Design, construction and commissioning of a high-flow radon removal system for XENONnT

M. Murra; D. Schulte; C. Huhmann; C. Weinheimer

doi:10.1140/epjc/s10052-022-11001-9

2023 Impact factor 4.2

Particles and Fields

Open Access

Eur. Phys. J. C (2022) 82: 1104
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

M. Murra^a, D. Schulte^b, C. Huhmann and C. Weinheimer

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

Abstract

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 $(91 \pm 2) kg / h$ $({91\pm 2})\,\mathrm{kg/h}$ (( $258 \pm 6$ $258\pm 6$ ) slpm), 30% over design. With this flow, a ²²²Rn activity concentration $< 1 μ$ $<1\,\upmu$ Bq/kg is expected inside the XENONnT detector given the measured radon source distribution.

© The Author(s) 2022

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