https://doi.org/10.1140/epjc/s10052-022-11001-9
Regular Article - Experimental Physics
Design, construction and commissioning of a high-flow radon removal system for XENONnT
Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, Münster, Germany
a
michaelmurra@uni-muenster.de
b
DennySchulte@uni-muenster.de
Received:
25
May
2022
Accepted:
4
November
2022
Published online: 7 December 2022
A high-flow radon removal system based on cryogenic distillation was developed and constructed to reduce radon-induced backgrounds in liquid xenon detectors for rare event searches such as XENONnT. A continuous purification of the XENONnT liquid xenon inventory of 8.4 tonnes at process flows up to 71 kg/h (200 slpm) is required to achieve a radon reduction by a factor larger than two for radon sources inside the detector. To reach such high flows, the distillation column’s design features liquid xenon inlet and outlets along with novel custom-made bath-type heat exchangers with high liquefaction capabilities. The distillation process was designed using a modification of the McCabe–Thiele approach without a bottom product extraction. The thermodynamic concept is based on a Clausius–Rankine cooling cycle with phase-changing medium, in this case the xenon itself. To drastically reduce the external cooling power requirements, an energy efficient heat pump concept was developed applying a custom-made four cylinder magnetically-coupled piston pump as compressor. The distillation system was operated at thermodynamically stable conditions at a process flow of 
((
) slpm), 30% over design. With this flow, a 222Rn activity concentration 
Bq/kg is expected inside the XENONnT detector given the measured radon source distribution.
© The Author(s) 2022
Open Access
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