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Articles 601 - 630 of 1762
Full-Text Articles in Physical Sciences and Mathematics
Generation Of Isolated Attosecond Pulses In The Far Field By Spatial Filtering With An Intense Few-Cycle Mid-Infrared Laser, Cheng Jin, Anh-Thu Le, Carlos A. Trallero-Herrero, C. D. Lin
Generation Of Isolated Attosecond Pulses In The Far Field By Spatial Filtering With An Intense Few-Cycle Mid-Infrared Laser, Cheng Jin, Anh-Thu Le, Carlos A. Trallero-Herrero, C. D. Lin
Physics Faculty Research & Creative Works
We report theoretical calculations of high-order harmonic generation (HHG) of Xe with the inclusion of multielectron effects and macroscopic propagation of the fundamental and harmonic fields in an ionizing medium. By using the time-frequency analysis we show that the reshaping of the fundamental laser field is responsible for the continuum structure in the HHG spectra. We further suggest a method for obtaining an isolated attosecond pulse (IAP) by using a filter centered on axis to select the harmonics in the far field with different divergence. We also discuss the carrier-envelope-phase dependence of an IAP and the possibility to optimize the …
Orientation Dependence Of The Ionization Of Co And No In An Intense Femtosecond Two-Color Laser Field, H. Li, D. Ray, S. De, I. Znakovskaya, W. Cao, G. Laurent, Z. Wang, M. F. Kling, Anh-Thu Le, C. L. Cocke
Orientation Dependence Of The Ionization Of Co And No In An Intense Femtosecond Two-Color Laser Field, H. Li, D. Ray, S. De, I. Znakovskaya, W. Cao, G. Laurent, Z. Wang, M. F. Kling, Anh-Thu Le, C. L. Cocke
Physics Faculty Research & Creative Works
Two-color (800- and 400-nm) short (45-fs) linearly polarized pulses are used to ionize and dissociate CO and NO. The emission of Cq+, Nq+, and O⁺ fragments indicates that the higher ionization rate occurs when the peak electric field points from C to O in CO and from N to O in NO. This preferred direction is in agreement with that predicted by Stark-corrected strong-field-approximation calculations.
Transport Properties In Antiferromagnetic Quantum Griffiths Phases, David Nozadze, Thomas Vojta
Transport Properties In Antiferromagnetic Quantum Griffiths Phases, David Nozadze, Thomas Vojta
Physics Faculty Research & Creative Works
We study the electrical resistivity in the quantum Griffiths phase associated with the antiferromagnetic quantum phase transition in a metal. The resistivity is calculated by means of the semi-classical Boltzmann equation. We show that the scattering of electrons by locally ordered rare regions leads to a singular temperature dependence. The rare-region contribution to the resistivity varies as Tλ with temperature T, where λ is the usual Griffiths exponent which takes the value zero at the critical point and increases with distance from criticality. We find similar singular contributions to other transport properties such as thermal resistivity, thermopower and the …
Double Ionization Of Helium By Highly-Charged-Ion Impact Analyzed Within The Frozen-Correlation Approximation, Marcelo F. Ciappina, Tom Kirchner, Michael Schulz
Double Ionization Of Helium By Highly-Charged-Ion Impact Analyzed Within The Frozen-Correlation Approximation, Marcelo F. Ciappina, Tom Kirchner, Michael Schulz
Physics Faculty Research & Creative Works
We apply the frozen-correlation approximation (FCA) to analyze double ionization of helium by energetic highly charged ions. In this model the double ionization amplitude is represented in terms of single ionization amplitudes, which we evaluate within the continuum distorted wave-eikonal initial state (CDW-EIS) approach. Correlation effects are incorporated in the initial and final states, but are neglected during the time the collision process takes place. We implement the FCA using the Monte Carlo event generator technique, which allows us to generate theoretical event files and to compare theory and experiment using the same analysis tools. The comparison with previous theoretical …
Microscopic Examination Of Hot Spots Giving Rise To Nonlinearity In Superconducting Resonators, Cihan Kurter, Alexander P. Zhuravel, Alexey V. Ustinov, Steven M. Anlage
Microscopic Examination Of Hot Spots Giving Rise To Nonlinearity In Superconducting Resonators, Cihan Kurter, Alexander P. Zhuravel, Alexey V. Ustinov, Steven M. Anlage
Physics Faculty Research & Creative Works
We investigate the microscopic origins of nonlinear rf response in superconducting electromagnetic resonators. Strong nonlinearity appearing in the transmission spectra at high input powers manifests itself through the emergence of jumplike features near the resonant frequency that evolve toward lower quality factor with higher insertion loss as the rf input power is increased. We directly relate these characteristics to the dynamics of localized normal regions (hot spots) caused by microscopic features in the superconducting material making up the resonator. A clear observation of hot-spot formation inside a Nb thin film self-resonant structure is presented by employing the microwave laser scanning …
Electron Loss From Fast Heavy Ions: Target-Scaling Dependence, Robert D. Dubois, A. C.F. Santos, G. M. Sigaud, E. C. Montenegro
Electron Loss From Fast Heavy Ions: Target-Scaling Dependence, Robert D. Dubois, A. C.F. Santos, G. M. Sigaud, E. C. Montenegro
Physics Faculty Research & Creative Works
The target dependence for projectile electron loss is investigated using experimental data taken from the literature. Impact energies range from a few tens of eV/u to tens of MeV/u. for energies less than several MeV/u, the target dependences are shown to be very similar, independent of projectile species and charge state. overall, however, with increasing impact energy the cross-section dependence on the target nuclear charge systematically increases. It is shown that none of the existing cross-section target scaling models reproduce these features. a model, based on Born scaling and including both the Anti screening and screening contributions to projectile electron …
Strong-Field Nonsequential Double Ionization Of Ar And Ne, Zhangjin Chen, Yaqiu Liang, Don H. Madison, Chiidong Lin
Strong-Field Nonsequential Double Ionization Of Ar And Ne, Zhangjin Chen, Yaqiu Liang, Don H. Madison, Chiidong Lin
Physics Faculty Research & Creative Works
We investigate the nonsequential double ionization (NSDI) of Ar and Ne based on quantitative rescattering theory (QRS). According to QRS theory, each elementary NSDI process can be calculated by multiplying the returning electron wave packet with appropriate differential electron-ion scattering cross sections. We include (e, 2e) and electron-impact excitation cross sections of Ar+ to obtain the correlated electron momentum spectra for the NSDI of Ar by few-cycle pulses to check the dependence of NSDI on the carrier-envelope phase. The results are compared to the ion momentum spectra from the recent experiment of Johnson [Phys. Rev. APLRAAN1050-294710.1103/ PhysRevA.83.013412 83, 013412 …
Mutual Projectile And Target Ionization In 1-Mev/Amu N⁴⁺ And N₅⁺+ He Collisions, Xincheng Wang, Katharina R. Schneider, Aditya H. Kelkar, Gunterschul Brenner, Michael Schulz, B. Najjari, Alexander B. Voitkiv, M. Gundmundsson, Manfred Grieser, Claude Krantz, Michael Lestinsky, Andreas R. Wolf, Siegbert Hagmann, Robert Moshammer, Joachim Hermann Ullrich, Daniel Fischer
Mutual Projectile And Target Ionization In 1-Mev/Amu N⁴⁺ And N₅⁺+ He Collisions, Xincheng Wang, Katharina R. Schneider, Aditya H. Kelkar, Gunterschul Brenner, Michael Schulz, B. Najjari, Alexander B. Voitkiv, M. Gundmundsson, Manfred Grieser, Claude Krantz, Michael Lestinsky, Andreas R. Wolf, Siegbert Hagmann, Robert Moshammer, Joachim Hermann Ullrich, Daniel Fischer
Physics Faculty Research & Creative Works
We have studied mutual projectile and target ionization in 1-MeV/amu N4+ and N5++He collisions in kinematically complete experiments by measuring the momenta of the recoil ion and both ejected electrons in coincidence with the charge-changed projectiles. By means of four-particle Dalitz plots, in which multiple differential cross sections are presented as a function of the momenta of all four particles, experimental spectra are compared with theoretical results from various models. The experimental data are qualitatively reproduced by higher-order calculations, where good agreement is achieved for N5++He collisions, while some discrepancies persist for N4++He …
Relativistic Reduced-Mass And Recoil Corrections To Vacuum Polarization In Muonic Hydrogen, Muonic Deuterium, And Muonic Helium Ions, Ulrich D. Jentschura
Relativistic Reduced-Mass And Recoil Corrections To Vacuum Polarization In Muonic Hydrogen, Muonic Deuterium, And Muonic Helium Ions, Ulrich D. Jentschura
Physics Faculty Research & Creative Works
The reduced-mass dependence of relativistic and radiative effects in simple muonic bound systems is investigated. The spin-dependent nuclear recoil correction of order (Zα)4μ3/m2N is evaluated for muonic hydrogen and deuterium and muonic helium ions (μ is the reduced mass and mN is the nuclear mass). Relativistic corrections to vacuum polarization of order α(Zα)4μ are calculated, with a full account of the reduced-mass dependence. The results shift theoretical predictions. The radiative-recoil correction to vacuum polarization of order α(Zα)5-ln2(Zα) μ2/mN is obtained in leading logarithmic approximation. …
Classical Analogue Of Electromagnetically Induced Transparency With A Metal-Superconductor Hybrid Metamaterial, Cihan Kurter, Philippe Tassin, Lei Zhang, Thomas Koschny, Alexander P. Zhuravel, Alexey V. Ustinov, Steven Mark Anlage, Costas M. Soukoulis
Classical Analogue Of Electromagnetically Induced Transparency With A Metal-Superconductor Hybrid Metamaterial, Cihan Kurter, Philippe Tassin, Lei Zhang, Thomas Koschny, Alexander P. Zhuravel, Alexey V. Ustinov, Steven Mark Anlage, Costas M. Soukoulis
Physics Faculty Research & Creative Works
Metamaterials are engineered materials composed of small electrical circuits producing novel interactions with electromagnetic waves. Recently, a new class of metamaterials has been created to mimic the behavior of media displaying electromagnetically induced transparency (EIT). Here we introduce a planar EIT metamaterial that creates a very large loss contrast between the dark and radiative resonators by employing a superconducting Nb film in the dark element and a normal-metal Au film in the radiative element. Below the critical temperature of Nb, the resistance contrast opens up a transparency window along with a large enhancement in group delay, enabling a significant slowdown …
Composition-Tuned Smeared Phase Transitions, Fawaz Hrahsheh, David Nozadze, Thomas Vojta
Composition-Tuned Smeared Phase Transitions, Fawaz Hrahsheh, David Nozadze, Thomas Vojta
Physics Faculty Research & Creative Works
Phase transitions in random systems are smeared if individual spatial regions can order independently of the bulk system. In this paper, we study such smeared phase transitions (both classical and quantum) in substitutional alloys A 1-xB x that can be tuned from an ordered phase at composition x=0 to a disordered phase at x=1. We show that the ordered phase develops a pronounced tail that extends over all compositions x<1. Using optimal fluctuation theory, we derive the composition dependence of the order parameter and other quantities in the tail of the smeared phase transition. We also compare our results to computer simulations of a toy model, and we discuss experiments.
Young-Type Interference In Projectile-Electron Loss In Energetic Ion-Molecule Collisions, Alexander B. Voitkiv, B. Najjari, Daniel Fischer, Anton N. Artemyev, Andrey S. Surzhykov
Young-Type Interference In Projectile-Electron Loss In Energetic Ion-Molecule Collisions, Alexander B. Voitkiv, B. Najjari, Daniel Fischer, Anton N. Artemyev, Andrey S. Surzhykov
Physics Faculty Research & Creative Works
Under certain conditions an electron bound in a fast projectile ion, colliding with a molecule, interacts mainly with the nuclei and inner shell electrons of atoms forming the molecule. Because of their compact localization in space and distinct separation from each other, these molecular centers play in such collisions a role similar to that of optical slits in light scattering leading to pronounced interference in the spectra of the electron emitted from the projectile.
Search For Gravitational Wave Bursts From Six Magnetars, J. Abadie, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Search For Gravitational Wave Bursts From Six Magnetars, J. Abadie, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Physics Faculty Research & Creative Works
Soft gamma repeaters (SGRs) and anomalous X-ray pulsars (AXPs) are thought to be magnetars: neutron stars powered by extreme magnetic fields. These rare objects are characterized by repeated and sometimes spectacular gamma-ray bursts. The burst mechanism might involve crustal fractures and excitation of non-radial modes which would emit gravitational waves (GWs). We present the results of a search for GW bursts from six galactic magnetars that is sensitive to neutron star f-modes, thought to be the most efficient GW emitting oscillatory modes in compact stars. One of them, SGR 0501+4516, is likely ∼1kpc from Earth, an order of magnitude …
Search For Gravitational Waves From Binary Black Hole Inspiral, Merger, And Ringdown, J. Abadie, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Search For Gravitational Waves From Binary Black Hole Inspiral, Merger, And Ringdown, J. Abadie, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Physics Faculty Research & Creative Works
We present the first modeled search for gravitational waves using the complete binary black-hole gravitational waveform from inspiral through the merger and ringdown for binaries with negligible component spin. We searched approximately 2 years of LIGO data, taken between November 2005 and September 2007, for systems with component masses of 1-99M⊙ and total masses of 25-100M⊙. We did not detect any plausible gravitational-wave signals but we do place upper limits on the merger rate of binary black holes as a function of the component masses in this range. We constrain the rate of mergers for 19M⊙ …
Evidence For Power-Law Griffiths Singularities In A Layered Heisenberg Magnet, Fawaz Hrahsheh, Hatem Barghathi, Priyanka Mohan, Rajesh Narayanan, Thomas Vojta
Evidence For Power-Law Griffiths Singularities In A Layered Heisenberg Magnet, Fawaz Hrahsheh, Hatem Barghathi, Priyanka Mohan, Rajesh Narayanan, Thomas Vojta
Physics Faculty Research & Creative Works
We study the ferromagnetic phase transition in a randomly layered Heisenberg model. A recent strong-disorder renormalization group approach [Phys. Rev. B 81, 144407 (2010)] predicted that the critical point in this system is of exotic infinite-randomness type and is accompanied by strong power-law Griffiths singularities. Here, we report results of Monte-Carlo simulations that provide numerical evidence in support of these predictions. Specifically, we investigate the finite-size scaling behavior of the magnetic susceptibility which is characterized by a non-universal power-law divergence in the Griffiths phase. In addition, we calculate the time autocorrelation function of the spins. It features a very slow …
Analysis Of Effects Of Macroscopic Propagation And Multiple Molecular Orbitals On The Minimum In High-Order Harmonic Generation Of Aligned Co₂, Cheng Jin, Anh-Thu Le, C. D. Lin
Analysis Of Effects Of Macroscopic Propagation And Multiple Molecular Orbitals On The Minimum In High-Order Harmonic Generation Of Aligned Co₂, Cheng Jin, Anh-Thu Le, C. D. Lin
Physics Faculty Research & Creative Works
We report theoretical calculations of the effect of the multiple-orbital contribution in high-order harmonic generation (HHG) of aligned CO₂ with the inclusion of macroscopic propagation of harmonic fields in the medium. Our results show very good agreement with recent experiments for the dynamics of the minimum in HHG spectra as laser intensity or alignment angle changes. Calculations are carried out to check how the position of the minimum in HHG spectra depends on the degrees of molecular alignment, laser-focusing conditions, and the effects of alignment-dependent ionization rates of the different molecular orbitals. These analyses help to explain why the minima …
Self-Energy Correction To The Hyperfine Splitting For Excited States, Benedikt J. Wundt, Ulrich D. Jentschura
Self-Energy Correction To The Hyperfine Splitting For Excited States, Benedikt J. Wundt, Ulrich D. Jentschura
Physics Faculty Research & Creative Works
The self-energy corrections to the hyperfine splitting is evaluated for higher excited states in hydrogenlike ions using an expansion in the binding parameter Zα, where Z is the nuclear-charge number and α is the fine-structure constant. We present analytic results for D, F, and G states, and for a number of highly excited Rydberg states, with principal quantum numbers in the range 13≤n≤16, and orbital angular momenta =n-2 and =n-1. A closed-form analytic expression is derived for the contribution of high-energy photons, valid for any state with ≥2 and arbitrary n, , and total angular momentum j. The low-energy contributions …
Forecasting The Cosmological Constraints With Anisotropic Baryon Acoustic Oscillations From Multipole Expansion, Atsushi Taruya, Shun Saito, Takahiro Nishimichi
Forecasting The Cosmological Constraints With Anisotropic Baryon Acoustic Oscillations From Multipole Expansion, Atsushi Taruya, Shun Saito, Takahiro Nishimichi
Physics Faculty Research & Creative Works
Baryon acoustic oscillations imprinted in the galaxy power spectrum can be used as a standard ruler to determine the angular diameter distance and Hubble parameter from high-redshift galaxies. Combining redshift distortion effect which apparently distorts the galaxy clustering pattern, we can also constrain the growth rate of large-scale structure formation. Usually, future forecasts for constraining these parameters from galaxy redshift surveys are made with the full 2D power spectrum characterized as a function of wave number k and directional cosine µ between line-of-sight direction and wave vector, i.e., P(k,µ). Here, we apply the multipole expansion to the full 2D power …
Relativistic Tight-Binding Model: Application To Pt Surfaces, Aleksandr V. Chernatynskiy, J. Woods Halley
Relativistic Tight-Binding Model: Application To Pt Surfaces, Aleksandr V. Chernatynskiy, J. Woods Halley
Physics Faculty Research & Creative Works
We report a parametrization of a previous self-consistent tight-binding model, suitable for metals with a high atomic number in which nonscalar-relativistic effects are significant in the electron physics of condensed phases. The method is applied to platinum. The model is fitted to density functional theory band structures and cohesive energies and spectroscopic data on platinum atoms in five oxidation states, and is then shown without further parametrization to correctly reproduce several low index surface structures. We also predict reconstructions of some vicinal surfaces.
Low Energy (E,2e) Studies From Ch₄: Results From Symmetric Coplanar Experiments And Molecular Three-Body Distorted Wave Theory, Kate L. Nixon, Andrew James Murray, Hari Chaluvadi, Chuangang Ning, Don H. Madison
Low Energy (E,2e) Studies From Ch₄: Results From Symmetric Coplanar Experiments And Molecular Three-Body Distorted Wave Theory, Kate L. Nixon, Andrew James Murray, Hari Chaluvadi, Chuangang Ning, Don H. Madison
Physics Faculty Research & Creative Works
Low energy experimental and theoretical triply differential cross sections are presented for electron impact ionization of methane (CH4) for both the highest occupied molecular orbital (HOMO) and next highest occupied molecular orbital (NHOMO). The HOMO is a predominantly p-type orbital which is labeled 1t2 and the NHOMO is predominantly s-type labeled 2a 1. Coplanar symmetric (symmetric both in final state electron energies and observation angles) are presented for final state electron energies ranging from 2.5 to 20 eV. The theoretical M3DW (molecular three-body distorted wave) results are in surprisingly good agreement with experiment for the HOMO …
Tracing The Redshift Evolution Of Hubble Parameter With Gravitational-Wave Standard Sirens, Atsushi J. Nishizawa, Atsushi Taruya, Shun Saito
Tracing The Redshift Evolution Of Hubble Parameter With Gravitational-Wave Standard Sirens, Atsushi J. Nishizawa, Atsushi Taruya, Shun Saito
Physics Faculty Research & Creative Works
Proposed space-based gravitational-wave detectors such as BBO and DECIGO can detect ~ 106 neutron star (NS) binaries and determine the luminosity distance to the binaries with high precision. Combining the luminosity distance and electromagnetically derived redshift, one would be able to probe cosmological expansion out to high redshift. In this paper, we show that the Hubble parameter as a function of redshift can be directly measured with monopole and dipole components of the luminosity distance on the sky. As a result, the measurement accuracies of the Hubble parameter in each redshift bin up to z=1 are 3-14%, 1.5-8%, and …
Hydrogen-Deuterium Isotope Shift: From The 1s-2s-Transition Frequency To The Proton-Deuteron Charge-Radius Difference, Ulrich D. Jentschura, Arthur N. Matveev, Christian G. Parthey, Janis Alnis, Randolf Pohl, Th H. Udem, Nikolai N. Kolachevsky, Theodor Wolfgang Hansch
Hydrogen-Deuterium Isotope Shift: From The 1s-2s-Transition Frequency To The Proton-Deuteron Charge-Radius Difference, Ulrich D. Jentschura, Arthur N. Matveev, Christian G. Parthey, Janis Alnis, Randolf Pohl, Th H. Udem, Nikolai N. Kolachevsky, Theodor Wolfgang Hansch
Physics Faculty Research & Creative Works
We analyze and review the theory of the hydrogen-deuterium isotope shift for the 1S-2S transition, which is one of the most accurately measured isotope shifts in any atomic system, in view of a recently improved experiment. A tabulation of all physical effects that contribute to the isotope shift is given. These include the Dirac binding energy, quantum electrodynamic effects, including recoil corrections, and the nuclear-size effect, including the pertaining relativistic and radiative corrections. From a comparison of the theoretical result Δfth=670999566.90(66)(60)kHz (exclusive of the nonrelativistic nuclear-finite-size correction) and the experimental result Δfexpt=670994334605(15) Hz, we infer the …
Manipulating Atomic Fragmentation Processes By Controlling The Projectile Coherence, Kisra N. Egodapitiya, Sachin D. Sharma, Ahmad Hasan, Aaron C. Laforge, Don H. Madison, Robert Moshammer, Michael Schulz
Manipulating Atomic Fragmentation Processes By Controlling The Projectile Coherence, Kisra N. Egodapitiya, Sachin D. Sharma, Ahmad Hasan, Aaron C. Laforge, Don H. Madison, Robert Moshammer, Michael Schulz
Physics Faculty Research & Creative Works
We have measured the scattering angle dependence of cross sections for ionization in p+H2 collisions for a fixed projectile energy loss. Depending on the projectile coherence, interference due to indistinguishable diffraction of the projectile from the two atomic centers was either present or absent in the data. This shows that, due to the fundamentals of quantum mechanics, the preparation of the beam must be included in theoretical calculations. The results have far-reaching implications on formal atomic scattering theory because this critical aspect has been overlooked for several decades.
Blackbody-Radiation Correction To The Polarizability Of Helium, Mariusz Puchalski, Ulrich D. Jentschura, Peter J. Mohr
Blackbody-Radiation Correction To The Polarizability Of Helium, Mariusz Puchalski, Ulrich D. Jentschura, Peter J. Mohr
Physics Faculty Research & Creative Works
The correction to the polarizability of helium due to blackbody radiation is calculated near room temperature. A precise theoretical determination of the blackbody radiation correction to the polarizability of helium is essential for dielectric gas thermometry and for the determination of the Boltzmann constant. We find that the correction, for not too high temperature, is roughly proportional to a modified hyperpolarizability (two-color hyperpolarizability), which is different from the ordinary hyperpolarizability of helium. Our explicit calculations provide a definite numerical result for the effect and indicate that the effect of blackbody radiation can be excluded as a limiting factor for dielectric …
Neutron Diffraction Studies On The Heusler Alloy Ni50mn 37sb13, N. V. Rama Rao, J. Arout Chelvane, V. Chandrasekaran, A. V. Morozkin, J. Lamsal, William B. Yelon, R. Nirmala, K. G. Suresh, S. K. Malik
Neutron Diffraction Studies On The Heusler Alloy Ni50mn 37sb13, N. V. Rama Rao, J. Arout Chelvane, V. Chandrasekaran, A. V. Morozkin, J. Lamsal, William B. Yelon, R. Nirmala, K. G. Suresh, S. K. Malik
Physics Faculty Research & Creative Works
The evolution of martensitic to austenitic transformation in Ni50Mn37Sb13 has been studied using temperature dependent neutron diffraction, thermal property, and magnetization studies. Differential scanning calorimetric studies reveal a martensitic transformation TM around 291 K. the magnetization data yield a ferromagnetic ordering temperature of 329 K in the austenitic phase and 230 K in the martensitic phase. the analysis of the powder neutron diffraction data in the temperature range of 325-12 K indicates a structural transition from a high temperature cubic L21 type structure to an orthorhombic structure. at 270 K, both cubic and orthorhombic phases …
Magnetization And Neutron Diffraction Studies On Sr2timno 6, Jagat Lamsal, Rajib Mondal, Anil Kumar, K. Kamala Bharathi, P. N. Santhosh, R. Nirmala, A. K. Nigam, William B. Yelon, S. Quezado, S. K. Malik
Magnetization And Neutron Diffraction Studies On Sr2timno 6, Jagat Lamsal, Rajib Mondal, Anil Kumar, K. Kamala Bharathi, P. N. Santhosh, R. Nirmala, A. K. Nigam, William B. Yelon, S. Quezado, S. K. Malik
Physics Faculty Research & Creative Works
Magnetic properties of the double perovskite oxide, Sr2TiMnO6, have been studied by means of bulk magnetization and powder neutron diffraction experiments. Low field magnetization data reveal transitions at ∼45 K (TC) and at ∼15 K (TN). a magnetic moment value of only ∼0.23 BF.U. is attained at 5 K in the 7 T field. Powder neutron diffraction studies suggest the possible antiferromagnetic order in this compound at 12 K with moments of ∼0.5 B at the Mn site. © 2011 American Institute of Physics.
Competing Magnetic Interactions In The Intermetallic Compounds Pr 5ge3 And Nd5ge3, R. Nirmala, A. V. Morozkin, A. K. Nigam, Jagat Lamsal, W. B. Yelon, O. Isnard, S. A. Granovsky, K. Kamala Bharathi, S. Quezado, S. K. Malik
Competing Magnetic Interactions In The Intermetallic Compounds Pr 5ge3 And Nd5ge3, R. Nirmala, A. V. Morozkin, A. K. Nigam, Jagat Lamsal, W. B. Yelon, O. Isnard, S. A. Granovsky, K. Kamala Bharathi, S. Quezado, S. K. Malik
Physics Faculty Research & Creative Works
Magnetic properties of polycrystalline Pr5Ge3 and Nd5Ge3 (hexagonal, Mn5Si3-type) compounds have been studied. Magnetization measurements in 0.5 T field indicate that the Pr5Ge3 orders antiferromagnetically at 18 K (TN). However, in an applied field of 10 mT, the zero-field-cooled and field-cooled magnetization bifurcates below ∼65 K. This and the positive paramagnetic Curie temperature, obtained from the Curie-Weiss fit to the paramagnetic susceptibility, suggest the presence of competing ferromagnetic and antiferromagnetic interactions. the magnetization versus field isotherm at 5 K shows an S-shaped curve and a weak tendency …
X-Ray Emission Cross Sections Following Ar18⁺ Charge-Exchange Collisions On Neutral Argon: The Role Of The Multiple Electron Capture, Sebastian Otranto, Ronald E. Olson
X-Ray Emission Cross Sections Following Ar18⁺ Charge-Exchange Collisions On Neutral Argon: The Role Of The Multiple Electron Capture, Sebastian Otranto, Ronald E. Olson
Physics Faculty Research & Creative Works
X-ray emission originating in charge-exchange collisions between Ar18+ and neutral argon is studied at impact energies of 5-4000 eV/amu by means of the classical trajectory Monte Carlo method (CTMC). Line emission and charge-exchange cross sections obtained from different CTMC versions based on the one-active electron approximation are contrasted among themselves and against the results obtained by means of a three-active electron code that lets us infer the role of multiple electron capture. the present results are compared to the recent experimental data available from the EBIT groups operating at Livermore, NIST, and Berlin. We were not able to reconcile …
Compton Upconversion Of Twisted Photons: Backscattering Of Particles With Non-Planar Wave Functions, Ulrich D. Jentschura, Valery G. Serbo
Compton Upconversion Of Twisted Photons: Backscattering Of Particles With Non-Planar Wave Functions, Ulrich D. Jentschura, Valery G. Serbo
Physics Faculty Research & Creative Works
Twisted photons are not plane waves, but superpositions of plane waves with a defined projection hm of the orbital angular momentum onto the propagation axis (m is integer and may attain values m≫ 1). Here, we describe in detail the possibility to produce high-energy twisted photons by backward Compton scattering of twisted laser photons on ultra-relativistic electrons with a Lorentz-factor γ=E/(mec2)≫ 1. When a twisted laser photon with the energy hω~1 eV performs a collision with an electron and scatters backward, the final twisted photon conserves the angular momentum m, but its energy hω' is increased …
Differential Cross Sections For Single Ionization Of H₂ By 75-Kev Proton Impact, Uttam Chowdhury, Michael Schulz, Don H. Madison
Differential Cross Sections For Single Ionization Of H₂ By 75-Kev Proton Impact, Uttam Chowdhury, Michael Schulz, Don H. Madison
Physics Faculty Research & Creative Works
We have calculated triply differential cross sections (TDCS) and doubly differential cross sections (DDCS) for single ionization of H2 by 75-keV proton impact using the molecular three-body distorted-wave-eikonal initial-state (M3DW-EIS) approach. Previously published measured DDCS (differential in the projectile scattering angle and integrated over the ejected electron angles) found pronounced structures at relatively large angles that were interpreted as an interference resulting from the two-centered potential of the molecule. Theory treating H2 as atomic H multiplied by a molecular interference factor only predicts the observed structure when assumptions are made about the molecular orientation. Here we apply the …