Application of gamma ray scattering technique for non-destructive evaluation of voids in concrete

Gamma backscattering analysis of flaw types and orientation based on Monte Carlo GEANT4 simulations

In this study, we modeled the effects of flaws in a solid material as three different slit types (rectangular, rectilinear, and semicircular) and their orientations in a duralumin (aluminum alloy) plate in simulations based on 137Cs gamma backscattering. The simulations were performed using the Monte Carlo GEANT4 simulation toolkit. The simulation results showed that the shape of the slit had a small effect on the backscattering peak curve. Rotating the slit on the Y-axis and Z-axis of the duralumin plate influenced the 137Cs backscattering peak height in the energy range from 0.185 to 0.20 MeV, where the backscattering peak areas exhibited specific patterns due to the slit orientations.

Impact of focused gamma ray beam angle on the response of density logging tool

The response of the gamma-gamma density logging tool with different focused gamma ray beam angle is investigated by using the MCNP code. This work focuses on the four aspects of spatial distribution and energy spectrum of scattered gamma rays, measurement uncertainty, the depth of investigation, and vertical resolution of the logging tool. The results show that the density measurement accuracy can be improved when a relative larger collimator angle is employed, and the vertical resolution of the tool would not get worse.