Monte Carlo simulations of response functions for gas filled and scintillator detectors with MCNPX code

Design of an on-line monitoring system based on a 3He detector

In this study, a neutron monitoring system based on a cylindrical ³He detector was designed and simulated using MCNPX code for the nuclear laboratories that use neutron sources for educational and research purposes. According to the simulation results, the monitoring system was experimentally tested with different moderators. Finally, using experimental and simulation results, a monitoring system with appropriate efficiency was built based on the considered detector and, its efficiency was measured in different conditions. The test results show that this system can measure the background radiation of the laboratory environment efficiently.

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.