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Published on: August 8, 2014
A new primary standardization of 229Th.
R Fitzgerald1, R Collé, L Laureano-Pérez
1Physics Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA. ryan.fitzgerald@nist.gov
Summary
The National Institute of Standards and Technology certified a thorium-229 standard using advanced anticoincidence counting. This ensures accurate radioactivity measurements for research and calibration.
Area of Science:
- Nuclear Metrology
- Radioactivity Standardization
Background:
- Accurate quantification of radionuclides is crucial for various scientific applications.
- Thorium-229 (229Th) is an important radionuclide with complex decay characteristics.
- Standard Reference Materials (SRMs) provide traceability for radioactivity measurements.
Purpose of the Study:
- To certify a high-purity 229Th Standard Reference Material (SRM 4328C).
- To establish accurate absolute activity and gamma-ray emission rates for 229Th.
- To improve the reliability of radioactivity measurements involving 229Th.
Main Methods:
- Live-timed 4π alpha-beta-gamma anticoincidence counting (LTAC) was the primary method for certification.
- Optimization of the LTAC system to minimize uncertainties from short-lived decay chain states.
- Confirmatory measurements using four independent methods were performed.
Main Results:
- Certification of 229Th SRM 4328C with high purity.
- Minimized uncertainty in absolute activity determination due to optimized LTAC.
- Obtained reliable gamma-ray emission probabilities by combining activity and emission rate data.
Conclusions:
- The certified 229Th SRM 4328C provides a reliable standard for radioactivity measurements.
- The optimized LTAC method enhances accuracy for radionuclides with complex decay chains.
- The study contributes to improved traceability and accuracy in nuclear metrology.
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