Heidelberg 2022 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 22: Search for Dark Matter 1

T 22.6: Vortrag

Montag, 21. März 2022, 17:35–17:50, T-H35

Radon removal system of the XENONnT experiment — •Denny Schulte, Henning Schulze Eißing, Philipp Schulte, Christian Huhmann, and Christian Weinheimer — WWU Münster

A novel high flux radon removal system has been built for the dark matter experiment XENONnT reducing the dominant electron recoil background produced by Rn-222 and its progenies. Continuous emanation from detector components and its half-life of 3.8 days leads to a homogenous distribution of the Rn-222 within the detector system before it decays. Our radon removal method is based on the vapor pressure difference of xenon and radon. We built a cryogenic distillation column with a throughput of 200 slpm to exchange the liquid xenon mass of 8.5 tonnes within one mean lifetime of Rn-222 in order to decrease the radon concentration by a factor 2. An additional extraction flow of 25 slpm from the xenon gas phase at the top of the XENONnT detector, where some specific radon sources were identified, demonstrated to provide an additonal radon reduction factor of nearly 2. Both reduction methods aim for reaching for the first time a radon activity concentration of 1 µBq/kg in a xenon-based dark matter experiment. To provide the enormous cooling power of more than 3 kW at about -100^∘C we use a heat-pump concept with custom-built, radon-free xenon compressors and heat exchangers.

This talk will focus on the principle, construction and commissioning measurements of the radon removal system.

The project is funded by BMBF under contract 05A20PM1.