Heidelberg 2022 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 22: Search for Dark Matter 1

T 22.5: Vortrag

Montag, 21. März 2022, 17:20–17:35, T-H35

Towards an automated krypton assay in xenon at the ppq level — •Robert Hammann, Hardy Simgen, and Steffen Form — Max-Planck Institut für Kernphysik, Heidelberg, Germany

The beta-decaying isotope ⁸⁵Kr is one of the main internal background sources of liquid xenon (LXe) detectors. With purification techniques, it is possible to reduce the concentration of krypton in xenon below 100 ppq (parts per quadrillion). To model the background contribution of the remaining ⁸⁵Kr, it is crucial for low-background experiments such as XENONnT to precisely quantify the concentration of krypton in the detector material. The rare gas mass spectrometer (RGMS) at MPIK Heidelberg can meet this requirement by measuring the krypton concentration of an extracted xenon sample in two steps: First, krypton is separated from the bulk of xenon using a cryogenic gas chromatographic system. Then, the amount of krypton is analyzed using a mass spectrometer. A fully automatic rare gas mass spectrometer (AutoRGMS) is envisaged for the krypton assay of future low-background LXe detectors. This instrument will considerably facilitate the time-consuming measurement procedure, thus enabling a more frequent krypton monitoring. In addition, larger adsorption traps with a novel adsorbent will be employed, which makes the system sensitive to lower krypton concentrations. A proof of concept was demonstrated with a test setup of an automated gas chromatographic system in which stable conditions were maintained for more than 10 hours during the separation process. Moreover, the setup was used to test individual components and to find a working point for AutoRGMS.