Hannover 2003 – wissenschaftliches Programm
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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.