A. Narayan - HKS - JLab E05-115 and E01-001 - Collaborations

A. Narayan
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A. Narayan
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HKS - JLab E05-115 and E01-001 - Collaborations
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Nuclear Experiment (16)
 
Physics - Mesoscopic Systems and Quantum Hall Effect (16)
 
Mathematics - Numerical Analysis (12)
 
Physics - Materials Science (11)
 
Physics - Instrumentation and Detectors (4)
 
High Energy Physics - Phenomenology (3)
 
Physics - Superconductivity (3)
 
Nuclear Theory (3)
 
High Energy Physics - Experiment (3)
 
Physics - Accelerator Physics (2)
 
Computer Science - Databases (2)
 
Mathematics - Classical Analysis and ODEs (1)
 
Mathematics - Probability (1)
 
General Relativity and Quantum Cosmology (1)
 
Physics - Strongly Correlated Electrons (1)
 
Physics - Optics (1)

Publications Authored By A. Narayan

It has long been a challenge to describe the origin of unconventional superconductivity. The two known examples with high Tc, based on iron and copper, have very different electronic structures, while other materials with similar electronic structure may not show superconductivity at all. In this paper, the authors show that by using high accuracy diffusion Monte Carlo calculations, the unconventional superconductors of both high Tc types form a cluster at intermediate spin-charge coupling. Read More

We provide a robust and general algorithm for computing distribution functions associated to induced orthogonal polynomial measures. We leverage several tools for orthogonal polynomials to provide a spectrally-accurate method for a broad class of measures, which is stable for polynomial degrees up to at least degree 1000. Paired with other standard tools such as a numerical root-finding algorithm and inverse transform sampling, this provides a methodology for generating random samples from an induced orthogonal polynomial measure. Read More

The Reduced Basis Method (RBM) is a popular certified model reduction approach for solving parametrized partial differential equations. One critical stage of the \textit{offline} portion of the algorithm is a greedy algorithm, requiring maximization of an error estimate over parameter space. In practice this maximization is usually performed by replacing the parameter domain continuum with a discrete "training" set. Read More

We study impurity scattering in the normal and d-wave superconducting states of line nodal semimetals and show that, due to additional scattering phase space available for impurities on the surface, the quasiparticle interference pattern acquires an extended character instead of a discrete collection of delta function peaks. Moreover, using the T-matrix formalism, we demonstrate that the conventional behavior of a scalar impurity in a d-wave superconductor breaks down on the surface of a line nodal semimetal in the quasi flat band limit. Read More

The recovery of approximately sparse or compressible coefficients in a Polynomial Chaos Expansion is a common goal in modern parametric uncertainty quantification (UQ). However, relatively little effort in UQ has been directed toward theoretical and computational strategies for addressing the sparse corruptions problem, where a small number of measurements are highly corrupted. Such a situation has become pertinent today since modern computational frameworks are sufficiently complex with many interdependent components that may introduce hardware and software failures, some of which can be difficult to detect and result in a highly polluted simulation result. Read More

Formed by the periodic motion of electrons through closed paths in the momentum space, cyclotron orbits have been known for decades and widely used as an effective tool to probe the Fermi surface by detecting the resultant quantum oscillations. Recent studies in topological systems show that a new type of electron orbits with open loops, known as Fermi arcs, will emerge at the surface of Weyl semimetals as a result of broken translational symmetry. Nevertheless, a complete cyclotron orbit can still be developed within open Fermi arcs on both sides of the surface, if electrons can tunnel through the bulk chiral mode and remain phase coherent. Read More

As an intermediate state in the topological phase diagram, Dirac semimetals are of particular interest as a platform for studying topological phase transitions under external modulations. Despite a growing theoretical interest in this topic, it remains a substantial challenge to experimentally tune the system across topological phase transitions. Here, we investigate the Fermi surface evolution of Cd3As2 under high pressure through magnetotransport. Read More

We report on a measurement of the constancy and anisotropy of the speed of light relative to the electrons in photon-electron scattering. We used the Compton scattering asymmetry measured by the new Compton polarimeter in Hall~C at Jefferson Lab to test for deviations from unity of the vacuum refractive index ($n$). For photon energies in the range of 9 - 46 MeV, we obtain a new limit of $1-n < 1. Read More

We have performed a novel comparison between electron-beam polarimeters based on M{\o}ller and Compton scattering. A sequence of electron-beam polarization measurements were performed at low beam currents ($<$ 5 $\mu$A) during the $Q_{\rm weak}$ experiment in Hall C at Jefferson Lab. These low current measurements were bracketed by the regular high current (180 $\mu$A) operation of the Compton polarimeter. Read More

2016Oct

The unpolarized semi-inclusive deep-inelastic scattering (SIDIS) differential cross sections in $^3$He($e,e^{\prime}\pi^{\pm}$)$X$ have been measured for the first time in Jefferson Lab experiment E06-010 performed with a $5.9\,$GeV $e^-$ beam on a $^3$He target. The experiment focuses on the valence quark region, covering a kinematic range $0. Read More

We propose that illumination with light provides a useful platform for creating tunable semimetals. We show that by shining light on semimetals with a line degeneracy, one can convert them to a point node semimetal. These point nodes are adjustable and their position can be controlled by simply rotating the incident light beam. Read More

2016Jun
Affiliations: 1HKS, 2HKS, 3HKS, 4HKS, 5HKS, 6HKS, 7HKS, 8HKS, 9HKS, 10HKS, 11HKS, 12HKS, 13HKS, 14HKS, 15HKS, 16HKS, 17HKS, 18HKS, 19HKS, 20HKS, 21HKS, 22HKS, 23HKS, 24HKS, 25HKS, 26HKS, 27HKS, 28HKS, 29HKS, 30HKS, 31HKS, 32HKS, 33HKS, 34HKS, 35HKS, 36HKS, 37HKS, 38HKS, 39HKS, 40HKS, 41HKS, 42HKS, 43HKS, 44HKS, 45HKS, 46HKS, 47HKS, 48HKS, 49HKS, 50HKS, 51HKS, 52HKS, 53HKS, 54HKS, 55HKS, 56HKS, 57HKS, 58HKS, 59HKS, 60HKS, 61HKS, 62HKS, 63HKS, 64HKS, 65HKS, 66HKS, 67HKS, 68HKS, 69HKS, 70HKS, 71HKS, 72HKS, 73HKS, 74HKS, 75HKS, 76HKS, 77HKS, 78HKS, 79HKS, 80HKS, 81HKS, 82HKS, 83HKS, 84HKS, 85HKS, 86HKS

The missing mass spectroscopy of the $^{7}_{\Lambda}$He hypernucleus was performed, using the $^{7}$Li$(e,e^{\prime}K^{+})^{7}_{\Lambda}$He reaction at the Thomas Jefferson National Accelerator Facility Hall C. The $\Lambda$ binding energy of the ground state (1/2$^{+}$) was determined with a smaller error than that of the previous measurement, being $B_{\Lambda}$ = 5.55 $\pm$ 0. Read More

Efficient retrieval of information is of key importance when using Big Data systems. In large scale-out data architectures, data are distributed and replicated across several machines. Queries/tasks to such data architectures, are sent to a router which determines the machines containing the requested data. Read More

We report on the results of the E06-014 experiment performed at Jefferson Lab in Hall A, where a precision measurement of the twist-3 matrix element $d_2$ of the neutron ($d_{2}^{n}$) was conducted. This quantity represents the average color Lorentz force a struck quark experiences in a deep inelastic electron scattering event off a neutron due to its interaction with the hadronizing remnants. This color force was determined from a linear combination of the third moments of the spin structure functions $g_1$ and $g_2$ on $^{3}$He after nuclear corrections had been applied to these moments. Read More

In this paper we propose an algorithm for recovering sparse orthogonal polynomials using stochastic collocation. Our approach is motivated by the desire to use generalized polynomial chaos expansions (PCE) to quantify uncertainty in models subject to uncertain input parameters. The standard sampling approach for recovering sparse polynomials is to use Monte Carlo (MC) sampling of the density of orthogonality. Read More

In this work, we discuss the problem of approximating a multivariate function via $\ell_1$ minimization method, using a random chosen sub-grid of the corresponding tensor grid of Gaussian points. The independent variables of the function are assumed to be random variables, and thus, the framework provides a non-intrusive way to construct the generalized polynomial chaos expansions, stemming from the motivating application of Uncertainty Quantification (UQ). We provide theoretical analysis on the validity of the approach. Read More

This paper proposes a new deterministic sampling strategy for constructing polynomial chaos approximations for expensive physics simulation models. The proposed approach, effectively subsampled quadratures involves sparsely subsampling an existing tensor grid using QR column pivoting. For polynomial interpolation using hyperbolic or total order sets, we then solve the following square least squares problem. Read More

The non-intrusive generalized Polynomial Chaos (gPC) method is a popular computational approach for solving partial differential equations (PDEs) with random inputs. The main hurdle preventing its efficient direct application for high-dimensional input parameters is that the size of many parametric sampling meshes grows exponentially in the number of inputs (the "curse of dimensionality"). In this paper, we design a weighted version of the reduced basis method (RBM) for use in the non-intrusive gPC framework. Read More

We present a class of Rashba systems in hexagonal semiconducting compounds, where an electrical control over spin-orbital texture is provided by their bulk ferroelectricity. Our first-principles calculations reveal a number of such materials with large Rashba coefficients. We, furthermore, show that strain can drive a topological phase transition in such materials, resulting in a ferroelectric topological insulating state. Read More

Expanding the library of known inorganic materials with functional electronic or magnetic behavior is a longstanding goal in condensed matter physics and materials science. Recently, the transition metal chalchogenides including selenium and sulfur have been of interest because of their correlated-electron properties, as seen in the iron based superconductors and the transition metal dichalcogenides. However, the chalcogenide chemical space is less explored than that of oxides, and there is an open question of whether there may be new materials heretofore undiscovered. Read More

Since the discovery of graphene, layered materials have attracted extensive interests owing to their unique electronic and optical characteristics. Among them, Dirac semimetal, one of the most appealing categories, has been a long-sought objective in layered systems beyond graphene. Recently, layered pentatelluride ZrTe5 was found to host signatures of Dirac semimetal. Read More

In the recent times, test of Lorentz Invariance has been used as a means to probe theories of physics beyond the standard model. We describe a simple way of utilizing the polarimeters, which are a critical beam instrument at precision and intensity frontier nuclear physics labs such as the erstwhile Stanford Linear Accelerator Center (SLAC) and Jefferson Lab (JLab), to constrain the dependence of vacuum dispersion with the energy of the photons and its direction of propagation at unprecedented level of precision. We obtain a limit of minimal Standard Model extension (MSME) parameters: $\sqrt{\kappa_X^2 + \kappa_Y^2} < 4. Read More

We report on the highest precision yet achieved in the measurement of the polarization of a low energy, $\mathcal{O}$(1 GeV), electron beam, accomplished using a new polarimeter based on electron-photon scattering, in Hall~C at Jefferson Lab. A number of technical innovations were necessary, including a novel method for precise control of the laser polarization in a cavity and a novel diamond micro-strip detector which was able to capture most of the spectrum of scattered electrons. The data analysis technique exploited track finding, the high granularity of the detector and its large acceptance. Read More

We give a remarkable additional orthogonality property of the classical Legendre polynomials on the real interval $[-1,1]$: polynomials up to degree $n$ from this family are mutually orthogonal under the arcsine measure weighted by the degree-$n$ normalized Christoffel function. Read More

We study the photoresponse of two-dimensional semi-Dirac semimetals and three-dimensional Dirac semimetals to off-resonant circularly polarized light. For two-dimensional semi-Dirac semimetals we find that incident light does not open a gap in the spectrum, in contrast to the case of purely linear dispersion. For the three-dimensional case we find that applying a circularly polarized light, one can tune from a trivial insulator to three-dimensional Dirac semimetal with an inverted gap. Read More

Two-dimensional (2D) layered transition metal dichalcogenides (TMDs) have been recently proposed as appealing candidate materials for spintronic applications owing to their distinctive atomic crystal structure and exotic physical properties arising from the large bonding anisotropy. Here we introduce the first MoS2-based spin-valves that employ monolayer MoS2 as the nonmagnetic spacer. In contrast with what expected from the semiconducting band-structure of MoS2, the vertically sandwiched-MoS2 layers exhibit metallic behavior. Read More

2015Feb

We report the measurement of beam-target double-spin asymmetries ($A_\text{LT}$) in the inclusive production of identified hadrons, $\vec{e}~$+$~^3\text{He}^{\uparrow}\rightarrow h+X$, using a longitudinally polarized 5.9 GeV electron beam and a transversely polarized $^3\rm{He}$ target. Hadrons ($\pi^{\pm}$, $K^{\pm}$ and proton) were detected at 16$^{\circ}$ with an average momentum $<$$P_h$$>$=2. Read More

Collocation has become a standard tool for approximation of parameterized systems in the uncertainty quantification (UQ) community. Techniques for least-squares regularization, compressive sampling recovery, and interpolatory reconstruction are becoming standard tools used in a variety of applications. Selection of a collocation mesh is frequently a challenge, but methods that construct geometrically "unstructured" collocation meshes have shown great potential due to attractive theoretical properties and direct, simple generation and implementation. Read More

Electrostatic doping in materials can lead to various exciting electronic properties, such as metal-insulator transition and superconductivity, by altering the Fermi level position or introducing exotic phases. Cd3As2, a three-dimensional (3D) analog of graphene with extraordinary carrier mobility, was predicted to be a 3D Dirac semimetal, a feature confirmed by recent experiments. However, most research so far has been focused on metallic bulk materials that are known to possess ultra-high mobility and giant magnetoresistance but limited carrier transport tunability. Read More

We propose, theoretically investigate, and numerically validate an algorithm for the Monte Carlo solution of least-squares polynomial approximation problems in a collocation frame- work. Our method is motivated by generalized Polynomial Chaos approximation in uncertainty quantification where a polynomial approximation is formed from a combination of orthogonal polynomials. A standard Monte Carlo approach would draw samples according to the density of orthogonality. Read More

The parity-violating asymmetries between a longitudinally-polarized electron beam and an unpolarized deuterium target have been measured recently. The measurement covered two kinematic points in the deep inelastic scattering region and five in the nucleon resonance region. We provide here details of the experimental setup, data analysis, and results on all asymmetry measurements including parity-violating electron asymmetries and those of inclusive pion production and beam-normal asymmetries. Read More

We study Andreev reflection in normal metal-superconductor junctions by using an extended Blonder-Tinkham-Klapwijk model combined with transport calculations based on density functional theory. Starting from a parameter-free description of the underlying electronic structure, we perform a detailed investigation of normal metal-superconductor junctions, as the separation between the superconductor and the normal metal is varied. The results are interpreted by means of transverse momentum resolved calculations, which allow us to examine the contributions arising from different regions of the Brillouin zone. Read More

We propose and test the first Reduced Radial Basis Function Method (R$^2$BFM) for solving parametric partial differential equations on irregular domains. The two major ingredients are a stable Radial Basis Function (RBF) solver that has an optimized set of centers chosen through a reduced-basis-type greedy algorithm, and a collocation-based model reduction approach that systematically generates a reduced-order approximation whose dimension is orders of magnitude smaller than the total number of RBF centers. The resulting algorithm is efficient and accurate as demonstrated through two- and three-dimensional test problems. Read More

2014Sep
Authors: Qweak Collaboration, T. Allison, M. Anderson, D. Androic, D. S. Armstrong, A. Asaturyan, T. D. Averett, R. Averill, J. Balewski, J. Beaufait, R. S. Beminiwattha, J. Benesch, F. Benmokhtar, J. Bessuille, J. Birchall, E. Bonnell, J. Bowman, P. Brindza, D. B. Brown, R. D. Carlini, G. D. Cates, B. Cavness, G. Clark, J. C. Cornejo, S. Covrig Dusa, M. M. Dalton, C. A. Davis, D. C. Dean, W. Deconinck, J. Diefenbach, K. Dow, J. F. Dowd, J. A. Dunne, D. Dutta, W. S. Duvall, J. R. Echols, M. Elaasar, W. R. Falk, K. D. Finelli, J. M. Finn, D. Gaskell, M. T. W. Gericke, J. Grames, V. M. Gray, K. Grimm, F. Guo, J. Hansknecht, D. J. Harrison, E. Henderson, J. R. Hoskins, E. Ihloff, K. Johnston, D. Jones, M. Jones, R. Jones, M. Kargiantoulakis, J. Kelsey, N. Khan, P. M. King, E. Korkmaz, S. Kowalski, A. Kubera, J. Leacock, J. P. Leckey, A. R. Lee, J. H. Lee, L. Lee, Y. Liang, S. MacEwan, D. Mack, J. A. Magee, R. Mahurin, J. Mammei, J. W. Martin, A. McCreary, M. H. McDonald, M. J. McHugh, P. Medeiros, D. Meekins, J. Mei, R. Michaels, A. Micherdzinska, A. Mkrtchyan, H. Mkrtchyan, N. Morgan, J. Musson, K. E. Mesick, A. Narayan, L. Z. Ndukum, V. Nelyubin, Nuruzzaman, W. T. H. van Oers, A. K. Opper, S. A. Page, J. Pan, K. D. Paschke, S. K. Phillips, M. L. Pitt, M. Poelker, J. F. Rajotte, W. D. Ramsay, W. R. Roberts, J. Roche, P. W. Rose, B. Sawatzky, T. Seva, M. H. Shabestari, R. Silwal, N. Simicevic, G. R. Smith, S. Sobczynski, P. Solvignon, D. T. Spayde, B. Stokes, D. W. Storey, A. Subedi, R. Subedi, R. Suleiman, V. Tadevosyan, W. A. Tobias, V. Tvaskis, E. Urban, B. Waidyawansa, P. Wang, S. P. Wells, S. A. Wood, S. Yang, S. Zhamkochyan, R. B. Zielinski

The Jefferson Lab Q_weak experiment determined the weak charge of the proton by measuring the parity-violating elastic scattering asymmetry of longitudinally polarized electrons from an unpolarized liquid hydrogen target at small momentum transfer. A custom apparatus was designed for this experiment to meet the technical challenges presented by the smallest and most precise ${\vec{e}}$p asymmetry ever measured. Technical milestones were achieved at Jefferson Lab in target power, beam current, beam helicity reversal rate, polarimetry, detected rates, and control of helicity-correlated beam properties. Read More

We study with first-principles methods the interplay between bulk and surface Dirac fermions in three dimensional Dirac semimetals. By combining density functional theory with the coherent potential approximation, we reveal a topological phase transition in Na$_3$Bi$_{1-x}$Sb$_{x}$ and Cd$_3$[As$_{1-x}$P$_x$]$_2$ alloys, where the material goes from a Dirac semimetal to a trivial insulator upon changing Sb or P concentrations. Tuning the composition allows us to engineer the position of the bulk Dirac points in reciprocal space. Read More

The appearance of topologically protected states at the surface of an ordinary insulator is a rare occurrence and to date only a handful of materials are known for having this property. An intriguing question concerns the possibility of forming topologically protected interfaces between different materials. Here we propose that a topological phase can be transferred to graphene by proximity with the three-dimensional topological insulator Bi$_2$Se$_3$. Read More

2014Jun
Authors: L. Tang1, C. Chen2, T. Gogami3, D. Kawama4, Y. Han5, L. Yuan6, A. Matsumura7, Y. Okayasu8, T. Seva9, V. M. Rodriguez10, P. Baturin11, A. Acha12, P. Achenbach13, A. Ahmidouch14, I. Albayrak15, D. Androic16, A. Asaturyan17, R. Asaturyan18, O. Ates19, R. Badui20, O. K. Baker21, F. Benmokhtar22, W. Boeglin23, J. Bono24, P. Bosted25, E. Brash26, P. Carter27, R. Carlini28, A. Chiba29, M. E. Christy30, L. Cole31, M. M. Dalton32, S. Danagoulian33, A. Daniel34, R. De Leo35, V. Dharmawardane36, D. Doi37, K. Egiyan38, M. Elaasar39, R. Ent40, H. Fenker41, Y. Fujii42, M. Furic43, M. Gabrielyan44, L. Gan45, F. Garibaldi46, D. Gaskell47, A. Gasparian48, E. F. Gibson49, P. Gueye50, O. Hashimoto51, D. Honda52, T. Horn53, B. Hu54, Ed V. Hungerford55, C. Jayalath56, M. Jones57, K. Johnston58, N. Kalantarians59, H. Kanda60, M. Kaneta61, F. Kato62, S. Kato63, M. Kawai64, C. Keppel65, H. Khanal66, M. Kohl67, L. Kramer68, K. J. Lan69, Y. Li70, A. Liyanage71, W. Luo72, D. Mack73, K. Maeda74, S. Malace75, A. Margaryan76, G. Marikyan77, P. Markowitz78, T. Maruta79, N. Maruyama80, V. Maxwell81, D. J. Millener82, T. Miyoshi83, A. Mkrtchyan84, H. Mkrtchyan85, T. Motoba86, S. Nagao87, S. N. Nakamura88, A. Narayan89, C. Neville90, G. Niculescu91, M. I. Niculescu92, A. Nunez93, Nuruzzaman94, H. Nomura95, K. Nonaka96, A. Ohtani97, M. Oyamada98, N. Perez99, T. Petkovic100, J. Pochodzalla101, X. Qiu102, S. Randeniya103, B. Raue104, J. Reinhold105, R. Rivera106, J. Roche107, C. Samanta108, Y. Sato109, B. Sawatzky110, E. K. Segbefia111, D. Schott112, A. Shichijo113, N. Simicevic114, G. Smith115, Y. Song116, M. Sumihama117, V. Tadevosyan118, T. Takahashi119, N. Taniya120, K. Tsukada121, V. Tvaskis122, M. Veilleux123, W. Vulcan124, S. Wells125, F. R. Wesselmann126, S. A. Wood127, T. Yamamoto128, C. Yan129, Z. Ye130, K. Yokota131, S. Zhamkochyan132, L. Zhu133
Affiliations: 1HKS - JLab E05-115 and E01-001 - Collaborations, 2HKS - JLab E05-115 and E01-001 - Collaborations, 3HKS - JLab E05-115 and E01-001 - Collaborations, 4HKS - JLab E05-115 and E01-001 - Collaborations, 5HKS - JLab E05-115 and E01-001 - Collaborations, 6HKS - JLab E05-115 and E01-001 - Collaborations, 7HKS - JLab E05-115 and E01-001 - Collaborations, 8HKS - JLab E05-115 and E01-001 - Collaborations, 9HKS - JLab E05-115 and E01-001 - Collaborations, 10HKS - JLab E05-115 and E01-001 - Collaborations, 11HKS - JLab E05-115 and E01-001 - Collaborations, 12HKS - JLab E05-115 and E01-001 - Collaborations, 13HKS - JLab E05-115 and E01-001 - Collaborations, 14HKS - JLab E05-115 and E01-001 - Collaborations, 15HKS - JLab E05-115 and E01-001 - Collaborations, 16HKS - JLab E05-115 and E01-001 - Collaborations, 17HKS - JLab E05-115 and E01-001 - Collaborations, 18HKS - JLab E05-115 and E01-001 - Collaborations, 19HKS - JLab E05-115 and E01-001 - Collaborations, 20HKS - JLab E05-115 and E01-001 - 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Collaborations, 101HKS - JLab E05-115 and E01-001 - Collaborations, 102HKS - JLab E05-115 and E01-001 - Collaborations, 103HKS - JLab E05-115 and E01-001 - Collaborations, 104HKS - JLab E05-115 and E01-001 - Collaborations, 105HKS - JLab E05-115 and E01-001 - Collaborations, 106HKS - JLab E05-115 and E01-001 - Collaborations, 107HKS - JLab E05-115 and E01-001 - Collaborations, 108HKS - JLab E05-115 and E01-001 - Collaborations, 109HKS - JLab E05-115 and E01-001 - Collaborations, 110HKS - JLab E05-115 and E01-001 - Collaborations, 111HKS - JLab E05-115 and E01-001 - Collaborations, 112HKS - JLab E05-115 and E01-001 - Collaborations, 113HKS - JLab E05-115 and E01-001 - Collaborations, 114HKS - JLab E05-115 and E01-001 - Collaborations, 115HKS - JLab E05-115 and E01-001 - Collaborations, 116HKS - JLab E05-115 and E01-001 - Collaborations, 117HKS - JLab E05-115 and E01-001 - Collaborations, 118HKS - JLab E05-115 and E01-001 - Collaborations, 119HKS - JLab E05-115 and E01-001 - Collaborations, 120HKS - JLab E05-115 and E01-001 - Collaborations, 121HKS - JLab E05-115 and E01-001 - Collaborations, 122HKS - JLab E05-115 and E01-001 - Collaborations, 123HKS - JLab E05-115 and E01-001 - Collaborations, 124HKS - JLab E05-115 and E01-001 - Collaborations, 125HKS - JLab E05-115 and E01-001 - Collaborations, 126HKS - JLab E05-115 and E01-001 - Collaborations, 127HKS - JLab E05-115 and E01-001 - Collaborations, 128HKS - JLab E05-115 and E01-001 - Collaborations, 129HKS - JLab E05-115 and E01-001 - Collaborations, 130HKS - JLab E05-115 and E01-001 - Collaborations, 131HKS - JLab E05-115 and E01-001 - Collaborations, 132HKS - JLab E05-115 and E01-001 - Collaborations, 133HKS - JLab E05-115 and E01-001 - Collaborations

Since the pioneering experiment, E89-009 studying hypernuclear spectroscopy using the $(e,e^{\prime}K^+)$ reaction was completed, two additional experiments, E01-011 and E05-115, were performed at Jefferson Lab. These later experiments used a modified experimental design, the "tilt method", to dramatically suppress the large electromagnetic background, and allowed for a substantial increase in luminosity. Additionally, a new kaon spectrometer, HKS (E01-011), a new electron spectrometer, HES, and a new splitting magnet were added to produce precision, high-resolution hypernuclear spectroscopy. Read More

2014Jun
Affiliations: 1The Jefferson Lab Hall A Collaboration, 2The Jefferson Lab Hall A Collaboration, 3The Jefferson Lab Hall A Collaboration, 4The Jefferson Lab Hall A Collaboration, 5The Jefferson Lab Hall A Collaboration, 6The Jefferson Lab Hall A Collaboration, 7The Jefferson Lab Hall A Collaboration, 8The Jefferson Lab Hall A Collaboration, 9The Jefferson Lab Hall A Collaboration, 10The Jefferson Lab Hall A Collaboration, 11The Jefferson Lab Hall A Collaboration, 12The Jefferson Lab Hall A Collaboration, 13The Jefferson Lab Hall A Collaboration, 14The Jefferson Lab Hall A Collaboration, 15The Jefferson Lab Hall A Collaboration, 16The Jefferson Lab Hall A Collaboration, 17The Jefferson Lab Hall A Collaboration, 18The Jefferson Lab Hall A Collaboration, 19The Jefferson Lab Hall A Collaboration, 20The Jefferson Lab Hall A Collaboration, 21The Jefferson Lab Hall A Collaboration, 22The Jefferson Lab Hall A Collaboration, 23The Jefferson Lab Hall A Collaboration, 24The Jefferson Lab Hall A Collaboration, 25The Jefferson Lab Hall A Collaboration, 26The Jefferson Lab Hall A Collaboration, 27The Jefferson Lab Hall A Collaboration, 28The Jefferson Lab Hall A Collaboration, 29The Jefferson Lab Hall A Collaboration, 30The Jefferson Lab Hall A Collaboration, 31The Jefferson Lab Hall A Collaboration, 32The Jefferson Lab Hall A Collaboration, 33The Jefferson Lab Hall A Collaboration, 34The Jefferson Lab Hall A Collaboration, 35The Jefferson Lab Hall A Collaboration, 36The Jefferson Lab Hall A Collaboration, 37The Jefferson Lab Hall A Collaboration, 38The Jefferson Lab Hall A Collaboration, 39The Jefferson Lab Hall A Collaboration, 40The Jefferson Lab Hall A Collaboration, 41The Jefferson Lab Hall A Collaboration, 42The Jefferson Lab Hall A Collaboration, 43The Jefferson Lab Hall A Collaboration, 44The Jefferson Lab Hall A Collaboration, 45The Jefferson Lab Hall A Collaboration, 46The Jefferson Lab Hall A Collaboration, 47The Jefferson Lab Hall A Collaboration, 48The Jefferson Lab Hall A Collaboration, 49The Jefferson Lab Hall A Collaboration, 50The Jefferson Lab Hall A Collaboration, 51The Jefferson Lab Hall A Collaboration, 52The Jefferson Lab Hall A Collaboration, 53The Jefferson Lab Hall A Collaboration, 54The Jefferson Lab Hall A Collaboration, 55The Jefferson Lab Hall A Collaboration, 56The Jefferson Lab Hall A Collaboration, 57The Jefferson Lab Hall A Collaboration, 58The Jefferson Lab Hall A Collaboration, 59The Jefferson Lab Hall A Collaboration, 60The Jefferson Lab Hall A Collaboration, 61The Jefferson Lab Hall A Collaboration, 62The Jefferson Lab Hall A Collaboration, 63The Jefferson Lab Hall A Collaboration, 64The Jefferson Lab Hall A Collaboration, 65The Jefferson Lab Hall A Collaboration, 66The Jefferson Lab Hall A Collaboration, 67The Jefferson Lab Hall A Collaboration, 68The Jefferson Lab Hall A Collaboration, 69The Jefferson Lab Hall A Collaboration, 70The Jefferson Lab Hall A Collaboration, 71The Jefferson Lab Hall A Collaboration, 72The Jefferson Lab Hall A Collaboration, 73The Jefferson Lab Hall A Collaboration, 74The Jefferson Lab Hall A Collaboration, 75The Jefferson Lab Hall A Collaboration, 76The Jefferson Lab Hall A Collaboration, 77The Jefferson Lab Hall A Collaboration, 78The Jefferson Lab Hall A Collaboration, 79The Jefferson Lab Hall A Collaboration, 80The Jefferson Lab Hall A Collaboration, 81The Jefferson Lab Hall A Collaboration, 82The Jefferson Lab Hall A Collaboration, 83The Jefferson Lab Hall A Collaboration, 84The Jefferson Lab Hall A Collaboration, 85The Jefferson Lab Hall A Collaboration, 86The Jefferson Lab Hall A Collaboration, 87The Jefferson Lab Hall A Collaboration, 88The Jefferson Lab Hall A Collaboration, 89The Jefferson Lab Hall A Collaboration, 90The Jefferson Lab Hall A Collaboration, 91The Jefferson Lab Hall A Collaboration, 92The Jefferson Lab Hall A Collaboration

We have performed precision measurements of the double-spin virtual-photon asymmetry $A_1$ on the neutron in the deep inelastic scattering regime, using an open-geometry, large-acceptance spectrometer. Our data cover a wide kinematic range $0.277 \leq x \leq 0. Read More

We demonstrate single atom anisotropic magnetoresistance on the surface of a topological insulator, arising from the interplay between the helical spin-momentum-locked surface electronic structure and the hybridization of the magnetic adatom states. Our first-principles quantum transport calculations based on density functional theory for Mn on Bi$_2$Se$_3$ elucidate the underlying mechanism. We complement our findings with a two dimensional model valid for both single adatoms and magnetic clusters, which leads to a proposed device setup for experimental realization. Read More

2014Apr
Authors: Y. X. Zhao1, Y. Wang2, K. Allada3, K. Aniol4, J. R. M. Annand5, T. Averett6, F. Benmokhtar7, W. Bertozzi8, P. C. Bradshaw9, P. Bosted10, A. Camsonne11, M. Canan12, G. D. Cates13, C. Chen14, J. -P. Chen15, W. Chen16, K. Chirapatpimol17, E. Chudakov18, E. Cisbani19, J. C. Cornejo20, F. Cusanno21, M. M. Dalton22, W. Deconinck23, C. W. de Jager24, R. De Leo25, X. Deng26, A. Deur27, H. Ding28, P. A. M. Dolph29, C. Dutta30, D. Dutta31, L. El Fassi32, S. Frullani33, H. Gao34, F. Garibaldi35, D. Gaskell36, S. Gilad37, R. Gilman38, O. Glamazdin39, S. Golge40, L. Guo41, D. Hamilton42, O. Hansen43, D. W. Higinbotham44, T. Holmstrom45, J. Huang46, M. Huang47, H. F Ibrahim48, M. Iodice49, X. Jiang50, G. Jin51, M. K. Jones52, J. Katich53, A. Kelleher54, W. Kim55, A. Kolarkar56, W. Korsch57, J. J. LeRose58, X. Li59, Y. Li60, R. Lindgren61, N. Liyanage62, E. Long63, H. -J. Lu64, D. J. Margaziotis65, P. Markowitz66, S. Marrone67, D. McNulty68, Z. -E. Meziani69, R. Michaels70, B. Moffit71, C. Muñoz Camacho72, S. Nanda73, A. Narayan74, V. Nelyubin75, B. Norum76, Y. Oh77, M. Osipenko78, D. Parno79, J. -C. Peng80, S. K. Phillips81, M. Posik82, A. J. R. Puckett83, X. Qian84, Y. Qiang85, A. Rakhman86, R. Ransome87, S. Riordan88, A. Saha89, B. Sawatzky90, E. Schulte91, A. Shahinyan92, M. H. Shabestari93, S. Širca94, S. Stepanyan95, R. Subedi96, V. Sulkosky97, L. -G. Tang98, A. Tobias99, G. M. Urciuoli100, I. Vilardi101, K. Wang102, B. Wojtsekhowski103, X. Yan104, H. Yao105, Y. Ye106, Z. Ye107, L. Yuan108, X. Zhan109, Y. Zhang110, Y. -W. Zhang111, B. Zhao112, X. Zheng113, L. Zhu114, X. Zhu115, X. Zong116
Affiliations: 1Jefferson Lab Hall A Collaboration, 2Jefferson Lab Hall A Collaboration, 3Jefferson Lab Hall A Collaboration, 4Jefferson Lab Hall A Collaboration, 5Jefferson Lab Hall A Collaboration, 6Jefferson Lab Hall A Collaboration, 7Jefferson Lab Hall A Collaboration, 8Jefferson Lab Hall A Collaboration, 9Jefferson Lab Hall A Collaboration, 10Jefferson Lab Hall A Collaboration, 11Jefferson Lab Hall A Collaboration, 12Jefferson Lab Hall A Collaboration, 13Jefferson Lab Hall A Collaboration, 14Jefferson Lab Hall A Collaboration, 15Jefferson Lab Hall A Collaboration, 16Jefferson Lab Hall A Collaboration, 17Jefferson Lab Hall A Collaboration, 18Jefferson Lab Hall A Collaboration, 19Jefferson Lab Hall A Collaboration, 20Jefferson Lab Hall A Collaboration, 21Jefferson Lab Hall A Collaboration, 22Jefferson Lab Hall A Collaboration, 23Jefferson Lab Hall A Collaboration, 24Jefferson Lab Hall A Collaboration, 25Jefferson Lab Hall A Collaboration, 26Jefferson Lab Hall A Collaboration, 27Jefferson Lab Hall A Collaboration, 28Jefferson Lab Hall A Collaboration, 29Jefferson Lab Hall A Collaboration, 30Jefferson Lab Hall A Collaboration, 31Jefferson Lab Hall A Collaboration, 32Jefferson Lab Hall A Collaboration, 33Jefferson Lab Hall A Collaboration, 34Jefferson Lab Hall A Collaboration, 35Jefferson Lab Hall A Collaboration, 36Jefferson Lab Hall A Collaboration, 37Jefferson Lab Hall A Collaboration, 38Jefferson Lab Hall A Collaboration, 39Jefferson Lab Hall A Collaboration, 40Jefferson Lab Hall A Collaboration, 41Jefferson Lab Hall A Collaboration, 42Jefferson Lab Hall A Collaboration, 43Jefferson Lab Hall A Collaboration, 44Jefferson Lab Hall A Collaboration, 45Jefferson Lab Hall A Collaboration, 46Jefferson Lab Hall A Collaboration, 47Jefferson Lab Hall A Collaboration, 48Jefferson Lab Hall A Collaboration, 49Jefferson Lab Hall A Collaboration, 50Jefferson Lab Hall A Collaboration, 51Jefferson Lab Hall A Collaboration, 52Jefferson Lab Hall A Collaboration, 53Jefferson Lab Hall A Collaboration, 54Jefferson Lab Hall A Collaboration, 55Jefferson Lab Hall A Collaboration, 56Jefferson Lab Hall A Collaboration, 57Jefferson Lab Hall A Collaboration, 58Jefferson Lab Hall A Collaboration, 59Jefferson Lab Hall A Collaboration, 60Jefferson Lab Hall A Collaboration, 61Jefferson Lab Hall A Collaboration, 62Jefferson Lab Hall A Collaboration, 63Jefferson Lab Hall A Collaboration, 64Jefferson Lab Hall A Collaboration, 65Jefferson Lab Hall A Collaboration, 66Jefferson Lab Hall A Collaboration, 67Jefferson Lab Hall A Collaboration, 68Jefferson Lab Hall A Collaboration, 69Jefferson Lab Hall A Collaboration, 70Jefferson Lab Hall A Collaboration, 71Jefferson Lab Hall A Collaboration, 72Jefferson Lab Hall A Collaboration, 73Jefferson Lab Hall A Collaboration, 74Jefferson Lab Hall A Collaboration, 75Jefferson Lab Hall A Collaboration, 76Jefferson Lab Hall A Collaboration, 77Jefferson Lab Hall A Collaboration, 78Jefferson Lab Hall A Collaboration, 79Jefferson Lab Hall A Collaboration, 80Jefferson Lab Hall A Collaboration, 81Jefferson Lab Hall A Collaboration, 82Jefferson Lab Hall A Collaboration, 83Jefferson Lab Hall A Collaboration, 84Jefferson Lab Hall A Collaboration, 85Jefferson Lab Hall A Collaboration, 86Jefferson Lab Hall A Collaboration, 87Jefferson Lab Hall A Collaboration, 88Jefferson Lab Hall A Collaboration, 89Jefferson Lab Hall A Collaboration, 90Jefferson Lab Hall A Collaboration, 91Jefferson Lab Hall A Collaboration, 92Jefferson Lab Hall A Collaboration, 93Jefferson Lab Hall A Collaboration, 94Jefferson Lab Hall A Collaboration, 95Jefferson Lab Hall A Collaboration, 96Jefferson Lab Hall A Collaboration, 97Jefferson Lab Hall A Collaboration, 98Jefferson Lab Hall A Collaboration, 99Jefferson Lab Hall A Collaboration, 100Jefferson Lab Hall A Collaboration, 101Jefferson Lab Hall A Collaboration, 102Jefferson Lab Hall A Collaboration, 103Jefferson Lab Hall A Collaboration, 104Jefferson Lab Hall A Collaboration, 105Jefferson Lab Hall A Collaboration, 106Jefferson Lab Hall A Collaboration, 107Jefferson Lab Hall A Collaboration, 108Jefferson Lab Hall A Collaboration, 109Jefferson Lab Hall A Collaboration, 110Jefferson Lab Hall A Collaboration, 111Jefferson Lab Hall A Collaboration, 112Jefferson Lab Hall A Collaboration, 113Jefferson Lab Hall A Collaboration, 114Jefferson Lab Hall A Collaboration, 115Jefferson Lab Hall A Collaboration, 116Jefferson Lab Hall A Collaboration

We report the first measurement of target single spin asymmetries of charged kaons produced in semi-inclusive deep inelastic scattering of electrons off a transversely polarized $^3{\rm{He}}$ target. Both the Collins and Sivers moments, which are related to the nucleon transversity and Sivers distributions, respectively, are extracted over the kinematic range of 0.1$<$$x_{bj}$$<$0. Read More

We propose an adaptive sparse grid stochastic collocation approach based upon Leja interpolation sequences for approximation of parameterized functions with high-dimensional parameters. Leja sequences are arbitrarily granular (any number of nodes may be added to a current sequence, producing a new sequence) and thus are a good choice for the univariate composite rule used to construct adaptive sparse grids in high dimensions. When undertaking stochastic collocation one is often interested in constructing weighted approximation where the weights are determined by the probability densities of the random variables. Read More

We demonstrate giant magnetoresistance in Fe/MoS$_2$/Fe junctions by means of \textit{ab-initio} transport calculations. We show that junctions incorporating either a mono- or a bi-layer of MoS$_2$ are metallic and that Fe acts as an efficient spin injector into MoS$_2$ with an efficiency of about 45\%. This is the result of the strong coupling between the Fe and S atoms at the interface. Read More

We investigate the effect of potential barriers in the form of step edges on the scattering properties of Bi$_2$Se$_3$(111) topological surface states by means of large-scale ab-initio transport simulations. Our results demonstrate the suppression of perfect backscattering, while all other scattering processes, which do not entail a complete spin and momentum reversal, are allowed. Furthermore, we find that the spin of the surface state develops an out of plane component as it traverses the barrier. Read More

Differential privacy is becoming a gold standard for privacy research; it offers a guaranteed bound on loss of privacy due to release of query results, even under worst-case assumptions. The theory of differential privacy is an active research area, and there are now differentially private algorithms for a wide range of interesting problems. However, the question of when differential privacy works in practice has received relatively little attention. Read More

In this work, we discuss the problem of approximating a multivariate function by discrete least squares projection onto a polynomial space using a specially designed deterministic point set. The independent variables of the function are assumed to be random variables, stemming from the motivating application of Uncertainty Quantification (UQ). Our deterministic points are inspired by a theorem due to Andr\'e Weil. Read More

2013Dec

An experiment to measure single-spin asymmetries in semi-inclusive production of charged pions in deep-inelastic scattering on a transversely polarized $^3$He target was performed at Jefferson Lab in the kinematic region of $0.16Read More

We propose a four-terminal device designed to manipulate by all electrical means the spin of a magnetic adatom positioned at the edge of a quantum spin Hall insulator. We show that an electrical gate, able to tune the interface resistance between a quantum spin Hall insulator and the source and drain electrodes, can switch the device between two regimes: one where the system exhibits spin pumping and the other where the adatom remains in its ground state. This demonstrates an all-electrical route to control single spins by exploiting helical edge states of topological materials. Read More

We analyze electron transport in multiprobe quantum spin Hall (QSH) bars using the B\"{u}ttiker formalism and draw parallels with their quantum Hall (QH) counterparts. We find that in a QSH bar the measured resistance changes upon introducing side voltage probes, in contrast to the QH case. We also study four- and six-terminal geometries and derive the expressions for the resistances. Read More