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Articles 31051 - 31080 of 36659

Full-Text Articles in Physical Sciences and Mathematics

Four Ways To Tev Scale, S. Sultansoy Jan 1998

Four Ways To Tev Scale, S. Sultansoy

Turkish Journal of Physics

Four known types of colliders, which may give an opportunity to achieve TeV center of mass energies in the near future (10-15 years), are discussed. Parameters of the linac-ring type $ep$ and $\gamma p$ machines are roughly estimated. Some speculations on TeV scale physics are given. The physics goals of the TeV energy $ep$ and $\gamma p$ colliders are considered.

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Interaction Region And Luminosity Limitations For Thetesla/Hera E/P Collider, R. Brinkmann Jan 1998

Interaction Region And Luminosity Limitations For Thetesla/Hera E/P Collider, R. Brinkmann

Turkish Journal of Physics

No abstract provided.

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Tune Shift Limitations For Linac-Ring Type Colliders, Ö. Yavaş Jan 1998

Tune Shift Limitations For Linac-Ring Type Colliders, Ö. Yavaş

Turkish Journal of Physics

Limitations on incoherent and beam-beam tune shift values are calculated by using gaussian beam distribution for linac-ring type $ep$ colliders. The advantage of this machine is achievement of multi TeV center of mass energies in lepton-hadron interactions at sufficiently high luminosities. Tune shift puts a limit on the number of electrons per effective area for the stability of proton beam and, therefore, gives an upper bound for the luminosity.

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Main Parameters Of \Gammap Colliders, A.K. Çi̇ftçi̇ Jan 1998

Main Parameters Of \Gammap Colliders, A.K. Çi̇ftçi̇

Turkish Journal of Physics

Main parameters of TeV energy $\gamma $p colliders have been investigated for HERA+ SBLC, HERA+TESLA, HERA+e-linac, LHC+TESLA, LHC+CLIC and LHC+$e$ -linac proposals. Luminosity of $\gamma p$ collisions for these colliders are studied in terms of a distance between the conversion region and the collision point.

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A Possibility To Control The Polarization Of High-Energy Photons By Means Of A Laser Beam, G.L. Kotkin, V.G. Serbo Jan 1998

A Possibility To Control The Polarization Of High-Energy Photons By Means Of A Laser Beam, G.L. Kotkin, V.G. Serbo

Turkish Journal of Physics

The elastic light-light scattering below the threshold of the $e^+e^-$ pair production leads to a variation in polarization of hard $\gamma$-quanta traversing without loss a region where the laser light is focused. This effect can be used to control the $\gamma$-quantum polarization. Equations are obtained which determine the variation of Stokes parameters of $\gamma$-quanta in this case, and their solutions are given. It is pointed out that this effect can be observed in the experiment E-144 at SLAC. It should be taken into account and, perhaps, it can be used in experiments at future $\gamma \gamma$ colliders.

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Ordinary And Coherent Bremsstrahlung At Linac-Ring Ep Colliders, V.G. Serbo, D.V. Serebryakova Jan 1998

Ordinary And Coherent Bremsstrahlung At Linac-Ring Ep Colliders, V.G. Serbo, D.V. Serebryakova

Turkish Journal of Physics

The ordinary bremsstrahlung $ep \rightarrow ep\gamma$ can be used at the linac-ring $ep$ colliders for luminosity measurement. It is known that at high energies this process has a large correction due to beam-size effect. We have calculated this effect for $ep$ colliders of the linac-ring type. For the LHC+CLIC collider the correction exceeds 10\% for $E_{\gamma} < 0.95\;E_e$. As a rule, the bremsstrahlung of protons in the $ep$ scattering is not considered due to its small cross section. However, if the photon energy $E_{\gamma}$ becomes small enough, the number of produced photons become large because in this case the radiation is determined by the interaction of a proton with the collective electromagnetic field of the electron bunch. It is coherent bremsstrahlung (CBS). We present the main characteristics of CBS calculated for linac-ring $ep$ colliders. At the LHC+CLIC collider it should be about $1700 \; dE_\gamma /E_\gamma$ photons for a single collision of bunches at $E_\gamma \stackrel{

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Electroweak Gauge Boson Production At \Gamma\Gamma Collider, G. Jikia Jan 1998

Electroweak Gauge Boson Production At \Gamma\Gamma Collider, G. Jikia

Turkish Journal of Physics

No abstract provided.

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Hard Diffractive Photoproduction With Rapidity Gap, Ilya F. Ginzburg Jan 1998

Hard Diffractive Photoproduction With Rapidity Gap, Ilya F. Ginzburg

Turkish Journal of Physics

Hard diffractive photoproduction with rapidity gap is the best place for study of perturbative Pomeron. Some predictions of pQCD and the range of their applicability are described.

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The Heavy Higgs Effects In The Framework Of Sm, V. Borodulin, G. Jikia Jan 1998

The Heavy Higgs Effects In The Framework Of Sm, V. Borodulin, G. Jikia

Turkish Journal of Physics

No abstract provided.

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Structural And Optical Characterisation Of Vacuum Deposited Cdte Thin Films, Murat Bayhan Jan 1998

Structural And Optical Characterisation Of Vacuum Deposited Cdte Thin Films, Murat Bayhan

Turkish Journal of Physics

The structural and optical properties of vacuum deposited CdTe thin films on glass substrates were investigated. The effect of the heat treatment in air over the former properties of the layers was also examined. Grain sizes of air heated layers estimated by net broading in the XRD spectra were found to be larger than as-grown layers, confirming that grain growth had occurred during the heat treatment. RHEED patterns of the layers grown at substrate temperatures between 150°C and 170°C had a distinct \{111\} preferred orientation. As-grown CdTe layers were slightly p-type, but highly resistive. Air heat treated layers were p-type …

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Remote Sensing And Synchronous Land Surface Measurements Of Soil Moisture And Soil Temperature In The Field, N.V. Kolev, K.P. Penev, Y.M. Kirkova, B.S. Krustanov, T.G. Nazarsky, G.K. Dimitrov, C.P. Levchev, H.I. Prodanov, L.H. Kraleva Jan 1998

Remote Sensing And Synchronous Land Surface Measurements Of Soil Moisture And Soil Temperature In The Field, N.V. Kolev, K.P. Penev, Y.M. Kirkova, B.S. Krustanov, T.G. Nazarsky, G.K. Dimitrov, C.P. Levchev, H.I. Prodanov, L.H. Kraleva

Turkish Journal of Physics

The paper presents the results of remote sensing and synchronous land surface measurements for estimation of soil (surface and profile) water content and soil temperature for different soil types in Bulgaria. The relationship between radiometric temperature and soil surface water content is shown. The research is illustrated by some results from aircraft and land surface measurements carried out over three test areas near Pleven, Sofia and Plovdiv, respectively, during the period 1988-1990.

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Elastic Scattering Of 344.5 Mev ^{12}C Ions From ^{11}B Nucleus, S.A.E. Khallaf, M.A. Abdel-Rahman, S.K. Abdel-Rahman, S.W.Z. Mahmoud Jan 1998

Elastic Scattering Of 344.5 Mev ^{12}C Ions From ^{11}B Nucleus, S.A.E. Khallaf, M.A. Abdel-Rahman, S.K. Abdel-Rahman, S.W.Z. Mahmoud

Turkish Journal of Physics

The angular distribution of the elastic scattering differential cross section of 344.5 MeV $^{12}$C ions from $^{11}$B nucleus is calculated and compared with the experimental data as well as the previously published calculations. The real part of the central optical potential is derived using the double-folding and single-folding procedures assuming Gaussian forms of the nucleon-nucleon and alpha-nucleon interactions, respectively. A nuclear matter density distribution function of $^{11}$B consisting of a spherical part plus a quadrupole term is used. The inclusion of the quadrupole term is found necessary to obtain good fits to the experimental data.

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Speed Cut-Off Point For Antiforce Waves, Mostafa Hemmati, Mathues Shane Doss, Eric L. George Jan 1998

Speed Cut-Off Point For Antiforce Waves, Mostafa Hemmati, Mathues Shane Doss, Eric L. George

Journal of the Arkansas Academy of Science

A one-dimensional, three-component, fluid model has been employed to investigate the existence of a speed cut-off point for antiforce breakdown waves. The term antiforce wave is used to identify breakdown waves for which the electric field force on electrons is in the opposite direction of wave propagation. The electron fluid-dynamical equations for antiforce waves are different from those of proforce waves. This presentation will address the difference in the set of equations for proforce and antiforce waves and the method of integration of the set of equations through the dynamical transition region for antiforce waves. Also, for antiforce waves, the …

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Continuous Monitoring Of Star's Main Time Projection Chamber, Wilfred J. Braithwaite, Edwin S. Braithwaite Jan 1998

Continuous Monitoring Of Star's Main Time Projection Chamber, Wilfred J. Braithwaite, Edwin S. Braithwaite

Journal of the Arkansas Academy of Science

STAR refers to the Solenoidal Tracking instrument At RHIC (the Relativistic Heavy Ion Collider). For momenta above 500 MeV/c charged kaons are not separated from pions within STAR's Main TPC (Time Projection Chamber) by track density alone and they are poorly separated below 500 MeV/c, even when using information from other sources like the vertex tracker. Within the TPC large numbers of kaons and pions decay into muons (and undetected neutrinos). Earlier work has shown parent pions and kaons whose decays are detected within a TPC may be distinguished uniquely from each other in a two-dimensional plot of muon-emission angle …

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Stress And Structure Of Ni Monolayers On W(110): The Importance Of Lattice Mismatch, D. Sander, C. Schmidthals, Axel Enders, J. Kirschner Jan 1998

Stress And Structure Of Ni Monolayers On W(110): The Importance Of Lattice Mismatch, D. Sander, C. Schmidthals, Axel Enders, J. Kirschner

Axel Enders Publications

The combination of in situ stress measurements, low-energy electron diffraction, and scanning tunneling microscopy reveals the intimate relation between film structure and film stress for epitaxial growth of Ni on W(110) in the monolayer range. In contradiction to lattice mismatch considerations, we measure tremendous compressive stress in the pseudomorphic Ni film, where tensile film stress is expected from strain arguments. Surface stress of the film-substrate composite is proposed to be much more relevant for the description of film stress in the submonolayer range than lattice mismatch arguments are.

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Emission Of Excimer Radiation From Direct Current, High-Pressure Hollow Cathode Discharge, Ahmed El-Habachi, Karl H. Schoenbach Jan 1998

Emission Of Excimer Radiation From Direct Current, High-Pressure Hollow Cathode Discharge, Ahmed El-Habachi, Karl H. Schoenbach

Bioelectrics Publications

A novel, nonequilibrium, high-pressure, direct current discharge, the microhollow cathode discharge, has been found to be an intense source of xenon and argon excimer radiation peaking at wavelengths of 170 and 130 nm, respectively. In argon discharges with a 100 μm diam hollow cathode, the intensity of the excimer radiation increased by a factor of 5 over the pressure range from 100 to 800 mbar. In xenon discharges, the intensity at 170 nm increased by two orders of magnitude when the pressure was raised from 250 mbar to 1 bar. Sustaining voltages were 200 V for argon and 400 V …

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Ab Initio Single- And Multiple-Scattering Exafs Debye-Waller Factors: Raman And Infrared Data, N. Dimakis, Grant Bunker Jan 1998

Ab Initio Single- And Multiple-Scattering Exafs Debye-Waller Factors: Raman And Infrared Data, N. Dimakis, Grant Bunker

Physics and Astronomy Faculty Publications and Presentations

The extended x-ray-absorption fine structure (EXAFS) Debye-Waller factor is an essential term appearing in the EXAFS equation that accounts for the molecular structural and thermal disorder of a sample. Single- and multiple-scattering Debye-Waller factors must be known accurately to obtain quantitative agreement between theory and experiment. Since the total number of fitting parameters that can be varied is limited in general, data cannot support fitting of all relevant multiple-scattering Debye-Waller factors. Calculation of the Debye-Waller factors is typically done using the correlated Debye approximation, where a single parameter (Debye temperature) is varied. However, this procedure cannot account in general for …

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A Data Analysis Approach For Detecting Gravitational Waves From Psr 0437-4715, Soumya Mohanty, I. S. Heng, David Blair, S. Dhurandhar, M. Tovar, E. Ivanov Jan 1998

A Data Analysis Approach For Detecting Gravitational Waves From Psr 0437-4715, Soumya Mohanty, I. S. Heng, David Blair, S. Dhurandhar, M. Tovar, E. Ivanov

Physics and Astronomy Faculty Publications and Presentations

A search for gravitational waves from the millisecond pulsar PSR 0437-4715 has been initiated using the bar detector NIOBE which is located at the University of Western Australia. We present a detailed report on the data analysis algorithm, called phase plane rotation, which will be used in this search. A discussion of the actual implementation of the algorithm is presented. The data analysis algorithm mentioned above has the advantage that it requires minimal changes to the already-existing data acquisition facility of NIOBE but, at the same time, it is as efficient as optimal filtering in detecting a signal. This …

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Searching For Periodic Sources With Ligo, Patrick R. Brady, Teviet Creighton, Curt Cutler, Bernard F. Schutz Jan 1998

Searching For Periodic Sources With Ligo, Patrick R. Brady, Teviet Creighton, Curt Cutler, Bernard F. Schutz

Physics and Astronomy Faculty Publications and Presentations

We investigate the computational requirements for all-sky, all-frequency searches for gravitational waves from spinning neutron stars, using archived data from interferometric gravitational wave detectors such as LIGO. These sources are expected to be weak, so the optimal strategy involves coherent accumulaton of signal-to-noise using Fourier transforms of long stretches of data (months to years). Earth-motion-induced Doppler shifts, and intrinsic pulsar spindown, will reduce the narrow-band signal-to-noise by spreading power across many frequency bins; therefore, it is necessary to correct for these effects before performing the Fourier transform. The corrections can be implemented by a parametrized model, in which one does …

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Hierarchical Search Strategy For The Detection Of Gravitational Waves From Coalescing Binaries: Extension To Post-Newtonian Waveforms, Soumya Mohanty Jan 1998

Hierarchical Search Strategy For The Detection Of Gravitational Waves From Coalescing Binaries: Extension To Post-Newtonian Waveforms, Soumya Mohanty

Physics and Astronomy Faculty Publications and Presentations

The detection of gravitational waves from coalescing compact binaries would be a computationally intensive process if a single bank of template wave forms (one step search) is used. In an earlier paper we presented a detection strategy, called a two step search, that utilizes a hierarchy of template banks. It was shown that in the simple case of a family of Newtonian signals, an on-line two step search was ≃8 times faster than an on-line one step search (for the initial LIGO). In this paper we extend the two step search to the more realistic case of …

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Critical Casimir Forces Between Spherical Particles In Fluids, Andreas Hanke, F. Schlesener, E. Eisenriegler, S. Dietrich Jan 1998

Critical Casimir Forces Between Spherical Particles In Fluids, Andreas Hanke, F. Schlesener, E. Eisenriegler, S. Dietrich

Physics and Astronomy Faculty Publications and Presentations

Long-ranged correlations in a fluid close to its critical point Tc cause distinct forces between immersed colloidal particles and the container walls. We calculate such a force and its temperature dependence for the generic case of a spherical particle located at a distance D from a planar wall and find that the force attains a maximum at a temperature Tmax(D) above Tc, which facilitates quantitative experimental tests. The corresponding effective pair interaction between the colloidal particles themselves, potentially leading to aggregation, is also discussed.

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Coherent Neutral Pion Photoproduction On The Deuteron, David G. Meekins Jan 1998

Coherent Neutral Pion Photoproduction On The Deuteron, David G. Meekins

Dissertations, Theses, and Masters Projects

The differential scattering cross section for the process gd→dp0 was measured, as part of experiment E89-012 at Thomas Jefferson National Accelerator Facility. The experiment was performed in Hall C during the Spring of 1996 as the commissioning experiment for the Hall C cryogenic target. The High Momentum Spectrometer was used to detect the recoil deuteron and no effort was made to detect the p0 or its decay photons. The differential cross section was measured at a number of incident photon energies between 0.8 GeV and 4.0 GeV for the deuteron center-of-mass angles of 90?? and 136??. The data were found …

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Stability Of Quark-Antiquark Models Of Mesons: A Study On The Validity Of The Spectator, Dirac, And Salpeter Equations, Michael Uzzo Jan 1998

Stability Of Quark-Antiquark Models Of Mesons: A Study On The Validity Of The Spectator, Dirac, And Salpeter Equations, Michael Uzzo

Dissertations, Theses, and Masters Projects

Mesons are made of quark-antiquark pairs held together by the strong force. The one channel spectator, Dirac, and Salpeter equations can each be used to model this pairing. We look at cases where the relativistic kernel of these equations corresponds to a linear combination of scalar exchange and vector exchange. The vector exchange will be either the time-like component or the full four vector. The systems covered here are referred to as quasirelativistic, which means retardation, regularization, and form factors are not included. Since the model used in this paper describes mesons which cannot decay physically, the equations must describe …

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Microscale And Nanoscale Testing Of Materials Using Scanning Probe Technologies, Mark Phelan Jan 1998

Microscale And Nanoscale Testing Of Materials Using Scanning Probe Technologies, Mark Phelan

Theses

Understanding solid surfaces and their properties is of crucial importance for many sectors of industry. This interest stems from the fact that solid surfaces are the working interface between a solid material and its environment and in many cases it is this interface which determines both the suitability and life span of a mechanical component. Furthermore the modification of surface properties using coatings and multi-layered materials has grown significantly, particularly in the case of data storage, optics and microelectronics. The demands of these and other sectors have provided the impetus for the development of material testing techniques applicable to coatings …

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Multicolor Fringe Projection System With Enhanced 3-D Reconstruction Of Surfaces, Bernard S. Gilbert, Joel H. Blatt Jan 1998

Multicolor Fringe Projection System With Enhanced 3-D Reconstruction Of Surfaces, Bernard S. Gilbert, Joel H. Blatt

Aerospace, Physics, and Space Science Faculty Publications

Most optical topology systems use a single wavelength laser for projection, using a swept spot, a moving line, or a projected grating. In a typical projected grating system, the gratings are shifted and a series of images are used to recover the 3-D shape of the target. When the series of images is analyzed in the normal phase shift manner, the resulting 2-D phase map typically has phase unwrapping problems due to noise and Nyquist limits. Surfaces with large vertical discontinuities present the biggest problem in 3-D shape recovery. This paper looks at simultaneously projecting multiple wavelengths onto a surface …

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Measurement Of Thin Liquid Film Drainage Using A Novel High-Speed Impedance Analyzer, K. O. Hool, R. C. Saunders, Harry J. Ploehn Jan 1998

Measurement Of Thin Liquid Film Drainage Using A Novel High-Speed Impedance Analyzer, K. O. Hool, R. C. Saunders, Harry J. Ploehn

Faculty Publications

This work describes the design and implementation of a new instrument, called the thin film impedance analyzer, which measures the rate of drainage of thin oil films. The instrument forms an oil film by elevating a planar oil–water interface into a water drop hanging from a stainless steel capillary tube immersed in the oil. The instrument measures the magnitude of the impedance of the matter between the capillary tube and a screen electrode immersed in the lower water phase. Under appropriate conditions, the capacitance of the oil film dominates the impedance. The instrument records the increase in the magnitude of …

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Π-Systems As Lithium/Hydrogen Bond Acceptors: Some Theoretical Observations, Salai Cheettu Ammal, P. Venuvanalingam Jan 1998

Π-Systems As Lithium/Hydrogen Bond Acceptors: Some Theoretical Observations, Salai Cheettu Ammal, P. Venuvanalingam

Faculty Publications

Ab initio calculations at the Hartree–Fock and correlated levels and density functional theory calculations have been performed with 6-31++G(d,p) and 6-311++G(d,p)basis sets on LiF and HF complexes of benzene, ethylene, and acetylene. Complex binding energies have been corrected for basis set superposition error, and zero point energy corrections have been done on Hartree–Fock binding energies. Computed results indicate that the complexes exist in different conformations and among them those with π-lithium and π-hydrogen bonds are the most stable. π-lithium bonds are stronger than π-hydrogen bonds. The computed binding energies and geometry of HF complexes correlate well with the available experimental …

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Ab Initio And Dft Investigations Of Lithium/Hydrogen Bonded Complexes Of Trimethylamine, Dimethyl Ether And Dimethyl Sulfide, Salai Cheettu Ammal, P. Venuvanalingam Jan 1998

Ab Initio And Dft Investigations Of Lithium/Hydrogen Bonded Complexes Of Trimethylamine, Dimethyl Ether And Dimethyl Sulfide, Salai Cheettu Ammal, P. Venuvanalingam

Faculty Publications

Ab initio and DFT computations have been carried out on LiF and HF complexes of a set of n-donors viz. trimethylamine, dimethyl ether and dimethyl sulfide with a 6-31++G(d,p) basis set. The effect of correlation has been included with MP2, MP4 and DFT calculations. NBO analyses of the wavefunctions have been performed to examine the intermolecular interaction at the orbital level. Calculations reveal that these donors form strong n→σ* complexes and computed binding energies of the (CH3)2O···HF complex agree very well with the experimental binding energies from IR spectroscopy. LiF forms stronger complexes than HF, …

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Ab Initio Study Of Formazan And 3-Nitroformazan, G. Buemi, F. Zuccarello, P. Venuvanalingam, M. Ramalingam, Salai Cheettu Ammal Jan 1998

Ab Initio Study Of Formazan And 3-Nitroformazan, G. Buemi, F. Zuccarello, P. Venuvanalingam, M. Ramalingam, Salai Cheettu Ammal

Faculty Publications

Formazan and 3-nitroformazan have been investigated at abinitio level (MP2/6-31G** and B3LYP/6-31G**) in all their possible conformations, for studying the various possibilities of intramolecular hydrogen bonding formation. The trans-syn-s-cis (TSSC), known also asyellowform, has been found to be the most stable conformer (at least in the gas phase) in both compounds. This particular structure is strongly stabilized by a N–H···N hydrogen bridge, which gives rise to a hexatomic chelate ring, with the possibility of a proton transfer process.This closely resembles that of malondialdehyde, previously studied, in the evolution of the …

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Complete Single-Ionization Momentum Spectra For Strong Perturbation Collisions, Ronald E. Olson, C. J. Wood, H. Schmidt-Böcking, R. Moshammer, J. Ullrich Jan 1998

Complete Single-Ionization Momentum Spectra For Strong Perturbation Collisions, Ronald E. Olson, C. J. Wood, H. Schmidt-Böcking, R. Moshammer, J. Ullrich

Physics Faculty Research & Creative Works

The combination of recoil ion and ionized electron momentum spectroscopy provides an unparalleled method to investigate the details of ion-atom collision dynamics in kinematically complete experiments. To predict single ionization scattering behavior at the level now realized by experiment, the classical trajectory three-body Monte Carlo method has been used to obtain complete momenta information for the ionized electron, recoil ion, and projectile in the collision plane defined by the incident projectile and outgoing recoil ion. Strongly coupled systems were considered where the charge state of the projectile divided by the speed of the collision [Formula Presented] is greater than unity. …

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