Abstract

In measurements to detect defects inside the materials by gamma-scattered technique, the single scattering intensity was often noticed. However, the spectrum processing to determine single scattering intensities was time consuming, which was detrimental to quick tests. This study aimed to use the total scattering intensity to determine the thickness of the material. In experimental measurements, the total scattering intensity can be determined directly without spectrum processing, thereby shortening the sample inspection time. To calculate the thickness of the material, the total scattering intensity ratio R = Ix/IRef was used. A standard curve of R against the material thickness was built from simulation data using MCNP6. The gamma scattering measurement system used a NaI(Tl) detector, a radioactive source 137Cs, the scattering targets were steel pipes with an outer diameter of 273 mm, a scattering angle of 120o. Based on the standard curve of R, the thickness of the real steel pipes was ditermined by experimental gamma scattering. The results showed that the thickness of steel pipes was determined with a deviation of less than 4% compared to reality. In addition, the calculations also showed that the saturation thickness of steel for the total scattering intensity was significantly larger than that of the single scattering intensity, thereby extending the limit on the thickness of the samples to be measured.