Design of B 4 C-Doped Hematite Concrete Shield for Photon and Photo-Neutron Beams Emitted from 18 MeV-Linac using Monte Carlo simulation

A study was conducted to determine the gamma linear attenuation coefficient and total neutron macroscopic cross section (µ _𝛄 and Σ _n ) for concretes with different percentages of hematite and varying amounts of boron carbide (B ₄ C) addition for photon and photo-neutron beams emitted from 18 MeV Linear Accelerator (Linac) head. This study used the MCNPX code for gamma and neutron spectra of the Linac 18 MeV source. The concrete samples were then produced in a laboratory, and their compressive strength (CS) was measured. The Quality Index parameter (QI), which includes µ _𝛄 and Σ _n and CS, was used to compare the overall quality of the samples. The study identified the optimal point for the highest quality to identifying best type of combination for constructing the concrete shield. The study found that hematite had a high gamma absorption capacity due to its high atomic number and density. It also showed that the neutron’s total macroscopic cross section increased with increasing in the percentage of hematite. However, increasing the Σ _n stopped when the concentration of hematite in concrete exceeded 50%. The highest value of the concrete quality index was obtained for the samples containing 40–50% hematite. These samples can be used as an effective shield for radiotherapy room.