Monte Carlo based calibration of an air monitoring system for gamma and beta+ radiation

• A GEANT4 simulation is developed for the calibration of an air monitoring system.
• Correction for both gamma and beta+ emitters are obtained.
• Simulation results are compared with analytical self-attenuation correction factors.
• The estimated accuracy of the Monte Carlo technique is within 2%.

Marinelli beaker systems are used to monitor the activity of radioactive samples. These systems are usually calibrated with water solutions and the determination of the activity in gases requires correction coefficients accounting for the different mass-thickness of the sample. For beta+ radionuclides the different distribution of the positrons annihilation points should be also considered. In this work a Monte Carlo simulation based on Geant4 is used to compute correction coefficients for the measurement of the activity of air samples.