Wilcken, KlausBarrows, TimothyFifield, L KeithTims, StephenSteier, P2015-12-080168-583Xhttp://hdl.handle.net/1885/29151The rare isotopes 236U and 239Pu are produced naturally by neutron capture in uranium ores. Here we measure 236U and 239Pu by accelerator mass spectrometry (AMS) in the same ore samples for the first time. To ensure efficient extraction of both elements and isotopic equilibrium between the 239Pu in the ore and a 242Pu spike, we developed a new sample preparation protocol. AMS has clear advantages over previous methods because it achieves better discrimination against molecular interferences with higher sensitivity and shorter counting times. Measurements of 236U and 239Pu hold considerable promise as proxy indicators of neutron flux and uranium concentration.Keywords: Mass spectrometry; Neutrons; Particle accelerators; Uranium; Isotopic equilibrium; Molecular interferences; Uranium concentration; Uranium ore; Radioisotopes 236U; 239Pu; AMS; Uranium ore200710.1016/j.nimb.2007.01.2102015-12-08