Fitting methods for constructing energy-dependent efficiency curves and their application to ionization chamber...

Area of Science:

• Nuclear physics
• Metrology
• Radiation detection

Background:

• Accurate radioactivity measurements are vital in metrology.
• Ionization chambers serve as secondary standards for activity measurements.
• Characterizing detector efficiency is essential for quantitative analysis.

Purpose of the Study:

• To calibrate an ionization chamber for radioactivity measurements.
• To establish energy-dependent photon-efficiency curves.
• To develop a method for calculating radionuclide efficiencies.

Main Methods:

• Calibration of an ionization chamber using radionuclide activity standards.
• Determination of energy-dependent photon-efficiency curves with and without an iron liner.
• Calculation of radionuclide efficiencies using an analytical function and nonlinear regression (MS Excel).
• Inclusion of bremsstrahlung efficiencies from beta emitters.

Main Results:

• Energy-dependent photon-efficiency curves were established for the ionization chamber.
• Radionuclide efficiencies were calculated, showing agreement within a few percent for photon emitters.
• Bremsstrahlung efficiencies from beta emitters were calibrated to a 10% accuracy level.

Conclusions:

• The developed method provides accurate radionuclide efficiencies for photon emitters.
• The ionization chamber, with or without an iron liner, is suitable as a secondary standard.
• This work contributes to reliable radioactivity measurements in metrology.