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

Abstract

The injection of (super 10) BeF (super -) instead of (super 10) BeO (super -) into a compact accelerator mass spectrometry system with a terminal voltage of 0.58 MV was investigated, because BF (super -) molecules are unstable and isobaric interference of (super 10) B with (super 10) Be can thus be significantly reduced. We describe the method we developed to prepare BeF (sub 2) samples. (super 10) Be was measured in a segmented gas ionization detector. Separation of (super 10) Be from (super 10) B 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. (super 10) Be/ (super 9) Be ratios ( approximately 10 (super -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.