Radon Mitigation for the SuperCDMS SNOLAB Dark Matter Experiment

TL;DR

This paper discusses radon mitigation techniques for the SuperCDMS SNOLAB dark matter experiment, focusing on reducing radon daughters on detector surfaces through a specialized cleanroom with advanced radon reduction.

Contribution

It presents a validated simulation model of a vacuum-swing-adsorption radon mitigation system used in a cleanroom, enabling optimization for dark matter experiments.

Findings

Achieved over 1000x radon reduction in the cleanroom.

Radon levels measured below 0.067 Bq/m^3 at 90% confidence.

Validated simulation aligns with calibration data.

Abstract

A potential background for the SuperCDMS SNOLAB dark matter experiment is from radon daughters that have plated out onto detector surfaces. To reach desired backgrounds, understanding plate-out rates during detector fabrication as well as mitigating radon in surrounding air is critical. A radon mitigated cleanroom planned at SNOLAB builds upon a system commissioned at the South Dakota School of Mines & Technology (SD Mines). The ultra-low radon cleanroom at SD Mines has air supplied by a vacuum-swing-adsorption radon mitigation system that has achieved $>$1000$\times$ reduction for a cleanroom activity consistent with zero and $<0.067\,$Bq$\,$m$^{-3}$ at 90% confidence. Our simulation of this system, validated against calibration data, provides opportunity for increased understanding and optimization for this and future systems.