Radiation Physics and Engineering
Volume:4 Issue: 4, Autumn 2023

Polycarbonate-bismuth oxide composite has been used as a beta-ray sensor in the previous works. Calculation of two main quantities namely stopping power and range of electrons in this material can be useful to evaluate the optimal thickness of the sensor. Thus, in this study, the range of electrons and stopping power of polycarbonate/bismuth oxide composite for several pure beta-emitters were estimated using the ESTAR program. Simulation findings indicated that the amount of concentration of the heavy metal oxide particles into the composite is an important factor to determine the range and stopping power of the electrons. Also, in the experimental phase, the response of the 50 wt% nanocomposite with thickness of 1 mm against the beta-rays of the P-32 source at the average energy of 695 keV in different activities was measured using an electrometer at a constant voltage of 800 V. Results showed that the response of the sample ranging from 4 to 6 mCi was linear with R2= 0.9757.

The neutron transmutation doping method is widely used in various fields, such as solar cells, hybrid cars, etc. The Silicon doping process can provide direct commercial income for nuclear research reactors. In this study, we aim to find the optimal location for silicon doping in the thermal column nose of the Tehran research reactor. For this purpose, computational MCNPX and ORIGEN2 codes were used to calculate the neutronic and radioactivity parameters of the silicon ingot. The important parameters such as the thermal to fast neutron ratio, heat deposition by gamma and neutron, and the radioactivity level of the silicon ingot and the produced radioisotopes have been determined to obtain the optimal irradiation channel. The results showed that the irradiation channel placed in the thermal column at a distance of 90 cm from the center of the TRR core has optimal conditions for the implementation of silicon doping. The channel provides a thermal neutron flux in order of 1.721012 n.cm-2.s‎-1‎ which is the least acceptable value to achieve a proposed neutron fluence during the operation cycles of TRR reactor. Also, the channel has the least possible heat deposition inside the silicon ingot of about 191 W. In addition, the thermal to fast neutron flux ratio of about 311 is enough higher than the determined IAEA limit for NTD.

High-energy heavy ions produced by accelerators are used in industrial and medical applications. Recently carbon ions have been used in the treatment of cancerous tumors. Heavy ions by the spallation process will activate the soft tissue components before tumors. In this research by GEANT4 toolkit and MCNPX code simulation were tried to calculate the secondary particles and radioactive elements produced in the soft tissue around tumors by the carbon ions spallation process. In the MCNPX code, the F8 tally card with the FT8 command was used to extract the activation and spallation information of secondary particles in the Z1=1 to Z2=25 atomic numbers range. It was shown that a wide range of radioactive elements was produced in healthy tissues in carbon therapy. addition to produced secondary particles, the Be-10 and C-14 radioactive elements were produced in high-energy carbon ions in soft tissue. Also, the GEANT4 toolkit result of produced secondary particles dosimetry was shown that the secondary particles dose per carbon ion is between 1.66 to 33.54 nGy for carbon ion energy between 1140 to 5160 MeV. The tail for 3480, 4080, and 5160 MeV of carbon ion energy are 0.12,1.01 and 11 cm respectively. The carbon ion beam divergence increases with beam energy and achieve to 33 mm for 5160 MeV carbon ion.

The present work is concerned on neutron flux increasing in Tehran Research Reactor (TRR). TRR is a 5 MW pool-type research reactor with plate type fuels in which the light water is used as both the coolant and moderator. The main goal of this paper is reaching to the average thermal neutron flux of the order of 1014 #/cm-2.s-1 in the central irradiation box. Combination of the TRR power upgrading with the compact core can enable us to reach a neutron flux higher than 1.5 × 1014 #/cm-2.s-1 without violating the neutronic and thermal-hydraulic safety criteria. The compact core, with 19 and 5 standard and control fuel elements respectively, is used as a base for the neutronic analyses. Compact core with 26 fuel assemblies fulfilled all neutronic and operation criteria. Considering thermal hydraulic aspect from previous study lets TRR to be upgraded to 8.5 MW, resulting in neutron thermal flux greater than 1.5 × 1014

Indirect drive inertial confinement fusion (ICF) holds promise for achieving practical energy generation through controlled fusion reactions. However, the efficiency of ICF is constrained by the Be ablator material used to contain the fuel. To overcome this limitation, researchers have proposed doping Be with various elements. In this study, we investigate the effects of Na and Br dopants, incorporated at concentrations of 4.86% and 2.1%, respectively, using a one-dimensional MULTI-IFE hydrodynamic code. This code serves as a numerical tool dedicated to analyzing Inertial Fusion Energy microcapsules, facilitating the examination of the Be ablator's performance in indirect drive ICF. Our results indicate that the addition of a beryllium layer doped with Na and Br significantly enhances the target gain, elevating it from the break-even value (G ≈ 1) to approximately G ≈ 12. Furthermore, we delve into the impact of these dopants on the plasma fuel conditions during the implosion, shedding light on the underlying physics of the system. These findings demonstrate that Na and Br doping in the Be ablator represents a viable approach for improving the efficiency of indirect drive ICF, potentially paving the way for the development of practical fusion energy systems.

Dielectric barrier discharge (DBD) plasma is used for various applications. DBD is also one of the most efficient and low-cost methods for active fluid flow control. In this study, a detailed physical model of DBD in atmospheric pressure at 1 kV DC voltage is developed with COMSOL Multiphysics software. Argon gas is also used as a background gas and electrodes are assumed to be copper. Plasma parameters such as electron and ion density, electric field, potential, and temperature for different gap distances of electrodes (1.0 mm, 0.9 mm, 0.8 mm) and different dielectric types (Quartz, Silica Glass, Mica). The results of the simulation show that the longitudinal distance of the grounded electrodes to the power electrodes has a direct influence on parameters such as electron temperature, and electron and ion density which are the main factors of fluid flow control. These parameters have the maximum value when Mica is used as a dielectric and the lowest value when Silica Glass is utilized.

By expanding the applications of GEM detectors, a newer pattern of such detectors was introduced in 2004, named THGEM detectors. In this work, a sample of an X-ray detector was designed and constructed using 2cm×2cm THGEMs domestically produced with a thickness of 250 μm, a hole diameter of 300 μm and a pitch of 500 μm, for the first time. The triple THGEM detector working in Ar/CO2 gas mixture was characterized. Influence of gas pressure and gas mixture on gain of the detector was investigated. Results show the detector operated in a stable mode with no discharges. The gain of the detector increased with high voltage across the THGEM electrodes exponentially. This verified the performance of a detector as a proportional counter. Also, the detector’s gain is maximum at Ar/CO2 (80/20) gas mixture and voltage of 700 V applied to each multiplier. The detector is promising for localization applications such as particle physics experiments.

In this research, the effect of deuterium beam energy distribution function resulting from TNSA and RPA mechanisms on the fast ignition of D/He-3 fuel pellet has been investigated. The fuel is irradiated with a deuterium beam through a conical guide. The energy distribution function will be different in different mechanisms. Penetration depth and stopping power of ignitor beam with mono- energy, Maxwellian and Gaussian distribution of energy are calculated. Calculations show that the Maxwellian beam from TNSA mechanism, penetrates up to about 100 μm in the fuel and the height of deposition peak is still in plasma corona. The height of the peak has also increased about 25 times compared to the case where the Gaussian beam is considered. Also, the obtained results are shown that the energy deposit of the deuterium beam resulting the RPA mechanism will be completely localized and will be more concentrated in the dense fuel core.