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Articles 1 - 30 of 1291

Full-Text Articles in Physics

Quantum Interference Of K Capture In Energetic G E31+(1s)-Kr Collisions, R. Schuch, Michael Schulz, For Full List Of Authors, See Publisher's Website. Apr 2020

Quantum Interference Of K Capture In Energetic G E31+(1s)-Kr Collisions, R. Schuch, Michael Schulz, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

We have measured characteristic K x rays in coincidence with the scattered particles from collisions of hydrogenlike Ge ions with Kr atoms. The ions were first accelerated to 8.6 MeV/amu, post-stripped to H-like charge state, and decelerated to around 2.5 MeV/amu. From the measurements the probabilities for K-shell to K-shell charge transfer as a function of collision impact parameters were obtained. The probabilities show an onset of oscillations which are interpreted as quantum interference between the K-shell to K-shell electron transfer amplitudes in two spatially separated coupling regions in the incoming and outgoing parts of the ...


Model Comparison From Ligo-Virgo Data On Gw170817'S Binary Components And Consequences For The Merger Remnant, B. P. Abbott, R. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website. Jan 2020

Model Comparison From Ligo-Virgo Data On Gw170817'S Binary Components And Consequences For The Merger Remnant, B. P. Abbott, R. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

GW170817 is the very first observation of gravitational waves originating from the coalescence of two compact objects in the mass range of neutron stars, accompanied by electromagnetic counterparts, and offers an opportunity to directly probe the internal structure of neutron stars. We perform Bayesian model selection on a wide range of theoretical predictions for the neutron star equation of state. For the binary neutron star hypothesis, we find that we cannot rule out the majority of theoretical models considered. In addition, the gravitational-wave data alone does not rule out the possibility that one or both objects were low-mass black holes ...


The Conundrum Of Relaxation Volumes In First-Principles Calculations Of Charged Defects In Uo₂, Anuj Goyal, Kiran Mathew, Richard G. Hennig, Aleksandr V. Chernatynskiy Dec 2019

The Conundrum Of Relaxation Volumes In First-Principles Calculations Of Charged Defects In Uo₂, Anuj Goyal, Kiran Mathew, Richard G. Hennig, Aleksandr V. Chernatynskiy

Physics Faculty Research & Creative Works

The defect relaxation volumes obtained from density-functional theory (DFT) calculations of charged vacancies and interstitials are much larger than their neutral counterparts, seemingly unphysically large. We focus on UO2 as our primary material of interest, but also consider Si and GaAs to reveal the generality of our results. In this work, we investigate the possible reasons for this and revisit the methods that address the calculation of charged defects in periodic DFT. We probe the dependence of the proposed energy corrections to charged defect formation energies on relaxation volumes and find that corrections such as potential alignment remain ambiguous with ...


Search For Gravitational Waves From Scorpius X-1 In The Second Advanced Ligo Observing Run With An Improved Hidden Markov Model, B. P. Abbott, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website. Dec 2019

Search For Gravitational Waves From Scorpius X-1 In The Second Advanced Ligo Observing Run With An Improved Hidden Markov Model, B. P. Abbott, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

We present results from a semicoherent search for continuous gravitational waves from the low-mass x-ray binary Scorpius X-1, using a hidden Markov model (HMM) to track spin wandering. This search improves on previous HMM-based searches of LIGO data by using an improved frequency domain matched filter, the J-statistic, and by analyzing data from Advanced LIGO's second observing run. In the frequency range searched, from 60 to 650 Hz, we find no evidence of gravitational radiation. At 194.6 Hz, the most sensitive search frequency, we report an upper limit on gravitational wave strain (at 95% confidence) of h0 ...


Lattice Thermal Conductivity Of Quartz At High Pressure And Temperature From The Boltzmann Transport Equation, Xue Xiong, Eugene J. Ragasa, Aleksandr V. Chernatynskiy, Dawei Tang, Simon R. Phillpot Dec 2019

Lattice Thermal Conductivity Of Quartz At High Pressure And Temperature From The Boltzmann Transport Equation, Xue Xiong, Eugene J. Ragasa, Aleksandr V. Chernatynskiy, Dawei Tang, Simon R. Phillpot

Physics Faculty Research & Creative Works

The thermal conductivities along the basal and hexagonal directions of α-quartz silica, the low-temperature form of crystalline SiO2, are predicted from the solution of the Boltzmann transport equation combined with the van Beest, Kramer, and van Santen potential for the temperature up to 900 K and the pressure as high as 4 GPa. The thermal conductivities at atmospheric pressure, which show a negative and nonlinear dependence on temperature, are in reasonable agreement with the experimental data. The influence of pressure on thermal conductivity is positive and linear. The pressure (P) and temperature (T) dependences of the thermal conductivity (λ ...


Local Orbital Degeneracy Lifting As A Precursor To An Orbital-Selective Peierls Transition, E. S. Bozin, W. G. Yin, R. J. Koch, M. Abeykoon, Yew San Hor, H. Zheng, H. C. Lei, C. Petrovic, J. F. Mitchell, S. J. L. Billinge Dec 2019

Local Orbital Degeneracy Lifting As A Precursor To An Orbital-Selective Peierls Transition, E. S. Bozin, W. G. Yin, R. J. Koch, M. Abeykoon, Yew San Hor, H. Zheng, H. C. Lei, C. Petrovic, J. F. Mitchell, S. J. L. Billinge

Physics Faculty Research & Creative Works

Fundamental electronic principles underlying all transition metal compounds are the symmetry and filling of the d-electron orbitals and the influence of this filling on structural configurations and responses. Here we use a sensitive local structural technique, x-ray atomic pair distribution function analysis, to reveal the presence of fluctuating local-structural distortions at high temperature in one such compound, CuIr2S4. We show that this hitherto overlooked fluctuating symmetry-lowering is electronic in origin and will modify the energy-level spectrum and electronic and magnetic properties. The explanation is a local, fluctuating, orbital-degeneracy-lifted state. The natural extension of our result would be ...


Tests Of General Relativity With The Binary Black Hole Signals From The Ligo-Virgo Catalog Gwtc-1, B. P. Abbott, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website. Nov 2019

Tests Of General Relativity With The Binary Black Hole Signals From The Ligo-Virgo Catalog Gwtc-1, B. P. Abbott, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

The detection of gravitational waves by Advanced LIGO and Advanced Virgo provides an opportunity to test general relativity in a regime that is inaccessible to traditional astronomical observations and laboratory tests. We present four tests of the consistency of the data with binary black hole gravitational waveforms predicted by general relativity. One test subtracts the best-fit waveform from the data and checks the consistency of the residual with detector noise. The second test checks the consistency of the low- and high-frequency parts of the observed signals. The third test checks that phenomenological deviations introduced in the waveform model (including in ...


Angular Memory Effect Of Transmission Eigenchannels, Hasan Yllmaz, Chia Wei Hsu, Arthur Goetschy, Stefan Bittner, Stefan Rotter, Alexey Yamilov, Hui Cao Nov 2019

Angular Memory Effect Of Transmission Eigenchannels, Hasan Yllmaz, Chia Wei Hsu, Arthur Goetschy, Stefan Bittner, Stefan Rotter, Alexey Yamilov, Hui Cao

Physics Faculty Research & Creative Works

The optical memory effect has emerged as a powerful tool for imaging through multiple-scattering media; however, the finite angular range of the memory effect limits the field of view. Here, we demonstrate experimentally that selective coupling of incident light into a high-transmission channel increases the angular memory-effect range. This enhancement is attributed to the robustness of the high-transmission channels against perturbations such as sample tilt or wave front tilt. Our work shows that the high-transmission channels provide an enhanced field of view for memory-effect-based imaging through diffusive media.


Search For Eccentric Binary Black Hole Mergers With Advanced Ligo And Advanced Virgo During Their First And Second Observing Runs, B. P. Abbott, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website. Oct 2019

Search For Eccentric Binary Black Hole Mergers With Advanced Ligo And Advanced Virgo During Their First And Second Observing Runs, B. P. Abbott, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

When formed through dynamical interactions, stellar-mass binary black holes (BBHs) may retain eccentric orbits (e > 0.1 at 10 Hz) detectable by ground-based gravitational-wave detectors. Eccentricity can therefore be used to differentiate dynamically formed binaries from isolated BBH mergers. Current template-based gravitational-wave searches do not use waveform models associated with eccentric orbits, rendering the search less efficient for eccentric binary systems. Here we present the results of a search for BBH mergers that inspiral in eccentric orbits using data from the first and second observing runs (O1 and O2) of Advanced LIGO and Advanced Virgo. We carried out the search ...


Probability Density Of The Fractional Langevin Equation With Reflecting Walls, Thomas Vojta, Sarah Skinner, Ralf Metzler Oct 2019

Probability Density Of The Fractional Langevin Equation With Reflecting Walls, Thomas Vojta, Sarah Skinner, Ralf Metzler

Physics Faculty Research & Creative Works

We investigate anomalous diffusion processes governed by the fractional Langevin equation and confined to a finite or semi-infinite interval by reflecting potential barriers. As the random and damping forces in the fractional Langevin equation fulfill the appropriate fluctuation-dissipation relation, the probability density on a finite interval converges for long times towards the expected uniform distribution prescribed by thermal equilibrium. In contrast, on a semi-infinite interval with a reflecting wall at the origin, the probability density shows pronounced deviations from the Gaussian behavior observed for normal diffusion. If the correlations of the random force are persistent (positive), particles accumulate at the ...


Search For Intermediate Mass Black Hole Binaries In The First And Second Observing Runs Of The Advanced Ligo And Virgo Network, B. P. Abbott, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website. Sep 2019

Search For Intermediate Mass Black Hole Binaries In The First And Second Observing Runs Of The Advanced Ligo And Virgo Network, B. P. Abbott, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

Gravitational-wave astronomy has been firmly established with the detection of gravitational waves from the merger of ten stellar-mass binary black holes and a neutron star binary. This paper reports on the all-sky search for gravitational waves from intermediate mass black hole binaries in the first and second observing runs of the Advanced LIGO and Virgo network. The search uses three independent algorithms: two based on matched filtering of the data with waveform templates of gravitational-wave signals from compact binaries, and a third, model-independent algorithm that employs no signal model for the incoming signal. No intermediate mass black hole binary event ...


Directional Limits On Persistent Gravitational Waves Using Data From Advanced Ligo's First Two Observing Runs, B. P. Abbott, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website. Sep 2019

Directional Limits On Persistent Gravitational Waves Using Data From Advanced Ligo's First Two Observing Runs, B. P. Abbott, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

We perform an unmodeled search for persistent, directional gravitational wave (GW) sources using data from the first and second observing runs of Advanced LIGO. We do not find evidence for any GW signals. We place limits on the broadband GW flux emitted at 25 Hz from point sources with a power law spectrum at Fα,Θ < (0.05-25) x 10−8 erg cm−2 s−1 Hz−1 and the (normalized) energy density spectrum in GWs at 25 Hz from extended sources at Ωα(Θ) < (0.19-2.89) x 10−8 sr−1 where α is the spectral index of the energy density spectrum. These represent improvements ...


Erratum: Searches For Gravitational Waves From Known Pulsars At Two Harmonics In 2015-2017 Ligo Data (Astrophysical Journal (2019) 879 (10) Doi: 10.3847/1538-4357/Ab20cb), B. P. Abbott, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website. Sep 2019

Erratum: Searches For Gravitational Waves From Known Pulsars At Two Harmonics In 2015-2017 Ligo Data (Astrophysical Journal (2019) 879 (10) Doi: 10.3847/1538-4357/Ab20cb), B. P. Abbott, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

Due to an error at the publisher, in the published article the number of pulsars presented in the paper is incorrect in multiple places throughout the text. Specifically, "222" pulsars should be "221." Additionally, the number of pulsars for which we have EM observations that fully overlap with O1 and O2 changes from "168" to "167." Elsewhere, in the machine-readable table of Table 1 and in Table 2, the row corresponding to pulsar J0952-0607 should be excised as well. Finally, in the caption for Table 2 the number of pulsars changes from "188" to "187." IOP Publishing sincerely regrets this ...


Gwtc-1: A Gravitational-Wave Transient Catalog Of Compact Binary Mergers Observed By Ligo And Virgo During The First And Second Observing Runs, B. P. Abbott, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website. Sep 2019

Gwtc-1: A Gravitational-Wave Transient Catalog Of Compact Binary Mergers Observed By Ligo And Virgo During The First And Second Observing Runs, B. P. Abbott, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

We present the results from three gravitational-wave searches for coalescing compact binaries with component masses above 1 Ma™ during the first and second observing runs of the advanced gravitational-wave detector network. During the first observing run (O1), from September 12, 2015 to January 19, 2016, gravitational waves from three binary black hole mergers were detected. The second observing run (O2), which ran from November 30, 2016 to August 25, 2017, saw the first detection of gravitational waves from a binary neutron star inspiral, in addition to the observation of gravitational waves from a total of seven binary black hole mergers ...


Search For The Isotropic Stochastic Background Using Data From Advanced Ligo's Second Observing Run, B. P. Abbott, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website. Sep 2019

Search For The Isotropic Stochastic Background Using Data From Advanced Ligo's Second Observing Run, B. P. Abbott, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

The stochastic gravitational-wave background is a superposition of sources that are either too weak or too numerous to detect individually. In this study, we present the results from a cross-correlation analysis on data from Advanced LIGO's second observing run (O2), which we combine with the results of the first observing run (O1). We do not find evidence for a stochastic background, so we place upper limits on the normalized energy density in gravitational waves at the 95% credible level of ΩGW < 6.0 x 10-8 for a frequency-independent (flat) background and ΩGW < 4.8 x 10-8 at 25 Hz for a background of ...


A Dynamical (E,2e) Investigation Into The Ionization Of The Outermost Orbitals Of R-Carvone, D. B. Jones, E. Ali, C. G. Ning, F. Ferreira Da Silva, O. Ingolfsson, M. C. A. Lopes, H. S. Chakraborty, Don H. Madison, M. J. Brunger Sep 2019

A Dynamical (E,2e) Investigation Into The Ionization Of The Outermost Orbitals Of R-Carvone, D. B. Jones, E. Ali, C. G. Ning, F. Ferreira Da Silva, O. Ingolfsson, M. C. A. Lopes, H. S. Chakraborty, Don H. Madison, M. J. Brunger

Physics Faculty Research & Creative Works

We report an experimental and theoretical investigation into the dynamics of electron-impact ionization of R-carvone. Experimental triple differential cross sections are obtained in asymmetric coplanar kinematic conditions for the ionization of the unresolved combination of the three outermost molecular orbitals (41a-39a) of R-carvone. These cross sections are compared with theoretical cross sections calculated within a molecular 3-body distorted wave (M3DW) framework employing either a proper orientation average or orbital average to account for the random orientation of the molecule probed in the experiment. Here, we observe that the overall scattering behavior observed in the experiment is fairly well reproduced within ...


Unconventional Josephson Junctions With Topological Kondo Insulator Weak Links, Xuecheng Ye, Jacob Cook, Erik D. Huemiller, Aaron D. K. Finck, P. K. Ghaemi, Thomas Vojta, For Full List Of Authors, See Publisher's Website. Sep 2019

Unconventional Josephson Junctions With Topological Kondo Insulator Weak Links, Xuecheng Ye, Jacob Cook, Erik D. Huemiller, Aaron D. K. Finck, P. K. Ghaemi, Thomas Vojta, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

Proximity-induced superconductivity in three-dimensional (3D) topological insulators forms a new quantum phase of matter and accommodates exotic quasiparticles such as Majorana bound states. One of the biggest drawbacks of the commonly studied 3D topological insulators is the presence of conducting bulk that obscures both surface states and low energy bound states. Introducing superconductivity in topological Kondo insulators such as SmB6, however, is promising due to their true insulating bulk at low temperatures. In this work, we develop an unconventional Josephson junction by coupling superconducting Nb leads to the surface states of a SmB6 crystal. We observe a robust critical current ...


Neutrino Splitting For Lorentz-Violating Neutrinos: Detailed Analysis, G. Somogyi, I. Nandori, Ulrich D. Jentschura Aug 2019

Neutrino Splitting For Lorentz-Violating Neutrinos: Detailed Analysis, G. Somogyi, I. Nandori, Ulrich D. Jentschura

Physics Faculty Research & Creative Works

Lorentz-violating neutrino parameters have been severely constrained on the basis of astrophysical considerations. In the high-energy limit, one generally assumes a superluminal dispersion relation of an incoming neutrino of the form E≈ |p ⃗|v , where E is the energy, p ⃗ is the momentum and v ₌ √(1+ δ) > 1. Lepton-pair creation due to a Cerenkov-radiation-like process (ν → ν + е-+e+) becomes possible above a certain energy threshold, and bounds on the Lorentz-violating parameter δ can be derived. Here, we investigate a related process, νi→ νi+ νf+ ν ‾f, where νi is an incoming neutrino mass eigenstate, while ...


Inverse Design Of Long-Range Intensity Correlation In Scattering Media, M. Koirala, R. Sarma, H. Cao, Alexey Yamilov Aug 2019

Inverse Design Of Long-Range Intensity Correlation In Scattering Media, M. Koirala, R. Sarma, H. Cao, Alexey Yamilov

Physics Faculty Research & Creative Works

We demonstrate a possibility of using geometry to deterministically control nonlocal correlation of waves undergoing mesoscopic transport through a disordered waveguide. In case of nondissipative medium, we find an explicit relationship between correlation and the shape of the system. Inverting this relationship, we realize inverse design: we obtain specific waveguide shape that leads to a predetermined nonlocal correlation. The proposed technique offers an approach to coherent control of wave propagation in random media that is complementary to wave-front shaping.


Radiative Transfer Distortions Of Lyman Α Emitters: A New Fingers-Of-God Damping In The Clustering In Redshift Space, Chris Byrohl, Shun Saito, Christoph Behrens Aug 2019

Radiative Transfer Distortions Of Lyman Α Emitters: A New Fingers-Of-God Damping In The Clustering In Redshift Space, Chris Byrohl, Shun Saito, Christoph Behrens

Physics Faculty Research & Creative Works

Complex radiative transfer (RT) of the Lyman α photons poses a theoretical challenge to galaxy surveys that infer the large-scale structure with Lyman α emitters (LAEs). Guided by RT simulations, prior studies investigated the impact of RT on the large-scale LAE clustering, and claimed that RT induces a selection effect which results in an anisotropic distortion even in real space but in an otherwise negligible effect in redshift space. However, our previous study, which relies on a full RT code run on the Illustris simulations, shows that the anisotropic selection effect was drastically reduced with higher spatial resolution. Adopting the ...


Pseudo-Periodic Natural Higgs Inflation, I. G. Marian, N. Defenu, Ulrich D. Jentschura, A. Trombettoni, I. Nandori Aug 2019

Pseudo-Periodic Natural Higgs Inflation, I. G. Marian, N. Defenu, Ulrich D. Jentschura, A. Trombettoni, I. Nandori

Physics Faculty Research & Creative Works

Inflationary cosmology represents a well-studied framework to describe the expansion of space in the early universe, as it explains the origin of the large-scale structure of the cosmos and the isotropy of the cosmic microwave background radiation. The recent detection of the Higgs boson renewed research activities based on the assumption that the inflaton could be identified with the Higgs field. At the same time, the question whether the inflationary potential can be extended to the electroweak scale and whether it should be necessarily chosen ad hoc in order to be physically acceptable are at the center of an intense ...


Multicenter Distorted-Wave Approach For Electron-Impact Ionization Of Molecules, Esam Ali, Don H. Madison Jul 2019

Multicenter Distorted-Wave Approach For Electron-Impact Ionization Of Molecules, Esam Ali, Don H. Madison

Physics Faculty Research & Creative Works

We have previously used the molecular three-body distorted-wave model to examine electron-impact single ionization of molecules. One of the possible weaknesses of this approach lies in the fact that the continuum electron wave functions do not depend on the orientation of the molecule. Here we introduce a model called the multicenter molecular three-body distorted-wave (MCM3DW) approach, for which the continuum electron wave functions depend on the orientation of the molecule at the time of ionization. The MCM3DW results are compared with experimental data taken from work by Dorn and colleagues [Ren, Phys. Rev. A 91, 032707 (2015)10.1103/PhysRevA ...


Imaging An Isolated Water Molecule Using A Single Electron Wave Packet, Xinyao Liu, Kasra Amini, Tobias Steinle, Anh-Thu Le, For Full List Of Authors, See Publisher's Website. Jul 2019

Imaging An Isolated Water Molecule Using A Single Electron Wave Packet, Xinyao Liu, Kasra Amini, Tobias Steinle, Anh-Thu Le, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

Observing changes in molecular structure requires atomic-scale Ångstrom and femtosecond spatio-temporal resolution. We use the Fourier transform (FT) variant of laser-induced electron diffraction (LIED), FT-LIED, to directly retrieve the molecular structure of H2O+ with picometer and femtosecond resolution without a priori knowledge of the molecular structure nor the use of retrieval algorithms or ab initio calculations. We identify a symmetrically stretched H2O+ field-dressed structure that is most likely in the ground electronic state. We subsequently study the nuclear response of an isolated water molecule to an external laser field at four different field strengths. We show ...


Searches For Gravitational Waves From Known Pulsars At Two Harmonics In 2015-2017 Ligo Data, B. P. Abbott, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website. Jun 2019

Searches For Gravitational Waves From Known Pulsars At Two Harmonics In 2015-2017 Ligo Data, B. P. Abbott, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

We present a search for gravitational waves from 221 pulsars with rotation frequencies ≳ 10 Hz. We use advanced LIGO data from its first and second observing runs spanning 2015-2017, which provides the highest-sensitivity gravitational-wave data so far obtained. In this search we target emission from both the l = m = 2 mass quadrupole mode, with a frequency at twice that of the pulsar's rotation, and the l = 2, m = 1 mode, with a frequency at the pulsar rotation frequency. The search finds no evidence for gravitational-wave emission from any pulsar at either frequency. For the l = m = 2 mode search ...


Few-Body Dynamics Underlying Postcollision Effects In The Ionization Of H₂ By 75-Kev Proton Impact, M. Dhital, S. Bastola, A. Silvus, Don H. Madison, Michael Schulz Jun 2019

Few-Body Dynamics Underlying Postcollision Effects In The Ionization Of H₂ By 75-Kev Proton Impact, M. Dhital, S. Bastola, A. Silvus, Don H. Madison, Michael Schulz

Physics Faculty Research & Creative Works

We have measured fully differential cross sections (FDCS) for ionization in 75-keVp+H2 collisions for ejected electron speeds close to the projectile speed. The data were analyzed in dependence on both the electron emission angle and the projectile scattering angle. Pronounced postcollisional effects between the projectile and the ejected electrons were observed. Significant differences between experiment and theory and between two conceptually very similar theoretical models were found. This shows that in the region of electron-projectile velocity-matching the FDCS is very sensitive to the details of the underlying few-body dynamics.


Narrow-Band Search For Gravitational Waves From Known Pulsars Using The Second Ligo Observing Run, B. P. Abbott, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website. Jun 2019

Narrow-Band Search For Gravitational Waves From Known Pulsars Using The Second Ligo Observing Run, B. P. Abbott, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

Isolated spinning neutron stars, asymmetric with respect to their rotation axis, are expected to be sources of continuous gravitational waves. The most sensitive searches for these sources are based on accurate matched filtering techniques that assume the continuous wave to be phase locked with the pulsar beamed emission. While matched filtering maximizes the search sensitivity, a significant signal-to-noise ratio loss will happen in the case of a mismatch between the assumed and the true signal phase evolution. Narrow-band algorithms allow for a small mismatch in the frequency and spin-down values of the pulsar while coherently integrating the entire dataset. In ...


Impact Of Anharmonicity On The Vibrational Entropy And Specific Heat Of Uo₂, M. S. Bryan, J. W. L. Pang, B. C. Larson, Aleksandr V. Chernatynskiy, D. L. Abernathy, K. Gofryk, M. E. Manley, For Full List Of Authors, See Publisher's Website. Jun 2019

Impact Of Anharmonicity On The Vibrational Entropy And Specific Heat Of Uo₂, M. S. Bryan, J. W. L. Pang, B. C. Larson, Aleksandr V. Chernatynskiy, D. L. Abernathy, K. Gofryk, M. E. Manley, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

The impact of anharmonicity on the vibrational entropy and heat capacity of UO2 has been investigated from 10 to 1200 K using inelastic neutron-scattering measurements of the phonon density of states (PDOS). Small changes in the PDOS are observed from 10 to 295 K, with more noticeable changes appearing in the 750- and 1200-K data. The specific heat determined from the PDOS measurements is in agreement with macroscopic specific heat measurements, and the overall impact of nondilation anharmonicity on the specific heat has been shown to be less than 2%. An analysis of the phonon measurements shows that the softening ...


Tests Of General Relativity With Gw170817, B. P. Abbott, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website. May 2019

Tests Of General Relativity With Gw170817, B. P. Abbott, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

The recent discovery by Advanced LIGO and Advanced Virgo of a gravitational wave signal from a binary neutron star inspiral has enabled tests of general relativity (GR) with this new type of source. This source, for the first time, permits tests of strong-field dynamics of compact binaries in the presence of matter. In this Letter, we place constraints on the dipole radiation and possible deviations from GR in the post-Newtonian coefficients that govern the inspiral regime. Bounds on modified dispersion of gravitational waves are obtained; in combination with information from the observed electromagnetic counterpart we can also constrain effects due ...


Triple Differential Cross Sections For Electron-Impact Ionization Of Methane At Intermediate Energy, Esam Ali, Carlos Granados, Ahmad Sakaamini, Don H. Madison May 2019

Triple Differential Cross Sections For Electron-Impact Ionization Of Methane At Intermediate Energy, Esam Ali, Carlos Granados, Ahmad Sakaamini, Don H. Madison

Physics Faculty Research & Creative Works

We report an experimental and theoretical investigation of electron-impact single ionization of the highest occupied molecular orbital 1t2 and the next highest occupied molecular orbital 2a1 states of CH4 at an incident electron energy of 250 eV. Triple differential cross sections measured in two different laboratories were compared with results calculated within the molecular 3-body distorted wave and generalized Sturmian function theoretical models. For ionization of the 1t2 state, the binary peak was observed to have a single maximum near the momentum transfer direction that evolved into a double peak for increasing projectile scattering angles, as ...


All-Sky Search For Long-Duration Gravitational-Wave Transients In The Second Advanced Ligo Observing Run, B. P. Abbott, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website. May 2019

All-Sky Search For Long-Duration Gravitational-Wave Transients In The Second Advanced Ligo Observing Run, B. P. Abbott, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

We present the results of a search for long-duration gravitational-wave transients in the data from the Advanced LIGO second observation run; we search for gravitational-wave transients of 2-500 s duration in the 24-2048 Hz frequency band with minimal assumptions about signal properties such as waveform morphologies, polarization, sky location or time of occurrence. Signal families covered by these search algorithms include fallback accretion onto neutron stars, broadband chirps from innermost stable circular orbit waves around rotating black holes, eccentric inspiral-merger-ringdown compact binary coalescence waveforms, and other models. The second observation run totals about 118.3 days of coincident data between ...