Distribution of the ²²²Rn decay products from a ²²⁶Ra solution in a PTB ampoule--implications for calibration

Area of Science:

• Nuclear physics
• Radiochemistry
• Metrology

Background:

• Accurate measurement of radioactive sources is crucial for various applications, including calibration and research.
• Understanding the spatial distribution of activity within a sealed source is essential for precise dose calculations and simulations.
• Radium-226 ((226)Ra) is a commonly used radionuclide, but its complex decay chain and potential for radon gas production require careful characterization.

Purpose of the Study:

• To investigate the spatial distribution of (226)Ra activity in a flame-sealed PTB ampoule.
• To validate Monte Carlo simulation methods for modeling radioactive sources.
• To determine the radon partition ratio between solution and air phases within the ampoule.

Main Methods:

• Autoradiography was employed to visualize the spatial distribution of radioactivity.
• Well-collimated gamma-ray spectroscopy was performed on 23 distinct sections of the ampoule.
• Monte Carlo simulations using the GESPECOR code were conducted based on experimental observations.

Main Results:

• A complex and non-uniform activity profile of (226)Ra was observed within the ampoule.
• The GESPECOR code accurately reproduced the experimental efficiency transfer factors.
• The study determined the radon partition ratio in the solution-air phases as a byproduct.

Conclusions:

• The spatial distribution of activity in (226)Ra sources can be complex and significantly impacts simulation accuracy.
• Monte Carlo simulations, when informed by experimental data, provide reliable modeling of radioactive sources.
• This research contributes to improved metrology of (226)Ra sources and understanding of radon behavior in sealed systems.