A radon emanation measurement system at the Carleton Noble Liquid Detector Laboratory

TL;DR

This paper describes the development of a radon emanation measurement system at COLD Lab to assess and reduce background contamination in rare event search experiments like Dark Matter and neutrino detection.

Contribution

The paper introduces a new radon detection system with specialized chambers and traps, enabling precise radon emanation measurements from materials and gases in low-background experiments.

Findings

The system effectively measures radon emanation from materials under vacuum.

It quantifies radon levels in nitrogen gas and residual radon in gas filters.

The radon counter is now calibrated and operational for background reduction.

Abstract

Radon is one of the most important sources of background in rare event search experiments, such as those searching for Dark Matter and neutrinos, due to its unavoidable production from natural uranium. In low-background experiments, radon emanation from detector materials and components accounts for a major portion of contamination. To investigate this, a radon detection system was developed at the Carleton nOble Liquid Detector Laboratory (COLD Lab). The setup consists of a stainless steel emanation chamber, a low-background ZnS(Ag) cell, and an assembly for radon transfer and collection. This setup was used to study radon emanation from materials under vacuum conditions. Additionally, a charcoal trap made of activated charcoal and equipped with a flow meter was constructed to study radon levels in nitrogen gas and the residual radon in the gas filter used in the DEAP-3600 processing system. The radon concentration in the glove box, where critical DEAP-3600 internal detector components were completed, was also calculated based on these measurements. Now calibrated and in-use, the COLD lab radon emanation counter is an essential diagnostic tool for reducing backgrounds in future rate-event search experiments.