Multiple scattering technique lidar
NASA Technical Reports Server (NTRS)
Bissonnette, Luc R.
1992-01-01
The Bernouilli-Ricatti equation is based on the single scattering description of the lidar backscatter return. In practice, especially in low visibility conditions, the effects of multiple scattering can be significant. Instead of considering these multiple scattering effects as a nuisance, we propose here to use them to help resolve the problems of having to assume a backscatter-to-extinction relation and specifying a boundary value for a position far remote from the lidar station. To this end, we have built a four-field-of-view lidar receiver to measure the multiple scattering contributions. The system has been described in a number of publications that also discuss preliminary results illustrating the multiple scattering effects for various environmental conditions. Reported here are recent advances made in the development of a method of inverting the multiple scattering data for the determination of the aerosol scattering coefficient.
1979-09-01
Equation .................................. 35 Boundary Conditions ................................ 37SIrradiance at Cloud Exit...mathematical description of the multiple scatter- ing problem is given by the nonstationary radiative transport equation of Chandrasekhar [2]. Written in...function, S0 is the source function, and X is the single-scatter albedo. Unfortunately, the nonstationary transport equation has not been solved in a
Multiple scattering expansion with distortion
NASA Astrophysics Data System (ADS)
Tandy, P. C.; Thaler, R. M.
1980-12-01
A multiple scattering description of elastic scattering is formulated in terms of impulsive scatterings from single target nucleons and pairs of target nucleons. In this description, distortion effects on the projectile from the residual medium are also described by multiple scattering in terms of the same single and pair amplitudes. At the level of single scattering, this procedure yields the first order optical potential result of Kerman, McManus, and Thaler. When scattering from both single nucleons and pairs of nucleons is included, the method leads to a one-body integral equation which requires the physical projectile-nucleon and projectile-pair transition amplitudes as input. This input is similar, but not exactly equivalent to that required by the spectator expansion for the optical potential truncated at second order. A principal advantage of the present formulation is that there need be no explicit dependence upon the projection operator Q which projects off the target ground state. This feature introduces a scaling which appears to be a direct extension of the first order Kerman, McManus, and Thaler type of scaling. We follow up suggestions arising in the foregoing to show that the exact optical potential to second order in the spectator expansion can also be cast into a form having no explicit dependence upon Q, and requiring physical projectile-nucleon and projectile-pair transition amplitudes as input. NUCLEAR REACTIONS Multiple scattering from single nucleons, pairs of nucleons in nucleus. Distortion from residual medium. Optical potential. spectator expansion.
Multiple Scattering Theory of XAFS
NASA Astrophysics Data System (ADS)
Zabinsky, Steven Ira
A multiple scattering theory of XAFS for arbitrary materials with convergence to full multiple scattering calculations and to experiment is presented. It is shown that the multiple scattering expansion converges with a small number of paths. The theory is embodied in an efficient automated computer code that provides accurate theoretical multiple scattering standards for use in experimental analysis. The basis of this work is a new path enumeration and filtering algorithm. Paths are constructed for an arbitrary cluster in order of increasing path length. Filters based on the relative importance of the paths in the plane wave approximation and on the random phase approximation limit the number of paths so that all important paths with effective path length up to the mean free path length (between 10 and 20 A) can be considered. Quantitative expressions for path proliferation and relative path importance are presented. The calculations are compared with full multiple scattering calculations for Cu and Al. In the case of fcc Cu, the path filters reduce the number of paths from 60 billion to only 56 paths in a cluster of radius 12.5 A. These 56 paths are sufficient to converge the calculation to within the uncertainty inherent in the band structure calculation. Based on an analysis of these paths, a new hypothesis is presented for consideration: Single scattering, double scattering, and all orders of scattering that involve only forward or back scattering are sufficient to describe XAFS. Comparison with experiment in Cu, Pt and Ti demonstrate the accuracy of the calculation through the fourth shell. The correlated Debye model is used to determine Debye-Waller factors--the strengths and weaknesses of this approach are discussed. Preliminary results for calculations of the x -ray absorption near edge structure (XANES) have been done. The calculations compare well with Cu, Pt and Ti experiments. The white line in the Pt absorption edge is calculated correctly. There are
Multiple-scattering effects in lidar spectroscopy
NASA Astrophysics Data System (ADS)
Joelson, Brad D.; Kattawar, George W.
1996-11-01
We have performed Monte Carlo calculations to investigate the effect of multiple scattering on the frequency spectra due to Brillouin scattering in the ocean. The use of the frequency spectra to determine the speed of sound and temperature profiles and the hydrosol backscattering probability is shown to be stable in turbid multiple scattering waters.
Exact Multiple Scattering XANES Calculations
NASA Astrophysics Data System (ADS)
Ravel, B.; Rehr, J. J.
1996-03-01
Ab initio calculations of X-ray absorption near-edge structure (XANES), are made by inverting the full multiple-scattering (MS) matrix G=(1-G_0t)-1G_0. Our approach uses the fast, quickly convergent Rehr-Albers(J.J. Rehr and R.C. Albers, Phys. Rev. B, 41), 8139, (1990) separable representation of the free electron propagator G0 together with atomic scattering t-matrices from the FEFF6 code,(S. I. Zabinsky, et al., Phys. Rev. B52), 2995 (1995). which are calculated within the muffin-tin approximation with overlapped atom potentials. With this technique XANES spectra and its polarization dependence can be calculated in reasonable cpu time on large clusters. Good agreement with the XANES spectra of several sample compounds is obtained. This strategy is also used to determine the local densities of states ρ(E, r ) from the full MS matrix. From ρ(E, r ) we calculate the Fermi energies and estimate charge transfer for our sample clusters. The prospect of quantitative analysis of XANES spectra and its preedge features is discussed.
Multiple scattering by deep perturbed gratings
Knotts, M.E.; O`Donnell, K.A.
1994-11-01
We present measurements of the far-field scattered intensity for gratings consisting of uniform, regularly spaced, wavelength-scale grooves that have randomly fluctuating depths. The complete polarization dependence of the scattering is determined, and particular attention is given to measurements that isolate multiple scattering. For both perturbed and unperturbed gratings, effects similar to backscattering enhancement seen for randomly rough surfaces are observed, and these effects are linked to the coherent interference of reciprocal pairs of waves multiply scattered within the grooves.
Polarimetric scattering from layered media with multiple species of scatterers
NASA Technical Reports Server (NTRS)
Nghiem, S. V.; Kwok, R.; Yueh, S. H.; Kong, J. A.; Hsu, C. C.; Tassoudji, M. A.; Shin, R. T.
1995-01-01
Geophysical media are usually heterogeneous and contain multiple species of scatterers. In this paper a model is presented to calculate effective permittivities and polarimetric backscattering coefficients of multispecies-layered media. The same physical description is consistently used in the derivation of both permittivities and scattering coefficients. The strong permittivity fluctuation theory is extended to account for the multiple species of scatterers with a general ellipsoidal shape whose orientations are randomly distributed. Under the distorted Born approximation, polarimetric scattering coefficients are obtained. These calculations are applicable to the special cases of spheroidal and spherical scatterers. The model is used to study effects of scatterer shapes and multispecies mixtures on polarimetric signatures of heterogeneous media. The multispecies model accounts for moisture content in scattering media such as snowpack in an ice sheet. The results indicate a high sensitivity of backscatter to moisture with a stronger dependence for drier snow and ice grain size is important to the backscatter. For frost-covered saline ice, model results for bare ice are compared with measured data at C band and then the frost flower formation is simulated with a layer of fanlike ice crystals including brine infiltration over a rough interface. The results with the frost cover suggest a significant increase in scattering coefficients and a polarimetric signature closer to isotropic characteristics compared to the thin saline ice case.
Multiple scattering effects on spaceborne lidar
NASA Technical Reports Server (NTRS)
Winker, David M.; Poole, Lamont R.
1992-01-01
A semianalytic Monte Carlo code originally developed for oceanographic calculations (Poole et al., 1981) has been modified for use in studying multiple scattering of space-based lidar. The approach is very similar to that described by Kunkel and Weinman (1976). The trajectory of each photon is followed from the transmitter through multiple scattering until the photon is either scattered backward out of the atmosphere, scattered forward into the ground and absorbed, or scattered out the sides of the cloud. The probability that the photon will return directly to the detector is computed and summed over all significant scattering events within the field of view of the detector. Multiple scattering of the lidar pulse causes an apparent increase in the transmittance of the medium. Multiple scattering effects for space-based lidar are more significant than for ground-based lidar due to the much larger beam diameter in the atmosphere. These larger diameters are due not only to the greater range between the lidar and the scattering volume, but also the need to maintain relatively large beam divergences to satisfy eye safety restrictions on the laser irradiance at the Earth's surface. The simulations presented here are for a wavelength of 1064 nm and the Deirmendjian C1 phase function, which yields an extinction coefficient of 17.259/km. We have looked at two cases: a space-based lidar at 296 km observing a C1 cloud 293 km from the lidar and, for comparison purposes, a ground-based lidar looking at a C1 cloud with a base height of either 2 km or 5 km. The C1 size distribution roughly approximates that of stratocumulus or altocumulus clouds (aufm Kampe and Weickmann, 1957).
Energy dependent 4-dimensional multiple scattering distributions
NASA Astrophysics Data System (ADS)
Tschalär, C.
1984-12-01
A complete analytic solution in Fourier space is presented of the four dimensional small angle, multiple scattering distribution MSD in angle and space, produced by an energy dependent single scattering cross section from an initial pencil beam of heavy particles. Independently, simple integrals are derived for the central moments of the energy dependent MSD in the continuous-slowing-down approximation. The distributions of the projections t and x of the scattering angle and displacement into a plane through the axis of propagation are evaluated numerically for a truncated Rutherford scattering cross section using a fast Fourier transform. The resulting MSDs for a wide range of particles, initial and final momenta, and scattering materials are found to be approximately represented by one-dimensional set of standard distributions symmetrized by a linear transformation in t- x-space.
Solving multiple scattering problems in planetary atmospheres
NASA Technical Reports Server (NTRS)
Irvine, W. M.; Lenoble, J.
1974-01-01
Multiple scattering problems, radiative transfer problems in planetary atmospheres within extended visible portion of the spectrum, are examined. The direct and inverse problems and the extinction coefficient are defined, along with other scattering characteristics. Albedos in semi-infinite and finite atmospheres are considered, as well as surface illumination, energy deposition, and polarization. The Eddington approximation figures prominently in the calculations. Precise numerical methods and analytical solutions are included.
Multiple Scattering Effects in Ionization Processes
NASA Astrophysics Data System (ADS)
Barrachina, R. O.
2011-10-01
The momentum distributions of electrons emitted in the ionization of atoms and molecules by the impact of photons or massive particles usually present interference patterns similar to those of the demonstrations with light proposed by Thomas Young more than two centuries ago. Furthermore, these cross sections also display richer structures due to the same multiple-scattering effects that are at the origin of different techniques to probe atomic aggregates and solid samples. In this talk, I will review these effects and discuss some of their most important characteristics, showing that they lead to distortions that are not fully replicated by non-scattering or even single-scattering approximations.
Multiple Scatters in Single Site Gamma Backgrounds
Brodsky, J. P.
2016-09-16
nEXO aims to reduce its gamma backgrounds by taking advantage of the fact that a large number of gammas that would otherwise be backgrounds will undergo multiple compton scattering in the TPC and produce spatially distinct signals. These multi-sited (MS) events can be excluded from the 0νββ search.
Multiple scattering of metallic wire structures
NASA Astrophysics Data System (ADS)
Zhan, T. R.; Chui, S. T.; Lin, Z. F.
2015-10-01
We describe how the electromagnetic resonance and scattering properties of complex structures of which metallic wire structures are constituents can be studied with multiple scattering theory. The t matrix of individual structures is calculated with our recently developed rigorous equivalent circuit theory in which retardation effects are taken into account. We illustrate our method with the example of a planar periodic array of split ring resonators. The transmission is calculated as a function of frequency. The result is found to agree well with that obtained by a commercial code (COMSOL) but our result is two orders of magnitude faster and requires much less memory.
Multiple Light Scattering Probes of Soft Materials
NASA Astrophysics Data System (ADS)
Scheffold, Frank
2007-02-01
I will discuss both static and dynamic properties of diffuse waves. In practical applications the optical properties of colloidal systems play an important role, for example in commercial products such as sunscreen lotions, food (drinks), coatings but also in medicine for example in cataract formation (eye lens turbidity). It is thus of importance to know the key parameters governing optical turbidity from the single to the multiple scattering regime. Temporal fluctuations of multiply scattered light are studied with photon correlation spectroscopy (Diffusing Wave Spectroscopy). This DWS method and its various implementations will be treated.
Theory of Multiple Coulomb Scattering from Extended Nuclei
DOE R&D Accomplishments Database
Cooper, L. N.; Rainwater, J.
1954-08-01
Two independent methods are described for calculating the multiple scattering distribution for projected angle scattering resulting when very high energy charged particles traverse a thick scatterer. The results are compared with the theories of Moliere and Olbert.
Acoustic multiple scattering using recursive algorithms
NASA Astrophysics Data System (ADS)
Amirkulova, Feruza A.; Norris, Andrew N.
2015-10-01
Acoustic multiple scattering by a cluster of cylinders in an acoustic medium is considered. A fast recursive technique is described which takes advantage of the multilevel Block Toeplitz structure of the linear system. A parallelization technique is described that enables efficient application of the proposed recursive algorithm for solving multilevel Block Toeplitz systems on high performance computer clusters. Numerical comparisons of CPU time and total elapsed time taken to solve the linear system using the direct LAPACK and TOEPLITZ libraries on Intel FORTRAN, show the advantage of the TOEPLITZ solver. Computations are optimized by multi-threading which displays improved efficiency of the TOEPLITZ solver with the increase of the number of scatterers and frequency.
Coulomb interaction in multiple scattering theory
NASA Astrophysics Data System (ADS)
Ray, L.; Hoffmann, G. W.; Thaler, R. M.
1980-10-01
The treatment of the Coulomb interaction in the multiple scattering theories of Kerman-McManus-Thaler and Watson is examined in detail. By neglecting virtual Coulomb excitations, the lowest order Coulomb term in the Watson optical potential is shown to be a convolution of the point Coulomb interaction with the distributed nuclear charge, while the equivalent Kerman-McManus-Thaler Coulomb potential is obtained from an averaged, single-particle Coulombic T matrix. The Kerman-McManus-Thaler Coulomb potential is expressed as the Watson Coulomb term plus additional Coulomb-nuclear and Coulomb-Coulomb cross terms, and the omission of the extra terms in usual Kerman-McManus-Thaler applications leads to negative infinite total reaction cross section predictions and incorrect pure Coulomb scattering limits. Approximations are presented which eliminate these anomalies. Using the two-potential formula, the full projectile-nucleus T matrix is separated into two terms, one resulting from the distributed nuclear charge and the other being a Coulomb distorted nuclear T matrix. It is shown that the error resulting from the omission of the Kerman-McManus-Thaler Coulomb terms is effectively removed when the pure Coulomb T matrix in Kerman-McManus-Thaler is replaced by the analogous quantity in the Watson approach. Using the various approximations, theoretical angular distributions are obtained for 800 MeV p+208Pb elastic scattering and compared with experimental data. NUCLEAR REACTIONS 208Pb(p, p), E=0.8 GeV, Kerman, McManus, and Thaler, and Watson multiple scattering theories, Coulomb correction terms, high momentum transfer.
Multiple scattering in particulate planetary surfaces
NASA Astrophysics Data System (ADS)
Muinonen, Karri; Peltoniemi, Jouni; Markkanen, Johannes; Penttilä, Antti; Videen, Gorden
2015-08-01
There are two ubiquitous phenomena observed at small solar phase angles (the Sun-Object-Observer angle) from, for example, asteroids and transneptunian objects. First, a nonlinear increase of brightness is observed toward the zero phase angle in the magnitude scale that is commonly called the opposition effect. Second, the scattered light is observed to be partially linearly polarized parallel to the Sun-Object-Observer plane that iscommonly called the negative polarization surge.The observations can be interpreted using a radiative-transfer coherent-backscattering Monte Carlo method (RT-CB, Muinonen 2004) that makes use of a so-called phenomenological fundamental single scatterer (Muinonen and Videen 2012). For the validity of RT-CB, see Muinonen et al. (2012). The method can allow us to put constraints on the size, shape, and refractive index of the fundamental scatterers.In the present work, we extend the RT-CB method for the specific case of a macroscopic medium of electric dipole scatterers. For the computation of the interactions, the far-field approximation inherent in the RT-CB method is replaced by an exact treatment, allowing us to account for, e.g., the so-called near-field effects. The present method constitutes the first milestone in the development of a multiple-scattering method, where the so-called ladder and maximally crossed cyclical diagrams of the multiple electromagnetic interactions are rigorously computed. We expect to utilize the new methods in the spectroscopic, photometric, and polarimetric studies of asteroids, as well as in the interpretation of radar echoes from small Solar System bodies.Acknowledgments. The research is funded by the ERC Advanced Grant No 320773 entitled Scattering and Absorption of Electromagnetic Waves in Particulate Media (SAEMPL).K. Muinonen, Waves in Random Media 14, 365 (2004).K. Muinonen, K., and G. Videen, JQSRT 113, 2385 (2012).K. Muinonen, M. I. Mishchenko, J. M. Dlugach, E. Zubko, A. Penttilä,and G. Videen
Multiple scattering theory for space filling potentials
Butler, W.H. ); Brown, R.G. . Dept. of Physics); Nesbet, R.K. . Almaden Research Center)
1990-01-01
Multiple scattering theory (MST) provides an efficient technique for solving the wave equation for the special case of muffin-tin potentials. Here MST is extended to treat space filling non-muffin tin potentials and its validity, accuracy and efficiency are tested by application of the two dimensional empty lattice test. For this test it is found that the traditional formulation of MST does not coverage as the number of partial waves is increased. A simple modification of MST, however, allows this problem to be solved exactly and efficiently. 15 refs., 3 tabs.
Solving multiple scattering problems in planetary atmospheres
NASA Technical Reports Server (NTRS)
Irvine, W. M.; Lenoble, J.
1974-01-01
Definitions are provided of the basic concepts occurring in the solution of multiple scattering problems involving planetary atmospheres and attention is given to aspects of problem characterization. Approaches are considered for finding the answer to a particular problem without the performance of detailed calculations. The characteristics of albedos are investigated, taking into account semiinfinite atmospheres and finite atmospheres. Questions of surface illumination are discussed along with aspects related to energy deposition in the atmosphere, intensity, and polarization. Precise numerical methods are examined and analytical solutions are presented.
Investigation of multiple scattering effects in aerosols
NASA Technical Reports Server (NTRS)
Deepak, A.
1980-01-01
The results are presented of investigations on the various aspects of multiple scattering effects on visible and infrared laser beams transversing dense fog oil aerosols contained in a chamber (4' x 4' x 9'). The report briefly describes: (1) the experimental details and measurements; (2) analytical representation of the aerosol size distribution data by two analytical models (the regularized power law distribution and the inverse modified gamma distribution); (3) retrieval of aerosol size distributions from multispectral optical depth measurements by two methods (the two and three parameter fast table search methods and the nonlinear least squares method); (4) modeling of the effects of aerosol microphysical (coagulation and evaporation) and dynamical processes (gravitational settling) on the temporal behavior of aerosol size distribution, and hence on the extinction of four laser beams with wavelengths 0.44, 0.6328, 1.15, and 3.39 micrometers; and (5) the exact and approximate formulations for four methods for computing the effects of multiple scattering on the transmittance of laser beams in dense aerosols, all of which are based on the solution of the radiative transfer equation under the small angle approximation.
Multiple scattering of laser beams in dense hydrosols
NASA Technical Reports Server (NTRS)
Zardecki, A.; Gerstl, S. A. W.; Unruh, W. P.; Stokes, G. H.; Stupin, D. M.; Elliott, N. E.; Weinman, J. A.
1986-01-01
The multiple scattering of laser beams is usually described within the framework of small-angle scattering theory. The validity of this approximation as well as improvements due to the incorporation of diffusion theory in the calculations were studied.
Measurements of muon multiple scattering in MICE
NASA Astrophysics Data System (ADS)
Bayes, R.;
2017-09-01
Neutrino factories have been identified as the best facility for making precision measurements of neutrino oscillation physics. To fully realize this technology, a demonstration of the reduction of the phase space of a muon beam must be presented. The Muon Ionization Cooling Experiment (MICE) is tasked with providing such a demonstration. Ionization cooling uses the energy loss in a low Z material followed by acceleration in RF cavities to reduce the phase space of a beam on a time scale many times less than the time scale of muon decay. Multiple coulomb scattering (MCS) simultaneously inflates the muon beam and so the interplay between energy loss and MCS must be well understood. Unfortunately MCS is not well simulated in the materials of interest in the GEANT Monte Carlo program. A programme has commenced for MICE to measure MCS in several materials of interest including lithium hydride, liquid hydrogen, and gaseous xenon. The experimental methods and early results will be presented.
Effect of Multiple Scattering in a Quantum Well
NASA Astrophysics Data System (ADS)
Sheng, Hanyu; Chua, Soo-Jin; Sinkkonen, Juha
This paper gives a potentially useful application to quantum well of the theory of scattering in the Born approximation. The simple formulae for multiple scattering in a quantum well of double barrier structure are derived. The multiple scattering parameter is the complex mean free path. We show that the amplitude of the coherent wave will be exponentially attenuated and the phase of the wave will be delayed because of the scattering.
Single and multiple scattering contributions to circumsolar radiation.
Box, M A; Deepak, A
1978-12-01
Single and multiple scattering contributions to the circumsolar radiation along the almucantar and sun vertical have been computed by a Gauss-Seidel solution to the radiative transfer equation. In the near forward direction, the multiple scattering contributions are significant for optical depths of the order of 0.4. However, the shape of the angular distribution of almucantar radiance up to 10 degrees appears less sensitive to multiple scattering. The results have been compared against an existing radiative transfer code.
Double- and multiple-scattering effects in translucent materials.
Holzschuch, Nicolas; Gascuel, Jean-Dominique
2013-01-01
Some materials, such as coffee, milk, or marble, have a soft translucent aspect because of subsurface scattering. Light enters them and gets scattered several times before leaving in a different place. A full representation of subsurface-scattering effects in illumination simulation is computationally expensive. The main difficulty comes from multiple scattering events. The high number of events increases the results' uncertainty, requiring more computation time. However, a strong correlation exists between the surface effects of multiple scattering and the effects after just two scattering events. This knowledge can help accelerate multiple-scattering effects. In particular, researchers have exploited this knowledge to provide a model and implementation for fast computation of double-scattering events using a precomputed density function stored compactly.
Multiple magnetic scattering in small-angle neutron scattering of Nd–Fe–B nanocrystalline magnet
Ueno, Tetsuro; Saito, Kotaro; Yano, Masao; Ito, Masaaki; Shoji, Tetsuya; Sakuma, Noritsugu; Kato, Akira; Manabe, Akira; Hashimoto, Ai; Gilbert, Elliot P.; Keiderling, Uwe; Ono, Kanta
2016-01-01
We have investigated the influence of multiple scattering on the magnetic small-angle neutron scattering (SANS) from a Nd–Fe–B nanocrystalline magnet. We performed sample-thickness- and neutron-wavelength-dependent SANS measurements, and observed the scattering vector dependence of the multiple magnetic scattering. It is revealed that significant multiple scattering exists in the magnetic scattering rather than the nuclear scattering of Nd–Fe–B nanocrystalline magnet. It is considered that the mean free path of the neutrons for magnetic scattering is rather short in Nd–Fe–B magnets. We analysed the SANS data by the phenomenological magnetic correlation model considering the magnetic microstructures and obtained the microstructural parameters. PMID:27321149
Multiple magnetic scattering in small-angle neutron scattering of Nd-Fe-B nanocrystalline magnet.
Ueno, Tetsuro; Saito, Kotaro; Yano, Masao; Ito, Masaaki; Shoji, Tetsuya; Sakuma, Noritsugu; Kato, Akira; Manabe, Akira; Hashimoto, Ai; Gilbert, Elliot P; Keiderling, Uwe; Ono, Kanta
2016-06-20
We have investigated the influence of multiple scattering on the magnetic small-angle neutron scattering (SANS) from a Nd-Fe-B nanocrystalline magnet. We performed sample-thickness- and neutron-wavelength-dependent SANS measurements, and observed the scattering vector dependence of the multiple magnetic scattering. It is revealed that significant multiple scattering exists in the magnetic scattering rather than the nuclear scattering of Nd-Fe-B nanocrystalline magnet. It is considered that the mean free path of the neutrons for magnetic scattering is rather short in Nd-Fe-B magnets. We analysed the SANS data by the phenomenological magnetic correlation model considering the magnetic microstructures and obtained the microstructural parameters.
Multiple magnetic scattering in small-angle neutron scattering of Nd-Fe-B nanocrystalline magnet
NASA Astrophysics Data System (ADS)
Ueno, Tetsuro; Saito, Kotaro; Yano, Masao; Ito, Masaaki; Shoji, Tetsuya; Sakuma, Noritsugu; Kato, Akira; Manabe, Akira; Hashimoto, Ai; Gilbert, Elliot P.; Keiderling, Uwe; Ono, Kanta
2016-06-01
We have investigated the influence of multiple scattering on the magnetic small-angle neutron scattering (SANS) from a Nd-Fe-B nanocrystalline magnet. We performed sample-thickness- and neutron-wavelength-dependent SANS measurements, and observed the scattering vector dependence of the multiple magnetic scattering. It is revealed that significant multiple scattering exists in the magnetic scattering rather than the nuclear scattering of Nd-Fe-B nanocrystalline magnet. It is considered that the mean free path of the neutrons for magnetic scattering is rather short in Nd-Fe-B magnets. We analysed the SANS data by the phenomenological magnetic correlation model considering the magnetic microstructures and obtained the microstructural parameters.
Experimental study of multiple scattering in anisotropic titanium alloys
NASA Astrophysics Data System (ADS)
Baelde, Aurelien; Laurent, Jérôme; Coulette, Richard; Khalifa, Warida Ben; Duclos, Daniel; Jenson, Frédéric; Fink, Mathias; Prada, Claire
2017-02-01
Ultrasonic testing of jet engine titanium alloys is of high importance for the aircraft manufacturing industry. The quality of ultrasonic non-destructive testing is severely impacted by the titanium complex microstructure. These alloys have been extensively studied and single scattering models are now well known and implemented in ultrasonic propagation simulators. In addition, titanium billets and forged parts have been known to exhibit a highly anisotropic microstructure. We studied ultrasonic wave scattering in Ti17 forged disk, through statistical analysis of the backscattered noise generated by the microstructure. More specifically, we focused on the quantification of multiple scattering relative to single scattering in the backscattered wave. To that end, we used the full matrix capture acquisition with a linear transducer array. Two phenomena were used to quantify the proportion of single scattering with respect to multiple scattering. The first is the coherent backscattering effect, used as a binary indicator of multiple scattering. The second is a repurposed version of the multiple scattering filter, recently developed on random rod forest and applied on Inconel alloys. With these methods, significant level of multiple scattering was consistently measured in Ti17 forged disks, showing that ultrasonic testing could be enhanced by filtering the multiple scattering contribution.
Light scattering from a randomly occupied optical lattice. II. The multiple scattering problem.
Guo, Wei; Prasad, Sudhakar
2003-05-01
In this paper, we study the problem of multiple scattering of light from a randomly occupied optical lattice, thereby extending the first-order Born analysis of the previous paper. A full multiple-scattering analysis is essential to a complete understanding of the nature of light propagation inside a medium. Our calculations show that the incident wave, when resonant with the atomic medium, is rapidly extinguished due to multiple scattering. The decay constant depends critically on the incident wavelength, the lattice constant, the average number density of atoms, and their polarizability. Both the Bragg scattering amplitudes and directions are modified as a result of multiple scattering. Because of the random site occupation of an otherwise regular lattice structure, a coherent enhancement of the scattering cross section is also predicted to occur along a discrete set of directions that are related to the strictly backward direction by reciprocal lattice vectors.
Multiple scattering of polarized light: influence of absorption.
Hohmann, A; Voit, F; Schäfer, J; Kienle, A
2014-06-07
This work continues previous research about multiple scattering of polarized light propagation in turbid media, putting emphasis on the imaginary part of the scatterers' complex refractive index. The whole angle-dependent Müller matrix is evaluated by comparing results of a polarization sensitive radiative transfer solution to Maxwell theory. Turbid media of defined scatterer concentrations are modelled in three dimensions by sphere ensembles kept inside a cubic or spherical simulation volume. This study addresses the impact of absorption on polarization characteristics for selected media from low to high absorption. Besides that, effects caused by multiple and dependent scattering are shown for increasing volume concentration. In this context some unique properties associated with multiple scattering and absorption are pointed out. Further, scattering results in two dimensions are compared for examples of infinite parallel cylinders of high absorption and perpendicularly incident plane waves.
Method and apparatus for fiber optic multiple scattering suppression
NASA Technical Reports Server (NTRS)
Ackerson, Bruce J. (Inventor)
2000-01-01
The instant invention provides a method and apparatus for use in laser induced dynamic light scattering which attenuates the multiple scattering component in favor of the single scattering component. The preferred apparatus utilizes two light detectors that are spatially and/or angularly separated and which simultaneously record the speckle pattern from a single sample. The recorded patterns from the two detectors are then cross correlated in time to produce one point on a composite single/multiple scattering function curve. By collecting and analyzing cross correlation measurements that have been taken at a plurality of different spatial/angular positions, the signal representative of single scattering may be differentiated from the signal representative of multiple scattering, and a near optimum detector separation angle for use in taking future measurements may be determined.
Lidar effective multiple-scattering coefficients in cirrus clouds.
Nicolas, F O; Bissonnette, L R; Flamant, P H
1997-05-20
We delimit a regime, valid for most ground-based lidar probings of cirrus clouds, in which the field-of-view dependence of multiple scattering reaches a plateau. In this regime and assuming the phase function to be constant around pi, we formally demonstrate Platt's modification of the single-scattering lidar equation, with a parameter eta(P) accounting for the reduction of the effective scattering coefficient defined so that (1 - eta(P)) is the amount of energy scattered in the forward peak. Then, to cope with nonconstant backscattering functions, we discuss the introduction of an effective backscattering coefficient that is an average of the scattering probabilities around pi.
Electric field autocorrelation functions for beginning multiple rayleigh scattering.
Lock, J A
2001-08-20
The polarization-resolved electric field autocorrelation function for p-order scattering was derived from the order-of-scattering solution of the exact equations for electromagnetic multiple Rayleigh scattering and was calculated for 2 scattering-angle dependence of the p-order autocorrelation function approximately decoupled from the delay-time dependence for p ? 3. The polarization-channel and the scattering-angle dependence were analytically calculated, and the delay-time dependence was analytically approximated. The resulting analytical model for the polarization-resolved autocorrelation function for beginning multiple Rayleigh scattering was then tested against experimental autocorrelation data. The data were found to be well fitted by the model.
Electric Field Autocorrelation Functions for Beginning Multiple Rayleigh Scattering
NASA Astrophysics Data System (ADS)
Lock, James A.
2001-08-01
The polarization-resolved electric field autocorrelation function for p -order scattering was derived from the order-of-scattering solution of the exact equations for electromagnetic multiple Rayleigh scattering and was calculated for 2 p 6 for particles undergoing diffusive motion in an idealized sample cell. It was found that the polarization-channel and the scattering-angle dependence of the p -order autocorrelation function approximately decoupled from the delay-time dependence for p ~ 3 . The polarization-channel and the scattering-angle dependence were analytically calculated, and the delay-time dependence was analytically approximated. The resulting analytical model for the polarization-resolved autocorrelation function for beginning multiple Rayleigh scattering was then tested against experimental autocorrelation data. The data were found to be well fitted by the model.
Multiple-Fiber-Optic Probe For Light-Scattering Measurements
NASA Technical Reports Server (NTRS)
Dhadwal, Harbans Singh; Ansari, Rafat R.
1996-01-01
Multiple-fiber-optical probe developed for use in measuring light scattered at various angles from specimens of materials. Designed for both static and dynamic light-scattering measurements of colloidal dispersions. Probe compact, rugged unit containing no moving parts and remains stationary during operation. Not restricted to operation in controlled, research-laboratory environment. Positioned inside or outside light-scattering chamber. Provides simultaneous measurements at small angular intervals over range of angles, made to include small scattering angles by orienting probe in appropriate direction.
Method for measuring multiple scattering corrections between liquid scintillators
Verbeke, J. M.; Glenn, A. M.; Keefer, G. J.; Wurtz, R. E.
2016-04-11
In this study, a time-of-flight method is proposed to experimentally quantify the fractions of neutrons scattering between scintillators. An array of scintillators is characterized in terms of crosstalk with this method by measuring a californium source, for different neutron energy thresholds. The spectral information recorded by the scintillators can be used to estimate the fractions of neutrons multiple scattering. With the help of a correction to Feynman's point model theory to account for multiple scattering, these fractions can in turn improve the mass reconstruction of fissile materials under investigation.
Method for measuring multiple scattering corrections between liquid scintillators
NASA Astrophysics Data System (ADS)
Verbeke, J. M.; Glenn, A. M.; Keefer, G. J.; Wurtz, R. E.
2016-07-01
A time-of-flight method is proposed to experimentally quantify the fractions of neutrons scattering between scintillators. An array of scintillators is characterized in terms of crosstalk with this method by measuring a californium source, for different neutron energy thresholds. The spectral information recorded by the scintillators can be used to estimate the fractions of neutrons multiple scattering. With the help of a correction to Feynman's point model theory to account for multiple scattering, these fractions can in turn improve the mass reconstruction of fissile materials under investigation.
Method for measuring multiple scattering corrections between liquid scintillators
Verbeke, J. M.; Glenn, A. M.; Keefer, G. J.; ...
2016-04-11
In this study, a time-of-flight method is proposed to experimentally quantify the fractions of neutrons scattering between scintillators. An array of scintillators is characterized in terms of crosstalk with this method by measuring a californium source, for different neutron energy thresholds. The spectral information recorded by the scintillators can be used to estimate the fractions of neutrons multiple scattering. With the help of a correction to Feynman's point model theory to account for multiple scattering, these fractions can in turn improve the mass reconstruction of fissile materials under investigation.
Atmospheric multiple scattering of a vertically directed laser beam
NASA Astrophysics Data System (ADS)
Malacari, M.; Dawson, B. R.
2017-07-01
Vertical laser beams are often used at ground-based cosmic ray observatories employing the fluorescence technique for characterizing the height-dependent properties of the atmosphere, as well as for calibration and telescope alignment studies. The light flux received at a detector from a laser is typically assumed to be only singly scattered out of the beam, with no possibility for the multiple scattering of photons initially scattered in other directions back into the detector's field of view. We present the results of a new simulation for the scattering of light from a vertically-directed laser beam, and derive a parametrization for the multiple scattered signal expected at a detector from such a source as a function of the prevailing atmospheric conditions. The parametrization is then used to estimate the increase in the reconstructed height-dependent aerosol loading when recovered using a laser-based technique.
NASA Astrophysics Data System (ADS)
Kiran, K. U.; Ravindraswami, K.; Eshwarappa, K. M.; Somashekarappa, H. M.
2016-02-01
Multiple scattering of gamma photons obtained from 0.215 GBq 137Cs source in both forward and backward hemisphere for 4 elements viz., carbon, aluminium, iron and copper are detected by a 76 mm ×76 mm NaI(Tl) scintillation detector. The variation of saturation thicknesses of 4 elements are studied experimentally at 60°, 80°, 90°, 100°, 120° and 135°. Monte Carlo N-Particle (MCNP) simulation of multiple scattering and variation in saturation thicknesses is carried out for 40°, 60°, 80°, 90°, 100°, 120°, 135°, 160° and 180° for four elements. The variation of the intensity of multiple scattered photons in different scattering angles is found to be different in forward and backward hemispheres. The intensity of multiple scattered photons is found to be minimum at around 90°. Saturation thicknesses for 40° and 60° are found to be less than saturation thicknesses for 80°, 90°, 100°, 120°, 135°, 160° and 180° in spite of the fact that the scattered energy is more for lower scattering angles. The behaviour of variation of saturation thicknesses as a function of scattering angles obtained from MCNP simulation agrees well with experimentally obtained values.
Multiple scattering induced negative refraction of matter waves.
Pinsker, Florian
2016-02-09
Starting from fundamental multiple scattering theory it is shown that negative refraction indices are feasible for matter waves passing a well-defined ensemble of scatterers. A simple approach to this topic is presented and explicit examples for systems of scatterers in 1D and 3D are stated that imply negative refraction for a generic incoming quantum wave packet. Essential features of the effective scattering field, densities and frequency spectrum of scatterers are considered. Additionally it is shown that negative refraction indices allow perfect transmission of the wave passing the ensemble of scatterers. Finally the concept of the superlens is discussed, since it is based on negative refraction and can be extended to matter waves utilizing the observations presented in this paper which thus paves the way to 'untouchable' quantum systems in analogy to cloaking devices for electromagnetic waves.
Multiple scattering induced negative refraction of matter waves
Pinsker, Florian
2016-01-01
Starting from fundamental multiple scattering theory it is shown that negative refraction indices are feasible for matter waves passing a well-defined ensemble of scatterers. A simple approach to this topic is presented and explicit examples for systems of scatterers in 1D and 3D are stated that imply negative refraction for a generic incoming quantum wave packet. Essential features of the effective scattering field, densities and frequency spectrum of scatterers are considered. Additionally it is shown that negative refraction indices allow perfect transmission of the wave passing the ensemble of scatterers. Finally the concept of the superlens is discussed, since it is based on negative refraction and can be extended to matter waves utilizing the observations presented in this paper which thus paves the way to ‘untouchable’ quantum systems in analogy to cloaking devices for electromagnetic waves. PMID:26857266
Markov chain solution of photon multiple scattering through turbid slabs.
Lin, Ying; Northrop, William F; Li, Xuesong
2016-11-14
This work introduces a Markov Chain solution to model photon multiple scattering through turbid slabs via anisotropic scattering process, i.e., Mie scattering. Results show that the proposed Markov Chain model agree with commonly used Monte Carlo simulation for various mediums such as medium with non-uniform phase functions and absorbing medium. The proposed Markov Chain solution method successfully converts the complex multiple scattering problem with practical phase functions into a matrix form and solves transmitted/reflected photon angular distributions by matrix multiplications. Such characteristics would potentially allow practical inversions by matrix manipulation or stochastic algorithms where widely applied stochastic methods such as Monte Carlo simulations usually fail, and thus enable practical diagnostics reconstructions such as medical diagnosis, spray analysis, and atmosphere sciences.
Correlations in multiple production in nuclei and the Glauber model for multiple scattering
Zoller, V.R.; Nikolayev, N.N.
1982-10-01
The Capella-Krzywicki-Shabelskii extension of the Glauber multiple-scattering model to the multiple production of particles in nuclei is applied to the description of correlation phenomena and analyzed critically.
NASA Astrophysics Data System (ADS)
Gruber, Fred K.; Marengo, Edwin A.; Devaney, Anthony J.
2004-06-01
The time-reversal imaging with multiple signal classification method for the location of point targets developed within the framework of the Born approximation in Lehman and Devaney [``Transmission mode time-reversal super-resolution imaging,'' J. Acoust. Soc. Am. 113, 2742-2753 (2003)] is generalized to incorporate multiple scattering between the targets. It is shown how the same method can be used in the location of point targets even if there is multiple scattering between them. On the other hand, both the conventional images and the calculated values of the target scattering amplitudes are scattering model-dependent.
Effect of multiple scattering on depolarization measurements with spaceborne lidars.
Reichardt, Susanne; Reichardt, Jens
2003-06-20
An analytical model based on the integration of the scattering-angle and light-path manifold has been developed to quantify the effect of multiple scattering on cirrus measurements obtained with elastic polarization lidars from space. Light scattering by molecules and by a horizontally homogeneous cloud is taken into account. Lidar parameter, including laser beam divergence, can be freely chosen. Up to 3 orders of scattering are calculated. Furthermore, an inversion technique for the retrieval of cloud extinction profiles from measurements with elastic-backscatter lidars is proposed that explicitly takes multiple scattering into account. It is found that for typical lidar system parameters such as those of the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) instrument multiple scattering does not significantly affect depolarization-ratio measurements in cirrus clouds with small to moderate optical depths. For all simulated clouds, the absolute value of the difference between measured and single-scattering volume depolarization ratio is < 0.006. The particle depolarization ratio can be calculated from the measured volume depolarization ratio and the retrieved backscatter ratio without degradation of accuracy; thus characterization of the various cirrus categories in terms of the particle depolarization ratio and retrieval of cloud microphysical properties is feasible from space. The results of this study apply to polar stratospheric clouds as well.
Analysis of multiple scattering effects in optical Doppler tomography
NASA Astrophysics Data System (ADS)
Yura, Harold T.; Thrane, Lars; Andersen, Peter E.
2005-08-01
Optical Doppler tomography (ODT) combines Doppler velocimetry and optical coherence tomography (OCT) to obtain high-resolution cross-sectional imaging of particle flow velocity in scattering media such as the human retina and skin. Here, we present the results of a theoretical analysis of ODT where multiple scattering effects are included. The purpose of this analysis is to determine how multiple scattering affects the estimation of the depth-resolved localized flow velocity. Depth-resolved velocity estimates are obtained directly from the corresponding mean or standard deviation of the observed Doppler frequency spectrum. Thus, in the present analysis, the dependence of the mean and standard deviation of the Doppler shift on the scattering properties of the flowing medium are obtained. Taking the multiple scattering effects into account, we are able to explain previous measurements of depth-resolved retinal flow profiles where the influence of multiple scattering was observed [Yazdanfar et al., Opt. Lett. 25, 1448 (2000)]. To the best of our knowledge, no analytical model exists that are able to explain these observations.
Analysis of multiple scattering effects in optical Doppler tomography
NASA Astrophysics Data System (ADS)
Yura, Harold T.; Thrane, Lars; Andersen, Peter E.
2005-04-01
Optical Doppler tomography (ODT) combines Doppler velocimetry and optical coherence tomography (OCT) to obtain high-resolution cross-sectional imaging of particle flow velocity in scattering media such as the human retina and skin. Here, we present the results of a theoretical analysis of ODT where multiple scattering effects are included. The purpose of this analysis is to determine how multiple scattering affects the estimation of the depth-resolved localized flow velocity. Depth-resolved velocity estimates are obtained directly from the corresponding mean or standard deviation of the observed Doppler frequency spectrum. Thus, in the present analysis, the dependence of the mean and standard deviation of the Doppler shift on the scattering properties of the flowing medium are obtained. Taking the multiple scattering effects into account, we are able to explain previous measurements of depth-resolved retinal flow profiles where the influence of multiple scattering was observed [Yazdanfar et al., Opt. Lett. 25, 1448 (2000)]. To the best of our knowledge, no analytical model exists that are able to explain these observations.
A covariant multiple scattering series for elastic projectile-target scattering
NASA Technical Reports Server (NTRS)
Gross, Franz; Maung-Maung, Khin
1989-01-01
A covariant formulation of the multiple scattering series for the optical potential is presented. The case of a scalar nucleon interacting with a spin zero isospin zero A-body target through meson exchange, is considered. It is shown that a covariant equation for the projectile-target t-matrix can be obtained which sums the ladder and crossed ladder diagrams efficiently. From this equation, a multiple scattering series for the optical potential is derived, and it is shown that in the impulse approximation, the two-body t-matrix associated with the first order optical potential is the one in which one particle is kept on mass-shell. The meaning of various terms in the multiple scattering series is given. The construction of the first-order optical potential for elastic scattering calculations is described.
Multiple parton scattering in nuclei: Parton energy loss
Wang, Xin-Nian; Guo, Xiao-feng
2001-02-17
Multiple parton scattering and induced parton energy loss are studied in deeply inelastic scattering (DIS) off nuclei. The effect of multiple scattering of a highly off-shell quark and the induced parton energy loss is expressed in terms of the modification to the quark fragmentation functions. The authors derive such modified quark fragmentation functions and their QCD evolution equations in DIS using the generalized factorization of higher twist parton distributions. They consider double-hard and hard-soft parton scattering as well as their interferences in the same framework. The final result, which depends on both the diagonal and off-diagonal twist-four parton distributions in nuclei, demonstrates clearly the Landau-Pomeranchuk-Migdal interference features and predicts a unique nuclear modification of the quark fragmentation functions.
Bright-White Beetle Scales Optimise Multiple Scattering of Light
Burresi, Matteo; Cortese, Lorenzo; Pattelli, Lorenzo; Kolle, Mathias; Vukusic, Peter; Wiersma, Diederik S.; Steiner, Ullrich; Vignolini, Silvia
2014-01-01
Whiteness arises from diffuse and broadband reflection of light typically achieved through optical scattering in randomly structured media. In contrast to structural colour due to coherent scattering, white appearance generally requires a relatively thick system comprising randomly positioned high refractive-index scattering centres. Here, we show that the exceptionally bright white appearance of Cyphochilus and Lepidiota stigma beetles arises from a remarkably optimised anisotropy of intra-scale chitin networks, which act as a dense scattering media. Using time-resolved measurements, we show that light propagating in the scales of the beetles undergoes pronounced multiple scattering that is associated with the lowest transport mean free path reported to date for low-refractive-index systems. Our light transport investigation unveil high level of optimisation that achieves high-brightness white in a thin low-mass-per-unit-area anisotropic disordered nanostructure. PMID:25123449
Bright-White Beetle Scales Optimise Multiple Scattering of Light
NASA Astrophysics Data System (ADS)
Burresi, Matteo; Cortese, Lorenzo; Pattelli, Lorenzo; Kolle, Mathias; Vukusic, Peter; Wiersma, Diederik S.; Steiner, Ullrich; Vignolini, Silvia
2014-08-01
Whiteness arises from diffuse and broadband reflection of light typically achieved through optical scattering in randomly structured media. In contrast to structural colour due to coherent scattering, white appearance generally requires a relatively thick system comprising randomly positioned high refractive-index scattering centres. Here, we show that the exceptionally bright white appearance of Cyphochilus and Lepidiota stigma beetles arises from a remarkably optimised anisotropy of intra-scale chitin networks, which act as a dense scattering media. Using time-resolved measurements, we show that light propagating in the scales of the beetles undergoes pronounced multiple scattering that is associated with the lowest transport mean free path reported to date for low-refractive-index systems. Our light transport investigation unveil high level of optimisation that achieves high-brightness white in a thin low-mass-per-unit-area anisotropic disordered nanostructure.
Efficient light propagation for multiple anisotropic volume scattering
Max, N. |
1993-12-01
Realistic rendering of participating media like clouds requires multiple anisotropic light scattering. This paper presents a propagation approximation for light scattered into M direction bins, which reduces the ``ray effect`` problem in the traditional ``discrete ordinates`` method. For a volume of n{sup 3} elements, it takes O(M n{sup 3} log n + M{sup 2} n{sup 3}) time and O(M n{sup 3}) space.
Role of multiple scattering in formation of OCT skin images
Kirillin, M Yu; Priezzhev, A V; Myllylae, R
2008-06-30
Optical coherence tomography (OCT) images of model human skin samples are obtained by using Monte Carlo simulations. The contributions of least and multiple scattering, diffusion and nondiffusion components and of separate scattering orders are studied by using a multilayer skin model based on experimental images. The model images are obtained by neglecting speckles or taking them into account. It is shown that least scattering forms the image of the upper skin layers, while the contribution of multiple scattering can be characterised as a blurred full image with a lower contrast. Repeated scattering mainly contributes to the OCT image at depths up to 1 mm. The diffusion component contributes to the image beginning from the epidermal basal layer. The partial image produced by this component is more blurred compared to the partial image produced by to multiple scattering. The nondiffusion component forms the OCT skin image at depths up to {approx}1.3 mm. (special issue devoted to application of laser technologies in biophotonics and biomedical studies)
Laser Light Scattering with Multiple Scattering Suppression Used to Measure Particle Sizes
NASA Technical Reports Server (NTRS)
Meyer, William V.; Tin, Padetha; Lock, James A.; Cannell, David S.; Smart, Anthony E.; Taylor, Thomas W.
1999-01-01
Laser light scattering is the technique of choice for noninvasively sizing particles in a fluid. The members of the Advanced Technology Development (ATD) project in laser light scattering at the NASA Lewis Research Center have invented, tested, and recently enhanced a simple and elegant way to extend the concentration range of this standard laboratory particle-sizing technique by several orders of magnitude. With this technique, particles from 3 nm to 3 mm can be measured in a solution. Recently, laser light scattering evolved to successfully size particles in both clear solutions and concentrated milky-white solutions. The enhanced technique uses the property of light that causes it to form tall interference patterns at right angles to the scattering plane (perpendicular to the laser beam) when it is scattered from a narrow laser beam. Such multiple-scattered light forms a broad fuzzy halo around the focused beam, which, in turn, forms short interference patterns. By placing two fiber optics on top of each other and perpendicular to the laser beam (see the drawing), and then cross-correlating the signals they produce, only the tall interference patterns formed by singly scattered light are detected. To restate this, unless the two fiber optics see the same interference pattern, the scattered light is not incorporated into the signal. With this technique, only singly scattered light is seen (multiple-scattered light is rejected) because only singly scattered light has an interference pattern tall enough to span both of the fiber-optic pickups. This technique is simple to use, easy to align, and works at any angle. Placing a vertical slit in front of the signal collection fibers enhanced this approach. The slit serves as an optical mask, and it significantly shortens the time needed to collect good data by selectively masking out much of the unwanted light before cross-correlation is applied.
Collective hypersonic excitations in strongly multiple scattering colloids.
Still, T; Gantzounis, G; Kiefer, D; Hellmann, G; Sainidou, R; Fytas, G; Stefanou, N
2011-04-29
Unprecedented low-dispersion high-frequency acoustic excitations are observed in dense suspensions of elastically hard colloids. The experimental phononic band structure for SiO(2) particles with different sizes and volume fractions is well represented by rigorous full-elastodynamic multiple-scattering calculations. The slow phonons, which do not relate to particle resonances, are localized in the surrounding liquid medium and stem from coherent multiple scattering that becomes strong in the close-packing regime. Such rich phonon-matter interactions in nanostructures, being still unexplored, can open new opportunities in phononics.
An empirical correction for moderate multiple scattering in super-heterodyne light scattering.
Botin, Denis; Mapa, Ludmila Marotta; Schweinfurth, Holger; Sieber, Bastian; Wittenberg, Christopher; Palberg, Thomas
2017-05-28
Frequency domain super-heterodyne laser light scattering is utilized in a low angle integral measurement configuration to determine flow and diffusion in charged sphere suspensions showing moderate to strong multiple scattering. We introduce an empirical correction to subtract the multiple scattering background and isolate the singly scattered light. We demonstrate the excellent feasibility of this simple approach for turbid suspensions of transmittance T ≥ 0.4. We study the particle concentration dependence of the electro-kinetic mobility in low salt aqueous suspension over an extended concentration regime and observe a maximum at intermediate concentrations. We further use our scheme for measurements of the self-diffusion coefficients in the fluid samples in the absence or presence of shear, as well as in polycrystalline samples during crystallization and coarsening. We discuss the scope and limits of our approach as well as possible future applications.
NASA Astrophysics Data System (ADS)
Deharak, B. A.; Savich, J. L.; Roberts, H. M.; Brown, E. G.; McGill, M. R.; Kim, B. N.; Weaver, C. M.; Martin, N. L. S.
2016-05-01
We have conducted a series of Monte Carlo simulations of laser assisted free-free scattering experiments. The simulations make use of Kroll-Watson approximation to account for the effects of the laser field on the scattering process. The parameters for these simulations are believed to mimic the experimental conditions of the work reported by Wallbank and Holmes, particularly the target number density. The simulations account for the effects multiple scattering (i.e., the scattering of a single incident electron from multiple target atoms). We present a comparison of the results of these simulations to the experimental results of Wallbank and Holmes. This work was supported by the National Science Foundation under Grants Nos. PHY-0855040 (NLSM) and PHY-1402899 (BAd).
An empirical correction for moderate multiple scattering in super-heterodyne light scattering
NASA Astrophysics Data System (ADS)
Botin, Denis; Mapa, Ludmila Marotta; Schweinfurth, Holger; Sieber, Bastian; Wittenberg, Christopher; Palberg, Thomas
2017-05-01
Frequency domain super-heterodyne laser light scattering is utilized in a low angle integral measurement configuration to determine flow and diffusion in charged sphere suspensions showing moderate to strong multiple scattering. We introduce an empirical correction to subtract the multiple scattering background and isolate the singly scattered light. We demonstrate the excellent feasibility of this simple approach for turbid suspensions of transmittance T ≥ 0.4. We study the particle concentration dependence of the electro-kinetic mobility in low salt aqueous suspension over an extended concentration regime and observe a maximum at intermediate concentrations. We further use our scheme for measurements of the self-diffusion coefficients in the fluid samples in the absence or presence of shear, as well as in polycrystalline samples during crystallization and coarsening. We discuss the scope and limits of our approach as well as possible future applications.
Single and Multiple Scattering Components of the Surface Current for Rough Surface Scattering
NASA Technical Reports Server (NTRS)
Rodriguez, Ernesto
1996-01-01
A method is presented for separating the single and multiple scattering contributions to the surface current which is valid up to the second order in perturbation theory. Using this method, numerical experiments are performed to determine the spectral characteristics of the surface current as a function of incidence angle and surface roughness for long random periodic gratings. It is shown that, as theincidence angle increases, the single scattering contribution shows a dependence on surface slope which is hot present in current perturbation theories.
Multiple light scattering methods for multiphase flow diagnostics
NASA Astrophysics Data System (ADS)
Estevadeordal, Jordi
2015-11-01
Multiphase flows of gases and liquids containing droplets, bubbles, or particulates present light scattering imaging challenges due to the interference from each phase, such as secondary reflections, extinctions, absorptions, and refractions. These factors often prevent the unambiguous detection of each phase and also produce undesired beam steering. The effects can be especially complex in presence of dense phases, multispecies flows, and high pressure environments. This investigation reports new methods for overcoming these effects for quantitative measurements of velocity, density, and temperature fields. The methods are based on light scattering techniques combining Mie and filtered Rayleigh scattering and light extinction analyses and measurements. The optical layout is designed to perform multiple property measurements with improved signal from each phase via laser spectral and polarization characterization, etalon decontamination, and use of multiple wavelengths and imaging detectors.
Joelson, B D; Kattawar, G W
1996-05-20
Monte Carlo calculations have been performed to investigate the effect of multiple scattering on the frequency spectra caused by Brillouin scattering in the ocean. It is shown that the use of the frequency spectra to determine the speed of sound profile and the hydrosol backscattering probability is stable under multiple scattering because the problem is limited to single backscattering events.
Stimulated Raman scattering of laser dye mixtures dissolved in multiple scattering media
Yashchuk, V P; Komyshan, A O; Tikhonov, E A; Olkhovyk, L A
2014-10-31
Stimulated Raman scattering (SRS) of a mixture of rhodamine 6G and pyrromethene 605 laser dyes in vesicular films is studied. It is shown that a peculiar interaction of dyes occurs under conditions of multiple scattering of light from vesicles. This interaction manifests itself as SRS excitation of one of the dyes by random lasing of the other dye, provided that the random lasing spectrum overlaps the Stokes lines of the first dye. In addition, there is energy transfer between molecules of these dyes if their luminescence and absorption spectra overlap. The results obtained confirm that the mechanism of SRS from laser dyes in multiple scattering media is similar to that in coherent-active Raman spectroscopy. These results extend the possibility of determining the vibrational spectrum of dye molecules from their secondary radiation in these media. (nonlinear optical phenomena)
Relativistic real-space multiple scattering calculations of EELS
NASA Astrophysics Data System (ADS)
Jorissen, K.; Rehr, J. J.; Sorini, A.; Levine, Z. H.
2006-03-01
We present an extension of the real space multiple scattering code FEFF8 for ab initio, relativistic calculations of electron energy loss spectra (EELS), which is applicable both to periodic and non-periodic systems. The approach explains the observed relativistic shifts in the magic angle. In addition, the method can account for experimental parameters such as collection and convergence angles of the microscope and sample orientation. We also discuss relativistic effects on inelastic electron scattering including the density correction to the stopping power. Our results are compared with other approaches and with experiment. B. Jouffrey, P. Schattschneider and C. Hebert, Ultramicroscopy 102, 61 (2004).
Multiple scattering measurements in laboratory and foggy atmosphere
NASA Technical Reports Server (NTRS)
Bruscaglioni, P.; Battistelli, E.; Pili, P.; Zaccanti, C.
1986-01-01
Multiple scattering affects propagation of light beams in turbid media. Backscattering or forward scattering based measurements of atmospheric parameters are influenced by this effect. Although largely studied theoretically, the effect needs measurements in control of situations due to the large variety of situations of practical importance. The results of laboratory measurements pertaining to the transmission of a collimated light beam (Helium-Neon souce, 10 mW) through suspensions of latex spheres in water are presented and a comparison was made with the predictions of calculation in a foggy atmosphere will also be presented.
Diffusion and multiple anisotropic scattering for global illumination in clouds
Max, N L; Schussman, G; Miyazaki, R; Iwasaki, K; Nishita, T
2003-10-14
The diffusion method is a good approximation inside the dense core of a cloud, but not at the more tenuous boundary regions. Also, it breaks down in regions where the density of scattering droplets is zero. We have enhanced it by using hardware cell projection volume rendering at cloud border voxels to account for the straight line light transport across these empty regions. We have also used this hardware volume rendering at key voxels in the low-density boundary regions to account for the multiple anisotropic scattering of the environment.
Multiple-Point Mass Flux Measurement System Using Rayleigh Scattering
NASA Technical Reports Server (NTRS)
Mielke, Amy F.; Elam, Kristie A.; Clem, Michelle M.
2009-01-01
A multiple-point Rayleigh scattering diagnostic is being developed to provide mass flux measurements in gas flows. Spectroscopic Rayleigh scattering is an established flow diagnostic that has the ability to provide simultaneous density, temperature, and velocity measurements. Rayleigh scattered light from a focused 18 Watt continuous-wave laser beam is directly imaged through a solid Fabry-Perot etalon onto a CCD detector which permits spectral analysis of the light. The spatial resolution of the measurements is governed by the locations of interference fringes, which can be changed by altering the etalon characteristics. A prototype system has been used to acquire data in a Mach 0.56 flow to demonstrate feasibility of using this system to provide mass flux measurements. Estimates of measurement uncertainty and recommendations for system improvements are presented
Influence of multiple scattering effects on in vivo NIR spectroscopy
NASA Astrophysics Data System (ADS)
Du, Chongwu; Nahm, Werner
1995-01-01
On the basis of both homogeneous and layered skin models this paper analyzes the influences of multiple scattering of skin on the measurements of NIR spectroscopy. Emphasis is laid on the wavelengths of 660, 805, and 940 nm which are used in clinical monitoring systems. The results of Monte-Carlo simulation show that the overwhelming scattering of tissue leads to a nonlinearity in the Lambert-Beer's relation between optical density and chromophore concentration. The consequences of this effect shall be discussed using as an example the non invasive measurement of Indocyanine Green (ICG) in the blood. In this case the multiple scattering of skin causes substantial non-linear relation between the optical density at 805 nm and the concentration of an injected NIR dye in the blood if the concentration of ICG exceeds 10 mg/l. This leads to a significant distortion of the ICG clearance curve and in consequence to a systematic error in the determination of physiological parameters. For multi-wavelength spectroscopy the wavelength dependency of scattering coefficients has to be noticed. The consequence of this effect is demonstrated for blood oxygen saturation (SaO2) measurements.
Does the multiple-scattering series in the pion-deuteron scattering actually converge?
Kudryavtsev, A. E. Romanov, A. I. Gani, V. A.
2013-07-15
It is demonstrated that the well-known answer for the multiple-scattering series (MSS) for a light particle interacting to a pair of static nucleons, calculated in the Fixed Centers Approximation (FCA), works well for a wide region of the two-body complex scattering length a. However, this approach is not applicable in a narrow region surrounding the real positive a half-axis, where the MSS does not converge. Simultaneously, for real positive a's the 3-body system forms an infinite set of bound states.
MODTRAN cloud and multiple scattering upgrades with application to AVIRIS
Berk, A.; Bernstein, L.S.; Acharya, P.K.; Robertson, D.C.; Adler-Golden, S.M.; Anderson, G.P.; Chetwynd, J.H.
1998-09-01
Recent upgrades to the MODTRAN atmospheric radiation code improve the accuracy of its radiance predictions, especially in the presence of clouds and thick aerosols, and for multiple scattering in regions of strong molecular line absorption. The current public-released version of MODTRAN (MODTRAN3.7) features a generalized specification of cloud properties, while the current research version of MODTRAN (MODTRAN4) implements a correlated-k (CK) approach for more accurate calculation of multiple scattered radiance. Comparisons to cloud measurements demonstrate the viability of the CK approach. The impact of these upgrades on predictions for AVIRIS viewing scenarios is discussed for both clear and clouded skies; the CK approach provides refined predictions for AVIRIS nadir and near-nadir viewing.
Multiple-scattering corrections to the Beer-Lambert law
Zardecki, A.
1983-01-01
The effect of multiple scattering on the validity of the Beer-Lambert law is discussed for a wide range of particle-size parameters and optical depths. To predict the amount of received radiant power, appropriate correction terms are introduced. For particles larger than or comparable to the wavelength of radiation, the small-angle approximation is adequate; whereas for small densely packed particles, the diffusion theory is advantageously employed. These two approaches are used in the context of the problem of laser-beam propagation in a dense aerosol medium. In addition, preliminary results obtained by using a two-dimensional finite-element discrete-ordinates transport code are described. Multiple-scattering effects for laser propagation in fog, cloud, rain, and aerosol cloud are modeled.
Electronic states of doped semiconductors: A multiple scattering approach
NASA Astrophysics Data System (ADS)
Ghazali, A.; Serre, J.
1983-03-01
The electronic structure of doped (and compensated) semiconductors is studied by using the Klauder's best multiple-scattering approximation. Electron correlations are also included. It is shown that as the impurity concentration is decreased, the band tail gradually splits off from the main band giving an impurity band. The domains of existence of extended states and localized states have been recognized by analyzing the shape of spectral densities. Lastly, our results are confronted with various experiments.
Loopy MSC: a simple way to improve multiplicative scatter correction.
Windig, Willem; Shaver, Jeremy; Bro, Rasmus
2008-10-01
Multiplicative scatter correction (MSC) is a widely used normalization technique. It aims to correct spectra in such a way that they are as close as possible to a reference spectrum, generally the mean of the data set, by changing the scale and the offset of the spectra. When there are other differences in the spectra than just a scale and an offset, the mean spectrum changes after MSC. As a result, another MSC, with the new mean spectrum as the reference, will result in an additional correction. This paper studies the effect of multiple applications of MSC.
Application of multiple scattering theory to lower-energy elastic nucleon-nucleus scattering
NASA Astrophysics Data System (ADS)
Chinn, C. R.; Elster, Ch.; Thaler, R. M.; Weppner, S. P.
1995-03-01
The optical model potentials for nucleon-nucleus elastic scattering at 65 meV are calculated for 12C, 16O, 28Si, 40Ca, 56Fe, 90Zr, and 208Pb in first-order multiple scattering theory, following the prescription of the spectator expansion, where the only inputs are the free nucleon-nucleon (NN) potentials, the nuclear densities, and the nuclear mean field as derived from microscopic nuclear structure calculations. These potentials are used to predict differential cross sections, analyzing powers, and spin rotation functions for neutron and proton scattering at 65 MeV projectile energy and compared with available experimental data. The theoretical curves are in very good agreement with the data. The modification of the propagator due to the coupling of the struck nucleon to the residual nucleus is seen to be significant at this energy and invariably improves the congruence of theoretical prediction and measurement.
NASA Astrophysics Data System (ADS)
Nakatsuka, Takao; Nishimura, Jun
2008-08-01
The Molière theory of multiple Coulomb scattering is improved to take account of ionization loss by applying a differential formulation of the theory. Distributions for the deflection angle θ⃗ , as well as for any linear combination between θ⃗ and the lateral displacement r⃗ , under the ionization process are derived by a series expansion with the same universal functions f(n)(ϑ) of Molière, except that the values for both the expansion parameter B and the scale angle θM are corrected from those under the fixed-energy process. We find that Goudsmit-Saunderson angular distribution with ionization is also expressed by the same characteristic parameters B and θM derived above by the Molière theory. The transport mechanism of Molière process of multiple Coulomb scattering and the stochastic property of Molière series expansion are also investigated and discussed.
Imaging depth and multiple scattering in laser speckle contrast imaging
Davis, Mitchell A.; Kazmi, S. M. Shams; Dunn, Andrew K.
2014-01-01
Abstract. Laser speckle contrast imaging (LSCI) is a powerful and simple method for full field imaging of blood flow. However, the depth dependence and the degree of multiple scattering have not been thoroughly investigated. We employ three-dimensional Monte Carlo simulations of photon propagation combined with high resolution vascular anatomy to investigate these two issues. We found that 95% of the detected signal comes from the top 700 μm of tissue. Additionally, we observed that single-intravascular scattering is an accurate description of photon sampling dynamics, but that regions of interest (ROIs) in areas free of obvious surface vessels had fewer intravascular scattering events than ROI over resolved surface vessels. Furthermore, we observed that the local vascular anatomy can strongly affect the depth dependence of LSCI. We performed simulations over a wide range of intravascular and extravascular scattering properties to confirm the applicability of these results to LSCI imaging over a wide range of visible and near-infrared wavelengths. PMID:25089945
Green Function Calculation for Full-potential Multiple Scattering Methods
NASA Astrophysics Data System (ADS)
Wang, Yang; Stocks, G. Malcolm; Nicholson, Don
2001-03-01
The Green function in the multiple scattering theory of Korringa(J.Korringa, Physica) 13, 392 (1947)., Kohn and Rostoker(W.Kohn and N.Rostoker, Phys. Rev.) 94, 1111 (1954). provides a very convenient approach to the electronic structure calculation for solids. The Green function was originally developed for muffin-tin potentials(J.S. Faulkner and G.M. Stocks, Phys. Rev.) B 21, 3222 (1980)., but can be generalized to the full potential case in which the one-electron potential associated with each atom is of arbitrary geometric shape. In this talk, we present our numerical techniques for Green function calculation in our newly developed full potential multiple scattering method code. We test the calculated Green function against the analytical expression for the case of three dimensional space filling simple analytic potentials. We show how the surface integral technique is used for the calculation of the single site scattering matrices and irregular solutions. We also discuss the L-convergence properties of the Green function.
Locating a small change in a multiple scattering environment
NASA Astrophysics Data System (ADS)
Planes, T.; Larose, E. F.; Rossetto, V.; Margerin, L.
2011-12-01
We present an imaging technique allowing locating a small perturbation appearing in a multiple scattering environment. This technique is based on the direct dependence in space and time of the coda decorrelation resulting from the apparition of a supplementary scatterer, which one wishes to image. The inverse problem solution - the location of the defect - is obtained using a maximum likelihood computation. The LOCADIFF technique has been applied to locate a millimeter change in concrete using ultrasounds with a precision of the order of one centimeter [Larose et al., Appl. Phys. Lett. 2010]. The size of the defect is comparable to that of the heterogeneities constituting the sample. We are currently working on a similar technique to locate small velocity perturbations in heterogeneous media, with potential applications on monitoring volcanoes and active faults.
Effects of Multiple Scattering for Millimeter-Wavelength Weather Radars
NASA Technical Reports Server (NTRS)
Kobayashi, Satoru; Tanelli, Simone; Im, Eastwood
2004-01-01
Effects of multiple scattering on the reflectivity measurement for millimeter-wavelength weather radars are studied, in which backscattering enhancement may play an important role. In the previous works, the backscattering enhancement has been studied for plane wave injection, the reflection of which is received at the infinite distance. In this paper, a finite beam width of a Gaussian antenna pattern along with spherical wave is taken into account. A time-independent second order theory is derived for a single layer of clouds of a uniform density. The ordinary second-order scattering (ladder term) and the second-order backscattering enhancement (cross term) are derived for both the copolarized and cross-polarized waves.
Effects of Multiple Scattering for Millimeter-Wavelength Weather Radars
NASA Technical Reports Server (NTRS)
Kobayashi, Satoru; Tanelli, Simone; Im, Eastwood
2004-01-01
Effects of multiple scattering on the reflectivity measurement for millimeter-wavelength weather radars are studied, in which backscattering enhancement may play an important role. In the previous works, the backscattering enhancement has been studied for plane wave injection, the reflection of which is received at the infinite distance. In this paper, a finite beam width of a Gaussian antenna pattern along with spherical wave is taken into account. A time-independent second order theory is derived for a single layer of clouds of a uniform density. The ordinary second-order scattering (ladder term) and the second-order backscattering enhancement (cross term) are derived for both the copolarized and cross-polarized waves.
Multiple light scattering and absorption in reef-building corals.
Terán, Emiliano; Méndez, Eugenio R; Enríquez, Susana; Iglesias-Prieto, Roberto
2010-09-20
We present an experimental and numerical study of the effects of multiple scattering on the optical properties of reef-building corals. For this, we propose a simplified optical model of the coral and describe in some detail methods for characterizing the coral skeleton and the layer containing the symbiotic algae. The model is used to study the absorption of light by the layer of tissue containing the microalgae by means of Monte Carlo simulations. The results show that, through scattering, the skeleton homogenizes and enhances the light environment in which the symbionts live. We also present results that illustrate the modification of the internal light environment when the corals loose symbionts or pigmentation.
Crespo, R.; Deltuva, A.; Cravo, E.; Rodriguez-Gallardo, M.; Fonseca, A. C.
2008-02-15
Full Faddeev-type calculations are performed for {sup 11}Be breakup on a proton target at 38.4, 100, and 200 MeV/u incident energies. The convergence of the multiple scattering expansion is investigated. The results are compared with those of other frameworks like distorted-wave impulse approximation that are based on an incomplete and truncated multiple scattering expansion.
Light organization of small particles by multiple scattering
NASA Astrophysics Data System (ADS)
Hang, Zhi Hong
Optical manipulation is of broad interest in physics, chemistry, and biology. In the literature, most of the studies are focused on the optical trapping on a single object. In this thesis, we investigated the light-induced interaction of a collection of particles. The light-induced interaction between small particles was studied by a hierarchy of methods including the dipole theory, the multiple scattering and Maxwell stress tensor formalism, and the finite-difference-time-domain method. We showed that the multiple scattering between small particles could induce a binding mechanism to stabilize optically organized structures, but at the same time induced an intrinsic unbinding mechanism. The stability of optically organized structure was studied and a concept of "optical density" was introduced to gauge the destabilizing effect. We found that light-induced forces could bind dielectric spheres into extended structures through two mechanisms, each with its own length scale which could be adjusted by the configuration of the external light source. By manipulating the commensurability of the two length scales, these two mechanisms cooperated to bind a large number of spheres. When the two length scales became incommensurate for some particular incident angle, the competition between the two mechanisms led to modulated structures and other complex phenomena such as re-entrant stability. We searched for the possibility for stabilizing larger clusters. For this purpose, we found that circularly polarized light bound dielectric spheres into large-scale two-dimensional hexagonal lattice and multiple scattering also induced a rotation of optically bound structures. We searched for configurations that could induce optical trapping by field enhancement. Enhanced transmission on perforated metallic film system was studied. Surface modes bound on multi perforated perfect metal plate system were analytical solved and related to different high transmittance modes. Near
Assessment of Multiple Scattering Errors of Laser Diffraction Instruments
2003-03-17
Rosin - Rammler or log-normal size distribution. With the multiple scattering correction, the 2600c instrument has been reported to be accurate at...geared toward providing maximum accuracy in a volume mean diameter. Figures 2 and 3 are plots of percent error in measured D43 as a function of light...data is defined for the volume distribution as; = [ •(D)D(D- ,3• 1/ 2 Yr (D)-,3(D)3D43 eqn. (3) Figure 6 contains plots of measurement error, expressed
Proton radiography, nuclear cross sections and multiple Coulomb scattering
Sjue, Sky K.
2015-11-04
The principles behind proton radiography including multiple Coulomb scattering are discussed for a purely imaginary square well nucleus in the eikonal approximation. It is found that a very crude model can reproduce the angular dependence of the cross sections measured at 24 GeV/c. The largest differences are ~3% for the 4.56 mrad data, and ~4% for the 6.68 mrad data. The prospect of understanding how to model deterministically high-energy proton radiography over a very large range of energies is promising, but it should be tested more thoroughly.
Multiple scattering of light in three-dimensional photonic quasicrystals.
Ledermann, Alexandra; Wiersma, Diederik S; Wegener, Martin; von Freymann, Georg
2009-02-02
Recent experiments on three-dimensional icosahedral dielectric photonic quasicrystals have shown several unexpected features: transmitted femtosecond pulses developed a trailing "diffusive" exponential tail and the sum of (zeroth-order) transmittance and reflectance was well below unity. These experimental findings have previously been ascribed to sample imperfections. Here, we analyze these findings by using 3D periodic approximants of the ideal photonic quasicrystals. We show that the experimental observations can be explained in terms of multiple scattering of light within these structures, i.e., in terms of intrinsic rather than purely extrinsic quasicrystal properties.
Single and multiple intrabeam scattering in hadron colliders
Lebedev, V.; /Fermilab
2005-01-01
Single and multiple intra-beam scattering are usually considered separately. Such separation works well for electron-positron colliders but usually yields only coarse description in the case of hadron colliders. Boltzmann type integro-differential equation is used to describe evolution of longitudinal distribution due to IBS. The finite size of the longitudinal potential well, its non-linearity and x-y coupling are taken into account. The model predictions for longitudinal and transverse distributions are compared to the experimental measurements.
Multiple Scattering of Waves in Discrete Random Media.
1987-12-31
2.2 Material Properties for Piezoelectric Composites (SH Wave Incidence) Case I Case 2 P, (kg/m ) 6600 7000 3 1100 1000 c44 (N/nm) 8.5 x 109 8 .S x...patterns of R-1 and R.4 are presented as Figures 7 and 8 respectively. The matrix material was chosen to be PVC and the dielectric constant of PVC...PENNSYLVANIA STATE UNIVERSITY * RESEARCH CENTER FOR THE ENGINEERING OF ELECTRONIC & ACOUSTIC MATERIALS 00 Multiple Scattering of Waves 0 in Discrete
NASA Astrophysics Data System (ADS)
Yashchuk, Vasil P.
2015-07-01
Random lasing (RL) and stimulated Raman scattering (SRS) of dye in multiple scattering media (MSM) appears simultaneously and each couple with other. This coupling has considerable influence on the SRS regularities of dye in MSM. The main feature of this impact is that RL radiation promotes the Raman lines revealing in the RL spectrum range as part of total radiation. SRS initiation occurs owing to the CARS-like mechanism provided by the two component pump: incident monochromatic radiation (laser pump) and RL radiation arising inside the MSM. It leads to important consequences: the RL spectrum must overlap with the spectral region of the possible Stokes lines of the dye; only those Stokes lines appear which are in a range of the RL spectrum; all conditions which promote RL assist SRS also. It is shown MSM promotes the best conditions for SRS and RL coupling due to optimal matching of RL localization regions and pump radiation.
Gruenzweig, C.; Hils, T.; Muehlbauer, S.; Ay, M.; Lorenz, K.; Georgii, R.; Gaehler, R.; Boeni, P.
2007-11-12
We report on the demonstration experiment of the multiple small angle neutron scattering (MSANS) technique at a 5.6 m long neutron beam line, leading to a q resolution of 3x10{sup -4} A{sup -1}. The MSANS technique is based on two two-dimensional multihole apertures placed at the front end of the collimator and close to the sample, respectively. By choosing the proper MSANS geometry, individual diffraction patterns are superimposed leading to a large gain in intensity. Using MSANS as an option for standard small angle neutron scattering beam lines, the q resolution could be increased to 10{sup -5} A{sup -1} without dramatically sacrificing intensity.
Aethalometer multiple scattering correction Cref for mineral dust aerosols
NASA Astrophysics Data System (ADS)
Di Biagio, Claudia; Formenti, Paola; Cazaunau, Mathieu; Pangui, Edouard; Marchand, Nicolas; Doussin, Jean-François
2017-08-01
In this study we provide a first estimate of the Aethalometer multiple scattering correction Cref for mineral dust aerosols. Cref is an empirical constant used to correct the aerosol absorption coefficient measurements for the multiple scattering artefact of the Aethalometer; i.e. the filter fibres on which aerosols are deposited scatter light and this is miscounted as absorption. The Cref at 450 and 660 nm was obtained from the direct comparison of Aethalometer data (Magee Sci. AE31) with (i) the absorption coefficient calculated as the difference between the extinction and scattering coefficients measured by a Cavity Attenuated Phase Shift Extinction analyser (CAPS PMex) and a nephelometer respectively at 450 nm and (ii) the absorption coefficient from a MAAP (Multi-Angle Absorption Photometer) at 660 nm. Measurements were performed on seven dust aerosol samples generated in the laboratory by the mechanical shaking of natural parent soils issued from different source regions worldwide. The single scattering albedo (SSA) at 450 and 660 nm and the size distribution of the aerosols were also measured. Cref for mineral dust varies between 1.81 and 2.56 for a SSA of 0.85-0.96 at 450 nm and between 1.75 and 2.28 for a SSA of 0.98-0.99 at 660 nm. The calculated mean for dust is 2.09 (±0.22) at 450 nm and 1.92 (±0.17) at 660 nm. With this new Cref the dust absorption coefficient by the Aethalometer is about 2 % (450 nm) and 11 % (660 nm) higher than that obtained by using Cref = 2.14 at both 450 and 660 nm, as usually assumed in the literature. This difference induces a change of up to 3 % in the dust SSA at 660 nm. The Cref seems to be independent of the fine and coarse particle size fractions, and so the obtained Cref can be applied to dust both close to sources and following transport. Additional experiments performed with pure kaolinite minerals and polluted ambient aerosols indicate Cref of 2.49 (±0.02) and 2.32 (±0.01) at 450 and 660 nm (SSA = 0.96-0.97) for
A new three-dimensional track fit with multiple scattering
NASA Astrophysics Data System (ADS)
Berger, Niklaus; Kozlinskiy, Alexandr; Kiehn, Moritz; Schöning, André
2017-02-01
Modern semiconductor detectors allow for charged particle tracking with ever increasing position resolution. Due to the reduction of the spatial hit uncertainties, multiple Coulomb scattering in the detector layers becomes the dominant source for tracking uncertainties. In this case long distance effects can be ignored for the momentum measurement, and the track fit can consequently be formulated as a sum of independent fits to hit triplets. In this paper we present an analytical solution for a three-dimensional triplet(s) fit in a homogeneous magnetic field based on a multiple scattering model. Track fitting of hit triplets is performed using a linearization ansatz. The momentum resolution is discussed for a typical spectrometer setup. Furthermore the track fit is compared with other track fits for two different pixel detector geometries, namely the Mu3e experiment at PSI and a typical high-energy collider experiment. For a large momentum range the triplets fit provides a significantly better performance than a single helix fit. The triplets fit is fast and can easily be parallelized, which makes it ideal for the implementation on parallel computing architectures.
Fining of Red Wine Monitored by Multiple Light Scattering.
Ferrentino, Giovanna; Ramezani, Mohsen; Morozova, Ksenia; Hafner, Daniela; Pedri, Ulrich; Pixner, Konrad; Scampicchio, Matteo
2017-07-12
This work describes a new approach based on multiple light scattering to study red wine clarification processes. The whole spectral signal (1933 backscattering points along the length of each sample vial) were fitted by a multivariate kinetic model that was built with a three-step mechanism, implying (1) adsorption of wine colloids to fining agents, (2) aggregation into larger particles, and (3) sedimentation. Each step is characterized by a reaction rate constant. According to the first reaction, the results showed that gelatin was the most efficient fining agent, concerning the main objective, which was the clarification of the wine, and consequently the increase in its limpidity. Such a trend was also discussed in relation to the results achieved by nephelometry, total phenols, ζ-potential, color, sensory, and electronic nose analyses. Also, higher concentrations of the fining agent (from 5 to 30 g/100 L) or higher temperatures (from 10 to 20 °C) sped up the process. Finally, the advantage of using the whole spectral signal vs classical univariate approaches was demonstrated by comparing the uncertainty associated with the rate constants of the proposed kinetic model. Overall, multiple light scattering technique showed a great potential for studying fining processes compared to classical univariate approaches.
Zhao, Yang; Maher, Jason R.; Ibrahim, Mohamed M.; Chien, Jennifer S.; Levinson, Howard; Wax, Adam
2016-01-01
We have developed frequency domain multispectral multiple scattering low coherence interferometry (ms2/LCI) for deep imaging of absorption and scattering contrast. Using tissue-mimicking phantoms that match the full scattering phase function of human dermal tissue, we demonstrate that ms2/LCI can provide a signal/noise ratio (SNR) improvement of 15.4 dB over conventional OCT at an imaging depth of 1 mm. The enhanced SNR and penetration depth provided by ms2/LCI could be leveraged for a variety of clinical applications including the assessment of burn injuries where current clinical classification of severity only provides limited accuracy. The utility of the approach was demonstrated by imaging a tissue phantom simulating a partial-thickness burn revealing good spectroscopic contrast between healthy and injured tissue regions deep below the sample surface. Finally, healthy rat skin was imaged in vivo with both a commercial OCT instrument and our custom ms2/LCI system. The results demonstrate that ms2/LCI is capable of obtaining spectroscopic information far beyond the penetration depth provided by conventional OCT. PMID:27867703
Multiple Scattering Debye-Waller Factors for Arsenate
NASA Astrophysics Data System (ADS)
Kim, E.; Chen, N.; Arthur, Z.; Warner, J.; Demopoulos, G. P.; Rowson, J. W.; Jiang, D. T.
2013-04-01
Debye-Waller factors for the As-O-O triangular multiple scattering paths within the arsenate in Na2HAsO4·7H2O are evaluated in terms of magnitude ratio with respect to the Debye-Waller factor of the nearest neighbour As-O shell (σ2As-0-0/σ2As-0). The arsenates are studied under two different levels of distortion from an ideal tetrahedron, i.e. a relatively high distortion in the powder form and a nearly ideal tetrahedron in an aqueous solution at pH 14. The Debye-Waller factor ratio σ2As-0-0/σ2As-0) is found to be 2.0 and 1.9 for the powder and liquid sample, respectively, appearing to be insensitive to the distortion of the arsenate tetrahedron.
Ultrafast collinear scattering and carrier multiplication in graphene.
Brida, D; Tomadin, A; Manzoni, C; Kim, Y J; Lombardo, A; Milana, S; Nair, R R; Novoselov, K S; Ferrari, A C; Cerullo, G; Polini, M
2013-01-01
Graphene is emerging as a viable alternative to conventional optoelectronic, plasmonic and nanophotonic materials. The interaction of light with charge carriers creates an out-of-equilibrium distribution, which relaxes on an ultrafast timescale to a hot Fermi-Dirac distribution, that subsequently cools emitting phonons. Although the slower relaxation mechanisms have been extensively investigated, the initial stages still pose a challenge. Experimentally, they defy the resolution of most pump-probe setups, due to the extremely fast sub-100 fs carrier dynamics. Theoretically, massless Dirac fermions represent a novel many-body problem, fundamentally different from Schrödinger fermions. Here we combine pump-probe spectroscopy with a microscopic theory to investigate electron-electron interactions during the early stages of relaxation. We identify the mechanisms controlling the ultrafast dynamics, in particular the role of collinear scattering. This gives rise to Auger processes, including charge multiplication, which is key in photovoltage generation and photodetectors.
Computational methods in metallic alloys within multiple scattering theory
NASA Astrophysics Data System (ADS)
Rusanu, Aurelian
Designing materials, particularly at the nano-scale, is an important scientific research area. It includes a large spectrum of basic science and technological developments. In order to provide results that are relevant to real materials, quantum mechanical simulations involving thousands to millions of atoms must be carried out. The locally self-consistent multiple scattering (LSMS) method is the method of choice for such calculations because it has a technical feature called order-N scaling. We describe an implementation of the LSMS for massively parallel supercomputers using k-space and real-space methods. For magnetic materials, the constrained local moment approach and the exchange interaction method are used. We demonstrate our approach by calculating the electronic and magnetic structure of an iron nano-particle embedded in an iron aluminide crystal matrix.
The Expected Impact of Multiple Scattering on ATLID Signals
NASA Astrophysics Data System (ADS)
Donovan, D. P.
2016-06-01
ATLID stands for "ATmospheric LIDar" and is the lidar to be flown on the Earth Clouds and Radiation Explorer (EarthCARE) platform in 2018. ATLID is a High-Spectral Resolution (HSRL) system operating at 355nm with a narrower field-of-view and lower orbit than the CALIPSO lidar. In spite of the smaller footprint multiple-scattering (MS) will have an important impact on ATLID cloud signals and, in some aspects, the accurate treatment of MS will be more important for ATLID than CALIPSO. On the other hand, the relationship between integrated backscatter and integrated MS induced depolarization in water clouds will be similar between ATLID and CALIPSO indicating that a CALIPSO-like strategy for cloud-phase identification can be successfully applied to ATLID.
Piskozub, Jacek; Stramski, Dariusz; Terrill, Eric; Melville, W Kendall
2004-08-20
Using three-dimensional Monte Carlo radiative transfer simulations, we examine the effect of beam transmissometer geometry on the relative error in the measurement of the beam-attenuation coefficient in an aquatic environment characterized by intense light scattering, especially within submerged bubble clouds entrained by surface-wave breaking. We discuss the forward-scattering error associated with the detection of photons scattered at small angles (< 1 degrees) and the multiple-scattering error associated with the detection of photons scattered more than once along the path length of the instrument. Several scattering phase functions describing bubble clouds at different bubble void fractions in the water are considered. Owing to forward-scattering error, a beam-attenuation meter (beam transmissometer) with a half-angle of receiver acceptance of 1.0 degrees and a path length of 0.1 m can underestimate the true beam attenuation within the bubble cloud by more than 50%. For bubble clouds with a beam attenuation of as much as 100 m(-1), the multiple-scattering error is no more than a few percent. These results are compared with simulations for some example phase functions that are representative of other scattering regimes found in natural waters. The forward-scattering error for the Petzold phase function of turbid waters is 16% for a typical instrument geometry, whereas for the Henyey-Greenstein phase function with the asymmetry parameter of 0.7 and 0.9 the error range is 8-28%.
Lidar multiple scattering as a tool for cloud microphysical parameters
NASA Astrophysics Data System (ADS)
Werner, Christian; Oppel, Ulrich G.
1995-09-01
Lidar was applied to identify atmospheric inhomogeneities by different scattering behavior of the aerosol particles. Aerosol is a general term, it includes also the aggregation to clouds. In the stratosphere there exist droplets of sulfuric acid (from volcanic eruptions), nitric acids and water vapor in mixed phases. In the polar region polar stratospheric (aerosol) clouds form during winter at temperatures around 195K. Usually the nucleation of nitric acid trihydrate (NAT) and nitric acids dihydrate (NAD) happens in a complicated mechanism. A lidar can identify the result of the nucleation process, not the gas phases. It can distinguish between droplets (as Mie particles) and crystal (frozen droplets of NAT and NAD) by polarization. Because the aerosols are driven with the wind and have a tendency to sediment, the orientation of the lidar to the aerosol particles is an important factor. Improvement of lidar measurements to distinguish between stratospheric aerosols and polar stratospheric clouds (i.e. by the given definition the frozen aggregation) was focused: 1) on the use of multiple wavelength lidar with a polarization channel, 2) on a theoretical study on the possibility to use multiple scattering as an additional discriminant and, 3) on scanning. Points 2 and 3 require a better detection and signal processing system. Statistical problems arise for the comparison of measurements, for example if one compares ground-based and airborne measurements of the same cloud. Airborne measurements can contribute to the problem because one can reduce the distance to the object and therefore the 1/R2-dependency leads to larger signals. Averaging with respect to ensemble statistics are covered in this report. It is accepted that ground-based lidar systems especially with a Raman channel measure with a high pulse repetition rate over a few minutes to get a signal which can be processed.
NASA Technical Reports Server (NTRS)
Deepak, A.; Fluellen, A.
1978-01-01
An efficient numerical method of multiple quadratures, the Conroy method, is applied to the problem of computing multiple scattering contributions in the radiative transfer through realistic planetary atmospheres. A brief error analysis of the method is given and comparisons are drawn with the more familiar Monte Carlo method. Both methods are stochastic problem-solving models of a physical or mathematical process and utilize the sampling scheme for points distributed over a definite region. In the Monte Carlo scheme the sample points are distributed randomly over the integration region. In the Conroy method, the sample points are distributed systematically, such that the point distribution forms a unique, closed, symmetrical pattern which effectively fills the region of the multidimensional integration. The methods are illustrated by two simple examples: one, of multidimensional integration involving two independent variables, and the other, of computing the second order scattering contribution to the sky radiance.
Multiple Scattering Effects on Pulse Propagation in Optically Turbid Media.
NASA Astrophysics Data System (ADS)
Joelson, Bradley David
The effects of multiple scattering in a optically turbid media is examined for an impulse solution to the radiative transfer equation for a variety of geometries and phase functions. In regions where the complexities of the phase function proved too cumbersome for analytic methods Monte Carlo techniques were developed to describe the entire scalar radiance distribution. The determination of a general spread function is strongly dependent on geometry and particular regions where limits can be placed on the variables of the problem. Hence, the general spread function is first simplified by considering optical regions which reduce the complexity of the variable dependence. First, in the small-angle limit we calculate some contracted spread functions along with their moments and then use Monte Carlo techniques to establish the limitations imposed by the small-angle approximation in planar geometry. The point spread function (PSF) for a spherical geometry is calculated for the full angular spread in the forward direction of ocean waters using Monte Carlo methods in the optically thin and moderate depths and analytic methods in the diffusion domain. The angular dependence of the PSF for various ocean waters is examined for a range of optical parameters. The analytic method used in the diffusion calculation is justified by examining the angular dependence of the radiance of a impulse solution in a planar geometry for a prolongated Henyey-Greenstein phase function of asymmetry factor approximately equal to that of the ocean phase functions. The Legendre moments of the radiance are examined in order to examine the viability of the diffusion approximation which assumes a linearly anisotropic angular distribution for the radiance. A realistic lidar calculation is performed for a variety of ocean waters to determine the effects of multiple scattering on the determination of the speed of sound by using the range gated frequency spectrum of the lidar signal. It is shown that the
Multiple scattering in a dark material - an anomaly
NASA Astrophysics Data System (ADS)
Smythe, W. D.; Nelson, R. M.; Hapke, B. W.; Hale, A. S.; Piatek, J. A.
2002-12-01
albedo is not only parameter determining the amount of multiple scattering in the medium. This unusual behavior is as yet unexplained; one conjecture is that a unique particle shape may create a very unusual single scattering phase function in boron carbide. It is important to understand this unusual behavior and its implications for models that retrieve surface textural properties from remote sensing data. This work performed at JPL under a contract from NASA's Planetary Geology and Geophysics Program. 1. Geherels, T. Astrophys. J, 123, 331-338, 1956 2. Hapke, B. W. Icarus, 67, 264-280, 1986 3. Shkuratov, Yu. SA-A.J., 27, 581-583, 1983 4. Hapke, B.W. Icarus, 88, 264-280, 1986 5. Nelson, R. M., B. W. Hapke, W. D. Smythe, L. J. Horn. Icarus 131, 223-230, 1998 6. Nelson, R. M., B. W. Hapke, W. D. Smythe, L. J. Spilker. Icarus, 147, 545-558, 2000 7. Nelson, R. M., W. D. Smythe, B. W. Hapke, A. S. Hale. to appear in Planet. Space Sci, 2002
Suppression of multiple scattering with a CCD camera detection scheme
NASA Astrophysics Data System (ADS)
Zakharov, Pavel; Schurtenberger, Peter; Scheffold, Frank
2005-06-01
We introduce a CCD camera detection scheme in dynamic light scattering that provides information on the single-scattered auto-correlation function even for fairly turbid samples. Our approach allows access to the extensive range of systems that show low-order scattering by selective detection of the singly scattered light. Model experiments on slowly relaxing suspensions of latex spheres in glycerol were carried out to verify validity range of our approach.
NASA Astrophysics Data System (ADS)
Hou, Weizhen; Sun, Bin; Li, Zhengqiang; Sun, Xiaobing; Hong, Jin; Qie, Lili; Wang, Han
2015-10-01
With the polynomial fitting of source function in each order of scattering calculation and the effective process of aerosol forward scattering peak, a polarized radiative transfer (RT) model based on the improved successive order of scattering (SOS) method has been developed to solve the vector radiative transfer equation. By our RT model, not only the total Stokes parameters [I, Q, U] measured by the satellite (aircraft) and ground-based sensors with linear polarization could be approximately simulated, but also the results of parameters for each scattering order event could conveniently calculated, which are very helpful to study the polarization properties for the atmospheric aerosol multiple scattering. In this study, the synchronous measured aerosol results including aerosol optical depth, complex refractive index and particle size distribution from AERONET under different air conditions, are considered as the input parameters for the successive scattering simulations. With our polarized RT model and the Mie code combined, the Stokes parameters as well as the degree of polarization for each scattering order are simulated and presented; meanwhile, the polarization (depolarization) properties of multiply scattering are preliminary analyzed and compared with different air quality (clear and pollution). Those results could provide a significant support for the further research of polarized aerosol remote sensing and inversion. Polarization properties of aerosol, successive order of scattering, vector radiative transfer equation, polynomial fitting of source function , multiply scattering
Coastal Zone Color Scanner atmospheric correction algorithm: multiple scattering effects.
Gordon, H R; Castaño, D J
1987-06-01
An analysis of the errors due to multiple scattering which are expected to be encountered in application of the current Coastal Zone Color Scanner (CZCS) atmospheric correction algorithm is presented in detail. This was prompted by the observations of others that significant errors would be encountered if the present algorithm were applied to a hypothetical instrument possessing higher radiometric sensitivity than the present CZCS. This study provides CZCS users sufficient information with which to judge the efficacy of the current algorithm with the current sensor and enables them to estimate the impact of the algorithm-induced errors on their applications in a variety of situations. The greatest source of error is the assumption that the molecular and aerosol contributions to the total radiance observed at the sensor can be computed separately. This leads to the requirement that a value epsilon'(lambda,lambda(0)) for the atmospheric correction parameter, which bears little resemblance to its theoretically meaningful counterpart, must usually be employed in the algorithm to obtain an accurate atmospheric correction. The behavior of '(lambda,lambda(0)) with the aerosol optical thickness and aerosol phase function is thoroughly investigated through realistic modeling of radiative transfer in a stratified atmosphere over a Fresnel reflecting ocean. A unique feature of the analysis is that it is carried out in scan coordinates rather than typical earth-sun coordinates allowing elucidation of the errors along typical CZCS scan lines; this is important since, in the normal application of the algorithm, it is assumed that the same value of can be used for an entire CZCS scene or at least for a reasonably large subscene. Two types of variation of ' are found in models for which it would be constant in the single scattering approximation: (1) variation with scan angle in scenes in which a relatively large portion of the aerosol scattering phase function would be examined
Kinetic Effects in Multiple Intra-Beam Scattering
Zenkevich, P.; Bolshakov, A.; Boine-Frankenheim, O.
2005-06-08
The analysis of the evolution in phase space induced by multiple intra-beam scattering (IBS) requires the solution of the Fokker-Planck equation (FPE) or of similar kinetic equations. The FPE is formulated in coordinate-momentum space (6 variables). Using the 'semi-Gaussian model' this equation is reduced to the longitudinal FPE that depends on longitudinal momentum and coordinate; drift and diffusion coefficients in this equation are presented as integrals on distribution function with kernels expressed in analytical form. The number of variables in the FPE can be reduced to three by reformulation in the space of invariants. The invariant-vector has the following components: a longitudinal energy (for the longitudinal degree of freedom) and the Courant-Snyder invariants (for the transverse motion). The coefficients of the FPE in invariant space are in the form of integrals over the distribution function and the invariants with the kernel in the form of many-dimensional integrals over the longitudinal variable and over the oscillation phases. The three-dimensional FPE can be solved numerically by application of macro-particle codes using the different methods: 1) Langevin method; 2) binary collision map. The last method is used in the code 'MOCAC' (MOnte CArlo Code) for IBS simulation. Examples of code validation and application are discussed.
Full-potential multiple-scattering theory without structure constants
NASA Astrophysics Data System (ADS)
Nesbet, R. K.
1992-10-01
A form of full-potential multiple-scattering theory for electrons in solids or molecules has recently been proposed in which the structure constants characteristic of standard theory (Korringa-Kohn-Rostoker) do not occur. This formalism was derived from the Lippmann-Schwinger integral equation and has been called the Green-function cellular method. It is shown here that this formalism is a restatement of the tail-cancellation condition of Andersen, applied originally in the context of his muffin-tin-orbital construction, using a local spherical approximation to the potential function in the Schrödinger equation. This was generalized to the atomic-cell orbital (ACO) construction for the full-potential problem by the present author. The equations of this method are derived here directly from the ACO tail-cancellation condition for boundary matching on the surface of each cell in a set of space-filling atomic cells, making no use of the free-particle or Helmholtz Green function. It is also shown here that these equations correspond to a restricted variation of trial functions on the surfaces of atomic cells in the context of the variational cellular method of Leite and collaborators, derived from the variational principle of Schlosser and Marcus.
Real-space multiple-scattering theory of XMCD including spin-orbit interaction in scattering process
NASA Astrophysics Data System (ADS)
Koide, Akihiro; Niki, Kaori; Sakai, Seiji; Fujikawa, Takashi
2016-05-01
The effects of the spin-orbit interaction on surrounding atoms for XMCD spectra are studied by a real-space multiple-scattering theory. The present numerical calculation for Fe K-edge XMCD spectra from BCC iron demonstrates the importance of the spin-orbit interaction on scattering atoms, which has been disregarded in previous works. These effects will be inevitable for K-edge XMCD analyses of light elements surrounded by heavy magnetic atoms.
NASA Astrophysics Data System (ADS)
Piskozub, Jacek; Stramski, Dariusz; Terrill, Eric; Melville, W. Kendall
2004-08-01
Using three-dimensional Monte Carlo radiative transfer simulations, we examine the effect of beam transmissometer geometry on the relative error in the measurement of the beam-attenuation coefficient in an aquatic environment characterized by intense light scattering, especially within submerged bubble clouds entrained by surface-wave breaking. We discuss the forward-scattering error associated with the detection of photons scattered at small angles (< 1Â°) and the multiple-scattering error associated with the detection of photons scattered more than once along the path length of the instrument. Several scattering phase functions describing bubble clouds at different bubble void fractions in the water are considered. Owing to forward-scattering error, a beam-attenuation meter (beam transmissometer) with a half-angle of receiver acceptance of 1.0Â° and a path length of 0.1 m can underestimate the true beam attenuation within the bubble cloud by more than 50%. For bubble clouds with a beam attenuation of as much as 100 m^-1, the multiple-scattering error is no more than a few percent. These results are compared with simulations for some example phase functions that are representative of other scattering regimes found in natural waters. The forward-scattering error for the Petzold phase function of turbid waters is 16% for a typical instrument geometry, whereas for the Henyey-Greenstein phase function with the asymmetry parameter of 0.7 and 0.9 the error range is 8-28%.
Improvements in simulation of multiple scattering effects in ATLAS fast simulation
Basalaev, A. E.
2016-12-15
Fast ATLAS Tracking Simulation (Fatras) package was verified on single layer geometry with respect to full simulation with GEANT4. Fatras hadronic interactions and multiple scattering simulation were studied in comparison with GEANT4. Disagreement was found in multiple scattering distributions of primary charged particles (μ, π, e). A new model for multiple scattering simulation was implemented in Fatras. The model was based on R. Frühwirth’s mixture models. New model was tested on single layer geometry and a good agreement with GEANT4 was achieved. Also a comparison of reconstructed tracks’ parameters was performed for Inner Detector geometry, and Fatras with new multiple scattering model proved to have better agreement with GEANT4. New model of multiple scattering was added as a part of Fatras package in the development release of ATLAS software—ATHENA.
Duadi, Hamootal; Fixler, Dror
2015-05-01
Light reflectance and transmission from soft tissue has been utilized in noninvasive clinical measurement devices such as the photoplethysmograph (PPG) and reflectance pulse oximeter. Incident light on the skin travels into the underlying layers and is in part reflected back to the surface, in part transferred and in part absorbed. Most methods of near infrared (NIR) spectroscopy focus on the volume reflectance from a semi-infinite sample, while very few measure transmission. We have previously shown that examining the full scattering profile (angular distribution of exiting photons) provides more comprehensive information when measuring from a cylindrical tissue. Furthermore, an isobaric point was found which is not dependent on changes in the reduced scattering coefficient. The angle corresponding to this isobaric point depends on the tissue diameter. We investigated the role of multiple scattering and absorption on the full scattering profile of a cylindrical tissue. First, we define the range in which multiple scattering occurs for different tissue diameters. Next, we examine the role of the absorption coefficient in the attenuation of the full scattering profile. We demonstrate that the absorption linearly influences the intensity at each angle of the full scattering profile and, more importantly, the absorption does not change the position of the isobaric point. The findings of this work demonstrate a realistic model for optical tissue measurements such as NIR spectroscopy, PPG, and pulse oximetery.
NASA Astrophysics Data System (ADS)
Chami, Malik; McKee, David; Leymarie, Edouard; Khomenko, Gueorgui
2006-12-01
Scattering phase functions derived from measured (volume-scattering meter, VSM) volume-scattering functions (VSFs) from Crimean coastal waters were found to have systematic differences in angular structure from Fournier-Forand (FF) functions with equivalent backscattering ratios. Hydrolight simulations demonstrated that differences in the angular structure of the VSF could result in variations in modeled subsurface radiance reflectances of up to ±20%. Furthermore, differences between VSM and FF simulated reflectances were found to be nonlinear as a function of scattering and could not be explained with the single-scattering approximation. Additional radiance transfer modeling demonstrated that the contribution of multiple scattering to radiance reflectance increased exponentially from a minimum of 16% for pure water to a maximum of ˜94% for turbid waters. Monte Carlo simulations demonstrated that multiple forward-scattering events were the dominant contributors to the generation of radiance reflectance signals for turbid waters and that angular structures in the shape of the VSF at forward angles could have a significant influence in determining reflectance signals for turbid waters.
Chami, Malik; McKee, David; Leymarie, Edouard; Khomenko, Gueorgui
2006-12-20
Scattering phase functions derived from measured (volume-scattering meter, VSM) volume-scattering functions (VSFs) from Crimean coastal waters were found to have systematic differences in angular structure from Fournier-Forand (FF) functions with equivalent backscattering ratios. Hydrolight simulations demonstrated that differences in the angular structure of the VSF could result in variations in modeled subsurface radiance reflectances of up to +/-20%. Furthermore, differences between VSM and FF simulated reflectances were found to be nonlinear as a function of scattering and could not be explained with the single-scattering approximation. Additional radiance transfer modeling demonstrated that the contribution of multiple scattering to radiance reflectance increased exponentially from a minimum of 16% for pure water to a maximum of approximately 94% for turbid waters. Monte Carlo simulations demonstrated that multiple forward-scattering events were the dominant contributors to the generation of radiance reflectance signals for turbid waters and that angular structures in the shape of the VSF at forward angles could have a significant influence in determining reflectance signals for turbid waters.
Multiple scattering and charged-particle - hydrogen-atom collisions
NASA Technical Reports Server (NTRS)
Franco, V.; Thomas, B. K.
1979-01-01
Glauber-approximation scattering amplitudes for charged-particle - hydrogen-atom elastic and inelastic collisions are derived directly in terms of the known particle-electron and particle-proton Coulomb scattering amplitudes and the known hydrogen-atom form factors. It is shown that the particle-hydrogen amplitude contains no single-scattering term. The double-scattering term is obtained as a two-dimensional integral in momentum space. It is demonstrated how the result can be used as the starting point for an alternative and relatively simple derivation, in closed form, of the Glauber particle-hydrogen scattering amplitude for transitions from the ground state to an arbitrary (nlm) state.
Few-body multiple scattering calculations for {sup 6}He on protons
Al-Khalili, J. S.; Johnson, R. C.; Thompson, I. J.; Crespo, R.; Moro, A. M.
2007-02-15
The elastic scattering of the halo nucleus {sup 6}He from a proton target at 717 MeV/nucleon is investigated within three different multiple-scattering formulations of the total transition amplitude. The factorized impulse approximation (FIA) and the fixed scatterer approximation (FSA) of the multiple-scattering expansion are used to evaluate accurately the single-scattering terms and to test the validity of a few-body Glauber approach. The latter also includes terms beyond single scattering and the importance of these terms is investigated. The differential cross section is calculated for proton scattering from {sup 6}He at 717 MeV in inverse kinematics and compared with recent data.
NASA Astrophysics Data System (ADS)
Margetan, F. J.; Haldipur, Pranaam; Yu, Linxiao; Thompson, R. B.
2005-04-01
For pulse/echo inspections of metals, models which predict backscattered noise characteristics often make a "single-scattering" assumption, i.e., multiple-scattering events in which sound is scattered from one grain to another before returning to the transducer are ignored. Models based on the single-scattering assumption have proven to be very useful in simulating inspections of engine-alloy billets and forgings. However, this assumption may not be accurate if grain scattering is too "strong" (e.g., if the mean grain diameter and/or the inspection frequency is too large). In this work, backscattered grain noise measurements and analyses were undertaken to search for evidence of significant multiple scattering in pulse/echo inspections of jet-engine Nickel alloys. At or above about 7 MHz frequency and 50 micron grain diameter, problems were seen with single-scattering noise models that are likely due to the neglect of multiple scattering by the models. The modeling errors were less severe for focused-probe measurements in the focal zone than for planar probe inspections. Single-scattering noise models are likely adequate for simulating current billet inspections which are carried out using 5-MHz focused transducers. However, multiple scattering effects should be taken into account in some fashion when simulating higher-frequency inspections of Nickel-alloy billets having large mean grain diameters (> 40 microns).
μ-diff: An open-source Matlab toolbox for computing multiple scattering problems by disks
NASA Astrophysics Data System (ADS)
Thierry, Bertrand; Antoine, Xavier; Chniti, Chokri; Alzubaidi, Hasan
2015-07-01
The aim of this paper is to describe a Matlab toolbox, called μ-diff, for modeling and numerically solving two-dimensional complex multiple scattering by a large collection of circular cylinders. The approximation methods in μ-diff are based on the Fourier series expansions of the four basic integral operators arising in scattering theory. Based on these expressions, an efficient spectrally accurate finite-dimensional solution of multiple scattering problems can be simply obtained for complex media even when many scatterers are considered as well as large frequencies. The solution of the global linear system to solve can use either direct solvers or preconditioned iterative Krylov subspace solvers for block Toeplitz matrices. Based on this approach, this paper explains how the code is built and organized. Some complete numerical examples of applications (direct and inverse scattering) are provided to show that μ-diff is a flexible, efficient and robust toolbox for solving some complex multiple scattering problems.
Robustness of the fractal regime for the multiple-scattering structure factor
NASA Astrophysics Data System (ADS)
Katyal, Nisha; Botet, Robert; Puri, Sanjay
2016-08-01
In the single-scattering theory of electromagnetic radiation, the fractal regime is a definite range in the photon momentum-transfer q, which is characterized by the scaling-law behavior of the structure factor: S(q) ∝ 1 /q df. This allows a straightforward estimation of the fractal dimension df of aggregates in Small-Angle X-ray Scattering (SAXS) experiments. However, this behavior is not commonly studied in optical scattering experiments because of the lack of information on its domain of validity. In the present work, we propose a definition of the multiple-scattering structure factor, which naturally generalizes the single-scattering function S(q). We show that the mean-field theory of electromagnetic scattering provides an explicit condition to interpret the significance of multiple scattering. In this paper, we investigate and discuss electromagnetic scattering by three classes of fractal aggregates. The results obtained from the TMatrix method show that the fractal scaling range is divided into two domains: (1) a genuine fractal regime, which is robust; (2) a possible anomalous scaling regime, S(q) ∝ 1 /qδ, with exponent δ independent of df, and related to the way the scattering mechanism uses the local morphology of the scatterer. The recognition, and an analysis, of the latter domain is of importance because it may result in significant reduction of the fractal regime, and brings into question the proper mechanism in the build-up of multiple-scattering.
NASA Astrophysics Data System (ADS)
Zhang, Dai; Hao, Shiqi; Wang, Lei; Zhao, Qi
2016-10-01
An analytical formula model which is used to describe laser beam's depolarization characteristics is solved based on multiple Rayleigh scattering model. Firstly, by using Stokes vector to characterize intensity and polarization, while at the same time using Mueller matrix and rotation matrix to characterize polarization changing in scattering procedure, a single scattering model is built. Then, a multiple scattering model is built considering the effects of atmospheric absorbing and scattering attenuation. The received light's Stokes vectors through multiple scattering procedure are separately solved. At last, on the basis of multiple scattering vectors, the depolarization characteristics of laser beam propagation through atmosphere are estimated though calculating ratio of depolarization and polarized angle shifting. The numerical analysis based on analytical conclusion of this paper shows that for a horizontal polarized laser beam, its ratio of depolarization is about 1% and polarized angle shifting is about 0.3° when propagates through atmosphere and arrives into the receiver on the ground, and both the above characteristics have only a small change compared with the change of cloud's depth. The findings of these research show that Rayleigh scattering from atmosphere has a weak effect on the laser beam's polarization status. The multiple scattering model and Stokes vector analytical formulas raised in the paper could also be used to study the depolarization characteristics of ellipse polarized laser beam and partially polarized laser beam propagating through atmosphere. The research findings of this paper will have theoretical guiding significances in the domain of laser communication, laser detection and laser imaging.
Experimental Studies of Multiple Scattering by Rough Surfaces.
NASA Astrophysics Data System (ADS)
Knotts, Michael Eugene
Experimental investigations were conducted to study the optical scattering properties of metallic rough surfaces with steep slopes and wavelength-sized structures that exhibit backscattering enhancement. Particular emphasis was placed on two kinds of surface with strictly one-dimensional roughness: random surfaces with Gaussian statistics and gratings consisting of deep, regularly spaced grooves that have been subjected to a random, groove-to-groove depth fluctuation. Methods for the fabrication of surfaces in photoresist and techniques for their characterization using a Talystep mechanical profilometer were developed. Normalized measurements of the angular dependence of the mean diffusely scattered intensities were obtained with the plane of incidence parallel to the axis of the surface height fluctuations. Using an incident wave polarized at 45^circ with respect to the plane of incidence, the Mueller matrix describing the complete polarization dependence of the mean scattered intensity was determined. It was shown that this matrix contains four distinct quantities corresponding to the second moments of scattered amplitudes, and that previous work presenting only the p- and s-polarized scattered intensities is therefore incomplete. Furthermore, it was shown that the four additional measured intensities required to determine the matrix elements can be used to isolate the backscattering enhancement and yield valuable physical insight. The results conclusively demonstrate that contributions arising from waves multiply scattered within valleys of the surface significantly affect the polarization dependence of the far-field scattered intensity and give rise to the observed backscattering enhancement.
Multiple scattering of surface waves by cavities in a half-space
Phan, Haidang; Cho, Younho; Ju, Taeho; Achenbach, Jan D.
2014-02-18
Scattering of surface waves from multiple two-dimensional cavities at the surface of a homogenous, isotropic, linearly elastic half-space is analyzed in this work. For the case of multiple cavities, the scattered field is shown to be equivalent to the total radiation from the distributions of tractions, calculated from the incident wave, over the surfaces of the cavities. The multiple-scattering model is obtained from known single-scattering calculation for a cavity by the use of the self-consistent method. The second order approximation to the multiple-scattering problem by a random distribution of cavities is then considered and solved analytically. The vertical displacement at some distance from the cavities is calculated and verified by the solution of the same problem obtained by the boundary element method (BEM). The analytical and BEM results are graphically displayed and show good agreement when the depths of the cavities are small compared to the wavelength.
Multiple-scattering effects of atmosphere aerosols on light-transmission measurements
NASA Astrophysics Data System (ADS)
Ma, Yuzhao; Liu, Wenrong; Cui, Yafeng; Xiong, Xinglong
2017-06-01
Multiple-scattering effects of atmosphere aerosols are of interest for remote sensing, free-space communications, and atmosphere detection. In the present work, the multiple-scattering effects of atmosphere aerosols on light-transmission measurements are, for the first time, investigated through numerical simulations based on the Monte Carlo method. For different extinction coefficients of the atmosphere, the multiple-scattering effects are discussed with respect to the aerosol asymmetry factor and the intended optical system parameters such as the baseline length, the area of the photoelectronic detector, and the field of view. As the simulation results, the total photon energies of scattering of each order are demonstrated. It is shown that the multiple-scattering effects are influenced by all the mentioned factors, as expected. Our work is useful for improving the optical systems based on the light-transmission measurements that are widely employed in weather observation and aerosol characterizations.
Multiple-scattering effects of atmosphere aerosols on light-transmission measurements
NASA Astrophysics Data System (ADS)
Ma, Yuzhao; Liu, Wenrong; Cui, Yafeng; Xiong, Xinglong
2017-08-01
Multiple-scattering effects of atmosphere aerosols are of interest for remote sensing, free-space communications, and atmosphere detection. In the present work, the multiple-scattering effects of atmosphere aerosols on light-transmission measurements are, for the first time, investigated through numerical simulations based on the Monte Carlo method. For different extinction coefficients of the atmosphere, the multiple-scattering effects are discussed with respect to the aerosol asymmetry factor and the intended optical system parameters such as the baseline length, the area of the photoelectronic detector, and the field of view. As the simulation results, the total photon energies of scattering of each order are demonstrated. It is shown that the multiple-scattering effects are influenced by all the mentioned factors, as expected. Our work is useful for improving the optical systems based on the light-transmission measurements that are widely employed in weather observation and aerosol characterizations.
Single and multiple light scattering studies of PDLC films in the presence of electric fields
NASA Astrophysics Data System (ADS)
Wu, Wei
Light scattering from Polymer Dispersed Liquid Crystal (PDLC) films is studied in four major respects: the differential scattering cross-section of a single liquid crystal droplet; the total scattering cross-section and film transmittance; multiple scattering effects; and scattering by absorbing droplets (PDLC doped with dichroic dye). The effects of applied electric field, light wavelength and the liquid crystal droplet size on the scattering behavior are examined. PDLC scattering properties under electric field are described by combining the Anomalous Diffraction Approach (ADA) with PDLC electro-optical response theory. Numerical computation results directly demonstrate how the total scattering cross section relates to the incident light wavelength, the droplet size and the applied electric field. Transmittance measurements are used to study the total scattering cross-section. Analyses of the transmittance characteristics show good agreement with the theoretical predictions. PDLC samples with a practical contrast ratio exhibit strong multiple scattering effects. Studies of the single scattering differential cross section provide a foundation for the modeling and experimental work on the multiple scattering effects. Single scattering characteristics of a bipolar droplet director configuration are derived for a highly symmetric situation. The results offer qualitative explanations for some experimental observations, such as the presence of off-normal maxima and breakdown of rotational symmetry in the scattering pattern. As a novel approach, we propose a multiple scattering model for PDLC based on successive order and Monte Carlo methods. This model, along with ADA and electro-optical response theories, was used to calculate the angular distribution of scattered light and electric field switching response. The predictions demonstrate close quantitative agreement with experimental results. Incorporating complex refractive indices to treat dye- doped PDLC
Multiple scattering of electrons in the reflex triode
Creedon, J.M. )
1990-12-01
Analytical theories and Monte Carlo calculations are used to treat the scattering and energy loss of electrons in the anode of a reflex triode. The solution of this scattering problem is combined with the equations for particle flow in vacuum to give a quantitative theory of triode operation. It is now possible to calculate several important properties of this device. These include the operating voltage in the constant voltage mode, the ratio of ion-to-electron current and the ion transit time.
Multiple Scattering of Electromagnetic Waves in Discrete Random Media.
1984-12-31
purposes, we have also investigated the electromagnetic wave propagation through randomly distributed and oriented scatterers by introducing the concept...computer to determine whether or not particle overlap has occurred. The implementation of the "physics" of the system and orientations of non-spherical...34Coherent electromagnetic wave propagation through randomly distributed and oriented pair-correlated dielectric scatterers," Radio Sci., 19, 1445-1449
Imaging Moving Objects from Multiply Scattered Waves and Multiple Sensors
2013-04-18
Online at stacks.iop.org/IP/29/054012 Abstract In this paper, we develop a linearized imaging theory that combines the spatial, temporal and spectral...public release; distribution unlimited 13. SUPPLEMENTARY NOTES 14. ABSTRACT In this paper, we develop a linearized imaging theory that combines the...spatial, temporal and spectral components of multiply scattered waves as they scatter from moving objects. In particular, we consider the case of
Joshi, Aditya; Lindsey, Brooks; Dayton, Paul; Pinton, Gianmarco; Muller, Marie
2017-03-07
- Ultrasound contrast agents (UCA), such as microbubbles, enhance the scattering properties of blood, which is otherwise hypoechoic. The multiple scattering interactions of the acoustic field with UCA's are poorly understood due to the complexity of the multiple scattering theories and the nonlinear microbubble response. The majority of bubble models describe the behavior of UCA's as single, isolated microbubbles suspended in infinite medium. Multiple scattering models such as the Independent Scattering Approximation can approximate phase velocity and attenuation for low scatterer volume fraction. However, all current models and simulations approach only describe multiple scattering and nonlinear bubble dynamics separately. Here we present an approach that combines two existing models: 1) a full-wave model that describes nonlinear propagation and scattering interactions in a heterogeneous attenuating medium and 2) a Paul-Sarkar model that describes the nonlinear interactions between an acoustic field and microbubbles. These two models were solved numerically and combined with an iterative approach. The convergence of this combined model was explored in silico for 0.5%, 1% and 2% bubble concentration by volume. The backscattering predicted by our modeling approach was verified experimentally with water tank measurements performed with a 128-element linear array transducer. An excellent agreement in terms of the fundamental and harmonic acoustic fields is shown. Additionally, our model correctly predicts the phase velocity and attenuation measured using through transmission and predicted by the Independent Scattering Approximation.
NASA Astrophysics Data System (ADS)
Joshi, Aditya; Lindsey, Brooks D.; Dayton, Paul A.; Pinton, Gianmarco; Muller, Marie
2017-05-01
Ultrasound contrast agents (UCA), such as microbubbles, enhance the scattering properties of blood, which is otherwise hypoechoic. The multiple scattering interactions of the acoustic field with UCA are poorly understood due to the complexity of the multiple scattering theories and the nonlinear microbubble response. The majority of bubble models describe the behavior of UCA as single, isolated microbubbles suspended in infinite medium. Multiple scattering models such as the independent scattering approximation can approximate phase velocity and attenuation for low scatterer volume fractions. However, all current models and simulation approaches only describe multiple scattering and nonlinear bubble dynamics separately. Here we present an approach that combines two existing models: (1) a full-wave model that describes nonlinear propagation and scattering interactions in a heterogeneous attenuating medium and (2) a Paul-Sarkar model that describes the nonlinear interactions between an acoustic field and microbubbles. These two models were solved numerically and combined with an iterative approach. The convergence of this combined model was explored in silico for 0.5 × 106 microbubbles ml-1, 1% and 2% bubble concentration by volume. The backscattering predicted by our modeling approach was verified experimentally with water tank measurements performed with a 128-element linear array transducer. An excellent agreement in terms of the fundamental and harmonic acoustic fields is shown. Additionally, our model correctly predicts the phase velocity and attenuation measured using through transmission and predicted by the independent scattering approximation.
NASA Astrophysics Data System (ADS)
Militsin, V. O.; Kachan, E. P.; Kandidov, V. P.
2006-11-01
Based on the stratified model of multiple coherent scattering of radiation in a dispersion medium, the nonlinear problem of the multiple filamentation of femtosecond laser pulses is studied by the Monte-Carlo method. It is shown that the modulation instability of a high-power light field, which develops on perturbations appearing upon coherent scattering by particles, causes the stochastic breakup of the pulse into numerous filaments. The influence of the size and concentration of particles in water aerosol on the generation of filamentation in a laser pulse is statistically estimated and the regions of different filamentation regimes are determined. The dynamic picture of the evolution of multiple filamentation and formation of plasma channels due to multiphoton ionisation upon aerosol scattering is obtained.
An SVD Investigation of Modeling Scatter in Multiple Energy Windows for Improved SPECT Images
Kadrmas, Dan J.; Frey, Eric C.; Tsui, Benjamin M.W.
2009-01-01
In this work singular value decomposition (SVD) techniques are used to investigate how the use of low energy photons and multiple energy windows affects the noise properties of Tc-99m SPECT imaging. We have previously shown that, when modeling scatter in the projector and backprojector of iterative reconstruction algorithms, simultaneous reconstruction from multiple energy window data can result in very different noise characteristics. Further, the properties depend upon the width and number of energy windows used. To investigate this further, we have generated photon transport matrices using models for scatter, an elliptical phantom containing cold rods of various sizes, and a number of multiple energy window acquisition schemes. Transfer matrices were also generated for the cases of perfect scatter rejection and ideal scatter subtraction. The matrices were decomposed using SVD, and signal power and projection space variance spectra were computed using the basis formed by the left singular vectors. Results indicate very different noise levels for the various energy window combinations. The perfect scatter rejection case resulted in the lowest variance spectrum, and reconstruction-based scatter compensation performed better than the scatter subtraction case. When including lower energy photons in reconstruction-based scatter compensation, using a series of multiple energy windows outperformed a single large energy window. One multiple window combination is presented which achieves a lower variance spectrum than the standard 20% energy window, indicating the potential for using low energy photons to improve the noise characteristics of SPECT images. PMID:20186285
NUMERICAL SIMULATIONS OF MULTIPLE SCATTERING OF THE f-MODE BY FLUX TUBES
Felipe, T.; Crouch, A.; Birch, A.
2013-09-20
We use numerical simulations to study the absorption and phase shift of surface-gravity waves caused by groups of magnetic flux tubes. The dependence of the scattering coefficients on the distance between the tubes and their positions is analyzed for several cases with two or three flux tubes embedded in a quiet Sun atmosphere. The results are compared with those obtained neglecting completely or partially multiple scattering effects. We show that multiple scattering has a significant impact on the absorption measurements and tends to reduce the phase shift. We also consider more general cases of ensembles of randomly distributed flux tubes, and we have evaluated the effects on the scattering measurements of changing the number of tubes included in the bundle and the average distance between flux tubes. We find that for the longest wavelength incoming waves, multiple scattering enhances the absorption, and its efficiency increases with the number of flux tubes and the reduction of the distance between them.
Wave multiple scattering by a finite number of unclosed circular cylinders
NASA Technical Reports Server (NTRS)
Veliyev, E. I.; Veremey, V. V.
1984-01-01
The boundary value problem of plane H-polarized electromagnetic wave multiple scattering by a finite number of unclosed circular cylinders is solved. The solution is obtained by two different methods: the method of successive scattering and the method of partial matrix inversion for simultaneous dual equations. The advantages of the successive scattering method are shown. Computer calculations of the suface currents and the total cross section are presented for the structure of two screens.
Gorodnichev, E. E.
2016-12-15
For elliptically polarized light incident on a two-dimensional medium with large inhomogeneities, the Stokes parameters of scattered waves are calculated. Multiple scattering is assumed to be sharply anisotropic. The degree of polarization of scattered radiation is shown to be a nonmonotonic function of depth when the incident wave is circularly polarized or its polarization vector is not parallel to the symmetry axis of the inhomogeneities.
Focused, multiple-pass cell for Raman scattering.
Hill, R A; Hartley, D L
1974-01-01
A simple optical system is described that makes use of a unique property of ellipsoidal mirrors, viz., light brought to one focus will be reflected alternately through the two foci and collapse to the major axis. This system consists of an on-axis ellipsoidal mirror facing a coaxial flat-spherical mirror assembly that is positioned at the minor axis. Calculations indicate that gains of the order of 500 in the light flux at the point of observation should be attainable with low-eccentricity ellipsoids. Raman-scattered light from atmospheric N(2) was obtained with a system employing a 0.2 eccentricity ellipsoid. An experimental gain of 93 was determined by the ratio of the scattering with the system to the scattering obtained with one beam. This result is in good agreement with the theory.
Kristensson, E; Araneo, L; Berrocal, E; Manin, J; Richter, M; Aldén, M; Linne, M
2011-07-04
The accuracy, precision and limitations of the imaging technique named Structured Laser Illumination Planar Imaging (SLIPI) have been investigated. SLIPI, which allows multiply scattered light to be diminished, has previously demonstrated improvements in image quality and contrast for spray imaging. In the current study the method is applied to a controlled confined environment consisting of a mixture of water and monodisperse polystyrene microspheres. Elastic scattering and fluorescence are studied and the results obtained when probing different particle concentrations and diameters conclusively show the advantages of SLIPI for imaging within moderately turbid media. Although the technique presents both good repeatability and agreement with the Beer-Lambert law, discrepancies in its performance were, however, discovered. Photons undergoing scattering without changing their incident trajectory cannot be discriminated and, owing to differences in scattering phase functions, probing larger particles reduces the suppression of multiply scattered light. However, in terms of visibility such behavior is beneficial as it allows denser media to be probed. It is further demonstrated that the suppression of diffuse light performs equally well regardless of whether photons propagate along the incident direction or towards the camera. In addition, this filtering process acts independently on the spatial distribution of the multiply scattered light but is limited by the finite dynamic range and unavoidable signal noise of the camera.
Effects of Multiple Photon Scattering in Deciduous Tree Canopies
2009-12-01
SCATTERING IN DECIDUOUS TREE CANOPIES 5a. CONTRACT NUMBER In-house 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 62204F 6. AUTHOR(S...where mh 18= , 16132.0 −= mLm , and 85.0=hzm . Note that the value for mL corresponds to our own experimental results, as will be described in Section 4
A Persistent Feature of Multiple Scattering of Waves in the Time-Domain: A Tutorial
NASA Technical Reports Server (NTRS)
Lock, James A.; Mishchenko, Michael I.
2015-01-01
The equations for frequency-domain multiple scattering are derived for a scalar or electromagnetic plane wave incident on a collection of particles at known positions, and in the time-domain for a plane wave pulse incident on the same collection of particles. The calculation is carried out for five different combinations of wave types and particle types of increasing geometrical complexity. The results are used to illustrate and discuss a number of physical and mathematical characteristics of multiple scattering in the frequency- and time-domains. We argue that frequency-domain multiple scattering is a purely mathematical construct since there is no temporal sequencing information in the frequency-domain equations and since the multi-particle path information can be dispelled by writing the equations in another mathematical form. However, multiple scattering becomes a definite physical phenomenon in the time-domain when the collection of particles is illuminated by an appropriately short localized pulse.
Probing atmospheric water vapor profiles via multiple scattering of electromagnetic waves
NASA Technical Reports Server (NTRS)
Tang, C. C. H.
1971-01-01
A theoretical analysis on the multiple scattering of electromagnetic waves propagating in a finite inhomogeneous medium is presented and applied to the study of wave propagation in a clear atmosphere (fine weather conditions). It is shown that the analysis offers a method of synthesizing the water vapor density profile in a clear atmosphere by measuring the resultant reflections from the density profile at several different frequencies. It is also shown that the resultant reflection emerges as the consequence of multiple scattering of partial reflections from various parts of the inhomogeneous medium. The solutions of the multiple scattering approach are shown to be more accurate than those of the WKB approach, which neglects the multiple scattering effects.
Effect of multiple scattering to optical forces on a sphere near an optical waveguide.
Xu, Jian; Zang, Wei-Ping; Tian, Jian-Guo
2015-02-23
We have investigated the effect of multiple scattering to optical forces on a particle in the evanescent field produced by an optical waveguide. Considering the multiple scattering between the sphere and the waveguide, we extend the formalism based on transition matrix and reflection matrix to calculate the optical forces on a sphere near an optical waveguide. Numerical results show that the influence that multiple scattering has on the optical forces can't be ignored, especially when the structure resonance of the particle arises. Moreover, the effect of multiple scattering to optical forces is also studied in detail on the condition that the distance between the sphere and the waveguide is within the effective operating distance.
A Persistent Feature of Multiple Scattering of Waves in the Time-Domain: A Tutorial
NASA Technical Reports Server (NTRS)
Lock, James A.; Mishchenko, Michael I.
2015-01-01
The equations for frequency-domain multiple scattering are derived for a scalar or electromagnetic plane wave incident on a collection of particles at known positions, and in the time-domain for a plane wave pulse incident on the same collection of particles. The calculation is carried out for five different combinations of wave types and particle types of increasing geometrical complexity. The results are used to illustrate and discuss a number of physical and mathematical characteristics of multiple scattering in the frequency- and time-domains. We argue that frequency-domain multiple scattering is a purely mathematical construct since there is no temporal sequencing information in the frequency-domain equations and since the multi-particle path information can be dispelled by writing the equations in another mathematical form. However, multiple scattering becomes a definite physical phenomenon in the time-domain when the collection of particles is illuminated by an appropriately short localized pulse.
Multiple scattering of slow ions in a partially degenerate electron fluid
Popoff, Romain; Maynard, Gilles; Deutsch, Claude
2009-10-15
We extend former investigation to a partially degenerate electron fluid at any temperature of multiple slow ion scattering at T=0. We implement an analytic and mean-field interpolation of the target electron dielectric function between T=0 (Lindhard) and T{yields}{infinity} (Fried-Conte). A specific attention is given to multiple scattering of proton projectiles in the keV energy range, stopped in a hot-electron plasma at solid density.
Angular width of the Cherenkov radiation with inclusion of multiple scattering
Zheng, Jian
2016-06-15
Visible Cherenkov radiation can offer a method of the measurement of the velocity of charged particles. The angular width of the radiation is important since it determines the resolution of the velocity measurement. In this article, the angular width of Cherenkov radiation with inclusion of multiple scattering is calculated through the path-integral method, and the analytical expressions are presented. The condition that multiple scattering processes dominate the angular distribution is obtained.
Investigation of multiple scattering processes resolved in clouds using a flash lidar
NASA Astrophysics Data System (ADS)
Weimer, C. S.; Hu, Y.; Saiki, E.; Delker, T.; Applegate, J.; Ramond, T.
2010-12-01
The Topographic Mapping Flash Lidar (TMFL) instrument developed at Ball Aerospace has been used to investigate the phenomenon of multiple scattering of the lidar signal inside a medium such as a water cloud. This behavior has been observed during a recent flight of the instrument aboard a Twin Otter aircraft flying over a steam plume. TMFL illuminates a line that extends across-track, and signal was observed off-axis over multiple pixels of the flash focal plane array. Thus the multiple scattering intensities are spatially sub-sampled, in addition to obtaining range resolutions. Variation of scattering strengths with off-axis distance is compared to those predicted by atmospheric models. It has been hypothesized that multiple scattering effects could account for a major source of error for space-based lidars such as CALIPSO, which samples atmospheric backscatter over a column. However, the physics behind multiple scattering is not well -understood and thus the effect cannot be sufficiently characterized to improve the error bars. The spatial resolution TMFL therefore provides a tool to quantify the effects of the processes of multiple scattering in lidar instrument signal. In addition, TMFL has recorded returns from the surface of a lake, and the strength of water surface returns can be correlated to the roughness of the water. That in turn can be tied to aerosol concentrations near the water surface.
Simplified multiple scattering model for radiative transfer in turbid water
NASA Technical Reports Server (NTRS)
Ghovanlou, A. H.; Gupta, G. N.
1978-01-01
Quantitative analytical procedures for relating selected water quality parameters to the characteristics of the backscattered signals, measured by remote sensors, require the solution of the radiative transport equation in turbid media. Presented is an approximate closed form solution of this equation and based on this solution, the remote sensing of sediments is discussed. The results are compared with other standard closed form solutions such as quasi-single scattering approximations.
Backscattered UV radiation - Effects of multiple scattering and the lower boundary of the atmosphere
NASA Technical Reports Server (NTRS)
Aruga, T.; Heath, D. F.
1982-01-01
A method is proposed for the calculation of a multiple-scattering correction to the single-scattering calculation of the radiance of the terrestrial atmosphere resulting from backscattered ultraviolet solar radiation in the spectral region used in the ozone profile inversion. This method uses jointly the usual analytical and Monte Carlo methods. Effects of the lower boundary of the atmosphere, cloud tops, and ground surface are investigated both qualitatively and quantitatively. The ratio of multiple to single scattering is determined, and its importance in ozone profile inversion of backscattered UV solar radiation from the terrestrial atmosphere is evaluated. The polarization of the atmospheric radiance is treated briefly.
[Multiple scattering of visible and infrared light by sea fog over wind driving rough sea surface].
Sun, Xian-Ming; Wang, Hai-Hua; Lei, Cheng-Xin; Shen, Jin
2013-08-01
The present paper is concerned with computing the multiple scattering characteristics of a sea fog-sea surface couple system within this context. The single scattering characteristics of sea fog were studied by Mie theory, and the multiple scattering of sunlight by single sea fog layer was studied by radiative transfer theory. The reflection function of a statistically rough ocean surface was obtained using the standard Kirchhoff formulation, with shadowing effects taken into account. The reflection properties of the combined sea fog and ocean surface were obtained employing the adding method, and the results indicated that the reflected light intensity of sea fog increased with the sea background.
Characterization and modeling of ultrasonic structural noise in the multiple scattering regime
NASA Astrophysics Data System (ADS)
Bedetti, T.; Dorval, V.; Jenson, F.; Derode, A.
2013-01-01
Multiple scattering can occur when performing ultrasonic measurements on highly scattering materials such as coarse grain steel or concrete. It constitutes in general a limiting factor for NDE techniques. In this communication, a method to simulate the structural noise due to multiple scattering is described. It requires three parameters: the diffusion constant, the elastic mean free path and the correlation distance. A method to obtain these parameters based on a single measurement procedure is presented. This approach has been applied to samples of coarse grain steel. The backscattered noise has been calculated for different probes and compared to experimental signals.
In-depth analyses of oceanic CloudSat reflectivity profiles burdened by multiple-scattering
NASA Astrophysics Data System (ADS)
Battaglia, A.; Simmer, C.
2009-04-01
Multiple scattering strongly affects the CloudSat Profiling Radar reflectivity when the satellite is over-passing moderate and heavy precipitation systems. Following a criterion developed by the authors in the past (Battaglia et al., 2008) and based on the freezing level altitude (FLA) and on the path integrated attenuation (PIA), oceanic CloudSat reflectivities profiles affected by multiple scattering are identified and further analysed. Profiles are clustered according to PIA, FLA, position and value of the profile maximum reflectivity, jump of the reflectivity from pixels close to the surface to the surface pixel. This last variable represents a rough estimate of the multiple-scattering strength, i.e. of the reflectivity enhancement produced by higher-than-one scattering orders in proximity to the surface. The slopes of the reflectivity profiles (which results from the combined effect of vertical variability, attenuation and multiple scattering) are then computed at different altitudes above the surface and their variability is discussed in relationships to the profile characteristic variables. Results from one full year of CloudSat data are discussed and compared with numerical simulation outputs based on Cloud Resolving Model (Battaglia and Simmer 2008). This study has strong relevance for attenuation-based retrievals of rainfall from high frequency space-borne radars (Matrosov et al., 2008). Battaglia, A., J. Haynes, T. L'Ecuyer, and C. Simmer, Identifying multiple-scattering-affected profiles in CloudSat observations over the Oceans, J. Geoph. Res., 113, D00A17, doi:101029/2008JD009960 Battaglia, A., and C. Simmer, How does multiple scattering affect the spaceborne W-band radar measurements at ranges close to and crossing the surface-range?, IEEE Tran. Geo. Rem. Sens., , Vol. 46, No. 6,1644-1651, 2008 Matrosov, S., Battaglia, A., Rodriguez, P. Effects of multiple scattering on attenuation-based retrievals of stratiform rainfall from CloudSat, J. Atm. Oc
The Dual Wavelength Ratio knee: a signature of multiple scattering in airborne Ku-Ka observations
NASA Astrophysics Data System (ADS)
Battaglia, Alessandro; Tanelli, Simone; Heymsfield, Gerald; Tian, Lin
2014-05-01
Deep convective systems observed by the HIWRAP radar during the 2011 MC3E field campaign in Oklahoma provide the first evidence of multiple scattering effects simultaneously at Ku and Ka band. One feature is novel and noteworthy: often, in correspondence to shafts with strong convection and when moving from the top of the cloud downward, the dual wavelength ratio (DWR) first increases as usual in Ku-/Ka-band observations, but then it reaches a maximum and after that point it steadily decreases all the way to the surface, forming what will be hereinafter referred to as a knee. This DWR knee cannot be reproduced by single-scattering theory under almost any plausible cloud microphysical profile, on the other hand it is explained straightforwardly with the help of multiple scattering theory when simulations involving hail-bearing convective cores with large horizontal extents are performed. The DWR reduction in the lower troposphere (i.e., DWR increasing with altitude) is interpreted as the result of multiple scattering pulse stretching caused by the highly-diffusive hail layer positioned high up in the atmosphere, with Ka multiple scattering typically exceeding that occurring in the Ku channel. Since the effects of multiple scattering increase with increasing footprint size, if multiple scattering effects are present in the aircraft measurements, they are likely to be more pronounced in the space-borne dual-frequency Ku - Ka radar observations, envisaged for the NASA-JAXA Global Precipitation (GPM) Measurement Mission, whose launch is expected in February 2014. Our notional study supports the idea that DWR knees will be observed by the GPM radar when overflying high-density ice shafts embedded in large convective systems and suggests that their explanation must not be sought in differential attenuation or differential Mie but via multiple scattering effects.
Cluster multiple-scattering theory for medium-energy electron diffraction
NASA Astrophysics Data System (ADS)
Barton, J. J.; Xu, M.-L.; van Hove, M. A.
1988-06-01
A theory of medium-energy (100-5000-eV) electron diffraction (MEED) is developed from a multiple-scattering, curved-wave theory of photoelectron diffraction. It may be called ``near-field expansion in clusters.'' Only selected important scattering events are included and these are computed in times proportional to electron wave number by using a generalized scattering-factor method (conventional low-energy electron-diffraction methods require computations proportional to at least the fourth power of the wave number, while the ``chain'' method for MEED scales as at least the square of the wave number). This removes the most serious barrier to a multiple-scattering analysis for surface-structure determination. A direct summation over atoms and scattering paths is used, avoiding any assumptions of periodicity in the surface structure. The theory allows a clearer understanding of the relationship between diffraction intensities and surface structure than heretofore possible.
Scattering from phase-separated vesicles. I. An analytical form factor for multiple static domains
Heberle, Frederick A.; Anghel, Vinicius N. P.; Katsaras, John
2015-08-18
This is the first in a series of studies considering elastic scattering from laterally heterogeneous lipid vesicles containing multiple domains. Unique among biophysical tools, small-angle neutron scattering can in principle give detailed information about the size, shape and spatial arrangement of domains. A general theory for scattering from laterally heterogeneous vesicles is presented, and the analytical form factor for static domains with arbitrary spatial configuration is derived, including a simplification for uniformly sized round domains. The validity of the model, including series truncation effects, is assessed by comparison with simulated data obtained from a Monte Carlo method. Several aspects of the analytical solution for scattering intensity are discussed in the context of small-angle neutron scattering data, including the effect of varying domain size and number, as well as solvent contrast. Finally, the analysis indicates that effects of domain formation are most pronounced when the vesicle's average scattering length density matches that of the surrounding solvent.
Feasibility Study of Compton Scattering Enhanced Multiple Pinhole Imager for Nuclear Medicine
Meng, L. J.; Rogers, W. L.; Clinthorne, N. H.
2016-01-01
This paper presents a feasibility study of a Compton scattering enhanced (CSE) multiple pinhole imaging system for gamma rays with energy of 140keV or higher. This system consists of a multiple-pinhole collimator, a position sensitive scintillation detector as used in standard Gamma camera, and a Silicon pad detector array, inserted between the collimator and the scintillation detector. The problem of multiplexing, normally associated with multiple pinhole system, is reduced by using the extra information from the detected Compton scattering events. In order to compensate for the sensitivity loss, due to the low probability of detecting Compton scattered events, the proposed detector is designed to collect both Compton scattering and Non-Compton events. It has been shown that with properly selected pinhole spacing, the proposed detector design leads to an improved image quality.
Influence of multiple scattering on CloudSat measurements in snow: A model study
NASA Astrophysics Data System (ADS)
Matrosov, Sergey Y.; Battaglia, Alessandro
2009-06-01
The effects of multiple scattering on larger precipitating hydrometers have an influence on measurements of the spaceborne W-band (94 GHz) CloudSat radar. This study presents initial quantitative estimates of these effects in “dry” snow using radiative transfer calculations for appropriate snowfall models. It is shown that these effects become significant (i.e., greater than approximately 1 dB) when snowfall radar reflectivity factors are greater than about 10-15 dBZ. Reflectivity enhancement due to multiple scattering can reach 4-5 dB in heavier stratiform snowfalls. Multiple scattering effects counteract signal attenuation, so the observed CloudSat reflectivity factors in snowfall could be relatively close to the values that would be observed in the case of single scattering and the absence of attenuation.
NASA Astrophysics Data System (ADS)
Kaduwela, Ajith P.
We apply a new separable-Green's-function matrix method due to Rehr and Albers (Phys. Rev. B4l (1990) 8139) to a multiple scattering treatment of photoelectron diffraction and Auger electron diffraction. This cluster -based method permits building up successive orders of scattering and judging the approach to convergence in a convenient and time-saving way. We include multiple scattering up to tenth order and can treat photoelectron emission form any initial state (s, p, d, or f) with full final-state interference. This new approach is used to simulate emission from linear and bent chains of atoms, from epitaxial overlayers and multilayer substrates and from atomic and molecular adsorbates, and various conclusions are drawn concerning the range of utility of the method and the geometric structures for which multiple scattering effects must be considered.
The correction for multiple scattering of the lidar retrieving in thin clouds
NASA Astrophysics Data System (ADS)
Melnikova, Irina; Vasilyev, Alexander; Samulenkov, Dmitriy; Sapunov, Maxim; Tagaev, Vladislav
2017-02-01
The lidar sounding in the cloudy atmosphere needs accounting the multiple scattering. The standard approach for the retrieval of optical parameters and morphology of aerosol particles might be not sufficient. Here the theoretical analyti cal and numerical methods for calculation of multiple scattering contributions in the backscattered lidar signal are used. The optical thickness of clouds that provokes a distinct multiply scattered light is determined. The possible correction as subtraction of the multiple scattered part from registered signal is proposed for clouds optically thicker than 4. The routine processing is possible for corrected the lidar signal if cloud optically thicker than 4 or without correction if cloud is opt ically thinner than 4. Considered observational data obtained in St. Petersburg lidar station appeared thin enough for application the standard procedure without correction. Optical parameters in and out of cloud are obtained.
A two-dimensional Helmhotlz equation solution for the multiple cavity scattering problem
NASA Astrophysics Data System (ADS)
Li, Peijun; Wood, Aihua
2013-05-01
Here considered is the mathematical analysis and numerical computation of the electromagnetic wave scattering by multiple cavities embedded in an infinite ground plane. Above the ground plane the space is filled with a homogeneous medium, while the interiors of the cavities are filled with inhomogeneous media characterized by variable permittivities. By introducing a new transparent boundary condition on the cavity apertures, the multiple cavity scattering problem is reduced to a boundary value problem of the two-dimensional Helmholtz equation imposed in the separated interior domains of the cavities. The existence and uniqueness of the weak solution for the model problem is achieved via a variational approach. A block Gauss-Seidel iterative method is introduced to solve the coupled system of the multiple cavity scattering problem, where only a single cavity scattering problem is required to be solved at each iteration. Numerical examples demonstrate the efficiency and accuracy of the proposed method.
Multiple scattering of arbitrarily incident Bessel beams by random discrete particles.
Cui, Zhiwei; Han, Yiping; Ai, Xia
2013-11-01
In this paper, we introduce an efficient numerical method to characterize the multiple scattering by random discrete particles illuminated by Bessel beams with arbitrary incidence. Specifically, the vector expressions of Bessel beams that perfectly satisfy Maxwell's equations in combination with rotation Euler angles are used to represent the arbitrarily incident Bessel beams. A hybrid vector finite element-boundary integral-characteristic-basis function method is utilized to formulate the scattering problems involving multiple discrete particles with a random distribution. Due to the flexibility of the finite element method, the adopted method can conveniently deal with the problems of multiple scattering by randomly distributed homogeneous particles, inhomogeneous particles, and anisotropic particles. Some numerical results are included to illustrate the validity and capability of the proposed method and to show the scattering behaviors of random discrete particles when they are illuminated by Bessel beams.
Coupling of multiple coulomb scattering and energy loss and straggling in HZETRN
NASA Astrophysics Data System (ADS)
Mertens, C. J.; Walker, S. A.; Wilson, J. W.; Singleterry, R. C.; Tweed, J.
Current developments in HZETRN are focused towards a full three-dimensional and computationally efficient deterministic transport code capable of simulating radiation transport with either space or laboratory boundary conditions One aspect of the new version of HZETRN is the inclusion of small-angle multiple Coulomb scattering of incident ions by target nuclei While the effects of multiple scattering are negligible in the space radiation environment multiple scattering must be included in laboratory transport code simulations to accurately model ion beam experiments to simulate the physical and biological-effective radiation dose and to develop new methods and strategies for light ion radiation therapy In this paper we present the theoretical formalism and computation procedures for incorporating multiple scattering into HZETRN and coupling the ion-nuclear scattering interactions with energy loss and straggling Simulations of the effects of multiple scattering on ion beam characterization will be compared with results from laboratory measurements which include path-length corrections angular and lateral broadening and absorbed dose
Multiple gold-dimer detection from large scattering background
NASA Astrophysics Data System (ADS)
Hong, Xin; Jin, Zheng
2016-10-01
Gold nanoparticles exhibit unique plasmonic optical properties in visible to near infrared band. Especially the coupling effect existing at the gap between a closely linked particle pair can make the local field strongly enhanced. These properties make gold particles more attractive to be employed as molecular probes in biomedical related fundamental and clinical researches. However in the bio-system exist many large molecules or groups, whose optical signals can strongly depress the gold particles without detectable. In this paper, we proposed a method to extract the targets which are labelled by gold dimer pairs from large scattering background.
Multiple Point Dynamic Gas Density Measurements Using Molecular Rayleigh Scattering
NASA Technical Reports Server (NTRS)
Seasholtz, Richard; Panda, Jayanta
1999-01-01
A nonintrusive technique for measuring dynamic gas density properties is described. Molecular Rayleigh scattering is used to measure the time-history of gas density simultaneously at eight spatial locations at a 50 kHz sampling rate. The data are analyzed using the Welch method of modified periodograms to reduce measurement uncertainty. Cross-correlations, power spectral density functions, cross-spectral density functions, and coherence functions may be obtained from the data. The technique is demonstrated using low speed co-flowing jets with a heated inner jet.
NASA Astrophysics Data System (ADS)
Kulinich, P.; Krylov, V.
2006-10-01
A String Banana Template Method (SBTM) for track reconstruction in the presence of significant Multiple Scattering (MS) is described. The main idea of the method is based on the features of ensembles of tracks selected by three-fold coincidences. The SBTM provides a narrower search window than other methods by exploiting the features of such ensembles: it deals with particular "branches" in the MS "tree". A two-step track model with additional parameters to account for MS is used. The SBTM uses stored template fields generated by precise Monte Carlo (MC) simulation. SBTM capabilities in terms of track parameter resolution are demonstrated for a model spectrometer. This method has been implemented in the ROOT C++ framework and tested with MC simulations as well as with data from a heavy ion collision experiment using a silicon-based spectrometer with a complex geometry, moderate segmentation (≃mm) and non-uniform magnetic field. Primary tracks in the most central Au-Au collisions at √{sNN}=200 GeV with occupancy >20% and momenta down to ˜80 MeV/c (for pions) have been reconstructed with high efficiency.
Extrinsic extinction cross-section in the multiple acoustic scattering by fluid particles
NASA Astrophysics Data System (ADS)
Mitri, F. G.
2017-04-01
Cross-sections (and their related energy efficiency factors) are physical parameters used in the quantitative analysis of different phenomena arising from the interaction of waves with a particle (or multiple particles). Earlier works with the acoustic scattering theory considered such quadratic (i.e., nonlinear) quantities for a single scatterer, although a few extended the formalism for a pair of scatterers but were limited to the scattering cross-section only. Therefore, the standard formalism applied to viscous particles is not suitable for the complete description of the cross-sections and energy balance of the multiple-particle system because both absorption and extinction phenomena arise during the multiple scattering process. Based upon the law of the conservation of energy, this work provides a complete comprehensive analysis for the extrinsic scattering, absorption, and extinction cross-sections (i.e., in the far-field) of a pair of viscous scatterers of arbitrary shape, immersed in a nonviscous isotropic fluid. A law of acoustic extinction taking into consideration interparticle effects in wave propagation is established, which constitutes a generalized form of the optical theorem in multiple scattering. Analytical expressions for the scattering, absorption, and extinction cross-sections are derived for plane progressive waves with arbitrary incidence. The mathematical expressions are formulated in partial-wave series expansions in cylindrical coordinates involving the angle of incidence, the addition theorem for the cylindrical wave functions, and the expansion coefficients of the scatterers. The analysis shows that the multiple scattering cross-section depends upon the expansion coefficients of both scatterers in addition to an interference factor that depends on the interparticle distance. However, the extinction cross-section depends on the expansion coefficients of the scatterer located in a particular system of coordinates, in addition to the
Kokhanovsky, Alexander A
2007-04-01
Analytical equations for the diffused scattered light correction factor of Sun photometers are derived and analyzed. It is shown that corrections are weakly dependent on the atmospheric optical thickness. They are influenced mostly by the size of aerosol particles encountered by sunlight on its way to a Sun photometer. In addition, the accuracy of the small-angle approximation used in the work is studied with numerical calculations based on the exact radiative transfer equation.
NASA Astrophysics Data System (ADS)
Conway, R. R.
1983-06-01
Multiple scattering in a plane-parallel radiative transfer model, and a line-by-line synthesis of individual bands, are used to calculate the absorption and reemission by N2 of the Lyman-Birge-Hopfield (LBH) and Birge-Hopfield (BH) band systems in both the earth aurora and the dayglow of Titan. Iteration through successive scatterings indicates that fewer than ten scatterings are important, even for the thickest bands. The excitation rate caused by multiple scattering is sensitive to the vibrational population distribution of the ambient N2, especially for the BH system in the earth aurora. The LBH system has an enhanced sensitivity to vibrational temperature on Titan, due to the rapidly changing photoabsorption cross section of CH4 around 1400 A. It is suggested that certain Rydberg bands should have an intensity profile similar to that of the BH bands.
Reduction of scatter in diagnostic radiology by means of a scanning multiple slit assembly.
Barnes, G T; Cleare, H M; Brezovich, I A
1976-09-01
Evidence is presented that an array of long, narrow beam-defining slits scanning a patient coupled with scatter-eliminating slots beneath the patient will substantially reduce scatter in diagnostic radiology. Scatter/primary ratios and the distribution of scatter in the plane of the image detector have been measured as a function of slit width and slot depth for a long, narrow beam-defining geometry. Using these data, calculations for the scatter/primary ratio incident on the image detector are made for a multiple slit assembly and compared with conventional grids. An improvement in contrast is obtained with little or no increase in patient exposure. Design considerations for the construction of such an array and data trends are discussed.
NASA Technical Reports Server (NTRS)
Eloranta, E. W.; Piironen, P. K.
1996-01-01
Quantitative lidar measurements of aerosol scattering are hampered by the need for calibrations and the problem of correcting observed backscatter profiles for the effects of attenuation. The University of Wisconsin High Spectral Resolution Lidar (HSRL) addresses these problems by separating molecular scattering contributions from the aerosol scattering; the molecular scattering is then used as a calibration target that is available at each point in the observed profiles. While the HSRl approach has intrinsic advantages over competing techniques, realization of these advantages requires implementation of a technically demanding system which is potentially very sensitive to changes in temperature and mechanical alignments. This paper describes a new implementation of the HSRL in an instrumented van which allows measurements during field experiments. The HSRL was modified to measure depolarization. In addition, both the signal amplitude and depolarization variations with receiver field of view are simultaneously measured. This allows for discrimination of ice clouds from water clouds and observation of multiple scattering contributions to the lidar return.
NASA Astrophysics Data System (ADS)
Yu, Ting; Chaix, Jean-François; Komatitsch, Dimitri; Garnier, Vincent; Audibert, Lorenzo; Henault, Jean-Marie
2017-02-01
Multiple scattering is important when ultrasounds propagate in a heterogeneous medium such as concrete, the scatterer size of which is in the order of the wavelength. The aim of this work is to build a 2D numerical model of ultrasonic wave propagation integrating the multiple scattering phenomena in SPECFEM software. The coherent field of multiple scattering could be obtained by averaging numerical wave fields, and it is used to determine the effective phase velocity and attenuation corresponding to an equivalent homogeneous medium. After the creation of numerical model under several assumptions, its validation is completed in a case of scattering by one cylinder through the comparison with analytical solution. Two cases of multiple scattering by a set of cylinders at different concentrations are simulated to perform a parametric study (of frequency, scatterer concentration, scatterer size). The effective properties are compared with the predictions of Waterman-Truell model as well, to verify its validity.
Monte Carlo modelling of single and multiple Compton scattering profiles in a concrete material
NASA Astrophysics Data System (ADS)
Akar Tarim, U.; Ozmutlu, E. N.; Gurler, O.; Yalcin, S.; Gundogdu, O.; Sharaf, J. M.; Bradley, D. A.
2013-04-01
A Monte Carlo simulation study has been conducted of 60Co photons Compton scattered in concrete, illustrating the degraded energy spectra of gamma-ray radiation. Results are produced representing a NaI(Tl) detector model. We were able to analyse energy distributions of photons that reach the detector system after suffering several successive Compton scatterings in the target. The predicted decrease in intensity of single- and multiple-scattering peaks with increase in thickness of the target medium are in good agreement with experimental observations and findings reported by others.
Geometry dependence of optical pulse broadening in multiple scattering media
NASA Technical Reports Server (NTRS)
Thomas, R. W. L.; Holland, A. C.
1979-01-01
A Monte Carlo simulation method has been used to evaluate the temporal response at a variety of receivers to an instantaneous laser pulse input to a turbid medium. The results are compared to the description of the ensemble of all transmitted photons for which a diffusion theory was developed. It was shown that the arrival times for all photons transmitted through the cloud are exponentially distributed with a mean time that varies as the product of the cloud thickness and the momentum transfer optical depth. For large optical depths the mean time delay associated with all reflected photons was found to depend only on the cloud thickness. The impulse response function for receivers on the beam axis varied with field of view and for small fields of view it was dominated by single scattering even for optically thick clouds. In these cases, the mean time delay could be up to 10 to the 6th times shorter than that associated with all transmitted photons with a related increase in the maximum modulation frequency.
NASA Astrophysics Data System (ADS)
Liu, Xiaodong
2017-08-01
A sampling method by using scattering amplitude is proposed for shape and location reconstruction in inverse acoustic scattering problems. Only matrix multiplication is involved in the computation, thus the novel sampling method is very easy and simple to implement. With the help of the factorization of the far field operator, we establish an inf-criterion for characterization of underlying scatterers. This result is then used to give a lower bound of the proposed indicator functional for sampling points inside the scatterers. While for the sampling points outside the scatterers, we show that the indicator functional decays like the bessel functions as the sampling point goes away from the boundary of the scatterers. We also show that the proposed indicator functional continuously depends on the scattering amplitude, this further implies that the novel sampling method is extremely stable with respect to errors in the data. Different to the classical sampling method such as the linear sampling method or the factorization method, from the numerical point of view, the novel indicator takes its maximum near the boundary of the underlying target and decays like the bessel functions as the sampling points go away from the boundary. The numerical simulations also show that the proposed sampling method can deal with multiple multiscale case, even the different components are close to each other.
Lambert, Simon A; Näsholm, Sven Peter; Nordsletten, David; Michler, Christian; Juge, Lauriane; Serfaty, Jean-Michel; Bilston, Lynne; Guzina, Bojan; Holm, Sverre; Sinkus, Ralph
2015-08-28
Wave scattering provides profound insight into the structure of matter. Typically, the ability to sense microstructure is determined by the ratio of scatterer size to probing wavelength. Here, we address the question of whether macroscopic waves can report back the presence and distribution of microscopic scatterers despite several orders of magnitude difference in scale between wavelength and scatterer size. In our analysis, monosized hard scatterers 5 μm in radius are immersed in lossless gelatin phantoms to investigate the effect of multiple reflections on the propagation of shear waves with millimeter wavelength. Steady-state monochromatic waves are imaged in situ via magnetic resonance imaging, enabling quantification of the phase velocity at a voxel size big enough to contain thousands of individual scatterers, but small enough to resolve the wavelength. We show in theory, experiments, and simulations that the resulting coherent superposition of multiple reflections gives rise to power-law dispersion at the macroscopic scale if the scatterer distribution exhibits apparent fractality over an effective length scale that is comparable to the probing wavelength. Since apparent fractality is naturally present in any random medium, microstructure can thereby leave its fingerprint on the macroscopically quantifiable power-law exponent. Our results are generic to wave phenomena and carry great potential for sensing microstructure that exhibits intrinsic fractality, such as, for instance, vasculature.
NASA Astrophysics Data System (ADS)
Lambert, Simon A.; Näsholm, Sven Peter; Nordsletten, David; Michler, Christian; Juge, Lauriane; Serfaty, Jean-Michel; Bilston, Lynne; Guzina, Bojan; Holm, Sverre; Sinkus, Ralph
2015-08-01
Wave scattering provides profound insight into the structure of matter. Typically, the ability to sense microstructure is determined by the ratio of scatterer size to probing wavelength. Here, we address the question of whether macroscopic waves can report back the presence and distribution of microscopic scatterers despite several orders of magnitude difference in scale between wavelength and scatterer size. In our analysis, monosized hard scatterers 5 μ m in radius are immersed in lossless gelatin phantoms to investigate the effect of multiple reflections on the propagation of shear waves with millimeter wavelength. Steady-state monochromatic waves are imaged in situ via magnetic resonance imaging, enabling quantification of the phase velocity at a voxel size big enough to contain thousands of individual scatterers, but small enough to resolve the wavelength. We show in theory, experiments, and simulations that the resulting coherent superposition of multiple reflections gives rise to power-law dispersion at the macroscopic scale if the scatterer distribution exhibits apparent fractality over an effective length scale that is comparable to the probing wavelength. Since apparent fractality is naturally present in any random medium, microstructure can thereby leave its fingerprint on the macroscopically quantifiable power-law exponent. Our results are generic to wave phenomena and carry great potential for sensing microstructure that exhibits intrinsic fractality, such as, for instance, vasculature.
NASA Astrophysics Data System (ADS)
Zimnyakov, D. A.; Yuvchenko, S. A.; Taskina, L. A.; Alonova, M. V.; Isaeva, E. A.; Isaeva, A. A.; Ushakova, O. V.
2016-04-01
The effect of increase in the uncertainty of local polarization states of laser light forward scattered by random media was studied in the experiments with phantom scatterers. At macroscopic level this effect is related to decay in the degree of polarization of scattered light in the course of transition from single to multiple scattering. Gelatin layers with embedded titania particles were used as the phantom scatterers. Features of distributions of local polarization states in various polarization coordinates were considered.
Supersymmetric and Kaluza-Klein Particles Multiple Scattering in the Earth
Albuquerque, Ivone; Klein, Spencer
2009-05-19
Neutrino telescopes with cubic kilometer volume have the potential to discover new particles. Among them are next to lightest supersymmetric (NLSPs) and next to lightest Kaluza-Klein (NLKPs) particles. Two NLSPs or NLKPs will transverse the detector simultaneously producing parallel charged tracks. The track separation inside the detector can be a few hundred meters. As these particles might propagate a few thousand kilometers before reaching the detector, multiple scattering could enhance the pair separation at the detector. We find that the multiple scattering will alter the separation distribution enough to increase the number of NLKP pairs separated by more than 100 meters (a reasonable experimental cut) by up to 46% depending on the NLKP mass. Vertical upcoming NLSPs will have their separation increased by 24% due to multiple scattering.
NASA Astrophysics Data System (ADS)
Fiorino, Steven T.; Elmore, Brannon; Schmidt, Jaclyn; Matchefts, Elizabeth; Burley, Jarred L.
2016-05-01
Properly accounting for multiple scattering effects can have important implications for remote sensing and possibly directed energy applications. For example, increasing path radiance can affect signal noise. This study describes the implementation of a fast-calculating two-stream-like multiple scattering algorithm that captures azimuthal and elevation variations into the Laser Environmental Effects Definition and Reference (LEEDR) atmospheric characterization and radiative transfer code. The multiple scattering algorithm fully solves for molecular, aerosol, cloud, and precipitation single-scatter layer effects with a Mie algorithm at every calculation point/layer rather than an interpolated value from a pre-calculated look-up-table. This top-down cumulative diffusivity method first considers the incident solar radiance contribution to a given layer accounting for solid angle and elevation, and it then measures the contribution of diffused energy from previous layers based on the transmission of the current level to produce a cumulative radiance that is reflected from a surface and measured at the aperture at the observer. Then a unique set of asymmetry and backscattering phase function parameter calculations are made which account for the radiance loss due to the molecular and aerosol constituent reflectivity within a level and allows for a more accurate characterization of diffuse layers that contribute to multiple scattered radiances in inhomogeneous atmospheres. The code logic is valid for spectral bands between 200 nm and radio wavelengths, and the accuracy is demonstrated by comparing the results from LEEDR to observed sky radiance data.
Girard, Jules; Maire, Guillaume; Giovannini, Hugues; Belkebir, Kamal; Chaumet, Patrick C.; Sentenac, Anne; Talneau, Anne
2010-12-15
The resolution of optical far-field microscopes is classically diffraction-limited to half the illumination wavelength. We show experimentally that this fundamental limit does not apply in the multiple scattering regime. We used tomographic diffractive microscopy at 633 nm to image two pairs of closely spaced rods (with a width and interdistance of 50 nm) of widely different diffractive properties. Using an inversion algorithm accounting for multiple scattering, only the pair of highly diffracting rods could be clearly visualized with a resolution similar to that of an atomic force microscope.
MULTIPLE-PLANET SCATTERING AND THE ORIGIN OF HOT JUPITERS
Beauge, C.; Nesvorny, D.
2012-06-01
Doppler and transit observations of exoplanets show a pile-up of Jupiter-size planets in orbits with a 3 day period. A fraction of these hot Jupiters have retrograde orbits with respect to the parent star's rotation, as evidenced by the measurements of the Rossiter-McLaughlin effect. To explain these observations we performed a series of numerical integrations of planet scattering followed by the tidal circularization and migration of planets that evolved into highly eccentric orbits. We considered planetary systems having three and four planets initially placed in successive mean-motion resonances, although the angles were taken randomly to ensure orbital instability in short timescales. The simulations included the tidal and relativistic effects, and precession due to stellar oblateness. Our results show the formation of two distinct populations of hot Jupiters. The inner population (Population I) is characterized by semimajor axis a < 0.03 AU and mainly formed in the systems where no planetary ejections occurred. Our follow-up integrations showed that this population was transient, with most planets falling inside the Roche radius of the star in <1 Gyr. The outer population of hot Jupiters (Population II) formed in systems where at least one planet was ejected into interstellar space. This population survives the effects of tides over >1 Gyr and fits nicely the observed 3 day pile-up. A comparison between our three-planet and four-planet runs shows that the formation of hot Jupiters is more likely in systems with more initial planets. Due to the large-scale chaoticity that dominates the evolution, high eccentricities and/or high inclinations are generated mainly by close encounters between the planets and not by secular perturbations (Kozai or otherwise). The relative proportion of retrograde planets seems of be dependent on the stellar age. Both the distribution of almost aligned systems and the simulated 3 day pile-up also fit observations better in our four
Multiple-scattering effects on spaceborne lidar dedicated to forests survey
NASA Astrophysics Data System (ADS)
Shang, Xiaoxia; Chazette, Patrick
2014-05-01
The role of forests in the climate balance of the Earth system leads us to consider their monitoring on a global scale. This militates towards the establishment of a long-term monitoring of both forest areas and their evolution, in accordance with the climatic scales. Lidar and radar are promising instruments for such observations from spaceborne stations and present strong complementarity via their use in synergy. Here, we will focus on lidar technology where one of the major difficulties is the choice of the emitted wavelength. In fact, for space observations, multiple-scattering may significantly affect the scattering of the propagating laser light through the forest canopy. Indeed, depending on the lidar system parameters (e.g. wavelength, field of view) and on the tree species, spaceborne lidar observations are more or less perturbed by multiple-scattering. To assess the multiple-scattering effects on lidar signal return, a Monte Carlo simulator has been built. The simulator is constraint by actual measurements performed by an airborne lidar using an ultraviolet wavelength (355 nm). The airborne lidar sampled forest types (e.g. oaks, maritime pines, poplars) representative of European mid-latitude forests to constitute a data base of extinction coefficient vertical profiles in the canopy. For the simulations, the leaves have been considered as Lambertian surfaces, but it is not a limitation for the statistic modelling. For example, the multiple-scattering may lead to a significant overestimation of the poplar crown depths, larger than 4 m. The footprint, accounting for the altitude of the satellite orbit, dimensions the amplitude of the multiple-scattering effects. It has to be assessed taking into account the ground slope. Results established using UV airborne lidar coupled with a Monte Carlo approach will be presented and discussed.
Multiple scattering dynamics of fermions at an isolated p-wave resonance
NASA Astrophysics Data System (ADS)
Thomas, R.; Roberts, K. O.; Tiesinga, E.; Wade, A. C. J.; Blakie, P. B.; Deb, A. B.; Kjærgaard, N.
2016-07-01
The wavefunction for indistinguishable fermions is anti-symmetric under particle exchange, which directly leads to the Pauli exclusion principle, and hence underlies the structure of atoms and the properties of almost all materials. In the dynamics of collisions between two indistinguishable fermions, this requirement strictly prohibits scattering into 90° angles. Here we experimentally investigate the collisions of ultracold clouds fermionic 40K atoms by directly measuring scattering distributions. With increasing collision energy we identify the Wigner threshold for p-wave scattering with its tell-tale dumb-bell shape and no 90° yield. Above this threshold, effects of multiple scattering become manifest as deviations from the underlying binary p-wave shape, adding particles either isotropically or axially. A shape resonance for 40K facilitates the separate observation of these two processes. The isotropically enhanced multiple scattering mode is a generic p-wave threshold phenomenon, whereas the axially enhanced mode should occur in any colliding particle system with an elastic scattering resonance.
Multiple scattering dynamics of fermions at an isolated p-wave resonance
Thomas, R.; Roberts, K. O.; Tiesinga, E.; Wade, A. C. J.; Blakie, P. B.; Deb, A. B.; Kjærgaard, N.
2016-01-01
The wavefunction for indistinguishable fermions is anti-symmetric under particle exchange, which directly leads to the Pauli exclusion principle, and hence underlies the structure of atoms and the properties of almost all materials. In the dynamics of collisions between two indistinguishable fermions, this requirement strictly prohibits scattering into 90° angles. Here we experimentally investigate the collisions of ultracold clouds fermionic 40K atoms by directly measuring scattering distributions. With increasing collision energy we identify the Wigner threshold for p-wave scattering with its tell-tale dumb-bell shape and no 90° yield. Above this threshold, effects of multiple scattering become manifest as deviations from the underlying binary p-wave shape, adding particles either isotropically or axially. A shape resonance for 40K facilitates the separate observation of these two processes. The isotropically enhanced multiple scattering mode is a generic p-wave threshold phenomenon, whereas the axially enhanced mode should occur in any colliding particle system with an elastic scattering resonance. PMID:27396294
NASA Astrophysics Data System (ADS)
Parnell, William J.; Abrahams, I. David
2010-11-01
In this article we attempt to clarify various notions regarding multiple point scattering. We consider several predictions for the effective material properties of an inhomogeneous slab region which can be derived from classical multiple scattering theories. In particular we are interested in the point scattering limit when wavelengths λ0 ≫ l ∼ a where l is the characteristic length-scale of the distance between inclusions and a is the characteristic length-scale of inclusions. In this limit we are able to derive effective properties which are physically valid for any volume fraction φ, except in the sound-soft scatterer case where there is a condition on the size of φ. We shall confine attention to random distributions of inclusions and employ the Quasi-Crystalline Approximation to yield results. In particular we discuss the different scenarios of acoustics and antiplane elasticity and stress the reciprocity between these two problems which means that they can be solved simultaneously. We make various statements regarding the efficacy of the various multiple scattering theories in the prediction of effective material properties in the quasi-static limit.
On the multiple scattering of VHF/UHF waves in the equatorial ionosphere
NASA Technical Reports Server (NTRS)
Vats, H. O.
1981-01-01
Using amplitude data of radio beacons at 40, 140, and 360 MHz from ATS 6 (phase II), an attempt has been made to study scattering of these waves in the equatorial ionosphere. A comparison of observed scintillation index S sub 4 with the theoretical results of the multiple scattering approach and variation of autocorrelation time with frequency indicates that this theory explains the results to a large extent. A comparison of power spectra of amplitude records with the ionograms of a nearby equatorial station has led to the following conclusions: the change from a weak scattering regime to a strong scattering regime is gradual and occurs because of the gradual decrease in the scale size of the irregularities (i.e., broadening of the spectra) and the gradual increase in the thickness of the irregular region.
Rakotonarivo, S T; Walker, S C; Kuperman, W A; Roux, P
2011-12-01
A method to actively localize a small perturbation in a multiple scattering medium using a collection of remote acoustic sensors is presented. The approach requires only minimal modeling and no knowledge of the scatterer distribution and properties of the scattering medium and the perturbation. The medium is ensonified before and after a perturbation is introduced. The coherent difference between the measured signals then reveals all field components that have interacted with the perturbation. A simple single scatter filter (that ignores the presence of the medium scatterers) is matched to the earliest change of the coherent difference to localize the perturbation. Using a multi-source/receiver laboratory setup in air, the technique has been successfully tested with experimental data at frequencies varying from 30 to 60 kHz (wavelength ranging from 0.5 to 1 cm) for cm-scale scatterers in a scattering medium with a size two to five times bigger than its transport mean free path. © 2011 Acoustical Society of America
NASA Astrophysics Data System (ADS)
Ma, L. X.; Tan, J. Y.; Zhao, J. M.; Wang, F. Q.; Wang, C. A.
2017-01-01
The radiative transfer equation (RTE) has been widely used to deal with multiple scattering of light by sparsely and randomly distributed discrete particles. However, for densely packed particles, the RTE becomes questionable due to strong dependent scattering effects. This paper examines the accuracy of RTE by comparing with the exact electromagnetic theory. For an imaginary spherical volume filled with randomly distributed, densely packed spheres, the RTE is solved by the Monte Carlo method combined with the Percus-Yevick hard model to consider the dependent scattering effect, while the electromagnetic calculation is based on the multi-sphere superposition T-matrix method. The Mueller matrix elements of the system with different size parameters and volume fractions of spheres are obtained using both methods. The results verify that the RTE fails to deal with the systems with a high-volume fraction due to the dependent scattering effects. Apart from the effects of forward interference scattering and coherent backscattering, the Percus-Yevick hard sphere model shows good accuracy in accounting for the far-field interference effects for medium or smaller size parameters (up to 6.964 in this study). For densely packed discrete spheres with large size parameters (equals 13.928 in this study), the improvement of dependent scattering correction tends to deteriorate. The observations indicate that caution must be taken when using RTE in dealing with the radiative transfer in dense discrete random media even though the dependent scattering correction is applied.
Relation between circular and linear depolarization ratios under multiple-scattering conditions.
Roy, Gilles; Roy, Nathalie
2008-12-10
A simple relationship is established between the linear and the circular depolarization ratios averaged over the azimuth angle of clouds made of spherical particles. The relationship is validated theoretically using double-scattering calculations; in the framework, the measurements are performed with a multiple-field-of-view lidar (MFOV) lidar. The relationship is also validated using data obtained with MFOV lidar equipped with linear and circular polarization measurement capabilities. The experimental data support theoretical results for small optical depths. At higher optical depths and large fields of view, the contribution of multiple scatterings is important; experimental data suggest that the relationship established between the linear and circular depolarization stays valid as long as the main depolarization mechanism comes from one scattering (most likely a backscattering a few degrees away from 180 degrees ).
NASA Technical Reports Server (NTRS)
Davis, A. B.; Varnai, T.; Marshak, A.
2010-01-01
The primary goal of NASA's current ICESat and future ICESat2 missions is to map the altitude of the Earth's land ice with high accuracy using laser altimetry technology, and to measure sea ice freeboard. Ice however is a highly transparent optical medium with variable scattering and absorption properties. Moreover, it is often covered by a layer of snow with varying depth and optical properties largely dependent on its age. We describe a modeling framework for estimating the potential altimetry bias caused by multiple scattering in the layered medium. We use both a Monte Carlo technique and an analytical diffusion model valid for optically thick media. Our preliminary numerical results are consistent with estimates of the multiple scattering delay from laboratory measurements using snow harvested in Greenland, namely, a few cm. Planned refinements of the models are described.
NASA Technical Reports Server (NTRS)
Otterman, Joseph; Brakke, T. W.
1991-01-01
All orders of scattering are analyzed for two artifical canopies. The SHL canopy consists of Small Horizontal Leaves that are much smaller than the leaf-to-leaf spacing. The IHL canopy consists of Infinite Horizontal Layers, where each leaf is of infinite extent (a horizontal plane). Hemispheric leaf reflectances and transmittances independent of the direction of illumination lead to exact solutions for these models. Sunlight that penetrates to a given leaf area index level is much stronger in an SHL canopy than that in IHL; but the difference becomes muted when leaf transmittance is large. Multiple scattering enhances the hemispheric canopy reflectance more strongly in SHL than it does in IHL. The enhancement depends linearly on leaf transmittance in SHL and on the transmittance squared in IHL. Comparison with measured reflectances indicates that IHL model grossly underestimates multiple scattering in soybean canopies.
Chen, Tianrun; Ratilal, Purnima; Makris, Nicholas C
2008-11-01
An analytical expression is derived for the temporal coherence of an acoustic field after multiple forward scattering through random three-dimensional (3D) inhomogeneities in an ocean waveguide. This expression makes it possible to predict the coherence time scale of field fluctuations in ocean-acoustic measurements from knowledge of the oceanography. It is used to explain the time scale of acoustic field fluctuations observed at megameter ranges in various deep ocean-acoustic transmission experiments. It is shown that this time scale is nonlinearly related to the much longer coherence time scale of deep ocean internal waves through a multiple forward scattering process. It is also shown that 3D scattering effects become pronounced when the acoustic Fresnel width exceeds the cross-range coherence length of the deep ocean internal waves, which lead to frequency and range-dependent power losses in the forward field that may help to explain historic long range measurements.
Simulation of multiple scattering in the systems with complicated phase function
NASA Astrophysics Data System (ADS)
Aksenova, E. V.; Kokorin, D. I.; Romanov, V. P.
2015-11-01
We consider simulation of multiple scattering of waves in isotropic and anisotropic media. The focus is on the construction of the phase function interpolation for the single scattering. The procedure is based on the construction of the adaptive partitioning of the angular variables that determine the phase function. The developed interpolation method allows us rather quickly to perform calculations for systems with very complicated phase function. Application of the proposed method is illustrated by calculating the multiple scattering of light in a nematic liquid crystal (NLC) which presents the uniaxial anisotropic system. For this system the grid corresponding to the adaptive partitioning is constructed and the transition to the diffusion regime for the photon distribution is presented.
Low-energy Auger electron diffraction: influence of multiple scattering and angular momentum
NASA Astrophysics Data System (ADS)
Chassé, A.; Niebergall, L.; Kucherenko, Yu.
2002-04-01
The angular dependence of Auger electrons excited from single-crystal surfaces is treated theoretically within a multiple-scattering cluster model taking into account the full Auger transition matrix elements. In particular the model has been used to discuss the influence of multiple scattering and angular momentum of the Auger electron wave on Auger electron diffraction (AED) patterns in the region of low kinetic energies. Theoretical results of AED patterns are shown and discussed in detail for Cu(0 0 1) and Ni(0 0 1) surfaces, respectively. Even though Cu and Ni are very similar in their electronic and scattering properties recently strong differences have been found in AED patterns measured in the low-energy region. It is shown that the differences may be caused to superposition of different electron diffraction effects in an energy-integrated experiment. A good agreement between available experimental and theoretical results has been achieved.
Shao, Peng; Cox, Ben; Zemp, Roger J
2011-07-01
While photoacoustic methods offer significant promise for high-resolution optical contrast imaging, quantification has thus far proved challenging. In this paper, a noniterative reconstruction technique for producing quantitative photoacoustic images of both absorption and scattering perturbations is introduced for the case when the optical properties of the turbid background are known and multiple optical illumination locations are used. Through theoretical developments and computational examples, it is demonstrated that multiple-illumination photoacoustic tomography (MI-PAT) can alleviate ill-posedness due to absorption-scattering nonuniqueness and produce quantitative high-resolution reconstructions of optical absorption, scattering, and Gruneisen parameter distributions. While numerical challenges still exist, we show that the linearized MI-PAT framework that we propose has orders of magnitude improved condition number compared with CW diffuse optical tomography.
NASA Technical Reports Server (NTRS)
Fymat, A. L.; Lenoble, J.
1979-01-01
The paper considers three complementary inverse multiple scattering problems relating to a uniquely defined atmospheric scattering model. Consideration is given to the appropriateness, for data inversion purposes, of intensities observed in diffuse reflection under a variety of experimental conditions; the uniqueness of the inverse solution is investigated. It is found that light curves representing monotonic variations, such as limb darkening curves and phase curves for a planetary (e.g., Venus) disk center are unsuitable for inferring atmospheric and scattering parameters.
Multiple-scattering model for inclusive proton production in heavy ion collisions
NASA Technical Reports Server (NTRS)
Cucinotta, Francis A.
1994-01-01
A formalism is developed for evaluating the momentum distribution for proton production in nuclear abrasion during heavy ion collisions using the Glauber multiple-scattering series. Several models for the one-body density matrix of nuclei are considered for performing numerical calculations. Calculations for the momentum distribution of protons in abrasion are compared with experimental data for inclusive proton production.
NASA Technical Reports Server (NTRS)
Luchini, Chris B.
1997-01-01
Development of camera and instrument simulations for space exploration requires the development of scientifically accurate models of the objects to be studied. Several planned cometary missions have prompted the development of a three dimensional, multi-spectral, anisotropic multiple scattering model of cometary coma.
Solution of a multiple-scattering inverse problem: electron diffraction from surfaces.
Saldin, D K; Seubert, A; Heinz, K
2002-03-18
We present a solution to the multiple-scattering inverse problem for low-energy electron diffraction that enables the determination of the three-dimensional atomic structure of an entire surface unit cell directly from measured data. The solution requires a knowledge of the structure of the underlying bulk crystal and is implemented by a maximum entropy algorithm.
NASA Technical Reports Server (NTRS)
Luchini, Chris B.
1997-01-01
Development of camera and instrument simulations for space exploration requires the development of scientifically accurate models of the objects to be studied. Several planned cometary missions have prompted the development of a three dimensional, multi-spectral, anisotropic multiple scattering model of cometary coma.
Amidani, L.; Pasquini, L.; Boscherini, F.
2012-08-15
We describe a soft x-ray appearance potential spectroscopy apparatus, which uses a windowless hyperpure Ge detector operated in the photon counting mode. Direct comparisons of recorded spectra with the self-convolution of x-ray absorption spectra and with ab initio simulations in the multiple scattering framework are reported and discussed.
Analysis of Spent Nuclear Fuel Imaging Using Multiple Coulomb Scattering of Cosmic Muons
NASA Astrophysics Data System (ADS)
Chatzidakis, Stylianos; Choi, Chan K.; Tsoukalas, Lefteri H.
2016-12-01
Cosmic ray muons passing through matter lose energy from inelastic collisions with electrons and are deflected from nuclei due to multiple Coulomb scattering. The strong dependence of scattering on atomic number Z and the recent developments on position sensitive muon detectors indicate that multiple Coulomb scattering could be an excellent candidate for spent nuclear fuel imaging. Muons present significant advantages over existing monitoring and imaging techniques and can play a central role in monitoring nuclear waste and spent nuclear fuel stored in dense well shielded containers. The main purpose of this paper is to investigate the applicability of multiple Coulomb scattering for imaging of spent nuclear fuel dry casks stored within vertical and horizontal commercial storage dry casks. Calculations of muon scattering were performed for various scenarios, including vertical and horizontal fully loaded dry casks, half loaded dry casks, dry casks with one row of fuel assemblies missing, dry casks with one fuel assembly missing and empty dry casks. Various detector sizes (1.2 m ×1.2 m, 2.4 m ×2.4 m and 3.6 m ×3.6 m) and number of muons (105, 5 · 105, 106 and 107) were used to assess the effect on image resolution. The Point-of-Closest-Approach (PoCA) algorithm was used for the reconstruction of the stored contents. The results demonstrate that multiple Coulomb scattering can be used to successfully reconstruct the dry cask contents and allow identification of all scenarios with the exception of one fuel assembly missing. In this case, an indication exists that a fuel assembly is not present; however, the resolution of the imaging algorithm was not enough to identify exact location.
Okamoto, Hajime; Sato, Kaori; Nishizawa, Tomoaki; Sugimoto, Nobuo; Makino, Toshiyuki; Jin, Yoshitaka; Shimizu, Atsushi; Takano, Toshiaki; Fujikawa, Masahiro
2016-12-26
We developed a multiple-field-of-view multiple-scattering polarization lidar (MFMSPL) to study the microphysics of optically thick clouds. Designed to measure enhanced backscattering and depolarization ratio comparable to space-borne lidar, the system consists of four sets of parallel and perpendicular channels mounted with different zenith angles. Depolarization ratios from water clouds were large as observed by MFMSPL compared to those observed by conventional lidar. Cloud top heights and depolarization ratios tended to be larger for outer MFMSPL channels than for vertically pointing channels. Co-located 95 GHz cloud radar and MFMSPL observations showed reasonable agreement at the observed cloud top height.
Choi, Wonjun; Jo, Yonghyeon; Ahn, Joonmo; Seo, Eunsung; Park, Q-Han; Jhon, Young Min; Choi, Wonshik
2017-01-01
Merging multiple microprocessors with high-speed optical networks has been considered a promising strategy for the improvement of overall computation power. However, the loss of the optical communication bandwidth is inevitable when interfacing between optical and electronic components. Here we present an on-chip plasmonic switching device consisting of a two-dimensional (2D) disordered array of nanoholes on a thin metal film that can provide multiple-input and multiple-output channels for transferring information from a photonic to an electronic platform. In this device, the surface plasmon polaritons (SPPs) generated at individual nanoholes become uncorrelated on their way to the detection channel due to random multiple scattering. We exploit this decorrelation effect to use individual nanoholes as independent antennas, and demonstrated that more than 40 far-field incident channels can be delivered simultaneously to the SPP channels, an order of magnitude improvement over conventional 2D patterned devices. PMID:28262721
Choi, Wonjun; Jo, Yonghyeon; Ahn, Joonmo; Seo, Eunsung; Park, Q-Han; Jhon, Young Min; Choi, Wonshik
2017-03-06
Merging multiple microprocessors with high-speed optical networks has been considered a promising strategy for the improvement of overall computation power. However, the loss of the optical communication bandwidth is inevitable when interfacing between optical and electronic components. Here we present an on-chip plasmonic switching device consisting of a two-dimensional (2D) disordered array of nanoholes on a thin metal film that can provide multiple-input and multiple-output channels for transferring information from a photonic to an electronic platform. In this device, the surface plasmon polaritons (SPPs) generated at individual nanoholes become uncorrelated on their way to the detection channel due to random multiple scattering. We exploit this decorrelation effect to use individual nanoholes as independent antennas, and demonstrated that more than 40 far-field incident channels can be delivered simultaneously to the SPP channels, an order of magnitude improvement over conventional 2D patterned devices.
NASA Astrophysics Data System (ADS)
Choi, Wonjun; Jo, Yonghyeon; Ahn, Joonmo; Seo, Eunsung; Park, Q.-Han; Jhon, Young Min; Choi, Wonshik
2017-03-01
Merging multiple microprocessors with high-speed optical networks has been considered a promising strategy for the improvement of overall computation power. However, the loss of the optical communication bandwidth is inevitable when interfacing between optical and electronic components. Here we present an on-chip plasmonic switching device consisting of a two-dimensional (2D) disordered array of nanoholes on a thin metal film that can provide multiple-input and multiple-output channels for transferring information from a photonic to an electronic platform. In this device, the surface plasmon polaritons (SPPs) generated at individual nanoholes become uncorrelated on their way to the detection channel due to random multiple scattering. We exploit this decorrelation effect to use individual nanoholes as independent antennas, and demonstrated that more than 40 far-field incident channels can be delivered simultaneously to the SPP channels, an order of magnitude improvement over conventional 2D patterned devices.
NASA Astrophysics Data System (ADS)
Fishkin, Joshua B.; So, Peter T. C.; Cerussi, Albert E.; Gratton, Enrico; Fantini, Sergio; Franceschini, Maria Angela
1995-03-01
We have measured the optical absorption and scattering coefficient spectra of a multiple-scattering medium (i.e., a biological tissue-simulating phantom comprising a lipid colloid) containing methemoglobin by using frequency-domain techniques. The methemoglobin absorption spectrum determined in the multiple-scattering medium is in excellent agreement with a corrected methemoglobin absorption spectrum obtained from a steady-state spectrophotometer measurement of the optical density of a minimally scattering medium. The determination of the corrected methemoglobin absorption spectrum takes into account the scattering from impurities in the methemoglobin solution containing no lipid colloid. Frequency-domain techniques allow for the separation of the absorbing from the scattering properties of multiple-scattering media, and these techniques thus provide an absolute
Multiple Scattering in Beam-line Detectors of the MUSE Experiment
NASA Astrophysics Data System (ADS)
Garland, Heather; Robinette, Clay; Strauch, Steffen; MUon Scattering Experiment (MUSE) Collaboration
2015-10-01
The charge radius of the proton has been obtained precisely from elastic electron-scattering data and spectroscopy of atomic hydrogen. However, a recent experiment using muonic hydrogen, designed for high-precision, presented a charge radius significantly smaller than the accepted value. This discrepancy certainly prompts a discussion of topics ranging from experimental methods to physics beyond the Standard Model. The MUon Scattering Experiment (MUSE) collaboration at the Paul Scherrer Institute, Switzerland, is planning an experiment to measure the charge radius of the proton in elastic scattering of electrons and muons of positive and negative charge off protons. In the layout for the proposed experiment, detectors will be placed in the beam line upstream of a hydrogen target. Using Geant4 simulations, we studied the effect of multiple scattering due to these detectors and determined the fraction of primary particles that hit the target for a muon beam at each beam momentum. Of the studied detectors, a quartz Cherenkov detector caused the largest multiple scattering. Our results will guide further optimization of the detector setup. Supported in parts by the U.S. National Science Foundation: NSF PHY-1205782.
NASA Technical Reports Server (NTRS)
Smith, James A.
1992-01-01
The inversion of the leaf area index (LAI) canopy parameter from optical spectral reflectance measurements is obtained using a backpropagation artificial neural network trained using input-output pairs generated by a multiple scattering reflectance model. The problem of LAI estimation over sparse canopies (LAI < 1.0) with varying soil reflectance backgrounds is particularly difficult. Standard multiple regression methods applied to canopies within a single homogeneous soil type yield good results but perform unacceptably when applied across soil boundaries, resulting in absolute percentage errors of >1000 percent for low LAI. Minimization methods applied to merit functions constructed from differences between measured reflectances and predicted reflectances using multiple-scattering models are unacceptably sensitive to a good initial guess for the desired parameter. In contrast, the neural network reported generally yields absolute percentage errors of <30 percent when weighting coefficients trained on one soil type were applied to predicted canopy reflectance at a different soil background.
NASA Astrophysics Data System (ADS)
Okamoto, Hajime; Sato, Kaori; Nishizawa, Tomoaki; Sugimoto, Nobuo; Jin, Yoshitaka
2017-02-01
We have examined the characteristic of backscattering coefficient and depolarization ratio that are affected by multiple scattering in optically thick water clouds. We used observations obtained by the Multiple Field of view Multiple Scattering Polarization Lidar (MFMSPL) system. The MFMSPL was the first ground-based lidar that can detect depolarization ratio of optically thick clouds and it has 8 channels, i.e., 4 for parallel channels and another 4 for perpendicular ones and achieved total FOV of 70mrad. The MFMSPL offers a unique opportunity to simulate and study space-borne lidar signals including depolarization ratio such as from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) lidar. It was shown that the attenuated backscattering coefficient and depolarization ratio constructed by using 8 channel observations by MFMSPL were comparable to the values obtained by CALIPSO lidar.
MULTIPLE SCATTERING OF WAVES BY A PAIR OF GRAVITATIONALLY STRATIFIED FLUX TUBES
Hanasoge, Shravan M.; Cally, Paul S.
2009-05-20
We study the near-field coupling of a pair of flux tubes embedded in a gravitationally stratified environment. The mutual induction of the near-field jackets of the two flux tubes can considerably alter the scattering properties of the system, resulting in sizable changes in the magnitudes of scattering coefficients and bizarre trends in the phases. The dominant length scale governing the induction zone turns out to be approximately half the horizontal wavelength of the incident mode, a result that fits in quite pleasantly with extant theories of scattering. Higher-{beta} flux tubes are more strongly coupled than weaker ones, a consequence of the greater role that the near-field jacket modes play in such tubes. We also comment on the importance of incorporating the effects of multiple scattering when studying the effects of mode absorption in plage and interpreting related scattering measurements. That the near field plays such an important role in the scattering process lends encouragement to the eventual goal of observationally resolving subwavelength features of flux tubes using techniques of helioseismology.
Scattering from phase-separated vesicles. I. An analytical form factor for multiple static domains
Heberle, Frederick A.; Anghel, Vinicius N. P.; Katsaras, John
2015-08-18
This is the first in a series of studies considering elastic scattering from laterally heterogeneous lipid vesicles containing multiple domains. Unique among biophysical tools, small-angle neutron scattering can in principle give detailed information about the size, shape and spatial arrangement of domains. A general theory for scattering from laterally heterogeneous vesicles is presented, and the analytical form factor for static domains with arbitrary spatial configuration is derived, including a simplification for uniformly sized round domains. The validity of the model, including series truncation effects, is assessed by comparison with simulated data obtained from a Monte Carlo method. Several aspects ofmore » the analytical solution for scattering intensity are discussed in the context of small-angle neutron scattering data, including the effect of varying domain size and number, as well as solvent contrast. Finally, the analysis indicates that effects of domain formation are most pronounced when the vesicle's average scattering length density matches that of the surrounding solvent.« less
Evaluation of a multiple scattering filter to enhance defect detection in heterogeneous media.
Shahjahan, Sharfine; Rupin, Fabienne; Aubry, Alexandre; Derode, Arnaud
2017-01-01
Ultrasonic evaluation of coarse-grain materials generates multiple scattering at high frequency and large depth. Recent academic experiments with array probes showed the ability of a random matrix method [multiple scattering filter (MSF)] to reduce multiple scattering, hence improving detection. Here, MSF is applied to an industrial nickel-based alloy with coarse-grain structure. Two samples with average grain sizes 90 ± 60 μm and 750 ± 400 μm are inspected with wide-band 64-element arrays at central frequencies 2, 3, and 5 MHz. They contain cylindrical through-holes (1-mm radius) at various depths. The array transfer matrix is recorded and post-processed both in the flawless area and for eleven positions above each defect, which allows for a statistical analysis. MSF is compared with two conventional imaging techniques: the total focusing method (TFM) and the decomposition of the time-reversal operator (DORT). Several parameters to assess the performance of detection techniques are proposed and discussed. The results show the benefit of MSF, especially at high frequencies and for deep defects: at 5 MHz and 70 mm depth, i.e., more than three scattering mean-free paths, the detection rate for MSF ranges between 55% and 100% while it is found to be 0% both for TFM and DORT.
USDA-ARS?s Scientific Manuscript database
The energy transport in a vegetated (corn) surface layer is examined by solving the vector radiative transfer equation using a numerical iterative approach. This approach allows a higher order that includes the multiple scattering effects. Multiple scattering effects are important when the optical t...
NASA Astrophysics Data System (ADS)
Ghazali, A.; Serre, J.
1985-02-01
Using a multiple-scattering method, we estimate the relative importance of both scattering and concentration-fluctuation effects on the band tailing and on interband optical absorption spectra. In addition, we show that as the impurity concentration decreases, the band tail gradually splits off from the main band, forming an impurity band. Spectral-density analysis allows one to distinguish between quasi-atomic and extended states. It is found that even when no gap appears, a significant part of electrons in the tail has a quasi-atomic character. Compensation effects have also been analyzed. Finally, our results are discussed and compared with various experiments.
Accelerated x-ray scatter projection imaging using multiple continuously moving pencil beams
NASA Astrophysics Data System (ADS)
Dydula, Christopher; Belev, George; Johns, Paul C.
2017-03-01
Coherent x-ray scatter varies with angle and photon energy in a manner dependent on the chemical composition of the scattering material, even for amorphous materials. Therefore, images generated from scattered photons can have much higher contrast than conventional projection radiographs. We are developing a scatter projection imaging prototype at the BioMedical Imaging and Therapy (BMIT) facility of the Canadian Light Source (CLS) synchrotron in Saskatoon, Canada. The best images are obtained using step-and-shoot scanning with a single pencil beam and area detector to capture sequentially the scatter pattern for each primary beam location on the sample. Primary x-ray transmission is recorded simultaneously using photodiodes. The technological challenge is to acquire the scatter data in a reasonable time. Using multiple pencil beams producing partially-overlapping scatter patterns reduces acquisition time but increases complexity due to the need for a disentangling algorithm to extract the data. Continuous sample motion, rather than step-and-shoot, also reduces acquisition time at the expense of introducing motion blur. With a five-beam (33.2 keV, 3.5 mm2 beam area) continuous sample motion configuration, a rectangular array of 12 x 100 pixels with 1 mm sampling width has been acquired in 0.4 minutes (3000 pixels per minute). The acquisition speed is 38 times the speed for single beam step-and-shoot. A system model has been developed to calculate detected scatter patterns given the material composition of the object to be imaged. Our prototype development, image acquisition of a plastic phantom and modelling are described.
Lu, Yong-jun; Qu, Yan-ling; Feng, Zhi-qing; Song, Min
2007-01-01
Multiple scattering correction(MSC) algorithm can be used effectively to remove the effect of scattering due to the physical factors such as the density and humidity of sample granule, and as a result the ratio of signal to noise is improved greatly. Meantime correlation spectrum plays a important role in the choice of optimum wavelength set because it describes the linear correlationship between the absorbance and concentration of the sample's ingredient under analysis. However, the correlation spectrum obtained by unitary linear regression(ULR) at single wavelength channel can be easily affected by the scattering so as to cover up the characteristic linear information of the sample. In order to solve the problem in the present paper MSC was applied to obtain useful signal and suppress noise of correlation spectrum. Through the careful calibration experiment of ginseng sample this idea has proved to be correct, and satisfactory result was obtained.
Inverse problem for multiple scattering of fast charged particles in a mesoscopic medium
Ramm, A.G. C-3 Division, Los Alamos National Laboratory, Los Alamos, New Mexcio 87545 ); Berman, G.P. Kirensky Institute of Physics, Research Educational Center for Nonlinear Processes, The Krasnoyarsk Technical University, 660036 Krasnoyarsk Theoretical Department, The Krasnoyarsk State University, 660036 Krasnoyarsk )
1995-01-15
We consider an inverse problem of multiple scattering for fast charged particles propagating in an inhomogeneous medium. The scattering processes are described by the diffusion-type equation in the small-angle approximation. It is shown that by using the scattering data given on some small interval, it is possible to recover the spatial dependence of the density of the medium. This inverse problem is ill posed in the sense that small noise in the data may lead to large perturbations in [epsilon]([ital z]) if no [ital a] priori assumptions are made about [epsilon]([ital z]). This is clear from our presentation, since an analytic continuation of [epsilon]([ital z]) is involved. One hopes that the proposed method can be applied to thin foils and to mesoscopic systems.
Momentum-space treatment of Coulomb distortions in a multiple-scattering expansion
NASA Astrophysics Data System (ADS)
Chinn, C. R.; Elster, Ch.; Thaler, R. M.
1991-10-01
The momentum-space treatment of the Coulomb interaction within the framework of the Watson multiple-scattering expansion is derived and tested numerically. By neglecting virtual Coulomb excitations and higher-order terms, the lowest-order optical potential for proton-nucleus scattering is shown to be the sum of the convolutions of a two-body nucleon-nucleon t matrix with the nuclear density and the point Coulomb interaction with the nuclear charge density. The calculation of the optical potential, as well as the treatment of the Coulomb interaction, is performed entirely in momentum space in an exact and numerically stable procedure. Elastic-scattering observables are presented for 16O, 40Ca, and 208Pb at energies up to 500 MeV. Comparisons are made with approximate treatments of the Coulomb interaction. The interference of nonlocality effects in the nuclear optical potential with different treatments of the Coulomb interaction is investigated.
NASA Astrophysics Data System (ADS)
Li, Meng; Jiang, Li-Hui; Xiong, Xing-Long; Ma, Yu-Zhao; Liu, Jie-Sheng
2016-08-01
Layer boundaries detection with LIDAR is of great significance for the meteorological and environmental research. Apart from the background noise, multiple scattering can also seriously affect the detection results in LIDAR signal processing. To alleviate these issues, a novel approach was proposed based upon morphological filtering and multiple scattering correction with multiple iterations, which essentially acts as a weighted algorithm with multiple scattering factors in different filtering scales, and applies integral extinction coefficients as media to perform correction. Simulations on artificial signals and real LIDAR signals support this approach.
Magnetotransport of multiple-band nearly antiferromagnetic metals due to hot-spot scattering
Koshelev, A. E.
2016-09-30
Multiple-band electronic structure and proximity to antiferromagnetic (AF) instability are the key properties of iron-based superconductors. In this paper, we explore the influence of scattering by the AF spin fluctuations on transport of multiple-band metals above the magnetic transition. A salient feature of scattering on the AF fluctuations is that it is strongly enhanced at the Fermi surface locations where the nesting is perfect (“hot spots” or “hot lines”). We review derivation of the collision integral for the Boltzmann equation due to AF-fluctuations scattering. In the paramagnetic state, the enhanced scattering rate near the hot lines leads to anomalous behaviormore » of electronic transport in magnetic field. We explore this behavior by analytically solving the Boltzmann transport equation with approximate transition rates. This approach accounts for return scattering events and is more accurate than the relaxation-time approximation. The magnetic-field dependences are characterized by two very different field scales: the lower scale is set by the hot-spot width and the higher scale is set by the total scattering amplitude. A conventional magnetotransport behavior is limited to magnetic fields below the lower scale. In the wide range in-between these two scales, the longitudinal conductivity has linear dependence on the magnetic field and the Hall conductivity has quadratic dependence. The linear dependence of the diagonal component reflects growth of the Fermi-surface area affected by the hot spots proportional to the magnetic field. Finally, we discuss applicability of this theoretical framework for describing of anomalous magnetotransport properties in different iron pnictides and chalcogenides in the paramagnetic state.« less
Magnetotransport of multiple-band nearly antiferromagnetic metals due to hot-spot scattering
Koshelev, A. E.
2016-09-30
Multiple-band electronic structure and proximity to antiferromagnetic (AF) instability are the key properties of iron-based superconductors. In this paper, we explore the influence of scattering by the AF spin fluctuations on transport of multiple-band metals above the magnetic transition. A salient feature of scattering on the AF fluctuations is that it is strongly enhanced at the Fermi surface locations where the nesting is perfect (“hot spots” or “hot lines”). We review derivation of the collision integral for the Boltzmann equation due to AF-fluctuations scattering. In the paramagnetic state, the enhanced scattering rate near the hot lines leads to anomalous behavior of electronic transport in magnetic field. We explore this behavior by analytically solving the Boltzmann transport equation with approximate transition rates. This approach accounts for return scattering events and is more accurate than the relaxation-time approximation. The magnetic-field dependences are characterized by two very different field scales: the lower scale is set by the hot-spot width and the higher scale is set by the total scattering amplitude. A conventional magnetotransport behavior is limited to magnetic fields below the lower scale. In the wide range in-between these two scales, the longitudinal conductivity has linear dependence on the magnetic field and the Hall conductivity has quadratic dependence. The linear dependence of the diagonal component reflects growth of the Fermi-surface area affected by the hot spots proportional to the magnetic field. Finally, we discuss applicability of this theoretical framework for describing of anomalous magnetotransport properties in different iron pnictides and chalcogenides in the paramagnetic state.
Magnetotransport of multiple-band nearly antiferromagnetic metals due to hot-spot scattering
NASA Astrophysics Data System (ADS)
Koshelev, A. E.
2016-09-01
Multiple-band electronic structure and proximity to antiferromagnetic (AF) instability are the key properties of iron-based superconductors. We explore the influence of scattering by the AF spin fluctuations on transport of multiple-band metals above the magnetic transition. A salient feature of scattering on the AF fluctuations is that it is strongly enhanced at the Fermi surface locations where the nesting is perfect ("hot spots" or "hot lines"). We review derivation of the collision integral for the Boltzmann equation due to AF-fluctuations scattering. In the paramagnetic state, the enhanced scattering rate near the hot lines leads to anomalous behavior of electronic transport in magnetic field. We explore this behavior by analytically solving the Boltzmann transport equation with approximate transition rates. This approach accounts for return scattering events and is more accurate than the relaxation-time approximation. The magnetic-field dependences are characterized by two very different field scales: the lower scale is set by the hot-spot width and the higher scale is set by the total scattering amplitude. A conventional magnetotransport behavior is limited to magnetic fields below the lower scale. In the wide range in-between these two scales, the longitudinal conductivity has linear dependence on the magnetic field and the Hall conductivity has quadratic dependence. The linear dependence of the diagonal component reflects growth of the Fermi-surface area affected by the hot spots proportional to the magnetic field. We discuss applicability of this theoretical framework for describing of anomalous magnetotransport properties in different iron pnictides and chalcogenides in the paramagnetic state.
A multiple maximum scatter difference discriminant criterion for facial feature extraction.
Song, Fengxi; Zhang, David; Mei, Dayong; Guo, Zhongwei
2007-12-01
Maximum scatter difference (MSD) discriminant criterion was a recently presented binary discriminant criterion for pattern classification that utilizes the generalized scatter difference rather than the generalized Rayleigh quotient as a class separability measure, thereby avoiding the singularity problem when addressing small-sample-size problems. MSD classifiers based on this criterion have been quite effective on face-recognition tasks, but as they are binary classifiers, they are not as efficient on large-scale classification tasks. To address the problem, this paper generalizes the classification-oriented binary criterion to its multiple counterpart--multiple MSD (MMSD) discriminant criterion for facial feature extraction. The MMSD feature-extraction method, which is based on this novel discriminant criterion, is a new subspace-based feature-extraction method. Unlike most other subspace-based feature-extraction methods, the MMSD computes its discriminant vectors from both the range of the between-class scatter matrix and the null space of the within-class scatter matrix. The MMSD is theoretically elegant and easy to calculate. Extensive experimental studies conducted on the benchmark database, FERET, show that the MMSD out-performs state-of-the-art facial feature-extraction methods such as null space method, direct linear discriminant analysis (LDA), eigenface, Fisherface, and complete LDA.
Multiple-mode Lamb wave scattering simulations using 3D elastodynamic finite integration technique.
Leckey, Cara A C; Rogge, Matthew D; Miller, Corey A; Hinders, Mark K
2012-02-01
We have implemented three-dimensional (3D) elastodynamic finite integration technique (EFIT) simulations to model Lamb wave scattering for two flaw-types in an aircraft-grade aluminum plate, a rounded rectangle flat-bottom hole and a disbond of the same shape. The plate thickness and flaws explored in this work include frequency-thickness regions where several Lamb wave modes exist and sometimes overlap in phase and/or group velocity. For the case of the flat-bottom hole the depth was incrementally increased to explore progressive changes in multiple-mode Lamb wave scattering due to the damage. The flat-bottom hole simulation results have been compared to experimental data and are shown to provide key insight for this well-defined experimental case by explaining unexpected results in experimental waveforms. For the rounded rectangle disbond flaw, which would be difficult to implement experimentally, we found that Lamb wave behavior differed significantly from the flat-bottom hole flaw. Most of the literature in this field is restricted to low frequency-thickness regions due to difficulties in interpreting data when multiple modes exist. We found that benchmarked 3D EFIT simulations can yield an understanding of scattering behavior for these higher frequency-thickness regions and in cases that would be difficult to set up experimentally. Additionally, our results show that 2D simulations would not have been sufficient for modeling the complicated scattering that occurred. Published by Elsevier B.V.
Direct Simulation of Multiple Scattering by Discrete Random Media Illuminated by Gaussian Beams
NASA Technical Reports Server (NTRS)
Mackowski, Daniel W.; Mishchenko, Michael I.
2011-01-01
The conventional orientation-averaging procedure developed in the framework of the superposition T-matrix approach is generalized to include the case of illumination by a Gaussian beam (GB). The resulting computer code is parallelized and used to perform extensive numerically exact calculations of electromagnetic scattering by volumes of discrete random medium consisting of monodisperse spherical particles. The size parameters of the scattering volumes are 40, 50, and 60, while their packing density is fixed at 5%. We demonstrate that all scattering patterns observed in the far-field zone of a random multisphere target and their evolution with decreasing width of the incident GB can be interpreted in terms of idealized theoretical concepts such as forward-scattering interference, coherent backscattering (CB), and diffuse multiple scattering. It is shown that the increasing violation of electromagnetic reciprocity with decreasing GB width suppresses and eventually eradicates all observable manifestations of CB. This result supplements the previous demonstration of the effects of broken reciprocity in the case of magneto-optically active particles subjected to an external magnetic field.
Multiple scattering model for the penetration depth of low-coherence enhanced backscattering.
Turzhitsky, Vladimir; Mutyal, Nikhil N; Radosevich, Andrew J; Backman, Vadim
2011-09-01
Low-coherence enhanced backscattering (LEBS) is a depth-selective self-interference phenomenon that originates from light traveling time-reversed paths in a scattering medium. The depth selectivity of LEBS and its sensitivity to optical properties of the scattering medium has made it a promising technique for probing the structure of biological tissue with applications to disease diagnosis and, in particular, precancerous conditions. The ability to accurately predict the penetration depth of the LEBS signal is important in targeting an optimal tissue depth for detecting precancerous cells. This prediction is further complicated by the variation in optical properties of different tissue types. In this paper, the effects of the reduced scattering coefficient (μ(s)'), the phase function and the instrument spatial coherence length (L(sc)) on the LEBS penetration depth are quantified. It is determined that the LEBS penetration depth is primarily dependent on L(sc), μ(s)', and the anisotropy factor (g), but has minimal dependence on higher moments of the phase function. An empirical expression, having a similar form as the double scattering approximation for LEBS, is found to accurately predict the average penetration depth in the multiple scattering regime. The expression is shown to be accurate for a broad range of experimentally relevant optical properties and spatial coherence lengths.
Direct simulation of multiple scattering by discrete random media illuminated by Gaussian beams
Mackowski, Daniel W.; Mishchenko, Michael I.
2011-01-15
The conventional orientation-averaging procedure developed in the framework of the superposition T-matrix approach is generalized to include the case of illumination by a Gaussian beam (GB). The resulting computer code is parallelized and used to perform extensive numerically exact calculations of electromagnetic scattering by volumes of discrete random medium consisting of monodisperse spherical particles. The size parameters of the scattering volumes are 40, 50, and 60, while their packing density is fixed at 5%. We demonstrate that all scattering patterns observed in the far-field zone of a random multisphere target and their evolution with decreasing width of the incident GB can be interpreted in terms of idealized theoretical concepts such as forward-scattering interference, coherent backscattering (CB), and diffuse multiple scattering. It is shown that the increasing violation of electromagnetic reciprocity with decreasing GB width suppresses and eventually eradicates all observable manifestations of CB. This result supplements the previous demonstration of the effects of broken reciprocity in the case of magneto-optically active particles subjected to an external magnetic field.
Direct Simulation of Multiple Scattering by Discrete Random Media Illuminated by Gaussian Beams
NASA Technical Reports Server (NTRS)
Mackowski, Daniel W.; Mishchenko, Michael I.
2011-01-01
The conventional orientation-averaging procedure developed in the framework of the superposition T-matrix approach is generalized to include the case of illumination by a Gaussian beam (GB). The resulting computer code is parallelized and used to perform extensive numerically exact calculations of electromagnetic scattering by volumes of discrete random medium consisting of monodisperse spherical particles. The size parameters of the scattering volumes are 40, 50, and 60, while their packing density is fixed at 5%. We demonstrate that all scattering patterns observed in the far-field zone of a random multisphere target and their evolution with decreasing width of the incident GB can be interpreted in terms of idealized theoretical concepts such as forward-scattering interference, coherent backscattering (CB), and diffuse multiple scattering. It is shown that the increasing violation of electromagnetic reciprocity with decreasing GB width suppresses and eventually eradicates all observable manifestations of CB. This result supplements the previous demonstration of the effects of broken reciprocity in the case of magneto-optically active particles subjected to an external magnetic field.
Multiple-scattering approach to the x-ray-absorption spectra of 3d transition metals
NASA Astrophysics Data System (ADS)
Kitamura, Michihide; Muramatsu, Shinji; Sugiura, Chikara
1986-04-01
The x-ray-absorption near-edge structure (XANES) has been calculated for the 3d transition metals Cr, Fe, Ni, and Cu from a multiple-scattering approach within the muffin-tin-potential approximation, as a first step to studying the XANES for complicated materials. The muffin-tin potential is constructed via the Mattheiss prescription using the atomic data of Herman and Skillman. It is found that the XANES is sensitive to the potential used and that the calculated XANES spectra reproduce the number of peaks and their separations observed experimentally. The final spectra, including the lifetime-broadening effect, show the general features of each material. We emphasize that the multiple-scattering theory which can be applied to the disordered systems as well as the ordered ones may be promising as a tool to analyze the XANES of complicated materials.
NASA Technical Reports Server (NTRS)
Ben-David, Avishai
1992-01-01
Knowing the optical properties of aerosol dust is important for designing electro-optical systems and for modeling the effect on propagation of light in the atmosphere. As CO2 lidar technology becomes more advanced and is used for multiwavelength measurements, information on the wavelength dependent backscattering of aerosol dust particles is required. The volume backscattering coefficient of aerosols in the IR is relatively small. Thus, only a few field measurements of backscattering, usually at only a few wavelengths, are reported in the literature. We present spectral field measurements of backscattering of kaolin dust in the 9-11 micron wavelength range. As the quantity of dust increases, multiple scattering contributes more to the measured backscattered signal. The measurements show the effect of the dust quantity of the spectral backscatter measurements. A simple analytical two stream radiative transfer model is applied to confirm the measurements and to give insight to the multiple scattering spectra of backscattering.
Lu, Yong-jun; Qu, Yan-ling; Song, Min
2007-05-01
Correlation spectroscopy can be used to describe the linear correlationship between the absorbance and concentration data in the whole spectra range and clearly figure out the characteristic peak position of the sample under test. Meantime, this chart plays an extremely important role in offering the precise information for choosing the optimal wavelength set during the calibration process. Multiple scatter correct (MSC) spectroscopy is a kind of multiple variable scatter correction technique, and can effectively remove the base shift and tilt phenomenon caused by MSC. As a result, the ratio of signal to noise is improved greatly. Based on this feature, the new idea of the MSC technique was introduced into the preceding data treatment for the creation of correlation chart, and through careful experiment this idea was proved to be correct and effective.
NASA Technical Reports Server (NTRS)
Ben-David, Avishai
1992-01-01
Knowing the optical properties of aerosol dust is important for designing electro-optical systems and for modeling the effect on propagation of light in the atmosphere. As CO2 lidar technology becomes more advanced and is used for multiwavelength measurements, information on the wavelength dependent backscattering of aerosol dust particles is required. The volume backscattering coefficient of aerosols in the IR is relatively small. Thus, only a few field measurements of backscattering, usually at only a few wavelengths, are reported in the literature. We present spectral field measurements of backscattering of kaolin dust in the 9-11 micron wavelength range. As the quantity of dust increases, multiple scattering contributes more to the measured backscattered signal. The measurements show the effect of the dust quantity of the spectral backscatter measurements. A simple analytical two stream radiative transfer model is applied to confirm the measurements and to give insight to the multiple scattering spectra of backscattering.
Coupling of Multiple Coulomb Scattering with Energy Loss and Straggling in HZETRN
NASA Technical Reports Server (NTRS)
Mertens, Christopher J.; Wilson, John W.; Walker, Steven A.; Tweed, John
2007-01-01
The new version of the HZETRN deterministic transport code based on Green's function methods, and the incorporation of ground-based laboratory boundary conditions, has lead to the development of analytical and numerical procedures to include off-axis dispersion of primary ion beams due to small-angle multiple Coulomb scattering. In this paper we present the theoretical formulation and computational procedures to compute ion beam broadening and a methodology towards achieving a self-consistent approach to coupling multiple scattering interactions with ionization energy loss and straggling. Our initial benchmark case is a 60 MeV proton beam on muscle tissue, for which we can compare various attributes of beam broadening with Monte Carlo simulations reported in the open literature.
NASA Technical Reports Server (NTRS)
Shettle, E. P.; Green, A. E. S.
1974-01-01
An investigation is conducted regarding the increase in the UV radiation as a function of wavelength due to changes in the amounts of ozone and various other parameters affecting the radiation in the atmosphere. Attention is given to the methods that can be used to solve the problem of the transfer of radiation through an absorbing and scattering atmosphere which includes aerosols. The multiple channel solution reported by Mudgett and Richards' (1971) is extended to vertically inhomogeneous atmospheres.
Multiple-scattering corrections in diluted magnetic semiconductors: A plane-wave expansion
NASA Astrophysics Data System (ADS)
Scalbert, D.; Ghazali, A.; Benoit à la Guillaume, C.
1993-12-01
Energy levels of band edges in diluted magnetic semiconductors are calculated in the effective-mass approximation, retaining off-diagonal terms in the exchange interaction and using a plane-wave expansion. This model accounts qualitatively for the observed asymmetry in the splitting of the A exciton in a magnetic field in Cd1-xMnxS for which multiple-scattering corrections are expected to be important.
Atmospheric neutrino oscillations from upward throughgoing muon multiple scattering in MACRO
NASA Astrophysics Data System (ADS)
MACRO Collaboration; Ambrosio, M.; Antolini, R.; Bakari, D.; Baldini, A.; Barbarino, G. C.; Barish, B. C.; Battistoni, G.; Becherini, Y.; Bellotti, R.; Bemporad, C.; Bernardini, P.; Bilokon, H.; Bloise, C.; Bower, C.; Brigida, M.; Bussino, S.; Cafagna, F.; Calicchio, M.; Campana, D.; Carboni, M.; Caruso, R.; Cecchini, S.; Cei, F.; Chiarella, V.; Chiarusi, T.; Choudhary, B. C.; Coutu, S.; Cozzi, M.; de Cataldo, G.; Dekhissi, H.; de Marzo, C.; de Mitri, I.; Derkaoui, J.; de Vincenzi, M.; di Credico, A.; Favuzzi, C.; Forti, C.; Fusco, P.; Giacomelli, G.; Giannini, G.; Giglietto, N.; Giorgini, M.; Grassi, M.; Grillo, A.; Gustavino, C.; Habig, A.; Hanson, K.; Heinz, R.; Iarocci, E.; Katsavounidis, E.; Katsavounidis, I.; Kearns, E.; Kim, H.; Kumar, A.; Kyriazopoulou, S.; Lamanna, E.; Lane, C.; Levin, D. S.; Lipari, P.; Longo, M. J.; Loparco, F.; Maaroufi, F.; Mancarella, G.; Mandrioli, G.; Manzoor, S.; Margiotta, A.; Marini, A.; Martello, D.; Marzari-Chiesa, A.; Mazziotta, M. N.; Michael, D. G.; Mikheyev, S.; Monacelli, P.; Montaruli, T.; Monteno, M.; Mufson, S.; Musser, J.; Nicolò, D.; Nolty, R.; Orth, C.; Osteria, G.; Palamara, O.; Patera, V.; Patrizii, L.; Pazzi, R.; Peck, C. W.; Perrone, L.; Petrera, S.; Popa, V.; Rainò, A.; Reynoldson, J.; Ronga, F.; Rrhioua, A.; Satriano, C.; Scapparone, E.; Scholberg, K.; Sciubba, A.; Serra, P.; Sioli, M.; Sirri, G.; Sitta, M.; Spinelli, P.; Spinetti, M.; Spurio, M.; Steinberg, R.; Stone, J. L.; Sulak, L. R.; Surdo, A.; Tarlè, G.; Togo, V.; Vakili, M.; Walter, C. W.; Webb, R.
2003-07-01
The energy of atmospheric neutrinos detected by MACRO was estimated using multiple Coulomb scattering of upward throughgoing muons. This analysis allows a test of atmospheric neutrino oscillations, relying on the distortion of the muon energy distribution. These results have been combined with those coming from the upward throughgoing muon angular distribution only. Both analyses are independent of the neutrino flux normalization and provide strong evidence, above the /4σ level, in favour of neutrino oscillations.
MsSpec-1.0: A multiple scattering package for electron spectroscopies in material science
NASA Astrophysics Data System (ADS)
Sébilleau, Didier; Natoli, Calogero; Gavaza, George M.; Zhao, Haifeng; Da Pieve, Fabiana; Hatada, Keisuke
2011-12-01
We present a multiple scattering package to calculate the cross-section of various spectroscopies namely photoelectron diffraction (PED), Auger electron diffraction (AED), X-ray absorption (XAS), low-energy electron diffraction (LEED) and Auger photoelectron coincidence spectroscopy (APECS). This package is composed of three main codes, computing respectively the cluster, the potential and the cross-section. In the latter case, in order to cover a range of energies as wide as possible, three different algorithms are provided to perform the multiple scattering calculation: full matrix inversion, series expansion or correlation expansion of the multiple scattering matrix. Numerous other small Fortran codes or bash/csh shell scripts are also provided to perform specific tasks. The cross-section code is built by the user from a library of subroutines using a makefile. Program summaryProgram title: MsSpec-1.0 Catalogue identifier: AEJT_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEJT_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 504 438 No. of bytes in distributed program, including test data, etc.: 14 448 180 Distribution format: tar.gz Programming language: Fortran 77 Computer: Any Operating system: Linux, MacOs RAM: Bytes Classification: 7.2 External routines: Lapack ( http://www.netlib.org/lapack/) Nature of problem: Calculation of the cross-section of various spectroscopies. Solution method: Multiple scattering. Running time: The test runs provided only take a few seconds to run.
Multiple scattering of light in a spherical cometary atmosphere with an axisymmetric dust jet
NASA Technical Reports Server (NTRS)
Chick, Kenneth M.; Gombosi, Tamas I.
1992-01-01
A numerical solution has been developed for the anisotropic multiple scattering of light in a spherical shell comet atmosphere. The code has been run for a spherically symmetric coma distribution, benchmarked against past studies, and then run for the conditions of an axisymmetric dust jet at the subsolar point of the comet. The radiant flux impinging on the nucleus surface and the mean intensity of light throughout the coma were investigated.
Doc, Jean-Baptiste; Conoir, Jean-Marc; Marchiano, Régis; Fuster, Daniel
2016-04-01
The weakly nonlinear propagation of acoustic waves in monodisperse bubbly liquids is investigated numerically. A hydrodynamic model based on the averaged two-phase fluid equations is coupled with the Rayleigh-Plesset equation to model the dynamics of bubbles at the local scale. The present model is validated in the linear regime by comparing with the Foldy approximation. The analysis of the pressure signals in the linear regime highlights two resonance frequencies: the Minnaert frequency and a multiple scattering resonance that strongly depends on the bubble concentration. For weakly nonlinear regimes, the generation of higher harmonics is observed only for the Minnaert frequency. Linear combinations between the Minnaert harmonics and the multiple scattering resonance are also observed. However, the most significant effect observed is the appearance of softening-hardening effects that share some similarities with those observed for sandstones or cracked materials. These effects are related to the multiple scattering resonance. Downward or upward resonance frequency shifts can be observed depending on the characteristic of the incident wave when increasing the excitation amplitude. It is shown that the frequency shift can be explained assuming that the acoustic wave velocity depends on a law different from those usually encountered for sandstones or cracked materials.
Dual wavelength multiple-angle light scattering system for cryptosporidium detection
NASA Astrophysics Data System (ADS)
Buaprathoom, S.; Pedley, S.; Sweeney, S. J.
2012-06-01
A simple, dual wavelength, multiple-angle, light scattering system has been developed for detecting cryptosporidium suspended in water. Cryptosporidium is a coccidial protozoan parasite causing cryptosporidiosis; a diarrheal disease of varying severity. The parasite is transmitted by ingestion of contaminated water, particularly drinking-water, but also accidental ingestion of bathing-water, including swimming pools. It is therefore important to be able to detect these parasites quickly, so that remedial action can be taken to reduce the risk of infection. The proposed system combines multiple-angle scattering detection of a single and two wavelengths, to collect relative wavelength angle-resolved scattering phase functions from tested suspension, and multivariate data analysis techniques to obtain characterizing information of samples under investigation. The system was designed to be simple, portable and inexpensive. It employs two diode lasers (violet InGaN-based and red AlGaInP-based) as light sources and silicon photodiodes as detectors and optical components, all of which are readily available. The measured scattering patterns using the dual wavelength system showed that the relative wavelength angle-resolved scattering pattern of cryptosporidium oocysts was significantly different from other particles (e.g. polystyrene latex sphere, E.coli). The single wavelength set up was applied for cryptosporidium oocysts'size and relative refractive index measurement and differential measurement of the concentration of cryptosporidium oocysts suspended in water and mixed polystyrene latex sphere suspension. The measurement results showed good agreement with the control reference values. These results indicate that the proposed method could potentially be applied to online detection in a water quality control system.
NASA Astrophysics Data System (ADS)
Patterson, M.; Hughes, S.; Schulz, S.; Beggs, D. M.; White, T. P.; O'Faolain, L.; Krauss, T. F.
2009-11-01
Through a combined theoretical and experimental study of disorder-induced incoherent scattering losses in slow-light photonic crystal slab waveguides, we show the importance of Bloch mode reshaping and multiple scattering. We describe a convenient and fully three-dimensional theoretical treatment of disorder-induced extrinsic scattering, including the calculation of backscatter and out-of-plane losses per unit cell, and the extrapolation of the unit-cell loss to the loss for an entire disordered waveguide. The theoretical predictions, which are also compared with recent measurements on dispersion engineered silicon waveguides, demonstrate the failure of the Beer-Lambert law due to multiple scattering. We also explain why the previously assumed group velocity scalings of disorder-induced loss break down in general.
The multiple scattering and N-body approaches to nuclear reactions
NASA Astrophysics Data System (ADS)
Picklesimer, A.; Tandy, P. C.; Thaler, R. M.
1983-02-01
The relationship between conventional multiple scattering approaches and the recently developed N-body approaches to nuclear reactions is considered with a view towards elastic scattering applications. Connectivity expansions in the N-body approach and multiple scattering expansions in the Watson approach are developed by a common technique so that a comparison of the physical content of each can be made. In the N-body case this leads to a new derivation of the equations of Bencze, Redish, and Sloan in both particle-labelled and partition-labelled form and this yields new insight into the minimal dimensionality of these equations and into the role of channel coupling schemes within this formulation. The relative simplicity and generality with which these results are obtained is designed to be easily understood by those unfamiliar with N-body formalisms. The two approaches are contrasted first for the three-particle problem and subsequently for the many-body problem. We argue that a strict adherence to the connected-kernel property which is advantageous for the three-particle problem may not be so advantageous for the many-body elastic scattering problem. Undesirable physical characteristics of the connectivity expansion for elastic scattering are identified and their rectification is discussed. The off-shell transformation associated with the N-body approach is examined critically. The origin of the multiplicity of N-body coupling schemes is elucidated. It is shown that a modified concept of connectivity, called inclusive connectivity, can be introduced to guide expansions which can be truncated in a physically meaningful way. The inclusive connectivity expansion is seen to be identical to the spectator expansion for an elementary projectile but differs in the case of a composite projectile. Extant elastic scattering optical potential formulations based on the two concepts of connectivity are compared and contrasted. We show that connected kernel integral equations
NASA Astrophysics Data System (ADS)
Margerin, Ludovic; Calvet, Marie
2013-04-01
The attenuation properties of the crust have been widely explored from measurements of the quality factor of coda waves (Qc) throughout the world. A number of studies have reported an increase of Qc with the lapse time in the coda of shear waves excited by local earthquakes. Based on a single-scattering interpretation, this observation is generally ascribed to depth-dependent attenuation properties in the crust. In recent years a number of observations -in particular seismic wave equipartition- have put forward the importance of multiple scattering in the coda. The main purpose of this study is therefore to clarify the role of multiple scattering in the lapse time dependence of Qc using numerical simulations and observations from the Pyrenees. Thanks to the European project Interreg SISPYR, we collected all available waveform data from various institutions that operate seismological networks along the range. We selected around 5000 waveforms from 159 local earthquakes (with a magnitude larger than 3) which occured between 2001 and 2010. The coda quality factor of short-period S-waves has been measured as a function of the length of the coda window (Lw) for different choices of the onset time of the coda. In the 2-16 Hz frequency band, we observe a transient regime characterized by an increase of Qc with Lw, followed by a stabilization around a plateau whose value depends on the central frequency of the signal and on the location along the range. Using Monte Carlo simulations of wave transport in a variety of random media (exponential, Von-Karman or gaussian heterogeneity power spectra), we demonstrate that the lapse-time dependence of Qc in the Pyrenees may be modeled by anisotropic multiple scattering of seismic waves, without invoking any depth dependence of the attenuation properties in the crust. In our model, anisotropic scattering is quantified by the ratio between the transport and scattering mean path (l*-l). At 6 Hz, we show that pyrenean data require an
NASA Astrophysics Data System (ADS)
Calvet, M.; Margerin, L.
2012-12-01
The attenuation properties of the crust have been widely explored from measurements of the quality factor of coda waves (Qc) throughout the world. A number of studies have reported an increase of Qc with the lapse time in the coda of shear waves excited by local earthquakes. Based on a single scattering interpretation, this observation is generally ascribed to depth-dependent attenuation properties in the crust. In recent years a number of observations -in particular seismic wave equipartition- have put forward the importance of multiple scattering in the coda. The main purpose of this study is therefore to clarify the role of multiple scattering in the lapse time dependence of Qc using numerical simulations and observations from the Pyrenees. Thanks to the European project Interreg SISPYR, we collected all available waveform data from various institutions that operate seismological networks along the range. We selected around 5000 waveforms from 159 local earthquakes (with a magnitude larger than 3) which occured between 2001 and 2010. The coda quality factor of short-period S-waves has been measured as a function of the length of the coda window (Lw) for different choices of the onset time of the coda. In the 2-16 Hz frequency band, we observe a transient regime characterized by an increase of Qc with Lw, followed by a stabilization around a plateau whose value depends on the central frequency of the signal and on the location along the range. Using Monte Carlo simulations of wave transport in a variety of random media (exponential, Von-Karman or gaussian heterogeneity power spectra), we demonstrate that the lapse-time dependence of Qc in the Pyrenees may be modeled by anisotropic multiple scattering of seismic waves, without invoking any depth dependence of the attenuation properties in the crust. In our model, anisotropic scattering is quantified by the ratio between the transport and scattering mean path (l*/l). At 6 Hz, we show that pyrenean data require an
A proposed study of multiple scattering through clouds up to 1 THz
NASA Technical Reports Server (NTRS)
Gerace, G. C.; Smith, E. K.
1992-01-01
A rigorous computation of the electromagnetic field scattered from an atmospheric liquid water cloud is proposed. The recent development of a fast recursive algorithm (Chew algorithm) for computing the fields scattered from numerous scatterers now makes a rigorous computation feasible. A method is presented for adapting this algorithm to a general case where there are an extremely large number of scatterers. It is also proposed to extend a new binary PAM channel coding technique (El-Khamy coding) to multiple levels with non-square pulse shapes. The Chew algorithm can be used to compute the transfer function of a cloud channel. Then the transfer function can be used to design an optimum El-Khamy code. In principle, these concepts can be applied directly to the realistic case of a time-varying cloud (adaptive channel coding and adaptive equalization). A brief review is included of some preliminary work on cloud dispersive effects on digital communication signals and on cloud liquid water spectra and correlations.
NASA Astrophysics Data System (ADS)
Ushakova, O. V.; Kuznetsova, L. V.; Zimnyakov, D. A.
2007-05-01
Diffuse reflectance of polarized light is studied in application to characterization of multiple scattering anisotropic media (such as, e.g., the fibrous tissues) with the use of focused probe laser beam. The theoretical model for description of the transport properties (the values of transport scattering coefficients and effective refractive index for different polarization states of probe light) of closely packed systems of partially disordered dielectric cylinders is considered on the base of coherent potential approximation. The influence of structural and optical characteristics of fibrous systems (such as the volume fraction of cylindrical scatters, their average diameter, the degree of disorder, refractive indices of scatters and surrounding medium) on diagnostical parameters determined with the polarization videoreflectometry can be analyzed in the framework of the considered theoretical model. The obtained theoretical results satisfactorily agree with the experimental data on polarization videoreflectometry and spectral-polarization measurements in the transmittance mode of in-vitro samples of demineralized bone, muscular tissue and phantom samples (partially oriented polymer films).
NASA Astrophysics Data System (ADS)
Zustiak, Silviya; Riley, Jason; Boukari, Hacène; Gandjbakhche, Amir; Nossal, Ralph
2012-12-01
Fluorescence correlation spectroscopy (FCS) is increasingly being used to assess the movement of particles diffusing in complex, optically dense surroundings, in which case measurement conditions may complicate data interpretation. It is considered how a single-photon FCS measurement can be affected if the sample properties result in scattering of the incident light. FCS autocorrelation functions of Atto 488 dye molecules diffusing in solutions of polystyrene beads are measured, which acted as scatterers. Data indicated that a scattering-linked increase in the illuminated volume, as much as two fold, resulted in minimal increase in diffusivity. To analyze the illuminated beam profile, Monte-Carlo simulations were employed, which indicated a larger broadening of the beam along the axial than the radial directions, and a reduction of the incident intensity at the focal point. The broadening of the volume in the axial direction has only negligible effect on the measured diffusion time, since intensity fluctuations due to diffusion events in the radial direction are dominant in FCS measurements. Collectively, results indicate that multiple scattering does not result in FCS measurement artifacts and thus, when sufficient signal intensity is attainable, single-photon FCS can be a useful technique for measuring probe diffusivity in optically dense media.
Multiple scattering effects on heavy meson production in p+A collisions at backward rapidity
Kang, Zhong-Bo; Vitev, Ivan; Wang, Enke; ...
2014-11-20
We study the incoherent multiple scattering effects on heavy meson production in the backward rapidity region of p+A collisions within the generalized high-twist factorization formalism. We calculate explicitly the double scattering contributions to the heavy meson differential cross sections by taking into account both initial-state and final-state interactions, and find that these corrections are positive. We further evaluate the nuclear modification factor for muons that come form the semi-leptonic decays of heavy flavor mesons. Phenomenological applications in d+Au collisions at a center-of-mass energy View the MathML sources=200 GeV at RHIC and in p+Pb collisions at View the MathML sources=5.02 TeVmore » at the LHC are presented. We find that incoherent multiple scattering can describe rather well the observed nuclear enhancement in the intermediate pTpT region for such reactions.« less
Characterisation of ultrasonic structural noise in multiple scattering media using phased arrays
NASA Astrophysics Data System (ADS)
Bedetti, T.; Dorval, V.; Jenson, F.; Derode, A.
2013-08-01
The ultrasonic inspection of multiple scattering media gives rise to structural noise which makes it difficult to detect potential damage or crack inside the component. In order to predict the performances of ultrasonic inspection over such complex media, scattering models can be used. Such models rely on specific key parameters describing the multiple scattering process, which can be determined by specific measurements and post-processing techniques. Such experiments were carried out on stainless steel plates using linear phased-arrays. They consist in recording the response matrix constituted by impulse responses between all the elements of the array. By conducting post-processing on this matrix, we measure the elastic mean free path le and the correlation distance dc of the recorded noise. Additionally, the dynamic behaviour of the coherent backscattering effect was studied in order to measure the diffusion constant D. Plane-wave beamforming has been applied to the response matrix to improve the angular resolution and the signal-to-noise ratio of the backscattered intensity. Details of postprocessing techniques will be shown.
Houamer, Salim; Popov, Yuri V.; Dal Cappello, Claude
2010-03-15
The first Born approximation is examined for different fast capture processes for the p+He system at incident energies of about 1 MeV. Calculations have been performed for the singly differential cross section (SDCS) for scattering angles 0-0.5 mrad in the laboratory frame. In the case of transfer ionization, we observe that the two-step-2 mechanism has a dominant contribution to the SDCS for the kinematics considered in this work. The present investigation demonstrates that the multiple peaking approximation is a very crude method which fails to describe the SDCS even at scattering angles below 0.5 mrad. We have also presented a doubly differential cross section for the fixed emission energy of 600 eV and compared our results with other theoretical calculations and experiments.
Investigating acoustic-induced deformations in a foam using multiple light scattering.
Erpelding, M; Guillermic, R M; Dollet, B; Saint-Jalmes, A; Crassous, J
2010-08-01
We have studied the effect of an external acoustic wave on bubble displacements inside an aqueous foam. The signature of the acoustic-induced bubble displacements is found using a multiple light scattering technique, and occurs as a modulation on the photon correlation curve. Measurements for various sound frequencies and amplitudes are compared to analytical predictions and numerical simulations. These comparisons finally allow us to elucidate the nontrivial acoustic displacement profile inside the foam; in particular, we find that the acoustic wave creates a localized shear in the vicinity of the solid walls holding the foam, as a consequence of inertial contributions. This study of how bubbles "dance" inside a foam as a response to sound turns out to provide new insights on foam acoustics and sound transmission into a foam, foam deformation at high frequencies, and analysis of light scattering data in samples undergoing nonhomogeneous deformations.
Model of laser/composite interaction based on scattering by multiple cylinders
NASA Astrophysics Data System (ADS)
Dedieu, Cyril; Chinesta, Francisco; Barasinski, Anaïs; Leygue, Adrien; Dupillier, Jean-Marc
2016-10-01
In the context of processing long-fiber reinforced thermoplastic composites with laser-heating, the spatial distribution of the heat flux is one of the main parameters which controls the induced processing temperature. Unfortunately, the illuminated geometry might be not trivial, and the optical properties related to absorption and scattering phenomena of such a material are not well-established. In order to study and characterize the laser/composite interaction at the scale of the micro-structure, a model based on multiple cylinders is envisaged. The method consists in the calculation of a semi-analytical solution for the electromagnetic scattering from an array of circular cylinders due to an obliquely incident plane wave.
Magnetic fields with photon beams: dose calculation using electron multiple-scattering theory.
Jette, D
2000-08-01
Strong transverse magnetic fields can produce large dose enhancements and reductions in localized regions of a patient under irradiation by a photon beam. We have developed a new equation of motion for the transport of charged particles in an arbitrary magnetic field, incorporating both energy loss and multiple scattering. Key to modeling the latter process is a new concept, that of "typical scattered particles." The formulas which we have arrived at are particularly applicable to the transport of, and deposition of energy by, Compton electrons and pair-production electrons and positrons generated within a medium by a photon beam, and we have shown qualitatively how large dose enhancements and reductions can occur. A companion article examines this dose modification effect through systematic Monte Carlo simulations.
NASA Astrophysics Data System (ADS)
Sica, R. J.; Haefele, A.
2014-12-01
The measurement of temperature in the middle atmosphere with Rayleigh-scatter lidars is an important technique for assessing atmospheric change. Current retrieval schemes for these temperature have several shortcoming which can be overcome using an optimal estimation method (OEM). OEMs are applied to the retrieval of temperature from Rayleigh-scatter lidar measurements using both single and multiple channel measurements. Forward models are presented that completely characterize the measurement and allow the simultaneous retrieval of temperature, dead time and background. The method allows a full uncertainty budget to be obtained on a per profile basis that includes, in addition to the statistical uncertainties, the smoothing error and uncertainties due to Rayleigh extinction, ozone absorption, the lidar constant, nonlinearity in the counting system, variation of the Rayleigh-scatter cross section with altitude, pressure, acceleration due to gravity and the variation of mean molecular mass with altitude. The vertical resolution of the temperature profile is found at each height, and a quantitative determination is made of the maximum height to which the retrieval is valid. A single temperature profile can be retrieved from measurements with multiple channels that cover different height ranges, vertical resolutions and even different detection methods. The OEM employed is shown to give robust estimates of temperature consistent with previous methods, while requiring minimal computational time. This demonstrated success of lidar temperature retrievals using an OEM opens new possibilities in atmospheric science for measurement integration between active and passive remote sensing instruments. We are currently working on extending our method to simultaneously retrieve water vapour and temperature using Raman-scatter lidar measurements.
NASA Astrophysics Data System (ADS)
Moshe, Tomer; Firer, Michael A.; Abookasis, David
2015-05-01
In this paper, we present a hybrid method for improving the imaging quality of objects obscured within a scattering environment by combining multiple elliptical polarized speckle contrast projections with the use of optical clearing agents (OCAs). Elliptically polarized light enables the probing of subsurface volumes, where OCAs decrease light scattering while increasing photons' penetration depth through the medium. Experiments were conducted on object sample and prostate cancer cells embedded within ex vivo biological samples (chicken breasts) in reflection configuration. After immersion with OCAs, the medium was irradiated with an elliptically polarized laser beam and multiple polarized speckled images obtained from a lens array were first converted to speckled contrast images and then processed using a self-deconvolution shift-and-add algorithm. The conversion to contrast images and multiple perspectives acquisition was found to emphasize contrast. Analysis of image quality indicated improvement in object visualization by the combination of elliptical polarization and OCAs. This enhanced imaging strategy may advance the development of improved methods in biomedicine field, specifically biomedical tomography.
A High Performance Computing approach to model multiple Rayleigh scattering in the Earth atmosphere
NASA Astrophysics Data System (ADS)
Franssens, Ghislain; Dekemper, Emmanuel; Mateshivili, Nina; Vanhellemont, filip; fussen, didier; pieroux, didier
2016-04-01
The retrieval of atmospheric trace gases and aerosols in the Earth atmosphere from light scattering measurements typically involves an iterative inversion algorithm. A key part of this algorithm is its forward model, which takes care of calculating the amount of light that the remote sensing instrument will see, for any assumed atmosphere composition. The forward model is usually an atmospheric radiative transfer code. It is a serious challenge for a radiative transfer code to be, at the same time, sufficiently accurate and sufficiently fast, so that it can be included in the iterative retrieval loop of an operational service. An accurate code must be able to calculate multiple Rayleigh scattering (important in the UV and/or at lower altitudes) by the air in a spherical atmosphere. This is something that currently only a Monte Carlo algorithm can do. However, any Monte Carlo code is far too slow to be included in the retrieval loop, even if we make use of the currently available HPC power. We report some first results that were obtained by a new solution to this old problem. We first use a HPC cluster to tabulate multiple Rayleigh scattering in a standard Earth atmosphere, using a Monte Carlo code, as function of 6 parameters (albedo, view zenith angle, solar zenith angle, relative azimuth angle, altitude and wavelength). Then, a well chosen empirical function is fitted on the tabulated data. From this function, correction factors are derived and appropriately inserted in a fast single scattering algorithm, which so effectively becomes a multiple scattering algorithm. Since the evaluation of the empirical function is also very fast, we end up with a radiative transfer code that is both accurate and sufficiently fast for operational data production. Our conclusion is that commonly available and affordable HPC systems can still not directly solve the retrieval problem with sufficient accuracy in real time. However, the above described two step approach now becomes
NASA Technical Reports Server (NTRS)
Toon, Owen B.; Mckay, C. P.; Ackerman, T. P.; Santhanam, K.
1989-01-01
The solution of the generalized two-stream approximation for radiative transfer in homogeneous multiple scattering atmospheres is extended to vertically inhomogeneous atmospheres in a manner which is numerically stable and computationally efficient. It is shown that solar energy deposition rates, photolysis rates, and infrared cooling rates all may be calculated with the simple modifications of a single algorithm. The accuracy of the algorithm is generally better than 10 percent, so that other uncertainties, such as in absorption coefficients, may often dominate the error in calculation of the quantities of interest to atmospheric studies.
NASA Astrophysics Data System (ADS)
Gong, Z.; Hu, R. H.; Shou, Y. R.; Qiao, B.; Chen, C. E.; He, X. T.; Bulanov, S. S.; Esirkepov, T. Zh.; Bulanov, S. V.; Yan, X. Q.
2017-01-01
γ -ray flash generation in near-critical-density target irradiated by four symmetrical colliding laser pulses is numerically investigated. With peak intensities about 1023 W /cm2, the laser pulses boost electron energy through direct laser acceleration, while pushing them inward with the ponderomotive force. After backscattering with counterpropagating laser, the accelerated electron is trapped in the electromagnetic standing waves or the ponderomotive potential well created by the coherent overlapping of the laser pulses, and emits γ -ray photons in a multiple-laser-scattering regime, where electrons act as a medium transferring energy from the laser to γ rays in the ponderomotive potential valley.
NASA Astrophysics Data System (ADS)
Mounaix, Mickael; Andreoli, Daria; Defienne, Hugo; Volpe, Giorgio; Katz, Ori; Grésillon, Samuel; Gigan, Sylvain
2016-06-01
We report the broadband characterization of the propagation of light through a multiple scattering medium by means of its multispectral transmission matrix. Using a single spatial light modulator, our approach enables the full control of both the spatial and spectral properties of an ultrashort pulse transmitted through the medium. We demonstrate spatiotemporal focusing of the pulse at any arbitrary position and time with any desired spectral shape. Our approach opens new perspectives for fundamental studies of light-matter interaction in disordered media, and has potential applications in sensing, coherent control, and imaging.
Multiple-scattering approach to the x-ray-absorption spectra of perovskite-type compounds
NASA Astrophysics Data System (ADS)
Kitamura, Michihide; Muramatsu, Shinji; Sugiura, Chikara
1988-04-01
The metal K x-ray-absorption near-edge structure has been calculated for the first time from a multiple-scattering formalism for the perovskite-type compounds KMnF3, KFeF3, KCoF3, KNiF3, and KZnF3. The calculation includes the effects of a core hole and of Madelung corrections for crystal potentials. It is shown that the results including the lifetime-broadening effect are in good agreement with the experiment of Shulman et al.
NASA Astrophysics Data System (ADS)
Kondrat'ev, Andrei V.
2004-06-01
Variation in the correlation function of light multiply scattered by a random medium was observed with increasing the incident beam power. The light-induced motion of microparticles in suspension, caused by a high-power laser radiation, serves as an additional factor in the decorrelation of the scattered light. The experimental data are in good agreement with the results of theoretical analysis.
NASA Technical Reports Server (NTRS)
Chick, Kenneth M.; Gombosi, Tamas I.
1993-01-01
A numerical solution for the multiple light scattering in spherical axisymmetric geometry is applied to the simulation of images of a coma as it would appear to a near-flying satellite such as Giotto. The appearance of symmetric comas and dust jets is examined in detail; the nucleus visibility is studied; the effect of forward scattering is considered; and single and multiple scattering effects are quantified. Attention is given to simulated images of a coma with a hollow cone of dust, as predicted by dust-gas hydrodynamic modeling. The cone's appearance is very similar to the northern area of activity on Comet Halley, observed by the Giotto HMC.
NASA Technical Reports Server (NTRS)
Chick, Kenneth M.; Gombosi, Tamas I.
1993-01-01
A numerical solution for the multiple light scattering in spherical axisymmetric geometry is applied to the simulation of images of a coma as it would appear to a near-flying satellite such as Giotto. The appearance of symmetric comas and dust jets is examined in detail; the nucleus visibility is studied; the effect of forward scattering is considered; and single and multiple scattering effects are quantified. Attention is given to simulated images of a coma with a hollow cone of dust, as predicted by dust-gas hydrodynamic modeling. The cone's appearance is very similar to the northern area of activity on Comet Halley, observed by the Giotto HMC.
A MULTIPLE SCATTERING POLARIZED RADIATIVE TRANSFER MODEL: APPLICATION TO HD 189733b
Kopparla, Pushkar; Yung, Yuk L.; Natraj, Vijay; Swain, Mark R.; Zhang, Xi; Wiktorowicz, Sloane J.
2016-01-20
We present a multiple scattering vector radiative transfer model that produces disk integrated, full phase polarized light curves for reflected light from an exoplanetary atmosphere. We validate our model against results from published analytical and computational models and discuss a small number of cases relevant to the existing and possible near-future observations of the exoplanet HD 189733b. HD 189733b is arguably the most well observed exoplanet to date and the only exoplanet to be observed in polarized light, yet it is debated if the planet’s atmosphere is cloudy or clear. We model reflected light from clear atmospheres with Rayleigh scattering, and cloudy or hazy atmospheres with Mie and fractal aggregate particles. We show that clear and cloudy atmospheres have large differences in polarized light as compared to simple flux measurements, though existing observations are insufficient to make this distinction. Futhermore, we show that atmospheres that are spatially inhomogeneous, such as being partially covered by clouds or hazes, exhibit larger contrasts in polarized light when compared to clear atmospheres. This effect can potentially be used to identify patchy clouds in exoplanets. Given a set of full phase polarimetric measurements, this model can constrain the geometric albedo, properties of scattering particles in the atmosphere, and the longitude of the ascending node of the orbit. The model is used to interpret new polarimetric observations of HD 189733b in a companion paper.
A Multiple Scattering Polarized Radiative Transfer Model: Application to HD 189733b
NASA Astrophysics Data System (ADS)
Kopparla, Pushkar; Natraj, Vijay; Zhang, Xi; Swain, Mark R.; Wiktorowicz, Sloane J.; Yung, Yuk L.
2016-01-01
We present a multiple scattering vector radiative transfer model that produces disk integrated, full phase polarized light curves for reflected light from an exoplanetary atmosphere. We validate our model against results from published analytical and computational models and discuss a small number of cases relevant to the existing and possible near-future observations of the exoplanet HD 189733b. HD 189733b is arguably the most well observed exoplanet to date and the only exoplanet to be observed in polarized light, yet it is debated if the planet’s atmosphere is cloudy or clear. We model reflected light from clear atmospheres with Rayleigh scattering, and cloudy or hazy atmospheres with Mie and fractal aggregate particles. We show that clear and cloudy atmospheres have large differences in polarized light as compared to simple flux measurements, though existing observations are insufficient to make this distinction. Futhermore, we show that atmospheres that are spatially inhomogeneous, such as being partially covered by clouds or hazes, exhibit larger contrasts in polarized light when compared to clear atmospheres. This effect can potentially be used to identify patchy clouds in exoplanets. Given a set of full phase polarimetric measurements, this model can constrain the geometric albedo, properties of scattering particles in the atmosphere, and the longitude of the ascending node of the orbit. The model is used to interpret new polarimetric observations of HD 189733b in a companion paper.
Neural Network Emulation of the Integral Equation Model with Multiple Scattering
Pulvirenti, Luca; Ticconi, Francesca; Pierdicca, Nazzareno
2009-01-01
The Integral Equation Model with multiple scattering (IEMM) represents a well-established method that provides a theoretical framework for the scattering of electromagnetic waves from rough surfaces. A critical aspect is the long computational time required to run such a complex model. To deal with this problem, a neural network technique is proposed in this work. In particular, we have adopted neural networks to reproduce the backscattering coefficients predicted by IEMM at L- and C-bands, thus making reference to presently operative satellite radar sensors, i.e., that aboard ERS-2, ASAR on board ENVISAT (C-band), and PALSAR aboard ALOS (L-band). The neural network-based model has been designed for radar observations of both flat and tilted surfaces, in order to make it applicable for hilly terrains too. The assessment of the proposed approach has been carried out by comparing neural network-derived backscattering coefficients with IEMM-derived ones. Different databases with respect to those employed to train the networks have been used for this purpose. The outcomes seem to prove the feasibility of relying on a neural network approach to efficiently and reliably approximate an electromagnetic model of surface scattering. PMID:22408496
High-definition projection screen based on multiple light scattering technique
NASA Astrophysics Data System (ADS)
Suzuki, Hiromasa; Okumura, Takamitsu; Tagaya, Akihiro; Higuchi, Eizaburo; Koike, Yasuhiro
2004-05-01
A novel rear projection screen (Blue Ocean screen, Nitto Jyushi Kogyo, Co., Ltd.) has been developed. Blue Ocean screen is a single polymer plate requiring no lens element. The projected image is formed on the screen surface by the multiple light scattering. An image light is multiply scattered and is converted into homogeneous light distribution efficiently due to the internal particles of micron order dispersed in the acrylic polymer matrix. An ambient light is reduced by the dye molecules doped in the polymer and the anti-reflective coating on the screen surface. The condition of the particles and the concentration of the dye molecules have been optimized by the ray tracing simulation program based on Mie scattering theory using a Monte Carlo method. The screen containing the particles of optimum condition exhibits the wide viewing angle, the well-controlled color balance, and the high sharpness level at the same time. The contrast level of the projected image in ambient light is improved by controlling the concentration of the dye molecules. This paper describes the optimization obtained theoretically and experimentally, and demonstrates the advantage of Blue Ocean screen.
Generalized Kubelka-Munk approximation for multiple scattering of polarized light.
Sandoval, Christopher; Kim, Arnold D
2017-02-01
We introduce a new model for multiple scattering of polarized light by statistically isotropic and mirror-symmetric particles, which we call the generalized Kubelka-Munk (gKM) approximation. It is obtained through a linear transformation of the system of equations resulting from applying the double spherical harmonics approximation of order one to the vector radiative transfer equation (vRTE). The result is a 32×32 system of differential equations that is much simpler than the vRTE. We compare numerical solutions of the vRTE with the gKM approximation for the problem in which a plane wave is normally incident on a plane-parallel slab composed of a uniform absorbing and scattering medium. These comparisons show that the gKM approximation accurately captures the key features of the polarization state of multiply scattered light. In particular, the gKM approximation accurately captures the complicated polarization characteristics of light backscattered by an optically thick medium composed of a monodisperse distribution of dielectric spheres over a broad range of sphere sizes.
Multiple scattering of polarized light in turbid birefringent media: a Monte Carlo simulation.
Otsuki, Soichi
2016-07-20
Multiple scattering of polarized light in a birefringent turbid plane medium was studied using a Monte Carlo simulation. The reduced effective scattering Mueller matrix obtained in the simulation was factorized in two dimensions using the Lu-Chipman decomposition, yielding polarization parameters that exhibited dependences on the azimuth and the radial distance around the illumination point. We propose a double-scattering model for the propagation of polarized photons in turbid infinite plane media. When the birefringence slow axis is along the azimuth of 90° on the plane surface, the retardance becomes the largest negative along the azimuth of 0° and the largest positive along the azimuth of 90° and increases with increasing the azimuth from 0° to 90°. This azimuthal dependence may result from the overlap of the contributions from the light propagations vertical to, and lateral along, the plane surface. Thus, the dependences on the azimuth and the radial distance of the polarization parameters, such as the retardance, its orientation, optical rotation, and the depolarization coefficients, are correctly predicted.
Redistribution of light frequency by multiple scattering in a resonant atomic vapor
NASA Astrophysics Data System (ADS)
Carvalho, João Carlos de A.; Oriá, Marcos; Chevrollier, Martine; Cavalcante, Hugo L. D. de Souza; Passerat de Silans, T.
2015-05-01
The propagation of light in a resonant atomic vapor can a priori be thought of as a multiple scattering process, in which each scattering event redistributes both the direction and the frequency of the photons. Particularly, the frequency redistribution may result in Lévy flights of photons, directly affecting the transport properties of light in a resonant atomic vapor and turning this propagation into a superdiffusion process. Here, we report on a Monte Carlo simulation developed to study the evolution of the spectrum of the light in a resonant thermal vapor. We observe the gradual change of the spectrum and its convergence towards a regime of complete frequency redistribution as the number of scattering events increases. We also analyze the probability density function of the step length of photons between emissions and reabsorptions in the vapor, which governs the statistics of the light diffusion. We observe two different regimes in the light transport: superdiffusion when the vapor is excited near the line center and normal diffusion for excitation far from the line center. The regime of complete frequency redistribution is not reached for excitation far from resonance even after many absorption and reemission cycles due to correlations between emitted and absorbed frequencies.
Multiple solutions to dense systems in radar scattering using a preconditioned block GMRES solver
Boyse, W.E.
1996-12-31
Multiple right-hand sides occur in radar scattering calculations in the computation of the simulated radar return from a body at a large number of angles. Each desired angle requires a right-hand side vector to be computed and the solution generated. These right-hand sides are naturally smooth functions of the angle parameters and this property is utilized in a novel way to compute solutions an order of magnitude faster than LINPACK The modeling technique addressed is the Method of Moments (MOM), i.e. a boundary element method for time harmonic Maxwell`s equations. Discretization by this method produces general complex dense systems of rank 100`s to 100,000`s. The usual way to produce the required multiple solutions is via LU factorization and solution routines such as found in LINPACK. Our method uses the block GMRES iterative method to directly iterate a subset of the desired solutions to convergence.
Stimulated Raman scattering of high pressure gas in multiple-pass configuration
NASA Astrophysics Data System (ADS)
Li, Zhonghui; Cai, XiangLong; Guo, Jingwei; Cai, Hongxing; Chen, Gao
2017-01-01
SRS (Stimulated Raman Scattering) is a very effective method to expand the spectrum range of high power laser, especially in the regime of near IR and middle IR. In this paper SRS of high pressure H2 and D2 with MPC (multiple-pass cell) configuration were reported. Relation of (FS1) first forward Stokes and (BS1) first backward Stokes has been analysis. The process of gain of FS1 was explained. Experimental results also indicated the second Stokes was also generated. D2 SRS of the fundamental output of Nd:YAG laser generates the second Stokes light of 2.92 m. The lasers with wavelength of 2.9 μm have broad applications. Finally, multiple-pass SRS was better for complete conversion of pump laser.
Reichardt, J; Hess, M; Macke, A
2000-04-20
Multiple-scattering correction factors for cirrus particle extinction coefficients measured with Raman and high spectral resolution lidars are calculated with a radiative-transfer model. Cirrus particle-ensemble phase functions are computed from single-crystal phase functions derived in a geometrical-optics approximation. Seven crystal types are considered. In cirrus clouds with height-independent particle extinction coefficients the general pattern of the multiple-scattering parameters has a steep onset at cloud base with values of 0.5-0.7 followed by a gradual and monotonic decrease to 0.1-0.2 at cloud top. The larger the scattering particles are, the more gradual is the rate of decrease. Multiple-scattering parameters of complex crystals and of imperfect hexagonal columns and plates can be well approximated by those of projected-area equivalent ice spheres, whereas perfect hexagonal crystals show values as much as 70% higher than those of spheres. The dependencies of the multiple-scattering parameters on cirrus particle spectrum, base height, and geometric depth and on the lidar parameters laser wavelength and receiver field of view, are discussed, and a set of multiple-scattering parameter profiles for the correction of extinction measurements in homogeneous cirrus is provided.
A triple axis double crystal multiple reflection camera for ultra small angle X-ray scattering
NASA Astrophysics Data System (ADS)
Lambard, Jacques; Lesieur, Pierre; Zemb, Thomas
1992-06-01
To extend the domain of small angle X-ray scattering requires multiple reflection crystals to collimate the beam. A double crystal, triple axis X-ray camera using multiple reflection channel cut crystals is described. Procedures for measuring the desmeared scattering cross-section on absolute scale are described as well as the measurement from several typical samples : fibrils of collagen, 0.3 μm diameter silica spheres, 0.16 μm diameter interacting latex spheres, porous lignite coal, liquid crystals in a surfactant-water system, colloidal crystal of 0.32 μm diameter silica spheres. L'extension du domaine de diffusion des rayons-X vers les petits angles demande l'emploi de cristaux à réflexions multiples pour collimater le faisceau. Nous décrivons une caméra à rayons-X à trois axes où les réflexions multiples sont réalisées dans deux cristaux à gorge. Nous donnons ensuite les procédures de déconvolution pour obtenir la section efficace de diffusion en échelle absolue, ainsi que les résultats des mesures effectuées avec plusieurs échantillons typiques : fibres de collagène, sphères de silice de 0,3 μm de diamètre, sphères de latex de 0,16 μm de diamètre en interaction, charbon lignite poreux, cristaux liquides formés dans un système eau-tensioactif, solution colloïdale de sphères de silice de 0,32 μm de diamètre.
Green's function multiple-scattering theory with a truncated basis set: An augmented-KKR formalism
Alam, Aftab; Khan, Suffian N.; Smirnov, A. V.; Nicholson, D. M.; Johnson, Duane D.
2014-11-04
Korringa-Kohn-Rostoker (KKR) Green's function, multiple-scattering theory is an ecient sitecentered, electronic-structure technique for addressing an assembly of N scatterers. Wave-functions are expanded in a spherical-wave basis on each scattering center and indexed up to a maximum orbital and azimuthal number L_{max} = (l,m)_{max}, while scattering matrices, which determine spectral properties, are truncated at L_{tr} = (l,m)_{tr} where phase shifts δl>l_{tr} are negligible. Historically, L_{max} is set equal to L_{tr}, which is correct for large enough L_{max} but not computationally expedient; a better procedure retains higher-order (free-electron and single-site) contributions for L_{max} > L_{tr} with δl>l_{tr} set to zero [Zhang and Butler, Phys. Rev. B 46, 7433]. We present a numerically ecient and accurate augmented-KKR Green's function formalism that solves the KKR equations by exact matrix inversion [R^{3} process with rank N(l_{tr} + 1)^{2}] and includes higher-L contributions via linear algebra [R^{2} process with rank N(l_{max} +1)^{2}]. Augmented-KKR approach yields properly normalized wave-functions, numerically cheaper basis-set convergence, and a total charge density and electron count that agrees with Lloyd's formula. We apply our formalism to fcc Cu, bcc Fe and L1_{0} CoPt, and present the numerical results for accuracy and for the convergence of the total energies, Fermi energies, and magnetic moments versus L_{max} for a given L_{tr}.
Green's function multiple-scattering theory with a truncated basis set: An augmented-KKR formalism
Alam, Aftab; Khan, Suffian N.; Smirnov, A. V.; ...
2014-11-04
Korringa-Kohn-Rostoker (KKR) Green's function, multiple-scattering theory is an ecient sitecentered, electronic-structure technique for addressing an assembly of N scatterers. Wave-functions are expanded in a spherical-wave basis on each scattering center and indexed up to a maximum orbital and azimuthal number Lmax = (l,m)max, while scattering matrices, which determine spectral properties, are truncated at Ltr = (l,m)tr where phase shifts δl>ltr are negligible. Historically, Lmax is set equal to Ltr, which is correct for large enough Lmax but not computationally expedient; a better procedure retains higher-order (free-electron and single-site) contributions for Lmax > Ltr with δl>ltr set to zero [Zhang andmore » Butler, Phys. Rev. B 46, 7433]. We present a numerically ecient and accurate augmented-KKR Green's function formalism that solves the KKR equations by exact matrix inversion [R3 process with rank N(ltr + 1)2] and includes higher-L contributions via linear algebra [R2 process with rank N(lmax +1)2]. Augmented-KKR approach yields properly normalized wave-functions, numerically cheaper basis-set convergence, and a total charge density and electron count that agrees with Lloyd's formula. We apply our formalism to fcc Cu, bcc Fe and L10 CoPt, and present the numerical results for accuracy and for the convergence of the total energies, Fermi energies, and magnetic moments versus Lmax for a given Ltr.« less
Green's function multiple-scattering theory with a truncated basis set: An augmented-KKR formalism
NASA Astrophysics Data System (ADS)
Alam, Aftab; Khan, Suffian N.; Smirnov, A. V.; Nicholson, D. M.; Johnson, Duane D.
2014-11-01
The Korringa-Kohn-Rostoker (KKR) Green's function, multiple-scattering theory is an efficient site-centered, electronic-structure technique for addressing an assembly of N scatterers. Wave functions are expanded in a spherical-wave basis on each scattering center and indexed up to a maximum orbital and azimuthal number Lmax=(l,mmax), while scattering matrices, which determine spectral properties, are truncated at Lt r=(l,mt r) where phase shifts δl >ltr are negligible. Historically, Lmax is set equal to Lt r, which is correct for large enough Lmax but not computationally expedient; a better procedure retains higher-order (free-electron and single-site) contributions for Lmax>Lt r with δl >ltr set to zero [X.-G. Zhang and W. H. Butler, Phys. Rev. B 46, 7433 (1992), 10.1103/PhysRevB.46.7433]. We present a numerically efficient and accurate augmented-KKR Green's function formalism that solves the KKR equations by exact matrix inversion [R3 process with rank N (ltr+1 ) 2 ] and includes higher-L contributions via linear algebra [R2 process with rank N (lmax+1) 2 ]. The augmented-KKR approach yields properly normalized wave functions, numerically cheaper basis-set convergence, and a total charge density and electron count that agrees with Lloyd's formula. We apply our formalism to fcc Cu, bcc Fe, and L 1 0 CoPt and present the numerical results for accuracy and for the convergence of the total energies, Fermi energies, and magnetic moments versus Lmax for a given Lt r.
NASA Astrophysics Data System (ADS)
Agueny, H.; Makhoute, A.; Tökési, K.; Dubois, A.; Hansen, J. P.
2017-09-01
We theoretically investigate electron emission process from a dimer generated by swift highly charged ions. The process under consideration is dealt with a non-perturbative approach by solving the time-dependent Schrödinger equation on a two-dimensional spatial grid. Numerical calculations show rich structures related to the multiple scattering paths of the electron prior to emission. This manifests by the emergence of additional oscillations with high-frequency superimposed on the Young-type oscillatory structure in the observed electron-ejected spectrum. This is not the case when calculations are performed based on the superposition principle, in which the final wave function is just a coherent sum of component wave functions described the electron emission from two-independent atoms. Within this assumption, only a direct electron emission process is taken into account. We find that contributions arising from these multiple scattering paths modify the dynamic electron emission process, and therefore, show the incorrect applicability of the above-mentioned principle, in concordance with the recent findings based on a simple three-slit interference experiment, reported in Sawant et al. (2014).
Multiplicities of charged kaons from deep-inelastic muon scattering off an isoscalar target
NASA Astrophysics Data System (ADS)
Adolph, C.; Aghasyan, M.; Akhunzyanov, R.; Alexeev, M. G.; Alexeev, G. D.; Amoroso, A.; Andrieux, V.; Anfimov, N. V.; Anosov, V.; Augsten, K.; Augustyniak, W.; Austregesilo, A.; Azevedo, C. D. R.; Badełek, B.; Balestra, F.; Ball, M.; Barth, J.; Beck, R.; Bedfer, Y.; Bernhard, J.; Bicker, K.; Bielert, E. R.; Birsa, R.; Bodlak, M.; Bordalo, P.; Bradamante, F.; Braun, C.; Bressan, A.; Büchele, M.; Capozza, L.; Chang, W.-C.; Chatterjee, C.; Chiosso, M.; Choi, I.; Chung, S.-U.; Cicuttin, A.; Crespo, M. L.; Curiel, Q.; Dalla Torre, S.; Dasgupta, S. S.; Dasgupta, S.; Denisov, O. Yu.; Dhara, L.; Donskov, S. V.; Doshita, N.; Dreisbach, Ch.; Duic, V.; Dünnweber, W.; Dziewiecki, M.; Efremov, A.; Eversheim, P. D.; Eyrich, W.; Faessler, M.; Ferrero, A.; Finger, M.; Finger, M.; Fischer, H.; Franco, C.; du Fresne von Hohenesche, N.; Friedrich, J. M.; Frolov, V.; Fuchey, E.; Gautheron, F.; Gavrichtchouk, O. P.; Gerassimov, S.; Giordano, F.; Gnesi, I.; Gorzellik, M.; Grabmüller, S.; Grasso, A.; Grosse Perdekamp, M.; Grube, B.; Grussenmeyer, T.; Guskov, A.; Haas, F.; Hahne, D.; Hamar, G.; von Harrach, D.; Heinsius, F. H.; Heitz, R.; Herrmann, F.; Horikawa, N.; d'Hose, N.; Hsieh, C.-Y.; Huber, S.; Ishimoto, S.; Ivanov, A.; Ivanshin, Yu.; Iwata, T.; Jary, V.; Joosten, R.; Jörg, P.; Kabuß, E.; Ketzer, B.; Khaustov, G. V.; Khokhlov, Yu. A.; Kisselev, Yu.; Klein, F.; Klimaszewski, K.; Koivuniemi, J. H.; Kolosov, V. N.; Kondo, K.; Königsmann, K.; Konorov, I.; Konstantinov, V. F.; Kotzinian, A. M.; Kouznetsov, O. M.; Krämer, M.; Kremser, P.; Krinner, F.; Kroumchtein, Z. V.; Kulinich, Y.; Kunne, F.; Kurek, K.; Kurjata, R. P.; Lednev, A. A.; Lehmann, A.; Levillain, M.; Levorato, S.; Lian, Y.-S.; Lichtenstadt, J.; Longo, R.; Maggiora, A.; Magnon, A.; Makins, N.; Makke, N.; Mallot, G. K.; Marianski, B.; Martin, A.; Marzec, J.; Matoušek, J.; Matsuda, H.; Matsuda, T.; Meshcheryakov, G. V.; Meyer, M.; Meyer, W.; Mikhailov, Yu. V.; Mikhasenko, M.; Mitrofanov, E.; Mitrofanov, N.; Miyachi, Y.; Nagaytsev, A.; Nerling, F.; Neyret, D.; Nový, J.; Nowak, W.-D.; Nukazuka, G.; Nunes, A. S.; Olshevsky, A. G.; Orlov, I.; Ostrick, M.; Panzieri, D.; Parsamyan, B.; Paul, S.; Peng, J.-C.; Pereira, F.; Pešek, M.; Peshekhonov, D. V.; Pierre, N.; Platchkov, S.; Pochodzalla, J.; Polyakov, V. A.; Pretz, J.; Quaresma, M.; Quintans, C.; Ramos, S.; Regali, C.; Reicherz, G.; Riedl, C.; Roskot, M.; Rossiyskaya, N. S.; Ryabchikov, D. I.; Rybnikov, A.; Rychter, A.; Salac, R.; Samoylenko, V. D.; Sandacz, A.; Santos, C.; Sarkar, S.; Savin, I. A.; Sawada, T.; Sbrizzai, G.; Schiavon, P.; Schmidt, K.; Schmieden, H.; Schönning, K.; Seder, E.; Selyunin, A.; Silva, L.; Sinha, L.; Sirtl, S.; Slunecka, M.; Smolik, J.; Sozzi, F.; Srnka, A.; Steffen, D.; Stolarski, M.; Subrt, O.; Sulc, M.; Suzuki, H.; Szabelski, A.; Szameitat, T.; Sznajder, P.; Takekawa, S.; Tasevsky, M.; Tessaro, S.; Tessarotto, F.; Thibaud, F.; Thiel, A.; Tosello, F.; Tskhay, V.; Uhl, S.; Veloso, J.; Virius, M.; Vondra, J.; Wallner, S.; Weisrock, T.; Wilfert, M.; Windmolders, R.; ter Wolbeek, J.; Zaremba, K.; Zavada, P.; Zavertyaev, M.; Zemlyanichkina, E.; Zhuravlev, N.; Ziembicki, M.; Zink, A.
2017-04-01
Precise measurements of charged-kaon multiplicities in deep inelastic scattering were performed. The results are presented in three-dimensional bins of the Bjorken scaling variable x, the relative virtual-photon energy y, and the fraction z of the virtual-photon energy carried by the produced hadron. The data were obtained by the COMPASS Collaboration by scattering 160 GeV muons off an isoscalar 6LiD target. They cover the kinematic domain 1(GeV / c)2
Topographic mapping flash lidar for multiple scattering, terrain, and forest mapping
NASA Astrophysics Data System (ADS)
Ramond, Tanya; Saiki, Eileen; Weimer, Carl; Applegate, Jeff; Hu, Yongxiang; Delker, Thomas; Ruppert, Lyle; Donley, Brian
2011-06-01
The Topographic Mapping Flash Lidar (TMFL) developed at Ball Aerospace combines a pushbroom format transmitter at 1064 nm with a flash focal plane receiver. The wide 20 degree field of view of the instrument enables broad swath coverage from a single laser pulse without the need for a scanning mechanism. These features make the TMFL design particularly well-suited for space flight. TMFL has been demonstrated during an airborne flight where data were gathered over a forest plot to measure tree waveforms. Topographic maps were assembled of river beds and geologic areas of high relief. The TMFL has also been used to observe multiple-scattering phenomena in clouds by illuminating a steam plume from the aircraft above. Signal was recorded off-axis from the illuminated laser line by as much as 1 degree. The TMFL study of multiple-scattering is valuable as it provides a unique way to significantly improve the calibration of measured backscatter for space lidars. Lidar backscatter was also measured from water surface and was shown to correlate with models of water surface roughness.
Muon Momentum Determination with Multiple Coulomb Scattering for the MicroBooNE Experiment
NASA Astrophysics Data System (ADS)
Abratenko, Polina; MicroBooNE Collaboration
2017-01-01
MicroBooNE is an experiment based at Fermilab that uses a Liquid Argon Time Projection Chamber (LArTPC) to investigate the excess of low energy events observed by the MiniBooNE experiment, study neutrino-argon cross-sections, and perform R&D for future LArTPC devices. MicroBooNE relies on the reconstruction of neutrino-induced muons for neutrino energy determination. However, a significant fraction of muons escape the detector. This talk describes a method for determining the momenta of escaping muons in LArTPC-based detectors. The technique uses information from multiple coulomb scattering to compute a muon's momentum through the maximization of a likelihood algorithm. This method was applied to both simulation and data, with momentum resolutions for both measured to be around 20% at typical MicroBooNE energies. Given this, multiple coulomb scattering provides a promising route towards energy determination for muons that escape the detector, and allows MicroBooNE to fully reconstruct and study uncontained, often high energy, events from both the Booster and NuMI neutrino beams. I will present the status and performance of the algorithm applied to simulation and data.
NASA Astrophysics Data System (ADS)
Mitri, F. G.
2017-08-01
The multiple scattering effects occurring between two scatterers are described based upon the multipole expansion formalism as well as the addition theorem of cylindrical wave functions. An original approach is presented in which an effective incident acoustic field on a particular object, which includes both the primary and re-scattered waves from the other particle is determined first, and then used with the scattered field to derive closed-form analytical expressions for the inherent (i.e. intrinsic) cross-sections based on the far-field scattering. This method does not introduce any approximation in the calculation of the intrinsic cross-sections since the procedure is reduced to the one-body problem. The mathematical expressions for the intrinsic cross-sections are formulated in partial-wave series expansions (PWSEs) in cylindrical coordinates involving the angle of incidence, the addition theorem for the cylindrical wave functions, and the expansion coefficients of the scatterers. Numerical examples illustrate the analysis for two rigid circular cylindrical cross-sections with different radii immersed in a non-viscous fluid. Computations for the dimensionless extrinsic and intrinsic extinction cross-section factors are evaluated with particular emphasis on varying the angle of incidence, the interparticle distance, as well as the sizes of the particles. A symmetric behavior is observed for the dimensionless extrinsic extinction cross-section, while asymmetry arises for the intrinsic extinction cross-section of each particle with respect to the angle of incidence. The present analysis provides a complete analytical and computational method for the prediction of the intrinsic (local) scattering, absorption and extinction cross-sections in the multiple acoustic scatterings of plane progressive waves of arbitrary incidence by a pair of scatterers. The results and computational analyses can be used as a priori information for future applications to guide the
NASA Astrophysics Data System (ADS)
Yu, Mei Ping; Han, Yi Ping; Cui, Zhi Wei; Chen, An Tao
2017-07-01
This study investigates the electromagnetic scattering of a high-order Bessel vortex beam by multiple dielectric particles of arbitrary shape based on the surface integral equation (SIE) method. In Cartesian coordinates, the mathematical formulas are given for characterizing the electromagnetic field components of an arbitrarily incident high-order Bessel vortex beam. By using the SIE, a numerical scheme is formulated to find solutions for characterizing the electromagnetic scattering by multiple homogeneous particles of arbitrary shape and a home-made FORTRAN program is written. The presented theoretical derivations as well as the home-made program are validated by comparing to the scattering results of a Zero-Order Bessel Beam by the Generalized Lorenz-Mie theory. From our simulations, the beam's order, half-cone angles, and the ways of particles' arrangement have a great influence upon the differential scattering cross section (DSCS) for multiple particles. Furthermore, for a better understanding of the scattering characteristic in three dimension (3-D) space, the 3-D distribution of the DSCS for different cases is presented. It is anticipated that these results can be helpful to understand the scattering mechanisms of a high-order Bessel vortex beam on multiple dielectric particles of arbitrary shape.
Track reconstruction for the Mu3e experiment based on a novel Multiple Scattering fit
NASA Astrophysics Data System (ADS)
Kozlinskiy, Alexandr
2017-08-01
The Mu3e experiment is designed to search for the lepton flavor violating decay μ+ → e+e+e-. The aim of the experiment is to reach a branching ratio sensitivity of 10-16. In a first phase the experiment will be performed at an existing beam line at the Paul-Scherrer Institute (Switzerland) providing 108 muons per second, which will allow to reach a sensitivity of 2 · 10-15. The muons with a momentum of about 28 MeV/c are stopped and decay at rest on a target. The decay products (positrons and electrons) with energies below 53MeV are measured by a tracking detector consisting of two double layers of 50 μm thin silicon pixel sensors. The high granularity of the pixel detector with a pixel size of 80 μm × 80 μm allows for a precise track reconstruction in the high multiplicity environment of the Mu3e experiment, reaching 100 tracks per reconstruction frame of 50 ns in the final phase of the experiment. To deal with such high rates and combinatorics, the Mu3e track reconstruction uses a novel fit algorithm that in the simplest case takes into account only the multiple scattering, which allows for a fast online tracking on a GPU based filter farm. An implementation of the 3-dimensional multiple scattering fit based on hit triplets is described. The extension of the fit that takes into account energy losses and pixel size is used for offline track reconstruction. The algorithm and performance of the offline track reconstruction based on a full Geant4 simulation of the Mu3e detector are presented.
Yang, S.; Park, S.; Makowski, L.; Roux, B.
2009-02-01
Small angle X-ray scattering (SAXS) is an increasingly powerful technique to characterize the structure of biomolecules in solution. We present a computational method for accurately and efficiently computing the solution scattering curve from a protein with dynamical fluctuations. The method is built upon a coarse-grained (CG) representation of the protein. This CG approach takes advantage of the low-resolution character of solution scattering. It allows rapid determination of the scattering pattern from conformations extracted from CG simulations to obtain scattering characterization of the protein conformational landscapes. Important elements incorporated in the method include an effective residue-based structure factor for each amino acid, an explicit treatment of the hydration layer at the surface of the protein, and an ensemble average of scattering from all accessible conformations to account for macromolecular flexibility. The CG model is calibrated and illustrated to accurately reproduce the experimental scattering curve of Hen egg white lysozyme. We then illustrate the computational method by calculating the solution scattering pattern of several representative protein folds and multiple conformational states. The results suggest that solution scattering data, when combined with a reliable computational method, have great potential for a better structural description of multi-domain complexes in different functional states, and for recognizing structural folds when sequence similarity to a protein of known structure is low. Possible applications of the method are discussed.
Neumayer, P
2007-05-14
A long-standing problem in the field of laser-plasma interactions is to successfully employ multiple-ion species plasmas to reduce stimulated Brillouin scattering (SBS) in inertial confinement fusion (ICF) hohlraum conditions. Multiple-ion species increase significantly the linear Landau damping for acoustic waves. Consequently, recent hohlraum designs for indirect-drive ignition on the National Ignition Facility investigate wall liner material options so that the liner gain for parametric instabilities will be below threshold for the onset SBS. Although the effect of two-ion species plasmas on Landau damping has been directly observed with Thomson scattering, early experiments on SBS in these plasmas have suffered from competing non-linear effects or laser beam filamentation. In this study, a reduction of SBS scattering to below the percent level has been observed in hohlraums at Omega that emulate the plasma conditions in an indirect drive ICF experiments. These experiments have measured the laser-plasma interaction processes in ignition-relevant high-electron temperature regime demonstrating Landau damping as a controlling process for SBS. The hohlraums have been filled with various fractions of CO{sub 2} and C{sub 3}H{sub 8} varying the ratio of the light (H) to heavy (C and O) ion density from 0 to 2.6. They have been heated by 14.5 kJ of 351-nm light, thus increasing progressively Landau damping by an order of magnitude at constant electron density and temperature. A delayed 351-nm interaction beam, spatially smoothed to produce a 200-{micro}m laser spot at best focus, has propagated along the axis of the hohlraum. The backscattered light, both into the lens and outside, the transmitted light through the hohlraum plasma and the radiation temperature of the hohlraum has been measured. For ignition relevant laser intensities (3-9 10{sup 14} Wcm{sup -2}), we find that the SBS reflectivity scales as predicted with Landau damping from >30% to <1%. Simultaneously
NASA Astrophysics Data System (ADS)
Petnikova, V. M.; Tret'yakov, Evgeniy V.; Shuvalov, Vladimir V.
2006-11-01
It is shown that the stability of the Henyey—Greenstein phase function allows the calculation rate of light propagation through strongly scattering objects to be drastically increased by using the same a priori information on interaction processes as in the initial formulation of the problem. The increase in the calculation rate is accompanied by a gradual impairment of simulation accuracy from the accuracy of the Monte-Carlo method to that of the diffusion approximation. By using a standard assumption about the statistical independence of the photon mean free path and photon scattering angle, an exact analytic expression relating the effective number of scattering events with the optical path is obtained.
An investigation of the internal sum convergence in the full potential multiple scattering theory
NASA Astrophysics Data System (ADS)
Wang, Yang; Rusanu, Aurelian; Stocks, G.; Faulkner, J.
2013-03-01
The ab initio methods based on multiple scattering theory (MST) have proved to be a very powerful technique for the electronic structure calculation for solids. The latest advances in the implementation of full potential MST have allowed us to investigate dislocations, point defects, and radiation damage effects on the physical properties of structural materials. In the conventional formulation of full potential MST, the single site wavefunctions ϕl , m are expanded in terms of spherical harmonics with angular momentum l up to a cutoff value ϕ-lmax. This cutoff value defines the extension of the internal sum and is usually taken to be the same as KKR-lmax, the cutoff value for the Bloch wave expansion (in terms of ϕl , m) so that the single site sine and cosine scattering matrices used for calculating the t-matrix and the Green function are square matrices. In this presentation, we show a technique that allows for ϕ-lmax to be greater than KKR-lmax, so to allow for converging the internal sum, while keeping the calculation of the t-matrix and the Green function tractable. We compare the results obtained from different ϕ-lmax values and discuss the implications of the internal sum convergence. Work supported by the Center for Defect Physics in Structural Materials (CDP), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences (GMS).
Multiple-scattering effects in nucleus-nucleus reactions with Glauber theory
NASA Astrophysics Data System (ADS)
Hatakeyama, Shinya; Ebata, Shuichiro; Horiuchi, Wataru; Kimura, Masaaki
2014-09-01
A study of new unstable nuclei has become possible in new radioactive beam facilities. In order to understand the relationship between reaction observables and nuclear structure, we need reaction theory which exactly reflects the nuclear structure. The Glauber theory is a powerful tool of analyzing high energy nuclear reactions. The theory describes the multiple scattering processes, whereas the optical limit approximation (OLA), which is widely used, ignores those processes. Those effects are expected to play an important role in the nuclear collision involving unstable nuclei (see for example Phys. Rev. C 54, 1843 (1996)). Here we apply the Glauber theory to nucleus-nucleus reactions. The wave functions are generated by the Skyrme-Hartree-Fock method and are expressed in a Slater determinant that allows us to evaluate the complete Glauber amplitude easily. We calculate total reaction cross sections, elastic cross sections and differential elastic cross sections for 16~24O, 40~70Ca, 56,58Ni, 100~140Sn, 190~214Pb on proton, 4He, 12C targets and compare with experimental data. The Glauber theory gives much better description than the OLA, especially at larger scattering angles.
Comparison of Geant4 multiple Coulomb scattering models with theory for radiotherapy protons
NASA Astrophysics Data System (ADS)
Makarova, Anastasia; Gottschalk, Bernard; Sauerwein, Wolfgang
2017-08-01
Usually, Monte Carlo models are validated against experimental data. However, models of multiple Coulomb scattering (MCS) in the Gaussian approximation are exceptional in that we have theories which are probably more accurate than the experiments which have, so far, been done to test them. In problems directly sensitive to the distribution of angles leaving the target, the relevant theory is the Molière/Fano/Hanson variant of Molière theory (Gottschalk et al 1993 Nucl. Instrum. Methods Phys. Res. B 74 467-90). For transverse spreading of the beam in the target itself, the theory of Preston and Koehler (Gottschalk (2012 arXiv:1204.4470)) holds. Therefore, in this paper we compare Geant4 simulations, using the Urban and Wentzel models of MCS, with theory rather than experiment, revealing trends which would otherwise be obscured by experimental scatter. For medium-energy (radiotherapy) protons, and low-Z (water-like) target materials, Wentzel appears to be better than Urban in simulating the distribution of outgoing angles. For beam spreading in the target itself, the two models are essentially equal.
Yi Xu; Xiao Yunfeng; Liu Yongchun; Li Beibei; Chen Youling; Li Yan; Gong Qihuang
2011-02-15
We theoretically investigate the mode-splitting phenomenon in a high-Q whispering-gallery-mode (WGM) microresonator coupled to multiple subwavelength Rayleigh scatterers. It is shown that the phase factors of the WGMs play the central role in such a system. Unlike the single-scatterer case, these phase factors in a multiscatterer system significantly influence both the modal coupling strength and the scattering-induced loss of a pair of counterpropagating WGMs. We scrutinize the condition for observing the splitting of transmission spectra. The mechanism can be used for highly sensitive biosensing, and the size of nanoparticles that can be detected is extended down to tens of nanometers.
Multiple scattering filter: Application to plane defect detection in a nickel alloy
NASA Astrophysics Data System (ADS)
Trottier, Camille; Shahjhan, Sharfine; Schumm, Andreas; Aubry, Alexandre; Derode, Arnaud
2016-02-01
The ultrasonic inspection of polycrystalline media remains a challenge. The high noise levels due to interaction between the wave and the microstructure limit the efficiency of classical ultrasonic techniques to detect a defect in a coarse grain structure. The aim of this work is to reduce the influence of multiple scattering in order to increase the information obtained from the defect. The technique introduced here is based on array probes for the acquisition of the medium's response matrix by full matrix capture, after which a filter based on random matrix theory is applied. Here an improvement of this technique is applied on nickel-based alloy mock-ups that present an unfavourable grain structure and well known bulk and plane defects. The results in normal incidence and with an angle array probe of 128 elements and 5 MHz of central frequency are compared to classical phased array probe techniques.
Multiple scattering and the Rehr-Albers-Fritzsche formula for the propagator matrix
NASA Astrophysics Data System (ADS)
Martin, P. A.
1998-11-01
The propagator matrix is one ingredient in exact theories of multiple scattering. It occurs in the addition theorem (or translation formula) for expanding a spherical outgoing multipole, singular at one point, in terms of regular spherical solutions about another point. It also occurs in the two-centre expansion of the free-space Green's function (or free-particle propagator). Many methods have been devised for computing the propagator matrix, but one of the most efficient, numerically, is based on a formula obtained in 1990 by Rehr and Albers and by Fritzsche. A clear derivation of this formula is given. The formula is also simplified, leading to an expansion in inverse powers of kb, where k is the wavenumber and b is the spacing. This leads to consistent approximations, which are asymptotic as 0305-4470/31/44/016/img1.
Multiple Scattering of Seismic Waves from Ensembles of Upwardly Lossy Thin Flux Tubes
NASA Astrophysics Data System (ADS)
Hanson, Chris S.; Cally, Paul S.
2015-07-01
Our previous semi-analytic treatment of - and -mode multiple scattering from ensembles of thin flux tubes (Hanson and Cally, Astrophys. J. 781, 125, 2014a; 791, 129, 2014b) is extended by allowing both sausage and kink waves to freely escape at the top of the model using a radiative boundary condition there. As expected, this additional avenue of escape, supplementing downward loss into the deep solar interior, results in substantially greater absorption of incident - and -modes. However, less intuitively, it also yields mildly to substantially smaller phase shifts in waves emerging from the ensemble. This may have implications for the interpretation of seismic data for solar plage regions, and in particular their small measured phase shifts.
Asymmetric acoustic transmission in an open channel based on multiple scattering mechanism
NASA Astrophysics Data System (ADS)
Ge, Yong; Sun, Hong-xiang; Yuan, Shou-qi; Xia, Jian-ping
2017-05-01
We report both experimentally and theoretically that asymmetric acoustic transmission is realized by an open channel with two triangle cavities of different sizes on each side immersed in air. This exotic phenomenon stems from asymmetric multiple scatterings induced by the triangle cavities, which is different from the previous devices based on acoustic metasurfaces. In addition, the influences of the temperature and machining inaccuracies on the asymmetric transmission effect are investigated in detail, and the asymmetric acoustic transmission still exists with the excitation of the cylindrical acoustic source. Our device is very simple and easy to be realized, and opens a new way to design the devices of the asymmetric acoustic transmission, which has great potential applications in acoustic rectifiers and acoustic diodes.
Momentum measurement by the multiple Coulomb scattering method in the OPERA lead-emulsion target
NASA Astrophysics Data System (ADS)
Agafonova, N.; Aleksandrov, A.; Altinok, O.; Anokhina, A.; Aoki, S.; Ariga, A.; Ariga, T.; Autiero, D.; Badertscher, A.; Bagulya, A.; Ben Dhahbi, A.; Bertolin, A.; Besnier, M.; Bozza, C.; Brugière, T.; Brugnera, R.; Brunet, F.; Brunetti, G.; Buontempo, S.; Cazes, A.; Chaussard, L.; Chernyavskiy, M.; Chiarella, V.; Chukanov, A.; D'Ambrosio, N.; Dal Corso, F.; De Lellis, G.; del Amo Sanchez, P.; Déclais, Y.; De Serio, M.; Di Capua, F.; Di Crescenzo, A.; Di Ferdinando, D.; Di Marco, N.; Dmitrievski, S.; Dracos, M.; Duchesneau, D.; Dusini, S.; Dzhatdoev, T.; Ebert, J.; Egorov, O.; Enikeev, R.; Ereditato, A.; Esposito, L. S.; Favier, J.; Ferber, T.; Fini, R. A.; Frekers, D.; Fukuda, T.; Garfagnini, A.; Giacomelli, G.; Giorgini, M.; Göllnitz, C.; Goldberg, J.; Golubkov, D.; Goncharova, L.; Gornushkin, Y.; Grella, G.; Grianti, F.; Guler, A. M.; Gustavino, C.; Hagner, C.; Hamada, K.; Hara, T.; Hierholzer, M.; Hollnagel, A.; Hoshino, K.; Ieva, M.; Ishida, H.; Jakovcic, K.; Jollet, C.; Juget, F.; Kamiscioglu, M.; Kazuyama, K.; Kim, S. H.; Kimura, M.; Kitagawa, N.; Klicek, B.; Knuesel, J.; Kodama, K.; Komatsu, M.; Kose, U.; Kreslo, I.; Kubota, H.; Lazzaro, C.; Lenkeit, J.; Lippi, I.; Ljubicic, A.; Longhin, A.; Loverre, P.; Lutter, G.; Malgin, A.; Mandrioli, G.; Manai, K.; Marteau, J.; Matsuo, T.; Matveev, V.; Mauri, N.; Medinaceli, E.; Meisel, F.; Meregaglia, A.; Migliozzi, P.; Mikado, S.; Miyamoto, S.; Monacelli, P.; Morishima, K.; Moser, U.; Muciaccia, M. T.; Naganawa, N.; Naka, T.; Nakamura, M.; Nakano, T.; Naumov, D.; Nikitina, V.; Niwa, K.; Nonoyama, Y.; Ogawa, S.; Okateva, N.; Olshevskiy, A.; Paniccia, M.; Paoloni, A.; Park, B. D.; Park, I. G.; Pastore, A.; Patrizii, L.; Pennacchio, E.; Pessard, H.; Pretzl, K.; Pilipenko, V.; Pistillo, C.; Polukhina, N.; Pozzato, M.; Pupilli, F.; Rescigno, R.; Roganova, T.; Rokujo, H.; Romano, G.; Rosa, G.; Rostovtseva, I.; Rubbia, A.; Russo, A.; Ryasny, V.; Ryazhskaya, O.; Sato, O.; Sato, Y.; Schembri, A.; Schmidt-Parzefall, W.; Schroeder, H.; Scotto Lavina, L.; Sheshukov, A.; Shibuya, H.; Shoziyoev, G.; Simone, S.; Sioli, M.; Sirignano, C.; Sirri, G.; Song, J. S.; Spinetti, M.; Stanco, L.; Starkov, N.; Stipcevic, M.; Strauss, T.; Strolin, P.; Takahashi, S.; Tenti, M.; Terranova, F.; Tezuka, I.; Tioukov, V.; Tolun, P.; Trabelsi, A.; Tran, T.; Tufanli, S.; Vilain, P.; Vladimirov, M.; Votano, L.; Vuilleumier, J. L.; Wilquet, G.; Wonsak, B.; Yakushev, V.; Yoon, C. S.; Yoshioka, T.; Yoshida, J.; Zaitsev, Y.; Zemskova, S.; Zghiche, A.; Zimmermann, R.
2012-01-01
A new method of momentum measurement of charged particles through multiple Coulomb scattering (MCS) in the OPERA lead-emulsion target is presented. It is based on precise measurements of track angular deviations carried out thanks to the very high resolution of nuclear emulsions. The algorithm has been tested with Monte Carlo pions. The results are found to describe within the expected uncertainties the data obtained from test beams. We also present a comparison of muon momenta evaluated through MCS in the OPERA lead-emulsion target with those determined by the electronic detectors for neutrino-charged current interaction events. The two independent measurements agree within the experimental uncertainties, and the results validate the algorithm developed for the emulsion detector of OPERA.
Green s functions in full-potential multiple-scattering theory
Rusanu, Aurelian; Stocks, George Malcolm; Wang, Yang; Faulkner, John Sam
2011-01-01
One-electron Green s functions play a central role in multiple-scattering theory (MST) based electronic- structure methods. Robust methods exist for calculating the Green s function for crystal potentials that are spherically symmetric about atomic centers. When applied to potentials of general shape, these same techniques result in pathologies in the small-r behavior of the electronic charge density because a portion of the Green s function can become singular at the origin for that case. We propose an algebraic method that eliminates the singular behavior by making use of the equivalence of two terms that involve poles in the inverse of the sine matrix. Our accurate calculations illustrate the limitations of previous methods for treating this problem that rely on extrapolating the solutions near the origin.
NASA Astrophysics Data System (ADS)
Amamou, Manel L.
2016-05-01
This paper develops an analytical solution for sound, electromagnetic or any other wave propagation described by the Helmholtz equation in three-dimensional case. First, a theoretical investigation based on multipole expansion method and spherical wave functions was established, through which we show that the resolution of the problem is reduced to solving an infinite, complex and large linear system. Second, we explain how to suitably truncate the last infinite dimensional system to get an accurate stable and fast numerical solution of the problem. Then, we evaluate numerically the theoretical solution of scattering problem by multiple ideal rigid spheres. Finally, we made a numerical study to present the "Head related transfer function" with respect to different physical and geometrical parameters of the problem.
Self-interaction correction in multiple scattering theory: application to transition metal oxides
Daene, Markus W; Lueders, Martin; Ernst, Arthur; Diemo, Koedderitzsch; Temmerman, Walter M; Szotek, Zdzislawa; Wolfam, Hergert
2009-01-01
We apply to transition metal monoxides the self-interaction corrected (SIC) local spin density (LSD) approximation, implemented locally in the multiple scattering theory within the Korringa-Kohn-Rostoker (KKR) band structure method. The calculated electronic structure and in particular magnetic moments and energy gaps are discussed in reference to the earlier SIC results obtained within the LMTO-ASA band structure method, involving transformations between Bloch and Wannier representations to solve the eigenvalue problem and calculate the SIC charge and potential. Since the KKR can be easily extended to treat disordered alloys, by invoking the coherent potential approximation (CPA), in this paper we compare the CPA approach and supercell calculations to study the electronic structure of NiO with cation vacancies.
NASA Technical Reports Server (NTRS)
Anderson, D. E., Jr.; Meier, R. R.; Hodges, R. R., Jr.; Tinsley, B. A.
1987-01-01
The H Balmer alpha nightglow is investigated by using Monte Carlo models of asymmetric geocoronal atomic hydrogen distributions as input to a radiative transfer model of solar Lyman-beta radiation in the thermosphere and atmosphere. It is shown that it is essential to include multiple scattering of Lyman-beta radiation in the interpretation of Balmer alpha airglow data. Observations of diurnal variation in the Balmer alpha airglow showing slightly greater intensities in the morning relative to evening are consistent with theory. No evidence is found for anything other than a single sinusoidal diurnal variation of exobase density. Dramatic changes in effective temperature derived from the observed Balmer alpha line profiles are expected on the basis of changing illumination conditions in the thermosphere and exosphere as different regions of the sky are scanned.
Multiple scattering in turbid media containing chiral components: A Monte Carlo simulation
NASA Astrophysics Data System (ADS)
Otsuki, Soichi
2017-01-01
A Monte Carlo simulation was performed for an infinite plane medium containing spherical particles as well as a chiral component. The optical activity shifts patterns in the two-dimensional map of the effective scattering Mueller matrix in the azimuthal direction. The reduced effective matrix obtained by the simulation approximately satisfies reciprocity in spite of the theoretical prediction. The pattern shifts are explained by the mixing of elements of the reduced effective Mueller matrix owing to multiplication of two rotation matrices. The reduced effective matrix was factorized using the Lu-Chipman polar decomposition affording the polarization components as a function of the distance. The functions as a retarding linear diattenuator of the medium decreases, whereas the optical rotation increases, as the distance increases. The estimated specific rotation on the medium surface is 1.6 times larger than the specific rotation in the medium used in the simulation.
NASA Technical Reports Server (NTRS)
Anderson, D. E., Jr.; Meier, R. R.; Hodges, R. R., Jr.; Tinsley, B. A.
1987-01-01
The H Balmer alpha nightglow is investigated by using Monte Carlo models of asymmetric geocoronal atomic hydrogen distributions as input to a radiative transfer model of solar Lyman-beta radiation in the thermosphere and atmosphere. It is shown that it is essential to include multiple scattering of Lyman-beta radiation in the interpretation of Balmer alpha airglow data. Observations of diurnal variation in the Balmer alpha airglow showing slightly greater intensities in the morning relative to evening are consistent with theory. No evidence is found for anything other than a single sinusoidal diurnal variation of exobase density. Dramatic changes in effective temperature derived from the observed Balmer alpha line profiles are expected on the basis of changing illumination conditions in the thermosphere and exosphere as different regions of the sky are scanned.
Santos, J; Calero, N; Trujillo-Cayado, L A; Garcia, M C; Muñoz, J
2017-08-14
This contribution deals with the study of the influence of surfactant ratio, namely triblock copolymer (Pluronic PE9400) to polyoxyethylene glycerol fatty acid ester (Levenol C201), on the stability of emulsions formulated with a mixture of two biosolvents (N,N Dimethyl Decanamide and D-limonene), which find applications as carriers of agrochemicals. Emulsions containing Pluronic, regardless of the concentration studied, underwent Ostwald ripening while coalescence controlled the destabilization process of emulsions containing Levenol C201 as the only emulsifier. The physical stability of the emulsions was analysed not only by means of mean diameters determined by laser diffraction but also with respect to their rheological properties and the so-called TSI parameter derived from multiple light scattering measurements with aging time. We propose that the different structures of both surfactants at the oil/water interface may be responsible for the occurrence of different destabilization mechanisms. It is likely that Copolymer Pluronic PE9400 formed multilayers in the emulsions studied, which may promote flocculation during processing and, subsequently, Ostwald ripening. In contrast, Levenol C201 probably formed a compact adsorbed layer with the molecules perpendicularly oriented to the interface. This work illustrates to what extent the combination of information provided by Multiple Light Scattering, rheology and laser diffraction enables the detection and monitoring of destabilization mechanisms such as Ostwald ripening and coalescence. In addition, this research highlights the importance of surfactant selection for the physical stability of emulsions that exhibited similar droplet size distributions just after preparation. Copyright © 2017 Elsevier B.V. All rights reserved.
Reichardt, Jens; Reichardt, Susanne
2006-04-20
A method is presented that permits the determination of the cloud effective particle size from Raman- or Rayleigh-integration temperature measurements that exploits the dependence of the multiple-scattering contributions to the lidar signals from heights above the cloud on the particle size of the cloud. Independent temperature information is needed for the determination of size. By use of Raman-integration temperatures, the technique is applied to cirrus measurements. The magnitude of the multiple-scattering effect and the above-cloud lidar signal strength limit the method's range of applicability to cirrus optical depths from 0.1 to 0.5. Our work implies that records of stratosphere temperature obtained with lidar may be affected by multiple scattering in clouds up to heights of 30 km and beyond.
NASA Astrophysics Data System (ADS)
Skipetrov, S. E.; Chesnokov, S. S.; Zakharov, S. D.; Kazaryan, M. A.; Korotkov, N. P.; Shcheglov, V. A.
1998-05-01
A self-consistent theoretical analysis is made of the multiple scattering of coherent laser radiation in a random medium under conditions of formation of a light-induced jet of scatterers. It is shown, that the laser particle acceleration leads to a qualitative change of the temporal auto-correlation function of scattered light as compared to the case of scattering on chaotically moving Brownian particles. The effect of radiation absorption on the temporal coherence of the multiple-scattered light under conditions of light-induced particle motion in the scattering medium is studied.
Berginc, G
2013-11-30
We have developed a general formalism based on Green's functions to calculate the coherent electromagnetic field scattered by a random medium with rough boundaries. The approximate expression derived makes it possible to determine the effective permittivity, which is generalised for a layer of an inhomogeneous random medium with different types of particles and bounded with randomly rough interfaces. This effective permittivity describes the coherent propagation of an electromagnetic wave in a random medium with randomly rough boundaries. We have obtained an expression, which contains the Maxwell – Garnett formula at the low-frequency limit, and the Keller formula; the latter has been proved to be in good agreement with experiments for particles whose dimensions are larger than a wavelength. (coherent light scattering)
NASA Astrophysics Data System (ADS)
Toft-Petersen, Rasmus; Groitl, Felix; Kure, Mathias; Lim, Joshua; Čermák, Petr; Alimov, Svyatoslav; Wilpert, Thomas; Le, Manh Duc; Quintero-Castro, Diana; Niedermayer, Christof; Schneidewind, Astrid; Habicht, Klaus
2016-09-01
A thorough experimental characterization of a multiplexing backend with multiple energy analysis on a cold-neutron triple axis spectrometer (cTAS) is presented. The prototype employs two angular segments (2 θ -segments) each containing five vertically scattering analyzers (energy channels), which simultaneously probe an energy transfer range of 2 meV at the corresponding two scattering angles. The feasibility and strength of such a vertically scattering multiple energy analysis setup is clearly demonstrated. It is shown, that the energy resolution near the elastic line is comparable to the energy resolution of a standard cTAS. The dispersion relation of the antiferromagnetic excitations in MnF2 has been mapped out by performing constant energy transfer maps. These results show that the tested setup is virtually spurion free. In addition, focusing effects due to (mis)matching of the instrumental resolution ellipsoid to the excitation branch are clearly evident.
NASA Technical Reports Server (NTRS)
Tsang, Leung; Chen, Zhengxiao; Oh, Seho; Marks, Robert J., II; Chang, A. T. C.
1992-01-01
Simultaneous inversion of the three parameters was performed which included mean-grain size of ice particles in snow, snow density, and snow temperatures from five brightness temperatures. Good results for the inversion of parameters were obtained using the neural network based on the simulated data computed from the dense media radiative transfer equation that takes into account the effects of multiple scattering.
NASA Technical Reports Server (NTRS)
Davis, Anthony B.; Winker, David M.
2011-01-01
Outline: (1) Signal Physics for Multiple-Scattering Cloud Lidar, (2) SNR Estimation (3) Cloud Property Retrievals (3a) several techniques (3b) application to Lidar-In-space Technology Experiment (LITE) data (3c) relation to O2 A-band
Prokudin, Alexey; Anselmino, Mauro; Boglione, Mariaelena; Melis, Stefano; Gonzalez, J. O.
2014-10-01
The unpolarised transverse momentum dependent distribution and fragmentation functions (TMDs) are extracted from HERMES and COMPASS experimental measurements of semi- inclusive deep inelastic scattering multiplicities for charged hadron production. A simple factorised functional form of the TMDs is adopted, with a Gaussian dependence on the intrinsic transverse momentum, which turns out to be quite adequate in shape.
Series solution for two-frequency Bragg interaction using the Korpel-Poon multiple-scattering model
NASA Astrophysics Data System (ADS)
Appel, R. K.; Somekh, M. G.
1993-03-01
Acoustooptic interactions are studied based on Korpel-Poon multiple scattering method. This method is used to derive an analytic solution for two frequency Bragg interaction. The present formulation was found to be more compact compared to that derived by Hecht. Solution is used to model a Bragg cell.
X-ray absorption spectroscopy of hemes and hemeproteins in solution: multiple scattering analysis.
D'Angelo, Paola; Lapi, Andrea; Migliorati, Valentina; Arcovito, Alessandro; Benfatto, Maurizio; Roscioni, Otello Maria; Meyer-Klaucke, Wolfram; Della-Longa, Stefano
2008-11-03
A full quantitative analysis of Fe K-edge X-ray absorption spectra has been performed for hemes in two porphynato complexes, that is, iron(III) tetraphenylporphyrin chloride (Fe(III)TPPCl) and iron(III) tetraphenylporphyrin bis(imidazole) (Fe(III)TPP(Imid)2), in two protein complexes whose X-ray structure is known at atomic resolution (1.0 A), that is, ferrous deoxy-myoglobin (Fe(II)Mb) and ferric aquo-myoglobin (Fe(III)MbH2O), and in ferric cyano-myoglobin (Fe(III)MbCN), whose X-ray structure is known at lower resolution (1.4 A). The analysis has been performed via the multiple scattering approach, starting from a muffin tin approximation of the molecular potential. The Fe-heme structure has been obtained by analyzing independently the Extended X-ray Absorption Fine Structure (EXAFS) region and the X-ray Absorption Near Edge Structure (XANES) region. The EXAFS structural results are in full agreement with the crystallographic values of the models, with an accuracy of +/- 0.02 A for Fe-ligand distances, and +/-6 degrees for angular parameters. All the XANES features above the theoretical zero energy (in the lower rising edge) are well accounted for by single-channel calculations, for both Fe(II) and Fe(III) hemes, and the Fe-N p distance is determined with the same accuracy as EXAFS. XANES evaluations of Fe-5th and Fe-6th ligand distances are determined with 0.04-0.07 A accuracy; a small discrepancy with EXAFS (0.01 to 0.05 A beyond the statistical error), is found for protein compounds. Concerns from statistical correlation among parameters and multiple minima in the parameter space are discussed. As expected, the XANES accuracy is slightly lower than what was found for polarized XANES on Fe(III)MbCN single crystal (0.03-0.04 A), and states the actual state-of-the-art of XANES analysis when used to extract heme-normal parameters in a solution spectrum dominated by heme-plane scattering.
Multiple-wavelength spectroscopic quantitation of light-absorbing species in scattering media
Nathel, Howard; Cartland, Harry E.; Colston, Jr., Billy W.; Everett, Matthew J.; Roe, Jeffery N.
2000-01-01
An oxygen concentration measurement system for blood hemoglobin comprises a multiple-wavelength low-coherence optical light source that is coupled by single mode fibers through a splitter and combiner and focused on both a target tissue sample and a reference mirror. Reflections from both the reference mirror and from the depths of the target tissue sample are carried back and mixed to produce interference fringes in the splitter and combiner. The reference mirror is set such that the distance traversed in the reference path is the same as the distance traversed into and back from the target tissue sample at some depth in the sample that will provide light attenuation information that is dependent on the oxygen in blood hemoglobin in the target tissue sample. Two wavelengths of light are used to obtain concentrations. The method can be used to measure total hemoglobin concentration [Hb.sub.deoxy +Hb.sub.oxy ] or total blood volume in tissue and in conjunction with oxygen saturation measurements from pulse oximetry can be used to absolutely quantify oxyhemoglobin [HbO.sub.2 ] in tissue. The apparatus and method provide a general means for absolute quantitation of an absorber dispersed in a highly scattering medium.
Effects of multiple scattering and surface albedo on the photochemistry of the troposphere
NASA Technical Reports Server (NTRS)
Augustsson, T. R.; Tiwari, S. N.
1981-01-01
The effect of treatment of incoming solar radiation on the photochemistry of the troposphere is discussed. A one dimensional photochemical model of the troposphere containing the species of the nitrogen, oxygen, carbon, hydrogen, and sulfur families was developed. The vertical flux is simulated by use of the parameterized eddy diffusion coefficients. The photochemical model is coupled to a radiative transfer model that calculates the radiation field due to the incoming solar radiation which initiates much of the photochemistry of the troposphere. Vertical profiles of tropospheric species were compared with the Leighton approximation, radiative transfer, matrix inversion model. The radiative transfer code includes the effects of multiple scattering due to molecules and aerosols, pure absorption, and surface albedo on the transfer of incoming solar radiation. It is indicated that significant differences exist for several key photolysis frequencies and species number density profiles between the Leighton approximation and the profiles generated with, radiative transfer, matrix inversion technique. Most species show enhanced vertical profiles when the more realistic treatment of the incoming solar radiation field is included
Band structures in a two-dimensional phononic crystal with rotational multiple scatterers
NASA Astrophysics Data System (ADS)
Song, Ailing; Wang, Xiaopeng; Chen, Tianning; Wan, Lele
2017-03-01
In this paper, the acoustic wave propagation in a two-dimensional phononic crystal composed of rotational multiple scatterers is investigated. The dispersion relationships, the transmission spectra and the acoustic modes are calculated by using finite element method. In contrast to the system composed of square tubes, there exist a low-frequency resonant bandgap and two wide Bragg bandgaps in the proposed structure, and the transmission spectra coincide with band structures. Specially, the first bandgap is based on locally resonant mechanism, and the simulation results agree well with the results of electrical circuit analogy. Additionally, increasing the rotation angle can remarkably influence the band structures due to the transfer of sound pressure between the internal and external cavities in low-order modes, and the redistribution of sound pressure in high-order modes. Wider bandgaps are obtained in arrays composed of finite unit cells with different rotation angles. The analysis results provide a good reference for tuning and obtaining wide bandgaps, and hence exploring the potential applications of the proposed phononic crystal in low-frequency noise insulation.
NASA Astrophysics Data System (ADS)
Berginc, G.
2013-11-01
We have developed a general formalism based on Green's functions to calculate the coherent electromagnetic field scattered by a random medium with rough boundaries. The approximate expression derived makes it possible to determine the effective permittivity, which is generalised for a layer of an inhomogeneous random medium with different types of particles and bounded with randomly rough interfaces. This effective permittivity describes the coherent propagation of an electromagnetic wave in a random medium with randomly rough boundaries. We have obtained an expression, which contains the Maxwell - Garnett formula at the low-frequency limit, and the Keller formula; the latter has been proved to be in good agreement with experiments for particles whose dimensions are larger than a wavelength.
NASA Astrophysics Data System (ADS)
Velten, Andreas
2017-05-01
Light scattering is a primary obstacle to optical imaging in a variety of different environments and across many size and time scales. Scattering complicates imaging on large scales when imaging through the atmosphere when imaging from airborne or space borne platforms, through marine fog, or through fog and dust in vehicle navigation, for example in self driving cars. On smaller scales, scattering is the major obstacle when imaging through human tissue in biomedical applications. Despite the large variety of participating materials and size scales, light transport in all these environments is usually described with very similar scattering models that are defined by the same small set of parameters, including scattering and absorption length and phase function. We attempt a study of scattering and methods of imaging through scattering across different scales and media, particularly with respect to the use of time of flight information. We can show that using time of flight, in addition to spatial information, provides distinct advantages in scattering environments. By performing a comparative study of scattering across scales and media, we are able to suggest scale models for scattering environments to aid lab research. We also can transfer knowledge and methodology between different fields.
NASA Astrophysics Data System (ADS)
Battaglia, A.; Tanelli, S.; Mroz, K.; Tridon, F.
2015-05-01
This paper illustrates how multiple scattering signatures affect Global Precipitation Measuring (GPM) Mission Dual-Frequency Precipitation Radar (DPR) Ku and Ka band reflectivity measurements and how they are consistent with prelaunch assessments based on theoretical considerations and confirmed by airborne observations. In particular, in the presence of deep convection, certain characteristics of the dual-wavelength reflectivity profiles cannot be explained with single scattering, whereas they are readily explained by multiple-scattering theory. Examples of such signatures are the absence of surface reflectivity peaks and anomalously small reflectivity slopes in the lower troposphere. These findings are relevant for DPR-based rainfall retrievals and stratiform/convective classification algorithms when dealing with deep convective regions. A path to refining the rainfall inversion problem is proposed by adopting a methodology based on a forward operator which accounts for multiple scattering. A retrieval algorithm based on this methodology is applied to a case study over Africa, and it is compared to the standard DPR products obtained with the at-launch version of the standard algorithms.
Battaglia, A; Tanelli, S; Mroz, K; Tridon, F
2015-05-16
This paper illustrates how multiple scattering signatures affect Global Precipitation Measuring (GPM) Mission Dual-Frequency Precipitation Radar (DPR) Ku and Ka band reflectivity measurements and how they are consistent with prelaunch assessments based on theoretical considerations and confirmed by airborne observations. In particular, in the presence of deep convection, certain characteristics of the dual-wavelength reflectivity profiles cannot be explained with single scattering, whereas they are readily explained by multiple-scattering theory. Examples of such signatures are the absence of surface reflectivity peaks and anomalously small reflectivity slopes in the lower troposphere. These findings are relevant for DPR-based rainfall retrievals and stratiform/convective classification algorithms when dealing with deep convective regions. A path to refining the rainfall inversion problem is proposed by adopting a methodology based on a forward operator which accounts for multiple scattering. A retrieval algorithm based on this methodology is applied to a case study over Africa, and it is compared to the standard DPR products obtained with the at-launch version of the standard algorithms.
NASA Astrophysics Data System (ADS)
Sha, Wei E. I.; Choy, Wallace C. H.; Liu, Yang G.; Cho Chew, Weng
2011-09-01
We investigate near-field multiple scattering effects of plasmonic nanospheres (NSPs) embedded into organic solar cells (OSCs). When NSPs are embedded into a spacer layer, the near-field scattering from the NSPs shows strong direction-dependent features, which significantly affects the optical absorption. When NSPs are embedded into an active layer, the absorption enhancement is attributed to the interplay between longitudinal and transverse modes supported by the NSP chain. The breakdown of electrostatic scaling law is confirmed by our theoretical model and should be accounted for optical designs of OSCs. The work provides the fundamental physical understanding and design guidelines for plasmonic photovoltaics.
NASA Astrophysics Data System (ADS)
Carlsson Tedgren, Åsa; Plamondon, Mathieu; Beaulieu, Luc
2015-07-01
The aim of this work was to investigate how dose distributions calculated with the collapsed cone (CC) algorithm depend on the size of the water phantom used in deriving the point kernel for multiple scatter. A research version of the CC algorithm equipped with a set of selectable point kernels for multiple-scatter dose that had initially been derived in water phantoms of various dimensions was used. The new point kernels were generated using EGSnrc in spherical water phantoms of radii 5 cm, 7.5 cm, 10 cm, 15 cm, 20 cm, 30 cm and 50 cm. Dose distributions derived with CC in water phantoms of different dimensions and in a CT-based clinical breast geometry were compared to Monte Carlo (MC) simulations using the Geant4-based brachytherapy specific MC code Algebra. Agreement with MC within 1% was obtained when the dimensions of the phantom used to derive the multiple-scatter kernel were similar to those of the calculation phantom. Doses are overestimated at phantom edges when kernels are derived in larger phantoms and underestimated when derived in smaller phantoms (by around 2% to 7% depending on distance from source and phantom dimensions). CC agrees well with MC in the high dose region of a breast implant and is superior to TG43 in determining skin doses for all multiple-scatter point kernel sizes. Increased agreement between CC and MC is achieved when the point kernel is comparable to breast dimensions. The investigated approximation in multiple scatter dose depends on the choice of point kernel in relation to phantom size and yields a significant fraction of the total dose only at distances of several centimeters from a source/implant which correspond to volumes of low doses. The current implementation of the CC algorithm utilizes a point kernel derived in a comparatively large (radius 20 cm) water phantom. A fixed point kernel leads to predictable behaviour of the algorithm with the worst case being a source/implant located well within a patient
Tedgren, Åsa Carlsson; Plamondon, Mathieu; Beaulieu, Luc
2015-07-07
The aim of this work was to investigate how dose distributions calculated with the collapsed cone (CC) algorithm depend on the size of the water phantom used in deriving the point kernel for multiple scatter. A research version of the CC algorithm equipped with a set of selectable point kernels for multiple-scatter dose that had initially been derived in water phantoms of various dimensions was used. The new point kernels were generated using EGSnrc in spherical water phantoms of radii 5 cm, 7.5 cm, 10 cm, 15 cm, 20 cm, 30 cm and 50 cm. Dose distributions derived with CC in water phantoms of different dimensions and in a CT-based clinical breast geometry were compared to Monte Carlo (MC) simulations using the Geant4-based brachytherapy specific MC code Algebra. Agreement with MC within 1% was obtained when the dimensions of the phantom used to derive the multiple-scatter kernel were similar to those of the calculation phantom. Doses are overestimated at phantom edges when kernels are derived in larger phantoms and underestimated when derived in smaller phantoms (by around 2% to 7% depending on distance from source and phantom dimensions). CC agrees well with MC in the high dose region of a breast implant and is superior to TG43 in determining skin doses for all multiple-scatter point kernel sizes. Increased agreement between CC and MC is achieved when the point kernel is comparable to breast dimensions. The investigated approximation in multiple scatter dose depends on the choice of point kernel in relation to phantom size and yields a significant fraction of the total dose only at distances of several centimeters from a source/implant which correspond to volumes of low doses. The current implementation of the CC algorithm utilizes a point kernel derived in a comparatively large (radius 20 cm) water phantom. A fixed point kernel leads to predictable behaviour of the algorithm with the worst case being a source/implant located well within a patient
Multiple Electromagnetic Scattering from a Cluster of Spheres. Volume I. Theory.
1981-09-01
Debye. P., Ann. Phys. 46, 809 (1915). 3. Kerker, M., Feone, W. A., and Matijevic , E. J. Opt. Soc. Am. 53, 758 (1963). 4i. Faone, W. A., Kerker, M...and Matijevic , E. Electromagnetic Scattering. M. Kerker, ed. Pergamon Press, Oxford. 1963. 5. Heller, W. Electromagnetic Scattering, M. Kerker, ad
Diez Muino, R.; Rolles, D.; Garcia de Abajo, F.J.; Fadley, C.S.; Van Hove, M.A.
2001-09-06
We use multiple scattering in non-spherical potentials (MSNSP) to calculate the angular distributions of electrons photoemitted from the 1s-shells of CO and N2 gas-phase molecules with fixed-in-space orientations. For low photoelectron kinetic energies (E<50 eV), as appropriate to certain shape-resonances, the electron scattering must be represented by non-spherical scattering potentials, which are naturally included in our formalism. Our calculations accurately reproduce the experimental angular patterns recently measured by several groups, including those at the shape-resonance energies. The MSNSP theory thus enhances the sensitivity to spatial electronic distribution and dynamics, paving the way toward their determination from experiment.
NASA Astrophysics Data System (ADS)
Darabi, Amir; Leamy, Michael J.
2017-08-01
Acoustoelastic wave energy harvesting in thin plates and other structures has recently gained attention from the energy harvesting research community. Metamaterial-inspired concepts for enhancing wave power generation have been investigated, including metamaterial funnels, mirrors, and defect-based resonators. In support of such concepts, this paper presents an electromechanically coupled, multiple scattering formulation for accurately modeling, exploring, and optimizing metamaterial-based harvesting systems incorporating scatterers (e.g., cylindrical inclusions and voids). Following development, the formulation is applied to determining optimal arrangements of scatterers, nominally in a semi-elliptical path, which maximize electrical power harvested, This is done, in part, by diminishing side lobes resulting from ellipse truncation. Optimization results exhibit minimized side lobes and harvester power nearly ten times that of the non-optimized case. Finally, an experimental study is presented which confirms many of the model predictions.
NASA Astrophysics Data System (ADS)
Chen, Duan; Cai, Wei; Zinser, Brian; Cho, Min Hyung
2016-09-01
In this paper, we develop an accurate and efficient Nyström volume integral equation (VIE) method for the Maxwell equations for a large number of 3-D scatterers. The Cauchy Principal Values that arise from the VIE are computed accurately using a finite size exclusion volume together with explicit correction integrals consisting of removable singularities. Also, the hyper-singular integrals are computed using interpolated quadrature formulae with tensor-product quadrature nodes for cubes, spheres and cylinders, that are frequently encountered in the design of meta-materials. The resulting Nyström VIE method is shown to have high accuracy with a small number of collocation points and demonstrates p-convergence for computing the electromagnetic scattering of these objects. Numerical calculations of multiple scatterers of cubic, spherical, and cylindrical shapes validate the efficiency and accuracy of the proposed method.
Malhotra, M.
1996-12-31
Finite-element discretizations of time-harmonic acoustic wave problems in exterior domains result in large sparse systems of linear equations with complex symmetric coefficient matrices. In many situations, these matrix problems need to be solved repeatedly for different right-hand sides, but with the same coefficient matrix. For instance, multiple right-hand sides arise in radiation problems due to multiple load cases, and also in scattering problems when multiple angles of incidence of an incoming plane wave need to be considered. In this talk, we discuss the iterative solution of multiple linear systems arising in radiation and scattering problems in structural acoustics by means of a complex symmetric variant of the BL-QMR method. First, we summarize the governing partial differential equations for time-harmonic structural acoustics, the finite-element discretization of these equations, and the resulting complex symmetric matrix problem. Next, we sketch the special version of BL-QMR method that exploits complex symmetry, and we describe the preconditioners we have used in conjunction with BL-QMR. Finally, we report some typical results of our extensive numerical tests to illustrate the typical convergence behavior of BL-QMR method for multiple radiation and scattering problems in structural acoustics, to identify appropriate preconditioners for these problems, and to demonstrate the importance of deflation in block Krylov-subspace methods. Our numerical results show that the multiple systems arising in structural acoustics can be solved very efficiently with the preconditioned BL-QMR method. In fact, for multiple systems with up to 40 and more different right-hand sides we get consistent and significant speed-ups over solving the systems individually.
Propagator and multiple scattering approach to the time of arrival problem
NASA Astrophysics Data System (ADS)
Los, Victor F.; Los, Andrei V.
2011-05-01
The propagator approach combined with the multiple-scattering theory is applied to the particle time of arrival (TOA) problem. This approach allows us to naturally include in the consideration the components of the particle initial wavefunction (defined at t = t0) corresponding to the positive (forward-moving term) and negative (backward-moving term) momenta. For a freely moving particle it is shown that the Allcock definition of the ideal total TOA probability disregards the backward-moving and interference terms entirely. In the presence of a measuring apparatus modeled by an imaginary step potential with the amplitude V0, the general expression for the TOA rate is obtained, the forward-moving component of which coincides with that obtained by Allcock. It is shown that when the initial particle wavefunction is well separated from the point of arrival and has a well-defined average momentum, the contribution of the backward-moving and interference terms are small and can be neglected. For a small V0, except the well-known convolution result by Allcock-Kijowski, the exponential form of the TOA rate follows at the double limit condition V0 → 0, t - t0 ~ planck/2V0 → ∞ (2V0(t - t0)/planck is finite) while the backward-moving and interference terms vanish. We show that the Allcock result for the TOA rate is valid in the entire range of V0 including the Zeno case (V0 → ∞) and the normalized TOA rate can be introduced for all values of V0 as a probability distribution. The latter is illustrated for the Gaussian wave packet.
NASA Astrophysics Data System (ADS)
Tauzin, B.; Trampert, J.; van der Hilst, R.; Wittlinger, G.; Vergne, J.
2011-12-01
Using data from the US Transportable Array, we combine observations of P-to-S single and multiple scattered waves to constrain the transition zone (TZ) structure beneath the Western US. From stacking the data by common conversion points along profiles, we produce depth images of seismic discontinuities. Systematic depth and amplitude measurements are performed for the '410', the '660', and some other minor seismic discontinuities identified as sharp reductions of wave velocities at ˜350 km depth (the '350') and ˜590 km depth (the '590'). The Gorda plate, subducted under Northern California, is traced back to the TZ where it seems to flatten and induces, due to cold temperatures or a high water content, a significant uplift of the '410' under Northern Nevada. The geographical maps of the '410'/'660' amplitude/topography reveal an anomalous TZ at the borders between Washington, Oregon and Idaho with: (i) a thickened TZ, (ii) a sharp jump in the topography of the '660' both in a South-North and West-East direction, and (iii) reduced '410' amplitudes at the North. Such anomalous structure might be inherited from the past history of plate subduction/accretion. A thinned TZ under the Yellowstone is likely the result of a deep hot thermal plume. Both the '350' and the '590' negative discontinuities extend over very large areas. They might be related either to an increased water content in the TZ and/or significant amount of oceanic material accumulated through the past 100 My. An estimation of the TZ water content is now possible based on observation of PPS reverberated phases on the '410' and '660' interfaces.
Local ordering of nanostructured Pt probed by multiple-scattering XAFS
Witkowska, Agnieszka; Di Cicco, Andrea; Principi, Emiliano
2007-09-01
We present detailed results of a multiple-scattering (MS) extended x-ray absorption fine structure (EXAFS) data analysis of crystalline and nanocrystalline platinum. Advanced MS EXAFS analysis has been applied to raw x-ray absorption data including the background, using the expansion of the absorption cross section in terms of local two-body and three-body configurations. Present EXAFS results on bulk Pt are found to be in agreement with previous structural and vibrational data, and has been used as a reference for reliable structural refinement of nanosized systems. EXAFS structural refinement of Pt nanoparticles has been performed in combination with electron microscopy and x-ray diffraction, showing the importance of considering the actual size distribution and morphology of the samples. Present samples were unsupported and supported Pt nanocrystalline systems with size distributions showing clusters of quasispherical shape in the 1-7 nm range. In particular, EXAFS spectra have been analyzed accounting for the reduction of the coordination number and degeneracy of three-body configurations, resulting from the measured size distribution and expected surface atom contributions. The importance of a correct account of the reduction of the number of neighbors for calculating MS contributions is emphasized in the paper. EXAFS results have been found compatible with x-ray diffraction and transmission electron microscopy investigations. We estimate that EXAFS could be used to study cluster shapes only for sizes below 2 nm using present methods and quality of the experimental data. We have also shown that the local distribution of distances and angles probed by EXAFS is broader than in bulk Pt, with first-neighbor bond length variance and asymmetry increasing upon reducing the particle size. Methods and results presented in this paper have been found to be successful for a robust structural refinement of monatomic nanocrystalline systems and represents a solid starting
Wang, L; Jette, D
1999-08-01
The transport of the secondary electrons resulting from high-energy photon interactions is essential to energy redistribution and deposition. In order to develop an accurate dose-calculation algorithm for high-energy photons, which can predict the dose distribution in inhomogeneous media and at the beam edges, we have investigated the feasibility of applying electron transport theory [Jette, Med. Phys. 15, 123 (1988)] to photon dose calculation. In particular, the transport of and energy deposition by Compton electron and electrons and positrons resulting from pair production were studied. The primary photons are treated as the source of the secondary electrons and positrons, which are transported through the irradiated medium using Gaussian multiple-scattering theory [Jette, Med. Phys. 15, 123 (1988)]. The initial angular and kinetic energy distribution(s) of the secondary electrons (and positrons) emanating from the photon interactions are incorporated into the transport. Due to different mechanisms of creation and cross-section functions, the transport of and the energy deposition by the electrons released in these two processes are studied and modeled separately based on first principles. In this article, we focus on determining the dose distribution for an individual interaction site. We define the Compton dose deposition kernel (CDK) or the pair-production dose deposition kernel (PDK) as the dose distribution relative to the point of interaction, per unit interaction density, for a monoenergetic photon beam in an infinite homogeneous medium of unit density. The validity of this analytic modeling of dose deposition was evaluated through EGS4 Monte Carlo simulation. Quantitative agreement between these two calculations of the dose distribution and the average energy deposited per interaction was achieved. Our results demonstrate the applicability of the electron dose-calculation method to photon dose calculation.
Kaina, Nadège; Lemoult, Fabrice; Fink, Mathias; Lerosey, Geoffroy
2015-09-03
Metamaterials, man-made composite media structured on a scale much smaller than a wavelength, offer surprising possibilities for engineering the propagation of waves. One of the most interesting of these is the ability to achieve superlensing--that is, to focus or image beyond the diffraction limit. This originates from the left-handed behavior--the property of refracting waves negatively--that is typical of negative index metamaterials. Yet reaching this goal requires the design of 'double negative' metamaterials, which act simultaneously on the permittivity and permeability in electromagnetics, or on the density and compressibility in acoustics; this generally implies the use of two different kinds of building blocks or specific particles presenting multiple overlapping resonances. Such a requirement limits the applicability of double negative metamaterials, and has, for example, hampered any demonstration of subwavelength focusing using left-handed acoustic metamaterials. Here we show that these strict conditions can be largely relaxed by relying on media that consist of only one type of single resonant unit cell. Specifically, we show with a simple yet general semi-analytical model that judiciously breaking the symmetry of a single negative metamaterial is sufficient to turn it into a double negative one. We then demonstrate that this occurs solely because of multiple scattering of waves off the metamaterial resonant elements, a phenomenon often disregarded in these media owing to their subwavelength patterning. We apply our approach to acoustics and verify through numerical simulations that it allows the realization of negative index acoustic metamaterials based on Helmholtz resonators only. Finally, we demonstrate the operation of a negative index acoustic superlens, achieving subwavelength focusing and imaging with spot width and resolution 7 and 3.5 times better than the diffraction limit, respectively. Our findings have profound implications for the
Shahjahan, S; Rupin, F; Aubry, A; Chassignole, B; Fouquet, T; Derode, A
2014-01-01
Ultrasonic non-destructive testing of polycrystalline structures can be disturbed by scattering at grain boundaries. Understanding and modeling this so-called "structural noise" is crucial for characterization as well as detection purposes. Structural noise can be considered as a fingerprint of the material under investigation, since it contains information about its microstructure. The interpretation of experimental data necessitates an accurate comprehension of complex phenomena that occur in multiple scattering media and thus robust scattering models. In particular, numerical models can offer the opportunity to realize parametrical studies on controlled microstructures. However, the ability of the model to simulate wave propagation in complex media must be validated. In that perspective, the main objective of the present work is to evaluate the ability of the finite-element code ATHENA 2D to reproduce typical features of multiple wave scattering in the context of ultrasonic non-destructive evaluation, with an array of sources and receivers. Experiments were carried out with a 64-element array, around 2 MHz. The sample was a mock-up of Inconel600 exhibiting a coarse grain structure with a known grain size distribution. The numerical model of this microstructure is based on Voronoi diagrams. Two physical parameters were used to compare numerical and experimental data: the coherent backscattering peak, and the singular value distribution of the array response matrix. Though the simulations are 2-D, a good agreement was found between simulated and experimental data. Copyright © 2013 Elsevier B.V. All rights reserved.
NASA Astrophysics Data System (ADS)
Viard, Nicolas; Gianmarinaro, Bruno; Derode, Arnaud; Barrière, Christophe
2014-04-01
Whereas multiple scattering and shock wave formation are known to be antagonistic phenomena, this work concentrates on the interaction of an ultrasonic shock wave with a random multiple scattering medium. The shock wave is generated by long distance propagation of a short pulse (4 periods at a 3.5 MHz central frequency) in water before it encounters the scattering medium (a slab-shaped random set of parallel metallic rods). Transmitted waves are recorded over hundreds of positions along the lateral dimension of the slab to estimate the ensemble-averaged transmitted field langlephi(t)rangle, also known as the coherent wave. Experiments are repeated for different thicknesses L of the slab and different emission amplitudes. The elastic mean free path le (i.e the typical distance for the decreasing of the coherent intensity |langlephi(t)rangle|2 due to scattering) is determined as well as the harmonic rate of the averaged transmitted wave. Experimental results are discussed and compared to the linear case.
NASA Astrophysics Data System (ADS)
Benedito, E.; Fernández-Varea, J. M.; Salvat, F.
2001-03-01
We describe an algorithm for mixed (class II) simulation of electron multiple elastic scattering using numerical differential cross-sections (DCS), which is applicable in a wide energy range, from ˜100 eV to ˜1 GeV. DCSs are calculated by partial-wave analysis, or from a suitable high-energy approximation, and tabulated on a grid of scattering angles and electron energies. The size of the required DCS table is substantially reduced by means of a change of variable that absorbs most of the energy dependence of the DCS. That is, the scattering angle θ is replaced by a variable u, whose probability distribution function varies smoothly with the kinetic energy of the electron. A fast procedure to generate random values of u in restricted intervals is described. The algorithm for the simulation of electron transport in pure elastic scattering media (with energy-loss processes switched off) is obtained by combining this sampling procedure with a simple model for space displacements. The accuracy and stability of this algorithm is demonstrated by comparing results with those from detailed, event by event, simulations using the same DCSs. A complete transport code, including energy losses and the production of secondary radiations, is obtained by coupling the present elastic scattering simulation algorithm to the general-purpose Monte Carlo program PENELOPE. Simulated angular distributions of MeV electrons backscattered in aluminium and gold are in good agreement with experimental data.
Muon momentum measurement in ICARUS-T600 LAr-TPC via multiple scattering in few-GeV range
NASA Astrophysics Data System (ADS)
Antonello, M.; Baibussinov, B.; Bellini, V.; Benetti, P.; Boffelli, F.; Bubak, A.; Calligarich, E.; Centro, S.; Cervi, T.; Cesana, A.; Cieslik, K.; Cocco, A. G.; Dabrowska, A.; Dermenev, A.; Falcone, A.; Farnese, C.; Fava, A.; Ferrari, A.; Gibin, D.; Gninenko, S.; Guglielmi, A.; Haranczyk, M.; Holeczek, J.; Janik, M.; Kirsanov, M.; Kisiel, J.; Kochanek, I.; Lagoda, J.; Menegolli, A.; Meng, G.; Montanari, C.; Otwinowski, S.; Picchi, P.; Pietropaolo, F.; Plonski, P.; Rappoldi, A.; Raselli, G. L.; Rossella, M.; Rubbia, C.; Sala, P.; Scaramelli, A.; Sergiampietri, F.; Spanu, M.; Stefan, D.; Sulej, R.; Szarska, M.; Terrani, M.; Torti, M.; Tortorici, F.; Varanini, F.; Ventura, S.; Vignoli, C.; Wang, H.; Yang, X.; Zalewska, A.; Zani, A.; Zaremba, K.
2017-04-01
The measurement of muon momentum by Multiple Coulomb Scattering is a crucial ingredient to the reconstruction of νμ CC events in the ICARUS-T600 liquid argon TPC in absence of magnetic field, as in the search for sterile neutrinos at Fermilab where ICARUS will be exposed to ~ 1 GeV Booster neutrino beam. A sample of ~ 1000 stopping muons produced by charged current interactions of CNGS νμ in the surrounding rock at the INFN Gran Sasso underground Laboratory provides an ideal benchmark in the few-GeV range since their momentum can be directly and independently obtained by the calorimetric measurement. Stopping muon momentum in the 0.5-4.5 GeV/c range has been reconstructed via Multiple Coulomb Scattering with resolution ranging from 10 to 25% depending on muon energy, track length and uniformity of the electric field in the drift volume.
Ushiro, Mayuko; Ohminami, Kenryo; Nagamatsu, Shin-ichi; Fujikawa, Takashi; Asakura, Kiyotaka
2007-02-02
Residual Ni species after Ni removal treatment of carbon nanofibers have been investigated by use of XAFS analyses. Most of the Ni impurities are in Ni monomer which is located on defects in carbon nanofibers. The XAFS analyses combined with the multiple scattering theory give useful information on nano-structures of small amount species. Molecular orbital calculation also support the results from the XAFS analyses.
Haworth, Kevin J.; Fowlkes, J. Brian; Carson, Paul L.; Kripfgans, Oliver D.
2009-01-01
A theoretical shot noise model to describe the output of a time-reversal experiment in a multiple-scattering medium is developed. This (non-wave equation based) model describes the following process. An arbitrary waveform is transmitted through a high-order multiple-scattering environment and recorded. The recorded signal is arbitrarily windowed and then time-reversed. The processed signal is retransmitted into the environment and the resulting signal recorded. The temporal and spatial signal and noise of this process is predicted statistically. It is found that the time when the noise is largest depends on the arbitrary windowing and this noise peak can occur at times outside the main lobe. To determine further trends, a common set of parameters is applied to the general result. It is seen that as the duration of the input function increases, the signal-to-noise ratio (SNR) decreases (independent of signal bandwidth). It is also seen that longer persisting impulse responses result in increased main lobe amplitudes and SNR. Assumptions underpinning the generalized shot noise model are compared to an experimental realization of a multiple-scattering medium (a time-reversal chaotic cavity). Results from the model are compared to random number numerical simulation. PMID:19425655
Electromagnetic Scattering by Multiple Cavities Embedded in the Infinite 2D Ground Plane
2014-07-01
numerical quadratures. C. Numerical examples The physical parameter of interest is the Radar Cross Section (RCS), which is defined by: .|)(|4 2...structure and an incident wave, the scattering problem is to predict the electromagnetic field scattered by the cavity . It has been extensively...Prescribed by ANSI Std Z39-18 The paper is outlined as follows. In Section 2, a mathematical model for the single cavity problem is introduced, the
NASA Astrophysics Data System (ADS)
Matson, Kenneth Howell
A method exists for marine seismic data which removes all orders of free surface multiples and suppresses all orders of internal multiples while leaving primaries intact. This method is based on the inverse scattering series and makes no assumptions about the subsurface earth model. The marine algorithm assumes that the sources and receivers are located in the water column. In the context of land and ocean bottom data, the sources and receivers are located on or in an elastic medium. This opens up the possibility of recording multicomponent seismic data. Because both compressional (P) and shear (S) primaries are recorded in multicomponent data, it has the potential for providing a more complete picture of the subsurface. Coupled with the benefits of the P and S primaries are a complex set of elastic free surface and internal multiples. In this thesis, I develop an inverse scattering series method to attenuate these elastic multiples from multicomponent land and ocean bottom data. For land data, this method removes elastic free surface multiples. For ocean bottom data, multiples associated with the top and bottom of the water column are removed. Internal multiples are strongly attenuated for both data types. In common with the marine formulation, this method makes no assumptions about the earth below the sources and receivers, and does not affect primaries. The latter property is important for amplitude variation with offset analysis (AVO). The theory for multiple attentuation requires four component (two source, two receiver) data, a known near surface or water bottom, near offsets, and a known source wavelet. Tests on synthetic data indicate that this method is still effective using data with less than four components and is robust with respect to errors in estimating the near surface or ocean bottom properties.
NASA Astrophysics Data System (ADS)
Chen, Y.; García de Abajo, F. J.; Chassé, A.; Ynzunza, R. X.; Kaduwela, A. P.; van Hove, M. A.; Fadley, C. S.
1998-11-01
The Rehr-Albers (RA) separable Green's-function formalism, which is based on an expansion series, has been successful in speeding up multiple-scattering cluster calculations for photoelectron diffraction simulations, particularly in its second-order version. The performance of this formalism is explored here in terms of computational speed, convergence over orders of multiple scattering, over orders of approximation, and over cluster size, by comparison with exact cluster-based formalisms. It is found that the second-order RA approximation [characterized by (6×6) scattering matrices] is adequate for many situations, particularly if the initial state from which photoemission occurs is of s or p type. For the most general and quantitative applications, higher-order versions of RA may become necessary for d initial states [third-order, i.e., (10×10) matrices] and f initial states [fourth-order, i.e., (15×15) matrices]. However, the required RA order decreases as an electron wave proceeds along a multiple-scattering path, and this can be exploited, together with the selective and automated cutoff of weakly contributing matrix elements and paths, to yield computer time savings of at least an order of magnitude with no significant loss of accuracy. Cluster sizes of up to approximately 100 atoms should be sufficient for most problems that require about 5% accuracy in diffracted intensities. Excellent sensitivity to structure is seen in comparisons of second-order theory with variable geometry to exact theory as a fictitious ``experiment.'' Our implementation of the Rehr-Albers formalism thus represents a versatile, quantitative, and efficient method for the accurate simulation of photoelectron diffraction.
Chen, Y.; Garcia de Abajo, F.J.; Ynzunza, R.X.; Kaduwela, A.P.; Van Hove, M.A.; Fadley, C.S. |
1998-11-01
The Rehr-Albers (RA) separable Green{close_quote}s-function formalism, which is based on an expansion series, has been successful in speeding up multiple-scattering cluster calculations for photoelectron diffraction simulations, particularly in its second-order version. The performance of this formalism is explored here in terms of computational speed, convergence over orders of multiple scattering, over orders of approximation, and over cluster size, by comparison with exact cluster-based formalisms. It is found that the second-order RA approximation [characterized by (6{times}6) scattering matrices] is adequate for many situations, particularly if the initial state from which photoemission occurs is of {ital s} or {ital p} type. For the most general and quantitative applications, higher-order versions of RA may become necessary for {ital d} initial states [third-order, i.e., (10{times}10) matrices] and {ital f} initial states [fourth-order, i.e., (15{times}15) matrices]. However, the required RA order decreases as an electron wave proceeds along a multiple-scattering path, and this can be exploited, together with the selective and automated cutoff of weakly contributing matrix elements and paths, to yield computer time savings of at least an order of magnitude with no significant loss of accuracy. Cluster sizes of up to approximately 100 atoms should be sufficient for most problems that require about 5{percent} accuracy in diffracted intensities. Excellent sensitivity to structure is seen in comparisons of second-order theory with variable geometry to exact theory as a fictitious {open_quotes}experiment.{close_quotes} Our implementation of the Rehr-Albers formalism thus represents a versatile, quantitative, and efficient method for the accurate simulation of photoelectron diffraction. {copyright} {ital 1998} {ital The American Physical Society}
NASA Astrophysics Data System (ADS)
Hirst, Evan; Thompson, Oliver; Andrews, Mike
2013-02-01
The retina/choroid structure is an example of a complex biological target featuring highly perfused tissues and vessel flows both near the surface and at some depth. Laser speckle imaging can be used to image blood flows but static scattering paths present a problem for extracting quantifiable data. The speckle contrast is artificially increased by any residual specular reflection and light paths where no moving scatterers are encountered. Here we present results from phantom experiments demonstrating that the static and dynamic contributions to laser speckle contrast can be separated when camera exposures of varying duration are used. The stationary contrast parameter follows the thickness and strength of the overlying scatterer while the dynamic proportion of the scatter resulting from vessel flows and Brownian motion is unchanged. The importance of separating the two scatter components is illustrated by in vivo measurements from a scarred human retina, where the effect of the un-perfused scar tissue can be decoupled from the dynamic speckle from the intact tissue beneath it.
Solving protein nanocrystals by cryo-EM diffraction: multiple scattering artifacts.
Subramanian, Ganesh; Basu, Shibom; Liu, Haiguang; Zuo, Jian-Min; Spence, John C H
2015-01-01
The maximum thickness permissible within the single-scattering approximation for the determination of the structure of perfectly ordered protein microcrystals by transmission electron diffraction is estimated for tetragonal hen-egg lysozyme protein crystals using several approaches. Multislice simulations are performed for many diffraction conditions and beam energies to determine the validity domain of the required single-scattering approximation and hence the limit on crystal thickness. The effects of erroneous experimental structure factor amplitudes on the charge density map for lysozyme are noted and their threshold limits calculated. The maximum thickness of lysozyme permissible under the single-scattering approximation is also estimated using R-factor analysis. Successful reconstruction of density maps is found to result mainly from the use of the phase information provided by modeling based on the protein data base through molecular replacement (MR), which dominates the effect of poor quality electron diffraction data at thicknesses larger than about 200 Å. For perfectly ordered protein nanocrystals, a maximum thickness of about 1000 Å is predicted at 200 keV if MR can be used, using R-factor analysis performed over a subset of the simulated diffracted beams. The effects of crystal bending, mosaicity (which has recently been directly imaged by cryo-EM) and secondary scattering are discussed. Structure-independent tests for single-scattering and new microfluidic methods for growing and sorting nanocrystals by size are reviewed.
NASA Technical Reports Server (NTRS)
Kobayashi, Satoru; Tanelli, Simone; Im, Eastwood
2005-01-01
Effects of multiple scattering on reflectivity are studied for millimeter wavelength weather radars. A time-independent vector theory, including up to second-order scattering, is derived for a single layer of hydrometeors of a uniform density and a uniform diameter. In this theory, spherical waves with a Gaussian antenna pattern are used to calculate ladder and cross terms in the analytical scattering theory. The former terms represent the conventional multiple scattering, while the latter terms cause backscattering enhancement in both the copolarized and cross-polarized components. As the optical thickness of the hydrometeor layer increases, the differences from the conventional plane wave theory become more significant, and essentially, the reflectivity of multiple scattering depends on the ratio of mean free path to radar footprint radius. These results must be taken into account when analyzing radar reflectivity for use in remote sensing.
NASA Technical Reports Server (NTRS)
Kobayashi, Satoru; Tanelli, Simone; Im, Eastwood
2005-01-01
Effects of multiple scattering on reflectivity are studied for millimeter wavelength weather radars. A time-independent vector theory, including up to second-order scattering, is derived for a single layer of hydrometeors of a uniform density and a uniform diameter. In this theory, spherical waves with a Gaussian antenna pattern are used to calculate ladder and cross terms in the analytical scattering theory. The former terms represent the conventional multiple scattering, while the latter terms cause backscattering enhancement in both the copolarized and cross-polarized components. As the optical thickness of the hydrometeor layer increases, the differences from the conventional plane wave theory become more significant, and essentially, the reflectivity of multiple scattering depends on the ratio of mean free path to radar footprint radius. These results must be taken into account when analyzing radar reflectivity for use in remote sensing.
Wang, Ruikang K
2002-07-07
Multiple scattering is a major source that limits light penetration into biotissues, thereby preventing visualization of the deep microstructures for high-resolution optical imaging techniques. The optical clearing approach is a new adventure in biomedical optics for manipulating the optical properties of tissue; for example, the scattering coefficient and the degree of forward scattering of photons, by the use of the chemical administration method in order to improve the optical imaging depth, particularly for the recently developed optical coherence tomography (OCT). This paper investigates systematically how the multiple scattering affects signal attenuation and localization in general, and how the alterations of optical properties of tissue enhance the optical imaging depth and signal localization in particular, by the use of Monte Carlo simulations through the separate considerations of the least scattered photons (LSP) and multiple scattered photons (MSP). The LSP are those photons that contribute to the precise OCT signal, i.e. localization, and the MSP are those that degrade the OCT signal. It is shown that with either the reduction of the scattering coefficient or the increase of the degree of forward scattering, signal localization and imaging depth for OCT is enhanced. Whilst the increase of the anisotropic factor of the medium is more efficient in improving signal localization, it introduces more scattering events for the photons travelling within the tissue for both the LSP and MSP. It is also found that the OCT imaging resolution is almost reduced exponentially with the increase of the probing depth as opposed to the claimed system resolution. We demonstrate that optical clearing could be a useful tool to improve the imaging resolution when the light progressively penetrates the high scattering medium. Experimental results are also presented to show intuitively how multiple scattering affects OCT signal profiles by the use of intralipid solution and
NASA Technical Reports Server (NTRS)
Mahesh, Ashwin; Spinhirne, James D.; Duda, David P.; Eloranta, Edwin W.; Starr, David O'C (Technical Monitor)
2001-01-01
The altimetry bias in GLAS (Geoscience Laser Altimeter System) or other laser altimeters resulting from atmospheric multiple scattering is studied in relationship to current knowledge of cloud properties over the Antarctic Plateau. Estimates of seasonal and interannual changes in the bias are presented. Results show the bias in altitude from multiple scattering in clouds would be a significant error source without correction. The selective use of low optical depth clouds or cloudfree observations, as well as improved analysis of the return pulse such as by the Gaussian method used here, are necessary to minimize the surface altitude errors. The magnitude of the bias is affected by variations in cloud height, cloud effective particle size and optical depth. Interannual variations in these properties as well as in cloud cover fraction could lead to significant year-to-year variations in the altitude bias. Although cloud-free observations reduce biases in surface elevation measurements from space, over Antarctica these may often include near-surface blowing snow, also a source of scattering-induced delay. With careful selection and analysis of data, laser altimetry specifications can be met.
Multiple scattering of light by the surfaces of small Solar System objects
NASA Astrophysics Data System (ADS)
Muinonen, K.; Penttilä, A.; Wilkman, O.; Videen, G.
2014-07-01
Scattering of electromagnetic waves in a macroscopic particulate medium composed of microscopic particles constitutes an open computational problem in planetary astrophysics. This problem manifests itself in the absence of inverse methods to address fundamental astronomical observations of small Solar System objects. There are two ubiquitous phenomena observed at small solar phase angles (the Sun-Object-Observer angle) from, for example, asteroids and transneptunian objects. First, a nonlinear increase of brightness is observed toward the zero phase angle in the magnitude scale that is commonly called the opposition effect. Second, the scattered light is observed to be partially linearly polarized parallel to the Sun-Object-Observer plane that is commonly called the negative polarization surge. The aforedescribed polarimetric and photometric observations of small Solar System objects are interpreted using a radiative-transfer coherent-backscattering model (RT-CB, Muinonen 2004) that makes use of a so-called phenomenological fundamental single scatterer (Muinonen and Videen 2012). For the validity of RT-CB, see Muinonen et al. (2012, 2013). The modeling allows us to constrain the single-scattering albedo, phase function, and polarization characteristics as well as the mean free path length between successive scatterings. With the help of laboratory experiments (Muñoz et al. and Peltoniemi et al., present meeting) and exact theoretical methods (e.g., Markkanen et al., present meeting), it further allows us to put constraints on the size, shape, and refractive index of the fundamental scatterers. We illustrate the application of RT-CB by interpreting the polarimetric and photometric observations of the C, M, S, and E-class asteroids.
NASA Astrophysics Data System (ADS)
Neuville, C.; Tassin, V.; Pesme, D.; Monteil, M.-C.; Masson-Laborde, P.-E.; Baccou, C.; Fremerye, P.; Philippe, F.; Seytor, P.; Teychenné, D.; Seka, W.; Katz, J.; Bahr, R.; Depierreux, S.
2016-06-01
The indirect-drive scheme to inertial confinement fusion uses a large number of laser beams arranged in a symmetric angular distribution. Collective laser plasma instabilities can therefore develop that couple all the incident laser waves located in a cone to the daughter wave growing along the cone symmetry axis [D. F. DuBois et al., Phys. Fluids B 4, 241 (1992)]. With complementary diagnostics of Thomson scattering and of the scattered light, we demonstrate the occurrence of collective stimulated Brillouin sidescattering driving collective acoustic waves in indirect-drive experiments.
NASA Astrophysics Data System (ADS)
Frosini, Mikael; Bernard, Denis
2017-09-01
We revisit the precision of the measurement of track parameters (position, angle) with optimal methods in the presence of detector resolution, multiple scattering and zero magnetic field. We then obtain an optimal estimator of the track momentum by a Bayesian analysis of the filtering innovations of a series of Kalman filters applied to the track. This work could pave the way to the development of autonomous high-performance gas time-projection chambers (TPC) or silicon wafer γ-ray space telescopes and be a powerful guide in the optimization of the design of the multi-kilo-ton liquid argon TPCs that are under development for neutrino studies.
Assessing multiple quality attributes of peaches using spectral absorption and scattering properties
USDA-ARS?s Scientific Manuscript database
The objective of this research was to measure the spectral absorption and reduced scattering coefficients of peaches, using a hyperspectral imaging-based spatially-resolved method, for maturity/quality assessment. A newly developed optical property measuring instrument was used for acquiring hypersp...
Lu, Xiaomei; Jiang, Yuesong; Zhang, Xuguo; Lu, Xiaoxia; He, Yuntao
2009-05-25
A new method is proposed to analyze the effects of multiple scattering on simultaneously detected lidar returns for ground-based and space-borne lidars, and it is applied to a Monte Carlo-based simulation to test the feasibility of the new method. The experimental evidence of multiple scattering influences on both ground-based and space-borne lidar returns is presented. Monte Carlo-based evaluations of the multiple scattering parameters for the counter-looking lidar returns are separately obtained in order to correct the effective values of backscattering and extinction coefficients. Results show that for the typical cirrus cloud, the presence of the multiple scattering can lead to an underestimation of the extinction coefficient by as large as 70%, and the backscattering coefficient is overestimated by nearly 10%, which are retrieved by the Counter-propagating Elastic Signals Combination (CESC) technique in which the multiple scattering influences are neglected. Nevertheless, by the new method in which the multiple scattering effects are considered differently for the ground-based and space-borne lidar returns the extinction and backscattering coefficients can be more accurately obtained.
Brancewicz, Marek; Itou, Masayoshi; Sakurai, Yoshiharu
2016-01-01
The first results of multiple scattering simulations of polarized high-energy X-rays for Compton experiments using a new Monte Carlo program, MUSCAT, are presented. The program is developed to follow the restrictions of real experimental geometries. The new simulation algorithm uses not only well known photon splitting and interaction forcing methods but it is also upgraded with the new propagation separation method and highly vectorized. In this paper, a detailed description of the new simulation algorithm is given. The code is verified by comparison with the previous experimental and simulation results by the ESRF group and new restricted geometry experiments carried out at SPring-8.
NASA Astrophysics Data System (ADS)
Wang, Lu-Yao
2006-03-01
We consider a Rashba-type quantum channel (RQC) consisting of one AC-biased finger-gates (FG) that orient perpendicularly and located above the RQC. Such an AC-biased FG gives rise to a local time-modulation in the Rashba coupling parameter, and generates a dc spin current (SC). A static potential is located inside or outside the FG in the RQC and the backscattering effect is studied. We use analytical time-dependent multiple scattering approach to treat the effect of the SC suppression due to a static potential in the RQC.
NASA Astrophysics Data System (ADS)
Makino, T.; Okamoto, H.; Sato, K.; Tanaka, K.; Nishizawa, T.; Sugimoto, N.; Matsui, I.; Jin, Y.; Uchiyama, A.; Kudo, R.
2014-12-01
We have developed a new type of ground-based lidar, Multi-Field of view-Multiple-Scattering-Polarization Lidar (MFMSPL), to analyze multiple scattering contribution due to low-level clouds. One issue of the ground based lidar is the limitation of optical thickness of about 3 due to the strong attenuation in the lidar signals so that only the cloud bottom part can be observed. In order to overcome the problem, we have proposed the MFMSPL that has been designed to observe similar degree of multiple scattering contribution expected from space-borne lidar CALIOP on CALIPSO satellite. The system consists of eight detectors; four telescopes for parallel channels and four for perpendicular channels. The four pairs of telescope have been mounted with four different off-beam angles, ranging from -5 to 35mrad, where the angle is defined as the one between the direction of laser beam and the direction of telescope. Consequently, similar large foot print (100m) as CALIOP can be achieved in the MFMSPL observations when the altitude of clouds is located at about 1km. The use of multi-field of views enables to measure depolarization ratio from optically thick clouds. The outer receivers attached with larger angles generally detect backscattered signals from clouds located at upper altitudes due to the enhanced multiple scattering compared with the inner receiver that detects signals only from cloud bottom portions. Therefore the information of cloud microphysics from optically thicker regions is expected by the MFMSPL observations compared with the conventional lidar with small FOV. The MFMSPL have been continuously operated in Tsukuba, Japan since June 2014.Initial analyses have indicated expected performances from the theoretical estimation by backward Monte-Carlo simulations. The depolarization ratio from deeper part of the clouds detected by the receiver with large off-beam angle showed much larger values than those from the one with small angle. The calibration procedures
2005-12-01
light in stimulated Mandel’shtam–Brillouin scattering,” JETP Lett ., 15, 109-112, 1972. 41 . Hellwarth, R. W., “Phase conjugation by stimulated...interferometry with wavefront-reversing mirrors,” Sov . Phys . JETP , 52, 847-851, 1980. 79. Valley, M., G. Lombardi, and R. Aprahamian, “Beam...discharge,” Appl. Phys . Lett ., 86, 111104, 2005. 13. Lange, Mathew A., “Kinetics of the electric discharge pumped oxygen-iodine laser,” Sixth
Multiple-Scattering Approach to the Formation of the Impurity Band in Semiconductors
NASA Astrophysics Data System (ADS)
Ghazali, A.; Serre, J.
1982-03-01
The electronic structure of doped semiconductors is studied by using the best approximation of Klauder's impurity-scattering theory which yields a wave-vector- and energy-dependent self-energy Σ(k-->,E). An approximation is used for electron correlation effects. It is shown that as the impurity concentration is decreased, the conduction-band tail progressively splits off, giving an impurity band. The link between the formation of the latter and the general theory of bifurcation is outlined.
Fast and scalable algorithm for the simulation of multiple Mie scattering in optical systems.
Kalthoff, Oliver; Kampmann, Ronald; Streicher, Simon; Sinzinger, Stefan
2016-05-20
The Monte Carlo simulation of light propagation in optical systems requires the processing of a large number of photons to achieve a satisfactory statistical accuracy. Based on classical Mie scattering, we experimentally show that the independence of photons propagating through a turbid medium imposes a postulate for a concurrent and scalable programming paradigm of general purpose graphics processing units. This ensures that, without rewriting code, increasingly complex optical systems can be simulated if more processors are available in the future.
NASA Astrophysics Data System (ADS)
Chaput, J.; Campillo, M.; Aster, R. C.; Roux, P.; Kyle, P. R.; Knox, H.; Czoski, P.
2015-02-01
We examine seismic coda from an unusually dense deployment of over 100 short-period and broadband seismographs in the summit region of Mount Erebus volcano on a network with an aperture of approximately 5 km. We investigate the energy-partitioning properties of the seismic wavefield generated by thousands of small icequake sources originating on the upper volcano and use them to estimate Green's functions via coda cross correlation. Emergent coda seismograms suggest that this locale should be particularly amenable to such methods. Using a small aperture subarray, we find that modal energy partition between S and P wave energy between ˜1 and 4 Hz occurs in just a few seconds after event onset and persists for tens of seconds. Spatially averaged correlograms display clear body and surface waves that span the full aperture of the array. We test for stable bidirectional Green's function recovery and note that good symmetry can be achieved at this site even with a geographically skewed distribution of sources. We estimate scattering and absorption mean free path lengths and find a power law decrease in mean free path between 1.5 and 3.3 Hz that suggests a quasi-Rayleigh or Rayleigh-Gans scattering situation. Finally, we demonstrate the existence of coherent backscattering (weak localization) for this coda wavefield. The remarkable properties of scattered seismic wavefields in the vicinity of active volcanoes suggests that the abundant small icequake sources may be used for illumination where temporal monitoring of such dynamic structures is concerned.
Almasian, Mitra; Bosschaart, Nienke; van Leeuwen, Ton G; Faber, Dirk J
2015-01-01
Optical coherence tomography (OCT) has the potential to quantitatively measure optical properties of tissue such as the attenuation coefficient and backscattering coefficient. However, to obtain reliable values for strong scattering tissues, accurate consideration of the effects of multiple scattering and the nonlinear relation between the scattering coefficient and scatterer concentration (concentration-dependent scattering) is required. We present a comprehensive model for the OCT signal in which we quantitatively account for both effects, as well as our system parameters (confocal point spread function and sensitivity roll-off). We verify our model with experimental data from controlled phantoms of monodisperse silica beads (scattering coefficients between 1 and 30 mm(−1) and scattering anisotropy between 0.4 and 0.9). The optical properties of the phantoms are calculated using Mie theory combined with the Percus–Yevick structure factor to account for concentration-dependent scattering. We demonstrate excellent agreement between the OCT attenuation and backscattering coefficient predicted by our model and experimentally derived values. We conclude that this model enables us to accurately model OCT-derived parameters (i.e., attenuation and backscattering coefficients) in the concentration-dependent and multiple scattering regime for spherical monodisperse samples.
Mézière, Fabien; Muller, Marie; Bossy, Emmanuel; Derode, Arnaud
2014-07-01
This article quantitatively investigates ultrasound propagation in numerical anisotropic porous media with finite-difference simulations in 3D. The propagation media consist of clusters of ellipsoidal scatterers randomly distributed in water, mimicking the anisotropic structure of cancellous bone. Velocities and attenuation coefficients of the ensemble-averaged transmitted wave (also known as the coherent wave) are measured in various configurations. As in real cancellous bone, one or two longitudinal modes emerge, depending on the micro-structure. The results are confronted with two standard theoretical approaches: Biot's theory, usually invoked in porous media, and the Independent Scattering Approximation (ISA), a classical first-order approach of multiple scattering theory. On the one hand, when only one longitudinal wave is observed, it is found that at porosities higher than 90% the ISA successfully predicts the attenuation coefficient (unlike Biot's theory), as well as the existence of negative dispersion. On the other hand, the ISA is not well suited to study two-wave propagation, unlike Biot's model, at least as far as wave speeds are concerned. No free fitting parameters were used for the application of Biot's theory. Finally we investigate the phase-shift between waves in the fluid and the solid structure, and compare them to Biot's predictions of in-phase and out-of-phase motions. Copyright © 2013 Elsevier B.V. All rights reserved.
NASA Astrophysics Data System (ADS)
Adolph, C.; Aghasyan, M.; Akhunzyanov, R.; Alexeev, G. D.; Alexeev, M. G.; Amoroso, A.; Andrieux, V.; Anfimov, N. V.; Anosov, V.; Augsten, K.; Augustyniak, W.; Austregesilo, A.; Azevedo, C. D. R.; Badełek, B.; Balestra, F.; Barth, J.; Beck, R.; Bedfer, Y.; Bernhard, J.; Bicker, K.; Bielert, E. R.; Birsa, R.; Bisplinghoff, J.; Bodlak, M.; Boer, M.; Bordalo, P.; Bradamante, F.; Braun, C.; Bressan, A.; Büchele, M.; Capozza, L.; Chang, W.-C.; Chatterjee, C.; Chiosso, M.; Choi, I.; Chung, S.-U.; Cicuttin, A.; Crespo, M. L.; Curiel, Q.; Dalla Torre, S.; Dasgupta, S. S.; Dasgupta, S.; Denisov, O. Yu.; Dhara, L.; Donskov, S. V.; Doshita, N.; Duic, V.; Dünnweber, W.; Dziewiecki, M.; Efremov, A.; Eversheim, P. D.; Eyrich, W.; Faessler, M.; Ferrero, A.; Finger, M.; Finger, M.; Fischer, H.; Franco, C.; du Fresne von Hohenesche, N.; Friedrich, J. M.; Frolov, V.; Fuchey, E.; Gautheron, F.; Gavrichtchouk, O. P.; Gerassimov, S.; Giordano, F.; Gnesi, I.; Gorzellik, M.; Grabmüller, S.; Grasso, A.; Grosse Perdekamp, M.; Grube, B.; Grussenmeyer, T.; Guskov, A.; Haas, F.; Hahne, D.; von Harrach, D.; Hashimoto, R.; Heinsius, F. H.; Heitz, R.; Herrmann, F.; Hinterberger, F.; Horikawa, N.; d'Hose, N.; Hsieh, C.-Y.; Huber, S.; Ishimoto, S.; Ivanov, A.; Ivanshin, Yu.; Iwata, T.; Jahn, R.; Jary, V.; Joosten, R.; Jörg, P.; Kabuß, E.; Ketzer, B.; Khaustov, G. V.; Khokhlov, Yu. A.; Kisselev, Yu.; Klein, F.; Klimaszewski, K.; Koivuniemi, J. H.; Kolosov, V. N.; Kondo, K.; Königsmann, K.; Konorov, I.; Konstantinov, V. F.; Kotzinian, A. M.; Kouznetsov, O. M.; Krämer, M.; Kremser, P.; Krinner, F.; Kroumchtein, Z. V.; Kuhn, R.; Kulinich, Y.; Kunne, F.; Kurek, K.; Kurjata, R. P.; Lednev, A. A.; Lehmann, A.; Levillain, M.; Levorato, S.; Lian, Y.-S.; Lichtenstadt, J.; Longo, R.; Maggiora, A.; Magnon, A.; Makins, N.; Makke, N.; Mallot, G. K.; Marchand, C.; Marianski, B.; Martin, A.; Marzec, J.; Matoušek, J.; Matsuda, H.; Matsuda, T.; Meshcheryakov, G. V.; Meyer, M.; Meyer, W.; Michigami, T.; Mikhailov, Yu. V.; Mikhasenko, M.; Mitrofanov, E.; Mitrofanov, N.; Miyachi, Y.; Montuenga, P.; Nagaytsev, A.; Nerling, F.; Neyret, D.; Nikolaenko, V. I.; Nový, J.; Nowak, W.-D.; Nukazuka, G.; Nunes, A. S.; Olshevsky, A. G.; Orlov, I.; Ostrick, M.; Panzieri, D.; Parsamyan, B.; Paul, S.; Peng, J.-C.; Pereira, F.; Pešek, M.; Peshekhonov, D. V.; Pierre, N.; Platchkov, S.; Pochodzalla, J.; Polyakov, V. A.; Pretz, J.; Quaresma, M.; Quintans, C.; Ramos, S.; Regali, C.; Reicherz, G.; Riedl, C.; Roskot, M.; Rossiyskaya, N. S.; Ryabchikov, D. I.; Rybnikov, A.; Rychter, A.; Salac, R.; Samoylenko, V. D.; Sandacz, A.; Santos, C.; Sarkar, S.; Savin, I. A.; Sawada, T.; Sbrizzai, G.; Schiavon, P.; Schmidt, K.; Schmieden, H.; Schönning, K.; Schopferer, S.; Seder, E.; Selyunin, A.; Shevchenko, O. Yu.; Silva, L.; Sinha, L.; Sirtl, S.; Slunecka, M.; Smolik, J.; Sozzi, F.; Srnka, A.; Steffen, D.; Stolarski, M.; Sulc, M.; Suzuki, H.; Szabelski, A.; Szameitat, T.; Sznajder, P.; Takekawa, S.; Tasevsky, M.; Tessaro, S.; Tessarotto, F.; Thibaud, F.; Tosello, F.; Tskhay, V.; Uhl, S.; Veloso, J.; Virius, M.; Vondra, J.; Weisrock, T.; Wilfert, M.; Windmolders, R.; ter Wolbeek, J.; Zaremba, K.; Zavada, P.; Zavertyaev, M.; Zemlyanichkina, E.; Zhuravlev, N.; Ziembicki, M.; Zink, A.
2017-01-01
Multiplicities of charged pions and charged hadrons produced in deep-inelastic scattering were measured in three-dimensional bins of the Bjorken scaling variable x, the relative virtual-photon energy y and the relative hadron energy z. Data were obtained by the COMPASS Collaboration using a 160GeV muon beam and an isoscalar target (6LiD). They cover the kinematic domain in the photon virtuality Q2 > 1(GeV / c) 2, 0.004 < x < 0.4, 0.2 < z < 0.85 and 0.1 < y < 0.7. In addition, a leading-order pQCD analysis was performed using the pion multiplicity results to extract quark fragmentation functions.
NASA Astrophysics Data System (ADS)
Sommer, H.; Ebenau, M.; Spaan, B.; Eichmann, M.
2017-03-01
Previous studies show remarkable differences in the simulation of electron depth dose profiles of ruthenium eye plaques. We examined the influence of the scoring and simulation geometry, the source spectrum and the multiple scattering algorithm on the depth dose profile using GEANT4. The simulated absolute dose deposition agrees with absolute dose data from the manufacturer within the measurement uncertainty. Variations in the simulation geometry as well as the source spectrum have only a small influence on the depth dose profiles. However, the multiple scattering algorithms have the largest influence on the depth dose profiles. They deposit up to 20% less dose compared to the single scattering implementation. We recommend researchers who are interested in simulating low- to medium-energy electrons to examine their simulation under the influence of different multiple scattering settings. Since the simulation and scoring geometry as well as the exact physics settings are best described by the source code of the application, we made the code publicly available.
NASA Astrophysics Data System (ADS)
Silván-Cárdenas, Jose L.; Corona-Romero, Nirani
2015-10-01
In this paper, we describe some results from a study on hyperspectral analysis of coniferous canopy scattering for the purpose of estimating forest biophysical and structural parameters. Georeferenced airborne hyperspectral measurements were taken from a flying helicopter over a coniferous forest dominated by Pinus hartweguii and Abies religiosa within the Federal District Conservation Land in Mexico City. Hyperspectral data was recorded in the optical range from 350 to 2500 nm at 1nm spectral resolution using the FieldSpec 4 (ASD Inc.). Spectral measurements were also carried out in the ground for vegetation and understory components, including leaf, bark, soil and grass. Measurements were then analyzed through a previously developed multiple scattering approximation (MSA) model, which represents above-canopy spectral reflectance through a non-linear combination of pure spectral components (endmembers), as well as through a set of photon recollision probabilities and interceptance fractions. In this paper we provide an expression for the canopy absorptance as the basis for estimating the components of canopy radiation budget using the MSA model. Furthermore, since MSA does not prescribe a priori the endmembers to incorporate in the model, a multiple endmember selection method (MESMSA) was developed and tested. Photon recollision probabilities and interceptance fractions were estimated by fitting the model to airborne spectral reflectance and selected endmembers where then used to estimate the canopy radiation budget at each measured location.
NASA Technical Reports Server (NTRS)
Martin, D. L.; Perry, M. J.
1994-01-01
Water-leaving radiances and phytoplankton pigment concentrations are calculated from coastal zone color scanner (CZCS) radiance measurements by removing atmospheric Rayleigh and aerosol radiances from the total radiance signal measured at the satellite. The single greatest source of error in CZCS atmospheric correction algorithms in the assumption that these Rayleigh and aerosol radiances are separable. Multiple-scattering interactions between Rayleigh and aerosol components cause systematic errors in calculated aerosol radiances, and the magnitude of these errors is dependent on aerosol type and optical depth and on satellite viewing geometry. A technique was developed which extends the results of previous radiative transfer modeling by Gordon and Castano to predict the magnitude of these systematic errors for simulated CZCS orbital passes in which the ocean is viewed through a modeled, physically realistic atmosphere. The simulated image mathematically duplicates the exact satellite, Sun, and pixel locations of an actual CZCS image. Errors in the aerosol radiance at 443 nm are calculated for a range of aerosol optical depths. When pixels in the simulated image exceed an error threshhold, the corresponding pixels in the actual CZCS image are flagged and excluded from further analysis or from use in image compositing or compilation of pigment concentration databases. Studies based on time series analyses or compositing of CZCS imagery which do not address Rayleigh-aerosol multiple scattering should be interpreted cautiously, since the fundamental assumption used in their atmospheric correction algorithm is flawed.
NASA Astrophysics Data System (ADS)
Sutherland, Robert A.; Thompson, Jill C.; Klett, James D.
2000-07-01
We report on the application of a recently developed method for producing exact solutions of the thermal vision of the radiative transfer equation1. The method is demonstrated to be accurate to within five significant figures when compared with the one dimensional plane layer solutions published by van de Hulst2, and, has the added capability for treating discrete localized, aerosol clouds of spherical and cylindrical symmetry. The method, described in detail in a companion paper1, is only briefly summarized here, where our main purpose is to demonstrate the utility of the method for calculating emissivity functions of finite aerosol clouds of arbitrary optical thickness and albedo, and most likely to occur on the modern cluttered battlefield. The emissivity functions are then used to determine apparent temperatures including effects of both internal thermal emission and in- scatter from the ambient surroundings. We apply the results to four generic scenarios, including the mid and far IR and a hypothetical full spectrum band. In all cases, calculations show that errors on the order of several degrees in the sensed temperature can occur if cloud emissivity is not accounted for; with errors being most pronounced at the higher values of optical depth and albedo. We also demonstrate that significant discrepancies can occur when comparing results from different spectral bands, especially for the mid IR which consistently shows higher apparent temperatures than the other bands, including the full spectrum case. Results of emissivity calculations show that in almost no case can one justify the simple Beer's Law model that essentially ignores emissive/scattering effects; however, there is reason for optimism in the use of other simplifying first and higher order approximations used in some contemporary models. The present version of the model treats only Gaussian aerosol distributions and isotropic scattering; although neither assumption necessarily represents a
2005-12-01
Mandel’shtam–Brillouin scattering,” JETP Lett ., 15, 109-112, 1972. 41 . Hellwarth, R. W., “Phase conjugation by stimulated backscattering,” ch. 7, Optical...wavefront-reversing mirrors,” Sov . Phys . JETP , 52, 847-851, 1980. 79. Valley, M., G. Lombardi, and R. Aprahamian, “Beam combination by stimulated...Thomas, and R. Byer, Monolithic, “Unidirectional single-mode Nd:YAG ring laser”, Opt. Lett ., 10, 65-67, 1985 . 56. Imai, M. and E. H. Hara
2005-12-22
Mandel’shtam–Brillouin scattering,” JETP Lett ., 15, 109-112, 1972. 41 . Hellwarth, R. W., “Phase conjugation by stimulated backscattering,” ch. 7, Optical...wavefront-reversing mirrors,” Sov . Phys . JETP , 52, 847-851, 1980. 79. Valley, M., G. Lombardi, and R. Aprahamian, “Beam combination by stimulated...Thomas, and R. Byer, Monolithic, “Unidirectional single-mode Nd:YAG ring laser”, Opt. Lett ., 10, 65-67, 1985 . 56. Imai, M. and E. H. Hara
NASA Astrophysics Data System (ADS)
Gustavsson, Magnus; Kristensson, Gerhard; Wellander, Niklas
2016-12-01
A numerical implementation of a method to analyze scattering by randomly located obstacles in a slab geometry is presented. In general, the obstacles can be of arbitrary shape, but, in this first implementation, the obstacles are dielectric spheres. The coherent part of the reflected and transmitted intensity at normal incidence is treated. Excellent agreement with numerical results found in the literature of the effective wave number is obtained. Moreover, comparisons with the results of the Bouguer-Beer (B-B) law are made. The present theory also gives a small reflected coherent field, which is not predicted by the Bouguer-Beer law, and these results are discussed in some detail.
A Two-Dimensional Helmholtz Equation Solution for the Multiple Cavity Scattering Problem
2013-02-01
present an efficient block Gauss– Seidel method , which may be written as follows: given ðuð0Þ1 ; ;u ð0Þ n Þ>, define ðuðkÞ1 ; . . . ;u ðkÞ n Þ>; k P...well-posed single cavity scattering problems (5.5)–(5.7) for the block Gauss– Seidel method at each iteration. 5.2. Transparent boundary condition... Seidel method for two consecutive approx- imations again the number of iterations for all three types of cavities. It can be seen from Fig. 10 that
Revisit the spin-FET: Multiple reflection, inelastic scattering, and lateral size effects
Xu, Luting; Li, Xin-Qi; Sun, Qing-feng
2014-01-01
We revisit the spin-injected field effect transistor (spin-FET) in a framework of the lattice model by applying the recursive lattice Green's function approach. In the one-dimensional case the results of simulations in coherent regime reveal noticeable differences from the celebrated Datta-Das model, which lead us to an improved treatment with generalized result. The simulations also allow us to address inelastic scattering and lateral confinement effects in the control of spins. These issues are very important in the spin-FET device. PMID:25516433
NASA Astrophysics Data System (ADS)
Cerussi, Albert E.; Gratton, Enrico; Fantini, Sergio
1999-07-01
Over the past few years, there has been significant research activity devoted to the application of fluorescence spectroscopy to strongly scattering media, where photons propagate diffusely. Much of this activity focused on fluorescence as a source of contrast enhancement in optical tomography. Our efforts have emphasized the quantitative recovery of fluorescence parameters for spectroscopy. Using a frequency-domain diffusion-based model, we have successfully recovered the lifetime, the absolute quantum yield, the fluorophore concentration, and the emission spectrum of the fluorophore, as well as the absorption and the reduced scattering coefficients at the emission wavelength of the medium in different measurements. In this contribution, we present a sensitive monitor of the binding between ethidium bromide and bovine cells in fresh milk. The spectroscopic contrast was the approximately tenfold increase in the ethidium bromide lifetime upon binding to DNA. The measurement clearly demonstrated that we could quantitatively measure the density of cells in the milk, which is an application vital to the tremendous economic burden of bovine subclinical mastitis detection. Furthermore, we may in principle use the spirit of this technique as a quantitative monitor of the binding of fluorescent drugs inside tissues. This is a first step towards lifetime spectroscopy in tissues.
NASA Astrophysics Data System (ADS)
Sergeeva, E. A.; Kirillin, M. Yu; Priezzhev, A. V.
2006-11-01
The time profile of a femtosecond pulse propagating in media with a high scattering anisotropy (g>=0.9) is studied in detail. The iteration method based on the expansion of the light field in a series in photon scattering orders with the account for the multiply scattered component is proposed to study analytically the structure of a scattered radiation pulse. The small-angle approximation of the radiation transfer theory used for calculations of low-order scatterings is modified to take into account the spread in the photon delay times. The shape of a scattered ultrashort pulse calculated theoretically well agrees with the shape obtained by the Monte-Carlo simulation. It is shown that the pulse profile in a scattering medium depends on the shape of the scattering phase function with the conservation of the anisotropy factor. A comparative analysis of contributions from different scattering orders to the pulse structure is performed depending on the optical properties of a scattering medium.
NASA Astrophysics Data System (ADS)
Arnott, W. P.; Moosmueller, H.; Sheridan, P. J.; Ogren, J. A.
2002-12-01
The filter used on the aethalometer is a multiple scattering substrate, yet the current parameterization of the instrument simply uses Beer's law for its analysis when obtaining black carbon concentration. Specific characterizations of the instrument response, where filter attenuation was obtained as a function of wavelength, gave the following impressions. 1. Filter attenuation generally increases inversely with wavelength for all aerosol types. 2. When subjected to a constant flow of low single scattering albedo aerosol, the instrument shows a non-constant response. The response is highest when the filter single scattering albdeo is highest, and it decreases as the filter blackens. 3. When subjected to a constant flow of essentially unity single scattering albedo aerosol, the instrument shows a non-zero response, even though it should do so. A few percent of scattering is converted to absorption, because the addition of purely scattering aerosol is analogous to a simple thickening of the filter. The effect is more pronounced at shorter wavelengths, and is related to item 1. The multiple scattering model reproduces these behaviors. The photoacoustic instrument light absorption calibration with nitrogen dioxide gas will be presented along with closure data from extinction minus scattering as evaluations of its measurement accuracy.
Response to ``non-muffin-tin band theories of the multiple-scattering type''
NASA Astrophysics Data System (ADS)
Brown, R. G.; Ciftan, M.
1985-07-01
We respond to the preceding Comment by J. S. Faulkner by examining the convergence properties of functions used to represent solutions to Schrödinger's equation in the context of Green's-function band theory. Such evidence as exists on the subject is reviewed. The conclusion drawn is that the data presented in his comment are sufficient to conclude that ``a large fraction of the errors caused by ignoring the non-muffin-tin parts of a potential can be eliminated by the simple expedient of including the nondiagonal parts of the scattering matrix.'' However, the data presented do not warrant the conclusion that our theory is incorrect through the neglect or incorrect treatment of the ``near field'' or in any other manner. This is a question that must ultimately be resolved algebraically, but the data so far presented do not seem to be inconsistent with our theory being exact.
Kirkwood, R. K.; Moody, J. D.; Niemann, C.; Williams, E. A.; Langdon, A. B.; Landen, O. L.; Divol, L.; Suter, L. J.; Depierreux, S.; Seka, W.
2006-08-15
Experiments in plasmas produced with 2 mm diameter gas filled targets preheated with 10 kJ of laser energy have shown that the stimulated Raman scattering (SRS) of a high intensity, 351 nm, beam is affected by the presence of a second, counterpropagating, high intensity beam and that has its polarization aligned to the first when the plasma conditions are relevant to ignition by indirect drive. Separate experiments with the crossing beam's polarization rotated to be normal to the first beam's polarization show little change in the SRS backscatter when the second beam is added, consistent with the reduction in the SRS being caused by low frequency waves driven by the ponderomotive force produced by the beating of the two beams.
Multiple size scale structures in silica/siloxane composites studied by small-angle scattering
Beaucage, G.; Schaefer, D.W.; Ulibarri, T.; Black, E.
1993-12-31
The physical properties of in-situ produced composites, such as the TEOS-polysiloxane based systems, are directly related to the complex interaction of structural features from the nano- to macro-scopic scales. The nature of these structural interactions are a key element in understanding and controlling mechanical properties in these systems. We believe that the smallest scale structures, in the nanometer range, correlate with properties such as the modulus while large-scale structures on the micron scale effect failure in these materials. This paper discusses techniques for analysis of structural features and interrelation of structural features over these wide ranges of size using small-angle light, x-ray and neutron scattering. Combination of data from different instruments allows for characterization of the interaction between these different size scale features.
NASA Astrophysics Data System (ADS)
French, Rebecca; Gigan, Sylvain; Muskens, Otto L.
2017-05-01
Encoding of spectral information onto monochrome imaging cameras is of interest for wavelength multiplexing and hyperspectral imaging applications. Here, the complex spatio-spectral response of a disordered material is used to demonstrate retrieval of a number of discrete wavelengths over a wide spectral range. Strong, diffuse light scattering in a semiconductor nanowire mat is used to achieve a highly compact spectrometer of micrometer thickness, transforming different wavelengths into distinct speckle patterns with nanometer sensitivity. Spatial multiplexing is achieved through the use of a microlens array, allowing simultaneous imaging of many speckles, ultimately limited by the size of the diffuse spot area. The performance of different information retrieval algorithms is compared. A compressive sensing algorithm exhibits efficient reconstruction capability in noisy environments and with only a few measurements.
NASA Astrophysics Data System (ADS)
Sulik, B.; Kövér, Á.; Ricz, S.; Koncz, Cs.; Tökesi, K.; Víkor, Gy.; Chesnel, J.-Y.; Stolterfoht, N.; Berényi, D.
Double differential cross sections in the 20-550 eV energy range and in the full angular range of 0°-180° for electron emission were measured by the impact of 150 keV/u C+ ions on He and Ne atoms. An unexpected, broad structure around 300 eV electron energy has been observed at backward emission angles relative to the beam direction. Our CTMC calculations support the hypothesis that the new structure is due to double scattering of the target electrons on the screened fields of the projectile and the target. According to the present impact-parameter Born calculations, the average degree of ionization is about 50% for C++ Ne collisions, i.e., a multiple ionized system is created in the collision.
Fulton, John L; Kathmann, Shawn M; Schenter, Gregory K; Balasubramanian, Mahalingam
2009-12-17
Details of the first-shell water structure about Ag(+) are reported from a corefinement of the K- and L(2)-edge multiple scattering signal in the X-ray absorption fine structure (XAFS) spectra. Detailed fits of the Ag K-edge data that include the contributions from multiple scattering processes in the hydrated ion structure cannot distinguish between models containing tetrahedral symmetry versus those containing collinear O-Ag-O bonds. However, we show that the multiple scattering oscillations at the L(2)-edges have distinctly different phase and amplitude functions than at the K-edge. These phase and amplitude functions depend not only on the symmetry of the multiple scattering paths but also on the nature of the final state electronic wave function probed by the dipole-allowed transition. Hence the multiple scattering portions of K- and L(2)-edge spectra provide independent measurements of the local symmetry--not a redundant measurement as is commonly believed. On the basis of the enhanced information content obtained by the simultaneous assessment of both the K- and L(2)-edges, we report that the hydrated Ag(+) structure contains five or six water molecules in the first shell with a significant number of nearly collinear and 90 degrees O-Ag-O bond angles. Finally, the K- and L(2)-edge spectra are used to benchmark the hydration structure that is generated from both DFT-based and classical molecular dynamics simulations. Simulated first-shell structures are compared to the experimental structures.
NASA Astrophysics Data System (ADS)
Churmakov, D. Yu; Kuz'min, V. L.; Meglinskii, I. V.
2006-11-01
The vector Monte-Carlo method is developed and applied to polarisation optical coherence tomography. The basic principles of simulation of the propagation of polarised electromagnetic radiation with a small coherence length are considered under conditions of multiple scattering. The results of numerical simulations for Rayleigh scattering well agree with the Milne solution generalised to the case of an electromagnetic field and with theoretical calculations in the diffusion approximation.
Rich, A.M.; Armstrong, R.S.; Ellis, P.J.; Freeman, H.C.; Lay, P.A.
1998-11-02
XAFS data in the range 0 {le} k {le} 14.5 {angstrom}{sup {minus}1} have been obtained from frozen aqueous solutions (10 K) of horse heart myoglobin (Mb) in the Fe(III) (aqua-met) and Fe(II) (deoxy) forms. The structures of the Fe sites have been refined using both single-scattering (SS) and multiple-scattering (MS) analyses. The XAFS MS analyses yield more precise Fe-ligand bond lengths (estimated error 0.02--0.03 {angstrom}) than those determined crystallographically (estimated errors {ge} 0.1 {angstrom}). For met-Mb, the MS analysis results in an average Fe-N(pyrrole) distance of 2.05 {angstrom}, an Fe-N(imidazole) distance of 2.17 {angstrom}, and an Fe-O(aqua) distance of 2.08 {angstrom}. For deoxy-Mb, the MS analysis results in Fe-N(pyrrole) and Fe-N(imidazole) distances of 2.06 and 2.16 {angstrom}, respectively. The final XAFS R values are 18.8% and 17.8% for met- and deoxy-Mb, respectively. The robustness of the refinements was tested by varying the starting models, constraints, restraints, and k ranges.
NASA Astrophysics Data System (ADS)
Lee, Taewoong; Lee, Hyounggun; Kim, Younghak; Lee, Wonho
2017-01-01
The purpose of this study is to compare and evaluate the performance of a multiple-scattering Compton imager (MSCI) to measure prompt gamma-rays emitted during proton therapy. Because prompt gamma-rays are generated simultaneously during the proton beam delivery, the falloff position of the Bragg peak of the proton beam can be determined from the distribution of prompt gamma-rays. The detection system was designed using three CdZnTe detector layers that can track radiation of unknown energy on the basis of effective Compton scattering events. The simple back-projection, filtered back-projection, and maximum likelihood expectation maximization (MLEM) algorithms were applied for the reconstructed Compton images. The falloff positions of the Bragg peaks determined from individual MSCIs were compared with the theoretical values calculated using the Monte Carlo N-Particle eXtended code. Moreover, the performance of the MSCI was compared with that of a previously developed system based on a slit collimator gamma camera. In summary, the MSCI with the MLEM reconstruction algorithm was better than the other reconstruction methods in terms of the falloff position of the Bragg peak, the angular resolution, and the signal-to-noise ratio.
Numerical Simulations of Single and Multiple Scattering by Fractal Ice Clusters
NASA Technical Reports Server (NTRS)
Dlugach, Janna M.; Mishchenko, Michael I.; Mackowski, Daniel W.
2011-01-01
We consider the scattering model in the form of a vertically and horizontally homogeneous particulate slab of an arbitrary optical thickness composed of widely separated fractal aggregates built of small spherical ice monomers. The aggregates are generated by applying three different approaches, including simulated cluster-cluster aggregation (CCA) and diffusion-limited aggregation (DLA) procedures. Having in mind radar remote-sensing applications, we report and analyze the results of computations of the backscattering circular polarization ratio obtained using efficient superposition T-matrix and vector radiative-transfer codes. The computations have been performed at a wavelength of 12.6 cm for fractal aggregates with the following characteristics: monomer refractive index m=1.78+i0.003, monomer radius r=1 cm, monomer packing density p=0.2, overall aggregate radii R in the range 4<=R<=10 cm and fractal dimensions D(sub f) 2.5 and 3. We show that for aggregates generated with simulated CCA and DLA procedures, the respective values of the backscattering circular polarization ratio differ weakly for D(sub f) 2.5, but the differences can increase somewhat for D(sub f)3, especially in case of an optically semi-infinite medium. For aggregates with a spheroidal overall shape, the dependence of the circular polarization ratio on the cluster morphology can be quite significant and increases with increasing the aspect ratio of the circumscribing spheroid.
Numerical Simulations of Single and Multiple Scattering by Fractal Ice Clusters
NASA Technical Reports Server (NTRS)
Dlugach, Janna M.; Mishchenko, Michael I.; Mackowski, Daniel W.
2011-01-01
We consider the scattering model in the form of a vertically and horizontally homogeneous particulate slab of an arbitrary optical thickness composed of widely separated fractal aggregates built of small spherical ice monomers. The aggregates are generated by applying three different approaches, including simulated cluster-cluster aggregation (CCA) and diffusion-limited aggregation (DLA) procedures. Having in mind radar remote-sensing applications, we report and analyze the results of computations of the backscattering circular polarization ratio obtained using efficient superposition T-matrix and vector radiative-transfer codes. The computations have been performed at a wavelength of 12.6 cm for fractal aggregates with the following characteristics: monomer refractive index m=1.78+i0.003, monomer radius r=1 cm, monomer packing density p=0.2, overall aggregate radii R in the range 4<=R<=10 cm and fractal dimensions D(sub f) 2.5 and 3. We show that for aggregates generated with simulated CCA and DLA procedures, the respective values of the backscattering circular polarization ratio differ weakly for D(sub f) 2.5, but the differences can increase somewhat for D(sub f)3, especially in case of an optically semi-infinite medium. For aggregates with a spheroidal overall shape, the dependence of the circular polarization ratio on the cluster morphology can be quite significant and increases with increasing the aspect ratio of the circumscribing spheroid.
NASA Astrophysics Data System (ADS)
Otsuki, Soichi
2017-01-01
The effective scattering Mueller matrices obtained by the simulation were simplified to the reduced matrices and factorized using the Lu-Chipman polar decomposition, which afforded the polarization parameters in two dimensions. In general, the scalar retardance around the illumination point of a pencil beam shows a broad azimuthal dependence with an offset. Photons may behave quite differently under the birefringence according to their polarization state. In contrast, when the birefringence is oriented along the y-axis in the plane parallel to the surface (x-y) plane, for example, the azimuthal dependence of the scalar retardance shows clear maxima along the x- and y-axes and sharp valleys between the maxima. Photons propagating in the medium probably experience the retardance in nearly the same way when they are polarized linearly and circularly. Moreover, the polarization parameters generally become nonsymmetric with respect to the plane perpendicular to both the x-y plane and the plane containing the birefringence axis, which suggests that the pathway of the lateral propagation of photons from the illumination point to the surrounding is slightly oblique upward relative to the x-y plane. These results were also compared with the case in which the birefringence axis is perpendicular to the x-y plane.
NASA Astrophysics Data System (ADS)
Otsuki, S.
2017-02-01
The effective scattering Mueller matrices obtained by the simulation were simplified to the reduced matrices and factorized using the Lu-Chipman polar decomposition, which afforded the polarization parameters in two dimensions. In general, the scalar retardance around the illumination point of a pencil beam shows a broad azimuthal dependence with an offset. Photons may behave quite differently under the birefringence according to their polarization state. In contrast, when the birefringence is oriented along the y axis in the plane parallel to the surface (x-y) plane, for example, the azimuthal dependence of the scalar retardance shows clear maxima along the x and y axes and sharp valleys between the maxima. Photons propagating in the medium probably experience the retardance in nearly the same way, when they are polarized linearly and circularly. Moreover, the polarization parameters generally become nonsymmetric with respect to the plane perpendicular to both the x-y plane and the plane containing the birefringence axis, which suggests that the pathway of the lateral propagation of photons from the illumination point to the surrounding is slightly oblique upward relative to the x-y plane.
NASA Astrophysics Data System (ADS)
Serre, J.; Ghazali, A.
1983-10-01
Klauder's best multiple-scattering approximation which allows the use of a realistic interaction potential and in which electron-electron interactions may be incorporated is shown to constitute a sound basis for the study of the electronic structure of doped semiconductors. The implementation of this formalism requires the solution of a self-consistent set of nonlinear integral equations. This has been done numerically over a large impurity-concentration range. We have thus shown that as the concentration decreases, the band tail gradually splits off from the main band, giving an impurity band. Spectral-density analysis allows one to distinguish between localized and extended states. Compensation effects have also been analyzed. Finally, our results are discussed and compared with various experiments.
Biris, Alexandru S.; Boldor, Dorin; Palmer, Jason; Monroe, William T.; Mahmood, Meena; Dervishi, Enkeleda; Xu, Yang; Li, Zhongrui; Galanzha, Ekaterina I.; Zharov, Vladimir P.
2016-01-01
Nanophotothermolysis with long laser pulses for treatment of scattered cancer cells and their clusters is introduced with the main focus on real-time monitoring of temperature dynamics inside and around individual cancer cells labeled with carbon nanotubes. This technique utilizes advanced time- and spatially-resolved thermal radiometry imaging for the visualization of laser-induced temperature distribution in multiple-point absorbing targets. The capability of this approach was demonstrated for monitoring of thermal effects under long laser exposure (from millisecond to seconds, wavelength 1064 nm, maximum power 1 W) of cervical cancer HeLa cells labeled with carbon nanotubes in vitro. The applications are discussed with a focus on the nanophotothermolysis of small tumors, tumor margins, or micrometastases under the guidance of near-IR and microwave radiometry. PMID:19405720
NASA Astrophysics Data System (ADS)
Cantero, E. D.; Lantschner, G. H.; Eckardt, J. C.; Lovey, F. C.; Arista, N. R.
2010-04-01
Measurements of angular distributions and of the angular dependence of the energy loss of 4-, 6-, and 9-keV protons transmitted through thin Cu and Ag polycrystalline foils are presented. By means of standard multiple-scattering model calculations it is found that a V(r)∝r-2.8 potential leads to significantly better fits of the angular distributions than the standard Thomas Fermi, Lenz-Jensen, or Ziegler-Biersack-Littmark potentials. A theoretical model for the angular dependence of the energy loss based on considering geometric effects on a frictional inelastic energy loss plus an angular-dependent elastic contribution and the effects of foil roughness reproduces the experimental data. This agrees with previous results in Au and Al, therefore extending the applicability of the model to other metallic elements.
NASA Astrophysics Data System (ADS)
Li, D. J.; Yang, G. L.; Chen, F.; Xie, J. J.; Zhang, L. M.; Guo, J.; Shao, C. L.; Peng, Z. Q.; Lu, Q. P.
2012-05-01
Stimulated rotational Raman scattering (SRRS) at multiwavelength pumped by TEA CO2 laser was demonstrated in this paper. Raman mediums were cooled by liquid-N2 and a multiple-pass cell (MPC) with 25 passes was designed and used. When the para-H2 was pumped by single-longitudinal-mode (SLM) circular polarized TEA CO2 laser on 10P(20), 9P(20), and 10R(20), 50 mJ 16.95 μm, 350 mJ 14.44 μm, and 536 mJ 16.9 μm radiations were obtained, corresponding to energy conversion efficiency of 1.2, 11.7, and 13.4%, respectively. When the ortho-D2 was pumped by CO2 laser on 10R(18), 108 mJ 12.57 μm Raman laser was obtained with energy conversion efficiency of 2.9%.
Ahn, Jae-Hyun; Park, Young-Je; Kim, Wonkook; Lee, Boram
2016-12-26
An estimation of the aerosol multiple-scattering reflectance is an important part of the atmospheric correction procedure in satellite ocean color data processing. Most commonly, the utilization of two near-infrared (NIR) bands to estimate the aerosol optical properties has been adopted for the estimation of the effects of aerosols. Previously, the operational Geostationary Color Ocean Imager (GOCI) atmospheric correction scheme relies on a single-scattering reflectance ratio (SSE), which was developed for the processing of the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) data to determine the appropriate aerosol models and their aerosol optical thicknesses. The scheme computes reflectance contributions (weighting factor) of candidate aerosol models in a single scattering domain then spectrally extrapolates the single-scattering aerosol reflectance from NIR to visible (VIS) bands using the SSE. However, it directly applies the weight value to all wavelengths in a multiple-scattering domain although the multiple-scattering aerosol reflectance has a non-linear relationship with the single-scattering reflectance and inter-band relationship of multiple scattering aerosol reflectances is non-linear. To avoid these issues, we propose an alternative scheme for estimating the aerosol reflectance that uses the spectral relationships in the aerosol multiple-scattering reflectance between different wavelengths (called SRAMS). The process directly calculates the multiple-scattering reflectance contributions in NIR with no residual errors for selected aerosol models. Then it spectrally extrapolates the reflectance contribution from NIR to visible bands for each selected model using the SRAMS. To assess the performance of the algorithm regarding the errors in the water reflectance at the surface or remote-sensing reflectance retrieval, we compared the SRAMS atmospheric correction results with the SSE atmospheric correction using both simulations and in situ match-ups with the
NASA Astrophysics Data System (ADS)
Lee, Taewoong; Yoon, Changyeon; Lee, Wonho
2014-06-01
During radiation therapy, the irradiated position and the energy deposited in a patient must be monitored. In general, calculations before photon exposure or 2D measurements of the transmitted photons have been widely used for making dose estimates. In this paper, we propose a real-time 3D dose measurement using Compton imaging technology. On the basis of the Monte-Carlo method, we designed a multiple-scattering Compton camera system (MSCC) with semiconductor and scintillation detectors. The MSCC was constructed with two semiconductor detectors as scattering detectors and a cadmium-tungstate (CWO) scintillator detector as an absorber detector. The two planar semiconductor arrays, and the CWO array consisted of 40 × 40 pixels, each with a size of 1 × 1 × ɛ mm3, where ɛ is the variable thickness of the detectors. The design parameters, such as the types of semiconductors, detector thicknesses and distances between detectors, were optimized on the basis of the detection efficiency and angular resolution of reconstructed images for a point source. Under the optimized conditions, uncertainty factors in geometry and energy were estimated for various inter-detector distances. We used a source corresponding to photons scattered from a water phantom exposed to 6-MeV peak X-rays. According to our simulation results, the figure of merit, reached its maximum value when the inter-detector distance was 3 cm. In order to achieve a high FOM, we chose 1 cm as the optimum thickness for the scattering and absorbed detectors. A cadmium-zinc-telluride (CZT) detector showed the best performance among the simulated semiconductors. The position uncertainty caused by the pixelization effect was the major factor in degrading the angular resolution of the reconstructed images, and the degradation caused by energy broadening was less than expected. The angular uncertainties caused by Doppler broadening and incorrect sequencing were minimal compared with that of pixelization. Our
Popov, A P; Priezzhev, A V; Lademann, Juergen; Myllylae, Risto
2007-01-31
The propagation of radiation in different spectral ranges in a superficial skin layer partially filled with titanium dioxide nanoparticles at the volume concentration 0.67%-2.25% is simulated by the Monte-Carlo method. This volume concentration corresponds to the maximum admissible concentrations of particles that most efficiently attenuate radiation in the independent scattering regime. The transmission of radiation at 307, 400, and 500 nm in a 20-{mu}m thick skin layer is simulated and the effect of nanoparticles on the contributions from photons of different scattering orders to transmission is considered. It is shown that the administration of nanoparticles results in the broadening of the scattering-order distribution of photons propagated through the skin layer and the shift of the maximum of this distribution in the direction of a greater number of scattering events at wavelengths 400 and 500 nm, the effect being more pronounced at 400 nm. The increase in the scattering order elongates photon trajectories in the medium and enhances diffusely scattered radiation, thereby reducing transmission. (special issue devoted to multiple radiation scattering in random media)
NASA Astrophysics Data System (ADS)
Berdnik, V. V.; Loiko, V. A.
2006-11-01
A method describing the propagation of radiation in concentrated dispersive media with optically soft particles is developed. The results of analysis of the angular structure of radiation scattered in the forward and backward semispheres depending on the direction of layer illumination, its optical thickness, concentration and the size of optically soft particles, are presented. The transport theory is used to describe the propagation of radiation. The equation of radiation transport is solved by the doubling method with the help of spline approximation averaged over the azimuth of scattering indicatrix in a unit volume. The parameters of the unit volume were determined by using the Mie theory and the interference approximation taking into account the collective scattering effects at a high concentration of particles.
Li, Xiang-Guo; Chu, Iek-Heng; Zhang, X. -G.; Cheng, Hai-Ping
2015-05-28
Electron transport in graphene is along the sheet but junction devices are often made by stacking different sheets together in a “side-contact” geometry which causes the current to flow perpendicular to the sheets within the device. Such geometry presents a challenge to first-principles transport methods. We solve this problem by implementing a plane-wave-based multiple-scattering theory for electron transport. In this study, this implementation improves the computational efficiency over the existing plane-wave transport code, scales better for parallelization over large number of nodes, and does not require the current direction to be along a lattice axis. As a first application, we calculate the tunneling current through a side-contact graphene junction formed by two separate graphene sheets with the edges overlapping each other. We find that transport properties of this junction depend strongly on the AA or AB stacking within the overlapping region as well as the vacuum gap between two graphene sheets. Finally, such transport behaviors are explained in terms of carbon orbital orientation, hybridization, and delocalization as the geometry is varied.
Valier-Brasier, Tony; Conoir, Jean-Marc; Coulouvrat, François; Thomas, Jean-Louis
2015-10-01
Sound propagation in dilute suspensions of small spheres is studied using two models: a hydrodynamic model based on the coupled phase equations and an acoustic model based on the ECAH (ECAH: Epstein-Carhart-Allegra-Hawley) multiple scattering theory. The aim is to compare both models through the study of three fundamental kinds of particles: rigid particles, elastic spheres, and viscous droplets. The hydrodynamic model is based on a Rayleigh-Plesset-like equation generalized to elastic spheres and viscous droplets. The hydrodynamic forces for elastic spheres are introduced by analogy with those of droplets. The ECAH theory is also modified in order to take into account the velocity of rigid particles. Analytical calculations performed for long wavelength, low dilution, and weak absorption in the ambient fluid show that both models are strictly equivalent for the three kinds of particles studied. The analytical calculations show that dilatational and translational mechanisms are modeled in the same way by both models. The effective parameters of dilute suspensions are also calculated.
Li, Xiang-Guo; Chu, Iek-Heng; Zhang, X. -G.; ...
2015-05-28
Electron transport in graphene is along the sheet but junction devices are often made by stacking different sheets together in a “side-contact” geometry which causes the current to flow perpendicular to the sheets within the device. Such geometry presents a challenge to first-principles transport methods. We solve this problem by implementing a plane-wave-based multiple-scattering theory for electron transport. In this study, this implementation improves the computational efficiency over the existing plane-wave transport code, scales better for parallelization over large number of nodes, and does not require the current direction to be along a lattice axis. As a first application, wemore » calculate the tunneling current through a side-contact graphene junction formed by two separate graphene sheets with the edges overlapping each other. We find that transport properties of this junction depend strongly on the AA or AB stacking within the overlapping region as well as the vacuum gap between two graphene sheets. Finally, such transport behaviors are explained in terms of carbon orbital orientation, hybridization, and delocalization as the geometry is varied.« less
NASA Astrophysics Data System (ADS)
Barborica, A.; Mihailescu, I. N.; Teodorescu, V. S.
1994-03-01
We introduce a theoretical analysis of the temporal and spatial evolution of the surface topography of solids following interference between incident and scattered pulsed laser beams. The essential role played by the nonlinear delayed feedback in the laser-radiation-surface system is considered. We show that it finally determines the surface topography evolution from pulse to pulse. In order to complete the analysis, numerical calculations have been conducted under the hypothesis of strong attenuation of laser radiation into the sample and of a limited heat diffusion during the action of a laser pulse. We predict an evolution from very simple to complex (chaotic) structures under multiple-pulse-laser irradiation of solid surfaces. This evolution is determined by some key irradiation parameters; initial surface microrelief, incident laser intensity, and the number of applied laser pulses. Experiments were performed in order to check the main predictions of the theoretical analysis. The system of transversal excited atmospheric pressure-CO2 laser radiation (λ=10.6 μm)-interacting with fused silica was chosen as appropriate for performing test experiments. Optical microscopy studies of laser-treated zones evidenced special modifications of the surface topography in good accordance with the conclusions following from the theoretical analysis. The theoretical analysis is also in good agreement with some available data from the literature, at the same time providing a coherent interpretation of previously unexplained behaviors.
NASA Astrophysics Data System (ADS)
Minato, Shohei; Ghose, Ranajit
2017-03-01
Low-frequency, axially-symmetric guided waves which propagate along a fluid-filled borehole (tube waves) are studied in order to characterize the hydraulic fractures intersecting the borehole. We formulate a new equation for the total tube wavefield, which includes simultaneous effects of (1) tube-wave scattering (reflection and transmission) due to wave propagation across hydraulic fractures, and (2) tube-wave generation due to incident plane P waves. The fracture is represented by the nonwelded interface boundary conditions. We use an appropriate form of the representation theorem in order to correctly handle the multiple scattering due to nonwelded interfaces. Our approach can implement any model that has so far been developed. We consider a recent model which includes simultaneous effects of fluid viscosity, dynamic fluid flow, and fracture compliance. The derived equation offers a number of important insights. We recognize that the effective generation amplitude contains the simultaneous effect of both tube-wave generation and scattering. This leads to a new physical understanding indicating that the tube waves are scattered immediately after generation. We show that this scattering is nonlinear with respect to interface compliance. This physical mechanism can be implicitly accounted for by considering more realistic boundary conditions. We also illustrate the application of the new equation in order to predict the complex signature of the total tube wavefield, including generation and scattering at multiple hydraulic fractures. A new formulation for focusing analyses is also derived in order to image and characterize the hydraulic fractures. The obtained results and discussions are important for interpretation, modeling, and imaging using low-frequency guided waves, in the presence of multiple fractures along a cylindrical inclusion.
Shea, Jacob D.; Kosmas, Panagiotis; Hagness, Susan C.; Van Veen, Barry D.
2010-01-01
Purpose: Breast density measurement has the potential to play an important role in individualized breast cancer risk assessment and prevention decisions. Routine evaluation of breast density will require the availability of a low-cost, nonionizing, three-dimensional (3-D) tomographic imaging modality that exploits a strong properties contrast between dense fibroglandular tissue and less dense adipose tissue. The purpose of this computational study is to investigate the performance of 3-D tomography using low-power microwaves to reconstruct the spatial distribution of breast tissue dielectric properties and to evaluate the modality for application to breast density characterization. Methods: State-of-the-art 3-D numerical breast phantoms that are realistic in both structural and dielectric properties are employed. The test phantoms include one sample from each of four classes of mammographic breast density. Since the properties of these phantoms are known exactly, these testbeds serve as a rigorous benchmark for the imaging results. The distorted Born iterative imaging method is applied to simulated array measurements of the numerical phantoms. The forward solver in the imaging algorithm employs the finite-difference time-domain method of solving the time-domain Maxwell’s equations, and the dielectric profiles are estimated using an integral equation form of the Helmholtz wave equation. A multiple-frequency, bound-constrained, vector field inverse scattering solution is implemented that enables practical inversion of the large-scale 3-D problem. Knowledge of the frequency-dependent characteristic of breast tissues at microwave frequencies is exploited to obtain a parametric reconstruction of the dispersive dielectric profile of the interior of the breast. Imaging is performed on a high-resolution voxel basis and the solution is bounded by a known range of dielectric properties of the constituent breast tissues. The imaging method is validated using a breast
Nisbet, A. G. A.; Beutier, G.; Fabrizi, F.; Moser, B.; Collins, S. P.
2015-01-01
A new form of diffraction lines similar to Rutherford, Kikuchi and Kossel lines has been identified. They can be used to eliminate the need for sample/source matching in Lonsdale’s triple convergent line method in lattice-parameter determination. A new form of diffraction lines has been identified, similar to Rutherford, Kikuchi and Kossel lines. This paper highlights some of the properties of these lines and shows how they can be used to eliminate the need for sample/source matching in Lonsdale’s triple convergent line method in lattice-parameter determination.
Meng, M.; Wu, S. X. Zhou, W. Q.; Li, S. W.
2016-08-22
Anomalous Hall effect (AHE) has been studied for ferrimagnetic antiperovskite Mn{sub 3.5}Dy{sub 0.5}N film grown by molecular-beam epitaxy. Reflective high energy electron diffraction and transmission electron microscopy demonstrate the high quality of the film. We have used a scaling involving multiple competing scattering mechanisms to distinguish variations of contributions to the AHE by heavily doped Dy. The scaling analysis revealed that the heavily doped Dy has dramatically modified the skew scattering part of the AHE in Mn{sub 4}N and Mn{sub 3.5}Dy{sub 0.5}N has a totally different scattering mechanism from an undoped film.
Ghosh, Nirmalya; Wood, Michael F G; Vitkin, I Alex
2008-01-01
Linear birefringence and optical activity are two common optical polarization effects present in biological tissue, and determination of these properties has useful biomedical applications. However, measurement and unique interpretation of these parameters in tissue is hindered by strong multiple scattering effects and by the fact that these and other polarization effects are often present simultaneously. We have investigated the efficacy of a Mueller matrix decomposition methodology to extract the individual intrinsic polarimetry characteristics (linear retardance delta and optical rotation psi, in particular) from a multiply scattering medium exhibiting simultaneous linear birefringence and optical activity. In the experimental studies, a photoelastic modulation polarimeter was used to record Mueller matrices from polyacrylamide phantoms having strain-induced birefringence, sucrose-induced optical activity, and polystyrene microspheres-induced scattering. Decomposition of the Mueller matrices recorded in the forward detection geometry from these phantoms with controlled polarization properties yielded reasonable estimates for delta and psi parameters. The confounding effects of scattering, the propagation path of multiple scattered photons, and detection geometry on the estimated values for delta and psi were further investigated using polarization-sensitive Monte Carlo simulations. The results show that in the forward detection geometry, the effects of scattering induced linear retardance and diattenuation are weak, and the decomposition of the Mueller matrix can retrieve the intrinsic values for delta and psi with reasonable accuracy. The ability of this approach to extract the individual intrinsic polarimetry characteristics should prove valuable in diagnostic photomedicine, for example, in quantifying the small optical rotations due to the presence of glucose in tissue and for monitoring changes in tissue birefringence as a signature of tissue abnormality.
Chaikovskaya, Ludmila I; Zege, Eleonora P; Katsev, Iosif L; Hirschberger, Markus; Oppel, Ulrich G
2009-01-20
Quite recently, a semi-analytical approach to the sounding of multiply scattering media (clouds, seawaters) using multiple-field-of-view and CCD lidars with polarization devices was developed. The angular distributions of polarized components of the lidar returns from multiply scattering media computed on the basis of this theory using the small-angle approximation are presented and discussed. The semi-analytical nature of the solution makes the computation procedure faster. The obtained data are compared with results provided by the most advanced Monte Carlo algorithms for simulation of modern lidar performance. The good agreement between data provided by the semi-analytical approach and Monte Carlo computations assures one that these approaches can serve as a reliable theoretical base for interpretation and inversion of cloud lidar sounding data obtained with polarized lidars, including polarized multiple-field-of-view and CCD lidars.
Ibraeva, E. T.; Imambekov, O.
2015-07-15
Differential cross sections for elastic p{sup 6,8}He and p{sup 8,9}Li scattering at energies between 60 and 70 MeV per nucleon and at the energy of 700 MeV per nucleon were calculated. The calculations in question were performed with the wave functions found on the basis of the α–n–n (for {sup 6}He), α–t–n (for {sup 8}Li), and α–t–2n (for {sup 9}Li) three-body models and with the density from the large-scale shell model for the {sup 8}He nucleus. The respective matrix elements were derived either upon taking fully into account the multiple-scattering operator or in the optical-limit approximation. A comparison of the results of the precise and approximate calculations made it possible to estimate reliably the contribution of higher multiplicity collisions to the differential cross sections.
Hudson, E.A.; Rehr, J.J.; Bucher, J.J.
1995-11-15
A theoretical study of the uranium {ital L}{sub 3}-edge x-ray absorption near-edge structure (XANES) is presented for several uranium compounds, including oxides, intermetallics, uranyl fluoride, and {alpha}-uranium. Calculations were performed using FEFF6, an {ital ab} {ital initio} multiple-scattering (MS) code that includes the most important features of current theories. The results, which account for both the fine structure {chi} and the atomiclike background {mu}{sub 0} of the absorption coefficient {mu}, are compared to new and previously measured experimental spectra, reavealing very good agreement for most systems. For several compounds, a more detailed theoretical analysis determined the influence of cluster size and scattering order upon the calculated spectra. Results indicate that MS paths and scattering paths that include rather distant atoms make significant contributions for UO{sub 2}, whereas XANES for crystals with lower symmetry and density can be modeled using only shorter single-scattering paths. In most cases, assumption of a screened final state in the calculation gives better agreement with experiment than use of an unscreened final state. The successful modeling of spectra for a variety of different uranium compounds, with differing spectral features, indicates that the semirelativistic treatment of XANES used here is adequate even for heavy elements. The well-known resonance, observed experimentally for uranyl (UO{sub 2}{sup 2+}) compounds {approx}15 eV above the white line, is successfully modeled here for the first time, using multiple-scattering paths within the O-U-O axial bonds. Overlapping muffin-tin spheres were required in the calculation, probably as a result of the short uranyl axial bonds.
NASA Astrophysics Data System (ADS)
Chang, Xin
This dissertation proposal is concerned with the use of fast and broadband full-wave electromagnetic methods for modeling high speed interconnects (e.g, vertical vias and horizontal traces) and passive components (e.g, decoupling capacitors) for structures of PCB and packages, in 3D IC, Die-level packaging and SIW based devices, to effectively modeling the designs signal integrity (SI) and power integrity (PI) aspects. The main contributions finished in this thesis is to create a novel methodology, which hybridizes the Foldy-Lax multiple scattering equations based fast full wave method, method of moment (MoM) based 1D technology, modes decoupling based geometry decomposition and cavity modes expansions, to model and simulate the electromagnetic scattering effects for the irregular power/ground planes, multiple vias and traces, for fast and accurate analysis of link level simulation on multilayer electronic structures. For the modeling details, the interior massively-coupled multiple vias problem is modeled most-analytically by using the Foldy-Lax multiple scattering equations. The dyadic Green's functions of the magnetic field are expressed in terms of waveguide modes in the vertical direction and vector cylindrical wave expansions or cavity modes expansions in the horizontal direction, combined with 2D MoM realized by 1D technology. For the incident field of the case of vias in the arbitrarily shaped antipad in finite large cavity/waveguide, the exciting and scattering field coefficients are calculated based on the transformation which converts surface integration of magnetic surface currents in antipad into 1D line integration of surface charges on the vias and on the ground plane. Geometry decomposition method is applied to model and integrate both the vertical and horizontal interconnects/traces in arbitrarily shaped power/ground planes. Moreover, a new form of multiple scattering equations is derived for solving coupling effects among mixed metallic
NASA Astrophysics Data System (ADS)
Omari, Khalid
This thesis investigated the development and assessment of a simple parameterization of the multiple scattering within canopies assuming the single scattering field is known and the background beneath the canopy is completely absorbing. The parameterization is based on the concept of spectral invariants related to recollision and escape probabilities from vegetation canopies. The simplified approach is evaluated against detailed 3-D ray tracing model, PARCINOPY, as well as reference datasets from the Radiation Modelling Intercomparison Experiment On-Line Checker. Comparison with homogenous canopies simulated with PARCINOPY showed that the model's performance is best in both the solar principal and perpendicular planes at low and mid LAI levels for all solar zenith angles. The comparison to the On-line Checker datasets shows also that the model is a suitable approach to describe the multiple scattering components of physically based models. This simple parameterization is then incorporated into the Four Scale Linear Model for Anisotropie Reflectance (FLAIR) canopy radiative transfer model to enhance the description of the spectrally dependant multiple scattered radiation field of a forest canopy. The contribution of the multiply scattered radiation between the canopy and the background is also added to the parameterization of the multiple scattering component. The validation of the new version of the FLAIR model was performed using the multi-angular data sets obtained by the airborne sensor POLarization and Directionality of the Earth's Reflectances (POLDER) during the BOReal Ecosystem-Atmosphere Study (BOREAS) campaign of 1994. The results indicate that this approach is well suited to the FLAIR model. It is also demonstrated that the multiple scattering problem can be parameterized by a limited number of architectural parameters and the leaf scattering coefficient. Finally, the combined canopy-leaf PROFLAIR (PROSPECT + FLAIR) model is used to investigate the
NASA Astrophysics Data System (ADS)
Reuter, Maximilian; Bovensmann, Heinrich; Buchwitz, Michael; Burrows, John P.; Heymann, Jens; Noël, Stefan; Rozanov, Vladimir; Schneising, Oliver
2017-04-01
Carbon dioxide is the most important anthropogenic greenhouse gas. Its global increasing concentration in the Earth's atmosphere is the main driver for global climate change. In spite of its importance, there are still large uncertainties on its global sources and sinks. Satellite measurements have the potential to reduce these surface flux uncertainties. However, the demanding accuracy requirements usually involve the need for precise radiative transfer calculations in a scattering atmosphere. These can be computationally so expensive that hundreds or thousands of CPU cores are need to keep up with the data stream of an instrument like OCO-2. Future instruments will further increase the amount of soundings at least by an order of magnitude. A radiative transfer model has been developed approximating scattering effects by multiple scattering at an optically thin scattering layer reducing the computational costs by several orders of magnitude. The model can be used to simulate the radiance in all three OCO-2 spectral bands allowing the simultaneous retrieval of CO2, H2O, and chlorophyll fluorescence. First retrieval results for OCO-2 data will be presented.
NASA Astrophysics Data System (ADS)
Dixon, David A.; Hughes, H. Grady
2017-09-01
This paper presents a validation test comparing angular distributions from an electron multiple-scattering experiment with those generated using the MCNP6 Monte Carlo code system. In this experiment, a 13- and 20-MeV electron pencil beam is deflected by thin foils with atomic numbers from 4 to 79. To determine the angular distribution, the fluence is measured down range of the scattering foil at various radii orthogonal to the beam line. The characteristic angle (the angle for which the max of the distribution is reduced by 1/e) is then determined from the angular distribution and compared with experiment. Multiple scattering foils tested herein include beryllium, carbon, aluminum, copper, and gold. For the default electron-photon transport settings, the calculated characteristic angle was statistically distinguishable from measurement and generally broader than the measured distributions. The average relative difference ranged from 5.8% to 12.2% over all of the foils, source energies, and physics settings tested. This validation illuminated a deficiency in the computation of the underlying angular distributions that is well understood. As a result, code enhancements were made to stabilize the angular distributions in the presence of very small substeps. However, the enhancement only marginally improved results indicating that additional algorithmic details should be studied.
NASA Astrophysics Data System (ADS)
Ikegami, Seiji
2017-09-01
The switching model (PSM) developed in the previous paper is extended to obtain an ;extended switching model (ESM). In the ESM, the mixt electronic-and-nuclear energy-loss region, in addition to the electronic and nuclear energy-loss regions in PSM, is taken into account analytically and appropriately. This model is combined with a small-angle multiple scattering range theory considering both nuclear and electronic stopping effects developed by Marwick-Sigmund and Valdes-Arista to formulate a improved range theory. The ESM is also combined with the multiple scattering theory with non-small angle approximation by Goudsmit-Saunderson. Furthermore, we applied ESM to lateral spread model of Marwick-Sigmund. Numerical calculations of the entire distribution functions including one of the mixt region are roughly and approximately possible. However, exact numerical calculation may be impossible. Consequently, several preliminary numerical calculations of the electronic, mixt, and nuclear regions are performed to examine their underlying behavior with respect to the incident energy, the scattering angle, the outgoing projectile intensity, and the target thickness. We show the numerical results not only of PSM and but also of ESM. Both numerical results are shown in the present paper for the first time. Since the theoretical relations are constructed using reduced variables, the calculations are made only on the case of C colliding on C.
Eisenbach, Markus; Larkin, Jeff; Lutjens, Justin; Rennich, Steven; Rogers, James H.
2016-07-12
The Locally Self-consistent Multiple Scattering (LSMS) code solves the first principles Density Functional theory Kohn–Sham equation for a wide range of materials with a special focus on metals, alloys and metallic nano-structures. It has traditionally exhibited near perfect scalability on massively parallel high performance computer architectures. In this paper, we present our efforts to exploit GPUs to accelerate the LSMS code to enable first principles calculations of O(100,000) atoms and statistical physics sampling of finite temperature properties. We reimplement the scattering matrix calculation for GPUs with a block matrix inversion algorithm that only uses accelerator memory. Finally, using the Cray XK7 system Titan at the Oak Ridge Leadership Computing Facility we achieve a sustained performance of 14.5PFlop/s and a speedup of 8.6 compared to the CPU only code.
Eisenbach, Markus; Larkin, Jeff; Lutjens, Justin; ...
2016-07-12
The Locally Self-consistent Multiple Scattering (LSMS) code solves the first principles Density Functional theory Kohn–Sham equation for a wide range of materials with a special focus on metals, alloys and metallic nano-structures. It has traditionally exhibited near perfect scalability on massively parallel high performance computer architectures. In this paper, we present our efforts to exploit GPUs to accelerate the LSMS code to enable first principles calculations of O(100,000) atoms and statistical physics sampling of finite temperature properties. We reimplement the scattering matrix calculation for GPUs with a block matrix inversion algorithm that only uses accelerator memory. Finally, using the Craymore » XK7 system Titan at the Oak Ridge Leadership Computing Facility we achieve a sustained performance of 14.5PFlop/s and a speedup of 8.6 compared to the CPU only code.« less
Eisenbach, Markus; Larkin, Jeff; Lutjens, Justin; Rennich, Steven; Rogers, James H.
2016-07-12
The Locally Self-consistent Multiple Scattering (LSMS) code solves the first principles Density Functional theory Kohn–Sham equation for a wide range of materials with a special focus on metals, alloys and metallic nano-structures. It has traditionally exhibited near perfect scalability on massively parallel high performance computer architectures. In this paper, we present our efforts to exploit GPUs to accelerate the LSMS code to enable first principles calculations of O(100,000) atoms and statistical physics sampling of finite temperature properties. We reimplement the scattering matrix calculation for GPUs with a block matrix inversion algorithm that only uses accelerator memory. Finally, using the Cray XK7 system Titan at the Oak Ridge Leadership Computing Facility we achieve a sustained performance of 14.5PFlop/s and a speedup of 8.6 compared to the CPU only code.
Hesford, Andrew J.; Astheimer, Jeffrey P.; Greengard, Leslie F.; Waag, Robert C.
2010-01-01
A multiple-scattering approach is presented to compute the solution of the Helmholtz equation when a number of spherical scatterers are nested in the interior of an acoustically large enclosing sphere. The solution is represented in terms of partial-wave expansions, and a linear system of equations is derived to enforce continuity of pressure and normal particle velocity across all material interfaces. This approach yields high-order accuracy and avoids some of the difficulties encountered when using integral equations that apply to surfaces of arbitrary shape. Calculations are accelerated by using diagonal translation operators to compute the interactions between spheres when the operators are numerically stable. Numerical results are presented to demonstrate the accuracy and efficiency of the method. PMID:20136208
NASA Astrophysics Data System (ADS)
Larin, Kirill V.; Ghosn, M. G.
2006-12-01
The passive diffusion of drugs through the epithelial surfaces of an eye (the most widespread method for medical treatment of various diseases) is considered. The permeability of water and drugs through rabbit cornea was measured in the isolated cornea (separate from an eye) and in the whole cornea. The permeability coefficients of water and dexamethasone were estimated by the method of optical coherence tomography (OCT). Because multiple photon scattering introduces noise and distortions to the OCT signal, measurements were performed at depths up to 500 μm where most likely single scattering of light occurs in cornea. It is shown that the permeability coefficients in the isolated and whole cornea strongly differ from each other. For example, the water permeability in the isolated and whole cornea is (7.09±0.12)×10-5 and (1.71±0.51)×10-5 cm s-1, respectively.
USDA-ARS?s Scientific Manuscript database
A highly sensitive immunoassay based on surface-enhanced Raman scattering (SERS) spectroscopy has been developed for multiplex detection of surface envelope and capsid antigens of the viral zoonotic pathogens West Nile virus (WNV) and Rift Valley fever virus (RVFV). Detection was mediated by antibo...
NASA Astrophysics Data System (ADS)
Jadach, S.; Ward, B. F. L.
1996-07-01
We present the theoretical basis and sample Monte Carlo data for the YFS exponentiated O(α) calculation of polarized Mo/ller scattering at c.m.s. energies large compared to 2me. Both longitudinal and transverse polarizations are discussed. Possible applications to Mo/ller polarimetry at the SLD are thus illustrated.
NASA Astrophysics Data System (ADS)
Kravtsenyuk, Olga V.; Lyubimov, Vladimir V.; Kalintseva, Natalie A.
2006-11-01
A reconstruction method elaborated for the optical diffusion tomography of the internal structure of objects containing absorbing and scattering inhomogeneities is considered. The method is developed for studying objects with fluorescing inhomogeneities and can be used for imaging of distributions of artificial fluorophores whose aggregations indicate the presence of various diseases or pathological deviations.
NASA Astrophysics Data System (ADS)
Madhulatha, A.; George, John P.; Rajagopal, E. N.
2017-03-01
Incorporation of cloud- and precipitation-affected radiances from microwave satellite sensors in data assimilation system has a great potential in improving the accuracy of numerical model forecasts over the regions of high impact weather. By employing the multiple scattering radiative transfer model RTTOV-SCATT, all-sky radiance (clear sky and cloudy sky) simulation has been performed for six channel microwave SAPHIR (Sounder for Atmospheric Profiling of Humidity in the Inter-tropics by Radiometry) sensors of Megha-Tropiques (MT) satellite. To investigate the importance of cloud-affected radiance data in severe weather conditions, all-sky radiance simulation is carried out for the severe cyclonic storm `Hudhud' formed over Bay of Bengal. Hydrometeors from NCMRWF unified model (NCUM) forecasts are used as input to the RTTOV model to simulate cloud-affected SAPHIR radiances. Horizontal and vertical distribution of all-sky simulated radiances agrees reasonably well with the SAPHIR observed radiances over cloudy regions during different stages of cyclone development. Simulated brightness temperatures of six SAPHIR channels indicate that the three dimensional humidity structure of tropical cyclone is well represented in all-sky computations. Improved correlation and reduced bias and root mean square error against SAPHIR observations are apparent. Probability distribution functions reveal that all-sky simulations are able to produce the cloud-affected lower brightness temperatures associated with cloudy regions. The density scatter plots infer that all-sky radiances are more consistent with observed radiances. Correlation between different types of hydrometeors and simulated brightness temperatures at respective atmospheric levels highlights the significance of inclusion of scattering effects from different hydrometeors in simulating the cloud-affected radiances in all-sky simulations. The results are promising and suggest that the inclusion of multiple scattering
NASA Astrophysics Data System (ADS)
Bachmann, Charles M.; Peck, Douglas S.; Ambeau, Brittany; Harms, Justin; Schultz, Malachi
2015-09-01
Approximate solutions to the Radiative transfer equation for granular media have been previously developed1. To apply these models to coastal sediments, modifications are needed to account for observed phenomenology. This study uses a new hyperspectral goniometer system, the Goniometer of the Rochester Institute of Technology (GRIT), designed for both field and laboratory settings, to compare observed bidirectional reflectance distribution function (BRDF) measurements with outcomes predicted by the approximate radiative transfer solutions. In previous laboratory studies,2 using a more limited hyperspectral goniometer observing in the principle plane, we had seen that the degree of optical contrast between coastal sand constituents was indicative of whether these models accurately predict the observed BRDF dependence on sediment density. Our earlier measurements using another field hyperspectral goniometer also demonstrated results consistent with the laboratory measurements as well as with CASI- 1500 airborne hyperspectral measurements3,4. In our earlier work,2 the presence of highly contrasting constituents (translucent quartz and more opaque fractions composed of minerals such as magnetite) led to greater reflectance as density decreased, exactly the opposite of what was anticipated from radiative transfer models for a more uniform sand. The present study shows that the illumination zenith angle also plays a significant role in whether or not BRDF dependency exhibits behavior predicted by current radiative transfer theory, and this distinction is directly related to the degree of multiple scattering, which depends on the illumination zenith angle. We also investigate a novel sampling paradigm that constrains the measurements to constant phase angle and reveals when the multiple scattering component of models departs from the assumptions of current theory. For the multiple scattering term, we also propose and analyze a simple modification which removes the
NASA Astrophysics Data System (ADS)
Dobbelaere, D.; De Zutter, D.; Van Hese, J.; Sercu, J.; Boonen, T.; Rogier, H.
2015-12-01
In the context of hybrid formulations, the Poincaré-Steklov operator acting on traces of solutions to the vector Helmholtz equation in a heterogeneous interior domain with a smooth boundary is regularized by a well-known boundary integral operator related to the homogeneous exterior domain. For the first time, this property allows us to simultaneously construct a Calderón multiplicative preconditioner for the discretized operator and for a 3-D hybrid finite/boundary element method formulation, applicable to electromagnetic scattering problems. Numerical examples demonstrate the effectiveness of this novel preconditioning scheme, even for heterogeneous domains with non-smooth boundaries.
NASA Astrophysics Data System (ADS)
Houser, B.; Ingalls, R.; Rehr, J. J.
1992-04-01
Rehr and Albers have shown that the exact x-ray-absorption fine-structure (XAFS) propagator may be expanded in a separable matrix form, and that the lowest-order term in the expansion yields XAFS formulas that contain spherical-wave corrections, yet retain the simplicity of the plane-wave approximation. This separable-spherical-wave approximation was used to model the multiple-scattering contributions to the XAFS spectrum of rhenium trioxide. We report a modest improvement over the plane-wave approximation.
NASA Astrophysics Data System (ADS)
Konovalov, Aleksandr B.; Vlasov, V. V.; Kalintsev, A. G.; Kravtsenyuk, Olga V.; Lyubimov, Vladimir V.
2006-11-01
The inverse problem of diffuse optical tomography (DOT) is reduced by the method of photon average trajectories (PAT) to the solution of the integral equation integrated along the conditional mean statistical photon trajectory. The PAT bending near the flat boundary of a scattering medium is estimated analytically. These estimates are used to determine the analytic statistical characteristics of photon trajectories for the flat layer geometry. The inverse DOT problem is solved by using the multiplicative algebraic algorithm modified to improve the convergence of the iteration reconstruction process. The numerical experiment shows that the modified PAT method permits the reconstruction of near-surface optical inhomogeneities virtually without distortions.
1983-12-01
function, pdf, of x, which is Rayleigh 0distributed is given by [Ref 10:1481: fx) = 2x/ m exp(-x 2m ) , x>0 (111-37) Not only is this amplitude pdf...form is obtained. s a (11:2-47) m m The above Rayleigh approximation is good only for many scatterers. If any one of the individual scatterers is much...joint pdf is given by [Ref 8:117]: 1 Af(am’ɟt ) A - exp( Q ) (V-18) M 2. s.7 s%A -i Il t where A A A AA- A Q 2=man] + t -O’ 2- 2 r am-Crm [at- 2(1 - r) sA
Jadach, S. |; Ward, B.F. |
1996-07-01
We present the theoretical basis and sample Monte Carlo data for the YFS exponentiated {ital O}({alpha}) calculation of polarized Mo/ller scattering at c.m.s. energies large compared to 2{ital m}{sub {ital e}}. Both longitudinal and transverse polarizations are discussed. Possible applications to Mo/ller polarimetry at the SLD are thus illustrated. {copyright} {ital 1996 The American Physical Society.}
Wojtkiewicz, S; Liebert, A; Rix, H; Zołek, N; Maniewski, R
2009-02-07
Recently, a method for the estimation of speed distribution of particles moving in an optically turbid medium has been proposed. The method allows potentially absolute measurement of speed of the particles and can be applied in laser-Doppler perfusion measurements. However, the decomposition technique was limited to short source-detector separations for which the assumption that one photon is Doppler scattered not more than once is fulfilled. In the present paper we show a generalized decomposition technique in which photons can be scattered more than once. We show the theoretical background for decomposition in such a case. We apply a decomposition method for the analysis of laser-Doppler spectra obtained by Monte Carlo simulations. This analysis allows showing noise limits in which the technique can be effectively applied in analysis of measured spectra. We propose an approximated scattering model based on the assumption that for one photon consecutive Doppler scattering events occur on particles moving with the same speed, and we show that this approximation does not influence significantly the uncertainty of the resulting speed distribution. The proposed decomposition procedure is validated in measurements on a physical flow model. The decomposition procedure is also validated by analysis of spectra measured on a physical phantom using laser-Doppler flow meter (Oxford Optronix, UK). A diluted solution of milk was pumped through a tube fixed in an optically turbid material with speed varying from 0 mm s(-1) to 4 mm s(-1). We observed a linear relation between actual speed of milk solution and speed estimated from results of spectra decomposition.
Sindona, A; Pisarra, M; Maletta, S; Riccardi, P; Falcone, G
2010-12-01
Resonant neutralization of hyperthermal energy Na(+) ions impinging on Cu(100) surfaces is studied, focusing on two specific collision events: one in which the projectile is reflected off the surface, the other in which the incident atom penetrates the outer surface layers initiating a series of scattering processes, within the target, and coming out together with a single surface atom. A semi-empirical model potential is adopted that embeds: (i) the electronic structure of the sample, (ii) the central field of the projectile, and (iii) the contribution of the Cu atom ejected in multiple scattering events. The evolution of the ionization orbital of the scattered atom is simulated, backwards in time, using a wavepacket propagation algorithm. The output of the approach is the neutralization probability, obtained by projecting the time-reversed valence wavefunction of the projectile onto the initially filled conduction band states. The results are in agreement with available data from the literature (Keller et al 1995 Phys. Rev. Lett. 75 1654) indicating that the motion of surface atoms, exiting the targets with kinetic energies of the order of a few electronvolts, plays a significant role in the final charge state of projectiles.
Xia, H. Patterson, R.; Feng, Y.; Shrestha, S.; Conibeer, G.
2014-08-11
The rates of charge carrier relaxation by phonon emission are of substantial importance in the field of hot carrier solar cell, primarily in investigation of mechanisms to slow down hot carrier cooling. In this work, energy and momentum resolved deformation potentials relevant to electron-phonon scattering are computed for wurtzite InN and GaN as well as an InN/GaN multiple quantum well (MQW) superlattice using ab-initio methods. These deformation potentials reveal important features such as discontinuities across the electronic bandgap of the materials and variations over tens of eV. The energy dependence of the deformation potential is found to be very similar for wurtzite nitrides despite differences between the In and Ga pseudopotentials and their corresponding electronic band structures. Charge carrier relaxation by this mechanism is expected to be minimal for electrons within a few eV of the conduction band edge. However, hole scattering at energies more accessible to excitation by solar radiation is possible between heavy and light hole states. Moderate reductions in overall scattering rates are observed in MQW relative to the bulk nitride materials.
NASA Technical Reports Server (NTRS)
Iguchi, Toshio; Meneghini, Robert
1993-01-01
Air-borne radar measurements of thunderstorms were made as part of the CaPE (Convection and Precipitation/Electrification) experiment in Florida in July 1991. The radar has two channels, X-band (10 GHz) and Ka-band (34.5 GHz), and is capable of measuring cross-polarized returns as well as co-polarized returns. In stratiform rain, the cross-polarized components can be observed only at the bright band region and from the surface reflection. The linear depolarization ratios (LDR's) measured at X-band and Ka-band at the bright band are nearly equal. In convective rain, however, the LDR in Ka-band often exceeds the X-band LDR by several dB, and sometimes by more than 10 dB, reaching LDR values of up to -5 dB over heavy convective rain. For randomly oriented hydrometeors, such high LDR values cannot be explained by single scattering from non-spherical scattering particles alone. Because the LDR by single backscatter depends weakly on the wavelength, the difference between the Ka-band and X-band LDR's suggests that multiple scattering effects prevail in the Ka-band LDR. In order to test this inference, the magnitude of the cross-polarized component created by double scattering was calculated using the parameters of the airborne radar, which for both frequencies has beamwidths of 5.1 degrees and pulse widths of 0.5 microsecond. Uniform rain beyond the range of 3 km is assumed.
Ren, X.; Senftleben, A.; Pflueger, T.; Dorn, A.; Ullrich, J.; Colgan, J.; Pindzola, M. S.; Al-Hagan, O.; Madison, D. H.; Bray, I.; Fursa, D. V.
2010-09-15
Absolutely normalized (e,2e) measurements for H{sub 2} and He covering the full solid angle of one ejected electron are presented for 16 eV sum energy of both final state continuum electrons. For both targets rich cross-section structures in addition to the binary and recoil lobes are identified and studied as a function of the fixed electron's emission angle and the energy sharing among both electrons. For H{sub 2} their behavior is consistent with multiple scattering of the projectile as discussed before [Al-Hagan et al., Nature Phys. 5, 59 (2009)]. For He the binary and recoil lobes are significantly larger than for H{sub 2} and partly cover the multiple scattering structures. To highlight these patterns we propose a alternative representation of the triply differential cross section. Nonperturbative calculations are in good agreement with the He results and show discrepancies for H{sub 2} in the recoil peak region. For H{sub 2} a perturbative approach reasonably reproduces the cross-section shape but deviates in absolute magnitude.
NASA Astrophysics Data System (ADS)
Ren, X.; Senftleben, A.; Pflüger, T.; Dorn, A.; Colgan, J.; Pindzola, M. S.; Al-Hagan, O.; Madison, D. H.; Bray, I.; Fursa, D. V.; Ullrich, J.
2010-09-01
Absolutely normalized (e,2e) measurements for H2 and He covering the full solid angle of one ejected electron are presented for 16 eV sum energy of both final state continuum electrons. For both targets rich cross-section structures in addition to the binary and recoil lobes are identified and studied as a function of the fixed electron’s emission angle and the energy sharing among both electrons. For H2 their behavior is consistent with multiple scattering of the projectile as discussed before [Al-Hagan , Nature Phys.PLRAAN1745-247310.1038/nphys1135 5, 59 (2009)]. For He the binary and recoil lobes are significantly larger than for H2 and partly cover the multiple scattering structures. To highlight these patterns we propose a alternative representation of the triply differential cross section. Nonperturbative calculations are in good agreement with the He results and show discrepancies for H2 in the recoil peak region. For H2 a perturbative approach reasonably reproduces the cross-section shape but deviates in absolute magnitude.
Lemeshko, Mikhail; Friedrich, Bretislav
2010-08-15
We present an analytic model of the refractive index for matter waves propagating through atomic or molecular gases. The model, which combines the Wentzel-Kramers-Brillouin (WKB) treatment of the long-range attraction with the Fraunhofer model treatment of the short-range repulsion, furnishes a refractive index in compelling agreement with recent experiments of Jacquey et al. [Phys. Rev. Lett. 98, 240405 (2007)] on Li atom matter waves passing through dilute noble gases. We show that the diffractive contribution, which arises from scattering by a two-dimensional 'hard core' of the potential, is essential for obtaining a correct imaginary part of the refractive index.
Sica, R J; Haefele, A
2016-02-01
Lidar measurements of the atmospheric water vapor mixing ratio provide an excellent complement to radiosoundings and passive, ground-based remote sensors. Lidars are now routinely used that can make high spatial-temporal resolution measurements of water vapor from the surface to the stratosphere. Many of these systems can operate during the day and night, with operation only limited by clouds thick enough to significantly attenuate the laser beam. To enhance the value of these measurements for weather and climate studies, this paper presents an optimal estimation method (OEM) to retrieve the water vapor mixing ratio, aerosol optical depth profile, Ångstrom exponent, lidar constants, detector dead times, and measurement backgrounds from multichannel vibrational Raman-scatter lidars. The OEM retrieval provides the systematic uncertainties due to the overlap function, calibration factor, air density and Rayleigh-scatter cross sections, in addition to the random uncertainties of the retrieval due to measurement noise. The OEM also gives the vertical resolution of the retrieval as a function of height, as well as the height to which the contribution of the a priori is small. The OEM is applied to measurements made by the Meteoswiss Raman Lidar for Meteorological Observations (RALMO) in the day and night for clear and cloudy conditions. The retrieved water vapor mixing ratio is in excellent agreement with both the traditional lidar retrieval method and coincident radiosoundings.
NASA Astrophysics Data System (ADS)
Zhang, Ting; Chaumet, Patrick C.; Sentenac, Anne; Belkebir, Kamal
2016-12-01
The singular vectors of the time reversal operator (décomposition de l'opérateur de retournement temporel, time reversal operator decomposition (DORT) processing) are often used for localizing small echogeneous targets in a cluttered environment. In this work, we show that they can also improve the imaging of relatively large and contrasted targets in a homogeneous environment. It is observed that non-linear inversion schemes, minimizing iteratively the discrepancy between experimental data and simulated field scattered by target estimates, are more efficient when the illuminations correspond to the DORT singular vectors. In addition, DORT preprocessing permits a drastic diminution of the data load and computer burden. This study is conducted with experimental microwave data of targets with size comparable or greater than the wavelength.
Cheng, M.C.; Rich, A.M.; Armstrong, R.S.; Ellis, P.J.; Lay, P.A.
1999-12-13
Cytochrome c (cyt c) is a small heme protein (MW 12 384) that functions as a biological electron-transfer agent. It consists of a single polypeptide chain and a prosthetic heme group and provides a pathway for the transfer of electrons from cyt c reductase to cyt c oxidase in the mitochondrial respiratory chain (oxidative phosphorylation). The protein participates in oxidation-reduction reactions with the heme iron alternating between the oxidized (ferric, Fe{sup III}) state and the reduced (ferrous, Fe{sup II}) state. X-ray absorption fine structure (XAFS) data were obtained from frozen aqueous solutions (10 K) of horse heart ferri- and ferrocyt c. Models of the structure about the Fe center were refined to optimize the fit between the observed XAFS in the range 0 {le} k {le} 16.3 {angstrom}{sup {minus}1} and the XAFS calculated using both single-scattering (SS) and multiple-scattering (MS) calculations. The bond lengths obtained are more accurate and precise than those determined previously for cyt c from various species using X-ray crystallography. The Fe-N bond lengths are 1.98--1.99 {angstrom} for both oxidation states of cyt c. The Fe-S bond of derricyt c (2.33 {angstrom}) is significantly longer than that of ferrocyt c (2.29 {angstrom}). The small changes in the bond lengths are consistent with the small reorganizational energy required for the fast electron-transfer reaction of cyt c.
Gao, Jiaxue; Ma, Lan; Lei, Zhen; Wang, Zhenxin
2016-03-07
The mapping of specific single nucleotide polymorphisms (SNPs) in patients' genome is a critical process for the development of personalized therapy. In this work, a DNA microarray-based resonance light scattering (RLS) assay has been developed for multiplexed detection of breast cancer related SNPs with high sensitivity and selectivity. After hybridization of the desired target single-stranded DNAs (ssDNAs) with the ssDNA probes on a microarray, the polyvalent ssDNA modified 13 nm gold nanoparticles (GNPs) are employed to label the hybridization reaction through the formation of a three-stranded DNA system. The H2O2-mediated enlargement of GNPs is then used to enhance the RLS signal. The microarray-based RLS assay provides a detection limit of 10 pM (S/N = 3) for the target ssDNA and determines an allele frequency as low as 1.0% in the target ssDNA cocktail. Combined with an asymmetric PCR technique, the proposed assay shows good accuracy and sensitivity in profiling 4 SNPs related to breast cancer of three selected cell lines.
Yang, Tianxi; Zhao, Bin; Hou, Ruyan; Zhang, Zhiyun; Kinchla, Amanda J; Clark, John M; He, Lili
2016-10-06
Understanding pesticide penetration is important for effectively applying pesticides and in reducing pesticide exposures from food. This study aims to evaluate multiclass systemic and nonsystemic pesticide penetration in 3 representative fresh produce (apples, grapes, and spinach leaves). Surface-enhanced Raman scattering mapping was applied for in situ and real-time tracking of pesticide penetration over time. The results show that 100 mg/L of systemic pesticides, thiabendazole and acetamiprid, penetrated more rapidly and deeply with maximum depth around 220 μm after 48-h exposure into the tested fresh produce than 100 mg/L of nonsystemic pesticides, ferbam and phosmet, with maximum depth about 80 μm. The fact that 2 nonsystemic pesticides were also able to penetrate over time into all 3 fresh produce tested may raise additional food safety concerns. Comparatively, grapes were generally more resistant for pesticide penetration with all pesticides penetration depth below 80 μm compared to apples and spinach leaves. The information obtained here could provide technical support and guidance for accurate, effective, and safe application of pesticides and for the reduction of pesticide exposure from fresh produce.
Eisenbach, Markus; Larkin, Jeff; Lutjens, Justin; Rennich, Steven; Rogers, James H
2016-01-01
The Locally Self-consistent Multiple Scattering (LSMS) code solves the first principles Density Functional theory Kohn-Sham equation for a wide range of materials with a special focus on metals, alloys and metallic nano-structures. It has traditionally exhibited near perfect scalability on massively parallel high performance computer architectures. We present our efforts to exploit GPUs to accelerate the LSMS code to enable first principles calculations of O(100,000) atoms and statistical physics sampling of finite temperature properties. Using the Cray XK7 system Titan at the Oak Ridge Leadership Computing Facility we achieve a sustained performance of 14.5PFlop/s and a speedup of 8.6 compared to the CPU only code.
Cavalier, J.; Lemoine, N.; Bonhomme, G.; Tsikata, S.; Honore, C.; Gresillon, D.
2012-08-15
The effect of the collective light scattering diagnostic transfer function is considered in the context of the dispersion relation of the unstable E Multiplication-Sign B mode previously reported. This transfer function is found to have a contribution to the measured frequencies and mode amplitudes which is more or less significant depending on the measurement wavenumbers and angles. After deconvolution, the experimental data are found to be possibly compatible with the idea that the mode frequency in the jet frame (after subtraction of the Doppler effect due to the plasma motion along the thruster axis) is independent of the orientation of the wave vector in the plane orthogonal to the local magnetic field.
NASA Technical Reports Server (NTRS)
Marconi, M. L.; Mendis, D. A.
1984-01-01
A self-consistent model of a dirty, clathrate cometary nucleus is extended to account for diffuse radiation fields caused by multiple scattering and thermal reradiation of the solar continuum by dust. The model is configured to fit conditions expected for the various spacecraft which will encounter Halley's comet at 0.89 AU. The atmosphere is assumed a chemically reactive dust-gas mixture in quasi-steady spherically symmetric expansion. The effect of electron-neutral ion collisions is accounted for, along with rate constants of the various species of clathrate ice particles and radiative transfer of the solar input in the UV, visible and near-IR intervals. The opacity of the circumnuclear dust is projected to be an order of magnitude greater than previous estimates, which severely impacts the potential visibility of the nucleus to the cameras of the flyby satellites.
NASA Astrophysics Data System (ADS)
Yon, J.; Therssen, E.; Liu, F.; Bejaoui, S.; Hebert, D.
2015-05-01
Laser-induced incandescence (LII) is a powerful and robust optical method for in situ determination of soot volume fraction and/or soot absorption/emission properties in flames and engine exhaust. The laser-induced signal is interpreted as thermal emission based on the Planck law. Up to now, the evaluation and interpretation of LII signal have been largely based on contributions from isolated primary particles that are assumed much smaller than wavelengths. In the present paper, the morphology, wavelength, and aggregate size-dependent effects of multiple scattering within fractal soot aggregates on their absorption and emission cross sections are taken into account in the evaluation of LII signal by proposing correction terms to the traditional model. The impact of accounting for the correction to soot aggregate emission due to multiple scattering on LII signal and on the two excitation wavelength-induced incandescence method for inferring the soot absorption function, E(m), is discussed. For wavelengths shorter than 532 nm, E(m, λ)/E(m, 1064 nm) increases more significantly with decreasing wavelength. For wavelengths longer than 532 nm, the wavelength dependence of E(m, λ)/E(m, 1064 nm) becomes very small and can be neglected. The proposed corrections, along with the soot morphology, are applied to re-analyze the experimental data of Bejaoui et al. (Appl Phys B Lasers Opt, 116:313, 2014) for deriving the relative soot absorption function variation with wavelength at different locations in a rich premixed methane flat flame at atmospheric pressure. The present analysis showed that the soot absorption function varies with the height above the burner exit and can be correlated with the degree of soot maturation.
Scheinost, A.C.; Sparks, D.L.
2000-03-15
Spectroscopic and microscopic studies have shown that Ni and Co sorption by clay minerals may proceed via formation of surface precipitates. Several studies employing X-ray absorption fine structure (XAFS) spectroscopy suggested the formation of turbostratic, a-type metal hydroxides, of layered double hydroxides (LDH) with Al-for-metal substitution, and of 1:1 or 2:1 phyllosilicates. Distinction of these phases is difficult because they have low crystallinity and/or a small mass compared to the sorbents, and because they have similar metal-metal distances in their hydroxide layers/sheets. Distinction of these phases is crucial, however, because they have substantially differing solubilities. In this paper the authors show that an XAFS beat pattern at about 8 {angstrom} {sup {minus}1} can be used as a fingerprint to unequivocally distinguish LDH from the {alpha}-type hydroxides and phyllosilicates. Full multiple-scattering simulations and experimental spectra of model compounds indicate that the beat pattern is due to focused multiple scattering at Me/Al ratios between 1 and 4(Me = Ni,Co). By applying the fingerprint method to new and to already published XAFS data on Ni and Co surface precipitates, the authors found that LDH preferentially forms in the presence of the Al-containing sorbents pyrophyllite, illite, kaolinite, gibbsite, and alumina above pH 7.0. However, {alpha}-type metal hydroxides form in the presence of the Al-free sorbents talc, silica, and rutile, and in the presence of the Al-containing clay minerals montmorillonite and vermiculite. The authors believe, that the high permanent charge of these latter minerals prevents or retards the release of Al. When Al is available, the formation of LDH seems to be thermodynamically and/or kinetically favored over the formation of {alpha}-type hydroxides.
NASA Astrophysics Data System (ADS)
Garnier, A.; Pelon, J.; Vaughan, M. A.; Winker, D. M.; Trepte, C. R.; Dubuisson, P.
2015-07-01
Cirrus cloud absorption optical depths retrieved at 12.05 μm are compared to extinction optical depths retrieved at 0.532 μm from perfectly co-located observations of single-layered semi-transparent cirrus over ocean made by the Imaging Infrared Radiometer (IIR) and the Cloud and Aerosol Lidar with Orthogonal Polarization (CALIOP) flying on board the CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) satellite. IIR infrared absorption optical depths are compared to CALIOP visible extinction optical depths when the latter can be directly derived from the measured apparent two-way transmittance through the cloud. An evaluation of the CALIOP multiple scattering factor is inferred from these comparisons after assessing and correcting biases in IIR and CALIOP optical depths reported in version 3 data products. In particular, the blackbody radiance taken in the IIR version 3 algorithm is evaluated, and IIR retrievals are corrected accordingly. Numerical simulations and IIR retrievals of ice crystal sizes suggest that the ratios of CALIOP extinction and IIR absorption optical depths should remain roughly constant with respect to temperature. Instead, these ratios are found to increase quasi-linearly by about 40 % as the temperature at the layer centroid altitude decreases from 240 to 200 K. It is discussed that this behavior can be explained by variations of the multiple scattering factor ηT applied to correct the measured apparent two-way transmittance for contribution of forward-scattering. While the CALIOP version 3 retrievals hold ηT fixed at 0.6, this study shows that ηT varies with temperature (and hence cloud particle size) from ηT = 0.8 at 200 K to ηT = 0.5 at 240 K for single-layered semi-transparent cirrus clouds with optical depth larger than 0.3. The revised parameterization of ηT introduces a concomitant temperature dependence in the simultaneously derived CALIOP lidar ratios that is consistent with observed changes in CALIOP
Subaihi, Abdu; Almanqur, Laila; Muhamadali, Howbeer; AlMasoud, Najla; Ellis, David I; Trivedi, Drupad K; Hollywood, Katherine A; Xu, Yun; Goodacre, Royston
2016-11-15
There has been an increasing demand for rapid and sensitive techniques for the identification and quantification of pharmaceutical compounds in human biofluids during the past few decades, and surface-enhanced Raman scattering (SERS) is one of a number of physicochemical techniques with the potential to meet these demands. In this study we have developed a SERS-based analytical approach for the assessment of human biofluids in combination with chemometrics. This novel approach has enabled the detection and quantification of the β-blocker propranolol spiked into human serum, plasma, and urine at physiologically relevant concentrations. A range of multivariate statistical analysis techniques, including principal component analysis (PCA), principal component-discriminant function analysis (PC-DFA) and partial least-squares regression (PLSR) were employed to investigate the relationship between the full SERS spectral data and the level of propranolol. The SERS spectra when combined with PCA and PC-DFA demonstrated clear differentiation of neat biofluids and biofluids spiked with varying concentrations of propranolol ranging from 0 to 120 μM, and clear trends in ordination scores space could be correlated with the level of propranolol. Since PCA and PC-DFA are categorical classifiers, PLSR modeling was subsequently used to provide accurate propranolol quantification within all biofluids with high prediction accuracy (expressed as root-mean-square error of predictions) of 0.58, 9.68, and 1.69 for serum, plasma, and urine respectively, and these models also had excellent linearity for the training and test sets between 0 and 120 μM. The limit of detection as calculated from the area under the naphthalene ring vibration from propranolol was 133.1 ng/mL (0.45 μM), 156.8 ng/mL (0.53 μM), and 168.6 ng/mL (0.57 μM) for serum, plasma, and urine, respectively. This result shows a consistent signal irrespective of biofluid, and all are well within the expected physiological
1991-04-01
practice as a "[descent] into that inner circle of the Inferno where the damned endlessly degate multiplicity for sentencing." United States v. Barnard...select the charges to be brought in a particular case"). 19 Brown v. Ohio, 432 U.S. 161, 165 (1977). 20 Whalen v. United States, 445 U.S. at 689. 21...parte Lange, 8-5 U.S. (19 Wall.) 163 (1874). Cf. Brown v. Ohio, 432 U.S. at 165 ("once the legislature has acted courts may not impose more than one
Reduction of the scattering matrix array
Sadovskyy, I. A.
2015-09-30
The scattering matrix approach is widely applied in wave engineering and quantum physics. Usually, a combination of multiple scattering matrices is used. In this article, we consider arbitrary arrays of interconnected scattering matrices and present a formal result for the reduced scattering matrix. We demonstrate this approach in two well-known scattering problems.
NASA Technical Reports Server (NTRS)
Hong, Byungsik; Maung, Khin Maung; Wilson, John W.; Buck, Warren W.
1989-01-01
The derivations of the Lippmann-Schwinger equation and Watson multiple scattering are given. A simple optical potential is found to be the first term of that series. The number density distribution models of the nucleus, harmonic well, and Woods-Saxon are used without t-matrix taken from the scattering experiments. The parameterized two-body inputs, which are kaon-nucleon total cross sections, elastic slope parameters, and the ratio of the real to the imaginary part of the forward elastic scattering amplitude, are presented. The eikonal approximation was chosen as our solution method to estimate the total and absorptive cross sections for the kaon-nucleus scattering.
ERIC Educational Resources Information Center
Young, Andrew T.
1982-01-01
The correct usage of such terminology as "Rayleigh scattering,""Rayleigh lines,""Raman lines," and "Tyndall scattering" is resolved during an historical excursion through the physics of light-scattering by gas molecules. (Author/JN)
ERIC Educational Resources Information Center
Young, Andrew T.
1982-01-01
The correct usage of such terminology as "Rayleigh scattering,""Rayleigh lines,""Raman lines," and "Tyndall scattering" is resolved during an historical excursion through the physics of light-scattering by gas molecules. (Author/JN)
NASA Astrophysics Data System (ADS)
Imitola, Jaime; Côté, Daniel; Rasmussen, Stine; Xie, X. Sunney; Liu, Yingru; Chitnis, Tanuja; Sidman, Richard L.; Lin, Charles. P.; Khoury, Samia J.
2011-02-01
Myelin loss and axonal degeneration predominate in many neurological disorders; however, methods to visualize them simultaneously in live tissue are unavailable. We describe a new imaging strategy combining video rate reflectance and fluorescence confocal imaging with coherent anti-Stokes Raman scattering (CARS) microscopy tuned to CH2 vibration of myelin lipids, applied in live tissue of animals with chronic experimental autoimmune encephalomyelitis (EAE). Our method allows monitoring over time of demyelination and neurodegeneration in brain slices with high spatial resolution and signal-to-noise ratio. Local areas of severe loss of lipid signal indicative of demyelination and loss of the reflectance signal from axons were seen in the corpus callosum and spinal cord of EAE animals. Even in myelinated areas of EAE mice, the intensity of myelin lipid signals is significantly reduced. Using heterozygous knock-in mice in which green fluorescent protein replaces the CX3CR1 coding sequence that labels central nervous system microglia, we find areas of activated microglia colocalized with areas of altered reflectance and CARS signals reflecting axonal injury and demyelination. Our data demonstrate the use of multimodal CARS microscopy for characterization of demyelinating and neurodegenerative pathology in a mouse model of multiple sclerosis, and further confirm the critical role of microglia in chronic inflammatory neurodegeneration.
NASA Astrophysics Data System (ADS)
Los, Victor F.; Los, Nicholas V.
2016-04-01
The exact expressions for an energy-dependent Green function (resolvent), space-time propagator and time-dependent solution for the wave function Ψ(r, t) of a particle moving in the presence of an asymmetric rectangular well/barrier potential are obtained. It is done by applying to this problem the multiple scattering theory (MST), which is different from previous such approaches by using the localized at the potential jumps effective potentials responsible for transmission through and reflection from the considered rectangular potential. This approach (alternative to the path-integral one) enables considering these processes from a particle (rather than a wave) point of view. The solution for the wave function describes these quantum phenomena as a function of time and is related to the fundamental issues (such as measuring time) of quantum mechanics. It is presented in terms of integrals of elementary functions and is a sum of the forward- and backward-moving components of the wave packet. The relative contribution of these components and their interference as well as of the potential asymmetry to the probability density |Ψ(x, t)|2 and particle dwell time is considered and numerically visualized for narrow and broad energy (momentum) distributions of the initial Gaussian wave packet. It is shown that in the case of a broad initial wave packet, the quantum mechanical counterintuitive effect of the influence of the backward-moving components on the considered quantities becomes significant.
Imitola, Jaime; Côté, Daniel; Rasmussen, Stine; Xie, X. Sunney; Liu, Yingru; Chitnis, Tanuja; Sidman, Richard L.; Lin, Charles. P.; Khoury, Samia J.
2011-01-01
Myelin loss and axonal degeneration predominate in many neurological disorders; however, methods to visualize them simultaneously in live tissue are unavailable. We describe a new imaging strategy combining video rate reflectance and fluorescence confocal imaging with coherent anti-Stokes Raman scattering (CARS) microscopy tuned to CH2 vibration of myelin lipids, applied in live tissue of animals with chronic experimental autoimmune encephalomyelitis (EAE). Our method allows monitoring over time of demyelination and neurodegeneration in brain slices with high spatial resolution and signal-to-noise ratio. Local areas of severe loss of lipid signal indicative of demyelination and loss of the reflectance signal from axons were seen in the corpus callosum and spinal cord of EAE animals. Even in myelinated areas of EAE mice, the intensity of myelin lipid signals is significantly reduced. Using heterozygous knock-in mice in which green fluorescent protein replaces the CX3CR1 coding sequence that labels central nervous system microglia, we find areas of activated microglia colocalized with areas of altered reflectance and CARS signals reflecting axonal injury and demyelination. Our data demonstrate the use of multimodal CARS microscopy for characterization of demyelinating and neurodegenerative pathology in a mouse model of multiple sclerosis, and further confirm the critical role of microglia in chronic inflammatory neurodegeneration. PMID:21361672
Borghi, Elena; Solari, Pier Lorenzo
2005-01-01
Our previous studies on the met- and met-azido-Hc forms from Octopus vulgaris (mollusc) and Carcinus aestuarii (arthropod) at pH 7.5 and on some related binuclear models without X-ray diffraction have considered and resolved some fundamental aspects of their binuclear type-3 copper site (i.e. correct values of the Cu-Cu distances; apical distortion, when present, at the copper site; presence and type of bridging groups). In this contribution the multiple-scattering (MS) calculations performed in order to refine the EXAFS modulation of the absorption spectra are presented. It is only with a composite and advanced approach that some severe problems, mainly deriving from the presence of two absorbing atoms and from the fact that the metal-metal contribution in the absorption spectra overlaps with the Cu-His signals, have been overcome. Results are also presented which indicate the role of the MS calculations in the XANES edge region, and which show how it is possible to extract quantitative information from this zone of the spectrum in order to refine the structure of the site also in the case of a binuclear centre.
NASA Astrophysics Data System (ADS)
Cui, P. X.; Lian, F. L.; Wang, Y.; Wen, Yi; Chu, W. S.; Zhao, H. F.; Zhang, S.; Li, J.; Lin, D. H.; Wu, Z. Y.
2014-02-01
Prion-related protein (PrP), a cell-surface copper-binding glycoprotein, is considered to be responsible for a number of transmissible spongiform encephalopathies (TSEs). The structural conversion of PrP from the normal cellular isoform (PrPC) to the post-translationally modified form (PrPSc) is thought to be relevant to Cu2+ binding to histidine residues. Rabbits are one of the few mammalian species that appear to be resistant to TSEs, because of the structural characteristics of the rabbit prion protein (RaPrPC) itself. Here we determined the three-dimensional local structure around the C-terminal high-affinity copper-binding sites using X-ray absorption near-edge structure combined with ab initio calculations in the framework of the multiple-scattering (MS) theory. Result shows that two amino acid resides, Gln97 and Met108, and two histidine residues, His95 and His110, are involved in binding this copper(II) ion. It might help us understand the roles of copper in prion conformation conversions, and the molecular mechanisms of prion-involved diseases.
NASA Astrophysics Data System (ADS)
Ishizawa, O. A.; Clouteau, D.
2007-12-01
Long-duration, amplifications and spatial response's variability of the seismic records registered in Mexico City during the September 1985 earthquake cannot only be explained by the soil velocity model. We will try to explain these phenomena by studying the extent of the effect of buildings' diffracted wave fields during an earthquake. The main question is whether the presence of a large number of buildings can significantly modify the seismic wave field. We are interested in the interaction between the incident wave field propagating in a stratified half- space and a large number of structures at the free surface, i.e., the coupled city-site effect. We study and characterize the seismic wave propagation regimes in a city using the theory of wave propagation in random media. In the coupled city-site system, the buildings are modeled as resonant scatterers uniformly distributed at the surface of a deterministic, horizontally layered elastic half-space representing the soil. Based on the mean-field and the field correlation equations, we build a theoretical model which takes into account the multiple scattering of seismic waves and allows us to describe the coupled city-site system behavior in a simple and rapid way. The results obtained for the configurationally averaged field quantities are validated by means of 3D results for the seismic response of a deterministic model. The numerical simulations of this model are computed with MISS3D code based on classical Soil-Structure Interaction techniques and on a variational coupling between Boundary Integral Equations for a layered soil and a modal Finite Element approach for the buildings. This work proposes a detailed numerical and a theoretical analysis of the city-site interaction (CSI) in Mexico City area. The principal parameters in the study of the CSI are the buildings resonant frequency distribution, the soil characteristics of the site, the urban density and position of the buildings in the city, as well as
Experimental Results of Multiple Scattering.
1981-11-01
fixed, the error is seen to be less for targets with smaller IJ(i)/S(O)Iratio like the softer particles made from expanded polystyrene and larger for...differences from the P, Q plots of dylite ( expanded polystyrene ) particles in preceding sections. It was rather difficult to prepare more than two identical...contacting identical spheres made of expanded polystyrene . As X is continuously varied for the display of il(e) , we notice a fairly symmetrical
Experimental Results of Multiple Scattering.
1980-07-01
error is seen to be less for targets with smaller IS()I/IS(O)Iratio like the softer particles made from expanded polystyrene and larger for harder...optical spectrum, we also notice marked differences from the P, Q plots of dylite ( expanded polystyrene ) particles in preceding sections. It was...spheres made of expanded polystyrene . As X is continuously varied for the display of if(e) , we notice a fairly symmetrical intensity profile about X = 8/2
NASA Astrophysics Data System (ADS)
Xie, Yi-Yan; Wang, Ben-Yi; Cheng, Zhen-Jia; Yue, Qing-Yang; Guo, Cheng-Shan
2017-05-01
An experimental system for measuring the complex vector transmission matrix (VTM) of an anisotropic multiple-scattering medium (AMSM) is proposed. In this system, a simple vector spatial light modulator unit composed of a conventional transmittance spatial light modulator and a small-angle birefringent beam splitter is introduced to realize programmable and quantitative control of both the amplitudes and phases of two orthogonal polarization components of the input vector beam point by point. At the same time, a two-channel angular-multiplexing holographic polarization recording geometry is applied to realize the synchronous holographic measurement of the two orthogonal polarization components of the scattered light field. Using this system, we measured the VTM of an AMSM composed of the ZnO scattering layer. At the same time, we also demonstrated that the system can be directly applied to realize focusing a vector beam through the AMSM based on the measured VTM.
NASA Astrophysics Data System (ADS)
Garnier, A.; Pelon, J.; Vaughan, M. A.; Winker, D. M.; Trepte, C. R.; Dubuisson, P.
2015-02-01
This paper provides a detailed evaluation of cloud absorption optical depths retrieved at 12.05 μm and comparisons to extinction optical depths retrieved at 0.532 μm from perfectly co-located observations of single-layered semi-transparent cirrus over ocean made by the Imaging Infrared Radiometer (IIR) and the Cloud and Aerosol Lidar with Orthogonal Polarization (CALIOP) flying on-board the CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) satellite. The blackbody radiance taken in the IIR Version 3 algorithm is evaluated, and IIR retrievals are corrected accordingly. IIR infrared absorption optical depths are then compared to CALIOP visible extinction optical depths when the latter can be directly derived from the measured apparent 2-way transmittance through the cloud. Numerical simulations and IIR retrievals of ice crystal sizes suggest that the ratios of CALIOP extinction and IIR absorption optical depths should remain roughly constant with respect to temperature. Instead, these ratios are found to increase quasi-linearly by about 40% as the temperature at the layer centroid altitude decreases from 240 to 200 K. This behavior is explained by variations of the multiple scattering factor ηT to be applied to correct the measured transmittance, which is taken equal to 0.6 in the CALIOP Version 3 algorithm, and which is found here to vary with temperature (and hence cloud particle size) from ηT = 0.8 at 200 K to ηT = 0.5 at 240 K for clouds with optical depth larger than 0.3. The revised parameterization of ηT introduces a concomitant temperature dependence in the simultaneously derived CALIOP lidar ratios that is consistent with observed changes in CALIOP depolarization ratios and particle habits derived from IIR measurements.
Wang, Shaofeng; Ma, Xu; Zhang, Guoqing; Jia, Yongfeng; Hatada, Keisuke
2016-11-15
Hydrous ferric arsenate (HFA) is an important arsenic-bearing precipitate in the mining-impacted environment and hydrometallurgical tailings. However, there is no agreement on its local atomic structure. The local structure of HFA was reprobed by employing a full-potential multiple scattering (FPMS) analysis, density functional theory (DFT) calculations, and vibrational spectroscopy. The FPMS simulations indicated that the coordination number of the As-Fe, Fe-As, or both in HFA was approximately two. The DFT calculations constructed a structure of HFA with the formula of Fe(HAsO4)x(H2AsO4)1-x(OH)y·zH2O. The presence of protonated arsenate in HFA was also evidenced by vibrational spectroscopy. The As and Fe K-edge X-ray absorption near-edge structure spectra of HFA were accurately reproduced by FPMS simulations using the chain structure, which was also a reasonable model for extended X-Ray absorption fine structure fitting. The FPMS refinements indicated that the interatomic Fe-Fe distance was approximately 5.2 Å, consistent with that obtained by Mikutta et al. (Environ. Sci. Technol. 2013, 47 (7), 3122-3131) using wavelet analysis. All of the results suggested that HFA was more likely to occur as a chain with AsO4 tetrahedra and FeO6 octahedra connecting alternately in an isolated bidentate-type fashion. This finding is of significance for understanding the fate of arsenic and the formation of ferric arsenate minerals in an acidic environment.
NASA Astrophysics Data System (ADS)
Hernandez, Joel
Depolarized light-scattering spectra of the intermediate glass-former glycerol were obtained in the frequency and temperature ranges of 0.4 to 6000 GHz and 173 to 413 K respectively. Analysis of the resulting susceptibility spectra using the asymptotic leading order equations of mode coupling theory (MCT) showed only partial agreement between theory and experiment. However, a recent analysis of our data using a full numerical solution of the MCT equations has been remarkably successful, widening the applicability of the theory to weak network glass-formers and motivating the need to conduct similar tests with strong network glass-formers. The accidental discovery of a low-frequency band in the light scattering spectrum from a powder of the protein lysozyme lead us to the development of a model for that kind of scattering. Such a model was found to be in very good agreement with our experimental data. A preliminary infrared absorption experiment on synthesized helical peptides, containing glutamic acid (Glu) amino acid residues spaced periodically along the polypeptide chain, showed evidence for the stabilization of the helical structure of the peptide, by intramolecular hydrogen bonding interactions between the carboxylic acid groups in the side chains of the Glu residues.
Resel, Roland; Bainschab, Markus; Pichler, Alexander; Dingemans, Theo; Simbrunner, Clemens; Stangl, Julian; Salzmann, Ingo
2016-01-01
Dynamical scattering effects are observed in grazing-incidence X-ray diffraction experiments using an organic thin film of 2,2′:6′,2′′-ternaphthalene grown on oxidized silicon as substrate. Here, a splitting of all Bragg peaks in the out-of-plane direction (z-direction) has been observed, the magnitude of which depends both on the incidence angle of the primary beam and the out-of-plane angle of the scattered beam. The incident angle was varied between 0.09° and 0.25° for synchrotron radiation of 10.5 keV. This study reveals comparable intensities of the split peaks with a maximum for incidence angles close to the critical angle of total external reflection of the substrate. This observation is rationalized by two different scattering pathways resulting in diffraction peaks at different positions at the detector. In order to minimize the splitting, the data suggest either using incident angles well below the critical angle of total reflection or angles well above, which sufficiently attenuates the contributions from the second scattering path. This study highlights that the refraction of X-rays in (organic) thin films has to be corrected accordingly to allow for the determination of peak positions with sufficient accuracy. Based thereon, a reliable determination of the lattice constants becomes feasible, which is required for crystallographic structure solutions from thin films. PMID:27140152
Resel, Roland; Bainschab, Markus; Pichler, Alexander; Dingemans, Theo; Simbrunner, Clemens; Stangl, Julian; Salzmann, Ingo
2016-05-01
Dynamical scattering effects are observed in grazing-incidence X-ray diffraction experiments using an organic thin film of 2,2':6',2''-ternaphthalene grown on oxidized silicon as substrate. Here, a splitting of all Bragg peaks in the out-of-plane direction (z-direction) has been observed, the magnitude of which depends both on the incidence angle of the primary beam and the out-of-plane angle of the scattered beam. The incident angle was varied between 0.09° and 0.25° for synchrotron radiation of 10.5 keV. This study reveals comparable intensities of the split peaks with a maximum for incidence angles close to the critical angle of total external reflection of the substrate. This observation is rationalized by two different scattering pathways resulting in diffraction peaks at different positions at the detector. In order to minimize the splitting, the data suggest either using incident angles well below the critical angle of total reflection or angles well above, which sufficiently attenuates the contributions from the second scattering path. This study highlights that the refraction of X-rays in (organic) thin films has to be corrected accordingly to allow for the determination of peak positions with sufficient accuracy. Based thereon, a reliable determination of the lattice constants becomes feasible, which is required for crystallographic structure solutions from thin films.
NASA Astrophysics Data System (ADS)
Bykov, A. V.; Kirillin, M. Yu; Priezzhev, A. V.; Myllylä, Risto
2006-12-01
The possibility of using spatially resolved reflectometry (SRR) at a wavelength of 820 nm to detect changes in the optical properties of a highly scattering layered random medium simulating a biological tissue caused by changes in the glucose level is analysed. Model signals from a three-layer biological tissue phantom consisting of two skin layers and a blood layer located between them are obtained by the Monte-Carlo method. It was assumed that variations in the glucose level induce variations in the optical parameters of the blood layer and the bottom skin layer. To analyse the trajectories of photons forming the SRR signal, their scattering maps are obtained. The ratio of the photon path in layers sensitive to the glucose level to the total path in the medium was used as a parameter characterising these trajectories. The relative change in the reflected signal caused by a change in the glucose concentration is analysed depending on the distance between a probe radiation source and a detector. It is shown that the maximum relative change in the signal (about 7%) takes place for the source — detector separation in the range from 0.3 to 0.5 mm depending on the model parameters.
Katcho, N. A.; Lomba, E.; Urones-Garrote, E.; Otero-Diaz, L. C.; Landa-Canovas, A. R.
2006-06-01
In this work we present an investigation on the composition dependence of the local structure in Se{sub x}Te{sub 1-x} crystalline alloys analyzing their experimental energy-loss spectra with the aid of a real-space multiple-scattering modeling approach and first-principles molecular dynamics. The concourse of this latter technique is essential for a proper modeling of the alloy spectra. From our results, it can be inferred that Se{sub x}Te{sub 1-x} alloys exhibit a high degree of substitutional disorder ruling out the existence of fully ordered alternating copolymer chains of Se and Te atoms.
NASA Astrophysics Data System (ADS)
Pelivanov, Ivan M.; Belov, Sergej A.; Solomatin, Vladimir S.; Khokhlova, Tanya D.; Karabutov, Aleksander A.
2006-12-01
The problem of opto-acoustic (AO) diagnostics of light scattering and absorption in biological media is considered. The objects under study were milk, bovine and porcine liver, and bovine muscle tissue. The forward and backward schemes for recording acoustic signals were used in experiments. The spatial distribution of the light intensity was measured for each biological medium from the temporal profile of the excited OA pulse and the absorption coefficient and reduced scattering coefficient were determined. Opto-acoustic signals were excited by a 1064-nm pulsed Nd:YAG laser and a tunable Ti:sapphire laser at 779 nm. It is shown that the proposed method can be used for obtaining a priori information on a biological medium in problems of optical and AO tomography.
NASA Astrophysics Data System (ADS)
Luxford, Thomas F. M.; Sharples, Thomas R.; McKendrick, Kenneth G.; Costen, Matthew L.
2016-11-01
We present a crossed molecular beam velocity-map ion imaging study of state-to-state rotational energy transfer of NO(A2Σ+, v = 0, N = 0, j = 0.5) in collisions with Ne atoms. From these measurements, we report differential cross sections and angle-resolved rotational angular momentum alignment moments for product states N' = 3 and 5-10 for collisions at an average energy of 523 cm-1, and N' = 3 and 5-14 for collisions at an average energy of 1309 cm-1, respectively. The experimental results are compared to the results of close-coupled quantum scattering calculations on two literature ab initio potential energy surfaces (PESs) [Pajón-Suárez et al., Chem. Phys. Lett. 429, 389 (2006) and Cybulski and Fernández, J. Phys. Chem. A 116, 7319 (2012)]. The differential cross sections from both experiment and theory show clear rotational rainbow structures at both collision energies, and comparison of the angles observed for the rainbow peaks leads to the conclusion that Cybulski and Fernández PES better represents the NO(A2Σ+)-Ne interaction at the collision energies used here. Sharp, forward scattered (<10°), peaks are observed in the experimental differential cross sections for a wide range of N' at both collision energies, which are not reproduced by theory on either PES. We identify these as L-type rainbows, characteristic of attractive interactions, and consistent with a shallow well in the collinear Ne-N-O geometry, similar to that calculated for the NO(A2Σ+)-Ar surface [Kłos et al., J. Chem. Phys. 129, 244303 (2008)], but absent from both of the NO(A2Σ+)-Ne surfaces tested here. The angle-resolved alignment moments calculated by quantum scattering theory are generally in good agreement with the experimental results, but both experiment and quantum scattering theories are dramatically different to the predictions of a classical rigid-shell, kinematic-apse conservation model. Strong oscillations are resolved in the experimental alignment moments as a
Luxford, Thomas F M; Sharples, Thomas R; McKendrick, Kenneth G; Costen, Matthew L
2016-11-07
We present a crossed molecular beam velocity-map ion imaging study of state-to-state rotational energy transfer of NO(A(2)Σ(+), v = 0, N = 0, j = 0.5) in collisions with Ne atoms. From these measurements, we report differential cross sections and angle-resolved rotational angular momentum alignment moments for product states N' = 3 and 5-10 for collisions at an average energy of 523 cm(-1), and N' = 3 and 5-14 for collisions at an average energy of 1309 cm(-1), respectively. The experimental results are compared to the results of close-coupled quantum scattering calculations on two literature ab initio potential energy surfaces (PESs) [Pajón-Suárez et al., Chem. Phys. Lett. 429, 389 (2006) and Cybulski and Fernández, J. Phys. Chem. A 116, 7319 (2012)]. The differential cross sections from both experiment and theory show clear rotational rainbow structures at both collision energies, and comparison of the angles observed for the rainbow peaks leads to the conclusion that Cybulski and Fernández PES better represents the NO(A(2)Σ(+))-Ne interaction at the collision energies used here. Sharp, forward scattered (<10°), peaks are observed in the experimental differential cross sections for a wide range of N' at both collision energies, which are not reproduced by theory on either PES. We identify these as L-type rainbows, characteristic of attractive interactions, and consistent with a shallow well in the collinear Ne-N-O geometry, similar to that calculated for the NO(A(2)Σ(+))-Ar surface [Kłos et al., J. Chem. Phys. 129, 244303 (2008)], but absent from both of the NO(A(2)Σ(+))-Ne surfaces tested here. The angle-resolved alignment moments calculated by quantum scattering theory are generally in good agreement with the experimental results, but both experiment and quantum scattering theories are dramatically different to the predictions of a classical rigid-shell, kinematic-apse conservation model. Strong oscillations are resolved in the experimental alignment
NASA Astrophysics Data System (ADS)
Kim, Dai-Sik
1990-01-01
Time-resolved Raman scattering experiments have been performed in semiconductors to study the relaxation of hot carriers excited by subpicosecond laser pulses. A one-beam-excite-and-probe Raman scattering technique has been developed and applied to the cooling of hot electrons by varying the laser pulse width. Electron-phonon scattering times have been deduced by measuring the population of phonons generated by hot electron relaxation as a function of carrier density. Three different type of samples: bulk GaAs, In_{0.53}Ga _{0.47}As alloy, and GaAs/AlAs multiple quantum wells have been studied. In GaAs, we discovered a transient overshoot of longitudinal optical (LO) phonon temperature above the electron temperature which we have called 'phonon temperature overshoot'. This is contrary to expectation if we assume that the electrons are cooled only by emission of LO phonons. The results can be explained if we assume that the electrons are cooled predominantly by another more efficient mechanism in addition to LO phonon emission. We found that intervalley scattering provided the cooling mechanism to explain both the phonon temperature overshoot and the cooling curve of the hot carriers. This model was found to be successful in explaining the hot electron cooling curve in In_{0.53 }Ga_{0.47}As and in enabling us to determine the intervalley scattering rate in In_{0.53}Ga _{0.47}As for the first time. Based on this same model, we predicted that the hot phonon population generated by hot electrons will be greatly reduced in GaAs/AlAs multiple quantum wells as the well thickness is reduced to below 400 A. This prediction has been verified by measuring the hot phonon population excited by subpicosecond laser pulses in a series of samples with well width varying between 1000 A to 100 A. While the experimental results are in good qualitative agreement with our prediction, the observed phonon population is higher than predicted by our model. One possible explanation of this
Rayleigh, Raman and particulate scattering
NASA Technical Reports Server (NTRS)
Cochran, W. D.
1982-01-01
Analysis of the visible and near infrared spectra of planetary atmospheres and the multiple scattering of photons within the atmosphere are discussed. Photons detected within the spectral region are solar photons which were scattered by the gas and particles in the planetary atmosphere. An example is given for the incident and emitted fluxes for a hypothetical planet with an effective temperature of 100 K. The absorption spectrum of the planetary atmosphere is discussed in terms of the various scattering processes photons undergo within the atmosphere. Three different physical processes are considered. Rayleigh scattering and Raman scattering by the gas molecules, and scattering by any cloud or dust aerosol particles in the atmosphere. The physics of each of these processes is examined.
Investigation of moderately turbid suspensions by heterodyne near field scattering.
Escobedo-Sánchez, M A; Rojas-Ochoa, L F; Laurati, M; Egelhaaf, S U
2017-08-03
Light scattering has proven to be a very powerful technique to characterize soft matter systems. However, many samples are turbid and hence suffer from multiple scattering which can affect the signal considerably. Multiple scattering can be reduced by diluting the sample or changing the solvent, but often this alters the sample and hence is precluded. Here we study the dynamics of a model system. In particular, we investigate the effects of moderate multiple scattering on small-angle heterodyne near field scattering (HNFS). Varying the particle concentration and size we change the degree of multiple scattering, which is quantified by the transmission of light. In dependence of the degree of multiple scattering, we analyze the statistical properties of the HNFS signal, which is the difference between two intensity patterns separated by a delay time. The distribution of intensity differences follows a Gaussian distribution if single scattering dominates and a Laplace distribution in the presence of extreme multiple scattering. We also investigate the effects of multiple scattering on the measured intermediate scattering function and the hydrodynamic radius of the particles. Reliable data are obtained for sample transmissions down to about 0.7. This is confirmed by a comparison with results from a far field cross-correlation instrument that suppresses multiple scattering contributions. Therefore, HNFS represents a technically simple but powerful method to investigate samples that are moderately multiple scattering.
NASA Technical Reports Server (NTRS)
Schaetzel, Klaus
1989-01-01
Since the development of laser light sources and fast digital electronics for signal processing, the classical discipline of light scattering on liquid systems experienced a strong revival plus an enormous expansion, mainly due to new dynamic light scattering techniques. While a large number of liquid systems can be investigated, ranging from pure liquids to multicomponent microemulsions, this review is largely restricted to applications on Brownian particles, typically in the submicron range. Static light scattering, the careful recording of the angular dependence of scattered light, is a valuable tool for the analysis of particle size and shape, or of their spatial ordering due to mutual interactions. Dynamic techniques, most notably photon correlation spectroscopy, give direct access to particle motion. This may be Brownian motion, which allows the determination of particle size, or some collective motion, e.g., electrophoresis, which yields particle mobility data. Suitable optical systems as well as the necessary data processing schemes are presented in some detail. Special attention is devoted to topics of current interest, like correlation over very large lag time ranges or multiple scattering.
Observation of Nonlinear Compton Scattering
Kotseroglou, T.
2003-12-19
This experiment tests Quantum Electrodynamics in the strong field regime. Nonlinear Compton scattering has been observed during the interaction of a 46.6 GeV electron beam with a 10{sup 18} W/cm{sup 2} laser beam. The strength of the field achieved was measured by the parameter {eta} = e{var_epsilon}{sub rms}/{omega}mc = 0.6. Data were collected with infrared and green laser photons and circularly polarized laser light. The timing stabilization achieved between the picosecond laser and electron pulses has {sigma}{sub rms} = 2 ps. A strong signal of electrons that absorbed up to 4 infrared photons (or up to 3 green photons) at the same point in space and time, while emitting a single gamma ray, was observed. The energy spectra of the scattered electrons and the nonlinear dependence of the electron yield on the field strength agreed with the simulation over 3 orders of magnitude. The detector could not resolve the nonlinear Compton scattering from the multiple single Compton scattering which produced rates of scattered electrons of the same order of magnitude. Nevertheless, a simulation has studied this difference and concluded that the scattered electron rates observed could not be accounted for only by multiple ordinary Compton scattering; nonlinear Compton scattering processes are dominant for n {ge} 3.
NASA Astrophysics Data System (ADS)
Kandidov, V. P.; Militsin, V. O.; Bykov, A. V.; Priezzhev, A. V.
2006-11-01
Two ways of simulating statistically the propagation of laser radiation in dispersive media by the Monte-Carlo method are compared. The first approach can be called corpuscular because it is based on the calculation of random photon trajectories, while the second one can be referred to as the wave approach because it is based on the calculation of characteristics of random wave fields. It is shown that, although these approaches are based on different physical concepts of radiation scattering by particles, they yield almost equivalent results for the intensity of a restricted beam in a dispersive medium. However, there exist some differences. The corpuscular Monte-Carlo method does not reproduce the diffraction divergence of the beam, which can be taken into account by introducing the diffraction factor. The wave method does not consider backscattering, which corresponds to the quasi-optical approximation.
NASA Astrophysics Data System (ADS)
Stratonnikov, Aleksandr A.; Meerovich, G. A.; Ryabova, A. V.; Savel'eva, T. A.; Loshchenov, V. B.
2006-12-01
The application of backward diffuse reflection (BDR) spectroscopy for in vivo monitoring the degree of haemoglobin oxygenation and concentration of photosensitisers in tissues subjected to photodynamic therapy is demonstrated. A simple experimental technique is proposed for measuring diffuse reflection spectra. The measurements are made under steady-state conditions using a fibreoptic probe with one transmitting and one receiving fibre separated by a fixed distance. Although this approach does not ensure the separation of contributions of scattering and absorption to the spectra being measured, it can be used for estimating the degree of haemoglobin oxygenation and concentration of photosensitisers in the tissues. Simple expressions for estimating the concentration of photosensitisers from the BDR spectra are presented and the accuracy of this approach is analysed. The results of application of BDR spectroscopy for monitoring various photosensitisers are considered.
Acoustic Coherent Backscatter Enhancement from Aggregations of Point Scatterers
2014-09-30
acoustic multiple scattering from two- and now three-dimensional aggregations of omni-directional point scatterers to determine the parametric realms in...given by the sum in (1), N is the number of scatterers , gn is the scattering coefficient of the nth scatterer , ψn(rn) is the field incident on the nth...SUBTITLE Acoustic Coherent Backscatter Enhancement from Aggregations of Point Scatterers 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT
Electromagnetic scattering from turbulent plasmas
Resendes, D.G. Instituto Superior Tecnico, Rua Rovisco Pais, Lisboa )
1992-11-15
A self-consistent multiple-scattering theory of vector electromagnetic waves scattered from a turbulent plasma is presented. This approach provides a general and systematic treatment to all orders in turbulence of the scattering of electromagnetic waves in terms of the properties of the turbulent structure of the scattering system and is applicable in the full regime from underdense to overdense plasmas. To illustrate the theory, a plasma consisting of a finite number density of discrete scatterers with a simple geometry and statistical properties is chosen. In this approach the exact solution for a single scatterer is obtained first. From it the configuration-dependent solution for {ital N} scatterers is constructed. Rather than solving explicitly for this solution and then averaging, the averaging operation will be taken first in order to find an approximate equation obeyed by the mean or coherent field. The coherent and incoherent scattering are then determined in terms of the coherent field and the backscatter is evaluated. The coherent and incoherent scattering, our principal results, are expressed in a plane-wave basis in a form suitable for numerical computation. A number of interesting phenomena which may readily be incorporated into the theory are indicated.
Demchenko, I. N.; Denlinger, J. D.; Chernyshova, M.; Yu, K. M.; Speaks, D. T.; Olalde-Velasco, P.; Hemmers, O.; Walukiewicz, W.; Derkachova, A.; Lawniczak-Jablonska, K.
2010-07-05
X-ray absorption near edge structure (XANES) at the cadmium L3 and oxygen K edges for CdO thin films grown by pulsed laser deposition method, is interpreted within the real-space multiple scattering formalism, FEFF code. The features in the experimental spectra are well reproduced by calculations for a cluster of about six and ten coordination shells around the absorber for L3 edge of Cd and K edge of O, respectively. The calculated projected electronic density of states is found to be in good agreement with unoccupied electronic states in experimental data and allows to conclude that the orbital character of the lowest energy of the conductive band is Cd-5s-O-2p. The charge transfer has been quantified and not purely ionic bonding has been found. Combined XANES and resonant inelastic x-ray scattering measurements allow us to determine the direct and indirect band gap of investigated CdO films to be {approx}2.4-eV and {approx}0.9-eV, respectively.
Lucas, A A; Sunjic, M; Benedek, G
2013-09-04
An analytic model is developed to describe the inelastic processes occurring when keV Ne(+) ions are scattered at grazing incidence by the (100) surface of LiF. The large energy losses (up to 30 eV) of the reflected Ne(+) particles reported by Borisov et al (1999 Phys. Rev. Lett. 83 5378) are shown to arise specifically from the long-range coupling between the projectiles and the so-called Fuchs-Kliewer (FK) optical phonons of LiF whose fields extend far outside the surface. The strength of the coupling is estimated, allowing one to compute the average number of excited FK phonon quanta (ħωS = 0.071 eV) and hence the mean energy losses. For emerging, neutralized Ne(0), a distinct energy loss mechanism is shown to occur, namely the excitation of FK phonons and other types of surface collective modes associated with the screening of the F(0) 'hole' left behind by the neutralization process. This mechanism contributes a large fraction of the loss, additional to that suffered by the incident Ne(+) ion. The model explains the experimental observations quantitatively (1999 Phys. Rev. Lett. 83 5378). The paper ends with a discussion of the large energy broadening of the observed loss peaks.
Pailloux, F.; Jublot, M.; Gaboriaud, R.J.; Jaouen, M.; Paumier, F.; Imhoff, D.
2005-09-15
Electron energy loss spectroscopy (EELS), high resolution transmission electron microscopy (HRTEM), and electron diffraction were used to investigate Y{sub 2}O{sub 3} thin films epitaxially grown on (001) MgO substrate. In the vicinity of the film/substrate interface, HRTEM experiments evidenced the presence of grains with various crystallographic structures most of them crystallizing in the well-known Ia3 cubic phase. Some other grains, nanometric in size, and only observed in the vicinity of the film/substrate interface, have a different and unknown crystallographic structure. EELS spectra have been acquired close to the Y{sub 2}O{sub 3}/MgO interface, to get a better knowledge of the phases nucleated close to the substrate surface. Spectra exhibiting different fine structures have been recorded and compared to multiple scattering calculations. The Ia3 phase has been detected as constituting the main component of the Y{sub 2}O{sub 3} thin film in agreement with previous observations. It is found that calculations performed in a real space self-consistent full multiple scattering scheme (SC-FMS) and experiments are in pretty good agreement even for small cluster sizes. The second family of spectra has also been compared to calculations performed for monoclinic C2/m yttrium oxide, with a little success. Another approach considering a local oxygen neighboring close to a distorted rock-salt-like structure led to a good match between experimental and calculated spectra. Our results emphasize how powerful is the combination of spectroscopic measurements at nanometer scale, as feasible with EELS and modern microscopes, with ab initio calculations for structure determination at such small scale lengths.
Critical fluid light scattering
NASA Technical Reports Server (NTRS)
Gammon, Robert W.
1988-01-01
The objective is to measure the decay rates of critical density fluctuations in a simple fluid (xenon) very near its liquid-vapor critical point using laser light scattering and photon correlation spectroscopy. Such experiments were severely limited on Earth by the presence of gravity which causes large density gradients in the sample when the compressibility diverges approaching the critical point. The goal is to measure fluctuation decay rates at least two decades closer to the critical point than is possible on earth, with a resolution of 3 microK. This will require loading the sample to 0.1 percent of the critical density and taking data as close as 100 microK to the critical temperature. The minimum mission time of 100 hours will allow a complete range of temperature points to be covered, limited by the thermal response of the sample. Other technical problems have to be addressed such as multiple scattering and the effect of wetting layers. The experiment entails measurement of the scattering intensity fluctuation decay rate at two angles for each temperature and simultaneously recording the scattering intensities and sample turbidity (from the transmission). The analyzed intensity and turbidity data gives the correlation length at each temperature and locates the critical temperature. The fluctuation decay rate data from these measurements will provide a severe test of the generalized hydrodynamic theories of transport coefficients in the critical regions. When compared to equivalent data from binary liquid critical mixtures they will test the universality of critical dynamics.
NASA Astrophysics Data System (ADS)
Pisek, J.; Kobayashi, H.; Kuusk, A.
2016-12-01
Correct estimates of gap fraction are essential for quantifying canopy architectural variables, such as leaf area and clumping indices, which modify land-atmosphere interactions. The plant canopy analyzer (PCA) LAI-2000/2200 has been in use for the non-destructive determination of leaf area index (LAI), and other structural attributes of vegetative canopies for over 25 years (Li-Cor, 1989). The instrument is considered the world standard for indirect LAI measurements (Li-Cor, 2014). The PCA uses the gap fraction technique for calculation of LAI and mean inclination angle of foliage. However, gap fraction measurements from optical sensors are contaminated by radiation that is scattered by plant elements and ground surfaces. Three proposed alternative schemes for correcting multiple scattering effects on gap fraction measurements by PCA are evaluated: 1) Leblanc and Chen, 2001. Agric. For. Meteorol. 110, 125-139; 2) Kobayashi et al.., 2013. Agric. For. Meteorol. 174-175, 170-183; and 3) Kuusk, 2016. Agric. For. Meteorol. 221, 242-247. Collectively these methods provide suggestions for the correction of LAI estimates from measurements under wide range of illumination conditions. The PCA measurements were taken at two different RAMI (RAdiation transfer Model Intercomparison) stands in Järvselja, Estonia. All three schemes agreed reasonably well in the sparse and homogeneous RAMI Scots pine stand; the effective LAI would be underestimated by up to 13% if the corrections are not implemented. The proposed corrections varied from 7% (method by Kobayashi et al., 2013) up to 23% (method by Leblanc and Chen, 2001) in denser and heterogeneous RAMI birch stand. The role of scattered sky radiation in the estimation of gap fraction in vegetation canopies using passive optical techniques should be clearly accounted for even in case of perfectly overcast sky. The PCA measurements are considered a reference in developing methods of the estimation of gap fraction from hemispherical
Structured light, transmission, and scattering
NASA Astrophysics Data System (ADS)
Andrews, David L.
2011-03-01
Numerous theoretical and experimental studies have established the principle that beams conveying orbital angular momentum offer a rich scope for information transfer. However, it is not clear how far it is practicable to operate such a concept at the single-photon level - especially when such a beam propagates through a system in which scattering can occur. In cases where scattering leads to photon deflection, it produces losses; however in terms of the retention of information content, there should be more concern over forward scattering. Based on a quantum electrodynamical formulation of theory, this paper aims to frame and resolve the key issues. A quantum amplitude is constructed for the representation of single and multiple scattering events in the propagation an individual photon, from a suitably structured beam. The analysis identifies potential limitations of principle, undermining complete fidelity of quantum information transmission.
Microscopic distorted wave theory of inelastic scattering
NASA Astrophysics Data System (ADS)
Picklesimer, A.; Tandy, P. C.; Thaler, R. M.
1982-03-01
An exact microscopic distorted wave theory of inelastic scattering is formulated which contains the physical picture usually associated with distorted wave approximations without the usual redundancy. This formulation encompasses the inelastic scattering of two fragments, elementary or composite (both with or without the full complexity of interfragment Pauli symmetries). The fact that these considerations need not be based upon elementary potential interactions is an indication of the generality of the approach and supports its applicability to inelastic meson scattering. The theory also maintains a description of inelastic scattering which is a natural extension of the description of elastic scattering and it provides a general basis for obtaining truncation models with an explicit distorted wave structure. The distorted wave impulse approximation is presented as an example of a particular truncation/approximation encompassed by this theory and the nature of the distorted waves is explicated. NUCLEAR REACTIONS Distorted wave theory, inelastic scattering, multiple scattering, spectator expansion, Pauli exclusion principle, composite particles, unitarity structure.
Nanowire Electron Scattering Spectroscopy
NASA Technical Reports Server (NTRS)
Hunt, Brian; Bronikowsky, Michael; Wong, Eric; VonAllmen, Paul; Oyafuso, Fablano
2009-01-01
Nanowire electron scattering spectroscopy (NESS) has been proposed as the basis of a class of ultra-small, ultralow-power sensors that could be used to detect and identify chemical compounds present in extremely small quantities. State-of-the-art nanowire chemical sensors have already been demonstrated to be capable of detecting a variety of compounds in femtomolar quantities. However, to date, chemically specific sensing of molecules using these sensors has required the use of chemically functionalized nanowires with receptors tailored to individual molecules of interest. While potentially effective, this functionalization requires labor-intensive treatment of many nanowires to sense a broad spectrum of molecules. In contrast, NESS would eliminate the need for chemical functionalization of nanowires and would enable the use of the same sensor to detect and identify multiple compounds. NESS is analogous to Raman spectroscopy, the main difference being that in NESS, one would utilize inelastic scattering of electrons instead of photons to determine molecular vibrational energy levels. More specifically, in NESS, one would exploit inelastic scattering of electrons by low-lying vibrational quantum states of molecules attached to a nanowire or nanotube.
Lectures on the scattering of light. [by dielectric sphere
NASA Technical Reports Server (NTRS)
Saxon, D. S.
1974-01-01
The exact (Mie) theory for the scattering of a plane wave by a dielectric sphere is presented. Since this infinite series solution is computationally impractical for large spheres, another formulation is given in terms of an integral equation valid for a bounded, but otherwise general array of scatterers. This equation is applied to the scattering by a single sphere, and several methods are suggested for approximating the scattering cross section in closed form. A tensor scattering matrix is introduced, in terms of which some general scattering theorems are derived. The application of the formalism to multiple scattering is briefly considered.
NASA Astrophysics Data System (ADS)
Zilani, M. A. K.; Xu, H.; Liu, T.; Sun, Y. Y.; Feng, Y. P.; Wang, X.-S.; Wee, A. T. S.
2006-05-01
The electronic structure of cobalt-induced magic clusters grown on Si(111)-(7×7) is investigated by scanning tunneling microscopy, scanning tunneling spectroscopy, and real-space multiple-scattering calculations. Topographical images of a half unit cell of Si(111)-(7×7) with the cluster acquired at low bias voltages of ±0.4V show greatly reduced cluster heights; however, the heights of the corner adatoms are unchanged, indicative of the highly localized nature of the charge distribution. Spectroscopic studies of the clusters indicate a band gap of ˜0.8eV , suggesting localized nonmetallic behavior. The opening of such a band gap is suggested to be a stabilizing factor for the observed magic clusters. A 65-atom Co-Si cluster is constructed to calculate the momentum- and element-projected density of states. The calculated result identifies that the intense state below the Fermi level at -1.75V in the experimental spectroscopic curve is primarily due to localized 3d orbitals of Co atoms in the magic clusters.
Modeling of scattering from ice surfaces
NASA Astrophysics Data System (ADS)
Dahlberg, Michael Ross
Theoretical research is proposed to study electromagnetic wave scattering from ice surfaces. A mathematical formulation that is more representative of the electromagnetic scattering from ice, with volume mechanisms included, and capable of handling multiple scattering effects is developed. This research is essential to advancing the field of environmental science and engineering by enabling more accurate inversion of remote sensing data. The results of this research contributed towards a more accurate representation of the scattering from ice surfaces, that is computationally more efficient and that can be applied to many remote-sensing applications.
Analytical optical scattering in clouds
NASA Technical Reports Server (NTRS)
Phanord, Dieudonne D.
1989-01-01
An analytical optical model for scattering of light due to lightning by clouds of different geometry is being developed. The self-consistent approach and the equivalent medium concept of Twersky was used to treat the case corresponding to outside illumination. Thus, the resulting multiple scattering problem is transformed with the knowledge of the bulk parameters, into scattering by a single obstacle in isolation. Based on the size parameter of a typical water droplet as compared to the incident wave length, the problem for the single scatterer equivalent to the distribution of cloud particles can be solved either by Mie or Rayleigh scattering theory. The super computing code of Wiscombe can be used immediately to produce results that can be compared to the Monte Carlo computer simulation for outside incidence. A fairly reasonable inverse approach using the solution of the outside illumination case was proposed to model analytically the situation for point sources located inside the thick optical cloud. Its mathematical details are still being investigated. When finished, it will provide scientists an enhanced capability to study more realistic clouds. For testing purposes, the direct approach to the inside illumination of clouds by lightning is under consideration. Presently, an analytical solution for the cubic cloud will soon be obtained. For cylindrical or spherical clouds, preliminary results are needed for scattering by bounded obstacles above or below a penetrable surface interface.
Single and Multiple Scattered Solar Radiation
1982-08-30
release; distribution unlimited Prel.paire(d for: AIR FORCE GEOPHYSICS LABORATORY D T IC AIR FORCE SYSSTEMS COMMAND , . UNITED STATES AIR FORCE IUXNSCOM...encountered in modeling engineering atnd atmospheric environments. Therefore, the following scemec is one possibLe approach to dec rease computational times for...1943). 39. Kreith, F. and Kreider, J.1., Principles of Solar Engineering . Mcct-aw-!hill 1ooký Company, New York (1978). 118 APPENDIX A: MIl DATA ACCESS
Multiple scattering theory of electron diffraction
NASA Astrophysics Data System (ADS)
Pendry, J. B.
1994-01-01
In the early 1960's surface science set itself some fundamental goals: to make a quantitative science out of surface crystallography; to understand the nature of electronic structure and bonding at surfaces; and to enhance the tools available for study of surfaces. The effort has very much been a collective one, reflected in the wide authorship of the present volume. Here I contribute to the picture my personal perspective on developments in the past 30 years of surface science, and describe some of the highlights in my own research and that of my close colleagues.
Interferometric Rayleigh Scattering Measurement System
NASA Technical Reports Server (NTRS)
Bivolaru, Daniel (Inventor); Danehy, Paul M. (Inventor); Lee, Joseph W. (Inventor)
2008-01-01
A method and apparatus for performing simultaneous multi-point measurements of multiple velocity components in a gas flow is described. Pulses of laser light are directed to a measurement region of unseeded gas to produce Rayleigh or Mie scattered light in a plurality of directions. The Rayleigh or Mie scattered light is collected from multiple directions and combined in a single collimated light beam. The Rayleigh or Mie scattered light is then mixed together with a reference laser light before it is passed through a single planar Fabry-Perot interferometer for spectral analysis. At the output of the interferometer, a high-sensitivity CCD camera images the interference fringe pattern. This pattern contains the spectral and spatial information from both the Rayleigh scattered light and the reference laser light. Interferogram processing software extracts and analyzes spectral profiles to determine the velocity components of the gas flow at multiple points in the measurement region. The Rayleigh light rejected by the interferometer is recirculated to increase the accuracy and the applicability of the method for measurements at high temperatures without requiring an increase in the laser energy.
Particle Diffusion Due to Coulomb Scattering
V. Lebedev and S. Nagaitsev
2002-06-03
Conventionally, the multiple and single particle scattering in a storage ring are considered to be independent. Such an approach is simple and often yields sufficiently accurate results. Nevertheless, there is a class of problems where such an approach is not adequate and the single and multiple scattering need to be considered together. This can be achieved by solving an integro-differential equation for the particle distribution function, which correctly treats particle Coulomb scattering in the presence of betatron motion. A derivation of the equation is presented in the article. A numerical solution for one practical case is also considered.
Rayleigh scattering. [molecular scattering terminology redefined
NASA Technical Reports Server (NTRS)
Young, A. T.
1981-01-01
The physical phenomena of molecular scattering are examined with the objective of redefining the confusing terminology currently used. The following definitions are proposed: molecular scattering consists of Rayleigh and vibrational Raman scattering; the Rayleigh scattering consists of rotational Raman lines and the central Cabannes line; the Cabannes line is composed of the Brillouin doublet and the central Gross or Landau-Placzek line. The term 'Rayleigh line' should never be used.
Basin topology in dissipative chaotic scattering.
Seoane, Jesús M; Aguirre, Jacobo; Sanjuán, Miguel A F; Lai, Ying-Cheng
2006-06-01
Chaotic scattering in open Hamiltonian systems under weak dissipation is not only of fundamental interest but also important for problems of current concern such as the advection and transport of inertial particles in fluid flows. Previous work using discrete maps demonstrated that nonhyperbolic chaotic scattering is structurally unstable in the sense that the algebraic decay of scattering particles immediately becomes exponential in the presence of weak dissipation. Here we extend the result to continuous-time Hamiltonian systems by using the Henon-Heiles system as a prototype model. More importantly, we go beyond to investigate the basin structure of scattering dynamics. A surprising finding is that, in the common case where multiple destinations exist for scattering trajectories, Wada basin boundaries are common and they appear to be structurally stable under weak dissipation, even when other characteristics of the nonhyperbolic scattering dynamics are not. We provide numerical evidence and a geometric theory for the structural stability of the complex basin topology.