Radon Daughter Plate-out onto Teflon

TL;DR

This paper investigates how radon decay products deposit onto Teflon surfaces in dark matter detectors, highlighting the significance of this contamination and exploring mitigation strategies to reduce background signals.

Contribution

It provides the first detailed analysis of radon daughter plate-out rates on Teflon and demonstrates mitigation techniques to minimize contamination in dark matter experiments.

Findings

Radon daughter plate-out rates on Teflon are significantly higher than on other materials.

Proximity to other materials can effectively reduce radon daughter deposition on Teflon.

Understanding plate-out mechanics is crucial for background reduction in dark matter detectors.

Abstract

Radiopure materials for detector components in rare event searches may be contaminated after manufacturing with long-lived $^{210}$Pb produced by the decay of atmospheric radon. Charged radon daughters deposited on the surface or implanted in the bulk of detector materials have the potential to cause noticeable backgrounds within dark matter regions of interest. Understanding the mechanics governing these background signals is therefore a paramount concern in dark matter experiments in order to distinguish a real signal from internal detector backgrounds. Teflon ($i.e.$ PTFE) is a specific material of interest because it makes up the walls of the inner detector of many liquid noble detectors such as the LUX-ZEPLIN experiment. The rate of radon daughter plate-out onto Teflon can be orders of magnitude larger than the plate-out rate onto other materials. Mitigation of plate-out onto Teflon and steel by proximity to other materials is demonstrated.