Intercomparison of gamma scattering, gammatography, and radiography techniques for mild steel nonuniform corrosion detection

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%.

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%.

A Recent Progress of Steel Bar Corrosion Diagnostic Techniques in RC Structures

Corrosion of steel bar is one of key factors undermining reinforced concrete (RC) structures in a harsh environment. This paper attempts to review the non-destructive procedures from the aspect of the corrosion measurement techniques, especially their advantages and limitations. Systematical classification of diagnostic methods is carried out to determine any probable corrosion issues before the structures become severe, and helps choose the suitable method according to different construction features. Furthermore, the three electrochemical factors method is introduced to inspire researchers to combine various techniques to improve corrosion evaluation accuracy. The recommendations for future work are summarized, in conclusion.

A method for determination mass absorption coefficient of gamma rays by Compton scattering

A method was proposed for determination mass absorption coefficient of gamma rays for compounds, alloys and mixtures. It is based on simulating interaction processes of gamma rays with target elements having atomic numbers from Z=1 to Z=92 using the MCSHAPE software. Intensities of Compton scattered gamma rays at saturation thicknesses and at a scattering angle of 90° were calculated for incident gamma rays of different energies. The obtained results showed that the intensity of Compton scattered gamma rays at saturations and mass absorption coefficients can be described by mathematical formulas. These were used to determine mass absorption coefficients for compound, alloys and mixtures with the knowledge of their Compton scattered intensities. The method was tested by calculating mass absorption coefficients for some compounds, alloys and mixtures. There is a good agreement between obtained results and calculated ones using WinXom software. The advantages and limitations of the method were discussed.

An improved Compton scattering method for determination of concentration of solutions

An improved Compton scattering method for determination of concentration of low-Z solutions is presented. The Monte Carlo (MC) numerical simulation of the scattering phenomena is done using the MCNP code. A unique non-linear extrapolation method is followed in correcting the scattered intensity for self-absorption and multiple scattering. The density ratios obtained using non linear extrapolated scattered intensity values are free from self-absorption and multiple scattering and agree well with the standard ones within experimental errors. The sensitivity study of transmission and scattering methods for determination of concentration of solutions having closer attenuation parameters at 661.6 keV is carried out to predict the range of effectiveness and suitability of these methods. The slopes (sensitivity/unit concentration) of the curves obtained from scattering method are higher by a factor of 1.26 compared to those of the transmission method in the measured range of concentrations.