Field calibration studies for ionisation chambers in mixed high-energy radiation fields

Area of Science:

• Radiation physics
• High-energy physics
• Radiation detection and measurement

Background:

• Monitoring ambient doses in mixed radiation fields near accelerators presents challenges.
• Centronics IG5 ionisation chambers are used at CERN for radiation exposure monitoring.
• Calibration is typically performed using standard photon and neutron fields for ambient dose equivalent H*(10).

Purpose of the Study:

• To assess the accuracy of conventionally calibrated ionisation chambers in mixed high-energy radiation fields.
• To investigate the relationship between ionisation chamber readings and ambient dose equivalent in complex fields.
• To explore the potential for 'field calibration' using Monte Carlo simulations.

Main Methods:

• Utilized the CERN-EU high-energy reference field facility.
• Assessed spectral fluence for each particle type using Monte Carlo simulations.
• Conducted measurements in a controlled radiation area near a beam loss point at CERN's proton synchrotron.

Main Results:

• Demonstrated reasonable agreement between measurements and Monte Carlo simulations for most exposure conditions.
• Indicated that conventionally calibrated ionisation chambers often provide satisfactory ambient dose equivalent measurements.
• Highlighted the importance of knowing spectral response and field composition for accurate assessment.

Conclusions:

• Conventionally calibrated ionisation chambers can be effective for monitoring stray radiation at high-energy accelerators.
• Monte Carlo simulations are crucial for understanding detector response in complex radiation fields.
• These findings support the development of 'field calibration' methods for radiation protection instruments.