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Showing 1 to 20 of 46 for “"Born approximation"”.
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The Plane Wave Born Approximation for Determining Atomic K-Shell Ionization Cross- Sections by Positive Ion Impact
… in this work is based upon the plane wave Born approximation (PWBA) as worked out by Merzbacher and his co-workers (Me58, Me73). In Chapter III, Merzbacher's development of the theory is presented as is found in (Me58), but with many of the missing steps worked out in detail. In this …
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Beyond the Born Approximation: A Precise Comparison of e+p and e-p Elastic Scattering in the CEBAF Large Acceptance Spectrometer (CLAS)
<p>How well we know the structure of the proton depends on our knowledge of the form factors of the proton. The ratio of the electromagnetic form factors of the proton measured by the Rosenbluth and the polarization transfer methods differ by a factor of 3 at four momentum transfer squared …
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A wave-kinetic numerical method for the propagation of optical waves
… from a Monte-Carlo simulation and the first Born approximation. Within the validity of the Liouville approximation, the Wigner distribution function ( WDF ) is conserved along the conventional ray trajectories, and, thus, by discretizing the input WDF with Gaussian beamlets, we can represent …
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Elastic wave scattering from bounded media with random microstructures
A first-order Born approximation is utilized to solve the direct and inverse scattering problems of bounded infinite media with random microstructures. The inhomogeneities of the media properties due to their microstructures are assumed to be small. Relatively simple relations are obtained between …
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An inverse method for obtaining the attenuation profile and small variations in the sound speed and density profiles of the ocean bottom
… is derived. This is then linearised using the Born approximation. The region of validity of the Born approximation is derived and based on this the optimum angular aperture for the input data is obtained. The linearised integral equation is a Fredholm integral equation of the first kind. An …
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Conductance and magnetoconductance of parabolically confined quasi-one-dimensional channels
… well as with the limit of the conductance in the Born approximation. A similar but new expression is obtained in the presence of a magnetic field perpendicular to the channel. This expression is more general than those contained in previous literature as it accounts explicitly for the Hall field. …
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Energy dependence of the helium-3 induced charge exchange reaction on several light nuclei with n - z = 1
… MeV. The data were analyzed using distorted-wave Born approximation with both a phenomenological and microscopic form factor. A generalized collective excitation model is introduced. The data suggests the need of a second order reaction mechanism.
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Investigating on elastic and inelastic nuclear scattering and polarisation
… compared with optical model and distorted wave Born approximation calculations.
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APPROXIMATE VS. PURELY NUMERICAL APPROACHES FOR FULL WAVEFORM MODELLING OF GLOBAL EARTH STRUCTURE
… Firstly, we investigate two techniques: (i) the Born approximation, which should be valid for media with weak heterogeneity; and, (ii) the full ray theory approach, which should be valid for smooth media. We find that the Born approximation has a very limited domain of validity. It only models …
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Computational Methods for One-Dimensional Scattering in Non-Smooth Media
… the scattering-based algorithm, the classical Born approximation, the refined impedance transform and the echoes-to-impedance transform. The last three are inverse scattering algorithms that numerically convert data in the time domain to an impedance in the spatial domain; however, the …
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Single proton transfer on 55Mn
… determined from local, zero-range distorted-wave Born approximation (DWBA) analyses of the measured angular distributions, allowing for l = 0, 1, 2 and 3 transfers. An optical-model analysis of the (d,d) data has been performed in order to yield optimum values of the potential parameters required …
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Exact reconstruction of ocean bottom velocity profiles from monochromatic scattering data
… are investigated. The first one is an "Improved Born approximation" wherein the solution is given as a series expansion the first term of which is the Born approximation while the second term represents a substantial and yet easy to implement improvement over Born. The two other methods are based …
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Testing the vibrational nature of 100Ru
… cross sections were compared with distorted wave Born approximation (DWBA) calculations. This spectroscopic analysis was used to probe the structure of 100Ru, and indicate that this particular case also does not convincingly demonstrate spherical vibrational behavior
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Anderson Localization in Two-Channel Wires with Correlated Disorder: DNA as an Application
… model. Calculations were within second-order Born-approximation to second-order in disorder parameters. An analytical expression for localization length as a functional of correlations in potentials was found. Anderson localization in DNA molecules were studied in single-channel wire and …
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Investigation of (E, 2E) Collisions and Related Phenomena
… methods. I first examine the problem using the Born approximations, particularly the Distorted Wave Born Approximation (DWBA), focusing on the underlying processes that dominate for ionization of the 2<em>p</em> state of Argon and Magnesium. I investigate as well the ionization of helium and …
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Inverse methods for sound speed estimation in the ocean
… past, Stickler and Zhou employed a first order Born approximation for solving the integral equation. This work introduces two new methods. The first is a modified Born approximation that improves upon a standard first order approximation, yet it is easy to implement; the second one is an …
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Interaction cross sections needed for simulation of secondary electron emission spectra from thin metal foils after fast proton impact
… thin-metal foils within the plane-wave first Born approximation (PWFBA) that factorizes the double cross section into the generalized oscillator strength and kinematic factors. The generalized oscillator strength or Bethe surface of the medium is obtained by using a semi-empirical optical …
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The ⁴⁴Ca(d,α)⁴²K reaction at 4.0 MeV
Distorted-wave Born-approximation (DWBA) analysis of direct reactions has proven to be a very useful tool in understanding single- and two-particle transfer reactions and nuclear structure. The 4 MV Van de Graaff accelerator at Virginia Polytechnic Institute and State University was used to check …
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Advanced Array Imaging for Breast and Prostate Sonography
… -4(r-r’) Using one of the most frequently used approximations, the Rayleigh-Born approximation we can modify equation (7). At large distance the Green‟s function can be approximated by G(r – r’) ~ eikr/r e-ikr.r’ which holds true for k0r‟2/r <<1. A Fourier diffraction theorem based …
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Orientation dependence of the acoustic backscatter for elongated zooplankton
… acoustic frequency. Using the distorted wave Born approximation (DWBA) and the geometry of a prolate spheroid, an analytic formula for the backscatter cross section as a function of orientation angle is derived. A directivity pattern is determined from the analytic formula and the width of the …
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