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Full-Text Articles in Physical Sciences and Mathematics

First All-Sky Search For Continuous Gravitational Waves From Unknown Sources In Binary Systems, J. Aasi, Marco Cavaglia, For Full List Of Authors, See Publisher's Website. Dec 2014

First All-Sky Search For Continuous Gravitational Waves From Unknown Sources In Binary Systems, J. Aasi, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

Gravitational waves from a variety of sources are predicted to superpose to create a stochastic background. This background is expected to contain unique information from throughout the history of the Universe that is unavailable through standard electromagnetic observations, making its study of fundamental importance to understanding the evolution of the Universe. We carry out a search for the stochastic background with the latest data from the LIGO and Virgo detectors. Consistent with predictions from most stochastic gravitational-wave background models, the data display no evidence of a stochastic gravitational-wave signal. Assuming a gravitational-wave spectrum of ΩGW(f) = Ωα(f ...


Improved Upper Limits On The Stochastic Gravitational-Wave Background From 2009-2010 Ligo And Virgo Data, J. Aasi, Marco Cavaglia, For Full List Of Authors, See Publisher's Website. Dec 2014

Improved Upper Limits On The Stochastic Gravitational-Wave Background From 2009-2010 Ligo And Virgo Data, J. Aasi, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

Gravitational waves from a variety of sources are predicted to superpose to create a stochastic background. This background is expected to contain unique information from throughout the history of the Universe that is unavailable through standard electromagnetic observations, making its study of fundamental importance to understanding the evolution of the Universe. We carry out a search for the stochastic background with the latest data from the LIGO and Virgo detectors. Consistent with predictions from most stochastic gravitational-wave background models, the data display no evidence of a stochastic gravitational-wave signal. Assuming a gravitational-wave spectrum of ΩGW(f)=Ωα±(f/fref)α ...


X-Ray Emission Produced In Charge-Exchange Collisions Between Highly Charged Ions And Argon: Role Of The Multiple Electron Capture, Sebastian Otranto, N. D. Cariatore, Ronald E. Olson Dec 2014

X-Ray Emission Produced In Charge-Exchange Collisions Between Highly Charged Ions And Argon: Role Of The Multiple Electron Capture, Sebastian Otranto, N. D. Cariatore, Ronald E. Olson

Physics Faculty Research & Creative Works

In this work we use the classical trajectory Monte Carlo method within an eight-electron scheme to theoretically study photonic spectra that follow charge-exchange processes between highly charged ions of charge states 10+, 17+, 18+, and 36+ with neutral argon. The energy range considered is 18 eV/amu to 4 keV/amu, covering typical electron beam ion traps and solar wind energies. The role played by multiple electron capture processes for the different collision systems under consideration is explicitly analyzed and its contribution separated as arising from radiative decay and autoionizing multiple capture. For the present collision systems we find that ...


Theoretical And Experimental (E, 2e) Study Of Electron-Impact Ionization Of Laser-Aligned Mg Atoms, Sadek Amami, Andrew J. Murray, Al Stauffer, Kate Nixon, Gregory Armstrong, James Colgan, Don H. Madison Dec 2014

Theoretical And Experimental (E, 2e) Study Of Electron-Impact Ionization Of Laser-Aligned Mg Atoms, Sadek Amami, Andrew J. Murray, Al Stauffer, Kate Nixon, Gregory Armstrong, James Colgan, Don H. Madison

Physics Faculty Research & Creative Works

We have performed calculations of the fully differential cross sections for electron-impact ionization of magnesium atoms. Three theoretical approximations, the time-dependent close coupling, the three-body distorted wave, and the distorted wave Born approximation, are compared with experiment in this article. Results will be shown for ionization of the 3s ground state of Mg for both asymmetric and symmetric coplanar geometries. Results will also be shown for ionization of the 3p state which has been excited by a linearly polarized laser which produces a charge cloud aligned perpendicular to the laser beam direction and parallel to the linear polarization. Theoretical and ...


Understanding Higher-Order Nonlocal Halo Bias At Large Scales By Combining The Power Spectrum With The Bispectrum, Shun Saito, Tobias Baldauf, For Full List Of Authors, See Publisher's Website. Dec 2014

Understanding Higher-Order Nonlocal Halo Bias At Large Scales By Combining The Power Spectrum With The Bispectrum, Shun Saito, Tobias Baldauf, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

Understanding the relation between underlying matter distribution and biased tracers such as galaxies or dark matter halos is essential to extract cosmological information from ongoing or future galaxy redshift surveys. At sufficiently large scales such as the baryon acoustic oscillation (BAO) scale, a standard approach for the bias problem on the basis of the perturbation theory (PT) is to assume the "local bias" model in which the density field of biased tracers is deterministically expanded in terms of matter density field at the same position. The higher-order bias parameters are then determined by combining the power spectrum with higher-order statistics ...


Route To Optimal Generation Of Soft X-Ray High Harmonics With Synthesized Two-Color Laser Pulses, Cheng Jin, Guoli Wang, Anh-Thu Le, C. D. Lin Nov 2014

Route To Optimal Generation Of Soft X-Ray High Harmonics With Synthesized Two-Color Laser Pulses, Cheng Jin, Guoli Wang, Anh-Thu Le, C. D. Lin

Physics Faculty Research & Creative Works

High harmonics extending to X-rays have been generated from gases by intense lasers. To establish these coherent broadband radiations as an all-purpose tabletop light source for general applications in science and technology, new methods are needed to overcome the present low conversion efficiencies. Here we show that the conversion efficiency may be drastically increased with an optimized two-color pulse. By employing an optimally synthesized 2-µm mid-infrared laser and a small amount of its third harmonic, we show that harmonic yields from sub- to few-keV energy can be increased typically by ten-fold over the optimized single-color one. By combining with favorable ...


Fully Differential Study Of Interference Effects In The Ionization Of H₂ By Proton Impact, Sachin D. Sharma, T. P. Arthanayaka, Ahmad Hasan, B. R. Lamichhane, J. Remolina, Adolph P. Smith, Michael Schulz Nov 2014

Fully Differential Study Of Interference Effects In The Ionization Of H₂ By Proton Impact, Sachin D. Sharma, T. P. Arthanayaka, Ahmad Hasan, B. R. Lamichhane, J. Remolina, Adolph P. Smith, Michael Schulz

Physics Faculty Research & Creative Works

We have measured fully differential cross sections for ionization of H2 by 75-keV proton impact. The coherence length of the projectile beam was varied by changing the distance between a collimating slit and the target. By comparing the cross sections measured for large and small coherence lengths pronounced interference effects could be identified in the data. A surprising result is that the phase angle in the interference term is primarily determined by the momentum transfer and only to a lesser extent by the recoil-ion momentum.


Multimessenger Search For Sources Of Gravitational Waves And High-Energy Neutrinos: Initial Results For Ligo-Virgo And Icecube, M. G. Aartsen, Marco Cavaglia, For Full List Of Authors, See Publisher's Website. Nov 2014

Multimessenger Search For Sources Of Gravitational Waves And High-Energy Neutrinos: Initial Results For Ligo-Virgo And Icecube, M. G. Aartsen, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

We report the results of a multimessenger search for coincident signals from the LIGO and Virgo gravitational-wave observatories and the partially completed IceCube high-energy neutrino detector, including periods of joint operation between 2007-2010. These include parts of the 2005-2007 run and the 2009-2010 run for LIGO-Virgo, and IceCube's observation periods with 22, 59 and 79 strings. We find no significant coincident events, and use the search results to derive upper limits on the rate of joint sources for a range of source emission parameters. For the optimistic assumption of gravitational-wave emission energy of 10-2M⊙c2 at ...


Light Localization Induced By A Random Imaginary Refractive Index, A. Basiri, Yaron Bromberg, Alexey Yamilov, Tsampikos Kottos Oct 2014

Light Localization Induced By A Random Imaginary Refractive Index, A. Basiri, Yaron Bromberg, Alexey Yamilov, Tsampikos Kottos

Physics Faculty Research & Creative Works

We show the emergence of light localization in arrays of coupled optical waveguides with randomness only in the imaginary part of their refractive index and develop a one-parameter scaling theory for the normalized participation number of Floquet-Bloch modes. This localization introduces a different length scale in the decay of the autocorrelation function of a paraxial beam propagation. Our results are relevant to a vast family of systems with randomness in the dissipative part of their impedance spatial profile.


Enhanced Rare-Region Effects In The Contact Process With Long-Range Correlated Disorder, Ahmed K. Ibrahim, Hatem Barghathi, Thomas Vojta Oct 2014

Enhanced Rare-Region Effects In The Contact Process With Long-Range Correlated Disorder, Ahmed K. Ibrahim, Hatem Barghathi, Thomas Vojta

Physics Faculty Research & Creative Works

We investigate the nonequilibrium phase transition in the disordered contact process in the presence of long-range spatial disorder correlations. These correlations greatly increase the probability for finding rare regions that are locally in the active phase while the bulk system is still in the inactive phase. Specifically, if the correlations decay as a power of the distance, the rare-region probability is a stretched exponential of the rare-region size rather than a simple exponential as is the case for uncorrelated disorder. As a result, the Griffiths singularities are enhanced and take a non-power-law form. The critical point itself is of infinite-randomness ...


Phase Transitions On Random Lattices: How Random Is Topological Disorder?, Hatem Barghathi, Thomas Vojta Sep 2014

Phase Transitions On Random Lattices: How Random Is Topological Disorder?, Hatem Barghathi, Thomas Vojta

Physics Faculty Research & Creative Works

We study the effects of topological (connectivity) disorder on phase transitions. We identify a broad class of random lattices whose disorder fluctuations decay much faster with increasing length scale than those of generic random systems, yielding a wandering exponent of ω = (d−1)/(2d) in d dimensions. The stability of clean critical points is thus governed by the criterion (d+1)ν > 2 rather than the usual Harris criterion dν > 2, making topological disorder less relevant than generic randomness. The Imry-Ma criterion is also modified, allowing first-order transitions to survive in all dimensions d > 1. These results explain a host ...


Strong-Disorder Magnetic Quantum Phase Transitions: Status And New Developments, Thomas Vojta Sep 2014

Strong-Disorder Magnetic Quantum Phase Transitions: Status And New Developments, Thomas Vojta

Physics Faculty Research & Creative Works

This article reviews the unconventional effects of random disorder on magnetic quantum phase transitions, focusing on a number of new experimental and theoretical developments during the last three years. On the theory side, we address smeared quantum phase transitions tuned by changing the chemical composition, for example in alloys of the type A1-xBx. We also discuss how the interplay of order parameter conservation and overdamped dynamics leads to enhanced quantum Griffiths singularities in disordered metallic ferromagnets. Finally, we discuss a semiclassical theory of transport properties in quantum Griffiths phases. Experimental examples include the ruthenates Sr1-xCa ...


Fine-Structure Constant For Gravitational And Scalar Interactions, Ulrich D. Jentschura Aug 2014

Fine-Structure Constant For Gravitational And Scalar Interactions, Ulrich D. Jentschura

Physics Faculty Research & Creative Works

Starting from the coupling of a relativistic quantum particle to the curved Schwarzschild space time, we show that the Dirac-Schwarzschild problem has bound states and calculate their energies including relativistic corrections. Relativistic effects are shown to be suppressed by the gravitational fine-structure constant αG=Gm1m2/(ℏc), where G is Newton's gravitational constant, c is the speed of light, and m1 and m2 ≫ m1 are the masses of the two particles. The kinetic corrections due to space-time curvature are shown to lift the familiar (n,j) degeneracy of the energy levels of the ...


Effect Of The Center-Of-Mass Approximation On The Scaling Of Electron-Capture Fully Differential Cross Sections, A. L. Harris, Don H. Madison Aug 2014

Effect Of The Center-Of-Mass Approximation On The Scaling Of Electron-Capture Fully Differential Cross Sections, A. L. Harris, Don H. Madison

Physics Faculty Research & Creative Works

We present results for p+He single electron capture and transfer with target excitation using the first Born approximation. The effect of approximating the center of mass of the helium atom and outgoing hydrogen atom at the respective nuclei is explored. Semianalytical results are compared for the calculations with and without the approximation, and it is shown that one must properly account for the center of mass of the atoms. It is also shown that this approximation is the result of the apparent v4 scaling that was previously observed with the four-body transfer with target excitation model.


Dynamical (E,2e) Investigations Of Structurally Related Cyclic Ethers, J. D. Builth-Williams, Luca Chiari, Penny A. Thorn, Susan M. Bellm, D. B. Jones, Hari Chaluvadi, Don H. Madison, Chuangang Ning, B. Lohmann, Oddur Ingólfsson, Michael J. Brunger Jul 2014

Dynamical (E,2e) Investigations Of Structurally Related Cyclic Ethers, J. D. Builth-Williams, Luca Chiari, Penny A. Thorn, Susan M. Bellm, D. B. Jones, Hari Chaluvadi, Don H. Madison, Chuangang Ning, B. Lohmann, Oddur Ingólfsson, Michael J. Brunger

Physics Faculty Research & Creative Works

Experimental and theoretical cross sections are presented for electron-impact ionization of a series of cyclic ethers.


Rare Regions And Griffiths Singularities At A Clean Critical Point: The Five-Dimensional Disordered Contact Process, Thomas Vojta, John Igo, José A. Hoyos Jul 2014

Rare Regions And Griffiths Singularities At A Clean Critical Point: The Five-Dimensional Disordered Contact Process, Thomas Vojta, John Igo, José A. Hoyos

Physics Faculty Research & Creative Works

We investigate the nonequilibrium phase transition of the disordered contact process in five space dimensions by means of optimal fluctuation theory and Monte Carlo simulations. We find that the critical behavior is of mean-field type, i.e., identical to that of the clean five-dimensional contact process. It is accompanied by off-critical power-law Griffiths singularities whose dynamical exponent z' saturates at a finite value as the transition is approached. These findings resolve the apparent contradiction between the Harris criterion, which implies that weak disorder is renormalization-group irrelevant, and the rare-region classification, which predicts unconventional behavior. We confirm and illustrate our theory ...


Probing Long-Range Intensity Correlations Inside Disordered Photonic Nanostructures, Raktim Sarma, Alexey Yamilov, Pauf Neupane, Boris Shapiro, Hui Cao Jul 2014

Probing Long-Range Intensity Correlations Inside Disordered Photonic Nanostructures, Raktim Sarma, Alexey Yamilov, Pauf Neupane, Boris Shapiro, Hui Cao

Physics Faculty Research & Creative Works

We report the direct observation of the development of long-range spatial intensity correlation and the growth of intensity fluctuations inside random media. We fabricated quasi-two-dimensional disordered photonic structures and probed light transport from a third dimension. Good agreement between experiment and theory is obtained. We were able to manipulate the long-range intensity correlation and intensity fluctuations inside the disordered waveguides by simply varying the waveguide geometry.


Evidence For Magnetic Clusters In Ni₁₋ₓVₓ Close To The Quantum Critical Concentration, R. Wang, S. Ubaid-Kassis, A. Schroeder, P. J. Baker, F. L. Pratt, S. J. Blundell, T. Lancaster, I. Franke, J. S. Möller, Thomas Vojta Jul 2014

Evidence For Magnetic Clusters In Ni₁₋ₓVₓ Close To The Quantum Critical Concentration, R. Wang, S. Ubaid-Kassis, A. Schroeder, P. J. Baker, F. L. Pratt, S. J. Blundell, T. Lancaster, I. Franke, J. S. Möller, Thomas Vojta

Physics Faculty Research & Creative Works

The d-metal alloy Ni1-xVx undergoes a quantum phase transition from a ferromagnetic ground state to a paramagnetic ground state as the vanadium concentration x is increased. We present magnetization, ac-susceptibility and muon-spin relaxation data at several vanadium concentrations near the critical concentration xc ~ 11.6 % at which the onset of ferromagnetic order is suppressed to zero temperature. Below xc, the muon data reveal a broad magnetic field distribution indicative of a long-range ordered ferromagnetic state with spatial disorder. We show evidence of magnetic clusters in the ferromagnetic phase and close to the phase boundary in ...


Universality Of Returning Electron Wave Packet In High-Order Harmonic Generation With Midinfrared Laser Pulses, Anh-Thu Le, Hui Wei, Cheng Jin, Vu Ngoc Tuoc, Toru Morishita, C. D. Lin Jul 2014

Universality Of Returning Electron Wave Packet In High-Order Harmonic Generation With Midinfrared Laser Pulses, Anh-Thu Le, Hui Wei, Cheng Jin, Vu Ngoc Tuoc, Toru Morishita, C. D. Lin

Physics Faculty Research & Creative Works

We show that a returning electron wave packet in high-order harmonic generation (HHG) with midinfrared laser pulses converges to a universal limit for a laser wavelength above about 3µm. The results are consistent among the different methods: a numerical solution of the time-dependent Schrödinger equation, the strong-field approximation, and the quantum orbits theory. We further analyze how the contribution from different electron "trajectories" survives the macroscopic propagation in the medium. Our result thus provides a new framework for investigating the wavelength scaling law for the HHG yields.


Theoretical And Experimental Investigation Of (E, 2e) Ionization Of Argon 3p In Asymmetric Kinematics At Intermediate Energy, Sadek Amami, Melike Ulu, Zehra Nur Ozer, Murat Yavuz, Suay Kazgoz, Mevlut Dogan, Oleg Zatsarinny, Klaus Bartschat, Don H. Madison Jul 2014

Theoretical And Experimental Investigation Of (E, 2e) Ionization Of Argon 3p In Asymmetric Kinematics At Intermediate Energy, Sadek Amami, Melike Ulu, Zehra Nur Ozer, Murat Yavuz, Suay Kazgoz, Mevlut Dogan, Oleg Zatsarinny, Klaus Bartschat, Don H. Madison

Physics Faculty Research & Creative Works

The field of electron-impact ionization of atoms, or (e, 2e), has provided significant detailed information about the physics of collisions. For ionization of hydrogen and helium, essentially exact numerical methods have been developed which can correctly predict what will happen. For larger atoms, we do not have theories of comparable accuracy. Considerable attention has been given to ionization of inert gases and, of the inert gases, argon seems to be the most difficult target for theory. There have been several studies comparing experiment and perturbative theoretical approaches over the last few decades, and generally qualitative but not quantitative agreement is ...


Control Of Light Diffusion In A Disordered Photonic Waveguide, Raktim Sarma, Timofey Golubev, Alexey Yamilov, Hui Cao Jul 2014

Control Of Light Diffusion In A Disordered Photonic Waveguide, Raktim Sarma, Timofey Golubev, Alexey Yamilov, Hui Cao

Physics Faculty Research & Creative Works

We control the diffusion of light in a disordered photonic waveguide by modulating the waveguide geometry. In a single waveguide of varying cross-section, the diffusion coefficient changes spatially in two dimensions due to localization effects. The intensity distribution inside the waveguide agrees with the prediction of the self-consistent theory of localization. Our work shows that wave diffusion can be efficiently manipulated without modifying the structural disorder.


Methods And Results Of A Search For Gravitational Waves Associated With Gamma-Ray Bursts Using The Geo 600, Ligo, And Virgo Detectors, J. Aasi, Marco Cavaglia, For Full List Of Authors, See Publisher's Website. Jun 2014

Methods And Results Of A Search For Gravitational Waves Associated With Gamma-Ray Bursts Using The Geo 600, Ligo, And Virgo Detectors, J. Aasi, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

In this paper we report on a search for short-duration gravitational wave bursts in the frequency range 64 Hz-1792 Hz associated with gamma-ray bursts (GRBs), using data from GEO 600 and one of the LIGO or Virgo detectors. We introduce the method of a linear search grid to analyze GRB events with large sky localization uncertainties, for example the localizations provided by the Fermi Gamma-ray Burst Monitor (GBM). Coherent searches for gravitational waves (GWs) can be computationally intensive when the GRB sky position is not well localized, due to the corrections required for the difference in arrival time between detectors ...


Search For Gravitational Waves Associated With Γ-Ray Bursts Detected By The Interplanetary Network, J. Aasi, Marco Cavaglia, For Full List Of Authors, See Publisher's Website. Jun 2014

Search For Gravitational Waves Associated With Γ-Ray Bursts Detected By The Interplanetary Network, J. Aasi, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

We present the results of a search for gravitational waves associated with 223 γ-ray bursts (GRBs) detected by the InterPlanetary Network (IPN) in 2005-2010 during LIGO's fifth and sixth science runs and Virgo's first, second, and third science runs. The IPN satellites provide accurate times of the bursts and sky localizations that vary significantly from degree scale to hundreds of square degrees. We search for both a well-modeled binary coalescence signal, the favored progenitor model for short GRBs, and for generic, unmodeled gravitational wave bursts. Both searches use the event time and sky localization to improve the gravitational ...


Theoretical Triple-Differential Cross Sections Of A Methane Molecule By A Proper-Average Method, Hari Chaluvadi, C. G. Ning, Don H. Madison Jun 2014

Theoretical Triple-Differential Cross Sections Of A Methane Molecule By A Proper-Average Method, Hari Chaluvadi, C. G. Ning, Don H. Madison

Physics Faculty Research & Creative Works

For the last few years, our group has calculated cross sections for electron-impact ionization of molecules using the molecular three-body distorted-wave approximation coupled with the orientation-averaged molecular orbital (OAMO) approximation. This approximation was very successful for calculating ionization cross sections for hydrogen molecules and to a lesser extent nitrogen molecules. Recently we used the approximation to calculate single ionization cross sections for the 1t2 state of methane (CH4) and we found major discrepancies with the experimental data. Here we investigate the validity of the OAMO approximation by calculating cross sections that have been properly averaged over all molecular ...


Fully Differential Cross Sections For Electron-Impact Excitation-Ionization Of Aligned D₂, Esam Ali, A. L. Harris, J. Lower, E. Weigold, Chuang-Gang Ning, Don H. Madison Jun 2014

Fully Differential Cross Sections For Electron-Impact Excitation-Ionization Of Aligned D₂, Esam Ali, A. L. Harris, J. Lower, E. Weigold, Chuang-Gang Ning, Don H. Madison

Physics Faculty Research & Creative Works

We examine fully differential cross sections for 176 eV electron-impact dissociative excitation-ionization of orientated D2 for transitions to final ion states 2sσg, 2pσu, and 2pπu. In previous work [Phys. Rev. A 88, 062705 (2013)PLRAAN1050-294710.1103/PhysRevA.88.062705], we calculated these cross sections using the molecular four-body distorted wave (M4DW) method with the ground-state D2 wave function being approximated by a product of two Dyson 1s-type orbitals. The theoretical results were compared with experimental measurements for five different orientations of the target molecule (four in the scattering plane and one perpendicular to the scattering plane). For ...


The Structure Of D₂O-Nonane Nanodroplets, Harshad Pathak, Abdalla Obeidat, Gerald Wilemski, Barbara Wyslouzil Jun 2014

The Structure Of D₂O-Nonane Nanodroplets, Harshad Pathak, Abdalla Obeidat, Gerald Wilemski, Barbara Wyslouzil

Physics Faculty Research & Creative Works

We study the internal structure of nanometer-sized D2O-nonane aerosol droplets formed in supersonic nozzle expansions using a variety of experimental techniques including small angle X-ray scattering (SAXS). By fitting the SAXS spectra to a wide range of droplet structure models, we find that the experimental results are inconsistent with mixed droplets that form aqueous core-organic shell structures, but are quite consistent with spherically asymmetric lens-on-sphere structures. The structure that agrees best with the SAXS data and Fourier transform infra-red spectroscopy measurements is that of a nonane lens on a sphere of D2O with a contact angle in the ...


Search For Gravitational Radiation From Intermediate Mass Black Hole Binaries In Data From The Second Ligo-Virgo Joint Science Run, J. Aasi, Marco Cavaglia, For Full List Of Authors, See Publisher's Website. Jun 2014

Search For Gravitational Radiation From Intermediate Mass Black Hole Binaries In Data From The Second Ligo-Virgo Joint Science Run, J. Aasi, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

This paper reports on an unmodeled, all-sky search for gravitational waves from merging intermediate mass black hole binaries (IMBHB). The search was performed on data from the second joint science run of the LIGO and Virgo detectors (July 2009-October 2010) and was sensitive to IMBHBs with a range up to ∼200Mpc, averaged over the possible sky positions and inclinations of the binaries with respect to the line of sight. No significant candidate was found. Upper limits on the coalescence-rate density of nonspinning IMBHBs with total masses between 100 and 450M and mass ratios between 0.25 and 1 were placed ...


The Clustering Of Galaxies In The Sdss-Iii Baryon Oscillation Spectroscopic Survey: Baryon Acoustic Oscillations In The Data Releases 10 And 11 Galaxy Samples, Lauren Anderson, Eric Aubourg, Shun Saito, For Full List Of Authors, See Publisher's Website. May 2014

The Clustering Of Galaxies In The Sdss-Iii Baryon Oscillation Spectroscopic Survey: Baryon Acoustic Oscillations In The Data Releases 10 And 11 Galaxy Samples, Lauren Anderson, Eric Aubourg, Shun Saito, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

We present a one per cent measurement of the cosmic distance scale from the detections of the baryon acoustic oscillations (BAO) in the clustering of galaxies from the Baryon Oscillation Spectroscopic Survey, which is part of the Sloan Digital Sky Survey III. Our results come from the Data Release 11 (DR11) sample, containing nearly one million galaxies and covering approximately 8500 square degrees and the redshift range 0.2 < z < 0.7. We also compare these results with those from the publicly released DR9 and DR10 samples. Assuming a concordance Λ cold dark matter (ΛCDM) cosmological model, the DR11 sample covers a volume of 13 Gpc3 and is the largest region of the Universe ever surveyed at this density. We measure the correlation function and power spectrum, including density-field reconstruction of the BAO feature. The acoustic ...


Waveforms For Optimal Sub-Kev High-Order Harmonics With Synthesized Two- Or Three-Colour Laser Fields, Cheng Jin, Guoli Wang, Hui Wei, Anh-Thu Le, C. D. Lin May 2014

Waveforms For Optimal Sub-Kev High-Order Harmonics With Synthesized Two- Or Three-Colour Laser Fields, Cheng Jin, Guoli Wang, Hui Wei, Anh-Thu Le, C. D. Lin

Physics Faculty Research & Creative Works

High-order harmonics extending to the X-ray region generated in a gas medium by intense lasers offer the potential for providing tabletop broadband light sources but so far are limited by their low conversion efficiency. Here we show that harmonics can be enhanced by one to two orders of magnitude without an increase in the total laser power if the laser's waveform is optimized by synthesizing two- or three-colour fields. The harmonics thus generated are also favourably phase-matched so that radiation is efficiently built up in the gas medium. Our results, combined with the emerging intense high-repetition MHz lasers, promise ...


Complete Momentum Balance In Ionization Of H₂ By 75-Kev-Proton Impact For Varying Projectile Coherence, Sachin D. Sharma, T. P. Arthanayaka, Ahmad Hasan, B. R. Lamichhane, J. Remolina, Adolph P. Smith, Michael Schulz May 2014

Complete Momentum Balance In Ionization Of H₂ By 75-Kev-Proton Impact For Varying Projectile Coherence, Sachin D. Sharma, T. P. Arthanayaka, Ahmad Hasan, B. R. Lamichhane, J. Remolina, Adolph P. Smith, Michael Schulz

Physics Faculty Research & Creative Works

We report on a kinematically complete experiment on ionization of H2 by proton impact. While a significant impact of the projectile coherence properties on the scattering-angle dependence of double-differential cross sections (DDCSs), reported earlier, is confirmed by the present data, only weak coherence effects are found in the electron and recoil-ion momentum dependence of the DDCSs. This suggests that the phase angle in the interference term is determined primarily by the projectile momentum transfer rather than by the recoil-ion momentum. We therefore cannot rule out the possibility that the interference observed in our data is not primarily due to ...