Online $^{222}$Rn removal by cryogenic distillation in the XENON100 experiment

TL;DR

This paper presents a cryogenic distillation method integrated into the XENON100 detector to effectively reduce radon-222 background, improving the detector's sensitivity for rare event searches.

Contribution

The study demonstrates the successful implementation of an online cryogenic distillation process for radon removal in a large-scale xenon detector, achieving a radon reduction factor of over 27.

Findings

Radon reduction factor R > 27 (95% C.L.) achieved

Cryogenic distillation effectively reduces radon background

Enhanced detector sensitivity for rare events

Abstract

We describe the purification of xenon from traces of the radioactive noble gas radon using a cryogenic distillation column. The distillation column is integrated into the gas purification loop of the XENON100 detector for online radon removal. This enabled us to significantly reduce the constant $^{222}$Rn background originating from radon emanation. After inserting an auxiliary $^{222}$Rn emanation source in the gas loop, we determined a radon reduction factor of R > 27 (95% C.L.) for the distillation column by monitoring the $^{222}$Rn activity concentration inside the XENON100 detector.