Physical Sciences and Mathematics Commons^™

The Theoretical Analysis Of The Second Order Coherence G^{(2)}(\Tau) And Power Stabilization Of Two-Mode He-Ne Laser, Erol Taşal, M. Selami̇ Kiliçkaya

Turkish Journal of Physics

In this study, second-order coherence and its frequency-dependent characteristics and the photon statistical properties of the two-mode He-Ne laser field are investigated.

Effect Of Nitriding On Phase Transformations In The Fe-Mn Alloys, K. G. Binnatov, I. I. Ali-Zade, A. O. Mekhrabov

Turkish Journal of Physics

We present results concerning the nitriding effects on phase transformations in Fe -- 40 at. % Mn and Fe -- 50 at. % Mn alloys. These alloys were studied by means of X-ray diffraction and Mössbauer-effect spectroscopy methods at room temperature. Results indicate that, after nitriding, in the absorption spectra of these alloys appears lines with hyperfine field H\sim 330 kOe which corresponds to the field on the ^{57} Fe nuclei in the \alpha -Fe. Annealing of the alloys at 650 ^oC temperature (nitriding temperature) in argon atmosphere do not change the form of the M\\"{o}ssbauer absorption spectra. It appears …

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.

Controlling The Optical Properties Of A Conjugated Co-Polymer Through Variation Of Backbone Isomerism And The Introduction Of Carbon Nanotubes, A. Dalton, J. Coleman, M. In Het Panhuis, B. Mccarthy, A. Drury, W. Blau, J. Nunzi, Hugh Byrne

Articles

The need to control the formation of weakly emitting species in polymers such as aggregates and excimers, which are normally detrimental to device performance, is illustrated for the example of the polymer poly(m-phenylenevinylene-co-2,5-dioctyloxy-p-phenylenevinylene), using the model compound, 2,5-dioctyloxy-p-distyrylbenzene as a comparison. Two different methods, namely a Homer-Emmons polycondensation in dimethylformamide (DMF) and a Wittig polycondensation in dry toluene, have been used during synthesis resulting in a polymer with a predominantly trans-vinylene backbone and a polymer with a predominantly cis-vinylene backbone, respectively. Photoluminescence and absorption spectroscopy indicate that the polymer forms aggregate species in solution with spectra that are distinctly red-shifted …

Effective Field Theory For The Small-X Evolution, I. Balitsky

Physics Faculty Publications

The small-x behavior of structure functions in the saturation region is determined by the non-linear generalization of the BFKL equation. I suggest the effective field theory for the small-x evolution which solves formally this equation. The result is the 2+1 functional integral for the structure functions at small x.

Electron Heating In Atmospheric Pressure Glow Discharges, Robert H. Stark, Karl H. Schoenbach

Bioelectrics Publications

The application of nanosecond voltage pulses to weakly ionized atmospheric pressure plasmas allows heating the electrons without considerably increasing the gas temperature, provided that the duration of the pulses is less than the critical time for the development of glow-to-arc transitions. The shift in the electron energy distribution towards higher energies causes a temporary increase in the ionization rate, and consequently a strong rise in electron density. This increase in electron density is reflected in an increased decay time of the plasma after the pulse application. Experiments in atmospheric pressure air glow discharges with gas temperatures of approximately 2000 K …

Xenon Excimer Emission From Pulsed Microhollow Cathode Discharges, M. Moselhy, R. H. Stark, K. H. Schoenbach, U. Kogelschatz

Bioelectrics Publications

By applying electrical pulses of 20 ns duration to xenon microplasmas, generated by direct current microhollow cathode discharges, we were able to increase the xenon excimer emission by more than an order of magnitude over direct current discharge excimer emission. For pulsed voltages in excess of 500 V, the optical power at 172 nm was found to increase exponentially with voltage. Largest values obtained were 2.75 W of vacuum-ultraviolet optical power emitted from a single microhollow cathode discharge in 400 Torr xenon with a 750 V pulse applied to a discharge. Highest radiative emittance was 15.2 W/cm². The …

Microwave Ionization Of An Atomic Electron Wave Packet, Michael W. Noel, Lung Ko, T. F. Gallagher

Physics Faculty Research and Scholarship

A short microwave pulse is used to ionize a lithium Rydberg wave packet launched from the core at a well-defined phase of the field. We observe a strong dependence on the relative phase between the motion of the wave packet and the oscillations of the field. This phase dependent ionization is also studied as a function of the relative frequency. Our experimental observations are in good qualitative agreement with a one-dimensional classical model of wave packet ionization.

A New Mechanism For Spin-Lattice Relaxation Of Heavy Nuclei In The Solid State: 207pb Relaxation In Lead Nitrate, John B. Grutzner, Kevin W. Stewart, Roderick E. Wasylishen, Michael D. Lumsden, Cecil Dybowski, Peter A. Beckmann

Physics Faculty Research and Scholarship

No abstract provided.

Report Of The State Nuclear Safety Advisor Submitted To The Governor And 120th Legislature As Of January 15, 2001, Paula M. Craighead

Maine Collection

Report of the State Nuclear Safety Advisor submitted to the Governor and 120th Legislature As of January 15, 2001

Paula M. Craighead, State Nuclear Safety Advisor, Executive Department, Maine State Planning Office, Augusta, Maine, 2001.

Contents: Introduction and Executive Summary / I. Maine Yankee Decommissioning / II. Portsmouth Naval Shipyard (PNS) / III. Low-Level Radioactive Waste (LLRW) / IV. High Level Radioactive Waste / V. Transport Routes and Safety Response / VI. Shipments / VII. Status of Federal and State Legal and Administrative Proceedings / References and Resources / Glossary

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 …

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.

Exciton Investigations And The Urbach Tails Of Gd Doped And Undoped Gase, Beki̇r Gürbulak

Turkish Journal of Physics

Absorption measurements were carried out in GaSe and GaSe:Gd samples in temperature range 10-320 K in steps 10 K. The first and the second (n=1 and n=2) excitonic levels were marked. The first exciton energies for n=1 were calculated as 2.118, 2.008 eV in GaSe, and 2.125, 2.006 eV in GaSe:Gd at 10, 320 K and respectively. The second exciton energies for n=2 were calculated as 2.140, 2.125 eV in GaSe at 10, 80 K and 2.141, 2.120 eV in GaSe:Gd at 10, 120 K and respectively. Binding energies of GaSe and GaSe:Gd were calculated as (29.46\pm 1 and 21.33\pm …

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.

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.

Measurement Of The Gluon Parton Distribution Function At Small X With Neutrino Telescopes, Gabriele U. Varieschi

Physics Faculty Works

We analyze the possibility that neutrino telescopes may provide an experimental determination of the slope λ of the gluon distribution in the proton at momentum fractions x smaller than the accelerator reach. The method is based on a linear relation between λ and the spectral index ~slope! of the down-going atmospheric muon flux above 100 TeV, for which there is no background. Considering the uncertainties in the charm production cross section and in the cosmic ray composition, we estimate the error on the measurement of l through this method, excluding the experimental error of the telescopes, to be ±0.2.

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 …

Viscous Dissipation Of Magnetosonic Waves In Solar Corona, Belinda Kalomeni, D. Özlem Hürkal, E. Rennan Pekünlü, Kadri̇ Yakut

Turkish Journal of Physics

Wave propagation and dissipation of magnetosonic waves are considered in an inhomogenous viscous coronal plasma permeated by a spatially varying magnetic field. In the linear magnetohydrodynamic approximation the dispersion relation yields two wave modes, fast and slow respectively. Depending on the physical parameters of the medium the damping length scales of the modes show varying behaviours. Damping length scales of the modes show sudden decrease at relevant heights. These drops may be due to phase mixing and resonance absorption. Wave flux density of the magnetosonic waves turns out to be of the order of 10^6 erg cm^{-2} s^{-1}. This is …

The Temperature Dependence Of Dark Conductivity In Hydrogenated Amorphous Sin_X Films, Hüseyi̇n Tolunay, İlker Ay

Turkish Journal of Physics

Thin film samples of hydrogenated amorphous silicon nitride with varying nitrogen content were prepared by conventional plasma deposition from a mixture of SiH_4 and NH_3 . The dark conductivity (\sigma_d) of the films have been measured in the temperature range 420 K - 100 K. The conductivity is thermally activated with a single activation energy down to 250 K and conduction is dominated by electrons in extended states. A strong decrease is observed sigma _d when the nitrogen content is increased.

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.

The Investigation Of The Thermoluminescence Emission Bands Of Lif:Mg,Ti (Tld-100) By A Simple Developed Model, A. Necmeddi̇n Yazici, Z. Öztürk, M. Bedi̇r

Turkish Journal of Physics

In this study, a new simple model based on the classical treatment of lattice vibrations and the Franck-Condon principle is developed to describe the shape of thermoluminescence (TL) emission bands of crystalline solids. According to developed model, shape of the emission band has a Gaussian form and depends on just two physical parameters: peak energy E_{0} and broadening of emission spectra U. In order to demonstrate the success of the developed model, the emission spectra of dosimetric material LiF:Mg,Ti (TLD-100) was also measured. Then, a computerised best-fit program including the developed model was used to analyse the emission spectra. The …

Computational Study For The Structural Change Of The System Cdte_{1-X} S_X Thin Film, Emad Khdayer Al-Shakarchi

Turkish Journal of Physics

Polycrystalline thin film of the graded system CdTe_{1-x}S_{x} for x=0,0.1,\ldots,1 are prepared by using thermal evaporation technique deposited on the glass substrate with an average thickness 3000 Å for each individual value of x . XRD technique is used with the aid of a computational program to study the phase change from cubic zinc blend structure to hexagonal wurtzite with an inversion point related to the x-value. It is found that x=0.1 gives us an inversion point in the structural change from cubic to hexagonal phase.

Null String In Curved Backgrounds, Sergey Nikolaevich Roshchupkin

Turkish Journal of Physics

We consider null string in curved backgrounds. Some exact solutions of the classical equations of motion and of the constraints for the null string in a large class of cosmological backgrounds are found.

On The Statistical Properties Of A Q-Oscillator, Abdullah Algin

Turkish Journal of Physics

Several statistical properties of the Coon-Baker-Yu (CBY) q-oscillator algebra are discussed. Particular emphasis is given to a careful derivation of second quantized particle statistics obtained via the CBY q-oscillator. It is outlined that, beside other limiting cases, the limit q = 0 of the CBY q-oscillator gives the Cuntz oscillator and the Fock space properties of both of these oscillators lead to various interesting results.

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.

Electrical Characterization Of Gate And Gate:Cu Semiconductor Compounds, Hüsnü Sali̇h Güder, Bahatti̇n Abay, Hasan Efeoğlu, Cevdet Coşkun, Şaki̇r Aydoğan, Yahya Kemal Yoğurtçu

Turkish Journal of Physics

Electrical properties of GaTe and GaTe:Cu binary compound semiconductors were investigated by Hall effect and resistivity measurements in the 77-320 K temperature range. Donor and acceptor densities, compensation ratios, acceptor ionization energies, valence band effective mass of holes and effective density of states in valence band were determined for the undoped and Cu doped samples using the single donor-single acceptor analysis of the hole concentration. Temperature coefficient of the hole mobility was determined and compared with related theories.

Optical Absorption And Photoluminescence Measurements In Inp And Inp:Fe Bulk Crystals And Inspection Of The Relations Between These Measurements, Seydi̇ Doğan, Sebahatti̇n Tüzemen, Beki̇r Gürbulak, Aytunç Ateş, Muhammet Yildirim

Turkish Journal of Physics

Optical absorption and photoluminescence (PL) measurements were carried out in both undoped and Fe-doped samples and the effect of Fe doping on absorption and PL spectra were studied. The results show that Fe or Fe-related defects behave as non-radiative recombination centers in InP. This is very important from the point of view that the control of minority carrier lifetime is possible. On the other hand, comparative analysis of the PL results with the optical absorption data show that quantitative assessment of relative PL intensities is possible with respect to Fe concentrations.

The Effect Of Phonon Drag Of Charge Carriers In In_{1 - X} Ga_{X} Sb, Sadiyar Ahmedoglu Zeynalov

Turkish Journal of Physics

The temperature dependencies of the thermal power a_{0} and thermal conductivity \kappa in two samples of In_{1 - x} Ga_{x}Sb (x=0.65 and 0.45) doped by {Te\sim } 0.001 at\%, with electron concentration n = 5.9 \cdot 10^{16} and 1.3 \cdot 10^{17} cm^{ - 3} (at 100K), have been investigated. It is shown that in In_{0.35}Ga_{0.65}Sb a_{0} increases with decreasing T below 50K. At 14K a_{0} passes through maximum and it falls sharply with decreasing T. It is shown that the maximum value of a_{0} is in agreement with the maximum value of \kappa . In In_{0.55}Ga_{0.45}Sb, starting from T = …

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.