Development and Calibration of a Real-Time Airborne Radioactivity Monitor Using Gamma-Ray Spectrometry on a Particulate Filter

In this work, we present the development and calibration of a Real-time Airborne Radioactivity Monitor using gamma-ray spectrometry on a particulate Filter (RARM-F) to be used in an automatic environmental radiation surveillance network. The RARM-F collects a constant flow of air that passes across a particulate filter, where airborne aerosols are collected. Then, the filter is faced toward a NaI(Tl) or LaBr₃(Ce) scintillation detector that is used for gamma-ray spectrometry. This permits the identification and quantification of airborne radioactive isotopes in real time. The RARM-F was fully calibrated with a combination of experimental data and Monte Carlo simulations. For the simulations, a user code, including a model of the system geometry, was prepared for the EGS5 code system and validated with experimental measurements. The calibration methodology is independent of the scintillation crystal used; however, the measurement capabilities and the performance of the RARM-F are not. Thus, we also discuss some characteristics of the RARM-F when using different crystals.