نشریه سنجش و ایمنی پرتو
سال پنجم شماره 1 (پیاپی 17، زمستان 1395)

In this paper design and simulation of an optimized accelerator tube is presented for the production of light charged particles up to energy of 2 MeV. Geometry of the accelerator tube electrodes was simulated based on the Van De Graaff accelerator tubes of Atomic Energy Organization by SIMION 7.0, Virtual Device and SIMION Toolkit codes. In accelerator tube, the extracted ion beam from the ion source is accelerated and converged thru the initial electrodes which each of the electrodes potential applied are slightly less than the former. Then, beam energy is increased by resemble acceleration electrodes and is guided to the target through drift tube. In this paper, we study beam dynamic in the simulated accelerator tube and effect of the different electrodes on the beam quality by features of the beam emittance criteria.

Nowadays, PGNAA applications in industrial, medicine, military,… are well known. A PGNAA system design requires simulations to determining some parameters, like gamma spectrum originated from shield, sample and surrounding materials, to ability, for example, to foreseen minimum detectable activity. Simulation codes use cross section libraries for calculating interaction probabilities and products. In this investigation, 16 important elements was selected and MCNPX-2.6 cross section libraries in 293.6°K compared for each of them by prompt gamma spectrum simulation in a PGNAA setting. Results showed differences among libraries. Correct libraries specified by comparing simulated prompt gamma spectra with reported experimental results or valid references.

Increasing growth of terrorist activities and threats to date and illegal transit of cargo led to the discovery and detection systems, have a lot of development. In this paper, to discovery and detection material has been used Prompt Gamma Neutron Activation Analysis (PGNAA) technique. Besides using simulated hypothetical system should also pay special attention to safety radiation and considerations related to the physics of health issues. If the amount of dose is relatively large, appeared deterministic effects and probable effects may occur at all radiation levels. Therefore, to determine allowable and protected region, to move personnel and public has been used ORNL-MIRDphantom. ORNL-MIRD Phantom provides analytical model of the human body. Calculation of doses in organs requests an exact description of the geometry of organs and the chemical constitution of tissues. At the available hypothetical system, the source and NaI detector has been used as neutron generator and emitted gamma receiver respectively. MCNPX2.7 code has been exploited to simulate neutron - photon transport in this system. Considering the details of the existing system to work with the system, protected region within a radius of 70 cm and the allowable region for radiographers were to 130 cm radius. Also the designed system is capable to detecting HMX explosive with weights of 158 gr and 501 gr at 10 and 1 minute respectively.

Thermal quenching is a known and important effect which should be taken into account in studying thermoluminescence (TL) phenomenon. This effect causes the probability of non-irradiative recombinations to be increased with raising temperature in TL process. This article deals with changes of the TL glow curve of LiF:Mg, Ti (TLD-100) with heating rates. It was observed that the fifth peak of this crystal is affected by thermal quenching. By increasing the heating rate, whilst the peak maximum shifts to higher temperatures, its intensity is also reduced. Also experimental data were fitted to the function describing the thermal quenching and related parameters for TLD-100 were obtained as W=1.66eV and C=3.965×1017

History and developing procedure of personal dosimetry services from start of film badge and TLD dosimetry services by legal authority as well as out sourcing of services presented in this article. Also results obtained from participation in regional intercomparisondosimetryprogramme (phases 1 and 2) planned by international atomic energy agency (IAEA) presented and discussed. Results of film badge and TLD shows that these methods meet the criteria of external dosimetry standards as well as acceptable uncertainty. Average ratio of measured dose to true dose for film badge was measured to be 1.17 and 1.03 in phase 1 and 2 respectively which shows theimprovement of the results.TLD shows a better results comparing to film badge, for which average of response measured to be 1.1 and 0.94 for phase 1 and 2 respectively.

The increasing use of wireless systems in educational and administrative environments has caused concern People working in these environments about the physical and psychological effects of the waves on health. This study was conducted to assess public exposure to microwave emissions intensity of the wireless system (Wireless) Qazvin University of Medical Sciences.
In this cross-sectional study, were measured the intensity of microwave radiation on 158 stations including the location of access points antennas, teachers room, meeting rooms, lecture classrooms, halls and nearby laptops in schools of Qazvin University of Medical Sciences. Wave intensity was measured using a wave control system (made in Spain) in accordance with standard procedures recommended by the National Institute of America IEEE C95.3. The effective intensity of exposure to microwave radiation emitted in the studied university was equaled to 0.121±0.437 μW/cm2 which was lower than the international exposure limits. Results also showed that there was a significant difference between the intensity of microwave with measurement points and Schools (pv

Recent studies suggest that relative biological damage (RBD) may change from in to out off field regions for 6 MV photon beams. In this study RBD was calculated in and out of field of 30x30 cm2 and 40x40 cm2 6 MV clinical photon beams including low energy slowing down electrons in track length estimated method. Varian 2100C/D linear accelerator was simulated using MCNPX code. Electron and photon spectra at energies higher than 2 keV were collected in a water phantom at different depths and off-axis points. New extrapolation method was used to estimate the electron spectra at energies lower than 2 keV. These spectra were used as an input to MCDS code to calculate the RBD of induced damage in DNA. There was an observable difference in the energy spectra for photons and electrons for points in the primary radiation field and those points out-of-field. RBD increases up to 10% for 10 MV photons in the out-of-field region. This work supports the hypothesis that in megavoltage treatments at the out-of-field, radiation quality can very enough to have an impact on RBD per unit dose.