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Physics Faculty Research & Creative Works

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Articles 451 - 480 of 1959

Full-Text Articles in Physical Sciences and Mathematics

Many-Body Dissipative Flow Of A Confined Scalar Bose-Einstein Condensate Driven By A Gaussian Impurity, Garyfallia C. Katsimiga, Simeon I. Mistakidis, G. M. Koutentakis, P. G. Kevrekidis, P. Schmelcher Jan 2018

Many-Body Dissipative Flow Of A Confined Scalar Bose-Einstein Condensate Driven By A Gaussian Impurity, Garyfallia C. Katsimiga, Simeon I. Mistakidis, G. M. Koutentakis, P. G. Kevrekidis, P. Schmelcher

Physics Faculty Research & Creative Works

The Many-Body Dissipative Flow Induced By A Mobile Gaussian Impurity Harmonically Oscillating Within A Cigar-Shaped Bose-Einstein Condensate Is Investigated. For Very Small And Large Driving Frequencies The Superfluid Phase Is Preserved. Dissipation Is Identified, For Intermediate Driving Frequencies, By The Nonzero Value Of The Drag Force Whose Abrupt Increase Signals The Spontaneous Downstream Emission Of An Array Of Gray Solitons. After Each Emission Event, Typically Each Of The Solitary Waves Formed Decays And Splits Into Two Daughter Gray Solitary Waves That Are Found To Be Robust Propagating In The Bosonic Background For Large Evolution Times. In Particular, A Smooth Transition …

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The Stripe 82 Massive Galaxy Project. Iii. A Lack Of Growth Among Massive Galaxies, Kevin Bundy, Alexie Leauthaud, Shun Saito, Claudia Maraston, David A. Wake, Daniel Thomas Dec 2017

The Stripe 82 Massive Galaxy Project. Iii. A Lack Of Growth Among Massive Galaxies, Kevin Bundy, Alexie Leauthaud, Shun Saito, Claudia Maraston, David A. Wake, Daniel Thomas

Physics Faculty Research & Creative Works

The average stellar mass (M*) of high-mass galaxies (log M*/M⊙ > 11.5) is expected to grow by ∼30% since z ~ 1, largely through ongoing mergers that are also invoked to explain the observed increase in galaxy sizes. Direct evidence for the corresponding growth in stellar mass has been elusive, however, in part because the volumes sampled by previous redshift surveys have been too small to yield reliable statistics. In this work, we make use of the Stripe 82 Massive Galaxy Catalog (S82-MGC) to build a mass-limited sample of 41,770 galaxies log M*/M⊙ …

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Long-Range Interactions For Hydrogen: 6p-1s And 6p-2s Systems, Ulrich D. Jentschura, Chandra M. Adhikari Dec 2017

Long-Range Interactions For Hydrogen: 6p-1s And 6p-2s Systems, Ulrich D. Jentschura, Chandra M. Adhikari

Physics Faculty Research & Creative Works

The collisional shift of a transition constitutes an important systematic effect in highprecision spectroscopy. Accurate values for van der Waals interaction coefficients are required in order to evaluate the distance-dependent frequency shift. We here consider the interaction of excited hydrogen 6P atoms with metastable atoms (in the 2S state), in order to explore the influence of quasi-degenerate 2P and 6S states on the dipole-dipole interaction. The motivation for the calculation is given by planned high-precision measurements of the transition. Due to the presence of quasi-degenerate levels, one can use the non-retarded approximation for the interaction terms over wide distance ranges.

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Estimating The Contribution Of Dynamical Ejecta In The Kilonova Associated With Gw170817, Benjamin P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website. Dec 2017

Estimating The Contribution Of Dynamical Ejecta In The Kilonova Associated With Gw170817, Benjamin P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

The source of the gravitational-wave (GW) signal GW170817, very likely a binary neutron star merger, was also observed electromagnetically, providing the first multi-messenger observations of this type. The two-week-long electromagnetic (EM) counterpart had a signature indicative of an r-process-induced optical transient known as a kilonova. This Letter examines how the mass of the dynamical ejecta can be estimated without a direct electromagnetic observation of the kilonova, using GW measurements and a phenomenological model calibrated to numerical simulations of mergers with dynamical ejecta. Specifically, we apply the model to the binary masses inferred from the GW measurements, and use the …

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First Low-Frequency Einstein@Home All-Sky Search For Continuous Gravitational Waves In Advanced Ligo Data, Benjamin P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website. Dec 2017

First Low-Frequency Einstein@Home All-Sky Search For Continuous Gravitational Waves In Advanced Ligo Data, Benjamin P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

We report results of a deep all-sky search for periodic gravitational waves from isolated neutron stars in data from the first Advanced LIGO observing run. This search investigates the low frequency range of Advanced LIGO data, between 20 and 100 Hz, much of which was not explored in initial LIGO. The search was made possible by the computing power provided by the volunteers of the Einstein@Home project. We find no significant signal candidate and set the most stringent upper limits to date on the amplitude of gravitational wave signals from the target population, corresponding to a sensitivity depth of 48.7 …

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First Narrow-Band Search For Continuous Gravitational Waves From Known Pulsars In Advanced Detector Data, Benjamin P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website. Dec 2017

First Narrow-Band Search For Continuous Gravitational Waves From Known Pulsars In Advanced Detector Data, Benjamin P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

Spinning neutron stars asymmetric with respect to their rotation axis are potential sources of continuous gravitational waves for ground-based interferometric detectors. In the case of known pulsars a fully coherent search, based on matched filtering, which uses the position and rotational parameters obtained from electromagnetic observations, can be carried out. Matched filtering maximizes the signal-to-noise (SNR) ratio, but a large sensitivity loss is expected in case of even a very small mismatch between the assumed and the true signal parameters. For this reason, narrow-band analysis methods have been developed, allowing a fully coherent search for gravitational waves from known pulsars …

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Gw170608: Observation Of A 19 Solar-Mass Binary Black Hole Coalescence, Benjamin P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website. Dec 2017

Gw170608: Observation Of A 19 Solar-Mass Binary Black Hole Coalescence, Benjamin P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

On 2017 June 8 at 02:01:16.49 UTC, a gravitational-wave (GW) signal from the merger of two stellar-mass blackholes was observed by the two Advanced Laser Interferometer Gravitational-Wave Observatory detectors with a network signal-to-noise ratio of 13. This system is the lightest black hole binary so far observed, with component masses of 12+7 -2M⊙+2-2M⊙ (90% credible intervals). These lie in the range of measured black hole masses in low-mass X-ray binaries, thus allowing us to compare black holes detected through GWs with electromagnetic observations. The source's luminosity distance is 340+140 -140 corresponding to redshift -0.07 …

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On The Progenitor Of Binary Neutron Star Merger Gw170817, Benjamin P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website. Dec 2017

On The Progenitor Of Binary Neutron Star Merger Gw170817, Benjamin P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

On 2017 August 17 the merger of two compact objects with masses consistent with two neutron stars was discovered through gravitational-wave (GW170817), gamma-ray (GRB 170817A), and optical (SSS17a/AT 2017gfo) observations. The optical source was associated with the early-type galaxy NGC 4993 at a distance of just ∼40 Mpc, consistent with the gravitational-wave measurement, and the merger was localized to be at a projected distance of ∼2 kpc away from the galaxy's center. We use this minimal set of facts and the mass posteriors of the two neutron stars to derive the first constraints on the progenitor of GW170817 at the …

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Nematic Topological Superconducting Phase In Nb-Doped Bi₂Se₃, Junying Shen, Wen-Yu He, Noah Fan Qi Yuan, Zengle Huang, Chang-Woo Cho, Seng Huat Lee, Yew San Hor, Kam Tuen Law, Rolf Lortz Dec 2017

Nematic Topological Superconducting Phase In Nb-Doped Bi₂Se₃, Junying Shen, Wen-Yu He, Noah Fan Qi Yuan, Zengle Huang, Chang-Woo Cho, Seng Huat Lee, Yew San Hor, Kam Tuen Law, Rolf Lortz

Physics Faculty Research & Creative Works

A nematic topological superconductor has an order parameter symmetry, which spontaneously breaks the crystalline symmetry in its superconducting state. This state can be observed, for example, by thermodynamic or upper critical field experiments in which a magnetic field is rotated with respect to the crystalline axes. The corresponding physical quantity then directly reflects the symmetry of the order parameter. We present a study on the superconducting upper critical field of the Nb-doped topological insulator NbxBi2Se3 for various magnetic field orientations parallel and perpendicular to the basal plane of the Bi2Se3 layers. The …

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Trigger And Noise Filtering Algorithms For The Lhaaso Water Cherenkov Detector Array, Xiao Jie Wang, Zhi Guo Yao, Min Zha, Ming Jun Chen, Bo Gao, De Zhi Huang, Hui Cai Li, Jin Yan Liu, Wen Ying Liao, Han Rong Wu Dec 2017

Trigger And Noise Filtering Algorithms For The Lhaaso Water Cherenkov Detector Array, Xiao Jie Wang, Zhi Guo Yao, Min Zha, Ming Jun Chen, Bo Gao, De Zhi Huang, Hui Cai Li, Jin Yan Liu, Wen Ying Liao, Han Rong Wu

Physics Faculty Research & Creative Works

Introduction: The Large High Altitude Air Shower Observatory (LHAASO) will be constructed at Mt. Haizishan, Sichuan Province, China. Among several detector components of the LHAASO, the Water Cherenkov Detector Array (WCDA) is of great importance for gamma-ray astronomy from 100 GeV to 30 TeV. The single-channel counting rate of a photo- multiplier tube can reach as high as 30 -35 kHz, most of them are background noise hits from the low energy cosmic ray showers, bringing a big challenge on data transferring, data storage and event reconstruction. Methods: In this paper, a dedicated trigger scheme and a fast noise filtering …

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Many-Body Quantum Dynamics In The Decay Of Bent Dark Solitons Of Bose-Einstein Condensates, Garyfallia C. Katsimiga, Simeon I. Mistakidis, G. M. Koutentakis, P. G. Kevrekidis, P. Schmelcher Dec 2017

Many-Body Quantum Dynamics In The Decay Of Bent Dark Solitons Of Bose-Einstein Condensates, Garyfallia C. Katsimiga, Simeon I. Mistakidis, G. M. Koutentakis, P. G. Kevrekidis, P. Schmelcher

Physics Faculty Research & Creative Works

The Beyond Mean-Field (MF) Dynamics Of A Bent Dark Soliton (BDS) Embedded In A Two-Dimensional Repulsively Interacting Bose-Einstein Condensate Is Explored. We Examine The Case Of A Single BDS Comparing The MF Dynamics To A Correlated Approach, The Multi-Configuration Time-Dependent Hartree Method For Bosons. Dynamical Snaking Of This Bent Structure Is Observed, Signaling The Onset Of Fragmentation Which Becomes Significant During The Vortex Nucleation. In Contrast To The MF Approximation 'filling' Of The Vortex Core Is Observed, Leading In Turn To The Formation Of Filled-Core Vortices, Instead Of The MF Vortex-Antivortex Pairs. The Resulting Smearing Effect In The Density Is …

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Neutrino Pair Cerenkov Radiation For Tachyonic Neutrinos, Ulrich D. Jentschura, Istvan Nandori Nov 2017

Neutrino Pair Cerenkov Radiation For Tachyonic Neutrinos, Ulrich D. Jentschura, Istvan Nandori

Physics Faculty Research & Creative Works

The emission of a charged light lepton pair by a superluminal neutrino has been identified as a major factor in the energy loss of highly energetic neutrinos. The observation of PeV neutrinos by IceCube implies their stability against lepton pair Cerenkov radiation. Under the assumption of a Lorentz-violating dispersion relation for highly energetic superluminal neutrinos, one may thus constrain the Lorentz-violating parameters. A kinematically different situation arises when one assumes a Lorentz-covariant, space-like dispersion relation for hypothetical tachyonic neutrinos, as an alternative to Lorentz-violating theories. We here discuss a hitherto neglected decay process, where a highly energetic tachyonic neutrino may …

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Enhanced Optical Coupling And Raman Scattering Via Microscopic Interface Engineering, Jonathan V. Thompson, Brett H. Hokr, Wihan Kim, Charles W. Ballmann, Brian E. Applegate, Javier Jo, Alexey Yamilov, Hui Cao, Marlan O. Scully, Vladislav V. Yakovlev Nov 2017

Enhanced Optical Coupling And Raman Scattering Via Microscopic Interface Engineering, Jonathan V. Thompson, Brett H. Hokr, Wihan Kim, Charles W. Ballmann, Brian E. Applegate, Javier Jo, Alexey Yamilov, Hui Cao, Marlan O. Scully, Vladislav V. Yakovlev

Physics Faculty Research & Creative Works

Spontaneous Raman scattering is an extremely powerful tool for the remote detection and identification of various chemical materials. However, when those materials are contained within strongly scattering or turbid media, as is the case in many biological and security related systems, the sensitivity and range of Raman signal generation and detection is severely limited. Here, we demonstrate that through microscopic engineering of the optical interface, the optical coupling of light into a turbid material can be substantially enhanced. This improved coupling facilitates the enhancement of the Raman scattering signal generated by molecules within the medium. In particular, we detect at …

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Search For High-Energy Neutrinos From Binary Neutron Star Merger Gw170817 With Antares, Icecube, And The Pierre Auger Observatory, A. Albert, Marco Cavaglia, For Full List Of Authors, See Publisher's Website. Nov 2017

Search For High-Energy Neutrinos From Binary Neutron Star Merger Gw170817 With Antares, Icecube, And The Pierre Auger Observatory, A. Albert, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

The Advanced LIGO and Advanced Virgo observatories recently discovered gravitational waves from a binary neutron star inspiral. A short gamma-ray burst (GRB) that followed the merger of this binary was also recorded by the Fermi Gamma-ray Burst Monitor (Fermi-GBM), and the Anti-Coincidence Shield for the Spectrometer for the International Gamma-Ray Astrophysics Laboratory (INTEGRAL), indicating particle acceleration by the source. The precise location of the event was determined by optical detections of emission following the merger. We searched for high-energy neutrinos from the merger in the GeV-EeV energy range using the Antares, IceCube, and Pierre Auger Observatories. No neutrinos …

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Study Of Inelastic Processes In Li⁺-Ar, K+-Ar, And Na+-He Collisions In The Energy Range 0.5-10 Kev, Ramaz A. Lomsadze, Malkhaz R. Gochitashvili, Roman Ya Kezerashvili, Michael Schulz Oct 2017

Study Of Inelastic Processes In Li⁺-Ar, K+-Ar, And Na+-He Collisions In The Energy Range 0.5-10 Kev, Ramaz A. Lomsadze, Malkhaz R. Gochitashvili, Roman Ya Kezerashvili, Michael Schulz

Physics Faculty Research & Creative Works

Absolute cross sections are measured for charge-exchange, ionization, and excitation processes within the same experimental setup for the Li+-Ar, K+-Ar, and Na+-He collisions in the ion energy range of 0.5-10 keV. The results of the measurements and schematic correlation diagrams are used to analyze and determine the mechanisms for these processes. The experimental results show that the charge-exchange processes occur with high probabilities and electrons are predominantly captured in ground states. The contributions of various partial inelastic channels to the total ionization cross section are estimated, and a primary mechanism for the process is identified. In addition, the energy-loss spectrum …

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Fully Differential Study Of Dissociative Single Capture And Coulomb Explosion Through Double Capture In P+ H2 Collisions, B. R. Lamichhane, Ahmad Hasan, T. Arthanayaka, M. Dhital, K. Koirala, T. Voss, R. A. Lomsadze, Michael Schulz Oct 2017

Fully Differential Study Of Dissociative Single Capture And Coulomb Explosion Through Double Capture In P+ H2 Collisions, B. R. Lamichhane, Ahmad Hasan, T. Arthanayaka, M. Dhital, K. Koirala, T. Voss, R. A. Lomsadze, Michael Schulz

Physics Faculty Research & Creative Works

We have measured fully differential cross sections for dissociative single capture and Coulomb explosion through double capture in 75 keV p+H2 collisions. Data were analyzed for fixed kinetic energy releases and molecular orientations as a function of scattering angle. Two-center interference was identified for dissociative single capture. The interference pattern is not inconsistent with the symmetry of the dissociative electronic state affecting the phase angle of the interference term. No clear signatures of single-center interference were observed for either process. For double capture at most only a very weak two-center interference structure was found. This very small (or zero) visibility …

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Gw170814: A Three-Detector Observation Of Gravitational Waves From A Binary Black Hole Coalescence, Benjamin P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website. Oct 2017

Gw170814: A Three-Detector Observation Of Gravitational Waves From A Binary Black Hole Coalescence, Benjamin P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

On August 14, 2017 at 10 30:43 UTC, the Advanced Virgo detector and the two Advanced LIGO detectors coherently observed a transient gravitational-wave signal produced by the coalescence of two stellar mass black holes, with a false-alarm rate of ≲1 in 27 000 years. The signal was observed with a three-detector network matched-filter signal-to-noise ratio of 18. The inferred masses of the initial black holes are 30.5-3.0+5.7M⊙ and 25.3-4.2+2.8M⊙ (at the 90% credible level). The luminosity distance of the source is 540-210+130 Mpc, corresponding to a redshift of z=0.11-0.04+0.03 …

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Gw170817: Observation Of Gravitational Waves From A Binary Neutron Star Inspiral, Benjamin P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website. Oct 2017

Gw170817: Observation Of Gravitational Waves From A Binary Neutron Star Inspiral, Benjamin P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

On August 17, 2017 at 12-41:04 UTC the Advanced LIGO and Advanced Virgo gravitational-wave detectors made their first observation of a binary neutron star inspiral. The signal, GW170817, was detected with a combined signal-to-noise ratio of 32.4 and a false-alarm-rate estimate of less than one per 8.0 x 104 years. We infer the component masses of the binary to be between 0.86 and 2.26 M⊙, in agreement with masses of known neutron stars. Restricting the component spins to the range inferred in binary neutron stars, we find the component masses to be in the range 1.17-1.60 M …

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Multi-Messenger Observations Of A Binary Neutron Star Merger, Benjamin P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website. Oct 2017

Multi-Messenger Observations Of A Binary Neutron Star Merger, Benjamin P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+ 8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in …

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Long-Range Interactions Of Hydrogen Atoms In Excited States. Iii. Ns−1s Interactions For N ≥ 3, Chandra M. Adhikari, V. Debierre, Ulrich D. Jentschura Sep 2017

Long-Range Interactions Of Hydrogen Atoms In Excited States. Iii. Ns−1s Interactions For N ≥ 3, Chandra M. Adhikari, V. Debierre, Ulrich D. Jentschura

Physics Faculty Research & Creative Works

The long-range interaction of excited neutral atoms has a number of interesting and surprising properties such as the prevalence of long-range oscillatory tails and the emergence of numerically large van der Waals C6 coefficients. Furthermore, the energetically quasidegenerate nP states require special attention and lead to mathematical subtleties. Here we analyze the interaction of excited hydrogen atoms in nS states (3 ≤ n ≤ 12) with ground-state hydrogen atoms and find that the C6 coefficients roughly grow with the fourth power of the principal quantum number and can reach values in excess of 240000 (in atomic units) for states …

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Recent Advances In Understanding The Structure And Properties Of Amorphous Oxide Semiconductors, Julia E. Medvedeva, D. B. Buchholz, Robert P. H. Chang Sep 2017

Recent Advances In Understanding The Structure And Properties Of Amorphous Oxide Semiconductors, Julia E. Medvedeva, D. B. Buchholz, Robert P. H. Chang

Physics Faculty Research & Creative Works

Amorphous oxide semiconductors (AOSs)--ternary or quaternary oxides of post-transition metals such as In-Sn-O, Zn-Sn-O, or In-Ga-Zn-O–have been known for a decade and have attracted a great deal of attention as they possess several technological advantages, including low-temperature large-area deposition, mechanical flexibility, smooth surfaces, and high carrier mobility that is an order of magnitude larger than that of amorphous silicon (a-Si:H). Compared to their crystalline counterparts, the structure of AOSs is extremely sensitive to deposition conditions, stoichiometry, and composition, giving rise to a wide range of tunable optical and electrical properties. The large parameter space and the resulting complex deposition--structure--property relationships …

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All-Sky Search For Periodic Gravitational Waves In The O1 Ligo Data, Benjamin P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website. Sep 2017

All-Sky Search For Periodic Gravitational Waves In The O1 Ligo Data, Benjamin P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

We report on an all-sky search for periodic gravitational waves in the frequency band 20-475 Hz and with a frequency time derivative in the range of [-1.0,+0.1] x 10-8 Hz/s. Such a signal could be produced by a nearby spinning and slightly nonaxisymmetric isolated neutron star in our galaxy. This search uses the data from Advanced LIGO's first observational run, O1. No periodic gravitational wave signals were observed, and upper limits were placed on their strengths. The lowest upper limits on worst-case (linearly polarized) strain amplitude h0 are ∼4 x 10-25 near 170 Hz. For a circularly …

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Upper Limits On Gravitational Waves From Scorpius X-1 From A Model-Based Cross-Correlation Search In Advanced Ligo Data, Benjamin P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website. Sep 2017

Upper Limits On Gravitational Waves From Scorpius X-1 From A Model-Based Cross-Correlation Search In Advanced Ligo Data, Benjamin P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

We present the results of a semicoherent search for continuous gravitational waves from the low-mass X-ray binary Scorpius X-1, using data from the first Advanced LIGO observing run. The search method uses details of the modeled, parametrized continuous signal to combine coherently data separated by less than a specified coherence time, which can be adjusted to trade off sensitivity against computational cost. A search was conducted over the frequency range 25-2000 Hz, spanning the current observationally constrained range of binary orbital parameters. No significant detection candidates were found, and frequency-dependent upper limits were set using a combination of sensitivity estimates …

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Robust Odd-Parity Superconductivity In The Doped Topological Insulator Nbₓbi₂Se₃, M. P. Smylie, K. Willa, H. Claus, A. Snezhko, I. Martin, W.-K. Kwok, Y. Qiu, Yew San Hor, E. Bokari, P. Niraula, A. Kayani, V. Mishra, U. Welp Sep 2017

Robust Odd-Parity Superconductivity In The Doped Topological Insulator Nbₓbi₂Se₃, M. P. Smylie, K. Willa, H. Claus, A. Snezhko, I. Martin, W.-K. Kwok, Y. Qiu, Yew San Hor, E. Bokari, P. Niraula, A. Kayani, V. Mishra, U. Welp

Physics Faculty Research & Creative Works

We present resistivity and magnetization measurements on proton-irradiated crystals demonstrating that the superconducting state in the doped topological insulator NbxBi2Se3 (x=0.25) is surprisingly robust against disorder-induced electron scattering. The superconducting transition temperature TC decreases without indication of saturation with increasing defect concentration, and the corresponding scattering rates far surpass expectations based on conventional theory. The low-temperature variation of the London penetration depth Δλ(T) follows a power law [Δλ(T)T2] indicating the presence of symmetry-protected point nodes. Our results are consistent with the proposed robust nematic Eu pairing state in this material.

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Fully Differential Study Of Capture With Vibrational Dissociation In P+ H2 Collisions, B. R. Lamichhane, T. Arthanayaka, J. Remolina, Ahmad Hasan, M. F. Ciappina, F. Navarrete, R. O. Barrachina, R. A. Lomsadze, Michael Schulz Aug 2017

Fully Differential Study Of Capture With Vibrational Dissociation In P+ H2 Collisions, B. R. Lamichhane, T. Arthanayaka, J. Remolina, Ahmad Hasan, M. F. Ciappina, F. Navarrete, R. O. Barrachina, R. A. Lomsadze, Michael Schulz

Physics Faculty Research & Creative Works

We have measured fully differential cross sections for electron capture in 75 keV p+H2 collisions with subsequent dissociation of the intermediate molecular H2+ ion by vibrational excitation using different projectile coherence lengths. Data were obtained for two molecular orientations as a function of projectile scattering angle. Two types of interference, single- and molecular two-center interference, were identified. The two-center interference structure is phase shifted by π compared to what we expected. Furthermore, the presence of projectile coherence effects could be reconfirmed.

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Differential Measurements Of Ionization And Excitation Of H2 By 250 Ev Positrons, O. G. De Lucio, Robert D. Dubois Aug 2017

Differential Measurements Of Ionization And Excitation Of H2 By 250 Ev Positrons, O. G. De Lucio, Robert D. Dubois

Physics Faculty Research & Creative Works

Synopsis Ejected electron-recoil ion and scattered projectile-recoil ion coincidences are measured for 250 eV positron impact on molecular hydrogen. The electron detector is also sensitive to photon emission. Various combinations of these coincidence spectra are used to extract differential information about ionization and excitation of H2.

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Benchmark Calculations Of Double Ionization Of Ne In Graphics Processing Units, F. D. Colavecchia, Michael Schulz, T. Kirchner, M. F. Ciappina Aug 2017

Benchmark Calculations Of Double Ionization Of Ne In Graphics Processing Units, F. D. Colavecchia, Michael Schulz, T. Kirchner, M. F. Ciappina

Physics Faculty Research & Creative Works

Synopsis In this work we present the analysis of the numerical performance and accuracy of the Monte Carlo Event Generator method applied to the double ionization of Neon by fast electrons. This implementation of the code runs in Graphics Processing Units, giving a clear advantage over other computational approaches. The code can provide five hundred cross sections per second with the optimal configuration, an order of magnitude faster than CPU counterparts.

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Quantum Oscillations In The Anomalous Spin Density Wave State Of Feas, Daniel J. Campbell, Chris Eckberg, Kefeng Wang, Limin Wang, Halyna Hodovanets, Dave Graf, David Parker, Johnpierre Paglione Aug 2017

Quantum Oscillations In The Anomalous Spin Density Wave State Of Feas, Daniel J. Campbell, Chris Eckberg, Kefeng Wang, Limin Wang, Halyna Hodovanets, Dave Graf, David Parker, Johnpierre Paglione

Physics Faculty Research & Creative Works

Quantum oscillations in the binary antiferromagnetic metal FeAs are presented and compared to theoretical predictions for the electronic band structure in the anomalous spin density wave state of this material. Demonstrating a method for growing single crystals out of Bi flux, we utilize the highest quality FeAs to perform torque magnetometry experiments up to 35 T, using rotations of field angle in two planes to provide evidence for one electron and one hole band in the magnetically ordered state. The resulting picture agrees with previous experimental evidence for multiple carriers at low temperatures, but the exact Fermi surface shape differs …

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Inverse Design Of Perfectly Transmitting Eigenchannels In Scattering Media, Milan Koirala, Raktim Sarma, Hui Cao, Alexey Yamilov Aug 2017

Inverse Design Of Perfectly Transmitting Eigenchannels In Scattering Media, Milan Koirala, Raktim Sarma, Hui Cao, Alexey Yamilov

Physics Faculty Research & Creative Works

Light-matter interactions inside a turbid medium can be controlled by tailoring the spatial distribution of energy density throughout the system. Wavefront shaping allows selective coupling of incident light to different transmission eigenchannels, producing dramatically different spatial intensity profiles. In contrast to the density of transmission eigenvalues that is dictated by the universal bimodal distribution, the spatial structures of the eigenchannels are not universal and depend on the confinement geometry of the system. Here, we develop and verify a model for the transmission eigenchannel with the corresponding eigenvalue close to unity. By projecting the original problem of two-dimensional diffusion in a …

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(E,2e) Ionization Studies Of N₂ At Low To Intermediate Energies From A Coplanar Geometry To The Perpendicular Plane, Ahmad Sakaamini, Matthew Harvey, Sadek Amami, Andrew James Murray, Don H. Madison, Chuangang Ning Aug 2017

(E,2e) Ionization Studies Of N₂ At Low To Intermediate Energies From A Coplanar Geometry To The Perpendicular Plane, Ahmad Sakaamini, Matthew Harvey, Sadek Amami, Andrew James Murray, Don H. Madison, Chuangang Ning

Physics Faculty Research & Creative Works

Synopsis. The progress of experimental and theoretical measurements for (e,2e) ionization cross sections from Nitrogen molecules is presented. Results are given for energies from ~10 eV above the ionization potential (IP) through to ~100 eV above the IP for the 3σg, 1πu and 2σg states.

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