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Variation of multiplication factor with enrichment for an enriched-uranium reactor
The criticality of a nuclear power reactor is one of the most important factors to be considered in any nuclear world. Multiplication factor, k, sometimes called as survival factor f, is the crucial parameter for achieving the criticality. There are many factors affecting the criticality and in the calculation of k: The thermal fission factor (η), the resonance escape probability (p), and the thermal utilization factor (ƒ) are some of them. Implicitly, the Moderator (graphite) to Fuel ratio (NMF) and the uranium-235 enrichment percent are what all these factors depend on. In order to determine the effects of these various parameters and to illustrate the relationship between these implicit factors and their impact on nuclear reactor criticality a computational method is applied, and the uranium-235 enrichment from 0.7 percent (uranium percent in nature) to 5.0 percent by weight (the maximum allowable in LEU) are examined to calculate the multiplication factor with the corresponding size and volume of the system under investigation. The minimum enrichment for a range of NMF as well as the minimum NMF ratio for a range of enrichment has been considered for the criticality as an optimization problem. Results are presented in Tables and Graphs, and the optimum conditions for the criticality have been discussed. Key
Investigation of first-stage sintering kinetics of UO2, ThO2 and (Th,U)O2 pellets manufactured by internal gelation technique of sol-gel process
The sol-gel process which is among the methods used for the production of UO2, ThO2 and ThO2-UO2 mixed oxide fuel pellets allows a high degree of micro-homogeneity of uranium and thorium in the solution stage. The first aim of this study was to develop an alternative method to produce uranium, thorium and mixed thorium-uranium dioxide fuel pellets by using internal gelation technique of sol–gel process. The second aim was to investigate shrinkage behavior and first-stage sintering kinetics of pellets compacted in the Ar-%5 H2 atmosphere using dilatometer. Shrinkage curves of the UO2, ThO2, ThO2-10%UO2 and ThO2-5%UO2 pellets obtained from the dilatometer were used to determine the sintering mechanism, the diffusion coefficients and the activation energy.
Synthesis and investigation of thermoluminescence properties of rare earth (Dy) doped CaAL4O7
In this study the thermoluminescence (TL) properties of calcium aluminate (CaAl4O7) doped with rare earth ion, Dysprosium (Dy), have been investigated in detail. CaAl4O7:Dy phosphors were synthesized by using the sol-gel method. The glow curves of the samples were evaluated by using 90Sr-90Y (≈ 0.04 Gy/s) beta source for different dose levels between 0.2 Gy and 864 Gy and the kinetic parameters such as activation energy (Ea), and order of kinetics (b) were calculated by using peak shape method, heating rate method, and computer glow curve deconvolution method. The results of the experiments have shown that the sample has two general order glow peaks; P1 at 125oC and P2 at 160 oC. The peak at 125oC has a kinetic order of b=1.5 and activation energy Ea= 0.5 eV. The fading characteristics of the sample were also studied over a period time. The samples were irradiated and stored in a darkroom at room temperature. The results have shown that, the intensity of the main glow peak (P1) of CaAl4O7: Dy at the end of the planned storage times reduced typically 51 % of its original value.
Solution of Klein-Gordon equation in D-dimension and its application in physical systems
The analytic and approximate solution of KG-equation in arbitrary dimension D are calculated by using Asymptotic Iteration Method. The system of some important type of potentials like harmonic oscillator potential, the Go'ldman-Krivchenkov potential and some exponential-type potentials such as Morse and Woods-Saxon potentials have been studied in the D-dimension. The corresponding eigenvalues are obtained. In addition, the total normalized eigenvectors are obtained after calculating normalization constant for each type of potentials. Furthermore, it is shown that application of Asymptotic Iteration Method in KG-equation gives the eigenvector solution in terms of the Gauss hypergeometric or its special cases using the wavefunction generator.
Computational modelling of highly mis-matched alloys of GaNAsP and GaNAsBi as a laser gain material
The aim of this thesis work is to model and investigate the electronic band structure and current density of highly mismatched alloys of GaNAsP and GaNAsBi. To reveal the importance of these highly mismatched alloys we provide a comparison of GaNAsP and GaNAsBi with their nitrogen free N-counterpart. The GaP-based dilute nitride direct bandgap material Ga(NAsP) is gaining importance for the monolithic integration of laser diodes on Si microprocessors. The major advantage of this newly proposed novel laser material system is the small lattice mismatch between GaP and Si. However, from first gain measurements it is found that Ga(NAsP)/GaP material system has high threshold current at room temperature. Therefore, we present a comprehensive theoretical analysis of band alignment and threshold current in dilute nitride direct bandgap Ga(NAsP)/GaP/AlGaP QWs on silicon substrates using model calculations. The comparison of our calculated results with that of the experimental data indicates that the Auger effect involving CHCC process can be considered as the dominant non-radiative loss mechanism at 300K. It has just recently reported that highly mismatched semiconductor alloys of GaAs(1-x)Bi(x) has also several novel electronic properties, including a rapid reduction in energy gap with increasing x and also a strong increase in spin-orbit-splitting energy with increasing Bi composition. We, therefore to understand the origins of the rapid reduction in energy gap and its consequences, study and compare band gap and critical thickness of GaNAsBi. The results indicate that GaNAsBi material can be used in optoelectronic applications in the long wavelength region.
Gaziantep şehrinin Şahinbey, Nurdağı ve İslahiye ilçelerinin topraklarında doğal radyoaktif seviyelerinin belirlenmesi
The aim of this thesis is determine of the level of natural radioactivity in 61 soil samples taken from different regions of Islahiye, Nurdagı and Sahinbey districts of Gaziantep city. 238U, 232Th and 40K radioactivity concentrations of radionuclides in soil samples taken from these district were measured by using a well type NaI(TI) detectors connected to multichannel analyzer (MCA). The results of the natural radioactivity of the region that have been evaluated according to specific criteria. Average specific activities of 238U, 232Th and 40K in soil samples taken from İslahiye, Nurdağı and Şahinbey districts in Gaziantep city were found to be 39.18 ± 21.52 Bq/kg, 44.30±20.81 Bq/kg and 325.54±42.13 Bq/kg, respectively. The average 40K activity values were found to be slightly lower than international average effective value given by UNESCEAR 2000 report. Key words: İslahiye, Nurdağı, Şahinbey, Gamma Spectroscopy, NaI(TI) detector.
A novel approach for heavy quarkonium spectra
In this work, we attempt to investigate heavy quark systems ( and ) in the non-relativistic framework using phenomenological inter-quark potentials. For this reason, we have developed a powerful and flexible theoretical formalism, within the frame of the Schrödinger equation, to use for the analysis of heavy quarkonium systems involving exactly solvable energy-dependent potentials, together with quasi-/conditionally-solvable and non-solvable interaction potentials. Our first application to exactly solvable systems has clarified that energy dependent term in the potential leads to saturation of the spectra and degree of saturation is governed by the magnitude of perturbation. Second application to quasi-exactly solvable potentials, which is the Coulomb plus linear potential with a quadratic term, has justified the success of the present formalism due to its wide range of applicability, considering the comparison of the findings obtained by the present approach with those of experimental results and the other theoretical predictions in the related literature. Finally, the application of this new technique to also non-solvable systems involving Cornell potential has shed some light on the questions concerning with the limitations of the traditional perturbation techniques.
Liquid drop model and alpha decay in nuclear structure study
Six different liquid drop model (LDM) formulas (LDM1, LDM2, LDM3, LDM4, LDM5 and LDM6) were analyzed to describe nuclear binding energy for 3252 nuclei which were classified into four groups; deformation group which contain six sets, decay mode group which contain two sets, spin group which contain six sets and final group which contain all nuclei. LDM6 was firstly formed and used in this study to represent nuclear binding energy. We determined the coefficients of all LDM formulas by using nonlinear regression method. Moreover we calculated root mean square (RMS) for all nuclei groups by using all LDM formulas. Comparison of experimental data of binding energy with calculations was also studied for all LDM formulas. It is shown in this study that by adding shell correction and shell effect terms to all LDM formulas RMS is being smaller. A systematic study on alpha decay half-lives using five different semi-empirical formulas for even-even, even-odd, odd-even and odd-odd nuclei was also done in this thesis. Calculated half-lives were carefully compared with measured ones for 459 different isotopes. Key words: Liquid drop model, binding energy, shell correction, shell effect, alpha decay, half-life, nonlinear regression.
The investigation of variation of TL dose response curve of natural calcite after annealing at different temperatures
The thermoluminescence (TL) studies of calcite mineral have resulted in the development of a wider range of applications in ceramic industry field. The TL glow curve shapes of minerals changes as a result of crystal purity, radiation dose, and thermal history previous the irradiation. In this study, the TL dose response of natural calcite samples of unannealed and annealed at different temperatures has been studied. The calcite samples that were collected from Elazığ-Ağın city in Turkey exhibit two main TL peaks following β-irradiation. The samples were annealed at 600, 700, 800, 900, 1000 oC from 15 minutes to 240 minutes and then they were irradiated at room temperature with a point beta source for different time durations to study TL dose response curve. It was observed that the annealings at 900 and 1000oC have high prononuced effects on the dose response curve of natural calcite.
Development of new thermoluminescent dosimeters for neutron measurements
The main purpose of the proposed study is the investigation of the possibility to be used as neutron dosimeters with the analysis of the dependence on thermoluminescent radiation dose by synthesizing the borates which is doped metal ions and were development of materials until obtaining the best thermoluminescent neutron dosimeters. Borate anion group-containing materials such as LiB3O5, Li2B4O7, BaB4O7, CaB4O7 and MgB4O7 were produced for to be used as neutron dosimeters by solid-state synthesis method and after the synthesizing process compounds which include borate anion group were be doped with metal ions by high temperature solid state method. Afterwards, for thermoluminescence measurement of doped materials with the aim of the characterization of dosimetric materials X-ray powder diffraction (XRD), Thermal (DTA, TGA), Scanning Electron Microscope (SEM) and Fourier Transform Infrared Spectroscopy (FTIR) analyses are done. As a result of this analyses, the thermoluminescence measurements of materials are taken. XRD patterns of the synthesized compounds have demonstrated compliance with borate peak in JCPDS card. FT-IR spectra results did not yield different band structure in compounds. Thermoluminescent measurement results show that neutron radiation-sensitive borate compound are produced. Thermal analysis of the neutron-sensitive compounds were performed. According to the results of this analysis borate compounds are thermally stable. In all borate compunds, 0.5Dy% doped CaB4O7 yielded highest thermoluminescence response. Doping with Dy, MgB4O7 compounds shows increased thermoluminescence response for neutron radiation. Using different concentrations of Dy, Ag, Cu, Eu, Mg and Gd dopants into Li2B4O7 gave good results of neutron-radiation sensitivity. In this study, borate compounds that result after neutron irradiation were compared with TLD-600/TLD-700 neutron dosimeters. Accordingly, the compounds exhibit an ideal fit for all conditions required for a neutron dosimeter. The work carried out under this thesis has reached the objectives.
A study on corrosion characteristics of AA2024 under different conditions
In this work the corrosion characteristics of bare aluminum based alloy (AA2024) and zinc coated AA2024 are studied in the aqueous solution having three different pH (2, 7 and 12). Apart from the traditional methods of aluminum coating (chromate conversion coating and zincating), this thesis suggests an alternative way to coat aluminum with a metal. A novel ionic liquid consisting of only cations and anions electrolyte is used for this purpose. AA2024 alloy in a deep eutectic solvent (DES) having zinc ions cannot be coated by zinc by applying anodic potential directly due to the typical characteristic of aluminium alloy which has Al2O3 thin layer occurring naturally on the aluminium surface. To electrodeposit zinc on aluminium alloy, an extreme anodic voltage (+1.65) is firstly applied for removing Al2O3 layer in Ethaline and then the cathodic potential (-1.5 V) is immediately applied in order to deposit zinc in-situ on newly prepared aluminium alloy surface which does not have Al2O3 anymore. Galvanised AA2024 displays the characteristic of an amorphous structure observed by SEM and XRD. Bare AA2024 has pitting corrosion at high potential in three aqueous medium use in this work (10 mM HCl, 0.5 M NaCl, 10 mM KOH). Zinc coated AA2024 has passivation behaviour in alkaline and acidic media. Corrosion resistance of zinc coated AA2024 alloy is almost as high as that of bare AA2024 in three different media. The work reported in this thesis presents that zinc coated AA2024 has more than six times higher corrosion resistance than bare Al2024 in alkaline medium (pH = 12).
Synthesis and thermoluminescence characteristics of rare earth doped nanophosphors
In this study we have investigated the thermoluminescence (TL) properties of Sr-doped magnesium tetraborate (MBO) and KCl doped zinc borate (ZnB2O4) nano phosphors, which were synthesized by using the high temperature solid-state and solution combustion method. The glow curves of the samples were evaluated by using 90Sr-90Y (≈ 0.04 Gy/s) beta source for different dose levels between 0.2 Gy and 288 Gy and the kinetic parameters such as activation energy (Ea), and order of kinetics (b) were calculated by using different methods. The experimental results for Sr-doped MBO nano phosphor indicated that it has main glow peak with highest intensity at approximately 200 °C with good linearity of the dose–response up to 570 Gy. On the other hand the experimental results for KCl doped ZnB2O4 nano phosphor has shown that it has a broad glow curve structure, which consists of nine glow peaks. The fading characteristics of the samples were also studied over a period time. The samples were irradiated and stored in a darkroom at room temperature. At the end of the planned storage times the normalized TL area, of Sr-doped MBO reduced typically 50% and KCl doped ZnB2O4 reduced 70% of its original value. Keywords: Thermoluminescence, dosimeter, kinetic parameter, MgB4O7:Sr, ZnB2O4:KCl, solid-state reaction method, solution combustion method, nanoparticle
The investigation of the effects of pre-irradiation annealing procedures on thermoluminescence dosimetric properties of different natural samples
Many thermoluminescence properties of dosimetric minerals may be affected by external effects and environmental condition. Annealing is one of the most known external effects and has different process. As a result of annealing process, the defect distribution of a specimen can be altered and thereby its sensitivity changes. In spite of fact that standard annealing procedures exist for the dosimetric purposes of the synthetic materials, these can be different for natural minerals. As the thermoluminescence properties of different natural minerals are unequal, different thermoluminescence properties are observed for the same natural minerals collected in the different region of the world. Therefore, annealing may alter the thermoluminescence properties of each natural minerals, differently. This thesis reveals that how the thermoluminescence properties of different natural minerals are affected by different pre-irradiation annealing processes. The origins of natural minerals used in this thesis were different and obtained from the different regions of Turkey. The thermoluminescence properties of four different natural minerals which are calcite minerals in sand used in making roasted chickpea, fluorapatite minerals in tooth enamel, plagioclase minerals in basaltic rocks and biogenic minerals in seashell have been studied under different thermal treatments.
Neutron halo and related structure in light nuclei
The works appeared recently dealing with exotic halo nuclei have displayed striking variations in nuclear shell structures and revealed the emergence of novel magic numbers unlike the stable nuclei. One of the significant reasons for these variations is the effect of tensor forces on nuclear structures, which has been reviewed in this report. Also, with the consideration of three-body nuclear forces, the known dramatic peculiarity over the oxygen isotopes has been debated to clarify why is the heaviest bound oxygen isotope. Finally, we focus at loosely bound neutron states within the frame of light halo nuclei to grasp why the weak binding plays a crucial role in observing the change in energies of lowest states. Keywords: Exotic nuclei, neutron-halo nuclei, , nuclear tensor force, three-body interaction force, binding energy
Investigation of thermoluminescence (TL) retrospective dosimetric properties of silicon carbide (sic) used in industry applications
During a nuclear accident or violent terror attack the dose measurement was not easily done at this moment because the data is not available to decide correct value of dose in the contaminated area. One of the alternative solution is by using retrospective dosimetry as a tool of accidental dosimetry for dose estimation. And many objects of the contaminated area are applicable as retrospective dosimeters. Although many electronic devices today are based on pure silicon substrates, a number of other substrates are used in various applications. SiC has been found to be widely useful as a substrate and wide band gap semiconductor in, high-temperature, high-frequency, and high-power electronic devices, as well as in short wavelength, radiation resistant optoelectronic devices. The aim of this study was to discuss the thermoluminescence (TL) properties of silicon carbide (SiC) used in industry applications for retrospective dosimetry purposes. Basic TL properties of these materials (e.g. dose response, heating rate, fading effect and reproducibility) have also been investigated.
Evaluation of the accuracy and efficiency of the in vivo dosimetry systems for whole brain cancer patients
In external beam radiotherapy quality assurance is carried out on the individual components of the treatment chain. The patient simulating device, planning system and linear accelerators are tested regularly according to set protocols developed by national and international organizations. In-vivo dosimetry measures the dose to the target volume through indirect measures therefore the most likely method for picking up errors which might occur earlier in the chain. In vivo dosimetry, using diodes or thermoluminescent dosimeters (TLDs) is performed in many radiotherapy departments to verify the dose delivered during treatment. In vivo dosimetry is applied to evaluate the delivered dose to critical organs or in complex geometries where the dose is hard to predict from the treatment. The aim of this study was to verily the response of TLDs type (LiF) use in radiotherapy, using Thermoluminescence detectors to establish calibration procedure for TLDs and to evaluate admission dose obtained by the treatment planning system with measured dose.
The investigation of thermoluminescence intensity-dose response relation of the tooth enamel at different annealing temperatures
Thermoluminescence (TL) is the natural light phenomenon emitted from an insulator or wide band gap semiconductor after absorbing some energy from an external radiation source when it is stimulated by thermal excitation. Tooth enamel is the hardest part of tooth and protects the dentine. In terms of its weight, it consists of 95% inorganic minerals, 1% organic minerals, and 3% water. Fluorapatite Ca5F(PO4)3 is an important mineral in tooth enamel. Due to the fact that the effective atomic number of fluorapatite is nearly the same with human calcified tissues, it is a candidate of important thermoluminescence dosimeter (TLD) material. In this thesis, thermoluminescence (TL) intensity-dose response relation of fluorapatite mineral in tooth enamel under the different annealing temperatures were investigated and then analyzed its thermoluminescence glow curve peaks with a computer programs. This study reveals that the fluorapatite mineral extracted from tooth enamel shows TL properties. Annealing of the sample at different temperatures affects the TL output- dose response relation. A good linearity in dose response is observed in the samples annealed at 400 oC and 700 oC. And also, dose variation differently changes the trap positions at different annealing temperature.
Acoustical analysis and evaluation of cultural centers at Gaziantep University
Gaziantep, one of the oldest cultural centers in the Southeastern Anatolia Region, is located on the historical Silk Road. The main objective of this thesis is the analysis of current acoustical performance of Gaziantep University Auditorium and Atatürk Cultural Center which are the most important centers of these cultural activities to carry out. Despite the fact that both salons are used as multipurpose halls, there are no variable panels (or any acoustic solution) in volume. In this context, the assessments were made on the basis of subjective and subjective parameters based on room acoustics. The measurements of the obtained acoustic parameters were compared with the results obtained in the ODEON acoustic analysis program for accuracy. The results were analyzed on the basis of the room acoustic criterion of multipurpose halls, and some suggestions were made to improve the acoustical performance of both halls.
Investigation of thermoluminescence response of TLD-600 and TLD-700 dosimeters to neutron+gamma and beta radiations
In this study some of the thermoluminescent properties such as glow curve structure, relative thermoluminescence sensitivity, dose response linearity of lithium fluoride thermoluminescent dosimeters TLD-600 (6LiF: Ti, Mg) and TLD-700 (7LiF: Ti, Mg) were investigated after irradiation 252Cf neutron+gamma and90Sr-90Y beta sources at room temperature and then with obtained results were compared. The kinetic parameters of TL glow peaks namely the order of kinetics (b), activation energy (Ea) and the frequency factor (s) of these dosimeters have also been obtained using the computerized glow curve deconvolution (CGCD) program. In addition, the effect of heating rate on the TL glow curves of dosimeters has been investigated. They were found that the maximum TL glow peak intensities and the total area under the glow curves of both dosimetries are decreasing with increasing heating rate. There is no good agreement with the kinetic parameters calculated by CGCD program for both radiation sources.
Investigation of thermoluminescence properties of natural calcite (CaCO3) from Iraq
Thermoluminescnce characteristics for natural calcite sample has been investigated in this study after irradiated by beta source for dose level from 2.4 Gy to 2.3 kGy. Computer glow curves deconvolution (CGCD) and Peak shape (PS) methods are used to estimate E (activation energy), s (attempt-to-escape frequency factor) and b (kinetic order). Calcite sample which used in this study where collected from DOHUK city – north of Iraq show two peaks follow Beta irradiation for dose levels which were applied in this study, peak 1 at 189 0C and peak 2 at 280 0C. Benefits of studying dose response and fading are to measure irradiation dosimetry and archeological dating. Calcite sample was irradiated and stored in dark box at room temperature and read out, after three weeks peak 1 completely disappeared, after 1 hour of stored peak 1 down to half of original intensity value, this means that this sample loses radiation fairly quickly.
Experimental performance investigation of electrical energy production system by using vertical barrel of two and five blades from wind energy in Gaziantep condition
Vertical-axis wind turbines (VAWTs) possess several advantages over the conventional horizontal-axis type. Savonius turbines are drag-based routers which operate due to a pressure difference between the advancing and retreating blades. These turbines are simpler in design, less expensive to install, non-dependent of wind direction, and more efficient at lower wind speeds. This makes it suitable for generating electricity in many countries. This work is a study of the performance of the Savonius rotor which contains two and five blades made from barrels of oil under the normal weather conditions of the Turkish city of Gaziantep. This rotor has the best self-starting at low wind speed, under any load generator. Where begins rotation of 20 RPM at 2 m/s wind velocity. We also find the maximum power coefficient at the tip speed ratio and the amount of voltages generated by the generator at different wind speeds to both types and know which one has the best performance. Key Words: Vertical axis wind turbine, savonius, electric power, voltage.
Calculation of critical mass for fission chain reaction
Neutrons at certain energies colliding with fissile nuclei may cause them to undergo fission reaction by splitting into fragments at different masses. Since new neutrons are produced at the end of each fission reaction, a certain amount of fissile material in any type of nuclear reactor core is required for a sustainable chain reaction by these neutrons. It is necessary to determine the amount of mass required for a sustainable fission chain reaction since the procedure is completely random for neutrons to strike target nuclei. It is known that the critical mass is the smallest amount of fissile material needed for such a sustainable nuclear chain reaction in any system of geometry. It is obvious that the critical mass of a fissionable material depends upon its nuclear properties such as its fission cross-section, density, shape, enrichment, purity, etc. In this study, the solutions of the steady-state one group diffusion equation are firstly analytically obtained and then compared with numerical results of the Monte Carlo Method coded to calculate the critical mass for three basic geometries. The survival fraction value, f_s (which is also called as the multiplication factor, k) is calculated for the criticality condition for these geometries and the results are tabulated for each one. Our numerical calculations by Monte Carlo Method show that the minimum critical mass is obtained in the case of spherical shape of fuel element for which the analytical solutions are also in aggrement.
Modelling of novel bismide alloys for optoelectronic devices
The purpose of this thesis work is to investigate the electronic band structures of InAsBi/InAs, InPBi/InP, InSbBi/InSb and GaAsBiN/GaAs III-V materials by means of using model calculations. When bismuth and nitrogen atoms are incorporated into a III-V binary host semiconductor, bismuth and nitrogen impurity atoms occupy at localized energy levels which lies inside or close to the valence and conduction band, respectively. These localized impurity states interact with the extended valence and conduction band states of host alloy. This interaction causes a splitting in each of these band states of the light hole, heavy-hole, split-off band and conduction subbands into subbands of E+ and E- energy levels. The incorporation of dilute bismides and nitrides into host materials cause a reduction in band gap with increasing bismuth and nitrogen concentration, an increase in spin-orbit splitting energy with increasing bismuth concentration. These major modifications in band structure tends to eliminate or suppress optical loss mechanism, such as Auger recombination and Intervalence band absorption. Our theoretical analysis is based on the conduction band anti-crossing, C-BAC, model for incorporation of dilute nitrides and the valence band anti-crossing, VBAC, model for incorporation of dilute bismides to model the restructuring of valence and conduction bands.
Investigation of thermoluminescence properties of calcite mineral conducted by bacterial calcium carbonate (CaCO3) precipitation in organic soil
The object of this study is investigation of thermoluminescence (TL) properties which are dose response, heating rate, reproducibility and fading of calcite mineral conducted by bacterial calcium carbonate (CaCO3) precipitation in organic soil. The TL glow curves of the irradiated samples by using beta source 90Sr-90Y (≈ 0.04 Gy/s) were obtained for different dose levels between 2.4 Gy and 6.9 kGy. Trap parameters such as trap depth (Ea) and kinetic order (b) were obtained by using computerized glow curve deconvolution (CGCD) method, also the peak integral (n) was evaluated from TL signal by choose a specific dose at with 1oC/s heating rate β. The results for calcite show a clear TL glow curve with four main peaks located around 90, 140, 210 and 240 oC and good TL properties with good reproducibility, wide linear dose response and good fading. A good linearity behavior observed for the dose–response between 140 Gy and 2.3 kGy for the peaks 210 oC and 240 oC. The dosimetric peaks located between 200 and 250 oC are not affected by the storage time. The kinetic parameters of traps are calculated for two main peaks which located around 88 and 208 oC, the trap depth varies between 0.74 - 0.82 eV and 0.83 - 0.88 eV, kinetic order (b) varies between 1.24 -1.5 and 1.4 -1.5, respectively.
On the prompt fission neutron energy distributions
Prompt fission neutron energy spectrum (PFNS) from spontaneous fission of 240Pu (sf) and 242Pu (sf) is calculated and compared quantitatively with the experimentally measured data. Calculations were done with three different methods; the first method is based on neutron's average center of mass kinetic energy, for the second fission fragment excitation energy distribution was used, and for the third method standardization of 252Cf (sf) was preferred. In each method aim is to calculate nuclear temperature parameters of light and heavy fission fragments. The last method has also been used in this thesis to calculate several crucial parameters of some well-known fissile nuclei, such as neutron average center of mass energy, excitation energy and multiplicity. We have shown that all calculations well describes the observed data.
Effect of temperature on photovoltaic panel efficiency
Today, the needs of societies are mostly provided by technology and the new generation technology has entered every part of our lives. New generation technology has created a high level of energy requirement. Many energy sources have started to be depleted rapidly and today's society has turned to search for renewable energy sources. The sun is the basis of all energy sources, and many solar energy systems especially photovoltaic panels have been developed. Photovoltaic panels are the system that converts light from the sun into direct electrical energy. In the photovoltaic panel system, there is a high amount of energy losses during the conversion of the incoming light to electricity. In this study, the negative effect of temperature on photovoltaic panels was investigated and in order to eliminate this effect, behind the panel was applied with water cooling method. Power comparison is carried out between normal solar panel and water cooled solar panel. It was shown that the output power in the water-cooled system is higher than the normal panel. Key word : Photovoltaics, Cell Efficiency, Solar system, Cell temperature
The investigation of thermoluminescence properties ofdental ceramics
Dental ceramics taken from humans who are potentially exposed to radiation, are commonly used as retrospective dosimetry for quick and reliable dose estimations due to nuclear power plants that are close to settlement of people. Nowadays most people have a dental restoration for the compulsory health problem and aesthetic beauty. Moreover dental restorations are usually applied to the front teeth, it can be considered that the radiation directly interact with the material. Therefore, dental ceramics could be potentially used for retrospective dosimetry purposes since allows a quick and reliable dose assessment in case of nuclear accident or bad use of a nuclear attack. Therefore, dental ceramics that used in restoration of human teeth as an accident dosimetry by thermally stimulated luminescence method have been investigated in this study. Glass ceramic, lithium disilicate glass ceramic and feldspathic dental ceramic which used in this study were obtained from Vivadent ivoclar, Sweden and Turkey, respectively. The aim of the study is to investigate the thermoluminescence dose response, the effects of heating rates on the thermoluminescence characteristics, the stability of the dental ceramics with respect to the cycle of measurement and also fading properties of dental ceramics. Finally we compared the samples with respect to their TL characteristic properties to choose the most suitable dosimetric ceramic.
Tactile, embedded, audible sensation system for blind people
ABSTRACT TACTILE, EMBEDDED, AUDIBLE SENSATION SYSTEM FOR BLIND PEOPLE KARAOĞLAN, Kemal M.Sc. in Physical Engineering Supervisor: Prof. Dr. Zihni ÖZTÜRK April 2019 59 pages It is not possible for visually impaired individuals to move around without getting support from another person when they go out of their houses and perceive their surroundings. He gets help to get to where he is going in the city and in all settlements, he does not know which street, street, building or institution he is when he comes to a door or entrance, when he comes to a street. For this reason, the visually impaired individual is guiding another person, which limits the individual life opportunities of the visually impaired individual. For this purpose, dots called the sensitive line, which are developed for this purpose, are not sufficient but only allow the visually impaired person to follow a line and realize that the end of the line is at the end of the line. You can not find out where you are walking, where you will be at the end of your walk, where you end up, and where the junction is. For this reason, he needs a support or knowledge again.This thesis study examines a system that allows the visually impaired individuals to use and perceive the place to go. It consists of a cane, wireless glasses and earphone, a movable cane carried by the user, and an informative unit which can be placed on the surface, buried in the pavement walkway and used indoors and outdoors Key Words: Audible eye, Sensitive lines, Voice relief lines, Voice access, Visual impairment orientation
A study on the computerized tomographic x-Ray radiation on duration and Ramsay scale of sedation
the effect of CT
Structure, composition and corrosion studies of Zn, Cu, Sn and their alloys electrodeposited from a deep eutectic solvent
In this thesis, platinum and steel were coated with metals (Cu, Zn and Sn), binary alloys (Cu-Zn, Cu-Sn and Zn-Sn) and a triple alloy (Cu-Zn-Sn) by electrochemical method. The corrosion behaviour of these films were investigated in 3.5% NaCl solution. Chlorine chloride-ethylene glycol based ionic liquid was used for electrodeposition of metals and alloys. The plating process was carried out on platinum and steel by a three electrode system by applying constant potential. As metals/alloys were electrodeposited potentiostatically, chronoamperometric graphs of deposition were obtained. The resulting coated samples were analyzed by SEM, XRD/EDAX and optical microscope. Potentiodynamic polarization (Tafel Plot) was applied to understand the corrosion mechanism of uncoated and coated samples in 3.5% NaCl. Corrosion current of Zn is lower than the other two metals and among these three metals zinc has passivation behaviour. Corrosion behaviours of binary alloys (Cu-Zn, Cu-Sn and Zn-Sn) and ternary Cu-Zn-Sn were examined. Generally, corrosion resistivity of binary alloys on Pt is higher than that of metals on Pt. It could be said that Zn dominates corrosion current of alloys deposited from a deep eutectic solvent. Corrosion resistivity of binary alloys on steel is close to each other. Corrosion current density of binary alloys on Pt is approximately 10 times more resistive than bare steel. The polarisation curve of the ternary alloy of Corrosion resistivity of ternary alloy (Cu-Zn-Sn) on Pt is eight times greater than bare steel. Alloys could be electrodeposited on steel to prevent corrosion.
Investigation of the effects of beta rays on phosphorescent materials
The aim of this thesis is to investigate the effects of beta radiation on phosphorescent materials. Nowadays phosphorescent materials are used to get the production of more efficient beta voltaic nuclear batteries. They convert the kinetic energy of particles to fluorescence by using phosphor material and then to convert electricity via photovoltaic cell. We have researched the effects of beta particles by analyzing the parameters such as range and generation rate for different type of phosphorescent materials that are used in nuclear batteries. These parameters effectively improve the output performance and energy conversion efficiency in nuclear batteries.
Design and production of a portable solar test device to test, the characteristic values and the classification of solar panels
The electric output performance of crystalline silicon and thin film PV modules are generally measured under standard test conditions (STC), ensuring a relatively independent comparison and output evaluation of different solar PV modules. STC is an industry-wide standard to indicate the performance of PV modules and specifies a cell temperature of 25°C and an irradiance of 1000 watt/m2 with an air mass 1.5 (AM 1.5). These correspond to the irradiance and spectrum of sunlight incident on a clear day upon a sun-facing 37 degrees tilted surface with the sun at an angle of 41.81 degrees above the horizon. This condition approximately represents solar noon near the spring and autumn equinoxes in the continental United States with surface of the cell aimed directly at the sun. However, these conditions are rarely encountered in the real-world. In this study, DC voltmeter and DC ammeter has been used which has RS485 communication protocol. Open circuit voltage (Voc) , short circuit current (Isc), maximum voltage under load (Vmp) and maximum current under load (Imp) of different power solar panels have been measured after that compared with label values. Additionally, Open circuit voltage (Voc) , short circuit current (Isc), maximum voltage under load (Vmp) and maximum current under load (Imp) values have been transferred to touchable Liquid crystal display (LCD) with the aid of RS485 protocol for user benefit. With aid of this portable test device also can measure personal solar panel power as small scale project and detect defect modules of in photovoltaic farm as large project. Key Words: PV Modules, Testing Measurement and Classification System for the PV Panels
Investigation of factors influencing the efficiency of nuclear batteries
In this thesis, the conversion of the kinetic energy of beta particles emitted from a radioactive isotope to electricity is investigated by using the direct and indirect conversion methods. In the experimental part, analysis of the effects of low-activity radiation from Pm147 and Sr90 beta sources, two different phosphors and graphene on Si photovoltaic cell is performed. Phosphor layers with different mass thicknesses are prepared from ZnS:CuCl and SrAl2O4:Eu2+,Dy3+ phosphor powders. The electrical performances of direct and indirect nuclear battery models are analyzed by measuring short-circuit current and open-circuit voltage. Furthermore, the time-dependent variation of the short-circuit current during the beta irradiation is researched. The most efficient battery model is determined as Pm147/SrAl2O4:Eu2+,Dy3+/PV cell. In the theoretical part, betavoltaic battery designs are modeled using the p-n homojunctions, p-n heterojunctions, and Ni63, Pm147 beta sources by considering the parameters affecting the efficiency. A theoretical investigation of the electrical performances has been carried out on Si, GaP, GaN, GaP-Si, and GaN-Si betavoltaic batteries. In addition, the effects of doping concentration and junction depth on the maximum power are examined. The heterojunction photovoltaic cells are preferred to increase the collection efficiency and the power in the betavoltaic battery according to our calculations. By optimizing the doping concentration and junction depth, high-efficient heterojunction betavoltaic batteries are achieved.
Measurement of the inclusive production of the d*0 (2007) meson in hadronic z decays with the aleph detector at the lep collider
A measurement of the inclusive production rate of the charmed D*0 (2007) meson in hadronic Z decays is performed using data from the ALEPH detector at the LEP collider. A total of 3,239,746 hadronic events are selected from data recorded by ALEPH from the 1991 to 1995 running periods. Decays of D*0 D0pi0 are reconstructed for x_E >= 0.3 where x_E = E_D*0 / Ebeam. The average D*0 multiplicity per hadronic event is evaluated to be: =0.289 +- 0.031 +- 0.067 +- 0.009 where the first error is statistical and the second is systematic. The third error is from the extrapolation to x_E = 0. The rates and differential cross-sections are compared with Monte Carlo model predictions. The signal significance is improved explicitly by applying machine learning algorithms based on Multi Variate classification methods of artificial intelligence applications.
The investigation of the effects of velocity dependent potential in the solution of wave equation
ABSTRACT THE INVESTIGATION OF THE EFFECTS OF VELOCITY DEPENDENT POTENTIAL IN THE SOLUTION OF WAVE EQUATION BERK ATEŞ, Yıldız Ph.D in Engineering Physics Supervisor: Prof. Dr. Eser OLĞAR February 2020 88 pages In this thesis, the effect of the velocity-dependent potential is taken into consideration in order to obtain the solution of Schrödinger equation (SE) for different physical potentials. By choosing form factors as three different cases such as ε(r)=γρ_0,ε(r)=γr and ε(r)=γr^2, the velocity-dependent potential is determined and the energy eigenvalues and eigenfunction are obtained for any quantum numbers n and l. During all calculations, the well-known method Nikiforov-Uvarov (NU) method is used. It is seen that by taking γ=0, the obtained results are reduced to results of velocity-independent potential case which are in good agreement with those of in literature. The variations of energy eigenvalues are tabulated and graphed with respect to quantum numbers n and l. Key Words: Velocity-Dependent Potentials, Analytical Solution, Numerical Solution, Nikiforov-Uvarov Method.
Investigation of spectral radiance responsivity for optical systems
The aim of this thesis is establishment and determination of radiance responsivity to be used in calibrations of polychromatic radiation sources. In realizing the radiance, Ar-Ion (457, 477,488 and 514 nm), He-Ne (543, 594, 604, 612 and 632.8 nm) and Nd:YAG (532 nm,1064 nm) lasers and an integrating sphere with 15 cm diameter are used to get radiation sources having Lambertian distributions. Then silicon photodiode based trap detector which is treaceble to the liquid helium cooled laser based cryogenic radiometer is used to measure the photocurrent corresponding to each wavelength and thereby to obtain radiance. The measurement system used to have spectral current response of this laser based radiance is a double grating monochromator with 2 x 300 mm focal length and triple gratings in its each turrets. The gratings used for these measurements have 2400 g/mm and 1200 g/mm grove densities and blazed to 250 nm and 500 nm respectively. The laser beams emerged from the integrating sphere after the radiance evaluation directed on monochromator and from its exit slit the photocurrent responses record at each laser wavelengths. From the radiance realized at laser wavelengths and the photocurrent, values recorded at the exit slit of monochromator, transfer function (radiance responsivity) of the optical system is obtained. This radiance responsivity together with monochromator system is used to derive the spectral radiance of polychromatic radiation sources with low uncertainty. Moreover, in this work the uncertainty scale is determined using both classical and Monte Carlo methods.
Numerical and algebraic treatment of dynamical systems equation and soluable potentials
ABSTRACT NUMERICAL AND ALGEBRAIC TREATMENT OF DYNAMICAL SYSTEMS EQUATION AND SOLVABLE POTENTIALS EserKÖRCÜK M.Sc, Engineering Physics Department Supervisor: Assists. Prof. Dr. Ramazan KOÇ January, 2001, In this thesis, the solution of the dynamic system equations of physics have been studied by using algebraic and numerical methods. In recent times Lie algebraic techniques have been used to construct complex quasi exactly solvable potentials with real spectrum. In our study, we find the solution of the several different Schrödinger equations using the method of Lie algebra and show how the use of Lie algebra helps in simplifying the eigenvalue problem. In the present study, we begin with a specific differential realization of the SU(l,l)«SO(2,l) algebra which can be used to derive the second order differential equation. Then apply variable and similarity transformations to the group generators in order to recover the Schrödinger equations for various potentials. We also demonstrated that non-Hermition PT symmetric Hamiltonians have real eigenvalues. In addition, the two well-known non linear equations, the Heat and Lorenz equations are solved by numerical Runge Kutta 4 method and via Mathematica in physics. The effects of parameters and the initial conditions are examined. Finally, we review the topological analysis of data generated by a dynamical system operating a chaotic regime. UlKey Words: Lie Algebra, Realization of SO(2,l), PT Symmetric Hamiltonians and Dynamical System. IV
Mappings between potentials
ABSTRACT MAPPINGS BETWEEN POTENTIALS KOÇAK Mehmet M. Sc. in Engineering Physics Supervisor: Assoc. Prof. Dr. Bülent GÖNÜL September 2002, 65 pages In this work we scrutinize applications of the point canonical transformations (PCT), which have received a tot of attention in the literature recently. The method has been applied to exactly solvable central and non-central potentials together with quasi-exactly solvable potentials. The PCT technique has led to new insights in the studies of physical problems posed in this thesis. The applications allow something of a systematic approach enabling one to recognize the equivalence of superficially unrelated quantum mechanical problems. Keywords: Point Canonical Transformation, quasi-exactly solvable potentials, exactly solvable central and non-central potentials. m
Investigation of thermally stimulated luminescence characteristics of synthetic and natural quartz
Quartz is one of the most important synthetic and natural crystals used in thermally stimulated luminescence studies, shortly named thermoluminescence (TL), and TL age estimation of historical samples which include the quartz minerals. Natural quartz minerals are highly found in the crust of the earth, the historical vestiges and meteors. It exhibits a number of TL peaks when quartz is heated from room temperature to 500oC. In this work, thermally stimulated luminescence characteristics of synthetic quartz which is purchased from Aldrich Company and natural quartz extracted from ceramics of Kubad Abad palace, Beyşehir, Konya, Turkey were carried out for different aims. The first aim was to see the stabilities of TL peak intensities and kinetic parameters of synthetic and natural quartz at different annealing temperatures. The second aim was to investigate the effects of thermal treatments on the TL intensity and kinetic parameters of natural quartz. The thermoluminescence dose responses of synthetic and natural quartz after different annealing protocols and the effects of heating rates on the thermoluminescence characteristics of synthetic and natural quartz constitute the third and fourth aim of this thesis, respectively.
Development of new sensitive thermoluminescent materials for radiation dosimetry
In this work, the thermoluminescent properties of undoped, and rare earth and metallic elements doped some alkaline earth borates were studied. The following materials BaB4O7, LiB3O5, Li2B4O7, MgB4O7 and CaB4O7 were synthesized by solid state and melting methods in air condition. The X-ray diffractometer method was firstly used to characterize and identify the products and then the various metals and rare earth elements were doped to enhance the thermoluminescence (TL) sensitivity of developed materials. Some of the TL properties of developed phosphors were studied in detail. Comparative TL studies of these compounds were shown that the Ce-doped BaB4O7 and Al-doped LiB3O5 compounds have higher TL sensitivity than the others. In addition, after the investigation of TL properties of Ce-doped BaB4O7 and Al-doped LiB3O5 samples, they seem as a good promising TL detector for different dosimetric applications owing to its simple glow curve structures with high sensitivity, the absence of thermal fading even at elevated temperatures, reduced light sensitivity, re-usability with excellent reproducibility and chemical stability. Therefore, it was assumed that the obtained Ce-doped BaB4O7 and Al-doped LiB3O5 crystal are quite suitable for use in high dose measurements in medical or industrial areas. The trap parameters namely the order of kinetics (b), activation energy (E) and frequency factor (s) associated with the glow peaks of some TL samples were also obtained by computer glow curve deconvolution (CGCD) method.Keywords: Thermoluminescence, Dosimetry, Alkaline earth borates
Investigations on compositional, structural and optical properties of In2S3 films produced by spray pyrolysis method at different substrate temperatures
In this study, In2S3 films were prepared by spray pyrolysis technique and their compositional, structural, and optical properties were investigated by using different methods. The In2S3 films were obtained on glass substrates at various substrate temperatures in the range of 250-350 ºC. The compositional analysis of the chemicals was made by EDX method. The EDX results taken from an area on the film indicated that the film is composed of O, Na, and Si in small amounts, and also provided the ratio of the In (indium) to S (sulphur) on the film. The optical properties of In2S3 films were examined from optical absorption coefficient data using double beam visible spectrophotometer. The band gap energy of the In2S3 films was found to be between 2.61 eV and 2.71 eV. The crystal structure of the In2S3 film samples were studied by SEM and X-ray diffraction peaks. In addition, In2S3 films at different annealing temperature in O2 flow were transformed into In2O3 films by thermal oxidation.
SR1 atlas TRT development and test facility
The Transition Radiation Tracker (TRT) is particle tracking detector of the ATLAS Inner Detector which is designed as a robust and powerful gaseous detector that provides tracking through individual drift-tubes (straws) as well as particle identification via Transition Radiation (TR) detection. The TRT consists of 370000 straw proportional tubes of 4 mm diameter with a 30 micron anode wire, which operates with a Xe/CO2/O2 gas mixture at a high voltage of approximately 1.5 kV. This detector enters a new area that requires it to operate at unprecedented high rates and integrated particle fluxes. Full functionality of the detector over the lifetime (10 years) of the experiment is demanded.This MSc. thesis presents development, testing process and cosmic data analysis of a replica has been built in an above-ground laboratory environment in SR1 at CERN.
Properties of electrodeposited metalic systems(Schottky diodes) on semiconductor substrates
In this study, by using n-type Si substrate with (100) orientation, 150 nm thickness and 10-20 ?m resistivity and chromium doped, thin film Schottky diode system (Cr/n-Si SBHs which is electrochemically formed on n-type Si) is constructed and characterized.In the electrical characterization of this diodes, the current ?voltoge (I-V) and the capacitance ? voltage (C-V) measurements are done.The basic diode parameters such as ideality factor (n) and barrier height (?b) were consequently extracted from electrical measurements. It has been shown that the ideality factors increased and barrier heights decreased with the decreasing temperatures, on the basis of the thermionic emission (TE) theory.The homogeneity or the uniformity of the Schottky BH is an issue with important implications on the theory of Schottky barrier formation and important ramifications for the operation of Schottky barrier diodes and contacts. Thus, provided semiconductor substrate is well characterized, the homogeneous Schottky BH may be obtained even from the I-V characteristics of one contact. For this purpose ,Cr/n-type Si SBHs with a doping density of about 1.25x1015 cm-3 is prepared and the linear region with large BHs is used. The electrical characterisitics of Cr/n-type structures were investigated in the wide temperature range (80-320 K) by steps of 20 K.Key words: Silicon, Schottky barrier diodes, Electrodeposition Method.
Differential thermal analysis instrument design
In this work, thermal analysis methods are introduced and differential thermal analysis (DTA) is briefly investigated, designed and constructed. The instrument then checked with native sulphates which are CaSO^.^O, MgSO^.TE^O, MgSC^.I^O, CuSO^.Sf^O, FeSO^.Tl^O, NiSO^.TI^O and ZnSO^O. Analysis have been carried out to the temperature range of (room temperature - 350 C) and the exponential heating rate is used. The obtained DTA curves are compared with literature. As seen that, the resultant curves which are obtained as same as the available documents. The minimum detectable sample is found as 20 mg.Keywords: Thermal analysis, DTA,
Developing a computer programme for simulating the reflectance and the transmittance of N-Layered systems
This study Is the computer simulation of the method developed by F. Abeles to represent the optical multilayers as 2X2 matrices to calculate the overall reflection and transmission characteristics of an n-layered optical system for a selected wavelength region. It Is assumed that all layers are made of non-absorbing, plane-parallel sided dielectrics. The number of layers are unlimited. The programme Is developed in Fortran 77 language and performed on an IBM compatible PC. The results are represented In graphical form showing the variation of reflectance with wavelength.Key Words: Optical Coatings, Reflectance, Transmittance, Computer Programme
The Determination sensitizing centers and band gap of the photoconductive materials
ÖZET FOTOILETKEN MALZEMELERİN HASSASLAŞTIRMA MERKEZLERİNİN VE BAND ARALIKLARININ HESAPLANMASI YAZICI Ahmet Necmeddin Yüksek Lisans Tezi, Fizik Mühendisliği Bölümü Tez Yöneticisi: Doç. Dr. Ata SELÇUK Şubat 1993, 96 sayfa Bu çalışmada, yüksek vakuum ve yüksek sxcaklik koşullarında Selenyum (Se) tozları Klor (Cl) tozları ile karıştırılıp Selenyum fotoiletkeni geliştirildi. Aynı şartlar altında Çinkosülfür (ZnS) ve Çinkoklörür (ZnCİ) tozları karıştırılıp Çinkosülfür fotoiletkeni yapıldı. Geliştirilen fotoiletkenler İşığa karşı oldukça hassastırlar. Bu fotoiletkenlerdeki hassaslaştirma merkezlerinin yoğunluğu Kapasitör-Voltaj (C-V) ve sinırlandırılmiş boşluk yükleri methodları kullanılarak bulundu. Se ve ZnS'nin yasak bölgesindeki hassaslaştirma merkezlerinin enerji seviyeleri dalgaboyu ile f otoiletkenlik uyarımının değişmesi methodu kullanılarak elde edildi. Hassaslaştirma merkezlerinin yoğunluğu ışık yoğunluğu ile düzgün değiştiği görüldü; Se ve ZnS fotoiletkenlerinin band enerji değerlerinin teorik değerleri ile çok iyi uyum içinde olduğu bulundu. Anahtar Kelimeler: Birleşme merkezleri II, Hassaslaştirma merkezleri, Fotohassaslık, Se, ZnS iv
Design and fabrication of mos solar cells
ABSTRACT DESIGN AND FABRICATION OF MOS SOLAR CELLS TÜTÜNCÜLER, Hayriye M. S in Physics Engineering Supervisor: Assoc. Prof.Dr. M. Sadettin ÖZYAZICI February 1994, 81 pages In this thesis, effects of insulating (oxide) layer on Schottky barrier (metal -semiconductor contact) has been investigated. To make this investigation more specific minority carrier metal -oxide-semiconductor (MOS) solar cells were designed and fabricated in the form of Al-oxide-p-type silicon crystal. Resistivity of samples were measured before fabricating MOS solar cells. Aluminum coating was made by Vacuum Coater System with Diffusion Pumping System. To maximize the efficiency of the MOS solar cell, the open circuit photovoltage, short circuit photocurrent and the fill factor must be as high as possible when the total incident light energy is kept constant. But these factors depend on the same parameters and related to each other. When one parameter is increasing as a function of certain parameter, the others may be decreasing. Therefore, straightforward maximization of efficiency is not possible. To see the effects of insulating layer thickness on the short circuit current, different oxidation techniques were used. After device fabrication was completed I-V and C-V iiicharacteristics of solar cells have been measured. Open circuit voltage(VQC) and short circuit current (Iscj which affect the conversion efficiency have been determined. Experimental results showed that presence of positive charges in oxide layer enhance the Voc as indicated by the increase in barrier height. High barrier height decreases the dark current altering the I-V characteristics in the dark. Efficiencies of MOS solar cells were calculated as 7.3 %. This value is low as compared to published results. The reasons of getting low conversion efficiencies have been also discussed. Key words: MIS/MOS solar cells, photocurrent, photovoltage, efficiency. IV
Methods for solution of Schrödinger equation with position dependent mass (PDM)
In this study, construction of PDM Schrödinger equation has been examined starting from the kinetic energy operator approximations. In addition to this, the role and improvement of the Schrödinger type equations? solutions have been discussed.Some of the most common methods used in order to solve Schrödinger type equations have been explained by using important articles. The potentials and the mass functions used have been emphasized. Also, the opportunity of comparing the studies have been given.To solve PDM Schrödinger equation which has been transformed in the form of the constant mass Schrödinger equation by changing coordinate and wave function is discussed for physical acceptability. Although it was expected to have different results from both of the experiments, the same eigenvalues have been found. This situation caused the improvement of a new method without transformation. The method improved by modifying Taylor Expansion Method is called Asymptotic Taylor Expansion Method.PDM Schrödinger equation has been solved by using Asymptotic Taylor Expansion Method for harmonic oscillator potentials. Asymptotic analyze has been done for four different Hamitonians and highly accurate energy eigenvalues and wavefunctions have been obtained. As a result of this, Asymptotic Taylor Expansion Method has been proved very useful to determine energy eigenvalues and wavefunctions in Schrödinger type equations.
Determination of trapping parameters from thermoluminescence glow curves by computer glow curve deconvolution method
In the given study, the synthetic glow curves were numerically obtained by directly solving the differential equations of thermoluminescence (TL) process without the use of approximating functions that have no physical meaning after different heating rates. The synthetic glow curves include a single TL glow peak. All of the simulated glow curves were analyzed by a glow curve deconvolution (fitting) program. The results of curve fitting program were compared with the input values to obtaining whether it reflects correct values of them or not. It was observed that the agreements between input parameters and results of curve fitting program are very good when the input parameters were chosen as very close to the first-order (An<
Phase-equivalent supersymmetric deep and shallow potentials
ABSTRACT PHASE-EQUIVALENT SUPERSYMMETRIC DEEP AND SHALLOW POTENTIALS ÖZER Okan M. Sc. in Physics Engineering Supervisor: Assoc. Prof. Dr Bülent GÖNÜL July 1999, 80 pages In this work we review theoretical formulation of the Supersymmetric Quantum Mechanics, which has received a lot of attention in the literature recently, and apply it to the determination of a shallow potential which is phase-equivalent to a deep potential, whose bound spectrum is identical except for the ground state which is suppressed. With this method, the non-physical Pauli forbidden bound states encountered in the spectrum of any potential can be eliminated, preserving the phase shift. The present approach is exact and provides differential relations between the wavefunctions of the two types of potentials. The method is applied to the a+a scattering, the deuteron and 11Be systems. We show that the deep potentials involving unphysical bound states and its supersymmetric, shallow, phase-equivalent partner excluding Pauli forbidden states give very similar physical quantities, although the corresponding eigenstates differ iiiin the node-number. This lends support to two nearly equivalent treatments of the Pauli principle. The supersymmetry aspect of nuclear interactions in the light of the calculation results obtained is discussed. Keywords : Supersymmetric Quantum Mechanics, Phase-Equivalent Potentials. IV