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Updated: Aug 9, 2026
10:42
Preparing an Isotopically Pure 229Th Ion Beam for Studies of 229mTh
Published on: May 3, 2019
NIST 222Rn emission standards
1National Institute of Standards and Technology, Gaithersburg, MD 20899-0001, USA. peter.volkovitsky@nist.gov
Summary
New NIST radon standards utilize polyethylene capsules containing radium-226. Measurements confirm calculations accounting for radon diffusion into the capsule walls, providing key data on radon solubility and diffusion in polyethylene.
Area of Science:
- Radiochemistry
- Metrology
- Materials Science
Background:
- National Institute of Standards and Technology (NIST) prepares radon standards for accurate radioactivity measurements.
- Polyethylene capsules are used as containers for radium-226 solutions in these standards.
- Understanding radon behavior within the capsule material is crucial for standard accuracy.
Purpose of the Study:
- To prepare and characterize new series of NIST radon standards.
- To investigate the emanation fraction and radon behavior within polyethylene capsules.
- To determine the solubility and diffusion coefficient of radon in polyethylene.
Main Methods:
- Preparation of new NIST radon standards with activities of 5, 50, 500, and 5000 Bq.
- Measurement of the emanation fraction from the standards.
- Calculation of radon accumulation within the polyethylene capsule walls.
- Determination of radon solubility and diffusion coefficient in polyethylene.
Main Results:
- New series of NIST radon standards were successfully prepared.
- Measured emanation fractions align with calculations considering radon diffusion into polyethylene.
- The solubility of radon in polyethylene was determined to be approximately 45% of its solubility in water.
- The diffusion coefficient of radon in low-density polyethylene was found to be 7.2x10⁻⁸ cm²/s.
Conclusions:
- The characterization of new NIST radon standards validates the methodology for accounting for radon diffusion.
- The determined physical properties of radon in polyethylene are essential for improving radon metrology.
- These findings contribute to the accuracy and reliability of radioactivity measurements using radon standards.
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