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MS: Fachverband Massenspektrometrie
MS 5: Poster
MS 5.8: Poster
Dienstag, 11. März 2025, 17:30–19:00, Foyer Physik
AMS for long-lived cosmogenic radionuclides in stony meteorites - Now without chemical preparation — •Silke Merchel, Oscar Marchhart, Martin Martschini, Alexander Wieser, and Robin Golser — University of Vienna, Faculty of Physics, Austria
Long-lived radionuclides in meteorites are a result of the interaction with cosmic rays. These cosmogenic nuclides (CNs) record the history of extraterrestrial matter. Reconstruction parameters of interest are: 1. pre-atmospheric size and shielding depth of the body in space (meteoroid); 2. irradiation time in space; 3. identification of complex exposure, i.e., repeated collisions or inherited CNs from pre-exposure at the surface of the meteoroid’s parent body (asteroid, Moon, Mars); 4. residence time on Earth (terrestrial age). Accelerator mass spectrometry (AMS) is the preferred method for the detection of CNs such as 10Be, 14C, 26Al, 36Cl, and 41Ca (t1/2 = 6 ka – 1.4 Ma). However, tedious radiochemical separation to deplete matrices and isobars has been essential for AMS preventing rapid analysis until recently. Now, the unique Ion-Laser InterAction Mass Spectrometry (ILIAMS) system at the Vienna Environmental Research Accelerator provides isobar suppression of up to 14 orders of magnitude. Thus, ILIAMS-assisted AMS, allows the direct detection of 26Al/27Al (∼10−10) and 41Ca/40Ca (∼10−11) in stony meteorites containing intrinsic ∼1% Al and Ca. Isobars of the naturally-abundant elements (∼15% Mg, ∼0.1% K) do not interfere, making radiochemical separation redundant. Recent examples are the German and Austrian meteorite falls of Elmshorn, Ribbeck (Bischoff et al., MAPS 2024a/b) and Kindberg.
Keywords: AMS; cosmogenic nuclide; meteorite