Abstract
Abstract
The PandaX-4T distillation system, designed for the removal
of krypton and radon from xenon, is evaluated for its radon removal
efficiency using a 222Rn source during the online distillation
process. The PandaX-4T dark matter detector is employed to monitor
the temporal evolution of radon activity. To determine the radon
reduction factor, the experimental data of radon atoms introduced
into and bypassed the distillation system is compared. The results
indicate that the PandaX-4T distillation system achieves a radon
reduction factor exceeding 190 at the flow rate of 10 slpm and the
reflux ratio of 1.44. Gas-only online distillation process of a flow
rate of 20 slpm is also conducted without observing significant
reduction of radon levels in the detector. This observation suggests
that the migration flow of radon atoms from the liquid phase to the
gas phase is limited, and the flow rate of gas circulation and
duration of the process are insignificant compared to the total
xenon mass of 5.6 tons in the detector. This study provides the
experimental data to support the efficient removal of radon at
∼Bq level using the PandaX-4T distillation system, which is the
prerequisite of the radon background control in the detector. The
further operation with higher flow rate will be applied for the
upcoming science run in PandaX-4T.