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The miniaturization of computer facilities conditioned by the miniaturization of applied components makes them very sensitive to radioactive radiation. This is where neutron and electromagnetic radiation come to the fore. The reason for the particularly pronounced effects of this radiation is the fact that they do not interact with the Coulomb force, so they pass (leave) the reactor vessel unimpeded. This study examines the reliability of magnetic and semiconductor computer memories in the field of neutron and gamma radiation. This study experimental, and conducted under well-controlled conditions. The combined measurement uncertainty of the experimental procedure is less than 5 %. Sophisticated methods of mathematical statistics were used to process the stochastic results of measurements.

The research presents an experiment with a model of an electronic generator for energy injection into the plasma of a fusion reactor. By recording a non-ionizing field in the vicinity of a fusion reactor, it was determined that this field has an extremely high growth rate. At the site of the maximum intensity of the field of non-ionizing radiation, commercial surge arresters with a flexible model of surge arresters were used for experimentation. It has been found that the commercial surge arresters have an efficiency of about 20%. For the efficiency of the flexible model, it was found to be slightly less than 40% (and to be achieved by the application of alpha particle radiation). Since neither of these efficiencies guarantee reliable operation of the gas-filled surge arrester, it was concluded that essential electronics in the vicinity of the fusion generator must be protected. However, since this protection can only be implemented in a fusion reactor, the fact remains that the environment of such a reactor is extremely contaminated with non-ionizing radiation. Commercial surge voltages are isolated for testing since the protection of electronic circuits from fast overvoltages is a critical point for the functioning of modern electronics.

This study considers the possibility of applying natural isotopes of water, tritium, and oxygen 18O, to analyze the connection between groundwater, surface, and precipitation waters. This analysis also enables the determination of the age of groundwater, separated from the cycle of water circulation in nature. Based on these methods, it is possible to reliably determine, by chronologically accurate method, the possibility of industrial application and application for human needs of the waters of this aquatorium.

The waters of two lakes and two streams that dominate in the Šar Mountains aquatorium were analyzed. The tritium profile of soil was also recorded. All samples were taken at approximately the same time, together with samples of precipitation. During the period of taking samples, the ambient temperature conditions were taken into account for ten days around the time of sampling. Monitoring of the seasonal maximum with taking into account the obtained tritium soil profile and the temperature on and around the day of sampling unambiguously showed that all tested water in the Šar Mountains aquatorium is of atmospheric origin and as such unsuitable for any major transformation for commercial purposes. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 171007]

The paper discusses the possibility of improving the character of gas surge arresters. Examined were: the magnetic field effect, the effect of the hollow cathode, and the effect of the alpha radiation source 241Am. Numerical and real experiments conducted are presented together with theoretical interpretations of the obtained results. Real experiments were carried out on a model of a gas surge arrester spatially constructed for experiments presented in this paper. The model was designed in such a way that it was possible to change all the relevant parameters of the gas surge arrester model. Experiments were conducted under well-controlled laboratory conditions. The tests were performed with d. c. and impulse voltage. The results obtained by experiments were processed by sophisticated statistical methods. The expressed measurement uncertainty of the experimental procedure showed a high statistical reliability of the obtained results. Based on the results of the research, the model of a gas surge arrester, in which the effect of the hollow cathode and the radioactive source 241Am were combined, unambiguously proved to have the best characteristics.

In this paper, the procedure for determination of the mean value of non-homogenous background radiation and the expression of measurement uncertainty is considered. The background radiation is described using the Student's distribution, and the measurement uncertainty using the Welch-Satterthwaite equation. The proposed algorithm was experimentally verified under well-controlled laboratory conditions and satisfactory results were obtained. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 171007]

This paper discusses the possibility of applying the F-test and double t-test in problems related to the identification of number of radioactive isotopes in a contaminated area by using only counters for radiation detection. The descriptions of the F-test and the double t-test are given along with the corresponding tabular values that enable their implementation. Finally, the experiment is presented via two radioactive samples. The results of the experiment were treated in the manner proposed in the paper and satisfactory results were obtained. [Projekat Ministarstva nauke Republike Srbije, br. 171007]

Positron emission tomography is a technology that provides unique and exquisite possibilities in functional diagnostics, in the sense that it is the most efficient and most reliable method for obtaining information about biochemical activity and cellular metabolism in the body, by determining exact localization and performing semi-quantitative assessment of the distribution of a radioactive tracer. This paper compares the characteristics of recently introduced lutetium based crystals to those of conventionally used bismuth-ortho-germanate scintillators; both options are used as scintillation detectors within the positron emission tomography systems. Energy resolution and scintillation decay time of lutetium based crystals and bis-muth-ortho-germanate crystals was experimentally tested. Main scintillation detector parameters which affect the resulting detector response are considered and analyzed, since they serve as the basis for a positron emission tomography medical image. [Projekat Ministarstva nauke Republike Srbije, br. 171007]

The operation of power lateral pnp transistors in gamma radiation field was examined by detection of the minimum dropout voltage on heavily loaded low-dropout voltage regulators LM2940CT5, clearly demonstrating their low radiation hardness, with unacceptably low values of output voltage and collector-emitter voltage volatility. In conjunction with previous results on base current and forward emitter current gain of serial transistors, it was possible to determine the positive influence of high load current on a slight improvement of voltage regulator LM2940CT5 radiation hardness. The high-current flow through the wide emitter aluminum contact of the serial transistor above the isolation oxide caused intensive annealing of the positive oxide-trapped charge, leading to decrease of the lateral pnp transistor's current gain, but also a more intensive recovery of the small-signal npn transistors in the control circuit. The high current density in the base area of the lateral pnp transistor immediately below the isolation oxide decreased the concentration of negative interface traps. Consequently, the positive influence of the reduced concentration of the oxide-trapped charge on the negative feedback reaction circuit, together with the favourable effect of reduced interface traps concentration, exceeded negative influence of the annealed oxide-trapped charge on the serial pnp transistor's forward emitter current gain.

The main objective of this study was to estimate the environmental and health risk of the Šar Mountains (Kosovo) for depleted uranium contamination. The risk assessment of the contamination is needed since, in the spring of 1999, conflict with bombarding took place in the territory of the Western Balkans, during which depleted uranium ammunition was used. In Serbia and Montenegro, such tests were performed; based on them, some territories were decontaminated. Šar Mountains is particularly important as it is one of the few water-rich areas in Kosovo. Therefore, soil and water samples were taken from characteristic places in the Šar Mountains aquatorium. Tests of the samples were performed under well-controlled conditions. The measurement uncertainty was less than 5%. Based on the obtained results, it was concluded that there was no contamination of the Šar Mountains with depleted uranium. This conclusion can be extended to the broader area around the Šar Mountains, as it is a safe area surrounded by high mountains. [ABSTRACT FROM AUTHOR]

Based on the principles derived from Campbell’s theorem, this paper carries out an analysis of the possibilities of Campbell’s mean square value signal processing system. The mean square value mode is especially suitable for measurements performed in a mixed radiation field, because the quantities of electrical charge involved in the interactions of the two types of radiation are substantially different. The measuring detector element may be an adequate ionization chamber and/or semiconductor components for mixed n-γ fields. An examination of the discrimination of gamma in relation to the neutron component in the signal of the detector output was carried out, calculated according to the theoretical model of radiation interaction with the detector. The advantage of the mean square value method was confirmed and it was concluded that the order of n-γ discrimination in mean square value signal processing is greater than the one rendered by the classical measuring method.

A method of on-line monitoring of the low-dropout voltage regulator's operation in a radiation environment is developed in this paper. The method had to enable detection of the circuit's degradation during exploitation, without terminating its operation in an ionizing radiation field. Moreover, it had to enable automatic measurement and data collection, as well as the detection of any considerable degradation, well before the monitored voltage regulator's malfunction. The principal parameters of the voltage regulator's operation that were monitored were the serial pnp transistor's base current and the forward emitter current gain. These parameters were procured indirectly, from the data on the voltage regulator's load and quiescent currents. Since the internal consumption current in moderately and heavily loaded devices was used, the quiescent current of a negligibly loaded voltage regulator of the same type served as a reference. Results acquired by on-line monitoring demonstrated marked agreement with the results acquired from examinations of the voltage regulator's maximum output current and minimum dropout voltage in a radiation environment. The results were particularly consistent in tests with heavily loaded devices. Results obtained for moderately loaded voltage regulators and the risks accompanying the application of the presented method, were also analyzed.

This paper investigates possible radiation effects in the Cooper-pair insulator state of indium oxide films. Radiation effects are predicted on the basis of Monte Carlo simulations. Results of a combined theoretical and numerical analysis suggest that radiation-induced changes in the investigated films could significantly affect their current-voltage characteristics, and that a transition to a metallic state is possible, due to radiation-induced disruption of the fine-tuned granular structure. Dissociation of Cooper pairs, caused by both the incident radiation and the ions displaced within InOx films, can also destroy the conditions for this specific insulating state to subsist.

This paper is a summary of broadband measurement values of radiofrequency radiation around GSM base stations in the vicinity of residential areas in Belgrade and 12 other cities in Serbia. It will be useful for determining non-ionizing radiation exposure levels of the general public in the future. The purpose of this paper is also an appropriate representation of basic information on the evaluation of measurement uncertainty.

This paper investigates possible effects of alpha particle and ion beam irradiation on the properties of the superinsulating phase, recently observed in titanium nitride films, by using numerical simulation of particle transport. Unique physical properties of the superinsulating state are considered by relying on a two-dimensional Josephson junction array as a model of material structure. It is suggested that radiation-induced change of the Josephson junction charging energy would not affect the current-voltage characteristics of the superinsulating film significantly. However, it is theorized that a relapse to an insulating state with thermally activated resistance is possible, due to radiation-induced disruption of the fine-tuned granular structure. The breaking of Cooper pairs caused by incident and displaced ions may also destroy the conditions for a superinsulating phase to exist. Finally, even the energy loss to phonons can influence the superinsulating state, by increasing the effective temperature of the phonon thermostat, thereby reestablishing means for an energy exchange that can support Cooper pair tunneling.

The wide substitution of conventional types of energy by solar energy lies in the rate of developing solar cell technology. Silicon is still the mostly used element for solar cell production, so efforts are directed to the improvement of physical properties of silicon structures. There are several trends in the development of solar cells, but mainly two directions are indicated: the improvement of the conventional solar cell characteristics based on semiconductor materials, and exploring the possibilities of using some new materials. The aim of this paper is to present some different approaches of improvement of solar cell properties through the investigation of radiation effects on the main solar cell characteristics.

The effects of exposing titanium dioxide memristors to ion beams are investigated through Monte Carlo simulation of particle transport. A model assuming ohmic electronic conduction and linear ionic drift in the memristor is utilized. The memristor is composed of a double-layer titanium dioxide thin film between two platinum electrodes. Obtained results suggest that a significant generation of oxygen ion/oxygen vacancy pairs in the oxide is to be expected along ion tracks. These can influence the device’s operation by lowering the resistance of the stoichiometric oxide region and the mobility of the vacancies. Changes induced by ion irradiation affect the current-voltage characteristic and state retention ability of the memristor. If the displaced oxygen ions reach the platinum electrodes, they can form the O2 gas and cause a permanent disruption of memristor functionality.

Low-dropout voltage regulators with various geometries and technological realisations of serial pnp power transistors were exposed to ionizing radiation. Although devices with vertical emitters were considered much less susceptible to the influence of radiation on forward emitter current gain than circuits with round emitters, the experiment showed a similar degradation of current gain in both cases. The main reason of high radiation susceptibility of the examined vertical serial pnp transistor is the implementation of an interdigitated emitter, with high perimeter-to-area ratio, causing the great increase of serial transistor’s base current, but a minor influence on the maximum output current. Transistors with round emitters with small perimeter-to-area ratio expressed a moderate current gain degradation, but a rapid fall of the emitter injection efficiency, causing a significant decrease of the maximum output current. Regardless of the similar forward emitter current gain degradation, reliability and operational characteristics of two types of low-dropout voltage regulators were completely different.

This paper deals with possible ways of obtaining expanded and combined uncertainty in measurements for four types of GM counters with a same counter’s tube, in cases when the contributors of these uncertainties are cosmic background radiation and induced overvoltage phenomena. Nowadays, as a consequence of electromagnetic radiation, the latter phenomenon is especially marked in urban environments. Based on experimental results obtained, it has been established that the uncertainties of an influenced random variable ′number of pulses from background radiation′ and ′number of pulses induced by overvoltage′ depend on the technological solution of the counter’s reading system and contribute in different ways to the expanded and combined uncertainty in measurements of the applied types of GM counters.

The aim of this paper is to examine the influence of gamma and X-radiation on relevant characteristics of commercial gas filled surge arresters in the d. c. regime. This question is very important because of the wide application of gas filled surge arresters in telecommunications, military industry and space technology. We found that both types of radiation had significant influence on the performance of gas filled surge arresters.

The research presents an experiment with a model of an electronic generator for energy injection into the plasma of a fusion reactor. By recording a non-ionizing field in the vicinity of a fusion reactor, it was determined that this field has an extremely high growth rate. At the site of the maximum intensity of the field of non-ionizing radiation, commercial surge arresters with a flexible model of surge arresters were used for experimentation. It has been found that the commercial surge arresters have an efficiency of about 20 %. For the efficiency of the flexible model, it was found to be slightly less than 40 % (and to be achieved by the application of alpha particle radiation). Since neither of these efficiencies guarantee reliable operation of the gas-filled surge arrester, it was concluded that essential electronics in the vicinity of the fusion generator must be protected. However, since this protection can only be implemented in a fusion reactor, the fact remains that the environment of such a reactor is extremely contaminated with non-ionizing radiation. Commercial surge voltages are isolated for testing since the protection of electronic circuits from fast overvoltages is a critical point for the functioning of modern electronics. [ABSTRACT FROM AUTHOR]

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The calculating of reached ageing based on the history of loading according of International Electrotechnical Commission standard algorithm is the first task. In order to verify the obtained results, measurements of polymerization index were made on 28 paper samples taken directly from low voltage terminals (winding ends) and bus connections of the transformer under test rated 380 MVA, 2x15,75 kV/420 kV. The complete procedure of paper sample locations and taking off is described, thereby providing a manner of how this should be done, determined by specific conditions of the transformer under test. Furthermore, the determination of limit viscosity and using its relationship function with polymerization index are explained together. Comparison is made with those of liquid chromatography of oil. The results of particle sort and size analysis are shown. Finally, an estimation of the transformer life remainder is made, which is of paramount importance when defining the steps that have to be made either in revitalization process or in transformer replacement planning. [ABSTRACT FROM AUTHOR]

Protection at positron emission tomography-computed tomography (PET-CT) installations is the most complex problem in the field of designing structural protection from ionising radiation in medical practice. This paper provides a discussion on the values for shield widths obtained from two different estimation methods, as well as of certain theoretical differences inherent in the two approaches. After the general operation principles of a PET-CT device are expounded, a comparative analysis of two methods for calculating structural barriers is performed. The first calculation was conducted by the ‘Vinča’ Institute of Nuclear Sciences, according to the recommendations of the AAPM task group 108, while the second was performed by a PET-CT device manufacturer, following the DIN 6844-3 standard. [ABSTRACT FROM AUTHOR]