Design of a controllable Am-Be neutron source: A Geant4 simulation

Area of Science:

• Nuclear Engineering
• Radiation Physics
• Materials Science

Background:

• Neutron sources are crucial for various scientific and industrial applications.
• Existing Am-Be neutron sources often lack precise control over yield and safety features.
• Development of advanced neutron sources is essential for research and security.

Purpose of the Study:

• To design and develop a controllable Americium-Beryllium (Am-Be) neutron source.
• To incorporate a self-safety mechanism for enhanced operational security.
• To optimize the neutron source's geometry and performance characteristics.

Main Methods:

• A novel Am-Be neutron source design comprising AmO2, air, and Be layers within a stainless-steel tank.
• Control of neutron yield and safety achieved by adjusting the vacuum level of the intermediate air layer.
• Optimization of geometrical parameters, including layer thicknesses, using the Geant4 toolkit.

Main Results:

• Optimized layer thicknesses: 5 μm (AmO2), 3.4 cm (air), and 300 μm (Be).
• Achieved neutron yield of 5.61 n/10^6α at an air layer vacuum of 1 kPa.
• Maximum neutron flux of 4.122 × 10^3 n·cm^-2·s^-1 emitted from the Be layer for an Am-241 alpha activity of 9.313 × 10^9 Bq.

Conclusions:

• Successfully developed a controllable Am-Be neutron source with a self-safety structure.
• The vacuum-controlled air layer provides an effective mechanism for regulating neutron output and safety.
• The optimized design demonstrates significant potential for applications requiring adjustable neutron flux.