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The recent emphasis on nanocomposites composed of polymers and metal oxides is largely due to their significant promise as effective radiation sensors, detectors, and dosimeters for gamma rays, X-rays, and charged particles. The sensitivity of a system may be affected by various factors, including the volume of the sensitive material, the concentration of heavy metal oxide nanoparticles, the bias voltage applied, and the degree of crystallinity within the polymer matrix. Studies have shown that a pronounced degree of crystallinity in polymers can restrict the homogeneous spread of nanoparticles. This research utilized two distinct polymer matrices, namely HDPE and PC, to create a nanocomposite that incorporated bismuth oxide nanoparticles at concentrations reaching 60 wt%. FESEM images revealed that PC exhibited better dispersion up to 60 wt%, while HDPE showed agglomeration at 40 wt%. Under a defined dose rate of 42.67 mGy.min-1, and with a fixed amount of Bi2O3 nano-fillers, the dosimetry response (measured as a change in electrical current) of PC was twice as pronounced compared to HDPE. Therefore, PC, as an amorphous polymer containing 50 wt% Bi2O3, may be considered a suitable candidate for dosimetry applications.

This research aims to determine and quantify the radiation shielding characteristics of High Density Polyethylene/Tungsten Oxide composite (HDPE/WO3) including the linear attenuation coefficient (µ), mass attenuation coefficient (µ/ρ), half-value layer (HVL) and tenth-value layer (TVL) for photons at various energies using Geant4, XCOM, and experiment. Thus, HDPE was chosen as the polymer matrix. Then, the samples at various concentrations of WO3 nanoparticles, including 0, 1, 2, 3, 4, 5, 6, and 9.5 wt%, different graphene oxide (GO) wt% namely 0, 0.25, 0.5, and 1 wt%, and linear low-density polyethylene (LLDPE) at 10, and 20 wt% were fabricated. NaI (Tl) scintillation detector was used to measure the shielding quantities using the 201Tl, and 99mTc sources at three energies of 135, 140, and 167 keV. The experimental results demonstrated that the addition of GO and LLDPE to the HDPE matrix resulted in a more uniform samples. Incorporating 20% LLDPE into the HDPE polymer matrix for the 99mTc resulted in an 18% rise in µ compared to pure HDPE. Finally, experimental results revealed a comparatively good agreement with the Geant4 and XCOM simulations.

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.

Sandwich panels are used in various industries due to their high special strength. It is used in ultra-light aerospace structures. In this paper the protective effect of sandwich structures used in ultralight space structures against gamma rays is investigated. Eight structures of the most widely used structures used in space structures such as telecommunication antennas and satellite bodies are exposed to radioisotopic sources of gamma rays (Amercium barium and cesium) with energies of 60 kV, 80 kV, 382 and 66 kV, have been compared to each other. Surface material (aluminum and carbon), surface thicknesses and honeycomb cell dimensions are the most important evaluation parameters. In this paper, different structures have been compared using the "special protection" parameter and the best structure from a protection perspective has been identified and reported.

Detection and dosimetry of ionizing radiation are important and fundamental issues in the nuclear industry. In this study, calculations related to the optimal thickness of a new beta detector for 90Sr source based on Polycarbonate/Bismuth oxide composite material (PC-Bi2O3) for different weight percentages of bismuth oxide fillers in polymer matrix, namely 0 wt%, 10 wt%, 20 wt%, 30 wt%, 40 wt% and 50 wt% were carried out using the ESTAR program. Results showed that the weight percentage of bismuth oxide particles was effective in determining the range and stopping power of the electrons in the composite detector. Finally, for 90Sr, using the evaluation of beta particles range in the aforementioned composite material, the optimal thickness for this detector was calculated.

In this study, calculations related to the mass attenuation coefficient (µ/ρ) of Polyethylene/Bismuth Oxide composite (HDPE-Bi2O3) for different weight percentages of Bi2O3 in the polymer matrix, namely 0 wt%, 1 wt%, 2 wt%, 3 wt%, 5 wt% and 8 wt% for photons with 59 keV energy that can be used in dental radiography centers were simulated using the MCNP code and results were compared with XCOM data. The simulation results of the mass attenuation coefficient of the composite in different weight fractions via the methods of MCNP and XCOM at 59 keV showed a good agreement with each other. The results of this study showed that the Polyethylene/Bismuth Oxide composite material in optimal weight fraction and thickness can be used as a radiation shield in dental radiography centers.

In the previous studies, a new type of gamma radiation dosimeter based on polymer/carbon nanostructures nanocomposite has been presented by the authors and also the dosimetric properties for this type of dosimeter have been investigated. In this experimental work, the electrical resistance of 0.28wt% Polystyrene/Multi-Walled Carbon Nanotube (PS/MWCNT) nanocomposite was measured at the temperature range of 25-75 °C. The work of a calorimeter is based on increasing the temperature of the sensitive volume due to irradiation. Results showed that with increasing the temperature, the electrical resistance of the nanocomposite was increased linearly and due to calorimetric relationships could be used as a calorimeter in the radiation processing region to measure the absorbed dose up to about 50 kGy.

In this experimental work, Polycarbonate/Bismuth Oxide (PC-Bi2O3) nanocomposites were prepared in various concentrations of 0, 10, 30, and 50 wt% with thicknesses of 1 mm and irradiated by a pure beta-emitter source of Sr-90. To fabricate the electrodes, copper sheets with thickness of 100 µm were attached to the top and bottom surfaces of the samples using the silver paste. Then, electric current as the dosimetry response, was measured at various dose rates ranging from 30-102 mSv.h-1 at a fixed voltage of 400 V using an electrometer. Results showed that increasing the Bi2O3 wt% led to improvement in the dosimetry response linearly at various dose rates. Also, the amounts of sensitivities for the samples of 0, 10, 30, and 50 wt% were measured as 20.3, 19.8, 28.6, and 36.7 nC.mSv-1.cm-3, respectively. Regarding the mechanism of beta interaction with a polymer-heavy metal oxide nanocomposite, the Bremsstrahlung radiation can be considered as a dominant effect.

Carbon nanostructures via adding to a polymer matrix, while improving the electrical, mechanical and optical properties of the nanocomposites, are widely used in the industry, medicine, and agriculture. The authors presented several investigations on a new type of gamma dosimeter based on the polymer-carbon nanostructures nanocomposite. In this research, the electrical percolation threshold of the Polystyrene-Graphene Oxide nanocomposite (PS/GO) was simulated using the finite element method in different weight percentages. Then, at the experimental phase, various nanocomposites were fabricated in different weight percentages of 0.05, 0.1, 0.5, 1, 2, 3, 5 and 8 via the mixed-solution process. The electrical conductivities of the samples were measured at the room temperature. Finally, the electrical conductivities of the nanocomposites were compared using the FEM simulation and the experimental results, which were estimated as 2.5wt%. The results of this study showed that the finite element method in accordance with the experimental results is a powerful tool to determine the electrical properties of the polymer nanocomposites considering the dosimetric approaches.

‎Collision of protons with background gas and beamline wall in proton therapy causes the creation of secondary particles‎, ‎e.g. neutrons‎, ‎which results in more difficulties in curing the tumors‎. ‎In the present simulation-based study‎, ‎the optimum diameter of proton beamline was determined to minimize the production of secondary particles in the presence of electric field with the magnitude of 50 kV/m‎, ‎perpendicular equal magnetic fields of 0.7 T‎, ‎and background gas of argon under Bounce boundary conditions via finite element method‎. ‎The results showed that the optimum diameter of the beamline for minimization of the secondary particles in the spot scanning proton therapy in the aforementioned conditions was 7 mm‎. ‎Also‎, ‎the values of drift velocities of protons were plotted in different time steps of 10 ns to 50 ns for the optimized size of the beamline‎. ‎Due to few interactions of forwarding particles with background gas‎, ‎the results showed that the forwarding particles in the propagation direction have greater velocities than those of rear particles‎. ‎The results can be used in spot scanning proton therapy for curing the localized cancers‎.

Recently, polymeric nanocomposites have been used as real-time detectors and dosimeters of gamma radiation. In this experimental work, multi-wall carbon nanotubes (MWCNT) were dispersed in polystyrene (PS) martix with a weight percentage of 0.05 wt%. SEM images confirmed the appropriate and uniform distribution of carbon nanotubes in the polymer matrix. The dark current and photocurrent of the nanocomposite were measured under gamma irradiation of 60Co source using an electrometer in the voltage region of 1-500 V, and the dose rate range of 40-134 mGy/min. The results showed that this dosimeter in the array form of 2 pieces in comparison with the 1 and 3 pieces show a better response in the mentioned dose-rate and voltage ranges. Thus, this nanocomposite can be used as an active dosimeter in the diagnostic and therapeutic level.

Recently, polymeric nanocomposites have been used in dosimetry and detection of gamma rays, but due to their low photon absorption cross section, they exhibit a small sensitivity to gamma rays. In order to overcome this problem, metal oxide particles with a high atomic number are added to the polymer matrix. For this purpose, in this work, tungsten oxide particles (WO3) were distributed in polyvinyl alcohol (PVA) matrix via two scales of nano and micro sizes of the fillers with a weight percentage of 20 wt%. A solvent solution was used in fabricating WO3-PVA composite (20 wt%). The FESEM test was performed to verify the composite rheology and to confirm the distribution of tungsten oxide micro/nanoparticles in the polymeric matrix. The quantum efficiency of gamma rays for 60Co was calculated for the aforementioned composite using the MCNP code, which showed an acceptable agreement with the XCOM results. One of the effective factors in detection response and dosimetry of this composite group is the change in the electrical current of the composite due to beam absorption. The dark current and photocurrent of tungsten oxide-polyvinyl alcohol nano/micro composite were measured in gamma and neutron radiation fields respectively by 60Co and 241Am-Be sources using two-probe electrometer in 100 V and 400 V voltages. The results showed that the sensitivity of nanocomposite to gamma rays is better than microcomposite. Also, the signal-to-noise ratio of nanocomposite for gamma-ray in the dose rate of 90-138 mGy/min increased linearly from 5 to 40, while the composite did not show a remarkable response to neutron beams.

Use of carbon nanotubes (CNTs) in dosimetry is a promising technique for real time in vivo dose measurements with high resolution for nuclear medicine and also dose rate monitoring for radiation protection utilizations. In this research with respect to extraordinary electrical properties of CNTs for several order of magnitudes increasing in electrical conductivity of polymeric matrix, the idea of application of polymer-CNT composite is introduced. One of the effective factors in the response of this kind of dosimeter is electrical conductivity variation due to radiation absorption. In this research, we simulated electrical conductivity of polyethylene-CNT composite with COMSOL Multiphysics software in different weight percentages of CNTs and then percolation threshold for two kinds of geometries random and array was evaluated and compared with Bruggeman Symmetric Equation. The results of simulation showed that the application of COMSOL software for evaluating effective electrical conductivity of PE-CNT composite is suitable for dosimetry purpose.