Sample records for vortex-state complex hall

  1. Intermittent trapping of a liquid-like vortex state visualized by scanning Hall probe microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Crisan, A; Bending, S J [Department of Physics, University of Bath, Claverton Down, Bath BA2 7AY (United Kingdom); Li, Z Z; Raffy, H [Laboratoire de Physique des Solides, Universite Paris-Sud, Batiment 510, UMR 8502, 91405 Orsay (France)


    We have used scanning Hall probe microscopy to investigate vortex structures and vortex dynamics in Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} thin films in very low perpendicular magnetic fields. After nominally zero field cooling in the Earth's field we find that the vortices appear to be in a stable glassy state in our highly disordered samples. After applying a cancellation field of a few Oersted at low temperature, however, the system enters a new regime at very low magnetic induction when the only image contrast is due to vortices that are intermittently trapped on strong pinning centres. This state shares many of the signatures of the re-entrant vortex liquid phase that has been theoretically predicted in these highly anisotropic materials at very low vortex densities. Analysing the trapping times for vortices in the fluctuating state we estimate that the pinning potential of typical strong pinning centres is about 900 K under our experimental conditions. To our knowledge, this is the first direct experimental evidence for the existence of a dynamic liquid-like vortex state in this highly anisotropic material at very low magnetic induction.

  2. The effect of Ni and Fe doping on Hall anomaly in vortex state of doped YBCO samples

    Directory of Open Access Journals (Sweden)

    M Nazarzadeh


    Full Text Available We have investigated hall effect on YBa2Cu3-xMxO7-δ (M=Ni, Fe bulk samples, with dopant amount 0 ≤ x ≤ 0.045 for Ni and 0 ≤ x ≤ 0.03 for Fe, with magnetic field (H=2.52, 4.61, 6.27 kOe perpendicular to sample’s surface with constant current 100 mA. Our study shows that as both dopants increases, TC decreases and it decreases faster by Ni . In these ranges of dopant and magnetic field the Hall sign reversal has been observed in all samples once and also ∆max has occurred in lower temperatures, its magnitude increases by Ni, and in Fe doped samples except in sample with dopant amount x=0.03, which almost decreases, that it can show effect of magnetic doping on hall effect.

  3. Theory and applications of free-electron vortex states (United States)

    Bliokh, K. Y.; Ivanov, I. P.; Guzzinati, G.; Clark, L.; Van Boxem, R.; Béché, A.; Juchtmans, R.; Alonso, M. A.; Schattschneider, P.; Nori, F.; Verbeeck, J.


    Both classical and quantum waves can form vortices : entities with helical phase fronts and circulating current densities. These features determine the intrinsic orbital angular momentum carried by localized vortex states. In the past 25 years, optical vortex beams have become an inherent part of modern optics, with many remarkable achievements and applications. In the past decade, it has been realized and demonstrated that such vortex beams or wavepackets can also appear in free electron waves, in particular, in electron microscopy. Interest in free-electron vortex states quickly spread over different areas of physics: from basic aspects of quantum mechanics, via applications for fine probing of matter (including individual atoms), to high-energy particle collision and radiation processes. Here we provide a comprehensive review of theoretical and experimental studies in this emerging field of research. We describe the main properties of electron vortex states, experimental achievements and possible applications within transmission electron microscopy, as well as the possible role of vortex electrons in relativistic and high-energy processes. We aim to provide a balanced description including a pedagogical introduction, solid theoretical basis, and a wide range of practical details. Special attention is paid to translating theoretical insights into suggestions for future experiments, in electron microscopy and beyond, in any situation where free electrons occur.

  4. Vortex state in a {ital d}-wave superconductor

    Energy Technology Data Exchange (ETDEWEB)

    Franz, M.; Kallin, C.; Soininen, P.I. [Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, L8S4M1 (CANADA); Berlinsky, A.J. [Brockhouse Institute for Materials Research, McMaster University, Hamilton, Ontario, L8S4M1 (CANADA); Fetter, A.L. [Department of Physics, Stanford University, Stanford, California 94305 (United States)


    We discuss the physics of the vortex state in a {ital d}-wave superconductor, using the phenomenological Ginzburg-Landau theory, where many unusual phenomena arise from the small admixture of the {ital s}-wave component induced by spatial variations in the dominant {ital d} wave. Properties of an isolated vortex and of the Abrikosov vortex lattice are studied by means of analytic and numerical methods. An isolated vortex has a considerable structure, with four {open_quote}{open_quote}extra{close_quote}{close_quote} nodes in the {ital s}-wave order parameter symmerically placed around the core and an amplitude forming a four-lobe profile decaying as 1/{ital r}{sup 2} at large distances. The supercurrent and magnetic-field distributions are also calculated. The Abrikosov lattice is in general oblique with the precise shape determined by the magnetic field and {ital s}-{ital d} mixing parameter {epsilon}{sub {ital v}}. The magnetic-field distribution in the Abrikosov state has two nonequivalent saddle points resulting in the prediction of a double peak line shape in {mu}SR and NMR experiments as a test of a {ital d}-wave symmetry. Detailed comparison is made with existing experimental data and experiments are proposed to test for the predicted effects. {copyright} {ital 1996 The American Physical Society.}

  5. Hall effect in CNT doped YBCO high temperature superconductor

    Directory of Open Access Journals (Sweden)

    S Dadras


    Full Text Available In order to study Hall effect in pure and CNT doped YBCO polycrystalline samples, we have measured longitudinal and transverse voltages at the different magnetic field (0-9T in the vortex state. We found a sign reversal for pure sample near 3T and double sign reversal of the Hall coefficient for CNT doped sample near 3 and 5T. It can be deduced that CNT doping caused strong flux pinning and Hall double sign reversal in this compound.

  6. Direct evidence of imprinted vortex states in the antiferromagnet of exchange biased microdisks (United States)

    Salazar-Alvarez, G.; Kavich, J. J.; Sort, J.; Mugarza, A.; Stepanow, S.; Potenza, A.; Marchetto, H.; Dhesi, S. S.; Baltz, V.; Dieny, B.; Weber, A.; Heyderman, L. J.; Nogués, J.; Gambardella, P.


    The magnetic domain structure of patterned antiferromagnetic/ferromagnetic Ir20Mn80/Ni80Fe20 bilayer microdisk arrays has been investigated using layer-specific polarized x-ray photoemission electron microscopy and magnetic circular dichroism. Magnetic imaging at the Fe and Mn L-edge resonances provided direct evidence of a vortex state imprinted into the antiferromagnet at the interface. The opposite magnetic contrast between the layers indicated a reversed chirality of the imprinted vortex state, and a quantitative analysis of the magnetic moment from the dichroism spectra showed that uncompensated Mn spins equivalent to about 60% of a monolayer of bulk Ir20Mn80 contributed to the imprinted information at the interface.

  7. Field effects on the vortex states in spin–orbit coupled Bose–Einstein condensates

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Liang-Liang; Liu, Yong-Kai; Feng, Shiping; Yang, Shi-Jie, E-mail:


    Multi-quantum vortices can be created in the ground state of rotating Bose–Einstein condensates with spin–orbit couplings. We investigate the effects of external fields, either a longitudinal field or a transverse field, on the vortex states. We reveal that both fields can effectively reduce the number of vortices. In the latter case we further find that the condensate density packets are pushed away in the horizontal direction and the vortices finally disappear to form a plane wave phase. - Highlights: • Vortex states of rotational spin–orbit coupled BEC have been studied. • Both longitudinal field and transverse field reduce vortices. • The transverse field pushes condensates to one direction.

  8. Magnetic vortex state and multi-domain pattern in electrodeposited hemispherical nanogranular nickel films

    Energy Technology Data Exchange (ETDEWEB)

    Samardak, Alexander; Sukovatitsina, Ekaterina; Ognev, Alexey; Stebliy, Maksim; Davydenko, Alexander; Chebotkevich, Ludmila [Laboratory of Thin Film Technologies, School of Natural Sciences, Far Eastern Federal University, Vladivostok (Russian Federation); Keun Kim, Young [Department of Materials Science and Engineering, Korea University, Seoul (Korea, Republic of); Nasirpouri, Forough [Department of Physics, University of Tabriz, Tabriz (Iran, Islamic Republic of); Janjan, Seyed-Mehdi [Faculty of Materials Engineering, Sahand University of Technology, Tabriz 51335-1996 (Iran, Islamic Republic of); Nasirpouri, Farzad, E-mail: [Faculty of Materials Engineering, Sahand University of Technology, Tabriz 51335-1996 (Iran, Islamic Republic of)


    Magnetic states of nickel nanogranular films were studied in two distinct structures of individual and agglomerated granules electrodeposited on n-type Si(1 1 1) surface from a modified Watts bath at a low pH of 2. Magnetic force microscopy and micromagnetic simulations revealed three-dimensional out-of-plane magnetic vortex states in stand-alone hemispherical granules and their arrays, and multi-domain patterns in large agglomerates and integrated films. Once the granules coalesce into small chains or clusters, the coercivity values increased due to the reduction of inter-granular spacing and strengthening of the magnetostatic interaction. Further growth leads to the formation of a continuous granulated film which strongly affected the coercivity and remanence. This was characterized by the domain wall nucleation and propagation leading to a stripe domain pattern. Magnetoresistance measurements as a function of external magnetic field are indicative of anisotropic magnetoresistance (AMR) for the continuous films electrodeposited on Si substrate. - Highlights: • Magnetic states of electrodeposited nickel in isolated spherical and agglomerated nanogranules, and a continuous film. • Preferential magnetization reversal mechanism in isolated granules is vortex state. • Micromagnetic simulations confirm the three-dimensional vortex. • Transition between the vortex state and multi-domain magnetic pattern causes a significant decrease in the coercive force. • Continuous nickel films electrodeposited on silicon substrate exhibit AMR whose magnitude increases with the film thickness.

  9. Direct observation of imprinted antiferromagnetic vortex state in CoO/Fe/Ag(001) disks

    Energy Technology Data Exchange (ETDEWEB)

    Wu, J.; Carlton, D.; Park, J. S.; Meng, Y.; Arenholz, E.; Doran, A.; Young, A.T.; Scholl, A.; Hwang, C.; Zhao, H. W.; Bokor, J.; Qiu, Z. Q.


    In magnetic thin films, a magnetic vortex is a state in which the magnetization vector curls around the center of a confined structure. A vortex state in a thin film disk, for example, is a topological object characterized by the vortex polarity and the winding number. In ferromagnetic (FM) disks, these parameters govern many fundamental properties of the vortex such as its gyroscopic rotation, polarity reversal, core motion, and vortex pair excitation. However, in antiferromagnetic (AFM) disks, though there has been indirect evidence of the vortex state through observations of the induced FM-ordered spins in the AFM disk, they have never been observed directly in experiment. By fabricating single crystalline NiO/Fe/Ag(001) and CoO/Fe/Ag(001) disks and using X-ray Magnetic Linear Dichroism (XMLD), we show direct observation of the vortex state in an AFM disk of AFM/FM bilayer system. We observe that there are two types of AFM vortices, one of which has no analog in FM structures. Finally, we show that a frozen AFM vortex can bias a FM vortex at low temperature.

  10. Negative velocity fluctuations and non-equilibrium fluctuation relation for a driven high critical current vortex state. (United States)

    Bag, Biplab; Shaw, Gorky; Banerjee, S S; Majumdar, Sayantan; Sood, A K; Grover, A K


    Under the influence of a constant drive the moving vortex state in 2H-NbS2 superconductor exhibits a negative differential resistance (NDR) transition from a steady flow to an immobile state. This state possesses a high depinning current threshold ([Formula: see text]) with unconventional depinning characteristics. At currents well above [Formula: see text], the moving vortex state exhibits a multimodal velocity distribution which is characteristic of vortex flow instabilities in the NDR regime. However at lower currents which are just above [Formula: see text], the velocity distribution is non-Gaussian with a tail extending to significant negative velocity values. These unusual negative velocity events correspond to vortices drifting opposite to the driving force direction. We show that this distribution obeys the Gallavotti-Cohen Non-Equilibrium Fluctuation Relation (GC-NEFR). Just above [Formula: see text], we also find a high vortex density fluctuating driven state not obeying the conventional GC-NEFR. The GC-NEFR analysis provides a measure of an effective energy scale (E eff ) associated with the driven vortex state. The E eff corresponds to the average energy dissipated by the fluctuating vortex state above [Formula: see text]. We propose the high E eff value corresponds to the onset of high energy dynamic instabilities in this driven vortex state just above [Formula: see text].

  11. Hall C (United States)

    Federal Laboratory Consortium — Hall C's initial complement of equipment (shown in the figure), includes two general-purpose magnetic spectrometers. The High Momentum Spectrometer (HMS) has a large...

  12. Hall A (United States)

    Federal Laboratory Consortium — The instrumentation in Hall A at the Thomas Jefferson National Accelerator Facility was designed to study electroand photo-induced reactions at very high luminosity...

  13. Geometry of laccolith margins: 2D and 3D models of the Late Paleozoic Halle Volcanic Complex (Germany) (United States)

    Schmiedel, T.; Breitkreuz, C.; Görz, I.; Ehling, B.-C.


    Well data and core samples from the Late Paleozoic Halle Volcanic Complex (HVC) have been used to describe the geometry of the rhyolitic porphyritic laccoliths and their margins. The HVC formed between 301 and 292 Ma in the intramontane Saale basin, and it comprises mainly rhyolitic subvolcanic bodies (~300 km3) as well as minor lava flows and volcaniclastic deposits. The major HVC laccolith units display aspect ratios ranging between 0.04 and 0.07, and they are separated by tilted and deformed Carboniferous-Permian host sediments. For the margin of the Landsberg laccolith, a major coarsely porphyritic unit of the HVC, an exceptional data set of 63 wells concentrated in an area of 10 km2 reaching to depth of 710 m exists. It was used to explore the 3D geometry and textures, and to deduce an intrusion model. For a 3D visualization of the Landsberg laccolith margin, Geological Object Computer Aided Design; Paradigm® software (GOCAD) was used. Curve objects have been derived from the intrusion-host contacts. Automated GOCAD® methods for 3D modelling failed. As a result, manual refinement was essential. A major finding of the 3D modelling is the presence of prolate sediment rafts, up to 1,400 m in length and up to 500 m in thickness, surrounded by Landsberg rhyolite. The sedimentary rafts dip away from the laccolith centre. The engulfing laccolith sheets reach thickness of 100-300 m. For other HVC laccolith units (Löbejün, Petersberg, Brachstedt), well data reveal vertical rhyolite/sediment contacts or magma lobes fingering into the host sediments. HVC laccolith contact textures include small-scale shearing of the intruding magma and of the host sediment. In addition, internal shear zones have been detected inside the rhyolite bodies. The present study suggests that the emplacement of successive magma sheets was an important process during laccolith growth in the HVC.

  14. Generation and Detection of Continuous Variable Quantum Vortex States via Compact Photonic Devices

    Directory of Open Access Journals (Sweden)

    David Barral


    Full Text Available A quantum photonic circuit with the ability to produce continuous variable quantum vortex states is proposed. This device produces two single-mode squeezed states which go through a Mach-Zehnder interferometer where photons are subtracted by means of weakly coupled directional couplers towards ancillary waveguides. The detection of a number of photons in these modes heralds the production of a quantum vortex. Likewise, a measurement system of the order and handedness of quantum vortices is introduced and the performance of both devices is analyzed in a realistic scenario by means of the Wigner function. These devices open the possibility of using the quantum vortices as carriers of quantum information.

  15. Complex Terahertz and Direct Current Inverse Spin Hall Effect in YIG/Cu1-xIrx Bilayers Across a Wide Concentration Range. (United States)

    Cramer, Joel; Seifert, Tom; Kronenberg, Alexander; Fuhrmann, Felix; Jakob, Gerhard; Jourdan, Martin; Kampfrath, Tobias; Kläui, Mathias


    We measure the inverse spin Hall effect of Cu1-xIrx thin films on yttrium iron garnet over a wide range of Ir concentrations (0.05 ⩽ x ⩽ 0.7). Spin currents are triggered through the spin Seebeck effect, either by a continuous (dc) temperature gradient or by ultrafast optical heating of the metal layer. The spin Hall current is detected by electrical contacts or measurement of the emitted terahertz radiation. With both approaches, we reveal the same Ir concentration dependence that follows a novel complex, nonmonotonous behavior as compared to previous studies. For small Ir concentrations a signal minimum is observed, whereas a pronounced maximum appears near the equiatomic composition. We identify this behavior as originating from the interplay of different spin Hall mechanisms as well as a concentration-dependent variation of the integrated spin current density in Cu1-xIrx. The coinciding results obtained for dc and ultrafast stimuli provide further support that the spin Seebeck effect extends to terahertz frequencies, thus enabling a transfer of established spintronic measurement schemes into the terahertz regime. Our findings also show that the studied material allows for efficient spin-to-charge conversion even on ultrafast time scales.

  16. Forming superposition of vortex states in Bose-Einstein condensates by a non-paraxial Laguerre-Gaussian beam

    CERN Document Server

    Bhowmik, Anal; Majumder, Sonjoy; Deb, Bimalendu


    The exchange of orbital angular momentum (OAM) between optical vortex and the center-of-mass (c.m.) motion of an atom or molecule is well known in paraxial approximation. We show here the possible superposition of vortex states with different angular momentum in condensed atoms in interaction with focused optical vortex field. Since, spin angular momentum (SAM) is coupled with OAM of the focused field, both angular momenta are now possible to be transferred to the internal electronic and external c.m. motion of atom provided both the motions are coupled. We study how two-photon Rabi frequencies of stimulated Raman transitions vary with focusing angles for different combinations of OAM and SAM of optical states. We demonstrate the possible generation of vortex-antivortex structure and discuss the interference of three vortex states in a single component Bose-Einstein condensate.

  17. Instability of Non-vortex State toward a Quantized Vortex in Bose-Einstein Condensate under External Rotation


    Isoshima, Tomoya; Machida, Kazushige


    The instability condition of the non-vortex state toward vortex formation is exa mined within the Bogoliubov theory when a Bose-Einstein condensate is under exte rnally forced rotation. The obtained critical angular velocity combined with the previous stability cond itions for a votex yields a detailed phase diagram in the critical velocity vs t he system parameter. This facilitates vortex formation experiments for alkali atom gases confined in a harmonic potential.

  18. Investigation of the Vortex States of Sr2RuO4-Ru Eutectic Microplates Using DC-SQUIDs (United States)

    Sakuma, Daisuke; Nago, Yusuke; Ishiguro, Ryosuke; Kashiwaya, Satoshi; Nomura, Shintaro; Kono, Kimitoshi; Maeno, Yoshiteru; Takayanagi, Hideaki


    We investigated the magnetic properties of a Sr2RuO4-Ru eutectic microplate containing a single Ru-inclusion using micrometer-sized DC-SQUIDs (direct-current superconducting quantum interference devices). A phase frustration at the interface between chiral p-wave superconducting Sr2RuO4 and s-wave superconducting Ru is expected to cause novel magnetic vortex states such as the spontaneous Ru-center vortex under zero magnetic field [as reported by H. Kaneyasu and M. Sigrist," xlink:type="simple">J. Phys. Soc. Jpn. 79, 053706 (2010)]. Our experimental results show no positive evidence for such a spontaneous vortex state. However, in an applied field, an abrupt change in the magnetic flux distribution was observed at a superconducting transition of Ru. The flux distribution is clarified by comparing our experimental results with electromagnetic field simulations in our sample geometry. We discuss the transition of the vortex states and the superconducting coupling at the Sr2RuO4/Ru interface.

  19. Laurance David Hall. (United States)

    Coxon, Bruce


    An account is given of the life, scientific contributions, and passing of Laurance David Hall (1938-2009), including his early history and education at the University of Bristol, UK, and the synthesis and NMR spectroscopy of carbohydrates and other natural products during ∼20 years of research and teaching at the University of British Columbia in Vancouver, Canada. Lists of graduate students, post-doctoral fellows, and sabbatical visitors are provided for this period. Following a generous endowment by Dr. Herchel Smith, Professor Hall built a new Department of Medicinal Chemistry at Cambridge University, UK, and greatly expanded his researches into the technology and applications of magnetic resonance imaging (MRI) and zero quantum NMR. MRI technology was applied both to medical problems such as the characterization of cartilage degeneration in knee joints, the measurement of ventricular function, lipid localization in animal models of atherosclerosis, paramagnetic metal complexes of polysaccharides as contrast agents, and studies of many other anatomical features, but also to several aspects of materials analysis, including food analyses, process control, and the elucidation of such physical phenomena as the flow of liquids through porous media, defects in concrete, and the visualization of fungal damage to wood. Professor Hall's many publications, patents, lectures, and honors and awards are described, and also his successful effort to keep the Asilomar facility in Pacific Grove, California as the alternating venue for the annual Experimental NMR Conference. Two memorial services for Professor Hall are remembered. Copyright © 2011 Elsevier Inc. All rights reserved.

  20. Divacancy-hydrogen complexes in dislocation-free high-purity germanium. [Annealing, Hall effect, steady-state concentration energy dependence

    Energy Technology Data Exchange (ETDEWEB)

    Haller, E.E.; Hubbard, G.S.; Hansen, W.L.; Seeger, A.


    A defect center with a single acceptor level at E/sub v/ + 0.08 eV appears in H/sub 2/-grown dislocation-free high-purity germanium. Its concentration changes reversibly upon annealing up to 650 K. By means of Hall-effect and conductivity measurements over a large temperature range the temperature dependence of the steady-state concentration between 450 and 720 K as well as the transients following changes in temperature were determined. The observed acceptor level is attributed to the divacancy-hydrogen complex V/sub 2/H. The complex reacts with hydrogen, dissolved in the Ge lattice or stored in traps, according to V/sub 2/H + H reversible V/sub 2/H/sub 2/. An energy level associated with the divacancy-dihydrogen complex was not observed. These results are in good agreement with the idea that hydrogen in germanium forms a ''very deep donor'' (i.e., the energy level lies inside the valence band).

  1. Observation of Caroli-de Gennes-Matricon Vortex States in YBa2Cu3O7 -δ (United States)

    Berthod, Christophe; Maggio-Aprile, Ivan; Bruér, Jens; Erb, Andreas; Renner, Christoph


    The copper oxides present the highest superconducting temperature and properties at odds with other compounds, suggestive of a fundamentally different superconductivity. In particular, the Abrikosov vortices fail to exhibit localized states expected and observed in all clean superconductors. We have explored the possibility that the elusive vortex-core signatures are actually present but weak. Combining local tunneling measurements with large-scale theoretical modeling, we positively identify the vortex states in YBa2Cu3O7 -δ . We explain their spectrum and the observed variations thereof from one vortex to the next by considering the effects of nearby vortices and disorder in the vortex lattice. We argue that the superconductivity of copper oxides is conventional, but the spectroscopic signature does not look so because the superconducting carriers are a minority.

  2. Skyrmions and Hall viscosity


    Kim, Bom Soo


    We discuss the contribution of magnetic Skyrmions to the Hall viscosity and propose a simple way to identify it in experiments. The topological Skyrmion charge density has a distinct signature in the electric Hall conductivity that is identified in existing experimental data. In an electrically neutral system, the Skyrmion charge density is directly related to the thermal Hall conductivity. These results are direct consequences of the field theory Ward identities, which relate various physica...

  3. Quantum Spin Hall Effect

    Energy Technology Data Exchange (ETDEWEB)

    Bernevig, B.Andrei; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.


    The quantum Hall liquid is a novel state of matter with profound emergent properties such as fractional charge and statistics. Existence of the quantum Hall effect requires breaking of the time reversal symmetry caused by an external magnetic field. In this work, we predict a quantized spin Hall effect in the absence of any magnetic field, where the intrinsic spin Hall conductance is quantized in units of 2 e/4{pi}. The degenerate quantum Landau levels are created by the spin-orbit coupling in conventional semiconductors in the presence of a strain gradient. This new state of matter has many profound correlated properties described by a topological field theory.

  4. The response of a complex Data Centre chilled water system to an unplanned site-wide power failure and the influence on the Data halls

    Energy Technology Data Exchange (ETDEWEB)

    Farsimadan, E.; Stec, W.; Howe, M.R. [Cundall LLP, Saffron House, 6-10 Kirby Street, London EC1N 8TS (United Kingdom)


    The paper describes the modelling and analysis of a 10 MW chilled water distribution system that is used for the cooling of parallel Data halls. During an unplanned site power failure, the Chillers may go offline for some minutes, affecting the temperature and delivery of chilled water to the Data hall cooling units. This may cause the air temperature within the Data halls to rise. The ultimate test of robustness is to ensure that the IT equipment is adequately cooled during this time. This work outlines the key findings from the thermal response of the cooling system to a site power failure. The entire chilled water network that comprised the primary and secondary plant was modelled, including components such as pumps, valves and Chillers. A transient analysis was conducted to predict the rise in water temperature at different locations in the system. Computational fluid dynamics was then adopted to predict the air temperature reaching the IT equipment, therefore confirming the capability of the design to steer clear of effects such as thermal runaway. The findings demonstrate that confidence in the omission of expensive buffer vessels and UPS backed plant could not have been achieved without the advanced transient analysis conducted here. (author)

  5. Halls Lake 1990 (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Salt marsh habitats along the shoreline of Halls Lake are threatened by wave erosion, but the reconstruction of barrier islands to reduce this erosion will modify or...

  6. General footage ISOLDE experimental hall

    CERN Multimedia


    Overview of the ISOLDE experimental hall. Equipment and experiments. Taken from the WITCH / EBIS platform: ISOLDE hall infrastructure, GHM line, LA1, LA2, LA0, central beamline, COLLAPS experiment, CRIS experiment, ISOLTRAP experiment, laser guidance from building 508 into the hall for laser spectroscopy COLLAPS and CRIS. Taken from the HIE ISOLDE shielding tunnel roof: ISOLDE hall infrastructure, WITCH experiment, VITO line, TAS experiment. General footage: High Tension room entrance and EBIS platform, staircases and passages in the experimental hall.

  7. Extraordinary hall balance (United States)

    Zhang, S. L.; Liu, Y.; Collins-McIntyre, L. J.; Hesjedal, T.; Zhang, J. Y.; Wang, S. G.; Yu, G. H.


    Magnetoresistance (MR) effects are at the heart of modern information technology. However, future progress of giant and tunnelling MR based storage and logic devices is limited by the usable MR ratios of currently about 200% at room-temperature. Colossal MR structures, on the other hand, achieve their high MR ratios of up to 106% only at low temperatures and high magnetic fields. We introduce the extraordinary Hall balance (EHB) and demonstrate room-temperature MR ratios in excess of 31,000%. The new device concept exploits the extraordinary Hall effect in two separated ferromagnetic layers with perpendicular anisotropy in which the Hall voltages can be configured to be carefully balanced or tipped out of balance. Reprogrammable logic and memory is realised using a single EHB element. PACS numbers: 85.75.Nn,85.70.Kh,72.15.Gd,75.60.Ej. PMID:23804036

  8. HEDSA Town Hall Meeting (United States)

    Afeyan, Bedros


    HEDSA will hold its Town Hall meeting on Wednesday October 25 at 12:30pm in the Wisconsin Center. The new steering committee members and HEDSA leadership will be announced. A report will be given on 2017 HEDSA activities. Program Managers from Federal Funding Agencies such as OFES, NNSA, AFOSR and NSF will provide updates on the state of sponsored research in HED plasmas, and to engage the community in an open dialogue. The HEDSA Town Hall is a ``bring your own lunch'' meeting. Current members of HEDSA and all graduate students are strongly encouraged to attend. To join HEDSA please visit

  9. Tutorial: Physics and modeling of Hall thrusters (United States)

    Boeuf, Jean-Pierre


    Hall thrusters are very efficient and competitive electric propulsion devices for satellites and are currently in use in a number of telecommunications and government spacecraft. Their power spans from 100 W to 20 kW, with thrust between a few mN and 1 N and specific impulse values between 1000 and 3000 s. The basic idea of Hall thrusters consists in generating a large local electric field in a plasma by using a transverse magnetic field to reduce the electron conductivity. This electric field can extract positive ions from the plasma and accelerate them to high velocity without extracting grids, providing the thrust. These principles are simple in appearance but the physics of Hall thrusters is very intricate and non-linear because of the complex electron transport across the magnetic field and its coupling with the electric field and the neutral atom density. This paper describes the basic physics of Hall thrusters and gives a (non-exhaustive) summary of the research efforts that have been devoted to the modelling and understanding of these devices in the last 20 years. Although the predictive capabilities of the models are still not sufficient for a full computer aided design of Hall thrusters, significant progress has been made in the qualitative and quantitative understanding of these devices.

  10. The Monty Hall Dilemma

    NARCIS (Netherlands)

    Barteld Kooi, [No Value


    Samenvatting: In het begin van de jaren negentig brak een wereldwijde discussie los over een probleem dat in het Engels 'The Monty Hall Dilemma' wordt genoemd. Marilyn vos Savant, die in het Guinness Book of World Records wordt genoemd als degene met het

  11. Halle, Prof. Thore Gustaf.

    Indian Academy of Sciences (India)

    Home; Fellowship. Fellow Profile. Elected: 1947 Honorary. Halle, Prof. Thore Gustaf. Date of birth: 25 September 1884. Date of death: 12 May 1964. YouTube; Twitter; Facebook; Blog. Academy News. IAS Logo. Theory Of Evolution. Posted on 23 January 2018. Joint Statement by the Three Science Academies of India on ...

  12. Hall Sweet Home (United States)

    Oguntoyinbo, Lekan


    Many urban and commuter universities have their sights set on students who are unlikely to connect with the college and likely to fail unless the right strategies are put in place to help them graduate. In efforts to improve retention rates, commuter colleges are looking to an unusual suspect: residence halls. The author discusses how these…

  13. La nuova Sala dedicata a Cola dell’Amatrice nel complesso francescano di Ascoli Piceno / The new Hall dedicated to Cola dell’Amatrice in the Franciscan complex of Ascoli Piceno

    Directory of Open Access Journals (Sweden)

    Enrica Petrucci


    The restoration can play a crucial role in developing a positive action for the enhancement of the architectural heritage. For the new hall dedicated to the painter architect Cola of Amatrice, recently opened in Ascoli Piceno, was implemented a strategy that has allowed us to enhance the architecture, through timely and specific measures. Through appropriate choices and best practices of construction, a neglected space in the Franciscan complex has been restored to return to the place values and meanings, encouraging the development of the historical center. The objective of the project was to transform the restored architecture in a large teca, for showing the frescoes of Cola; after long and intricate stories, they have returned to their original location, especially set up to ensure the best conditions for conservation and exhibition.

  14. Magnetometria por efeito Hall


    Fernández Pinto, Janeth


    Construímos um magnetômetro utilizando dois sensores Hall de GaAs (Toshiba- THS118) operando em um modo diferencial. Cada sensor tem um circuito préamplificador associado a ele e a diferencia de voltagem entre eles é amplificada com um ganho variável de 30 - 7000. Os sensores Hall têm dimensões típicas de 1,5 x 1,7 x 0,6 mm3 e foram montados separados um do outro de 0,71 mm, em uma configuração espacial planar. O magnetômetro foi testado usando tanto correntes dc (Idc) quant...

  15. Relativistic Hall effect. (United States)

    Bliokh, Konstantin Y; Nori, Franco


    We consider the relativistic deformation of quantum waves and mechanical bodies carrying intrinsic angular momentum (AM). When observed in a moving reference frame, the centroid of the object undergoes an AM-dependent transverse shift. This is the relativistic analogue of the spin-Hall effect, which occurs in free space without any external fields. Remarkably, the shifts of the geometric and energy centroids differ by a factor of 2, and both centroids are crucial for the Lorentz transformations of the AM tensor. We examine manifestations of the relativistic Hall effect in quantum vortices and mechanical flywheels and also discuss various fundamental aspects of this phenomenon. The perfect agreement of quantum and relativistic approaches allows applications at strikingly different scales, from elementary spinning particles, through classical light, to rotating black holes.

  16. Quantum critical Hall exponents

    CERN Document Server

    Lütken, C A


    We investigate a finite size "double scaling" hypothesis using data from an experiment on a quantum Hall system with short range disorder [1-3]. For Hall bars of width w at temperature T the scaling form is w(-mu)T(-kappa), where the critical exponent mu approximate to 0.23 we extract from the data is comparable to the multi-fractal exponent alpha(0) - 2 obtained from the Chalker-Coddington (CC) model [4]. We also use the data to find the approximate location (in the resistivity plane) of seven quantum critical points, all of which closely agree with the predictions derived long ago from the modular symmetry of a toroidal sigma-model with m matter fields [5]. The value nu(8) = 2.60513 ... of the localisation exponent obtained from the m = 8 model is in excellent agreement with the best available numerical value nu(num) = 2.607 +/- 0.004 derived from the CC-model [6]. Existing experimental data appear to favour the m = 9 model, suggesting that the quantum Hall system is not in the same universality class as th...

  17. Internal field effect on vortex states in the layered organic superconductor λ -(BETS)2Fe1 -xGaxCl4 (x =0.37 ) (United States)

    Uji, S.; Terashima, T.; Konoike, T.; Yamaguchi, T.; Yasuzuka, S.; Kobayashi, A.; Zhou, B.


    Resistance and magnetic torque measurements have been performed to investigate an internal field effect on vortex states for a layered organic superconductor λ -(BETS) 2Fe1 -xGaxCl4 (x =0.37 ), where BETS = bis(ethylenedithio)tetraselenafulvalene. Because of the internal field by the localized 3 d spins of the Fe ions, the superconducting transition temperature has a maximum at 14 T. The strongest energy dissipation due to Josephson vortex dynamics and the largest pinning of pancake vortices are observed at ˜14 T. The interlayer resistance in parallel fields shows a characteristic dip with decreasing temperature. The dip temperature decreases with increasing field, suggesting a Josephson vortex transition. At ˜23 T, we observe another small dip in the field dependence of the interlayer resistance, steep deceases of the perpendicular critical field, and diamagnetism. These results show a phase transition of the superconductivity, which is likely ascribed to an inhomogeneous superconducting transition.

  18. Analysis of the Pancharatnam-Berry phase of vector vortex states using the Hamiltonian based on the Maxwell-Schr\\"odinger equation

    CERN Document Server

    Suzuki, Masato; Oka, Kazuhiko; Toda, Yasunori; Morita, Ryuji


    We derived the Berry connection of vector vortex states (VVSs) from the "true" Hamiltonian obtained through the Maxwell--Schr\\"odinger equation for an inhomogeneous anisotropic (IA) medium, and we experimentally demonstrated measurement of the corresponding Pancharatnam--Berry (PB) geometrical phase of VVSs. The PB phase (PBP) of VVSs can be divided into two phases: homogeneous and inhomogeneous PBPs. Homogeneous and inhomogeneous PBPs are related to the conventional PBP and the spatially-dependent geometric phase given by an IA medium such as a polarization converter, respectively. We theoretically detected that inhomogeneous PBP accumulation originates from the gauge dependence of the index of the hybrid-order Poincar\\'e sphere, which provides an alternate method for understanding optical spin--orbital angular momentum conversion. The homogeneous PBP, which is explicitly observed for the first time, has implications for quantum state manipulation and information processing.

  19. Magnesium Hall Thruster (United States)

    Szabo, James J.


    This Phase II project is developing a magnesium (Mg) Hall effect thruster system that would open the door for in situ resource utilization (ISRU)-based solar system exploration. Magnesium is light and easy to ionize. For a Mars- Earth transfer, the propellant mass savings with respect to a xenon Hall effect thruster (HET) system are enormous. Magnesium also can be combusted in a rocket with carbon dioxide (CO2) or water (H2O), enabling a multimode propulsion system with propellant sharing and ISRU. In the near term, CO2 and H2O would be collected in situ on Mars or the moon. In the far term, Mg itself would be collected from Martian and lunar regolith. In Phase I, an integrated, medium-power (1- to 3-kW) Mg HET system was developed and tested. Controlled, steady operation at constant voltage and power was demonstrated. Preliminary measurements indicate a specific impulse (Isp) greater than 4,000 s was achieved at a discharge potential of 400 V. The feasibility of delivering fluidized Mg powder to a medium- or high-power thruster also was demonstrated. Phase II of the project evaluated the performance of an integrated, highpower Mg Hall thruster system in a relevant space environment. Researchers improved the medium power thruster system and characterized it in detail. Researchers also designed and built a high-power (8- to 20-kW) Mg HET. A fluidized powder feed system supporting the high-power thruster was built and delivered to Busek Company, Inc.

  20. Conjunctures, crises, and cultures: Valuing Stuart Hall


    Clarke, John


    This article explores the significance of the work of Stuart Hall for social and political anthropology. It identifies the concern with concrete conjunctural analysis, the continuing attention to the problem of hegemony, and the centrality of a politics of articulation in theory and practice as core features of Hall’s work. The article also touches on his complex relationship with theory and theorising while grounding his work in a series of political and ethical commitments within and beyond...

  1. Hall Potential Distribution in Anti-Hall bar Geometry (United States)

    Tarquini, Vinicio; Knighton, Talbot; Wu, Zhe; Huang, Jian; Pfeiffer, Loren; West, Ken

    A high quality system has been fabricated in an Anti-Hall bar geometry, by opening a 1.4 x 2.0 mm rectangular window using wet etching in the middle of a 2.4 x 3.0 mm two-dimensional high-mobility (μ = 2 . 6 × 106 cm2/(V .s)) hole system confined in a 20 nm wide (100) GaAs quantum well. Topologically this system is equivalent to a normal Hall bar even though there is an extra set of edges in the center. This configuration allows us to probe the Hall potential distribution in relation to the formation of edge channels. The Quantum Hall measurements at 30 mK show a standard behavior of the outer edges. At each Hall plateau the inner edge becomes an equipotential and the Hall voltage between the inner and outer edges exhibits a drastic asymmetry for the upper and lower arms of the sample. At various integer fillings, depending on the chirality, the voltage drop across one of the arms measures 0 while the drop across the other one is equal to the Hall voltage. This behavior will be explained in terms of the dynamical process of forming the edge channels which also will account for the more irregular behavior of the Hall potential in more disordered systems. NSF DMR-1410302.

  2. Quantum Hall Electron Nematics (United States)

    MacDonald, Allan

    In 2D electron systems hosted by crystals with hexagonal symmetry, electron nematic phases with spontaneously broken C3 symmetry are expected to occur in the quantum Hall regime when triplets of Landau levels associated with three different Fermi surface pockets are partially filled. The broken symmetry state is driven by intravalley Coulombic exchange interactions that favor spontaneously polarized valley occupations. I will discuss three different examples of 2D electron systems in which this type of broken symmetry state is expected to occur: i) the SnTe (111) surface, ii) the Bi (111) surface. and iii) unbalanced bilayer graphene. This type of quantum Hall electron nematic state has so far been confirmed only in the Bi (111) case, in which the anisotropic quasiparticle wavefunctions of the broken symmetry state were directly imaged. In the SnTe case the nematic state phase boundary is controlled by a competition between intravalley Coulomb interactions and intervalley scattering processes that increase in relative strength with magnetic field. An in-plane Zeeman field alters the phase diagram by lifting the three-fold Landau level degeneracy, yielding a ground state energy with 2 π/3 periodicity as a function of Zeeman-field orientation angle. I will comment on the possibility of observing similar states in the absence of a magnetic field. Supported by DOE Division of Materials Sciences and Engineering Grant DE-FG03-02ER45958.

  3. The ISOLDE hall

    CERN Multimedia

    Maximilien Brice


    Since 1992, after its move from the 600 MeV SC, ISOLDE is a customer of the Booster (then 1 GeV, now 1.4 GeV). The intense Booster beam (some 3E13 protons per pulse) is directed onto a target, from which a mixture of isotopes emanates. After ionization and electrostatic acceleration to 60 keV, they enter one of the 2 spectrometers (General Purpose Separator: GPS, and High Resolution Separator: HRS) from which the selected ions are directed to the experiments. The photos show: the REX-ISOLDE post accelerator; the mini-ball experiment; an overview of the ISOLDE hall. In the picture (_12) of the hall, the separators are behind the wall. From either of them, beams can be directed into any of the many beamlines towards the experiments, some of which are visible in the foreground. The elevated cubicle at the left is EBIS (Electron Beam Ion Source), which acts as a charge-state multiplier for the REX facility. The ions are further mass analzyzed and passed on to the linac which accelerates them to higher energies. T...

  4. Cosmopolitanism - Conversation with Stuart Hall


    Hall, Stuart


    Forty minute conversation between Stuart Hall and Pnina Werbner, filmed and edited by Haim Bresheeth. Synopsis by Sarah Harrison. Conversation between Stuart Hall and Pnina Werbner on the theme of Cosmopolitanism (to be shown at the Association of Social Anthropologists Silver Jubilee conference in 2006), in March 2006

  5. Farm Hall: The Play (United States)

    Cassidy, David C.


    It's July 1945. Germany is in defeat and the atomic bombs are on their way to Japan. Under the direction of Samuel Goudsmit, the Allies are holding some of the top German nuclear scientists-among them Heisenberg, Hahn, and Gerlach-captive in Farm Hall, an English country manor near Cambridge, England. As secret microphones record their conversations, the scientists are unaware of why they are being held or for how long. Thinking themselves far ahead of the Allies, how will they react to the news of the atomic bombs? How will these famous scientists explain to themselves and to the world their failure to achieve even a chain reaction? How will they come to terms with the horror of the Third Reich, their work for such a regime, and their behavior during that period? This one-act play is based upon the transcripts of their conversations as well as the author's historical work on the subject.

  6. Hall Effect Gyrators and Circulators

    Directory of Open Access Journals (Sweden)

    Giovanni Viola


    Full Text Available The electronic circulator and its close relative the gyrator are invaluable tools for noise management and signal routing in the current generation of low-temperature microwave systems for the implementation of new quantum technologies. The current implementation of these devices using the Faraday effect is satisfactory but requires a bulky structure whose physical dimension is close to the microwave wavelength employed. The Hall effect is an alternative nonreciprocal effect that can also be used to produce desired device functionality. We review earlier efforts to use an Ohmically contacted four-terminal Hall bar, explaining why this approach leads to unacceptably high device loss. We find that capacitive coupling to such a Hall conductor has much greater promise for achieving good circulator and gyrator functionality. We formulate a classical Ohm-Hall analysis for calculating the properties of such a device, and show how this classical theory simplifies remarkably in the limiting case of the Hall angle approaching 90°. In this limit, we find that either a four-terminal or a three-terminal capacitive device can give excellent circulator behavior, with device dimensions far smaller than the ac wavelength. An experiment is proposed to achieve GHz-band gyration in millimeter (and smaller scale structures employing either semiconductor heterostructure or graphene Hall conductors. An inductively coupled scheme for realizing a Hall gyrator is also analyzed.

  7. Topological Hall and spin Hall effects in disordered skyrmionic textures

    KAUST Repository

    Ndiaye, Papa Birame


    We carry out a thorough study of the topological Hall and topological spin Hall effects in disordered skyrmionic systems: the dimensionless (spin) Hall angles are evaluated across the energy-band structure in the multiprobe Landauer-Büttiker formalism and their link to the effective magnetic field emerging from the real-space topology of the spin texture is highlighted. We discuss these results for an optimal skyrmion size and for various sizes of the sample and find that the adiabatic approximation still holds for large skyrmions as well as for nanoskyrmions. Finally, we test the robustness of the topological signals against disorder strength and show that the topological Hall effect is highly sensitive to momentum scattering.

  8. Topological Hall and Spin Hall Effects in Disordered Skyrmionic Textures (United States)

    Ndiaye, Papa Birame; Akosa, Collins; Manchon, Aurelien; Spintronics Theory Group Team

    We carry out a throughout study of the topological Hall and topological spin Hall effects in disordered skyrmionic systems: the dimensionless (spin) Hall angles are evaluated across the energy band structure in the multiprobe Landauer-Büttiker formalism and their link to the effective magnetic field emerging from the real space topology of the spin texture is highlighted. We discuss these results for an optimal skyrmion size and for various sizes of the sample and found that the adiabatic approximation still holds for large skyrmions as well as for few atomic size-nanoskyrmions. Finally, we test the robustness of the topological signals against disorder strength and show that topological Hall effect is highly sensitive to momentum scattering. This work was supported by the King Abdullah University of Science and Technology (KAUST) through the Award No OSR-CRG URF/1/1693-01 from the Office of Sponsored Research (OSR).

  9. Planar Hall effect bridge magnetic field sensors

    DEFF Research Database (Denmark)

    Henriksen, A.D.; Dalslet, Bjarke Thomas; Skieller, D.H.


    Until now, the planar Hall effect has been studied in samples with cross-shaped Hall geometry. We demonstrate theoretically and experimentally that the planar Hall effect can be observed for an exchange-biased ferromagnetic material in a Wheatstone bridge topology and that the sensor signal can...... Hall effect bridge sensors....

  10. "Hall mees" Linnateatris / Triin Sinissaar

    Index Scriptorium Estoniae

    Sinissaar, Triin


    Tallinn Linnateatri ja Raadioteatri ühislavastus "Hall mees" Gill Adamsi näidendi järgi, lavastaja Eero Spriit, osades Helene Vannari ja Väino Laes, kunstnik Kustav - Agu Püüman. Esietendus 22. okt

  11. Herstructurering Stageprocessen Van Hall Larenstein

    NARCIS (Netherlands)

    Schelvis-Smit, A.A.M.


    Verslag van de herstructurering van het stageproces bij het Onderwijsbureau van Hogelschool VanHall Larenstein. Uitgangspunt hierbij was het onderling uitwisselbaar worden van personeel bij het uitvoeren van werkzaamheden met betrekking tot stages.

  12. Shared Magnetics Hall Thruster Project (United States)

    National Aeronautics and Space Administration — In the proposed Phase II program, Busek Co. will demonstrate an innovative methodology for clustering Hall thrusters into a high performance, very high power...

  13. A game generalizing Hall's theorem


    Rabern, Landon


    We characterize the initial positions from which the first player has a winning strategy in a certain two-player game. This provides a generalization of Hall's theorem. Vizing's edge coloring theorem follows from a special case.

  14. Shared Magnetics Hall Thruster Project (United States)

    National Aeronautics and Space Administration — In the proposed Phase I program, Busek Co. will demonstrate an innovative methodology for clustering Hall thrusters into a high performance, very high power...

  15. Sheldon-Hall syndrome

    Directory of Open Access Journals (Sweden)

    Bamshad Michael J


    Full Text Available Abstract Sheldon-Hall syndrome (SHS is a rare multiple congenital contracture syndrome characterized by contractures of the distal joints of the limbs, triangular face, downslanting palpebral fissures, small mouth, and high arched palate. Epidemiological data for the prevalence of SHS are not available, but less than 100 cases have been reported in the literature. Other common clinical features of SHS include prominent nasolabial folds, high arched palate, attached earlobes, mild cervical webbing, short stature, severe camptodactyly, ulnar deviation, and vertical talus and/or talipes equinovarus. Typically, the contractures are most severe at birth and non-progressive. SHS is inherited in an autosomal dominant pattern but about half the cases are sporadic. Mutations in either MYH3, TNNI2, or TNNT3 have been found in about 50% of cases. These genes encode proteins of the contractile apparatus of fast twitch skeletal muscle fibers. The diagnosis of SHS is based on clinical criteria. Mutation analysis is useful to distinguish SHS from arthrogryposis syndromes with similar features (e.g. distal arthrogryposis 1 and Freeman-Sheldon syndrome. Prenatal diagnosis by ultrasonography is feasible at 18–24 weeks of gestation. If the family history is positive and the mutation is known in the family, prenatal molecular genetic diagnosis is possible. There is no specific therapy for SHS. However, patients benefit from early intervention with occupational and physical therapy, serial casting, and/or surgery. Life expectancy and cognitive abilities are normal.

  16. Transport Signatures of the Hall Viscosity. (United States)

    Delacrétaz, Luca V; Gromov, Andrey


    Hall viscosity is a nondissipative response function describing momentum transport in two-dimensional systems with broken parity. It is quantized in the quantum Hall regime, and contains information about the topological order of the quantum Hall state. Hall viscosity can distinguish different quantum Hall states with identical Hall conductances, but different topological order. To date, an experimentally accessible signature of Hall viscosity is lacking. We exploit the fact that Hall viscosity contributes to charge transport at finite wavelengths, and can therefore be extracted from nonlocal resistance measurements in inhomogeneous charge flows. We explain how to determine the Hall viscosity from such a transport experiment. In particular, we show that the profile of the electrochemical potential close to contacts where current is injected is sensitive to the value of the Hall viscosity.

  17. General footage ISOLDE experimental hall HD

    CERN Multimedia


    Overview of the ISOLDE experimental hall. Equipment and experiments. Taken from the WITCH / EBIS platform: ISOLDE hall infrastructure, GHM line, LA1, LA2, LA0, central beamline, COLLAPS experiment, CRIS experiment, ISOLTRAP experiment, laser guidance from building 508 into the hall for laser spectroscopy COLLAPS and CRIS. Taken from the HIE ISOLDE shielding tunnel roof: ISOLDE hall infrastructure, WITCH experiment, VITO line, TAS experiment. General footage: High Tension room entrance and EBIS platform, staircases and passages in the experimental hall.

  18. Iodine Hall Thruster (United States)

    Szabo, James


    Iodine enables dramatic mass and cost savings for lunar and Mars cargo missions, including Earth escape and near-Earth space maneuvers. The demonstrated throttling ability of iodine is important for a singular thruster that might be called upon to propel a spacecraft from Earth to Mars or Venus. The ability to throttle efficiently is even more important for missions beyond Mars. In the Phase I project, Busek Company, Inc., tested an existing Hall thruster, the BHT-8000, on iodine propellant. The thruster was fed by a high-flow iodine feed system and supported by an existing Busek hollow cathode flowing xenon gas. The Phase I propellant feed system was evolved from a previously demonstrated laboratory feed system. Throttling of the thruster between 2 and 11 kW at 200 to 600 V was demonstrated. Testing showed that the efficiency of iodine fueled BHT-8000 is the same as with xenon, with iodine delivering a slightly higher thrust-to-power (T/P) ratio. In Phase II, a complete iodine-fueled system was developed, including the thruster, hollow cathode, and iodine propellant feed system. The nominal power of the Phase II system is 8 kW; however, it can be deeply throttled as well as clustered to much higher power levels. The technology also can be scaled to greater than 100 kW per thruster to support megawatt-class missions. The target thruster efficiency for the full-scale system is 65 percent at high specific impulse (Isp) (approximately 3,000 s) and 60 percent at high thrust (Isp approximately 2,000 s).

  19. Ventilation systems for high halls

    Energy Technology Data Exchange (ETDEWEB)

    Sodec, F.; Veldboer, W.


    A ventilation system for high halls is described which meets the demands of steady air flow in spite of inverse thermal currents, intensive ventilation of working areas during heating and cooling and ventilation free of draught. The main element of the ventilation system is the air outlet in the ceiling, with variable beam direction. The horizontal, rotated beams are superimposed by a vertical beam whose strength may be varied. This way, the beam direction can be adapted to the thermal load of the hall and the height of blowout. The blowout angle is large for heating and small for cooling. Studies have shown that halls are ventilated thoroughly and free of draught by this system. The variable, rotary outlet presented in the article is best suited for heights of 4.00 to 12.00 m. The outlet, with a rated diameter of 400 mm, has been in use for two years now in fields as varied as diecasting works, halls at fairs, sports halls, etc. The air volume flow rate is 1000 to 3000 m/sup 3//h per outlet. A bigger version is now being developed; it will have a rated diameter of 710 mm and an air volume flow rate of 3000 to 9000 m/sup 3//h.

  20. Novel concepts in Hall sensors (United States)

    Mani, R. G.


    Hall effect devices are widely used as position sensors and contactless switches in applications ranging from electric motors to soft drink machines and automobiles. Such devices typically operate in an adverse environment where offset voltages originating from various physical effects limit the effective sensitivity of the sensor to the weak magnetic field (B device that automatically reduces such spurious offsets is desirable because improved 'signal to offset' would relax manufacturing tolerances and other constraints within the sensor system. Here, we examine some techniques and sensor configurations (R. G. Mani, K. von Klitzing, F. Jost, K. Marx, S. Lindenkreuz, and H. P. Trah, Appl. Phys. Lett. 67, 2223, 1995.) based on the so called 'anti Hall bar' geometry that promise the possibility of a Silicon based Hall sensor with a field equivalent offset well below 1 mT.

  1. Optical detection of spin Hall effect in metals (United States)

    van T Erve, Olaf; Hanbicki, Aubrey; Li, Connie; Jonker, Berend

    Spin Hall effects in metals have been successfully measured using electrical methods such as nonlocal spin valve transport, ferromagnetic resonance or spin torque transfer experiments. These methods require complex processing techniques and measuring setups. Here we present room temperature measurements of the spin Hall effect in non-magnetic metals such as Pt and β-W using a standard bench top magneto-optic Kerr effect (MOKE) system. With this system, one can readily determine the angular dependence of the induced polarization on the bias current direction. When a bias current is applied, the spin Hall effect causes electrons of opposite spin to be scattered in opposite directions, resulting in a spin accumulation at the surface of the film. The MOKE signal tracks the applied square wave bias current with an amplitude and phase directly related to the spin Hall angle. Using this technique, we show that the spin-Hall angle of β-W is opposite in sign and significantly larger than that of Pt. In addition, we use this technique to detect spin diffusion from β-W into Al thin films, as well as spin diffusion from the topological surface states of Bi2Se3 into Al. We will also show direct modulation of the reflected light up to 100 kHz, using Bi doped Cu samples. This work was supported by internal programs at NRL.

  2. ATLAS Assembly Hall Open Day

    CERN Multimedia

    Patrice Loiez


    To mark the 50th Anniversary of the founding of CERN, a day of tours, displays and presentations was held in October 2004. The assembly halls for the experiments that were waiting to be installed on the LHC, such as ATLAS shown here, were transformed into display areas and cafés.

  3. City Hall and Territorial Development

    Directory of Open Access Journals (Sweden)

    Carlos Borrás Querol


    Full Text Available The current economic conditions impose a new role upon the local administration, a new one added to its traditional role as administrators of public services and managers of the local territory. City Halls are increasingly widening their action area to include spheres of interest that were previously not dealt with: fundamentally – jobs promotion and encouraging economic development. With respect to this, the article describes the important experience of the City Hall of Alcalá la Real (Jaén, whose trajectory of enacting strategies for local development are alternatives to the model of speculative development, strategies whose objective is to direct the potential for local community development by matching the interests of the citizens and the system of productivity in a balanced and sustainable manner, thereby contributing not only to the creation of new businesses and favoring the creation of jobs, but the advancement of territorial balance and social cohesion.

  4. Hall Sensors for Extreme Temperatures

    Directory of Open Access Journals (Sweden)

    Maciej Oszwaldowski


    Full Text Available We report on the preparation of the first complete extreme temperature Hall sensor. This means that the extreme-temperature magnetic sensitive semiconductor structure is built-in an extreme-temperature package especially designed for that purpose. The working temperature range of the sensor extends from −270 °C to +300 °C. The extreme-temperature Hall-sensor active element is a heavily n-doped InSb layer epitaxially grown on GaAs. The magnetic sensitivity of the sensor is ca. 100 mV/T and its temperature coefficient is less than 0.04 %/K. This sensor may find applications in the car, aircraft, spacecraft, military and oil and gas industries.

  5. Symmetric functions and Hall polynomials

    CERN Document Server

    MacDonald, Ian Grant


    This reissued classic text is the acclaimed second edition of Professor Ian Macdonald's groundbreaking monograph on symmetric functions and Hall polynomials. The first edition was published in 1979, before being significantly expanded into the present edition in 1995. This text is widely regarded as the best source of information on Hall polynomials and what have come to be known as Macdonald polynomials, central to a number of key developments in mathematics and mathematical physics in the 21st century Macdonald polynomials gave rise to the subject of double affine Hecke algebras (or Cherednik algebras) important in representation theory. String theorists use Macdonald polynomials to attack the so-called AGT conjectures. Macdonald polynomials have been recently used to construct knot invariants. They are also a central tool for a theory of integrable stochastic models that have found a number of applications in probability, such as random matrices, directed polymers in random media, driven lattice gases, and...

  6. Photovoltaic Hall effect in graphene (United States)

    Oka, Takashi; Aoki, Hideo


    Response of electronic systems in intense lights (ac electric fields) to dc source-drain fields is formulated with the Floquet method. We have then applied the formalism to graphene, for which we show that a nonlinear effect of a circularly polarized light can open a gap in the Dirac cone, which is predicted to lead to a photoinduced dc Hall current. This is numerically confirmed for a graphene ribbon attached to electrodes with the Keldysh Green’s function.

  7. Library rooms or Library halls


    Alfredo Serrai


    Library Halls, understood as Renaissance and Baroque architectural creations, along with the furnishings and decorations, accomplish a cognitive task and serve to transmit knowledge. The design of these spaces based on the idea that they should reflect the merits and content of the collections housed within them, in order to prepare the mind of the reader to respect and admire the volumes. In accordance with this principle, in the fifteenth century library rooms had a basilican shape, with tw...

  8. Spin Hall effect by surface roughness

    KAUST Repository

    Zhou, Lingjun


    The spin Hall and its inverse effects, driven by the spin orbit interaction, provide an interconversion mechanism between spin and charge currents. Since the spin Hall effect generates and manipulates spin current electrically, to achieve a large effect is becoming an important topic in both academia and industries. So far, materials with heavy elements carrying a strong spin orbit interaction, provide the only option. We propose here a new mechanism, using the surface roughness in ultrathin films, to enhance the spin Hall effect without heavy elements. Our analysis based on Cu and Al thin films suggests that surface roughness is capable of driving a spin Hall angle that is comparable to that in bulk Au. We also demonstrate that the spin Hall effect induced by surface roughness subscribes only to the side-jump contribution but not the skew scattering. The paradigm proposed in this paper provides the second, not if only, alternative to generate a sizable spin Hall effect.

  9. Observation of the Zero Hall Plateau in a Quantum Anomalous Hall Insulator

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Yang; Feng, Xiao; Ou, Yunbo; Wang, Jing; Liu, Chang; Zhang, Liguo; Zhao, Dongyang; Jiang, Gaoyuan; Zhang, Shou-Cheng; He, Ke; Ma, Xucun; Xue, Qi-Kun; Wang, Yayu


    We report experimental investigations on the quantum phase transition between the two opposite Hall plateaus of a quantum anomalous Hall insulator. We observe a well-defined plateau with zero Hall conductivity over a range of magnetic field around coercivity when the magnetization reverses. The features of the zero Hall plateau are shown to be closely related to that of the quantum anomalous Hall effect, but its temperature evolution exhibits a significant difference from the network model for a conventional quantum Hall plateau transition. We propose that the chiral edge states residing at the magnetic domain boundaries, which are unique to a quantum anomalous Hall insulator, are responsible for the novel features of the zero Hall plateau.

  10. Anomalous Hall effect in polycrystalline Ni films

    KAUST Repository

    Guo, Zaibing


    We systematically studied the anomalous Hall effect in a series of polycrystalline Ni films with thickness ranging from 4 to 200 nm. It is found that both the longitudinal and anomalous Hall resistivity increased greatly as film thickness decreased. This enhancement should be related to the surface scattering. In the ultrathin films (46 nm thick), weak localization corrections to anomalous Hall conductivity were studied. The granular model, taking into account the dominated intergranular tunneling, has been employed to explain this phenomenon, which can explain the weak dependence of anomalous Hall resistivity on longitudinal resistivity as well. © 2011 Elsevier Ltd. All rights reserved.

  11. Library rooms or Library halls

    Directory of Open Access Journals (Sweden)

    Alfredo Serrai


    Full Text Available Library Halls, understood as Renaissance and Baroque architectural creations, along with the furnishings and decorations, accomplish a cognitive task and serve to transmit knowledge. The design of these spaces based on the idea that they should reflect the merits and content of the collections housed within them, in order to prepare the mind of the reader to respect and admire the volumes. In accordance with this principle, in the fifteenth century library rooms had a basilican shape, with two or three naves, like churches, reflecting thus the spiritual value of the books contained there. Next to that inspiring function, library rooms had also the task of representing the entire logical and conceptual universe of human knowledge in a figurative way, including for this purpose also the and Kunst- und Wunderkammern, namely the collections of natural, artficial objects, and works of art. The importance of library rooms and their function was understood already in the early decades of the seventeenth century, as underlined in the treatise, Musei sive Bibliothecae tam privatae quam publicae Extructio, Instructio, Cura, Usus, written by the Jesuit Claude Clément and published in 1635. Almost the entire volume is dedicated to the decoration and ornamentation of the Saloni, and the function of the library is identified exclusively with the preservation and decoration of the collection, neglecting more specifically bibliographic aspects or those connected to library science. The architectural structure of the Saloni was destined to change in relation to two factors, namely the form of books, and the sources of light. As a consequence, from the end of the sixteenth century – or perhaps even before if one considers the fragments of the Library of Urbino belonging to Federico da Montefeltro – shelves and cabinets have been placed no longer in the center of the room, but were set against the walls. This new disposition of the furniture, surmounted by

  12. The Duesseldorf fairground. New building of hall 6; Messe Duesseldorf. Neubau der Halle 6

    Energy Technology Data Exchange (ETDEWEB)

    Gampfer, W.; Wendt, W.; Paar, A.; Schwarz, A.; Klemp, P.; Ambaum, P.; Joppen, H.; Hesse, D.; Hauser, K. [Messe Duesseldorf GmbH (Germany)


    The Duesseldorf fairground is highly successful and is constantly growing. With the inauguration of the new Hall 6 in May 2000, the former twelve halls have now become 17. The new Hall 6 will also be used for sports events, concerts, meetings etc. [German] Der Erfolg der Messe Duesseldorf laesst sich am stetigen Wachstum der Ausstellungsbereiche ablesen. So wurden aus den ehemals zwoelf Hallen bis heute mit der Einweihung der Neuen Halle 6 im Mai 2000 17 Hallen. Die zuletzt hinzugekommene Halle 6 wird neben der ueberwiegenden Nutzung als Messehalle auch als tagesbelichtete Mehrzweckhalle fuer Veranstaltungen, wie z.B. Sportveranstaltungen, Grosskonzerte, Versammlungen etc., genutzt. (orig.)

  13. Quasiclassical theory of the vortex state in unconventional systems. Study of magnesium diboride and d-wave superconductors; Quasiklassische Theorie des Vortexzustandes in unkonventionellen Systemen. Betrachtung zu Magnesiumdiborid und d-Wellen-Supraleitern

    Energy Technology Data Exchange (ETDEWEB)

    Graser, S.


    The two-band superconductor magnesium diboride as well as the high temperature cuprates belong to the class of type-II superconductors. In these systems between an upper and a lower critical magnetic field one can only find an incomplete Meissner effect und magnetic flux penetrates the superconductor in form of quantized flux tubes, so-called vortices. This work is devoted to the vortex state in magnesium diboride and the interplay of vortices and boundaries in d-wave superconductors. First of all analytical results for the quasiparticle density of states in high magnetic fields are obtained within the framework of the quasiclassical theory. Especially the influence of the Fermi surface topology on the spatially averaged quasiparticle density of states is discussed in detail. Furthermore selfconsistent numerical calculations of the pairing potential around an isolated vortex - a model of the vortex state in the vicinity of the lower critical field - are performed. In this context the unusual shrinkage of the vortex core with decreasing temperature, visible only in very clean superconductors and known as the Kramer-Pesch-effect, is examined for a two-band system. The last chapter is concerned with the influence of the flow-field of an isolated phase vortex on the Andreev bound states at the surface of a d-wave superconductor. The local suppression of the Andreev bound states in a shadow-like region between vortex and boundary is the main result and consequences of this ''vortexshadow-effect'' are discussed. (orig.)

  14. Mesoscopic effects in the quantum Hall regime

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 58; Issue 2 ... Mesoscopic effects; quantum Hall transitions; finite-size scaling. ... When band mixing between multiple Landau levels is present, mesoscopic effects cause a crossover from a sequence of quantum Hall transitions for weak disorder to classical behavior ...

  15. Kelvin's Canonical Circulation Theorem in Hall Magnetohydrodynamics

    CERN Document Server

    Shivamoggi, B K


    The purpose of this paper is to show that, thanks to the restoration of the legitimate connection between the current density and the plasma flow velocity in Hall magnetohydrodynamics (MHD), Kelvin's Circulation Theorem becomes valid in Hall MHD. The ion-flow velocity in the usual circulation integral is now replaced by the canonical ion-flow velocity.

  16. Mesoscopic effects in the quantum Hall regime

    Indian Academy of Sciences (India)

    may be of relevance to experimentally observed transitions between quantum Hall states and the insulating phase ... In this paper, we discuss the mesoscopic effects in the quantum Hall regime, in particu- lar the effects of ...... finite sizes, due to the presence of long length scales, quantum interference effects can be cut-off at ...

  17. Novel optical probe for quantum Hall system

    Indian Academy of Sciences (India)

    Surface photovoltage spectroscopy; quantum Hall effect; Landau levels; edge states. Abstract. Surface photovoltage (SPV) spectroscopy has been used for the first time to explore Landau levels of a two-dimensional electron gas (2DEG) in modulation doped InP/InGaAs/InP QW in the quantum Hall regime. The technique ...

  18. Hall devices improve electric motor efficiency (United States)

    Haeussermann, W.


    Efficiency of electric motors and generators is reduced by radial magnetic forces created by symmetric fields within device. Forces are sensed and counteracted by Hall devices on excitation or control windings. Hall generators directly measure and provide compensating control of anu asymmetry, eliminating additional measurements needed for calibration feedback control loop.

  19. The quantum Hall impedance standard (United States)

    Schurr, J.; Kučera, J.; Pierz, K.; Kibble, B. P.


    Alternating current measurements of double-shielded quantum Hall devices have revealed a fascinating property of which only a quantum effect is capable: it can detect its own frequency dependence and convert it to a current dependence which can be used to eliminate both of them. According to an experimentally verified model, the residual frequency dependence is smaller than the measuring uncertainty of 1.3 × 10-9 kHz-1. In this way, a highly precise quantum standard of impedance can be established, without having to correct for any calculated frequency dependence and without the need for any artefact with a calculated frequency dependence. Nothing else like that is known to us and we hope that our results encourage other national metrology institutes to also apply it to impedance metrology and further explore its beautiful properties.

  20. The quantum Hall effects: Philosophical approach (United States)

    Lederer, P.


    The Quantum Hall Effects offer a rich variety of theoretical and experimental advances. They provide interesting insights on such topics as gauge invariance, strong interactions in Condensed Matter physics, emergence of new paradigms. This paper focuses on some related philosophical questions. Various brands of positivism or agnosticism are confronted with the physics of the Quantum Hall Effects. Hacking's views on Scientific Realism, Chalmers' on Non-Figurative Realism are discussed. It is argued that the difficulties with those versions of realism may be resolved within a dialectical materialist approach. The latter is argued to provide a rational approach to the phenomena, theory and ontology of the Quantum Hall Effects.

  1. Bound values for Hall conductivity of heterogeneous medium under ...

    Indian Academy of Sciences (India)

    Bound values for Hall conductivity under quantum Hall effect (QHE) conditions in inhomogeneous medium has been studied. It is shown that bound values for Hall conductivity differ from bound values for metallic conductivity. This is due to the unusual character of current percolation under quantum Hall effect conditions.

  2. Iodine Hall Thruster for Space Exploration Project (United States)

    National Aeronautics and Space Administration — Busek Co. Inc. proposes to develop a high power (high thrust) electric propulsion system featuring an iodine fueled Hall Effect Thruster (HET). The system to be...

  3. Iodine Hall Thruster for Space Exploration Project (United States)

    National Aeronautics and Space Administration — In the Phase I program, Busek Co. Inc. tested an existing Hall thruster, the BHT-8000, on iodine propellant. The thruster was fed by a high flow iodine feed system,...

  4. AA under construction in its hall

    CERN Multimedia

    CERN PhotoLab


    The Antiproton Accumulator was installed in a specially built hall. Here we see it at an "early" stage of installation, just a few magnets on the floor, no vacuum chamber at all, but: 3 months later there was circulating beam !

  5. Success of Hall technique crowns questioned. (United States)

    Nainar, S M Hashim


    Hall technique is a method of providing stainless steel crowns for primary molars without tooth preparation and requires no local anesthesia. Literature review showed inconclusive evidence and therefore this technique should not be used in clinical practice.

  6. Dual Mode Low Power Hall Thruster Project (United States)

    National Aeronautics and Space Administration — Sample and return missions desire and missions like Saturn Observer require a low power Hall thruster that can operate at high thrust to power as well as high...

  7. Light Metal Propellant Hall Thruster Project (United States)

    National Aeronautics and Space Administration — Busek proposes to develop light metal Hall Effect thrusters that will help reduce the travel time, mass, and cost of SMD spacecraft. Busek has identified three...

  8. Two LHC dipole magnets in assembly hall

    CERN Multimedia

    Maximilien Brice


    The final LHC components are completed in the assembly hall, prior to installation in the tunnel. These pictures show two 15-m long LHC cryogenic magnets, both before and after insertion into their blue vacuum vessel.

  9. Giant thermal Hall effect in multiferroics (United States)

    Ideue, T.; Kurumaji, T.; Ishiwata, S.; Tokura, Y.


    Multiferroics, in which dielectric and magnetic orders coexist and couple with each other, attract renewed interest for their cross-correlated phenomena, offering a fundamental platform for novel functionalities. Elementary excitations in such systems are strongly affected by the lattice-spin interaction, as exemplified by the electromagnons and the magneto-thermal transport. Here we report an unprecedented coupling between magnetism and phonons in multiferroics, namely, the giant thermal Hall effect. The thermal transport of insulating polar magnets (ZnxFe1-x)2Mo3O8 is dominated by phonons, yet extremely sensitive to the magnetic structure. In particular, large thermal Hall conductivities are observed in the ferrimagnetic phase, indicating unconventional lattice-spin interactions and a new mechanism for the Hall effect in insulators. Our results show that the thermal Hall effect in multiferroic materials can be an effective probe for strong lattice-spin interactions and provide a new tool for magnetic control of thermal currents.

  10. NAS Decadal Review Town Hall (United States)

    The National Academies of Sciences, Engineering and Medicine is seeking community input for a study on the future of materials research (MR). Frontiers of Materials Research: A Decadal Survey will look at defining the frontiers of materials research ranging from traditional materials science and engineering to condensed matter physics. Please join members of the study committee for a town hall to discuss future directions for materials research in the United States in the context of worldwide efforts. In particular, input on the following topics will be of great value: progress, achievements, and principal changes in the R&D landscape over the past decade; identification of key MR areas that have major scientific gaps or offer promising investment opportunities from 2020-2030; and the challenges that MR may face over the next decade and how those challenges might be addressed. This study was requested by the Department of Energy and the National Science Foundation. The National Academies will issue a report in 2018 that will offer guidance to federal agencies that support materials research, science policymakers, and researchers in materials research and other adjoining fields. Learn more about the study at

  11. The fluctuation Hall conductivity and the Hall angle in type-II superconductor under magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Tinh, Bui Duc, E-mail: [Institute of Research and Development, Duy Tan University, K7/25 Quang Trung, Danang (Viet Nam); Department of Physics, Hanoi National University of Education, 136 Xuan Thuy, Cau Giay, Hanoi (Viet Nam); Hoc, Nguyen Quang; Thu, Le Minh [Department of Physics, Hanoi National University of Education, 136 Xuan Thuy, Cau Giay, Hanoi (Viet Nam)


    Highlights: • The time-dependent Ginzburg–Landau was used to calculate fluctuation Hall conductivity and Hall angle in type-II superconductor in 2D and 3D. • We obtain analytical expressions for the fluctuation Hall conductivity and the Hall angle summing all Landau levels without need to cutoff higher Landau levels to treat arbitrary magnetic field. • The results were compared to the experimental data on YBCO. - Abstract: The fluctuation Hall conductivity and the Hall angle, describing the Hall effect, are calculated for arbitrary value of the imaginary part of the relaxation time in the frame of the time-dependent Ginzburg–Landau theory in type II-superconductor with thermal noise describing strong thermal fluctuations. The self-consistent Gaussian approximation is used to treat the nonlinear interaction term in dynamics. We obtain analytical expressions for the fluctuation Hall conductivity and the Hall angle summing all Landau levels without need to cutoff higher Landau levels to treat arbitrary magnetic field. The results are compared with experimental data on high-T{sub c} superconductor.

  12. Generic Superweak Chaos Induced by Hall Effect


    Ben-Harush, Moti; Dana, Itzhack


    We introduce and study the "kicked Hall system" (KHS), i.e., charged particles periodically kicked in the presence of uniform magnetic ($\\mathbf{B}$) and electric ($\\mathbf{E}$) fields that are perpendicular to each other and to the kicking direction. We show that for resonant values of $B$ and $E$ and in the weak-chaos regime of sufficiently small nonintegrability parameter $\\kappa$ (the kicking strength), there exists a \\emph{generic} family of periodic kicking potentials for which the Hall...

  13. Turbulence Measurements in a Tropical Zoo Hall (United States)

    Eugster, Werner; Denzler, Basil; Bogdal, Christian


    The Masoala rainforest hall of the Zurich Zoo, Switzerland, covers a ground surface area of 10,856 m2 and reaches 30 m in height. With its transparent ETFE foiled roof it provides a tropical climate for a large diversity of plants and animals. In combination with an effort to estimate dry deposition of elemental mercury, we made an attempt to measure turbulent transfer velocity with an ultrasonic anemometer inside the hall. Not surprising, the largest turbulence elements were on the order of the hall dimension. Although the dimensions of the hall seem to be small (200,000 m3) for eddy covariance flux measurements and the air circulation inside the hall was extremely weak, the spectra of wind velocity components and virtual (sonic) temperature obeyed the general statistical description expected under unconstrained outdoor measurement conditions. We will present results from a two-week measurement campaign in the Masoala rainforest hall and make a suggestion for the deposition velocity to be used to estimate dry deposition of atmospheric components to the tropical vegetation surface.

  14. Air temperature gradient in large industrial hall (United States)

    Karpuk, Michał; Pełech, Aleksander; Przydróżny, Edward; Walaszczyk, Juliusz; Szczęśniak, Sylwia


    In the rooms with dominant sensible heat load, volume airflow depends on many factors incl. pre-established temperature difference between exhaust and supply airflow. As the temperature difference is getting higher, airflow volume drops down, consequently, the cost of AHU is reduced. In high industrial halls with air exhaust grids located under the ceiling additional temperature gradient above working zone should be taken into consideration. In this regard, experimental research of the vertical air temperature gradient in high industrial halls were carried out for the case of mixing ventilation system The paper presents the results of air temperature distribution measurements in high technological hall (mechanically ventilated) under significant sensible heat load conditions. The supply airflow was delivered to the hall with the help of the swirl diffusers while exhaust grids were located under the hall ceiling. Basing on the air temperature distribution measurements performed on the seven pre-established levels, air temperature gradient in the area between 2.0 and 7.0 m above the floor was calculated and analysed.

  15. Complexity

    Indian Academy of Sciences (India)

    Rahul Pandit


    Oct 31, 2008 ... ”The more complex a thing is, the more you can talk about it.” - attributed to Giorgio Parisi. ▻ ”C'est magnifique, mais ce n'est pas de la science.” (It is magnificent, but not all of it is science.) - attributed ... Earliest examples: theoretical computer science, algorithmic complexity, etc. ▻ Rapid progress after the ...

  16. Acoustics in rock and pop music halls

    DEFF Research Database (Denmark)

    Adelman-Larsen, Niels Werner; Thompson, Eric Robert; Gade, Anders Christian


    The existing body of literature regarding the acoustic design of concert halls has focused almost exclusively on classical music, although there are many more performances of rhythmic music, including rock and pop. Objective measurements were made of the acoustics of twenty rock music venues...... in Denmark and a questionnaire was used in a subjective assessment of those venues with professional rock musicians and sound engineers. Correlations between the objective and subjective results lead, among others, to a recommendation for reverberation time as a function of hall volume. Since the bass...

  17. Prototype dining hall energy efficiency study

    Energy Technology Data Exchange (ETDEWEB)

    Mazzucchi, R.P.; Bailey, S.A.; Zimmerman, P.W.


    The energy consumption of food service facilities is among the highest of any commercial building type, owing to the special requirements for food preparation, sanitation, and ventilation. Consequently, the US Air Force Engineering and Services Center (AFESC) contracted with Pacific Northwest Laboratory (PNL) to collect and analyze end-use energy consumption data for a prototypical dining hall and make specific recommendations on cost-effective energy conservation options. This information will be used to establish or update criteria for dining hall designs and retrofits as appropriate. 6 refs., 21 figs., 23 tabs.


    Directory of Open Access Journals (Sweden)

    Laura Lizondo Sevilla


    Full Text Available RESUMEN El artículo enmarca el edificio del Crown Hall en el contexto docente y arquitectónico de Mies van der Rohe. Revisa sus inicios en la Bauhaus con su primera intervención en un espacio docente para la Bauhaus de Berlín en 1932, así como su marcha a Estados Unidos, los planteamientos arquitectónicos del campus del IIT y el proyecto del Crown Hall. El texto incide en el estudio del proceso proyectual del Crown Hall analizando la evolución de su concepción arquitectónica a través de las diferentes versiones del proyecto. Se constata la transición desde los primeros planteamientos arquitectónicos de los edificios del campus del IIT proyectados por Mies hacia el planteamiento del gran espacio unitario del Crown Hall. Este proyecto se puede entender desde la creciente importancia de la estructura, la claridad constructiva y el manejo del acero y vidrio como únicos materiales de la imagen del edificio y el carácter flexible y unitario del espacio. Finalmente se hace referencia al concepto del "espacio universal" en la arquitectura de Mies, como un concepto abstracto que supera los de flexibilidad de uso o unidad espacial, insinuando, a modo de reflexión, las principales variables que definirían el espacio universal miesiano.SUMMARY The article showcases the Crown Hall building in the educational and architectural context of Mies van der Rohe. It reviews his beginnings in the Bauhaus with his first intervention in an educational space for the Bauhaus of Berlin in 1932, as well as his sojourn to the United States, and the architectural approaches to the IIT campus and the Crown Hall project. The text touches on the study of the planning process for the Crown Hall, analysing the evolution of its architectural conception, through the different versions of the project. The article covers the transition from the first architectural approaches for the IIT campus buildings, planned by Mies, to the approach of the large unitary space of

  19. Dynamics Of Human Motion The Case Study of an Examination Hall (United States)

    Ogunjo, Samuel; Ajayi, Oluwaseyi; Fuwape, Ibiyinka; Dansu, Emmanuel

    Human behaviour is difficult to characterize and generalize due to ITS complex nature. Advances in mathematical models have enabled human systems such as love interaction, alcohol abuse, admission problem to be described using models. This study investigates one of such problems, the dynamics of human motion in an examination hall with limited computer systems such that students write their examination in batches. The examination is characterized by time (t) allocated to each students and difficulty level (dl) associated with the examination. A stochastic model based on the difficulty level of the examination was developed for the prediction of student's motion around the examination hall. A good agreement was obtained between theoretical predictions and numerical simulation. The result obtained will help in better planning of examination session to maximize available resources. Furthermore, results obtained in the research can be extended to other areas such as banking hall, customer service points where available resources will be shared amongst many users.

  20. Automated Micro Hall Effect measurements

    DEFF Research Database (Denmark)

    Petersen, Dirch Hjorth; Henrichsen, Henrik Hartmann; Lin, Rong


    With increasing complexity of processes and variety of materials used for semiconductor devices, stringent control of the electronic properties is becoming ever more relevant. Collinear micro four-point probe (M4PP) based measurement systems have become high-end metrology methods for characteriza...

  1. Quantized Anomalous Hall Effect in Magnetic Topological Insulators

    National Research Council Canada - National Science Library

    Rui Yu; Wei Zhang; Hai-Jun Zhang; Shou-Cheng Zhang; Xi Dai; Zhong Fang


    .... In a quantum anomalous Hall insulator, spontaneous magnetic moments and spin-orbit coupling combine to give rise to a topologically nontrivial electronic structure, leading to the quantized Hall...

  2. Bound values for Hall conductivity of heterogeneous medium under ...

    Indian Academy of Sciences (India)

    - ditions in inhomogeneous medium has been studied. It is shown that bound values for. Hall conductivity differ from bound values for metallic conductivity. This is due to the unusual character of current percolation under quantum Hall effect ...

  3. Topological spin Hall effect resulting from magnetic skyrmions

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Gen; Liu, Yizhou; Barlas, Yafis; Zang, Jiadong; Lake, Roger K.


    The intrinsic spin Hall effect originates from the topology of the Bloch bands in momentum space. The duality between real space and momentum space calls for a spin Hall effect induced from a real space topology in analogy to the topological Hall effect of skyrmions. We theoretically demonstrate the topological spin Hall effect in which a pure transverse spin current is generated from a skyrmion spin texture.

  4. Nonexponential sound decay in concert halls (United States)

    Kanev, N. G.


    The paper presents acoustic measurement results for two concert halls in which nonexponential sound decay is observed. Quantitative estimates are given for how the obtained decay laws differ from exponential. Problems are discussed that arise when using reverberation time to assess the quality of room acoustics with nonexponential sound decay.

  5. Concept of Operating Indoor Skiing Halls with

    DEFF Research Database (Denmark)

    Paul, Joachim


    Indoor skiing halls are conventionally operated at low temperatures and with either crushed ice as snow substitute or snow made from freezing water in cold air. Both systems have a high energy demand for air cooling, floor freezing and consequently snow harvest. At the same time the snow at the top...

  6. View of CMS in the assembly hall

    CERN Multimedia

    Maximilien Brice


    The CMS detector is stored in the assembly hall at Cessy, France. Once the detector has been fully assembled on the surface, it will be lowered into its cathedral-like cavern. A large range of physics will be studied in this experiment, including the possibility of extra dimensions and the search for the Higgs Boson.

  7. Room acoustic properties of concert halls

    DEFF Research Database (Denmark)

    Gade, Anders Christian


    A large database of values of various room acoustic parameters has provided the basis for statistical analyses of how and how much the acoustic properties of concert halls are influenced by their size, shape, and absorption area (as deduced from measured reverberation time). The data have been...

  8. Supersymmetry in the Fractional Quantum Hall Regime

    CERN Document Server

    Sagi, Eran


    Supersymmetry (SUSY) is a symmetry transforming bosons to fermions and vice versa. Indications of its existence have been extensively sought after in high-energy experiments. However, signatures of SUSY have yet to be detected. In this manuscript we propose a condensed matter realization of SUSY on the edge of a Read-Rezayi quantum Hall state, given by filling factors of the form $\

  9. Massive Skyrmions in quantum Hall ferromagnets

    NARCIS (Netherlands)

    Abolfath, M.; Mullen, K.; Stoof, H.T.C.


    We apply the theory of elasticity to study the effects of Skyrmion mass on lattice dynamics in quantum Hall systems. We find that massive Skyrme lattices behave like a Wigner crystal in the presence of a uniform perpendicular magnetic field. We make a comparison with the microscopic Hartree-Fock

  10. Hall Thruster With an External Acceleration Zone

    National Research Council Canada - National Science Library

    Gascon, Nicolas; Corey, Ronald L; Cappelli, Mark A; Hargus, William


    ... of wall material, or magnetic field intensity. When operated with a low background pressure, the particular Hall discharge studied here creates an ion accelerating electrostatic field mainly outside of the channel, in a narrow zone located 5-20 mm away from the exit plane.

  11. Large Spin Hall Angle in Vanadium Film (United States)

    Wang, Tao; Fan, Xin; Wang, Wenrui; Xie, Yunsong; Warsi, Muhammad A.; Wu, Jun; Chen, Yunpeng; Lorenz, Virginia O.; Xiao, John Q.

    We report the large spin Hall angle observed in Vanadium film with small grain size and distorted lattice parameter. The spin Hall angle is quantified by measuring current-induced spin-orbit torque in V/CoFeB bilayer using optical spin torque magnetometer based on polar magneto-optical Kerr effect (MOKE). The spin Hall angle as large as θSH = -0.071 has been observed in V/CoFeB bilayer Structural analysis, using X-ray diffraction (XRD), transmission electron microscopy (TEM) and selected area electron diffraction (SAED), confirms films grown at room temperature have very small grain size and enlarged lattice parameter. The Vanadium films with distorted crystal structure also have high resistivity (>200 μΩ cm) and long spin diffusion length (~16.3 nm) measured via spin pumping experiment. This finding of spin Hall effect enhancement in more disordered structure will provide insights for understanding and exploiting materials with strong spin orbit interaction, especially in light 3d transition metals which promise long spin diffusion length.

  12. Development and applications of mesoscopic hall microprobes

    NARCIS (Netherlands)

    Novoselov, Konstantin S.


    This thesis is devoted to the further development of the local Hall magnetometery technique, and its application for studying ferromagnetic domain wall propagation on the sub-atomic scale. First the ballistic electron transport in a strong, non-uniform magnetic field is discussed. Than a possible

  13. Individualization in a Lecture Hall Setting. (United States)

    Halyard, Rebecca A.

    A two-quarter Human Anatomy and Physiology course for health-science students has been developed which incorporates the principles of individualization while maintaining the lecture hall setting. The lecture method contributes the following components to the course: (1) no special equipment or supplies; (2) personal interaction between instructor…

  14. Prospect of quantum anomalous Hall and quantum spin Hall effect in doped kagome lattice Mott insulators. (United States)

    Guterding, Daniel; Jeschke, Harald O; Valentí, Roser


    Electronic states with non-trivial topology host a number of novel phenomena with potential for revolutionizing information technology. The quantum anomalous Hall effect provides spin-polarized dissipation-free transport of electrons, while the quantum spin Hall effect in combination with superconductivity has been proposed as the basis for realizing decoherence-free quantum computing. We introduce a new strategy for realizing these effects, namely by hole and electron doping kagome lattice Mott insulators through, for instance, chemical substitution. As an example, we apply this new approach to the natural mineral herbertsmithite. We prove the feasibility of the proposed modifications by performing ab-initio density functional theory calculations and demonstrate the occurrence of the predicted effects using realistic models. Our results herald a new family of quantum anomalous Hall and quantum spin Hall insulators at affordable energy/temperature scales based on kagome lattices of transition metal ions.

  15. Inertial-Hall effect: the influence of rotation on the Hall conductivity

    Directory of Open Access Journals (Sweden)

    Julio E. Brandão


    Full Text Available Inertial effects play an important role in classical mechanics but have been largely overlooked in quantum mechanics. Nevertheless, the analogy between inertial forces on mass particles and electromagnetic forces on charged particles is not new. In this paper, we consider a rotating non-interacting planar two-dimensional electron gas with a perpendicular uniform magnetic field and investigate the effects of the rotation in the Hall conductivity. The rotation introduces a shift and a split in the Landau levels. As a consequence of the break of the degeneracy, the counting of the states fully occupied below the Fermi energy increases, tuning the Hall quantization steps. The rotation also changes the quantum Hall plateau widths. Additionally, we find the Hall quantization steps as a function of rotation at a fixed value of the magnetic field.

  16. Dust exposure in indoor climbing halls. (United States)

    Weinbruch, Stephan; Dirsch, Thomas; Ebert, Martin; Hofmann, Heiko; Kandler, Konrad


    The use of hydrated magnesium carbonate hydroxide (magnesia alba) for drying the hands is a strong source for particulate matter in indoor climbing halls. Particle mass concentrations (PM10, PM2.5 and PM1) were measured with an optical particle counter in 9 indoor climbing halls and in 5 sports halls. Mean values for PM10 in indoor climbing halls are generally on the order of 200-500 microg m(-3). For periods of high activity, which last for several hours, PM10 values between 1000 and 4000 microg m(-3) were observed. PM(2.5) is on the order of 30-100 microg m(-3) and reaches values up to 500 microg m(-3), if many users are present. In sports halls, the mass concentrations are usually much lower (PM10 indoor climbing were observed. The size distribution and the total particle number concentration (3.7 nm-10 microm electrical mobility diameter) were determined in one climbing hall by an electrical aerosol spectrometer. The highest number concentrations were between 8000 and 12 000 cm(-3), indicating that the use of magnesia alba is no strong source for ultrafine particles. Scanning electron microscopy and energy-dispersive X-ray microanalysis revealed that virtually all particles are hydrated magnesium carbonate hydroxide. In-situ experiments in an environmental scanning electron microscope showed that the particles do not dissolve at relative humidities up to 100%. Thus, it is concluded that solid particles of magnesia alba are airborne and have the potential to deposit in the human respiratory tract. The particle mass concentrations in indoor climbing halls are much higher than those reported for schools and reach, in many cases, levels which are observed for industrial occupations. The observed dust concentrations are below the current occupational exposure limits in Germany of 3 and 10 mg m(-3) for respirable and inhalable dust. However, the dust concentrations exceed the German guide lines for work places without use of hazardous substances. In addition

  17. Digital technology impacts on the Arnhem transfer hall structural design

    NARCIS (Netherlands)

    Van de Straat, R.; Hofman, S.; Coenders, J.L.; Paul, J.C.


    The new Transfer Hall in Arnhem is one of the key projects to prepare the Dutch railways for the increased future demands for capacity. UNStudio developed a master plan in 1996 for the station area of which the completion of the Transfer Hall in 2015 will be a final milestone. The Transfer Hall is a

  18. Topological honeycomb magnon Hall effect: A calculation of thermal Hall conductivity of magnetic spin excitations

    Energy Technology Data Exchange (ETDEWEB)

    Owerre, S. A., E-mail: [African Institute for Mathematical Sciences, 6 Melrose Road, Muizenberg, Cape Town 7945, South Africa and Perimeter Institute for Theoretical Physics, 31 Caroline St. N., Waterloo, Ontario N2L 2Y5 (Canada)


    Quite recently, the magnon Hall effect of spin excitations has been observed experimentally on the kagome and pyrochlore lattices. The thermal Hall conductivity κ{sup xy} changes sign as a function of magnetic field or temperature on the kagome lattice, and κ{sup xy} changes sign upon reversing the sign of the magnetic field on the pyrochlore lattice. Motivated by these recent exciting experimental observations, we theoretically propose a simple realization of the magnon Hall effect in a two-band model on the honeycomb lattice. The magnon Hall effect of spin excitations arises in the usual way via the breaking of inversion symmetry of the lattice, however, by a next-nearest-neighbour Dzyaloshinsky-Moriya interaction. We find that κ{sup xy} has a fixed sign for all parameter regimes considered. These results are in contrast to the Lieb, kagome, and pyrochlore lattices. We further show that the low-temperature dependence on the magnon Hall conductivity follows a T{sup 2} law, as opposed to the kagome and pyrochlore lattices. These results suggest an experimental procedure to measure thermal Hall conductivity within a class of 2D honeycomb quantum magnets and ultracold atoms trapped in a honeycomb optical lattice.

  19. Equilibrium large vortex state in ferromagnetic disks (United States)

    Metlov, Konstantin L.


    Magnetic vortices in soft ferromagnetic nano-disks have been extensively studied for at least several decades both for their applied (non-volatile information storage) as well as fundamental value. Here, it is shown that there is another vortex ground state with large radius-dependent core profile in nano-scale ferromagnetic disks of several exchange lengths in size. Its energy is computed numerically and its stability is studied analytically, which allows to plot it on magnetic phase diagram. Large vortices may exist on par with the classical ones, while being separated by an energy barrier, controllable by tuning the geometry and material of ferromagnetic disk.

  20. Diagnostics Systems for Permanent Hall Thrusters Development (United States)

    Ferreira, Jose Leonardo; Soares Ferreira, Ivan; Santos, Jean; Miranda, Rodrigo; Possa, M. Gabriela

    This work describes the development of Permanent Magnet Hall Effect Plasma Thruster (PHALL) and its diagnostic systems at The Plasma Physics Laboratory of University of Brasilia. The project consists on the construction and characterization of plasma propulsion engines based on the Hall Effect. Electric thrusters have been employed in over 220 successful space missions. Two types stand out: the Hall-Effect Thruster (HET) and the Gridded Ion Engine (GIE). The first, which we deal with in this project, has the advantage of greater simplicity of operation, a smaller weight for the propulsion subsystem and a longer shelf life. It can operate in two configurations: magnetic layer and anode layer, the difference between the two lying in the positioning of the anode inside the plasma channel. A Hall-Effect Thruster-HET is a type of plasma thruster in which the propellant gas is ionized and accelerated by a magneto hydrodynamic effect combined with electrostatic ion acceleration. So the essential operating principle of the HET is that it uses a J x B force and an electrostatic potential to accelerate ions up to high speeds. In a HET, the attractive negative charge is provided by electrons at the open end of the Thruster instead of a grid, as in the case of the electrostatic ion thrusters. A strong radial magnetic field is used to hold the electrons in place, with the combination of the magnetic field and the electrostatic potential force generating a fast circulating electron current, the Hall current, around the axis of the Thruster, mainly composed by drifting electrons in an ion plasma background. Only a slow axial drift towards the anode occurs. The main attractive features of the Hall-Effect Thruster are its simple design and operating principles. Most of the Hall-Effect Thrusters use electromagnet coils to produce the main magnetic field responsible for plasma generation and acceleration. In this paper we present a different new concept, a Permanent Magnet Hall

  1. Accurate micro Hall effect measurements on scribe line pads

    DEFF Research Database (Denmark)

    Østerberg, Frederik Westergaard; Petersen, Dirch Hjorth; Wang, Fei


    Hall mobility and sheet carrier density are important parameters to monitor in advanced semiconductor production. If micro Hall effect measurements are done on small pads in scribe lines, these parameters may be measured without using valuable test wafers. We report how Hall mobility can...... be extracted from micro four-point measurements performed on a rectangular pad. The dimension of the investigated pad is 400 × 430 ¿m2, and the probe pitches range from 20 ¿m to 50 ¿m. The Monte Carlo method is used to find the optimal way to perform the Hall measurement and extract Hall mobility most...

  2. Identifying concert halls from source presence vs room presence. (United States)

    Haapaniemi, Aki; Lokki, Tapio


    Identification of concert halls was studied to uncover whether the early or late part of the acoustic response is more salient in a hall's fingerprint. A listening test was conducted with auralizations of measured halls using full, hybrid, and truncated impulse responses convolved with anechoic symphonic music. Subjects identified halls more reliably based on differences in early responses rather than late responses, although varying the late response had more effect on acoustic parameters. The results suggest that in a typical situation with running symphonic music, the early response determines the perceptual fingerprint of a hall more than the late response.

  3. The Hall effect in the organic conductor TTF–TCNQ: choice of geometry for accurate measurements of a highly anisotropic system

    DEFF Research Database (Denmark)

    Tafra, E; Čulo, M; Basletić, M


    We have measured the Hall effect on recently synthesized single crystals of the quasi-one-dimensional organic conductor TTF–TCNQ (tetrathiafulvalene–tetracyanoquinodimethane), a well known charge transfer complex that has two kinds of conductive stacks: the donor (TTF) and the acceptor (TCNQ...... Hall effect measurements. Our results show, contrary to past belief, that the Hall coefficient does not depend on the geometry of measurements and that the Hall coefficient value is approximately zero in the high temperature region (T > 150 K), implying that there is no dominance of either the TTF...... or the TCNQ chain. At lower temperatures our measurements clearly prove that all three phase transitions of TTF–TCNQ could be identified from Hall effect measurements....

  4. Music hall Markneukirchen; Musikhalle in Markneukirchen

    Energy Technology Data Exchange (ETDEWEB)



    The article presents the new building of the music hall Markneukirchen. From the planned use of the building result very high demands on the ventilation system in order to keep to a sound power level of less than 30 dB(A) in the hall. The building services are dealt with using numerous flowsheets and diagrams: Heat supply, ventilation system, sanitary system, building management, instrumentation and control, electric and lighting systems. (BWI) [Deutsch] Der vorliegende Beitrag stellt den Neubau der Musikhalle Markneukirchen vor. Durch das Nutzungskonzept ergeben sich fuer die Einhaltung eines Schalleistungspegels von weniger als 30 dB(A) im Saalbereich an die Lueftungsanlage sehr hohe Ansprueche. Es werden die raumlufttechnischen Anlagen anhand zahlreicher Flussbilder und Abbildungen vorgestellt: Waermeversorgung, Lueftungstechnik, Sanitaertechnik, Gebaeudeleit- und MSR-Technik, Elektro- und Lichttechnik. (BWI)

  5. Stuart Hall and Cultural Studies, circa 1983

    Directory of Open Access Journals (Sweden)

    Ann Curthoys


    Full Text Available Stuart Hall sought to internationalise theoretical debates and to create Cultural Studies as interdisciplinary. We chart his theoretical journey through a detailed examination of a series of lectures delivered in 1983 and now published for the first time. In these lectures, he discusses theorists such as E.P. Thompson, Raymond Williams, Louis Althusser, Levi Strauss and Antonio Gramsci, and explores the relationship between ideas and social structure, the specificities of class and race, and the legacies of slavery. We note his turn towards metaphors of divergence and dispersal and highlight how autobiographical and deeply personal Hall is in these lectures, especially in his ego histoire moment of traumatic memory recovery.

  6. Three halls for music performance in Chile (United States)

    Delannoy, Jaime; Heuffemann, Carolina; Ramirez, Daniel; Galvez, Fernando


    The primary purpose of this work was to investigate about the present acoustic conditions of used architectonic spaces in Santiago of Chile for orchestras of classic music performance. The studied halls were three: Aula Magna Universidad de Santiago, Teatro Municipal de Nunoa, and Teatro Baquedano. The used methodology was based on studies made by L. Beranek, M. Barron, among others, in concert halls worldwide. As it guides, for the measurement procedure, physical parameters RT, EDT, C50, C80, LF, BR, G, U50 were evaluated according to norm ISO 3382. On the other hand, it has been defined, to proposal way, a questionnaire of subjective valuation directed to musicians, specialized conductors, and listeners.

  7. Anyons in Integer Quantum Hall Magnets

    Directory of Open Access Journals (Sweden)

    Armin Rahmani


    Full Text Available Strongly correlated fractional quantum Hall liquids support fractional excitations, which can be understood in terms of adiabatic flux insertion arguments. A second route to fractionalization is through the coupling of weakly interacting electrons to topologically nontrivial backgrounds such as in polyacetylene. Here, we demonstrate that electronic fractionalization combining features of both these mechanisms occurs in noncoplanar itinerant magnetic systems, where integer quantum Hall physics arises from the coupling of electrons to the magnetic background. The topologically stable magnetic vortices in such systems carry fractional (in general, irrational electronic quantum numbers and exhibit Abelian anyonic statistics. We analyze the properties of these topological defects by mapping the distortions of the magnetic texture onto effective non-Abelian vector potentials. We support our analytical results with extensive numerical calculations.

  8. Homotopy arguments for quantized Hall conductivity

    CERN Document Server

    Richter, T


    Using the strong localization bounds obtained by the Aizenman-Molcanov method for a particle in a magnetic field and a disordered potential, we show that the zero-temperature Hall conductivity of a gas of such particles is quantized and constant as long as both Fermi energy and disorder coupling parameter vary in a region of strong localization of the corresponding two-dimensional phase diagram.

  9. SERVIR Town Hall - Connecting Space to Village (United States)

    Limaye, Ashutosh S.; Searby, Nancy D.; Irwin, Daniel; Albers, Cerese


    SERVIR, a joint NASA-USAID project, strives to improve environmental decision making through the use of Earth observations, models, and geospatial technology innovations. SERVIR connects these assets with the needs of end users in Mesoamerica, East Africa, and Hindu Kush-Himalaya regions. This Town Hall meeting will engage the AGU community by exploring examples of connecting Space to Village with SERVIR science applications.

  10. Quantum spin Hall phase in multilayer graphene


    García-Martínez, N. A.; Lado, Jose L.; Fernández Rossier, Joaquín


    The so-called quantum spin Hall phase is a topologically nontrivial insulating phase that is predicted to appear in graphene and graphenelike systems. In this paper we address the question of whether this topological property persists in multilayered systems. We consider two situations: purely multilayer graphene and heterostructures where graphene is encapsulated by trivial insulators with a strong spin-orbit coupling. We use a four-orbital tight-binding model that includes full atomic spin-...

  11. SPS beam to the West Hall

    CERN Multimedia

    CERN PhotoLab


    One of the two target stations feeding the West Hall (see Annual Report 1976). After the proton beam was split into three branches, the outer two were directed on to targets in the cast iron shielding box, the centre one passing through the box to another target station downstream. Five different targets could be put in each beam, controlled by the mechanism seen on top.

  12. Views of the ATLAS experimental hall

    CERN Multimedia

    Maximilien Brice


    The shell of the ATLAS detector is seen from many angles within its cavernous underground hall. All of the eight huge toroid magnets have been installed and fixed in place. The core of the detector, the largest of its type in the world, will soon be filled with many different detector-elements to observe the results of proton-proton collisions at the LHC when it is turned on in 2008.

  13. Multipole expansion in the quantum hall effect

    Energy Technology Data Exchange (ETDEWEB)

    Cappelli, Andrea [INFN, Sezione di Firenze,Via G. Sansone 1, 50019 Sesto Fiorentino, Firenze (Italy); Randellini, Enrico [INFN, Sezione di Firenze,Via G. Sansone 1, 50019 Sesto Fiorentino, Firenze (Italy); Dipartimento di Fisica, Università di Firenze,Via G. Sansone 1, 50019 Sesto Fiorentino, Firenze (Italy)


    The effective action for low-energy excitations of Laughlin’s states is obtained by systematic expansion in inverse powers of the magnetic field. It is based on the W-infinity symmetry of quantum incompressible fluids and the associated higher-spin fields. Besides reproducing the Wen and Wen-Zee actions and the Hall viscosity, this approach further indicates that the low-energy excitations are extended objects with dipolar and multipolar moments.

  14. Acoustics in rock and pop music halls

    DEFF Research Database (Denmark)

    Larsen, Niels Werner; Thompson, Eric Robert; Gade, Anders Christian


    The existing body of literature regarding the acoustic design of concert halls has focused almost exclusively on classical music, although there are many more performances of rhythmic music, including rock and pop. Objective measurements were made of the acoustics of twenty rock music venues...... frequency sounds are typically highly amplified, they play an important role in the subjective ratings and the 63-Hz-band must be included in objective measurements and recommendations....

  15. Double Hall sensor structure reducing voltage offset (United States)

    Oszwaldowski, M.; El-Ahmar, S.


    In this paper, we report on the double Hall sensor structure (DHSS) in which the voltage offset can be effectively reduced. The DHSS is composed of two standard Hall sensors that are activated with two currents from electrically independent current sources. The operation principle of the DHSS is explained in detail, and the concluded properties of the DHSS are confirmed in the experimental part of the paper. The measurements are performed on DHSSs based on InSb thin films. The offset is reduced by about three orders of magnitude. The minimum value of the reduced offset obtained is 10 μV. It appears that the minimum reduced offset is limited by the electric noise. The advantage of DHSS is that it can be manufactured with the standard thin film technology enabling effective miniaturization of the system. The DHSS can effectively be used for the measurements of the Hall effect in ultra-thin layers containing the two dimensional electron gas, such as the epitaxial graphene.

  16. Spin Hall and spin swapping torques in diffusive ferromagnets

    KAUST Repository

    Pauyac, C. O.


    A complete set of the generalized drift-diffusion equations for a coupled charge and spin dynamics in ferromagnets in the presence of extrinsic spin-orbit coupling is derived from the quantum kinetic approach, covering major transport phenomena, such as the spin and anomalous Hall effects, spin swapping, spin precession and relaxation processes. We argue that the spin swapping effect in ferromagnets is enhanced due to spin polarization, while the overall spin texture induced by the interplay of spin-orbital and spin precessional effects displays a complex spatial dependence that can be exploited to generate torques and nucleate/propagate domain walls in centrosymmetric geometries without use of external polarizers, as opposed to the conventional understanding of spin-orbit mediated torques.

  17. Antiferromagnetic skyrmion crystals: Generation, topological Hall, and topological spin Hall effect (United States)

    Göbel, Börge; Mook, Alexander; Henk, Jürgen; Mertig, Ingrid


    Skyrmions are topologically nontrivial, magnetic quasiparticles that are characterized by a topological charge. A regular array of skyrmions, a skyrmion crystal (SkX), features the topological Hall effect (THE) of electrons, which, in turn, gives rise to the Hall effect of the skyrmions themselves. It is commonly believed that antiferromagnetic skyrmion crystals (AFM-SkXs) lack both effects. In this Rapid Communication, we present a generally applicable method to create stable AFM-SkXs by growing a two-sublattice SkX onto a collinear antiferromagnet. As an example we show that both types of skyrmion crystals, conventional and antiferromagnetic, exist in honeycomb lattices. While AFM-SkXs with equivalent lattice sites do not show a THE, they exhibit a topological spin Hall effect. On top of this, AFM-SkXs on inequivalent sublattices exhibit a nonzero THE, which may be utilized in spintronics devices. Our theoretical findings call for experimental realization.

  18. Hall viscosity: A link between quantum Hall systems, plasmas and liquid crystals

    Energy Technology Data Exchange (ETDEWEB)

    Lingam, Manasvi, E-mail:


    In this Letter, the assumption of two simple postulates is shown to give rise to a Hall viscosity term via an action principle formulation. The rationale behind the two postulates is clearly delineated, and the connections to an intrinsic angular momentum are emphasized. By employing this methodology, it is shown that Hall viscosity appears in a wide range of fields, and the interconnectedness of quantum Hall systems, plasmas and nematic liquid crystals is hypothesized. Potential avenues for experimental and theoretical work arising from this cross-fertilization are also indicated. - Highlights: • Connections between simple 2D fluid models in different fields of physics presented. • Structure emerges via varied physical mechanisms driven by internal angular momentum. • Properties of these models such as Casimirs, equilibria and stability are analyzed.

  19. Kelvin-Helmholtz Instability in a Cool Solar Jet in the Framework of Hall Magnetohydrodynamics: A Case Study (United States)

    Zhelyazkov, I.; Dimitrov, Z.


    We investigate the conditions under which the magnetohydrodynamic (MHD) modes in a cylindrical magnetic flux tube moving along its axis become unstable against the Kelvin-Helmholtz (KH) instability. We use the dispersion relations of MHD modes obtained from the linearized Hall MHD equations for cool (zero beta) plasma by assuming real wave numbers and complex angular wave frequencies/complex wave phase velocities. The dispersion equations are solved numerically at fixed input parameters and varying values of the ratio l_{Hall}/a, where l_{Hall} = c/ω_{pi} (c being the speed of light, and ω_{pi} the ion plasma frequency) and a is the flux tube radius. It is shown that the stability of the MHD modes depends upon four parameters: the density contrast between the flux tube and its environment, the ratio of external and internal magnetic fields, the ratio l_{Hall}/a, and the value of the Alfvén Mach number defined as the ratio of the tube axial velocity to Alfvén speed inside the flux tube. It is found that at high density contrasts, for small values of l_{Hall}/a, the kink (m = 1) mode can become unstable against KH instability at some critical Alfvén Mach number (or equivalently at critical flow speed), but a threshold l_{Hall}/a can suppress the onset of the KH instability. At small density contrasts, however, the magnitude of l_{Hall}/a does not affect noticeably the condition for instability occurrence - even though it can reduce the critical Alfvén Mach number. It is established that the sausage mode (m = 0) is not subject to the KH instability.

  20. Conductivity tensor in a holographic quantum Hall ferromagnet

    Directory of Open Access Journals (Sweden)

    Joel Hutchinson


    Full Text Available The Hall and longitudinal conductivities of a recently studied holographic model of a quantum Hall ferromagnet are computed using the Karch–O'Bannon technique. In addition, the low temperature entropy of the model is determined. The holographic model has a phase transition as the Landau level filling fraction is increased from zero to one. We argue that this phase transition allows the longitudinal conductivity to have features qualitatively similar to those of two dimensional electron gases in the integer quantum Hall regime. The argument also applies to the low temperature limit of the entropy. The Hall conductivity is found to have an interesting structure. Even though it does not exhibit Hall plateaux, it has a flattened dependence on the filling fraction with a jump, analogous to the interpolation between Hall plateaux, at the phase transition.

  1. Commemorative Symposium on the Hall Effect and its Applications

    CERN Document Server

    Westgate, C


    In 1879, while a graduate student under Henry Rowland at the Physics Department of The Johns Hopkins University, Edwin Herbert Hall discovered what is now universally known as the Hall effect. A symposium was held at The Johns Hopkins University on November 13, 1979 to commemorate the lOOth anniversary of the discovery. Over 170 participants attended the symposium which included eleven in­ vited lectures and three speeches during the luncheon. During the past one hundred years, we have witnessed ever ex­ panding activities in the field of the Hall effect. The Hall effect is now an indispensable tool in the studies of many branches of condensed matter physics, especially in metals, semiconductors, and magnetic solids. Various components (over 200 million!) that utilize the Hall effect have been successfully incorporated into such devices as keyboards, automobile ignitions, gaussmeters, and satellites. This volume attempts to capture the important aspects of the Hall effect and its applications. It includes t...

  2. Basic Instrumentation for Hall A at Jefferson Jab

    Energy Technology Data Exchange (ETDEWEB)

    The Jefferson Lab Hall A Collaboration


    The instrumentation in Hall A at the JLab was designed to study electro- and photo-induced reactions at very high luminosity and good momentum and angular resolution for at least one of the reaction products. A collaboration of approximately 50 institutions from all over the world has actively contributed and participated in the design, construction and commissioning of the Hall A instrumentation. The basic Hall A equipment is described herein.

  3. Precision of single-engage micro Hall effect measurements

    DEFF Research Database (Denmark)

    Henrichsen, Henrik Hartmann; Hansen, Ole; Kjær, Daniel


    Recently a novel microscale Hall effect measurement technique has been developed to extract sheet resistance (RS), Hall sheet carrier density (NHS) and Hall mobility (μH) from collinear micro 4-point probe measurements in the vicinity of an insulating boundary [1]. The technique measures in less......]. In this study we calculate the measurement error on RS, NHS and μH resulting from electrode position errors, probe placement, sample size and Hall signal magnitude. We show the relationship between measurement precision and electrode pitch, which is important when down-scaling the micro 4-point probe to fit...

  4. Hall Sensor Output Signal Fault-Detection & Safety Implementation Logic

    Directory of Open Access Journals (Sweden)

    Lee SangHun


    Full Text Available Recently BLDC motors have been popular in various industrial applications and electric mobility. Recently BLDC motors have been popular in various industrial applications and electric mobility. In most brushless direct current (BLDC motor drives, there are three hall sensors as a position reference. Low resolution hall effect sensor is popularly used to estimate the rotor position because of its good comprehensive performance such as low cost, high reliability and sufficient precision. Various possible faults may happen in a hall effect sensor. This paper presents a fault-tolerant operation method that allows the control of a BLDC motor with one faulty hall sensor and presents the hall sensor output fault-tolerant control strategy. The situations considered are when the output from a hall sensor stays continuously at low or high levels, or a short-time pulse appears on a hall sensor signal. For fault detection, identification of a faulty signal and generating a substitute signal, this method only needs the information from the hall sensors. There are a few research work on hall effect sensor failure of BLDC motor. The conventional fault diagnosis methods are signal analysis, model based analysis and knowledge based analysis. The proposed method is signal based analysis using a compensation signal for reconfiguration and therefore fault diagnosis can be fast. The proposed method is validated to execute the simulation using PSIM.

  5. High Efficiency Hall Thruster Discharge Power Converter Project (United States)

    National Aeronautics and Space Administration — Busek leveraged previous, internally sponsored, high power, Hall thruster discharge converter development which allowed it to design, build, and test new printed...

  6. Quantum Hall effect in multi-terminal suspended graphene devices (United States)

    Ghahari, Fereshte; Zhao, Yue; Bolotin, Kirill; Kim, Philip


    The integer and fractional quantum hall effects have been already observed in two terminal suspended graphene devices. However in this two probe device geometry, mixing between magnetoresistance ρxx and Hall resistance ρxy for incompletely developed quantum Hall states leads to substantial deviation of conductance plateaus values. In this talk, we present the experimental results from four terminal suspended graphene devices. The quality of quantum Hall effect will be discussed in muti-terminal device geometry in conjunction with the current-induced annealing process to improve the quality of graphene samples.

  7. Planar Hall Effect Sensors for Biodetection

    DEFF Research Database (Denmark)

    Rizzi, Giovanni

    as labels and planar Hall effect bridge (PHEB) magnetic field sensor as readout for the beads. The choice of magnetic beads as label is motivated by the lack of virtually any magnetic background from biological samples. Moreover, magnetic beads can be manipulated via an external magnetic field...... system capable of generating both temperature and concentration gradients over the sensor surface. The temperature and buffer concentration can be varied in order to perform denaturation analysis of the DNA hybrids. In this thesis, this kind assay is tested with temperature varying from 20ºC to 70º...

  8. Neutronic design of MYRRHA reactor hall shielding (United States)

    Celik, Yurdunaz; Stankovskiy, Alexey; Eynde, Gert Van den


    The lateral shielding of a 600 MeV proton linear accelerator beam line in the MYRRHA reactor hall has been assessed using neutronic calculations by the MCNPX code complemented with analytical predictions. Continuous beam losses were considered to define the required shielding thickness that meets the requirements for the dose rate limits. Required shielding thicknesses were investigated from the viewpoint of accidental full beam loss as well as beam loss on collimator. The results confirm that the required shielding thicknesses are highly sensitive to the spatial shape of the beam and strongly divergent beam losses. Therefore shielding barrier should be designed according to the more conservative assumptions.


    Directory of Open Access Journals (Sweden)

    Peter Turček


    Full Text Available The construction of an industrial park is now being prepared near the town of Nitra. The investor fixed very strict conditions for the bearing capacity and, above all, the settlement of halls and their floors. The geological conditions at the construction site are difficult: there are soft clay soils with high compressibility and low bearing capacity. A detailed analysis of soil improvement was made. Stone columns were prepared to be fitted into an approximately 5 m thick layer of soft clay. The paper shows the main steps used in the design of the stone columns.

  10. Current correlations in quantum spin Hall insulators. (United States)

    Schmidt, Thomas L


    We consider a four-terminal setup of a two-dimensional topological insulator (quantum spin Hall insulator) with local tunneling between the upper and lower edges. The edge modes are modeled as helical Luttinger liquids and the electron-electron interactions are taken into account exactly. Using perturbation theory in the tunneling, we derive the cumulant generating function for the interedge current. We show that different possible transport channels give rise to different signatures in the current noise and current cross correlations, which could be exploited in experiments to elucidate the interplay between electron-electron interactions and the helical nature of the edge states. © 2011 American Physical Society

  11. Bimetric Theory of Fractional Quantum Hall States (United States)

    Gromov, Andrey; Son, Dam Thanh


    We present a bimetric low-energy effective theory of fractional quantum Hall (FQH) states that describes the topological properties and a gapped collective excitation, known as the Girvin-Macdonald-Platzman (GMP) mode. The theory consists of a topological Chern-Simons action, coupled to a symmetric rank-2 tensor, and an action à la bimetric gravity, describing the gapped dynamics of a spin-2 mode. The theory is formulated in curved ambient space and is spatially covariant, which allows us to restrict the form of the effective action and the values of phenomenological coefficients. Using bimetric theory, we calculate the projected static structure factor up to the k6 order in the momentum expansion. To provide further support for the theory, we derive the long-wave limit of the GMP algebra, the dispersion relation of the GMP mode, and the Hall viscosity of FQH states. The particle-hole (PH) transformation of the theory takes a very simple form, making the duality between FQH states and their PH conjugates manifest. We also comment on the possible applications to fractional Chern insulators, where closely related structures arise. It is shown that the familiar FQH observables acquire a curious geometric interpretation within the bimetric formalism.

  12. Hypernuclear Spectroscopy at JLab Hall C

    Energy Technology Data Exchange (ETDEWEB)

    Hashimoto, Osamu; Doi, Daisuke; Fujii, Yu; Toshiyuki, Gogami; Kanda, Hiroki; Kaneta, M; Kawama, Daisuke; Maeda, Kazushige; Maruta, Tomofumi; Matsumura, Akihiko; Nagao, Sho; Nakamura, Satoshi; Shichijo, Ayako; Tamura, Hirokazu; Taniya, Naotaka; Yamamoto, Taku; Yokota, Kosuke; Kato, S; Sato, Yoshinori; Takahashi, Toshiyuki; Noumi, Hiroyuki; Motoba, T; Hiyama, E; Albayrak, Ibrahim; Ates, Ozgur; Chen, Chunhua; Christy, Michael; Keppel, Cynthia; Kohl, Karl; Li, Ya; Liyanage, Anusha Habarakada; Tang, Liguang; Walton, T; Ye, Zhihong; Yuan, Lulin; Zhu, Lingyan; Baturin, Pavlo; Boeglin, Werner; Dhamija, Seema; Markowitz, Pete; Raue, Brian; Reinhold, Joerg; Hungerford, Ed; Ent, Rolf; Fenker, Howard; Gaskell, David; Horn, Tanja; Jones, Mark; Smith, Gregory; Vulcan, William; Wood, Stephen; Johnston, C; Simicevic, Neven; Wells, Stephen; Samantha, Chhanda; Hu, Bitao; Shen, Ji; Wang, W; Zhang, Xiaozhuo; Zhang, Yi; Feng, Jing; Fu, Y; Zhou, Jian; Zhou, S; Jiang, Yi; Lu, H; Yan, Xinhu; Ye, Yunxiu; Gan, Liping; Ahmidouch, Abdellah; Danagoulian, Samuel; Gasparian, Ashot; Elaasar, Mostafa; Wesselmann, Frank; Asaturyan, Arshak; Margaryan, Amur; Mkrtchyan, Arthur; Mkrtchyan, Hamlet; Tadevosyan, Vardan; Androic, Darko; Furic, Miroslav; Petkovic, Tomislav; Seva, Tomislav; Niculescu, Gabriel; Niculescu, Maria-Ioana; Rodriguez, Victor; Cisbani, Evaristo; Cusanno, Francesco; Garibaldi, Franco; Urciuoli, Guido; De Leo, Raffaele; Maronne, S; Achenbach, Carsten


    Since the 1st generation experiment, E89-009, which was successfully carried out as a pilot experiment of (e,e'K+) hypernuclear spectroscopy at JLab Hall C in 2000, precision hypernuclear spectroscopy by the (e,e'K+) reactions made considerable progress. It has evolved to the 2nd generation experiment, E01-011, in which a newly constructed high resolution kaon spectrometer (HKS) was installed and the “Tilt method” was adopted in order to suppress large electromagnetic background and to run with high luminosity. Preliminary high-resolution spectra of 7ΛHe and 28ΛAl together with that of 12ΛB that achieved resolution better than 500 keV(FWHM) were obtained. The third generation experiment, E05-115, has completed data taking with an experimental setup combining a new splitter magnet, high resolution electron spectrometer (HES) and the HKS used in the 2nd generation experiment. The data were accumulated with targets of 7Li, 9Be, 10B, 12C and 52Cr as well as with those of CH2 and H2O for calibration. The analysis is under way with particular emphasis of determining precision absolute hypernuclear masses. In this article, hypernuclear spectroscopy program in the wide mass range at JLab Hall C that has undergone three generation is described.

  13. Quantum spin Hall phase in multilayer graphene (United States)

    García-Martínez, N. A.; Lado, J. L.; Fernández-Rossier, J.


    The so-called quantum spin Hall phase is a topologically nontrivial insulating phase that is predicted to appear in graphene and graphenelike systems. In this paper we address the question of whether this topological property persists in multilayered systems. We consider two situations: purely multilayer graphene and heterostructures where graphene is encapsulated by trivial insulators with a strong spin-orbit coupling. We use a four-orbital tight-binding model that includes full atomic spin-orbit coupling and we calculate the Z2 topological invariant of the bulk states as well as the edge states of semi-infinite crystals with armchair termination. For homogeneous multilayers we find that even when the spin-orbit interaction opens a gap for all possible stackings, only those with an odd number of layers host gapless edge states while those with an even number of layers are trivial insulators. For heterostructures where graphene is encapsulated by trivial insulators, it turns out that interlayer coupling is able to induce a topological gap whose size is controlled by the spin-orbit coupling of the encapsulating materials, indicating that the quantum spin Hall phase can be induced by proximity to trivial insulators.

  14. Bimetric Theory of Fractional Quantum Hall States

    Directory of Open Access Journals (Sweden)

    Andrey Gromov


    Full Text Available We present a bimetric low-energy effective theory of fractional quantum Hall (FQH states that describes the topological properties and a gapped collective excitation, known as the Girvin-Macdonald-Platzman (GMP mode. The theory consists of a topological Chern-Simons action, coupled to a symmetric rank-2 tensor, and an action à la bimetric gravity, describing the gapped dynamics of a spin-2 mode. The theory is formulated in curved ambient space and is spatially covariant, which allows us to restrict the form of the effective action and the values of phenomenological coefficients. Using bimetric theory, we calculate the projected static structure factor up to the k^{6} order in the momentum expansion. To provide further support for the theory, we derive the long-wave limit of the GMP algebra, the dispersion relation of the GMP mode, and the Hall viscosity of FQH states. The particle-hole (PH transformation of the theory takes a very simple form, making the duality between FQH states and their PH conjugates manifest. We also comment on the possible applications to fractional Chern insulators, where closely related structures arise. It is shown that the familiar FQH observables acquire a curious geometric interpretation within the bimetric formalism.

  15. The first vineyard concert hall in North America (United States)

    Jaffe, Christopher; Rivera, Carlos


    The first vineyard or surround concert hall designed and built in the Western Hemisphere is the Sala Nezahualcoyotl in Mexico City. The Hall was completed in 1976 and is part of the Cultural Center at the Universidad Nacional Autonoma de Mexico. The hall was named after a Toltec poet, architect, and musician who lived in the 15th century and was the Renaissance man of his day. In order to provide the familiar traditional sound of the rectangular (shoebox) European Hall, the acoustic designers set the criteria for reverberation times through the frequency spectrum and the Initial Time Delay Gap at every seat in the house to match the measurements taken at the Grosser Musik vereinssaal in Vienna and Boston Symphony Hall. In this paper we discuss the techniques used to create the traditional sound in a vineyard hall and the reaction of musicians and audiences to the completed facility. The Sala was the model for Suntory Hall in Japan which in turn spawned a number of vineyard halls in Japan. Most recently, the vineyard style seems to be appealing to more and more symphonic organizations in Europe and North America.

  16. Magnetoresistance in quantum Hall metals due to Pancharatnam ...

    Indian Academy of Sciences (India)

    electron flow is independent of these spacings (require small changes to the phase factor, or negligible changes to the group momentum of a wavefunction). Here, we shall further elaborate on these two processes, and use them to derive and discuss the Hall resistance in quantum Hall metals for both fractional and integer ...

  17. Cultural Composition: Stuart Hall on Ethnicity and the Discursive Turn. (United States)

    Drew, Julie


    Interviews Stuart Hall, a black public intellectual and an activist of the New Left. Discusses the growing disillusionment with cultural studies now that it is no longer in its ascendancy; the proliferation of pedagogical practices given a cultural studies tag; Hall's approval of the use of popular culture in the composition classroom; and the…

  18. Whose Big Prize? A Response to Hall and Gunter (United States)

    Furlong, John


    This article presents the author's response to Hall and Gunter who accuse the author of trying to mount "a stout defence" of New Labour's reforms of the teaching profession. Hall and Gunter go further and accuse the author of "triumphalism" in his use of the title "Tony Blair's big prize". Their second and more…

  19. Spatial sensitivity mapping of Hall crosses using patterned magnetic nanostructures

    NARCIS (Netherlands)

    Alexandrou, M.; Nutter, P.W.; Delalande, M.Y.; de Vries, Jeroen; Hill, E.W.; Schedin, F.; Abelmann, Leon; Thomson, T.


    Obtaining an accurate profile of the spatial sensitivity of Hall cross structures is crucial if such devices are to be used to analyze the switching behavior of magnetic nanostructures and determine the switching field distribution of bit patterned media. Here, we have used the anomalous Hall effect

  20. Acoustic investigations of concert halls for rock music

    DEFF Research Database (Denmark)

    Adelman-Larsen, Niels Werner; Thompson, Eric Robert; Gade, Anders Christian


    Objective measurement data and subjective evaluations have been collected from 20 small-/medium-sized halls in Denmark used for amplified rhythmic music concerts (pop, rock, jazz). The purpose of the study was to obtain knowledge about optimum acoustic conditions for this type of hall. The study...

  1. Acoustic Requirements for a Multi-Purpose Hall. (United States)

    Schulte, W. Allen


    This case study examines the proposed design of a new lecture/recital hall in Centennial Hall at Lynchburg College that will be used for lectures, public events, a film studies course, and musical recitals. It explores the audio-visual challenges presented by the differing acoustical requirements for the building. (EV)

  2. The Impact of Coed Residence Halls on Self-Actualization (United States)

    Schroeder, Charles C.; LeMay, Morris L.


    The purpose of the present study was to determine if there were initial differences on selected scales of the Personal Orientation Inventory (POI) between students who chose to live in coed residence halls and those who chose to live in traditional single-sex residence halls, and also if residing in coed living units affected the further…

  3. Mary E. Hall: Dawn of the Professional School Librarian (United States)

    Alto, Teresa


    A century ago, a woman named Mary E. Hall convinced school leaders of the need for the professional school librarian--a librarian who cultivated a love of reading, academic achievement, and independent learning skills. After graduating from New York City's Pratt Institute Library School in 1895, Hall developed her vision for the high school…

  4. A Residential Paradox?: Residence Hall Attributes and College Student Outcomes (United States)

    Bronkema, Ryan; Bowman, Nicholas A.


    The researchers of this brief observed that few environments have the potential to shape the outcomes of college students as much as residence halls. As a result, residence halls have the capacity to foster a strong sense of community as well as other important outcomes such as college satisfaction and academic achievement. However, given the high…

  5. G. Stanley Hall's Adolescence: A centennial reappraisal introduction. (United States)

    Arnett, Jeffrey Jensen; Cravens, Hamilton


    This article is an overview of the special issue "G. Stanley Hall's Adolescence: A Centennial Reappraisal." First, a brief biography of Hall is presented. Then each of the six articles in the special issue is summarized. Three of the articles are by historians and three are by psychologists, but all six articles integrate history and psychology.

  6. Stuart Hall on Racism and the Importance of Diasporic Thinking (United States)

    Rizvi, Fazal


    In this article, I want to show how my initial encounter with the work of Stuart Hall was grounded in my reading of the later philosophy of Ludwig Wittgenstein, and was shaped by my interest in understanding the nature of racism across the three countries in which I had lived. Over the years, Hall's various writings have helped me to make sense of…

  7. Quantization of Hall Resistance at the Metallic Interface between an Oxide Insulator and SrTiO3

    DEFF Research Database (Denmark)

    Trier, Felix; Prawiroatmodjo, Guenevere E. D. K.; Zhong, Zhicheng


    The two-dimensional metal forming at the interface between an oxide insulatorand SrTiO3 provides new opportunities for oxide electronics. However, the quantum Hall effect, one of the most fascinating effects of electrons confined in two dimensions, remains underexplored at these complex oxide...... heterointerfaces. Here, we report the experimental observation of quantized Hall resistance in a SrTiO3 heterointerface based on the modulation-doped amorphous-LaAlO3/SrTiO3 heterostructure, which exhibits both highelectron mobility exceeding 10, 000 cm2/V s and low carrier density on the order of ~1012 cm-2....... Along with unambiguous Shubnikov-de Haasoscillations, the spacing of the quantized Hall resistance suggests that the interface is comprised of a single quantum well with ten parallel conducting two-dimensional subbands. This provides new insight into the electronic structure of conducting oxide...

  8. Unconventional quantum Hall effect in Floquet topological insulators

    KAUST Repository

    Tahir, M.


    We study an unconventional quantum Hall effect for the surface states of ultrathin Floquet topological insulators in a perpendicular magnetic field. The resulting band structure is modified by photon dressing and the topological property is governed by the low-energy dynamics of a single surface. An exchange of symmetric and antisymmetric surface states occurs by reversing the lights polarization. We find a novel quantum Hall state in which the zeroth Landau level undergoes a phase transition from a trivial insulator state, with Hall conductivity αyx = 0 at zero Fermi energy, to a Hall insulator state with αyx = e2/2h. These findings open new possibilities for experimentally realizing nontrivial quantum states and unusual quantum Hall plateaus at (±1/2,±3/2,±5/2, ...)e2/h. © 2016 IOP Publishing Ltd Printed in the UK.

  9. Formulation of the relativistic quantum Hall effect and parity anomaly (United States)

    Yonaga, Kouki; Hasebe, Kazuki; Shibata, Naokazu


    We present a relativistic formulation of the quantum Hall effect on Haldane sphere. An explicit form of the pseudopotential is derived for the relativistic quantum Hall effect with/without mass term. We clarify particular features of the relativistic quantum Hall states with the use of the exact diagonalization study of the pseudopotential Hamiltonian. Physical effects of the mass term to the relativistic quantum Hall states are investigated in detail. The mass term acts as an interpolating parameter between the relativistic and nonrelativistic quantum Hall effects. It is pointed out that the mass term unevenly affects the many-body physics of the positive and negative Landau levels as a manifestation of the "parity anomaly." In particular, we explicitly demonstrate the instability of the Laughlin state of the positive first relativistic Landau level with the reduction of the charge gap.

  10. Asymmetric nonlinear response of the quantized Hall effect (United States)

    Siddiki, A.; Horas, J.; Kupidura, D.; Wegscheider, W.; Ludwig, S.


    An asymmetric breakdown of the integer quantized Hall effect (IQHE) is investigated. This rectification effect is observed as a function of the current value and its direction in conjunction with an asymmetric lateral confinement potential defining the Hall bar. Our electrostatic definition of the Hall bar via Schottky gates allows a systematic control of the steepness of the confinement potential at the edges of the Hall bar. A softer edge (flatter confinement potential) results in more stable Hall plateaus, i.e. a breakdown at a larger current density. For one soft and one hard edge, the breakdown current depends on its direction, resembling rectification. This nonlinear magneto-transport effect confirms the predictions of an emerging screening theory of the IQHE.

  11. Construction and Operation of a Differential Hall Element Magnetometer (United States)

    Calkins, Matthew W.; Javernick, Philip D.; Quintero, Pedro A.; Calm, Yitzi M.; Meisel, Mark W.


    A Differential Hall Element Magnetometer (DHEM) was constructed to measure the magnetic saturation and coercive fields of small samples consisting of magnetic nanoparticles that may have biomedical applications. The device consists of two matched Hall elements that can be moved through the room temperature bore of a 9 Tesla superconducting magnet. The Hall elements are wired in opposition such that a null response, to within a small offset, is measured in the absence of a sample that may be located on top of one unit. A LabVIEW program controls the current through the Hall elements and measures the net Hall voltage while simultaneously moving the probe through the magnetic field by regulating a linear stepper motor. Ultimately, the system will be tested to obtain a figure of merit using successively smaller samples. Details of the apparatus will be provided along with preliminary data.

  12. Suitable reverberation time for halls for rock and pop music

    DEFF Research Database (Denmark)

    Adelman-Larsen, Niels Werner; Thompson, Eric Robert; Gade, Anders Christian


    The existing body of literature regarding the acoustic design of concert halls has focused almost exclusively on classical music, although there are many more performances of popular music, including rock and pop. Objective measurements were made of the acoustics of 20 rock music venues in Denmark...... and a questionnaire was used in a subjective assessment of those venues with professional rock musicians and sound engineers as expert listeners. Correlations between the measurements show that clarity, including bass frequencies down to 63 Hz, is important for the general impression of the acoustics of the hall....... The best-rated halls in the study have reverberation times that are approximately frequency independent from 0.6 to 1.2 s for hall volumes from 1000 to 6000 m3. The worst rated halls in the study had significantly higher reverberation times in the 63 and 125 Hz bands. Since most audiences at rock concerts...

  13. Fractional quantum Hall states of bosons on cones (United States)

    Wu, Ying-Hai; Tu, Hong-Hao; Sreejith, G. J.


    Motivated by a recent experiment, which synthesizes Landau levels for photons on cones [Schine et al., Nature (London) 534, 671 (2016), 10.1038/nature17943], and more generally the interest in understanding gravitational responses of quantum Hall states, we study fractional quantum Hall states of bosons on cones. A variety of trial wave functions for conical systems are constructed and compared with exact diagonalization results. The tip of a cone is a localized geometrical defect with singular curvature, which can modify the density profiles of quantum Hall states. The density profiles on cones can be used to extract some universal information about quantum Hall states. The values of certain quantities are computed numerically using the density profiles of some quantum Hall states and they agree with analytical predictions.

  14. On-Chip Microwave Quantum Hall Circulator

    Directory of Open Access Journals (Sweden)

    A. C. Mahoney


    Full Text Available Circulators are nonreciprocal circuit elements that are integral to technologies including radar systems, microwave communication transceivers, and the readout of quantum information devices. Their nonreciprocity arises from the interference of microwaves over the centimeter scale of the signal wavelength, in the presence of bulky magnetic media that breaks time-reversal symmetry. Here, we realize a completely passive on-chip microwave circulator with size 1/1000th the wavelength by exploiting the chiral, “slow-light” response of a two-dimensional electron gas in the quantum Hall regime. For an integrated GaAs device with 330  μm diameter and about 1-GHz center frequency, a nonreciprocity of 25 dB is observed over a 50-MHz bandwidth. Furthermore, the nonreciprocity can be dynamically tuned by varying the voltage at the port, an aspect that may enable reconfigurable passive routing of microwave signals on chip.

  15. Layered quantum Hall insulators with ultracold atoms

    Energy Technology Data Exchange (ETDEWEB)

    Zamora, A. [ICFO-Institut de Ciencies Fotoniques, Av. Carl Friedrich Gauss 3, E-08860 Castelldefels (Barcelona) (Spain); Szirmai, G. [ICFO-Institut de Ciencies Fotoniques, Av. Carl Friedrich Gauss 3, E-08860 Castelldefels (Barcelona) (Spain); Research Institute for Solid State Physics and Optics, P.O. Box 49, H-1525 Budapest (Hungary); Lewenstein, M. [ICFO-Institut de Ciencies Fotoniques, Av. Carl Friedrich Gauss 3, E-08860 Castelldefels (Barcelona) (Spain); ICREA-Institucio Catalana de Recerca i Estudis Avancats, Passeig Lluis Companys 23, E-08010 Barcelona (Spain)


    We consider a generalization of the two-dimensional (2D) quantum Hall insulator to a noncompact, non-Abelian gauge group, the Heisenberg-Weyl group. We show that this kind of insulator is actually a layered three-dimensional (3D) insulator with nontrivial topology. We further show that nontrivial combinations of quantized transverse conductivities can be engineered with the help of a staggered potential. We investigate the robustness and topological nature of this conductivity and connect it to the surface modes of the system. We also propose a simple experimental realization with ultracold atoms in 3D confined to a 2D square lattice with the third dimension being mapped to a gauge coordinate.

  16. Magnetic circuit for hall effect plasma accelerator (United States)

    Manzella, David H. (Inventor); Jacobson, David T. (Inventor); Jankovsky, Robert S. (Inventor); Hofer, Richard (Inventor); Peterson, Peter (Inventor)


    A Hall effect plasma accelerator includes inner and outer electromagnets, circumferentially surrounding the inner electromagnet along a thruster centerline axis and separated therefrom, inner and outer magnetic conductors, in physical connection with their respective inner and outer electromagnets, with the inner magnetic conductor having a mostly circular shape and the outer magnetic conductor having a mostly annular shape, a discharge chamber, located between the inner and outer magnetic conductors, a magnetically conducting back plate, in magnetic contact with the inner and outer magnetic conductors, and a combined anode electrode/gaseous propellant distributor, located at a bottom portion of the discharge chamber. The inner and outer electromagnets, the inner and outer magnetic conductors and the magnetically conducting back plate form a magnetic circuit that produces a magnetic field that is largely axial and radially symmetric with respect to the thruster centerline.

  17. Quantum Hall Effect in Hydrogenated Graphene (United States)

    Guillemette, J.; Sabri, S. S.; Wu, Binxin; Bennaceur, K.; Gaskell, P. E.; Savard, M.; Lévesque, P. L.; Mahvash, F.; Guermoune, A.; Siaj, M.; Martel, R.; Szkopek, T.; Gervais, G.


    The quantum Hall effect is observed in a two-dimensional electron gas formed in millimeter-scale hydrogenated graphene, with a mobility less than 10cm2/V·s and corresponding Ioffe-Regel disorder parameter (kFλ)-1≫1. In a zero magnetic field and low temperatures, the hydrogenated graphene is insulating with a two-point resistance of the order of 250h/e2. The application of a strong magnetic field generates a negative colossal magnetoresistance, with the two-point resistance saturating within 0.5% of h/2e2 at 45 T. Our observations are consistent with the opening of an impurity-induced gap in the density of states of graphene. The interplay between electron localization by defect scattering and magnetic confinement in two-dimensional atomic crystals is discussed.

  18. The Hall Technique 10 years on: Questions and answers. (United States)

    Innes, N P T; Evans, D J P; Bonifacio, C C; Geneser, M; Hesse, D; Heimer, M; Kanellis, M; Machiulskiene, V; Narbutaité, J; Olegário, I C; Owais, A; Araujo, M P; Raggio, D P; Splieth, C; van Amerongen, E; Weber-Gasparoni, K; Santamaria, R M


    It is ten years since the first paper on the Hall Technique was published in the British Dental Journal and almost 20 years since the technique first came to notice. Dr Norna Hall a (now retired) general dental practitioner from the north of Scotland had, for many years, been managing carious primary molar teeth by cementing preformed metal crowns over them, with no local anaesthesia, tooth preparation or carious tissue removal. This first report, a retrospective analysis of Dr Hall's treatments, caused controversy. How could simply sealing a carious lesion, with all the associated bacteria and decayed tissues, possibly be clinically successful? Since then, growing understanding that caries is essentially a biofilm driven disease rather than an infectious disease, explains why the Hall Technique, and other 'sealing in' carious lesion techniques, are successful. The intervening ten years has seen robust evidence from several randomised control trials that are either completed or underway. These have found the Hall Technique superior to comparator treatments, with success rates (no pain or infection) of 99% (UK study) and 100% (Germany) at one year, 98% and 93% over two years (UK and Germany) and 97% over five years (UK). The Hall Technique is now regarded as one of several biological management options for carious lesions in primary molars. This paper covers commonly asked questions about the Hall Technique and speculates on what lies ahead.

  19. Feasibility of ultra-sensitive 2D layered Hall elements (United States)

    Joo, Min-Kyu; Kim, Joonggyu; Lee, Gwanmu; Kim, Hyun; Lee, Young Hee; Suh, Dongseok


    A Hall effect sensor is an analog transducer that detects a magnetic flux. The general requirements for its high magnetic sensitivity in conventional semiconductors are high carrier mobility and ultra-thin conduction channel in the material’s and the device’s point of view. Recently, graphene Hall elements (GHEs) that satisfy those conditions have been demonstrated with a current-normalized magnetic sensitivity (S I) superior to that of Si-based Hall sensors. Nevertheless, the feasibility of Hall elements based on an atomically thin monolayer transition metal dichalcogenide (TMD) system has not been studied thus far, although such a system would further enable a largely suppressed 2D carrier density. Herein, we show the strategy how to achieve the highest possible S I in a TMD-based Hall element in terms of the device structure as well as the operating bias condition. A monolayer molybdenum disulfide Hall element (MHE) on a hexagonal boron nitride (h-BN) thin film was fabricated, and the best bias conditions were selected based on the analytical model for zero-field transconductance data. Finally, the maximum S I of MHE/h-BN was found to be ~3000 V/AT. This work sheds light on the feasibility of TMD-based Hall element systems.

  20. Sensitivity of resistive and Hall measurements to local inhomogeneities

    DEFF Research Database (Denmark)

    Koon, Daniel W.; Wang, Fei; Petersen, Dirch Hjorth


    We derive exact, analytic expressions for the sensitivity of sheet resistance and Hall sheet resistance measurements to local inhomogeneities for the cases of nonzero magnetic fields, strong perturbations, and perturbations over a finite area, extending our earlier results on weak perturbations. We...... express these sensitivities for conductance tensor components and for other charge transport quantities. Both resistive and Hall sensitivities, for a van der Pauw specimen in a finite magnetic field, are a superposition of the zero-field sensitivities to both sheet resistance and Hall sheet resistance...

  1. Effective Field Theory of Fractional Quantized Hall Nematics

    Energy Technology Data Exchange (ETDEWEB)

    Mulligan, Michael; /MIT, LNS; Nayak, Chetan; /Station Q, UCSB; Kachru, Shamit; /Stanford U., Phys. Dept. /SLAC


    We present a Landau-Ginzburg theory for a fractional quantized Hall nematic state and the transition to it from an isotropic fractional quantum Hall state. This justifies Lifshitz-Chern-Simons theory - which is shown to be its dual - on a more microscopic basis and enables us to compute a ground state wave function in the symmetry-broken phase. In such a state of matter, the Hall resistance remains quantized while the longitudinal DC resistivity due to thermally-excited quasiparticles is anisotropic. We interpret recent experiments at Landau level filling factor {nu} = 7/3 in terms of our theory.

  2. Anomalous Hall effect in Fe/Gd bilayers

    KAUST Repository

    Xu, W. J.


    Non-monotonic dependence of anomalous Hall resistivity on temperature and magnetization, including a sign change, was observed in Fe/Gd bilayers. To understand the intriguing observations, we fabricated the Fe/Gd bilayers and single layers of Fe and Gd simultaneously. The temperature and field dependences of longitudinal resistivity, Hall resistivity and magnetization in these films have also been carefully measured. The analysis of these data reveals that these intriguing features are due to the opposite signs of Hall resistivity/or spin polarization and different Curie temperatures of Fe and Gd single-layer films. Copyright (C) EPLA, 2010

  3. Signal conditioning and processing for metallic Hall sensors.

    Czech Academy of Sciences Publication Activity Database

    Entler, Slavomír; Ďuran, Ivan; Sládek, P.; Vayakis, G.; Kočan, M.


    Roč. 123, November (2017), s. 783-786 ISSN 0920-3796. [SOFT 2016: Symposium on Fusion Technology /29./. Prague, 05.09.2016-09.09.2016] R&D Projects: GA MŠk LG14002 Institutional support: RVO:61389021 Keywords : Hall sensor * Lock-in * Synchronous detection * Current spinning * Hall effect * Planar hall effect suppression Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.319, year: 2016

  4. TCC2, the target hall of the SPS North Area

    CERN Multimedia


    In the foreground can be seen the three proton beam branches leading to the targets enclosed in an assembly of iron blocks with the positioning mechanism on top. In the background, the six secondary beams lead off towards the experimental areas, H2/P2, H4/E4/P4 (from T2 via TT81) and H6, H8 (from T4 via TT82) towards the hall EHN1, M2 from T6 via TT83 towards the hall EHN2. The development proton beam line P0 leads off from T4 via TT83 towards TCC8 and hall ECN3 (NAHIF).

  5. Benchmark experiments on neutron streaming through JET Torus Hall penetrations (United States)

    Batistoni, P.; Conroy, S.; Lilley, S.; Naish, J.; Obryk, B.; Popovichev, S.; Stamatelatos, I.; Syme, B.; Vasilopoulou, T.; contributors, JET


    Neutronics experiments are performed at JET for validating in a real fusion environment the neutronics codes and nuclear data applied in ITER nuclear analyses. In particular, the neutron fluence through the penetrations of the JET torus hall is measured and compared with calculations to assess the capability of state-of-art numerical tools to correctly predict the radiation streaming in the ITER biological shield penetrations up to large distances from the neutron source, in large and complex geometries. Neutron streaming experiments started in 2012 when several hundreds of very sensitive thermo-luminescence detectors (TLDs), enriched to different levels in 6LiF/7LiF, were used to measure the neutron and gamma dose separately. Lessons learnt from this first experiment led to significant improvements in the experimental arrangements to reduce the effects due to directional neutron source and self-shielding of TLDs. Here we report the results of measurements performed during the 2013-2014 JET campaign. Data from new positions, at further locations in the South West labyrinth and down to the Torus Hall basement through the air duct chimney, were obtained up to about a 40 m distance from the plasma neutron source. In order to avoid interference between TLDs due to self-shielding effects, only TLDs containing natural Lithium and 99.97% 7Li were used. All TLDs were located in the centre of large polyethylene (PE) moderators, with natLi and 7Li crystals evenly arranged within two PE containers, one in horizontal and the other in vertical orientation, to investigate the shadowing effect in the directional neutron field. All TLDs were calibrated in the quantities of air kerma and neutron fluence. This improved experimental arrangement led to reduced statistical spread in the experimental data. The Monte Carlo N-Particle (MCNP) code was used to calculate the air kerma due to neutrons and the neutron fluence at detector positions, using a JET model validated up to the

  6. Are health sciences students who sit at the back of the lecture hall not motivated?

    Directory of Open Access Journals (Sweden)

    Sébastien Uffler

    Full Text Available Motivation is a crucial determinant in learning and performance. It would therefore be advantageous for teachers to use strategies intended to have a positive effect on their students' motivation. With this in mind, the first thing to do is to identify students with motivation problems, which can be a complex exercise when there are large groups. We wanted to explore whether the place chosen by health sciences students in a classroom or lecture hall showed any correlation with their motivation.We carried out a multicentre, prospective, observational study of 596 health sciences students in 9 training institutes. The students filled in a self-administered questionnaire to measure the different components of their motivation to take part in a mandatory lesson. These components were correlated with the row in which they sat in a classroom or lecture hall, when they had a free choice of where to sit.Apart from extrinsic motivation, all the components of motivation for the health sciences students recruited were significantly correlated with the row. The further the students were from the first row, the less they were motivated.In accordance with teachers' views, the level of motivation of the students was less the further their position in a classroom or lecture hall was from the first row. A student's position in the classroom could provide a useful indicator for teachers looking to target their motivational strategies for students with potential motivation problems in the environment, where identifying student motivation levels is impossible.

  7. Are health sciences students who sit at the back of the lecture hall not motivated? (United States)

    Uffler, Sébastien; Bartier, Jean-Claude; Pelaccia, Thierry


    Motivation is a crucial determinant in learning and performance. It would therefore be advantageous for teachers to use strategies intended to have a positive effect on their students' motivation. With this in mind, the first thing to do is to identify students with motivation problems, which can be a complex exercise when there are large groups. We wanted to explore whether the place chosen by health sciences students in a classroom or lecture hall showed any correlation with their motivation. We carried out a multicentre, prospective, observational study of 596 health sciences students in 9 training institutes. The students filled in a self-administered questionnaire to measure the different components of their motivation to take part in a mandatory lesson. These components were correlated with the row in which they sat in a classroom or lecture hall, when they had a free choice of where to sit. Apart from extrinsic motivation, all the components of motivation for the health sciences students recruited were significantly correlated with the row. The further the students were from the first row, the less they were motivated. In accordance with teachers' views, the level of motivation of the students was less the further their position in a classroom or lecture hall was from the first row. A student's position in the classroom could provide a useful indicator for teachers looking to target their motivational strategies for students with potential motivation problems in the environment, where identifying student motivation levels is impossible.

  8. From University Heights to Cooperstown: Halls of Fame and American Memory (United States)

    Friss, Evan J.


    This article examines the development and function of American halls of fame as cultural memory institutions. By comparing the Hall of Fame for Great Americans with the National Baseball Hall of Fame, the author posits that halls of fame illuminate the ways in which cultural memory institutions can, through an archival process, preserve, instill,…

  9. Magnesium Hall Thruster for Solar System Exploration Project (United States)

    National Aeronautics and Space Administration — The innovation being developed in this program is a Mg Hall Effect Thruster system that would open the door for In-Situ Resource Utilization based solar system...

  10. High Throughput Hall Thruster for Small Spacecraft Project (United States)

    National Aeronautics and Space Administration — Busek is developing a high throughput nominal 100-W Hall Effect Thruster. This device is well sized for spacecraft ranging in size from several tens of kilograms to...

  11. High Throughput Hall Thruster for Small Spacecraft Project (United States)

    National Aeronautics and Space Administration — Busek Co. Inc. proposes to develop a high throughput, nominal 100 W Hall Effect Thruster (HET). This HET will be sized for small spacecraft (< 180 kg), including...

  12. Pragmatic data fusion uncertainty concerns: Tribute to Dave L. Hall

    CSIR Research Space (South Africa)

    Blasch, E


    Full Text Available Over the course of Dave Hall's career, he highlighted various concerns associated with the implementation of data fusion methods. Many of the issues included the role of uncertainty in data fusion, practical implementation of sensor fusion systems...

  13. High Input Voltage Hall Thruster Discharge Converter Project (United States)

    National Aeronautics and Space Administration — The overall scope of this Phase I/II effort is the development of a high efficiency 15kW (nominal) Hall thruster discharge converter. In Phase I, Busek Co. Inc. will...

  14. Recent concert halls and opera house in Japan (United States)

    Hidaka, Takayuki


    Since we invited Dr. Beranek to Japan for the first time in 1989, we had been working together with him for a period of 13 years, until 2001, on seven hall projects as acoustic design consultants. All of these halls are of premium importance to Japan. Dr. Beranek always came up with innovative concepts and helped create halls endowed with high acoustic originality. These halls are now loved by music-related people and music fanciers and regarded as the pride of Japan. The reviews and studies achieved through these projects were published as seven J. Acoust Soc. Am papers to disclose the outcome in an objective way to the public. A brief outline of the history of our collaboration and its background are presented.

  15. Quantum Theory of Conducting Matter Superconductivity and Quantum Hall Effect

    CERN Document Server

    Fujita, Shigeji; Godoy, Salvador


    Explains major superconducting properties including zero resistance, Meissner effect, sharp phase change, flux quantization, excitation energy gap, and Josephson effects using quantum statistical mechanical calculations. This book covers the 2D superconductivity and the quantum Hall effects

  16. Investigating Anisotropic Quantum Hall States with Bimetric Geometry (United States)

    Gromov, Andrey; Geraedts, Scott D.; Bradlyn, Barry


    We construct a low energy effective theory of anisotropic fractional quantum Hall (FQH) states. We develop a formalism similar to that used in the bimetric approach to massive gravity, and apply it to describe Abelian anisotropic FQH states in the presence of external electromagnetic and geometric backgrounds. We derive a relationship between the shift, the Hall viscosity, and a new quantized coupling to anisotropy, which we term anisospin. We verify this relationship by numerically computing the Hall viscosity for a variety of anisotropic quantum Hall states using the density matrix renormalization group. Finally, we apply these techniques to the problem of nematic order and clarify certain disagreements that exist in the literature about the meaning of the coefficient of the Berry phase term in the nematic effective action.

  17. A High Performance Cathode Heater for Hall Thrusters Project (United States)

    National Aeronautics and Space Administration — High current hollow cathodes are the baseline electron source for next generation high power Hall thrusters. Currently for electron sources providing current levels...

  18. Quantized anomalous Hall effect in magnetic topological insulators. (United States)

    Yu, Rui; Zhang, Wei; Zhang, Hai-Jun; Zhang, Shou-Cheng; Dai, Xi; Fang, Zhong


    The anomalous Hall effect is a fundamental transport process in solids arising from the spin-orbit coupling. In a quantum anomalous Hall insulator, spontaneous magnetic moments and spin-orbit coupling combine to give rise to a topologically nontrivial electronic structure, leading to the quantized Hall effect without an external magnetic field. Based on first-principles calculations, we predict that the tetradymite semiconductors Bi2Te3, Bi2Se3, and Sb2Te3 form magnetically ordered insulators when doped with transition metal elements (Cr or Fe), in contrast to conventional dilute magnetic semiconductors where free carriers are necessary to mediate the magnetic coupling. In two-dimensional thin films, this magnetic order gives rise to a topological electronic structure characterized by a finite Chern number, with the Hall conductance quantized in units of e2/h (where e is the charge of an electron and h is Planck's constant).

  19. Magnesium Hall Thruster for Solar System Exploration Project (United States)

    National Aeronautics and Space Administration — Busek proposes to prove the feasibility of a Mg Hall effect thruster system that would open the door for In-Situ Resource Utilization (ISRU) based solar system...

  20. Positive operator valued measures and the quantum Monty Hall problem

    Directory of Open Access Journals (Sweden)

    Claudia Zander


    Full Text Available A quantum version of the Monty Hall problem, based upon the Positive Operator Valued Measures (POVM formalism, is proposed. It is shown that basic normalization and symmetry arguments lead univocally to the associated POVM elements, and that the classical probabilities associated with the Monty Hall scenario are recovered for a natural choice of the measurement operators.Uma visão quântica do problema Monty Hall é proposta baseada no formalismo das Medidas Avaliadas do Operador Positivo (POVM. Demonstra-se que os argumentos de normalização básica e simetria levam de maneira inequívoca para elementos associados a POVM e que as probabilidades clássicas associadas ao cenário Monty Hall são recuperadas para uma escolha natural de medidas operadoras.

  1. Survey of the Fermilab D0 detector collision hall

    Energy Technology Data Exchange (ETDEWEB)

    Babatunde O' Sheg Oshinowo


    The Fermilab D0 detector was used for the discovery of the top quark during Run I in 1996. It had been upgraded to exploit the physics potential to be presented by the Main Injector and the Tevatron Collider during Run II. The upgrade of the D0 detector was fully commissioned on March 1, 2001, and thus marked the official start of the Run II experiment. The detector which weighs about 5500 tons, was assembled in the Assembly Hall. Prior to moving the detector into the Collision Hall, the existing survey monuments were densified in the Collision Hall with new monuments. This paper discusses the survey of the Collision Hall using a combination of the Laser Tracker, BETS, V-Stars, and other Optical systems to within the specified accuracy of {+-}0.5mm.

  2. Hall Mobility of Amorphous Ge2Sb2Te5

    National Research Council Canada - National Science Library

    Baily, S. A; Emin, David; Li, Heng


    The electrical conductivity, Seebeck coefficient, and Hall coefficient of 3 micron thick films of amorphous Ge2Sb2Te5 have been measured as functions of temperature from room temperature down to as low as 200 K...

  3. Acoustics in Halls for Speech and Music (United States)

    Gade, Anders C.

    This chapter deals specifically with concepts, tools, and architectural variables of importance when designing auditoria for speech and music. The focus will be on cultivating the useful components of the sound in the room rather than on avoiding noise from outside or from installations, which is dealt with in Chap. 11. The chapter starts by presenting the subjective aspects of the room acoustic experience according to consensus at the time of writing. Then follows a description of their objective counterparts, the objective room acoustic parameters, among which the classical reverberation time measure is only one of many, but still of fundamental value. After explanations on how these parameters can be measured and predicted during the design phase, the remainder of the chapter deals with how the acoustic properties can be controlled by the architectural design of auditoria. This is done by presenting the influence of individual design elements as well as brief descriptions of halls designed for specific purposes, such as drama, opera, and symphonic concerts. Finally, some important aspects of loudspeaker installations in auditoria are briefly touched upon.

  4. Quantum Spin Hall phase in multilayer graphene (United States)

    Garcia, Noel; Lado, Jose Luis; Fernandez-Rossier, Joaquin; Theory of Nanostructures Team


    We address the question of whether multilayer graphene systems are Quantum Spin Hall (QSH) insulators. Since interlayer coupling coples pz orbitals to s orbitals of different layers and Spin-Orbit (SO) couples pz orbitals with px and py of opposite spins, new spins mixing channels appear in the multilayer scenario that were not present in the monolayer. These new spin-mixing channels cast a doubt on the validity of the spin-conserving Kane-Mele model for multilayers and motivates our choice of a four orbital tight-binding model in the Slater-Koster approximation with intrinsic Spin-Orbit interaction. To completely determine if the QSH phase is present we calculate for different number of layers both the Z2 invariant for different stackings (only for inversion symmetric systems), and the density of states at the edge of semi-infinite graphene ribbon with armchair termination. We find that systems with even number of layers are normal insulators while systems with odd number of layers are QSH insulators, regardless of the stacking. We acknowledge financial support by Marie-Curie-ITN 607904-SPINOGRAPH.

  5. The integer quantum hall effect revisited

    Energy Technology Data Exchange (ETDEWEB)

    Michalakis, Spyridon [Los Alamos National Laboratory; Hastings, Matthew [Q STATION, CALIFORNIA


    For T - L x L a finite subset of Z{sup 2}, let H{sub o} denote a Hamiltonian on T with periodic boundary conditions and finite range, finite strength intetactions and a unique ground state with a nonvanishing spectral gap. For S {element_of} T, let q{sub s} denote the charge at site s and assume that the total charge Q = {Sigma}{sub s {element_of} T} q{sub s} is conserved. Using the local charge operators q{sub s}, we introduce a boundary magnetic flux in the horizontal and vertical direction and allow the ground state to evolve quasiadiabatically around a square of size one magnetic flux, in flux space. At the end of the evolution we obtain a trivial Berry phase, which we compare, via a method reminiscent of Stokes Theorem. to the Berry phase obtained from an evolution around an exponentially small loop near the origin. As a result, we show, without any averaging assumption, that the Hall conductance is quantized in integer multiples of e{sup 2}/h up to exponentially small corrections of order e{sup -L/{zeta}}, where {zeta}, is a correlation length that depends only on the gap and the range and strength of the interactions.

  6. Brand new hall in the main building

    CERN Multimedia

    Corinne Pralavorio


    The renovation of the UNIQA and post office premises is getting under way, with their reopening scheduled for the spring.   The renovation of the large hall in the main building (Building 500) has finally reached the home straight. As of this week, building contractors will get to work on the last part – the offices of UNIQA and La Poste. In the last week of November, the two concessions moved their offices across Route Scherrer to the same part of Building 510 where UBS was temporarily housed during the bank’s refurbishment. Their services were therefore unavailable for one day. The renovation work will last until the spring, with the new offices expected to open in May 2015. Between now and then, the windows and insulation will be completely refitted, with a view to reducing heat loss considerably, and, above all, the premises will be modernised to improve customer reception and service. For example, UNIQA’s new premises will feature a confidential area, guarantee...

  7. Supersymmetry in the fractional quantum Hall regime (United States)

    Sagi, Eran; Santos, Raul A.


    Supersymmetry (SUSY) is a symmetry transforming bosons to fermions and vice versa. Indications of its existence have been extensively sought after in high-energy experiments. However, signatures of SUSY have yet to be detected. In this paper we study a condensed matter realization of SUSY on the edge of a Read-Rezayi quantum Hall state, given by filling factors of the form ν =k/k +2 , where k is an integer. As we show explicitly, this strongly interacting state exhibits an N =2 SUSY. This allows us to use a topological invariant—the Witten index—defined specifically for supersymmetric theories, to count the difference between the number of bosonic and fermionic zero modes in a circular edge. In this system, we argue that the edge hosts k +1 protected zero modes. We further discuss the stability of SUSY with respect to generic perturbations and find that much of the above results remain unchanged. In particular, these results directly apply to the well-established ν =1 /3 Laughlin state, in which case SUSY is a robust property of the edge theory. These results unveil a hidden topological structure on the long-studied Read-Rezayi states.

  8. Low-Cost, High-Performance Hall Thruster Support System (United States)

    Hesterman, Bryce


    Colorado Power Electronics (CPE) has built an innovative modular PPU for Hall thrusters, including discharge, magnet, heater and keeper supplies, and an interface module. This high-performance PPU offers resonant circuit topologies, magnetics design, modularity, and a stable and sustained operation during severe Hall effect thruster current oscillations. Laboratory testing has demonstrated discharge module efficiency of 96 percent, which is considerably higher than current state of the art.

  9. What is the Hallé? | Smith | Philosophical Papers

    African Journals Online (AJOL)

    I address what I call 'the number issue', which is raised by our ordinary talk and beliefs about certain social groups and institutions, and I take the Hallé orchestra as my example. The number issue is that of whether the Hallé is one individual or several individuals. I observe that if one holds that it is one individual, one faces ...

  10. Pseudospectral Model for Hybrid PIC Hall-effect Thruster Simulation (United States)


    Paper 3. DATES COVERED (From - To) July 2015-July 2015 4. TITLE AND SUBTITLE Pseudospectral model for hybrid PIC Hall-effect thruster simulationect...of a pseudospectral azimuthal-axial hybrid- PIC HET code which is designed to explicitly resolve and filter azimuthal fluctuations in the...661-275-5908 Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std. 239.18 Pseudospectral model for hybrid PIC Hall-effect thruster simulation IEPC

  11. High-performance LED luminaire for sports hall (United States)

    Lee, Xuan-Hao; Yang, Jin-Tsung; Chien, Wei-Ting; Chang, Jung-Hsuan; Lo, Yi-Chien; Lin, Che-Chu; Sun, Ching-Cherng


    In this paper, we present a luminaire design with anti-glare and energy-saving effects for sports hall. Compared with traditional lamps using in a badminton court, the average illuminance on the ground of the proposed LED luminaire is enhanced about 300%. Besides, the uniformity is obviously enhanced and improved. The switch-on speed of lighting in sports hall is greatly reduced from 5-10 minutes to 1 second. The simulation analysis and the corresponding experiment results are demonstrated.

  12. Quantum Hall Mach-Zehnder interferometer at fractional filling factors


    Deviatov, E. V.; Egorov, S. V.; Biasiol, G.; Sorba, L.


    We use a Mach-Zehnder quantum Hall interferometer of a novel design to investigate the interference effects at fractional filling factors. Our device brings together the advantages of usual Mach-Zehnder and Fabry-Perot quantum Hall interferometers. It realizes the simplest-for-analysis Mach-Zehnder interference scheme, free from Coulomb blockade effects. By contrast to the standard Mach-Zehnder realization, our device does not contain an etched region inside the interference loop. For the fir...

  13. Hall effect in amorphous calcium-aluminum alloys (United States)

    Mayeya, F. M.; Howson, M. A.


    We present results of the Hall effect measurements in CaAl(Au) amorphous alloys. The Hall coefficients have been found to be negative and independent of temperature. Their magnitudes deviate significantly from the nearly-free-electron calculations, and are reduced by gold doping. These deviations have been accounted for from considerations of the unusual electronic structure of CaAl, and the effects of both s-d hybridization and side-jump mechanism on the conduction electrons.

  14. Stainless Steel Crown Placement Utilizing the Hall Technique (United States)



  15. Tunnelling anomalous and planar Hall effects (Conference Presentation) (United States)

    Matos-Abiague, Alex; Scharf, Benedikt; Han, Jong E.; Hankiewicz, Ewelina M.; Zutic, Igor


    We theoretically show how the interplay between spin-orbit coupling (SOC) and magnetism can result in a finite tunneling Hall conductance, transverse to the applied bias. For two-dimensional tunnel junctions with a ferromagnetic lead and magnetization perpendicular to the current flow, the detected anomalous Hall voltage can be used to extract information not only about the spin polarization but also about the strength of the interfacial SOC. In contrast, a tunneling current across a ferromagnetic barrier on the surface of a three-dimensional topological insulator (TI) can induce a planar Hall response even when the magnetization is oriented along the current flow[1]. The tunneling nature of the states contributing to the planar Hall conductance can be switched from the ordinary to the Klein regimes by the electrostatic control of the barrier strength. This allows for an enhancement of the transverse response and a giant Hall angle, with the tunneling planar Hall conductance exceeding the longitudinal component. Despite the simplicity of a single ferromagnetic region, the TI/ferromagnet system exhibits a variety of functionalities. In addition to a spin-valve operation for magnetic sensing and storing information, positive, negative, and negative differential conductances can be tuned by properly adjusting the barrier potential and/or varying the magnetization direction. Such different resistive behaviors in the same system are attractive for potential applications in reconfigurable spintronic devices. [1] B. Scharf, A. Matos-Abiague, J. E. Han, E. M. Hankiewicz, and I. Zutic, arXiv:1601.01009 (2016).

  16. Arsenic complexes optical signatures in As-doped HgCdTe

    Energy Technology Data Exchange (ETDEWEB)

    Gemain, F.; Robin, I. C.; Brochen, S.; Ballet, P.; Gravrand, O.; Feuillet, G. [CEA-LETI Minatec Campus, 17 rue des Martyrs, 38000 Grenoble (France)


    In this paper, the optical signatures of arsenic complexes in As-doped HgCdTe samples grown by molecular beam epitaxy are clearly identified using comparison between photoluminescence spectra, Extended X-Ray Absorption Fine Structure, and Hall measurements. The ionization energies of the different complexes are measured both by photoluminescence and Hall measurements.

  17. Mode Transitions in Hall Effect Thrusters (United States)

    Sekerak, Michael J.; Longmier, Benjamin W.; Gallimore, Alec D.; Brown, Daniel L.; Hofer, Richard R.; Polk, James E.


    Mode transitions have been commonly observed in Hall Effect Thruster (HET) operation where a small change in a thruster operating parameter such as discharge voltage, magnetic field or mass flow rate causes the thruster discharge current mean value and oscillation amplitude to increase significantly. Mode transitions in a 6-kW-class HET called the H6 are induced by varying the magnetic field intensity while holding all other operating parameters constant and measurements are acquired with ion saturation probes and ultra-fast imaging. Global and local oscillation modes are identified. In the global mode, the entire discharge channel oscillates in unison and azimuthal perturbations (spokes) are either absent or negligible. Downstream azimuthally spaced probes show no signal delay between each other and are very well correlated to the discharge current signal. In the local mode, signals from the azimuthally spaced probes exhibit a clear delay indicating the passage of "spokes" and are not well correlated to the discharge current. These spokes are localized oscillations propagating in the ExB direction that are typically 10-20% of the mean value. In contrast, the oscillations in the global mode can be 100% of the mean value. The transition between global and local modes occurs at higher relative magnetic field strengths for higher mass flow rates or higher discharge voltages. The thrust is constant through mode transition but the thrust-to-power decreased by 25% due to increasing discharge current. The plume shows significant differences between modes with the global mode significantly brighter in the channel and the near-field plasma plume as well as exhibiting a luminous spike on thruster centerline. Mode transitions provide valuable insight to thruster operation and suggest improved methods for thruster performance characterization.

  18. Seville City Hall Chapter Room ceiling decoration

    Directory of Open Access Journals (Sweden)

    Robador, M. D.


    Full Text Available The present article describes a chemical and physical study of the colour, chemical composition and mineral phases of the decorative materials in the Seville City Hall Chapter House ceiling. The findings showed that the inner most layer of material, calcite, was covered with white lead, in turn concealed under a layer of gilded bole. The ceiling underwent re-gilding, also over bole, due in all likelihood to wear on the original gold leaf. In the nineteenth century, the entire ceiling with the exception of the inscriptions was whitewashed with calcite and white lead. Silver was employed on King John I’s sword (coffer 27. Gold leaf was used to adorn the royal attributes: crowns, belts, sceptres, swords and rosary beads. The high reliefs were likewise gilded. The pigments identified on the ceiling adornments included azurite, malachite, vermilion and gas black. A lime and ground dolomite mortar was used throughout.

    El objetivo de este trabajo es el estudio de diferentes aspectos, como el color, la composición química y las fases mineralógicas presentes en los diferentes materiales que forman la ornamentación del techo de la Sala Capitular del Ayuntamiento de Sevilla, mediante métodos físicos y químicos. Nuestros resultados muestran que el dorado fue realizado sobre una capa de bol previamente depositada sobre una lámina de blanco de plomo que cubría un estrato de calcita. Posteriormente, y probablemente debido a alteraciones en el dorado original, el techo fue de nuevo dorado usando una técnica similar. En el siglo XIX, casi todo el techo, excepto las zonas con inscripciones, fue blanqueado usando una mezcla de calcita y blanco de plomo. Se empleó plata para cubrir la espada del rey Juan I (casetón 27. Finísimas láminas de oro se usaron para decorar los atributos reales: coronas, cinturones, cetros, espadas y rosarios. En diferentes partes de la decoración fueron detectados pigmentos como azurita, malaquita, bermellón y

  19. Concert hall acoustics assessment with individually elicited attributes. (United States)

    Lokki, Tapio; Patynen, Jukka; Kuusinen, Antti; Vertanen, Heikki; Tervo, Sakari


    Concert hall acoustics was evaluated with a descriptive sensory analysis method by employing an individual vocabulary development technique. The goal was to obtain sensory profiles of three concert halls by eliciting perceptual attributes for evaluation and comparison of the halls. The stimuli were gathered by playing back anechoic symphony music from 34 loudspeakers on stage in each concert hall and recording the sound field with a microphone array. Four musical programs were processed for multichannel 3D sound reproduction in the actual listening test. Twenty screened assessors developed their individual set of attributes and performed a comparative evaluation of nine seats, three in each hall. The results contain the distinctive groups of elicited attributes and show good agreement within assessors, even though they applied individual attributes when rating the samples. It was also found that loudness and distance gave the strongest perceptual direction to the principal component basis. In addition, the study revealed that the perception of reverberance is related to the size of the space or to the enveloping reverberance, depending on the assessor.

  20. Perception of music dynamics in concert hall acoustics. (United States)

    Pätynen, Jukka; Lokki, Tapio


    Dynamics is one of the principal means of expressivity in Western classical music. Still, preceding research on room acoustics has mostly neglected the contribution of music dynamics to the acoustic perception. This study investigates how the different concert hall acoustics influence the perception of varying music dynamics. An anechoic orchestra signal, containing a step in music dynamics, was rendered in the measured acoustics of six concert halls at three seats in each. Spatial sound was reproduced through a loudspeaker array. By paired comparison, naive subjects selected the stimuli that they considered to change more during the music. Furthermore, the subjects described their foremost perceptual criteria for each selection. The most distinct perceptual factors differentiating the rendering of music dynamics between halls include the dynamic range, and varying width of sound and reverberance. The results confirm the hypothesis that the concert halls render the performed music dynamics differently, and with various perceptual aspects. The analysis against objective room acoustic parameters suggests that the perceived dynamic contrasts are pronounced by acoustics that provide stronger sound and more binaural incoherence by a lateral sound field. Concert halls that enhance the dynamics have been found earlier to elicit high subjective preference.

  1. G. Stanley Hall, Child Study, and the American Public. (United States)

    Young, Jacy L


    In the final decades of the 19th century psychologist Granville Stanley Hall was among the most prominent pedagogical experts in the nation. The author explores Hall's carefully crafted persona as an educational expert, and his engagements with the American public, from 1880 to 1900, arguably the height of his influence. Drawing from accounts of Hall's lecture circuit in the popular press, a map of his talks across the nation is constructed to assess the geographic scope of his influence. These talks to educators on the psychology underlying childhood and pedagogy, and his views and research on child life more generally, were regularly discussed in newspapers and popular periodicals. The venues in which Hall's ideas were disseminated, discussed, and in some cases, dismissed are described. His efforts to mobilize popular support for, and assistance with, his research endeavors in child study are also discussed. Such efforts were controversial both within the burgeoning field of psychology and among the public. Through his various involvements in pedagogy, and concerted efforts to engage with the American public, Hall helped establish psychology's relevance to parenting and educational practices.

  2. Suitable reverberation times for halls for rock and pop music. (United States)

    Adelman-Larsen, Niels Werner; Thompson, Eric R; Gade, Anders C


    The existing body of literature regarding the acoustic design of concert halls has focused almost exclusively on classical music, although there are many more performances of popular music, including rock and pop. Objective measurements were made of the acoustics of 20 rock music venues in Denmark and a questionnaire was used in a subjective assessment of those venues with professional rock musicians and sound engineers as expert listeners. Correlations between the measurements show that clarity, including bass frequencies down to 63 Hz, is important for the general impression of the acoustics of the hall. The best-rated halls in the study have reverberation times that are approximately frequency independent from 0.6 to 1.2 s for hall volumes from 1000 to 6000 m(3). The worst rated halls in the study had significantly higher reverberation times in the 63 and 125 Hz bands. Since most audiences at rock concerts are standing, absorption coefficients were measured with a standing audience from 63 Hz to 4 kHz. These measurements showed that a standing audience absorbs about five times as much energy in mid-/high-frequency bands as in low-frequency bands.

  3. Higher (odd) dimensional quantum Hall effect and extended dimensional hierarchy (United States)

    Hasebe, Kazuki


    We demonstrate dimensional ladder of higher dimensional quantum Hall effects by exploiting quantum Hall effects on arbitrary odd dimensional spheres. Non-relativistic and relativistic Landau models are analyzed on S 2 k - 1 in the SO (2 k - 1) monopole background. The total sub-band degeneracy of the odd dimensional lowest Landau level is shown to be equal to the winding number from the base-manifold S 2 k - 1 to the one-dimension higher SO (2 k) gauge group. Based on the chiral Hopf maps, we clarify the underlying quantum Nambu geometry for odd dimensional quantum Hall effect and the resulting quantum geometry is naturally embedded also in one-dimension higher quantum geometry. An origin of such dimensional ladder connecting even and odd dimensional quantum Hall effects is illuminated from a viewpoint of the spectral flow of Atiyah-Patodi-Singer index theorem in differential topology. We also present a BF topological field theory as an effective field theory in which membranes with different dimensions undergo non-trivial linking in odd dimensional space. Finally, an extended version of the dimensional hierarchy for higher dimensional quantum Hall liquids is proposed, and its relationship to quantum anomaly and D-brane physics is discussed.

  4. Diaphragm Effect of Steel Space Roof Systems in Hall Structures

    Directory of Open Access Journals (Sweden)

    Mehmet FENKLİ


    Full Text Available Hall structures have been used widely for different purposes. They have are reinforced concrete frames and shear wall with steel space roof systems. Earthquake response of hall structures is different from building type structures. One of the most critical nodes is diaphragm effect of steel space roof on earthquake response of hall structures. Diaphragm effect is depending on lateral stiffness capacity of steel space roof system. Lateral stiffness of steel space roof system is related to modulation geometry, support conditions, selected sections and system geometry. In current paper, three representative models which are commonly used in Turkey were taken in to account for investigation. Results of numerical tests were present comparatively

  5. Nonlinear analysis of magnetization dynamics excited by spin Hall effect (United States)

    Taniguchi, Tomohiro


    We investigate the possibility of exciting self-oscillation in a perpendicular ferromagnet by the spin Hall effect on the basis of a nonlinear analysis of the Landau-Lifshitz-Gilbert (LLG) equation. In the self-oscillation state, the energy supplied by the spin torque during a precession on a constant energy curve should equal the dissipation due to damping. Also, the current to balance the spin torque and the damping torque in the self-oscillation state should be larger than the critical current to destabilize the initial state. We find that these conditions in the spin Hall system are not satisfied by deriving analytical solutions of the energy supplied by the spin transfer effect and the dissipation due to the damping from the nonlinear LLG equation. This indicates that the self-oscillation of a perpendicular ferromagnet cannot be excited solely by the spin Hall torque.

  6. Stability of fractional quantum Hall states in disordered photonic systems (United States)

    DeGottardi, Wade; Hafezi, Mohammad


    The possibility of realizing fractional quantum Hall liquids in photonic systems has attracted a great deal of interest of late. Unlike electronic systems, interactions in photonic systems must be engineered from nonlinear elements and are thus subject to positional disorder. The stability of the topological liquid relies on repulsive interactions. In this paper we investigate the stability of fractional quantum Hall liquids to impurities which host attractive interactions. Employing the Bose–Hubbard model with a magnetic field, we find that for sufficiently strong attractive interactions these impurities can destroy the topological liquid. However, we find that the liquid is quite robust to these defects, a fact which bodes well for the realization of topological quantum Hall liquids in photonic systems.

  7. Composed planar Hall effect sensors with dual-mode operation

    Directory of Open Access Journals (Sweden)

    Vladislav Mor


    Full Text Available We present a composed planar Hall effect sensor with two modes of operation: (a an ON mode where the composed sensor responds to magnetic field excitations similarly to the response of a regular planar Hall effect sensor, and (b an OFF mode where the response is negligible. The composed planar Hall effect sensor switches from the OFF mode to the ON mode when it is exposed to a magnetic field which exceeds a certain threshold determined by the sensor design. The features of this sensor make it useful as a switch triggered by magnetic field and as a sensing device with memory, as its mode of operation indicates exposure to a magnetic field larger than a certain threshold without the need to be activated during the exposure itself.

  8. Quantum Hall effect in graphene with superconducting electrodes. (United States)

    Rickhaus, Peter; Weiss, Markus; Marot, Laurent; Schönenberger, Christian


    We have realized an integer quantum Hall system with superconducting contacts by connecting graphene to niobium electrodes. Below their upper critical field of 4 T, an integer quantum Hall effect coexists with superconductivity in the leads but with a plateau conductance that is larger than in the normal state. We ascribe this enhanced quantum Hall plateau conductance to Andreev processes at the graphene-superconductor interface leading to the formation of so-called Andreev edge-states. The enhancement depends strongly on the filling-factor and is less pronounced on the first plateau due to the special nature of the zero energy Landau level in monolayer graphene. © 2012 American Chemical Society

  9. Crossover between spin swapping and Hall effect in disordered systems

    KAUST Repository

    Saidaoui, Hamed Ben Mohamed


    We theoretically study the crossover between spin Hall effect and spin swapping, a recently predicted phenomenon that consists of the interchange between the current flow and its spin polarization directions [M. B. Lifshits and M. I. Dyakonov, Phys. Rev. Lett. 103, 186601 (2009)]. Using a tight-binding model with spin-orbit coupled disorder, spin Hall effect, spin relaxation, and spin swapping are treated on equal footing. We demonstrate that spin swapping and spin Hall effect present very different dependencies as a function of the spin-orbit coupling and disorder strengths and confirm that the former exceeds the latter in the parameter range considered. Three setups are proposed for the experimental observation of the spin swapping effect.

  10. Metal-to-insulator switching in quantum anomalous Hall states (United States)

    Pan, Lei; Kou, Xufeng; Wang, Jing; Fan, Yabin; Choi, Eun Sang; Shao, Qiming; Zhang, Shou Cheng; Wang, Kang Lung

    Quantum anomalous Hall effect (QAHE) was recently achieved in magnetic topological insulator films as a form of dissipationless transport without external magnetic field. However, the universal phase diagram of QAHE and its relation with quantum Hall effect (QHE) remain to be investigated. Here, we report the experimental observation of the giant longitudinal resistance peak and zero Hall conductance plateau at the coercive field in the six quintuple-layer (Cr0.12Bi0.26Sb0.62)2 Te3 film, and demonstrate the metal-to-insulator switching between two opposite QAHE plateau states up to 0.3 K. The universal QAHE phase diagram is further confirmed through the angle-dependent measurements. Our results address that the quantum phase transitions in both QAHE and QHE regimes are in the same universality class, yet the microscopic details are different.

  11. Topological Phase Transitions in the Photonic Spin Hall Effect (United States)

    Kort-Kamp, W. J. M.


    The recent synthesis of two-dimensional staggered materials opens up burgeoning opportunities to study optical spin-orbit interactions in semiconducting Dirac-like systems. We unveil topological phase transitions in the photonic spin Hall effect in the graphene family materials. It is shown that an external static electric field and a high frequency circularly polarized laser allow for active on-demand manipulation of electromagnetic beam shifts. The spin Hall effect of light presents a rich dependence with radiation degrees of freedom, and material properties, and features nontrivial topological properties. We discover that photonic Hall shifts are sensitive to spin and valley properties of the charge carriers, providing an unprecedented pathway to investigate spintronics and valleytronics in staggered 2D semiconductors.

  12. Admittance of multiterminal quantum Hall conductors at kilohertz frequencies

    Energy Technology Data Exchange (ETDEWEB)

    Hernández, C. [Departamento de Física, Universidad Militar Nueva Granada, Carrera 11 101-80 Bogotá D.C. (Colombia); Consejo, C.; Chaubet, C., E-mail: [Université Montpellier 2, Laboratoire Charles Coulomb UMR5221, F-34095 Montpellier, France and CNRS, Laboratoire Charles Coulomb UMR5221, F-34095 Montpellier (France); Degiovanni, P. [Université de Lyon, Fédération de Physique Andrée Marie Ampère, CNRS, Laboratoire de Physique de l' Ecole Normale Supérieure de Lyon, 46 allée d' Italie, 69364 Lyon Cedex 07 (France)


    We present an experimental study of the low frequency admittance of quantum Hall conductors in the [100 Hz, 1 MHz] frequency range. We show that the frequency dependence of the admittance of the sample strongly depends on the topology of the contacts connections. Our experimental results are well explained within the Christen and Büttiker approach for finite frequency transport in quantum Hall edge channels taking into account the influence of the coaxial cables capacitance. In the Hall bar geometry, we demonstrate that there exists a configuration in which the cable capacitance does not influence the admittance measurement of the sample. In this case, we measure the electrochemical capacitance of the sample and observe its dependence on the filling factor.

  13. Maximizing utilization of sport halls during peak hours

    DEFF Research Database (Denmark)

    Iversen, Evald Bundgård; Forsberg, Peter

    BACKGROUNDDuring peak hours (4.30pm-8pm) demand for timeslots in sport halls in Denmark are high and there are few timeslots available. Further, focus on how public resources are spent most efficient is increasing (Iversen, 2013). This makes it interesting to analyse how utilization could...... be increased during peak hours. DATA AND METHODOLOGYData is collected by observation of activities during two weeks on for example whether halls are used or not; the amount of playing field used; and number of participants (Iversen, 2012). Data on 1.331 activities in 36 sport halls across 4 municipalities have...... been collected. RESULTS The number of participants per activity is higher during peak hours, which is expected when demand is high. However, the usage of sport floor only differs slightly between peak and low hours. Both during peak and low hours on average 80-100 per cent of floor space is used...

  14. Carl Gustav Jung and Granville Stanley Hall on Religious Experience. (United States)

    Kim, Chae Young


    Granville Stanley Hall (1844-1924) with William James (1842-1910) is the key founder of psychology of religion movement and the first American experimental or genetic psychologist, and Carl Gustav Jung (1875-1961) is the founder of the analytical psychology concerned sympathetically about the religious dimension rooted in the human subject. Their fundamental works are mutually connected. Among other things, both Hall and Jung were deeply interested in how the study of religious experience is indispensable for the depth understanding of human subject. Nevertheless, except for the slight indication, this common interest between them has not yet been examined in academic research paper. So this paper aims to articulate preliminary evidence of affinities focusing on the locus and its function of the inner deep psychic dimension as the religious in the work of Hall and Jung.

  15. A Parametric Modelling Process for the Integration of Architecture and Structure in Large Multi-functional Sports Hall Design: a Case Study

    NARCIS (Netherlands)

    Pan, W.; Sun, Yimin; Turrin, M.; Paul, JC; Kawaguchi, K.; Ohsaki, M.; Takeuchi, T.


    The integration of architectural (functional spaces) and structural design is especially crucial for the conceptual design of large multi-functional sports halls, due to the strict regulations for functional spaces, the requirement of large-span structure, and the complex interrelationships between

  16. A topological Dirac insulator in a quantum spin Hall phase. (United States)

    Hsieh, D; Qian, D; Wray, L; Xia, Y; Hor, Y S; Cava, R J; Hasan, M Z


    When electrons are subject to a large external magnetic field, the conventional charge quantum Hall effect dictates that an electronic excitation gap is generated in the sample bulk, but metallic conduction is permitted at the boundary. Recent theoretical models suggest that certain bulk insulators with large spin-orbit interactions may also naturally support conducting topological boundary states in the quantum limit, which opens up the possibility for studying unusual quantum Hall-like phenomena in zero external magnetic fields. Bulk Bi(1-x)Sb(x) single crystals are predicted to be prime candidates for one such unusual Hall phase of matter known as the topological insulator. The hallmark of a topological insulator is the existence of metallic surface states that are higher-dimensional analogues of the edge states that characterize a quantum spin Hall insulator. In addition to its interesting boundary states, the bulk of Bi(1-x)Sb(x) is predicted to exhibit three-dimensional Dirac particles, another topic of heightened current interest following the new findings in two-dimensional graphene and charge quantum Hall fractionalization observed in pure bismuth. However, despite numerous transport and magnetic measurements on the Bi(1-x)Sb(x) family since the 1960s, no direct evidence of either topological Hall states or bulk Dirac particles has been found. Here, using incident-photon-energy-modulated angle-resolved photoemission spectroscopy (IPEM-ARPES), we report the direct observation of massive Dirac particles in the bulk of Bi(0.9)Sb(0.1), locate the Kramers points at the sample's boundary and provide a comprehensive mapping of the Dirac insulator's gapless surface electron bands. These findings taken together suggest that the observed surface state on the boundary of the bulk insulator is a realization of the 'topological metal'. They also suggest that this material has potential application in developing next-generation quantum computing devices that may

  17. Hall effect on tearing mode instabilities in tokamak (United States)

    Zhang, W.; Ma, Z. W.; Wang, S.


    The tearing mode instability is one of the most important dynamic processes in space and laboratory plasmas. Hall effects, resulting from the decoupling of electron and ion motions, can cause fast development and rotation of the perturbation structure of the tearing mode. A high-accuracy nonlinear magnetohydrodynamics code is developed to study Hall effects on the evolution of tearing modes in the Tokamak geometry. It is found that the linear growth rate increases with the increase in the ion skin depth and the self-consistently generated rotation can greatly alter the dynamic behavior of the double tearing mode.

  18. Spin Hall magnetoresistance in antiferromagnet/normal metal bilayers

    KAUST Repository

    Manchon, Aurelien


    We investigate the emergence of spin Hall magnetoresistance in a magnetic bilayer composed of a normal metal adjacent to an antiferromagnet. Based on a recently derived drift diffusion equation, we show that the resistance of the bilayer depends on the relative angle between the direction transverse to the current flow and the Néel order parameter. While this effect presents striking similarities with the spin Hall magnetoresistance recently reported in ferromagnetic bilayers, its physical origin is attributed to the anisotropic spin relaxation of itinerant spins in the antiferromagnet.

  19. Disorder Effect of Quantum Anomalous Hall effect in Graphene (United States)

    Qiao, Zhenhua; Yang, Shengyuan A.; Tse, Wang-Kong; Yao, Yugui; Wang, Jian; Niu, Qian


    We investigate the possibility of realizing quantum anomalous Hall effect in graphene. We show that a bulk energy gap can be opened in the presence of both Rashba spin-orbit coupling and an exchange field. We calculate the Berry curvature distribution and find a nonzero Chern number for the valence bands and demonstrate the existence of gapless edge states. Inspired by this finding, we also study, by first-principles method, a concrete example of graphene with Fe atoms adsorbed on top, obtaining the same result. We further study the disorder effect of this quantum anomalous Hall effect and show how this state is localized in the presence of strong disorders.

  20. Porting a Hall MHD Code to a Graphic Processing Unit (United States)

    Dorelli, John C.


    We present our experience porting a Hall MHD code to a Graphics Processing Unit (GPU). The code is a 2nd order accurate MUSCL-Hancock scheme which makes use of an HLL Riemann solver to compute numerical fluxes and second-order finite differences to compute the Hall contribution to the electric field. The divergence of the magnetic field is controlled with Dedner?s hyperbolic divergence cleaning method. Preliminary benchmark tests indicate a speedup (relative to a single Nehalem core) of 58x for a double precision calculation. We discuss scaling issues which arise when distributing work across multiple GPUs in a CPU-GPU cluster.

  1. Inverse spin Hall effect in a closed loop circuit

    Energy Technology Data Exchange (ETDEWEB)

    Omori, Y.; Auvray, F.; Wakamura, T.; Niimi, Y., E-mail: [Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwa-no-ha, Kashiwa, Chiba 277-8581 (Japan); Fert, A. [Unité Mixte de Physique CNRS/Thales, 91767 Palaiseau France associée à l' Université de Paris-Sud, 91405 Orsay (France); Otani, Y. [Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwa-no-ha, Kashiwa, Chiba 277-8581 (Japan); RIKEN-CEMS, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)


    We present measurements of inverse spin Hall effects (ISHEs), in which the conversion of a spin current into a charge current via the ISHE is detected not as a voltage in a standard open circuit but directly as the charge current generated in a closed loop. The method is applied to the ISHEs of Bi-doped Cu and Pt. The derived expression of ISHE for the loop structure can relate the charge current flowing into the loop to the spin Hall angle of the SHE material and the resistance of the loop.

  2. Impact of external conditions on energy consumption in industrial halls (United States)

    Żabnieńśka-Góra, Alina


    The energy demand for heating the halls buildings is high. The impact on this may have the technology of production, building construction and technology requirements (HVAC systems). The isolation of the external partitions, the location of the object in relation to the surrounding buildings and the degree of the interior insolation (windows and skylights) are important in the context of energy consumption. The article discusses the impact of external conditions, wind and sunlight on energy demand in the industrial hall. The building model was prepared in IDA ICE 4.0 simulation software. Model validation was done based on measurements taken in the analyzed building.

  3. Skyrmion-induced anomalous Hall conductivity on topological insulator surfaces (United States)

    Araki, Yasufumi; Nomura, Kentaro


    Electron-spin momentum locking together with background magnetic textures can significantly alter the electron transport properties. We investigate theoretically the electron transport at the interface between a topological insulator and a magnetic insulator with magnetic skyrmions on the top. In contrast to the conventional topological Hall effect in normal metals, the skyrmions yield an additional contribution to the anomalous Hall conductivity even in the absence of in-plane magnetic texture, arising from the phase factor characteristic of Dirac electrons acquired at the skyrmion boundary.

  4. Wind tunnel tests of tent halls of different shape

    Directory of Open Access Journals (Sweden)

    Porowska Agnieszka


    Full Text Available Aerodynamic investigations of wind pressure distribution on the surfaces of models of tent halls were carried out in the boundary layer wind tunnel at the Cracow University of Technology. Four types of objects of different shapes and construction were tested. Although tent halls are significantly vulnerable with respect to the wind action, there is no information about pressure distribution on objects of such type in standards, codes and normalization documents. Obtained results indicate that it is necessary to take into account different configurations of wind action while designing of the analysed structures.

  5. Quantum inferring acausal structures and the Monty Hall problem (United States)

    Kurzyk, Dariusz; Glos, Adam


    This paper presents a quantum version of the Monty Hall problem based upon the quantum inferring acausal structures, which can be identified with generalization of Bayesian networks. Considered structures are expressed in formalism of quantum information theory, where density operators are identified with quantum generalization of probability distributions. Conditional relations between quantum counterpart of random variables are described by quantum conditional operators. Presented quantum inferring structures are used to construct a model inspired by scenario of well-known Monty Hall game, where we show the differences between classical and quantum Bayesian reasoning.

  6. Spin-Hall nano-oscillator: A micromagnetic study

    Energy Technology Data Exchange (ETDEWEB)

    Giordano, A.; Azzerboni, B.; Finocchio, G. [Department of Electronic Engineering, Industrial Chemistry and Engineering, University of Messina, C.da di Dio, I-98166 Messina (Italy); Carpentieri, M. [Department of Electrical and Information Engineering, Politecnico of Bari, via E. Orabona 4, I-70125 Bari (Italy); Laudani, A. [Department of Engineering, University of Roma Tre, via V. Volterra 62, I-00146 Roma (Italy); Gubbiotti, G. [Istituto Officina dei Materiali del CNR (CNR-IOM), Unità di Perugia c/o Dipartimento di Fisica e Geologia, Via A. Pascoli, 06123 Perugia (Italy)


    This Letter studies the dynamical behavior of spin-Hall nanoscillators from a micromagnetic point of view. The model parameters have been identified by reproducing recent experimental data quantitatively. Our results indicate that a strongly localized mode is observed for in-plane bias fields such as in the experiments, while predict the excitation of an asymmetric propagating mode for large enough out-of plane bias field similarly to what observed in spin-torque nanocontact oscillators. Our findings show that spin-Hall nanoscillators can find application as spin-wave emitters for magnonic applications where spin waves are used for transmission and processing information on nanoscale.

  7. Fractional Quantum Hall Plateau Transitions and Composite Fermi Liquids (United States)

    Cho, Gil Young; Moon, Eun-Gook; Fradkin, Eduardo

    We will investigate relationship between the fractional quantum Hall plateau transition from Laughlin state at ν =1/2 n + 1 to a trivial insulator, and composite Fermi liquid at ν =1/2 (2 n + 1) . We use the recently-developed quantum field theoretic technique, 3d dualities, in combinations with the coupled-wire descriptions for quantum Hall states. We will show that we can also access various other phases, including non-abelian paired states at ν =1/2 (2 n + 1) , from the plateau transition. This work is supported by the Brain Korea 21 PLUS Project of Korea Government and KAIST start-up funding (GYC & EGM).

  8. Hall Effect Thruster for High Power Solar Electric Propulsion Technology Demonstration Project (United States)

    National Aeronautics and Space Administration — Busek proposes to develop a flight version of a high power Hall Effect thruster. While numerous high power Hall Effect thrusters have been demonstrated in the...

  9. Measured Early Lateral Energy Fractions in Concert Halls and Opera Houses (United States)

    BARRON, M.


    In the 30 years since early lateral reflections were first suggested as important for concert halls, spatial impression and source broadening have become almost universally accepted as essential characteristics of halls with good acoustics. Two objective measures of source broadening have been proposed. Measured values of the best defined of these measures, the early lateral energy fraction (LF), are considered here. Results from two independent measurement surveys are discussed. Comparisons of LF values by hall show a significant link between hall mean LF and hall width. There is however considerable overlap between measured LF values in different halls so the relevance of describing halls by their mean early lateral energy fraction values is questionable. The behaviour of LF values within auditoria is discussed for different concert hall plan forms and within opera houses. A measure of source broadening including sound level is proposed and results considered in the context of auditorium design.

  10. Hall-Effect Thruster Simulations with 2-D Electron Transport and Hydrodynamic Ions (United States)

    Mikellides, Ioannis G.; Katz, Ira; Hofer, Richard H.; Goebel, Dan M.


    A computational approach that has been used extensively in the last two decades for Hall thruster simulations is to solve a diffusion equation and energy conservation law for the electrons in a direction that is perpendicular to the magnetic field, and use discrete-particle methods for the heavy species. This "hybrid" approach has allowed for the capture of bulk plasma phenomena inside these thrusters within reasonable computational times. Regions of the thruster with complex magnetic field arrangements (such as those near eroded walls and magnets) and/or reduced Hall parameter (such as those near the anode and the cathode plume) challenge the validity of the quasi-one-dimensional assumption for the electrons. This paper reports on the development of a computer code that solves numerically the 2-D axisymmetric vector form of Ohm's law, with no assumptions regarding the rate of electron transport in the parallel and perpendicular directions. The numerical challenges related to the large disparity of the transport coefficients in the two directions are met by solving the equations in a computational mesh that is aligned with the magnetic field. The fully-2D approach allows for a large physical domain that extends more than five times the thruster channel length in the axial direction, and encompasses the cathode boundary. Ions are treated as an isothermal, cold (relative to the electrons) fluid, accounting for charge-exchange and multiple-ionization collisions in the momentum equations. A first series of simulations of two Hall thrusters, namely the BPT-4000 and a 6-kW laboratory thruster, quantifies the significance of ion diffusion in the anode region and the importance of the extended physical domain on studies related to the impact of the transport coefficients on the electron flow field.

  11. Finite-temperature effective boundary theory of the quantized thermal Hall effect


    Nakai, Ryota; Ryu, Shinsei; Nomura, Kentaro


    A finite-temperature effective free energy of the boundary of a quantized thermal Hall system is derived microscopically from the bulk two-dimensional Dirac fermion coupled with a gravitational field. In two spatial dimensions, the thermal Hall conductivity of fully gapped insulators and superconductors is quantized and given by the bulk Chern number, in analogy to the quantized electric Hall conductivity in quantum Hall systems. From the perspective of effective action functionals, two disti...

  12. Stuart Hall and the Theory and Practice of Articulation (United States)

    Clarke, John


    In this article, I argue that the idea of articulation links three different dimensions of Stuart Hall's work: it is central to the work of cultural politics, to the work of hegemony and to his practice of embodied pedagogy. I claim that his approach to pedagogy entails the art of listening combined with the practice of theorising in the service…

  13. Challenges of scanning hall microscopy using batch fabricated probes

    NARCIS (Netherlands)

    Hatakeyama, Kodai


    Scanning Hall probe microscopy is a widely used technique for quantitative high resolution imaging of magnetic stray fields. Up to now probes with nanometer spatial resolution have only been realized by electron beam lithography, which is a slow and expensive fabrication technique. In this thesis,

  14. NASA HERMeS Hall Thruster Electrical Configuration Characterization (United States)

    Peterson, Peter; Kamhawi, Hani; Huang, Wensheng; Yim, John; Herman, Daniel; Williams, George; Gilland, James; Hofer, Richard


    NASAs Hall Effect Rocket with Magnetic Shielding (HERMeS) 12.5 kW Technology Demonstration Unit-1 (TDU-1) Hall thruster has been the subject of extensive technology maturation in preparation for development into a flight ready propulsion system. Part of the technology maturation was to test the TDU-1 thruster in several ground based electrical configurations to assess the thruster robustness and suitability to successful in-space operation. The ground based electrical configuration testing has recently been demonstrated as an important step in understanding and assessing how a Hall thruster may operate differently in space compared to ground based testing, and to determine the best configuration to conduct development and qualification testing. This presentation will cover the electrical configuration testing of the TDU-1 HERMeS Hall thruster in NASA Glenn Research Centers Vacuum Facility 5. The three electrical configurations examined are the thruster body tied to facility ground, thruster floating, and finally the thruster body electrically tied to cathode common. The TDU-1 HERMeS was configured with two different exit plane boundary conditions, dielectric and conducting, to examine the influence on the electrical configuration characterization.

  15. Sensitivity of resistive and Hall measurements to local inhomogeneities

    DEFF Research Database (Denmark)

    Koon, Daniel W.; Wang, Fei; Petersen, Dirch Hjorth


    We derive exact, analytic expressions for the sensitivity of resistive and Hall measurements to local inhomogeneities in a specimen's material properties in the combined linear limit of a weak perturbation over an infinitesimal area in a small magnetic field. We apply these expressions both to four...

  16. From quantum confinement to quantum Hall effect in graphene nanostructures

    NARCIS (Netherlands)

    Guimaraes, M. H. D.; Shevtsov, O.; Waintal, X.; van Wees, B. J.


    We study the evolution of the two-terminal conductance plateaus with a magnetic field for armchair graphene nanoribbons (GNRs) and graphene nanoconstrictions (GNCs). For GNRs, the conductance plateaus of 2e(2)/h at zero magnetic field evolve smoothly to the quantum Hall regime, where the plateaus in

  17. Composite fermions a unified view of the quantum Hall regime

    CERN Document Server


    One of the most exciting recent developments to have emerged from the quantum Hall effect is the subject of composite fermions. This important volume gives a self-contained, comprehensive description of the subject, including fundamentals, more advanced theoretical work, and results from experimental observations of composite fermions.

  18. Tondiraba jäähall = Tondiraba ice arena

    Index Scriptorium Estoniae


    Tondiraba jäähall Tallinnas Varraku tänav 14, valminud 2014. Arhitektid Ott Kadarik, Mihkel Tüür, Kadri Tamme (Kadarik Tüür Arhitektid OÜ), insener Paavo Pikand. Eesti Kultuurkapitali Arhitektuuri sihtkapitali aastapreemia 2014

  19. Design of an Efficient Incinerator for Independence Hall, University ...

    African Journals Online (AJOL)

    The menace constituted by improperly disposed solid waste has led to an increase in growing awareness towards solid waste disposal alternatives. The case of Independence Hall in University of Ibadan, Nigeria is not different as delay in the ultimate collection of the waste makes the storage site become an eye-sore and ...

  20. Stop Tobacco in Restaurants: Fifth Grade Students STIR City Hall (United States)

    Morris, Ronald Vaughan


    This article discusses a campaign called STIR: Stop Tobacco in Restaurants, that was started by fourth and fifth grade students. The goal was to end smoking in public places, including restaurants, bowling alleys, sports bars, and pool halls. For two years they motivated their peers, coordinated an information campaign to urge kids and adults to…

  1. Relationship between room shape and acoustics of rectangular concert halls

    DEFF Research Database (Denmark)

    Klosak, Andrzej K.; Gade, Anders Christian


    Extensive acoustics computer simulations have been made using Odeon computer simulation software. In 24 rectangular rooms representing "shoe-box" type concert halls with volumes of 8 000 m3, 12 000 m3 and 16 000 m3 from 300 to 850 measurements positions have been analysed. Only room averaged...

  2. Effect of Hall Current and Finite Larmor Radius Corrections on ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Astrophysics and Astronomy; Volume 37; Issue 3. Effect of Hall Current and Finite Larmor Radius Corrections on Thermal Instability of Radiative Plasma for Star Formation in Interstellar Medium (ISM). Sachin Kaothekar. Research Article Volume 37 Issue 3 September 2016 Article ID 23 ...

  3. Effect of Hall Current and Finite Larmor Radius Corrections on ...

    Indian Academy of Sciences (India)

    Abstract. The effects of finite ion Larmor radius (FLR) corrections,. Hall current and radiative heat-loss function on the thermal instability of an infinite homogeneous, viscous plasma incorporating the effects of finite electrical resistivity, thermal conductivity and permeability for star formation in interstellar medium have been ...

  4. Quantum Hall physics: Hierarchies and conformal field theory techniques (United States)

    Hansson, T. H.; Hermanns, M.; Simon, S. H.; Viefers, S. F.


    The fractional quantum Hall effect, being one of the most studied phenomena in condensed matter physics during the past 30 years, has generated many ground-breaking new ideas and concepts. Very early on it was realized that the zoo of emerging states of matter would need to be understood in a systematic manner. The first attempts to do this, by Haldane and Halperin, set an agenda for further work which has continued to this day. Since that time the idea of hierarchies of quasiparticles condensing to form new states has been a pillar of our understanding of fractional quantum Hall physics. In the 30 years that have passed since then, a number of new directions of thought have advanced our understanding of fractional quantum Hall states and have extended it in new and unexpected ways. Among these directions is the extensive use of topological quantum field theories and conformal field theories, the application of the ideas of composite bosons and fermions, and the study of non-Abelian quantum Hall liquids. This article aims to present a comprehensive overview of this field, including the most recent developments.

  5. new concepts of a modified hall - petch type relationship

    African Journals Online (AJOL)


    Abstract. A modified form of the Hall - Perch equation, where the average grain diameter is replaced by the surface to volume ratio of internal boundaries (Sv), is considered. Working with this model, a flow stress – Sv relationship dominated by geometrically necessary dislocations (GNDs) is derived for the low strain region.

  6. Virtual Environment of Real Sport Hall and Analyzing Rendering Quality

    Directory of Open Access Journals (Sweden)

    Filip Popovski


    Full Text Available Here is presented virtual environment of a real sport hall created in Quest3D VR Edition. All analyzes of the rendering quality, techniques of interaction and performance of the system in real time are presented. We made critical analysis on all of these techniques on different machines and have excellent results.

  7. Magnetoresistance in quantum Hall metals due to Pancharatnam ...

    Indian Academy of Sciences (India)

    We discuss the relevant physical postulates with respect to these physical processes to qualitatively reproduce the measured Hall resistance's zigzag curve for both the integer and the ... Manuscript received: 14 January 2014; Manuscript revised: 15 May 2014; Accepted: 16 June 2014; Early published: 11 January 2015 ...

  8. Acceptability of the Hall Technique to parents and children. (United States)

    Page, Lyndie A Foster; Boyd, Dorothy H; Davidson, Sarah E; McKay, Samantha K; Thomson, W Murray; Innes, Nicola P


    To investigate the acceptability of stainless steel crowns placed by dental therapists on children's primary molars using the Hall Technique. Mixed methods approach, using qualitative inductive analysis and quantitative analysis. Hawke's Bay Community Oral Health Service One focus group was conducted and ten thirty-minute phone interviews were undertaken with parents of children who had previously had a stainless steel crown placed using the Hall Technique (over the period 1 December 2011 to 31 May 2012). An inductive approach was used to analyse the qualitative research data, and the information was arranged into several categories based on the key themes which arose. Children treated with the Hall Technique were asked immediately after treatment whether they had enjoyed their visit to the clinic that day. Common themes were found with regard to appearance, pain, the procedure, and general opinions on acceptability. Nearly all (90%) of the children responded positively about their visit to the clinic. There was a high degree of acceptance among both parents and children for stainless steel crown placement using the Hall Technique in this group.

  9. Hall kirjandus võrgustunud maailmas / Anneli Kuiv

    Index Scriptorium Estoniae

    Kuiv, Anneli


    1997. aasta määratluse kohaselt on hall kirjandus "kirjandus, mida toodetakse kõikidel tasanditel valitsus- ja teadusasutuste, äri- ja tootmisringkondade poolt nii trükituna kui ka elektroonselt, kuid mis ei ole kirjastustööstuse kontrolli all"

  10. Planar Hall effect sensor for magnetic micro- and nanobead detection

    DEFF Research Database (Denmark)

    Ejsing, Louise Wellendorph; Hansen, Mikkel Fougt; Menon, Aric Kumaran


    Magnetic bead sensors based on the planar Hall effect in thin films of exchange-biased permalloy have been fabricated and characterized. Typical sensitivities are 3 muV/Oe mA. The sensor response to an applied magnetic field has been measured without and with coatings of commercially available 2 ...

  11. Low-frequency noise in planar Hall effect bridge sensors

    DEFF Research Database (Denmark)

    Persson, Anders; Bejhedb, R.S.; Bejhed, R.S.


    The low-frequency characteristics of planar Hall effect bridge sensors are investigated as function of the sensor bias current and the applied magnetic field. The noise spectra reveal a Johnson-like spectrum at high frequencies, and a 1/f-like excess noise spectrum at lower frequencies, with a knee...

  12. Decomposition of fractional quantum Hall states: New symmetries and approximations

    NARCIS (Netherlands)

    Thomale, R.; Estienne, B.; Regnault, N.; Bernevig, B.A.


    Abstract: We provide a detailed description of a new symmetry structure of the monomial (Slater) expansion coefficients of bosonic (fermionic) fractional quantum Hall states first obtained in Ref. 1, which we now extend to spin-singlet states. We show that the Haldane-Rezayi spin-singlet state can

  13. Ion Velocity Measurements in a Linear Hall Thruster

    National Research Council Canada - National Science Library

    Gascon, Nicolas; Cappelli, Mark A; Hargus, William A., Jr


    ... of wall material, or magnetic field intensity. When operated with a low background pressure, the particular Hall discharge studied here creates an ion accelerating electrostatic field mainly outside of the channel, in a narrow zone located 5-20 mm away from the exit plane.

  14. Mini array of quantum Hall devices based on epitaxial graphene

    Energy Technology Data Exchange (ETDEWEB)

    Novikov, S.; Lebedeva, N. [Department of Micro and Nanosciences, Aalto University, Micronova, Tietotie 3, Espoo (Finland); Hämäläinen, J.; Iisakka, I.; Immonen, P.; Manninen, A. J.; Satrapinski, A. [VTT Technical Research Centre of Finland Ltd., Centre for Metrology MIKES, P.O. Box 1000, 02044 VTT (Finland)


    Series connection of four quantum Hall effect (QHE) devices based on epitaxial graphene films was studied for realization of a quantum resistance standard with an up-scaled value. The tested devices showed quantum Hall plateaux R{sub H,2} at a filling factor v = 2 starting from a relatively low magnetic field (between 4 T and 5 T) when the temperature was 1.5 K. The precision measurements of quantized Hall resistance of four QHE devices connected by triple series connections and external bonding wires were done at B = 7 T and T = 1.5 K using a commercial precision resistance bridge with 50 μA current through the QHE device. The results showed that the deviation of the quantized Hall resistance of the series connection of four graphene-based QHE devices from the expected value of 4×R{sub H,2} = 2 h/e{sup 2} was smaller than the relative standard uncertainty of the measurement (<1 × 10{sup −7}) limited by the used resistance bridge.

  15. College Sports Fan Aggression: Implications for Residence Hall Discipline. (United States)

    Coons, Christine Jansen; And Others


    Evaluated relationship between spectator aggression at football games and residence hall discipline. Results indicated that there is significant correlation, on five variables tested, between fan behavior and the increase of disciplinary cases during football weekends. Provides suggestions for interventions to reduce disciplinary actions. (JBJ)

  16. The Marketing of Residence Halls: A Question of Positioning. (United States)

    Parker, R. Stephen; And Others


    A survey of 343 college residence hall directors revealed percentages of private and public institutions offering different amenities, main selling points in promotional brochures, and the most common resident complaints. Results were compared with those of a resident survey concerning the importance of various housing attributes. Implications for…

  17. Energy efficient heating and ventilation of large halls

    CERN Document Server

    Hojer, Ondrej; Kabele, Karel; Kotrbaty, Miroslav; Sommer, Klaus; Petras, Dusan


    This guidebook is focused on modern methods for design, control and operation of energy efficient heating systems in large spaces and industrial halls. The book deals with thermal comfort, light and dark gas radiant heaters, panel radiant heating, floor heating and industrial air heating systems. Various heating systems are illustrated with case studies. Design principles, methods and modeling tools are presented for various systems.

  18. Darrell Hall Covos-Day Books, Weltevreden Park, South Africa ...

    African Journals Online (AJOL)

    published in 1991 and a second edition in 1994. His second work, entitled Long Tom, deals with the history of the famous 155mm Creusot siege guns of the Boers. His last work, The. Hall handbook of the Anglo-Boer War, was published posthumously in 1999 under the editorship of Fransjohan Pretorius and Gilbert Torlage.

  19. Quantum Hall Ferroelectrics and Nematics in Multivalley Systems

    Directory of Open Access Journals (Sweden)

    Inti Sodemann


    Full Text Available We study broken symmetry states at integer Landau-level fillings in multivalley quantum Hall systems whose low-energy dispersions are anisotropic. When the Fermi surface of individual pockets lacks twofold rotational symmetry, like in bismuth (111 [Feldman et al. , Observation of a Nematic Quantum Hall Liquid on the Surface of Bismuth, Science 354, 316 (2016SCIEAS0036-807510.1126/science.aag1715] and in Sn_{1-x}Pb_{x}Se (001 [Dziawa et al., Topological Crystalline Insulator States in Pb_{1-x}Sn_{x}Se, Nat. Mater. 11, 1023 (2012NMAACR1476-112210.1038/nmat3449] surfaces, interactions tend to drive the formation of quantum Hall ferroelectric states. We demonstrate that the dipole moment in these states has an intimate relation to the Fermi surface geometry of the parent metal. In quantum Hall nematic states, like those arising in AlAs quantum wells, we demonstrate the existence of unusually robust Skyrmion quasiparticles.

  20. Exotic galilean symmetry, non-commutativity & the Hall effect


    Horvathy, P.


    The ``exotic'' particle model associated with the two-parameter central extension of the planar Galilei group can be used to derive the ground states of the Fractional Quantum Hall Effect. Similar equations arise for a semiclassical Bloch electron. Exotic Galilean symmetry is also be shared by Chern-Simons field theory of the Moyal type.

  1. Interaction Induced Quantum Valley Hall Effect in Graphene

    Directory of Open Access Journals (Sweden)

    E. C. Marino


    Full Text Available We use pseudo-quantum electrodynamics in order to describe the full electromagnetic interaction of the p electrons in graphene in a consistent 2D formulation. We first consider the effect of this interaction in the vacuum polarization tensor or, equivalently, in the current correlator. This allows us to obtain the T→0 conductivity after a smooth zero-frequency limit is taken in Kubo’s formula. Thereby, we obtain the usual expression for the minimal conductivity plus corrections due to the interaction that bring it closer to the experimental value. We then predict the onset of an interaction-driven spontaneous quantum valley Hall effect below an activation temperature of the order of 2 K. The transverse (Hall valley conductivity is evaluated exactly and shown to coincide with the one in the usual quantum Hall effect. Finally, by considering the effects of pseudo-quantum electrodynamics, we show that the electron self-energy is such that a set of P- and T-symmetric gapped electron energy eigenstates are dynamically generated, in association with the quantum valley Hall effect.

  2. A two fluid description of the Quantum Hall Soliton

    Energy Technology Data Exchange (ETDEWEB)

    Freivogel, Ben [Stanford Univ., Stanford, CA (United States); Susskind, Leonard [Stanford Univ., Stanford, CA (United States); Toumbas, Nicolaos [Stanford Univ., Stanford, CA (United States)


    We show that the Quantum Hall Soliton constructed in [1] is stable under small perturbations. We find that creating quasiparticles actually lowers the energy of the system, and discuss whether this indicates an instability on the time scales relevant to the problem.

  3. A Spreadsheet Simulation of the Monty Hall Problem (United States)

    Patterson, Mike C.; Harmel, Bob; Friesen, Dan


    The "Monty Hall" problem or "Three Door" problem--where a person chooses one of three doors in hope of winning a valuable prize but is subsequently offered the choice of changing his or her selection--is a well known and often discussed probability problem. In this paper, the structure, history, and ultimate solution of the…

  4. Numerical simulation of SMART-1 Hall-thruster plasma interactions

    NARCIS (Netherlands)

    Tajmar, Martin; Sedmik, René; Scharlemann, Carsten


    SMART-1 has been the first European mission using a Hall thruster to reach the moon. An onboard plasma diagnostic package allowed a detailed characterization of the thruster exhaust plasma and its interactions with the spacecraft. Analysis of in-flight data revealed, amongst others, an unpredicted

  5. Mechanism of sound absorption by seated audience in halls. (United States)

    Nishihara, N; Hidaka, T; Beranek, L L


    Four methods are explored for predicting the reverberation times in fully occupied halls for music as related to the sound absorption by their audiences. The methods for providing audience absorptions include two that use reverberation chambers, namely, the ISO 354 method (and other similar standards) (ISO) and Kath and Kuhl's method (K & K) [Acustica 15, 127-131 (1965)], and two that use average data from halls, i.e., Beranek's method (COH) [Concert and Opera Halls: How They Sound (Acoustical Society of America, Melville, NY, 1996)], and the average audience power-per-seat absorption which in practice is multiplied by the number of seats (AA). These methods are applied to the calculation of reverberation times in six existing halls, fully occupied, and the results were compared with actual measurements. The COH method was best for predictions over the entire frequency range. The K & K method showed the highest accuracy at mid-frequencies. Both the ISO and the K & K methods yielded wide differences for the measurements in the 125- and 250-Hz bands. The AA method was as good as the COH method when the measurements for the six halls were averaged, but showed a wide spread in the predictions around the average because it does not consider the degree of upholstering of the seats. It was hypothecated by the authors that the principal reasons for the ISO and K & K discrepancies at low frequencies were (a) differences between the degree of sound diffusion in actual halls and that in reverberation chambers, and (b) lack of information on the mechanisms of absorption of sound by people seated side-by-side in rows, particularly for near-grazing incidence sound fields. First, this article explores the sound diffusivity in a reverberation chamber and in the halls using CAD models. A probability density function of the incident angles of the sound rays that impinge on the audiences is defined and was measured for each case. Using a unique method, the sound absorption

  6. The influence of profiled ceilings on sports hall acoustics : Ground effect predictions and scale model measurements

    NARCIS (Netherlands)

    Wattez, Y.C.M.; Tenpierik, M.J.; Nijs, L.


    Over the last few years, reverberation times and sound pressure levels have been measured in many sports halls. Most of these halls, for instance those made from stony materials, perform as predicted. However, sports halls constructed with profiled perforated steel roof panels have an unexpected

  7. The use of Hall technique preformed metal crowns by specialist paediatric dentists in the UK


    Roberts, A; McKay, A; Albadri, S


    Examines treatment planning involving Hall technique preformed metal crowns by specialists in paediatric dentistry. Explores clinical situations in which specialists in paediatric dentistry feel it is appropriate or not to fit Hall technique preformed metal crowns. Investigates which types of carious lesions are being treated with Hall technique preformed metal crowns by specialists in paediatric dentistry.

  8. Welcome to USA 15, the first large underground hall for the LHC

    CERN Multimedia


    The first of the four huge underground halls for LHC is ready. USA 15 will be the service hall for ATLAS. It has taken three years to finish the first underground hall for LHC. It is 62 metres long and 20 metres diameter.

  9. 78 FR 37553 - Maternal Health Town Hall Listening Session; Notice of Meeting (United States)


    ... ideas in support of the National Maternal Health Initiative. The Town Hall Listening Session will serve... HUMAN SERVICES Health Resources and Services Administration Maternal Health Town Hall Listening Session; Notice of Meeting Name: Maternal Health Town Hall Listening Session. Date and Time: August 27, 2013, 2:00...

  10. Gender Differences in the Relationship of Hall Directors' Transformational and Transactional Leadership and Achieving Styles. (United States)

    Komives, Susan R.


    In seven-campus study, found significant gender differences in self-perceptions of leadership and achieving style among hall directors (n=74). Found only hall director relational achieving styles were related to resident assistants' work unit's assessment of their hall director's transformational leadership. (Author)

  11. The Relationship of Hall Directors' Transformational and Transactional Leadership to Select Resident Assistant Outcomes. (United States)

    Komives, Susan R.


    Multicampus study examined transformational and transactional leadership factors of hall directors (n=84) and resident assistants (n=806). Results indicated both male and female hall directors practiced transformational leadership behaviors. Hall director leadership behavior accounted for two-thirds of the variance in resident assistant…

  12. In-Situ Measurement of Hall Thruster Erosion Using a Fiber Optic Regression Probe (United States)

    Polzin, Kurt; Korman, Valentin


    One potential life-limiting mechanism in a Hall thruster is the erosion of the ceramic material comprising the discharge channel. This is especially true for missions that require long thrusting periods and can be problematic for lifetime qualification, especially when attempting to qualify a thruster by analysis rather than a test lasting the full duration of the mission. In addition to lifetime, several analytical and numerical models include electrode erosion as a mechanism contributing to enhanced transport properties. However, there is still a great deal of dispute over the importance of erosion to transport in Hall thrusters. The capability to perform an in-situ measurement of discharge channel erosion is useful in addressing both the lifetime and transport concerns. An in-situ measurement would allow for real-time data regarding the erosion rates at different operating points, providing a quick method for empirically anchoring any analysis geared towards lifetime qualification. Erosion rate data over a thruster s operating envelope would also be useful in the modeling of the detailed physics inside the discharge chamber. There are many different sensors and techniques that have been employed to quantify discharge channel erosion in Hall thrusters. Snapshots of the wear pattern can be obtained at regular shutdown intervals using laser profilometry. Many non-intrusive techniques of varying complexity and sensitivity have been employed to detect the time-varying presence of erosion products in the thruster plume. These include the use quartz crystal microbalances, emission spectroscopy, laser induced flourescence, and cavity ring-down spectroscopy. While these techniques can provide a very accurate picture of the level of eroded material in the thruster plume, it is more difficult to use them to determine the location from which the material was eroded. Furthermore, none of the methods cited provide a true in-situ measure of erosion at the channel surface while

  13. Skyrmion Hall effect revealed by direct time-resolved X-ray microscopy (United States)

    Litzius, Kai; Lemesh, Ivan; Krüger, Benjamin; Bassirian, Pedram; Caretta, Lucas; Richter, Kornel; Büttner, Felix; Sato, Koji; Tretiakov, Oleg A.; Förster, Johannes; Reeve, Robert M.; Weigand, Markus; Bykova, Iuliia; Stoll, Hermann; Schütz, Gisela; Beach, Geoffrey S. D.; Kläui, Mathias


    Magnetic skyrmions are promising candidates for future spintronic applications such as skyrmion racetrack memories and logic devices. They exhibit exotic and complex dynamics governed by topology and are less influenced by defects, such as edge roughness, than conventionally used domain walls. In particular, their non-zero topological charge leads to a predicted `skyrmion Hall effect', in which current-driven skyrmions acquire a transverse velocity component analogous to charged particles in the conventional Hall effect. Here, we use nanoscale pump-probe imaging to reveal the real-time dynamics of skyrmions driven by current-induced spin-orbit torques. We find that skyrmions move at a well-defined angle ΘSkH that can exceed 30° with respect to the current flow, but in contrast to conventional theoretical expectations, ΘSkH increases linearly with velocity up to at least 100 ms-1. We qualitatively explain our observation based on internal mode excitations in combination with a field-like spin-orbit torque, showing that one must go beyond the usual rigid skyrmion description to understand the dynamics.

  14. Temporal Correlations in Vortex Channel Flow Studied Using High-Resolution Hall Probes. (United States)

    James, S.; Field, S. B.; Shtrikman, H.; Hong, K.; Reich, D. H.


    The dynamics of vortices near the depinning transition can be quite complex, with vortices moving via channel-like flow configurations in a manner which is not fully understood. We have investigated this system using single and multiple GaAs heterojunction Hall probes fixed to a current-carrying Nb strip. A single 1μm fixed probe reveals that the (time-averaged) flux beneath it changes in a discrete fashion at evidently random times. The flux may remain at a particular value for up to several seconds before changing, during which time millions of vortices pass under the probe. This suggests that the vortices flow along very long-lived channels which occasionally rearrange themselves, perhaps due to thermal activation of pinned vortices. An extension of the investigation using a linear array of 16 Hall probes arranged perpendicular to the vortex flow will further reveal spatial and temporal correlations in this channel flow. The array consists of a 1μm-wide bar along which adjoin 16 pairs of 1μm-wide voltage leads at 1μm intervals. A 16 channel digital lockin technique has been developed to record the data.

  15. Magnetic field deformation due to electron drift in a Hall thruster


    Han Liang; Ding Yongjie; Zhang Xu; Wei Liqiu; Yu Daren


    The strength and shape of the magnetic field are the core factors in the design of the Hall thruster. However, Hall current can affect the distribution of static magnetic field. In this paper, the Particle-In-Cell (PIC) method is used to obtain the distribution of Hall current in the discharge channel. The Hall current is separated into a direct and an alternating part to calculate the induced magnetic field using Finite Element Method Magnetics (FEMM). The results show that the direct Hall c...

  16. On the low-field Hall coefficient of graphite

    Directory of Open Access Journals (Sweden)

    P. Esquinazi


    Full Text Available We have measured the temperature and magnetic field dependence of the Hall coefficient (RH in three, several micrometer long multigraphene samples of thickness between ∼9 to ∼30 nm in the temperature range 0.1 to 200 K and up to 0.2 T field. The temperature dependence of the longitudinal resistance of two of the samples indicates the contribution from embedded interfaces running parallel to the graphene layers. At low enough temperatures and fields RH is positive in all samples, showing a crossover to negative values at high enough fields and/or temperatures in samples with interfaces contribution. The overall results are compatible with the reported superconducting behavior of embedded interfaces in the graphite structure and indicate that the negative low magnetic field Hall coefficient is not intrinsic of the ideal graphite structure.

  17. The Hall Technique for managing carious primary molars. (United States)

    Innes, Nicola; Evans, Dafydd; Hall, Norna


    The Hall Technique, a method of managing carious primary molars effectively with preformed metal crowns, without the use of local anaesthesia, caries removal or tooth preparation of any kind, is described.The technique is illustrated with a case report.The evidence underpinning the technique is discussed, along with indications and contra-indications for its use, and details of where clinicians can obtain further information on the technique if they are considering using it. Research evidence has indicated that the Hall Technique is effective in managing dental caries in primary molar teeth when used by General Dental Practitioners, and is preferred by them, their child patients and the children's parents to conventional restorative methods for these teeth.

  18. Chiral Exact Relations for Helicities in Hall Magnetohydrodynamic Turbulence

    CERN Document Server

    Banerjee, Supratik


    Besides total energy, three-dimensional incompressible Hall magnetohydrodynamics (MHD) possesses two inviscid invariants which are the magnetic helicity and the generalized helicity. New exact relations are derived for homogeneous (non-isotropic) stationary Hall MHD turbulence (and also for its inertialess electron MHD limit) with non-zero helicities and in the asymptotic limit of large Reynolds numbers. The universal laws are written only in terms of mixed second-order structure functions, i.e. the scalar product of two different increments. It provides, therefore, a direct measurement of the dissipation rates for the corresponding invariant flux. This study shows that the generalized helicity cascade is strongly linked to the left polarized fluctuations while the magnetic helicity cascade is linked to the right polarized fluctuations.

  19. Multi-region relaxed Hall magnetohydrodynamics with flow

    CERN Document Server

    Lingam, Manasvi; Hudson, Stuart R


    The recent formulations of multi-region relaxed magnetohydrodynamics (MRxMHD) have generalized the famous Woltjer-Taylor states by incorporating a collection of "ideal barriers" that prevent global relaxation, and flow. In this paper, we generalize MRxMHD with flow to include Hall effects (MRxHMHD), and thereby obtain the partially relaxed counterparts of the famous double Beltrami states as a special subset. The physical and mathematical consequences arising from the introduction of the Hall term are also presented. We demonstrate that our results (in the ideal MHD limit) constitute an important subset of ideal MHD equilibria, and we compare our approach against other variational principles proposed for deriving the relaxed states.

  20. Recent advances in the spin Hall effect of light (United States)

    Ling, Xiaohui; Zhou, Xinxing; Huang, Kun; Liu, Yachao; Qiu, Cheng-Wei; Luo, Hailu; Wen, Shuangchun


    The spin Hall effect (SHE) of light, as an analogue of the SHE in electronic systems, is a promising candidate for investigating the SHE in semiconductor spintronics/valleytronics, high-energy physics and condensed matter physics, owing to their similar topological nature in the spin-orbit interaction. The SHE of light exhibits unique potential for exploring the physical properties of nanostructures, such as determining the optical thickness, and the material properties of metallic and magnetic thin films and even atomically thin two-dimensional materials. More importantly, it opens a possible pathway for controlling the spin states of photons and developing next-generation photonic spin Hall devices as a fundamental constituent of the emerging spinoptics. In this review, based on the viewpoint of the geometric phase gradient, we give a detailed presentation of the recent advances in the SHE of light and its applications in precision metrology and future spin-based photonics.

  1. Creating a bosonic fractional quantum Hall state by pairing fermions (United States)

    Repellin, Cécile; Yefsah, Tarik; Sterdyniak, Antoine


    We numerically study the behavior of spin-1 /2 fermions on a two-dimensional square lattice subject to a uniform magnetic field, where opposite spins interact via an on-site attractive interaction. Starting from the noninteracting case where each spin population is prepared in a quantum Hall state with unity filling, we follow the evolution of the system as the interaction strength is increased. Above a critical value and for sufficiently low flux density, we observe the emergence of a twofold quasidegeneracy accompanied by the opening of an energy gap to the third level. Analysis of the entanglement spectra shows that the gapped ground state is the bosonic 1 /2 Laughlin state. Our work therefore provides compelling evidence of a topological phase transition from the fermionic quantum Hall state at unity filling to the bosonic Laughlin state at a critical attraction strength of the order of the one-body spectrum linewidth.

  2. Precise quantization of anomalous Hall effect near zero magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Bestwick, A. J. [Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States); Fox, E. J. [Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States); Kou, Xufeng [Univ. of California, Los Angeles, CA (United States); Pan, Lei [Univ. of California, Los Angeles, CA (United States); Wang, Kang L. [Univ. of California, Los Angeles, CA (United States); Goldhaber-Gordon, D. [Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)


    In this study, we report a nearly ideal quantum anomalous Hall effect in a three-dimensional topological insulator thin film with ferromagnetic doping. Near zero applied magnetic field we measure exact quantization in the Hall resistance to within a part per 10,000 and a longitudinal resistivity under 1 Ω per square, with chiral edge transport explicitly confirmed by nonlocal measurements. Deviations from this behavior are found to be caused by thermally activated carriers, as indicated by an Arrhenius law temperature dependence. Using the deviations as a thermometer, we demonstrate an unexpected magnetocaloric effect and use it to reach near-perfect quantization by cooling the sample below the dilution refrigerator base temperature in a process approximating adiabatic demagnetization refrigeration.

  3. Tearing mode dynamics and sawtooth oscillation in Hall-MHD (United States)

    Ma, Zhiwei; Zhang, Wei; Wang, Sheng


    Tearing mode instability is one of the most important dynamic processes in space and laboratory plasmas. Hall effects, resulted from the decoupling of electron and ion motions, could cause the fast development and perturbation structure rotation of the tearing mode and become non-negligible. We independently developed high accuracy nonlinear MHD code (CLT) to study Hall effects on the dynamic evolution of tearing modes with Tokamak geometries. It is found that the rotation frequency of the mode in the electron diamagnetic direction is in a good agreement with analytical prediction. The linear growth rate increases with increase of the ion inertial length, which is contradictory to analytical solution in the slab geometry. We further find that the self-consistently generated rotation largely alters the dynamic behavior of the double tearing mode and the sawtooth oscillation. National Magnetic Confinement Fusion Science Program of China under Grant No. 2013GB104004 and 2013GB111004.

  4. Planar Hall effect sensor with magnetostatic compensation layer

    DEFF Research Database (Denmark)

    Dalslet, Bjarke Thomas; Donolato, Marco; Hansen, Mikkel Fougt


    Demagnetization effects in cross-shaped planar Hall effect sensors cause inhomogeneous film magnetization and a hysteretic sensor response. Furthermore, when using sensors for detection of magnetic beads, the magnetostatic field from the sensor edges attracts and holds magnetic beads near the sen...... flow 60 times smaller than a flow that failed to remove beads from an uncompensated sensor.......Demagnetization effects in cross-shaped planar Hall effect sensors cause inhomogeneous film magnetization and a hysteretic sensor response. Furthermore, when using sensors for detection of magnetic beads, the magnetostatic field from the sensor edges attracts and holds magnetic beads near...... the sensor edges causing inhomogeneous and non-specific binding of the beads. We show theoretically that adding a compensation magnetic stack beneath the sensor stack and exchange-biasing it antiparallel to the sensor stack, the magnetostatic field is minimized. We show experimentally that the compensation...

  5. Simulating Smoke Filling in Big Halls by Computational Fluid Dynamics

    Directory of Open Access Journals (Sweden)

    W. K. Chow


    Full Text Available Many tall halls of big space volume were built and, to be built in many construction projects in the Far East, particularly Mainland China, Hong Kong, and Taiwan. Smoke is identified to be the key hazard to handle. Consequently, smoke exhaust systems are specified in the fire code in those areas. An update on applying Computational Fluid Dynamics (CFD in smoke exhaust design will be presented in this paper. Key points to note in CFD simulations on smoke filling due to a fire in a big hall will be discussed. Mathematical aspects concerning of discretization of partial differential equations and algorithms for solving the velocity-pressure linked equations are briefly outlined. Results predicted by CFD with different free boundary conditions are compared with those on room fire tests. Standards on grid size, relaxation factors, convergence criteria, and false diffusion should be set up for numerical experiments with CFD.

  6. Quantum anomalous Hall effect in 2D organic topological insulators. (United States)

    Wang, Z F; Liu, Zheng; Liu, Feng


    The quantum anomalous Hall effect (QAHE) is a fundamental transport phenomenon in the field of condensed-matter physics. Without an external magnetic field, spontaneous magnetization combined with spin-orbit coupling gives rise to a quantized Hall conductivity. So far, a number of theoretical proposals have been made to realize the QAHE, but all based on inorganic materials. Here, using first-principles calculations, we predict a family of 2D organic topological insulators for realizing the QAHE. Designed by assembling molecular building blocks of triphenyl-transition-metal compounds into a hexagonal lattice, this new class of organic materials is shown to have a nonzero Chern number and exhibits a gapless chiral edge state within the Dirac gap.

  7. Can ensemble condition in a hall be improved and measured?

    DEFF Research Database (Denmark)

    Gade, Anders Christian


    of the ceiling reflectors; and (c) changing the position of the orchestra on the platform. These variables were then tested in full scale experiments in the hall including subjective evaluation by the orchestra in order to verify their effects under practical conditions. New objective parameters, which showed......In collaboration with the Danish Broadcasting Corporation an extensive series of experiments has been carried out in The Danish Radio Concert Hall with the practical purpose of trying to improve the ensemble conditions on the platform for the resident symphony orchestra. First, a series...... of experiments in a 1:20 scale model indicated that among several suggested means the following would be the most effective and acceptable: (a) changing the shape of the sidewalls in the platform area in order to make them reflect sound back to the musicians more effectively; (b) lowering and redesigning...

  8. Quantum Hall effect in epitaxial graphene with permanent magnets. (United States)

    Parmentier, F D; Cazimajou, T; Sekine, Y; Hibino, H; Irie, H; Glattli, D C; Kumada, N; Roulleau, P


    We have observed the well-kown quantum Hall effect (QHE) in epitaxial graphene grown on silicon carbide (SiC) by using, for the first time, only commercial NdFeB permanent magnets at low temperature. The relatively large and homogeneous magnetic field generated by the magnets, together with the high quality of the epitaxial graphene films, enables the formation of well-developed quantum Hall states at Landau level filling factors v = ±2, commonly observed with superconducting electro-magnets. Furthermore, the chirality of the QHE edge channels can be changed by a top gate. These results demonstrate that basic QHE physics are experimentally accessible in graphene for a fraction of the price of conventional setups using superconducting magnets, which greatly increases the potential of the QHE in graphene for research and applications.

  9. Spin Hall effect-driven spin torque in magnetic textures

    KAUST Repository

    Manchon, Aurelien


    Current-induced spin torque and magnetization dynamics in the presence of spin Hall effect in magnetic textures is studied theoretically. The local deviation of the charge current gives rise to a current-induced spin torque of the form (1 - ΒM) × [(u 0 + αH u 0 M) ∇] M, where u0 is the direction of the injected current, H is the Hall angle and is the non-adiabaticity parameter due to spin relaxation. Since αH and ×can have a comparable order of magnitude, we show that this torque can significantly modify the current-induced dynamics of both transverse and vortex walls. © 2011 American Institute of Physics.

  10. Admittance measurements in the quantum Hall effect regime

    Energy Technology Data Exchange (ETDEWEB)

    Hernández, C., E-mail: [Departamento de Física, Universidad Militar Nueva Granada, Carrera 11 # 101-80, Bogotá D.C. (Colombia); Laboratorio de Magnetismo, Departamento de Física, Universidad de los Andes, A.A. 4976, Bogotá D.C. (Colombia); Consejo, C.; Chaubet, C. [Laboratoire Charles Coulomb L2C, Université Montpellier II, Pl. E. Bataillon, 34095 Montpellier Cedex 5 (France)


    In this work we present an admittance study of a two-dimensional electron gas (2DEG) in the quantum Hall effect (QHE) regime. We have studied several Hall bars in different contacts configurations in the frequency range 100 Hz–1 MHz. Our interpretation is based on the Landauer–Büttiker theory and takes into account both the capacitance and the topology of the coaxial cables which are connected to the sample holder. We show that we always observe losses through the capacitive impedance of the coaxial cables, except in the two contacts configuration in which the cable capacitance does not influence the admittance measurement of the sample. In this case, we measure the electrochemical capacitance of the 2DEG and show its dependence with the filling factor ν.

  11. Hall hole mobility in boron-doped homoepitaxial diamond (United States)

    Pernot, J.; Volpe, P. N.; Omnès, F.; Muret, P.; Mortet, V.; Haenen, K.; Teraji, T.


    Hall hole mobility of boron-doped homoepitaxial (100) diamond samples has been investigated in the temperature range of 100-900 K, both experimentally and theoretically. The temperature dependence of the mobility measured in high-quality and low boron-doped materials was compared with theoretical calculations to determine the phonon-hole coupling constants (deformation potential for acoustic phonons and coupling constant for optical phonons). The maximum hole mobility is found to be close to 2000cm2/Vs at room temperature. For boron-doped material, the hole scattering by neutral boron atoms is shown to be important in diamond due to the high ionization energy of the boron acceptor. The doping dependence of the Hall hole mobility is established for boron-doping levels ranging between 1014 and 1020cm-3 at 300 and 500 K. The physical reasons which make diamond a semiconductor with a higher mobility than other semiconductors of column IV are discussed.

  12. Anomalous Hall effect scaling in ferromagnetic thin films

    KAUST Repository

    Grigoryan, Vahram L.


    We propose a scaling law for anomalous Hall effect in ferromagnetic thin films. Our approach distinguishes multiple scattering sources, namely, bulk impurity, phonon for Hall resistivity, and most importantly the rough surface contribution to longitudinal resistivity. In stark contrast to earlier laws that rely on temperature- and thickness-dependent fitting coefficients, this scaling law fits the recent experimental data excellently with constant parameters that are independent of temperature and film thickness, strongly indicating that this law captures the underlying physical processes. Based on a few data points, this scaling law can even fit all experimental data in full temperature and thickness range. We apply this law to interpret the experimental data for Fe, Co, and Ni and conclude that (i) the phonon-induced skew scattering is unimportant as expected; (ii) contribution from the impurity-induced skew scattering is negative; (iii) the intrinsic (extrinsic) mechanism dominates in Fe (Co), and both the extrinsic and intrinsic contributions are important in Ni.

  13. Extraordinary Hall-effect in colloidal magnetic nanoparticle films

    Energy Technology Data Exchange (ETDEWEB)

    Ben Gur, Leah; Tirosh, Einat [School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 6997801 (Israel); Segal, Amir [School of Physics, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 6997801 (Israel); Markovich, Gil, E-mail: [School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 6997801 (Israel); Gerber, Alexander, E-mail: [School of Physics, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 6997801 (Israel)


    Colloidal nickel nanoparticles (NPs) coated with polyvinylpyrrolidone (PVP) were synthesized. The nanoparticle dispersions were deposited on substrates and dried under mild heating to form conductive films. The films exhibited very small coercivity, nearly metallic conductivity, and a significant extraordinary Hall effect signal. This method could be useful for preparing simple, printed magnetic field sensors with the advantage of relatively high sensitivity around zero magnetic field, in contrast to magnetoresistive sensors, which have maximal field sensitivity away from zero magnetic field. - Highlights: • Ni nanoparticle ink capable of forming conductive films on drying. • The Ni nanoparticle films exhibit significant extraordinary Hall effect. • This system could be used for preparing printed magnetic field sensors integrated in 3D printed structures.

  14. Dissipative quantum hall effect in graphene near the Dirac point. (United States)

    Abanin, Dmitry A; Novoselov, Kostya S; Zeitler, Uli; Lee, Patrick A; Geim, A K; Levitov, L S


    We report on the unusual nature of the nu=0 state in the integer quantum Hall effect (QHE) in graphene and show that electron transport in this regime is dominated by counterpropagating edge states. Such states, intrinsic to massless Dirac quasiparticles, manifest themselves in a large longitudinal resistivity rho(xx) > or approximately h/e(2), in striking contrast to rho(xx) behavior in the standard QHE. The nu=0 state in graphene is also predicted to exhibit pronounced fluctuations in rho(xy) and rho(xx) and a smeared zero Hall plateau in sigma(xy), in agreement with experiment. The existence of gapless edge states puts stringent constraints on possible theoretical models of the nu=0 state.

  15. Quantum Beats of Resonant Tunneling between Fractional Quantum Hall Edges (United States)

    Maasilta, Ilari J.; Goldman, V. J.


    We report measurements of resonant tunneling between two fractional quantum Hall edges in a quantum antidot geometry (I. J. Maasilta and V. J. Goldman, to appear in Phys. Rev. B 55),(1997).. We observe beats in the conductance oscillations, whose evolution as a function of experimental parameters is discussed. Possible explanations in terms of different models (G. Kirczenow Phys. Rev. B 53), 15767 (1996), M. Geller et. al, preprint. are presented.

  16. Suitable reverberation time for halls for rock and pop music


    Adelman-Larsen, Niels Werner; Thompson, Eric Robert; Gade, Anders Christian


    The existing body of literature regarding the acoustic design of concert halls has focused almost exclusively on classical music, although there are many more performances of popular music, including rock and pop. Objective measurements were made of the acoustics of 20 rock music venues in Denmark and a questionnaire was used in a subjective assessment of those venues with professional rock musicians and sound engineers as expert listeners. Correlations between the measurements show that clar...

  17. Extraordinary Hall-effect in colloidal magnetic nanoparticle films (United States)

    Ben Gur, Leah; Tirosh, Einat; Segal, Amir; Markovich, Gil; Gerber, Alexander


    Colloidal nickel nanoparticles (NPs) coated with polyvinylpyrrolidone (PVP) were synthesized. The nanoparticle dispersions were deposited on substrates and dried under mild heating to form conductive films. The films exhibited very small coercivity, nearly metallic conductivity, and a significant extraordinary Hall effect signal. This method could be useful for preparing simple, printed magnetic field sensors with the advantage of relatively high sensitivity around zero magnetic field, in contrast to magnetoresistive sensors, which have maximal field sensitivity away from zero magnetic field.


    Bekker, Marthinus J; Cumming, Tania D; Osborne, Nikola K.P; Bruining, Angela M; McClean, Julia I; Leland, Louis S


    This experiment investigated the combined use of visual prompts, daily feedback, and rewards to reduce electricity consumption in a university residential hall. After a 17-day baseline period, the experimental intervention was introduced in the intervention hall, and no change was made in the control hall. Energy usage decreased in the intervention hall, but energy usage did not change appreciably in the control hall. In the intervention hall, mean daytime and nighttime savings were 16.2% and 10.7%, respectively, compared to savings of 3.8% (day) and 6.5% (night) in the control hall. PMID:21119909

  19. Direct comparison of fractional and integer quantized Hall resistance (United States)

    Ahlers, Franz J.; Götz, Martin; Pierz, Klaus


    We present precision measurements of the fractional quantized Hall effect, where the quantized resistance {{R}≤ft[ 1/3 \\right]} in the fractional quantum Hall state at filling factor 1/3 was compared with a quantized resistance {{R}[2]} , represented by an integer quantum Hall state at filling factor 2. A cryogenic current comparator bridge capable of currents down to the nanoampere range was used to directly compare two resistance values of two GaAs-based devices located in two cryostats. A value of 1-(5.3  ±  6.3) 10-8 (95% confidence level) was obtained for the ratio ({{R}≤ft[ 1/3 \\right]}/6{{R}[2]} ). This constitutes the most precise comparison of integer resistance quantization (in terms of h/e 2) in single-particle systems and of fractional quantization in fractionally charged quasi-particle systems. While not relevant for practical metrology, such a test of the validity of the underlying physics is of significance in the context of the upcoming revision of the SI.

  20. Sound quality (SQ) of concert halls: Physical and subjective attributes (United States)

    Beranek, Leo L.


    Each new concert hall has the following stated goal: ``Acoustics equal to the best in the world.'' The owner can specify the number of seats, areas of public spaces, lighting intensities, etc. But, the attributes of acoustical quality cannot as yet be specified. Most acoustical consultants seem to feel that a ``seat of the pants'' experience is the only possible specification. But the architect's goal is a monument to himself and he believes the acoustical consultant should achieve the ``best in the world'' goal without visible means. Numbers for specifications are needed. In this paper 40 years of pertinent research are described: What are the critical physical attributes of good acoustics, how do we measure them, and how can they be translated into architectural specifications? Four steps have been involved: (1) interviews of conductors and music critics to determine (a) their acoustical rank orderings of a large number of halls and (b) which acoustical characteristics do they believe are important, viz., reverberance, strength of sound, etc.; (2) a determination of which physical measures correlate with their beliefs plus others that are physiologically important; (3) measurements of those physical quantities in the rank-ordered halls; and (5) the correlation of the measured values with the subjective quality ratings.

  1. Symmetry-protected quantum spin Hall phases in two dimensions. (United States)

    Liu, Zheng-Xin; Wen, Xiao-Gang


    Symmetry-protected topological (SPT) states are short-range entangled states with symmetry. Nontrivial SPT states have symmetry-protected gapless edge excitations. In 2 dimension (2D), there are an infinite number of nontrivial SPT phases with SU(2) or SO(3) symmetry. These phases can be described by SU(2) or SO(3) nonlinear-sigma models with a quantized topological θ term. At an open boundary, the θ term becomes the Wess-Zumino-Witten term and consequently the boundary excitations are decoupled gapless left movers and right movers. Only the left movers (if θ>0) carry the SU(2) or SO(3) quantum numbers. As a result, the SU(2) SPT phases have a half-integer quantized spin Hall conductance and the SO(3) SPT phases have an even-integer quantized spin Hall conductance. Both the SU(2) and SO(3) SPT phases are symmetric under their U(1) subgroup and can be viewed as U(1) SPT phases with even-integer quantized Hall conductance.

  2. Mission and System Advantages of Iodine Hall Thrusters (United States)

    Dankanich, John W.; Szabo, James; Pote, Bruce; Oleson, Steve; Kamhawi, Hani


    The exploration of alternative propellants for Hall thrusters continues to be of interest to the community. Investments have been made and continue for the maturation of iodine based Hall thrusters. Iodine testing has shown comparable performance to xenon. However, iodine has a higher storage density and resulting higher ?V capability for volume constrained systems. Iodine's vapor pressure is low enough to permit low-pressure storage, but high enough to minimize potential adverse spacecraft-thruster interactions. The low vapor pressure also means that iodine does not condense inside the thruster at ordinary operating temperatures. Iodine is safe, it stores at sub-atmospheric pressure, and can be stored unregulated for years on end; whether on the ground or on orbit. Iodine fills a niche for both low power (10kW) electric propulsion regimes. A range of missions have been evaluated for direct comparison of Iodine and Xenon options. The results show advantages of iodine Hall systems for both small and microsatellite application and for very large exploration class missions.

  3. Magnetic mirror effect in a cylindrical Hall thruster (United States)

    Jiang, Yiwei; Tang, Haibin; Ren, Junxue; Li, Min; Cao, Jinbin


    For cylindrical Hall thrusters, the magnetic field geometry is totally different from that in conventional Hall thrusters. In this study, we investigate the magnetic mirror effect in a fully cylindrical Hall thruster by changing the number of iron rings (0–5), which surround the discharge channel wall. The plasma properties inside the discharge channel and plume area are simulated with a self-developed PIC-MCC code. The numerical results show significant influence of magnetic geometry on the electron confinement. With the number of rings increasing above three, the near-wall electron density gap is reduced, indicating the suppression of neutral gas leakage. The electron temperature inside the discharge channel reaches its peak (38.4 eV) when the magnetic mirror is strongest. It is also found that the thruster performance has strong relations with the magnetic mirror as the propellant utilisation efficiency reaches the maximum (1.18) at the biggest magnetic mirror ratio. Also, the optimal magnetic mirror improves the multi-charged ion dynamics, including the ion production and propellant utilisation efficiency.

  4. Stability of the Hall sensors performance under neutron irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Duran, I.; Hron, M.; Stockel, J. [Institute of Plasma Physics, Association EURATOM/IPP.CR, Praha (Czech Republic); Viererbl, L.; Vsolak, R.; Cerva, V. [Nuclear Research Institute plc (Czech Republic); Bolshakova, I.; Holyaka, R. [Lviv Polytechnic National Univ. (Ukraine); Vayakis, G. [ITER International Team, Naka Joint Work Site, Naka, Ibaraki (Japan)


    A principally new diagnostic method must be developed for magnetic measurements in steady state regime of operation of fusion reactor. One of the options is the use of transducers based on Hall effect. The use of Hall sensors in ITER is presently limited by their questionable radiation and thermal stability. Issues of reliable operation in ITER like radiation and thermal environment are addressed in the paper. The results of irradiation tests of candidate Hall sensors in LVR-15 and IBR-2 experimental fission reactors are presented. Stable operation (deterioration of sensitivity below one percent) of the specially prepared sensors was demonstrated during irradiation by the total fluence of 3.10{sup 16} n/cm{sup 2} in IBR-2 reactor. Increasing the total neutron fluence up to 3.10{sup 17} n/cm{sup 2} resulted in deterioration of the best sensor's output still below 10% as demonstrated during irradiation in LVR-15 fission reactor. This level of neutron is already higher than the expected ITER life time neutron fluence for a sensor location just outside the ITER vessel. (authors)

  5. Topological thermal Hall effect in frustrated kagome antiferromagnets (United States)

    Owerre, S. A.


    In frustrated magnets the Dzyaloshinsky-Moriya interaction (DMI) arising from spin-orbit coupling can induce a magnetic long-range order. Here, we report a theoretical prediction of the thermal Hall effect in frustrated kagome magnets such as KCr3(OH) 6(SO4) 2 and KFe3(OH) 6(SO4)2 . The thermal Hall effects in these materials are induced by scalar spin chirality as opposed to DMI in previous studies. The scalar spin chirality originates from the magnetic-field-induced chiral spin configuration due to noncoplanar spin textures, but in general it can be spontaneously developed as a macroscopic order parameter in chiral quantum spin liquids. Therefore, we infer that there is a possibility of the thermal Hall effect in frustrated kagome magnets such as herbertsmithite ZnCu3(OH) 6Cl2 and the chromium compound Ca10Cr7O28 , although they also show evidence of magnetic long-range order in the presence of applied magnetic field or pressure.

  6. Typology of Retractable Roof Structures in Stadiums and Sports Halls

    Directory of Open Access Journals (Sweden)

    Andrej Mahovič


    Full Text Available Retractable roof structures are one of the four fundamental systems (in addition to the playing area, stands and facade in a stadium and sports hall. The roof protects users against various weather conditions and creates optimum circumstances for carrying out different activities. Stadiums and sports halls with retractable roof structures can host a greater variety of activities, improve the quality of their implementation and the quality of visitors’ experience, and affect the perception and experience of people using or observing such buildings. A retractable roof structure allows for natural lighting and ventilation of the venue, gives optimal conditions for grass growth on the playing field, and reduces costs of use and maintenance of the building. Different typologies of movement of roof structures (frequency of opening and closing, design of the structure, and methods of movement are categorised in terms of their architectural and structural design. Application of different retractable roof systems worldwide is indicator of their effectiveness and efficiency, and is basis for use of movement also in other fundamental systems of stadiums and sports halls. Research and identification of characteristics of retractable roof structures lead to the design of new moving systems that can with the application of the moving principle change the purpose of movable elements or assume the characteristics of other fundamental systems.

  7. Use of CFD modelling for analysing air parameters in auditorium halls (United States)

    Cichowicz, Robert


    Modelling with the use of numerical methods is currently the most popular method of solving scientific as well as engineering problems. Thanks to the use of computer methods it is possible for example to comprehensively describe the conditions in a given room and to determine thermal comfort, which is a complex issue including subjective sensations of the persons in a given room. The article presents the results of measurements and numerical computing that enabled carrying out the assessment of environment parameters, taking into consideration microclimate, temperature comfort, speeds in the zone of human presence and dustiness in auditory halls. For this purpose measurements of temperature, relative humidity and dustiness were made with the use of a digital microclimate meter and a laser dust particles counter. Thanks to the above by using the application DesignBuilder numerical computing was performed and the obtained results enabled determining PMV comfort indicator in selected rooms.

  8. Reliability enhancement of the MNP23 magnet in the East Experimental Hall

    CERN Document Server

    Bodart, D


    The MNP23 magnet is installed in the East Experimental Hall, which is a part of the PS complex located at CERN in Meyrin. It is a very compact septum magnet used to distribute the beam to the different users in the T9 line. The magnet is installed in an area exposed to high levels of ionizing radiation, and is operated at extreme water pressure and flow rate: such conditions are responsible of recurrent failures which not only produce frequent stops of the facility, but also require interventions in radioactive areas and repair of very radioactive components. Since 1970 three different designs have been attempted, all resulting in a poor reliability. This paper reports about a new modification of the magnet which has been implemented in 2010 and should ensure, in principle, a definitive fix to the problems encountered so far.

  9. Use of CFD modelling for analysing air parameters in auditorium halls

    Directory of Open Access Journals (Sweden)

    Cichowicz Robert


    Full Text Available Modelling with the use of numerical methods is currently the most popular method of solving scientific as well as engineering problems. Thanks to the use of computer methods it is possible for example to comprehensively describe the conditions in a given room and to determine thermal comfort, which is a complex issue including subjective sensations of the persons in a given room. The article presents the results of measurements and numerical computing that enabled carrying out the assessment of environment parameters, taking into consideration microclimate, temperature comfort, speeds in the zone of human presence and dustiness in auditory halls. For this purpose measurements of temperature, relative humidity and dustiness were made with the use of a digital microclimate meter and a laser dust particles counter. Thanks to the above by using the application DesignBuilder numerical computing was performed and the obtained results enabled determining PMV comfort indicator in selected rooms.

  10. Semitransparent anisotropic and spin Hall magnetoresistance sensor enabled by spin-orbit torque biasing (United States)

    Yang, Yumeng; Xu, Yanjun; Xie, Hang; Xu, Baoxi; Wu, Yihong


    We demonstrate an ultrathin and semitransparent anisotropic and spin Hall magnetoresistance sensor based on NiFe/Pt heterostructures. The use of a spin-orbit torque effective field for transverse biasing allows us to reduce the total thickness of the sensors down to 3-4 nm, thereby leading to the semitransparency. Despite the extremely simple design, the spin-orbit torque effective field biased NiFe/Pt sensor exhibits levels of linearity and sensitivity comparable to those of sensors using more complex linearization schemes. In a proof-of-concept design using a full Wheatstone bridge comprising four sensing elements, we obtained a sensitivity up to 202.9 mΩ Oe-1, a linearity error below 5%, and a detection limit down to 20 nT. The transmittance of the sensor is over 50% in the visible range.

  11. Experiments on Quantum Hall Topological Phases in Ultra Low Temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Du, Rui-Rui [Rice Univ., Houston, TX (United States). Dept. of Physics and Astronomy


    This project is to cool electrons in semiconductors to extremely low temperatures and to study new states of matter formed by low-dimensional electrons (or holes). At such low temperatures (and with an intense magnetic field), electronic behavior differs completely from ordinary ones observed at room temperatures or regular low temperature. Studies of electrons at such low temperatures would open the door for fundamental discoveries in condensed matter physics. Present studies have been focused on topological phases in the fractional quantum Hall effect in GaAs/AlGaAs semiconductor heterostructures, and the newly discovered (by this group) quantum spin Hall effect in InAs/GaSb materials. This project consists of the following components: 1) Development of efficient sample cooling techniques and electron thermometry: Our goal is to reach 1 mK electron temperature and reasonable determination of electron temperature; 2) Experiments at ultra-low temperatures: Our goal is to understand the energy scale of competing quantum phases, by measuring the temperature-dependence of transport features. Focus will be placed on such issues as the energy gap of the 5/2 state, and those of 12/5 (and possible 13/5); resistive signature of instability near 1/2 at ultra-low temperatures; 3) Measurement of the 5/2 gaps in the limit of small or large Zeeman energies: Our goal is to gain physics insight of 5/2 state at limiting experimental parameters, especially those properties concerning the spin polarization; 4) Experiments on tuning the electron-electron interaction in a screened quantum Hall system: Our goal is to gain understanding of the formation of paired fractional quantum Hall state as the interaction pseudo-potential is being modified by a nearby screening electron layer; 5) Experiments on the quantized helical edge states under a strong magnetic field and ultralow temperatures: our goal is to investigate both the bulk and edge states in a quantum spin Hall insulator under

  12. Chip-Based Measurements of Brownian Relaxation of Magnetic Beads Using a Planar Hall Effect Magnetic Field Sensor

    DEFF Research Database (Denmark)

    Østerberg, Frederik Westergaard; Dalslet, Bjarke Thomas; Snakenborg, Detlef


    We present a simple 'click-on' fluidic system with integrated electrical contacts, which is suited for electrical measurements on chips in microfluidic systems. We show that microscopic magnetic field sensors based on the planar Hall effect can be used for detecting the complex magnetic response...... using only the self-field arising from the bias current applied to the sensors as excitation field. We present measurements on a suspension of magnetic beads with a nominal diameter of 250 nm vs. temperature and find that the observations are consistent with the Cole-Cole model for Brownian relaxation...... biosensor based on the detection of the dynamic response of magnetic beads....

  13. Teaching Complex Organizations: A Survey Essay. (United States)

    Dobratz, Betty


    Briefly reviews six textbooks for teaching about complex organizations: ORGANIZATIONS: STRUCTURES, PROCESSES, AND OUTCOMES (Hall, 1987); ORGANIZATIONS: RATIONAL, NATURAL, AND OPEN SYSTEMS (Scott, 1987); ORGANIZATIONS IN SOCIETY (Etzioni, 1985); ORGANIZATIONAL BEHAVIOR (Hellriegel et al, 1986); ORGANIZATIONAL BEHAVIOR: EXPERIENCES AND CASES (Hai,…

  14. Spin disorder effect in anomalous Hall effect in MnGa (United States)

    Mendonça, A. P. A.; Varalda, J.; Schreiner, W. H.; Mosca, D. H.


    We report on resistivity and Hall effect in MnGa thin films grown by molecular beam epitaxy on GaAs substrates. Highly (1 1 1)-textured MnGa film with L10 structure exhibits hard magnetic properties with coercivities as high as 20 kOe and spin disorder mechanisms contributing to the Hall conductivity at room temperature. Density functional theory calculations were performed to determine the intrinsic Berry curvature in the momentum space with chiral spin structure that results in an anomalous Hall conductivity of 127 (Ωcm)-1 comparable to that measured at low temperature. In addition to residual and side-jump contributions, which are enhanced by thermal activation, both anomalous Hall conductivity and Hall angle increase between 100 K and room temperature. The present results reinforce the potential of Mn-Ga system for developing Hall effect-based spintronic devices.

  15. Interactions, disorder and spin waves in quantum Hall ferromagnets near integer filling

    CERN Document Server

    Rapsch, S


    dynamics is discussed in chapter 5 and employed to study spin waves in a domain wall structure. A hydrodynamic theory of spin waves is used to treat long-wavelength excitations of randomly disordered quantum Hall ferromagnets. Finally, the contribution of spin waves to the optical conductivity is studied in chapter 6. Predictions are made for the experimental signatures of spin waves in disordered quantum Hall systems. The observability of these signatures is discussed both for transport measurements and NMR experiments. The interplay between exchange interactions and disorder is studied in quantum Hall ferromagnets near integer filling. Both analytical and numerical methods are used to investigate a non-linear sigma model of these systems in the limit of vanishing Zeeman coupling and at zero temperature. Chapter 1 gives an introduction to the quantum Hall effect and to quantum Hall ferromagnets in particular. A brief review of existing work on disordered quantum Hall systems is included. In chapters 2-4, the...

  16. Theory of pairing symmetry in the vortex states

    NARCIS (Netherlands)

    Yokoyama, Takehito; Ichioka, Yukio; Yanaka, Yukio; Golubov, Alexandre Avraamovitch


    We investigate pairing symmetry in an Abrikosov vortex and vortex lattice. It is shown that the Cooper pair wave function at the center of an Abrikosov vortex with vorticity m has a different parity with respect to frequency from that in the bulk if m is an odd number, while it has the same parity

  17. Ferroelectric nanostructure having switchable multi-stable vortex states (United States)

    Naumov, Ivan I [Fayetteville, AR; Bellaiche, Laurent M [Fayetteville, AR; Prosandeev, Sergey A [Fayetteville, AR; Ponomareva, Inna V [Fayetteville, AR; Kornev, Igor A [Fayetteville, AR


    A ferroelectric nanostructure formed as a low dimensional nano-scale ferroelectric material having at least one vortex ring of polarization generating an ordered toroid moment switchable between multi-stable states. A stress-free ferroelectric nanodot under open-circuit-like electrical boundary conditions maintains such a vortex structure for their local dipoles when subject to a transverse inhomogeneous static electric field controlling the direction of the macroscopic toroidal moment. Stress is also capable of controlling the vortex's chirality, because of the electromechanical coupling that exists in ferroelectric nanodots.

  18. Optimal Volume for Concert Halls Based on Ando’s Subjective Preference and Barron Revised Theories

    Directory of Open Access Journals (Sweden)

    Salvador Cerdá


    Full Text Available The Ando-Beranek’s model, a linear version of Ando’s subjective preference theory, obtained by the authors in a recent work, was combined with Barron revised theory. An optimal volume region for each reverberation time was obtained for classical music in symphony orchestra concert halls. The obtained relation was tested with good agreement with the top rated halls reported by Beranek and other halls with reported anomalies.

  19. Spin Hall effects for cold atoms in a light induced gauge potential

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Shi-Liang; /Michigan U., MCTP /South China Normal U.; Fu, Hao; /Michigan U., MCTP; Wu, C.-J.; /Santa Barbara, KITP; Zhang, S.-C.; /Stanford U., Phys. Dept.; Duan, L.-M. /Michigan U., MCTP


    We propose an experimental scheme to observe spin Hall effects with cold atoms in a light induced gauge potential. Under an appropriate configuration, the cold atoms moving in a spatially varying laser field experience an effective spin-dependent gauge potential. Through numerical simulation, we demonstrate that such a gauge field leads to observable spin Hall currents under realistic conditions. We also discuss the quantum spin Hall state in an optical lattice.

  20. Comparisons between Computer Simulations of Room Acoustical Parameters and those Measured in Concert Halls

    DEFF Research Database (Denmark)

    Rindel, Jens Holger; Shiokawa, Hiroyoshi; Christensen, Claus Lynge


    A number of European concert halls were surveyed in 1989. In this paper comparisons are made between measured room acoustical parameters and those obtained from computer simulations using the ODEON program version 3.1 on two concert halls. One is Musikverein in Vienna and the other is Concertgebouw...... in Amsterdam. Comparisons are also made between the results obtained from computer simulations using models with high geometrical fidelity and those from models with simplifications to geometry on both concert halls....

  1. Low-Cost High-Performance Hall Thruster Support System Project (United States)

    National Aeronautics and Space Administration — Colorado Power Electronics (CPE) has built an innovative modular power processing unit (PPU) for Hall Thrusters, including discharge, magnet, heater and keeper...

  2. Anisotropic anomalous Hall effect in triangular itinerant ferromagnet Fe3GeTe2 (United States)

    Wang, Yihao; Xian, Cong; Wang, Jian; Liu, Bingjie; Ling, Langsheng; Zhang, Lei; Cao, Liang; Qu, Zhe; Xiong, Yimin


    Magnetic frustrated materials are of great interest for their novel spin-dependent transport properties. We report an anisotropic anomalous Hall effect in the triangular itinerant ferromagnet Fe3GeTe2 . When the current flows along the a b plane, Fe3GeTe2 exhibits the conventional anomalous Hall effect below the Curie temperature Tc, which can be depicted by Karplus-Luttinger theory. On the other hand, the topological Hall effect shows up below Tc with current along the c axis. The enhancement of Hall resistivity can be attributed to the chiral effect during the spin-flop process.

  3. Photoproduction of Light and Exotic Mesons in Hall D (United States)

    Meyer, Curtis


    The Jefferson Lab Hall D collaboration is proposing a program to search for and study gluonic excitations of mesons using 8-9 GeV linearly polarized photon beams. By extending the nearly non-existent meson data in photoproduction, as well as taking advantage of a spin 1 probe, we expect to be able to produce and study hybrid mesons with exotic, or non q-barq quantum numbers. The properties of these mesons yield information on the dynamic nature of gluons, and yield information on the issue of confinement.

  4. Hall Plateaus at magic angles in ultraquantum Bismuth (United States)

    Benoît, Fauqué.


    The behaviour of a three-dimensional electron gas in the presence of a magnetic field strong enough to put all carriers in the first Landau level (i.e. beyond the quantum limit) is a longstanding question of theoretical condensed matter physics [1]. This issue has been recently explored by two high-field experiments on elemental semi-metal Bismuth. In a first study of transport coefficients (which are dominated by hole-like carriers), the Nernst coefficient presented three unexpected maxima that are concomitant with quasi-plateaux in the Hall coefficient [2]. In a second series of experiments, torque magnetometry (which mainly probes the three Dirac valley electron pockets) detected a field-induced phase transition [3]. The full understanding of the electron and hole behaviours above the quantum limit of pure Bi is therefore still under debate. In this talk, we will present our measurement of the Hall resistivity and torque magnetometry with magnetic field up to 31 T and rotating in the trigonal-bisectrix plane [4]. The Hall response is dominated by the hole pockets according to its sign as well as the period and the angular dependence of its quantum oscillations. In the vicinity of the quantum limit, it presents additional anomalies which are the fingerprints of the electron pockets. We found that for particular orientations of the magnetic field (namely ``magic angles''), the Hall response becomes field-independent within the experimental resolution around 20T. This drastic dependence of the plateaux on the field orientation provides strong constraints for theoretical scenarios. [4pt] [1] Bertrand I. Halperin, Japanese Journal of Applied Physics, 26, Supplement 26-3 (1987).[0pt] [2] Kamran Behnia, Luis Balicas, Yakov Kopelevich, Science, 317, 1729 (2008).[0pt] [3] Lu Li, J. G. Checkelsky, Y. S. Hor, C. Uher, A. F. Hebard, R. J. Cava, and N. P. Ong , Science, 321, 5888 (2008).[0pt] [4] Benoît Fauqu'e, Luis Balicas, Ilya Sheikin, Jean Paul Issi and Kamran Behnia

  5. Topological Hall conductivity of vortex and skyrmion spin textures

    Energy Technology Data Exchange (ETDEWEB)

    Jalil, M. B. A., E-mail:; Ghee Tan, Seng [Department of Electrical and Computer Engineering, National University of Singapore, 1 Engineering Drive 3, Singapore 117576 (Singapore); Data Storage Institute, Agency for Science, Technology and Research (A-STAR), DSI Building, 5 Engineering Drive 1, Singapore 117608 (Singapore); Eason, Kwaku; Kong, Jian Feng [Data Storage Institute, Agency for Science, Technology and Research (A-STAR), DSI Building, 5 Engineering Drive 1, Singapore 117608 (Singapore)


    We analyze the topological Hall conductivity experienced by conduction electrons whose spins are strongly coupled to axially symmetric spin textures, such as magnetic vortex and skyrmion of types I and II, theoretically by gauge theory, and numerically via micromagnetic simulations. The numerical results are in agreement with the theoretical predictions. Divergence between the two is seen when the vortex/skyrmion core radius is comparable or larger than the element size, and when the skyrmion configuration breaks down at high Dzyaloshinskii-Moriya interaction strength.

  6. Subjective ranking of concert halls substantiated through orthogonal objective parameters. (United States)

    Cerdá, Salvador; Giménez, Alicia; Cibrián, Rosa; Girón, Sara; Zamarreño, Teófilo


    This paper studies the global subjective assessment, obtained from mean values of the results of surveys addressed to members of the audience of live concerts in Spanish auditoriums, through the mean values of the three orthogonal objective parameters (Tmid, IACCE3, and LEV), expressed in just noticeable differences (JNDs), regarding the best-valued hall. Results show that a linear combination of the relative variations of orthogonal parameters can largely explain the overall perceived quality of the sample. However, the mean values of certain orthogonal parameters are not representative, which shows that an alternative approach to the problem is necessary. Various possibilities are proposed.

  7. Redundant speed control for brushless Hall effect motor (United States)

    Nola, F. J. (Inventor)


    A speed control system for a brushless Hall effect device equipped direct current (D.C.) motor is described. Separate windings of the motor are powered by separate speed responsive power sources. A change in speed, upward or downward, because of the failure of a component of one of the power sources results in a corrective signal being generated in the other power source to supply an appropriate power level and polarity to one winding to cause the motor to be corrected in speed.

  8. Hall-Petch relationship in a nanotwinned nickel alloy

    Energy Technology Data Exchange (ETDEWEB)

    Shaw, Leon L. [Department of Chemical, Materials and Biomolecular Engineering, University of Connecticut, Storrs, CT 06269 (United States)], E-mail:; Ortiz, Angel L. [Departamento de Ingenieria Mecanica, Energetica y de los Materiales Universidad de Extremadura, 06071 Badajoz (Spain); Villegas, Juan C. [Intel Corporation, Chandler, AZ 85226 (United States)


    The Hall-Petch relationship in a nanotwinned alloy with absence of dislocation pile-ups is investigated for the first time. It is shown that, when the twin spacing is large (d > 150 nm), the hardness exhibits a d{sup -1/2} dependence. However, when the twin spacing is small (d < 100 nm), a d{sup -1} dependence results. These phenomena are interpreted based on dislocation-mediated mechanisms corroborated by the analysis of electron microscopy and X-ray diffractometry.

  9. TOPICAL REVIEW: Spin current, spin accumulation and spin Hall effect

    Directory of Open Access Journals (Sweden)

    Saburo Takahashi and Sadamichi Maekawa


    Full Text Available Nonlocal spin transport in nanostructured devices with ferromagnetic injector (F1 and detector (F2 electrodes connected to a normal conductor (N is studied. We reveal how the spin transport depends on interface resistance, electrode resistance, spin polarization and spin diffusion length, and obtain the conditions for efficient spin injection, spin accumulation and spin current in the device. It is demonstrated that the spin Hall effect is caused by spin–orbit scattering in nonmagnetic conductors and gives rise to the conversion between spin and charge currents in a nonlocal device. A method of evaluating spin–orbit coupling in nonmagnetic metals is proposed.

  10. Microwave generation by spin Hall nanooscillators with nanopatterned spin injector

    Energy Technology Data Exchange (ETDEWEB)

    Zholud, A., E-mail:; Urazhdin, S. [Department of Physics, Emory University, Atlanta, Georgia 30322 (United States)


    We experimentally study spin Hall nano-oscillators based on Pt/ferromagnet bilayers with nanopatterned Pt spin injection layer. We demonstrate that both the spectral characteristics and the electrical current requirements can be simultaneously improved by reducing the spin injection area. Moreover, devices with nanopatterned Pt spin injector exhibit microwave generation over a wide temperature range that extends to room temperature. Studies of devices with additional Pt spacers under the device electrodes show that the oscillation characteristics are affected not only by the spin injection geometry but also by the effects of Pt/ferromagnet interface on the dynamical properties of the ferromagnet.

  11. Gaussian free fields at the integer quantum Hall plateau transition

    Energy Technology Data Exchange (ETDEWEB)

    Bondesan, R., E-mail: [Rudolf Peierls Centre for Theoretical Physics, 1 Keble Road, Oxford OX1 3NP (United Kingdom); Wieczorek, D.; Zirnbauer, M.R. [Institut für Theoretische Physik, Universität zu Köln, Zülpicher Straße 77, 50937 Köln (Germany)


    In this work we put forward an effective Gaussian free field description of critical wavefunctions at the transition between plateaus of the integer quantum Hall effect. To this end, we expound our earlier proposal that powers of critical wave intensities prepared via point contacts behave as pure scaling fields obeying an Abelian operator product expansion. Our arguments employ the framework of conformal field theory and, in particular, lead to a multifractality spectrum which is parabolic. We also derive a number of old and new identities that hold exactly at the lattice level and hinge on the correspondence between the Chalker–Coddington network model and a supersymmetric vertex model.

  12. Quantum pump in quantum spin Hall edge states (United States)

    Cheng, Fang


    We present a theory for quantum pump in a quantum spin Hall bar with two quantum point contacts (QPCs). The pump currents can be generated by applying harmonically modulating gate voltages at QPCs. The phase difference between the gate voltages introduces an effective gauge field, which breaks the time-reversal symmetry and generates pump currents. The pump currents display very different pump frequency dependence for weak and strong e-e interaction. These unique properties are induced by the helical feature of the edge states, and therefore can be used to detect and control edge state transport.

  13. Shielding evaluation of neutron generator hall by Monte Carlo simulations

    Energy Technology Data Exchange (ETDEWEB)

    Pujala, U.; Selvakumaran, T.S.; Baskaran, R.; Venkatraman, B. [Radiological Safety Division, Indira Gandhi Center for Atomic Research, Kalpakkam (India); Thilagam, L.; Mohapatra, D.K., E-mail: [Safety Research Institute, Atomic Energy Regulatory Board, Kalpakkam (India)


    A shielded hall was constructed for accommodating a D-D, D-T or D-Be based pulsed neutron generator (NG) with 4π yield of 10{sup 9} n/s. The neutron shield design of the facility was optimized using NCRP-51 methodology such that the total dose rates outside the hall areas are well below the regulatory limit for full occupancy criterion (1 μSv/h). However, the total dose rates at roof top, cooling room trench exit and labyrinth exit were found to be above this limit for the optimized design. Hence, additional neutron shielding arrangements were proposed for cooling room trench and labyrinth exits. The roof top was made inaccessible. The present study is an attempt to evaluate the neutron and associated capture gamma transport through the bulk shields for the complete geometry and materials of the NG-Hall using Monte Carlo (MC) codes MCNP and FLUKA. The neutron source terms of D-D, D-T and D-Be reactions are considered in the simulations. The effect of additional shielding proposed has been demonstrated through the simulations carried out with the consideration of the additional shielding for D-Be neutron source term. The results MC simulations using two different codes are found to be consistent with each other for neutron dose rate estimates. However, deviation up to 28% is noted between these two codes at few locations for capture gamma dose rate estimates. Overall, the dose rates estimated by MC simulations including additional shields shows that all the locations surrounding the hall satisfy the full occupancy criteria for all three types of sources. Additionally, the dose rates due to direct transmission of primary neutrons estimated by FLUKA are compared with the values calculated using the formula given in NCRP-51 which shows deviations up to 50% with each other. The details of MC simulations and NCRP-51 methodology for the estimation of primary neutron dose rate along with the results are presented in this paper. (author)

  14. Minimal Excitations in the Fractional Quantum Hall Regime (United States)

    Rech, J.; Ferraro, D.; Jonckheere, T.; Vannucci, L.; Sassetti, M.; Martin, T.


    We study the minimal excitations of fractional quantum Hall edges, extending the notion of levitons to interacting systems. Using both perturbative and exact calculations, we show that they arise in response to a Lorentzian potential with quantized flux. They carry an integer charge, thus involving several Laughlin quasiparticles, and leave a Poissonian signature in a Hanbury Brown-Twiss partition noise measurement at low transparency. This makes them readily accessible experimentally, ultimately offering the opportunity to study real-time transport of Abelian and non-Abelian excitations.

  15. Partition functions of non-Abelian quantum Hall states

    Energy Technology Data Exchange (ETDEWEB)

    Cappelli, Andrea; Viola, Giovanni, E-mail:, E-mail: [INFN, Sezione di Firenze, Via G. Sansone 1, 50019 Sesto Fiorentino (Italy)


    Partition functions of edge excitations are obtained for non-Abelian Hall states in the second Landau level, such as the anti-Read-Rezayi state, the Bonderson-Slingerland hierarchy and the Wen non-Abelian fluid, as well as for the non-Abelian spin-singlet state. The derivation is straightforward and unique starting from the non-Abelian conformal field theory data and solving the modular invariance conditions. The partition functions provide a complete account of the excitation spectrum and are used to describe experiments of Coulomb blockade and thermopower.

  16. Hard-wall confinement of a fractional quantum Hall liquid (United States)

    Macaluso, E.; Carusotto, I.


    We make use of numerical exact diagonalization calculations to explore the physics of ν =1 /2 bosonic fractional quantum Hall droplets in the presence of experimentally realistic cylindrically symmetric hard-wall potentials. This kind of confinement is found to produce very different many-body spectra compared to a harmonic trap or the so-called extremely steep limit. For a relatively weak confinement, the degeneracies are lifted and the low-lying excited states organize themselves in energy branches that can be explained in terms of their Jack polynomial representation. For a strong confinement, a strong spatial deformation of the droplet is found, with an unexpected depletion of its central density.

  17. Quantum Hall Effect (QHE) in ABA stacked trilayer graphene (United States)

    Stepanov, Petr; Barlas, Yafis; Gillgren, Nathaniel; Taniguchi, Takashi; Lau, Jeanie


    Since its experimental discovery in 2004 graphene was under extensive research as a promising counterpart of silicon for the future electronics application as well as an excellent model of 2 dimensional electron gas. Here we investigate quantum Hall effect in ABA trilayer graphene - hexagonal boron nitride heterostructures. Landau Levels (LL) crossings at low filling factors were observed and explored at different external electric fields. The formation of the QH states as an interaction of monlayer-like and bilayer-like branches will be discussed. We will present the most recent experimental results.

  18. Band structure in bulk entanglement spectrum of quantum Hall state (United States)

    Lu, Chi-Ken; Chiou, D.-W.; Lin, F.-L.

    We study the bulk entanglement spectrum of integer quantum Hall state with a symmetric checkerboard partition of space. By reformulating the correlation matrix in a guiding center representation, we show that the problem is mapped to a two-dimensional lattice with unit vector determined by the field and partition grid. The bulk entanglement spectrum shows the particle-hole symmetry and the band touching, whic are related to the dual symmetry of partition and the Chern number, respectively. The work was supported by Ministry of Science and Technology Taiwan.

  19. Conducting wall Hall thrusters in magnetic shielding and standard configurations (United States)

    Grimaud, Lou; Mazouffre, Stéphane


    Traditional Hall thrusters are fitted with boron nitride dielectric discharge channels that confine the plasma discharge. Wall properties have significant effects on the performances and stability of the thrusters. In magnetically shielded thrusters, interactions between the plasma and the walls are greatly reduced, and the potential drop responsible for ion acceleration is situated outside the channel. This opens the way to the utilization of alternative materials for the discharge channel. In this work, graphite walls are compared to BN-SiO2 walls in the 200 W magnetically shielded ISCT200-MS and the unshielded ISCT200-US Hall thrusters. The magnetically shielded thruster shows no significant change in the discharge current mean value and oscillations, while the unshielded thruster's discharge current increases by 25% and becomes noticeably less stable. The electric field profile is also investigated through laser spectroscopy, and no significant difference is recorded between the ceramic and graphite cases for the shielded thruster. The unshielded thruster, on the other hand, has its acceleration region shifted 15% of the channel length downstream. Lastly, the plume profile is measured with planar probes fitted with guard rings. Once again the material wall has little influence on the plume characteristics in the shielded thruster, while the unshielded one is significantly affected.

  20. Working with Cyril M. Harris at Benaroya Hall (United States)

    Hoover, Robert M.; Taylor, Ashton


    To contribute to a project such as Benaroya Hall, now the home of the Seattle Symphony Orchestra, as team members of acoustical giant Cyril M. Harris was a golden opportunity for Robert M. Hoover and Ashton Taylor. Their involvement in the project and association with Cyril began at the early stages of the project as consultants in noise control. During the schematic design phase, Cyril dictated to the LMN Architects design team that authority for all noise control decisions rested with Bob Hoover. This led to good working relationships, especially with the mechanical engineering firm and the air-conditioning contractor. Throughout the project, Cyril insisted upon the highest standards of materials and workmanship, and relied on the expertise of his acoustical design team, even if it went against his initial idea on some issue. At the beginning with the setting of noise criteria and in the finished building when measuring background sound, Cyril participated in the noise control process. Benaroya Hall has been critically acclaimed by the media and musicians, it was an honor for both Bob Hoover and Ashton Taylor to be part of that success.

  1. Anomalous Hall effect in Fe/Au multilayers

    KAUST Repository

    Zhang, Q.


    To understand the interfacial scattering effect on the anomalous Hall effect (AHE), we prepared multilayers of (Fe(36/n)nm/Au(12/n)nm)n using an e-beam evaporator. This structure design allowed us to investigate the effect of interfacial scattering on the AHE, while keeping the samples\\' thickness and composition unchanged. We measured the (magneto)transport properties of the samples in a wide temperature range (10–310 K) with magnetic fields up to 50 kOe. We found that the scaling between the anomalous Hall resistivity (ρAHE) and longitudinal resistivity (ρxx) can be roughly described by ρAHE∼ργxx with γ=2.65±0.10 and 1.90 ± 0.04 for samples from n=1 to n=4 and samples from n=4 to n=12, respectively. Our quantitative analysis results showed that the interfacial scattering suppresses the contribution of the intrinsic mechanism and gives rise to a side-jump contribution.

  2. Hanbury Brown and Twiss correlations in quantum Hall systems (United States)

    Campagnano, Gabriele; Zilberberg, Oded; Gornyi, Igor V.; Gefen, Yuval


    We study a Hanbury Brown and Twiss (HBT) interferometer formed with chiral edge channels of a quantum Hall system. HBT cross correlations are calculated for a device operating both in the integer and fractional quantum Hall regimes, the latter at Laughlin filling fractions. We find that in both cases, when the current is dominated by electron tunneling, current-current correlations show antibunching, characteristic of fermionic correlations. When the current-current correlations are dominated by quasiparticle tunneling, the correlations reveal bunching, characteristic of bosons. For electron tunneling, we use the Keldysh technique, and show that the result for fractional filling factors can be obtained in a simple way from the results of the integer case. It is shown that quasiparticle-dominated cross-current correlations can be analyzed by means of a quantum master-equation approach. We present here a detailed derivation of the results [Campagnano , Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.109.106802 109, 106802 (2012)] and generalize them to all Laughlin fractions.

  3. Spatially resolved Hall effect measurement in a single semiconductor nanowire (United States)

    Storm, Kristian; Halvardsson, Filip; Heurlin, Magnus; Lindgren, David; Gustafsson, Anders; Wu, Phillip M.; Monemar, Bo; Samuelson, Lars


    Efficient light-emitting diodes and photovoltaic energy-harvesting devices are expected to play an important role in the continued efforts towards sustainable global power consumption. Semiconductor nanowires are promising candidates as the active components of both light-emitting diodes and photovoltaic cells, primarily due to the added freedom in device design offered by the nanowire geometry. However, for nanowire-based components to move past the proof-of-concept stage and be implemented in production-grade devices, it is necessary to precisely quantify and control fundamental material properties such as doping and carrier mobility. Unfortunately, the nanoscale geometry that makes nanowires interesting for applications also makes them inherently difficult to characterize. Here, we report a method to carry out Hall measurements on single core-shell nanowires. Our technique allows spatially resolved and quantitative determination of the carrier concentration and mobility of the nanowire shell. As Hall measurements have previously been completely unavailable for nanowires, the experimental platform presented here should facilitate the implementation of nanowires in advanced practical devices.

  4. Parametric studies of the Hall current plasma thruster (United States)

    Ashkenazy, J.; Raitses, Y.; Appelbaum, G.


    The Hall current plasma thruster accelerates a plasma jet by an axial electric field and an applied radial magnetic field in an annular ceramic channel. A relatively large current density (>0.1 A/cm2) can be obtained as the acceleration mechanism is not limited by space charge effects. Such a device can be used as a small rocket engine on board spacecraft with the advantage of a large jet velocity compared to conventional rocket engines (10000-30000 m/s versus 2000-4800 m/s). An experimental Hall thruster was constructed and operated in a broad range of operating conditions and under various configuration variations. Electrical, magnetic and plasma diagnostics, and as well accurate thrust and gas flow rate measurements, have been used to investigate the dependence of thruster behavior on the applied voltage, gas flow rate, magnetic field, channel geometry and wall material. The studies conducted so far have demonstrated a significant effect of channel material on thruster electrical characteristics and the existence of an optimal channel length for a given flow rate. Representative results highlighting these findings are presented.

  5. Quantum Hall drag of exciton condensate in graphene (United States)

    Liu, Xiaomeng; Watanabe, Kenji; Taniguchi, Takashi; Halperin, Bertrand I.; Kim, Philip


    An exciton condensate is a Bose-Einstein condensate of electron and hole pairs bound by the Coulomb interaction. In an electronic double layer (EDL) subject to strong magnetic fields, filled Landau states in one layer bind with empty states of the other layer to form an exciton condensate. Here we report exciton condensation in a bilayer graphene EDL separated by hexagonal boron nitride. Driving current in one graphene layer generates a near-quantized Hall voltage in the other layer, resulting in coherent exciton transport. Owing to the strong Coulomb coupling across the atomically thin dielectric, quantum Hall drag in graphene appears at a temperature ten times higher than previously observed in a GaAs EDL. The wide-range tunability of densities and displacement fields enables exploration of a rich phase diagram of Bose-Einstein condensates across Landau levels with different filling factors and internal quantum degrees of freedom. The observed robust exciton condensation opens up opportunities to investigate various many-body exciton phases.

  6. Photonic spin Hall effect in metasurfaces: a brief review

    Directory of Open Access Journals (Sweden)

    Liu Yachao


    Full Text Available The photonic spin Hall effect (SHE originates from the interplay between the photon-spin (polarization and the trajectory (extrinsic orbital angular momentum of light, i.e. the spin-orbit interaction. Metasurfaces, metamaterials with a reduced dimensionality, exhibit exceptional abilities for controlling the spin-orbit interaction and thereby manipulating the photonic SHE. Spin-redirection phase and Pancharatnam-Berry phase are the manifestations of spin-orbit interaction. The former is related to the evolution of the propagation direction and the latter to the manipulation with polarization state. Two distinct forms of splitting based on these two types of geometric phases can be induced by the photonic SHE in metasurfaces: the spin-dependent splitting in position space and in momentum space. The introduction of Pacharatnam-Berry phases, through space-variant polarization manipulations with metasurfaces, enables new approaches for fabricating the spin-Hall devices. Here, we present a short review of photonic SHE in metasurfaces and outline the opportunities in spin photonics.

  7. Photovoltaic Hall Effect in Dirac systems -- Application to Graphene (United States)

    Oka, Takashi; Aoki, Hideo


    We theoretically propose to irradiate electron systems with massless Dirac dispersion with circularly polarized light, for which we predict that the photo-irradiation can induce a dc Hall effect in the absence of static, uniform magnetic fields. The effect bears a geometric origin, traced back to the non-adiabatic phase (Aharonov-Anandan phase) which is acquired by the motion of k-points in the Brilliouin zone when they encircle the Dirac cones. The Kubo formula for linear responses is extended to the nonlinear effects via the Floquet formalism for strong ac fields, which is used to calculate the photo-induced Berry curvature. The irradiation induces a dynamical gap at the Dirac point which gives rise to a universal ac Wannier-Stark ladder in Dirac systems observable in the density of states. We further use the Keldysh + Floquet method to analyze finite graphene systems, which confirms the existence of photovoltaic dc Hall effect. The required strength of the circularly polarized light to observe these effects is estimated to be O(10^7eV/m), which is within an accessible range for present laser sources. (arXiv:0807.4767)

  8. Assessment of Pole Erosion in a Magnetically Shielded Hall Thruster (United States)

    Mikellides, Ioannis G.; Ortega, Alejandro L.


    Numerical simulations of a 6-kW laboratory Hall thruster called H6 have been performed to quantify the erosion rate at the inner pole. The assessments have been made in two versions of the thruster, namely the unshielded (H6US) and magnetically shielded (H6MS) configurations. The simulations have been performed with the 2-D axisymmetric code Hall2De which employs a new multi-fluid ion algorithm to capture the presence of low-energy ions in the vicinity of the poles. It is found that the maximum computed erosion rate at the inner pole of the H6MS exceeds the measured rate of back-sputtered deposits by 4.5 times. This explains only part of the surface roughening that was observed after a 150-h wear test, which covered most of the pole area exposed to the plasma. For the majority of the pole surface the computed erosion rates are found to be below the back-sputter rate and comparable to those in the H6US which exhibited little to no sputtering in previous tests. Possible explanations for the discrepancy are discussed.

  9. Low-Mass, Low-Power Hall Thruster System (United States)

    Pote, Bruce


    NASA is developing an electric propulsion system capable of producing 20 mN thrust with input power up to 1,000 W and specific impulse ranging from 1,600 to 3,500 seconds. The key technical challenge is the target mass of 1 kg for the thruster and 2 kg for the power processing unit (PPU). In Phase I, Busek Company, Inc., developed an overall subsystem design for the thruster/cathode, PPU, and xenon feed system. This project demonstrated the feasibility of a low-mass power processing architecture that replaces four of the DC-DC converters of a typical PPU with a single multifunctional converter and a low-mass Hall thruster design employing permanent magnets. In Phase II, the team developed an engineering prototype model of its low-mass BHT-600 Hall thruster system, with the primary focus on the low-mass PPU and thruster. The goal was to develop an electric propulsion thruster with the appropriate specific impulse and propellant throughput to enable radioisotope electric propulsion (REP). This is important because REP offers the benefits of nuclear electric propulsion without the need for an excessively large spacecraft and power system.

  10. Real-space imaging of fractional quantum Hall liquids. (United States)

    Hayakawa, Junichiro; Muraki, Koji; Yusa, Go


    Electrons in semiconductors usually behave like a gas--as independent particles. However, when confined to two dimensions under a perpendicular magnetic field at low temperatures, they condense into an incompressible quantum liquid. This phenomenon, known as the fractional quantum Hall (FQH) effect, is a quantum-mechanical manifestation of the macroscopic behaviour of correlated electrons that arises when the Landau-level filling factor is a rational fraction. However, the diverse microscopic interactions responsible for its emergence have been hidden by its universality and macroscopic nature. Here, we report real-space imaging of FQH liquids, achieved with polarization-sensitive scanning optical microscopy using trions (charged excitons) as a local probe for electron spin polarization. When the FQH ground state is spin-polarized, the triplet/singlet intensity map exhibits a spatial pattern that mirrors the intrinsic disorder potential, which is interpreted as a mapping of compressible and incompressible electron liquids. In contrast, when FQH ground states with different spin polarization coexist, domain structures with spontaneous quasi-long-range order emerge, which can be reproduced remarkably well from the disorder patterns using a two-dimensional random-field Ising model. Our results constitute the first reported real-space observation of quantum liquids in a class of broken symmetry state known as the quantum Hall ferromagnet.

  11. Magnetoelectric tuning of the inverse spin-Hall effect (United States)

    Vargas, José M.; Gómez, Javier E.; Avilés-Félix, Luis; Butera, Alejandro


    We demonstrate in this article that the magnetoelectric (ME) mechanism can be exploited to control the spin current emitted in a spin pumping experiment using moderate electric fields. Spin currents were generated at the interface of a ferromagnet/metal bilayer by driving the system to the ferromagnetic resonance condition at X-Band (9.78 GHz) with an incident power of 200 mW. The ME structure, a thin (20 nm) FePt film grown on top of a polished 011-cut single crystal lead magnesium niobate-lead titanate (PMN-PT) slab, was prepared by dc magnetron sputtering. The PMN-PT/FePt was operated in the L-T mode (longitudinal magnetized-transverse polarized). This hybrid composite showed a large ME coefficient of 140 Oe cm/kV, allowing to easily tune the ferromagnetic resonance condition with electric field strengths below 4 kV/cm. A thin layer of Pt (10 nm) was grown on top of the PMN-PT/FePt structure and was used to generate and detect the spin current by taking advantage of its large spin-orbit coupling that produces a measurable signal via the inverse spin-Hall effect. These results proved an alternative way to tune the magnetic field at which the spin current is established and consequently the inverse spin-Hall effect signal, which can promote advances in hybrid spintronic devices.

  12. Gluonic Excitations and Experimental Hall-D at Jefferson Lab

    Energy Technology Data Exchange (ETDEWEB)

    Stevens, Justin [MIT


    A new tagged photon beam facility is being constructed in experimental Hall-D at Jefferson Lab as a part of the 12 GeV upgrade program. The 9 GeV linearly-polarized photon beam will be produced via coherent Bremsstrahlung using the CEBAF electron beam, incident on a diamond radiator. The GlueX experiment in Hall-D will use this photon beam to search for and study the pattern of gluonic excitations in the meson spectrum produced through photoproduction reactions with a liquid hydrogen target. Recent lattice QCD calculations predict a rich spectrum of hybrid mesons, that are formed by exciting the gluonic field that couples the quarks. A subset of these hybrid mesons are predicted to have exotic quantum numbers which cannot be formed from a simple qq^- pair, and thus provide an ideal laboratory for testing QCD in the confinement regime. In these proceedings the status of the construction and installation of the GlueX detector will be presented, in addition to simulation results for some reactions of interest in hybrid meson searches.

  13. Rule-based fault diagnosis of hall sensors and fault-tolerant control of PMSM (United States)

    Song, Ziyou; Li, Jianqiu; Ouyang, Minggao; Gu, Jing; Feng, Xuning; Lu, Dongbin


    Hall sensor is widely used for estimating rotor phase of permanent magnet synchronous motor(PMSM). And rotor position is an essential parameter of PMSM control algorithm, hence it is very dangerous if Hall senor faults occur. But there is scarcely any research focusing on fault diagnosis and fault-tolerant control of Hall sensor used in PMSM. From this standpoint, the Hall sensor faults which may occur during the PMSM operating are theoretically analyzed. According to the analysis results, the fault diagnosis algorithm of Hall sensor, which is based on three rules, is proposed to classify the fault phenomena accurately. The rotor phase estimation algorithms, based on one or two Hall sensor(s), are initialized to engender the fault-tolerant control algorithm. The fault diagnosis algorithm can detect 60 Hall fault phenomena in total as well as all detections can be fulfilled in 1/138 rotor rotation period. The fault-tolerant control algorithm can achieve a smooth torque production which means the same control effect as normal control mode (with three Hall sensors). Finally, the PMSM bench test verifies the accuracy and rapidity of fault diagnosis and fault-tolerant control strategies. The fault diagnosis algorithm can detect all Hall sensor faults promptly and fault-tolerant control algorithm allows the PMSM to face failure conditions of one or two Hall sensor(s). In addition, the transitions between health-control and fault-tolerant control conditions are smooth without any additional noise and harshness. Proposed algorithms can deal with the Hall sensor faults of PMSM in real applications, and can be provided to realize the fault diagnosis and fault-tolerant control of PMSM.

  14. Two-component systems are involved in the regulation of botulinum neurotoxin synthesis in Clostridium botulinum type A strain Hall.

    Directory of Open Access Journals (Sweden)

    Chloé Connan

    Full Text Available Clostridium botulinum synthesizes a potent neurotoxin (BoNT which associates with non-toxic proteins (ANTPs to form complexes of various sizes. The bont and antp genes are clustered in two operons. In C. botulinum type A, bont/A and antp genes are expressed during the end of the exponential growth phase and the beginning of the stationary phase under the control of an alternative sigma factor encoded by botR/A, which is located between the two operons. In the genome of C. botulinum type A strain Hall, 30 gene pairs predicted to encode two-component systems (TCSs and 9 orphan regulatory genes have been identified. Therefore, 34 Hall isogenic antisense strains on predicted regulatory genes (29 TCSs and 5 orphan regulatory genes have been obtained by a mRNA antisense procedure. Two TCS isogenic antisense strains showed more rapid growth kinetics and reduced BoNT/A production than the control strain, as well as increased bacterial lysis and impairment of the bacterial cell wall structure. Three other TCS isogenic antisense strains induced a low level of BoNT/A and ANTP production. Interestingly, reduced expression of bont/A and antp genes was shown to be independent of botR/A. These results indicate that BoNT/A synthesis is under the control of a complex network of regulation including directly at least three TCSs.

  15. Estimating the spin diffusion length and the spin Hall angle from spin pumping induced inverse spin Hall voltages (United States)

    Roy, Kuntal


    There exists considerable confusion in estimating the spin diffusion length of materials with high spin-orbit coupling from spin pumping experiments. For designing functional devices, it is important to determine the spin diffusion length with sufficient accuracy from experimental results. An inaccurate estimation of spin diffusion length also affects the estimation of other parameters (e.g., spin mixing conductance, spin Hall angle) concomitantly. The spin diffusion length for platinum (Pt) has been reported in the literature in a wide range of 0.5-14 nm, and in particular it is a constant value independent of Pt's thickness. Here, the key reasonings behind such a wide range of reported values of spin diffusion length have been identified comprehensively. In particular, it is shown here that a thickness-dependent conductivity and spin diffusion length is necessary to simultaneously match the experimental results of effective spin mixing conductance and inverse spin Hall voltage due to spin pumping. Such a thickness-dependent spin diffusion length is tantamount to the Elliott-Yafet spin relaxation mechanism, which bodes well for transitional metals. This conclusion is not altered even when there is significant interfacial spin memory loss. Furthermore, the variations in the estimated parameters are also studied, which is important for technological applications.

  16. Understanding and Interrupting Hegemonic Projects in Education: Learning from Stuart Hall (United States)

    Apple, Michael W.


    Stuart Hall had a significant impact on critical analyses of rightist mobilizations in education. This is very visible in my own work, for example, in such volumes as "Official Knowledge" (2014) and "Educating the 'Right' Way" (2006). After describing an important series of lectures that Stuart Hall gave at the Havens Center…

  17. Making and Moving Publics: Stuart Hall's Projects, Maximal Selves and Education (United States)

    Roman, Leslie G.


    An extraordinary educator and public intellectual, Stuart Hall's career as a scholar, activist, teacher and mentor has touched almost every field in the social sciences and humanities. Paradoxically, education rarely claims him as an educator. Stuart Hall's refusal to see publics as given, fixed or settled matters with clear or final demarcations…

  18. The Role of Social Influence on How Residence Hall Inhabitants Respond to Fire Alarms (United States)

    Leytem, Michael; Stark, Emily


    College resident halls pose a threat for a catastrophic event in the case of fire, but little research has examined potential influences on students' responses to fire alarms, particularly the role of social influence in affecting their behaviors. In the current study, residence hall inhabitants reported their knowledge about fire safety, their…

  19. Scaling of the Quantum Anomalous Hall Effect as an Indicator of Axion Electrodynamics. (United States)

    Grauer, S; Fijalkowski, K M; Schreyeck, S; Winnerlein, M; Brunner, K; Thomale, R; Gould, C; Molenkamp, L W


    We report on the scaling behavior of V-doped (Bi,Sb)_{2}Te_{3} samples in the quantum anomalous Hall regime for samples of various thickness. While previous quantum anomalous Hall measurements showed the same scaling as expected from a two-dimensional integer quantum Hall state, we observe a dimensional crossover to three spatial dimensions as a function of layer thickness. In the limit of a sufficiently thick layer, we find scaling behavior matching the flow diagram of two parallel conducting topological surface states of a three-dimensional topological insulator each featuring a fractional shift of 1/2e^{2}/h in the flow diagram Hall conductivity, while we recover the expected integer quantum Hall behavior for thinner layers. This constitutes the observation of a distinct type of quantum anomalous Hall effect, resulting from 1/2e^{2}/h Hall conductance quantization of three-dimensional topological insulator surface states, in an experiment which does not require decomposition of the signal to separate the contribution of two surfaces. This provides a possible experimental link between quantum Hall physics and axion electrodynamics.

  20. Galvanomagnetic Effects ¨Sensors based on Hall Effect¨

    Directory of Open Access Journals (Sweden)

    Panagiotis D. Dimitropoulos


    Full Text Available The Hall effect is the generation of a transverse electromotive force in a sample carrying an electric current and exposed to perpendicular magnetic field. Depending on the sample geometry, this electromotive force may cause the appearance of a transverse voltage across the sample, or a current deflection in the sample. The generation of this transverse voltage, called Hall voltage, is the generally known way for the of the appearance of the Hall effect.The resistance of this sample increasing under influence of the magnetic field, this called magnetoresistance effect. Both the Hall effect and the magnetoresistance effect belong to the more general class of phenomena called galvanomagnetic effects. Galvamomagnetic effects are the manifestations of charge transport phenomena in condensed matter in the presence of a magnetic field.The sensor applications of Hall effect became important only with the development of semiconductor technology. For one thing, the Hall effect is only strong enough for this propose in some semiconductors. Therefore, the first Hall effect magnetic sensor became commercially available in the mid 1950s, a few year after the discovery of high-mobility compound semiconductors. Our goal in this paper is to understand the physically background of the Hall and the magnetoresistance effects. We are going to discuss the effect of parameters in those phenomena and how we can make better our technology to improve better efficiency.

  1. The Alberta Jubilee Halls reborn with up-to-date acoustics

    DEFF Research Database (Denmark)

    Jordan, Niels V.; Rindel, Jens Holger


    acoustical knowledge of that time, it had become clear that the halls suffered by several acoustical problems, and thus the government of Alberta wanted the halls to be brought up-to-date for the 100 years jubilee of the state. The Canadian architect Fred Valentine together with other North American...

  2. Hall effect in the normal phase of the organic superconductor (TMTSF)2PF6

    DEFF Research Database (Denmark)

    Moser, J.; Cooper, J.R.; Jerome, D.


    We report accurate Hall effect measurements performed in the normal phase of the quasi-one-dimensional organic conductor (TMTSF)(2)PF(6) at ambient pressure. The Hall coefficient is found to be strongly temperature dependent all the way from 300 K down to the spin density wave onset arising aroun...

  3. "Are You as Hard as 50 Cent?" Negotiating Race and Masculinity in the Residence Halls (United States)

    Jaggers, Dametraus; Iverson, Susan V.


    In a qualitative study of Black undergraduate men at a predominantly White university in the Midwest, participants shared their experiences in residence halls, including roommate conflicts, interracial tensions, and disagreements with residence hall staff. This article focuses on Black male undergraduates' negotiation of racialized conceptions of…

  4. "Are You as Hard as 50 Cent? Negotiating Race and Masculinity in the Residence Halls (United States)

    Jaggers, Dametraus; Iverson, Susan V.


    In a qualitative study of Black undergraduate men at a predominantly White university in the Midwest, participants shared their experiences in residence halls, including roommate conflicts, interracial tensions, and disagreements with residence hall staff. This article focuses on Black male undergraduates' negotiation of racialized conceptions of…

  5. Science 101: How Do Acoustics Dictate the Design of a Concert Hall? (United States)

    Robertson, Bill


    This column provides background science information for elementary teachers. When the author was young he used to think that the ideal design for a concert hall would contain walls that were composed of sound-absorbing material, like foam or egg cartons or such. He noticed, though, that this was not the case. Most concert halls contain curtains…

  6. Acoustical measurements on stages of nine U.S. concert halls

    DEFF Research Database (Denmark)

    Gade, Anders Christian; Bradley, J S


    A measurement tour of nine U.S. concert halls included acoustical measurements on the stage of each hall. Two teams (from the National Research Council of Canada, and the Technical University of Denmark) made measurements of the acoustical quantities suggested by Gade: the ``support'' family...

  7. Purposeful naming: The case of beer halls named during both the ...

    African Journals Online (AJOL)

    This article examines the reasons behind names given to beer halls from their inception in colonial Rhodesia to present day Zimbabwe. To achieve this goal, it analyses names of beer halls, beer outlets built in the former townships of colonial Rhodesia (now called high-density suburbs), and those built at growth points, ...

  8. The Baseball Hall of Fame Is Not the Kiss of Death (United States)

    Smith, Gary


    E. Abel and M. Kruger (2005) reported that the median life expectancy of Major League Baseball players after election to the Baseball Hall of Fame is 5 years shorter than that of players of the same age who are not elected to the Hall of Fame. This conclusion is surprising because there is no compelling explanation for such a dramatic reduction in…

  9. Naval Postgraduate School inducts SEAL, industry mogul into University Hall of Fame


    Stewart, Kenneth A.


    The Naval Postgraduate School (NPS) welcomed its two newest inductees into the university's prestigious Hall of Fame during a ceremony in Herrmann Hall, Nov. 30. Interim President Rear Admiral Jan Tighe presided over the event, enshrining retired Adm. Eric Olson and retired Marine Corps Col. Walt Havenstein as the latest graduates to receive the distriguished honor.

  10. 78 FR 20372 - Culturally Significant Objects Imported for Exhibition Determinations: “Hall of Ancient Egypt” (United States)


    ... From the Federal Register Online via the Government Publishing Office ] DEPARTMENT OF STATE Culturally Significant Objects Imported for Exhibition Determinations: ``Hall of Ancient Egypt'' SUMMARY... objects to be included in the exhibition ``Hall of Ancient Egypt,'' imported from abroad for temporary...

  11. 78 FR 26682 - Culturally Significant Objects Imported for Exhibition Determinations: “Hall of Ancient Egypt” (United States)


    ... Culturally Significant Objects Imported for Exhibition Determinations: ``Hall of Ancient Egypt'' AGENCY... pertaining to the exhibition ``Hall of Ancient Egypt.'' The referenced notice is corrected here to include... of Ancient Egypt,'' imported from abroad for temporary exhibition within the United States, are of...

  12. Student Development in a Coed Residence Hall: Promiscuity, Prophylactic, or Panacea? (United States)

    Brown, Robert D.; And Others


    The results of this study on evaluation of coed residence halls, indicate that a coed hall can lead to an entirely different environment, one that is a contributing factor in positive student development. This paper was presented at the APGA Convention, Chicago, Illinois, 1972. (JC)

  13. Room acoustic enhancement in a small hall with very low natural reverberation time

    DEFF Research Database (Denmark)

    Gade, Anders Christian


    In small multipurpose halls to be equipped with electronic reverberation enhancement systems, selecting a very low natural reverberation time is advantageous for several reasons. It will 1) reduce the risk of feedback, 2) increase the possible range of room acoustic variation and 3) allow for more...... natural combinations of room acoustic properties. Consequently, the natural reverberation time in a newly opened 350 seat multipurpose hall in Denmark was designed as low as 0.7 sec. Two different reverberation enhancement systems were considered and tested in the hall. The objective and subjective...... testing results are reported and compared with previous results obtained in another small hall supplied with a similar enhancement system. The results concerning 'realism' are also compared with acoustic properties found in 'natural' halls of different sizes and reverberation times....

  14. Stress dependence of the Hall coefficient of a nickel-base superalloy (United States)

    Kosaka, Daigo; Frishman, Anatoli; Nakagawa, Norio


    This paper reports on the Hall Effect and their stress dependence, observed experimentally on the superalloy Inconel® 718. The work is motivated by the desire to develop a nondestructive method of characterizing the near-surface protective residual stress in metals. Our approach is based on Hall Effect measurements, because it is anticipated that these measurements are less contaminated by cold work and other effects than conductivity-based measurements such as eddy current. The challenge is that, in metals, the Hall coefficient is very small. To achieve the required sensitivity, the Hall coefficient was measured with an AC injected current and an AC magnetic field. The measurements were performed on a thin film sample. The Hall coefficient was found to be positive, and varies proportionally to the applied tension. The proportionality coefficient is significantly larger than estimated from the volumetric effect in a free carrier model.

  15. Effects of surface and interface scattering on anomalous Hall effect in Co/Pd multilayers

    KAUST Repository

    Guo, Zaibing


    In this paper, we report the results of surface and interface scattering on anomalous Hall effect in Co/Pd multilayers with perpendicular magnetic anisotropy. The surface scattering effect has been extracted from the total anomalous Hall effect. By scaling surface scattering contribution with ρAHs∼ργss, the exponent γ has been found to decrease with the increase of surface scattering resistivity, which could account for the thickness-dependent anomalous Hall effect. Interface diffusion induced by rapid thermal annealing modifies not only the magnetization and longitudinal resistivity but also the anomalous Hall effect; a large exponent γ ∼ 5.7 has been attributed to interface scattering-dominated anomalous Hall effect.

  16. Unconventional scaling of the anomalous Hall effect accompanying electron localization correction in the dirty regime

    KAUST Repository

    Lu, Y. M.


    Scaling of the anomalous Hall conductivity to longitudinal conductivity σAH∝σ2xx has been observed in the dirty regime of two-dimensional weak and strong localization regions in ultrathin, polycrystalline, chemically disordered, ferromagnetic FePt films. The relationship between electron transport and temperature reveals a quantitatively insignificant Coulomb interaction in these films, while the temperature dependent anomalous Hall conductivity experiences quantum correction from electron localization. At the onset of this correction, the low-temperature anomalous Hall resistivity begins to be saturated when the thickness of the FePt film is reduced, and the corresponding Hall conductivity scaling exponent becomes 2, which is above the recent unified theory of 1.6 (σAH∝σ1.6xx). Our results strongly suggest that the correction of the electron localization modulates the scaling exponent of the anomalous Hall effect.

  17. Impact of confined LO-phonons on the Hall effect in doped semiconductor superlattices

    Directory of Open Access Journals (Sweden)

    Nguyen Quang Bau


    Full Text Available Based on the quantum kinetic equation method, the Hall effect in doped semiconductor superlattices (DSSL has been theoretically studied under the influence of confined LO-phonons and the laser radiation. The analytical expression of the Hall conductivity tensor, the magnetoresistance and the Hall coefficient of a GaAs:Si/GaAs:Be DSSL is obtained in terms of the external fields, lattice period and doping concentration. The quantum numbers N, n, m were varied in order to characterize the effect of electron and LO-phonon confinement. Numerical evaluations showed that LO-phonon confinement enhanced the probability of electron scattering, thus increasing the number of resonance peaks in the Hall conductivity tensor and decreasing the magnitude of the magnetoresistance as well as the Hall coefficient when compared to the case of bulk phonons. The nearly linear increase of the magnetoresistance with temperature was found to be in good agreement with experiment.

  18. Performance Comparison of Cross-Like Hall Plates with Different Covering Layers

    Directory of Open Access Journals (Sweden)

    Fei Lyu


    Full Text Available This paper studies the effects of the covering layers on the performance of a cross-like Hall plate. Three different structures of a cross-like Hall plate in various sizes are designed and analyzed. The Hall plate sensitivity and offset are characterized using a self-built measurement system. The effect of the P-type region over the active area on the current-related sensitivity is studied for different Hall plate designs. In addition, the correlation between the P-type covering layer and offset is analyzed. The best structure out of three designs is determined. Besides, a modified eight-resistor circuit model for the Hall plate is presented with improved accuracy by taking the offset into account.

  19. Scattering Effect on Anomalous Hall Effect in Ferromagnetic Transition Metals

    KAUST Repository

    Zhang, Qiang


    The anomalous Hall effect (AHE) has been discovered for over a century, but its origin is still highly controversial theoretically and experimentally. In this study, we investigated the scattering effect on the AHE for both exploring the underlying physics and technical applications. We prepared Cox(MgO)100-x granular thin films with different Co volume fraction (34≤≤100) and studied the interfacial scattering effect on the AHE. The STEM HAADF images confirmed the inhomogeneous granular structure of the samples. As decreases from 100 to 34, the values of longitudinal resistivity () and anomalous Hall resistivity (AHE) respectively increase by about four and three orders in magnitude. The linear scaling relation between the anomalous Hall coefficient () and the measured at 5 K holds in both the as-prepared and annealed samples, which suggests a skew scattering dominated mechanism in Cox(MgO)100-x granular thin films. We prepared (Fe36//Au12/), (Ni36//Au12/) and (Ta12//Fe36/) multilayers to study the interfacial scattering effect on the AHE. The multilayer structures were characterized by the XRR spectra and TEM images of cross-sections. For the three serials of multilayers, both the and AHE increase with , which clearly shows interfacial scattering effect. The intrinsic contribution decreases with increases in the three serials of samples, which may be due to the crystallinity decaying or the finite size effect. In the (Fe36//Au12/) samples, the side-jump contribution increases with , which suggests an interfacial scattering-enhanced side jump. In the (Ni36//Au12/) samples, the side-jump contribution decreases with increases, which could be explained by the opposite sign of the interfacial scattering and grain boundary scattering contributed side jump. In the (Ta12//Fe36/) multilayers, the side-jump contribution changed from negative to positive, which is also because of the opposite sign of the interfacial scattering and grain boundary scattering

  20. Audience noise in concert halls during musical performances

    DEFF Research Database (Denmark)

    Jeong, Cheol-Ho; Marie, Pierre; Brunskog, Jonas


    Noise generated by the audience during musical performances is audible and sometimes disturbing. In this study, an attempt to estimate such audience noise was carried out. From the recordings of performances in five performance spaces (four concert halls and one opera house), probability density...... functions of the sound pressure levels were obtained in octave bands, which were fitted with three Gaussian distribution curves. The Gaussian distribution curve with the lowest mean value corresponds to a mixture of the technical background noise and audience generated noise, which is named the mixed...... background noise. Finally, the audience noise distribution is extracted by energy subtraction of the technical background noise levels measured in an empty condition from the mixed background noise levels. As a single index, L-90 of the audience noise distribution is named the audience noise level. Empirical...

  1. Audience noise in concert halls during musical performances

    DEFF Research Database (Denmark)

    Marie, Pierre; Jeong, Cheol-Ho; Brunskog, Jonas


    Noise generated by the audience during musical performances is audible and sometimes disturbing. In this study, an attempt to estimate such audience noise was carried out. From the recordings of performances in five performance spaces (four concert halls and one opera house), probability density...... functions of the sound pressure levels were obtained in octave bands, which were fitted with three Gaussian distribution curves. The Gaussian distribution curve with the lowest mean value corresponds to a mixture of the technical background noise and audience generated noise, which is named the mixed...... background noise. Finally, the audience noise distribution is extracted by energy subtraction of the technical background noise levels measured in an empty condition from the mixed background noise levels. As a single index, L90 of the audience noise distribution is named the audience noise level. Empirical...

  2. Entanglement Entropy of Quantum Hall Systems with Short Range Disorder (United States)

    Friedman, Barry; Levine, Greg


    The critical value of the mobility for which the filling 5/2 quantum Hall effect is destroyed by short range disorder is determined from an earlier calculation of the entanglement entropy. The value agrees well with experiment; this agreement is particularly significant in that there are no adjustable parameters. Entanglement entropy vs. disorder strength for filling 1/2, filling 9/2 and filling 7/3 is calculated. For filling 1/2 there is no evidence for a transition for the disorder strengths considered; for filling 9/2 there appears to be a stripe-liquid transition. For filling 7/3 there again appears to be a transition at similar value of the disorder strength as the 5/2 transition but there are stronger finite size effects.

  3. Coulomb branch Hilbert series and Hall-Littlewood polynomials

    CERN Document Server

    Cremonesi, Stefano; Mekareeya, Noppadol; Zaffaroni, Alberto


    There has been a recent progress in understanding the chiral ring of 3d $\\mathcal{N}=4$ superconformal gauge theories by explicitly constructing an exact generating function (Hilbert series) counting BPS operators on the Coulomb branch. In this paper we introduce Coulomb branch Hilbert series in the presence of background magnetic charges for flavor symmetries, which are useful for computing the Hilbert series of more general theories through gluing techniques. We find a simple formula of the Hilbert series with background magnetic charges for $T_\\rho(G)$ theories in terms of Hall-Littlewood polynomials. Here $G$ is a classical group and $\\rho$ is a certain partition related to the dual group of $G$. The Hilbert series for vanishing background magnetic charges show that Coulomb branches of $T_\\rho(G)$ theories are complete intersections. We also demonstrate that mirror symmetry maps background magnetic charges to baryonic charges.

  4. RHETT2/EPDM Hall Thruster Propulsion System Electromagnetic Compatibility Evaluation (United States)

    Sarmiento, Charles J.; Sankovic, John M.; Freitas, Joseph; Lynn, Peter R.


    Electromagnetic compatibility measurements were obtained as part of the Electric Propulsion Demonstration Module (EPDM) flight qualification program. Tests were conducted on a Hall thruster system operating at a nominal 66O W discharge power. Measurements of conducted and radiated susceptibility and emissions were obtained and referenced to MEL-STD-461 C. The power processor showed some conducted susceptibility below 4 kHz for the magnet current and discharge voltage. Radiated susceptibility testing yielded a null result. Conducted emissions showed slight violations of the specified limit for MIL-461C CE03. Radiated emissions exceeded the RE02 standard at low frequencies, below 300 MHz, by up to 40 dB RV/m/MHz.

  5. Quantum Hall effects recent theoretical and experimental developments

    CERN Document Server

    Ezawa, Zyun Francis


    Enthusiasm for research on the quantum Hall effect (QHE) is unbounded. The QHE is one of the most fascinating and beautiful phenomena in all branches of physics. Tremendous theoretical and experimental developments are still being made in this sphere. Composite bosons, composite fermions and anyons were among distinguishing ideas in the original edition. In the 2nd edition, fantastic phenomena associated with the interlayer phase coherence in the bilayer system were extensively described. The microscopic theory of the QHE was formulated based on the noncommutative geometry. Furthermore, the unconventional QHE in graphene was reviewed, where the electron dynamics can be treated as relativistic Dirac fermions and even the supersymmetric quantum mechanics plays a key role. In this 3rd edition, all chapters are carefully reexamined and updated. A highlight is the new chapter on topological insulators. Indeed, the concept of topological insulator stems from the QHE. Other new topics are recent prominent experime...

  6. Domain wall assisted GMR head with spin-Hall effect (United States)

    Arun, R.; Sabareesan, P.; Daniel, M.


    We theoretically study the dynamics of a field induced domain wall in the Py/Pt bi-layer structure in the presence of spin-Hall effect (SHE) by solving the Landau-Lifshitz-Gilbert (LLG) equation along with the adiabatic, nonadiabatic and SHE spin-transfer torques (STTs). It is observed that a weak magnetic field moves the domain wall with high velocity in the presence of SHE and the direction of the velocity is changed by changing the direction of the weak field. The numerical results show that the magnetization of the ferromagnetic layer can be reversed quickly through domain wall motion by changing the direction of a weak external field in the presence of SHE while the direction of current is fixed. The SHE reduces the magnetization reversal time of 1000 nm length strip by 14.7 ns. This study is extended to model a domain wall based GMR (Giant Magnetoresistance) read head with SHE.

  7. Beam Loss Ion Chamber System Upgrade for Experimental Halls

    CERN Document Server

    Dotson, Danny W


    The Beam loss Ion Chamber System (BLICS) was developed to protect Jefferson Labs transport lines, targets and beam dumps from a catastrophic "burn through." Range changes and testing was accomplished manually requiring the experiment to be shut down. The new upgraded system is based around an "off the shelf" Programmable Logic Controller located in a single controll box supporting up to ten individual detectors. All functions that formerly required an entry into the experimental hall and manual adjustment can be accomplished from the Machine Control Center (MCC). A further innovation was the addition of a High Voltage "Brick" at the detector location. A single cable supplies the required voltage for the Brick and a return line for the ion chamber signal. The read back screens display range, trip point, and accumulated dose for each location. The new system is very cost effective and significantly reduces the amount of lost experimental time.

  8. Imaging of Coulomb-Driven Quantum Hall Edge States

    KAUST Repository

    Lai, Keji


    The edges of a two-dimensional electron gas (2DEG) in the quantum Hall effect (QHE) regime are divided into alternating metallic and insulating strips, with their widths determined by the energy gaps of the QHE states and the electrostatic Coulomb interaction. Local probing of these submicrometer features, however, is challenging due to the buried 2DEG structures. Using a newly developed microwave impedance microscope, we demonstrate the real-space conductivity mapping of the edge and bulk states. The sizes, positions, and field dependence of the edge strips around the sample perimeter agree quantitatively with the self-consistent electrostatic picture. The evolution of microwave images as a function of magnetic fields provides rich microscopic information around the ν=2 QHE state. © 2011 American Physical Society.

  9. Intrinsic and Extrinsic Spin Hall Effects of Dirac Electrons (United States)

    Fukazawa, Takaaki; Kohno, Hiroshi; Fujimoto, Junji


    We investigate the spin Hall effect (SHE) of electrons described by the Dirac equation, which is used as an effective model near the L-points in bismuth. By considering short-range nonmagnetic impurities, we calculate the extrinsic as well as intrinsic contributions on an equal footing. The vertex corrections are taken into account within the ladder type and the so-called skew-scattering type. The intrinsic SHE which we obtain is consistent with that of Fuseya et al. [" xlink:type="simple">J. Phys. Soc. Jpn. 81, 093704 (2012)]. It is found that the extrinsic contribution dominates the intrinsic one when the system is metallic. The extrinsic SHE due to the skew scattering is proportional to Δ/niu, where 2Δ is the band gap, ni is the impurity concentration, and u is the strength of the impurity potential.

  10. Extrinsic anomalous Hall effect in epitaxial Mn4N films (United States)

    Meng, M.; Wu, S. X.; Ren, L. Z.; Zhou, W. Q.; Wang, Y. J.; Wang, G. L.; Li, S. W.


    Anomalous Hall effect (AHE) in ferrimagnetic Mn4N epitaxial films grown by molecular-beam epitaxy is investigated. The longitudinal conductivity σx x is within the superclean regime, indicating Mn4N is a highly conducting material. We further demonstrate that the AHE signal in 40-nm-thick films is mainly due to the extrinsic contributions based on the analysis fitted by ρAH=a 'ρxx 0+b ρxx2 and σA H∝σx x . Our study not only provide a strategy for further theoretical work on antiperovskite manganese nitrides but also shed promising light on utilizing their extrinsic AHE to fabricate spintronic devices.

  11. Heavy Gas Cerenkov Detector for Jefferson Lab Hall C (United States)

    Li, Wenliang


    The Thomas Jefferson National Accelerator Facility (JLab) has undertaken the 12 GeV Upgrade to double the accelerating energy of its electron beam. This attracts many interesting proposals to probe the quark-gluon nature of nuclear matter at higher energy therefore a new set of equipment are required. A new Super High Momentum Spectrometer (SHMS) is currently under construction for the experimental Hall C. University of Regina is assigned to construct the Heavy Gas Cerenkov Detector as part of SHMS focal plane detectors. This detector will be used as critical component for good pion identification in the SHMS experimental program. In this presentation, we will report the design, current status and expected performance. Supported by the Natural Sciences and Engineering Research Council of Canada (NSERC).

  12. Elimination of Lifetime Limiting Mechanism of Hall Thrusters (United States)

    Jacobson, David T. (Inventor); Manzella, David H. (Inventor)


    A Hall thruster includes inner and outer electromagnets, with the outer electromagnet circumferentially surrounding the inner electromagnet along a centerline axis and separated therefrom, inner and outer poles, in physical connection with their respective inner and outer electromagnets, with the inner pole having a mostly circular shape and the outer pole having a mostly annular shape, a discharge chamber separating the inner and outer poles, a combined anode electrode/gaseous propellant distributor, located at an upstream portion of the discharge chamber and supplying propellant gas and an actuator, in contact with a sleeve portion of the discharge chamber. The actuator is configured to extend the sleeve portion or portions of the discharge chamber along the centerline axis with respect to the inner and outer poles.

  13. Inducing superconducting correlation in quantum Hall edge states (United States)

    Lee, Gil-Ho; Huang, Ko-Fan; Efetov, Dmitri K.; Wei, Di S.; Hart, Sean; Taniguchi, Takashi; Watanabe, Kenji; Yacoby, Amir; Kim, Philip


    The quantum Hall (QH) effect supports a set of chiral edge states at the boundary of a two-dimensional system. A superconductor (SC) contacting these states can provide correlations of the quasiparticles in the dissipationless edge states. Here we fabricated highly transparent and nanometre-scale SC junctions to graphene. We demonstrate that the QH edge states can couple via superconducting correlations through the SC electrode narrower than the superconducting coherence length. We observe that the chemical potential of the edge state exhibits a sign reversal across the SC electrode. This provides direct evidence of conversion of the incoming electron to the outgoing hole along the chiral edge state, termed crossed Andreev conversion (CAC). We show that CAC can successfully describe the temperature, bias and SC electrode width dependences. This hybrid SC/QH system could provide a novel route to create isolated non-Abelian anyonic zero modes, in resonance with the chiral edge states.

  14. Magnetic bilayer-skyrmions without skyrmion Hall effect. (United States)

    Zhang, Xichao; Zhou, Yan; Ezawa, Motohiko


    Magnetic skyrmions might be used as information carriers in future advanced memories, logic gates and computing devices. However, there exists an obstacle known as the skyrmion Hall effect (SkHE), that is, the skyrmion trajectories bend away from the driving current direction due to the Magnus force. Consequently, the skyrmions in constricted geometries may be destroyed by touching the sample edges. Here we theoretically propose that the SkHE can be suppressed in the antiferromagnetically exchange-coupled bilayer system, since the Magnus forces in the top and bottom layers are exactly cancelled. We show that such a pair of SkHE-free magnetic skyrmions can be nucleated and be driven by the current-induced torque. Our proposal provides a promising means to move magnetic skyrmions in a perfectly straight trajectory in ultra-dense devices with ultra-fast processing speed.

  15. Torque engineering in trilayer spin-hall system (United States)

    Gupta, Gaurav; Jalil, Mansoor Bin Abdul; Liang, Gengchiau


    A trilayer system with perpendicularly magnetized metallic (FMM) free-layer, heavy metal (HM) with strong spin-hall effect and ferromagnetic insulating (FMI) substrate has been proposed to significantly enhance the torque acting on FMM. Its magnitude can be engineered by configuring the magnetization of the FMI. The analytical solution has been developed for four stable magnetization states (non-magnetic and magnetization along three Cartesian axes) of FMI to comprehensively appraise the anti-damping torque on FMM and the Gain factor. It is shown that the proposed system has much larger gain and torque compared to a bilayer system (or a trilayer system with non-magnetic substrate). The performance improvement may be extremely large for system with a thin HM. Device optimization is shown to be non-trivial and various constraints have been explained. These results would enable design of more efficient spin-orbit torque memories and logic with faster switching at yet lower current.

  16. Hall MHD Stability and Turbulence in Magnetically Accelerated Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    H. R. Strauss


    The object of the research was to develop theory and carry out simulations of the Z pinch and plasma opening switch (POS), and compare with experimental results. In the case of the Z pinch, there was experimental evidence of ion kinetic energy greatly in excess of the ion thermal energy. It was thought that this was perhaps due to fine scale turbulence. The simulations showed that the ion energy was predominantly laminar, not turbulent. Preliminary studies of a new Z pinch experiment with an axial magnetic field were carried out. The axial magnetic is relevant to magneto - inertial fusion. These studies indicate the axial magnetic field makes the Z pinch more turbulent. Results were also obtained on Hall magnetohydrodynamic instability of the POS.

  17. Observation of the fractional quantum Hall effect in graphene (United States)

    Bolotin, Kirill; Ghahari, Fereshte; Shulman, Michael D.; Stormer, Horst L.; Kim, Philip


    Only a glimpse of correlated electron physics has been observed in graphene so far, mostly due to the strong electron scattering caused by charged impurities in the substrate. To overcome this limitation,we fabricate devices where electrically contacted and electrostatically gated graphene samples are suspended over a substrate. The measured low-temperature sample mobility is found to exceed 100,000 cm2/Vs in such devices. The very high mobility of our specimens allows us to observe previously inaccessible transport regimes in graphene. We report the observation of the fractional quantum Hall effect, supporting the existence of interaction induced correlated electron states in the presence of a magnetic field. In addition, at low carrier density graphene becomes an insulator with an energy gap tunable by magnetic field.

  18. Hall Effect Characterization Of Thin Films Deposited By Laser Ablation

    Energy Technology Data Exchange (ETDEWEB)

    Canulescu, S.; Montenegro, M.; Lippert, Th.; Wokaun, A.


    A series of La{sub 0.6}Co{sub 0.4}.CoO{sub 3}, La{sub 0.6}Co{sub 0.4}Mn{sub 0.9}Ni{sub 0.1}O{sub 3}, La{sub 0.6}Co{sub 0.4}MnO{sub 3}, La{sub 0.6}Co{sub 0.4}MnO{sub 3} thin films were investigated by Hall effect measurements and Raman Spectroscopy. It was found that the manganese thin films have excellent magneto resistive properties. The influence of the substrate on the electrical properties of the films was investigated. (author)

  19. Helical liquid and the edge of quantum spin Hall systems. (United States)

    Wu, Congjun; Bernevig, B Andrei; Zhang, Shou-Cheng


    The edge states of the recently proposed quantum spin Hall systems constitute a new symmetry class of one-dimensional liquids dubbed the "helical liquid," where the spin orientation is determined by the direction of electron motion. We prove a no-go theorem which states that a helical liquid with an odd number of components cannot be constructed in a purely 1D lattice system. In a helical liquid with an odd number of components, a uniform gap in the ground state can appear when the time-reversal symmetry is spontaneously broken by interactions. On the other hand, a correlated two-particle backscattering term by an impurity can become relevant while keeping the time-reversal invariance.

  20. The quantum Hall effect at 5/2 filling factor. (United States)

    Willett, R L


    Experimental discovery of a quantized Hall state at 5/2 filling factor presented an enigmatic finding in an established field of study that has remained an open issue for more than twenty years. In this review we first examine the experimental requirements for observing this state and outline the initial theoretical implications and predictions. We will then follow the chronology of experimental studies over the years and present the theoretical developments as they pertain to experiments, directed at sets of issues. These topics will include theoretical and experimental examination of the spin properties at 5/2; is the state spin polarized? What properties of the higher Landau levels promote development of the 5/2 state, what other correlation effects are observed there, and what are their interactions with the 5/2 state? The 5/2 state is not a robust example of the fractional quantum Hall effect: what experimental and material developments have allowed enhancement of the effect? Theoretical developments from initial pictures have promoted the possibility that 5/2 excitations are exceptional; do they obey non-abelian statistics? The proposed experiments to determine this and their executions in various forms will be presented: this is the heart of this review. Experimental examination of the 5/2 excitations through interference measurements will be reviewed in some detail, focusing on recent results that demonstrate consistency with the picture of non-abelian charges. The implications of this in the more general physics picture is that the 5/2 excitations, shown to be non-abelian, should exhibit the properties of Majorana operators. This will be the topic of the last review section.

  1. Encouraging Electricity Savings in a University Residential Hall through a Combination of Feedback, Visual Prompts, and Incentives (United States)

    Bekker, Marthinus J.; Cumming, Tania D.; Osborne, Nikola K. P.; Bruining, Angela M.; McClean, Julia I.; Leland, Louis S., Jr.


    This experiment investigated the combined use of visual prompts, daily feedback, and rewards to reduce electricity consumption in a university residential hall. After a 17-day baseline period, the experimental intervention was introduced in the intervention hall, and no change was made in the control hall. Energy usage decreased in the…

  2. Objective and perceptual evaluation of distance-dependent scattered sound effects in a small variable-acoustics hall. (United States)

    Shtrepi, Louena; Astolfi, Arianna; D'Antonio, Gianluca; Guski, Martin


    Performance spaces are characterized by a complex sound field, due to the presence of absorptive and diffusive surfaces. In situ evaluations of the acoustic effects that these surfaces have on the objective acoustic parameters and on sound perception have not yet been fully understood. To this aim, acoustic measurements have been performed in a variable-acoustic concert hall, the Espace de Projection, at the Institut de Recherche et Coordination Acoustique/Musique. These measurements have allowed the effects of one single wall to be determined. A diffusive and a reflective condition of one of the long lateral walls of the shoebox-like hall have been considered, while the other surfaces have been fixed in absorptive mode. Measurements have been carried out at different distances from the test wall, using an artificial head and an array of omnidirectional microphones. Objective acoustic parameters, such as early decay time, reverberation time (T30), clarity (C80), definition (D50), and interaural cross correlation, have been compared between both conditions. In addition to the objective indexes, a perceptual evaluation has been performed using listening tests that had the purpose of determining the maximum distance from a diffusive surface at which acoustic scattering effects are still audible.

  3. The Hall technique is an effective treatment option for carious primary molar teeth. (United States)

    Rosenblatt, Aronita


    This was a general dental practice (GDP)-based, split-mouth, randomised controlled trial (RCT). The Hall technique, where a preformed metal crown (PMC) is cemented with no local anaesthesia, caries removal or tooth preparation, was compared with restoration with the material the GDP would normally choose. The outcomes were recorded as success; minor failure (restoration failure or reversible pulpitis, which could be managed by repair or replacement); or major failure (signs or symptoms of irreversible pulpal damage, such as dental abscess, or tooth broken down and unfeasible to repair or replace the restoration). A total of 128 conventional restorations were placed on 132 control teeth, and 128 PMC on 132 intervention teeth. Eighty-nine per cent of Hall PMC were rated by dentists as causing no apparent discomfort through to merely mild discomfort: for the control restorations this was 78% (not a significant difference). The Hall PMC outperformed the control restorations in terms of the number of major and minor failures (see Table 1). Preference for the Hall technique was recorded at 77% for the children, 83% for carers and 81% for dentists who expressed a preference, which this was significant (Chi square, P<0.0001). The Hall technique was preferred to conventional restorations by the majority of children, carers and dental practitioners. After 2 years, Hall PMC showed more favourable outcomes for pulpal health and restoration longevity than conventional restorations. The Hall technique appears to offer an effective treatment option for carious primary molar teeth.

  4. Quantum spin/valley Hall effect and topological insulator phase transitions in silicene

    KAUST Repository

    Tahir, M.


    We present a theoretical realization of quantum spin and quantum valley Hall effects in silicene. We show that combination of an electric field and intrinsic spin-orbit interaction leads to quantum phase transitions at the charge neutrality point. This phase transition from a two dimensional topological insulator to a trivial insulating state is accompanied by a quenching of the quantum spin Hall effect and the onset of a quantum valley Hall effect, providing a tool to experimentally tune the topological state of silicene. In contrast to graphene and other conventional topological insulators, the proposed effects in silicene are accessible to experiments.


    Energy Technology Data Exchange (ETDEWEB)

    Ron Gilman; F.T. Baker; Louis Bimbot; Ed Brash; Charles Glashausser; Mark Jones; Gerfried Kumbartzki; Sirish Nanda; Charles F. Perdrisat; Vina Punjabi; Ronald Ransome; Paul Rutt


    A focal plane polarimeter intended for the CEBAF Hall A high resolution hadron spectrometer is under construction at Rutgers University and the College of William and Mary. Experiments with focal plane polarimeters are only now beginning at electron accelerators; they play a prominent role in the list of approved experiments for Hall A. Construction of the polarimeter is in progress, it is expected to be brought to CEBAF in spring 1995. Several coincidence (e,e'p) and singles (gamma, p) measurements by the Hall A Collaboration are expected to start in 1996. In this paper we describe the polarimeter and the physics program planned for it.

  6. Inverse spin Hall effect in ferromagnetic metal with Rashba spin orbit coupling

    Directory of Open Access Journals (Sweden)

    M.-J. Xing


    Full Text Available We report an intrinsic form of the inverse spin Hall effect (ISHE in ferromagnetic (FM metal with Rashba spin orbit coupling (RSOC, which is driven by a normal charge current. Unlike the conventional form, the ISHE can be induced without the need for spin current injection from an external source. Our theoretical results show that Hall voltage is generated when the FM moment is perpendicular to the ferromagnetic layer. The polarity of the Hall voltage is reversed upon switching the FM moment to the opposite direction, thus promising a useful reading mechanism for memory or logic applications.

  7. Hall effect on thermosolutal convection of ferromagnetic fluids in porous medium (United States)

    Aggarwal, A. K.; Makhija, Suman


    The present study deals with effect of Hall currents on thermal convection of ferromagnetic fluids in porous medium. The combined effect of solute gradient, medium permeability, magnetic field and Hall currents on the thermal stability has been investigated. It is found that Hall currents destabilize the system. The magnetic field and solute gradient have stabilizing effect on the convection. The medium permeability has conditional effect on the stability. The principle of exchange of stabilities (PES) is not satisfied under these conditions. In the absence of magnetic field and solute gradient, PES is valid.

  8. Alcohol trajectories over three years in a Swedish residence hall student population. (United States)

    Ståhlbrandt, Henriettae; Leifman, Anders; Johnsson, Kent O; Berglund, Mats


    Although it is known that college students have a high alcohol consumption, less is known about the long-term drinking trajectories amongst college students and, in particular, students living in residence halls, known to be high-risk drinkers. Over four consecutive years, the drinking habits of 556 Swedish residence hall students were analyzed. The main instruments for measuring outcome were AUDIT (Alcohol Use Identification Disorders Test), SIP (Short Index of Problems) and eBAC (estimated Blood Alcohol Concentration). The drinking trajectories among Swedish residence hall students showed stable and decreasing drinking patterns, with age and gender being predictors of group membership.

  9. Photovoltaic infrared photoresponse of the high-mobility graphene quantum Hall system due to cyclotron resonance (United States)

    Masubuchi, Satoru; Onuki, Masahiro; Arai, Miho; Yamaguchi, Takehiro; Watanabe, Kenji; Taniguchi, Takashi; Machida, Tomoki


    We report on the infrared photoresponse of high-mobility graphene in high magnetic fields. Two types of photoresponse signals were observed that were due to photovoltaic and bolometric effects. The photovoltaic signal was observed in the quantum Hall regime, whereas the bolometric signal was dominant in the quantum Hall transition regime. The photovoltaic effect, which was induced by cyclotron resonance, was observable up to 180 K. The polarity of the photovoltaic photoresponse was shown to be systematically reversed on reversal of the applied magnetic field direction and measurement geometry, suggesting that the photovoltage signals were generated along the quantum Hall edge channel.

  10. Alcohol Trajectories over Three Years in a Swedish Residence Hall Student Population

    Directory of Open Access Journals (Sweden)

    Henriettae Ståhlbrandt


    Full Text Available Although it is known that college students have a high alcohol consumption, less is known about the long-term drinking trajectories amongst college students and, in particular, students living in residence halls, known to be high-risk drinkers. Over four consecutive years, the drinking habits of 556 Swedish residence hall students were analyzed. The main instruments for measuring outcome were AUDIT (Alcohol Use Identification Disorders Test, SIP (Short Index of Problems and eBAC (estimated Blood Alcohol Concentration. The drinking trajectories among Swedish residence hall students showed stable and decreasing drinking patterns, with age and gender being predictors of group membership.

  11. Detection and Solution of Indoor Air Quality Problems in a Danish Town Hall

    DEFF Research Database (Denmark)

    Hyldgård, Carl-Erik; Brohus, Henrik

    in the climate laboratory. A new heating and ventilating system and a new control strategy were chosen and implemented into the town hall. It was found that air supply upwards along a window may make it nearly impossible to achieve comfort and a good air quality the year round without full-scale measurements.......In connection with the research programme "Healthy Buildings", a building with indoor air quality problems was selected for further investigations. A Danish town hall was chosen because of many complaints over several years. A full-scale mock-up of a typical town hall office was built...

  12. Alcohol Trajectories over Three Years in a Swedish Residence Hall Student Population (United States)

    Ståhlbrandt, Henriettae; Leifman, Anders; Johnsson, Kent O.; Berglund, Mats


    Although it is known that college students have a high alcohol consumption, less is known about the long-term drinking trajectories amongst college students and, in particular, students living in residence halls, known to be high-risk drinkers. Over four consecutive years, the drinking habits of 556 Swedish residence hall students were analyzed. The main instruments for measuring outcome were AUDIT (Alcohol Use Identification Disorders Test), SIP (Short Index of Problems) and eBAC (estimated Blood Alcohol Concentration). The drinking trajectories among Swedish residence hall students showed stable and decreasing drinking patterns, with age and gender being predictors of group membership. PMID:20617038

  13. Thermal Hall Effect in a Phonon-Glass Ba3 CuSb2 O9 (United States)

    Sugii, K.; Shimozawa, M.; Watanabe, D.; Suzuki, Y.; Halim, M.; Kimata, M.; Matsumoto, Y.; Nakatsuji, S.; Yamashita, M.


    A distinct thermal Hall signal is observed in a quantum spin liquid candidate Ba3 CuSb2 O9 . The transverse thermal conductivity shows a power-law temperature dependence below 50 K, where a spin gap opens. We suggest that because of the very low longitudinal thermal conductivity and the thermal Hall signals, a phonon Hall effect is induced by strong phonon scattering of orphan Cu2 + spins formed in the random domains of the Cu2 + -Sb5 + dumbbells in Ba3 CuSb2 O9 .

  14. On the gauge invariant and topological nature of the localization determining the Quantum Hall Effect plateaus

    CERN Document Server

    Cabo-Montes de Oca, Alejandro


    It is shown how the electromagnetic response of 2DEG under Quantum Hall Effect regime, characterized by the Chern-Simons topological action, transforms the sample impurities and defects in charge-reservoirs that stabilize the Hall conductivity plateaus. The results determine the basic dynamical origin of the singular properties of localization under the occurrence of the Quantum Hall Effect obtained in the pioneering works of Laughlin and of Joynt and Prange, by means of a gauge invariance argument and a purely electronic analysis, respectively. The common intuitive picture of electrons moving along the equipotential lines gets an analytical realization through the Chern-Simons current and charge densities.

  15. The X3: A 200 kW Class Nested Channel Hall Thruster (United States)

    Sheehan, J. P.


    Electric propulsion has seen rapid adoption in recent years for commercial, scientific, and exploratory space missions. The X3 is a three channel nested channel Hall thruster, designed to push the boundaries of high power electric propulsion for cargo transfer to Mars and large military assets. It has been operated at thermal steady state up to 30 kW of power. Thrust measurements were made on an inverted pendulum thrust stand, indicating over 2000 s specific impulse and 65 mN/kW thrust to power ratio. Detailed plume measurements were made with Faraday and Langmuir probes. The multiple concentric channels provide better performance than the sum of the individual channel operations due to superior propellant utilization from its compact design. Using a high speed camera, the breathing and spoke mode instabilities were captured in all three channels. Spoke and breathing instabilities couple between the channels, indicating that complex plasma and neutral interactions are at play. Electron transport, both cross field and in the cathode plume, are well suited to be explored in a thruster of this size. Supported under NASA contract No. NNH16CP17C.

  16. Hypernuclear spectroscopy with electron beam at JLab Hall C

    Energy Technology Data Exchange (ETDEWEB)

    Yuu Fujii


    Hypernuclear spectroscopy with electron beam at JLab Hall C has been studied since 2000. The first experiment, JLab E89-009, used Short Orbit Spectrometer (SOS) as a kaon arm and a split-pole type spectrometer (ENGE) as an electron arm. E89-009 employed zero-degree tagging method, which tags scattered electrons at zero-degree and the kaon arm also covered zero-degree. This method obtains maximum yield of hypernuclei but sufferers from high rate background of electrons from bremsstrahlung and positrons from pair-creation. Nevertheless, this experiment demonstrated the possibility of the (e,e' K{sup +}) reaction for hypernuclear spectroscopy by obtaining a hypernuclear mass spectrum with an energy resolution of better than 1 MeV (FWHM) [1][2]. However, poor signal to noise ratio and poor statistics requires us to improve the experimental setup. Therefore, E01-011 experiment was proposed based on the success of the JLab E01-011 experiment. Improvements of E01-011 from E09-009 can be summarized as: 1. Employed newly constructed high resolution kaon spectrometer (HKS) as a kaon arm. 2. Employed so-called 'tilt-method' for the electron arm. With the newly constructed HKS, having 2-10-4 momentum resolution, we expect an energy resolution of 400 keV (FWHM). The 'tilt-method' means the electron arm is tilted vertically to the splitter dispersive plane to avoid background electrons from bremsstrahlung and moeller scattering. The setup allowed us to use up to a few tens beam. The experiment was performed in 2005 and final result will be shown shortly. The third experiment, JLab E05-115 experiment was proposed as a natural extension of E01-011 experiment and will be performed in 2009. Improvements of experimental setup are, 1. Employed newly constructed high resolution electron spectrometer (HES) as a electron arm, 2. Employed a new charge-separation magnet (Splitter), fully customized for hypernuclear experiment at Hall C. With the third generation

  17. Lung function and dust in climbing halls: two pilot studies. (United States)

    Moshammer, Hanns; Shahraki, Shifra; Mondel, Thomas; Gebhart, Patrik


    In climbing halls, high levels of dust are found because magnesia powder is used to dry hands. Concerns have been raised about possible health effects after reports from asthmatics experiencing worsening of symptoms while or after climbing. We investigated acute and sub-acute effects of climbing in dusty halls on lung function in two pilot studies. The first study examined 109 climbers before and after a climbing activity that lasted at least 1 h. In the second study, 25 climbers from different age classes participated in a 2-day climbing competition. Of these, 24 agreed to take part in our investigation, but only 22 provided valid lung function tests on both days. The climbers underwent lung function tests before the first round of the competition (in the morning), after the second round approximately 3 h later and in the morning of the second day before the competition started again. In the first study, we found acute effects, a decline in lung function immediately after the exposure, likely due to protective reflexes of the bronchial muscles and stronger declines in persons with higher exhaled nitric oxide (NO) pre-climbing. In the second study, we also expected sub-acute effects on the next day due to inflammation. On the first day of the competition (second study), dust levels at a central monitor increased over time in a linear manner. Most of the dust was in the size range between 2.5 and 10 μm and dust levels of particulate matter (PM10) reached 0.5 mg/m3. There was a decline in lung function over 24 h in persons with higher exhaled NO levels pre-exposure. All spirometric parameters were affected though the effects were not statistically significant in all cases. Younger age classes started earlier in the morning. Because of the increasing trend in dust levels we expected stronger effects with higher numbers but for the acute effects the reverse was true, possibly because younger climbers use magnesia more or with less experience thus causing higher

  18. Space Technology: A study of the significance of recognition for innovators of spinoff technologies. A case study on the impact of the space technology hall of fame award (United States)


    This report represents the preliminary effort in studying the significance of recognition for innovators of spinoff technologies. The purpose of this initial year's effort in this area was to gather preliminary data and define the direction for the remainder of the research. This report focuses on the most recent recipients of the Hall of Fame Award, the developers of liquid-cooled garments. Liquid-cooled garments technology and its spinoffs were used as a case study to define and explore the factors involved in technology transfer and to consider the possible incentives in developing commercial applications including the Hall of Fame Award. Through interviews, views of award recipients were obtained on factors encouraging spinoffs as well as impediments to spinoffs. The researchers observed complex inter-relationships among the significant entities (government, individuals, large and small business), the importance of people, the importance of resource availability, and the significance of intrinsic motivation; drew preliminary conclusions pertaining to the direct and indirect influence of recognition like the Hall of Fame Award; and planned the direction for next year's follow-on research.

  19. Silicon Carbide (SiC) Power Processing Unit (PPU) for Hall Effect Thrusters Project (United States)

    National Aeronautics and Space Administration — In this SBIR project, APEI, Inc. is proposing to develop a high efficiency, rad-hard 3.8 kW silicon carbide (SiC) Power Processing Unit (PPU) for Hall Effect...

  20. Kinetic Molecular Dynamic Model of Hall Thruster Channel Wall Erosion Project (United States)

    National Aeronautics and Space Administration — Hall thrusters are being considered for many space missions because their high specific impulse delivers a larger payload mass fraction than chemical rockets. With a...

  1. Wide Throttling, High Throughput Hall Thruster for Science and Exploration Missions Project (United States)

    National Aeronautics and Space Administration — In response to Topic S3.04 "Propulsion Systems," Busek Co. Inc. will develop a high throughput Hall effect thruster with a nominal peak power of 1-kW and wide...

  2. Generation of Alfvén wave energy during magnetic reconnection in Hall MHD (United States)

    Li, Lingjie; Ma, Zhiwei; Wang, Licheng


    The effect of the reconnection rate on the generation of Alfvén wave energy is systematically investigated using Hall magnetohydrodynamics (MHD). It is well known that a decrease in magnetic energy is proportional to the reconnection rate. It is found that an instantaneous increase in Alfvén wave energy in unit Alfvén time is the square dependence on the reconnection rate. The converted Alfvén wave energy is strongly enhanced due to the large increase in the reconnection rate in Hall MHD. For solar-terrestrial plasmas, the maximum converted Alfvén wave energy in unit Alfvén time with the Hall effect can be over 50 times higher than that without the Hall effect during magnetic reconnection.

  3. High Performance Plasma Channel Insulators for High Power Hall Thrusters Project (United States)

    National Aeronautics and Space Administration — NASA missions for planetary exploration require high power, long-life Hall thrusters. However, thruster power and lifetime are limited by the erosion of plasma...

  4. Design and performance evaluation of a hall effect magnetic compass for oceanographic and meteorological applications

    Digital Repository Service at National Institute of Oceanography (India)

    Joseph, A.; Desai, R.G.P.; Agarvadekar, Y.; Tengali, T.; Mishra, M.; Fadate, C.; Gomes, L.

    A Hall Effect magnetic compass, suitable for oceanographic and meteorological applications, has been designed and its performance characteristics have been evaluated. Slope of the least-squares-fitted linear graph was found to be close to the ideal...

  5. On-Chip Magnetorelaxometry Using Planar Hall Effect Magnetic Field Sensors

    DEFF Research Database (Denmark)

    Østerberg, Frederik Westergaard

    the relaxation of magnetic beads without the need of any external fields and estimates of the forces that influence magnetic beads near a planar Hall effect sensor. The temperature dependence of measurements using planar Hall effect sensors is investigated. This is done both with respect to how the sensor...... signals depend on temperature and how temperature influences the Brownian relaxation of magnetic beads. It is shown that the hydrodynamic diameter of the magnetic beads can be extracted from AC susceptibility measurements with planar Hall effect sensors when the temperature and dynamic viscosity...... of using planar Hall effect magnetic field sensors to measure magnetorelaxomety of magnetic beads. This can be used as the readout principle for volume-based biosensing, by detecting changes in the hydrodynamic diameter of magnetic beads due to binding of analytes. Traditionally magnetorelaxomety...

  6. Comparisons of auditorium acoustics measurements as a function of location in halls (A)

    DEFF Research Database (Denmark)

    Bradley, J. S.; Gade, Anders Christian; Siebein, G W


    In a measurement tour of nine U.S. concert halls measurements were made at 30 or more combinations of source and receiver position in each hall. Each of the three measurement teams (the University of Florida, the Danish Technical University, and the National Research Council of Canada) made...... parallel measurements of a number of modern room acoustics quantities using different equipment and measurement procedures. These results are compared on a seat-by-seat basis and the differences are explained in terms of earlier systematic studies of the effects of measurement procedure details....... The measurement results were also used to examine the influence of different measurement equipment and measurement procedures on the within hall variations of the various acoustical quantities. [Work partially supported by the Concert Hall Research Group.]...

  7. Long Life 600W Hall Thruster System for Radioisotope Electric Propulsion Project (United States)

    National Aeronautics and Space Administration — Radioisotope Electric Propulsion (REP) offers the prospect for a variety of new science missions by enabling use of Hall Effect propulsion in the outer solar system,...

  8. Hall mobility in lead selenide and its analysis in MathCad computer environment


    Budzhak, Ya. S.; Zub, O. V.


    This thesis demonstrates that current carriers in an experimental crystal diffuse on the thermal vibrations of lattice by means of regression analysis of experimental data for Hall mobility of PbSe crystals.

  9. Observation of orbital resonance Hall effect in (TMTSF)2ClO4. (United States)

    Kobayashi, Kaya; Satsukawa, H; Yamada, J; Terashima, T; Uji, S


    We report the observation of a Hall effect driven by orbital resonance in the quasi-1-dimensional (q1D) organic conductor (TMTSF)2ClO4. Although a conventional Hall effect is not expected in this class of materials due to their reduced dimensionality, we observed a prominent Hall response at certain orientations of the magnetic field B corresponding to lattice vectors of the constituent molecular chains, known as the magic angles (MAs). We show that this Hall effect can be understood as the response of conducting planes generated by an effective locking of the orbital motion of the charge carriers to the MA driven by an electron-trajectory resonance. This phenomenon supports a class of theories describing the rich behavior of MA phenomena in q1D materials based on altered dimensionality. Furthermore, we observed that the effective carrier density of the conducting planes is exponentially suppressed in large B, which indicates possible density wave formation.

  10. Shifting Diagnostic Systems for Defining Intellectual Disability in Death Penalty Cases: Hall vs. Florida (United States)

    Mukherjee, Mina; Westphal, Alexander


    The case of Hall vs. Florida tested Florida's so called "bright line rule" in determining intellectual disability in capital cases. The Supreme Court Decision reflects a more general trend from categorical to dimensional approaches in psychiatric diagnostic systems.

  11. Do 'liberal market economies' really innovate more radically than 'coordinated market economies'? Hall and Soskice reconsidered

    NARCIS (Netherlands)

    Akkermans, Dirk; Castaldi, Carolina; Los, Bart

    In Varieties of Capitalism: The Institutional Foundations of Comparative Advantage, Peter A. Hall and David Soskice (H&S) argue that technological specialization patterns are largely determined by the prevailing "variety of capitalism". They hypothesize that "liberal market economies" (LMEs)

  12. Infrared Hall conductivity of Na0.7CoO2 (United States)

    Choi, E. J.; Jung, S. H.; Noh, J. H.; Zimmers, A.; Schmadel, D.; Drew, H. D.; Bang, Y. K.; Son, J. Y.; Cho, J. H.


    We report the infrared Hall conductivity σxy(ω) of Na0.7CoO2 thin films at ω=1100cm-1 determined from Faraday rotation θF measurements. σxy(ω) exhibits two types of hole conduction, Drude and incoherent carriers. The coherent Drude carriers appear at low temperatures and show a large renormalized mass and Fermi-liquid-like behavior of Hall scattering rate, γH˜aT2 . The spectral weight is suppressed with increasing temperature and disappears at T=120K . The incoherent carrier response is centered at mid-IR frequency and shifts to lower energy with increasing T . The infrared Hall constant is positive and almost independent of temperature, in sharp contrast with the dc Hall constant and theoretical predictions.

  13. Study of the catastrophic discharge phenomenon in a Hall thruster (United States)

    Ding, Yongjie; Su, Hongbo; Li, Peng; Wei, Liqiu; Li, Hong; Peng, Wuji; Xu, Yu; Sun, Hezhi; Yu, Daren


    In a 1350-W Hall-effect thruster, in which a technique for pushing down the magnetic field is implemented, a catastrophic discharge phenomenon is identified by varying the magnetic field strength while keeping all other operating parameters constant. According to experiments, before and after the discharge catastrophe, the plume changes from focusing state to a divergent state, and discharge parameters such as discharge current and thrust exhibit noticeable changes. The divergence half-angle of the plume increases from 22° to 46°. The oscillation amplitude and mean values of the discharge current significantly increase from 0.8 A to 4 A and from 4.6 A to 6.3 A, respectively, while the thrust increases from 89.3 mN to 91 mN. Analysis of the experimental results shows that as the maximum magnetic field of the thruster we developed is in the plume region, the acceleration occurs in the plume region and a large number of Xe2+ ions appear in the plume area, the catastrophic discharge phenomenon observed.

  14. Magnetoresistance, electrical conductivity, and Hall effect of glassy carbon

    Energy Technology Data Exchange (ETDEWEB)

    Baker, D.F.


    These properties of glassy carbon heat treated for three hours between 1200 and 2700/sup 0/C were measured from 3 to 300/sup 0/K in magnetic fields up to 5 tesla. The magnetoresistance was generally negative and saturated with reciprocal temperature, but still increased as a function of magnetic field. The maximum negative magnetoresistance measured was 2.2% for 2700/sup 0/C material. Several models based on the negative magnetoresistance being proportional to the square of the magnetic moment were attempted; the best fit was obtained for the simplest model combining Curie and Pauli paramagnetism for heat treatments above 1600/sup 0/C. Positive magnetoresistance was found only in less than 1600/sup 0/C treated glassy carbon. The electrical conductivity, of the order of 200 (ohm-cm)/sup -1/ at room temperature, can be empirically written as sigma = A + Bexp(-CT/sup -1/4) - DT/sup -1/2. The Hall coefficient was independent of magnetic field, insensitive to temperature, but was a strong function of heat treatment temperature, crossing over from negative to positive at about 1700/sup 0/C and ranging from -0.048 to 0.126 cm/sup 3//coul. The idea of one-dimensional filaments in glassy carbon suggested by the electrical conductivity is compatible with the present consensus view of the microstructure.

  15. Quantum Spin Hall Effect in Inverted Type II Semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Chaoxing; /Tsinghua U., Beijing /Stanford U., Phys. Dept.; Hughes, Taylor L.; Qi, Xiao-Liang; /Stanford U., Phys. Dept.; Wang, Kang; /UCLA; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.


    The quantum spin Hall (QSH) state is a topologically non-trivial state of quantum matter which preserves time-reversal symmetry; it has an energy gap in the bulk, but topologically robust gapless states at the edge. Recently, this novel effect has been predicted and observed in HgTe quantum wells. In this work we predict a similar effect arising in Type-II semiconductor quantum wells made from InAs/GaSb/AlSb. Because of a rare band alignment the quantum well band structure exhibits an 'inverted' phase similar to CdTe/HgTe quantum wells, which is a QSH state when the Fermi level lies inside the gap. Due to the asymmetric structure of this quantum well, the effects of inversion symmetry breaking and inter-layer charge transfer are essential. By standard self-consistent calculations, we show that the QSH state persists when these corrections are included, and a quantum phase transition between the normal insulator and the QSH phase can be electrically tuned by the gate voltage.

  16. High-Efficiency Hall Thruster Discharge Power Converter (United States)

    Jaquish, Thomas


    Busek Company, Inc., is designing, building, and testing a new printed circuit board converter. The new converter consists of two series or parallel boards (slices) intended to power a high-voltage Hall accelerator (HiVHAC) thruster or other similarly sized electric propulsion devices. The converter accepts 80- to 160-V input and generates 200- to 700-V isolated output while delivering continually adjustable 300-W to 3.5-kW power. Busek built and demonstrated one board that achieved nearly 94 percent efficiency the first time it was turned on, with projected efficiency exceeding 97 percent following timing software optimization. The board has a projected specific mass of 1.2 kg/kW, achieved through high-frequency switching. In Phase II, Busek optimized to exceed 97 percent efficiency and built a second prototype in a form factor more appropriate for flight. This converter then was integrated with a set of upgraded existing boards for powering magnets and the cathode. The program culminated with integrating the entire power processing unit and testing it on a Busek thruster and on NASA's HiVHAC thruster.

  17. Novel Planar Hall Effect in the Surface of Topological Insulators (United States)

    Taskin, Alexey; Legg, Henry; Yang, Fan; Sasaki, Satoshi; Kanai, Yasushi; Matsumoto, Kazuhiko; Rosch, Achim; Ando, Yoichi

    The progress in the study of topological materials depends on the ability to measure their surface properties. Recent advances in MBE growth allowed us to obtain suitable topological insulators (TIs). Here we report a magneto-transport study of high-quality bulk-insulating Bi2-xSbxTe3 thin films, which were fabricated into devices with electrostatic gates on both bottom and top surfaces. For magnetic fields applied parallel to the surface of a TI, we found a clear anisotropy in magnetoresistance (MR) and related planar Hall effect. This anisotropy is a consequence of two fundamental facts: 1) the time-reversal symmetry is broken by the magnetic field, lifting the topological protection of spin-momentum locked Dirac electrons against backscattering from impurities; 2) the in-plane magnetic field does not open the gap in the surface state, preserving the Dirac physics. As a result the back scattering protection can still be maintained for electrons with spins parallel/antiparallel to the direction of the magnetic field, giving rise to the scattering-rate anisotropy. The key signature of anisotropic MR is a strong dependence on the gate voltage with a characteristic two-peak structure near the Dirac point, which was observed by employing the dual-gating technique.

  18. Cluster multipole theory for anomalous Hall effect in antiferromagnets (United States)

    Suzuki, M.-T.; Koretsune, T.; Ochi, M.; Arita, R.


    We introduce a cluster extension of multipole moments to discuss the anomalous Hall effect (AHE) in both ferromagnetic (FM) and antiferromagnetic (AFM) states in a unified framework. We first derive general symmetry requirements for the AHE in the presence or absence of the spin-orbit coupling by considering the symmetry of the Berry curvature in k space. The cluster multipole (CMP) moments are then defined to quantify the macroscopic magnetization in noncollinear AFM states as a natural generalization of the magnetization in FM states. We identify the macroscopic CMP order which induces the AHE. The theoretical framework is applied to the noncollinear AFM states of Mn3Ir , for which an AHE was predicted in a first-principles calculation, and Mn3Z (Z =Sn ,Ge ), for which a large AHE was recently discovered experimentally. We further compare the AHE in Mn3Z and bcc Fe in terms of the CMP. We show that the AHE in Mn3Z is characterized by the magnetization of a cluster octupole moment in the same manner as that in bcc Fe characterized by the magnetization of the dipole moment.

  19. Superconducting Analogue of the Parafermion Fractional Quantum Hall States

    Directory of Open Access Journals (Sweden)

    Abolhassan Vaezi


    Full Text Available Read-Rezayi Z_{k} parafermion wave functions describe ν=2+(k/kM+2 fractional quantum Hall (FQH states. These states support non-Abelian excitations from which protected quantum gates can be designed. However, there is no experimental evidence for these non-Abelian anyons to date. In this paper, we study the ν=2/k FQH-superconductor heterostructure and find the superconducting analogue of the Z_{k} parafermion FQH state. Our main tool is the mapping of the FQH into coupled one-dimensional chains, each with a pair of counterpropagating modes. We show that by inducing intrachain pairing and charge preserving backscattering with identical couplings, the one-dimensional chains flow into gapless Z_{k} parafermions when k<4. By studying the effect of interchain coupling, we show that every parafermion mode becomes massive except for the two outermost ones. Thus, we achieve a fractional topological superconductor whose chiral edge state is described by a Z_{k} parafermion conformal field theory. For instance, we find that a ν=2/3 FQH in proximity to a superconductor produces a Z_{3} parafermion superconducting state. This state is topologically indistinguishable from the non-Abelian part of the ν=12/5 Read-Rezayi state. Both of these systems can host Fibonacci anyons capable of performing universal quantum computation through braiding operations.

  20. Robust electron pairing in the integer quantum hall effect regime (United States)

    Choi, H. K.; Sivan, I.; Rosenblatt, A.; Heiblum, M.; Umansky, V.; Mahalu, D.


    Electron pairing is a rare phenomenon appearing only in a few unique physical systems; for example, superconductors and Kondo-correlated quantum dots. Here, we report on an unexpected electron pairing in the integer quantum Hall effect regime. The pairing takes place within an interfering edge channel in an electronic Fabry-Perot interferometer at a wide range of bulk filling factors, between 2 and 5. We report on three main observations: high-visibility Aharonov-Bohm conductance oscillations with magnetic flux periodicity equal to half the magnetic flux quantum; an interfering quasiparticle charge equal to twice the elementary electron charge as revealed by quantum shot noise measurements, and full dephasing of the pairs' interference by induced dephasing of the adjacent inner edge channel--a manifestation of inter-channel entanglement. Although this pairing phenomenon clearly results from inter-channel interaction, the exact mechanism that leads to electron-electron attraction within a single edge channel is not clear. We believe that substantial efforts are needed in order to clarify these intriguing and unexpected findings.

  1. Thermal stability of the krypton Hall effect thruster

    Directory of Open Access Journals (Sweden)

    Szelecka Agnieszka


    Full Text Available The Krypton Large IMpulse Thruster (KLIMT ESA/PECS project, which has been implemented in the Institute of Plasma Physics and Laser Microfusion (IPPLM and now is approaching its final phase, was aimed at incremental development of a ~500 W class Hall effect thruster (HET. Xenon, predominantly used as a propellant in the state-of-the-art HETs, is extremely expensive. Krypton has been considered as a cheaper alternative since more than fifteen years; however, to the best knowledge of the authors, there has not been a HET model especially designed for this noble gas. To address this issue, KLIMT has been geared towards operation primarily with krypton. During the project, three subsequent prototype versions of the thruster were designed, manufactured and tested, aimed at gradual improvement of each next exemplar. In the current paper, the heat loads in new engine have been discussed. It has been shown that thermal equilibrium of the thruster is gained within the safety limits of the materials used. Extensive testing with both gases was performed to compare KLIMT’s thermal behaviour when supplied with krypton and xenon propellants.

  2. Habitat Restoration/Enhancement Fort Hall Reservation : 2008 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Osborne, Hunter [Shoshone Bannock Tribes


    Habitat enhancement, protection and monitoring were the focus of the Resident Fisheries Program during 2008. Enhancement and protection included sloping, fencing and planting wetlands plugs at sites on Spring Creek (Head-waters). Many previously constructed instream structures (rock barbs and wing dams) were repaired throughout the Fort Hall Indian Reservation (Reservation). Physical sampling during 2008 included sediment and depth measurements (SADMS) in Spring Creek at the Car Removal site. SADMS, used to track changes in channel morphology and specifically track movements of silt through Bottoms stream systems were completed for 5 strata on Spring Creek. Water temperature and chemistry were monitored monthly on Spring Creek, Clear Creek, Diggie Creek, and Portneuf (Jimmy Drinks) and Blackfoot rivers. Fish population densities and biomass were sampled in five reservation streams which included nine sites. Sampling protocols were identical to methods used in past years. Numbers of fish in Spring Creek series remained relatively low, however, there was an increase of biomass overall since 1993. Salmonid fry densities were monitored near Broncho Bridge and were similar to 2006, and 2007, however, as in years past, high densities of macrophytes make it very difficult to see fry in addition to lack of field technicians. Mean catch rate by anglers on Bottoms streams stayed the same as 2007 at 1.5/hr. Numbers of fish larger than 18-inches caught by anglers increased from 2007 at .20 to .26/hr.

  3. Fort Hall Reservation Stream Enhancement : 1999 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Moser, David C.


    Habitat enhancement and protection were the main focus of the Resident Fish Program during 1999. Biotic sampling included a genetic survey of salmonids on the Fort Hall Reservation. In addition, density and biomass of fish in select Bottoms streams was monitored. Enhancement and protection included anchoring 1,327 m of evergreen tree revetments and erecting three kilometers of enclosure fence. Physical sampling during 1999 included sediment and depth surveys and chemical measurements. Baseline SADM's, used to track changes in channel morphology and specifically track movements of silt through the system were completed for eight strata in Big Jimmy Creek. Numbers of fish in Clear creek were much lower than previous years. In addition, numbers of fry counted at Broncho Bridge were significantly lower than previous years. Future monitoring will determine whether low numbers are cyclic and related to weak year classes or low numbers are the result of anthropogenic influences. Permit fishing seasons continued to provide a source of income for the Tribes and an opportunity for non-tribal members to fish Bottoms streams. Mean catch rate by anglers on Bottoms streams increased from that of previous years to 1.02 fish per hour.

  4. Domain wall assisted GMR head with spin-Hall effect

    Energy Technology Data Exchange (ETDEWEB)

    Arun, R., E-mail: [Centre for Nonlinear Dynamics, School of Physics, Bharathidasan University, Tiruchirappalli - 620 024 (India); Sabareesan, P., E-mail: [Centre for Nonlinear Science and Engineering, School of Electrical and Electronics Engineering, SASTRA University, Thanjavur - 613 401 (India); Daniel, M., E-mail: [Centre for Nonlinear Dynamics, School of Physics, Bharathidasan University, Tiruchirappalli - 620 024 (India); SNS Institutions, Coimbatore - 641 049, Tamilnadu (India)


    We theoretically study the dynamics of a field induced domain wall in the Py/Pt bi-layer structure in the presence of spin-Hall effect (SHE) by solving the Landau-Lifshitz-Gilbert (LLG) equation along with the adiabatic, nonadiabatic and SHE spin-transfer torques (STTs). It is observed that a weak magnetic field moves the domain wall with high velocity in the presence of SHE and the direction of the velocity is changed by changing the direction of the weak field. The numerical results show that the magnetization of the ferromagnetic layer can be reversed quickly through domain wall motion by changing the direction of a weak external field in the presence of SHE while the direction of current is fixed. The SHE reduces the magnetization reversal time of 1000 nm length strip by 14.7 ns. This study is extended to model a domain wall based GMR (Giant Magnetoresistance) read head with SHE.

  5. Stochastic geometry in disordered systems, applications to quantum Hall transitions (United States)

    Gruzberg, Ilya


    A spectacular success in the study of random fractal clusters and their boundaries in statistical mechanics systems at or near criticality using Schramm-Loewner Evolutions (SLE) naturally calls for extensions in various directions. Can this success be repeated for disordered and/or non-equilibrium systems? Naively, when one thinks about disordered systems and their average correlation functions one of the very basic assumptions of SLE, the so called domain Markov property, is lost. Also, in some lattice models of Anderson transitions (the network models) there are no natural clusters to consider. Nevertheless, in this talk I will argue that one can apply the so called conformal restriction, a notion of stochastic conformal geometry closely related to SLE, to study the integer quantum Hall transition and its variants. I will focus on the Chalker-Coddington network model and will demonstrate that its average transport properties can be mapped to a classical problem where the basic objects are geometric shapes (loosely speaking, the current paths) that obey an important restriction property. At the transition point this allows to use the theory of conformal restriction to derive exact expressions for point contact conductances in the presence of various non-trivial boundary conditions.

  6. Electric field control photo-induced Hall currents in semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Miah, M. Idrish [Nanoscale Science and Technology Centre, Griffith University, Nathan, Brisbane, QLD 4111 (Australia); Department of Physics, University of Chittagong, Chittagong, Chittagong 4331 (Bangladesh)], E-mail:


    We generate spin-polarized carrier populations in GaAs and low temperature-grown GaAs (LT-GaAs) by circularly polarized optical beams and pull them by external electric fields to create spin-polarized currents. In the presence of the optically generated spin currents, anomalous Hall currents with an enhancement with increasing doping are observed and found to be almost steady in moderate electric fields up to {approx}120 mV {mu}m{sup -1}, indicating that photo-induced spin orientation of electrons is preserved in these systems. However, a field {approx}300 mV {mu}m{sup -1} completely destroys the electron spin polarization due to an increase of the D'yakonov-Perel' spin precession frequency of the hot electrons. This suggests that high field carrier transport conditions might not be suitable for spin-based technology with GaAs and LT-GaAs. It is also demonstrated that the presence of the excess arsenic sites in LT-GaAs might not affect the spin relaxation by Bir-Aronov-Pikus mechanism owing to a large number of electrons in n-doped materials.

  7. Teorema de Hall y un algoritmo para detectar sistemas de representantes distintos

    Directory of Open Access Journals (Sweden)

    Edwin Carranza Vargas


    Full Text Available Este trabajo presenta dos aportes a la combinatoria aplicada el primerola relación de equivalencia de los Teoremas de Ford- Fulkerson, Menger,Köning, Dilworth y Hall, además presenta una nueva prueba al Teoremade Hall que sirve como algoritmo para detectar sistemas de representantes distintos.En cada sección se establecen generalidades de los teoremas mencionados y finalmente el algoritmo con su respectiva justificación.

  8. Dynamic Particle Weight Remapping in Hybrid PIC Hall-effect Thruster Simulation (United States)


    Paper 3. DATES COVERED (From - To) May 2015-July 2015 4. TITLE AND SUBTITLE Dynamic Particle Weight Remapping in Hybrid PIC Hall-effect Thruster...macroparticle growth and distribution and statistical noise are key challenges for particle kinetic models such as particle-in-cell ( PIC ). For hybrid fluid... PIC models such as those commonly used in Hall-effect thruster (HET) simulation, the statistical noise adds an additional challenge due to the

  9. Prediction of a quantum anomalous Hall state in Co-decorated silicene

    KAUST Repository

    Kaloni, Thaneshwor P.


    Based on first-principles calculations, we demonstrate that Co-decorated silicene can host a quantum anomalous Hall state. The exchange field induced by the Co atoms combined with the strong spin-orbit coupling of the silicene opens a nontrivial band gap at the K point. As compared to other transition metals, Co-decorated silicene is unique in this respect, since usually hybridization and spin-polarization induced in the silicene suppress a quantum anomalous Hall state.

  10. Quantum fluctuation theorem in an interacting setup: point contacts in fractional quantum Hall edge state devices. (United States)

    Komnik, A; Saleur, H


    We verify the validity of the Cohen-Gallavotti fluctuation theorem for the strongly correlated problem of charge transfer through an impurity in a chiral Luttinger liquid, which is realizable experimentally as a quantum point contact in a fractional quantum Hall edge state device. This is accomplished via the development of an analytical method to calculate the full counting statistics of the problem in all the parameter regimes involving the temperature, the Hall voltage, and the gate voltage.

  11. Alcohol Trajectories over Three Years in a Swedish Residence Hall Student Population


    Henriettae Ståhlbrandt; Anders Leifman; Johnsson, Kent O.; Mats Berglund


    Although it is known that college students have a high alcohol consumption, less is known about the long-term drinking trajectories amongst college students and, in particular, students living in residence halls, known to be high-risk drinkers. Over four consecutive years, the drinking habits of 556 Swedish residence hall students were analyzed. The main instruments for measuring outcome were AUDIT (Alcohol Use Identification Disorders Test), SIP (Short Index of Problems) and eBAC (estimated ...

  12. Stuart Hall sobre raza y racismo: estudios culturales y la práctica del contextualismo

    Directory of Open Access Journals (Sweden)

    Lawrence Grossberg


    Full Text Available El trabajo de Stuart Hall sobre la raza no puede separarse de su trabajo sobre los estudios culturales, y en particular, de su compromiso con un contextualismo radical. En este artículo, argumento que la obra de Stuart Hall sobre raza y racismo en el contexto de su compromiso de larga data con una práctica radicalmente contextualista y con la noción de la especificidad histórica en particular.

  13. An Overview of Preformed Metal Crowns. Part 2: The Hall Technique. (United States)

    Hyde, Amy C; Rogers, Helen J; Batley, Haris A; Morgan, Annie G; Deery, Chris


    Part 2 of this series of two articles addresses the Hall Technique for preformed metal crowns. It will discuss the need for an effective child and dentist friendly method to restore carious primary molars. The technique is described in detail and the evidence for its effectiveness and acceptance by children, parents, dentists and dental educators is presented. CPD/Clinical Relevance: Dentists and dental care professionals should be aware of the evidence to support the adoption of the Hall Technique.

  14. Global Linear Stability Analysis of the Spoke Oscillation in Hall Effect Thrusters (United States)


    Stubbers, B.E. Jurczyk, et al. Hall Thruster Electron Mobility Investigation using Full 3DMonte Carlo Trajectory Simulations. In Proceedings of the...112] A. Dinklage, T. Klinger, G. Marx , and L. Schweikhard. Plasma physics: confinement, transport and collective effects. Berlin Springer Verlag...Garrigues. Study of stochastic effects in a Hall effect thruster using a test particles Monte- Carlo model. In Proceedings of the 32nd International

  15. Magnetic field deformation due to electron drift in a Hall thruster

    Directory of Open Access Journals (Sweden)

    Han Liang


    Full Text Available The strength and shape of the magnetic field are the core factors in the design of the Hall thruster. However, Hall current can affect the distribution of static magnetic field. In this paper, the Particle-In-Cell (PIC method is used to obtain the distribution of Hall current in the discharge channel. The Hall current is separated into a direct and an alternating part to calculate the induced magnetic field using Finite Element Method Magnetics (FEMM. The results show that the direct Hall current decreases the magnetic field strength in the acceleration region and also changes the shape of the magnetic field. The maximum reduction in radial magnetic field strength in the exit plane is 10.8 G for an anode flow rate of 15 mg/s and the maximum angle change of the magnetic field line is close to 3° in the acceleration region. The alternating Hall current induces an oscillating magnetic field in the whole discharge channel. The actual magnetic deformation is shown to contain these two parts.

  16. Magnetic field deformation due to electron drift in a Hall thruster (United States)

    Liang, Han; Yongjie, Ding; Xu, Zhang; Liqiu, Wei; Daren, Yu


    The strength and shape of the magnetic field are the core factors in the design of the Hall thruster. However, Hall current can affect the distribution of static magnetic field. In this paper, the Particle-In-Cell (PIC) method is used to obtain the distribution of Hall current in the discharge channel. The Hall current is separated into a direct and an alternating part to calculate the induced magnetic field using Finite Element Method Magnetics (FEMM). The results show that the direct Hall current decreases the magnetic field strength in the acceleration region and also changes the shape of the magnetic field. The maximum reduction in radial magnetic field strength in the exit plane is 10.8 G for an anode flow rate of 15 mg/s and the maximum angle change of the magnetic field line is close to 3° in the acceleration region. The alternating Hall current induces an oscillating magnetic field in the whole discharge channel. The actual magnetic deformation is shown to contain these two parts.

  17. Exploring 4D quantum Hall physics with a 2D topological charge pump. (United States)

    Lohse, Michael; Schweizer, Christian; Price, Hannah M; Zilberberg, Oded; Bloch, Immanuel


    The discovery of topological states of matter has greatly improved our understanding of phase transitions in physical systems. Instead of being described by local order parameters, topological phases are described by global topological invariants and are therefore robust against perturbations. A prominent example is the two-dimensional (2D) integer quantum Hall effect: it is characterized by the first Chern number, which manifests in the quantized Hall response that is induced by an external electric field. Generalizing the quantum Hall effect to four-dimensional (4D) systems leads to the appearance of an additional quantized Hall response, but one that is nonlinear and described by a 4D topological invariant-the second Chern number. Here we report the observation of a bulk response with intrinsic 4D topology and demonstrate its quantization by measuring the associated second Chern number. By implementing a 2D topological charge pump using ultracold bosonic atoms in an angled optical superlattice, we realize a dynamical version of the 4D integer quantum Hall effect. Using a small cloud of atoms as a local probe, we fully characterize the nonlinear response of the system via in situ imaging and site-resolved band mapping. Our findings pave the way to experimentally probing higher-dimensional quantum Hall systems, in which additional strongly correlated topological phases, exotic collective excitations and boundary phenomena such as isolated Weyl fermions are predicted.

  18. Spin Chirality and Hall-Like Transport Phenomena of Spin Excitations (United States)

    Han, Jung Hoon; Lee, Hyunyong


    Experimental and theoretical aspects of Hall-type transport of spins in magnetic insulators are reviewed. A general formalism for linear response theory of thermal Hall transport in the spin model is developed, which is general enough to be applicable to both the magnon and the paramagnetic, spin-liquid regimes. The expression of the energy current operator in the spin language is shown to be closely related to the spin chirality operator. Recent experiments on magnon-mediated thermal Hall transport in the two-dimensional kagome, and three-dimensional pyrochlore ferromagnetic insulators are reviewed in light of the multi-band magnon theory of Hall transport, and compared to the more mysterious thermal Hall transport found in the putative quantum spin ice material. As realizations of spin-chirality driven magnon transport in the real space, we review the general theory of emergent gauge fields governing the magnon dynamics in the textured magnet, and discuss its application to the magnon-Skyrmion scattering problem. Topological magnon Hall effect driven by the Skyrmion texture is discussed.

  19. The signal-to-noise ratio and a hidden symmetry of Hall plates (United States)

    Ausserlechner, Udo


    In a Hall plate with finite size and contacts the Hall output voltage is given by the product of sheet resistance, input current, Hall mobility, magnetic flux density, and Hall geometry factor GH . GH ∈ [ 0, 1 ] accounts for the loss in signal due to the contacts. At weak magnetic field GH →GH0 is a function of geometrical parameters only, which makes it the crucial point for layout optimization. We show how to express GH0 alternatively as a function of electrical parameters only, namely of input and output resistances over sheet resistance. This allows for an analytical optimization of signal-to-noise-ratio (SNR) without getting lost in the multitude of geometrical representations of equivalent Hall plates. In the course of this investigation we notice a hidden symmetry property of GH , which we prove rigorously in the limit of small magnetic fields. The physical meaning of this symmetry in the case of Hall plates with equal input and output resistances is also explained.

  20. Using nutrition labeling as a potential tool for changing eating habits of university dining hall patrons. (United States)

    Driskell, Judy A; Schake, Marian C; Detter, Hillary A


    The purpose of this cross-sectional study was to examine the influence of the nutritional labeling Nutrition Bytes on the eating habits of adults eating in dining halls at a Midwestern university and to assess differences between sexes. Dining hall patrons (114 men, 91 women) 19 years of age or older voluntarily completed a descriptive 15-item written questionnaire that examined the use and nonuse of Nutrition Bytes, which contains much of the information included in the Nutrition Facts label. A significantly higher percentage of women than men patrons reported currently using Nutrition Bytes labels (PNutrition Bytes labels were: general knowledge, concern about overall health, calorie counting, and concern about a certain nutrient(s). Predominant reasons given for not using Nutrition Bytes labels were: will not change my mind about food items selected and not enough time. Reasons given by men and women for using or not using Nutrition Bytes labels were similar. Significantly higher percentages of women than men using Nutrition Bytes labels indicated being interested in having serving sizes (Pusers who indicated nearly always and sometimes changing their food choices after reading Nutrition Bytes labels inside the dining halls were 12% and 80%, respectively, whereas 23% and 65%, respectively, indicated changing their food choices after reading the nutrition label when eating outside the dining halls. Nutrition Bytes labeling seemed to positively impact food choices of these adult dining hall patrons, and likely would do so at other dining halls.

  1. Algorithm and exploratory study of the Hall MHD Rayleigh-Taylor instability.

    Energy Technology Data Exchange (ETDEWEB)

    Gardiner, Thomas Anthony


    This report is concerned with the influence of the Hall term on the nonlinear evolution of the Rayleigh-Taylor (RT) instability. This begins with a review of the magnetohydrodynamic (MHD) equations including the Hall term and the wave modes which are present in the system on time scales short enough that the plasma can be approximated as being stationary. In this limit one obtains what are known as the electron MHD (EMHD) equations which support two characteristic wave modes known as the whistler and Hall drift modes. Each of these modes is considered in some detail in order to draw attention to their key features. This analysis also serves to provide a background for testing the numerical algorithms used in this work. The numerical methods are briefly described and the EMHD solver is then tested for the evolution of whistler and Hall drift modes. These methods are then applied to study the nonlinear evolution of the MHD RT instability with and without the Hall term for two different configurations. The influence of the Hall term on the mixing and bubble growth rate are analyzed.

  2. A portable Hall magnetometer probe for characterization of magnetic iron oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Araujo, Jefferson F.D.F.; Costa, Mateus C.; Louro, Sonia R.W.; Bruno, Antonio C., E-mail:


    We have built a portable Hall magnetometer probe, for measuring magnetic properties of iron oxide nanoparticles, that can be used for bulk materials and liquid samples as well. The magnetometer probe consists of four voltage-programmable commercial Hall sensors and a thin acrylic plate for positioning the sensors. In order to operate, it needs to be attached to a pole of an electromagnet and connected to an AD converter and a computer. It acquires a complete magnetization curve in a couple of minutes and has a magnetic moment sensitivity of 3.5×10{sup −7} Am{sup 2}. We tested its performance with magnetic nanoparticles containing an iron oxide core and having coating layers with different sizes. The magnetization results obtained were compared with measurements performed on commercial stand-alone magnetometers, and exhibited errors of about ±0.2 Am{sup 2}/kg (i.e 0.4%) at saturation and below 0.5 Am{sup 2}/kg (i.e. 10%) at remanence. - Highlights: • A low-cost portable Hall magnetometer probe has been built. • The Hall magnetometer probe can be attached to any electromagnet. • The Hall probe was calibrated and successfully compared to industry standard magnetometers. • The Hall probe was able to measure iron oxide nanoparticles with different coatings.

  3. Evaluation of stage acoustics in Seoul Arts Center Concert Hall by measuring stage support. (United States)

    Jeon, Jin Yong; Barron, Michael


    Stage acoustics is an important characteristic for concert halls, both for the acoustic quality on stage and for the audience. However, relatively little research has been conducted into the question. This study was based on the investigation of an actual concert hall stage, that of the Seoul Arts Center Concert Hall in Korea. The stage acoustics was evaluated in the actual hall, and with two models: a 1:25 scale model and a computer model. The study was based on the stage support parameter ST1 proposed by Gade as a measure of support for individual performers [Acustica 65, 193-203 (1989)]. The variation of support was measured on the empty stage of the actual hall and in the two models. The effect of musicians on stage, the effect of moving the orchestra, the effect of ceiling height and of stage-wall profile were also investigated. Conclusions are drawn both relating to the Seoul Concert Hall stage and stages in general.

  4. 3D Quantum Hall Effect of Fermi Arc in Topological Semimetals (United States)

    Wang, C. M.; Sun, Hai-Peng; Lu, Hai-Zhou; Xie, X. C.


    The quantum Hall effect is usually observed in 2D systems. We show that the Fermi arcs can give rise to a distinctive 3D quantum Hall effect in topological semimetals. Because of the topological constraint, the Fermi arc at a single surface has an open Fermi surface, which cannot host the quantum Hall effect. Via a "wormhole" tunneling assisted by the Weyl nodes, the Fermi arcs at opposite surfaces can form a complete Fermi loop and support the quantum Hall effect. The edge states of the Fermi arcs show a unique 3D distribution, giving an example of (d -2 )-dimensional boundary states. This is distinctly different from the surface-state quantum Hall effect from a single surface of topological insulator. As the Fermi energy sweeps through the Weyl nodes, the sheet Hall conductivity evolves from the 1 /B dependence to quantized plateaus at the Weyl nodes. This behavior can be realized by tuning gate voltages in a slab of topological semimetal, such as the TaAs family, Cd3 As2 , or Na3Bi . This work will be instructive not only for searching transport signatures of the Fermi arcs but also for exploring novel electron gases in other topological phases of matter.

  5. 3D Quantum Hall Effect of Fermi Arcs in Topological Semimetals. (United States)

    Wang, C M; Sun, Hai-Peng; Lu, Hai-Zhou; Xie, X C


    The quantum Hall effect is usually observed in 2D systems. We show that the Fermi arcs can give rise to a distinctive 3D quantum Hall effect in topological semimetals. Because of the topological constraint, the Fermi arc at a single surface has an open Fermi surface, which cannot host the quantum Hall effect. Via a "wormhole" tunneling assisted by the Weyl nodes, the Fermi arcs at opposite surfaces can form a complete Fermi loop and support the quantum Hall effect. The edge states of the Fermi arcs show a unique 3D distribution, giving an example of (d-2)-dimensional boundary states. This is distinctly different from the surface-state quantum Hall effect from a single surface of topological insulator. As the Fermi energy sweeps through the Weyl nodes, the sheet Hall conductivity evolves from the 1/B dependence to quantized plateaus at the Weyl nodes. This behavior can be realized by tuning gate voltages in a slab of topological semimetal, such as the TaAs family, Cd_{3}As_{2}, or Na_{3}Bi. This work will be instructive not only for searching transport signatures of the Fermi arcs but also for exploring novel electron gases in other topological phases of matter.

  6. The rotation of discs around neutron stars: dependence on the Hall diffusion (United States)

    Faghei, Kazem; Salehi, Fatemeh


    In this paper, we study the dynamics of a geometrically thin, steady and axisymmetric accretion disc surrounding a rotating and magnetized star. The magnetic field lines of star penetrate inside the accretion disc and are twisted due to the differential rotation between the magnetized star and the disc. We apply the Hall diffusion effect in the accreting plasma, because of the Hall diffusion plays an important role in both fully ionized plasma and weakly ionized medium. In the current research, we show that the Hall diffusion is also an important mechanism in accreting plasma around neutron stars. For the typical system parameter values associated with the accreting X-ray binary pulsar, the angular velocity of the inner regions of disc departs outstandingly from Keplerian angular velocity, due to coupling between the magnetic field of neutron star and the rotating plasma of disc. We found that the Hall diffusion is very important in inner disc and increases the coupling between the magnetic field of neutron star and accreting plasma. On the other word, the rotational velocity of inner disc significantly decreases in the presence of the Hall diffusion. Moreover, the solutions imply that the fastness parameter decreases and the angular velocity transition zone becomes broad for the accreting plasma including the Hall diffusion.

  7. Exploring 4D quantum Hall physics with a 2D topological charge pump (United States)

    Lohse, Michael; Schweizer, Christian; Price, Hannah M.; Zilberberg, Oded; Bloch, Immanuel


    The discovery of topological states of matter has greatly improved our understanding of phase transitions in physical systems. Instead of being described by local order parameters, topological phases are described by global topological invariants and are therefore robust against perturbations. A prominent example is the two-dimensional (2D) integer quantum Hall effect: it is characterized by the first Chern number, which manifests in the quantized Hall response that is induced by an external electric field. Generalizing the quantum Hall effect to four-dimensional (4D) systems leads to the appearance of an additional quantized Hall response, but one that is nonlinear and described by a 4D topological invariant—the second Chern number. Here we report the observation of a bulk response with intrinsic 4D topology and demonstrate its quantization by measuring the associated second Chern number. By implementing a 2D topological charge pump using ultracold bosonic atoms in an angled optical superlattice, we realize a dynamical version of the 4D integer quantum Hall effect. Using a small cloud of atoms as a local probe, we fully characterize the nonlinear response of the system via in situ imaging and site-resolved band mapping. Our findings pave the way to experimentally probing higher-dimensional quantum Hall systems, in which additional strongly correlated topological phases, exotic collective excitations and boundary phenomena such as isolated Weyl fermions are predicted.

  8. The role of the men's hall in the development of the Anglo-Saxon superego. (United States)

    Earl, J W


    This paper is a historical study of ritual space--a bit of psychoanalytic anthropology applied to a particular case, the evolution of the men's hall among the early Anglo-Saxons. I focus particularly on the ritual functions of poetry in the hall, the same poetry which is our major evidence regarding the hall, especially the epic Beowulf. I define the hall as a cultural institution, and redefine the native poetic tradition in relation to the hall's varied ritual life, with which the poetry is so occupied. Though my argument is focused on the hall, it includes a framework of theoretical concerns. Early Anglo-Saxon culture is of anthropological interest chiefly because of its rapid and dramatic emergence from Germanic tribal prehistory into a leading role in the civilization of Christian Europe. The conquest of Britain by the Anglo-Saxons in the fifth and sixth centuries, and their conversion soon afterward, is a case history of the transformations of a tribal society suddenly introduced to the special forces of civilization and the higher religions that control them. The Anglo-Saxons are fascinating in this regard because of the fortuitous developments that prepared for this transformation and made it so successful.

  9. Synthesis and characterization of some metal complexes of a Schiff ...

    African Journals Online (AJOL)

    Sadtler Research Laboratories Inc. 1966 Standard Spectra, #21078K. 34. Bellamy, L.J. The Infrared Spectra of Complex Molecules, Vol. II, 2nd ed., Chapman and. Hall: New York; 1980. 35. Nakamoto, K. Infrared and Raman Spectra of Inorganic and Coordination Compounds, Part. B, 5th ed., John Wiley: New York; 1997.

  10. Effet Hall et Magnetisme des Alliages Amorphes Nickel-Zirconium Fabriques Par Pulverisation (United States)

    Morel, Robert

    Cette these se situe dans le cadre d'une etude des proprietes electroniques et structurales des alliages metalliques amorphes, en cours depuis quelques annees a l'Universite de Montreal. Ce programme nous a entre autres amene a caracteriser la magnetoresistivite et l'effet Hall d'alliages FeZr, CoZr et NiZr, ce qui a permis de mettre en evidence deux caracteristiques de l'effet Hall: Dans les alliages amorphes ferromagnetiques, la resistivite elevee engendre un effet Hall extraordinaire beaucoup plus important que celui enregistre dans les metaux cristallins. La polarisation des spins entrai ne une asymetrie de la diffusion qui, tant dans les phases cristalline et amorphe, est tenue responsable de cette contribution. L'autre particularite du comportement de Hall de ces systemes est le renversement de signe du coefficient de Hall ordinaire, qui passe du negatif au positif dans les echantillons plus riches en zirconium. Dans les metaux cristallins, un modele d'electrons libres predit un signe negatif a moins que la conduction ne soit dominee par les trous. Or, dans un milieu desordonne les memes concepts sont difficilement applicables et de nouvelles theories ont du etre elaborees pour expliquer ce phenomene. Jusqu'a maintenant, l'etude des alliages amorphes nickel-zirconium s'est faite surtout a partir d'echantillons fabriques par trempe sur roue. Malheureusement cette technique ne permet pas la fabrication d'alliages contenant plus de 70% de nickel, a l'exception du seul compose Ni _{90}Zr_{10 }. Pour pallier a cette lacune et etendre nos connaissance a l'ensemble de la gamme de compositions, nous avons fabrique par pulverisation cathodique des echantillons NiZr amorphes--et quelques alliages cristallins tres riches en nickel--couvrant une bonne partie de la gamme interdite par la technique de trempe sur roue. Dans un premier temps, par comparaison avec les resultats connus nous avons mis en evidence les similitudes et les differences entre les alliages obtenus par

  11. Deep Exclusive Pseudoscalar Meson Production at Jefferson Lab Hall C

    Energy Technology Data Exchange (ETDEWEB)

    Basnet, Samip [Univ. of Regina, SK (Canada)


    Measurements of exclusive meson production are a useful tool in the study of hadronic structure. In particular, one can discern the relevant degrees of freedom at different distance scales through these studies. In the transition region between low momentum transfer (where a description of hadronic degrees of freedom in terms of effective hadronic Lagrangians is valid) and high momentum transfer (where the degrees of freedom are quarks and gluons), the predictive power of Quantum Chromodynamics (QCD), the theory of the strong interaction, is limited due to the absence of a complete solution. Thus, one has to rely upon experimental data from the non-perturbative intermediate-energy regime to thoroughly understand the onset of perturbative QCD (pQCD) as the momentum transfer is increased. This work involves two deep exclusive meson electroproduction experiments at Jefferson Lab (JLab). The p(e,e'pi+)n reaction is studied at fixed Q^2 and W of 2.5 GeV2 and 2.0 GeV, respectively, while varying the four momentum transfer to the nucleon -t from 0.2 to 2.1 GeV2 . As -t is increased, the hadronic interaction scale is reduced independently of the observation scale of the virtual photon, providing valuable information about the hard- scattering process in general. The data was taken at JLab Hall C in 2003, as a part of the experiment E01-004, Fpi-2, using the High Momentum Spectrometer (HMS) and Short Orbit Spectrometer (SOS), and in this work, the results of the differential cross section analysis are presented and compared to prior data, as well as two theoretical models. Using these results over a wide -t range, the transition from hard to soft QCD is also studied. In addition, the p(e,e'K+)Lambda(Sigma0) reactions are also studied. Despite their importance in elucidating the reaction mechanism underlying strangeness production, we still do not have complete understanding of these reactions above the resonance region. The experiment, E12- 09-011, intends to

  12. Thermal evolution of the central Halls Creek Orogen, northern Australia

    Energy Technology Data Exchange (ETDEWEB)

    Bodorkos, S.; Cawood, P.A. [Curtin University of Technology, Perth, WA (Australia). Tectonics Special Research Centre, School of Applied Geology; Oliver, N.H.S. [James Cook University, Townsville, QLD (Australia). Economic Geology Research Unit, School of Earth Sciences


    The Halls Creek Orogen in northern Australia records the Palaeoproterozoic collision of the Kimberley Craton with the North Australian Craton. Integrated structural, metamorphic and geochronological studies of the Tickalara Metamorphics show that this involved a protracted episode of high temperature, low-pressure metamorphism associated with intense and prolonged mafic and felsic intrusive activity in the interval ca 1850-1820 Ma. Tectonothermal development of the region commenced with an inferred mantle perturbation event, probably at ca 1880 Ma. This resulted in the generation of mafic magmas in the upper mantle or lower crust, while upper crustal extension preceded the rapid deposition of the Tickalara sedimentary protoliths. An older age limit for these rocks is provided by a psammopelitic gneiss from the Tickalara Metamorphics, which yield a {sup 207}Pb/{sup 206}Pb SHRIMP age of 1867 {+-} 4 Ma for the youngest detrital zircon suite. Voluminous layered mafic intrusives were emplaced in the middle crust at ca 1860-1855 Ma. prior to the attainment of lower granulite facies peak metamorphic conditions in the middle crust. Locally preserved layer-parallel D{sub 1} foliations that were developed during prograde metamorphism were pervasively overprinted by the dominant regional S{sub 2} gneissosity coincident with peak metamorphism. Overgrowths on zircons record a metamorphic {sup 207}Pb/{sup 206}Pb age of 1845 {+-} 4 Ma. The S{sub 2} fabric is folded around tight folds and cut by ductile shear zones associated with D{sub 3} (ca 1830 Ma), and all pre-existing structures are folded around large-scale, open F{sub 4} folds (ca 1820 Ma). Construction of a temperature-time path for the mid-crustal section exposed in the central Halls Creek Orogen, based on detailed SHRIMP zircon data, key field relationships and petrological evidence, suggests the existence of one protracted thermal event (>400-500degC for 25-30 million years) encompassing two deformation phases

  13. The influence of basic design variables on the acoustics of concert halls; new results derived from analysing a large number of existing halls

    DEFF Research Database (Denmark)

    Gade, Anders Christian


    A large data base over values of various room acoustic parameters has provided the basis for statistical analyses of how and how much the acoustic properties of conert halls are influenced by their size, shape and absorption area (as deduced from measured reverberation time). The data have been...

  14. Obituary: R(oyal) Glenn Hall, 1921-2004 (United States)

    McCarthy, Dennis Dean


    R. Glenn Hall died on 25 June 2004 following a battle with prostate cancer. His contributions to the determination of the frequency corresponding to an energy level transition in the Cesium atom led to the definition of the length of the second and formed the basis for precise modern timekeeping. Glenn was born on 23 June 1921 in Koloa, Hawaii, and together with a brother and three sisters, grew up in Albion, Michigan. His father was a professor of political science at Albion College. He graduated from Park College in Parkville, Missouri with a degree in mathematics in 1941. He served as a corpsman in the U. S. Navy during World War II, and went on to earn a PhD at the University of Chicago in 1949. Glenn joined the faculty at the University of Chicago as an instructor from 1949 through 1952 and became a research associate there in 1953. While at the U. of Chicago he worked extensively on mass ratios of binary stars, binary star orbits and the determination of stellar parallaxes. In 1953 Glenn came to the U. S. Naval Observatory (USNO) where he became the Assistant Director of the Time Service Division. His early work at the Naval Observatory was related to the determination of Ephemeris Time (ET) from photographic observations of the Moon with respect to background stars. This work provided a time scale more uniform than that based on the Earth's rotation, which was the internationally accepted time scale at the time. As a result, the International Astronomical Union in 1955 redefined the second to be the second as determined from Ephemeris Time. In June 1955, L. Essen and J.V.L. Parry placed in operation a Cesium beam atomic standard at the National Physical Laboratory in Teddington, England. William Markowitz (1907-1998), the director of the Time Service, and Hall together with Essen and Parry then began the work leading to the determination of the frequency of the Cesium atom in terms of the second of the seasonally corrected time scale determined from the

  15. The Great British Music Hall: Its Importance to British Culture and ‘The Trivial’

    Directory of Open Access Journals (Sweden)

    Steven Gerrard


    Full Text Available By 1960, Britain’s once-thriving Music Hall industry was virtually dead. Theatres with their faded notions of Empire gave way to Cinema and the threat of Television. Where thousands once linked arms singing popular songs, watch acrobatics, see feats of strength, and listen to risqué jokes, now the echoes of those acts lay as whispers amongst the stalls’ threadbare seats. The Halls flourished in the 19th Century, but had their origins in the taverns of the 16th and 17th Centuries. Minstrels plied their trade egged on by drunken crowds. As time passed, the notoriety of the Music Hall acts and camaraderie produced grew. Entrepreneurial businessman tapped into this commerciality and had purpose-built status symbol theatres to provide a ‘home’ for acts and punters. With names like The Apollo giving gravitas approaching Olympian ideals, so the owners basked in wealth and glory. The Music Hall became the mass populist entertainment for the population. Every town had one, where everyone could be entertained by variety acts showing off the performers’ skills. The acts varied from singers, joke-tellers, comics, acrobats, to dancers. They all aimed to entertain. They enabled audiences to share a symbiotic relationship with one another; became recruitment officers for the Army; inspired War Poets; showed short films; and they and the halls reflected both the ideals and foibles of their era. By using Raymond Williams’ structures of feeling as its cornerstone, the article will give a brief history of the halls, whilst providing analysis into how they grew into mass populist entertainment that represented British culture. Case studies of famous artistes are given, plus an insight into how Music Hall segued into radio, film and television.

  16. A mobile ferromagnetic shape detection sensor using a Hall sensor array and magnetic imaging. (United States)

    Misron, Norhisam; Shin, Ng Wei; Shafie, Suhaidi; Marhaban, Mohd Hamiruce; Mailah, Nashiren Farzilah


    This paper presents a mobile Hall sensor array system for the shape detection of ferromagnetic materials that are embedded in walls or floors. The operation of the mobile Hall sensor array system is based on the principle of magnetic flux leakage to describe the shape of the ferromagnetic material. Two permanent magnets are used to generate the magnetic flux flow. The distribution of magnetic flux is perturbed as the ferromagnetic material is brought near the permanent magnets and the changes in magnetic flux distribution are detected by the 1-D array of the Hall sensor array setup. The process for magnetic imaging of the magnetic flux distribution is done by a signal processing unit before it displays the real time images using a netbook. A signal processing application software is developed for the 1-D Hall sensor array signal acquisition and processing to construct a 2-D array matrix. The processed 1-D Hall sensor array signals are later used to construct the magnetic image of ferromagnetic material based on the voltage signal and the magnetic flux distribution. The experimental results illustrate how the shape of specimens such as square, round and triangle shapes is determined through magnetic images based on the voltage signal and magnetic flux distribution of the specimen. In addition, the magnetic images of actual ferromagnetic objects are also illustrated to prove the functionality of mobile Hall sensor array system for actual shape detection. The results prove that the mobile Hall sensor array system is able to perform magnetic imaging in identifying various ferromagnetic materials.

  17. Hořava-Lifshitz gravity and effective theory of the fractional quantum Hall effect

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Chaolun [Kadanoff Center for Theoretical Physics and Enrico Fermi Institute, University of Chicago,Chicago, Illinois 60637 (United States); Wu, Shao-Feng [Department of Physics, Shanghai University,Shanghai 200444 (China); Kadanoff Center for Theoretical Physics and Enrico Fermi Institute, University of Chicago,Chicago, Illinois 60637 (United States)


    We show that Hořava-Lifshitz gravity theory can be employed as a covariant framework to build an effective field theory for the fractional quantum Hall effect that respects all the spacetime symmetries such as non-relativistic diffeomorphism invariance and anisotropic Weyl invariance as well as the gauge symmetry. The key to this formalism is a set of correspondence relations that maps all the field degrees of freedom in the Hořava-Lifshitz gravity theory to external background (source) fields among others in the effective action of the quantum Hall effect, according to their symmetry transformation properties. We originally derive the map as a holographic dictionary, but its form is independent of the existence of holographic duality. This paves the way for the application of Hořava-Lifshitz holography on fractional quantum Hall effect. Using the simplest holographic Chern-Simons model, we compute the low energy effective action at leading orders and show that it captures universal electromagnetic and geometric properties of quantum Hall states, including the Wen-Zee shift, Hall viscosity, angular momentum density and their relations. We identify the shift function in Hořava-Lifshitz gravity theory as minus of guiding center velocity and conjugate to guiding center momentum. This enables us to distinguish guiding center angular momentum density from the internal one, which is the sum of Landau orbit spin and intrinsic (topological) spin of the composite particles. Our effective action shows that Hall viscosity is minus half of the internal angular momentum density and proportional to Wen-Zee shift, and Hall bulk viscosity is half of the guiding center angular momentum density.

  18. Towards the Hall viscosity of the Fermi-liquid-like phase at the filling factor of 1/2 (United States)

    Milovanović, M. V.


    We discuss the Berry curvature calculations of the Hall viscosity for the Fermi-liquid-like state, i.e., a Fermi-liquid state of underlying composite particles of the Hall system. We conclude, within assumptions made, that in the linear response, with small deformation of the system and in the thermodynamic limit, the Hall viscosity takes the value characteristic for the Laughlin states. We present arguments that the value is the same even for general deformations in the same limit.

  19. Thermodynamic anomalous Hall effect in quantum oscillation regime in a semiconductor with low concentration of transition element impurities (United States)

    Lonchakov, A. T.; Okulov, V. I.; Pamyatnykh, E. A.; Bobin, S. B.; Deryushkin, V. V.; Govorkova, T. E.; Neverov, V. N.; Paranchich, L. D.


    The given report is devoted to the study of anomalous Hall resistance of donor electron system of hybridized states of transition element impurities of low concentration in quantum oscillation regime. There presented theoretical description of predicted specific behaviors on the base of the ideas about thermodynamic anomalous Hall effect. In experiments on mercury selenide crystals with cobalt impurities of low concentration one revealed the quantum oscillations of anomalous contribution to the Hall resistance corresponding to the developed concepts.

  20. Influence of defects and disorder on anomalous Hall effect and spin Seebeck effect on permalloy and Heusler compounds

    Energy Technology Data Exchange (ETDEWEB)

    Vilanova Vidal, Enrique


    In this work Heusler thin films have been prepared and their transport properties have been studied. Of particularly interest is the anomalous Hall effect (AHE). The effect is a long known but still not fully understood transport effect. Most theory papers focus on the influence of one particular contribution to the AHE. Actual measured experimental data, however, often are not in accordance with idealized assumptions. This thesis discusses the data analysis for materials with low residual resistivity ratios. As prototypical materials, half metallic Heusler compounds are studied. Here, the influence of defects and disorder is apparent in a material with a complex topology of the Fermi surface. Using films with different degrees of disorder, the different scattering mechanisms can be separated. For Co{sub 2}FeSi{sub 0.6}Al{sub 0.4} and Co{sub 2}FeGa{sub 0.5}Ge{sub 0.5}, the AHE induced by B2-type disorder and temperature-dependent scattering is positive, while DO{sub 3}-type disorder and possible intrinsic contributions possess a negative sign. For these compounds, magneto-optical Kerr effects (MOKE) are investigated. First order contributions as a function of intrinsic and extrinsic parameters are qualitatively analyzed. The relation between the crystalline ordering and the second order contributions to the MOKE signal is studied. In addition, sets of the Heusler compound Co{sub 2}MnAl thin films were grown on MgO(100) and Si(100) substrates by radio frequency magnetron sputtering. Composition, magnetic and transport properties were studied systematically for samples deposited at different conditions. In particular, the anomalous Hall effect resistivity presents an extraordinarily temperature independent behavior in a moderate magnetic field range from 0 to 0.6 T. The off-diagonal transport at temperatures up to 300 C was analyzed. The data show the suitability of the material for Hall sensors working well above room temperature. Recently, the spin Seebeck effect