Physics Commons^™

Double Transition Effect In Anderson Transition, Hüseyi̇n Aktaş

Turkish Journal of Physics

In this work we have studied the electronic mobility \mu within a completely disordered lattice system by using the strong interatomic hopping potential V(r) = ( - {\frac{{r}}{{a_{o}} }}) \exp( - r / a_{o} ) for site representation of the Hamiltonian. It is shown that a metallic system of a completely disordered lattice first goes insulating and then goes back to metallic again at higher atomic density \rho .

Autoionization Resonances In The Simultaneous Excitation-Ionization Of Helium, Mevlut Dogan, Albert Crowe

Turkish Journal of Physics

The effect of autoionizing states on excitation-ionization processes has been investigated experimentally by observation of the electron impact ionization process leading to He^{ + }(2p) with the excitation energy region in helium corresponding to doubly excitated states above the second ionization threshold. Also, the process arising from the decay of the doubly excited `parity unfavoured' (2p^{2})^{3}P state of helium, is studied.

Magnetization Measurements On Electrodeposited Cu_{1 - X}Co_{X} Alloy Films, Ömer F. Bakkaloğlu, İsmai̇l H. Karahan, Hasan Efeoğlu, Muhammet Yildirim, Uğur Çevi̇k, Yahya Kemal Yoğurtçu

Turkish Journal of Physics

The magnetic properties of Cu_{1 - x}Co_{x} alloy films prepared by electrodeposition technique were investigated by Alternating Gradient Force Magnetometer. The magnetization curves of Cu_{0.94}Co_{0.06}, Cu_{0.87}Co_{0.13} and Cu_{0.74}Co_{0.26} films were easily saturated while the other Cu_{1 - x}Co_{x} samples with x= 0.17, 0.19 and 0.21 had more inclined magnetization curves. The saturation magnetization value of Cu_{1 - x}Co_{x} film increased with increasing Co content in the film. The minimum values of the ratio of remanence to magnetization and the coercive field were determined in the Cu_{0.81}Co_{0.19} alloy film among the others. The ferromagnetic order in the Cu_{1 - x}Co_{x} films …

A Theoretical Analysis Of Transverse Mode Control In Waveguide Gas Lasers, Erol Taşal, M. Selami̇ Kiliçkaya

Turkish Journal of Physics

Theoretical of multiple transverse mode laser oscillation involving spatially varying gain and loss are investigated. The effect of gain and loss distribution on mode competition is analyzed. A theoretical analysis of laser transverse mode competition is investigated from the perspective of the spetial overlap of modes with a transverse gain-loss distribution. The dominant mode of laser oscillation is the mode that is stable under small perturbations.

Impurity Conductivity In Semiconductors Resulting From Radiant Excitation, Vakhab T. Toulanov, Aziza Sh. Davletova, Lesbek T. Tashimov, Kamila A. Ortaeva

Turkish Journal of Physics

This paper deals with the derivation of common formulae for induced impurity photosensibility with an arbitrary set of energy levels in the semiconductor gap. We give the expression for the real recombinational situation with two types of impurity levels as well. The basic properties and certain common peculiarities concerning induced photoconductivity in semiconductors are under consideration.

Electron Impact Double Ionization Of Helium From [E, (3-1)E] Experiments}, Mevlut Dogan

Turkish Journal of Physics

Electron impact double ionization of helium has been observed in an [e,(3-1)e] experiment at an incident electron energy of 200 eV. 110 eV scattered and 10 eV ejected electrons are observed in coincidence without detection of the second ejected electron (1 eV). Present and previous observations are discussed.

Directional Solidification Of Pure Succinonitrile And Succinonitrile- Salol Alloys, İbrahi̇m Karaca, Emi̇n Çadirli, Hasan Kaya, Necmetti̇n Maraşli

Turkish Journal of Physics

Pure succinonitrile (SCN) and succinonitrile-salol alloys with four different concentrations of salol were unidirectionally solidified at five different growth rates in a temperature gradient. The microstructure parameters, viz., the primary dendrite arm spacing \lambda _{1}, dendrite tip radius R and mushy zone depth d, were measured. The dependence of the microstructure parameters on the solidification parameters for pure SCN and SCN-Salol alloys were determined via linear regression analysis. The results are compared with published data.

Influence Of Above-Molecular Structure, Electronic And Ionic Phenomena On Durable Properties Of Polymer Dielectrics In The Electric Field, T. M. Veliyev, S. A. Abasov, M. J. Zeynalova, E. Hali̇lova, H. Memedov, I. Askerov, S. Aydoğu

Turkish Journal of Physics

Influence of above-molecular structure (AMS) on electrothermoluminescence, the altering time and the mechanic time of polymer dielectrics in strong electric fields that depend on temperature have been investigated. It has been shown that change of AMS considerably influenced the processes of injection and stabilization of charges as well as the solidity properties of polymers. It has been determined that the relaxation translations in large spherolite samples were observed at lower temperatures than the relaxation translations in small spherolite samples.

The Resonance Bremsstrahlung Of A Fast Charged Particle In A Medium, Khamidbi M. Beshtoev

Turkish Journal of Physics

The bremsstrahlung of a fast charged particle in the medium with dielectric permittivity \epsilon at velocities v \ge \frac{c}{n} (\mbox{Re}\epsilon = n^2) was considered. Bremsstrahlung radiation has singularity at \beta = \frac{1}{n \cos\theta} (\beta = \frac{v}{c}, \theta is an angle of the bremsstrahlung.) and is interpreted as resonance bremsstrahlung with the width characterized by Im\epsilon = \epsilon_2; and smaller \epsilon_2 is, the higher the peak of the resonance. The angle distribution of the bremsstrahlung is determined by \cos \theta = \frac{1}{n\beta} and \theta coincides with the angle of Cherenkov radiation. At \beta = \frac{1}{n} the resonance bremsstrahlung goes in the …

Properties Of Mos Capacitors Produced On Sige Formed By Ge-Implanted Si, M. Şahi̇n, Serhat Özder, Raşi̇t Turan

Turkish Journal of Physics

Metal-oxide-semiconductor (MOS) capacitors fabricated on Ge-implanted Si have been investigated by using C-V and G-V measurements. The control sample on pure Si substrate yielded normal C-V and G-V characteristics. The Ge-implanted MOS samples exhibited anomalous C-V and G-V behavior. The C-V curves of the samples were strongly frequency dependent both in the accumulation and inversion regions. They shift almost in parallel to higher values with decreasing frequency, reaching the oxide capacitance value in the quasi-static (QS) measurement. A band structure and equivalent circuit model were introduced to explain this and other features of the experimental observations. It is shown that …

Features Of The Compound Multiplicity Of The Interactions Of ^{24}Mg And ^{28}Si Ions With Emulsion Nuclei At 4.5a Gev/C, N. N. Abd-Allah, M. Mohery

Turkish Journal of Physics

The present paper deals with the interactions of ^{24}Mg and ^{28}Si nuclei at 4.5A GeV/c with emulsion. Some characteristics of the compound multiplicity given by the numerical sum of grey and shower particles have been investigated. The obtained results indicate that the compound multiplicity distribution is consistent with KNO-Scaling and its width increases with the size of the projectile nucleus.The dependence of the average compound multiplicity on the numbers of black and the grey particles and the sum of them is obvious and the values of the slope has been found to be independent of the projectile nucleus.

Effect Of Carrier Concentration Dependant Mobility On The Performance Of High Electron Mobility Transistors, Mustafa Erol

Turkish Journal of Physics

The influence of the sheet carrier concentration dependence on mobility on the performance of High Electron Mobility Transistor (HEMT) structures is theoretically modeled. The model basically takes into account both the drift and diffusion part of the overall drain current. The normalised drain current and normalised transconductance are found to be greatly affected by the carrier concentration dependant mobility.

Factors Affecting Radon Concentration In Houses, Abdel-Latif Al-Sharif, Y. S. Abdelrahman

Turkish Journal of Physics

The dangers to the human health upon exposure to radon and its daughter products is the main motivation behind the vast number of studies performed to find the concentration of radon in our living environment, including our houses. The presence of radon and its daughter products in houses are due to various sources including building materials and the soil under the houses. Many factors affect radon concentration in our houses, the elevation above ground level,ventilation, building materials and room usage being among these factors. In our paper, we discuss the effect of elevation above ground level, room usage and ventilation …

Path Integral Treatment For Spinless Relativistic Equation In The Two Component Theory, M. Merad, T. Boudjedaa, Lyazid Chetouani

Turkish Journal of Physics

In this paper we have set up a path integral formalism for Feshbach-Villars equation by using the fermionic Schwinger model for Pauli matrices which describe an isocharge symmetry. This choice is made in analogy with spin model and the coherent state representation is then used. We have also given a general method of treating the problem of vanishing scalar potential by reducing it the to non-relativistic case and then, via Foldy-Wouthuysen canonical transformation, an explicit solution is constructed. The free case and constant magnetic field interaction are explicitly exposed. In each cases the propagators are evaluated and the energy spectrum …

Optical Transmission Measurements On Glow-Discharge Amorphous Silicon Nitride Films, İlker Ay, Hüseyi̇n Tolunay

Turkish Journal of Physics

Hydrogenated amorphous silicon nitride films have been prepared by the glow-discharge decomposition of ammonia/silane gas mixture. From optical transmission measurements in the wavelength range from 400 nm to 1100 nm refractive indices absorption coefficients and optical Tauc gaps of the films have been obtained. A systematic investigation of optical parameters has been carried out as a function of the nitrogen content of samples.

Determination Of The Trapping Parameters Of Glow Peaks Of Caf2:Dy(Tld-200) By Using Computer Glov Curve Deconcolution Method, A. Necmeddi̇n Yazici, M. Yakup Hacii̇brahi̇moğlu

Turkish Journal of Physics

Computerized glow curve deconvolution method is used to determine the number of peaks, the order of kinetics b, the activation energy E_a,frequency factor s and number of the trapped electrons n_0 associated with the glow peaks in single crystal of CaF_2:Dy (TLD-200). Glow curve analysis indicate that the glow curve in the temperature region between room temperature and 250 ^oC can be best described as a superposition of six peaks. First five peaks are described by first-order kinetics and sixth peak general-order kinetic. The number of trapped electrons, activation energies and frequency factor for individual glow peaks are as follows: …

Preparation Of Pb Doped 110 K Phase Bisrcacuo Thick Films By Screen Printing, Ertan Şahi̇n, Necdet Baştürk

Turkish Journal of Physics

Thick Films of Bi_2Sr_2Ca_2Cu_3O_x were obtained on cleaved MgO (100) substrates from a component gel of stoichiometric composition with partial Pb substitution of Bi. Formation employeed screen printing method. Films were subjected two step annealing at temperatures above 850^oC and 880^\oC for the formation of the crystal structure and to attain superconducting properties. X-ray diffraction patterns and R-T measurements showed coexistence of the (2212) and (2223) phases for most of the films. Metallic behaviour in resistance and 110 K onset temperature were observed for good quality films with a completed superconducting transition between 78-103 K. Critical current densities were found …

Vacuum Cryostat's Pressure Dependent Dark Conductivity Measurements On A-Si:H And A-Sin:H Films, İlker Ay, Hüseyi̇n Tolunay

Turkish Journal of Physics

The electrical properties of a-Si:( H ) and a- SiN ):( H ) films prepared by plasma deposition from SiH_4+NH_3 gas mixtures have been investigated. We observed anomalous peaks in the temperature dependent dark conductivity curves of annealed a-Si:H and a-SiN:H samples when the temperatures were increased from 90 K to room temperature at a constant heating rate. To study the surface adsorption effect, vacuum cryostat pressure dependence of these peaks are investigated. We have also studied the effect of nitrogen on these observed peaks in dark conductivity.

Reasoning Of Young Adults And Introductory Physics: What’S The Connection?, Vicki L. Plano Clark

Research in Physics Education Group

Moshman's discussion in his chapter from the Handbook of Child Psychology (1998) is very relevant to my work with young adults at UNL and to my interests in physics education. While there are many possible topics upon which I could write in this essay, one statement from this chapter in particular resonated with me and will serve as the starting point of my essay. This statement was as follows (emphasis added):

"Legal thinking may be defined as thinking aimed at determining what the law requires or forbids. It is often argued that legal education should be aimed at teaching a …

Field And Polarization Effects Arising In Neutrino-Lepton Processes In A Magnetic Field, V. A. Gusseinov

Turkish Journal of Physics

We discuss the effects arising in the neutrino-lepton processes (\nu_{\mu}+e^{-} \rightarrow \nu_{e}+\mu^{-} and \overline{\nu}_{e}+e^{-}\rightarrow\overline{\nu}_{\mu}+\mu^{-}) in a constant uniform magnetic field in the framework of the Weinberg-Salam-Glashow model. It is shown that in the case of a superstrong magnetic field and for the muon producing on the ground Landau level the leading term of the cross section asymptotics of the \nu_{\mu}-process does not depend on the field intensity and it effectively describes the one-dimensional free process. In the \nu_{\mu}-process the muons with the spins oriented opposite to the direction of the field are mostly produced. The electrons with the spins oriented …

Is There An Age Of The Universe Problem After The Hipparcos Data?, Murat Özer

Turkish Journal of Physics

We have reanalyzed the age of the universe problem under the assumption that the lower limit on the age of the globular clusters is \sim11 Gyr, as predicted by the recent Hipparcos data. We find that the globular cluster and the expansion ages in a standard \lambda=0 universe are consistent only if the present value H_0 of the Hubble constant is \leq 60{\rm kms}^{-1}Mpc^{-1}. If H_0>60{\rm kms}^{-1}Mpc^{-1} some kind of modification of the standard \lambda=0 model is required. Invoking a (time-independent) cosmological term \lambda in the Einstein field equations, as has been done frequently before, we have found that …

Magnetoresistance Measurements On Electrodeposited Co_X Cu_{1-X} Alloy Films, Ömer F. Bakkaloğlu, İsmai̇l H. Karahan

Turkish Journal of Physics

Co_x Cu_{1-x} alloy films were prepared by using electrodeposition technique. The variations of Co and Cu contents of the films were investigated as functions of bath pH and Co content. The compositions of the alloy films were determined using an atomic absorption spectrophotometer. The crystal structures of the alloy films were analyzed using a Cu (K \alpha )-X-ray diffractometer. The diffraction lines observed were only those of copper component in the alloy films. All three films showed negative magnetoresistance and a giant magnetoresistance effect on the order of 1% in Co_{0.26} Cu_{0.74} and 1.7% in Co_{0.19} Cu_{0.81} alloy films at …

Multiple Structures Of (110) Csl Twist Boundaries In Fcc Metals, A. Ghafoor, B. A. S. Faridi, S. A. Ahmad

Turkish Journal of Physics

The geometry of different possible structures of (110) fcc twist boundaries is explored. Computer simulation of all possible low energy structures have been carried out for \Sigma=3 and \Sigma=9 twist boundaries using many-body potentials representing copper, silver and gold. Low symmetry structures are found to have lower energies than the high symmetry CSL structures.

A Novel Technique For The Preparation Of Textured Yba_{2}Cu_{3}O_{7-\Delta} Superconductor, Naheed Kouser, Saadat Anwar Siddiqi, Asghari Maqsood

Turkish Journal of Physics

Textured samples having composition of YBa_{2}Cu_{3}O_{7-\delta} were prepared by using a novel technique of heating the samples in a thermal gradient which varies linearly between 930-950 ^oC over a distance of 5 cm. The samples were characterized by X-ray powder diffraction analysis, temperature dependent resistivity and magnetic susceptibility measurements, and scanning electron microscopy. XRD analysis shows that sample heated between 930-935 ^oC has tetragonal symmetry and all other three samples show orthorhombic symmetry. Samples heated in temperature gradient of 935-945 ^oC aligned along the c-axis. The orthorhombic samples exhibited zero resistance above 86K with short transition width and samples heated …

Successive Toroidal Compactifications Of A Closed Bosonic Strings, N. Mebarki, A. Taleb, H. Aissaoui, Nadir Belaloui, M. Haouchine

Turkish Journal of Physics

Successive toroidal compactifications of a closed bosonic string are studied and some Lie groups solutions are derived.

Multiparticle Equations For Scalar Particles, Valery Nikolaevich Kapshai, Alexander Ivanovich Fursin

Turkish Journal of Physics

Multiparticle equations for scalar particles are derived in the framework of the Lagrangian formalism of field theory as a consequence of the Dyson-Schwinger equations for the generating functional of Green's functions. The general form of the n-particle equation is determined. The formula for the kernel of the equation is obtained. It makes possible to use the functional methods for the investigation of the equation. It is proven that the equation is correct in the lower orders for two-particle Green's functions.

Zeros Of Scattering Amplitude For A Spin-Dependent Gaussian Potential, Nilufar Farhat Hossain, Hasna Banu, A. K. Halder

Turkish Journal of Physics

In the proposed model, polarization in the scattering amplitude for a Gaussian potential including spin is considered. The problem of scattering amplitude is formulated in two different ways: the first and second Born approximations along with their high energy limits and the eikonal approximation including Wallace corrections. A comparison of the numerical zeros of the scattering amplitude computed in the above two approximations is studied in the complex momentum transfer plane. An analysis of the zero trajectories shows that the contribution of the spin part in the potential is quite significant at high energies whereas at low energies the spin-part …

Beta Spectrometers With Surface Barrier Detector And Plastic Scintillator: Applications To ^{90}Sr,^{204}Tl,^{210}Pb And ^{14}C, Cüneyt Çeli̇ktaş

Turkish Journal of Physics

In this work, a comparison of responses between a spectrometer using Si Surface Barrier Detector (Si SBD) and a spectrometer using Plastic Scintillator (PS) is given. Experimental pulse height spectra of beta particles from ^{90}Sr,^{204}Tl,^{210}Pb and ^{14}C pure beta sources has been obtained separately. By comparing obtained spectra, the priority of obtaining the beta spectra among them is discussed. This work is related to the spectral response of beta spectrometers to pure beta sources.

Mössbauer-Effect Study Of Fine Atomic Structure Of Fe-Ni-C Alloys, K. G. Binnatov, A. O. Mekhrabov

Turkish Journal of Physics

Fine atomic structure of Fe-Ni-C alloys containing of 30-36 wt. % Ni and 0.1-1.0 wt. % C have been analysed by means of a nuclear \gamma -resonance method. The alloys under investigation were in austenite phase. The study shows that the effective hyperfine magnetic field H_{eff} on the ^{57}Fe nuclei is affected by the presence of C atoms in Fe-Ni alloys and the mean value of H_{eff} fields increase with increasing of C element content in these alloys. It has been detected that increase in carbon content in Fe-Ni alloys leads to a broadening of Mössbauer absorption lines. On the …

Cation Distribution And Magnetisation Study Of Nd^{+3} Substituted Zn-Mg Ferrites, B. P. Ladgaonkar, P. N. Vasambekar, A. S. Vaingankar

Turkish Journal of Physics

Polycrystalline ferrites Zn_{x}Mg_{1-x}Fe_{2-y}Nd_{y}O_{4} (x = 0.00, 0.20, 0.40, 0.80 and 1.00; y = 0.00, 0.05 and 0.10) were prepared by standard ceramic method. Thecompositions,oncharacterisation by X-ray diffraction, shows formation of single phase cubic spinels. Magnetic measurement of these composition shows increase in magnetic moment n_{\beta} with Zn^{2+} concentration up to x = 0.4 and decreases thereafter. This is attributed to the existence of locallised canted spin. The compositions for x = 0.8 and 1.0 shows paramagnetic behaviour at and above room temperature. The trivalent substitution of Nd^{3+} ion causes reduction in the magnetic moment. The cation distribution of the sytem …