The evaluation of the 1001.03 keV gamma emission absolute intensity using fundamental parameter method

Area of Science:

• Nuclear physics
• Radiochemistry
• Analytical chemistry

Background:

• Accurate determination of Uranium-238 (238U) is vital for nuclear material and environmental monitoring.
• The 1001.03 keV gamma-ray transition of Protactinium-234m (234mPa) is a key indicator for 238U quantification.
• Previous absolute intensity values for this transition have varied widely (0.59-1.12%), leading to potential inaccuracies.

Purpose of the Study:

• To re-evaluate the absolute intensity of the 1001.03 keV gamma-ray transition of 234mPa.
• To establish a more accurate value for improved 238U activity concentration determination.
• To address the discrepancy and potential overestimation associated with commonly used intensity values.

Main Methods:

• Utilized the Fundamental Parameter Method (FPM) in various modes.
• Employed diverse sample types including uranium ore and granite.
• Investigated different sample-to-detector geometries and gamma-ray spectrometers for comprehensive analysis.

Main Results:

• The re-evaluated absolute intensity is 1.067 ± 0.084%.
• This new value shows an average relative bias of -20% compared to the commonly used value of 0.847 ± 0.008%.
• The findings indicate that the previously accepted value likely leads to an overestimation of 238U activity concentration.

Conclusions:

• The re-evaluated absolute intensity provides a more accurate basis for 238U determination.
• This improved accuracy is critical for reliable nuclear material accounting and environmental monitoring.
• The study highlights the importance of precise gamma-ray intensity data in nuclear measurements.