Heidelberg 2022 – scientific programme

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T: Fachverband Teilchenphysik

T 78: Experimental Techniques in Astroparticle Physics 3

T 78.3: Talk

Wednesday, March 23, 2022, 16:45–17:00, T-H37

Gaseous xenon measurements with APIMS and gas chromatography — •Veronica Pizzella and Hardy Simgen — Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117, Heidelberg

The latest generation of dual phase gas-liquid xenon TPC detectors for rare event searches employ several tonnes of xenon. It is crucial for the success of these experiments that the chemical impurities in LXe are below ppb level. Some chemical impurities of concern are: electronegative molecules such as oxygen, since they trap the electrons; radioactive impurities such as H-3, since they increase the background in the ROI.

In this presentation, a method to measure chemical impurities below ppb level is presented. The measurement is performed using Atmospheric Pressure Ionization Mass Spectrometry (APIMS), with a commercial instrument from Thermo Scientific. This instrument uses a corona discharge to ionize helium gas at atmospheric pressure, which in turn ionizes mixed trace impurities very efficiently. The setup uses a custom chromatography setup to separate the impurities from the xenon and mix them with helium. Some of the challenges of oxygen and hydrogen quantification are illustrated and some adapted solutions are outlined. A first measurement of the xenon from the gas phase of the XENONnT experiment is reported.