Open Access. Powered by Scholars. Published by Universities.®
Physical Sciences and Mathematics Commons™
Open Access. Powered by Scholars. Published by Universities.®
- Discipline
-
- Physics (1742)
- Chemistry (77)
- Computer Sciences (44)
- Numerical Analysis and Scientific Computing (44)
- Engineering (19)
-
- Materials Science and Engineering (10)
- Astrophysics and Astronomy (6)
- Metallurgy (5)
- Aerospace Engineering (4)
- Mechanical Engineering (4)
- Social and Behavioral Sciences (3)
- Earth Sciences (2)
- Geology (2)
- Psychology (2)
- Biochemical and Biomolecular Engineering (1)
- Chemical Engineering (1)
- Civil and Environmental Engineering (1)
- Electrical and Computer Engineering (1)
- Library and Information Science (1)
- Nuclear Engineering (1)
- Keyword
-
- Ionization (58)
- Electrons (42)
- Quantum Theory (42)
- Helium (36)
- Atoms (34)
-
- Hydrogen (34)
- Electrodynamics (32)
- Gravitational waves (31)
- Gravity waves (29)
- Molecules (29)
- Gravitational effects (28)
- Photons (28)
- Impact ionization (25)
- Atomic physics (22)
- Gravitation (21)
- Impact Ionization (19)
- Quantum theory (19)
- Electron Energy Levels (18)
- Atomic Physics (17)
- Photoionization (17)
- Stars (17)
- Ions (16)
- Mathematical models (16)
- Projectiles (16)
- Electron impact-ionization (15)
- Hamiltonians (15)
- Polarization (15)
- Quantum Electrodynamics (15)
- Electron energy levels (14)
- Gravitational-wave signals (14)
- Publication Year
Articles 721 - 750 of 1762
Full-Text Articles in Physical Sciences and Mathematics
Nonlinear Power Spectrum In The Presence Of Massive Neutrinos: Perturbation Theory Approach, Galaxy Bias, And Parameter Forecasts, Shun Saito, Masahiro Takada, Atsushi Taruya
Nonlinear Power Spectrum In The Presence Of Massive Neutrinos: Perturbation Theory Approach, Galaxy Bias, And Parameter Forecasts, Shun Saito, Masahiro Takada, Atsushi Taruya
Physics Faculty Research & Creative Works
Future or ongoing galaxy redshift surveys can put stringent constraints on neutrinos masses via the high-precision measurements of galaxy power spectrum, when combined with CMB information. In this paper we develop a method to model galaxy power spectrum in the weakly nonlinear regime for a mixed dark matter [cold dark matter (CDM) plus finite-mass neutrinos] model, based on perturbation theory (PT) whose validity is well tested by simulations for a CDM model. In doing this we carefully study various aspects of the nonlinear clustering (nonlinear neutrino perturbations and the higher-order growth functions), and then arrive at a useful approximation allowing …
Nonperturbative Treatment Of Double Compton Backscattering In Intense Laser Fields, Erik Lotstedt, Ulrich D. Jentschura
Nonperturbative Treatment Of Double Compton Backscattering In Intense Laser Fields, Erik Lotstedt, Ulrich D. Jentschura
Physics Faculty Research & Creative Works
The emission of a pair of entangled photons by an electron in an intense laser field can be described by two-photon transitions of laser-dressed, relativistic Dirac-Volkov states. In the limit of a small laser field intensity, the two-photon transition amplitude approaches the result predicted by double Compton scattering theory. Multiexchange processes with the laser field, including a large number of exchanged laser photons, cannot be described without the fully relativistic Dirac-Volkov propagator. The nonperturbative treatment significantly alters theoretical predictions for future experiments of this kind. We quantify the degree of polarization correlation of the photons in the final state by …
On The Transition Rate Of The Fe X Red Coronal Line, Gunter Brenner, Jose R. Crespo Lopez-Urrutia, Sven Bernitt, Daniel Fischer, Rainer Ginzel, Kai Uwe Kuhnel, Volkhard Mackel, Paul H. Mokler, Martin C. Simon, Joachim Hermann Ullrich
On The Transition Rate Of The Fe X Red Coronal Line, Gunter Brenner, Jose R. Crespo Lopez-Urrutia, Sven Bernitt, Daniel Fischer, Rainer Ginzel, Kai Uwe Kuhnel, Volkhard Mackel, Paul H. Mokler, Martin C. Simon, Joachim Hermann Ullrich
Physics Faculty Research & Creative Works
We present a lifetime measurement of the 3s 23p 5 2 Po 1/2 first excited fine-structure level of the ground state configuration in chlorine-like Fe X, which relaxes to the ground state through a magnetic dipole (M1) transition (the so-called red coronal line) with a wavelength accurately determined to 637.454(1) nm. Moreover, the Zeeman splitting of line was observed. The lifetime of 14.2(2) ms is the most precise one measured in the red wavelength region and agrees well with advanced theoretical predictions and an empirically scaled interpolation based on experimental values from the same isoelectronic sequence.
First Ligo Search For Gravitational Wave Bursts From Cosmic (Super)Strings, Benjamin P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
First Ligo Search For Gravitational Wave Bursts From Cosmic (Super)Strings, Benjamin P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Physics Faculty Research & Creative Works
We report on a matched-filter search for gravitational wave bursts from cosmic string cusps using LIGO data from the fourth science run (S4) which took place in February and March 2005. No gravitational waves were detected in 14.9 days of data from times when all three LIGO detectors were operating. We interpret the result in terms of a frequentist upper limit on the rate of gravitational wave bursts and use the limits on the rate to constrain the parameter space (string tension, reconnection probability, and loop sizes) of cosmic string models. Many grand unified theory-scale models (with string tension Gμ/c …
Search For Gravitational Wave Ringdowns From Perturbed Black Holes In Ligo S4 Data, Benjamin P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Search For Gravitational Wave Ringdowns From Perturbed Black Holes In Ligo S4 Data, Benjamin P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Physics Faculty Research & Creative Works
According to general relativity a perturbed black hole will settle to a stationary configuration by the emission of gravitational radiation. Such a perturbation will occur, for example, in the coalescence of a black hole binary, following their inspiral and subsequent merger. At late times the waveform is a superposition of quasinormal modes, which we refer to as the ringdown. The dominant mode is expected to be the fundamental mode, l = m = 2. Since this is a well-known waveform, matched filtering can be implemented to search for this signal using LIGO data. We present a search for gravitational waves …
Beam Lifetimes And Ionization Cross Sections Of U28+, G. Weber, C. Omet, Robert D. Dubois, O. De Lucio, Th Stöhlker, C. Brandau, A. Gumberidze, S. Hagmann, S. Hess, C. Kozhuharov, R. Reuschl, P. Spiller, U. Spillmann, M. Steck
Beam Lifetimes And Ionization Cross Sections Of U28+, G. Weber, C. Omet, Robert D. Dubois, O. De Lucio, Th Stöhlker, C. Brandau, A. Gumberidze, S. Hagmann, S. Hess, C. Kozhuharov, R. Reuschl, P. Spiller, U. Spillmann, M. Steck
Physics Faculty Research & Creative Works
Beam lifetimes of stored U28+ ions with energies between 10 and 180MeV/u were measured in the heavy ion synchrotron SIS18 and in the experimental storage ring (ESR) of the GSI accelerator facility. by using the internal gas jet target of the ESR, it was possible to obtain projectile ionization cross sections for collisions with H2 and N2 from the lifetime data. the experimental cross sections are compared to theoretical data predicted by the n-body classical-trajectory Monte Carlo (CTMC) method of Olson etal. and to calculations of Shevelko etal. using the LOSS-R code. in addition, both theoretical approaches …
Einstein@Home Search For Periodic Gravitational Waves In Early S5 Ligo Data, Benjamin P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Einstein@Home Search For Periodic Gravitational Waves In Early S5 Ligo Data, Benjamin P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Physics Faculty Research & Creative Works
This paper reports on an all-sky search for periodic gravitational waves from sources such as deformed isolated rapidly spinning neutron stars. The analysis uses 840 hours of data from 66 days of the fifth LIGO science run (S5). The data were searched for quasimonochromatic waves with frequencies f in the range from 50 to 1500 Hz, with a linear frequency drift ḟ (measured at the solar system barycenter) in the range -f/τ < ḟ < 0.1f/τ, for a minimum spin-down age τ of 1000 years for signals below 400 Hz and 8000 years above 400 Hz. The main computational work …
Search For Gravitational Waves From Low Mass Compact Binary Coalescence In 186 Days Of Ligo's Fifth Science Run, Benjamin P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Search For Gravitational Waves From Low Mass Compact Binary Coalescence In 186 Days Of Ligo's Fifth Science Run, Benjamin P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Physics Faculty Research & Creative Works
We report on a search for gravitational waves from coalescing compact binaries, of total mass between 2 and 35M⊙, using LIGO observations between November 14, 2006 and May 18, 2007. No gravitational-wave signals were detected. We report upper limits on the rate of compact binary coalescence as a function of total mass. The LIGO cumulative 90%-confidence rate upper limits of the binary coalescence of neutron stars, black holes and black hole-neutron star systems are 1.4x10-2, 7.3x10-4 and 3.6x10yr-1L10-1, respectively, where L10 is 1010 times the blue solar …
Relativistic (Zα)2 Corrections And Leading Quantum Electrodynamic Corrections To The Two-Photon Decay Rate Of Ionic States, Benedikt J. Wundt, Ulrich D. Jentschura
Relativistic (Zα)2 Corrections And Leading Quantum Electrodynamic Corrections To The Two-Photon Decay Rate Of Ionic States, Benedikt J. Wundt, Ulrich D. Jentschura
Physics Faculty Research & Creative Works
We calculate the relativistic corrections of relative order (Zα) 2 to the two-photon decay rate of higher excited S and D states in ionic atomic systems, and we also evaluate the leading radiative corrections of relative order α (Zα) 2 ln [(Zα) -2]. We thus complete the theory of the two-photon decay rates up to relative order α3 ln (α). An approach inspired by nonrelativistic quantum electrodynamics is used. We find that the corrections of relative order (Zα) 2 to the two-photon decay are given by the Zitterbewegung, by the spin-orbit coupling and by relativistic corrections to the electron mass, …
Light-Particle Single Ionization Of Argon: Influence Of The Projectile Charge Sign, Sebastian Otranto, Ronald E. Olson
Light-Particle Single Ionization Of Argon: Influence Of The Projectile Charge Sign, Sebastian Otranto, Ronald E. Olson
Physics Faculty Research & Creative Works
The ionization of the 3p orbital of argon by incident electrons and positrons is studied by means of the post version of the continuum distorted wave-eikonal initial-state model. Results are presented at both 200 and 500 eV impact energies for conditions amenable to present experiments. Differences in the fully differential cross sections (FDCSs) are analyzed and the influence of the projectile charge sign on the emission dynamics is discussed. The FDCSs are found to display the classic binary plus recoil peak structure at 500 eV, but transition to a more complicated four-lobed structure at the lower impact energy.
Thermal Expansion And Grüneisen Parameter In Quantum Griffiths Phases, Thomas Vojta
Thermal Expansion And Grüneisen Parameter In Quantum Griffiths Phases, Thomas Vojta
Physics Faculty Research & Creative Works
We consider the behavior of the Grüneisen parameter, the ratio between thermal expansion and specific heat, at pressure-tuned infinite-randomness quantum-critical points and in the associated quantum Griffiths phases. We find that the Grüneisen parameter diverges as ln (T0 /T) with vanishing temperature T in the quantum Griffiths phases. at the infinite-randomness critical point itself, the Grüneisen parameter behaves as [ln (T0 /T)]1+1/ (νψ) where ν and ψ are the correlation length and tunneling exponents. Analogous results hold for the magnetocaloric effect at magnetic-field-tuned transitions. We contrast clean and dirty systems, we discuss subtle differences between Ising and …
Quantitative Rescattering Theory For High-Order Harmonic Generation From Molecules, Anh-Thu Le, R. R. Lucchese, S. Tonzani, Toru Morishita, C. D. Lin
Quantitative Rescattering Theory For High-Order Harmonic Generation From Molecules, Anh-Thu Le, R. R. Lucchese, S. Tonzani, Toru Morishita, C. D. Lin
Physics Faculty Research & Creative Works
The quantitative rescattering theory (QRS) for high-order harmonic generation (HHG) by intense laser pulses is presented. According to the QRS, HHG spectra can be expressed as a product of a returning electron wave packet and the photorecombination differential cross section of the laser-free continuum electron back to the initial bound state. We show that the shape of the returning electron wave packet is determined mostly by the laser. The returning electron wave packets can be obtained from the strong-field approximation or from the solution of the time-dependent Schrödinger equation (TDSE) for a reference atom. The validity of the QRS is …
Simulations Of Baryon Acoustic Oscillations. Ii. Covariance Matrix Of The Matter Power Spectrum, Ryuichi Takahashi, Naoki Yoshida, Masahiro Takada, Takahiko Matsubara, Naoshi Sugiyama, Issha Kayo, Atsushi J. Nishizawa, Takahiro Nishimichi, Shun Saito, Atsushi Taruya
Simulations Of Baryon Acoustic Oscillations. Ii. Covariance Matrix Of The Matter Power Spectrum, Ryuichi Takahashi, Naoki Yoshida, Masahiro Takada, Takahiko Matsubara, Naoshi Sugiyama, Issha Kayo, Atsushi J. Nishizawa, Takahiro Nishimichi, Shun Saito, Atsushi Taruya
Physics Faculty Research & Creative Works
We use 5000 cosmological N-body simulations of 1 h-3 Gpc3 box for the concordance ËCDM model in order to study the sampling variances of a nonlinear matter power spectrum. We show that the non-Gaussian errors can be important even on large length scales relevant for baryon acoustic oscillations (BAOs). Our findings are the following: (1) the non-Gaussian errors degrade the cumulative signal-to-noise ratios (S/Ns) for the power spectrum amplitude by up to a factor of 2 and 4 for redshifts z = 1 and 0, respectively; (2) there is little information on the power spectrum amplitudes in the …
Stacked Search For Gravitational Waves From The 2006 Sgr 1900+14 Storm, Benjamin P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Stacked Search For Gravitational Waves From The 2006 Sgr 1900+14 Storm, 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 LIGO search for short-duration gravitational waves (GWs) associated with the 2006 March 29 SGR 1900+14 storm. A new search method is used, "stacking" the GW data around the times of individual soft-gamma bursts in the storm to enhance sensitivity for models in which multiple bursts are accompanied by GW emission. We assume that variation in the time difference between burst electromagnetic emission and potential burst GW emission is small relative to the GW signal duration, and we time-align GW excess power time-frequency tilings containing individual burst triggers to their corresponding electromagnetic emissions. We use …
String Resonances At The Large Hadron Collider, Arunava Roy, Marco Cavaglia
String Resonances At The Large Hadron Collider, Arunava Roy, Marco Cavaglia
Physics Faculty Research & Creative Works
The Large Hadron Collider promises to discover new physics beyond the standard model. An exciting possibility is the formation of string resonances at the TeV scale. In this article, we show how string resonances may be detected at the LHC in the pp →γ + jet channel. Our study is based on event-shape variables, missing energy and momentum, maximum transverse momentum of photons and dijet invariant mass. These observables provide interesting signatures which enable us to discriminate string events from the standard model background.
Accurate Retrieval Of Atomic Structures From High-Order Harmonic Spectra, Toshihito Umegaki, Toru Morishita, Shinichiro Minemoto, Yuichiro Oguchi, Anh-Thu Le, Shinichi Watanabe, Hirofumi Sakai
Accurate Retrieval Of Atomic Structures From High-Order Harmonic Spectra, Toshihito Umegaki, Toru Morishita, Shinichiro Minemoto, Yuichiro Oguchi, Anh-Thu Le, Shinichi Watanabe, Hirofumi Sakai
Physics Faculty Research & Creative Works
We extracted the photorecombination cross sections from the high-order harmonic spectra generated from rare gases by intense femtosecond pulses. By taking the ratio between the observed high-order harmonic spectra and recolliding electron wave packets, we successfully obtained the photorecombination cross sections.
Three-Body Dynamics In Single Ionization Of Atomic Hydrogen By 75 Kev Proton Impact, Ahmad Hasan, Michael Schulz, Aaron C. Laforge, Jason S. Alexander, M. F. Ciappina, M. A. Khakoo, Kisra Nayomal Egodapitiya
Three-Body Dynamics In Single Ionization Of Atomic Hydrogen By 75 Kev Proton Impact, Ahmad Hasan, Michael Schulz, Aaron C. Laforge, Jason S. Alexander, M. F. Ciappina, M. A. Khakoo, Kisra Nayomal Egodapitiya
Physics Faculty Research & Creative Works
Doubly differential cross sections for single ionization of atomic hydrogen by 75 keV proton impact have been measured and calculated as a function of the projectile scattering angle and energy loss. This pure three-body collision system represents a fundamental test case for the study of the reaction dynamics in few-body systems. A comparison between theory and experiment reveals that three-body dynamics is important at all scattering angles and that an accurate description of the role of the projectile-target-nucleus interaction remains a major challenge to theory.
Search For Gravitational Waves From Low Mass Binary Coalescences In The First Year Of Ligo's S5 Data, Benjamin P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Search For Gravitational Waves From Low Mass Binary Coalescences In The First Year Of Ligo's S5 Data, Benjamin P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Physics Faculty Research & Creative Works
We have searched for gravitational waves from coalescing low mass compact binary systems with a total mass between 2M⊙ and 35M⊙ and a minimum component mass of 1M⊙ using data from the first year of the fifth science run of the three LIGO detectors, operating at design sensitivity. Depending on the mass, we are sensitive to coalescences as far as 150 Mpc from the Earth. No gravitational-wave signals were observed above the expected background. Assuming a population of compact binary objects with a Gaussian mass distribution representing binary neutron star systems, black hole-neutron star …
Treatment Of Ion-Atom Collisions Using A Partial-Wave Expansion Of The Projectile Wavefunction, T. G. Wong, M. Foster, J. Colgan, Don H. Madison
Treatment Of Ion-Atom Collisions Using A Partial-Wave Expansion Of The Projectile Wavefunction, T. G. Wong, M. Foster, J. Colgan, Don H. Madison
Physics Faculty Research & Creative Works
We present calculations of ion-atom collisions using a partial-wave expansion of the projectile wavefunction. Most calculations of ion-atom collisions have typically used classical or plane-wave approximations for the projectile wavefunction, since partial-wave expansions are expected to require prohibitively large numbers of terms to converge scattering quantities. Here we show that such calculations are possible using modern high-performance computing. We demonstrate the utility of our method by examining elastic scattering of protons by hydrogen and helium atoms, problems familiar to undergraduate students of atomic scattering. Application to ionization of helium using partial-wave expansions of the projectile wavefunction, which has long been …
Feasibility Of Coherent Xuv Spectroscopy On The 1s-2s Transition In Singly Ionized Helium, Maximilian Herrmann, Martin K. Haas, Ulrich D. Jentschura, Franz Kottmann, Dietrich Leibfried, Guido Saathoff, Christoph Gohle, Akira Ozawa, V. Batteiger, S. Knunz, Nikolai N. Kolachevsky, H. A. Schussler, Theodor Wolfgang Hansch, Th H. Udem
Feasibility Of Coherent Xuv Spectroscopy On The 1s-2s Transition In Singly Ionized Helium, Maximilian Herrmann, Martin K. Haas, Ulrich D. Jentschura, Franz Kottmann, Dietrich Leibfried, Guido Saathoff, Christoph Gohle, Akira Ozawa, V. Batteiger, S. Knunz, Nikolai N. Kolachevsky, H. A. Schussler, Theodor Wolfgang Hansch, Th H. Udem
Physics Faculty Research & Creative Works
The 1S-2S two-photon transition in singly ionized helium is a highly interesting candidate for precision tests of bound-state quantum electrodynamics (QED). With the recent advent of extreme ultraviolet frequency combs, highly coherent quasi-continuous-wave light sources at 61 nm have become available, and precision spectroscopy of this transition now comes into reach for the first time. We discuss quantitatively the feasibility of such an experiment by analyzing excitation and ionization rates, propose an experimental scheme, and explore the potential for QED tests.
Probing Molecular Frame Photoionization Via Laser Generated High-Order Harmonics From Aligned Molecules, Anh-Thu Le, R. R. Lucchese, M. T. Lee, C. D. Lin
Probing Molecular Frame Photoionization Via Laser Generated High-Order Harmonics From Aligned Molecules, Anh-Thu Le, R. R. Lucchese, M. T. Lee, C. D. Lin
Physics Faculty Research & Creative Works
Present experiments cannot measure molecular frame photoelectron angular distributions (MFPAD) for ionization from the outermost valence orbitals of molecules. We show that the details of MFPAD can be retrieved with high-order harmonics generated by infrared lasers from aligned molecules. Using accurately calculated photoionization transition dipole moments for fixed-in-space molecules, we show that the dependence of the magnitude and phase of the high-order harmonics on the alignment angle of the molecules observed in recent experiments can be quantitatively reproduced. This result provides the needed theoretical basis for ultrafast dynamic chemical imaging using infrared laser pulses.
Retrieval Of Target Photorecombination Cross Sections From High-Order Harmonics Generated In A Macroscopic Medium, Cheng Jin, Anh-Thu Le, C. D. Lin
Retrieval Of Target Photorecombination Cross Sections From High-Order Harmonics Generated In A Macroscopic Medium, Cheng Jin, Anh-Thu Le, C. D. Lin
Physics Faculty Research & Creative Works
We investigate high-order harmonic generation (HHG) in a thin macroscopic medium by solving Maxwell's equation using microscopic single-atom induced dipole moment calculated from the recently developed quantitative rescattering (QRS) theory. We show that macroscopic HHG yields calculated from QRS compared well with those obtained from solving the single-atom time-dependent Schrödinger equation but with great saving of computer time. We also show that macroscopic HHG can be expressed as a product of a "macroscopic wave packet" and the photorecombination cross section of the target gas. The latter enables us to extract target structure from the experimentally measured HHG spectra, thus paves …
Absorbing-State Phase Transitions On Percolating Lattices, Man Young Lee, Thomas Vojta
Absorbing-State Phase Transitions On Percolating Lattices, Man Young Lee, Thomas Vojta
Physics Faculty Research & Creative Works
We study nonequilibrium phase transitions of reaction-diffusion systems defined on randomly diluted lattices, focusing on the transition across the lattice percolation threshold. To develop a theory for this transition, we combine classical percolation theory with the properties of the supercritical nonequilibrium system on a finite-size cluster. In the case of the contact process, the interplay between geometric criticality due to percolation and dynamical fluctuations of the nonequilibrium system leads to a different universality class. The critical point is characterized by ultraslow activated dynamical scaling and accompanied by strong Griffiths singularities. To confirm the universality of this exotic scaling scenario we …
Binding Two-Loop Vacuum-Polarization Corrections To The Bound-Electron G Factor, Ulrich D. Jentschura
Binding Two-Loop Vacuum-Polarization Corrections To The Bound-Electron G Factor, Ulrich D. Jentschura
Physics Faculty Research & Creative Works
We commence the evaluation of the one- and two-loop binding corrections to the g factor for an electron in a hydrogenlike system of order alpha2(Zalpha)5 and consider diagrams with closed fermion loops. The one-loop vacuum-polarization correction is rederived and confirmed. For the two-loop vacuum-polarization correction, due to a specific gauge-invariant set of diagrams with closed fermion loops, we find a correction deltag=7.442(alpha/pi)2(Zalpha)5. Based on the numerical trend of the coefficients inferred from the gauge-invariant subset, we obtain a numerically large tentative estimate for the complete two-loop binding correction to the g factor (sum of self-energy and vacuum polarization).
Two-Center Double-Capture Interference In Fast H E²⁺+ H₂ Collisions, Deepankar S. Misra, Henning T. Schmidt, M. Gudmundsson, Daniel Fischer, Nicole Haag, Henrik A B Johansson, Anders Kallberg, B. Najjari, Peter Reinhed, Reinhold S. Schuch, Markus S. Schoffler, Ansgar Simonsson, Alexander B. Voitkiv, Henrik Cederquist
Two-Center Double-Capture Interference In Fast H E²⁺+ H₂ Collisions, Deepankar S. Misra, Henning T. Schmidt, M. Gudmundsson, Daniel Fischer, Nicole Haag, Henrik A B Johansson, Anders Kallberg, B. Najjari, Peter Reinhed, Reinhold S. Schuch, Markus S. Schoffler, Ansgar Simonsson, Alexander B. Voitkiv, Henrik Cederquist
Physics Faculty Research & Creative Works
We report the first observation of Young-type interference effects in a two-electron transfer process. These effects change strongly as the projectile velocity changes in fast (1.2 and 2.0 MeV) He2++H2 collisions as manifested in strong variations of the double-electron capture rates with the H2 orientation. This is consistent with fully quantum mechanical calculations, which ignore sequential electron transfer, and a simple projectile de Broglie wave picture assuming that two-electron transfer probabilities are higher in collisions where the projectile passes close to either one of the H2 nuclei.
Role Of Elastic Projectile-Electron Scattering In Double Ionization Of Helium By Fast Proton Impact, Michael Schulz, M. F. Ciappina, T. Kirchner, Daniel Fischer, R. Moshammer, J. D. Ullrich
Role Of Elastic Projectile-Electron Scattering In Double Ionization Of Helium By Fast Proton Impact, Michael Schulz, M. F. Ciappina, T. Kirchner, Daniel Fischer, R. Moshammer, J. D. Ullrich
Physics Faculty Research & Creative Works
We present a systematic study of atomic four-body fragmentation dynamics. To this end we have measured a variety of multiple differential double ionization cross sections for 6 MeV p+He collisions. The data are compared to a first-order calculation with correlated electrons and to a simulation representing a second-order process, with some experimental results seemingly in favor of the first, others in agreement with the second approach. This apparent conflict can be resolved by accounting for elastic scattering between the projectile and one electron already promoted to the continuum through electron-electron correlation in the first-order process.
Quantitative Rescattering Theory For Laser-Induced High-Energy Plateau Photoelectron Spectra, Zhangjin Chen, Anh-Thu Le, Toru Morishita, C. D. Lin
Quantitative Rescattering Theory For Laser-Induced High-Energy Plateau Photoelectron Spectra, Zhangjin Chen, Anh-Thu Le, Toru Morishita, C. D. Lin
Physics Faculty Research & Creative Works
A comprehensive quantitative rescattering (QRS) theory for describing the production of high-energy photoelectrons generated by intense laser pulses is presented. According to the QRS, the momentum distributions of these electrons can be expressed as the product of a returning electron wave packet with the elastic differential cross sections (DCS) between free electrons with the target ion. We show that the returning electron wave packets are determined mostly by the lasers only and can be obtained from the strong field approximation. The validity of the QRS model is carefully examined by checking against accurate results from the solution of the time-dependent …
All-Sky Ligo Search For Periodic Gravitational Waves In The Early Fifth-Science-Run Data, Benjamin P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
All-Sky Ligo Search For Periodic Gravitational Waves In The Early Fifth-Science-Run 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 with the LIGO detectors for periodic gravitational waves in the frequency range 50-1100Hz and with the frequency's time derivative in the range -5x10-9-0Hzs-1. Data from the first eight months of the fifth LIGO science run (S5) have been used in this search, which is based on a semicoherent method (PowerFlux) of summing strain power. Observing no evidence of periodic gravitational radiation, we report 95% confidence-level upper limits on radiation emitted by any unknown isolated rotating neutron stars within the search range. Strain limits below 10-24 are obtained over a …
Magnetic Ordering In The Spinel Compound Li[Mn₂₋ₓlix]O₄(X=0, 0.04), John Gaddy, Jagat Lamsal, Marcus Petrovic, Wouter Montfrooij, Alexander Schmets, Thomas Vojta
Magnetic Ordering In The Spinel Compound Li[Mn₂₋ₓlix]O₄(X=0, 0.04), John Gaddy, Jagat Lamsal, Marcus Petrovic, Wouter Montfrooij, Alexander Schmets, Thomas Vojta
Physics Faculty Research & Creative Works
The two B-site ions Mn3+ and Mn4+ in the stoichiometric spinel structure LiMn2O4 form a complex, columnar ordered pattern below the charge-ordering transition at room temperature. On further cooling to below 66 K, the system develops long-range antiferromagnetic order. In contrast, whereas lithium-substituted Li[Mn2−xLix]O4 also undergoes a charge-ordering transition around room temperature, it only displays frozen in short-range magnetic order below ~25-30 K. We investigate to what extent the columnar charge-order pattern observed in LiMn2O4 can account for the measured magnetic ordering patterns in both the pure and Li-substituted (x=0.04) compounds. We conclude that eightfold rings of Mn4+ ions form …
Virtual Resonant States In Two-Photon Decay Processes: Lower-Order Terms, Subtractions, And Physical Interpretations, Ulrich D. Jentschura
Virtual Resonant States In Two-Photon Decay Processes: Lower-Order Terms, Subtractions, And Physical Interpretations, Ulrich D. Jentschura
Physics Faculty Research & Creative Works
We investigate the two-photon decay rate of a highly excited atomic state which can decay to bound states of lower energy via cascade processes. We show that a naïve treatment of the process, based on the introduction of phenomenological decay rates for the intermediate, resonant states, leads to lower-order terms which need to be subtracted in order to obtain the coherent two-photon correction to the decay rate. The sum of the lower-order terms is exactly equal to the one-photon decay rate of the initial state, provided the naïve two-photon decay rates are summed over all available two-photon channels. A quantum …