Standoff α-Radioactive Contamination Imaging via Enhanced Radioluminescence Detection

Alpha-emitting actinides pose critical environmental risks due to their high ionizing potential and potential for internal exposure via aerosol inhalation. However, conventional detection methods are constrained by the short attenuation length of α-rays (<5 mm in air), requiring direct contact with contaminated surfaces. Here, we present an advanced scanning methodology for standoff α-imaging by exploiting nitrogen-oxygen radioluminescence in air. A lens-coupled single-photon detection system was developed, integrating a Galilean telescope-optimized optical assembly with Monte Carlo-based numerical integration modeling to refine the mechanistic understanding of radioluminescence photon distribution in scanned images. Our innovation achieves a 328% enhancement in photon collection efficiency and reduces measurement time by 2.78 times through optimized optical design and Monte Carlo-driven signal calibration, enabled by the fully simulated 2D scanning system for radioluminescence imaging. More importantly, experimental validation using ²³⁹Pu sources demonstrates sub-1.5% relative error in mapping complex "C"-shaped contamination patterns through improved image reconstruction algorithms, with a spatial resolution of 0.031 m². The adaptive efficiency calibration algorithm further enables real-time quantification of surface activity under variable scanning angles by optimizing the translation from raw scan data to contamination maps, addressing critical limitations in nuclear emergency response by enabling rapid, non-contact contamination mapping, and establishes a framework for high-precision actinide monitoring in decommissioning scenarios.