10Be analyses with a compact AMS facility - Are BeF2 samples the solution?

Abstract

The injection of 10BeF- instead of 10BeO- into a compact accelerator mass spectrometry system with a terminal voltage of 0.58 MV was investigated, because BF- molecules are unstable and isobaric interference of 10B with 10Be can thus be significantly reduced. We describe the method we developed to prepare BeF2 samples. 10Be was measured in a segmented gas ionization detector. Separation of 10Be from 10B could be achieved both for ions in the 1+ charge state with an energy of 0.8 MeV and in the 2+ charge state with an energy of 1.4 MeV The 2+ ions are better separated, whereas the 1+ charge state has a higher transmission. 10Be/9Be ratios (∼10-12) in a suite of rock samples were successfully determined for exposure dating in either charge state and compared with measurements made on the 6MV tandem.