First intercomparison of ²⁴¹Am activity measurements using primary methods including magnetic micro-calorimetrers

Area of Science:

• Nuclear Metrology
• Applied Physics
• Radiochemistry

Background:

• Magnetic Micro-calorimeters (MMCs) are emerging low-temperature detectors with potential for primary radionuclide activity standardization.
• Validation of MMC measurement techniques is necessary due to their relatively novel application in metrology.
• Americium-241 (²⁴¹Am), an alpha-particle emitter, is suitable for intercomparison due to its standardization via multiple established methods.

Purpose of the Study:

• To conduct an intercomparison of activity measurements between Magnetic Micro-calorimeters (MMCs) and conventional primary methods using ²⁴¹Am.
• To validate the performance of MMCs in radionuclide standardization against well-established techniques.
• To identify challenges and areas for improvement in MMC-based activity measurements.

Main Methods:

• Preparation of a specialized ²⁴¹Am source via electro-precipitation, compatible with both MMC spectrometry and traditional methods.
• Measurement of the ²⁴¹Am source by four metrology institutes (LNE-LNHB, CIEMAT, CHUV, PTB) using diverse primary standardization techniques.
• Subsequent division of the source into secondary sources for multi-channel MMC spectrometer analysis.

Main Results:

• Activity measurements were performed using MMCs, and results were compared with those from conventional techniques across participating laboratories.
• Reported uncertainties were in the range of a few percent, attributed to the low activity of the source and potential activity loss.
• This initial intercomparison provided valuable data and highlighted opportunities for refining MMC measurement protocols.

Conclusions:

• The intercomparison demonstrated the feasibility of using MMCs for radionuclide activity measurements, albeit with current limitations.
• Further optimization of source preparation and measurement procedures is needed to reduce uncertainties in future MMC applications.
• This study serves as a foundation for future validation exercises and the broader adoption of MMCs in primary standardization.