SAMOP 2021 – wissenschaftliches Programm
MS 8.5: Vortrag
Donnerstag, 23. September 2021, 15:00–15:15, H3
Low-level 166mHo measurements with AMS for the ECHo-project — •Georg Rugel1, Sebastian Berndt2, Christoph E. Düllmann2,3,4, Holger Dorrer2, Oliver Forstner5,6, Tom Kieck2,7, Nina Kneip2,7, Johannes Lachner1, Silke Merchel1,8, Carlos Vivo-Vilches1, Anton Wallner1, and Klaus Wendt7 — 1Accelerator Mass Spectrometry and Isotope Research, Helmholtz- Zentrum Dresden-Rossendorf, Dresden — 2Department of Chemistry, Johannes Gutenberg University, Mainz — 3GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt — 4Helmholtz Institute Mainz, Mainz — 5Friedrich-Schiller-University Jena — 6Helmholtz Institute Jena, Jena — 7Institute of Physics, Johannes Gutenberg University — 8Isotope Physics, Faculty of Physics, University of Vienna, Vienna, Austria
The Electron Capture in 163Ho experiment (ECHo) aims at measuring the mass of νe by analysing the EC spectrum of the long-lived radionuclide 163Ho (T1/2=4570 a) with a metallic magnetic calorimeter (MMC). For the determination of a reasonable upper limit for the neutrino mass it is mandatory to keep any contamination with the long-lived radionuclide 166mHo nine orders of magnitude below the 163Ho content. The ion-implantation of ultra-pure 163Ho into a MMC for the experiment is carried out by the RISIKO mass separator. The separation from 166mHo, however, cannot be quantified to such low levels as needed. Here we present our approach to determine the corresponding low isotopic ratio with accelerator mass spectrometry (AMS). This requires the formation of negative ions, we find the highest negative ion yield for the anion HoO2−. For first tests 165Ho was implanted by RISIKO in various metal foils and we obtained results for the Ho detection efficieny. This allows for extrapolations for the expected measurement limit of the 166mHo/163Ho ratio.