevier B.V. All rights reserved.