جستجوی مقالات مرتبط با کلیدواژه « Monte Carlo Simulations » در نشریات گروه « فیزیک »

A portable body counter detects internal contamination in an emergency. Monte Carlo code estimates minimum detection activity (MDA) for a portable whole-body counter. In the case of outdoor open fields, natural background radiations were simulated. This counter has a chair geometry equipped with a NaI (Tl) detector (5cm x 5cm) inside a lead shield collimator consisting of a set of lines and a continuous component with monenergistic γ sources ranging from 300 to 2000 keV at intervals of 100 keV. This data matrix is folded with the measured spectrum outside the setup to estimate the observed spectrum in the detector. We evaluated the variation of the detector flux transmitted through the lead collimator and chair shield. This was done at different lead densities and different photon energies. Computational data were used to estimate the monitoring system MDA. This method is cheaper to design and test a counter system for low-level counting of γ emitting radionuclides than experimental methods

In this research, using Geant4 Monte Carlo simulation tool, we have investigated the shielding properties of aluminum oxide, magnesium fluoride, aluminum fluoride, titanium dioxide, magnesium diboride, magnesium silicide, calcium disilicate, and Fluental in the energy range of 0.015 to 10 𝑀𝑒𝑉. In this review, we have calculated and analyzed the linear attenuation coefficient (LAC) and mass attenuation coefficients (MAC), half-value layer (HVL), tenth value layer (TVL), mean free path (MFP), and effective atomic number, effective electron density, equivalent atomic number and buildup factor. In the continuation of the work, we have compared the calculated results of mass attenuation coefficient by Geant4 Monte Carlo simulation tool with the experimental results of others and with the simulation data by XMuDat code, and they have a very low relative error and are in good agreement with each other. Finally, the results obtained for the selected materials are shown in appropriate figures.

Among the approaches commonly used to extend the sharp peak of the deposited dose in proton therapy, passive scattering is widely used and also is of concern because of the potential for generating secondary particles, especially neutrons, which can damage the non-target healthy tissues. The present simulation-based study investigates the effect of using the passive method for different primary proton energies on the dose delivered to the tissue compared with those of the pencil beam scanning method. The results show that the generation of secondary neutrons strongly depends on the material used in the beam design. Also, it was found that the passive method would lead to the physical neutron dose higher than that of the beam scanning method for various primary proton energies.