An Improved Passive CR-39-Based Direct ²²²Rn/²²⁰Rn Progeny Detector

Area of Science:

• Environmental Science
• Nuclear Physics
• Radiation Detection

Background:

• Radon (Rn) and thoron (Tn) are radioactive gases posing health risks.
• Accurate measurement of their progeny's equilibrium equivalent concentration (EEC) is crucial for radiation protection.
• Existing methods may require equilibrium factors, complicating measurements.

Purpose of the Study:

• To design and test an improved passive CR-39-based detector for direct measurement of ²²²Rn and ²²⁰Rn progeny.
• To establish a theoretical model for calculating EEC without the equilibrium factor.
• To validate the detector's performance against a theoretical model using chamber experiments.

Main Methods:

• Development of a CR-39 detector with 3 detection channels.
• Establishment of an optimized theoretical model for EEC calculation.
• Conducting exposure experiments to compare detector measurements with theoretical predictions.
• Analysis of energy-weighted net track density (NTD) in relation to time-integrated EEC.

Main Results:

• The improved detector accurately measures EEC for both ²²²Rn and ²²⁰Rn without equilibrium factors.
• The theoretical model showed good agreement with experimental data, particularly for progeny deposition flux.
• Energy-weighted NTD demonstrated a reliable linear relationship with time-integrated EEC.
• Detector performance is sensitive to environmental conditions, necessitating calibration.

Conclusions:

• The developed CR-39 detector offers a reliable method for direct EEC measurement of radon and thoron progeny.
• The validated theoretical model enhances the accuracy of EEC calculations.
• Calibration in typical indoor environments is recommended for optimal application of the detector for radiation monitoring.