A Radon Progeny Deposition Model

TL;DR

This paper develops a new model for radon progeny deposition on detector surfaces, crucial for reducing backgrounds in underground low-background experiments, based on experimental data from a controlled test stand.

Contribution

It introduces a novel deposition model for radon progeny that incorporates environmental factors previously unconsidered in existing models.

Findings

The deposition model accurately predicts progeny accumulation under various conditions.

Environmental factors significantly influence radon progeny deposition rates.

Experimental data validate the model's applicability for low-background experiment design.

Abstract

The next generation low-background detectors operating underground aim for unprecedented low levels of radioactive backgrounds. Although the radioactive decays of airborne radon (particularly Rn-222) and its subsequent progeny present in an experiment are potential backgrounds, also problematic is the deposition of radon progeny on detector materials. Exposure to radon at any stage of assembly of an experiment can result in surface contamination by progeny supported by the long half life (22 y) of Pb-210 on sensitive locations of a detector. An understanding of the potential surface contamination from deposition will enable requirements of radon-reduced air and clean room environments for the assembly of low background experiments. It is known that there are a number of environmental factors that govern the deposition of progeny onto surfaces. However, existing models have not explored the impact of some environmental factors important for low background experiments. A test stand has been constructed to deposit radon progeny on various surfaces under a controlled environment in order to develop a deposition model. Results from this test stand and the resulting deposition model are presented.