Advanced gamma spectrum processing technique applied to the analysis of scattering spectra for determining material thickness

Thickness measurement of material plates using low-activity sources with various energies in gamma-ray transmission technique

This study proposes an approach based on the gamma-ray transmission technique to accurately determine the thickness of material plates using a low-activity source. For this purpose, we have set up an experimental configuration without collimators for both source and detector. Besides, a Monte Carlo simulation model using MCNP6 code has been created with the same geometric parameters as the empirical one. The calibration curves of thickness measurement were constructed for various energies of the incident gamma rays in the range of 123-661.7 keV and two materials of aluminum and copper using Monte Carlo simulation data. The thickness of the material plate was determined by applying experimental data to a known calibration curve. For a given material and gamma energy, the measurable thickness range (MTR) was estimated by investigating the dependence of the expected relative error on the thickness of the material plate. The obtained results show that the approach is feasible with the relative deviation between the measured and reference thicknesses of mostly less than 2% and the relative uncertainty of less than 3%. Such an approach could suggest a practical and cost-effective evaluation tool for optimizing the configuration to achieve a given accuracy corresponding to each type of material.

A study on the sensitivity of the measurement of liquid density at different scattering angles using a gamma scattering technique

This study aims to evaluate the sensitivity of the measurement of liquid density at different scattering angles using a gamma scattering technique. To perform this, the linear calibration curves of the ratio R (R is the ratio of the area under a single scattering peak for a liquid relative to that for water) versus the liquid density were constructed at different scattering angles. The sensitivity of the measurement is defined as the slope coefficient of these linear calibration curves. The results obtained from the Monte Carlo simulation data showed that the sensitivity of the measurement at different scattering angles including 70°, 80°, 90°, 100°, 110°, 120°, 130°, and 140° changes in the range from 0.44 to 0.48. Also, the results obtained from the experiment when performing the measurements at scattering angles of 90°, 100°, 110°, and 120° ranged from 0.46 to 0.48. This confirms that the dependence of the sensitivity of the measurement on scattering angle is insignificant. Besides, for every experimental dataset, we used each of 8 above-obtained calibration curves, in turn, to determine the densities of 8 liquids which yield the relative deviation between the measured density and the reference one is mostly less than 5%, the relative deviation of remaining cases (64 of 256 measurements) is in the range of 5.0%-9.9%.

ANN coupled with Monte Carlo simulation for predicting the concentration of acids

The present study proposes a new approach for determining the concentration of acids. The method is based on the combination of Monte Carlo simulation and artificial neural network (ANN) technique for predicting the concentration of acids. Firstly, a Monte Carlo simulation model is validated based on the comparison of simulation data with experimental data. Then, the whole data derived from the Monte Carlo simulation using the MCNP code was used to train the ANN model. The trained ANN model was used to predict the percentage concentrations of 14 acid samples, which yields the maximum relative deviation between the predicted and the reference concentrations is less than 3.5%.

Determining the density of liquid using gamma scattering method

This study proposes an approach to determine the density of a liquid based on the gamma scattering method. The liquids used to determine density were poured in a cylindrical tube. This approach requires that the ratio R (the ratio of area under a single scattering peak for a liquid to that for water) increase linearly with an increase in the density of the liquid. In a certain range of density, a linear relationship was obtained between the ratio R and density, as described by a linear calibration curve with coefficients of slope and intercept, for the investigated tube diameters. In particular, the values of the slope and intercept could be expressed as mathematical functions of the diameter of the tube. For a given tube, the coefficients of slope and intercept of the linear calibration curve were obtained based on these functions, which helped determine the density of the liquid. The reliability of the proposed approach was evaluated by using it to calculate the densities of five liquids-n-hexane, diethyl ether, acetonitrile, toluene, and glycerol-using tubes with inner diameters of 1.8 cm, 2.25 cm, and 2.68 cm. The results show that the maximum relative deviation between the reference and the measured densities was 4.3%.

Semi-empirical method for determining the density of liquids using a NaI(Tl) scintillation detector

In this study, we developed a new method for determining the density of liquids using the Compton backscattering technique. The principle of this method is based on the change in the area under a single scattering peak versus the liquid density. The linear calibration curve of the ratio R versus the density is required to determine the density of an unknown liquid (R is the ratio of the area under a single scattering peak for a liquid relative to that for water). In the proposed method, the calibration curve is completely constructed based on a simulation using the MCNP5 code. The method involves combining a simulation with an experiment as a semi-empirical method. Using this method, we determined the density of four liquids comprising acetonitrile, glycerol, nitric acid, and sulfuric acid, and the maximum deviations between the reference densities and measured values were less than 1.4%, except in the case of sulfuric acid, which was approximately 4.5%. The results obtained in this study strongly suggest that the proposed method is suitable and feasible for application.

Optimization of the Monte Carlo simulation model of NaI(Tl) detector by Geant4 code

This work aimed to optimize the Monte Carlo simulation model of NaI(Tl) detector by Geant4 code. For detector modeling, the geometrical parameters are usually derived from the manufacturer's specification because of availability and convenience. However, the difference between real and nominal values in geometrical parameters of the detector can considerably affect the simulation results. To overcome this problem, a complete procedure for optimizing the geometrical parameters of the detector was proposed in this study. The results showed a good agreement between the simulated and experimental values, and the maximum discrepancy between the experimental and simulated values was 3.96%, 1.69%, and 3.50% for full-energy peak efficiency, energy resolution, and peak to Compton ratio, respectively.