Design and Commissioning of the PandaX-4T Cryogenic Distillation System for Krypton and Radon Removal

TL;DR

This paper details the design, construction, and commissioning of a cryogenic distillation system for PandaX-4T that effectively reduces krypton and radon contaminants in xenon, enhancing dark matter detection sensitivity.

Contribution

It introduces a novel cryogenic distillation system capable of significantly reducing krypton and radon levels in xenon for dark matter experiments.

Findings

Krypton content reduced by 7 orders of magnitude

Radon reduction factor of about 1.8 achieved

Krypton concentration measured with an upper limit of 8.0 ppt

Abstract

An online cryogenic distillation system for the removal of krypton and radon from xenon was designed and constructed for PandaX-4T, a highly sensitive dark matter detection experiment. The krypton content in a commercial xenon product is expected to be reduced by 7 orders of magnitude with 99% xenon collection efficiency at a flow rate of 10 kg/h by design. The same system can reduce radon content in xenon by reversed operation, with an expected radon reduction factor of about 1.8 in PandaX-4T under a flow rate of 56.5 kg/h. The commissioning of this system was completed, with krypton and radon operations tested under respective working conditions. The krypton concentration of the product xenon was measured with an upper limit of 8.0 ppt.