Sensitivity of standard and stacked RADFET dosimeters

Radiation Sensing Field Effect Transistors (RADFETs), also known as MOSFET dosimeters, are discrete p-channel MOSFETs with the gate oxide engineered for increased radiation sensitivity. RADFETs are small, require very little or no power during operation, read-out is simple and non-destructive, and their electronic signal is suitable for integration with the electronics systems. For these reasons RADFETs have found applications in quality assurance of radiotherapy, dose monitoring in high energy physics laboratories, accidental personal dosimetry, and space. Lower dose applications, such as e.g. occupational personal dosimetry and radiology, are currently out of reach owing to inherent sensitivity limits of the standard RADFET technology. Tyndall National Institute has been involved in RADFET research and development, fabrication, and commercialisation for several decades and has acquired significant experience in the technology and applications. This paper presents Tyndall recent efforts in RADFET manufacturing and characterisation for different applications and discusses possible approaches towards increased sensitivity of the technology, including standard and stacked RADFETs.Fourth International Conferenceon Radiation and Applications in Various Fields of Research, RAD 2016, May 23-27, 2016, Niš, Serbi

Development of RADFET detector for personal dosimeter system for European astronauts

Radiation environment in space is very complex, with varying contributions from photons, electrons, protons, and heavy ions. There is a need to measure radiation dose received by the astronauts onboard International Space Station (ISS), and the European Space Agency (ESA) has been supporting a collaborative research project aimed at development of a personal dosimeter for European astronauts at ISS. The development of the personal dosimeter system is in the final phase, with the launch expected in the second half of 2015. The system is called “European Crew Personal Active Dosimeter (EuCPAD)” and consists of a base unit and several mobile units. Base unit is stationery and houses system electronics, Tissue Equivalent Proportional Counter (TEPC), and charging slots for mobile units. Mobile units are worn by the astronauts during their daily activities and consist of four dosimetric modules: thin silicon diode, thick silicon diode, Direct Ion Storage (DIS) dosimeter, and Radiation Sensing Field Effect Transistor (RADFET). We describe the EuCPAD system and our efforts in development of the RADFET module for the EuCPAD mobile unit.Third International Conferenceon Radiation and Applications in Various Fields of Research, RAD 2015, June8-12, 2015, Budva, Montenegr

Application of electrodialysis for whey demineralization

Elektrodijaliza predstavlja suvremenu membransku metodu koja se u svijetu sve više koristi za demineralizaciju sirutke radi ostvarivanja njene veće primjene u proizvodnji hrane za ljude. Slatko-slani ukus sirutke u prahu i visoki sadržaj mineralnih tvari naročito ograničavaju njeno učešće u proizvodima konditorske industrije i proizvodnji dječje hrane. Na laboratorijskom uređaju vršena je elektrodijaliza svježe, slatke surutke pri različitim gustoćama struje.Elektrodialysis represents a modern contemporary membrane process which beside many other recent applications finds increasing uses in whey desalinization. Demineralized whey powder appears in wide increasing application in many products of food technology and most particularly for children food

Comprehensive characterisation of Tyndall National Institute RADFETs for commercial applications in various fields

Radiation Sensing Field Effect Transistors (RADFETs), also known as MOSFET dosimeters or pMOS dosimeters, have found applications in space, high-energy physics laboratories, and radiotherapy clinics. The RADFET is a discrete p-channel MOSFET with a thick gate oxide (typically from 100 nm to over 1 µm), optimised for radiation sensitivity. Radiation induces charges in the gate oxide, which cause the shift of the threshold voltage proportional to the radiation dose. The main good features of the RADFET are small size, simple/immediate/non-destructive read-out, electronic signal, and small cost when produced in volume. The main shortcoming is limited sensitivity, which precludes the use of standard RADFET designs in applications requiring minimum detectable dose lower than approx. 1 cGy. Tyndall National Institute has been developing RADFETs for almost three decades. The technology has recently been transferred to a start-up company Varadis. We present results of electrical and radiation characterisation steps done on Varadis commercial RADFET products. We discuss critical issues in relation to the optimum use of RADFETs and possible methods for lowering the minimum detectable dose.RAP 2019 : International conference on radiation applications; Proceedings book; September 16-19, 2019, Belgrad

Experiments with RADFET dosimeter in electron-beams irradiation and numerical computation of the physical shielding factor

MOSFET electronic components are already the subject of several decades of research in various fields of dosimetry and radiation protection. Special interest appeared when these components are started to be used as dosimeters in radiotherapy with electron beams. However, if one looks much more serious in the wider scientific research horizon, all the results obtained in experiments with precisely defined energies of incident electrons can be used in other disciplines which consider the impacts spectra of cosmic radiation on electronic devices, which is especially importance for cosmic science and space research instrumentation. In this paper, one of the objectives was to examine the electrical characteristics specially designed ESAPMOS RADFET dosimeters in the experiments that were conducted on a linear accelerator installations. RADFET components are bombarded electron beams energy of 6 MeV and 8 MeV, and then are followed by changes in threshold voltage shift mean values depending on the change of absorbed dose is referred to as D(cGy) was determined in water. Conclusions performance RADFET components are more than encouraging in terms of further research to improve the linearity of the energy dependence as widely energy electrons. In the second part of the test complex structure of packaging components RADFET focus is placed on the determination of the energy deposited in layers that are of interest for the analysis of microscopic processes related to the recombination of radiation-induced electron-hole pairs. Transport incident electrons through all the layers of structure RADFET component type ESAPMOS was carried out numerical simulations of the Monte Carlo method using the software package FOTELP-2K12. On this occasion, were taken into account all the physical processes of interaction of electrons with materials given structure. When he conquered the numerical application of mathematical and physical model for determining the value of the absorbed energy as the energy deposited per unit mass in a given layers with different materials, it could be accessed defining physical shielding factor (PSF) for a given structure RADFET components. Physical shielding factor (PSF) is defined as the ratio of absorbed dose values, which in fact means that it is equal to the energy deposited when the RADFET is shielded with protection, and the RADFET without lid. When we know the energy dependence factor for PSF of RADFET with and without armour, can be carried out and the analysis of whether and to what extent the energy required compensating the electronic components. Monte Carlo simulations were performed for the transport of incident electrons from 4 MeV, 6 MeV, 8 MeV and 12 MeV. It can be concluded that the different energy of incident electrons there is a significant influence of material Kovar on the absorbed energy in SiO2 and Si layers structure RADFET, in cases where Kovar used among other things as physical protection.Third International Conference on Radiation and Applications in Various Fields of Research, RAD 2015, June 8-12, 2015, Budva, Montenegr

Radiation characteristics for HFO2 and SIO2 incorporated in electronic component with mos structure in fields of gamma and x-radiation

VI International Conference on Radiation in Various Fields of Research : RAD 2018 : book of abstracts; June 18-22, 2018; Ohrid, Macedoni

One numerical method for determining the absorbed dose of gamma and X radiation in the ZrO2 dielectric within the MOS capacitor

At present, advanced microelectronics devices with Metal-Oxide-Silicon (MOS) structures are used to improve the functional characteristics of devices used in nuclear technology, radiation dosimetry and radiation protection in aerospace engineering, nuclear industry and radiotherapy equipment. Among other things, it is often the goal of new research to find new materials for the dielectric oxide such as of zirconium oxide (ZrO2) with higher dielectric constant (high-k) and testing its characteristics in an environment with radioactive radiation. The paper presents the application of a numerical method for the determination of the absorbed dose of gamma and X radiation in the dielectric thin layer of zirconium oxide, which is located in the structure of the MOS capacitor. The relation on the basis of the numerically calculated absorbed dose of radiation is obtained by using the theory of the physical transport of photons in a thin layer of dielectric. In doing so, it is necessary to know the spatial dependence of the photon flux of gamma or X-ray in a volume of the dielectric, as well as the values of the total mass attenuation coefficient and total energy absorbed mass coefficient for ZrO2 as a radiation characteristic of the material from which is made a dielectric. Based on the results of our research, it can be concluded that ZrO2 has satisfactory radiation characteristics as an alternative to the selection of dielectrics in MOS structures that are incorporated in dosimeters and radiation monitors.VII International Conference on Radiation in Various Fields of Research : RAD 2019 : book of abstracts; June 10-14, 2019; Herceg Novi, Montenegr

A design concept for radiation hardened RADFET readout system for space applications

Instruments for measuring the absorbed dose and dose rate under radiation exposure, known as radiation dosimeters, are indispensable in space missions. They are composed of radiation sensors that generate current or voltage response when exposed to ionizing radiation, and processing electronics for computing the absorbed dose and dose rate. Among a wide range of existing radiation sensors, the Radiation Sensitive Field Effect Transistors (RADFETs) have unique advantages for absorbed dose measurement, and a proven record of successful exploitation in space missions. It has been shown that the RADFETs may be also used for the dose rate monitoring. In that regard, we propose a unique design concept that supports the simultaneous operation of a single RADFET as absorbed dose and dose rate monitor. This enables to reduce the cost of implementation, since the need for other types of radiation sensors can be minimized or eliminated. For processing the RADFET's response we propose a readout system composed of analog signal conditioner (ASC) and a self-adaptive multiprocessing system-on-chip (MPSoC). The soft error rate of MPSoC is monitored in real time with embedded sensors, allowing the autonomous switching between three operating modes (high-performance, de-stress and fault-tolerant), according to the application requirements and radiation conditions

Fuzzy Approach in Ranking of Banks according to Financial Performances

Evaluating bank performance on a yearly basis and making comparison among banks in certain time intervals provide an insight into general financial state of banks and their relative position with respect to the environment (creditors, investors, and stakeholders). The aim of this study is to propose a new fuzzy multicriteria model to evaluate banks respecting relative importance of financial performances and their values. The relative importance of each pair of financial performance groups is assessed linguistic expressions which are modeled by triangular fuzzy numbers. Fuzzy Analytic Hierarchical Process (FAHP) is applied to determine relative weights of the financial performances. In order to rank the treated banks, new model based on Fuzzy Technique for Order Performance by Similarity to Ideal Solution (FTOPSIS) is deployed. The proposed model is illustrated by an example giving real life data from 12 banks having 80% share of the Serbian market. In order to verify the proposed FTOPSIS different measures of separation are used. The presented solution enables the ranking of banks, gives an insight of bank’s state to stakeholders, and provides base for successful improvement in a field of strategy quality in bank business

LEVEL CROSSING RATE OF MACRODIVERSITY SYSTEM OVER COMPOSITE GAMMA SHADOWED ALPHA-KAPPA-MU MULTIPATH FADING CHANNEL

In this paper macrodiversity system with macrodiversity selection combining (SC) receiver and two microdiversity SC receivers operating over composite shadowed multipath fading environment is considered. Received signal is subjected simultaneously to gamma long term fading and α-κ-μ short term fading resulting in system performance degradation. Macrodiversity SC receiver reduces gamma long term fading effects and microdiversity SC receivers mitigate α-κ-μ short term fading effects. Analitical expression for average level crossing rate of proposed wireless mobile system represented as an infinite series is evaluated. Mathematical and numerical analysis are shown influences of gamma fading severity, α-κ-μ multipath fading severity, and Rician factor on average level crossing rate