Absolute activity determination of Au-198 solid source using 4 pi beta-gamma coincidence counting corrected by Monte-Carlo calculation

作者：Mo L^*; Wu H Y; Baldock C

来源：IEEE Transactions on Nuclear Science, 2007, 54(3): 677-683.

DOI：10.1109/TNS.2007.895504

• Au-198
• 4 pi beta-gamma
• coincidence-counting
• activity
• Monte Carlo simulation

For the commissioning process of the OPAL nuclear reactor of the Australian Nuclear Science and Technology Organization (ANSTO), the thermal neutron flux is measured through the activity measurement of an activated An wire, Au-Al (0.112% of An) alloy wire and An foil.
The absolute activities of Au-198 in the form of An wire, Al-Au wire and An foil were determined using the conventional 4 pi beta - gamma coincidence-counting method. Monte Carlo simulation technique was employed to simulate the complicated absorption and attenuation processes of electrons and gamma photon interactions with the surrounding materials. The Monte Carlo calculated probabilities of escape beta particles, internal conversion electrons and photon-interaction generated photoelectrons and Compton electrons were used to determine the correction term of the coincidence equation. The corrections for the An wire (length: 8.000 mm, radius: 0.064 mm), Al-Au wire (length: 7.690 mm, radius: 0.255 mm) and An foil (thickness: 0.025 mm, radius: 3.000 mm) were found to be 5.2% 0.1%,2.6% 0.1% and 4.2% 0.2% respectively. The study demonstrates that the Monte Carlo calculation for the correction term of the coincidence equation can be applied to the absolute activity determination of radionuclides with well-defined source geometries with an uncertainty of better than 1%.

• 出版日期2007-6
• 单位河北医科大学