In low-background particle physics experiments, surface deposition of radon progeny presents a significant background challenge. To characterize this contamination, a high-sensitivity surface α-activity measurement system was developed, which employs a 3×3 Si-PIN array operating in vacuum to perform α-spectroscopy on samples. The system was calibrated using Poly(Methyl MethAcrylate) (PMMA) plates exposed to a controlled high-radon atmosphere, achieving an energy resolution of 2.09 \% for 5.30~MeV α particles and a one-day measurement sensitivity of 1.27~μBq/cm2 for 210Po surface activity. Using this system and a self-built high radon concentration chamber, the deposition behavior of radon progeny on PMMA surfaces was investigated. Results indicate a non-monotonic dependence on exposure time, a significant enhancement of deposition with increasing negative surface electrostatic potential, and a strong modulation by ambient humidity. This paper details the apparatus design, calibration, and experimental study of radon progeny deposition dynamics on PMMA surfaces.
@article{arxiv.2603.00647,
title = {Precise Measurement and Control of Radon Progeny on Detector Surfaces},
author = {C. B. Z. Luo and C. Guo and L. P. Xiang and Y. H. Niu and F. G. Mo and J. C. Liu and Y. P. Zhang and C. G. Yang},
journal= {arXiv preprint arXiv:2603.00647},
year = {2026}
}