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MS: Massenspektrometrie

MS 1: Beschleunigermassenspektrometrie

MS 1.3: Vortrag

Montag, 24. März 2003, 14:30–14:45, F 428

¹⁰ Be measurements with terminal voltages below 1 MV — •Michal Grajcar¹, Max Döbeli², Peter W. Kubik², Colin Maden¹, Martin Suter¹, and Hans A. Synal² — ¹Institute of Particle Physics, ETH-Hönggerberg, CH-8093 Zürich, Switzerland — ²Paul Scherrer Institut, c/o ETH-Hönggerberg, CH-8093 Zürich, Switzerland

At the AMS laboratory in Zürich, the potential for ¹⁰ Be detection is presently being explored with the existing 1-SDH Pelletron facility. Using charge state 2 ⁺ , an energy of about 1.5 MeV and a transmission of about 13 % is obtained. A stack of 7 carbon foils (20 µ g/cm ² ) has been placed between the high-energy analysing magnet and the electrostatic deflector. With this dE/dx foil technique, a boron suppression of about 3 orders of magnitude has been achieved. In addition, the ¹⁰ B interference has been suppressed by another 5 orders of magnitude with a Δ E-E _R gas ionisation chamber. The total background suppression is thus at least 8 orders of magnitude. For samples prepared by converting to BeO, this corresponds to a background ¹⁰ Be/ ⁹ Be ratio of about 10 ⁻¹² . The IsoTrace group in Toronto suggested the use of BeF as sample material instead of BeO. Extracting BeF ⁻ molecules from the ion source seems to reduce the ¹⁰ B fraction in the beam by about 5 orders of magnitude in comparison to extraction of BeO ⁻ . The potential of this alternative technique is also discussed.