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2002

University of Nebraska - Lincoln

Articles 31 - 60 of 116

Full-Text Articles in Physics

Direct Measurement Of The W Boson Decay Width, V. M. Abazov, Gregory R. Snow, D0 Collaboration Aug 2002

Direct Measurement Of The W Boson Decay Width, V. M. Abazov, Gregory R. Snow, D0 Collaboration

Gregory Snow Publications

Based on 85 pb-1 data of pp̅ collisions at √s = 1.8 TeV collected using the DØ detector at Fermilab during the 1994–1995 run of the Tevatron, we present a direct measurement of the total decay width of the W boson ΓW . The width is determined from the transverse mass spectrum in the W→e+ν ℯ decay channel and found to be ΓW=2.23-0.14+0.15 (stat) ±0.10(syst) GeV, consistent with the expectation from the standard model.

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Dielectric Properties Of A Ferroelectric Copolymer Langmuir–Blodgett Film, Mahantappa S. Jogad, Stephen Ducharme Aug 2002

Dielectric Properties Of A Ferroelectric Copolymer Langmuir–Blodgett Film, Mahantappa S. Jogad, Stephen Ducharme

Stephen Ducharme Publications

We report measurements of the real (epsilon prime) and imaginary (epsilon double-prime) parts of the relative complex permittivity of a Langmuir–Blodgett film of ferroelectric copolymer of vinylidene fluoride (70%) with trifluoroethylene (30%). The measurements were made in the temperature range of 35 to 125° C, and frequency range of 19 Hz to 5 MHz. The results indicate low frequency loss due to conduction and dielectric loss peak near the ferroelectric–paraelectric phase transition.

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Spin Injection Into Amorphous Semiconductors, Evgeny Y. Tsymbal, V. M. Burlakov, Ivan I. Oleinik Aug 2002

Spin Injection Into Amorphous Semiconductors, Evgeny Y. Tsymbal, V. M. Burlakov, Ivan I. Oleinik

Evgeny Tsymbal Publications

Using a realistic model for the atomic and electronic structure of amorphous silicon, we explore spin injection into amorphous semiconductors. We calculate the spin-dependent conductance of magnetoresistive devices within the Landauer-Büttiker formalism including inelastic scattering. We find that reducing the density of injected carriers and increasing the spin polarization of the electrodes are favorable for spin injection, whereas inelastic scattering is detrimental, and show that the upper limit for magnetoresistance is given by Julliere's formula.

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Magnetism Of Co Nanocluster Films, Y. Qiang, R.F. Sabiryanov, Sitaram Jaswal, Yi Liu, H. Haberland, David J. Sellmyer Aug 2002

Magnetism Of Co Nanocluster Films, Y. Qiang, R.F. Sabiryanov, Sitaram Jaswal, Yi Liu, H. Haberland, David J. Sellmyer

David Sellmyer Publications

A cluster-beam technique is used to produce nearly monodispersed nanoclusters of Co while independently varying their size and concentration. The Co clusters are embedded in Cu and SiO2 to form films with cluster size varying from 300 to 9000 atoms and Co concentration varying from 10 to 50 vol %. The Co magnetization (Ms) increases with increasing cluster size and decreases with increasing Co concentration for a given cluster size but is always less than the bulk value. First-principles calculations are used to analyze the experimental data in terms of the local environment effects at the …

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An All Optical Laser Wakefield Electron Injector, Donald Umstadter Jul 2002

An All Optical Laser Wakefield Electron Injector, Donald Umstadter

Donald Umstadter Publications

The personnel who were supported by the grant included the P.I. (Prof. Umstadter), several research scientists (A. Maksimchuk and V. Yanovsky), a postdoc (P. Zhang) and several graduate and undergraduate students.
Although there were several setbacks in developing the novel laser technology required to produce a monoenergetic beam of electrons from an all-optical accelerator, several important steps were taken towards reaching that ultimate goal. The most important outcome of this project was that we demonstrated the principle of optical control of laser accelerators, namely, that one laser pulse could modify the properties (e.g., emittance and electron number) of an electron …

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Search For New Physics In Photon-Lepton Events In Pp̅ Collisions At √S= 1.8 Tev, Darin Acosta, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Jul 2002

Search For New Physics In Photon-Lepton Events In Pp̅ Collisions At √S= 1.8 Tev, Darin Acosta, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We present the results of a search in pp̅ collisions at √s = 1.8 TeV for anomalous production of events containing a photon and a lepton ( e or μ), both with large transverse energy, using 86 pb-1 of data collected with the Collider Detector at Fermilab during the 1994–1995 collider run at the Fermilab Tevatron. The presence of large missing transverse energy (ET), additional photons, or additional leptons in these events is also analyzed. The results are consistent with standard model expectations, with the possible exception of photon-lepton events with large ET, for …

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Band Structure Of Strained Gd(0001) Films, I. N. Yakovkin, Takashi Komesu, Peter A. Dowben Jul 2002

Band Structure Of Strained Gd(0001) Films, I. N. Yakovkin, Takashi Komesu, Peter A. Dowben

Peter Dowben Publications

The electronic structure of strained and unstrained Gd(0001) surfaces has been studied both theoretically and experimentally with spin-polarized photoemission spectroscopy and spin-polarized inverse photoemission spectroscopy. Good agreement between calculated surface bands and surface-induced features of the spectra provides the basis for a more detailed explanation of the origin of the spin-polarized bands than was previously possible. It has been found that observed relaxation of the expansively strained in-plane crystal lattice constant, of Gd(0001) on Mo(112), significantly affects the electronic structure of the surface.

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Search For New Physics In Photon-Lepton Events In Pp̅ Collisions At √S =1.8 1.8 Tev, Darin Acosta, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Jul 2002

Search For New Physics In Photon-Lepton Events In Pp̅ Collisions At √S =1.8 1.8 Tev, Darin Acosta, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We present the results of a search in pp̅ collisions at √s =1.8 TeV for anomalous production of events containing a photon with large transverse energy and a lepton (e or m) with large transverse energy, using 86 pb-1 of data collected with the Collider Detector at Fermilab during the 1994–1995 collider run at the Fermilab Tevatron. The presence of large missing transverse energy (E/T), additional photons, or additional leptons in these events is also analyzed. The results are consistent with standard model expectations, with the possible exception of photon-lepton events with large E/T , …

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Improved W Boson Mass Measurement With The Dø Detector, V. M. Abazov, Gregory R. Snow, D0 Collaboration Jun 2002

Improved W Boson Mass Measurement With The Dø Detector, V. M. Abazov, Gregory R. Snow, D0 Collaboration

Gregory Snow Publications

We have measured the W boson mass using the DØ detector and a data sample of 82 pb-1 from the Fermilab Tevatron collider. This measurement uses W→eν decays, where the electron is close to a boundary of a central electromagnetic calorimeter module. Such “edge” electrons have not been used in any previous DØ analysis, and represent a 14% increase in the W boson sample size. For these electrons, new response and resolution parameters are determined, and revised backgrounds and underlying event energy flow measurements are made. When the current measurement is combined with previous DØ W boson mass …

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Gev Electrons From Ultraintense Laser Interaction With Highly Charged Ions, S.X. Hu, Anthony F. Starace Jun 2002

Gev Electrons From Ultraintense Laser Interaction With Highly Charged Ions, S.X. Hu, Anthony F. Starace

Anthony F. Starace Publications

Ultraintense laser interactions with highly charged ions are investigated using three-dimensional Monte Carlo simulations. Results show that ultraenergetic GeV electrons may be produced for highly charged ions chosen so that their electrons remain bound during the rise time of the laser pulse, and so that the electrons are ionized when the laser is near its maximum amplitude, which satisfies the best injection condition for subsequent laser acceleration.

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Band Filling And Depletion Through The Doping Of Polyaniline Thin Films, B. Xu, Jaewu Choi, A. N. Caruso, Peter A. Dowben Jun 2002

Band Filling And Depletion Through The Doping Of Polyaniline Thin Films, B. Xu, Jaewu Choi, A. N. Caruso, Peter A. Dowben

Peter Dowben Publications

The position of the molecular orbitals of polyaniline, relative to the Fermi level, shifts with the doping of polyaniline by both charge donor and charge acceptor species. Sodium as an electron donor, when added to the polyaniline system, results in an increase in electron population in the polyaniline bands but a decrease in density of states near EF . This is evident from the consistent shifts toward the greater binding energy of the occupied as well as unoccupied molecular orbitals, the valence bands and conduction band edges and characteristic core levels. In the case of iodine doping, an electron …

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Piezoresponse Force Microscopy For Polarity Imaging Of Gan, B.J. Rodriguez, Alexei Gruverman, A. I. Kingon, R. J. Nemanich Jun 2002

Piezoresponse Force Microscopy For Polarity Imaging Of Gan, B.J. Rodriguez, Alexei Gruverman, A. I. Kingon, R. J. Nemanich

Alexei Gruverman Publications

The polarity distribution of GaN based lateral polarity heterostructures is investigated by piezoresponse force microscopy (PFM). Simultaneous imaging of surface morphology, as well as the phase and magnitude of the piezoelectric response, is performed by PFM on a GaN film with patterned polarities on a c-Al2O3 substrate. We demonstrate that the polarity distribution of GaN based lateral polarity heterostructures can be deduced from the phase image of the piezoresponse with nanometer scale spatial resolution.

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Online Track Processor For The Cdf Upgrade, E. J. Thomson, C. Ciobanu, J.Y. Chung, J. Gerstenslager, J. Hoftiezer, R.E. Hughes, M. Johnson, P. Koehn, C. Neu, C. Sanchez, B.L. Winer, J. Dittman, J. Freeman, S. Holm, J.D. Lewis, C.J. Lin, T. Shaw, T. Wesson, Kenneth A. Bloom, D. Gerdes, N. Goldschmidt, J. Dawson, W. Haberichter Jun 2002

Online Track Processor For The Cdf Upgrade, E. J. Thomson, C. Ciobanu, J.Y. Chung, J. Gerstenslager, J. Hoftiezer, R.E. Hughes, M. Johnson, P. Koehn, C. Neu, C. Sanchez, B.L. Winer, J. Dittman, J. Freeman, S. Holm, J.D. Lewis, C.J. Lin, T. Shaw, T. Wesson, Kenneth A. Bloom, D. Gerdes, N. Goldschmidt, J. Dawson, W. Haberichter

Kenneth Bloom Publications

A trigger track processor, called the eXtremely Fast Tracker (XFT), has been designed for the Collider Detector at Fermilab (CDF) upgrade. This processor identifies high-transverse- momentum ( 1 5 GeV/c) charged particles in the new central outer tracking chamber for CDF II. The XFT design is highly parallel to handle the input rate of 183 Gb/s and the output rate of 44 Gb/s. The processor is pipelined and reports the result for a new event every 132 ns. The processor uses three stages: hit classification, segment finding, and segment linking. The pattern recognition algorithms for the three stages are implemented …

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Search For The Decay BS→Μ+Μ-Φ In Pp̅ Collisions At √S =1.8 Tev, Darin Acosta, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Jun 2002

Search For The Decay BS→Μ+Μ-Φ In Pp̅ Collisions At √S =1.8 Tev, Darin Acosta, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We present a search for the flavor-changing neutral current decay Bs→μ+μ-φ in pp̅ collisions at √s =1.8 TeV, using 91 pb-1 of data collected at the Collider Detector at Fermilab (CDF).We find two candidate events for this decay, which are consistent with the background estimate of one event, and set an upper limit on the branching fraction of Ɓ(Bs→μ+μ-φ),6.7x10-5 at a 95% confidence level. This is the first limit on the branching fraction of this decay.

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Chemical Bonds Broken In Latent Tracks Of Light Ions In Plastic Track Detectors, R. Barillon, M. Fromm, Robert Katz, A. Chambaudet Jun 2002

Chemical Bonds Broken In Latent Tracks Of Light Ions In Plastic Track Detectors, R. Barillon, M. Fromm, Robert Katz, A. Chambaudet

Robert Katz Publications

When a swift ion is slowed down through a plastic detector it creates a latent track. In nuclear track detectors, this latent track can be specifically etched by an appropriate chemical solution. This enlargement process is due to a higher etch velocity (VT) along the ion's path than in the non-damaged part of the detector. The etched track velocity is definitely linked to the damage created by the incoming ion in the detector material. A relationship between the physical parameters of the energy deposition and the variation in this etched track velocity with the ion energy cannot easily …

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Mechanically Milled Nanostructured (Sm,Pr) 12.5Co85.5Zr2 Magnets With Tbcu7 Structure, Hong Tang, Jian Zhou, David J. Sellmyer May 2002

Mechanically Milled Nanostructured (Sm,Pr) 12.5Co85.5Zr2 Magnets With Tbcu7 Structure, Hong Tang, Jian Zhou, David J. Sellmyer

David Sellmyer Publications

Nanostructured (Sm,Pr)(Co,Zr) magnets with the TbCu7-type structure have been synthesized by mechanically milling (Sm1-xPrx)12.5Co85.5Zr2 alloys (0≤x≤0.8) followed by appropriate annealing. Magnetic properties, structure, and microstructure have been investigated. It is found that single-phase (Sm,Pr)(Co,Zr) 7 magnets with the TbCu7 structure and with nanoscale grain size (14–19 nm) form in the whole composition range. Intrinsic coercivity Hci decreases from 20.7 to 5.6 kOe with increasing Pr content from 0 to 0.8, while energy products (BH)max shows an optimum value of 12.6 MGOe (Hciof 17.9 kOe) at …

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Structure And Magnetic Properties Of Sputtered (Nd,Dy)(Fe,Co,Nb,B) 5.5/M (M = Feco,Co) Multilayer Magnets, W. Liu, Z.D. Zhang, J. Ping Liu, Xingzhong Li, X.K. Sun, David J. Sellmyer May 2002

Structure And Magnetic Properties Of Sputtered (Nd,Dy)(Fe,Co,Nb,B) 5.5/M (M = Feco,Co) Multilayer Magnets, W. Liu, Z.D. Zhang, J. Ping Liu, Xingzhong Li, X.K. Sun, David J. Sellmyer

David Sellmyer Publications

The magnetic properties of nanocomposite multilayer magnets of the (Nd,Dy)(Fe,Co,Nb,B) 5.5/M (M = Co,FeCo) on Ti-buffered Si substrates have been investigated. X-ray diffraction results reveal that the Nd2Fe14B-type phase in almost all the films is randomly oriented. Different thickness x (nm) for Co layers and y (nm) for FeCo layers were adopted in the multilayers. It is found that high remanence is achieved in the nanocomposite multilayer films consisting of the Nd2Fe14B-type phase and soft magnetic phase for Co with 6≥x≥4 and for FeCo with 10≥y≥6. The …

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L10,(001)-Oriented Fept:B2O3 Composite Films For Perpendicular Recording, M.L. Yan, H. Zeng, Nathan D. Powers, David J. Sellmyer May 2002

L10,(001)-Oriented Fept:B2O3 Composite Films For Perpendicular Recording, M.L. Yan, H. Zeng, Nathan D. Powers, David J. Sellmyer

David Sellmyer Publications

A multilayered deposition structure was developed for fabricating FePt:B2O3 films. We successfully obtained nanostructured FePt:B2O3 films with FePt grains aligned perpendicular to film plane by postannealing the as-deposited multilayers at 550 °C for 30 min. It was found that development of (001) texture depends strongly on the total film thickness, initial B2O3 layer thickness, and Fe concentration. Nearly perfect (001) orientation of FePt-ordered grains can be obtained in the films with small total film thickness, large initial B2O3 layer thickness, and slightly higher Fe concentration. Our results show …

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Magnetic Force Microscopy Observations Of The Magnetic Behavior In Co–C Nanodot Arrays, L. Gao, Sy_Hwang Liou, M. Zheng, Ralph Skomski, M.L. Yan, David J. Sellmyer, N.I. Polushkin May 2002

Magnetic Force Microscopy Observations Of The Magnetic Behavior In Co–C Nanodot Arrays, L. Gao, Sy_Hwang Liou, M. Zheng, Ralph Skomski, M.L. Yan, David J. Sellmyer, N.I. Polushkin

David Sellmyer Publications

The nanomagnetic behavior of Co–C nanodot arrays was investigated by magnetic force microscopy (MFM) and an alternative gradient force magnetometer. The direction of the easy axis can be observed directly with MFM by comparing the saturated magnetization state and the remanent magnetization state. Interaction of the domain wall with local defects was observed by field dependent MFM measurements. Some types of defects that can pin domain wall movement were identified.

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Exact Nucleation Modes In Arrays Of Magnetic Particles, Ralph Skomski May 2002

Exact Nucleation Modes In Arrays Of Magnetic Particles, Ralph Skomski

Ralph Skomski Publications

Magnetization reversal in arrays of magnetic nanoparticles with perpendicular anisotropy is investigated. Aside from domain-wall propagation effects, the reversal involves two main aspects: the nucleation behavior of individual particles and interparticle interactions. Due to magnetostatic self-interaction effects, the interparticle interaction cannot be reduced to a stray-field correction to the external field. Exact nucleation fields and explicit stray-field and self-interaction contributions are obtained for rings of equidistant dots. An exact treatment of self-interactions in various structurally inhomogeneous but rotationally symmetric wire, sphere, and thin-film nanostructures leads to renormalization of the uniaxial anisotropy. Finally, an approximate method to calculate nucleation fields is …

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Spin Blockade Effects In Chromium Oxide Intergrain Magnetoresistance, Andrei Sokolov, C.S. Yang, Lu Yuan, Sy_Hwang Liou, Ruihua Cheng, B. Xu, C.N. Borca, Peter A. Dowben, Bernard Doudin May 2002

Spin Blockade Effects In Chromium Oxide Intergrain Magnetoresistance, Andrei Sokolov, C.S. Yang, Lu Yuan, Sy_Hwang Liou, Ruihua Cheng, B. Xu, C.N. Borca, Peter A. Dowben, Bernard Doudin

Peter Dowben Publications

CrO2 thin films with crystallites of a significant size permit investigation of the thin intergrain conduction between a limited numbers of crystals. Phoemission techniques reveal that the CrO2 films are covered by a 1–2-nm-thick Cr2O3 insulating barrier. The electronic band gap of the surface electrons is 3.4 eV at low temperatures, decreases sharply down to 2.8 eV at ambient. Electric transport though a few junctions in series shows a remarkable zero-bias anomaly, interpreted in terms of blockade effects. We show that the magnetoresistance is governed by low-bias blockade in these junctions. © 2002 American Institute …

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The Finite-Temperature Densities Of States For Half-Metallic Ferromagnets, Ralph Skomski, Peter A. Dowben May 2002

The Finite-Temperature Densities Of States For Half-Metallic Ferromagnets, Ralph Skomski, Peter A. Dowben

Peter Dowben Publications

A unitary spinor transformation is used to show that the spin-down density of states (DOS) of half-metallic ferromagnets becomes nonzero at finite temperatures. In a strict sense, this thermally activated spin mixing means that half-metallic ferromagnetism is limited to zero temperature. Similar effects are created by crystal imperfections, interfaces, and surfaces. The calculations, which imply that the finite-temperature resistivity of an individual spin channel is never infinite, are used to discuss recent experimental work on half-metallic oxides and Heusler-type alloys.

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Exchange-Controlled Magnetic Anisotropy, Ralph Skomski May 2002

Exchange-Controlled Magnetic Anisotropy, Ralph Skomski

Ralph Skomski Publications

The magnetocrystalline anisotropy of 5f transition-metal atoms (actinides) is investigated. A simple model Hamiltonian reproduces the observed huge low-temperature anisotropy of cubic actinide compounds such as US and predicts the temperature dependence of the anisotropy. The dominance of the spin–orbit and crystal–field interactions means that the magnitude of the anisotropy is limited only by interatomic exchange. One consequence is that cubic and uniaxial 4f magnets have similar magnitudes of the anisotropy and similar temperatures dependencies.

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Magnetic Force Microscopy Observations Of The Magnetic Behavior In Co–C Nanodot Arrays, L. Gao, Sy_Hwang Liou, M. Zheng, Ralph Skomski, M. L. Yan, David J. Sellmyer, N.I. Polushkin May 2002

Magnetic Force Microscopy Observations Of The Magnetic Behavior In Co–C Nanodot Arrays, L. Gao, Sy_Hwang Liou, M. Zheng, Ralph Skomski, M. L. Yan, David J. Sellmyer, N.I. Polushkin

Sy-Hwang Liou Publications

The nanomagnetic behavior of Co–C nanodot arrays was investigated by magnetic force microscopy (MFM) and an alternative gradient force magnetometer. The direction of the easy axis can be observed directly with MFM by comparing the saturated magnetization state and the remanent magnetization state. Interaction of the domain wall with local defects was observed by field dependent MFM measurements. Some types of defects that can pin domain wall movement were identified.

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Magnetic Intergranular Interaction In Nanocomposite CoΧPt100-Χ:C Thin Films, Nathan D. Powers, M.L. Yan, L. Gao, Sy_Hwang Liou, David J. Sellmyer May 2002

Magnetic Intergranular Interaction In Nanocomposite CoΧPt100-Χ:C Thin Films, Nathan D. Powers, M.L. Yan, L. Gao, Sy_Hwang Liou, David J. Sellmyer

Sy-Hwang Liou Publications

Magnetization reversal and intergranular interactions have been studied in composite CoχPt100-χ:C thin films using several magnetic characterization techniques. The intergranular interactions, as determined by ΔM curves, were strongly dependent on the ratio of Co and Pt concentration. For films with high Co content, the intergranular exchange coupling was predominant, while dipolar interactions were exhibited in the film with the equiatomic concentration of Co and Pt. Magnetic intergranular interaction was directly observed using magnetic force microscopy. There is a strong correlation between the value of the ΔM and magnetic correlation length obtained from the magnetic …

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Magnetoresistance Study In Thin Zig Zag Nife Wires, J. L. Tsai, S.F. Lee, Y.D. Yao, C. Yu, Sy_Hwang Liou May 2002

Magnetoresistance Study In Thin Zig Zag Nife Wires, J. L. Tsai, S.F. Lee, Y.D. Yao, C. Yu, Sy_Hwang Liou

Sy-Hwang Liou Publications

Thickness dependence on the domain wall resistivity of zig zag thin permalloy wires was studied from 10 to 300 K. The maximum domain wall resistivity was obtained in wire with 100-nm-film thickness. The multidomain state resistivity was 14.29 µΩ cm, while single-domain state resistivity was 14.36 µΩ cm at 10 K. The ratio of domain wall magnetoresistance was measured to be 0.034%, 0.112%, and 0.258%, and the magnetic field where the domain wall started to switch was measured as –70, –40, and +80 Oe for wires with thicknesses of 20, 40, and 100 nm, respectively, at 250 K. Domain wall …

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Threshold-Related Enhancement Of The High-Energy Plateau In Above-Threshold Detachment, Bogdan Borca, M.V. Frolov, N.L. Manakov, Anthony F. Starace May 2002

Threshold-Related Enhancement Of The High-Energy Plateau In Above-Threshold Detachment, Bogdan Borca, M.V. Frolov, N.L. Manakov, Anthony F. Starace

Anthony F. Starace Publications

We present nonperturbative theoretical results showing a resonant-like enhancement of above-threshold detachment spectra in the region of the high-energy plateau as the laser intensity sweeps across channel thresholds. This enhancement has a pure quantum origin stemming from well-known threshold phenomena in multichannel problems whose features are clearly demonstrated in our numerical results. Similar well-known anomalies at neutral atom thresholds are expected to explain experimentally observed resonant-like enhancements of above-threshold ionization spectra.

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A Class Of Boron-Rich Solid-State Neutron Detectors, B. W. Robertson, Shireen Adenwalla, A. Harken, P. Welsch, Jennifer I. Brand, Peter A. Dowben, J.P. Claassen May 2002

A Class Of Boron-Rich Solid-State Neutron Detectors, B. W. Robertson, Shireen Adenwalla, A. Harken, P. Welsch, Jennifer I. Brand, Peter A. Dowben, J.P. Claassen

Peter Dowben Publications

Real-time solid-state neutron detectors have been fabricated from semiconducting boron–carbon alloys, deposited by plasma-enhanced chemical vapor deposition. Single neutrons were detected and signals induced by gamma rays were determined to be insignificant. The source gas closo-1,2-dicarbadodecaborane (ortho-carborane) was used to fabricate the boron–carbon alloys with only the natural isotopic abundance of 10B. Devices made of thicker boron–carbon alloy layers enriched in 10B could lead to increased detection efficiency and active diodes could use the inherent micron scale spatial resolution, increasing the range of possible applications. © 2002 American Institute of Physics. [DOI: 10.1063/1.1477942]

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Search For Leptoquark Pairs Decaying Into Νν + Jets In Pp̅ Collisions At √S = 1.8 Tev, V. M. Abazov, Gregory R. Snow, D0 Collaboration May 2002

Search For Leptoquark Pairs Decaying Into Νν + Jets In Pp̅ Collisions At √S = 1.8 Tev, V. M. Abazov, Gregory R. Snow, D0 Collaboration

Gregory Snow Publications

We present the results of a search for leptoquark (LQ) pairs in (85.2 ± 3.7) pb-1 of pp̅ collider data collected by the D0 experiment at the Fermilab Tevatron. We observe no evidence for leptoquark production and set a limit on σ(pp̅→ LQ L̅Q̅→ νν + jets) as a function of the mass of the leptoquark (mLQ). Assuming the decay LQ → νq, we exclude scalar leptoquarks for mLQ< 98 GeV/c2, and vector leptoquarks for mLQ < 200 GeV/c2 and coupling which produces the minimum cross section, at a 95% confidence …

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Threshold-Related Effects In High-Order Harmonic Generation, Bogdan Borca, Anthony F. Starace, A. V. Flegel, M. V. Frolov, N. L. Manakov May 2002

Threshold-Related Effects In High-Order Harmonic Generation, Bogdan Borca, Anthony F. Starace, A. V. Flegel, M. V. Frolov, N. L. Manakov

Department of Physics and Astronomy: Faculty Publications

We present exact ab initio quantum results for harmonic generation (HG) by a weakly bound electron interacting with a strong monochromatic laser field. The analytic structure of the HG amplitude resulting from the multiphoton detachment thresholds is demonstrated. Our numerical results show that the HG spectrum is sensitive primarily to the distance in energy from the thresholds, thereby opening new possibilities for control of HG.

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