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Full-Text Articles in Physical Sciences and Mathematics

Radioluminescent Properties Of Cds(Ag) Crystals, Ruhi̇ Kaplan, F. Esen Özsan Jan 2000

Radioluminescent Properties Of Cds(Ag) Crystals, Ruhi̇ Kaplan, F. Esen Özsan

Turkish Journal of Physics

The radioluminescent proporties of silver-doped cadmium sulphide, CdS(Ag), crystals excited by 5.5 MeV $ \alpha $-particles from an $ ^{241}$Am radioactive source have been investigated. The emission spectra, decay profiles and thermal quenching curves were obtained accurately at temperatures between 80 K and 300 K. Two main radioluminescent emission bands centered at about 5760 \AA\ and 5940 \AA\ were observed. Their decay curves were found to be fast and nonexponential. From the thermal quenching of radioluminescence, the activation energies of centers responsible for these emissions were determined. The results are interpreted as the radioluminescence is possibly due to donor-acceptor pair …


Synthesis And Characteristics Of Nickel Manganite By Lithiation, S. V. Salvi, M. R. Parab Jan 2000

Synthesis And Characteristics Of Nickel Manganite By Lithiation, S. V. Salvi, M. R. Parab

Turkish Journal of Physics

Spinel nickel manganite has been synthesized using ceramic technique, from (2MnO$_{2}$+NiO) mixture reduced using LiAlH$_{4}$. Powder X-ray diffractometry (XRD) indicates the formation of cubic spinel (a=8.33 A^o), while IR absorption spectral features are rather broad, though similar to those of spinel. The d.c. electrical conductivity of the ceramic is much smaller than that reported for NiMn$_{2}$O$_{4}$. Even though the band gap remains the same, when the sintering temperature is increased from 950^oC to 1100 ^oC, all other changes are insignificant except that the porosity and particle size nearly halve. The characteristics of the system are discussed in terms of `lithiation'.


K-Vacancy Production In The Collision Of Highly Charged Relativistic Ions With Heavy Atoms, P. K. Khabibullaev, V. I. Matveev, D. U. Matrasulov Jan 2000

K-Vacancy Production In The Collision Of Highly Charged Relativistic Ions With Heavy Atoms, P. K. Khabibullaev, V. I. Matveev, D. U. Matrasulov

Turkish Journal of Physics

A general expression for the cross section of the inelastic collision of relativistic highly charged ion with heavy (relativistic) atoms is obtained using the generalized eikonal approximation. In the ultrarelativistic limit, the obtained formula coincides with a known exact one. As an application of the obtained result, probability and cross section of the K-vacany production in the $U^{92+} - U^{91+}$ collision are calculated.


Crystallographic Analysis Of Martensitic Transformation In Cusn Alloy, Ekrem Artunç, Seyfetti̇n Çakmak, Seval Çakmak Jan 2000

Crystallographic Analysis Of Martensitic Transformation In Cusn Alloy, Ekrem Artunç, Seyfetti̇n Çakmak, Seval Çakmak

Turkish Journal of Physics

In this study, the Kajiwara model has been applied to Cu-14.8at.\%Sn alloy with good agreement with experimental results. For this alloy, the austenite phase has a body centered cubic (bcc) lattice and the martensite phase has a monoclinic 9R superlattice. Using the lattice parameters of both phases, the calculated habit plane indices, magnitude of the lattice invariant shear and orientation relationships, have been compared with the observed results for this alloy.


An Extended Adiabatic Approach For Nuclear Reactions, Mustafa Yilmaz, Bülent Gönül Jan 2000

An Extended Adiabatic Approach For Nuclear Reactions, Mustafa Yilmaz, Bülent Gönül

Turkish Journal of Physics

In this letter, an alternative approximation is developed for the treatment of breakup process in nuclear reactions, which presents a way of evaluating non-adiabatic corrections to the adiabatic model three-body wavefunction by introducing a more consistent prescription for the continuum n-p center of mass energy. Although the present formalism goes beyond the quasi-adiabatic approach, due to the use of exact continuum channel energies, its application to deuteron involving reactions at medium energies shows that such an approach can not be used in its present form. A possible reason behind this failure is discussed.


Temperature Dependence Of Vickers Microhardness And Creep Study Of In_X Bi_{2-X} Te_3 Crystals, G. R. Pandya, S. R. Bhavsar, C. F. Desai Jan 2000

Temperature Dependence Of Vickers Microhardness And Creep Study Of In_X Bi_{2-X} Te_3 Crystals, G. R. Pandya, S. R. Bhavsar, C. F. Desai

Turkish Journal of Physics

Temperature dependence of Vickers microhardness of ln$_x$ Bi$_{2-x}$ Te$_3$ single crystals with x ranging from 0.1 to 0.5 has been studied. Loading time dependence of microhardness at different temperatures has been used for creep study in the temperature range 300 K to 400 K. The activation energy for indentation creep of the crystals has been evaluated.


The Growth Of P-Type A^{Iii} B^{Iii} C_2^{V I} Single Crystals, Beki̇r Gürbulak, Cevdet Coşkun, Seydi̇ Doğan, Aytunç Ateş, Yahya Kemal Yoğurtçu Jan 2000

The Growth Of P-Type A^{Iii} B^{Iii} C_2^{V I} Single Crystals, Beki̇r Gürbulak, Cevdet Coşkun, Seydi̇ Doğan, Aytunç Ateş, Yahya Kemal Yoğurtçu

Turkish Journal of Physics

$A^{III}B^{III}C_2^{VI}$ single crystals were grown by the modified Bridgman-Stockbarger method, a procedure similar to direct freezing in our crystal growth laboratory. $A^{III}B^{III}C_2^{VI}$ compounds are collected into two groups (III. group: TI, Ga, In and VI. group: Se, S, Te): 1. TlGaSe$_2$, TlGaS$_2$ and TlInS$_2$ have layer structure. 2. TlInSe$_2$, TlInTe$_2$ and TlGaTe$_2$ have chained structure. The main reasons such crystals grown with this method is similar to the direct freezing method because 1) quality of crystals is the same as crystals grown by other methods, and 2) growth time of crystals is shorter by about 5-10 days. None of the …


Solar Observations Made At The Malatya Station With Danjon Astrolabe, Orhan Gölbaşi, Hüseyi̇n Kiliç, Fernand Chollet Jan 2000

Solar Observations Made At The Malatya Station With Danjon Astrolabe, Orhan Gölbaşi, Hüseyi̇n Kiliç, Fernand Chollet

Turkish Journal of Physics

The first results of astrometric solar observations made at the Malatya Station with a modified version of the Paris Observatory astrolabe are presented. This campaign was conducted as part of a cooperation between Inonü University and the Paris Observatory. The astrolabe, exactly the same as the one at Santiago de Chile [1], uses two reflecting prisms instead of transparent prisms in order to be able to observe at two zenith distances of 30^o and 60^o. The time is supplied by a Global Positioning System (GPS) receiver. The measurements (Table 1, 2) made between 1993 and 1994, were used in obtaining …


Thickness Dependence Of C/A Polytwin Structures Observed In Epitaxial Oxide Ferroelectric Thin Films, S. Pami̇r Alpay, Alexander L. Roytburd Jan 2000

Thickness Dependence Of C/A Polytwin Structures Observed In Epitaxial Oxide Ferroelectric Thin Films, S. Pami̇r Alpay, Alexander L. Roytburd

Turkish Journal of Physics

Ferroelectric or ferroelastic epitaxial films undergoing a cubic-to-tetragonal phase transformation usually relax the resultant strain energy due to lattice misfit by forming a polytwin (polydomain) structure. Polydomain formation occurs at the expense of building interdomain interfaces and microstresses which develop at the film-substrate interface due to the periodic deviation of the strain. The interplay between these components results in a critical thickness for domain formation below which the polydomain structure is not stable. In this article, we investigate the film thickness dependence of a polydomain structure using a thermodynamical approach.


The Effect Of Iterative Solutions In The Quasi-Adiabatic Treatment Of Transfer Reactions Involving Deuterons, Mustafa Yilmaz, Bülent Gönül Jan 2000

The Effect Of Iterative Solutions In The Quasi-Adiabatic Treatment Of Transfer Reactions Involving Deuterons, Mustafa Yilmaz, Bülent Gönül

Turkish Journal of Physics

Using an iterative scheme, the effects of a more correct treatment of large n-p components of deuteron channel wavefunction in the continuum, which are associated with near-side contributions of transition amplitude, are investigated in the framework of the reformulated quasi-adiabatic model for the \( ^{116} \)Sn \( (d,p) \) \( ^{117} \)Sn reaction at 79 MeV bombarding energy. As the \( \ell_{n} \)-transfer rises, the far-side amplitude increases with improvements in the linear and angular momentum responce, which results in a relative suppression of the near-side components of the amplitude. Therefore, one might expect that the iteration of the quasi-adiabatic …


The Lattice Dynamics Of Bcc Titanium, Kemal Çolakoğlu, Yasemi̇n Özteki̇n Çi̇ftçi̇ Jan 2000

The Lattice Dynamics Of Bcc Titanium, Kemal Çolakoğlu, Yasemi̇n Özteki̇n Çi̇ftçi̇

Turkish Journal of Physics

Using in measurements of the phonon frequencies of bcc Titanium, the lattice dynamical calculations are performed on the same phase by using the Third-neighbour Clark-Gazis-Wallis(CGW) model. The theory is used to compute the phonon dispersion curves, the frequency spectra and the lattice spesific heat of the studied phase. The obtained results are compared with the available experimental data.


Properties Of Ag-Doped Bi_{(1.6)}Pb_{(0.4)}Sr_2ca_3cu_{(4-X)}Ag_Xo_Y (2234) Oxides Prepared By S.S.R. Method, Süleyman Bolat, E. Yanmaz, H. Cömert Jan 2000

Properties Of Ag-Doped Bi_{(1.6)}Pb_{(0.4)}Sr_2ca_3cu_{(4-X)}Ag_Xo_Y (2234) Oxides Prepared By S.S.R. Method, Süleyman Bolat, E. Yanmaz, H. Cömert

Turkish Journal of Physics

The effect of Ag-doping Bi$_{1.6}$Pb$_{0.4}$Sr$_{2}$Ca$_{3}$Cu$_{4-x}$Ag$_{x}$O$_{y}$ compounds (x=0.0-1.0), prepared by conventional Solid-State-Reaction (SSR) technique, was studied using x-ray diffraction (XRD) and electrical resistivity. The high-T$_{c}$ fraction of the 2223 phase, formed from the nominal composition of 2234, decreases with increasing Ag content. From lattice parameter calculations it follows that Ag-doping the unit cell phase of (Bi,Pb)$_{2}$Sr$_{2}$Ca$_{2}$Cu$_{3}$O$_{y}$ is limited to the value of x$\leq$0.1. The zero resistance critical temperature (T$_{c,zero}$) was determined from the resistivity curves for all samples. The value of T$_{c,zero}$ decreases slightly to 106 K for x$\leq$0.4 and when the nominal silver content increases up to x=0.7 or more …


The Interaction Of The Dipole Moment Of The Water Molecule With The Interface States Of The Cuprous Oxide/Cupric Oxide Junction, Necmi̇ Seri̇n, Tülay Seri̇n, Basri̇ Ünal Jan 2000

The Interaction Of The Dipole Moment Of The Water Molecule With The Interface States Of The Cuprous Oxide/Cupric Oxide Junction, Necmi̇ Seri̇n, Tülay Seri̇n, Basri̇ Ünal

Turkish Journal of Physics

An Au/CuO/Cu$_{2}$O/Cu sandwich structure has been obtained by growing successive Cu$_{2}$O and CuO layers on a Cu sheet. A gold metal contact was formed CuO side at pressure of $1\times10^{-6}$ Torr. Current-voltage characteristics and capacitance of the system were seen to change over a great extent due to the presence of humidity. The effect of the humidity on Au/CuO/Cu$_{2}$O/Cu is explored through the effect of water's dipole moment.


Analysis On The 2-Dim Quantum Poincare Group At Roots Of Unity, Haji Ahmedov Jan 2000

Analysis On The 2-Dim Quantum Poincare Group At Roots Of Unity, Haji Ahmedov

Turkish Journal of Physics

2--Dim quantum Poincar\'e Group $E_q(1,1)$ at roots of unity, its dual $U_q(e(1,1))$ and some of its homogeneous spaces are introduced. Invariant integrals on $E_q(1,1)$ and its invariant discrete subgroup $E(1,1\mid p)$ are constructed. $*$--Representations of the quantum algebra $U_q(e(1,1))$ constructed in the homogeneous space $SO(1,1\mid p)$ are integrated to the pseudo--unitary representations of $E_q(1,1)$ by means of the universal $T$--matrix. $U_q(e(1,1))$ is realized on the quantum plane $E_q^{(1,1)}$ and the eigenfunctions of the complete set of observables are obtained in the angular momentum and momentum basis. The matrix elements of the pseudo--unitary irreducible representations are given in terms of the …


Generalized 2d Yang-Mills Theories: Large-N Limit And Phase Structure, Masoud Alimohammadi Jan 2000

Generalized 2d Yang-Mills Theories: Large-N Limit And Phase Structure, Masoud Alimohammadi

Turkish Journal of Physics

After review the 2D Yang--Mills theories (YM$_2$) and its large--$N$ behaviour, the Generalized 2D Yang--Mills theories (gYM$_2$) and their partition functions on a general two--dimensional Riemann surface are discussed.The large--$N$ behaviour of these models is studied in weak regime, and in strong regime, we restrict ourselves to $\phi^4$ gYM$_2$. We show that this model has a third order phase transition, similar to ordinary YM$_2$ theory.


Noncommutativity In String Theory And Large Extra Dimensions, Farhad Ardalan Jan 2000

Noncommutativity In String Theory And Large Extra Dimensions, Farhad Ardalan

Turkish Journal of Physics

Noncommutativity of space coordinates of string theory are reviewed and are related to the large extra dimension solution of the hierarchy problem.


Kerr Spinning Particle, A. Burinskii Jan 2000

Kerr Spinning Particle, A. Burinskii

Turkish Journal of Physics

We give a brief review of the problems connected with the model of spinning particle based on the Kerr geometry. We consider peculiarities of the Kerr rotating black hole solution in gravity, supergravity and low energy string theory. A non-trivial supergeneralization of the Kerr-Newman solution to broken N=2 supergravity is considered. \par The problem of source of the Kerr geometry is discussed, and we consider some arguments in favor of the supersymmetric Fermi-ball model for the Kerr source based on the Witten $U(1)\times U(\tilde 1)$ field model for superconducting strings.


Global Results In Space Of Inter-Monomer Interactions For Hp Lattice Model, M. R. Ejtehadi̇, V. Shahrezaei̇, N. Hamedani̇ Jan 2000

Global Results In Space Of Inter-Monomer Interactions For Hp Lattice Model, M. R. Ejtehadi̇, V. Shahrezaei̇, N. Hamedani̇

Turkish Journal of Physics

Using the ground state candidates for Hydrophobic-Polar lattice model on a two dimensional square lattice, we exactly enumerate the native states of proteins with length up to 20 for a wide range of energy parameters. We find the reduced set of contact maps, ground state candidates, perfectly stable sequences and designability of configurations.


The Statistics Of Energy States Of A Hookean Model For Proteins, Ayşe Erzan, Erkan Tüzel Jan 2000

The Statistics Of Energy States Of A Hookean Model For Proteins, Ayşe Erzan, Erkan Tüzel

Turkish Journal of Physics

A generic model of a random polypeptide chain, with discrete torsional degrees of freedom and Hookean springs connecting pairs of hydrophobic residues, reproduces the energy probability distribution of real proteins over a very large range of energies. We show that this system with harmonic interactions, under dissipative dynamics driven by random noise, leads to a distribution of energy states obeying a modified one-dimensional Ornstein-Uhlenbeck process with reflecting boundary conditions, and giving rise to distributions of the Wigner or inverse Gaussian form. A continuum approximation leads to a path integral formulation of the problem. PACS 5.65+b,5.70Ln,87.17.Aa


Gauge Invariant Reduction And Integrability Of Sl(2 ,R)/ U(1) Wznw Theory, Chris Ford, George Jorjadze, Gerhard Weigt Jan 2000

Gauge Invariant Reduction And Integrability Of Sl(2 ,R)/ U(1) Wznw Theory, Chris Ford, George Jorjadze, Gerhard Weigt

Turkish Journal of Physics

The general solution of $SL(2,{\bf R})/U(1)$ WZNW theory is constructed by a gauge invariant reduction. This is done within both Lagrangian and Hamiltonian frameworks.


Canonical Quantisation Of The Sl(2,R)/ U(1) Gauged Wznw Black Hole Model, Christopher Ford, George Jorjadze, Gerhard Weigt Jan 2000

Canonical Quantisation Of The Sl(2,R)/ U(1) Gauged Wznw Black Hole Model, Christopher Ford, George Jorjadze, Gerhard Weigt

Turkish Journal of Physics

Gauged WZNW models are integrable conformal field theories with non-local canonical free-field transformations. Canonical quantisation requires quantum deformations.


Multi-Species Asymmetric Exclusion Process In Ordered Sequential Update, M. Ebrahi̇m Fouladvand, Farhad Jafarpour Jan 2000

Multi-Species Asymmetric Exclusion Process In Ordered Sequential Update, M. Ebrahi̇m Fouladvand, Farhad Jafarpour

Turkish Journal of Physics

A multi-species generalization of the asymmetric simple exclusion process (ASEP) is studied in ordered sequential and sub-lattice parallel updating schemes. In this model, particles hop with their own specific probabilities to their rightmost empty site and fast particles overtake slow ones with a definite probability. Using Matrix Product Ansatz (MPA), we obtain the relevant algebra, and study the uncorrelated stationary state of the model both for an open system and on a ring. A complete comparison between the physical results in these updates and those of random sequential introduced in [20,21] is made.


Nonabelian Cosmic Strings From So(3) Gauge Symmetry, Mehmet Koca Jan 2000

Nonabelian Cosmic Strings From So(3) Gauge Symmetry, Mehmet Koca

Turkish Journal of Physics

The nature of $SO(3)$ breaking into its closed subgroups and the emergence of nonabelian cosmic strings are discussed. Relevance to GUT breaking and thereby to cosmology is pointed out. Classification of cosmic strings are associated with the affine ADE Lie algebras.


Spinors And Positive Mass, Malcolm Ludvigsen Jan 2000

Spinors And Positive Mass, Malcolm Ludvigsen

Turkish Journal of Physics

As an example of how spinor methods can be applied to the positive-mass theorem, a simple, spinor-based proof of the theorem is presented for the case of a single black hole. Generalisations of the theorem are also discussed.


Cosmological Adiabatic Geometric Phase Of A Scalar Field In A Bianchi Spacetime, Ali̇ Mostafazadeh Jan 2000

Cosmological Adiabatic Geometric Phase Of A Scalar Field In A Bianchi Spacetime, Ali̇ Mostafazadeh

Turkish Journal of Physics

A two-component formulation of the Klein-Gordon equation is used to investigate the cyclic and noncyclic adiabatic geometric phases due to spatially homogeneous (Bianchi) cosmological models. It is shown that no adiabatic geometric phases arise for Bianchi type I models. For general Bianchi type IX models the problem of the adiabatic geometric phase is shown to be equivalent to the one for nuclear quadrupole interactions of a spin. For these models nontrivial non-Abelian adiabatic geometrical phases may occur in general.


From Antibracket To Equivariant Characteristic Classes, Armen Nersessian Jan 2000

From Antibracket To Equivariant Characteristic Classes, Armen Nersessian

Turkish Journal of Physics

We equip the exterior algebra of Riemann manifold by the odd symplectic structure. Then, by its use we construct the equivariant even (pre)symplectic structure, whose Poincare - Cartan invariants of the second structure define the equivariant Euler classes of the surfaces.


Chaos In Closed Isotropic Cosmological Models With Steep Scalar Field Potential, A. V. Toporensky Jan 2000

Chaos In Closed Isotropic Cosmological Models With Steep Scalar Field Potential, A. V. Toporensky

Turkish Journal of Physics

The dynamics of closed scalar field FRW cosmological models is studied for several types of exponentially and more than exponentially steep potentials. The parameters of scalar field potentials which allow a chaotic behaviour are found from numerical investigations. It is argued that analytical studies of equation of motion at the Euclidean boundary can provide an important information about the properties of chaotic dynamics. Several types of transition from chaotic to regular dynamics are described.


Skyrmions From Harmonic Maps, Wojtek Zakrzewski Jan 2000

Skyrmions From Harmonic Maps, Wojtek Zakrzewski

Turkish Journal of Physics

We describe some relations between solitonic solutions of various models in different dimensions. We present some examples and then concentrate on some of our recent work (performed in collaboration with Ioannidou and Piette) \cite{IPZ} \cite{us2} which shows how some harmonic maps from $S^2$ to $CP^{N-1}$ can be used to find nontrivial spherically symmetric static solutions of the $SU(N)$ Skyrme model in 3 dimensions and to generate some of its low energy field configurations.


The Decay Of A Black Hole As A Quantum Dissipative Process, Carl Wolf Jan 2000

The Decay Of A Black Hole As A Quantum Dissipative Process, Carl Wolf

Turkish Journal of Physics

By considering the decay of a black hole as a result of the interaction of a quantum system with a dissipative vacuum, or in terms of string theory, the interaction of localized string modes with non-local string modes, we demonstrate how the single parameter representing dissipation can be calculated in terms of known fundamental constants. In view of the uncertainty embodied in all the present theories of black hole decay it is suggested that the approach of this note might provide fresh insight to the problem of black hole decay. P.A.C.S.: 98.80-Dr Cosmology


Associations Of X-Ray Binaries With Open Clusters And Supernova Remnants, Eni̇s Tuncer, H. Guseinov, Ü. Kiziloğlu, A. O. Allakhverdiev Jan 2000

Associations Of X-Ray Binaries With Open Clusters And Supernova Remnants, Eni̇s Tuncer, H. Guseinov, Ü. Kiziloğlu, A. O. Allakhverdiev

Turkish Journal of Physics

Searching for X-ray binaries projected on open clusters (OCs) and supernova remnants (SNRs), associations of X-ray binaries with OCs and SNRs in the Galaxy are discussed. Three of the high mass X-ray binaries (HMXBs) and four of the low mass X-ray binaries (LMXBs) are projected on open clusters. Five of HMXBs and six of LMXBs are projected on SNRs. The number of the HMXB projections are less than the LMXBs, which is not expected and is surprising since the objects in this study, except the LMXBs, are all young objects. Such associations help us improve distance and age estimates of …