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

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. continuous purification of the XENONnT inventory 8.4 tonnes at process flows up 71 kg/h (200 slpm) is required achieve a reduction by factor larger than two sources inside detector. To reach high flows, column’s design features inlet outlets along with novel custom-made bath-type heat exchangers liquefaction capabilities. The designed using modification McCabe–Thiele approach without bottom product extraction. thermodynamic concept Clausius–Rankine cooling cycle phase-changing medium, this case itself. drastically external power requirements, an energy efficient pump applying four cylinder magnetically-coupled piston compressor. operated thermodynamically stable conditions flow $$({91\pm 2})\,\mathrm{kg/h}$$ ( 91 ± 2 ) kg / h (( $$258\pm 6$$ 258 6 ) slpm), 30% over design. With flow, "Image missing" activity concentration $$<1\,\upmu $$ < 1 μ Bq/kg expected detector given measured source distribution.