A thermal neutron source for the CERN radiation Calibration Laboratory

Area of Science:

• Nuclear Physics and Engineering
• Radiation Detection and Measurement
• Neutron Physics

Background:

• Existing Am-Be neutron sources require specialized equipment for calibration.
• Lightweight and cost-effective neutron assemblies are needed for radiation calibration laboratories.

Purpose of the Study:

• To design, construct, and characterize a novel thermal neutron assembly.
• To enhance the capabilities of the CERN radiation Calibration Laboratory (Cal Lab).

Main Methods:

• Utilized FLUKA Monte Carlo simulations for optimizing thermal neutron fluence.
• Experimental validation performed using a bare Helium-3 proportional counter.
• Designed a cylindrical moderator and an optional reflector box.

Main Results:

• Optimized thermal neutron fluence achieved at the exposure location.
• Fluence increased from 7.43 × 10^2 cm⁻²s⁻¹ (moderator only) to 5.75 × 10³ cm⁻²s⁻¹ (moderator + reflector box).
• Achieved a uniform thermal neutron fluence (<5% variation) within the exposure volume.

Conclusions:

• The developed thermal neutron assembly is lightweight, low-cost, and effective.
• The assembly significantly enhances thermal neutron fluence for detector calibration at CERN.
• The design provides a uniform and optimized neutron field for radiation measurements.