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Igor Bray

Bio: Igor Bray is an academic researcher from Curtin University. The author has contributed to research in topics: Ionization & Scattering. The author has an hindex of 44, co-authored 566 publications receiving 9408 citations. Previous affiliations of Igor Bray include Los Alamos National Laboratory & University of Maryland, College Park.


Papers
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Journal ArticleDOI
TL;DR: This work presents convergent elastic, 2s, and 2p differential cross sections, spin asymmetries, and angular-correlation parameters for the 2p excitation at 35, 54.4, and 100 eV.
Abstract: The convergence of the close-coupling formalism is studied by expanding the target states in an orthogonal ${\mathit{L}}^{2}$ Laguerre basis. The theory is without approximation, and convergence is established by simply increasing the basis size. We present convergent elastic, 2s, and 2p differential cross sections, spin asymmetries, and angular-correlation parameters for the 2p excitation at 35, 54.4, and 100 eV. Integrated and total cross sections as well as T-matrix elements for the first five partial waves are also given.

353 citations

Journal ArticleDOI
TL;DR: Generally, good agreement with experiment is obtained with the available differential, integrated, ionization, and total cross sections, as well as with the electron-impact coherence parameters up to and including the 3 {sup 3}{ital D}-state excitation.
Abstract: We present the convergent close-coupling theory for the calculation of electron-helium scattering. We demonstrate its applicability at a range of projectile energies of 1.5 to 500 eV to scattering from the ground state to n\ensuremath{\le}3 states. Generally, good agreement with experiment is obtained with the available differential, integrated, ionization, and total cross sections, as well as with the electron-impact coherence parameters up to and including the 3 $^{3}$D-state excitation. This agreement is shown to be overall the best of the currently used electron-helium scattering theories. On occasion, some significant discrepancies with experiment are observed, particularly for the triplet-state excitations.

267 citations

Journal ArticleDOI
TL;DR: LXCat as mentioned in this paper is an open-access platform for curating data needed for modeling the electron and ion components of technological plasmas, including scattering cross sections and swarm/transport parameters, ion-neutral interaction potentials, and optical oscillator strengths.
Abstract: LXCat is an open-access platform (www.lxcat.net) for curating data needed for modeling the electron and ion components of technological plasmas. The data types presently supported on LXCat are scattering cross sections and swarm/transport parameters, ion-neutral interaction potentials, and optical oscillator strengths. Twenty-four databases contributed by different groups around the world can be accessed on LXCat. New contributors are welcome; the database contributors retain ownership and are responsible for the contents and maintenance of the individual databases. This article summarizes the present status of the project.

177 citations

Journal ArticleDOI
TL;DR: In this article, a solution of a small-model three-body problem, using the convergent close-coupling method, has led to numerous applications involving real atomic collision systems.
Abstract: The substantial progress that has occurred during the 1990s in the field of electron-atom-collision theory is discussed. We show how a solution of a small-model three-body problem, using the convergent close-coupling method, has led to numerous applications involving real atomic collision systems. Consequently many fundamental electron-atom collision processes are considered as 'solved', and accurate collision data of interest to science and industry have become available. However, we suggest that the present has only just seen the birth of modern atomic collision theory. There are many more important collision problems to be tackled, with guidance coming from experiment being as important as ever.

165 citations

Journal ArticleDOI
Igor Bray1
TL;DR: In this article, the convergent-close-coupling method was extended for the calculation of electron-hydrogen scattering to hydrogen-like targets, atoms, or ions.
Abstract: We extend the convergent-close-coupling method for the calculation of electron-hydrogen scattering to hydrogenlike targets, atoms, or ions. These include H, Li, Na, and K, atoms, as well as the multitude of ions which have the same isoelectronic sequence as any of these atoms. The reliability of the method is independent of the projectile energy, and we demonstrate its applicability by achieving excellent agreement with a large set of measurements for electron scattering on sodium at projectile energies ranging from 1 to 54.4 eV. These measurements include spin asymmetries, singlet and triplet ${\mathit{L}}_{\mathrm{\ensuremath{\perp}}}$, reduced Stokes parameters, differential, integrated, and total cross sections, as well as the total ionization spin asymmetry. The method is found to give better agreement with experiment than any other over this entire energy range.

158 citations


Cited by
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[...]

08 Dec 2001-BMJ
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

33,785 citations

Book
01 Jan 1957

1,574 citations

Journal ArticleDOI
TL;DR: In this article, the authors present a comprehensive set of FDCSs for single ionization of atoms by ion-impact, the most basic atomic fragmentation reaction, brought new insight, a couple of surprises and unexpected challenges to theory at keV to GeV collision energies.
Abstract: Recoil-ion and electron momentum spectroscopy is a rapidly developing technique that allows one to measure the vector momenta of several ions and electrons resulting from atomic or molecular fragmentation. In a unique combination, large solid angles close to 4π and superior momentum resolutions around a few per cent of an atomic unit (a.u.) are typically reached in state-of-the art machines, so-called reaction-microscopes. Evolving from recoil-ion and cold target recoil-ion momentum spectroscopy (COLTRIMS), reaction-microscopes—the `bubble chambers of atomic physics'—mark the decisive step forward to investigate many-particle quantum-dynamics occurring when atomic and molecular systems or even surfaces and solids are exposed to time-dependent external electromagnetic fields. This paper concentrates on just these latest technical developments and on at least four new classes of fragmentation experiments that have emerged within about the last five years. First, multi-dimensional images in momentum space brought unprecedented information on the dynamics of single-photon induced fragmentation of fixed-in-space molecules and on their structure. Second, a break-through in the investigation of high-intensity short-pulse laser induced fragmentation of atoms and molecules has been achieved by using reaction-microscopes. Third, for electron and ion-impact, the investigation of two-electron reactions has matured to a state such that the first fully differential cross sections (FDCSs) are reported. Fourth, comprehensive sets of FDCSs for single ionization of atoms by ion-impact, the most basic atomic fragmentation reaction, brought new insight, a couple of surprises and unexpected challenges to theory at keV to GeV collision energies. In addition, a brief summary on the kinematics is provided at the beginning. Finally, the rich future potential of the method is briefly envisaged.

1,375 citations

Journal ArticleDOI
TL;DR: In this article, a two-part review summarizes the observations, theory, and simulations of interstellar turbulence and their implications for many fields of astrophysics, including basic fluid equations, solenoidal and compressible modes, global inviscid quadratic invariants, scaling arguments for the power spectrum, phenomenological models for the scaling of higher-order structu...
Abstract: ▪ Abstract Turbulence affects the structure and motions of nearly all temperature and density regimes in the interstellar gas. This two-part review summarizes the observations, theory, and simulations of interstellar turbulence and their implications for many fields of astrophysics. The first part begins with diagnostics for turbulence that have been applied to the cool interstellar medium and highlights their main results. The energy sources for interstellar turbulence are then summarized along with numerical estimates for their power input. Supernovae and superbubbles dominate the total power, but many other sources spanning a large range of scales, from swing-amplified gravitational instabilities to cosmic ray streaming, all contribute in some way. Turbulence theory is considered in detail, including the basic fluid equations, solenoidal and compressible modes, global inviscid quadratic invariants, scaling arguments for the power spectrum, phenomenological models for the scaling of higher-order structu...

1,195 citations

Journal ArticleDOI
TL;DR: The cold target recoil ion momentum spectroscopy (COLTRIMS) is a momentum space imaging technique for the investigation of the dynamics of ionizing ion, electron or photon impact reactions with atoms or molecules as mentioned in this paper.

985 citations