Application of ²⁵²Cf neutron source for precise nuclear data experiments

Area of Science:

• Nuclear Physics and Engineering
• Neutron Source Characterization
• Nuclear Data Validation

Background:

• Californium-252 (²⁵²Cf) is a key neutron source for various experiments.
• Precise characterization of ²⁵²Cf sources is essential for accurate high-precision experiments.
• Existing benchmark sets for neutronics studies can be expanded.

Purpose of the Study:

• To provide comprehensive information for experiments using ²⁵²Cf neutron sources.
• To characterize a specific ²⁵²Cf source, including its geometry and isotopic content.
• To investigate the use of cube-shaped materials as alternatives to spheres in neutronics benchmarks.

Main Methods:

• Detailed geometric modeling of the ²⁵²Cf source in MCNP6.
• Investigation of the influence of palladium matrix density on reaction rates.
• Measurement of fast neutron leakage spectra using a stilbene scintillation detector and comparison with MCNP6 simulations.

Main Results:

• The ²⁵²Cf source was confirmed to be volumetric and isotropic in experimental settings.
• Cube-shaped graphite benchmarks showed comparable results to spheres with lower production costs.
• Discrepancies were observed between MCNP6 calculations (ENDF/B-VII.1) and experimental data for neutron leakage spectra around 3.5 and 8 MeV.

Conclusions:

• The MCNP6 model is validated for ²⁵²Cf neutron leakage flux and reaction rate studies above 1 MeV.
• The study highlights the need for improved nuclear data, particularly around specific energy regions.
• The use of cube benchmarks offers a cost-effective extension to traditional spherical benchmarks.