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.