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Physics

University of Nebraska - Lincoln

1999

Articles 1 - 30 of 74

Full-Text Articles in Physical Sciences and Mathematics

Nanocomposite Copt:C Films For Extremely High-Density Recording, M. Yu, Yi Liu, A. Moser, D. Weller, David J. Sellmyer Dec 1999

Nanocomposite Copt:C Films For Extremely High-Density Recording, M. Yu, Yi Liu, A. Moser, D. Weller, David J. Sellmyer

David Sellmyer Publications

Nanocomposite CoPt:C films were investigated as potential media for extremely high-density recording. An annealing temperature of over 600 °C is necessary to form nanocomposite CoPt:C films consisting of C matrix and fct CoPt nanocrystallites with grain sizes of 8–20 nm and coercivities of 3–12 kOe. Coercivity and grain size increase with increasing annealing temperature and decreasing C concentration and they are insensitive to film thickness. The average activation volumes are about 0.9×10-18 cm3. The properties of these nanocomposite CoPt:C films can be tailored to satisfy the thermal stability, coercivity, and media noise requirements for extremely high-density recording.

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Measurement Of The B0B̅0 Oscillation Frequency Using L-D*+ Pairs And Lepton Flavor Tags, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Dec 1999

Measurement Of The B0B̅0 Oscillation Frequency Using L-D*+ Pairs And Lepton Flavor Tags, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

The oscillation frequency Δmd of B0B̅0 mixing is measured using the partially reconstructed semileptonic decay B̅0→l- ν̅ D*+X. The data sample was collected with the CDF detector at the Fermilab Tevatron collider during 1992–1995 by triggering on the existence of two lepton candidates in an event, and corresponds to about 110 pb-1 of p̅p collisions at √s =1.8 TeV. We estimate the proper decay time of the B̅0 meson from the measured decay length and reconstructed momentum of the l-D*+ system. The charge of …

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Molecular-Dynamics Study Of Phase Transitions In Alkali Azides, M. M. Ossowski, John R. Hardy, R. W. Smith Dec 1999

Molecular-Dynamics Study Of Phase Transitions In Alkali Azides, M. M. Ossowski, John R. Hardy, R. W. Smith

John R. Hardy Papers

An account is presented of our studies of the order-disorder phase transitions in KN3, RbN3, and CsN3. These are based on parameter-free interionic potentials based on the Gordon-Kim modified electron-gas formalism extended to molecular ions. We performed static structural relaxations and supercell molecular dynamics and predicted with reasonable accuracy the temperatures for the onset of the transitions. In particular, we address the question of how the N3- ions reorient to yield the transitions. We found the existence of NaCl-type high-temperature phases in disordered KN3 and RbN3 and argue that this …

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Detailed Dynamics Of Electron Beams Self-Trapped And Accelerated In A Self-Modulated Laser Wakefield, Shouyuan Chen, M. Krishnan, Anatoly Maksimchuk, R. Wagner, Donald P. Umstadter Dec 1999

Detailed Dynamics Of Electron Beams Self-Trapped And Accelerated In A Self-Modulated Laser Wakefield, Shouyuan Chen, M. Krishnan, Anatoly Maksimchuk, R. Wagner, Donald P. Umstadter

Donald Umstadter Publications

The electron beam generated in a self-modulated laser-wakefield accelerator is characterized in detail. A transverse normalized emittance of 0.06 π mm mrad, the lowest ever for an electron injector, was measured for 2 MeV electrons. The electron beam was observed to have a multicomponent beam profile and energy distribution. The latter also undergoes discrete transitions as the laser power or plasma density is varied. In addition, dark spots that form regular modes were observed in the electron beam profile. These features are explained by analysis and test particle simulations of electron dynamics during acceleration in a three-dimensional plasma wakefield.

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Photodetachment Of He- In The Vicinity Of The He* (N=3, 4, And 5) Thresholds, Chien-Nan Liu, Anthony F. Starace Dec 1999

Photodetachment Of He- In The Vicinity Of The He* (N=3, 4, And 5) Thresholds, Chien-Nan Liu, Anthony F. Starace

Anthony F. Starace Publications

A comprehensive eigenchannel R-matrix study of photodetachment of He-(1 s2s2p 4P0 (1 ) is presented for the energy region of the Hesnl3l) thresholds, where 3<~n<~5. Over this energy region we present all partial cross sections which have been measured experimentally, including theoretical predictions (1 for the Hes3p 3P ( ) partial cross section, as well as energies and widths for all resonances, and identifications of all major ones. Near the Hen=3) thresholds, we predict two 4De resonances that to our knowledge have previously been neither predicted nor observed, and present results showing their effects on partial cross sections and photoelectron angular distributions; …

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Lattice-Stiffening Transition In Copolymer Films Of Vinylidene Fluoride (70%) With Trifluoroethylene (30%), C.N. Borca, Shireen Adenwalla, Jaewu Choi, P.T. Sprungerr, Stephen Ducharme, Lee Robertson, S.P. Palto, Jianglai Liu, Matt Poulsen, V.M. Fridkin, H. You, Peter A. Dowben Nov 1999

Lattice-Stiffening Transition In Copolymer Films Of Vinylidene Fluoride (70%) With Trifluoroethylene (30%), C.N. Borca, Shireen Adenwalla, Jaewu Choi, P.T. Sprungerr, Stephen Ducharme, Lee Robertson, S.P. Palto, Jianglai Liu, Matt Poulsen, V.M. Fridkin, H. You, Peter A. Dowben

Peter Dowben Publications

We report the discovery of a compressibility phase transition at 160 K in crystalline copolymer films of vinylidene fluoride ( 70%) with trifluoroethylene ( 30%). This phase transition is distinct from the known bulk ferroelectric-paraelectric phase transition at 353 K and surface ferroelectric phase transition at 295 K. The new phase transition is characterized by an increase in the effective Debye temperature from 48 to 245 K along the 〈010〉 direction as the temperature falls below 160 K. This phase transition is evident in neutron scattering, x-ray diffraction, angle-resolved photoemission, and in the dipole active phonon modes in electron energy-loss …

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Electron Injection By Dephasing Electrons With Laser Fields, E. Dodd, J.K. Kim, Donald P. Umstadter Nov 1999

Electron Injection By Dephasing Electrons With Laser Fields, E. Dodd, J.K. Kim, Donald P. Umstadter

Donald Umstadter Publications

The authors seek to review injection concepts for plasma based acceleration. It is shown that regardless of injection mechanism, resultant beams will be similar due to wave structure. Also, most schemes employ the same basic processes, namely the dephasing of electrons by laser fields, and can thus be analyzed with similar approaches.

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Acceleration Of Electrons In A Self-Modulated Laser Wakefield, Shouyuan Chen, M. Krishnan, Anatoly Maksimchuk, Donald P. Umstadter Nov 1999

Acceleration Of Electrons In A Self-Modulated Laser Wakefield, Shouyuan Chen, M. Krishnan, Anatoly Maksimchuk, Donald P. Umstadter

Donald Umstadter Publications

Acceleration of electrons in a self-modulated laser-wakefield is investigated. The generated electron beam is oberved to have a multi-component beam profile and its energy distribution undergoes discrete transitions as the conditions are varied. These features can be explained by simple simulations of electron propagation in a 3-D plasma wave.

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Rkky Interactions Between Nanomagnets Of Arbitrary Shape, Ralph Skomski Nov 1999

Rkky Interactions Between Nanomagnets Of Arbitrary Shape, Ralph Skomski

Ralph Skomski Publications

The RKKY interaction between well-separated magnetic particles in a nonmagnetic metallic matrix is calculated. It turns out that the net interaction can be mapped onto an RKKY interaction between two point-like effective moments. The effective moments exhibit a strongly oscillating dependence on the particle's size, shape, and orientation, but their magnitudes are governed by scaling laws. As a rule, magnetostatic interactions tend to suppress the RKKY effect in particles larger than about 1 nm. Surface roughness leaves the effective-moment picture unaltered but tends to yield a moderate reduction of the effective moments. The results are discussed in the context of …

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Selective Adsorption Of Metallocenes On Clean And Chemically Modified Si(111) Surfaces, J.-L. Lin, H. Rauscher, A. Kirakosian, F.J. Himpsel, Peter A. Dowben Nov 1999

Selective Adsorption Of Metallocenes On Clean And Chemically Modified Si(111) Surfaces, J.-L. Lin, H. Rauscher, A. Kirakosian, F.J. Himpsel, Peter A. Dowben

Peter Dowben Publications

Metallocene adsorption on clean Si(111) and CaF2/CaF1/Si(111) substrates has been investigated with scanning tunneling microscopy. The surface chemical composition is found to strongly change the adsorption site selectivity, leading to an enhanced edge selectivity on modified substrates. Templates with well-defined local chemical reactivity have been created via self-assembly. The selective adsorption of metallocenes on such tailored substrates facilitates patterning ordered arrays of magnetic nanowires and stripes on the single digit nanometer scale. ©1999 American Institute of Physics.

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Structural And Magnetic Properties Of Fept:Sio2 Granular Thin Films, C.P. Luo, David J. Sellmyer Nov 1999

Structural And Magnetic Properties Of Fept:Sio2 Granular Thin Films, C.P. Luo, David J. Sellmyer

David Sellmyer Publications

Nanocomposite FePt:SiO2 films have been fabricated by annealing the as-deposited FePt/SiO2 multilayers at temperatures from 450 to 650 °C. These films consist of high-anisotropy tetragonal L10 FePt particles embedded in a SiO2 matrix. The structural and magnetic properties of these films were investigated. We have found that coercivity and grain size are highly dependent on the annealing temperature and SiO2 concentration. Films with coercivities in the range from 2 to 8 kOe and grain sizes of 10 nm or less were obtained. These films have considerable potential as high-density magnetic recording media.

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Laser Light In, 50-Mev Protons Out, Phillip F. Schewe, Ben Stein, Donald P. Umstadter Nov 1999

Laser Light In, 50-Mev Protons Out, Phillip F. Schewe, Ben Stein, Donald P. Umstadter

Donald Umstadter Publications

At next week's meeting of the American Physical Society Division of Plasma Physics in Seattle, three groups will independently announce their ability to generate powerful, intense streams of ions by shining ultrashort laser pulses on tiny spots of solid material. Potentially, this approach offers an alternative to bulky, expensive ion accelerators for producing high-velocity ions useful for cancer therapy and electronics manufacturing. Using a single pulse of light from Livermore's Petawatt laser, the most powerful in the world, researchers at that laboratory (Scott Wilks, 925-422-2974, wilks@icf.llnl.gov) have reported generating 30 trillion protons with energies up to 50 MeV, from a …

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Measurement Of B Quark Fragmentation Fractions In The Production Of Strange And Light B Mesons In Pp̅ Collisions At √S =1.8 Tev, F. Abe, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Nov 1999

Measurement Of B Quark Fragmentation Fractions In The Production Of Strange And Light B Mesons In Pp̅ Collisions At √S =1.8 Tev, F. Abe, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

A new technique to measure the ratio of b quark fragmentation fractions in pp̅ collisions is described. Using a 70-pb-1 sample of low-mass dimuon trigger data recorded with the Collider Detector at Fermilab, we identify B mesons by observing the double semileptonic decays b→cμX with c→sμ X. By counting the numbers of K*(892) 0, K*(892) 1, and Φ (1020) mesons produced in association with these muon pairs, we measure the ratio of strange to nonstrange B meson production to be fs /( fu+ i>fd)=[21.0±3.6(stat) -3.0 …

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Intensity Dependence Of Plateau Structures In Laser-Assisted X-Ray–Atom Scattering Processes, Dejan B. Miloševic, Anthony F. Starace Nov 1999

Intensity Dependence Of Plateau Structures In Laser-Assisted X-Ray–Atom Scattering Processes, Dejan B. Miloševic, Anthony F. Starace

Anthony F. Starace Publications

The dependence on laser intensity of recently discovered plateau structures in laser-assisted x-ray–atom scattering, both with and without a static electric field present, is analyzed. Using the “three-step” model and the strong-field approximation we demonstrate a connection between laser-assisted, x-ray–atom scattering and high-order harmonic generation: For high laser-field intensities without a static field present, both processes have plateaus whose energies extend to the cutoff value 3.17Up, where Up is the ponderomotive potential energy. For x-ray–atom scattering in the presence of a static electric field we show that at high laser-field intensities two plateaus appear: One is …

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Search For The Flavor-Changing Neutral Current Decays B+→ Μ+Μ-K+ And B0→ Μ+Μ-K*0, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Oct 1999

Search For The Flavor-Changing Neutral Current Decays B+→ Μ+Μ-K+ And B0→ Μ+Μ-K*0, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We report on a search for the flavor-changing neutral current decays B+→ μ+μ-K+ and i>B0→ μ+μ-K*0 using 88 pb-1 of data from p̅p collisions at √s =1.8 TeV, collected with the Collider Detector at Fermilab. Finding no evidence for these decays, we set upper limits on the branching fractions Ɓ(B+→ μ+μ-K+) < 5.2 X 10-6 and Ɓ(B+→ μ+μ-K*0) -6 at the 90% confidence level.

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Search For A Technicolor ΩT Particle In Events With A Photon And A B-Quark Jet At Fermilab, F. Abe, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Oct 1999

Search For A Technicolor ΩT Particle In Events With A Photon And A B-Quark Jet At Fermilab, F. Abe, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

If the technicolor ωT particle exists, a likely decay mode is ωT→ γπT , followed by πT → bb̅, yielding the signature γbb̅. We have searched 85 pb-1 of data collected by the CDF experiment at the Fermilab Tevatron for events with a photon and two jets, where one of the jets must contain a secondary vertex implying the presence of a b quark. We find no excess of events above standard model expectations. We express the result as an exclusion region in the MωT -MπT …

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Measurement Of B0-B̅0 Flavor Oscillations Using Jet-Charge And Lepton Flavor Tagging In Pp̅ Collisions At √S =1.8 Tev, F. Abe, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Oct 1999

Measurement Of B0-B̅0 Flavor Oscillations Using Jet-Charge And Lepton Flavor Tagging In Pp̅ Collisions At √S =1.8 Tev, F. Abe, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We present a measurement of the mass difference Δmd for the B0 meson and the statistical power of the b flavor tagging methods used. The measurement uses 90 pb-1 of data from pp̅ collisions at √s =1.8 TeV collected with the CDF detector. An inclusive lepton trigger is used to collect a large sample of B hadron semileptonic decays. The mass difference Δmd is determined from the proper time dependence of the fraction of B hadrons that undergo flavor oscillations. The flavor at decay is inferred from the charge of the lepton from semileptonic …

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A Simplified Gaas Polarized Electron Source, H. M. Al-Khateeb, B. G. Birdsey, T. C. Bowen, A. S. Green, M. E. Johnston, Timothy J. Gay Oct 1999

A Simplified Gaas Polarized Electron Source, H. M. Al-Khateeb, B. G. Birdsey, T. C. Bowen, A. S. Green, M. E. Johnston, Timothy J. Gay

Timothy J. Gay Publications

We report operational and construction details of a simplified GaAs polarized electron source. It is contained in a modified 4.63 in. Conflat four-way cross, and uses a single 56 ℓ /s turbomolecular pump. The design incorporates multiple cesiators to extend source lifetime, a new spring-clamp GaAs crystal mounting design to provide uniform crystal heating, and a very simple tubular 90° electrostatic deflector. We also discuss matters related to preparing, heat cleaning, and activating the GaAs crystal.

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Multiphoton Ionization Of V, Cr, Y, La, And Ir Through 0.5-Ps Ultraviolet Laser Pulses, B. Witzel, N. A. Poppadogiannis, Cornelis J. Uiterwaal, H. Schröder, D. Charalambidis Oct 1999

Multiphoton Ionization Of V, Cr, Y, La, And Ir Through 0.5-Ps Ultraviolet Laser Pulses, B. Witzel, N. A. Poppadogiannis, Cornelis J. Uiterwaal, H. Schröder, D. Charalambidis

C.J.G.J. Uiterwaal Publications

The two-photon ionization of the metal atoms V, Cr, Y, La, and Ir sputtered by an Ar-ion gun from solid targets has been investigated using linearly polarized laser pulses of 500- fs duration and 248.6-nm (KrF) wavelength in combination with mass spectroscopy that is free of volume effects. A near-resonant ionization process has to be attributed to all five atoms. By fitting analytical solutions of a rate equation model describing the temporal evolution of the ionization process, we can determine absolute values of the one-photon cross sections and saturation intensities.

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High-Order Harmonic Generation In Magnetic And Parallel Magnetic And Electric Fields, Dejan B. Miloševic, Anthony F. Starace Oct 1999

High-Order Harmonic Generation In Magnetic And Parallel Magnetic And Electric Fields, Dejan B. Miloševic, Anthony F. Starace

Anthony F. Starace Publications

We demonstrate control of high-harmonic generation (HHG) by a linearly polarized laser field using uniform static magnetic and electric fields parallel to the laser polarization. We show that the harmonic intensity can be considerably increased for particular values of the magnetic field. The maximum values of the harmonic intensity correspond to such values of magnetic induction for which an integer multiple of the classical cyclotron period of the electron’s motion perpendicular to the magnetic field is equal to the return time of the ionized electron wave packet to the nucleus under the influence of the laser field (and static electric …

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Search For R-Parity Violating Supersymmetry Using Like-Sign Dielectrons In Pp̅ Collisions At √S = 1.8 Tev, F. Abe, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Sep 1999

Search For R-Parity Violating Supersymmetry Using Like-Sign Dielectrons In Pp̅ Collisions At √S = 1.8 Tev, F. Abe, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We present a search for like-sign dielectron plus multijet events using 107 pb-1 of data in pp̅ collisions at √s =1.8 TeV collected in 1992–1995 by the CDF experiment. Finding no events that pass our selection, we set σ X BR limits on two supersymmetric processes that can produce this experimental signature: gluino-gluino or squark-antisquark production with R-parity violating decays of the charm squark or lightest neutralino via a nonzero λ′121 coupling. We compare our results to the next-to-leading order calculations for gluino and squark production cross sections and set lower limits on M (g̃), M (t̃ …

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Scaling Effect On Statistical Behavior Of Switching Parameters Of Ferroelectric Capacitors, Alexei Gruverman Sep 1999

Scaling Effect On Statistical Behavior Of Switching Parameters Of Ferroelectric Capacitors, Alexei Gruverman

Alexei Gruverman Publications

Scanning force microscopy (SFM) has been used to study nanoscale variations in switching parameters in layered perovskite films of SrBi2Ta2O9 and to investigate the effect of capacitor scaling on the standard deviation of the capacitors’ integral polarization signal. Ferroelectric poling and SFM piezoresponse imaging were performed in a number of regions on the film surface sized 2x2, 1x1, 0.5x0.5, and 0.3x0.3 μm2 with subsequent statistical analysis of the obtained data. It has been found that variations of the polarization signal can be approximated by the normal distribution function. The standard deviation increases with the …

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Correlation Of Co(Llo)/Cr(002) Texture And Magnetic Properties In Cocrtapt Granular Films, Z.S. Shan, C.P. Luo, M. Azarisooreh, K. Honardoost, M. Russak, Yi Liu, J. Ping Liu, David J. Sellmyer Sep 1999

Correlation Of Co(Llo)/Cr(002) Texture And Magnetic Properties In Cocrtapt Granular Films, Z.S. Shan, C.P. Luo, M. Azarisooreh, K. Honardoost, M. Russak, Yi Liu, J. Ping Liu, David J. Sellmyer

David Sellmyer Publications

Studies of the effects of substrate temperature T, on the evolution of CO( 1 10)/Cr(002) texture, magnetic and physical grain size, intergrain-interaction, anisotropy, orientation ratio of remanence and coercivity were investigated experimentally. It is found that the hcp- Co(l10)hcc-Cr(002) texture is improved with increasing T, from 27OC to 265°C. The intergrain-interaction, magnetic and physical grain size decrease with increasing Ts and reach their minima at T,- 265°C where the magnetic grain size is close to the physical grain size. The correlation between the film microstructure and magnetic properties is studied systematically.

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High Energy Products In Exchange-Coupled Nanocomposite Films, J. Ping Liu, Yi Liu, Ralph Skomski, David J. Sellmyer Sep 1999

High Energy Products In Exchange-Coupled Nanocomposite Films, J. Ping Liu, Yi Liu, Ralph Skomski, David J. Sellmyer

David Sellmyer Publications

Several systems of nanocomposite thin films have been prepared by plasma sputtering and heat treatment. By choosing suitable multilayer structures of the as-deposited films and subsequent heat-treatment processes, the nanostrnctures of the films have been tailored. The thermal processing is the key to control the morphology. Appropriate heat-treatment processes have been found for the systems studied, which result in the desired nanostructures. For the first time a nearly ideal nanostructure with the soft-phase grains embedded homogeneously in the hard phase gralns has been obtained for the FePt-Fei.,Pt,(x-0.3) system. Effective intergrain exchange coupling has been realized. As a consequence, high energy …

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Measurement Of The BD0B̅D0 Oscillation Frequency Using Dimuon Data In Pp̅ Collisions At √S =1.8tev, F. Abe, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Sep 1999

Measurement Of The BD0B̅D0 Oscillation Frequency Using Dimuon Data In Pp̅ Collisions At √S =1.8tev, F. Abe, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We present a measurement of the mass difference Δmd of the two Bd0 mass eigenstates. We use a flavor tagging method based on the lepton charge, in a sample of events with two muons at low transverse momentum. The sample corresponds to an integrated luminosity of 90 pb-1 collected by the Collider Detector at Fermilab. The result obtained is Dmd=0.503±0.064(stat) ±0.071(syst) ps-1.

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Quasicoherent Nucleation Mode In Two-Phase Nanomagnets, Ralph Skomski, J. Ping Liu, David J. Sellmyer Sep 1999

Quasicoherent Nucleation Mode In Two-Phase Nanomagnets, Ralph Skomski, J. Ping Liu, David J. Sellmyer

David Sellmyer Publications

Magnetization processes in advanced magnetic nanostructures are investigated. For the case of spherical soft or semihard grains surrounded by a very hard matrix a bulging nucleation mode is discovered. The bulging mode exhibits the radial angular symmetry of the coherent mode, but it is incoherent due to its radial variation. The radial dependence of the bulging mode is obtained by solving a spherical Bessel equation which is subject to appropriate boundary conditions. In contrast to the coherent mode, the bulging mode yields a nucleationfield coercivity which depends on the exchange stiffness and on the size of the grain. There is …

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Comparison Of Magnetic Images Using Point And Thin-Film Magnetic Force Microscopy Tips, Sy_Hwang Liou Sep 1999

Comparison Of Magnetic Images Using Point And Thin-Film Magnetic Force Microscopy Tips, Sy_Hwang Liou

Sy-Hwang Liou Publications

The magnetic images of a magnetic reference sample were compared using point and thin-film magnetic force microscopy (MFM) tips. The thin film MFM tip was made by magnetron sputtering of an amorphous metal. The point MFM tip was made by an ion milling process that produces a small magnetic particle on the cantilever. Our results clearly demonstrated that the volume of magnetic material involved in the tip-sample interaction is much reduced in the case of the point tip compared to that of the thin film tips. By comparing the magnetic images of a tri-bit pattern on a magnetic reference sample, …

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Switching Properties Of Self-Assembled Ferroelectric Memory Cells, M. Alexe, Alexei Gruverman, C. Harnagea, N. D. Zakharov, A. Pignolet, D. Hesse, J. F. Scott Aug 1999

Switching Properties Of Self-Assembled Ferroelectric Memory Cells, M. Alexe, Alexei Gruverman, C. Harnagea, N. D. Zakharov, A. Pignolet, D. Hesse, J. F. Scott

Alexei Gruverman Publications

In this letter, we report on the switching properties of an ordered system of Bi4Ti3O12 ferroelectric memory cells of an average lateral size of 0.18 μm formed via a self-assembling process. The ferroelectricity of these cells has been measured microscopically and it has been demonstrated that an individual cell of 0.18 μm size is switching. Switching of single nanoelectrode cells was achieved via scanning force microscopy working in piezoresponse mode.

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The Effect Of Abundance Variations On Estimates Of The Densities Of Broad-Line Region Clouds In Quasars, Stephanie A. Snedden, C. Martin Gaskell Aug 1999

The Effect Of Abundance Variations On Estimates Of The Densities Of Broad-Line Region Clouds In Quasars, Stephanie A. Snedden, C. Martin Gaskell

C. Martin Gaskell Publications

There has been a long-standing discrepancy between the densities deduced from studies of the variability of quasar emission lines and those inferred from standard photoionization analyses. We have found that the higher metal abundances now believed to be present in most quasars lead to the higher densities being predicted by photoionization models. We explain why this is so.

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Online Track Processor For The Cdf Upgrade, C. Ciobanu, J. Gerstenslager, J. Hoftiezer, R. Hughes, M. Johnson, P. Koehn, C. Neu, C. Sanchez, B.L. Winer, J. Freeman, S. Holm, J.D. Lewis, T. Shaw, T. Wesson, Kenneth A. Bloom, D. Gerdes, J.W. Dawson, W.N. Haberichter Aug 1999

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

Kenneth Bloom Publications

A trigger track processor is being designed for the CDF upgrade. This processor identifies high momentum (PT > 1.5 GeV/c) charged tracks in the new central outer tracking chamber for CDF 11. The track processor is called the extremely Fast Tracker (XFT). The XFT design is highly parallel to handle the input rate of 183 Gbits/sec and output rate of 44 Gbitslsec. The processor is pipelined and reports the results 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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