جستجوی مقالات مرتبط با کلیدواژه "radiation safety" در نشریات گروه "فیزیک"

Having a portable and accessible radiation monitoring tool for members of the society, especially when faced with radiation caused by unwanted nuclear accidents, can provide a solution for radiation exposure monitoring. The monitoring is based on the sensitivity of CCD and CMOS semiconductor of smart mobiles to ionizing radiations. After receiving ionizing radiation such as gamma and X-rays, these sensors can receive the incident beam energy as a result of processes such as the photoelectric phenomenon and create charge carriers by creating ionization in the semiconductor medium of the sensor. The current resulting from the collection of charge carriers will result in the recording of bright (irradiated) and dark (unirradiated) spots on the camera sensor. Measuring the density of bright and dark points in the recorded images provides the possibility of estimating the amount of radiation exposure. In this research, four quality cameras and different brands were selected and dosimetry process for two sources of gamma radiation 60Co and 137Cs have been investigated.  The ratio of the total area of bright spots to the number of illuminated pixels per unit of time, which is proportional to the received dose, was measured and the calibration coefficient was determined for each camera. In the measurements made, the effect of time of death, resolution, stability and reproducibility have been checked and the necessary corrections have been applied. The obtained results show that for all the cameras used, there is a linear relationship between the recorded results and the received dose.

Physical inspection methods are not limited to metal detectors. Today, whole-body or part-body scanners are widely used in some countries. Body scanners are systems used to control people suspected of carrying weapons, explosives and narcotics embedded in body cavities at airports, prisons or other sensitive security and economic centers. At present, about 20 Soter-RS body scanners have been used in the country. The amount of dose received by the person being scanned with these devices is one of the most important aspects of their safety that is used in categorizing the device as well as determining the number of scans allowed for each person during a year. Of course, the justification for using such systems depends on the laws and regulations of each country. Studies and evaluations of body scanners in operation in the country show that the devices are in a limited-use range (Limited-use) but still with a limited number of scans recommended in the standard ANSI-43.17, the dose received by these people is less than the dose limit and the limited dose. Monitoring and evaluations show that the limit of the number of scans in accordance with the dose applied to the devices used in the country has been observed.

In this paper, a novel dual-band bandpass filter for the measurement and optimization of Wi-Fi waves exposure in the non-ionizing frequency range of 2.4 and 5 gigahertz, has been designed and simulated. In the novel proposed method for detection, initially the Wi-Fi waves have been filtered and then converted to the direct current signal in the detector. This filter consists of a complementary split ring resonator metamaterial and an interdigital capacitor which has been printed on a 50 ohms coplanar waveguide with the Rogers 3003 dielectric. In the equivalent circuit model of the bandpass filter, the complementary split ring resonator has been represented by a tank circuit which is in parallel with the coplanar waveguide. The interdigital coupling capacitor is in series with the waveguide. By adjusting the complementary split ring resonator radius and the interdigital capacitor length, the frequency of transmission poles of the filter can be tuned. The electromagnetic coupling mechanism in the components has been discussed. According to the results of the scattering parameters curve, the return loss at the transmission poles is more than 40 dB while the insertion loss in passbands is less than 0.3 dB.

In this paper, an experimental setup is used to measure the temperature dependence of the refractive index of a water phantom. In radiation calorimetry by laser beams and interferometric systems, the amount of change induced by radiation within the phantom can be accurately measured. Absorption of dose and the resulted change in temperature changes the refractive index within the material. In order to be able to measure the small amount of the absorbed dose within the phantom, the temperature dependence of the refractive index of the material must be precisely known. The measurement results of temperature dependence to the refractive index of water indicate the decrease of its refractive index by increasing the temperature.