Articles
Publication Date: 2025
Radiation Physics and Chemistry (0969806X)226
In this study, the instrumental neutron activation analysis (INAA) process has been simulated using Monte Carlo method in three steps at Isfahan Miniature Neutron Source Reactor (MNSR), and simulation results have been validated by experiments. The thermal neutron flux at the inner irradiation channel of the reactor and the effective multiplication factor (keff) of the reactor have been investigated by both Monte Carlo simulations and experiments. The Certified Reference Material (CRM) LKSD-4 geology sample has been irradiated in the inner irradiation channel for 60 s, and the gamma spectrum of the activated sample have been measured for 500s after52 s cooling time. The gamma spectrum has been obtained by the HPGe detector. The corrections related to the background spectrum and the detector resolution have been calculated and applied to the results. An experiment has been performed in the similar condition, and the results have been compared with the simulation. The results have showed an acceptable confirmation between experiment and simulation. This method can be used as an effective tool for prediction of the INAA procedure before performing the real analyze on the samples. © 2024 Elsevier Ltd
Publication Date: 2023
Radiation Physics and Chemistry (18790895)212
FLASH radiotherapy (or FLASH-RT) is a novel radiotherapy technology consisting of radiation delivery at dose rates several orders of magnitude higher (≥40Gy/s) than the currently used in conventional clinical radiotherapy. Many recent in-vivo preclinical studies indicate that FLASH-RT can greatly spare healthy tissues while maintaining unchanged tumour control. The generally acknowledged, though not entirely substantiated, explanation for the FLASH effect relates to the oxygen depletion that occurs after the radiation passage. On the other hand, oxygen depletion or, more in general, oxygen-related effects are still not fully clarified. Different research groups carried out the Monte Carlo simulations of electron and proton irradiations in oxygenated water to evaluate the oxygen-concentration-related effects at the cell-scale level. We analysed and compared the simulation results of the oxygen effect under the FLASH condition (considering the time-dependent G-values and the oxygen enhancement ratio-weighted dose) we obtained with GEANT4-DNA against TRAX-CHEM code results in the literature. Our results indicate that oxygen depletion has a negligible effect on radiosensitivity via oxygen enhancement, showing a close agreement with the TRAX-CHEM code. The conclusion is that the Geant4-DNA toolkit can be a valid instrument to study the FLASH effect. © 2023 Elsevier Ltd
Publication Date: 2023
Applied Radiation and Isotopes (09698043)193
In this study, the effects of irradiation by proton beam of a plasma focus device with 5 kJ discharge energy on photovoltaic (PV) cells were investigated. Before and after irradiation, the I–V curve of the cells was measured. Changes in Voc and Isc of silicon-type PV cells were recorded. After 1, 2, 4 and 8 shots, on average compared to the initial conditions, the voltage decreased by 76.81%, 76.70%, 84.94% and 83.74% respectively, and the current decreased by 43.18%, 54.91%, 67.49% and 58.07% respectively. The behavior of the plasma focus device was simulated by the LEE code, and the damage caused by the protons of the plasma focus device in each shot was evaluated by SRIM & TRIM software. For each shot of the plasma focus device, on average, about 3.82% of the atoms were displaced. The recovery time of the crystal structure, and the improvement of photovoltaic cells’ properties after irradiation were investigated experimentally. After 10 days of irradiation, the open circuit voltage of the cells that were irradiated by 1, 2 and 4 shots were increased by 22.81, 18.00 and 35.10%, respectively. Also, the short-circuit current of the cells were increased by 7.37, 8.91 and 27.89%, respectively. © 2023 Elsevier Ltd
