A compact Rn-220 reference chamber with constant temperature and humidity.

Area of Science:

• Environmental Science
• Nuclear Physics
• Metrology

Background:

• Radon-220 (Rn-220) is a key radioisotope in radiation studies.
• Accurate calibration of radiation detection instruments requires stable reference sources.
• Existing Rn-220 sources may lack stability or compactness for certain applications.

Purpose of the Study:

• To design and develop a novel, compact Rn-220 reference chamber.
• To ensure stable environmental conditions (temperature and humidity) within the chamber.
• To establish a reliable Rn-220 source for radiation-related experimental studies and instrument calibration.

Main Methods:

• A 200 L stainless-steel cylindrical chamber was constructed.
• Thorium-doped lantern mantles were used as Rn-220 radioactive sources.
• Humidity was controlled using a supersaturated salt solution, and temperature was stabilized externally.
• Air mixing was achieved using a fan, and Rn-220 concentrations were monitored with a RAD7 detector.

Main Results:

• The chamber maintained stable conditions: 73 ± 3% relative humidity and 31 ± 1°C temperature.
• Rn-220 concentrations reached up to 166,700 ± 35,300 Bq m⁻³ with 36 mantles.
• The 9-mantle configuration yielded 47,700 ± 12,400 Bq m⁻³ with 26.0% uncertainty and minimal vertical variation, selected as the reference source.

Conclusions:

• A compact and stable Rn-220 reference chamber was successfully developed.
• The chamber provides controlled environmental conditions and high Rn-220 concentrations.
• This device is suitable for instrument calibration and various radiation research applications.