Development of ²²²Rn Emanation Sources with Integrated Quasi 2π Active Monitoring.

Area of Science:

• Nuclear Physics
• Metrology
• Environmental Science

Background:

• Standardization of low-level radon-222 (²²²Rn) emanation is crucial for environmental monitoring and radiation protection.
• Existing methods may lack the temporal resolution or traceability required for accurate measurements.

Purpose of the Study:

• To present a novel approach for the standardization of low-level ²²²Rn emanation.
• To develop a technique enabling continuous monitoring of residual ²²²Rn with high temporal resolution and SI traceability.

Main Methods:

• Integration of a ²²²Rn source (²²⁶RaCl₂) with an alpha-particle detector (Si-diode) using thermal physical vapor deposition.
• Continuous collection and analysis of alpha-particle spectra for statistical inversion to derive emanation.
• Characterization of detection efficiency using defined solid-angle alpha-particle spectrometry for SI traceability.

Main Results:

• The developed technique achieves high temporal resolution due to low background and high counting efficiency.
• Radon emanation shows a dependence on relative humidity (up to 15% between 20% and 90% rH).
• SI-traceable emanation values with a combined standard uncertainty not exceeding 2% were achieved for release rates from 1 to 210 ²²²Rn atoms per second.

Conclusions:

• The novel technique provides a reliable method for standardizing ²²²Rn emanation.
• This approach enables the realization of reference atmospheres for typical environmental ²²²Rn levels.
• It significantly improves the realization and dissemination of activity concentration units for ²²²Rn in air.