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Articles 29911 - 29940 of 36682

Full-Text Articles in Physical Sciences and Mathematics

Electroweak Structure Of Three-And Four-Body Nuclei, Laura Elisa Marcucci Jul 2000

Electroweak Structure Of Three-And Four-Body Nuclei, Laura Elisa Marcucci

Physics Theses & Dissertations

This work reports results for (i) the elastic electromagnetic form factors of the trinucleons; (ii) the nuclear response functions of interest in [e → e'] experiments, at excitation energies below the deuteron breakup threshold; (iii) the astrophysical S-factor for proton weak capture on 3He (the hep reaction). The initial and final state wave functions are calculated using the correlated hyperspherical harmonics method, from a realistic Hamiltonian consisting of the Argonne v18 two-nucleon and Urbana IX three-nucleon interactions. The nuclear electroweak charge and current operators include one- and many-body components. The predicted magnetic form factor of …

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Changes In Electron-Phonon Coupling Across A Bulk Phase Transition In Copolymer Films Of Vinylidene Fluoride (70%) With Trifluoroethylene (30%), C. N. Borca, Shireen Adenwalla, Jaewu Choi, Lee Robertson, H. You, V. M. Fridkin, S. P. Palto, N. Petukhova, Stephen Ducharme, Peter A. Dowben Jun 2000

Changes In Electron-Phonon Coupling Across A Bulk Phase Transition In Copolymer Films Of Vinylidene Fluoride (70%) With Trifluoroethylene (30%), C. N. Borca, Shireen Adenwalla, Jaewu Choi, Lee Robertson, H. You, V. M. Fridkin, S. P. Palto, N. Petukhova, Stephen Ducharme, Peter A. Dowben

Peter Dowben Publications

We present evidence for a change in electron - phonon coupling across a bulk phase transition. Below the lattice stiffening transition at around 160 K, there is a change in the diffracted peak width observed by neutron and X-ray scattering techniques. Also, the electronic band structure of the copolymer is shifting in binding energy below 160 K, decreasing the density of states near the Fermi level. The value of the effective Debye temperature above the transition temperature is approximately 50 K, while below 160 K, the value of the Debye parameter is 245 K. We postulate that the coupling between …

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Essentials Of K-Essence, Christian Armendariz-Picon, V. Mukhanov, Paul J. Steinhardt Jun 2000

Essentials Of K-Essence, Christian Armendariz-Picon, V. Mukhanov, Paul J. Steinhardt

Physics - All Scholarship

We recently introduced the concept of "k-essence" as a dynamical solution for explaining naturally why the universe has entered an epoch of accelerated expansion at a late stage of its evolution. The solution avoids fine-tuning of parameters and anthropic arguments. Instead, k-essence is based on the idea of a dynamical attractor solution which causes it to act as a cosmological constant only at the onset of matter-domination. Consequently, k-essence overtakes the matter density and induces cosmic acceleration at about the present epoch. In this paper, we present the basic theory of k-essence and dynamical attractors based on evolving scalar fields …

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Rare-Earth Boride Thin Film System, Peter A. Dowben, Zenchen Zhong, David J. Sellmyer Jun 2000

Rare-Earth Boride Thin Film System, Peter A. Dowben, Zenchen Zhong, David J. Sellmyer

Peter Dowben Publications

Disclosed is a system made by a method for depositing rare-earth boride onto the surface of a substrate which is submerged in an organic solution of borane and a rare-earth halide. Application of electromagnetic radiation, preferably in the visible wavelength range, through a mask near the surface of the submerged substrate, drives the formation and deposition of rare-earth boride onto a substrate in desired patterns.

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The Primordial Helium Abundance: Toward Understanding And Removing The Cosmic Scatter In The Dy/Dz Relation, D. R. Ballantyne, Gary J. Ferland, P. G. Martin Jun 2000

The Primordial Helium Abundance: Toward Understanding And Removing The Cosmic Scatter In The Dy/Dz Relation, D. R. Ballantyne, Gary J. Ferland, P. G. Martin

Physics and Astronomy Faculty Publications

We present results from photoionization models of low-metallicity H II regions. These nebulae form the basis for measuring the primordial helium abundance. Our models show that the helium ionization correction factor (ICF) can be nonnegligible for nebulae excited by stars with effective temperatures larger than 40,000 K. Furthermore, we find that when the effective temperature rises to above 45,000 K, the ICF can be significantly negative. This result is independent of the choice of stellar atmosphere. However, if an H II region has an [O III] λ5007/[O I] λ6300 ratio greater than 300, then our models show that, regardless of …

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Search For A W′ Boson Via The Decay Mode W′→Μν Μ In 1.8 Tev Pp̅ Collisions, F. Abe, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Jun 2000

Search For A W′ Boson Via The Decay Mode W′→Μν Μ In 1.8 Tev Pp̅ Collisions, F. Abe, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We report the results of a search for a W′ boson produced in pp̅ collisions at a center-of-mass energy of 1.8 TeV using a 107 pb-1 data sample recorded by the Collider Detector at Fermilab. We consider the decay channel W′→ μνμ and search for anomalous production of high transverse mass μνμ lepton pairs. We observe no excess of events above background and set limits on the rate of W′ boson production and decay relative to standard model W boson production and decay using a fit of the transverse mass distribution observed. If we assume standard …

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Search For Scalar Top And Scalar Bottom Quarks In Pp̅ Collisions At √S = 1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Jun 2000

Search For Scalar Top And Scalar Bottom Quarks In Pp̅ Collisions At √S = 1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We have searched for direct pair production of scalar top and scalar bottom quarks in 88 pb-1 of pp̅ collisions at √s =1.8 TeV with the CDF detector. We looked for events with a pair of heavy flavor jets and missing energy, consistent with scalar top (bottom) quark decays to a charm (bottom) quark and a neutralino. The numbers of events that pass our selections show no significant deviation from standard model expectations. We compare our results to the next-to-leading order scalar quark production cross sections to exclude regions in scalar quark-neutralino mass parameter space.

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Electronic Structure Of Bas And Boride Iii-V Alloys, Gus L. W. Hart, Alex Zunger Jun 2000

Electronic Structure Of Bas And Boride Iii-V Alloys, Gus L. W. Hart, Alex Zunger

Faculty Publications

Boron arsenide, the typically ignored member of the Group-III–V arsenide series BAs-AlAs-GaAs-InAs is found to resemble silicon electronically: its Γ conduction-band minimum is p-like (Γ15), not s-like (Γ1c), it has an X1c-like indirect band gap, and its bond charge is distributed almost equally on the two atoms in the unit cell, exhibiting nearly perfect covalency. The reasons for these are tracked down to the anomalously low atomic p orbital energy in the boron and to the unusually strong s–s repulsion in BAs relative to most other Group-III–V compounds. We find unexpected valence-band offsets of BAs with respect to GaAs and …

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State-Selective Cross Section Scalings For Electron Capture Collisions, K. R. Cornelius, K. Wojtkowski, Ronald E. Olson Jun 2000

State-Selective Cross Section Scalings For Electron Capture Collisions, K. R. Cornelius, K. Wojtkowski, Ronald E. Olson

Physics Faculty Research & Creative Works

The classical-trajectory Monte Carlo method is used to calculate total and final nf state-selective electron capture cross sections for various fully stripped ions, ranging from He2+ to Ne10+, incident on H(ni = 1-4) and Li(2s and 2p) targets over the collision energies of 1-100 keV u-1. Theoretical derivations of two scaling laws for state-selective electron capture cross sections as a function of collision energy, initial and final bound electron states and projectile charge are presented. The new scaling rules reduce the state-selective capture cross sections to very distinct universal curves. Curve fits …

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Single Ionization Of Ne By Intense Laser Fields, C. R. Feeler, Ronald E. Olson Jun 2000

Single Ionization Of Ne By Intense Laser Fields, C. R. Feeler, Ronald E. Olson

Physics Faculty Research & Creative Works

A three-dimensional classical Monte Carlo method has been used to examine the final state electron dynamics after single ionization of neon in an electric field generated by a short-pulse high-intensity laser. Linearly and circularly polarized fields were studied. Intensities ranging from 3 x 1014 to 3 x 1015 W cm-2 were used with a wavelength of 800 nm and a full-width at half-maximum of 30 fs. At these values, the Keldysh parameter is less than one, making the classical approximation valid. A potential determined by Hartree-Fock calculations has been used to model the Ne atom. A kinematically complete picture …

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Observation Of Phase-Matched Relativistic Harmonic Generation, Shouyuan Chen, Anatoly Maksimchuk, Eric Esarey, Donald P. Umstadter Jun 2000

Observation Of Phase-Matched Relativistic Harmonic Generation, Shouyuan Chen, Anatoly Maksimchuk, Eric Esarey, Donald P. Umstadter

Donald Umstadter Publications

Phase-matched relativistic harmonic generation in plasmas is observed for the first time. Third-harmonic light is detected and discriminated spectrally and angularly from the harmonics generated from competing processes. Its angular pattern is a narrow forward-directed cone, which is consistent with phase matching of a high-order transverse mode in a plasma. The signal level is found to be on the same order of magnitude for a circularly polarized pump pulse as for a linearly polarized pump pulse.

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Dimethylsulfoxide Reductase: An Enzyme Capable Of Catalysis With Either Molybdenum Or Tungsten At The Active Site, Lisa J. Stewart, Susan Bailey, Brian Bennett, John M. Charnock, C. David Garner, Alan S. Mcalpine Jun 2000

Dimethylsulfoxide Reductase: An Enzyme Capable Of Catalysis With Either Molybdenum Or Tungsten At The Active Site, Lisa J. Stewart, Susan Bailey, Brian Bennett, John M. Charnock, C. David Garner, Alan S. Mcalpine

Physics Faculty Research and Publications

DMSO reductase (DMSOR) from Rhodobacter capsulatus, well-characterised as a molybdoenzyme, will bind tungsten. Protein crystallography has shown that tungsten in W-DMSOR is ligated by the dithiolene group of the two pyranopterins, the oxygen atom of Ser147 plus another oxygen atom, and is located in a very similar site to that of molybdenum in Mo-DMSOR. These conclusions are consistent with W LIII-edge X-ray absorption, EPR and UV/visible spectroscopic data. W-DMSOR is significantly more active than Mo-DMSOR in catalysing the reduction of DMSO but, in contrast to the latter, shows no significant ability to catalyse the oxidation of DMS.

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Entangling Macroscopic Quantum States, John C. Howell, John A. Yeazell Jun 2000

Entangling Macroscopic Quantum States, John C. Howell, John A. Yeazell

Mathematics, Physics, and Computer Science Faculty Articles and Research

Spatial entanglements of macroscopic quantum systems are proposed. The which-path uncertainty of a single photon passing through a beam splitter is transformed into the which-path uncertainty of two macroscopic fields via two quantum nondemolition measurements. The macroscopic fields are nonlocally correlated.

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Electron Acceleration And The Propagation Of Ultrashort High-Intensity Laser Pulses In Plasmas, Xiaofang Wang, Mohan Krishnan, Ned Saleh, Haiwen Wang, Donald P. Umstadter Jun 2000

Electron Acceleration And The Propagation Of Ultrashort High-Intensity Laser Pulses In Plasmas, Xiaofang Wang, Mohan Krishnan, Ned Saleh, Haiwen Wang, Donald P. Umstadter

Donald Umstadter Publications

Reported are interactions of high-intensity laser pulses ( λ = 810 nm and l≤3×1018 W/cm2) with plasmas in a new parameter regime, in which the pulse duration ( τ = 29 fs) corresponds to 0.6–2.6 plasma periods. Relativistic filamentation is observed to cause laser-beam breakup and scattering of the beam out of the vacuum propagation angle. A beam of megaelectronvolt electrons with divergence angle as small as 1° is generated in the forward direction, which is correlated to the growth of the relativistic filamentation. Raman scattering, however, is found to be much less than previous long-pulse …

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Search For Scalar Top Quark Production In Pp̅ Collisions At √S = 1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Jun 2000

Search For Scalar Top Quark Production In Pp̅ Collisions At √S = 1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We have searched for direct production of scalar top quarks at the Collider Detector at Fermilab in 88 pb-1 of pp collisions at √s =1.8 TeV. We assume the scalar top quark decays into either a bottom quark and a chargino or a bottom quark, a lepton, and a scalar neutrino. The event signature for both decay scenarios is a lepton, missing transverse energy, and at least two b-quark jets. For a chargino mass of 90 GeV/c2 and scalar neutrino masses of at least 40 GeV/c2, we find no evidence for scalar top …

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A Cone Of Coherent Light, Shouyuan Chen, Anatoly Maksimchuk, Eric Esarey, Donald P. Umstadter Jun 2000

A Cone Of Coherent Light, Shouyuan Chen, Anatoly Maksimchuk, Eric Esarey, Donald P. Umstadter

Donald Umstadter Publications

Lasers come in infrared and visible varieties, but none yet in the x-ray band. A compact and powerful source of coherent x rays is the dream of many physicists, who see applications such as making atomic scale, three-dimensional movies of a melting crystal or an operating photosynthesis protein. In a step toward that goal, a research team has detected high frequency coherent light generated by a new process. As they report in the 12 June PRL, intense laser pulses can stimulate free electrons in a plasma to emit coherent light at triple the input frequency in a narrowly-directed cone. The …

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Sans Polarization Analysis With Nuclear-Spin-Polarized He-3, T. R. Gentile, Gordon L. Jones, A. K. Thompson, J. Barker, C. J. Glinka, B. Hammouda, J. W. Lynn Jun 2000

Sans Polarization Analysis With Nuclear-Spin-Polarized He-3, T. R. Gentile, Gordon L. Jones, A. K. Thompson, J. Barker, C. J. Glinka, B. Hammouda, J. W. Lynn

Articles

A neutron spin filter based on transmission through nuclear-spin-polarized He-3 gas has been applied to polarization analysis of small angle neutron scattering (SANS). Such spin filters, which are based on the large spin dependence of the absorption of neutrons by He-3, make SANS polarization analysis possible because of their large angular acceptance. In the present experiment, a He-3-based analyzer was employed to separate nuclear scattering into its coherent and spin-incoherent components. Polarized He-3 analyzers were prepared by two different optical pumping methods and installed on the NG3 SANS instrument at the NIST Center for Neutron Research (NCNR). Measurements were taken …

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System Architecture And Hardware Design Of The Cdf Xft Online Track Processor, S. Holm, J.R. Dittman, J. Freeman, R. Klein, J.D. Lewis, T.M. Shaw, T. Wesson, C. Ciobanu, J. Gerstenslager, J. Hoftiezer, R. Hughes, M. Johnson, P. Koehn, C. Neu, C. Sanchez, B.L. Winer, Kenneth A. Bloom, D. Gerdes, J.W. Dawson, W.N. Haberichter Jun 2000

System Architecture And Hardware Design Of The Cdf Xft Online Track Processor, S. Holm, J.R. Dittman, J. Freeman, R. Klein, J.D. Lewis, T.M. Shaw, T. Wesson, C. Ciobanu, J. Gerstenslager, J. Hoftiezer, R. Hughes, M. Johnson, P. Koehn, C. Neu, C. Sanchez, B.L. Winer, Kenneth A. Bloom, D. Gerdes, J.W. Dawson, W.N. Haberichter

Kenneth Bloom Publications

A trigger track processor is being designed for CDF Run 2. This processor identifies high momentum (PT > 1.5 GeV/c) charged tracks in the new central outer tracking chamber for the CDF I1 detector. The design of the track processor, called the extremely Fast Trackcr (XFT), is highly parallel and handle an input rate of 183 Gbitslsec and output rate of 44 Gbitdsec. The XFT is pipclined and reports the results for a new event every 132ns. The XFT uses threc stages, hit classification, segment finding, and segment linking. The pattem recognition algorithm for the three stages are implemented …

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Dissociation Of Al2o3(0001) Substrates And The Roles Of Silicon And Oxygen In N-Type Gan Thin Solid Films Grown By Gas-Source Molecular Beam Epitaxy, J. E. Van Nostrand, J. Solomon, A. Saxler, Q. H. Xie, D. C. Reynolds, David C. Look Jun 2000

Dissociation Of Al2o3(0001) Substrates And The Roles Of Silicon And Oxygen In N-Type Gan Thin Solid Films Grown By Gas-Source Molecular Beam Epitaxy, J. E. Van Nostrand, J. Solomon, A. Saxler, Q. H. Xie, D. C. Reynolds, David C. Look

Physics Faculty Publications

Unintentionally doped and silicon doped GaN films prepared by molecular beam epitaxy using ammonia are investigated. Hall, secondary ion mass spectroscopy (SIMS), photoluminescence, and x-ray data are utilized for analysis of sources of autodoping of GaN epitaxial films in an effort to identify whether the n-type background electron concentration is of impurity origin or native defect origin. We identify and quantify an anomalous relationship between the Si doping concentration and free carrier concentration and mobility using temperature dependent Hall measurements on a series of 2.0-μm-thick GaN(0001) films grown on sapphire with various Si doping concentrations. SIMS is used to …

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Control And Data Acquisition For An Electron Spectrometer System, Stanislav Rumega Jun 2000

Control And Data Acquisition For An Electron Spectrometer System, Stanislav Rumega

Masters Theses

An electron spectrometer system, installed on one of the beam lines in the WMU Van de Graaff accelerator laboratory, consists of two 45o parallel-plate electrostatic analyzers, a decelerating grid, and a channeltron. It allows the energy analysis, angular analysis, and the detection of continuum electrons ejected following the bombardment of a target with accelerated ions or electrons. First, the principles of operation of the spectrometer itself are discussed with emphasis on the energy analysis. Next, the electronics and computer interfacing required for control of the spectrometer functions and for acquisition of data are described. Finally, the control and data …

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Comments On D Branes And The Renormalization Group, Vatche Sahakian Jun 2000

Comments On D Branes And The Renormalization Group, Vatche Sahakian

All HMC Faculty Publications and Research

We review the de Boer-Verlinde-Verlinde formalism for the renormalization group in the context of Dp-brane vacua for p < 5. We comment on various aspects of the dictionary between bulk and boundary and relate the discussion to the Randall-Sundrum scenario. We find that the gravitational coupling for the Randall-Sundrum gravity on the Dp-brane worldvolume is dressed by the c-function of the Yang-Mills theory. We compute the beta function and find the expected uneventful flow prescribed by the classical dimension of the Yang-Mills operator.

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Pulse Radiolysis Of Liquid Water Using Picosecond Electron Pulses Produced By A Table-Top Terawatt Laser System, Ned Saleh, Kirk Flippo, Koshichi Nemoto, Donald P. Umstadter, Robert A. Crowell, Charles D. Jonah, Alexander D. Trifunac Jun 2000

Pulse Radiolysis Of Liquid Water Using Picosecond Electron Pulses Produced By A Table-Top Terawatt Laser System, Ned Saleh, Kirk Flippo, Koshichi Nemoto, Donald P. Umstadter, Robert A. Crowell, Charles D. Jonah, Alexander D. Trifunac

Donald Umstadter Publications

A laser based electron generator is shown, for the first time, to produce sufficient charge to conduct time resolved investigations of radiation induced chemical events. Electron pulses generated by focussing terawatt laser pulses into a supersonic helium gas jet are used to ionize liquid water. The decay of the hydrated electrons produced by the ionizing electron pulses is monitored with 0.3 µs time resolution. Hydrated electron concentrations as high as 22 µM were generated. The results show that terawatt lasers offer both an alternative to linear accelerators and a means to achieve subpicosecond time resolution for pulse radiolysis studies.

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Photoionization And Photofragmentation Of Gaseous Toluene Using 80-Fs, 800-Nm Laser Pulses, A. M. Müller, Cornelis J. Uiterwaal, B. Witzel, J. Wanner, K.-L. Kompa Jun 2000

Photoionization And Photofragmentation Of Gaseous Toluene Using 80-Fs, 800-Nm Laser Pulses, A. M. Müller, Cornelis J. Uiterwaal, B. Witzel, J. Wanner, K.-L. Kompa

C.J.G.J. Uiterwaal Publications

This paper presents ion yields resulting from multiphoton ionization and fragmentation of gaseous toluene (C7H8) in the focus of an 80 fs Ti:sapphire laser beam (λ = 800 nm) with a sufficiently small B-integral [Siegman, Lasers (University Science Books, Mill Valley, CA, 1986)]. The peak intensity was varied between 1.9x1013 and 2.8x1013Wcm-2, and both linear and circular polarization were used. Over the whole range of intensities studied, only the singly charged parent ion and its fragment, C7H7+, are found. Although the Keldysh adiabaticity parameter equals …

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Terdiurnal Oscillations In Oh Meinel Rotational Temperatures For Fall Conditions At Northern Mid-Latitude Sites, W. R. Pendleton Jr., Michael J. Taylor, Larry Gardner Jun 2000

Terdiurnal Oscillations In Oh Meinel Rotational Temperatures For Fall Conditions At Northern Mid-Latitude Sites, W. R. Pendleton Jr., Michael J. Taylor, Larry Gardner

All Physics Faculty Publications

High‐precision (∼0.5 K) measurements of OH Meinel (M) (6,2) rotational temperatures above the Bear Lake Observatory, UT (42°N, 112°W) during October 1996 have revealed an interesting and unexpected mean nocturnal pattern. Ten quality nights (>100 h) of data have been used to form a mean night for autumnal, near‐equinoctial conditions. The mean temperature and RMS variability associated with this mean night were 203 ± 5 K and 2.4 K, respectively, and compare very favorably with expectations based on Na‐lidar measurements of mean tidal temperature perturbations over Urbana, IL (40°N, 88°W) during the fall 1996. Furthermore, this comparison shows that …

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Reversible Carbon Monoxide Binding And Inhibition At The Active Site Of The Fe-Only Hydrogenase, Brian Bennett, Brian J. Lemon, John W. Peters Jun 2000

Reversible Carbon Monoxide Binding And Inhibition At The Active Site Of The Fe-Only Hydrogenase, Brian Bennett, Brian J. Lemon, John W. Peters

Physics Faculty Research and Publications

Carbon monoxide binding and inhibition have been investigated by electron paramagnetic resonance (EPR) spectroscopy in solution and in crystals of structurally described states of the Fe-only hydrogenase (CpI) from Clostridium pasteurianum. Simulation of the EPR spectrum of the as-isolated state indicates that the main component of the EPR spectrum consists of the oxidized state of the “H cluster” and components due to reduced accessory FeS clusters. Addition of carbon monoxide to CpI in the presence of dithionite results in the inhibition of hydrogen evolution activity, and a characteristic axial EPR signal [geff(1), geff(2), and …

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A Look At What Is (And Isn't) Known About Quasar Broad Line Regions And How Narrow-Line Seyfert 1s Fit In, C. Martin Gaskell Jun 2000

A Look At What Is (And Isn't) Known About Quasar Broad Line Regions And How Narrow-Line Seyfert 1s Fit In, C. Martin Gaskell

Department of Physics and Astronomy: Faculty Publications

The evidence is reviewed that the Broad Line Region (BLR) probably has two distinct components located at about the same distance from the central black hole. One component, BLR II, is optically-thick, low-ionization emission at least some of which arises from a disc and the other, BLR I, is probably optically-thin emission from a more spherically symmetric halo or atmosphere. The high Fe II/Hβ ratios seen in Narrow-Line Seyfert 1 galaxies (NLS1s) are not due to strong Fe II emission, as is commonly thought, but to unusually weak Balmer emission, probably caused by higher densities. NLS1s probably differ from non-NLS1s …

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Time Domain Measurement Of The Nonlinear Refractive Index In Optical Fibers And Semiconductor Film, Hernando Garcia May 2000

Time Domain Measurement Of The Nonlinear Refractive Index In Optical Fibers And Semiconductor Film, Hernando Garcia

Dissertations

A new technique to measure the nonlinear refractive index n2 in optical fibers and semiconductor films has been developed. It is based on the time delay two-beam coupling of very intense picosecond laser pulses that have been self-phase modulated in the nonlinear optical medium. The two beams are coupled in a slow responding medium that is sensitive to time dependent phase distortions. We determine that the amount of phase distortion experienced by the pulse is proportional to the nonlinear refractive index of the medium, This time domain approach can also be applied to optical fiber amplifiers in the presence …

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Modeling, Design And Fabrication Of Thin-Film Microcrystalline Silicon Solar Cells, Wei Chen May 2000

Modeling, Design And Fabrication Of Thin-Film Microcrystalline Silicon Solar Cells, Wei Chen

Dissertations

The modeling, design and fabrication of low-cost thin-film microcrystalline silicon(µcSi) solar cells is studied in this thesis. The cell, considered in this investigation, utilizes low-cost glass as the substrate and microcrystalline Si (µc-Si) as the active layer. A comprehensive refractive index (n) and extinction coefficient (k) model of silicon as function of doping, temperature and wavelength is developed to assist the optical design of the cell. In order to obtain acceptable short circuit current density (Jsc) from the cell, it is found that the thickness of the silicon thin film should be more than 10µm. To get the best light …

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Diffractive Dijets With A Leading Antiproton In P̅P Collisions At √S = 1800 Gev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration May 2000

Diffractive Dijets With A Leading Antiproton In P̅P Collisions At √S = 1800 Gev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We report results from a study of events with a leading antiproton of beam momentum fraction 0.905 <xF < 0.965 and 4-momentum transfer squared |t|< 3 GeV2 produced in p̅p collisions at √s =1800 GeV at the Fermilab Tevatron collider. Approximately 2% of the events contain two jets of transverse energy ETjet > 7 GeV. Using the dijet events, we evaluate the diffractive structure function of the antiproton and compare it with expectations based on results obtained in diffractive deep inelastic scattering experiments at the DESY ep collider HERA.

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Measurement Of Azimuthal Asymmetries In Deep Inelastic Scattering, J. Breitweg, S. Chekanov, M. Derrick, D. Krakauer, S. Magill, B. Musgrave, A. Pellegrino, J. Repond, R. Stanek, R. Yoshida, Margarita C. K. Mattingly, G. Abbiendi, F. Anselmo, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, N. Coppola, M. Corradi, S. De Pasquale, P. Giusti, G. Iacobucci, G. Laurenti May 2000

Measurement Of Azimuthal Asymmetries In Deep Inelastic Scattering, J. Breitweg, S. Chekanov, M. Derrick, D. Krakauer, S. Magill, B. Musgrave, A. Pellegrino, J. Repond, R. Stanek, R. Yoshida, Margarita C. K. Mattingly, G. Abbiendi, F. Anselmo, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, N. Coppola, M. Corradi, S. De Pasquale, P. Giusti, G. Iacobucci, G. Laurenti

Faculty Publications

The distribution of the azimuthal angle for the charged hadrons has been studied in the hadronic centre-of-mass system for neutral current deep inelastic positron-proton scattering with the ZEUS detector at HERA. Measurements of the dependence of the moments of this distribution on the transverse momenta of the charged hadrons are presented. Asymmetries that can be unambiguously attributed to perturbative QCD processes have been observed for the first time. (C) 2000 Elsevier Science B.V.

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