Exploiting Universality in Atoms with Large Scattering Lengths
Braaten, Eric
2012-05-31T23:59:59.000Z
The focus of this research project was atoms with scattering lengths that are large compared to the range of their interactions and which therefore exhibit universal behavior at sufficiently low energies. Recent dramatic advances in cooling atoms and in manipulating their scattering lengths have made this phenomenon of practical importance for controlling ultracold atoms and molecules. This research project was aimed at developing a systematically improvable method for calculating few-body observables for atoms with large scattering lengths starting from the universal results as a first approximation. Significant progress towards this goal was made during the five years of the project.
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15 16 17 18 19 20 21 22 23 24 25 Next Page Last Page Topic Index 1 Atomic-Molecular Condensates with Large Positive Scattering Length Nuclear Theory (arXiv) Summary: We show that...
Kaonic hydrogen atom and kaon-proton scattering length
Y. Yan
2009-05-29T23:59:59.000Z
Kaonic hydrogen is studied with various realistic potentials in an accurate numerical approach based on Sturmian functions. The kaon-proton scattering length extracted from the 1s energy shift of the kaonic hydrogen by applying the Deser-Trueman formula is severely inconsistent with the one derived by directly solving the scattering Schoedinger equation. We pay special attention to the recent measurement of the energy shift and decay width of the 1s kaonic hydrogen state by the DEAR Collaboration. After taking into account the large discrepancy between the extracted and directly-evaluated scattering lengths, we found theoretical predictions of most chiral SU(3) based models for the kaonic hydrogen decay width are consistent with the DEAR data. We warn the SIDDHARTA collaboration that it may not be reasonable to extract kaon-nucleon scattering lengths, by using the Coulomb-interaction corrected Deser-Truemab formula, from the planned measurement of kaonic hydrogen.
Can one extract the pi-neutron scattering length from pi-deuteron scattering?
A. Nogga; C. Hanhart
2005-11-02T23:59:59.000Z
We give a prove of evidence that the original power counting by Weinberg can be applied to estimate the contributions of the operators contributing to the pi-deuteron scattering length. As a consequence, pi-deuteron observables can be used to extract neutron amplitudes--in case of pi-deuteron scattering this means that the pi-neutron scattering length can be extracted with high accuracy. This result is at variance with recent claims. We discuss the origin of this difference.
Optical Scattering Lengths in Large Liquid-Scintillator Neutrino Detectors
Michael Wurm; Franz von Feilitzsch; Marianne Goeger-Neff; Martin Hofmann; Tobias Lachenmaier; Timo Lewke; Teresa Marrodan Undagoitita; Quirin Meindl; Randoplh Moellenberg; Lothar Oberauer; Walter Potzel; Marc Tippmann; Sebastian Todor; Christoph Traunsteiner; Juergen Winter
2010-04-06T23:59:59.000Z
For liquid-scintillator neutrino detectors of kiloton scale, the transparency of the organic solvent is of central importance. The present paper reports on laboratory measurements of the optical scattering lengths of the organic solvents PXE, LAB, and Dodecane which are under discussion for next-generation experiments like SNO+, Hanohano, or LENA. Results comprise the wavelength range from 415 to 440nm. The contributions from Rayleigh and Mie scattering as well as from absorption/re-emission processes are discussed. Based on the present results, LAB seems to be the preferred solvent for a large-volume detector.
Lambda-Neutron Scattering Lengths from Radiative K-minus Capture
W. R. Gibbs; S. A. Coon; H. K. Han; B. F. Gibson
2000-01-02T23:59:59.000Z
Radiative capture of the K-minus by the deuteron as a reaction for measurement of the Lambda-neutron scattering lengths. The use of spin information to separate the singlet and triplet scattering lengths is treated.
The K+ K+ scattering length from Lattice QCD
Silas Beane; Thomas Luu; Konstantinos Orginos; Assumpta Parreno; Martin Savage; Aaron Torok; Andre Walker-Loud
2007-09-11T23:59:59.000Z
The K+K+ scattering length is calculated in fully-dynamical lattice QCD with domain-wall valence quarks on the MILC asqtad-improved gauge configurations with fourth-rooted staggered sea quarks. Three-flavor mixed-action chiral perturbation theory at next-to-leading order, which includes the leading effects of the finite lattice spacing, is used to extrapolate the results of the lattice calculation to the physical value of mK + /fK + . We find mK^+ aK^+ K^+ = â~0.352 Â± 0.016, where the statistical and systematic errors have been combined in quadrature.
The bound coherent neutron scattering length of the oxygen isotopes
Fischer, Henry E [Institut Laue-Langevin (ILL); Simonson, J Michael {Mike} [ORNL; Neuefeind, Joerg C [ORNL; Lemmel, Hartmut [Technical University Vienna; Rauch, Helmut [E141 Atominstitut der Österreichischen Universitäten,; Zeidler, Anita [University of Bath; Salmon, Phil [University of Bath
2012-01-01T23:59:59.000Z
The technique of neutron interferometry was used to measure the bound coherent neutron scattering length bcoh of the oxygen isotopes 17O and 18O. From the measured difference in optical path between two water samples, either H2 17O or H2 18O versus H2 natO, where nat denotes the natural isotopic composition, we obtain bcoh , 17O = 5.867(4) fm and bcoh , 18O = 6.009(5) fm, based on the accurately known value of bcoh , natO = 5.805(4) fm which is equal to bcoh , 16O within the experimental uncertainty. Our results for bcoh , 17O and bcoh , 18O differ appreciably from the standard tabulated values of 5.6(5) fm and 5.84(7) fm, respectively. In particular, our measured scattering length contrast of 0.204(3) fm between 18O and natO is nearly a factor of 6 greater than the tabulated value, which renders feasible neutron diffraction experiments using 18O isotope substitution and thereby offers new possibilites for measuring the partial structure factors of oxygen-containing compounds, such as water.
SPIN-DEPENDENT SCATTERING LENGTHS OF SLOW NEUTRONS WITH NUCLEI BY PSEUDOMAGNETIC MEASUREMENTS
Boyer, Edmond
L-263 SPIN-DEPENDENT SCATTERING LENGTHS OF SLOW NEUTRONS WITH NUCLEI BY PSEUDOMAGNETIC MEASUREMENTS vu par les noyaux. Abstract. - The spin-dependent scattering length of slow neutrons by the nuclei 23 can be of practical importance in many thermal neutron scattering experiments. A new method, called
Microscopic calculation of the spin-dependent neutron scattering lengths on 3He
H. M. Hofmann; G. M. Hale
2003-04-16T23:59:59.000Z
We report on the spin.dependent neutron scattering length on 3He from a microscopic calculation of p-3H, n-3He, and d-2H scattering employing the Argonne v18 nucleon-nucleon potential with and without additional three-nucleon force. The results and that of a comprehensive R-matrix analysis are compared to a recent measurement. The overall agreement for the scattering lengths is quite good. The imaginary parts of the scattering lengths are very sensitive to the inclusion of three-nucleon forces, whereas the real parts are almost insensitive.
Fresnel zone effects in the scattering of sound by cylinders of various lengths
Stanton, Tim
Fresnel zone effects in the scattering of sound by cylinders of various lengths DanielT. Di-source/point-receivercombination.Numerically evaluatingthisexpressionshowedthescatteringcharacteristicstobedominatedbyFresnel zoneeffects·scillationsin thebackscatterversuslengthcurvecausedbyconstructiveand
Precision Measurement of the n-3He Incoherent Scattering Length Using Neutron Interferometry
M. G. Huber; M. Arif; T. C. Black; W. C. Chen; T. R. Gentile; D. S. Hussey; D. Pushin; F. E. Wietfeldt; L. Yang
2009-05-12T23:59:59.000Z
We report the first measurement of the low-energy neutron-$^3$He incoherent scattering length using neutron interferometry: $b_i' = (-2.512\\pm 0.012{statistical}\\pm0.014{systematic})$ fm. This is in good agreement with a recent calculation using the AV18+3N potential. The neutron-$^3$He scattering lengths are important for testing and developing nuclear potential models that include three nucleon forces, effective field theories for few-body nuclear systems, and neutron scattering measurements of quantum excitations in liquid helium. This work demonstrates the first use of a polarized nuclear target in a neutron interferometer.
Scattering lengths in SU(2) gauge theory with two fundamental fermions
R. Arthur; V. Drach; M. Hansen; A. Hietanen; C. Pica; F. Sannino
2014-12-15T23:59:59.000Z
We investigate non perturbatively scattering properties of Goldstone Bosons in an SU(2) gauge theory with two Wilson fermions in the fundamental representation. Such a theory can be used to build extensions of the Standard Model that unifies Technicolor and pseudo Goldstone composite Higgs models. The leading order contribution to the scattering amplitude of Goldstone bosons at low energy is given by the scattering lengths. In the context of technicolor extensions of the Standard Model the scattering lengths are constrained by WW scattering measurements. We first describe our setup and in particular the expected chiral symmetry breaking pattern. We then discuss how to compute them on the lattice and give preliminary results using finite size methods.
Richard Beyer; Markus Franke; Hans Joachim Schöpe; Eckhard Bartsch; Thomas Palberg
2014-12-02T23:59:59.000Z
Hard spheres are a well recognized model system of statistical physics and soft condensed matter. Their crystallization behaviour has been intensively studied at the structural length scale by Bragg light scattering and/or high resolution microscopy. We here present an improved light scattering apparatus capable to perform simultaneous measurements in the Bragg scattering regime and in the small angle regime. We give an account of its construction and demonstrate its performance for several examples of hard sphere and attractive hard sphere suspensions. Comparison of small angle to Bragg data allows a calibration of the sequence of events in time. We show how important complementary information can be gained from the small angle studies e.g. on the immediate environment of the growing crystals or the global scale crystallite distribution. We further demonstrate that processes occurring on larger length scales have a significant influence on the crystallization kinetics and the final micro-structure.
On the S-wave piD-scattering length in the relativistic field theory model of the deuteron
A. N. Ivanov; N. I. Troitskaya; M. Faber; H. Oberhummer
1997-01-16T23:59:59.000Z
The S-wave scattering length of the strong pion-deuteron (pi D) scattering is calculated in the relativistic field theory model of the deuteron suggested in [1,2].The theoretical result agrees well with the experimental data. The important role of the Delta-resonance contribution to the elastic pi D-scattering is confirmed.
Dean Lee; Thomas Schaefer
2005-09-07T23:59:59.000Z
We study cold dilute neutron matter on the lattice using an effective field theory. We work in the unitary limit in which the scattering length is much larger than the interparticle spacing. In this paper we focus on the equation of state at temperatures above the Fermi temperature and compare lattice simulations to the virial expansion on the lattice and in the continuum. We find that in the unitary limit lattice discretization errors in the second virial coefficient are significantly enhanced. As a consequence the equation of state does not show the universal scaling behavior expected in the unitary limit. We suggest that scaling can be improved by tuning the second virial coefficient rather than the scattering length.
Thermal behavior of {pi}-{pi} scattering lengths in the Nambu-Jona-Lasinio model
Loewe, M.; Ruiz, Jorge A.; Rojas, J. C. [Facultad de Fisica, Pontificia Universidad Catolica de Chile, Casilla 306, Santiago 22 (Chile); Departamento de Fisica, Universidad Catolica del Norte, Angamos 0610, Antofagasta (Chile)
2008-11-01T23:59:59.000Z
We calculate the thermal evolution of {pi}-{pi} scattering lengths, in the framework of the Nambu-Jona-Lasinio model. The thermal corrections were calculated at the one-loop level using thermofield dynamics. We present also results for the pion thermal mass. Our procedure implies the modeling of a propagating scalar meson as a resumation of chains of quark bubbles, which is presented explicitly. We compare our results with previous analysis of this problem in the framework of different theoretical approaches.
D. E. Gonzalez Trotter; F. Salinas; Q. Chen; A. S. Crowell; W. Gloeckle; C. R. Howell; C. D. Roper; D. Schmidt; I. Slaus; H. Tang; W. Tornow; R. L. Walter; H. Witala; Z. Zhou
1999-08-11T23:59:59.000Z
The present paper reports high-accuracy cross-section data for the 2H(n,nnp) reaction in the neutron-proton (np) and neutron-neutron (nn) final-state-interaction (FSI) regions at an incident mean neutron energy of 13.0 MeV. These data were analyzed with rigorous three-nucleon calculations to determine the 1S0 np and nn scattering lengths, a_np and a_nn. Our results are a_nn = -18.7 +/- 0.6 fm and a_np = -23.5 +/- 0.8 fm. Since our value for a_np obtained from neutron-deuteron (nd) breakup agrees with that from free np scattering, we conclude that our investigation of the nn FSI done simultaneously and under identical conditions gives the correct value for a_nn. Our value for a_nn is in agreement with that obtained in pion-deuteron capture measurements but disagrees with values obtained from earlier nd breakup studies.
Solution of A Class of Finite-Range Potentials with Large Scattering Length
Bimalendu Deb
2015-06-22T23:59:59.000Z
We show that there exists a class of finite-range model potentials that may be useful for describing resonant interactions with large scattering length at low energy. They are expressed in terms of the effective range $r_0$ and the $s$-wave scattering length $a_s$. The mathematical expression of the potential $V_+(r)$ with positive $a_s$ is different from that of the potential $V_{-}(r)$ with negative $a_s$. However, both reduce to the same form $V_{\\infty}$ in the unitarity limits $a_s \\rightarrow \\pm \\infty$. We derive scattering and bound-sate solutions of these potentials. By writing $V_{\\pm}(r) = V^{{\\rm PT}}(r) + V_{\\pm}^{\\epsilon}(r)$, where $ V^{{\\rm PT}}(r)$ is of the form of P\\"{o}schl-Teller potential and $V_{\\pm}^{\\epsilon}$ is expressed as a power series of the small parameter $\\epsilon = (\\sqrt{1 - 2 r_0/a_s})^{-1} - 1 $ when $a_s$ is large, we derive Green function of $V^{{\\rm PT}}(r)$ and thereby develop a perturbative method to obtain scattering solution of $V_{\\pm}(r)$ as a power series in $\\epsilon$. We describe the threshold behavior of scattering phase shift $\\delta_0$ in the unitarity limits and establish the connection of $\\delta_0$ with the strength of the P\\"{o}schl-Teller potential. This study may be important for developing an accurate description or better understanding of physics of strongly interacting ultracold atomic gases with tunable interactions.
T. C. Black; P. R. Huffman; D. L. Jacobson; W. M. Snow; K. Schoen; M. Arif; H. Kaiser; S. K. Lamoreaux; S. A. Werner
2003-05-21T23:59:59.000Z
We have performed the first high precision measurement of the coherent neutron scattering length of deuterium in a pure sample using neutron interferometry. We find b_nd = (6.665 +/- 0.004) fm in agreement with the world average of previous measurements using different techniques, b_nd = (6.6730 +/- 0.0045) fm. We compare the new world average for the nd coherent scattering length b_nd = (6.669 +/- 0.003) fm to calculations of the doublet and quartet scattering lengths from several modern nucleon-nucleon potential models with three-nucleon force (3NF) additions and show that almost all theories are in serious disagreement with experiment. This comparison is a more stringent test of the models than past comparisons with the less precisely-determined nuclear doublet scattering length of a_nd = (0.65 +/- 0.04) fm.
Determination of the eta'-proton scattering length in free space
E. Czerwinski; P. Moskal; M. Silarski; S. D. Bass; D. Grzonka; B. Kamys; A. Khoukaz; J. Klaja; W. Krzemien; W. Oelert; J. Ritman; T. Sefzick; J. Smyrski; A. Taschner; M. Wolke; M. Zielinski
2014-07-17T23:59:59.000Z
Taking advantage of both the high mass resolution of the COSY-11 detector and the high energy resolution of the low-emittance proton-beam of the Cooler Synchrotron COSY we determine the excitation function for the pp --> pp eta' reaction close-to-threshold. Combining these data with previous results we extract the scattering length for the eta'-proton potential in free space to be Re(a_{p eta'}) = 0+-0.43 fm and Im(a_{p eta'}) = 0.37(+0.40)(-0.16) fm.
Review of Indirect Methods Used to Determine the $^1S_0$ Neutron-Neutron Scattering Length
C. R. Howell
2008-05-08T23:59:59.000Z
We have determined a value for the $^1S_0$ neutron-neutron scattering length ($a_{nn}$) from high-precision measurements of time-of-flight spectra of neutrons from the $^2H(\\pi^-,n \\gamma)n$ capture reaction. The measurements were done at the Los Alamos Meson Physics Facility by the E1286 collaboration. The high spatial resolution of our gamma-ray detector enabled us to make a detailed assessment of the systematic uncertainties in our techniques. The value obtained in the present work is $a_{nn} = -18$.63 $\\pm $0.10 (statistical) $\\pm$ 0.44 (systematic) $\\pm$ 0.30 (theoretical) fm. This result is consistent with previous determinations of $a_{nn}$ from the $\\pi^-d$ capture reaction. We found that the analysis of the data with calculations that use a relativistic phase-space factor gives a more negative value for $a_{nn}$ by 0.33 fm over the analysis done using a nonrelativistic phase-space factor. Combining the present result with the previous ones from $\\pi^-d$ capture gives: $a_{nn} = - 18$.63 $\\pm$ 0.27 (expt) $\\pm$ 0.30 fm (theory). For the first time the combined statistical and systematic experimental uncertainty in $a_{nn}$ is smaller than the theoretical uncertainty and comparable to the uncertainty in the proton-proton $^1S_0$ scattering length ($a_{pp}$). This average value of $a_{nn}$ when corrected for the magnetic-moment interaction of the two neutrons becomes -18.9 $\\pm$ 0.4 fm which is 1.6 $\\pm$ 0.5 fm different from the recommended value of $a_{pp}$, thereby confirming charge symmetry breaking at the 1% confidence level.
Danon, Yaron
Scattering of 64 eV to 3 keV Neutrons from Polyethylene and Graphite and the Coherence Length 12180, USA (Received 31 August 2005; published 8 February 2006) We measured the neutron scattering by the neutron coherence length. The scattered intensity ratios were found to conform to conventional
S. Ceci; D. Hrupec; A. Svarc
2001-04-12T23:59:59.000Z
Using the new set of dd --> eta alpha near threshold experimental data, the estimate of the importance of the nucleon-nucleon correlations for the eta alpha S-wave scattering length in the multiple scattering theory is obtained using the low-energy scattering length model. The contribution turns out to be much bigger then previously believed. The pi-eta mixing angle is extracted using the experimental data on the dd --> eta alpha and dd --> pi alpha processes. The model is dominated by the subthreshold extrapolation recipe for the eta alpha scattering amplitudes. When the recipe is chosen the model is completely insensitive to the eta alpha parameters for the subthreshold value of the eta cm momentum of p_{eta}^2 = -(0.46)^2 fm^{-2}. Provided that the subthreshold extrapolation recipe is correct, a good estimate of the pi-eta mixing angle is obtained, if the experimental cross sections for the dd --> pi alpha reaction at the corresponding deuteron input energy are taken from the literature.
L. Debenjak; P. Achenbach; J. Pochodzalla; T. Saito
Charged particle identification at the PANDA experiment will be performed over a wide range of momenta by ?erenkov detectors. One option to identify higher momentum charged particles under small polar angles could be the use of silica aerogels as radiator. Simultaneously, an aerogel ?erenkov counter is being designed for the Kaos spectrometer at the Mainz Microtron MAMI for the discrimination between kaons and pions of momenta ? 1GeV/c. For the simulation of such detectors, the optical properties of the aerogel are needed as input data. We have measured the wavelength dependence of the transmittance (T) and reflectivity (R) of high density aerogel with n ? 1.07, made by Chiba U. in Japan. The characteristic absorption length (?abs) and scattering length (?scat) were extracted by fitting ?abs and ?scat to T. Table 1: The absorption and scattering lengths at different aerogel thicknesses (at ? = 500 nm). Deviations of values at different thicknesses may indicate that the simple powerlaw dependance assumed in Eq. (2) is inappropriate, as also established by [2]. d 2 cm 4 cm 9 cm ?abs 10.1 cm 9.1 cm 7.9 cm ?scat 10.8 cm 13.7 cm 13.5 cm The results are in fair agreement with the values obtained by [1]. These parameters have also been measured at different thicknesses of the aerogel by selecting different tile orientations. The corresponding absorption and scattering lengths at the wavelength seen by PMTs (? ? 500 nm) are shown in Table 1. Such high losses in the aerogel lead to a very low number of deteced photons. Figure 1: Transmittance (T) and reflectivity (R) as a function of the wavelength for silica aerogel with n ? 1.07. The transmittance between 200 nm and 800 nm of two aerogel tiles has been measured at different positions on the surface to scan for potential inhomogeneity and to obtain averaged values, see Fig. 1. From these measurements the scattering length, the absorption length and the attenuation length have been deduced by applying the following relation T(?) = (1 ? R(?))exp
M. G. Huber; M. Arif; W. C. Chen; T. R. Gentile; D. S. Hussey; T. C. Black; D. A. Pushin; C. B. Shahi; F. E. Wietfeldt; L. Yang
2014-09-30T23:59:59.000Z
We report a determination of the n-$^3$He scattering length difference $\\Delta b^{\\prime} = b_{1}^{\\prime}-b_{0}^{\\prime} = $ ($-5.411$ $\\pm$ $0.031$ (statistical) $\\pm$ $0.039$ (systematic)) fm between the triplet and singlet states using a neutron interferometer. This revises our previous result $\\Delta b^{\\prime} = $ (-5.610 $\\pm$ $0.027$ (statistical) $\\pm$ $0.032$ (systematic) fm obtained using the same technique in 2008. This revision is due to a re-analysis of the 2008 experiment that includes a more robust treatment of the phase shift caused by magnetic field gradients near the $^3$He cell. Furthermore, we more than doubled our original data set from 2008 by acquiring six months of additional data in 2013. Both the new data set and a re-analysis of the older data are in good agreement. Scattering lengths of low Z isotopes are valued for use in few-body nuclear effective field theories, provide important tests of modern nuclear potential models and in the case of $^3$He aid in the interpretation of neutron scattering from quantum liquids. The difference $\\Delta b^{\\prime}$ was determined by measuring the relative phase shift between two incident neutron polarizations caused by the spin-dependent interaction with a polarized $^3$He target. The target $^3$He gas was sealed inside a small, flat windowed glass cell that was placed in one beam path of the interferometer. The relaxation of $^3$He polarization was monitored continuously with neutron transmission measurements. The neutron polarization and spin flipper efficiency were determined separately using $^3$He analyzers and two different polarimetry analysis methods. A summary of the measured scattering lengths for n-$^3$He with a comparison to nucleon interaction models is given.
Richard Beyer; Markus Franke; Hans Joachim Schöpe; Eckhard Bartsch; Thomas Palberg
2015-05-11T23:59:59.000Z
Hard sphere suspensions are well recognized model systems of statistical physics and soft condensed matter. We here investigate the temporal evolution of the immediate environment of nucleating and growing crystals and/or their global scale distribution using time resolved Small Angle Light Scattering (SALS). Simultaneously performed Bragg scattering (BS) measurements provide an accurate temporal gauging of the sequence of events. We apply this approach to studies of re-crystallization in several different shear molten hard sphere and attractive hard sphere samples with the focus being on the diversity of observable signal shapes and their change in time. We demonstrate that depending on the preparation conditions different processes occur on length scales larger than the structural scale which significantly influence both the crystallization kinetics and the final micro-structure. By careful analysis of the SALS signal evolution and by comparing different suggestions for small angle signal shapes to our data we can for most cases identify the processes leading to the observed signals. These include phase contrast form factor scattering from depletion zones during formation and overlap as well as during gelation, amplitude contrast form factor scattering by more transparent crystals, and structure factor scattering from late stage inter-crystallite ordering. The large variety of different small angle signals thus in principle contains valuable information complementary to that gained from Bragg scattering or microscopy. Our comparison, however, also shows that further refinement and adaptation of the theoretical expressions to the sample specific boundary conditions is desired for a quantitative kinetic analysis of micro-structural evolution.
A. B. Popov; T. Yu. Tretyakova
2008-12-30T23:59:59.000Z
We discuss the experimental data on the n,e-scattering length bne and the values of mean square charge radius of the neutron obtained from them. It is shown that the accumulated during the last 50 years most significant experimental estimates of the bne are not contradictory and lead to the average value =-0.1178+-0.0037 fm^2. Assuming that all the authors have underestimated the errors of their measurements by a factor of 1.7, the combined fit of all available experimental data would lead to Chi^2~1 per degree of freedom. Different modern theoretical predictions of are considered. They are found to be in a good agreement with the obtained experimental value . However the existing theoretical description of the structure of neutron does not provide a value of with a sufficient accuracy.
Small Angle Neutron Scattering Study of Conformation of Oligo(ethylene glycol)- Grafted Polystyrene Fengjun Hua,2 Kunlun Hong,2 and Jimmy W. Mays2 1Neutron Scattering Sciences Division, ORNL 2Center
V. P. Levashev
2008-12-22T23:59:59.000Z
We have studied the relations between the neutron-triton scattering lengths and effective ranges and the corresponding quantities for the p --$^{3}$He scattering in the framework of the potential model with an effective nucleon-nucleus interaction in the form of a $\\delta $-shell potential. It is shown that the Coulomb renormalization of the pure nuclear scattering lengths does not change the relation well established for the n + $^{3}$H system between the lengths: $A^{1} scattering lengths which give preference to set I of the phase analysis performed by E.A. George et al. (2003), which corresponds to the inequality $A^{1}_{nc} scattering lengths.
Sprouse, Gene D. [American Physical Society (United States)
2011-07-15T23:59:59.000Z
Technological changes have moved publishing to electronic-first publication where the print version has been relegated to simply another display mode. Distribution in HTML and EPUB formats, for example, changes the reading environment and reduces the need for strict pagination. Therefore, in an effort to streamline the calculation of length, the APS journals will no longer use the printed page as the determining factor for length. Instead the journals will now use word counts (or word equivalents for tables, figures, and equations) to establish length; for details please see http://publish.aps.org/authors/length-guide. The title, byline, abstract, acknowledgment, and references will not be included in these counts allowing authors the freedom to appropriately credit coworkers, funding sources, and the previous literature, bringing all relevant references to the attention of readers. This new method for determining length will be easier for authors to calculate in advance, and lead to fewer length-associated revisions in proof, yet still retain the quality of concise communication that is a virtue of short papers.
X-ray and Neutron Scattering Studies of Magnetic Domain Dynamics and Spin Structures /
Chen, San-Wen
2014-01-01T23:59:59.000Z
Stanley. X-ray and neutron scattering from rough surfaces.1988. [3] R. Pynn. Neutron scattering by rough surfaces at39] V. F. Sears. Neutron scattering lengths and cross
Scattering lengths for collisions of hydrogen and deuterium atoms
Chu, X.; Jamieson, M.J.
Chu,X. Jamieson,M.J. Dalgarno,A. Journal of Physics B: Atomic, Molecular and Optical Physics, Vol. 36 pp L415-L418
Neutron-3H and Proton-3He Zero Energy Scattering
M. Viviani; S. Rosati; A. Kievsky
1998-07-23T23:59:59.000Z
The Kohn variational principle and the (correlated) Hyperspherical Harmonics technique are applied to study the n-3H and p-3He scattering at zero energy. Predictions for the singlet and triplet scattering lengths are obtained for non-relativistic nuclear Hamiltonians including two- and three-body potentials. The calculated n-3H total cross section agrees well with the measured value, while some small discrepancy is found for the coherent scattering length. For the p-3He channel, the calculated scattering lengths are in reasonable agreement with the values extrapolated from the measurements made above 1 MeV.
Spin-dependent scattering and absorption of thermal neutrons on dynamically polarized nuclei
Paris-Sud XI, Université de
957 Spin-dependent scattering and absorption of thermal neutrons on dynamically polarized nuclei H neutrons and polarized nuclei have been used to measure spin-dependent scattering lengths and absorption cross sections of slow (S-wave) neutrons on nuclei. In order to obtain those scattering lengths
Formation lengths of hadrons in lepto-production
Levon Grigoryan
2012-09-28T23:59:59.000Z
The average formation lengths of the hadrons produced during the deep inelastic scattering (DIS) of leptons on protons are studied in the framework of the symmetric Lund model. It is shown that these formation lengths essentially depend on the electric charges of the hadron. For electro-production and charged current (CC) neutrino-production, the average formation lengths of positively charged particles are larger than those of negatively charged antiparticles. This situation is reversed for CC antineutrino-production. In all the mentioned cases, the main mechanism is the direct production of hadrons. The additional mechanism of hadron production, through the decay of resonances, is essential only for pions and leads to a decrease in the average formation lengths.
Comparing Membrane Simulations to Scattering Experiments: Introducing the SIMtoEXP Software
Nagle, John F.
of biomembrane simulations with experimental X-ray and neutron scattering data. It has the following features: (1 the electron density e(z) and neutron scattering length density m(z) profiles along the z direction (i.e., nor simulation Á X-ray scattering Á Neutron scattering Á Computer software Introduction It is well recognized
MAGNETIC NEUTRON SCATTERING. And Recent Developments in the Triple Axis Spectroscopy
Johnson, Peter D.
Chapter 1 MAGNETIC NEUTRON SCATTERING. And Recent Developments in the Triple Axis Spectroscopy Igor.................................................................................... 2 2. Neutron interaction with matter and scattering cross-section ........ 6 2.1 Basic scattering theory and differential cross-section................ 7 2.2 Neutron interactions and scattering lengths
Intravalley Multiple Scattering of Quasiparticles in Graphene
J. Y. Vaishnav; Justin Q. Anderson; Jamie D. Walls
2011-05-28T23:59:59.000Z
We develop a theoretical description of intravalley scattering of quasiparticles in graphene from multiple short-range scatterers of size much greater than the carbon-carbon bond length. Our theory provides a method to rapidly calculate the Green's function in graphene for arbitrary configurations of scatterers. We demonstrate that non-collinear multiple scattering trajectories generate pseudospin rotations that alter quasiparticle interference, resulting in significant modifications to the shape, intensity, and pattern of the interference fringes in the local density of states (LDOS). We illustrate these effects via theoretical calculations of the LDOS for a variety of scattering configurations in single layer graphene. A clear understanding of impurity scattering in graphene is a step towards exploiting graphene's unique properties to build future devices.
Estimate of the scatter component in SPECT
Ivanovic, M.; Weber, D.A. [Univ. of California, Sacramento, CA (United States); Loncaric, S. [Univ. of Zagreb (Croatia)
1996-12-31T23:59:59.000Z
Analytical expressions that describe the dependence of slopes and amplitudes of the scatter distribution functions (SDF) on source depth and media density are used to estimate a scatter component in SPECT projection data. Since the ratio of detected scattered to total photons (S/T), SDF amplitude and slope depend strongly on line source length (SL) used to obtain SDFs, we compared estimated scattered components using SDFs, obtained for lengths of 2-21 cm. At 10 cm source depth, S/T changes from 0.19 to 0.36 when SL changes from 2 to 21 cm. Scatter amplitude`s dependence on source depth (d) in water was described by 6.38e{sup -0.186d} for a 2 cm and 16.15e{sup -0.129d} for a 21 cm SL. Slope was described by 0.292d{sup -0.601} for a cm SL and by 0.396d{sup -0.82} for a 21 cm SL. The estimated scatter components are compared with simulated SPECT projection data obtained with Monte Carlo modeling of six hot spheres placed in a cylindrical water filled phantom. The comparison of estimated with simulated total counts/projection shows very good agreement when approaching SDF for a point source (the % difference varied from 2 to 13% for 2 cm SL). Significant overestimate is seen when source length increases.
Suppression of Quantum Scattering in Strongly Confined Systems
Kim, J. I. [Departamento de Pesquisas, Altanova, R. Silva Teles 712, CEP 03026-000, Bras, Sa(tilde sign)o Paulo, SP, Brasil (Brazil); Melezhik, V. S. [Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, Dubna, Moscow Region 141980 (Russian Federation); Schmelcher, P. [Physikalisches Institut, Universitaet Heidelberg, Philosophenweg 12, 69120 Heidelberg (Germany); Theoretische Chemie, Institut fuer Physikalische Chemie, Universitaet Heidelberg, Im Neuenheimer Feld 229, 69120 Heidelberg (Germany)
2006-11-10T23:59:59.000Z
We demonstrate that scattering of particles strongly interacting in three dimensions (3D) can be suppressed at low energies in a quasi-one-dimensional (1D) confinement. The underlying mechanism is the interference of the s- and p-wave scattering contributions with large s- and p-wave 3D scattering lengths being a necessary prerequisite. This low-dimensional quantum scattering effect might be useful in 'interacting' quasi-1D ultracold atomic gases, guided atom interferometry, and impurity scattering in strongly confined quantum wire-based electronic devices.
Continuously variable focal length lens
Adams, Bernhard W; Chollet, Matthieu C
2013-12-17T23:59:59.000Z
A material preferably in crystal form having a low atomic number such as beryllium (Z=4) provides for the focusing of x-rays in a continuously variable manner. The material is provided with plural spaced curvilinear, optically matched slots and/or recesses through which an x-ray beam is directed. The focal length of the material may be decreased or increased by increasing or decreasing, respectively, the number of slots (or recesses) through which the x-ray beam is directed, while fine tuning of the focal length is accomplished by rotation of the material so as to change the path length of the x-ray beam through the aligned cylindrical slows. X-ray analysis of a fixed point in a solid material may be performed by scanning the energy of the x-ray beam while rotating the material to maintain the beam's focal point at a fixed point in the specimen undergoing analysis.
Enhancement of Compton Scattering by an Effective Coupling Constant
Bernardo Barbiellini; Piero Nicolini
2011-08-08T23:59:59.000Z
A robust thermodynamic argument shows that a small reduction of the effective coupling constant $\\alpha$ of QED greatly enhances the Compton scattering cross section and that the Thomson scattering length is connected to a fundamental scale $\\lambda$. A discussion provides a possible quantum interpretation of this enormous sensitivity to changes in the effective coupling constant $\\alpha$.
Continuous lengths of oxide superconductors
Kroeger, Donald M. (Knoxville, TN); List, III, Frederick A. (Andersonville, TN)
2000-01-01T23:59:59.000Z
A layered oxide superconductor prepared by depositing a superconductor precursor powder on a continuous length of a first substrate ribbon. A continuous length of a second substrate ribbon is overlaid on the first substrate ribbon. Sufficient pressure is applied to form a bound layered superconductor precursor powder between the first substrate ribbon and the second substrate ribbon. The layered superconductor precursor is then heat treated to establish the oxide superconducting phase. The layered oxide superconductor has a smooth interface between the substrate and the oxide superconductor.
[49] INTERSUBUNIT MEASUREMENTS BY NEUTRON SCATTERING 629 ribosomal 30 S subparticle in its lateral Neutron Scattering By PETER B. MOOREand DONALDM. ENGELMAN Several years ago we suggested that neutron.28 " The scattering lengths are taken from G. E. Bacon, "Neutron Scattering." Oxford Univ. Press (Clarendon
Imaging with Scattered Neutrons
H. Ballhausen; H. Abele; R. Gaehler; M. Trapp; A. Van Overberghe
2006-10-30T23:59:59.000Z
We describe a novel experimental technique for neutron imaging with scattered neutrons. These scattered neutrons are of interest for condensed matter physics, because they permit to reveal the local distribution of incoherent and coherent scattering within a sample. In contrast to standard attenuation based imaging, scattered neutron imaging distinguishes between the scattering cross section and the total attenuation cross section including absorption. First successful low-noise millimeter-resolution images by scattered neutron radiography and tomography are presented.
Stimulated Raman scattering in large plasmas
Phillion, D.W.; Banner, D.L.
1980-11-06T23:59:59.000Z
Stimulated Raman scattering is of concern to laser fusion since it can create a hot electron environment which can increase the difficulty of achieving high final fuel densities. In earlier experiments with one micron laser light, the energy measured in Raman-scattered light has been insignificant. But these experiments were done with, at most, about 100 joules of laser energy. The Raman instability has a high threshold which also requires a large plasma to be irradiated with a large diameter spot. Only with a long interaction length can the Raman-scattered light wave convectively grow to a large amplitude, and only in recent long pulse, high energy experiments (4000 joules in 2 ns) at the Shiva laser facility have we observed as much as several percent of the laser light to be Raman-scattered. We find that the Raman instability has a much lower intensity threshold for longer laser pulselength and larger laser spot size on a solid target.
Distributions of off-diagonal scattering matrix elements: Exact results
Nock, A., E-mail: a.nock@qmul.ac.uk; Kumar, S., E-mail: skumar.physics@gmail.com; Sommers, H.-J., E-mail: h.j.sommers@uni-due.de; Guhr, T., E-mail: thomas.guhr@uni-due.de
2014-03-15T23:59:59.000Z
Scattering is a ubiquitous phenomenon which is observed in a variety of physical systems which span a wide range of length scales. The scattering matrix is the key quantity which provides a complete description of the scattering process. The universal features of scattering in chaotic systems is most generally modeled by the Heidelberg approach which introduces stochasticity to the scattering matrix at the level of the Hamiltonian describing the scattering center. The statistics of the scattering matrix is obtained by averaging over the ensemble of random Hamiltonians of appropriate symmetry. We derive exact results for the distributions of the real and imaginary parts of the off-diagonal scattering matrix elements applicable to orthogonally-invariant and unitarily-invariant Hamiltonians, thereby solving a long standing problem. -- Highlights: •Scattering problem in complex or chaotic systems. •Heidelberg approach to model the chaotic nature of the scattering center. •A novel route to the nonlinear sigma model based on the characteristic function. •Exact results for the distributions of off-diagonal scattering-matrix elements. •Universal aspects of the scattering-matrix fluctuations.
Nano-wires with surface disorder: Giant localization lengths and quantum-to-classical crossover
J. Feist; A. Bäcker; R. Ketzmerick; S. Rotter; B. Huckestein; J. Burgdörfer
2006-09-14T23:59:59.000Z
We investigate electronic quantum transport through nano-wires with one-sided surface roughness. A magnetic field perpendicular to the scattering region is shown to lead to exponentially diverging localization lengths in the quantum-to-classical crossover regime. This effect can be quantitatively accounted for by tunneling between the regular and the chaotic components of the underlying mixed classical phase space.
Ps-atom scattering at low energies
Fabrikant, I I
2015-01-01T23:59:59.000Z
A pseudopotential for positronium-atom interaction, based on electron-atom and positron-atom phase shifts, is constructed, and the phase shifts for Ps-Kr and Ps-Ar scattering are calculated. This approach allows us to extend the Ps-atom cross sections, obtained previously in the impulse approximation [Phys. Rev. Lett. 112, 243201 (2014)], to energies below the Ps ionization threshold. Although experimental data are not available in this low-energy region, our results describe well the tendency of the measured cross sections to drop with decreasing velocity at $v<1$ a.u. Our results show that the effect of the Ps-atom van der Waals interaction is weak compared to the polarization interaction in electron-atom and positron-atom scattering. As a result, the Ps scattering length for both Ar and Kr is positive, and the Ramsauer-Townsend minimum is not observed for Ps scattering from these targets. This makes Ps scattering quite different from electron scattering in the low-energy region, in contrast to the inter...
dynamics that occur in the ®nal stages of protein folding, we have used neutron scattering to probe- lastic neutron scattering (IQNS). The IQNS results show length scale dependent, pico-second dynamics neutron scattering; a-lactalbumin*Corresponding author Introduction Proteins can form collapsed, partially
Nonlinear X-ray Compton Scattering
Fuchs, Matthias; Chen, Jian; Ghimire, Shambhu; Shwartz, Sharon; Kozina, Michael; Jiang, Mason; Henighan, Thomas; Bray, Crystal; Ndabashimiye, Georges; Bucksbaum, P H; Feng, Yiping; Herrmann, Sven; Carini, Gabriella; Pines, Jack; Hart, Philip; Kenney, Christopher; Guillet, Serge; Boutet, Sebastien; Williams, Garth; Messerschmidt, Marc; Seibert, Marvin; Moeller, Stefan; Hastings, Jerome B; Reis, David A
2015-01-01T23:59:59.000Z
X-ray scattering is a weak linear probe of matter. It is primarily sensitive to the position of electrons and their momentum distribution. Elastic X-ray scattering forms the basis of atomic structural determination while inelastic Compton scattering is often used as a spectroscopic probe of both single-particle excitations and collective modes. X-ray free-electron lasers (XFELs) are unique tools for studying matter on its natural time and length scales due to their bright and coherent ultrashort pulses. However, in the focus of an XFEL the assumption of a weak linear probe breaks down, and nonlinear light-matter interactions can become ubiquitous. The field can be sufficiently high that even non-resonant multiphoton interactions at hard X-rays wavelengths become relevant. Here we report the observation of one of the most fundamental nonlinear X-ray-matter interactions, the simultaneous Compton scattering of two identical photons producing a single photon at nearly twice the photon energy. We measure scattered...
Scattering of low-energy electrons and positrons by atomic beryllium: Ramsauer-Townsend effect
Reid, David D
2014-01-01T23:59:59.000Z
Total cross sections for the scattering of low-energy electrons and positrons by atomic beryllium in the energy range below the first inelastic thresholds are calculated. A Ramsauer-Townsend minimum is seen in the electron scattering cross sections, while no such effect is found in the case of positron scattering. A minimum total cross section of 0.016 a.u. at 0.0029 eV is observed for the electron case. In the limit of zero energy, the cross sections yield a scattering length of -0.61 a.u. for electron and +13.8 a.u. for positron scattering.
Environmental Stresses Disrupt Telomere Length Homeostasis
Shamir, Ron
Environmental Stresses Disrupt Telomere Length Homeostasis Gal Hagit Romano1,2,3. , Yaniv Harari1 and Biotechnology, Tel Aviv University, Tel Aviv, Israel, 2 Blavatnik School of Computer Science, Tel Aviv response to environmental signals. These results demonstrate that telomere length can be manipulated
Variable Length Path Coupling Thomas P. Hayes
Hayes, Thomas
length path coupling theorem, we im- prove the upper bound on the mixing time of the Glauber dynamics . By a "coupling" for this chain, we will mean a joint stochastic process (Xt, Yt) on × such that eachVariable Length Path Coupling Thomas P. Hayes Eric Vigoda July 17, 2006 Abstract We present a new
E. Borie
2013-02-05T23:59:59.000Z
A recent proposal to measure the proton form factor by means of muon-proton scattering will use muons which are not ultrarelativistic (and also not nonrelativistic). The usual equations describing the scattering cross section use the approximation that the scattered lepton (usually an electron) is ultrarelativistic, with v/c approximately equal to 1. Here the cross section is calculated for all values of the energy. It agrees with the standard result in the appropriate limit.
The Fiber Optic Multiplexed Thomson Scattering Diagnostic for the ETE Tokamak
The Fiber Optic Multiplexed Thomson Scattering Diagnostic for the ETE Tokamak M. P. Alonso1 , L. A system and the details of the proposed multiplexed Thomson scattering diagnostic based on a fiber optic-lengths optical fibers to relay the light signals to the same polychromator [4]. The proposed system uses large
The Fiber Optic Multiplexed Upgraded Thomson Scattering Diagnostic for the ISTTOK Tokamak
The Fiber Optic Multiplexed Upgraded Thomson Scattering Diagnostic for the ISTTOK Tokamak M. P by different length optical fibers used to relay the scattered light to a single spectrometer. 2. Thomson vessel and opposite to the collection lenses. Figure 1 shows the present two fiber optic Thomson
Environment scattering in GADRAS.
Thoreson, Gregory G.; Mitchell, Dean James; Theisen, Lisa Anne; Harding, Lee T.
2013-09-01T23:59:59.000Z
Radiation transport calculations were performed to compute the angular tallies for scattered gamma-rays as a function of distance, height, and environment. Green's Functions were then used to encapsulate the results a reusable transformation function. The calculations represent the transport of photons throughout scattering surfaces that surround sources and detectors, such as the ground and walls. Utilization of these calculations in GADRAS (Gamma Detector Response and Analysis Software) enables accurate computation of environmental scattering for a variety of environments and source configurations. This capability, which agrees well with numerous experimental benchmark measurements, is now deployed with GADRAS Version 18.2 as the basis for the computation of scattered radiation.
Lujan Neutron Scattering Center
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
the inadvertent spread of Technetium 99 by employees and contractors at the Lujan Neutron Scattering Center August 27, 2012-The Laboratory is investigating the inadvertent...
Probing the Conformational Distributions of Sub-Persistence Length DNA
Mastroianni, Alexander; Sivak, David; Geissler, Phillip; Alivisatos, Paul
2009-06-08T23:59:59.000Z
We have measured the bending elasticity of short double-stranded DNA (dsDNA) chains through small-angle X-ray scattering from solutions of dsDNA-linked dimers of gold nanoparticles. This method, which does not require exertion of external forces or binding to a substrate, reports on the equilibrium distribution of bending fluctuations, not just an average value (as in ensemble FRET) or an extreme value (as in cyclization), and in principle provides a more robust data set for assessing the suitability of theoretical models. Our experimental results for dsDNA comprising 42-94 basepairs (bp) are consistent with a simple worm-like chain model of dsDNA elasticity, whose behavior we have determined from Monte Carlo simulations that explicitly represent nanoparticles and their alkane tethers. A persistence length of 50 nm (150 bp) gave a favorable comparison, consistent with the results of single-molecule force-extension experiments on much longer dsDNA chains, but in contrast to recent suggestions of enhanced flexibility at these length scales.
Effect of Minimal lengths on Electron Magnetism
Khireddine Nouicer
2007-07-13T23:59:59.000Z
We study the magnetic properties of electron in a constant magnetic field and confined by a isotropic two dimensional harmonic oscillator on a space where the coordinates and momenta operators obey generalized commutation relations leading to the appearance of a minimal length. Using the momentum space representation we determine exactly the energy eigenvalues and eigenfunctions. We prove that the usual degeneracy of Landau levels is removed by the presence of the minimal length in the limits of weak and strong magnetic field.The thermodynamical properties of the system, at high temperature, are also investigated showing a new magnetic behavior in terms of the minimal length.
Rainer Jakob
2000-10-16T23:59:59.000Z
We present the handbag contribution to Wide Angle Compton Scattering (WACS) at moderately large momentum transfer obtained with a proton distribution amplitude close to the asymptotic form. In comparison it is found to be significantly larger than results from the hard scattering (pQCD) approach.
Hurd, A.J.
1989-01-01T23:59:59.000Z
The realization that structures in Nature often can be described by Mandelbrot's ''fractals'' has led to a revolution in many areas of physics. The interaction of waves with fractal systems has, understandably, become intensely studied since scattering is the method of choice to probe delicate fractal structures such as chainlike particle aggregates. Not all of these waves are electromagnetic: neutron scattering, for example, is an important complementary tool to structural studies by x-ray and light scattering. Since the phenomenology of small-angle neutron scattering (SANS), as it is applied to fractal systems, is identical to that of small-angle x-ray scattering (SAXS), it falls within the scope of this Working Paper. 9 refs.
Inheritance of Cotton Fiber Length and Strength
Joy, Kolbyn Seth
2014-04-23T23:59:59.000Z
hybrids. General combining ability (GCA) and specific combining ability (SCA) were estimated according to Griffing’s diallel Model I, Method 4 for lint percent, high volume instrument (HVI) upper half mean length (UHML), fiber bundle strength (Str...
Carbon Nanotubes: Measuring Dispersion and Length
Fagan, Jeffrey A.; Bauer, Barry J.; Hobbie, Erik K.; Becker, Matthew L.; Hight-Walker, Angela; Simpson, Jeffrey R.; Chun, Jaehun; Obrzut, Jan; Bajpai, Vardhan; Phelan, Fred R.; Simien, Daneesh; Yeon Huh, Ji; Migler, Kalman B.
2011-03-01T23:59:59.000Z
Advanced technological uses of single-wall carbon nanotubes (SWCNTs) rely on the production of single length and chirality populations that are currently only available through liquid phase post processing. The foundation of all of these processing steps is the attainment of individualized nanotube dispersion in solution; an understanding of the collodial properties of the dispersed SWCNTs can then be used to designed appropriate conditions for separations. In many instances nanotube size, particularly length, is especially active in determining the achievable properties from a given population, and thus there is a critical need for measurement technologies for both length distribution and effective separation techniques. In this Progress Report, we document the current state of the art for measuring dispersion and length populations, including separations, and use examples to demonstrate the desirability of addressing these parameters.
A length operator for canonical quantum gravity
T. Thiemann
1996-06-29T23:59:59.000Z
We construct an operator that measures the length of a curve in four-dimensional Lorentzian vacuum quantum gravity. We work in a representation in which a $SU(2)$ connection is diagonal and it is therefore surprising that the operator obtained after regularization is densely defined, does not suffer from factor ordering singularities and does not require any renormalization. We show that the length operator admits self-adjoint extensions and compute part of its spectrum which like its companions, the volume and area operators already constructed in the literature, is purely discrete and roughly is quantized in units of the Planck length. The length operator contains full and direct information about all the components of the metric tensor which faciliates the construction of a new type of weave states which approximate a given classical 3-geometry.
Janos Polonyi; Karima Zazoua
2012-03-11T23:59:59.000Z
The cross section of elastic electron-proton scattering taking place in an electron gas is calculated within the Closed Time Path method. It is found to be the sum of two terms, one being the expression in the vacuum except that it involves dressing due to the electron gas. The other term is due to the scattering particles-electron gas entanglement. This term dominates the usual one when the exchange energy is in the vicinity of the Fermi energy. Furthermore it makes the trajectories of the colliding particles more consistent and the collision more irreversible, rendering the scattering more classical in this regime.
Scattering Solar Thermal Concentrators
Broader source: Energy.gov [DOE]
"This fact sheet describes a scattering solar thermal concentrators project awarded under the DOE's 2012 SunShot Concentrating Solar Power R&D award program. The team, led by the Pennsylvania State University, is working to demonstrate a new, scattering-based approach to concentrating sunlight that aims to improve the overall performance and reliability of the collector field. The research team aims to show that scattering solar thermal collectors are capable of achieving optical performance equal to state-of-the-art parabolic trough systems, but with the added benefits of immunity to wind-load tracking error, more efficient land use, and utilization of stationary receivers."
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Compton Scattering of Picosecond Electron and CO2 beams T. Hirose (TMU) @BNL user meeting, Jan. 31, 2002 JapanUS cooperation in high energy physics (Supported by JSPS from 1998)...
Sighting optics including an optical element having a first focal length and a second focal length
Crandall, David Lynn (Idaho Falls, ID)
2011-08-01T23:59:59.000Z
One embodiment of sighting optics according to the teachings provided herein may include a front sight and a rear sight positioned in spaced-apart relation. The rear sight includes an optical element having a first focal length and a second focal length. The first focal length is selected so that it is about equal to a distance separating the optical element and the front sight and the second focal length is selected so that it is about equal to a target distance. The optical element thus brings into simultaneous focus, for a user, images of the front sight and the target.
Absorption Lengths in the Holographic Plasma
Irene Amado; Carlos Hoyos; Karl Landsteiner; Sergio Montero
2007-07-11T23:59:59.000Z
We consider the effect of a periodic perturbation with frequency $\\omega$ on the holographic N=4 plasma represented by the planar AdS black hole. The response of the system is given by exponentially decaying waves. The corresponding complex wave numbers can be found by solving wave equations in the AdS black hole background with infalling boundary conditions on the horizon in an analogous way as in the calculation of quasinormal modes. The complex momentum eigenvalues have an interpretation as poles of the retarded Green's functions, where the inverse of the imaginary part gives an absorption length $\\lambda$. At zero frequency we obtain the screening length for a static field. These are directly related to the glueball masses in the dimensionally reduced theory. We also point out that the longest screening length corresponds to an operator with non-vanishing R-charge and thus does not have an interpretation as a QCD3 glueball.
Fracture Properties From Seismic Scattering
Burns, Daniel R.
2007-01-01T23:59:59.000Z
Fractures scatter seismic energy and this energy can be analyzed to provide information about fracture
S-wave scattering lengths and effective ranges for collisions of ground state Be atoms
Jamieson, M.J.
Jamieson,M.J. Cheung,A.S.C. Ouerdane,H. Jeung,G.H. Geum,N. Journal of Physics B, Volume 40 pp 3497-3504
Crystal diffraction lens with variable focal length
Smither, R.K.
1991-04-02T23:59:59.000Z
A method and apparatus for altering the focal length of a focusing element of one of a plurality of pre-determined focal lengths by changing heat transfer within selected portions of the element by controlled quantities is disclosed. Control over heat transfer is accomplished by manipulating one or more of a number of variables, including: the amount of heat or cold applied to surfaces; type of fluids pumped through channels for heating and cooling; temperatures, directions of flow and rates of flow of fluids; and placement of channels. 19 figures.
Apparatus for fabricating continuous lengths of superconductor
Kroeger, Donald M. (Knoxville, TN); List, III, Frederick A. (Andersonville, TN)
2002-01-01T23:59:59.000Z
A process and apparatus for manufacturing a superconductor. The process is accomplished by depositing a superconductor precursor powder on a continuous length of a first substrate ribbon, overlaying a continuous length of a second substrate ribbon on said first substrate ribbon, and applying sufficient pressure to form a bound layered superconductor comprising a layer of said superconducting precursor powder between said first substrate ribbon and said second substrates ribbon. The layered superconductor is then heat treated to establish the superconducting phase of said superconductor precursor powder.
Apparatus for fabricating continuous lengths of superconductor
Kroeger, Donald M. (Knoxville, TN); List, III, Frederick A. (Andersonville, TN)
2001-01-01T23:59:59.000Z
A process and apparatus for manufacturing a superconductor. The process is accomplished by depositing a superconductor precursor powder on a continuous length of a first substrate ribbon, overlaying a continuous length of a second substrate ribbon on said first substrate ribbon, and applying sufficient pressure to form a bound layered superconductor comprising a layer of said superconducting precursor powder between said first substrate ribbon and said second substrates ribbon. The layered superconductor is then heat treated to establish the superconducting phase of said superconductor precursor powder.
Forster, T.E.
EA Systems Examples Induction and Recursion Length Measuring the Universe Analysis Number systems of Mathematics University of Bristol April 21, 2008 Richard.Pettigrew@bris.ac.uk Natural number systems and infinitesimal analysis #12;EA Systems Examples Induction and Recursion Length Measuring the Universe Analysis
M. -Th. Huett; A. I. L'vov; A. I. Milstein; M. Schumacher
1999-05-13T23:59:59.000Z
The concept of Compton scattering by even-even nuclei from giant-resonance to nucleon-resonance energies and the status of experimental and theoretical researches in this field are outlined. Nuclear Compton scattering in the giant-resonance energy-region provides information on the dynamical properties of the in-medium mass of the nucleon. The electromagnetic polarizabilities of the nucleon in the nuclear medium can be extracted from nuclear Compton scattering data obtained in the quasi-deuteron energy-region. Recent results are presented for two-body effects due to the mesonic seagull amplitude and due to the excitation of nucleon internal degrees of freedom accompanied by meson exchanges. Due to these studies the in-medium electromagnetic polarizabilities are by now well understood, whereas the understanding of nuclear Compton scattering in the Delta-resonance range is only at the beginning. Phenomenological methods how to include retardation effects in the scattering amplitude are discussed and compared with model predictions.
Pauling bond strength, bond length and electron density distribution...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Pauling bond strength, bond length and electron density distribution. Pauling bond strength, bond length and electron density distribution. Abstract: A power law regression...
Quaglioni, S; Navratil, P; Roth, R
2009-12-15T23:59:59.000Z
The exact treatment of nuclei starting from the constituent nucleons and the fundamental interactions among them has been a long-standing goal in nuclear physics. Above all nuclear scattering and reactions, which require the solution of the many-body quantum-mechanical problem in the continuum, represent an extraordinary theoretical as well as computational challenge for ab initio approaches.We present a new ab initio many-body approach which derives from the combination of the ab initio no-core shell model with the resonating-group method [4]. By complementing a microscopic cluster technique with the use of realistic interactions, and a microscopic and consistent description of the nucleon clusters, this approach is capable of describing simultaneously both bound and scattering states in light nuclei. We will discuss applications to neutron and proton scattering on sand light p-shell nuclei using realistic nucleon-nucleon potentials, and outline the progress toward the treatment of more complex reactions.
New hydrocracking catalysts increase throughput, run length
Huizinga, T. [Shell Internationale Petroleum Mij., The Hague (Netherlands); Theunissen, J.M.H. [Rayong Refinery Co. Ltd., Rayong (Thailand); Minderhoud, H.; Veen, R. van [Koninklijke/Shell-Lab., Amsterdam (Netherlands)
1995-06-26T23:59:59.000Z
An improved, second-stage hydrocracking catalyst has been developed by combining stabilized Y zeolites with amorphous silica alumina cracking components. A commercial application of this catalyst, along with a new, first-stage zeolitic hydrocracking catalyst, resulted in increased unit throughput and cycle length. The paper discusses the hydrocracking process, first-stage catalysts, second-stage catalysts, hydrogenation process, commercial results, and product properties.
What Does a Scattering Pattern Tell US?
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Scattering Space sample light image Image Space lens Angular Space Q 4p sin(q) l Fourier Transform Scattering Pattern Fourier Transform Phase Problem Scattering Pattern...
Neutron Scattering Tutorials | Neutron Science | ORNL
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Neutron Scattering Tutorials SHARE Neutron Scattering Tutorials The following lectures were presented at the 2011 and 2010 National School on Neutron & X-Ray Scattering. This...
Length and Energy of Quadratic Bezier Curves and Applications
Hoffmann, Christoph M.
Length and Energy of Quadratic B´ezier Curves and Applications Young Joon Ahn a , Christoph for the arc length and the bending energy of quadratic B´ezier curves. The formulae are in terms control point is analyzed for curves of fixed arc length or bending energy. In the case of arc length
Scattering for dummies? Tommy Angelini
is elastic: |k|=|k'| #12;Kinematic Scattering Large R, scattered wave looks like plane wave. #12;2 ( ) ( )I A#q q Kinematic Scattering Many scatterers, add up waves at R. All waves have kR and $t... factor outV Electrons ~1's Ã? 100's keV Okay, not really... we'll treat them the same... neutrons too #12;Kinematic
General introduction to Compton scattering
D. Drechsel
1996-07-12T23:59:59.000Z
Real and virtual Compton scattering has been and will be an important tool to study the structure of hadronic systems. We summarize the status of real Compton scattering and give an outlook at the new theoretical and experimental developments in the field of virtual Compton scattering.
PHOTOIONIZATION SPECTRA OF CH3I PERTURBED BY SF6: ELECTRON SCATTERING IN SF6 GAS
Findley, Gary L.
1 PHOTOIONIZATION SPECTRA OF CH3I PERTURBED BY SF6: ELECTRON SCATTERING IN SF6 GAS C. M. Evansa of SF6 perturbers (up to the perturber density 9.75 x 1019 cm-3 ) disclosed a red shift of autoionizing of the CH3I nd! Rydbergs (n=9,10,11,12), the electron scattering length of SF6 was found to be A = -0.484 nm
Multiple Contributors
1981-01-01T23:59:59.000Z
. "Triskelian Fledgeling" — by Vel Jaeger "Kelvan Exile" — by Vel Jaeger 111. Romulan Astronomy — by Robert S. Sayes 113c Trek-M's Speak their Minds on ST:TMP 121. A Glance Backwards - reactions to TaL I (first issue of TREKisM at Length) 122. Trivia Quizes #3...\\un Speck run. "fynjrur^run. -Storu Ipu1- 'The^dds" UYena T^fc* Ink.nc l'*- bjj rafrick La\\fena ^aq Kidd LuckICKU ©/980' -14- 0N CONVENTIONAL OCCASIONS The following Is a conglomeration of reports, Interviews, and reminiscences from TREKisM members...
Multiple Contributors
1988-01-01T23:59:59.000Z
Trek IV! SHALOM PAX PEACE to us all in 1986 Table of Contents TITLE AUTHOR ARTIST PAGE I. DATA ENTRIES FROST ON THE TYPEWRITER V.L. Thorn LaVena Kay Kldd 2 "Trek Omen" V.L. Thorn 6 (originally appeared In TREKisM #26) JAMES T. KIRK vs THE COMPUTER... appeared in TREKisM at Length III) TALES FROM THE VULCAN HEARTH Karen C. Hunter 53 HOW THE VULCANS LOST THEIR WINGS 54 THE SKY GOD'S DAUGHTER 56 THE GIFT OF THE GODS LaVena Kay Kldd 57 "Sul Generis" V.L. Thorn 58 "Cat-Kin" Emily Ross 60 (originally appeared...
Property:Length (m) | Open Energy Information
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Probing Nanoscale Surface Enhanced Raman Scattering Fluctuation...
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Nanoscale Surface Enhanced Raman Scattering Fluctuation Dynamics using Correalted AFM and Confocal Ultramicroscopy. Probing Nanoscale Surface Enhanced Raman Scattering Fluctuation...
Nanoscale structure in AgSbTe2 determined by diffuse elastic neutron scattering
Specht, Eliot D [ORNL; Ma, Jie [ORNL; Delaire, Olivier A [ORNL; Budai, John D [ORNL; May, Andrew F [ORNL; Karapetrova, Evguenia A. [Argonne National Laboratory (ANL)
2015-01-01T23:59:59.000Z
Diffuse elastic neutron scattering measurements confirm that AgSbTe2 has a hierarchical structure, with defects on length scales from nanometers to microns. While scattering from mesoscale structure is consistent with previously-proposed structures in which Ag and Sb order on a NaCl lattice, more diffuse scattering from nanoscale structure suggests a structural rearrangement in which hexagonal layers form a combination of (ABC), (ABA), and (AAB) stacking sequences. The AgCrSe2 structure is the best-fitting model for the local atomic arrangements.
Stellar mixing length theory with entropy rain
Brandenburg, Axel
2015-01-01T23:59:59.000Z
Stellar mixing length theory is modified to include the effects of a nongradient term that originates from the motion of convective elements with entropy perturbations of either sign. It is argued that such a term, first studied by Deardorff in the meteorological context, represents the effects of thin intense downdrafts caused by the rapid cooling in the granulation layer at the top of the convection zone. They transport heat nonlocally, as originally anticipated by Spruit in the 1990s, who describes the convection in the strongly stratified simulations of Stein & Nordlund as entropy rain. Although our model has ill-determined free parameters, it demonstrates that solutions can be found that look similar to the original ones, except that the deeper layers are now Schwarzschild stable, so no giant cells are produced and the typical convective scale is that of granules even at larger depth. Consequences for modeling solar differential, the global dynamo, and sunspots are briefly discussed.
A New Polyethylene Scattering Law Determined Using Inelastic Neutron Scattering
Lavelle, Christopher M [ORNL; Liu, C [Oak Ridge National Laboratory (ORNL); Stone, Matthew B [ORNL
2013-01-01T23:59:59.000Z
Monte Carlo neutron transport codes such as MCNP rely on accurate data for nuclear physics cross-sections to produce accurate results. At low energy, this takes the form of scattering laws based on the dynamic structure factor, S (Q, E). High density polyethylene (HDPE) is frequently employed as a neutron moderator at both high and low temperatures, however the only cross-sections available are for T =300 K, and the evaluation has not been updated in quite some time. In this paper we describe inelastic neutron scattering measurements on HDPE at 5 and 300 K which are used to improve the scattering law for HDPE. We describe the experimental methods, review some of the past HDPE scattering laws, and compare computations using these models to the measured S (Q, E). The total cross-section is compared to available data, and the treatment of the carbon secondary scatterer as a free gas is assessed. We also discuss the use of the measurement itself as a scattering law via the 1 phonon approximation. We show that a scattering law computed using a more detailed model for the Generalized Density of States (GDOS) compares more favorably to this experiment, suggesting that inelastic neutron scattering can play an important role in both the development and validation of new scattering laws for Monte Carlo work.
Geometric Solutions for the Neutrino Oscillation Length Resonance
Jason Pruet; George M. Fuller
1999-04-02T23:59:59.000Z
We give a geometric interpretation of the neutrino 'oscillation length resonance' recently discovered by Petcov. We use this picture to identify two new solutions for oscillation length resonances in a 3-layer earth model.
Low-coherent WDM reflectometry for accurate fiber length monitoring
Hui, Rongqing; Thomas, J.; Allen, Christopher Thomas; Fu, B.; Gao, S.
2003-01-01T23:59:59.000Z
A fiber-optic low-coherent reflectometer was developed to accurately monitor fiber length variation. A large length-coverage range was obtained by using a fiber Bragg grating array in a wavelength-division-multiplexing ...
Scattering Techniques and Geometries
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AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What's PossibleRadiationImplementingnpitcheResearch Briefs TheSanket A.LittleFY13Scarboro girlsScattering
Dictionaries Using Variable-Length Keys and Data, with Applications *
Blelloch, Guy E.
(Isil- logn, 1) + Itil) and Isil is the length of bit string si. We assume a word length w > log m. We present string Isil > 1, Itil > 1 for all bit-strings si and ti. Fox' fixed-length keys the dictionary problem
Weak Deeply Virtual Compton Scattering
A. Psaker; W. Melnitchouk; A. V. Radyushkin
2006-12-21T23:59:59.000Z
We extend the analysis of the deeply virtual Compton scattering process to the weak interaction sector in the generalized Bjorken limit. The virtual Compton scattering amplitudes for the weak neutral and charged currents are calculated at the leading twist within the framework of the nonlocal light-cone expansion via coordinate space QCD string operators. Using a simple model, we estimate cross sections for neutrino scattering off the nucleon, relevant for future high intensity neutrino beam facilities.
Weak Deeply Virtual Compton Scattering
Ales Psaker; Wolodymyr Melnitchouk; Anatoly Radyushkin
2007-03-01T23:59:59.000Z
We extend the analysis of the deeply virtual Compton scattering process to the weak interaction sector in the generalized Bjorken limit. The virtual Compton scattering amplitudes for the weak neutral and charged currents are calculated at the leading twist within the framework of the nonlocal light-cone expansion via coordinate space QCD string operators. Using a simple model, we estimate cross sections for neutrino scattering off the nucleon, relevant for future high intensity neutrino beam facilities.
D. Choudhury; D. R. Phillips; A. Nogga
2006-11-09T23:59:59.000Z
We present first calculations for Compton scattering on $^3$He. The objective of the calculation is an extraction of the neutron polarizabilities.
Advances in total scattering analysis
Proffen, Thomas E [Los Alamos National Laboratory; Kim, Hyunjeong [Los Alamos National Laboratory
2008-01-01T23:59:59.000Z
In recent years the analysis of the total scattering pattern has become an invaluable tool to study disordered crystalline and nanocrystalline materials. Traditional crystallographic structure determination is based on Bragg intensities and yields the long range average atomic structure. By including diffuse scattering into the analysis, the local and medium range atomic structure can be unravelled. Here we give an overview of recent experimental advances, using X-rays as well as neutron scattering as well as current trends in modelling of total scattering data.
Compact noninvasive electron bunch-length monitor
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Roberts, B.; Mammei, R. R.; Poelker, M.; McCarter, J. L.
2012-12-01T23:59:59.000Z
A compact rf cavity was constructed that simultaneously resonates at many harmonic modes when excited by a repetitive bunched electron beam passing through its bore. The excitation of these modes provides a Fourier description of the temporal characteristics of the bunch train. The cavity was used to noninvasively characterize electron bunches produced from thin and thick GaAs photocathodes inside a DC high voltage photogun illuminated with 37 ps (full width half maximum, FWHM) laser pulses at repetition rates near 1500 MHz, at average beam current from 5 to 500????A , and at beam energy from 75 to 195 keV. The cavity bunch-length monitor could detect electron bunches as short as 57 ps (FWHM) when connected directly to a sampling oscilloscope, and could clearly distinguish bunches with varying degrees of space-charge induced growth and with different tail signatures. Efforts are under way to detect shorter bunches by designing cavities with increased bandwidth. This demonstration lends credibility to the idea that these cavities could also be used for other applications, including bunching and shaping, when driven with external rf.
Effective spin-flip scattering in diffusive superconducting proximity systems with magnetic disorder
Skvortsov, Mikhail
Effective spin-flip scattering in diffusive superconducting proximity systems with magnetic superconductors and normal metals or ferromagnets with magnetic disorder. On the length scales much larger than.45. c, 75.60.Ch, 74.78.Fk I. INTRODUCTION In conventional superconductors S , pairing occurs be- tween
Superlinear growth of Rayleigh scattering-induced intensity noise in single-mode fibers
Cahill, James P; Zhou, Weimin; Menyuk, Curtis R; Carter, Gary M
2015-01-01T23:59:59.000Z
Rayleigh scattering generates intensity noise close to an optical carrier that propagates in a single-mode optical fiber. This noise degrades the performance of optoelectronic oscillators and RF-photonic links. When using a broad linewidth laser, we previously found that the intensity noise power scales linearly with optical power and fiber length, which is consistent with guided entropy mode Rayleigh scattering (GEMRS), a third order nonlinear scattering process, in the spontaneous limit. In this work, we show that this behavior changes significantly with the use of a narrow linewidth laser. Using a narrow linewidth laser, we measured the bandwidth of the intensity noise plateau to be 10 kHz. We found that the scattered noise power scales superlinearly with fiber length up to lengths of 10 km in the frequency range of 500 Hz to 10 kHz, while it scales linearly in the frequency range of 10 Hz to 100 Hz. These results suggest that the Rayleigh-scattering-induced intensity noise cannot be explained by third-ord...
Renormalization plasma shielding effects on scattering entanglement fidelity in dense plasmas
Lee, Gyeong Won [Department of Bionanotechnology, Hanyang University, Ansan, Kyunggi-Do 426-791 (Korea, Republic of); Shim, Jaewon [Department of Applied Physics, Hanyang University, Ansan, Kyunggi-Do 426-791 (Korea, Republic of); Jung, Young-Dae, E-mail: ydjung@hanyang.ac.kr [Department of Bionanotechnology, Hanyang University, Ansan, Kyunggi-Do 426-791 (Korea, Republic of); Department of Applied Physics, Hanyang University, Ansan, Kyunggi-Do 426-791 (Korea, Republic of); Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180-3590 (United States)
2014-10-15T23:59:59.000Z
The influence of renormalization plasma screening on the entanglement fidelity for the elastic electron-atom scattering is investigated in partially ionized dense hydrogen plasmas. The partial wave analysis and effective interaction potential are employed to obtain the scattering entanglement fidelity in dense hydrogen plasmas as functions of the collision energy, the Debye length, and the renormalization parameter. It is found that the renormalization plasma shielding enhances the scattering entanglement fidelity. Hence, we show that the transmission of the quantum information can be increased about 10% due to the renormalization shielding effect in dense hydrogen plasmas. It is also found that the renormalization shielding effect on the entanglement fidelity for the electron-atom collision increases with an increase of the collision energy. In addition, the renormalization shielding function increases with increasing collision energy and saturates to the unity with an increase of the Debye length.
Hu, Naiping; Borkar, Neha; Kohls, Doug; Schaefer, Dale W. (UCIN)
2014-09-24T23:59:59.000Z
A combination of ultra small angle X-ray scattering (USAXS) and ultra small angle neutron scattering (USANS) is used to characterize porous materials. The analysis methods yield quantitative information, including the mean skeletal chord length, mean pore chord length, skeletal density, and composition. A mixed cellulose ester (MCE) membrane with a manufacturer-labeled pore size of 0.1 {mu}m was used as a model to elucidate the specifics of the method. Four approaches describing four specific scenarios (different known parameters and form of the scattering data) are compared. Pore chords determined using all four approaches are in good agreement with the scanning electron microscopy estimates but are larger than the manufacturer's nominal pore size. Our approach also gives the average chord of the skeletal solid (struts) of the membrane, which is also consistent for all four approaches. Combined data from USAXS and USANS gives the skeletal density and the strut composition.
Kegel, Gunter H.R.; Egan, James J
2007-04-18T23:59:59.000Z
This project covers four principal areas of research: Elastic and inelastic neutron scattering studies in odd-A terbium, thulium and other highly deformed nuclei near A=160 with special regard to interband transitions and to the investigation of the direct-interaction versus the compound-nucleus excitation process in these nuclei. Examination of new, fast photomultiplier tubes suitable for use in a miniaturized neutron-time-of-flight spectrometer. Measurement of certain inelastic cross sections of 238U. Determination of the multiplicity of prompt fission gamma rays in even-A fissile actinides. Energies and mean lives of fission isomers produced by fast fission of even-Z, even-A actinides. Study of the mean life of 7Be in different host matrices and its possible astro-physical significance.
INVERSE MEDIUM SCATTERING PROBLEMS FOR ...
SIAM (#1) 1035 2001 Apr 10 12:32:38
2005-08-08T23:59:59.000Z
Consider a time-harmonic electromagnetic plane wave incident on a ..... the step size of time marching, whose length is restricted by the stability of the explicit.
Infrared limit in external field scattering
Andrzej Herdegen
2012-05-17T23:59:59.000Z
Scattering of electrons/positrons by external classical electromagnetic wave packet is considered in infrared limit. In this limit the scattering operator exists and produces physical effects, although the scattering cross-section is trivial.
What Does a Scattering Pattern Tell US?
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Reciprocal Space Apurva Mehta 7 th X-ray Scattering School Scattering Physics Sample Space Scattering Space sample light image Image Space lens Can we create the image without a...
LIGHT SCATTERING STUDIES OF SILICA AEROGELS
Hunt, A.J.
2010-01-01T23:59:59.000Z
van de Hulst, H.C. , Light Scattering by Small Particles,A New Polarization-Modulated Light Scattering Instrument,"and interpretation of light scattering effects in aerogels.
Requirements, possible alternatives & international NEUTRON SCATTERING
Dimeo, Robert M.
Requirements, possible alternatives & international NEUTRON SCATTERING DETECTORS for Rob Dimeo NIST neutron scattering instruments are the most demanding require background low #12;#12;The Helium-3 Supply Crisis Alternative Techniques to Helium-3 based Detectors for Neutron Scattering Applications
Collective stimulated Brillouin scatter
Alexander O. Korotkevich; Pavel M. Lushnikov; Harvey A. Rose
2011-05-11T23:59:59.000Z
We develop a statistical theory of stimulated Brillouin backscatter (BSBS) of a spatially and temporally partially incoherent laser beam for laser fusion relevant plasma. We find a new collective regime of BSBS which has a much larger threshold than the classical threshold of a coherent beam in long-scale-length laser fusion plasma. We identify two contributions to BSBS convective instability increment. The first is collective with intensity threshold independent of the laser correlation time and controlled by diffraction. The second is independent of diffraction, it grows with increase of the correlation time and does not have an intensity threshold. The instability threshold is inside the typical parameter region of National Ignition Facility (NIF). We also find that the bandwidth of KrF-laser-based fusion systems would be large enough to allow additional suppression of BSBS.
Small angle neutron scattering from high impact polystyrene
Pringle, O.A.
1981-01-01T23:59:59.000Z
High impact polystyrene (HIPS) is a toughened plastic composed of a polystyrene matrix containing a few percent rubber in the form of dispersed 0.1 to 10 micron diameter rubber particles. Some commercial formulations of HIPS include the addition of a few percent mineral oil, which improves the toughness of the plastic. Little is known about the mechanism by which the mineral oil helps toughen the plastic. It is hypothesized that the oil is distributed only in the rubber particles, but whether this hypothesis is correct was not known prior to this work. The size of the rubber particles in HIPS and their neutron scattering length density contrast with the polystyrene matrix cause HIPS samples to scatter neutrons at small angles. The variation of this small angle neutron scattering (SANS) signal with mineral oil content has been used to determine the location of the oil in HIPS. The SANS spectrometer at the University of Missouri Research Reactor Facility (MURR) was used to study plastic samples similar in composition to commercial HIPS. The MURR SANS spectrometer is used to study the small angle scattering of a vertical beam of 4.75 A neutrons from solid and liquid samples. The scattered neutrons are detected in a 54 x 60 cm/sup 2/ position sensitive detector designed and built at MURR. A series of plastic samples of varying rubber and oil content and different rubber domain sizes and shapes were examined on the MURR SANS spectrometer. Analysis of the scattering patterns showed that the mineral oil is about eight to ten times more likely to be found in the rubber particles than in the polystyrene matrix. This result confirmed the hypothesis that the mineral oil is distributed primarily in the rubber particles.
A. Gashi; E. Matsinos; G. C. Oades; G. Rasche; W. S. Woolcock
2007-10-18T23:59:59.000Z
Using newly calculated electromagnetic corrections, we have made a phase shift analysis of experimental data on pi+/- p elastic scattering up to 100 MeV, assuming the effective hadronic interaction to be isospin invariant. The output consists of parametrised s and p-wave hadronic phases for isospin 1/2 and 3/2. It is not possible to fit the charge exchange data satisfactorily. We give values for the s-wave scattering lengths and effective ranges and for the p-wave scattering volumes. The combinations 2a_1 + a_3 and a_1 - a_3 of s-wave scattering lengths extracted from pionic hydrogen data are compared with those obtained from our analysis.
Benchmark calculations for elastic fermion-dimer scattering
Shahin Bour; H. -W. Hammer; Dean Lee; Ulf-G. Meißner
2012-06-08T23:59:59.000Z
We present continuum and lattice calculations for elastic scattering between a fermion and a bound dimer in the shallow binding limit. For the continuum calculation we use the Skorniakov-Ter-Martirosian (STM) integral equation to determine the scattering length and effective range parameter to high precision. For the lattice calculation we use the finite-volume method of L\\"uscher. We take into account topological finite-volume corrections to the dimer binding energy which depend on the momentum of the dimer. After subtracting these effects, we find from the lattice calculation kappa a_fd = 1.174(9) and kappa r_fd = -0.029(13). These results agree well with the continuum values kappa a_fd = 1.17907(1) and kappa r_fd = -0.0383(3) obtained from the STM equation. We discuss applications to cold atomic Fermi gases, deuteron-neutron scattering in the spin-quartet channel, and lattice calculations of scattering for nuclei and hadronic molecules at finite volume.
Development of a nine spatial point, multipulse Thomson scattering diagnostic
Glass, F.; Deng, B. H.; Garate, E.; Gornostaeva, O.; Schroeder, J. [Tri Alpha Energy, Inc., Rancho Santa Margarita, California 92688 (United States)
2010-10-15T23:59:59.000Z
A Thomson scattering diagnostic has been developed for the C-2 field-reversed configuration device. Based on a multipulse ruby laser, the system measures the electron temperature at nine spatial points. These points are chosen from 22 selectable positions covering r{approx_equal}1-41 cm. Twin collection lenses couple the scattered photons to nine optical fiber pairs. Extra fiber lengths delay the signals from different spatial points relative to each other, allowing up to three points to be analyzed by a single polychromator. The polychromator, using compact photomultipliers as detectors, has six spectral channels covering the range of 685-725 nm and is able to estimate electron temperatures of {approx_equal}10-200 eV. The photomultiplier output signals are recorded by digital storage oscilloscopes integrated with the main MDSplus database, with temperature and error estimates generated automatically at the conclusion of each plasma discharge.
Comparison of collimation systems for small-angle neutron scattering
Seeger, P.A.
1985-01-01T23:59:59.000Z
It is shown by simple first-order geometric arguments that for a given resolution, the flux on sample in a small-angle scattering instrument is independent of the form of the collimator or of the length of the instrument. Count rate may be increased by increasing the sample size, through the use of multi-aperture systems. In second order, it is shown to be advantageous to place the beam defining elements as close as possible to the source and the sample. The multiple-pinhole system gives maximum flux on small samples but has non-uniform illumination so that intensity increases only about half as fast as sample area. Soller slits and continuous tubes from source to sample were also considered, but neutron scattering and reflection from surfaces generate a large halo. Monte-Carlo simulations confirm these results, with the conclusion that the optimum collimator configuration is the multiple-pinhole system. 4 refs., 4 figs.
Elastic meson production and Compton scattering
M. Diehl
2001-09-13T23:59:59.000Z
I discuss recent progress in the theory of exclusive meson production and Compton scattering, focusing on hard-scattering factorization and on the dipole formalism.
Real Compton Scattering from the Proton
Alan M. Nathan
1999-08-31T23:59:59.000Z
Real Compton Scattering on the proton in the hard scattering regime is investigated. Recent theoretical developments are reviewed. Plans for new experimental studies at Jefferson Laboratory are presented.
What Does a Scattering Pattern Tell US?
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* Good when there is need to remove inelastic scattering signal: e.g., fluorescence, compton scattering - Energy Insensitive detectors: E resol > 1000 eV * photomultiplier,...
Search for: "neutron scattering" | DOE PAGES
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neutron scattering" Find + Advanced Search Advanced Search All Fields: "neutron scattering" Title: Full Text: Bibliographic Data: Creator Author: Name Name ORCID Search...
11th LANSCE School on Neutron Scattering
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11th LANSCE School on Neutron Scattering LANSCE 11th LANSCE School on Neutron Scattering Home Abstract Lecturers Lecturer Abstracts Hands-On Experiments Free Day About the...
Structuring Materials on Multiple Length Scales for Energy Application...
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Structuring Materials on Multiple Length Scales for Energy Applications October 25, 2012 at 3pm36-428 Adreas Stein Department of Chemistry, University of Minnesota astein...
Ultra-low-loss tapered optical fibers with minimal lengths
Ryutaro Nagai; Takao Aoki
2014-11-09T23:59:59.000Z
We design and fabricate ultra-low-loss tapered optical fibers (TOFs) with minimal lengths. We first optimize variations of the torch scan length using the flame-brush method for fabricating TOFs with taper angles that satisfy the adiabaticity criteria. We accordingly fabricate TOFs with optimal shapes and compare their transmission to TOFs with a constant taper angle and TOFs with an exponential shape. The highest transmission measured for TOFs with an optimal shape is in excess of 99.7 % with a total TOF length of only 23 mm, whereas TOFs with a constant taper angle of 2 mrad reach 99.6 % transmission for a 63 mm TOF length.
Crandall, David Lynn
2011-08-16T23:59:59.000Z
Sighting optics include a front sight and a rear sight positioned in a spaced-apart relation. The rear sight includes an optical element having a first focal length and a second focal length. The first focal length is selected so that it is about equal to a distance separating the optical element and the front sight and the second focal length is selected so that it is about equal to a target distance. The optical element thus brings into simultaneous focus for a user images of the front sight and the target.
Scattering theory with path integrals
Rosenfelder, R. [Particle Theory Group, Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland)] [Particle Theory Group, Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland)
2014-03-15T23:59:59.000Z
Starting from well-known expressions for the T-matrix and its derivative in standard nonrelativistic potential scattering, I rederive recent path-integral formulations due to Efimov and Barbashov et al. Some new relations follow immediately.
Neutron scattering and models: Titanium
Smith, A.B.
1997-07-01T23:59:59.000Z
Differential neutron elastic-scattering cross sections of elemental titanium were measured from 4.5 {r_arrow} 10.0 MeV in incident energy increments of {approx} 0.5 MeV. At each energy the measurements were made at forty or more scattering angles distributed between {approx} 17 and 160{degree}. Concurrently, differential neutron inelastic-scattering cross sections were measured for observed excitations of 0.975 {+-} 0.034, 1.497 {+-} 0.033, 2.322 {+-} 0.058, 3.252 {+-} 0.043, 3.700 {+-} 0.093, 4.317 {+-} 0.075 and 4.795 {+-} 0.100 MeV. All of the observed inelastically-scattered neutron groups were composites of contributions from several isotopes and/or levels. The experimental results were used to develop energy-average optical, statistical and coupled-channels models.
Aspects of Nucleon Compton Scattering
V. Bernard; N. Kaiser; Ulf-G. Meißner; A. Schmidt
1993-11-24T23:59:59.000Z
We consider the spin-averaged nucleon forward Compton scattering amplitude in heavy baryon chiral perturbation theory including all terms to order ${\\cal O} (q^4)$. The chiral prediction for the spin-averaged forward Compton scattering amplitude is in good agreement with the data for photon energies $\\omega \\le 110$ MeV. We also evaluate the nucleon electric and magnetic Compton polarizabilities to this order and discuss the uncertainties of the various counter terms entering the chiral expansion of these quantities.
A Study of Query Length Avi Arampatzis1
Arampatzis, Avi
length, and fit power-law and Poisson distribu- tions to four different query sets. We provide and a power-law distribution for longer queries, that better fits real query length distributions than earlier proposals. Categories and Subject Descriptors: H.3 [Information Storage and Re- trieval]: H.3.3 Information
On Termination and Derivation Lengths for Ground Rewrite Systems
Giesl, Juergen
On Termination and Derivation Lengths for Ground Rewrite Systems Dieter Hofbauer 1 UniversitÂ¨at GH@theory.informatik.uniÂkassel.de Abstract. It is shown that for terminating ground term rewrite systems the length of derivations a suitable interpretation into the natural numbers. Terminating ground systems are not necessarily
Scaling Behavior and Equilibrium Lengths of Knotted Polymers
Bigelow, Stephen
Scaling Behavior and Equilibrium Lengths of Knotted Polymers Eric Rawdon Akos Dobay John C. Kern numerical simulations to investigate how the chain length and topology of freely fluctuating knotted polymer of a characteristic changes with the chain size and how this change depends on the topology of the modeled polymers
Light and Color in Nature -Scattering Effects -
Assarsson, Ulf
1 Seminar WS 2003/04 Light and Color in Nature - Scattering Effects - Marcus Magnor WS03/04: Light and Color in Nature Scattering Overview · Last Lecture Interference · Today Light scattering: water rendering #12;2 WS03/04: Light and Color in Nature Scattering List of Topics · Rainbow Stephan
RisR1125(EN) Neutron Scattering
RisøR1125(EN) Neutron Scattering Studies of Modulated Magnetic Structures Steen Aagaard Sørensen investigations of the magnetic systems DyFe4Al8 and MnSi by neutron scattering and in the former case also by X and the correlations between the scattering entities of the sample. The theoretical framework of neutron scattering
Shy,Jow-Tsong
a convenient and objective length standard for use in both academic and industrial applications. Ever since the ve- locity of light in a vacuum was defined as 299 792 458 m/s in 1983,1 atom or molecule of the primary length-standard lasers,16 and some inter- comparisons were held thereafter.11,14 Therefore
J. M. Harris; G. R. S. Iyer; D. O. Simien; J. A. Fagan; J. Y. Huh; J. Y. Chung; S. D. Hudson; J. Obrzut; J. F. Douglas; C. M. Stafford; E. K. Hobbie
2011-01-01T23:59:59.000Z
Single-wall carbon nanotube (SWCNT) films show significant promise for transparent electronics applications that demand mechanical flexibility, but durability remains an outstanding issue. In this work, thin membranes of length purified single-wall carbon nanotubes (SWCNTs) are uniaxially and isotropically compressed by depositing them on prestrained polymer substrates. Upon release of the strain, the topography, microstructure, and conductivity of the films are characterized using a combination of optical/fluorescence microscopy, light scattering, force microscopy, electron microscopy, and impedance spectroscopy. Above a critical surface mass density, films assembled from nanotubes of well-defined length exhibit a strongly nonlinear mechanical response. The measured strain dependence reveals a dramatic softening that occurs through an alignment of the SWCNTs normal to the direction of prestrain, which at small strains is also apparent as an anisotropic increase in sheet resistance along the same direction. At higher strains, the membrane conductivities increase due to a compression-induced restoration of conductive pathways. Our measurements reveal the fundamental mode of elasto-plastic deformation in these films and suggest how it might be suppressed.
Small angle X-ray scattering study of coal soot formation
Winans, R. E.; Parker, J. T.; Seifert, S.; Fletcher, T. H.
2000-02-14T23:59:59.000Z
The objective of this study is to examine, by small angle X-ray scattering (SAXS), the formation of soot from individual coal particle combustion in a methane flat flame burner. The SAXS instrument at the Basic Energy Sciences Synchrotron Radiation Center (BESSRC) at the Advanced Photon Source (APS) can be used to observe both the formation of spherules and clusters since it can access length scales of 6--6000 {angstrom}. The high X-ray flux enables rapid acquisition of scattering data of various regions of the flame. SAXS data reveal particle size, shape, surface areas, and surface roughness.
Finite volume effects in low-energy neutron-deuteron scattering
Alexander Rokash; Evgeny Epelbaum; Hermann Krebs; Dean Lee; Ulf-G. Meißner
2013-08-15T23:59:59.000Z
We present a lattice calculation of neutron-deuteron scattering at very low energies and investigate in detail the impact of the topological finite-volume corrections. Our calculations are carried out in the framework of pionless effective field theory at leading order in the low-energy expansion. Using lattice sizes and a lattice spacing comparable to those employed in nuclear lattice simulations, we find that the topological volume corrections must be taken into account in order to obtain correct results for the neutron-proton S-wave scattering lengths.
Hydrogen atom in momentum space with a minimal length
Djamil Bouaziz; Nourredine Ferkous
2010-09-05T23:59:59.000Z
A momentum representation treatment of the hydrogen atom problem with a generalized uncertainty relation,which leads to a minimal length ({\\Delta}X_{i})_{min}= \\hbar \\sqrt(3{\\beta}+{\\beta}'), is presented. We show that the distance squared operator can be factorized in the case {\\beta}'=2{\\beta}. We analytically solve the s-wave bound-state equation. The leading correction to the energy spectrum caused by the minimal length depends on \\sqrt{\\beta}. An upper bound for the minimal length is found to be about 10^{-9} fm.
Inflationary universe in the presence of a minimal measurable length
A. Mohammadi; Ahmed Farag Ali; T. Golanbari; A. Aghamohammadi; Kh. Saaidi; Mir Faizal
2015-05-17T23:59:59.000Z
In this paper, we will study the effect of having a minimum measurable length on inflationary cosmology. We will analyse the inflationary cosmology in the Jacobson approach. In this approach, gravity is viewed as an emergent thermodynamical phenomena. We will demonstrate that the existence of a minimum measurable length will modify the Friedmann equations in the Jacobson approach. We will use this modified Friedmann equation to analyse the effect of minimum measurable length scale on inflationary cosmology. This analysis will be performed using the Hamiltonian-Jacobi approach. We compare our results to recent data, and find that our model may agree with the recent data.
Inflationary universe in the presence of a minimal measurable length
Mohammadi, A; Golanbari, T; Aghamohammadi, A; Saaidi, Kh; Faizal, Mir
2015-01-01T23:59:59.000Z
In this paper, we will study the effect of having a minimum measurable length on inflationary cosmology. We will analyse the inflationary cosmology in the Jacobson approach. In this approach, gravity is viewed as an emergent thermodynamical phenomena. We will demonstrate that the existence of a minimum measurable length will modify the Friedmann equations in the Jacobson approach. We will use this modified Friedmann equation to analyse the effect of minimum measurable length scale on inflationary cosmology. This analysis will be performed using the Hamiltonian-Jacobi approach. We compare our results to recent data, and find that our model may agree with the recent data.
Mechanical property scatter in CFCCs
Steen, M.; Filiou, C.
2000-01-01T23:59:59.000Z
The tensile response of continuous fiber reinforced ceramic matrix composites (CFCCs) is not expected to show the large variation in strength properties commonly observed for monolithic ceramics. Results of recent investigations on a number of two-dimensional reinforced CFCCs have nevertheless revealed a considerable scatter in the initial elastic modulus, in the first matrix cracking stress and in the failure stress. One school of thought considers that the observed variability is caused by experimental factors. Elaborate testing programs have been set up to clarify the origins of this scatter by investigation of the effects of control mode, loading rate, specimen shape, etc. Another school explains the scatter by the presence of (axial) residual stresses in the fibers and in the matrix. Although plausible, this hypothesis is difficult to verify because experimental determination of the residual stress state in CFCCs is not straightforward. In addition, with the available methods it is impractical to determine the residual stresses in every test specimen. This approach is indeed required for establishing the relationship between the magnitude of the residual stresses and the experimentally observed scatter. At IAM a method has been developed and validated which allows to quantify the axial residual stress state in individual CFCC specimens by subjecting them to intermittent unloading-reloading cycles. The method as well as the derived relationship between residual stress state and scatter in mechanical response will be presented.
Scattering apodizer for laser beams
Summers, M.A.; Hagen, W.F.; Boyd, R.D.
1984-01-01T23:59:59.000Z
A method is disclosed for apodizing a laser beam to smooth out the production of diffraction peaks due to optical discontinuities in the path of the laser beam, such method comprising introduction of a pattern of scattering elements for reducing the peak intensity in the region of such optical discontinuities, such pattern having smoothly tapering boundaries in which the distribution density of the scattering elements is tapered gradually to produce small gradients in the distribution density, such pattern of scattering elements being effective to reduce and smooth out the diffraction effects which would otherwise be produced. The apodizer pattern may be produced by selectively blasting a surface of a transparent member with fine abrasive particles to produce a multitude of minute pits. In one embodiment, a scattering apodizer pattern is employed to overcome diffraction patterns in a multiple element crystal array for harmonic conversion of a laser beam. The interstices and the supporting grid between the crystal elements are obscured by the gradually tapered apodizer pattern of scattering elements.
Scattering apodizer for laser beams
Summers, Mark A. (Livermore, CA); Hagen, Wilhelm F. (Livermore, CA); Boyd, Robert D. (Livermore, CA)
1985-01-01T23:59:59.000Z
A method is disclosed for apodizing a laser beam to smooth out the production of diffraction peaks due to optical discontinuities in the path of the laser beam, such method comprising introduction of a pattern of scattering elements for reducing the peak intensity in the region of such optical discontinuities, such pattern having smoothly tapering boundaries in which the distribution density of the scattering elements is tapered gradually to produce small gradients in the distribution density, such pattern of scattering elements being effective to reduce and smooth out the diffraction effects which would otherwise be produced. The apodizer pattern may be produced by selectively blasting a surface of a transparent member with fine abrasive particles to produce a multitude of minute pits. In one embodiment, a scattering apodizer pattern is employed to overcome diffraction patterns in a multiple element crystal array for harmonic conversion of a laser beam. The interstices and the supporting grid between the crystal elements are obscured by the gradually tapered apodizer pattern of scattering elements.
A coarse entropy-rigidity theorem and discrete length-volume inequalities
Kinneberg, Kyle Edward
2014-01-01T23:59:59.000Z
A discrete length-volume inequality . . . . . . . .v 3 Length-volume inequalities revisitedlength-volume inequality for cubes . . . . . . . . . . . .
Asymptotic Completeness for Compton Scattering
J. Froehlich; M. Griesemer; B. Schlein
2003-07-26T23:59:59.000Z
Scattering in a model of a massive quantum-mechanical particle, an ``electron'', interacting with massless, relativistic bosons, ``photons'', is studied. The interaction term in the Hamiltonian of our model describes emission and absorption of ``photons'' by the ``electron''; but ``electron-positron'' pair production is suppressed. An ultraviolet cutoff and an (arbitrarily small, but fixed) infrared cutoff are imposed on the interaction term. In a range of energies where the propagation speed of the dressed ``electron'' is strictly smaller than the speed of light, unitarity of the scattering matrix is proven, provided the coupling constant is small enough; (asymptotic completeness of Compton scattering). The proof combines a construction of dressed one--electron states with propagation estimates for the ``electron'' and the ``photons''.
Compton Scattering and Generalized Polarizabilities
Stefan Scherer
2004-10-14T23:59:59.000Z
In recent years, real and virtual Compton scattering off the nucleon have attracted considerable interest from both the experimental and theoretical sides. Real Compton scattering gives access to the so-called electromagnetic polarizabilities containing the structure information beyond the global properties of the nucleon such as its charge, mass, and magnetic moment. These polarizabilities have an intuitive interpretation in terms of induced dipole moments and thus characterize the response of the constituents of the nucleon to a soft external stimulus. The virtual Compton scattering reaction $e^-p\\to e^-p\\gamma$ allows one to map out the {\\em local} response to external fields and can be described in terms of generalized electromagnetic polarizabilities. A simple classical interpretation in terms of the induced electric and magnetic polarization densities is proposed. We will discuss experimental results for the polarizabilities of the proton and compare them with theoretical predictions.
Compton Scattering on Light Nuclei
Deepshikha Shukla
2009-12-22T23:59:59.000Z
Compton scattering on light nuclei ($A=2,3$) has emerged as an effective avenue to search for signatures of neutron polarizabilities, both spin--independent and spin--dependent ones. In this discussion I will focus on the theoretical aspect of Compton scattering on light nuclei; giving first a brief overview and therafter concentrating on our Compton scattering calculations based on Chiral effective theory at energies of the order of pion mass. These elastic $\\gamma$d and $\\gamma$He-3 calculations include nucleons, pions as the basic degrees of freedom. I will also discuss $\\gamma$d results where the $\\Delta$-isobar has been included explicitly. Our results on unpolarized and polarization observables suggest that a combination of experiments and further theoretical efforts will provide an extraction of the neutron polarizabilities.
FEL GAIN LENGTH AND TAPER MEASUREMENTS AT LCLS
Ratner, D.
2010-01-01T23:59:59.000Z
taper mea- surements from LCLS. We ?nd gain lengths of ? 2.9AND TAPER MEASUREMENTS AT LCLS ? D. Ratner † , A. Brachmann,et al. , First Results of the LCLS Laser-Heater Sys- tem,
amyloid fibril length: Topics by E-print Network
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22 23 24 25 Next Page Last Page Topic Index 1 Intrinsic Linear Heterogeneity of Amyloid Beta Protein Fibrils Revealed by Higher Resolution Mass-per-length Determinations* Chemistry...
Applying Vocal Tract Length Normalization to Meeting Recordings
Garau, Giulia; Renals, Steve; Hain, Thomas
2005-01-01T23:59:59.000Z
Vocal Tract Length Normalisation (VTLN) is a commonly used technique to normalise for inter-speaker variability. It is based on the speaker-specific warping of the frequency axis, parameterised by a scalar warp factor. ...
Inferring the Rate-Length Law of Protein Folding
Lane, Thomas J
2013-01-01T23:59:59.000Z
We investigate the rate-length scaling law of protein folding, a key undetermined scaling law in the analytical theory of protein folding. We demonstrate that chain length is a dominant factor determining folding times, and that the unambiguous determination of the way chain length corre- lates with folding times could provide key mechanistic insight into the folding process. Four specific proposed laws (power law, exponential, and two stretched exponentials) are tested against one an- other, and it is found that the power law best explains the data. At the same time, the fit power law results in rates that are very fast, nearly unreasonably so in a biological context. We show that any of the proposed forms are viable, conclude that more data is necessary to unequivocally infer the rate-length law, and that such data could be obtained through a small number of protein folding experiments on large protein domains.
FEL GAIN LENGTH AND TAPER MEASUREMENTS AT LCLS
Ratner, D.
2010-01-01T23:59:59.000Z
more than double the coherent, FEL power over the satura-FEL GAIN LENGTH AND TAPER MEASUREMENTS AT LCLS ? D.Figure 11: Post-saturation FEL pulse energy for a taper with
Hydrogen-atom spectrum under a minimal-length hypothesis
Sandor Benczik; Lay Nam Chang; Djordje Minic; Tatsu Takeuchi
2005-07-08T23:59:59.000Z
The energy spectrum of the Coulomb potential with minimal length commutation relations $[X_i, P_j] = i\\hbar\\{\\delta_{ij}(1+\\beta P^2) + \\beta'P_iP_j\\}$ is determined both numerically and perturbatively for arbitrary values of $\\beta'/\\beta$ and angular momenta $\\ell$. The constraint on the minimal length scale from precision hydrogen spectroscopy data is of order of a few GeV$\
Pion Compton scattering and bremsstrahlung
Göran Fäldt; Ulla Tengblad
2008-02-08T23:59:59.000Z
The pion-polarizability functions are structure functions of pion-Compton scattering. They can be assessed in high-energy pion-nucleus bremsstrahlung reactions, $\\pi^- +A\\to\\pi^- +\\gamma +A$. We present numerical expectations for pion-nucleus bremsstrahlung cross sections in the Coulomb region, i.e. the small-angle region where the nuclear scattering is dominated by the Coulomb interaction. We investigate the prospects of measuring the polarizability functions for pion-Compton c.m. energies from threshold up to 1 GeV. A meson-exchange model is used for the pion-Compton amplitude.
An investigation of angular and multiple scattering at 3.2-cm and 10.3-cm wave lengths
Webb, Randall Carroll
1966-01-01T23:59:59.000Z
(150) ~ SAV5(150)t ISAV6(150) ~ SAV'7(150) ~ SAVB(150)tSAV9(150)tSAV10(150) ~ SAV11(150) ~ 2SAV12(150& ~ SAV13(150)tSAV14&150&iSAV15(150)tSAV16(150) ~ SAV17(150)t 3XPLOT ( 150 ) COMMON FAC ~ GAMltGAM2tTAUtPIEtSUh(3(SUM4(SQCO&PE IhltRtSUMlt[PRINT DIMENSION...
Washington at Seattle, University of - Department of Physics, Electroweak Interaction Research Group
neutrinoless double beta decay and measure solar neutrinos and geoneutrinos. The type of particle by ap- proximately 9500 PMTs. For detections of neutrinoless double beta decay, the liquid scintillator double beta decay, low energy solar neutrinos, geo- neutrinos and supernova neutrinos using scintillation
Antenna mechanism of length control of actin cables
Lishibanya Mohapatra; Bruce L. Goode; Jane Kondev
2015-05-02T23:59:59.000Z
Actin cables are linear cytoskeletal structures that serve as tracks for myosin-based intracellular transport of vesicles and organelles in both yeast and mammalian cells. In a yeast cell undergoing budding, cables are in constant dynamic turnover yet some cables grow from the bud neck toward the back of the mother cell until their length roughly equals the diameter of the mother cell. This raises the question: how is the length of these cables controlled? Here we describe a novel molecular mechanism for cable length control inspired by recent experimental observations in cells. This antenna mechanism involves three key proteins: formins, which polymerize actin, Smy1 proteins, which bind formins and inhibit actin polymerization, and myosin motors, which deliver Smy1 to formins, leading to a length-dependent actin polymerization rate. We compute the probability distribution of cable lengths as a function of several experimentally tuneable parameters such as the formin-binding affinity of Smy1 and the concentration of myosin motors delivering Smy1. These results provide testable predictions of the antenna mechanism of actin-cable length control.
ANL/APS/TB-20 Bremsstrahlung Scattering Calculations for the...
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at rest and in flight, Moliere multiple scattering, Moller and Bhabha scattering, Compton scattering, pair production, photoelectric effect and the continuous energy loss...
Neutron Scattering: Condensed Matter and Magnetic Science, MPA...
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Neutron Scattering Neutron Scattering Capability description: Neutron scattering is a powerful probe of structure and collective modes of condensed matter. We are focused on direct...
Intrabeam scattering in the HEB
Larson, D.J.
1994-03-01T23:59:59.000Z
A study of Intrabeam Scattering (IBS) in the High Energy Booster (HEB) is presented. Piwinski`s formulas for IBS are presented and evaluated for the HEB. A computer code written to evaluate Piwinski`s formulas is discussed. The result of the study is that IBS should not be a problem for the HEB, although the safety factor is not enormous.
Electromagnetic Scattering by Nonspherical Particles
by the classical Lorenz-Mie theory and must be determined using ad- vanced theoretical and experimental techniques patterns and stress the need for a statistical approach in model- ing scattering and absorption as if the particles were perfect spheres. However, it is becoming increasingly obvious that this approach can cause
Scattering resonances as viscosity limits
Maciej Zworski
2015-05-04T23:59:59.000Z
Using the method of complex scaling we show that scattering resonances of $ - \\Delta + V $, $ V \\in L^\\infty_{\\rm{c}} ( \\mathbb R^n ) $, are limits of eigenvalues of $ - \\Delta + V - i \\epsilon x^2 $ as $ \\epsilon \\to 0+ $. That justifies a method proposed in computational chemistry and reflects a general principle for resonances in other settings.
6, 81258154, 2006 Multiple scattering
Boyer, Edmond
ACPD 6, 81258154, 2006 Multiple scattering effects for Cloudsat A. Battaglia et al. Title Page A. Battaglia1 , M. O. Ajewole2 , and C. Simmer3 1 Meteorological Institute, University of Bonn, Bonn: 28 August 2006 Correspondence to: A. Battaglia (batta@uni-bonn.de) 8125 #12;ACPD 6, 81258154, 2006
Scattering of very light charged particles
J C Taylor
1993-06-07T23:59:59.000Z
I advance arguments against the view that the Lee-Nauenberg-Kinoshita theorem is relevant in practice to the scattering of charged particles as their mass tends to zero. I also discuss the case of massive coloured particle scattering.
Coherent scattering from a free gas
Sanders, Scott N.
We investigate decoherence in atom interferometry due to scattering from a background gas and show that the supposition that residual coherence is due to near-forward scattering is incorrect. In fact, the coherent part is ...
GPDs, form factors and Compton scattering
P. Kroll
2002-07-09T23:59:59.000Z
The basic theoretical ideas of the handbag factorization and its application to wide-angle scattering reactions are reviewed. With regard to the present experimental program carried out at JLab, wide-angle Compton scattering is discussed in some detail.
Electromagnetic Scattering by Spheres of Topological Insulators
Ge, Lixin; Zi, Jian
2015-01-01T23:59:59.000Z
The electromagnetic scattering properties of topological insulator (TI) spheres are systematically studied in this paper. Unconventional backward scattering caused by the topological magneto-electric (TME) effect of TIs are found in both Rayleigh and Mie scattering regimes. This enhanced backward scattering can be achieved by introducing an impedance-matched background which can suppress the bulk scattering. For the cross-polarized scattering coefficients, interesting antiresonances are found in the Mie scattering regime, wherein the cross-polarized electromagnetic fields induced by the TME effect are trapped inside TI spheres. In the Rayleigh limit, the quantized TME effect of TIs can be determined by measuring the electric-field components of scattered waves in the far field.
10th LANSCE School on Neutron Scattering
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10th LANSCE School on Neutron Scattering LANSCE 10th LANSCE School on Neutron Scattering Home Abstract Lecturers Hands-On Experiments Free Day About the School Sponsors FAQ's...
Feedback Mechanism for Microtubule Length Regulation by Stathmin Gradients
Maria Zeitz; Jan Kierfeld
2014-12-09T23:59:59.000Z
We formulate and analyze a theoretical model for the regulation of microtubule (MT) polymerization dynamics by the signaling proteins Rac1 and stathmin. In cells, the MT growth rate is inhibited by cytosolic stathmin, which, in turn, is inactivated by Rac1. Growing MTs activate Rac1 at the cell edge, which closes a positive feedback loop. We investigate both tubulin sequestering and catastrophe promotion as mechanisms for MT growth inhibition by stathmin. For a homogeneous stathmin concentration in the absence of Rac1, we find a switch-like regulation of the MT mean length by stathmin. For constitutively active Rac1 at the cell edge, stathmin is deactivated locally, which establishes a spatial gradient of active stathmin. In this gradient, we find a stationary bimodal MT length distributions for both mechanisms of MT growth inhibition by stathmin. One subpopulation of the bimodal length distribution can be identified with fast growing and long pioneering MTs in the region near the cell edge, which have been observed experimentally. The feedback loop is closed through Rac1 activation by MTs. For tubulin sequestering by stathmin, this establishes a bistable switch with two stable states: one stable state corresponds to upregulated MT mean length and bimodal MT length distributions, i.e., pioneering MTs; the other stable state corresponds to an interrupted feedback with short MTs. Stochastic effects as well as external perturbations can trigger switching events. For catastrophe promoting stathmin we do not find bistability.
Small-angle scattering instruments on a 1 MW long pulse spallation source
Olah, G.A.; Hjelm, R.P.; Seeger, P.A.
1995-12-01T23:59:59.000Z
Two small-angle neutron scattering instruments have been designed and optimized for installation at a 1 MW long pulse spallation source. The first of these instruments allows access to length scales in materials from 10 to 400 {angstrom}, and the second instrument from 40 to 1200 {angstrom}. Design characteristics were determined and optimization was done using the MCLIB Monte Carlo instrument simulation package. The code has been {open_quote}benchmarked{close_quote} by simulating the {open_quote}as-built{close_quote} D11 spectrometer at ILL and a performance comparison of the three instruments was made. Comparisons were made by evaluating the scattered intensity for {delta} scatterers at different Q values for various instrument configurations needed to span a Q-range of 0.0007 - 0.44 {angstrom}{sup {minus}1}.
Neutron Scattering Studies of Correlated Electron Systems
Boothroyd, Andrew
Neutron Scattering Studies of Correlated Electron Systems Lucy Helme Thesis submitted submitted for the Degree of Doctor of Philosophy, Trinity Term 2006 This thesis presents neutron scatteringO2, through inelastic neutron scattering studies of the crystal field transitions above and below
Measurements of the Thermal Neutron Scattering Kernel
Danon, Yaron
Measurements of the Thermal Neutron Scattering Kernel Li (Emily) Liu, Yaron Danon, Bjorn Becker and discussions Problems and Future study Questions #12;3 M. Mattes and J. Keinert, Thermal Neutron Scattering experimental data used was from 1973-1974! M. Mattes and J. Keinert, Thermal Neutron Scattering Data
Quantification of microstructural features in HMX using small angle neutron scattering techniques
Mang, J.T.; Skidmore, C.B.; Hjelm, R.P.; Howe, P.M.
1998-12-01T23:59:59.000Z
Microstructural features in raw powders of High Explosives have been qualitatively observed by many researchers, using polarized light and scanning electron microscopy. Here, the authors present a method for non-destructive quantification of volume fraction and structure of intragranular cracks and crystallization voids in a bulk sample (100--300 mg). By employing Small Angle Neutron Scattering (SANS) in conjunction with the method of contrast variation, they can effectively highlight different structural features of a complex system. The technique of contrast variation relies on immersing the sample in a uniform fluid of known neutron scattering length density. By selectively varying the scattering length density of the immersion fluid, scattering contributions from internal and external structures can be separated. This approach is analogous to varying the index of refraction for immersion oil relative to a sample in polarized light microscopy. SANS experiments on HMX were conducted using loose powders (261 and 10 micron mean particle diameters) and pellets made by uniaxial consolidation (without binder) to 7 and 10 volume percent porosity respectively. Detailed modeling of the SANS data indicate significant alteration of the intragranular void/crack/pore structure, with pressing, of the HMX powders.
Critical Waves and the Length Problem of Biology
Laughlin, R B
2015-01-01T23:59:59.000Z
It is pointed out that the mystery of how biological systems measure their lengths vanishes away if one premises that they have discovered a way to generate linear waves analogous to compressional sound. These can be used to detect length at either large or small scales using echo timing and fringe counting. It is shown that suitable linear chemical potential waves can, in fact, be manufactured by tuning to criticality conventional reaction-diffusion with a small number substances. Min oscillations in E. coli are cited as precedent resonant length measurement using chemical potential waves analogous to laser detection. Mitotic structures in eucaryotes are identified as candidates for such an effect at higher frequency. The engineering principle is shown to be very general and functionally the same as that used by hearing organs. PNAS Significance Statement: This paper invokes physical principles to address the question of how living things might use reaction-diffusion to measure out and regulate the many thou...
Pumping current of a Luttinger liquid with finite length
Sebastián Franchino Viñas; Pablo Pisani; Mariano Salvay
2012-03-16T23:59:59.000Z
We study transport properties in a Tomonaga-Luttinger liquid in the presence of two time-dependent point like weak impurities, taking into account finite-length effects. By employing analytical methods and performing a perturbation theory, we compute the backscattering pumping current (I_bs) in different regimes which can be established in relation to the oscillatory frequency of the impurities and to the frequency related to the length and the renormalized velocity (by the electron-electron interactions) of the charge density modes. We investigate the role played by the spatial position of the impurity potentials. We also show how the previous infinite length results for I_bs are modified by the finite size of the system.
FEL GAIN LENGTH AND TAPER MEASUREMENTS AT LCLS
Ratner, D.; Fawley, W. M.; Brachmann, A.; Decker, F.J.; Ding, Y.; Dowell, D.; Emma, P.; Frisch, J.; Gilevich, S.; Hays, G.; Hering, P.; Huang, Z.; Loos, H.; Miahnahri, A.; Nuhn, H.D.; Turner, J.; Welch, J.; White, W.; Wu, J.; Xiang, D.; Yocky, G.; Fawley, W. M.
2009-08-14T23:59:59.000Z
We present experimental studies of the gain length and saturation power level from 1.5 nm to 1.5 Angstroms at the Linac Coherent Light Source (LCLS). By disrupting theFEL process with an orbit kick, we are able to measure the X-ray intensity as a function of undulator length. This kick method is cross-checked with the method of removing undulator sections. We also study the FEL-induced electron energy loss after saturation to determine the optimal taper of the undulator K values. The experimental results are compared to theory and simulations.
Scattering of radiation in collisionless dusty plasmas
Tolias, P.; Ratynskaia, S. [Space and Plasma Physics, Royal Institute of Technology, Stockholm SE-100 44 (Sweden)
2013-04-15T23:59:59.000Z
Scattering of electromagnetic waves in collisionless dusty plasmas is studied in the framework of a multi-component kinetic model. The investigation focuses on the spectral distribution of the scattered radiation. Pronounced dust signatures are identified in the coherent spectrum due to scattering from the shielding cloud around the dust grains, dust acoustic waves, and dust-ion acoustic waves. The magnitude and shape of the scattered signal near these spectral regions are determined with the aid of analytical expressions and its dependence on the dust parameters is investigated. The use of radiation scattering as a potential diagnostic tool for dust detection is discussed.
Folding model analysis of pion elastic and inelastic scattering from {sup 6}Li and {sup 12}C
Ebrahim, A. A., E-mail: aebrahim@aun.edu.eg [Assiut University, Physics Department (Egypt)
2013-04-15T23:59:59.000Z
{pi}{sup {+-}}-Nucleus scattering cross sections are calculated applying the Watanabe superposition model with a phenomenological Woods-Saxon potential. The phenomenological potential parameters are searched for {pi}{sup {+-}} scattering from {sup 6}Li and {sup 12}C to reproduce not only differential elastic cross sections but also inelastic and total and reaction cross sections at pion kinetic energies from 50 to 672 MeV. The optical potentials of {sup 6}Li and {sup 12}C are calculated in terms of the alpha particle and deuteron optical potentials. Inelastic scattering has been analyzed using the distorted waves from elastic-scattering data. The values of deformation lengths thus obtained compare very well with the ones reported earlier.
Coulomb scattering in plasma revised
S. Gordienko; D. V. Fisher; J. Meyer-ter-Vehn
2003-05-13T23:59:59.000Z
A closed expression for the momentum evolution of a test particle in weakly-coupled plasma is derived, starting from quantum many particle theory. The particle scatters from charge fluctuations in the plasma rather than in a sequence of independent binary collisions. Contrary to general belief, Bohr's (rather than Bethe's) Coulomb logarithm is the relevant one in most plasma applications. A power-law tail in the distribution function is confirmed by molecular dynamics simulation.
Length control of microtubules by depolymerizing motor proteins
Bindu S. Govindan; Manoj Gopalakrishnan; Debashish Chowdhury
2008-07-08T23:59:59.000Z
In many intracellular processes, the length distribution of microtubules is controlled by depolymerizing motor proteins. Experiments have shown that, following non-specific binding to the surface of a microtubule, depolymerizers are transported to the microtubule tip(s) by diffusion or directed walk and, then, depolymerize the microtubule from the tip(s) after accumulating there. We develop a quantitative model to study the depolymerizing action of such a generic motor protein, and its possible effects on the length distribution of microtubules. We show that, when the motor protein concentration in solution exceeds a critical value, a steady state is reached where the length distribution is, in general, non-monotonic with a single peak. However, for highly processive motors and large motor densities, this distribution effectively becomes an exponential decay. Our findings suggest that such motor proteins may be selectively used by the cell to ensure precise control of MT lengths. The model is also used to analyze experimental observations of motor-induced depolymerization.
Performing local similarity searches with variable length seeds
CsÃ¼rÃ¶s, MiklÃ³s
Performing local similarity searches with variable length seeds MiklÂ´os CsurÂ¨os DÂ´epartement d manner. The algorithm uses a single parameter to control the speed of the similarity search there are many inventions that improve the speed of a full sensitivity search (e.g., [3]), a full-scale search
Reinforcement Learning for Active Length Control of Shape Memory Alloys
Valasek, John
Reinforcement Learning for Active Length Control of Shape Memory Alloys Kenton Kirkpatrick John Valasek Aerospace Engineering Department Texas A&M University AIAA GNC Conference 21 August 2008 Honolulu;Kirkpatrick & Valasek - 5 Shape Memory Alloys (SMA) Metallic Alloys used as actuators Shape Memory Effect
Multi-length Scale Modeling of CVD of Diamond Films
Grujicic, Mica
) of single-- crystalline and polycrystalline diamond films in acrystalline and polycrystalline diamond filmsMulti-length Scale Modeling of CVD of Diamond Films M. Grujicic and S. G. LaiM. Grujicic and S. G-scale Modeling of CVD Deposition of Diamond Films RotatingRotating--disk Hotdisk Hot--filament CVD
On Postnikov's Hook Length Formula for Binary Trees
Chen, Bill
note that Seo [7] also found combinatorial proof of the identity (1). Further studies related to Postnikov's hook length formula (1) have been carried out by Du and Liu [1], Gessel and Seo [2], Liu [4., 28 (2007), 1312-1321. [2] I. M. Gessel and S. Seo, A refinement of Cayley's formula for trees
Long-length contaminated equipment burial containers fabrication process procedures
McCormick, W.A., Fluor Daniel Hanford
1997-03-11T23:59:59.000Z
These special process procedures cover the detailed step-by-step procedures required by the supplier who will manufacture the Long-Length Contaminated Equipment (LLCE) Burial Container design. Also included are detailed step-by-step procedures required by the disposal process for completion of the LLCE Burial Containers at Hanford.
Lolon, Elyezer P.
2006-04-12T23:59:59.000Z
Low-permeability gas wells often produce less than predicted after a fracture treatment. One of the reasons for this is that fracture lengths calculated after stimulation are often less than designed lengths. While actual fracture lengths may...
Lolon, Elyezer P.
2006-04-12T23:59:59.000Z
Low-permeability gas wells often produce less than predicted after a fracture treatment. One of the reasons for this is that fracture lengths calculated after stimulation are often less than designed lengths. While actual fracture lengths may...
Association of length-slow silica with evaporites
Heaney, P.J. (Princeton Univ., Princeton, NJ (United States). Dept. of Geology); Sheppard, R.A. (Geological Survey, Denver, CO (United States). Denver Federal Center); Post, J.E. (Smithsonian Inst., Washington, DC (United States). Dept. of Mineral Sciences)
1992-01-01T23:59:59.000Z
In 1971, Folk and Pittman described the common occurrence of length-slow quartz (or lutecite) with evaporitic minerals, and they suggested that lutecite might be a useful indicator for vanished evaporites. However, the subsequent discoveries of length-slow silica in carbonate turbidites and in abyssal Pacific cherts revealed that lutecite is not restricted to near-surface deposits. Moreover, Kastner found that length-slow quartz could be crystallized in slightly alkaline solutions enriched in Mg[sup 2+], Na[sup +], and SO[sub 4][sup [minus]2]. Following these studies, researchers have cited the presence of lutecite in rock samples as suggestive but not compelling evidence for an evaporitic origin, and the precise nature of this form of silica has remained somewhat enigmatic. Investigations of chert nodules from evaporitic and non-evaporitic regimes support an identification of length-slow quartz'' with the mineral moganite, a polymorph of silica that is fibrous and optically length slow. Results are based upon X-ray powder diffraction of the chert, followed by Rietveld refinement of the X-ray patterns to quantify the weight fraction of quartz and moganite in each specimen. Most non-evaporitic chert appears to contain between 5 and 15 wt. % moganite, but evaporitic cherts often contain more than 20 wt. %. Cherts that have transformed from precursor magadiite can be particularly rich in moganite; samples from Lake Magadi, Kenya and from Harney Lake, Oregon revealed about equal parts moganite and quartz. However, the observation of decreasing abundances of moganite in rocks of increasing age indicates that moganite is metastable relative to quartz.
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AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of ScienceandMesa del Sol HomeFacebook Twitter Principal InvestigatorsSave Energy onofCNMS, SNS
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AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of ScienceandMesa del Sol HomeFacebook Twitter Principal InvestigatorsSave Energy onofCNMS, SNSScattering
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOnItemResearch > TheNuclearHomeland andEffectsScanning/Transmission Electron
Influence of the Environment Fluctuations on Incoherent Neutron Scattering Functions
D. J. Bicout
2001-04-09T23:59:59.000Z
In extending the conventional dynamic models, we consider a simple model to account for the environment fluctuations of particle atoms in a protein system and derive the elastic incoherent structure factor (EISF) and the incoherent scattering correlation function C(Q,t) for both the jump dynamics between sites with fluctuating site interspacing and for the diffusion inside a fluctuating sphere. We find that the EISF of the system (or the normalized elastic intensity) is equal to that in the absence of fluctuations averaged over the distribution of site interspacing or sphere radius a. The scattering correlation function is $C(Q,t)=\\sum_{n} \\psi(t)$, where the average is taken over the Q-dependent effective distribution of relaxation rates \\lambda_n(a) and \\psi(t) is the correlation function of the length a. When \\psi(t)=1, the relaxation of C(Q,t) is exponential for the jump dynamics between sites (since \\lambda_n(a) is independent of a) while it is nonexponential for diffusion inside a sphere.
Compton Scattering on the Proton
O. Scholten; S. Kondratyuk
2002-03-28T23:59:59.000Z
A microscopic coupled-channels model for Compton and pion scattering off the nucleon is introduced which is applicable at the lowest energies (polarizabilities) as well as at GeV energies. To introduce the model first the conventional K-matrix approach is discussed to extend this in a following chapter to the "Dressed K-Matrix" model. The latter approach restores causality, or analyticity, of the amplitude to a large extent. In particular, crossing symmetry, gauge invariance and unitarity are satisfied. The extent of violation of analyticity (causality) is used as an expansion parameter.
Completeness for sparse potential scattering
Shen, Zhongwei, E-mail: zzs0004@auburn.edu [Department of Mathematics and Statistics, Auburn University, Auburn, Alabama 36849 (United States)] [Department of Mathematics and Statistics, Auburn University, Auburn, Alabama 36849 (United States)
2014-01-15T23:59:59.000Z
The present paper is devoted to the scattering theory of a class of continuum Schrödinger operators with deterministic sparse potentials. We first establish the limiting absorption principle for both modified free resolvents and modified perturbed resolvents. This actually is a weak form of the classical limiting absorption principle. We then prove the existence and completeness of local wave operators, which, in particular, imply the existence of wave operators. Under additional assumptions on the sparse potential, we prove the completeness of wave operators. In the context of continuum Schrödinger operators with sparse potentials, this paper gives the first proof of the completeness of wave operators.
Small Angle X-Ray Scattering Detector
Hessler, Jan P.
2004-06-15T23:59:59.000Z
A detector for time-resolved small-angle x-ray scattering includes a nearly constant diameter, evacuated linear tube having an end plate detector with a first fluorescent screen and concentric rings of first fiber optic bundles for low angle scattering detection and an annular detector having a second fluorescent screen and second fiber optic bundles concentrically disposed about the tube for higher angle scattering detection. With the scattering source, i.e., the specimen under investigation, located outside of the evacuated tube on the tube's longitudinal axis, scattered x-rays are detected by the fiber optic bundles, to each of which is coupled a respective photodetector, to provide a measurement resolution, i.e., dq/q, where q is the momentum transferred from an incident x-ray to an x-ray scattering specimen, of 2% over two (2) orders of magnitude in reciprocal space, i.e., qmax/qmin approx=lO0.
Dangerous implications of a minimum length in quantum gravity
Cosimo Bambi; Katherine Freese
2008-07-17T23:59:59.000Z
The existence of a minimum length and a generalization of the Heisenberg uncertainty principle seem to be two fundamental ingredients required in any consistent theory of quantum gravity. In this letter we show that they would predict dangerous processes which are phenomenologically unacceptable. For example, long--lived virtual super--Planck mass black holes may lead to rapid proton decay. Possible solutions of this puzzle are briefly discussed.
Critical Waves and the Length Problem of Biology
R. B. Laughlin
2015-04-17T23:59:59.000Z
It is pointed out that the mystery of how biological systems measure their lengths vanishes away if one premises that they have discovered a way to generate linear waves analogous to compressional sound. These can be used to detect length at either large or small scales using echo timing and fringe counting. It is shown that suitable linear chemical potential waves can, in fact, be manufactured by tuning to criticality conventional reaction-diffusion with a small number substances. Min oscillations in E. coli are cited as precedent resonant length measurement using chemical potential waves analogous to laser detection. Mitotic structures in eucaryotes are identified as candidates for such an effect at higher frequency. The engineering principle is shown to be very general and functionally the same as that used by hearing organs. PNAS Significance Statement: This paper invokes physical principles to address the question of how living things might use reaction-diffusion to measure out and regulate the many thousands of lengths required to make their body parts and internal organs. It argues that two ideas have been missing. One is that oscillation is necessary to achieve the necessary design stability and plasticity. The other is that the system must be tuned to criticality to stabilize the propagation velocity, thus enabling clocks to function as meter sticks. The broader significance is twofold: First, a fundamental piece of the machinery of life is probably invisible to present-day biochemical methods because they are too slow. Second, the simplicity of growth and form identified a century ago by D'Arcy Thompson is probably a symptom of biological engineering strategies, not primitive law.
Multi-length Scale Modeling of Titanium Nitride Coatings
Grujicic, Mica
Multi-length Scale Modeling of Titanium Nitride Coatings M. Grujicic and S. G. LaiM. Grujicic and S Conservation Circumferential Momentum Conservation Thermal Energy Balance Species Continuity Dependent of Titanium Nitride Surface Species TiCl4(S): NH2(S): TiCl2(S): NH(S): TiCl(S): N(S): Ti (S): N*(S): Ti*(S): N
Magnetic field-line lengths inside interplanetary magnetic flux ropes
Hu, Qiang; Krucker, Sam
2015-01-01T23:59:59.000Z
We report on the detailed and systematic study of field-line twist and length distributions within magnetic flux ropes embedded in Interplanetary Coronal Mass Ejections (ICMEs). The Grad-Shafranov reconstruction method is utilized together with a constant-twist nonlinear force-free (Gold-Hoyle) flux rope model to reveal the close relation between the field-line twist and length in cylindrical flux ropes, based on in-situ Wind spacecraft measurements. We show that the field-line twist distributions within interplanetary flux ropes are inconsistent with the Lundquist model. In particular we utilize the unique measurements of magnetic field-line lengths within selected ICME events as provided by Kahler et al. (2011) based on energetic electron burst observations at 1 AU and the associated type III radio emissions detected by the Wind spacecraft. These direct measurements are compared with our model calculations to help assess the flux-rope interpretation of the embedded magnetic structures. By using the differen...
INVERSE SCATTERING OF SEISMIC DATA WITH THE ...
1910-61-22T23:59:59.000Z
We discuss the inverse scattering of seismic reflection data making use of the generalized Radon transform. Through an extension, the relevant transform attains ...
Coupled-channel scattering on a torus
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Guo, Peng [JLAB; Dudek, Jozef Jon [Old Dominion U., JLAB; Edwards, Robert G. [JLAB; Szczepaniak, Adam Pawel [Indiana U.
2013-07-01T23:59:59.000Z
Based on the Hamiltonian formalism approach, a generalized Luscher's formula for two particle scattering in both the elastic and coupled-channel cases in moving frames is derived from a relativistic Lippmann-Schwinger equation. Some strategies for extracting scattering amplitudes for a coupled-channel system from the discrete finite-volume spectrum are discussed and illustrated with a toy model of two-channel resonant scattering. This formalism will, in the near future, be used to extract information about hadron scattering from lattice QCD computations.
INVERSE SCATTERING PROBLEMS WITH MULTI-FREQUENCIES ...
2015-01-25T23:59:59.000Z
as location, geometry, or material property, from knowledge of the scattered field ... areas such as radar and sonar (e.g., stealth aircraft design and submarine ...
Fast methods for inverse wave scattering problems
Lee, Jung Hoon, Ph. D. Massachusetts Institute of Technology
2008-01-01T23:59:59.000Z
Inverse wave scattering problems arise in many applications including computerized/diffraction tomography, seismology, diffraction/holographic grating design, object identification from radar singals, and semiconductor ...
Recent Studies on Inverse Medium Scattering Problems
2007-06-28T23:59:59.000Z
Numerical examples are presented to illustrate the efficiency and robustness of the ... Energy estimates for the scattered field are established, which provide ...
Multiple-scattering series for color transparency
Greenberg, W.R.; Miller, G.A. (Department of Physics, FM-15, University of Washington, Seattle, Washington 98195 (United States))
1993-03-01T23:59:59.000Z
Cold transparency (CT) depends on the formation of a wave packet of small spatial extent. It is useful to interpret experimental searches for CT with a multiple-scattering series based on wave-packet--nucleon scattering instead of the standard one using nucleon-nucleon scattering. We develop several new techniques which are valid for differing ranges of energy. These techniques are applied to verify some early approximations, study new forms of the wave-packet--nucleon interaction, examine effects of treating wave packets of nonzero size, and predict the production of [ital N][sup *]'s in electron scattering experiments.
Lee, Wu-Jung
2013-01-01T23:59:59.000Z
The interpretation of echoes collected by active remote-sensing systems, such as sonar and radar, is often ambiguous due to the complexities in the scattering processes involving the scatterers, the environment, and the ...
Scattering of internal gravity waves
Leaman Nye, Abigail
2011-04-19T23:59:59.000Z
of the perturbed buoy- ancy field throughout a period of the motion. Curves represent cross-sections taken from the incident beam (cyan); a beam after reflection from a solid horizontal bound- ary (dark blue) and a beam after interaction with the sponge formation... wavenumber components and (b) plots power spectra calculated with Fourier and maximum entropy methods. k˜ is a nondimensional wavenumber representing the number of waves in an across-beam section of length Rc. . . . . . . 114 4.7 Two-dimensional power spectra...
22.101 Applied Nuclear Physics (Fall 2006) Lecture 8 (10/4/06) Neutron-Proton Scattering
unknown authors
We continue the study of the neutron-proton system by taking up the well-known problem of neutron scattering in hydrogen. The scattering cross section has been carefully measured to be 20.4 barns over a wide energy range. Our intent is to apply the method of phase shifts summarized in the preceding lecture to this problem. We see very quickly that the s-wave approximation (the condition of interaction at low energy) is very well justified in the neutron energy range of 1- 1000 eV. The scattering-state solution, with E> 0, gives us the phase shift or equivalently the scattering length. This calculation yields a cross section of 2.3 barns which is considerably different from the experimental value. The reason for the discrepancy lies in the fact that we have not taken into account the spin-dependent nature of the n-p interaction. The neutron and proton spins can form two distinct spin configurations, the two spins being parallel (triplet state) or anti-parallel (singlet), each giving rise to a scattering length. When this is taken into account, the new estimate is quite close to the experimental value. The conclusion is therefore that n-p interaction is spin-dependent and that the anomalously large value of the hydrogen scattering cross section for neutrons is really due to this aspect of the nuclear force. For the scattering problem our task is to solve the radial wave equation for s-wave for solutions with E> 0. The interior and exterior solutions have the form ur () = Bsin ( Kr ' ) , r < ro (8.1) and ur () = C sin(
Kucheyev, S O; Toth, M; Baumann, T F; Hamza, A V; Ilavsky, J; Knowles, W R; Thiel, B L; Tileli, V; van Buuren, T; Wang, Y M; Willey, T M
2006-06-05T23:59:59.000Z
We use low-vacuum scanning electron microscopy to image directly the ligament and pore size and shape distributions of representative aerogels over a wide range of length scales ({approx} 10{sup 0}-10{sup 5} nm). The images are used for unambiguous, real-space interpretation of small-angle scattering data for these complex nanoporous systems.
V. A. Babenko; N. M. Petrov
2007-04-08T23:59:59.000Z
The triplet and singlet low-energy parameters in the effective-range expansion for neutron--proton scattering are determined by using the latest experimental data on respective phase shifts from the SAID nucleon--nucleon database. The results differ markedly from the analogous parameters obtained on the basis of the phase shifts of the Nijmegen group and contradict the parameter values that are presently used as experimental ones. The values found with the aid of the phase shifts from the SAID nucleon--nucleon database for the total cross section for the scattering of zero-energy neutrons by protons, $\\sigma_{0}=20.426 $b, and the neutron--proton coherent scattering length, $f=-3.755 $fm, agree perfectly with the experimental cross-section values obtained by Houk, $\\sigma_{0}=20.436\\pm 0.023 $b, and experimental scattering-length values obtained by Houk and Wilson, $f=-3.756\\pm 0.009 $fm, but they contradict cross-section values of $\\sigma_{0}=20.491\\pm 0.014 $b according to Dilg and coherent-scattering-length values of $f=-3.7409\\pm 0.0011 $fm according to Koester and Nistler.
Compton Scattering on Black Body Photons
Lowell S. Brown; Ronald S. Steinke
1996-09-27T23:59:59.000Z
We examine Compton scattering of electrons on black body photons in the case where the electrons are highly relativistic, but the center of mass energy is small in comparison with the electron mass. We derive the partial lifetime of electrons in the LEP accelerator due to this form of scattering in the vacuum beam pipe and compare it with previous results.
Relativistic Wave Equations and Compton Scattering
B. A. Robson; S. H. Sutanto
2006-05-25T23:59:59.000Z
The recently proposed eight-component relativistic wave equation is applied to the scattering of a photon from a free electron (Compton scattering). It is found that in spite of the considerable difference in the structure of this equation and that of Dirac the cross section is given by the Klein-Nishina formula.
A Deeply Virtual Compton Scattering Amplitude
M. Capua; S. Fazio; R. Fiore; L. Jenkovszky; F. Paccanoni
2006-07-07T23:59:59.000Z
A factorized Regge-pole model for deeply virtual Compton scattering is suggested. The use of an effective logarithmic Regge-Pomeron trajectory provides for the description of both ``soft'' (small $|t|$) and ``hard'' (large $|t|$) dynamics. The model contains explicitly the photoproduction and the DIS limits and fits the existing HERA data on deeply virtual Compton scattering.
QCD Sum Rules and Virtual Compton Scattering
A. V. Radyushkin
1996-09-19T23:59:59.000Z
In this talk I report on recent progress in a few areas closely related to the virtual Compton scattering studies. In particular, I discuss the quark-hadron duality estimate of the $\\gamma^* p \\to \\Delta^+$ transition, QCD sum rule calculation of the $\\gamma \\gamma^* \\to \\pi^0$ form factor, and application of perturbative QCD to deeply virtual Compton scattering at small $t$.
Technology development for gene discovery and full-length sequencing
Marcelo Bento Soares
2004-07-19T23:59:59.000Z
In previous years, with support from the U.S. Department of Energy, we developed methods for construction of normalized and subtracted cDNA libraries, and constructed hundreds of high-quality libraries for production of Expressed Sequence Tags (ESTs). Our clones were made widely available to the scientific community through the IMAGE Consortium, and millions of ESTs were produced from our libraries either by collaborators or by our own sequencing laboratory at the University of Iowa. During this grant period, we focused on (1) the development of a method for preferential cloning of tissue-specific and/or rare transcripts, (2) its utilization to expedite EST-based gene discovery for the NIH Mouse Brain Molecular Anatomy Project, (3) further development and optimization of a method for construction of full-length-enriched cDNA libraries, and (4) modification of a plasmid vector to maximize efficiency of full-length cDNA sequencing by the transposon-mediated approach. It is noteworthy that the technology developed for preferential cloning of rare mRNAs enabled identification of over 2,000 mouse transcripts differentially expressed in the hippocampus. In addition, the method that we optimized for construction of full-length-enriched cDNA libraries was successfully utilized for the production of approximately fifty libraries from the developing mouse nervous system, from which over 2,500 full-ORF-containing cDNAs have been identified and accurately sequenced in their entirety either by our group or by the NIH-Mammalian Gene Collection Program Sequencing Team.
Dynamics and length distribution of microtubules under force and confinement
Björn Zelinski; Nina Müller; Jan Kierfeld
2012-12-14T23:59:59.000Z
We investigate the microtubule polymerization dynamics with catastrophe and rescue events for three different confinement scenarios, which mimic typical cellular environments: (i) The microtubule is confined by rigid and fixed walls, (ii) it grows under constant force, and (iii) it grows against an elastic obstacle with a linearly increasing force. We use realistic catastrophe models and analyze the microtubule dynamics, the resulting microtubule length distributions, and force generation by stochastic and mean field calculations; in addition, we perform stochastic simulations. We also investigate the force dynamics if growth parameters are perturbed in dilution experiments. Finally, we show the robustness of our results against changes of catastrophe models and load distribution factors.
Static Length Scales of N=6 Chern-Simons Plasma
Dongsu Bak; Kazem Bitaghsir Fadafan; Hyunsoo Min
2010-04-19T23:59:59.000Z
Using gravity description, we compute various static length scales of N=6 Chern Simons plasma in a strongly coupled regime. For this, we consider the CP3 compactification of the type IIA supergravity down to four dimensions, and identify all the low-lying bosonic modes up to masses corresponding to the operator dimension 3 together with all the remaining CP3 invariant modes. We find the true mass gap, the Debye screening mass and the corresponding dual operators to be probed in the field theory side.
Varying properties along lengths of temperature limited heaters
Vinegar, Harold J. (Bellaire, TX); Xie, Xueying (Houston, TX); Miller, David Scott (Katy, TX); Ginestra, Jean Charles (Richmond, TX)
2011-07-26T23:59:59.000Z
A system for heating a subsurface formation is described. The system includes an elongated heater in an opening in the formation. The elongated heater includes two or more portions along the length of the heater that have different power outputs. At least one portion of the elongated heater includes at least one temperature limited portion with at least one selected temperature at which the portion provides a reduced heat output. The heater is configured to provide heat to the formation with the different power outputs. The heater is configured so that the heater heats one or more portions of the formation at one or more selected heating rates.
Self-aligned submicron gate length gallium arsenide MESFET
Huang, Hsien-Ching
1987-01-01T23:59:59.000Z
38 21. Proximity cap annealing . 22. Temperature profile of post implant anneal 46 47 23. 24. 25. 26. 27. 28. 29. 30. "Pits" or holes in GaAs post implant anneal without sacrificial cap Silicon monoxide source (bafile box) used.... 16(b)). The bottom resist layer is then further etched in the oxygen plasma to produce undercutting for the desire gate structure. The amount of undercut is determined by the desired length of the gate and is the width of the remaining resist...
Pauling bond strength, bond length and electron density distribution
Gibbs, Gerald V.; Ross, Nancy L.; Cox, David F.; Rosso, Kevin M.; Iversen, Bo B.; Spackman, M. A.
2014-01-18T23:59:59.000Z
A power law regression equation, /r)-0.21, determined for a large number of oxide crystals at ambient conditions and /r)-0.22, determined for geometry optimized hydroxyacid molecules, that connect the bond lengths to the average Pauling electrostatic bond strength, , for the M-O bonded interactions. On the basis of the correspondence between the two sets of equations connecting ?(rc) and the Pauling bond strength s with bond length, it appears that Pauling’s simple definition of bond strength closely mimics the accumulation of the electron density between bonded pairs of atoms. The similarity of the expressions for the crystals and molecules is compelling evidence that the M-O bonded interactions for the crystals and molecules 2 containing the same bonded interactions are comparable. Similar expressions, connecting bond lengths and bond strength, have also been found to hold for fluoride, nitride and sulfide molecules and crystals. The Brown-Shannon bond valence, ?, power law expression ? = [R1/(R(M-O)]N that has found wide use in crystal chemistry, is shown to be connected to a more universal expression determined for oxides and the perovskites, = r[(1.41)/
136 3. Scattering The Compton scattering of an x-ray is incoherent because there are de-
136 3. Scattering The Compton scattering of an x-ray is incoherent because there are de- grees of freedom in each scattering event associated with the atomic electron. Compton scattering provides of an atom are the ones that can participate in Compton scattering because they can be- come unbound from
Temperature Dependent Neutron Scattering Sections for Polyethylene
Roger E. Hill; C. -Y. Liu
2003-09-05T23:59:59.000Z
This note presents neutron scattering cross sections for polyethylene at 296 K, 77 K and 4 K derived from a new scattering kernel for neutron scattering off of hydrogen in polyethylene. The kernel was developed in ENDF-6 format as a set of S(alpha,beta) tables using the LEAPR module of the NJOY94 code package. The polyethylene density of states (from 0 to sub eV) adopted to derive the new kernel is presented. We compare our calculated room temperature total scattering cross sections and double differential cross sections at 232 meV at various angles with the available experimental data (at room temperature), and then extrapolate the calculations to lower temperatures (77K and 4K). The new temperature dependent scattering kernel gives a good quantitative fit to the available room temperature data and has a temperature dependence that is qualitatively consistent with thermodynamics.
Modeling scattered intensity from microspheres in evanescent field
Shah, Suhani Kiran
2008-10-10T23:59:59.000Z
of the total scattered light intensity on microsphere size accounts for the scattered intensity distribution in a polydisperse microsphere sample. Understanding this variation in the scattered light with microsphere size will allow improved characterization...
UNIVERSITY OF CALIFORNIA Inelastic Neutron Scattering Study of the
Lawrence, Jon
UNIVERSITY OF CALIFORNIA IRVINE Inelastic Neutron Scattering Study of the Intermediate Valence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2 Inelastic Neutron Scattering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2.a Neutron Scattering Instruments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2.b
Fully portable, highly flexible dilution refrigerator systems for neutron scattering
Boyer, Edmond
775 Fully portable, highly flexible dilution refrigerator systems for neutron scattering P. A systems developed specifically for neutron scattering environ- ments. The refrigerators are completely relatively recently however, the lowest temperatures available in almost all neutron scattering laboratories
Beyond Mixing-length Theory: a step toward 321D
Arnett, W David; Viallet, Maxime; Campbell, Simon W; Lattanzio, John; Mo?ak, Miroslav
2015-01-01T23:59:59.000Z
We present a physical basis for algorithms to replace mixing-length theory (MLT) in stellar evolutionary computations. The 321D procedure is based on three-dimensional (3D) time-dependent solutions of the Navier-Stokes equations, including the Kolmogorov cascade as a sub-grid model of dissipation (implicit large eddy simulations; ILES). We use Reynolds-averaged Navier-Stokes (RANS) averaging to make 3D simulation data concise, and use 3D simulations to give RANS closure. We sketch a simple algorithm, which is non-local and time-dependent, with both MLT and the Lorenz convective roll as particular subsets of solutions. The damping length is determined from a balance between the large-scale driving and damping at the Kolmogorov scale. We find that (1) braking regions (boundary layers in which mixing occurs) automatically appear {\\it beyond} the edges of convection as defined by the Schwarzschild criterion, (2) dynamic (non-local) terms imply a non-zero turbulent kinetic energy flux (unlike MLT), (3) the effects...
Cooling Configuration Design Considerations for Long-Length HTS Cables
Demko, Jonathan A [ORNL; Duckworth, Robert C [ORNL
2009-01-01T23:59:59.000Z
Recent successes in demonstrating high temperature superconducting (HTS) cable systems hundreds of meters in length have inspired even longer length projects. A compact and energy efficient cooling configuration can be achieved using a counterflow-cooling arrangement. This is particularly attractive when all three phases are contained in a single cryostat because of the elimination of the space and thermal requirements of a separate liquid nitrogen return line. Future cable projects will utilize second generation (2G) wire which is expected to become lower in cost but may have different thermal requirements than first generation (1G) BSCCO wire due to the lower critical temperature and to a lesser extent, the lower thermal conductivity of the wire. HTS cable configurations will be studied with a numerical model to assess thermal hydraulic performance with AC and thermal losses; a summary of the results from the analysis will be presented. An analysis of the cable thermal- hydraulic response to over-current faults will be presented.
The Chain-Length Distribution in Subcritical Systems
Steven Douglas Nolen
2000-06-01T23:59:59.000Z
The individual fission chains that appear in any neutron multiplying system provide a means, via neutron noise analysis, to unlock a wealth of information regarding the nature of the system. This work begins by determining the probability density distributions for fission chain lengths in zero-dimensional systems over a range of prompt neutron multiplication constant (K) values. This section is followed by showing how the integral representation of the chain-length distribution can be used to obtain an estimate of the system's subcritical prompt multiplication (MP). The lifetime of the chains is then used to provide a basis for determining whether a neutron noise analysis will be successful in assessing the neutron multiplication constant, k, of the system in the presence of a strong intrinsic source. A Monte Carlo transport code, MC++, is used to model the evolution of the individual fission chains and to determine how they are influenced by spatial effects. The dissertation concludes by demonstrating how experimental validation of certain global system parameters by neutron noise analysis may be precluded in situations in which the system K is relatively low and in which realistic detector efficiencies are simulated.
The I=2 ?? S-wave Scattering Phase Shift from Lattice QCD
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Beane, S R; Detmold, W; Lin, H W; Luu, T C; Orginos, K; Parreno, A; Savage, M J; Torok, A; Walker-Loud, A
2012-02-16T23:59:59.000Z
The ?+?+ s-wave scattering phase-shift is determined below the inelastic threshold using Lattice QCD. Calculations were performed at a pion mass of m? ? 390 MeV with an anisotropic nf = 2+1 clover fermion discretization in four lattice volumes, with spatial extent L ? 2.0, 2.5, 3.0 and 3.9 fm, and with a lattice spacing of bs ? 0.123 fm in the spatial direction and bt bs/3.5 in the time direction. The phase-shift is determined from the energy-eigenvalues of ?+?+ systems with both zero and non-zero total momentum in the lattice volume using Luscher's method. Our calculations are precise enough to allow for a determination of the threshold scattering parameters, the scattering length a, the effective range r, and the shape-parameter P, in this channel and to examine the prediction of two-flavor chiral perturbation theory: m?2 a r = 3+O(m?2/??2). Chiral perturbation theory is used, with the Lattice QCD results as input, to predict the scattering phase-shift (and threshold parameters) at the physical pion mass. Our results are consistent with determinations from the Roy equations and with the existing experimental phase shift data.
The I=2 ?? S-wave Scattering Phase Shift from Lattice QCD
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Beane, S R; Detmold, W; Lin, H W; Luu, T C; Orginos, K; Parreno, A; Savage, M J; Torok, A; Walker-Loud, A
2012-02-16T23:59:59.000Z
The ?+?+ s-wave scattering phase-shift is determined below the inelastic threshold using Lattice QCD. Calculations were performed at a pion mass of m? ? 390 MeV with an anisotropic nf = 2+1 clover fermion discretization in four lattice volumes, with spatial extent L ? 2.0, 2.5, 3.0 and 3.9 fm, and with a lattice spacing of bs ? 0.123 fm in the spatial direction and bt bs/3.5 in the time direction. The phase-shift is determined from the energy-eigenvalues of ?+?+ systems with both zero and non-zero total momentum in the lattice volume using Luscher's method. Our calculations are precise enoughmore »to allow for a determination of the threshold scattering parameters, the scattering length a, the effective range r, and the shape-parameter P, in this channel and to examine the prediction of two-flavor chiral perturbation theory: m?2 a r = 3+O(m?2/??2). Chiral perturbation theory is used, with the Lattice QCD results as input, to predict the scattering phase-shift (and threshold parameters) at the physical pion mass. Our results are consistent with determinations from the Roy equations and with the existing experimental phase shift data.« less
Hjelm, R.P.
1998-12-01T23:59:59.000Z
The neutron scattering methods, small-angle neutron scattering and neutron reflectometry, provide information on the structure of polymer composite materials that is not available from other structural probes. The unique capabilities of these methods derive from three factors. First, the length scales probed correspond to polymer conformation, molecular and domain scales and to the characteristic sizes of many fillers. Second, neutrons are able to penetrate relatively thick samples, allowing bulk samples to be measured, and enabling buried interfaces to be studied. This characteristic also allows for the construction of special sample containment needed for studying materials under stress, extremes in pressure and temperature, etc. Third, neutrons readily distinguish between different light elements, and between different isotopes of the same element. The ability to distinguish between hydrogen and deuterium is particularly important in this regard. New ways of exploiting the capabilities of neutrons are opening up with the development of improved sources and instruments in the US and elsewhere. In this talk the author will discuss the basic concepts that give rise to the unique capabilities of neutron scattering, giving several examples of the uses of neutron scattering techniques in the study of polymer composites. The examples will include the morphology of fillers, polymer binders and matrices, interfaces and defect structures.
Nuclear level density as a tool for probing the inelastic scattering of 6He
Bora Canbula; Halil Babacan
2014-10-23T23:59:59.000Z
The cross sections are calculated for the both elastic and inelastic scattering of 6He from 12C and 4He. A phenomenological optical potential is used to describe the elastic scattering. 4He is taken as spherical and inelastic couplings to the first excited states of 6He and 12C are described with collective rotational model and coupled-channels method. Deformation lengths for 6He and 12C are determined from semi-classical nuclear level density model by using Laplace-like formula for the nuclear level density parameter. The comparison of the predicted and the measured cross sections are presented to test the applicability of nuclear level density model to the light exotic nuclei reactions. Good agreement is achieved between the predicted and measured cross sections.
pi pi scattering in a nonlocal Nambu: Jona-Lasinio model
Osipov, A A; Volkov, M K
2006-01-01T23:59:59.000Z
We consider a nonlocal version of the Nambu and Jona-Lasinio model. The nonlocality is contained in the quark-antiquark bilinears of the four-quark vertices as a form factor of the Gaussian type. The model has three parameters which can be fixed in favour of the values of the pion mass, the pion decay constant f_pi, and the current quark mass. The pi pi scattering amplitude is obtained by calculating the quark box and the sigma-pole diagrams, where sigma is the scalar isoscalar meson. It is shown that this amplitude satisfies the well-known Weinberg relation. We obtain the s, p, d wave scattering lengths in all isotopic channels and the s wave slope parameters. The results are in satisfactory agreement with both phenomenological data and the basic requirements of low-energy theorems, thus supporting to the form factor used.
Neutron scattering as a probe of liquid crystal polymer-reinforced composite materials
Hjelm, R.P.; Douglas, E.P.; Benicewicz, B.C.; Langlois, D.A.
1995-12-31T23:59:59.000Z
This is the final report of a three-year Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). This research project sought to obtain nanoscale and molecular level information on the mechanism of reinforcement in liquid crystal polymer (LCP)-reinforced composites, to realize molecular-reinforced LCP composites, and to test the validity of the concept of molecular reinforcement. Small-angle neutron scattering was used to study the structures in the ternary phase diagram of LCP with liquid crystal thermosets and solvent on length scales ranging from 1-100 nm. The goal of the scattering measurements is to understand the phase morphology and degree of segregation of the reinforcing and matrix components. This information helps elucidate the physics of self assembly in these systems. This work provides an experimental basis for a microengineering approach to composites of vastly improved properties.
angle light scattering: Topics by E-print Network
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Biological tissues tend Kim, Arnold D. 11 Static light scattering and small-angle neutron scattering study on aggregated recombinant gelatin in aqueous solution University...
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of scatterers Physics Websites Summary: experimentally and theoretically, the ballistic propagation of ultrasonic wave pulses through a random strongly scattering materials;...
Jefferson Lab experiment works to clarify Real Compton Scattering...
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Real Compton Scattering experiment spokespeople The Real Compton Scattering experiment spokespeople take a short break for a photo. From left is Bogdan Wojtsekhowski, JLab staff...
2012 LANSCE Neutron Scattering School | Los Alamos National Laboratory
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2 LANSCE Neutron Scattering School LANSCE 2012 LANSCE Neutron Scattering School Home About the School Hands-On Experiments Quick Links Application - Closed Schedule Poster...
Proton Angular Distribution for 90 Mev Neutron-proton Scattering
Hadley, James
2010-01-01T23:59:59.000Z
recoil protons in neutron -proton scattering at 90 Mev hasFOR 90 lWEV NEUTRON-PROTON SCATTERING James Hadley, Cecil E.
Application of Neutron Imaging and Scattering to Fluid Flow and...
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Application of Neutron Imaging and Scattering to Fluid Flow and Fracture in EGS Environments Application of Neutron Imaging and Scattering to Fluid Flow and Fracture in EGS...
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Laboratory Rex Hjelm Rex P. Hjelm is the Instrument Scientist for the small-angle neutron scattering instrument, LQD, at the Lujan Neutron Scattering Center of LANSCE at...
International Conference on Neutron Scattering 2005 Darling Harbour. Sydney. Australia
International Conference on Neutron Scattering 2005 Darling Harbour. Sydney. Australia 27 November, Hillerød, Denmark Combined application of small-angle neutron scattering and oscillatory shear
11th LANSCE School on Neutron Scattering | About the School
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students calculate results About the LANSCE School on Neutron Scattering The annual Los Alamos Neutron Science Center (LANSCE) School on Neutron Scattering is 9- to 10-day school...
2012 LANSCE Neutron Scattering School | Los Alamos National Laboratory
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1 LANSCE Neutron Scattering School LANSCE 2011 LANSCE Neutron Scattering School Home NSS 2011 About the School Lecturers Hands-On Experiments Quick Links Application Schedule...
High Energy Scattering Amplitudes of Superstring Theory
Chuan-Tsung Chan; Jen-Chi Lee; Yi Yang
2005-11-18T23:59:59.000Z
We use three different methods to calculate the proportionality constants among high-energy scattering amplitudes of different string states with polarizations on the scattering plane. These are the decoupling of high-energy zero-norm states (HZNS), the Virasoro constraints and the saddle-point calculation. These calculations are performed at arbitrary but fixed mass level for the NS sector of 10D open superstring. All three methods give the consistent results, which generalize the previous works on the high-energy 26D open bosonic string theory. In addition, we discover new leading order high-energy scattering amplitudes, which are still proportional to the previous ones, with polarizations orthogonal to the scattering plane. These scattering amplitudes are of subleading order in energy for the case of 26D open bosonic string theory. The existence of these new high-energy scattering amplitudes is due to the worldsheet fermion exchange in the correlation functions and is, presumably, related to the high-energy massive spacetime fermionic scattering amplitudes in the R-sector of the theory.
Simulations of The Dalles Dam Proposed Full Length Spillwall
Rakowski, Cynthia L.; Perkins, William A.; Richmond, Marshall C.; Serkowski, John A.
2008-02-25T23:59:59.000Z
This report presents results of a computational fluid dynamics (CFD) modeling study to evaluatethe impacts of a full-length spillwall at The Dalles Dam. The full-length spillwall is being designed and evaluated as a structural means to improve tailrace egress and thus survival of juvenile fish passing through the spillway. During the course of this study, a full-length spillwall at Bays 6/7 and 8/9 were considered. The U.S. Army Corps of Engineers (USACE) has proposed extending the spillwall constructed in the stilling basin between spillway Bays 6 and 7 about 590 ft farther downstream. It is believed that the extension of the spillwall will improve egress conditions for downstream juvenile salmonids by moving them more rapidly into the thalweg of the river hence reducing their exposure to predators. A numerical model was created, validated, and applied the The Dalles Dam tailrace. The models were designed to assess impacts to flow, tailrace egress, navigation, and adult salmon passage of a proposed spill wall extension. The more extensive model validation undertaken in this study greatly improved our confidence in the numerical model to represent the flow conditions in The Dalles tailrace. This study used these validated CFD models to simulate the potential impacts of a spillwall extension for The Dalles Dam tailrace for two locations. We determined the following: (1)The construction of an extended wall (between Bays 6/7) will not adversely impact entering or exiting the navigation lock. Impact should be less if a wall were constructed between Bays 8/9. (2)The construction of a wall between Bays 6/7 will increase the water surface elevation between the wall and the Washington shore. Although the increased water surface elevation would be beneficial to adult upstream migrants in that it decreases velocities on the approach to the adult ladder, the increased flow depth would enhance dissolved gas production, impacting potential operations of the project because of water quality. A wall between Bays 8/9 should have a lesser impact as the confined spill would be across more bays and the relative flow constriction less. (3) The 405 kcfs case was used for the rapid assessment of flow conditions and hydraulic mechanisms that might be responsible for the unexpected erosion at the end of the shelf downstream of Bay 7.
Nucleon-Nucleon Scattering Parameters in the Limit of SU(3) Flavor Symmetry
Beane, Silas [Universität Bonn; Chang, Emanuel [University of Washington; Savage, Martin [University of Washington; Lin, Huey-Wen [University of Washington; Orginos, Konstantinos [College of William and Mary, JLAB; Cohen, Saul [University of Washington; Detmold, William [MIT; Luu, Tom [College of William and Mary; Parreno, Assumpta [Universitat de Barcelona, Martí i Franquès 1; Junnarkar, Parikshit [University of New Hampshire; Walker-Loud, Andre Paul [LBNL, UC-Berkeley
2013-08-01T23:59:59.000Z
The scattering lengths and effective ranges that describe low-energy nucleon-nucleon scattering are calculated in the limit of SU(3)-flavor symmetry at the physical strange-quark mass with Lattice Quantum Chromodynamics. The calculations are performed with an isotropic clover discretization of the quark action in three volumes with spatial extents of L ~ 3.4 fm, 4.5 fm and 6.7 fm, and with a lattice spacing of b ~ 0.145 fm. With determinations of the energies of the two-nucleon systems ?both of which contain bound states at these light-quark masses? at rest and moving in the lattice volume, Luscher?s method is used to determine the low-energy phase shift in each channel, from which the scattering length and effective range are obtained. The scattering parameters in the {sup 1}S{sub 0} channel are found to be m{sub ?}a{sup ({sup 1}S{sub 0})} = 9.51+/-0.74+/-1.00 and m{sub ?}r{sup ({sup 1}S{sub 0})} = 4.76+/-0.37+/-0.40, and in the {sup 3}S{sub 1} channel are m{sub ?}a{sup ({sup 3}S{sub 1})} = 7.45+/-0.57+/-0.71 and m{sub ?}r{sup ({sup 3}S{sub 1})} = 3.71+/-0.28+/-0.28. These values are consistent with the two-nucleon system exhibiting Wigner?s supermultiplet symmetry, which becomes exact in the limit of large-N{sub c}.
CMB Cold Spot from Inflationary Feature Scattering
Wang, Yi
2015-01-01T23:59:59.000Z
We propose a "feature-scattering" mechanism to explain the cosmic microwave background cold spot seen from {\\it WMAP} and {\\it Planck} maps. If there are hidden features in the potential of multi-field inflation, the inflationary trajectory can be scattered by such features. The scattering is controlled by the amount of isocurvature fluctuations, and thus can be considered as a mechanism to convert isocurvature fluctuations into curvature fluctuations. This mechanism predicts localized cold spots (instead of hot ones) on the CMB. In addition, it may also bridge a connection between the cold spot and a dip on the CMB power spectrum at $\\ell \\sim 20$.
Diffraction Patterns in Deeply Virtual Compton Scattering
Asmita Mukherjee
2006-11-30T23:59:59.000Z
We report on a calculation to show that the Fourier transform of the Deeply Virtual Compton Scattering (DVCS) amplitude with respect to the skewness variable \\zeta at fixed invariant momentum transfer squared t gives results that are analogous to the diffractive scattering of a wave in optics. As a specific example, we utilize the quantum fluctuations of a fermion state at one loop in QED to obtain the behavior of the DVCS amplitude for electron-photon scattering. We then simulate the wavefunctions for a hadron by differentiating the above LFWFs with respect to M^2 and study the corresponding DVCS amplitudes in light-front longitudinal space.
Virtual Compton Scattering off the nucleon
P. A. M. Guichon; M. Vanderhaeghen
1998-06-08T23:59:59.000Z
We review the recent developments of virtual Compton scattering. We focus on the kinematical regimes which look the most promising. The threshold regime gives access to the generalized polarizabilities of the proton. The hard scattering regime allows tests of perturbative QCD predictions and of the valence quark wave function. The Bjorken regime is closely related to deep inelastic scattering. It gives access to the off-forward parton distributions which generalize the ordinary parton distributions and may shed a new light on the spin problem. For each regime we discuss the experimental perspectives and the role of the Bethe-Heitler background.
Attosecond neutron Compton scattering from protons
C. Aris Chatzidimitriou-Dreismann
2007-02-01T23:59:59.000Z
The effect of "anomalous" scattering of neutrons and electrons from protons in the electron-volt energy-transfer range is considered, and related experimental results are mentioned. A recent independent confirmation of this effect with a new data analysis procedure is presented. Due to the very short characteristic scattering time, there is no well defined separation of time scales of electronic and protonic motions. An outline of a proposed theoretical interpretation is presented, which is based on the fact that scattering protons represent \\textit{open} quantum systems, thus being subject to decoherence.
Hadronic ?Z box corrections in Møller scattering
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Hall, Nathan L. [Adelaide U.; Blunden, Peter G. [Manitoba U.; Melnitchouk, Wally [JLAB; Thomas, Anthony W. [Adelaide U.; Young, Ross D. [Adelaide U.
2014-04-01T23:59:59.000Z
The possibility of measuring the parity-violating asymmetry in Moller scattering with sufficient accuracy to determine sin2?W to 0.1% offers a complementary path to the discovery of new physics to that followed at high energy colliders. We present a new calculation of the ?Z box contribution to parity-violating electron-proton scattering, which constitutes an important uncertainty in computing the background to this process. We show that while the ?Z correction grows rapidly with energy, it can be relatively well constrained by data from parity-violating inelastic scattering and parton distribution functions.
Nuclear effects in deep inelastic scattering
O. Benhar; V.R. Pandharipande; I. Sick
1998-03-01T23:59:59.000Z
The authors extend the approach used to treat quasi-elastic inclusive electron-nucleus scattering to the deep inelastic region. They provide a general approach to describe lepton scattering from an off-shell nucleon, and calculate the ratio of inclusive deep inelastic scattering cross sections to the deuteron for nuclear matter and helium (EMC-effect). They find that the consistent inclusion of the binding effects, in particular the ones arising from the short-range nucleon-nucleon interaction, allows to describe the data in the region of x > 0.15 where binding fully accounts for the deviation of the cross section ratios from one.
Gordon Chalmers; Olaf Lechtenfeld; Bernd Niemeyer
2000-09-08T23:59:59.000Z
We calculate the genus-one three- and four-point amplitudes in the 2+2 dimensional closed N=(2,2) worldsheet supersymmetric string within the RNS formulation. Vertex operators are redefined with the incorporation of spinor helicity techniques, and the quantum scattering is shown to be manifestly gauge and Lorentz invariant after normalizing the string states. The continuous spin structure summation over the monodromies of the worldsheet fermions is carried out explicitly, and the field-theory limit is extracted. The amplitude in this limit is shown to be the maximally helicity violating amplitude in pure gravity evaluated in a two-dimensional setting, which vanishes, unlike the four-dimensional result. The vanishing of the genus-one N=2 closed string amplitude is related to the absence of one-loop divergences in dimensionally regulated IIB supergravity. Comparisons and contrasts between self-dual field theory and the N=2 string theory are made at the quantum level; they have different S-matrices. Finally, we point to further relations with self-dual field theory and two-dimensional models.
Long-length contaminated equipment disposal process path document
McCormick, W.A.
1998-09-30T23:59:59.000Z
The first objective of the LLCE Process Path Document is to guide future users of this system on how to accomplish the cradle-to-grave process for the disposal of long-length equipment. Information will be provided describing the function and approach to each step in the process. Pertinent documentation, prerequisites, drawings, procedures, hardware, software, and key interfacing organizations will be identified. The second objective is related to the decision to lay up the program until funding is made available to complete it or until a need arises due to failure of an important component in a waste tank. To this end, the document will identify work remaining to be completed for each step of the process and open items or issues that remain to be resolved.
Light absorption cell combining variable path and length pump
Prather, William S. (2419 Dickey Rd., Augusta, GA 30906)
1993-01-01T23:59:59.000Z
A device for use in making spectrophotometric measurements of fluid samples. In particular, the device is a measurement cell containing a movable and a fixed lens with a sample of the fluid therebetween and through which light shines. The cell is connected to a source of light and a spectrophotometer via optic fibers. Movement of the lens varies the path length and also pumps the fluid into and out of the cell. Unidirectional inlet and exit valves cooperate with the movable lens to assure a one-way flow of fluid through the cell. A linear stepper motor controls the movement of the lens and cycles it from a first position closer to the fixed lens and a second position farther from the fixed lens, preferably at least 10 times per minute for a nearly continuous stream of absorption spectrum data.
Analyzing gigahertz bunch length instabilities with a digital signal processor
Stege, R.E. Jr.; Krejcik, P.; Minty, M.G.
1992-11-01T23:59:59.000Z
A bunch length instability, nicknamed the ``sawtooth``, because of its transient behavior, has been observed at high current running in the Stanford Linear Collider (SLC) electron damping ring. The incompatibility of this instability with successful SLC naming prompted its study using a high bandwidth real-time spectrum analyzer, the Tektronix 3052 digital signal processor (DSP) system. This device has been used to study energy ramping in storage rings but this is the first time it has been used to study transient instability phenomena. It is a particularly valuable tool for use in understanding non-linear, multiple frequency phenomena. The frequency range of this device has been extended through the use of radio frequency (RF) down converters. This paper describes the measurement setup and presents some of the results.
Analyzing gigahertz bunch length instabilities with a digital signal processor
Stege, R.E. Jr.; Krejcik, P.; Minty, M.G.
1992-11-01T23:59:59.000Z
A bunch length instability, nicknamed the sawtooth'', because of its transient behavior, has been observed at high current running in the Stanford Linear Collider (SLC) electron damping ring. The incompatibility of this instability with successful SLC naming prompted its study using a high bandwidth real-time spectrum analyzer, the Tektronix 3052 digital signal processor (DSP) system. This device has been used to study energy ramping in storage rings but this is the first time it has been used to study transient instability phenomena. It is a particularly valuable tool for use in understanding non-linear, multiple frequency phenomena. The frequency range of this device has been extended through the use of radio frequency (RF) down converters. This paper describes the measurement setup and presents some of the results.
Light absorption cell combining variable path and length pump
Prather, W.S.
1993-12-07T23:59:59.000Z
A device is described for use in making spectrophotometric measurements of fluid samples. In particular, the device is a measurement cell containing a movable and a fixed lens with a sample of the fluid there between and through which light shines. The cell is connected to a source of light and a spectrophotometer via optic fibers. Movement of the lens varies the path length and also pumps the fluid into and out of the cell. Unidirectional inlet and exit valves cooperate with the movable lens to assure a one-way flow of fluid through the cell. A linear stepper motor controls the movement of the lens and cycles it from a first position closer to the fixed lens and a second position farther from the fixed lens, preferably at least 10 times per minute for a nearly continuous stream of absorption spectrum data. 2 figures.
DHS Internship Summary-Crystal Assembly at Different Length Scales
Mishchenko, L
2009-08-06T23:59:59.000Z
I was part of a project in which in situ atomic force microscopy (AFM) was used to monitor growth and dissolution of atomic and colloidal crystals. At both length scales, the chemical environment of the system greatly altered crystal growth and dissolution. Calcium phosphate was used as a model system for atomic crystals. A dissolution-reprecipitation reaction was observed in this first system, involving the conversion of brushite (DCPD) to octacalcium phosphate (OCP). In the second system, polymeric colloidal crystals were dissolved in an ionic solvent, revealing the underlying structure of the crystal. The dissolved crystal was then regrown through an evaporative step method. Recently, we have also found that colloids can be reversibly deposited in situ onto an ITO (indium tin oxide) substrate via an electrochemistry setup. The overall goal of this project was to develop an understanding of the mechanisms that control crystallization and order, so that these might be controlled during material synthesis. Controlled assembly of materials over a range of length scales from molecules to nanoparticles to colloids is critical for designing new materials. In particular, developing materials for sensor applications with tailorable properties and long range order is important. In this work, we examine two of these length scales: small molecule crystallization of calcium phosphate (whose crystal phases include DCPD, OCP, and HAP) and colloidal crystallization of Poly(methyl methacrylate) beads. Atomic Force Microscopy is ideal for this line of work because it allows for the possibility of observing non-conducting samples in fluid during growth with high resolution ({approx} 10 nm). In fact, during atomic crystal growth one can observe changes in atomic steps, and with colloidal crystals, one can monitor the individual building blocks of the crystal. Colloids and atoms crystallize under the influence of different forces acting at different length scales as seen in Table 1. In particular, molecular crystals, which are typically dominated by ionic and covalent bonding, are an order of magnitude more strongly bonded than colloidal crystals. In molecular crystals, ordering is driven by the interaction potentials between molecules. By contrast, colloidal assembly is a competition between the repulsive electrostatic forces that prevent aggregation in solution (due to surface charge), and short-range van der Waals and entropic forces that leads to ordering. Understanding atomic crystallization is fundamentally important for fabrication of tailorable crystalline materials, for example for biological or chemical sensors. The transformation of brushite to OCP not only serves as a model system for atomic crystal growth (applicable to many other crystal growth processes), but is also important in bone cements. Colloidal crystals have unique optical properties which respond to chemical and mechanical stimuli, making them very important for sensing applications. The mechanism of colloidal crystal assembly is thus fundamentally important. Our in situ dissolution and regrowth experiments are one good method of analyzing how these crystals pack under different conditions and how defect sites are formed and filled. In these experiments, a silica additive was used to strengthen the colloidal crystal during initial assembly (ex situ) and to increase domain size and long range order. Reversible electrodeposition of colloids onto a conductive substrate (ITO in our case) is another system which can further our knowledge of colloidal assembly. This experiment holds promise of allowing in situ observation of colloidal crystal growth and the influence of certain additives on crystal order. The ultimate goal would be to achieve long range order in these crystals by changing the surface charge or the growth environment.
Query-Efficient Locally Decodable Codes of Subexponential Length
Chee, Yeow Meng; Ling, San; Wang, Huaxiong; Zhang, Liang Feng
2010-01-01T23:59:59.000Z
We develop the algebraic theory behind the constructions of Yekhanin (2008) and Efremenko (2009), in an attempt to understand the ``algebraic niceness'' phenomenon in $\\mathbb{Z}_m$. We show that every integer $m = pq = 2^t -1$, where $p$, $q$ and $t$ are prime, possesses the same good algebraic property as $m=511$ that allows savings in query complexity. We identify 50 numbers of this form by computer search, which together with 511, are then applied to gain improvements on query complexity via Itoh and Suzuki's composition method. More precisely, we construct a $3^{\\lceil r/2\\rceil}$-query LDC for every positive integer $rLDC for every integer $r\\geq 104$, both of length $N_{r}$, improving the $2^r$ queries used by Efremenko (2009) and $3\\cdot 2^{r-2}$ queries used by Itoh and Suzuki (2010). We also obtain new efficient private information retrieval (PIR) schemes from the new query-efficient LDCs.
Analysis and Optimization of "Full-Length" Diodes
Schock, Alfred
2012-01-19T23:59:59.000Z
A method of analyzing the axial variation of the heat generation rate, temperature, voltage, current density and emitter heat flux in a thermionic converter is described. The method is particularly useful for the case of "long" diodes, each extending over the full length of the reactor core. For a given diode geometry and fuel distribution, the analysis combines a nuclear solution of the axial fission density profile with the iterative solution of four differential equations representing the thermal, electrical, and thermionic interactions within the diode. The digital computer program developed to solve these equations can also perform a design optimization with respect to lead resistance, load voltage, and emitter thickness, for a specified maximum emitter temperature. Typical results are presented, and the use of this analysis for predicting the diode operating characteristics is illustrated.
Characteristic length of an AdS/CFT superconductor
Kengo Maeda; Takashi Okamura
2008-10-30T23:59:59.000Z
We investigate in more detail the holographic model of a superconductor recently found by Hartnoll, Herzog, and Horowitz [Phys. Rev. Lett. 101, 031601], which is constructed from a condensate of a charged scalar field in AdS_4-Schwarzschild background. By analytically studying the perturbation of the gravitational system near the critical temperature T_c, we obtain the superconducting coherence length proportional to 1/\\sqrt{1-T/T_c} via AdS/CFT correspondence. By adding a small external homogeneous magnetic field to the system, we find that a stationary diamagnetic current proportional to the square of the order parameter is induced by the magnetic field. These results agree with Ginzburg-Landau theory and strongly support the idea that a superconductor can be described by a charged scalar field on a black hole via AdS/CFT duality.
Sewing on the Frame: Medieval Iberian Frametale Collections as Book-length Narratives
Nielsen, Karla Ann Merino
2010-01-01T23:59:59.000Z
the Novella: The European Tale Collection from Boccaccio andIberian Frametale Collections as Book-length Narratives byIberian Frametale Collections as Book-length Narratives by
E-Print Network 3.0 - active recombinant full-length Sample Search...
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the locus of integration... ), recombination between the 5 eyfp cassette and this down- stream 3 eyfp fragment cannot give rise to full-length... by restoration of full-length...
Fuzzy Partitioning Using Real Coded Variable Length Genetic Algorithm for Pixel Classification
Bandyopadhyay, Sanghamitra
, fuzzy clustering, pattern recognition, remote sensing imagery, Department of Computer Science, KalyaniFuzzy Partitioning Using Real Coded Variable Length Genetic Algorithm for Pixel Classification space. Real-coded variable string length genetic fuzzy clustering with automatic evolution of clusters
Heavy quarks in deeply virtual Compton scattering
Jens D. Noritzsch
2003-12-11T23:59:59.000Z
A detailed study of the heavy quark h=c,b,... contributions to deeply virtual Compton scattering is performed at both the amplitude and the cross section level, and their phenomenological relevance is discussed. For this purpose I calculate the lowest order off-forward photon-gluon scattering amplitude with a massive quark loop and the corresponding hard scattering coefficients. In a first numerical analysis these fixed order perturbation theory results are compared with the conventional intrinsic "massless" parton approach considering generalized parton distributions for the heavy quarks. The differences between these two prescriptions can be quite significant, especially at small skewedness where the massless approach largely overestimates the deeply virtual Compton scattering cross section.
QED radiative corrections to virtual Compton scattering
M. Vanderhaeghen; J. M. Friedrich; D. Lhuillier; D. Marchand; L. Van Hoorebeke; J. Van de Wiele
2000-01-12T23:59:59.000Z
The QED radiative corrections to virtual Compton scattering (reaction $e p \\to e p \\gamma$) are calculated to first order in $\\alpha_{em} \\equiv e^2 / 4 \\pi$. A detailed study is presented for the one-loop virtual corrections and for the first order soft-photon emission contributions. Furthermore, a full numerical calculation is given for the radiative tail, corresponding with photon emission processes, where the photon energy is not very small compared with the lepton momenta. We compare our results with existing works on elastic electron-proton scattering, and show for the $e p \\to e p \\gamma$ reaction how the observables are modified due to these first order QED radiative corrections. We show results for both unpolarized and polarized observables of the virtual Compton scattering in the low energy region (where one is sensitive to the generalized polarizabilities of the nucleon), as well as for the deeply virtual Compton scattering.
Compton Scattering in the ALS Booster
Robin, David
2008-01-01T23:59:59.000Z
pulses by colliding short laser pulses with highly focusedAs a result of the laser pulses short duration and the elec-ton side scattering of a short visible laser beam by a well-
Scattering Properties of Oriented Hexagonal Ice Crystals
Zhang, Feng
2010-01-14T23:59:59.000Z
To interpret the data from spaceborn lidar measurements, one must have a basic understanding of the backscattering of oriented ice particles. The conventional raytracing method is not applicable to the scattering of light by oriented particles...
Conformal Bootstrap, Universality and Gravitational Scattering
Steven Jackson; Lauren McGough; Herman Verlinde
2014-12-23T23:59:59.000Z
We use the conformal bootstrap equations to study the non-perturbative gravitational scattering between infalling and outgoing particles in the vicinity of a black hole horizon in AdS. We focus on irrational 2D CFTs with large $c$ and only Virasoro symmetry. The scattering process is described by the matrix element of two light operators (particles) between two heavy states (BTZ black holes). We find that the operator algebra in this regime is (i) universal and identical to that of Liouville CFT, and (ii) takes the form of an exchange algebra, specified by an R-matrix that exactly matches with the scattering amplitude of 2+1 gravity. The R-matrix is given by a quantum 6j-symbol and the scattering phase by the volume of a hyperbolic tetrahedron. We comment on the relevance of our results to scrambling and the holographic reconstruction of the bulk physics near black hole horizons.
INELASTIC LIGHT SCATTERING STUDIES OF BOROCARBIDE SUPERCONDUCTORS
Yang, In-Sang
INELASTIC LIGHT SCATTERING STUDIES OF BOROCARBIDE SUPERCONDUCTORS INSANG YANG Department In recent years of studies in ``unconventional'' superconductivity, researchers have concentrated on exotic behavior of the heavy fermion and cuprate su perconductors. However, even superconductors that are thought
What Does a Scattering Pattern Tell US?
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
amplitude e iwt Phase difference Phase difference S e i (ri Q) A(DK) fi A(Q) Fourier Transform ( ri ) DK Q 4p sin(q) l Lensless Imaging Sample Space Scattering Space...
Fully relativistic form factor for Thomson scattering
Palastro, J. P.; Ross, J. S.; Pollock, B.; Divol, L.; Froula, D. H.; Glenzer, S. H. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)
2010-03-15T23:59:59.000Z
We derive a fully relativistic form factor for Thomson scattering in unmagnetized plasmas valid to all orders in the normalized electron velocity, beta->=v->/c. The form factor is compared to a previously derived expression where the lowest order electron velocity, beta->, corrections are included [J. Sheffield, Plasma Scattering of Electromagnetic Radiation (Academic Press, New York, 1975)]. The beta-> expansion approach is sufficient for electrostatic waves with small phase velocities such as ion-acoustic waves, but for electron-plasma waves the phase velocities can be near luminal. At high phase velocities, the electron motion acquires relativistic corrections including effective electron mass, relative motion of the electrons and electromagnetic wave, and polarization rotation. These relativistic corrections alter the scattered emission of thermal plasma waves, which manifest as changes in both the peak power and width of the observed Thomson-scattered spectra.
Neutron-deuteron breakup and quasielastic scattering
Ohlson, Alice Elisabeth
2009-01-01T23:59:59.000Z
Quasielastic scattering and deuteron breakup in the 200 MeV region is studied by impinging a pulsed neutron beam on a deuterium target at the Weapons Neutron Research facility at the Los Alamos Neutron Science Center. The ...
W. J. Henney
1994-03-11T23:59:59.000Z
A general theoretical framework is developed for interpreting spectropolarimetric observations of optically thin emission line scattering from small dust particles. Spatially integrated and spatially resolved line profiles of both scattered intensity and polarization are calculated analytically from a variety of simple kinematic models. These calculations will provide a foundation for further studies of emission line scattering from dust and electrons in such diverse astrophysical environments as Herbig-Haro objects, symbiotic stars, starburst galaxies and active galactic nuclei.
Light-scattering studies of silica aerogels
Hunt, A.J.
1983-02-01T23:59:59.000Z
Due to its combination of transparency and low thermal conductivity, aerogel holds considerable promise for use as insulating window materials for residential and commercial applications. This paper reports on the preliminary investigation of the optical and scattering properties of silica aerogels. It briefly describes the properties of aerogels important for window glazing applications. The optical properties are then described, followed by a discussion of the scattering measurements and their interpretation.
QCD Sum Rules and Compton Scattering
Claudio Coriano'; Anatoly Radyushkin; George Sterman
1993-01-26T23:59:59.000Z
We extend QCD sum rule analysis to moderate energy fixed angle Compton scattering. In this kinematic region there is a strong similarity to the sum rule treatment of electromagnetic form factors, although the four-point amplitude requires a modification of the Borel transform. To illustrate our method, we derive the sum rules for helicity amplitudes in pion Compton scattering and estimate their large-$t$ behavior in the local duality approximation.
Parity Violation in gamma proton Compton Scattering
Paulo F. Bedaque; Martin J. Savage
1999-10-19T23:59:59.000Z
A measurement of parity-violating spin-dependent gamma proton Compton scattering will provide a theoretically clean determination of the parity-violating pion-nucleon coupling constant $h_{\\pi NN}^{(1)}$. We calculate the leading parity-violating amplitude arising from one-loop pion graphs in chiral perturbation theory. An asymmetry of ~5 10^{-8} is estimated for Compton scattering of 100 MeV photons.
Scattering by coupled resonating elements in air
Anton Krynkin; Olga Umnova; Alvin Y. B. Chong; Shahram Taherzadeh; Keith Attenborough
2011-01-12T23:59:59.000Z
Scattering by (a) a single composite scatterer consisting of a concentric arrangement of an outer N-slit rigid cylinder and an inner cylinder which is either rigid or in the form of a thin elastic shell and (b) by a finite periodic array of these scatterers in air has been investigated analytically and through laboratory experiments. The composite scatterer forms a system of coupled resonators and gives rise to multiple low frequency resonances. The corresponding analytical model employs polar angle dependent boundary conditions on the surface of the N-slit cylinder. The solution inside the slits assumes plane waves. It is shown also that in the low-frequency range the N-slit rigid cylinder can be replaced by an equivalent fluid layer. Further approximations suggest a simple square root dependence of the resonant frequencies on the number of slits and this is confirmed by data. The observed resonant phenomena are associated with Helmholtz-like behaviour of the resonator for which the radius and width of the openings are much smaller than the wavelength. The problem of scattering by a finite periodic array of such coupled resonators in air is solved using multiple scattering techniques. The resulting model predicts band-gap effects resulting from the resonances of the individual composite scatterers below the first Bragg frequency . Predictions and data confirm that use of coupled resonators results in substantial insertion loss peaks related to the resonances within the concentric configuration. In addition, for both scattering problems experimental data, predictions of the analytical approach and predictions of the equivalent fluid layer approximations are compared in the low-frequency interval.
Symmetry Algebra of IIB Superstring Scattering
Gordon Chalmers
2005-10-26T23:59:59.000Z
The graviton scattering in IIB superstring theory is examined in the context of S-duality and symmetry. There is an algebra that generates all of the terms in the four-point function to any order in derivatives. A map from the algebra to the scattering is given; it suggests the correctness of the full four-point function with the S-duality. The higher point functions are expected to follow a similar pattern.
Variation of Entanglement Entropy in Scattering Process
I. Y. Park; Shigenori Seki; Sang-Jin Sin
2015-01-09T23:59:59.000Z
In a scattering process, the final state is determined by an initial state and an S-matrix. We focus on two-particle scattering processes and consider the entanglement between these particles. For two types initial states; i.e., an unentangled state and an entangled one, we calculate perturbatively the change of entanglement entropy from the initial state to the final one. Then we show a few examples in a field theory and in quantum mechanics.
An electrical resistance method for determining the fiber length distribution of cotton lint
Hartstack, Albert W
1961-01-01T23:59:59.000Z
. . ~. . . o ~ o . i e ~ e Specimen Clamp Vise ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ Page ~ ~ ~ 14 5 16 Instrumentation for %ms u'ing and Recotrd&g the Length of Cotton Fibers. . . . ~ IB 5. Ezpcrimsntal Setup for Nsasuring the Length Distribution... the difference 'n fiber length was cl earil reer, o?sibbs for inferior processing arid yarn quality, Abided et al (5) nake this statement conci ming length: A review of the previous work done on the relationship between the fiber-properties and the spinrdng...
Software-only Multiple Variable Length Decoding for Real-Time Video on MDSP*
Chaudhary, Vipin
3.44 Software-only Multiple Variable Length Decoding for Real- Time Video on MDSP* Ganesh Yadav', R Inc. Abstract-We present the multiple variable length decode algorithm implemented in most video mechanism. I. INTRODUCTION Variable Length Decoding (VLD) is the most important part of the video standards
QueueTrak: Automated Line Length Detection using a Wireless Sensor Network
Whitehouse, Kamin
, it uses a series of custom active infrared sensors to detect the length of a line in a store or restaurant the design, implementation, and evaluation of QueueTrak, a sensor network that measures the length of linesQueueTrak: Automated Line Length Detection using a Wireless Sensor Network Jared Alexander, Matthew
A New Technique To Determine The Upper Threshold for Finite Length Turbo Codes
Chaturvedi, A K
A New Technique To Determine The Upper Threshold for Finite Length Turbo Codes A.Rajeshand A in finite frame length turbo codes. These thresholds depend on the component encoder as well as the frame to indecisive and unequivocal fixed points respectively, for finiteframe length turbo codes. Concurrently, Gamal
Neutron and X-ray Scattering Study of Magnetic Manganites
Boothroyd, Andrew
Neutron and X-ray Scattering Study of Magnetic Manganites Graeme Eoin Johnstone A Thesis submitted are performed using a variety of neutron scattering and x-ray scattering techniques. The electronic ground for analysing the results of the polarised neutron scattering experiment. There are a large number of people who
Neutron scattering at high pressure D. B. McWhan
Paris-Sud XI, Université de
715 Neutron scattering at high pressure D. B. McWhan Room 1D-234, Murray Hill, New Jersey 07974, U scattering at steady-state and pulsed sources are reviewed. The pressure cells available at most neutron 10 GPa have been made. For elastic scattering, a comparison is made between neutron scattering and X
Love, Steven P.; Davis, A. B. (Anthony B.); Rohde, C. A. (Charles A.); Tellier, L. L. (Larry L.); Ho, Cheng,
2002-01-01T23:59:59.000Z
At most optical wavelengths, laser light in a cloud lidar experiment is not absorbed but merely scattered out of the beam, eventually escaping the cloud via multiple scattering. There is much information available in this light scattered far from the input beam, information ignored by traditional 'on-beam' lidar. Monitoring these off-beam returns in a fully space- and time-resolved manner is the essence of our unique instrument, Wide Angle Imaging Lidar (WAIL). In effect, WAIL produces wide-field (60-degree full-angle) 'movies' of the scattering process and records the cloud's radiative Green functions. A direct data product of WAIL is the distribution of photon path lengths resulting from multiple scattering in the cloud. Following insights from diffusion theory, we can use the measured Green functions to infer the physical thickness and optical depth of the cloud layer, and, from there, estimate the volume-averaged liquid water content. WAIL is notable in that it is applicable to optically thick clouds, a regime in which traditional lidar is reduced to ceilometry. Here we present recent WAIL data oti various clouds and discuss the extension of WAIL to full diurnal monitoring by means of an ultra-narrow magneto-optic atomic line filter for daytime measurements.
On the Lengths, Colours and Ages of Bars
F. Combes; J. Palous; Dimitri A. Gadotti; Ronaldo E. De Souza
2006-01-01T23:59:59.000Z
Abstract. In an effort to obtain further observational evidences for secular evolution processes in galaxies, as well as observational constraints to current theoretical models of secular evolution, we have used BVRI and Ks images of a sample of 18 barred galaxies to measure the lengths and colours of bars, create colour maps and estimate global colour gradients. In addition, applying a method we developed in a previous article, we could distinguish for 7 galaxies in our sample those whose bars have been recently formed from the ones with already evolved bars. We estimated an average difference in the optical colours between young and evolved bars that may be translated to an age difference of the order of 10 Gyr, meaning that bars may be long standing structures. Moreover, our results show that, on average, evolved bars are longer than young bars. This seems to indicate that, during its evolution, a bar grows longer by capturing stars from the disk, in agreement with recent numerical and analytical results.
Thermal management of long-length HTS cable systems
Demko, Jonathan A [ORNL; Hassenzahl, William V [ORNL
2011-01-01T23:59:59.000Z
Projections of electric power production suggest a major shift to renewables, such as wind and solar, which will be in remote locations where massive quantities of power are available. One solution for transmitting this power over long distances to load centers is direct current (dc), high temperature superconducting (HTS) cables. Electric transmission via dc cables promises to be effective because of the low-loss, highcurrent- carrying capability of HTS wire at cryogenic temperatures. However, the thermal management system for the cable must be carefully designed to achieve reliable and energyefficient operation. Here we extend the analysis of a superconducting dc cable concept proposed by the Electric Power Research Institute (EPRI), which has one stream of liquid nitrogen flowing in a cryogenic enclosure that includes the power cable, and a separate return tube for the nitrogen. Refrigeration stations positioned every 10 to 20 km cool both nitrogen streams. Both go and return lines are contained in a single vacuum/cryogenic envelope. Other coolants, including gaseous helium and gaseous hydrogen, could provide potential advantages, though they bring some technical challenges to the operation of long-length HTS dc cable systems. A discussion of the heat produced in superconducting cables and a system to remove the heat are discussed. Also, an analysis of the use of various cryogenic fluids in long-distance HTS power cables is presented.
Kurokawa, M.; Kitajima, M.; Toyoshima, K.; Kishino, T.; Odagiri, T. [Department of Chemistry, Tokyo Institute of Technology, Tokyo 152-8551 (Japan); Kato, H.; Hoshino, M.; Tanaka, H. [Department of Physics, Sophia University, Tokyo 102-8554 (Japan); Ito, K. [Photon Factory, Institute of Materials Structure Science, Tsukuba 305-0801 (Japan)
2011-12-15T23:59:59.000Z
Absolute total cross sections for electron scattering from Ar and Xe at electron energies ranging from 7 meV to 20 eV were obtained with the experimental technique employing the threshold-photoelectron source. The measured total cross sections are in good agreement with those obtained by other groups down to 100 meV, above which several experimental works have been reported. Scattering lengths for electron scattering from Ar, Kr, and Xe were determined from the present total cross sections and our recent results for Kr using the modified effective range theory. The values of the scattering length obtained in the present analysis differ from the values determined from the previous swarm experiments and beam experiments. The resonant structures in the total cross sections due to Feshbach resonances of Ar, Kr, and Xe with an improved energy resolution were also measured. Analyses of the resonant structure were carried out based on the spin-dependent resonant scattering theory in order to determine the values of the natural width of Feshbach resonances of Ar, Kr, and Xe precisely.
Method for compression of data using single pass LZSS and run-length encoding
Berlin, G.J.
1994-01-01T23:59:59.000Z
A method used preferably with LZSS-based compression methods for compressing a stream of digital data. The method uses a run-length encoding scheme especially suited for data strings of identical data bytes having large run-lengths, such as data representing scanned images. The method reads an input data stream to determine the length of the data strings. Longer data strings are then encoded in one of two ways depending on the length of the string. For data strings having run-lengths less than 18 bytes, a cleared offset and the actual run-length are written to an output buffer and then a run byte is written to the output buffer. For data strings of 18 bytes or longer, a set offset and an encoded run-length are written to the output buffer and then a run byte is written to the output buffer. The encoded run-length is written in two parts obtained by dividing the run length by a factor of 255. The first of two parts of the encoded run-length is the quotient; the second part is the remainder. Data bytes that are not part of data strings of sufficient length are written directly to the output buffer.
Simulation and Application of Light Scattering Properties for Scatterers with Large Aspect Ratios
Sun, Bingqiang
2014-12-02T23:59:59.000Z
scatterers with one dimension periodicity, a semi-analytical solution instead of the iterative technique has been obtained by extending the application of the MBIT method to infinite number of sub-units. The semi-analytical solution of a scatterer with 1-D...
Simulation and Application of Light Scattering Properties for Scatterers with Large Aspect Ratios
Sun, Bingqiang
2014-12-02T23:59:59.000Z
For scatterers with axial or N-fold rotational symmetry, the T-matrix is one of the most efficient techniques to obtain the scattering properties. Extended boundary condition method (EBCM) and invariant imbedding T-matrix method (II-TM...
Coherent neutron scattering and collective dynamics on mesoscale
Novikov, Vladimir [ORNL; Schweizer, Kenneth S [ORNL; Sokolov, Alexei P [ORNL
2013-01-01T23:59:59.000Z
By combining, and modestly extending, a variety of theoretical concepts for the dynamics of liquids in the supercooled regime, we formulate a simple analytic model for the temperature and wavevector dependent collective density fluctuation relaxation time that is measurable using coherent dynamic neutron scattering. Comparison with experiments on the ionic glass-forming liquid Ca K NO3 in the lightly supercooled regime suggests the model captures the key physics in both the local cage and mesoscopic regimes, including the unusual wavevector dependence of the collective structural relaxation time. The model is consistent with the idea that the decoupling between diffusion and viscosity is reflected in a different temperature dependence of the collective relaxation time at intermediate wavevectors and near the main (cage) peak of the static structure factor. More generally, our analysis provides support for the ideas that decoupling information and growing dynamic length scales can be at least qualitatively deduced by analyzing the collective relaxation time as a function of temperature and wavevector, and that there is a strong link between dynamic heterogeneity phenomena at the single and many particle level. Though very simple, the model can be applied to other systems, such as molecular liquids.
Inclusion of Scatter in HADES: Final Report
Aufderheide, M B
2010-12-20T23:59:59.000Z
Covert nuclear attack is one of the foremost threats facing the United States and is a primary focus of the War on Terror. The Domestic Nuclear Detection Office (DNDO), within the Department of Homeland Security (DHS), is chartered to develop, and improve domestic systems to detect and interdict smuggling for the illicit use of a nuclear explosive device, fissile material or radiologica1 material. The CAARS (Cargo Advanced Automated Radiography System) program is a major part of the DHS effort to enhance US security by harnessing cutting-edge technologies to detect radiological and nuclear threats at points of entry to the United States. DNDO has selected vendors to develop complete radiographic systems. It is crucial that the initial design and testing concepts for the systems be validated and compared prior to the substantial efforts to build and deploy prototypes and subsequent large-scale production. An important aspect of these systems is the scatter which interferes with imaging. Monte Carlo codes, such as MCNP (X-5 Monte Carlo Team, 2005 Revision) allow scatter to be calculatied, but these calculations are very time consuming. It would be useful to have a fast scatter estimation algorithm in a fast ray tracing code. We have been extending the HADES ray-tracing radiographic simulation code to model vendor systems in a flexible and quick fashion and to use this tool to study a variety of questions involving system performance and the comparative value of surrogates. To enable this work, HADES has been linked to the BRL-CAD library (BRL-CAD Open Source Project, 2010), in order to enable the inclusion of complex CAD geometries in simulations, scanner geometries have been implemented in HADES, and the novel detector responses have been included in HADES. A major extension of HADES which has been required by this effort is the inclusion of scatter in these radiographic simulations. Ray tracing codes generally do not easily allow the inclusion of scatter, because these codes define a source and a grid of detector pixels and only compute the attenuation along rays between these points. Scatter is an extremely complex set of processes which can involve rays which change directions many times between the source and detector. Scatter from outside the field of view of the imaging system, as well as within the field of view, can have an important role in image formation. In this report, we will describe how we implemented a treatment of scatter in HADES. We begin with a discussion of how we define scatter in Section 2, followed by a description of how single Compton scatter is now included in HADES in Section 3. In Section 4 we report a set of verification tests against MCNP and tests of how the technique scales with image size, number of scatters allowed and number of processors used in the calculations. In Section 5, we describe how we plan to extend this approach to other forms of scatter and conclude in Section 6. It should be emphasized that the purpose of this report is to show that a form of scatter has been implemented in HADES and has been verified against MCNP. Validation, the process of comparing simulation and experiment, is a future task.
BUILDING A NETWORK FOR NEUTRON SCATTERING EDUCATION
Pynn, Roger [ORNL; Baker, Shenda Mary [ORNL; Louca, Despo A [ORNL; McGreevy, Robert L [ORNL; Ekkebus, Allen E [ORNL; Kszos, Lynn A [ORNL; Anderson, Ian S [ORNL
2008-10-01T23:59:59.000Z
In a concerted effort supported by the National Science Foundation, the Department of Commerce, and the Department of Energy, the United States is rebuilding its leadership in neutron scattering capability through a significant investment in U.S. neutron scattering user facilities and related instrumentation. These unique facilities provide opportunities in neutron scattering to a broad community of researchers from academic institutions, federal laboratories, and industry. However, neutron scattering is often considered to be a tool for 'experts only' and in order for the U.S. research community to take full advantage of these new and powerful tools, a comprehensive education and outreach program must be developed. The workshop described below is the first step in developing a national program that takes full advantage of modern education methods and leverages the existing educational capacity at universities and national facilities. During March 27-28, 2008, a workshop entitled 'Building a Network for Neutron Scattering Education' was held in Washington, D.C. The goal of the workshop was to define and design a roadmap for a comprehensive neutron scattering education program in the United States. Successful implementation of the roadmap will maximize the national intellectual capital in neutron sciences and will increase the sophistication of research questions addressed by neutron scattering at the nation's forefront facilities. (See Appendix A for the list of attendees, Appendix B for the workshop agenda, Appendix C for a list of references. Appendix D contains the results of a survey given at the workshop; Appendix E contains summaries of the contributed talks.) The workshop brought together U.S. academicians, representatives from neutron sources, scientists who have developed nontraditional educational programs, educational specialists, and managers from government agencies to create a national structure for providing ongoing neutron scattering education. A concerted effort was made to involve representatives from historically black colleges and universities (HBCUs) and minority educational institutions (MEIs). The roadmap contained herein provides the path to a national infrastructure for education of students, faculty, and professional researchers who wish to make use of national neutron scattering facilities but do not have (or do not believe they have) the educational background to do so. Education of other stakeholders, including the public, students in kindergarten through twelfth grade (K-12), and policy makers is also included. The opening sessions of the workshop provided the current status of neutron scattering education in North America, Europe, and Australia. National neutron sources have individually developed outreach and advertising programs aimed at increasing awareness among researchers of the potential applications of neutron scattering. However, because their principal mission is to carry out scientific research, their outreach efforts are necessarily self-limiting. The opening session was designed to build awareness that the individual programs need to be coupled with, and integrated into, a broader education program that addresses the complete range of experience, from the student to the experienced researcher, and the wide range of scientific disciplines covered by neutron scattering. Such a program must also take full advantage of existing educational programs and expertise at universities and expand them using modern distance learning capabilities, recognizing that the landscape of education is changing.
Scattering and; Delay, Scale, and Sum Migration
Lehman, S K
2011-07-06T23:59:59.000Z
How do we see? What is the mechanism? Consider standing in an open field on a clear sunny day. In the field are a yellow dog and a blue ball. From a wave-based remote sensing point of view the sun is a source of radiation. It is a broadband electromagnetic source which, for the purposes of this introduction, only the visible spectrum is considered (approximately 390 to 750 nanometers or 400 to 769 TeraHertz). The source emits an incident field into the known background environment which, for this example, is free space. The incident field propagates until it strikes an object or target, either the yellow dog or the blue ball. The interaction of the incident field with an object results in a scattered field. The scattered field arises from a mis-match between the background refractive index, considered to be unity, and the scattering object refractive index ('yellow' for the case of the dog, and 'blue' for the ball). This is also known as an impedance mis-match. The scattering objects are referred to as secondary sources of radiation, that radiation being the scattered field which propagates until it is measured by the two receivers known as 'eyes'. The eyes focus the measured scattered field to form images which are processed by the 'wetware' of the brain for detection, identification, and localization. When time series representations of the measured scattered field are available, the image forming focusing process can be mathematically modeled by delayed, scaled, and summed migration. This concept of optical propagation, scattering, and focusing have one-to-one equivalents in the acoustic realm. This document is intended to present the basic concepts of scalar scattering and migration used in wide band wave-based remote sensing and imaging. The terms beamforming and (delayed, scaled, and summed) migration are used interchangeably but are to be distinguished from the narrow band (frequency domain) beamforming to determine the direction of arrival of a signal, and seismic migration in which wide band time series are shifted but not to form images per se. Section 3 presents a mostly graphically-based motivation and summary of delay, scale, and sum beamforming. The model for incident field propagation in free space is derived in Section 4 under specific assumptions. General object scattering is derived in Section 5 and simplified under the Born approximation in Section 6. The model of this section serves as the basis in the derivation of time-domain migration. The Foldy-Lax, full point scatterer scattering, method is derived in Section 7. With the previous forward models in hand, delay, scale, and sum beamforming is derived in Section 8. Finally, proof-of-principle experiments are present in Section 9.
Massive superstring scatterings in the Regge regime
He Song; Lee, Jen-Chi; Takahashi, Keijiro; Yang Yi [Institute of High Energy Physics, Chinese Academic of Sciences, Beijing (China); Department of Electrophysics, National Chiao-Tung University and Physics Division, National Center for Theoretical Sciences, Hsinchu, Taiwan (China); Department of Electrophysics, National Chiao-Tung University, Hsinchu, Taiwan (China); Department of Electrophysics, National Chiao-Tung University and Physics Division, National Center for Theoretical Sciences, Hsinchu, Taiwan (China)
2011-03-15T23:59:59.000Z
We calculate four classes of high-energy massive string scattering amplitudes of fermionic string theory at arbitrary mass levels in the Regge regime (RR). We show that all four leading order amplitudes in the RR can be expressed in terms of the Kummer function of the second kind. Based on the summation algorithm of a set of extended signed Stirling number identities, we show that all four ratios calculated previously by the method of decoupling of zero-norm states among scattering amplitudes in the Gross regime can be extracted from this Kummer function in the RR. Finally, we conjecture and give evidence that the existence of these four Gross regime ratios in the RR persists to subleading orders in the Regge expansion of all high-energy fermionic string scattering amplitudes.
New High Field Magnet for Neutron Scattering at Hahn-Meitner Institute
M Steiner; D A Tennant; P Smeibidl
Abstract. The Berlin Neutron Scattering Center BENSC at the Hahn-Meitner-Institute (HMI) is a user facility for the study of structure and dynamics of condensed matter with neutrons and synchrotron radiation with special emphasis on experiments under extreme conditions. Neutron scattering is uniquely suited to study magnetic properties on a microscopic length scale, because neutrons have comparable wavelengths and, due to their magnetic moment, they interact with the atomic magnetic moments. Magnetic interactions and magnetic phenomena depend on thermodynamic parameters like magnetic field, temperature and pressure. At HMI special efforts are being made to offer outstanding sample environments such as very low temperatures or high magnetic fields or combination of both. For the future a dedicated instrument for neutron scattering at extreme fields is under construction, the Extreme Environment Diffractometer ExED. For this instrument the existing superconducting magnets as well as a future hybrid system can be used. The highest fields, above 30 T will be produced by the planned series-connected hybrid magnet system, designed and constructed in collaboration with the National High Magnetic Field Laboratory, Tallahassee, FL. 1.
Dual-angle, self-calibrating Thomson scattering measurements in RFX-MOD
Giudicotti, L., E-mail: leonardo.giudicotti@unipd.it [Consorzio RFX, Corso Stati Uniti, 4, 35127 Padova (Italy); Department of Industrial Engineering, Padova University, Via Gradenigo 6/a, 35131 Padova (Italy); Pasqualotto, R. [Department of Industrial Engineering, Padova University, Via Gradenigo 6/a, 35131 Padova (Italy); Fassina, A. [Consorzio RFX, Corso Stati Uniti, 4, 35127 Padova (Italy)
2014-11-15T23:59:59.000Z
In the multipoint Thomson scattering (TS) system of the RFX-MOD experiment the signals from a few spatial positions can be observed simultaneously under two different scattering angles. In addition the detection system uses optical multiplexing by signal delays in fiber optic cables of different length so that the two sets of TS signals can be observed by the same polychromator. Owing to the dependence of the TS spectrum on the scattering angle, it was then possible to implement self-calibrating TS measurements in which the electron temperature T{sub e}, the electron density n{sub e} and the relative calibration coefficients of spectral channels sensitivity C{sub i} were simultaneously determined by a suitable analysis of the two sets of TS data collected at the two angles. The analysis has shown that, in spite of the small difference in the spectra obtained at the two angles, reliable values of the relative calibration coefficients can be determined by the analysis of good S/N dual?angle spectra recorded in a few tens of plasma shots. This analysis suggests that in RFX-MOD the calibration of the entire set of TS polychromators by means of the similar, dual-laser (Nd:YAG/Nd:YLF) TS technique, should be feasible.
Neutron scattering measurements at intermediate energies
N. Olsson; J. Blomgren; E. Ramstrom
The study of elastic neutron scattering at intermediate energies is essential for the understanding of the isovector term in the nucleon-nucleus interaction, as well as for the development of macroscopic and microscopic optical potentials at these energies. The techniques used for neutron scattering measurements is presented in this paper, as well as the di culties encountered. The few facilities that have been used are reviewed, and a newly installed setup for such measurements in Uppsala is described. Finally, the normalization problem is speci cally addressed. 1
Fitzpatrick, A.Liam; /Boston U.; Kaplan, Jared; /SLAC
2012-02-14T23:59:59.000Z
We show that suitably regulated multi-trace primary states in large N CFTs behave like 'in' and 'out' scattering states in the flat-space limit of AdS. Their transition matrix elements approach the exact scattering amplitudes for the bulk theory, providing a natural CFT definition of the flat space S-Matrix. We study corrections resulting from the AdS curvature and particle propagation far from the center of AdS, and show that AdS simply provides an IR regulator that disappears in the flat space limit.
Radiation from SU(3) monopole scattering
Patrick Irwin
2000-04-07T23:59:59.000Z
The energy radiated during the scattering of SU(3) monopoles is estimated as a function of their asymptotic velocity v. In a typical scattering process the total energy radiated is of order v^3 as opposed to v^5 for SU(2) monopoles. For charge (1,1) monopoles the dipole radiation produced is estimated for all geodesics on the moduli space. For charge (2,1) monopoles the dipole radiation is estimated for the axially symmetric geodesic. The power radiated appears to diverge in the massless limit. The implications of this for the case of non-Abelian unbroken symmetry are discussed.
Real Compton Scattering via Color Dipoles
B. Z. Kopeliovich; Ivan Schmidt; M. Siddikov
2009-08-24T23:59:59.000Z
We study photoabsorption reaction and real Compton scattering (RCS) within the color dipole model. We rely on a photon wave function derived in the instanton vacuum model, and on the energy dependent phenomenological elastic dipole amplitude. Data for the photoabsorption cross section at high energies agree with our parameter free calculations. We also provide predictions for the differential RCS cross section. Although no data for small angle Compton scattering are available so far, this process can be measured in ultra-peripheral hadronic and nuclear collisions at the LHC.
Alpha resonant scattering for astrophysical reaction studies
Yamaguchi, H.; Kahl, D.; Nakao, T. [Center for Nuclear Study (CNS), University of Tokyo, RIKEN campus, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Wakabayashi, Y.; Kubano, S. [The Institute of Physical and Chemical Research (RIKEN), 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Hashimoto, T. [Research Center for Nuclear Physics (RCNP), Osaka University, 10-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Hayakawa, S. [Istituto Nazionale Fisica Nucleare - Laboratori Nazionali del Sud (INFN-LNS), Via S. Sofia 62, 95125 Catania (Italy); Kawabata, T. [Department of Physics, Kyoto University, Kita-Shirakawa, Kyoto 606-8502 (Japan); Iwasa, N. [Department of Physics, Tohoku University, Aoba, Sendai, Miyagi 980-8578 (Japan); Teranishi, T. [Department of Physics, Kyushu University, 6-10-1 Hakozaki, Fukuoka 812-8581 (Japan); Kwon, Y. K. [Institute for Basic Science, 70, Yuseong-daero 1689-gil, Yuseong-gu, Daejeon 305-811 (Korea, Republic of); Binh, D. N. [30 MeV Cyclotron Center, Tran Hung Dao Hospital, Hoan Kiem District, Hanoi (Viet Nam); Khiem, L. H.; Duy, N. G. [Institute of Physics, Vietnam Academy of Science and Technology, 18 Hong Quoc Viet, Nghia do, Hanoi (Viet Nam)
2014-05-02T23:59:59.000Z
Several alpha-induced astrophysical reactions have been studied at CRIB (CNS Radioactive Ion Beam separator), which is a low-energy RI beam separator at Center for Nuclear Study (CNS) of the University of Tokyo. One of the methods to study them is the ? resonant scattering using the thick-target method in inverse kinematics. Among the recent studies at CRIB, the measurement of {sup 7}Be+? resonant scattering is discussed. Based on the result of the experiment, we evaluated the contributions of high-lying resonances for the {sup 7}Be(?,?) reaction, and proposed a new cluster band in {sup 11}C.
DEEPLY INELASTIC SCATTERING OFF NUCLEI AT RHIC.
VENUGOPALAN, R.
2001-09-14T23:59:59.000Z
In this talk, we discussed the physics case for an eA collider. We emphasized the novel physics that might be studied at small x. The interesting physics at intermediate x's has been discussed elsewhere [3]. Plans for an electron-ion collider include, as a major part of the program, the possibility of doing polarized electron-polarized proton/light ion scattering. A discussion of the combined case for high energy electron nucleus and polarized electron-polarized proton scattering will be published separately [66].
[Inelastic electron scattering from surfaces]. [Progress report
Not Available
1993-10-01T23:59:59.000Z
This program uses ab-initio and multiple scattering to study surface dynamical processes; high-resolution electron-energy loss spectroscopy is used in particular. Off-specular excitation cross sections are much larger if electron energies are in the LEED range (50--300 eV). The analyses have been extended to surfaces of ordered alloys. Phonon eigenvectors and eigenfrequencies were used as inputs to electron-energy-loss multiple scattering cross section calculations. Work on low-energy electron and positron holography is mentioned.
Quantum-entanglement-initiated super Raman scattering
Agarwal, G. S. [Department of Physics, Oklahoma State University, Stillwater, Oklahoma 74078 (United States)
2011-02-15T23:59:59.000Z
It has now been possible to prepare a chain of ions in an entangled state and thus the question arises: How will the optical properties of a chain of entangled ions differ from say a chain of independent particles? We investigate nonlinear optical processes in such chains. Since light scattering is quite a versatile technique to probe matter, we explicitly demonstrate the possibility of entanglement-produced super Raman scattering. Our results suggest the possibility of similar enhancement factors in other nonlinear processes like four-wave mixing.
Quantum Electric Field Fluctuations and Potential Scattering
Huang, Haiyun
2015-01-01T23:59:59.000Z
Some physical effects of time averaged quantum electric field fluctuations are discussed. The one loop radiative correction to potential scattering are approximately derived from simple arguments which invoke vacuum electric field fluctuations. For both above barrier scattering and quantum tunneling, this effect increases the transmission probability. It is argued that the shape of the potential determines a sampling function for the time averaging of the quantum electric field operator. We also suggest that there is a nonperturbative enhancement of the transmission probability which can be inferred from the probability distribution for time averaged electric field fluctuations.
Circular polarization memory in polydisperse scattering media
Macdonald, Callum M; Meglinski, Igor
2015-01-01T23:59:59.000Z
We investigate the survival of circularly polarized light in random scattering media. The surprising persistence of this form of polarization has a known dependence on the size and refractive index of scattering particles, however a general description regarding polydisperse media is lacking. Through analysis of Mie theory, we present a means of calculating the magnitude of circular polarization memory in complex media, with total generality in the distribution of particle sizes and refractive indices. Quantification of this memory effect enables an alternate pathway towards recovering particle size distribution, based on measurements of diffusing circularly polarized light.
Geometric phases in a scattering process
H. D. Liu; X. X. Yi
2011-03-19T23:59:59.000Z
The study of geometric phase in quantum mechanics has so far be confined to discrete (or continuous) spectra and trace preserving evolutions. Consider only the transmission channel, a scattering process with internal degrees of freedom is neither a discrete spectrum problem nor a trace preserving process. We explore the geometric phase in a scattering process taking only the transmission process into account. We find that the geometric phase can be calculated by the some method as in an unitary evolution. The interference visibility depends on the transmission amplitude. The dependence of the geometric phase on the barrier strength and the spin-spin coupling constant is also presented and discussed.
Persistence-Length Renormalization of Polymers in a Crowded Environment of Hard Disks
Sebastian Schöbl; Sebastian Sturm; Wolfhard Janke; Klaus Kroy
2014-10-22T23:59:59.000Z
The most conspicuous property of a semiflexible polymer is its persistence length, defined as the decay length of tangent correlations along its contour. Using an efficient stochastic growth algorithm to sample polymers embedded in a quenched two-dimensional hard-disk fluid, we find apparent wormlike chain statistics with a renormalized persistence length. We identify a universal form of the disorder renormalization that suggests itself as a quantitative measure of molecular crowding.
Perturbation hydrogen-atom spectrum in deformed space with minimal length
M. M. Stetsko; V. M. Tkachuk
2006-03-06T23:59:59.000Z
We study energy spectrum for hydrogen atom with deformed Heisenberg algebra leading to minimal length. We develop correct perturbation theory free of divergences. It gives a possibility to calculate analytically in the 3D case the corrections to $s$-levels of hydrogen atom caused by the minimal length. Comparing our result with experimental data from precision hydrogen spectroscopy an upper bound for the minimal length is obtained.
Simulation of a D-T Neutron Source for Neutron Scattering Experiments
Lou, T.P.; Ludewigt, B.A.; Vujic, J.L.; Leung, K.-N.
2003-01-01T23:59:59.000Z
T Neutron Source for Neutron Scattering Experiments T.P. Louor cold neutrons for neutron scattering experiments. Thisto simulate a neutron scattering setup and to estimate
Speliotopoulos, A. D.
2010-01-01T23:59:59.000Z
z RESEARCH ARTICLE Dark energy and extending the geodesicof motion using the Dark Energy length scale was proposed.observations. Keywords Dark energy · Galactic density pro?le
Time and length scales within a fire and implications for numerical simulation
TIESZEN,SHELDON R.
2000-02-02T23:59:59.000Z
A partial non-dimensionalization of the Navier-Stokes equations is used to obtain order of magnitude estimates of the rate-controlling transport processes in the reacting portion of a fire plume as a function of length scale. Over continuum length scales, buoyant times scales vary as the square root of the length scale; advection time scales vary as the length scale, and diffusion time scales vary as the square of the length scale. Due to the variation with length scale, each process is dominant over a given range. The relationship of buoyancy and baroclinc vorticity generation is highlighted. For numerical simulation, first principles solution for fire problems is not possible with foreseeable computational hardware in the near future. Filtered transport equations with subgrid modeling will be required as two to three decades of length scale are captured by solution of discretized conservation equations. By whatever filtering process one employs, one must have humble expectations for the accuracy obtainable by numerical simulation for practical fire problems that contain important multi-physics/multi-length-scale coupling with up to 10 orders of magnitude in length scale.
amplified-fragment length polymorphism: Topics by E-print Network
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
NOTE Shannon L. Datwyler,1,2 Environmental Sciences and Ecology Websites Summary: in Hemp and Marijuana (Cannabis sativa L.) According to Amplified Fragment Length...
Causality bounds for neutron-proton scattering
Serdar Elhatisari; Dean Lee
2012-07-25T23:59:59.000Z
We consider the constraints of causality and unitarity for the low-energy interactions of protons and neutrons. We derive a general theorem that non-vanishing partial-wave mixing cannot be reproduced with zero-range interactions without violating causality or unitarity. We define and calculate interaction length scales which we call the causal range and the Cauchy-Schwarz range for all spin channels up to J = 3. For some channels we find that these length scales are as large as 5 fm. We investigate the origin of these large lengths and discuss their significance for the choice of momentum cutoff scales in effective field theory and universality in many-body Fermi systems.
METHODOLOGY. TIME DISTRIBUTION OF MOSSBAUER SCATTERED RADIATION
Paris-Sud XI, Université de
METHODOLOGY. TIME DISTRIBUTION OF MOSSBAUER SCATTERED RADIATION H. DROST, K. PALOW and G. WEYER distribution en temps du rayonnement reemis par un absorbant Mossbauer. Des effets d'interference dus a l la reponse de 1'absorbant. Les mesures ont et6 realisees avec le rayonnement Mossbauer a 14.4 keV du
Scattering theory of electrical Markus Bttiker
Paris-Sud 11, Université de
symmetry H-invariant if momenta and magnetic field are reversed 13 but is an even function incident current density density of states independent of material !! 6 Landauer formula #12;Drift state scattering matrix current conservation S is a unitray matrix In the absence of a magnetic field
RADIATION FIELDS, SCATTERING AND ... - Purdue University
2006-12-26T23:59:59.000Z
We define the forward and backward radiation fields on an asymptotically hyperbolic man- ... There is a history of interest in scattering theory for this class of manifolds, ...... and lower order terms as in in (4.10). ...... We first re-examine (
Compton scattering and polarizabilities of the nucleon
M. Gorchtein; D. Drechsel; B. Pasquini; M. Vanderhaeghen
1999-11-19T23:59:59.000Z
Fixed-$t$ subtracted dispersion relations are presented for Compton scattering off the nucleon at energies $E_\\gamma \\leq 500$ MeV, as a formalism to extract the nucleon polarizabilities from the data with a minimum of model dependence. The scalar polarizabilities difference $\\alpha - \\beta$ and the backward spin polarizability $\\gamma_\\pi$ enter directly as fit parameters in this formalism.
Some Aspects of Deeply Virtual Compton Scattering
Elena Kuchina
2004-05-10T23:59:59.000Z
We consider different aspects of the virtual Compton amplitude in QCD on two examples: small-x physics accessible in the Regge regime and twist-3 approximation in the description of DVCS through the general parton distributions. Using this model, we give an estimate for the cross section of deeply virtual Compton scattering for the kinematics of CEBAF at Jefferson Lab.
Colour dipoles and deeply virtual Compton scattering
R. Sandapen
2002-07-01T23:59:59.000Z
I report on an analysis of Deeply Virtual Compton Scattering (DVCS) within the dipole model, done in collaboration with M. McDermott and G. Shaw. The two models considered here are distinct in their structure and implications. They both agree with the available cross-section data on DVCS from HERA. Predictions for various asymmetries are also given.
Pion Compton Scattering in Perturbative QCD
E. Maina; R. Torasso
1993-09-23T23:59:59.000Z
Pion Compton scattering is studied in perturbative QCD for real and space--like initial photons. Different methods for the convolution of the hard amplitude with the pion wave--functions, which have in the past led to conflicting results, are compared.
The Kinematic Algebras from the Scattering Equations
Monteiro, Ricardo
2013-01-01T23:59:59.000Z
We study kinematic algebras associated to the recently proposed scattering equations, which arise in the description of the scattering of massless particles. In particular, we describe the role that these algebras play in the BCJ duality between colour and kinematics in gauge theory, and its relation to gravity. We find that the scattering equations are a consistency condition for a self-dual-type vertex which is associated to each solution of those equations. We also identify an extension of the anti-self-dual vertex, such that the two vertices are not conjugate in general. Both vertices correspond to the structure constants of Lie algebras. We give a prescription for the use of the generators of these Lie algebras in trivalent graphs that leads to a natural set of BCJ numerators. In particular, we write BCJ numerators for each contribution to the amplitude associated to a solution of the scattering equations. This leads to a decomposition of the determinant of a certain kinematic matrix, which appears natur...
Geometry of Scattering at Planckian Energies
Renata Kallosh
1991-11-05T23:59:59.000Z
We present an alternative derivation and geometrical formulation of Verlinde topological field theory, which may describe scattering at center of mass energies comparable or larger than the Planck energy. A consistent trunckation of 3+1 dimensional Einstein action is performed using the standard geometrical objects, like tetrads and spin connections. The resulting topological invariant is given in terms of differential forms.
A modified variational approach to scattering
Parnell, Gregory Elliott
1978-01-01T23:59:59.000Z
, 11'-99 -C. ', i493 Q I; 49". , 0 ;Q594 -0. 105&34 1CSoc TABLE III. phase shiftstl for single'. p-wave electron scattering from H calculated by the modi- fied variational method (with second basis function peak at 1/2). H is the number of basis...
Fiber optic probe for light scattering measurements
Nave, Stanley E. (Evans, GA); Livingston, Ronald R. (Aiken, SC); Prather, William S. (Augusta, GA)
1995-01-01T23:59:59.000Z
A fiber optic probe and a method for using the probe for light scattering analyses of a sample. The probe includes a probe body with an inlet for admitting a sample into an interior sample chamber, a first optical fiber for transmitting light from a source into the chamber, and a second optical fiber for transmitting light to a detector such as a spectrophotometer. The interior surface of the probe carries a coating that substantially prevents non-scattered light from reaching the second fiber. The probe is placed in a region where the presence and concentration of an analyte of interest are to be detected, and a sample is admitted into the chamber. Exciting light is transmitted into the sample chamber by the first fiber, where the light interacts with the sample to produce Raman-scattered light. At least some of the Raman-scattered light is received by the second fiber and transmitted to the detector for analysis. Two Raman spectra are measured, at different pressures. The first spectrum is subtracted from the second to remove background effects, and the resulting sample Raman spectrum is compared to a set of stored library spectra to determine the presence and concentration of the analyte.
Fiber optic probe for light scattering measurements
Nave, S.E.; Livingston, R.R.; Prather, W.S.
1993-01-01T23:59:59.000Z
This invention is comprised of a fiber optic probe and a method for using the probe for light scattering analyses of a sample. The probe includes a probe body with an inlet for admitting a sample into an interior sample chamber, a first optical fiber for transmitting light from a source into the chamber, and a second optical fiber for transmitting light to a detector such as a spectrophotometer. The interior surface of the probe carries a coating that substantially prevents non-scattered light from reaching the second fiber. The probe is placed in a region where the presence and concentration of an analyte of interest are to be detected, and a sample is admitted into the chamber. Exciting light is transmitted into the sample chamber by the first fiber, where the light interacts with the sample to produce Raman-scattered light. At least some of the Raman- scattered light is received by the second fiber and transmitted to the detector for analysis. Two Raman spectra are measured, at different pressures. The first spectrum is subtracted from the second to remove background effects, and the resulting sample Raman spectrum is compared to a set of stored library spectra to determine the presence and concentration of the analyte.
Rutherford Scattering MIT Department of Physics
Seager, Sara
of the scattering angle, the alpha particle energy, and the nuclear charge. You will then measure the intensity atomic weight, but to its atomic number, determined by its position in the periodic table. Since the mass in any atom is associated with the positive charge. The central problem was to figure out how
SCATTERING BY CRACKS BENEATH FLUIDSOLID INTERFACES
Craster, Richard
parameters relevant for watermetal and waterrock combinations are taken and far field scattering patterns the fluid. For line source excitation surface waves are generated that impinge upon defects near the surface with distance along the interface from its source of excitation. The light fluid loading limit is important f
Photophoresis and the scattering of electromagnetic radiation
Ipser, J.R.
1985-09-01T23:59:59.000Z
Electron-microscope photographs of soot lend support to the picture in which a soot particle is modeled as a collection of chains of small carbon spheres. The soot particle itself is typically considerably larger than the small carbon spheres making up the chains. Thus the soot particles might have a size approx.0.1 - 1 ..mu..m while the small carbon spheres might have a size approx.0.03 ..mu..m in typical situations. Further, measurements of the density of soot yield values much less than that of normal carbon, indicating that an individual soot particle has a rather small filling factor, i.e., the fraction of the volume of the particle tht is occupied by chains. If a soot particle is taken to be a sphere partially filled with carbon chains, what are its scattering and absorption properties. Several workers have adopted the view that the net scattering and absorption properties can be determined simply by summing the cross-sections for the individual small carbon spheres. We feel that such a procedure cannot be valid in general because it neglects coherence effects among the various randomly located scatterers within the soot particle. It appears that in a first rough approximation the scattering and absorption properties of soot can be determined by estimating the effective dielectric constant of a soot sphere.
Anovitz, Lawrence {Larry} M [ORNL; Cole, David [Ohio State University; Rother, Gernot [ORNL; Allard Jr, Lawrence Frederick [ORNL; Jackson, Andrew [NIST Center for Neutron Research (NCRN), Gaithersburg, MD; Littrell, Ken [ORNL
2013-01-01T23:59:59.000Z
Small- and Ultra-Small Angle Neutron Scattering (SANS and USANS) provide powerful tools for quantitative analysis of porous rocks, yielding bulk statistical information over a wide range of length scales. This study utilized (U)SANS to characterize shallowly buried quartz arenites from the St. Peter Sandstone. Backscattered electron imaging was also used to extend the data to larger scales. These samples contain significant volumes of large-scale porosity, modified by quartz overgrowths, and neutron scattering results show significant sub-micron porosity. While previous scattering data from sandstones suggest scattering is dominated by surface fractal behavior over many orders of magnitude, careful analysis of our data shows both fractal and pseudo-fractal behavior. The scattering curves are composed of subtle steps, modeled as polydispersed assemblages of pores with log-normal distributions. However, in some samples an additional surface-fractal overprint is present, while in others there is no such structure, and scattering can be explained by summation of non-fractal structures. Combined with our work on other rock-types, these data suggest that microporosity is more prevalent, and may play a much more important role than previously thought in fluid/rock interactions.
Inelastic neutron scattering in valence fluctuation compounds
Jon M Lawrence
2011-02-15T23:59:59.000Z
The valence fluctuation compounds are rare earth intermetallics where hybridization of the nearly-localized 4f electrons with the conduction electrons leads to incorporation of the 4f's into the itinerant states. This hybridization slows down the conduction electrons and hence gives them a heavy effective mass, justifying application of the term 'heavy Fermion' (HF) to these materials. During the project period, we grew large single crystals of several such compounds and measured their properties using both standard thermodynamic probes and state-of-the-art inelastic neutron scattering. We obtained three main results. For the intermediate valence compounds CePd{sub 3} and YbAl{sub 3}, we showed that the scattering of neutrons by the fluctuations of the 4f magnetic moment does not have the momentum dependence expected for the itinerant heavy mass state; rather, the scattering is more typical of a localized spin fluctuation. We believe that incoherent scattering localizes the excitation. For the heavy Fermion compound Ce(Ni{sub 0.935}Pd{sub 0.065}){sub 2}Ge{sub 2}, which sits at a T = 0 critical point for transformation into an antiferromagnetic (AF) phase, we showed that the scattering from the AF fluctuations does not exhibit any of the divergences that are expected at a phase transition. We speculate that alloy disorder profoundly suppresses the growth of the fluctuating AF regions, leading to short range clusters rather than regions of infinite size. Finally, we explored the applicability of key concepts used to describe the behavior of rare earth heavy Fermions to uranium based HF compounds where the 5f electrons are itinerant as opposed to localized. We found that scaling laws relating the spin fluctuation energy measured in neutron scattering to the low temperature specific heat and susceptibility are valid for the uranium compounds, once corrections are made for AF fluctuations; however, the degeneracy of the high temperature moment is smaller than expected for rare-earth-like Hund's rule behavior, essentially because the orbital moment is suppressed for itinerant 5f electrons. We also found that the standard local-moment-based theory of the temperature dependence of the specific heat, susceptibility and neutron scattering fails badly for URu{sub 2}Zn{sub 20} and UCo{sub 2}Zn{sub 20}, even though the theory is phenomenally successful for the closely related rare earth compound YbFe{sub 2}Zn{sub 20}. Both these results highlight the distinction between the itineracy of the 5f's and the localization of the 4f's. It is our hope that these results are sufficiently significant as to stimulate deeper investigation of these compounds.
Off-Shell Scattering Amplitudes for WW Scattering and the Role of the Photon Pole
J. Bartels; F. Schwennsen
2005-06-06T23:59:59.000Z
We derive analytic expressions for high energy $2 \\to 2$ off-shell scattering amplitudes of weak vector bosons. They are obtained from six fermion final states in processes of the type $e^+ e^- \\to \\bar\
Inverse scattering J-matrix approach to nucleon-nucleus scattering and the shell model
A. M. Shirokov; A. I. Mazur; J. P. Vary; E. A. Mazur
2008-10-06T23:59:59.000Z
The $J$-matrix inverse scattering approach can be used as an alternative to a conventional $R$-matrix in analyzing scattering phase shifts and extracting resonance energies and widths from experimental data. A great advantage of the $J$-matrix is that it provides eigenstates directly related to the ones obtained in the shell model in a given model space and with a given value of the oscillator spacing $\\hbar\\Omega$. This relationship is of a particular interest in the cases when a many-body system does not have a resonant state or the resonance is broad and its energy can differ significantly from the shell model eigenstate. We discuss the $J$-matrix inverse scattering technique, extend it for the case of charged colliding particles and apply it to the analysis of $n\\alpha$ and $p\\alpha$ scattering. The results are compared with the No-core Shell Model calculations of $^5$He and $^5$Li.
Scattered neutron tomography based on a neutron transport problem
Scipolo, Vittorio
2005-11-01T23:59:59.000Z
scattering objects because it does not adequately account for the scattering component of the neutron beam intensity exiting the sample. We proposed a new method of computed tomography which employs an inverse problem analysis of both the transmitted...
A study of neutron-deuteron scattering in configuration space
V. M. Suslov; M. A. Braun; I. Filikhin; B. Vlahovic
2006-10-09T23:59:59.000Z
A new computational method for solving the configuration-space Faddeev equations for the breakup scattering problem has been applied to nd scattering both below and above the two-body threshold.
Wavelet Analysis of Two Dimensional Quantum Scattering A thesis presented
Heller, Eric
Wavelet Analysis of Two Dimensional Quantum Scattering A thesis presented by Jonathan Dillwyn the local nature of the scattering. We present an alternative discretization based on the discrete wavelet
Anisotropic light scattering of individual sickle red blood cells
Kim, Youngchan
We present the anisotropic light scattering of individual red blood cells (RBCs) from a patient with sickle cell disease (SCD). To measure light scattering spectra along two independent axes of elongated-shaped sickle RBCs ...
Scattered neutron tomography based on a neutron transport problem
Scipolo, Vittorio
2005-11-01T23:59:59.000Z
scattering objects because it does not adequately account for the scattering component of the neutron beam intensity exiting the sample. We proposed a new method of computed tomography which employs an inverse problem analysis of both the transmitted...
The I=2 ?? S-wave Scattering Phase Shift from Lattice QCD
Beane, S R; Detmold, W; Lin, H W; Luu, T C; Orginos, K; Parreno, A; Savage, M J; Torok, A; Walker-Loud, A
2012-02-16T23:59:59.000Z
The ?^{+}?^{+} s-wave scattering phase-shift is determined below the inelastic threshold using Lattice QCD. Calculations were performed at a pion mass of m_{?} ? 390 MeV with an anisotropic n_{f} = 2+1 clover fermion discretization in four lattice volumes, with spatial extent L ? 2.0, 2.5, 3.0 and 3.9 fm, and with a lattice spacing of b_{s} ? 0.123 fm in the spatial direction and b_{t} b_{s}/3.5 in the time direction. The phase-shift is determined from the energy-eigenvalues of ?^{+}?^{+} systems with both zero and non-zero total momentum in the lattice volume using Luscher's method. Our calculations are precise enough to allow for a determination of the threshold scattering parameters, the scattering length a, the effective range r, and the shape-parameter P, in this channel and to examine the prediction of two-flavor chiral perturbation theory: m_{?}^{2} a r = 3+O(m_{?}^{2}/?_{?}^{2}). Chiral perturbation theory is used, with the Lattice QCD results as input, to predict the scattering phase-shift (and threshold parameters) at the physical pion mass. Our results are consistent with determinations from the Roy equations and with the existing experimental phase shift data.
Raman scattering from defects in GaN: The question of vibrational or electronic scattering mechanism
Nabben, Reinhard
Raman scattering from defects in GaN: The question of vibrational or electronic scattering on defects in GaN, which appear in the Raman spectra as sharp and intense lines in the low-energy region from into the GaN material. S0163-1829 98 00344-0 I. INTRODUCTION Low-temperature Raman spectra of GaN films grown
McCray, John (Colorado School of Mines); Navarre-Sitchler, Alexis (Colorado School of Mines); Mouzakis, Katherine (Colorado School of Mines); Heath, Jason E.; Dewers, Thomas A.; Rother, Gernot (Oak Ridge National Laboratory)
2010-11-01T23:59:59.000Z
Geological carbon sequestration relies on the principle that CO{sub 2} injected deep into the subsurface is unable to leak to the atmosphere. Structural trapping by a relatively impermeable caprock (often mudstone such as a shale) is the main trapping mechanism that is currently relied on for the first hundreds of years. Many of the pores of the caprock are of micrometer to nanometer scale. However, the distribution, geometry and volume of porosity at these scales are poorly characterized. Differences in pore shape and size can cause variation in capillary properties and fluid transport resulting in fluid pathways with different capillary entry pressures in the same sample. Prediction of pore network properties for distinct geologic environments would result in significant advancement in our ability to model subsurface fluid flow. Specifically, prediction of fluid flow through caprocks of geologic CO{sub 2} sequestration reservoirs is a critical step in evaluating the risk of leakage to overlying aquifers. The micro- and nanoporosity was analyzed in four mudstones using small angle neutron scattering (SANS). These mudstones are caprocks of formations that are currently under study or being used for carbon sequestration projects and include the Marine Tuscaloosa Group, the Lower Tuscaloosa Group, the upper and lower shale members of the Kirtland Formation, and the Pennsylvanian Gothic shale. Total organic carbon varies from <0.3% to 4% by weight. Expandable clay contents range from 10% to {approx}40% in the Gothic shale and Kirtland Formation, respectively. Neutrons effectively scatter from interfaces between materials with differing scattering length density (i.e. minerals and pores). The intensity of scattered neutrons, I(Q), where Q is the scattering vector, gives information about the volume of pores and their arrangement in the sample. The slope of the scattering data when plotted as log I(Q) vs. log Q provides information about the fractality or geometry of the pore network. Results from this study, combined with high-resolution TEM imaging, provide insight into the differences in volume and geometry of porosity between these various mudstones.
Ying Chen; Ming Gong; Yu-Hong Lei; Ning Li; Jian Liang; Chuan Liu; Jin-Long Liu; Yong-Fu Liu; Yu-Bin Liu; Zhaofeng Liu; Jian-Ping Ma; Zhan-Lin Wang; Jian-Bo Zhang
2015-03-09T23:59:59.000Z
In this paper, low-energy scattering of the $(D^{*}\\bar{D}^{*})^\\pm$ meson system is studied within L\\"uscher's finite-size formalism using $N_{f}=2$ twisted mass gauge field configurations. With three different pion mass values, the $s$-wave threshold scattering parameters, namely the scattering length $a_0$ and the effective range $r_0$, are extracted in $J^P=1^+$ channel. Our results indicate that, in this particular channel, the interaction between the two vector charmed mesons is weakly repulsive in nature hence do not support the possibility of a shallow bound state for the two mesons, at least for the pion mass values being studied. This study provides some useful information on the nature of the newly discovered resonance-like structure $Z_c(4025)$ observed in various experiments.
2D Static Light Scattering for Dairy Based Applications
2D Static Light Scattering for Dairy Based Applications Jacob Lercke Skytte Kongens Lyngby 2014 Ph information on the microstructure. The second paper makes a direction comparison between the light scattering a recently introduced light scattering tech- nique. The system setup of the technique is highly flexible
Fractal dimension in dissipative chaotic scattering Jess M. Seoane,1,
Rey Juan Carlos, Universidad
Fractal dimension in dissipative chaotic scattering JesÃºs M. Seoane,1, * Miguel A. F. SanjuÃ¡n,1 on chaotic scattering is relevant to situations of physical interest. We inves- tigate how the fractal is thus the fractal dimension of the set of singularities. For nonhyperbolic scattering, it has been known
Small Angle X-ray Scattering (SAXS) Laboratory Learning Experiences
Meagher, Mary
.A. & Svergun D.I. (1987). Structure Analysis by Small-Angle X-Ray and Neutron Scattering. NY: Plenum PressSmall Angle X-ray Scattering (SAXS) Laboratory Learning Experiences o - Use of small angle X-ray scattering instrumentation o - Programs that you will use SAXS (BRUKER AXS) PRIMUS (Konarev, Volkov, Koch
Diffractive and deeply virtual Compton scattering in holographic QCD
Alexander Stoffers; Ismail Zahed
2012-10-13T23:59:59.000Z
We further analyze the holographic dipole-dipole scattering amplitude developed in arXiv:1202.0831, 1205.3223. Gribov diffusion at strong coupling yields the scattering amplitude in a confining background. We compare the holographic result for the differential cross section to proton-proton and deeply virtual Compton scattering data.
Scattering Summary/Review Spring 2009 Compton Lecture Series
Scattering Summary/Review Spring 2009 Compton Lecture Series: From Quantum Mechanics to the String distributed range of impact parameters. This beam is scattered into a distribution of angles. The number of particles scattered into a given angular range depends on the shape of the potential hill. This is what
INTRA BEAM SCATTERING IN LINEAR ACCELERATORS, ESPECIALLY ERLS
Hoffstaetter, Georg
are called Touschek particles. Touschek scattering in a linear acceler- ator is interesting because. In this paper we describe two ways of simu- lating particle loss by these scattering affects, both imple- mented complete propagation of scattered particle. For the example of the ERL x-ray facility that Cornell plans
Disorder scattering in graphene nanoribbons F. Libisch1
Florian, Libisch
Disorder scattering in graphene nanoribbons F. Libisch1 , S. Rotter1 , J. Burgd¨orfer1 1 Institute investigate transport through bulk-disordered graphene nanoribbons and nanoconstrictions. Employing a modular transforming the scattered wave we disentangle inter-valley scattering between the two Dirac cones of graphene
Raman Scattering through a quantum-critical point
Freericks, Jim
spectral weight with underdoping. J. G. Naeini et al., PRB 1999 J. K. Freericks, Georgetown University, Raman scattering talk, 2001 M. Opel et al., PRB 2000 //( >> 0) k() qp scattering talk, 2001 #12;Experimental data for Kondo insulators · Nyhus et al, PRB 95 Raman scattering on Fe
Automatically Identifying Scatter in Fluorescence Data using Robust Techniques.
(PARAFAC) to fluorescence excitation-emission data (EEM). The scatter does not contain any relevant handle first and second order Rayleigh scatter as well as Raman scatter in various types of EEM data of such a measurement is an excitation-emission matrix (EEM). When several samples (I) are mea- sured the data can
Neutron Scattering Society of America Purpose and New Initiatives
Pennycook, Steve
1 Neutron Scattering Society of America (NSSA) Purpose and New Initiatives www.neutronscattering.org SNS/ANL School on Neutron and X-Ray Scattering June 2010 Visit us now on Facebook #12;2 What and provide a focal point for the neutron scattering community in the USA To identify the needs
Fourteenth National School on Neutron and X-ray Scattering
Pennycook, Steve
Fourteenth National School on Neutron and X-ray Scattering August 12 - 25, 2012 at Argonne National of the National School on Neutron and X-ray Scattering is to educate graduate students on the utilization of major Ridge National Laboratory's Neutron Scattering Science Division. Scientific Directors: Jonathan C. Lang
The Neutron Scattering Society www.neutronscattering.org
Chen, Sow-Hsin
The Neutron Scattering Society of America www.neutronscattering.org Press Release, February 4, 2008 The Neutron Scattering Society of America is pleased to announce the 2008 recipients of its 3 major prizes. The Neutron Scattering Society of America (NSSA) established the Clifford G. Shull Prize in Neutron Science
Nitrogen Contamination in Elastic Neutron Scattering Songxue Chi,ab
Lynn, Jeffrey W.
Nitrogen Contamination in Elastic Neutron Scattering Songxue Chi,ab Jeffrey W. Lynn,a* Ying Chen a neutron scattering measurement is a contribution to the background, especially in inelastic measurements of having N2 in the sample environment system during elastic neutron scattering measurements on a single
Tenth National School on Neutron and X-ray Scattering
Pennycook, Steve
Tenth National School on Neutron and X-ray Scattering September 24 - October 11, 2008 at Argonne of the National School on Neutron and X-ray Scattering is to educate graduate students on the utilization of major National Laboratory's Neutron Scattering Science Division. Scientific Directors: Jonathan C. Lang, Suzanne
Neutron Scattering Society of America Purpose and New Initiatives
1 Neutron Scattering Society of America (NSSA) Purpose and New Initiatives www.neutronscattering.org SNS/ANL School on Neutron and X-Ray Scattering June 2011 Visit us now on Facebook #12;2 What and provide a focal point for the neutron scattering community in the USA To identify the needs
National School on Neutron and X-ray Scattering
15th National School on Neutron and X-ray Scattering August 10 - 24, 2013 at Argonne National of the National School on Neutron and X-ray Scattering is to educate graduate students on the utilization of major Ridge National Laboratory's Neutron Scattering Science Division. Scientific Directors: Jonathan C. Lang
TUTORIAL / ARTICLE DIDACTIQUE Neutron scattering study of the classical
Ryan, Dominic
TUTORIAL / ARTICLE DIDACTIQUE Neutron scattering study of the classical antiferromagnet MnF2: a perfect hands-on neutron scattering teaching course1 Z. Yamani, Z. Tun, and D.H. Ryan Abstract: We present of neutron scattering concepts. The nature of antiferromagnetism and the magnetic Hamiltonian in this classi
Thirteenth National School on Neutron and X-ray Scattering
Thirteenth National School on Neutron and X-ray Scattering June 11 June 25, 2011 at Argonne of the National School on Neutron and X-ray Scattering is to educate graduate students on the utilization of major National Laboratory's Neutron Scattering Science Division. Scientific Directors: Jonathan C. Lang, Suzanne
LANSCE School on Neutron Scattering: Materials at the Mesoscale
1 11th LANSCE School on Neutron Scattering: Materials at the Mesoscale Lujan Center Los Alamos. Please name the applicant for admission to the 11th LANSCE School on Neutron Scattering: Last, First LANSCE School on Neutron Scattering including: drive and motivation, ability to work with others
The Neutron Scattering Society www.neutronscattering.org
Homes, Christopher C.
The Neutron Scattering Society of America www.neutronscattering.org Press Release February 11, 2008 The Neutron Scattering Society of America is pleased to announce the election as Fellows of the Society of in application of neutron scattering to studies of surfaces and crystal field excitations as well as his
Sixteenth National School on Neutron and X-ray Scattering
Pennycook, Steve
Sixteenth National School on Neutron and X-ray Scattering June 14-28, 2014 at Argonne National of the National School on Neutron and X-ray Scattering is to educate graduate students on the utilization of major's Neutron Scattering Science Division. Scientific Directors: Suzanne G.E. te Velthuis, Esen Ercan Alp
Neutron scattering in magnetic fields (*) W. C. Koehler
Boyer, Edmond
691 Neutron scattering in magnetic fields (*) W. C. Koehler Solid State Division, Oak Ridge. Abstract 2014 The use of magnetic fields in neutron scattering experimentation is reviewed briefly. Two of the scattering sample ; in the second the field acts on the neutron itself. Several examples are discussed
Twelfth National School on Neutron and X-ray Scattering
Pennycook, Steve
Twelfth National School on Neutron and X-ray Scattering June 12 June 26, 2010 at Argonne National of the National School on Neutron and X-ray Scattering is to educate graduate students on the utilization of major National Laboratory's Neutron Scattering Science Division. Scientific Directors: Jonathan C. Lang, Suzanne
National School on Neutron and X-ray Scattering
Pennycook, Steve
National School on Neutron and X-ray Scattering May 30 June 13, 2009 at Argonne National of the National School on Neutron and X-ray Scattering is to educate graduate students on the utilization of major National Laboratory's Neutron Scattering Science Division. Scientific Directors: Jonathan C. Lang, Suzanne
A Java-based Science Portal for Neutron Scattering Experiments
Vazhkudai, Sudharshan
A Java-based Science Portal for Neutron Scattering Experiments Sudharshan S. Vazhkudai James A scattering facility recently commissioned by the US Department of Energy (DOE). The neutron beam produced (SNS) [14] is a large-scale leading- edge neutron scattering facility that hopes to fundamen- tally
ORNL Neutron Scattering School May 30 -June 5, 2009
Pennycook, Steve
ORNL Neutron Scattering School May 30 - June 5, 2009 Oak Ridge National Laboratory Oak Ridge, 2009, for the first week of the Neutron Xray Scattering School. Please be certain to bring photo for Neutron Scattering Users · Radiological Worker Training for HFIR and SNS Users In addition
ccsd00002835, Light scattering from cold rolled aluminum surfaces
ccsd00002835, version 2 14 Sep 2004 Light scattering from cold rolled aluminum surfaces Damien Camille Soula , 31400 Toulouse, France We present experimental light scattering measurements from aluminum scattering measurements of an s-polarized electromagnetic wave (632.8 nanometers) from a rough aluminum alloy
A Statistical Study of the Relationship between the Solar Cycle Length and TreeRing Index
A Statistical Study of the Relationship between the Solar Cycle Length and TreeÂRing Index Values, 450052, China 2 Armagh Observatory, College Hill, Armagh BT61 9DG, N. Ireland Abstract We have determined of the solar cycle length on climate with a reasonable degree of confidence. We find that the data confirm
EFFECTS OF SAMPLE SIZE ON CHARACTERIZATION OF WOOD-PARTICLE LENGTH DISTRIBUTION
EFFECTS OF SAMPLE SIZE ON CHARACTERIZATION OF WOOD-PARTICLE LENGTH DISTRIBUTION Quang V. Cao of sample size on fitting length distribution of wood particles used for manufacturing wood-based composites moments and the ability of the sample distributions to characterize the population represented
On Loewy lengths of blocks (joint work with S. Koshitani and B. Klshammer)
On Loewy lengths of blocks (joint work with S. Koshitani and B. KÃ¼lshammer) Benjamin Sambale, FSU Jena March 26, 2013 Benjamin Sambale On Loewy lengths of blocks #12;Notation G Â finite group p Â prime number F Â algebraically closed field of characteristic p B Â block of FG J(B) Â Jacobson radical of B
Length Based Attack and Braid Groups: Cryptanalysis of Anshel-Anshel-Goldfeld Key
Myasnikov, Aleksey
Length Based Attack and Braid Groups: Cryptanalysis of Anshel-Anshel-Goldfeld Key Exchange Protocol of Technology, Hoboken, New Jersey, USA, 07030 {amyasnik,aushakov}@stevens.edu Abstract. The length based attack and Tannenbaum in [9]. Several attempts have been made to implement the attack [6], but none of them had produced
Evaluation of Largemouth Bass Slot Length Limits in South Dakota Waters
IY5~p: SOUTH DAKOTA ----.--) o o ~o Evaluation of Largemouth Bass Slot Length Limits in South Dakota Waters Department of Game, Fish and Parks Wildlife Division Foss Building Pierre. South Dakota 67601.3182 Completion Report No. 93-13 #12;Evaluation of Largemouth Bass Slot Length Limits in South
Variable length pattern coding for power reduction in off-chip data buses
Venkitasubramanian Iyer, Jayakrishnan
2009-05-15T23:59:59.000Z
indicating the index of the match is sent. If a variable length pattern match occurs then the code and unmatched portion of data is sent. We implemented our scheme, Variable Length Pattern Coding (VLPC) for various integer and floating point benchmarks...
Impact of Interconnect Length on BTI and HCI Induced Frequency Degradation
Kim, Chris H.
Impact of Interconnect Length on BTI and HCI Induced Frequency Degradation Xiaofei Wang Pulkit Jain Instability (BTI) and Hot Carrier Injection (HCI) induced frequency degradation on interconnect length has degradation due to BTI decreases monotonically with longer wires because of the shorter effective stress time
VALVE: Variable Length Value Encoder for Off-Chip Data Buses. Dinesh C. Suresh, Banit Agrawal*
Najjar, Walid A.
VALVE: Variable Length Value Encoder for Off-Chip Data Buses. Dinesh C. Suresh, Banit Agrawal (VALVE) technique to reduce the power consumption in the off-chip data buses. While past research has proposed scheme is capable of detecting and encoding variable length bit patterns in the data values. VALVE
Surface Free Energies, Interfacial Tensions and Correlation Lengths of the ABF Models
Pearce, Paul A.
Surface Free Energies, Interfacial Tensions and Correlation Lengths of the ABF Models David L. O. Abstract The surface free energies, interfacial tensions and correlation lengths of the Andrews been established there are various quan- tities of physical interest, such as the surface free energies
Scanning microscopy using a short-focal-length Fresnel zone plate
Scanning microscopy using a short-focal-length Fresnel zone plate Ethan Schonbrun,* Winnie N. Ye demonstrate a form of scanning microscopy using a short-focal-length Fresnel zone plate and a low-NA relay. In this scheme, parallel scanning microscopy using a Fresnel zone-plate array would require only a single spatial
The Distribution of Loop Lengths in Graphical Models for Turbo Decoding
Smyth, Padhraic
1 The Distribution of Loop Lengths in Graphical Models for Turbo Decoding Xianping Ge, David model for a K = 6, N = 12, rate 1=2 turbo code. Abstract| This paper analyzes the distribution of loop lengths in graphical models for turbo decoding. The prop- erties of such loops are of signi#12;cant
TESLA-FEL 2004-01 Silica Aerogel Radiators for Bunch Length
TESLA-FEL 2004-01 Silica Aerogel Radiators for Bunch Length Measurements J. BÂ¨ahr a , V. Djordjadze aerogel are used to measure the electron bunch length at the photo injector test facility at DESY Zeuthen by the usage of aerogel is calculated analytically and Monte Carlo simulations are performed. It is shown
Video Description Length Guided Constant Quality Video Coding with Bitrate Constraint
Tomkins, Andrew
Video Description Length Guided Constant Quality Video Coding with Bitrate Constraint Lei Yang propose a new video encoding strategy -- Video description length guided Constant Quality video coding with Bitrate Constraint (V-CQBC), for large scale video transcoding systems of video charing websites
Stewart, G.; Lackner, M.; Haid, L.; Matha, D.; Jonkman, J.; Robertson, A.
2013-07-01T23:59:59.000Z
With the push towards siting wind turbines farther offshore due to higher wind quality and less visibility, floating offshore wind turbines, which can be located in deep water, are becoming an economically attractive option. The International Electrotechnical Commission's (IEC) 61400-3 design standard covers fixed-bottom offshore wind turbines, but there are a number of new research questions that need to be answered to modify these standards so that they are applicable to floating wind turbines. One issue is the appropriate simulation length needed for floating turbines. This paper will discuss the results from a study assessing the impact of simulation length on the ultimate and fatigue loads of the structure, and will address uncertainties associated with changing the simulation length for the analyzed floating platform. Recommendations of required simulation length based on load uncertainty will be made and compared to current simulation length requirements.
Yano, M., E-mail: masao-yano-aa@mail.toyota.co.jp; Manabe, A.; Shoji, T.; Kato, A. [Advanced Material Engineering Division, Toyota Motor Corporation, Susono 410-1193 (Japan); Ono, K. [High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801 (Japan); Harada, M. [Toyota Central R and D Labs, Inc., Aichi 480-1192 (Japan); Kohlbrecher, J. [Laboratory for Neutron Scattering, Paul Scherrer Institut, 5232 Villigen PSI (Switzerland)
2014-05-07T23:59:59.000Z
The magnetic reversal behaviors of single domain sized Nd-Fe-B permanent magnets, with and without isolation between the Nd{sub 2}Fe{sub 14}B grains, was clarified using small-angle neutron scattering (SANS). The SANS patterns obtained arose from changes in the magnetic domains and were analyzed using the Teubner–Stray model, a phenomenological correlation length model, to quantify the periodicity and morphology of the magnetic domains. The results indicated that the magnetic reversal evolved with the magnetic domains that had similar sized grains. The grain isolation enabled us to realize the reversals of single domains.
Inelastic Scatterings of Entangled Mossbauer Gammas
Yao Cheng; Zhongming Wang
2006-10-12T23:59:59.000Z
We report the observation of the temperature-dependent inelastic scattering of three entangled Mossbauer gammas in the time-resolved Mossbauer spectroscopy. Recently, the long-lived E3 Mossbauer transition of rhodium generated by bremsstrahlung irradiation has been reported. Two kinds of X-rays with the fast decay are attributed to the tri-photon effect. They are tri-photon pile-up of rhodium K X-rays and the high-Z impurity K X-rays. Energy of the particular K emission is higher than the sum energy of two Mossbauer gammas. This letter reports new discoveries by cooling down the sample using liquid nitrogen, namely the collective anomalous emission of entangled Mossbauer gammas. The enhancement of inelastic scatterings at low temperature such as rhodium K satellites is attributed to this entanglement.
Inelastic Scatterings of Entangled Mossbauer Gammas
Cheng, Y; Cheng, Yao; Wang, Zhongming
2006-01-01T23:59:59.000Z
We report the observation of the temperature-dependent inelastic scattering of three entangled Mossbauer gammas in the time-resolved Mossbauer spectroscopy. Recently, the long-lived E3 Mossbauer transition of rhodium generated by bremsstrahlung irradiation has been reported. Two kinds of x rays with the fast decay are attributed to the tri-photon effect. They are tri-photon pile-up of rhodium K x rays and the high-Z impurity K x rays. Energy of the particular K emission is greater than the sum energy of two Mossbauer gammas. This letter reports new discoveries by cooling down the sample using liquid nitrogen, namely the collective anomalous emission of entangled Mossbauer gammas. The enhancement of inelastic scatterings at low temperature such as rhodium K satellites is attributed to this entanglement.
Optical theorem and elastic nucleon scattering
Milos V. Lokajicek; Vojtech Kundrat
2009-06-22T23:59:59.000Z
In the theoretical analysis of high-energy elastic nucleon scattering one starts commonly from the description based on the validity of optical theorem, which allows to derive the value of total cross section directly from the experimentally measured t-dependence of elastic differential cross section. It may be shown, however, that this theorem has been derived on the basis of one assumption that might be regarded perhaps as acceptable for long-range (e.g., Coulomb) forces but must be denoted as quite unacceptable for finite-range hadron forces. Consequently, the conclusions leading to the increase of total cross section with energy at higher collision energies must be newly analyzed. The necessity of new analysis concerns also the derivation of elastic scattering t-dependence at very low transverse momenta from measured data.
Multiple Scattering Measurements in the MICE Experiment
Carlisle, T.; Cobb, J.; /Oxford U.; Neuffer, D.; /Fermilab
2012-05-01T23:59:59.000Z
The international Muon Ionization Cooling Experiment (MICE), under construction at RAL, will test a prototype cooling channel for a future Neutrino Factory or Muon Collider. The cooling channel aims to achieve, using liquid hydrogen absorbers, a 10% reduction in transverse emittance. The change in 4D emittance will be determined with an accuracy of 1% by measuring muons individually. Step IV of MICE will make the first precise emittance-reduction measurements of the experiment. Simulation studies using G4MICE, based on GEANT4, find a significant difference in multiple scattering in low Z materials, compared with the standard expression quoted by the Particle Data Group. Direct measurement of multiple scattering using the scintillating-fibre trackers is found to be possible, but requires the measurement resolution to be unfolded from the data.
Scattering theory of topological insulators and superconductors
I. C. Fulga; F. Hassler; A. R. Akhmerov
2013-01-10T23:59:59.000Z
The topological invariant of a topological insulator (or superconductor) is given by the number of symmetry-protected edge states present at the Fermi level. Despite this fact, established expressions for the topological invariant require knowledge of all states below the Fermi energy. Here, we propose a way to calculate the topological invariant employing solely its scattering matrix at the Fermi level without knowledge of the full spectrum. Since the approach based on scattering matrices requires much less information than the Hamiltonian-based approaches (surface versus bulk), it is numerically more efficient. In particular, is better-suited for studying disordered systems. Moreover, it directly connects the topological invariant to transport properties potentially providing a new way to probe topological phases.
Pumping angular momentum by driven chaotic scattering
T. Dittrich; F. L. Dubeibe
2008-04-29T23:59:59.000Z
Chaotic scattering with an internal degree of freedom and the possibility to generate directed transport of angular momentum is studied in a specific model, a magnetic dipole moving in a periodically modulated magnetic field confined to a compact region in space. We show that this system is an irregular scatterer in large parts of its parameter space. If in addition all spatio-temporal symmetries are broken, directed transport of mass as well as angular momentum occurs. The sensitive parameter dependence of the corresponding currents includes frequent sign reversals. Zeros of either quantity entail the exclusive occurrence of the other and thus give rise in particular to angular-momentum separation without mass transport as a classical analogue of spin-polarized currents.
Ab initio alpha-alpha scattering
Serdar Elhatisari; Dean Lee; Gautam Rupak; Evgeny Epelbaum; Hermann Krebs; Timo A. Lähde; Thomas Luu; Ulf-G. Meißner
2015-06-11T23:59:59.000Z
Processes involving alpha particles and alpha-like nuclei comprise a major part of stellar nucleosynthesis and hypothesized mechanisms for thermonuclear supernovae. In an effort towards understanding alpha processes from first principles, we describe in this letter the first ab initio calculation of alpha-alpha scattering. We use lattice effective field theory to describe the low-energy interactions of nucleons and apply a technique called the adiabatic projection method to reduce the eight-body system to an effective two-cluster system. We find good agreement between lattice results and experimental phase shifts for S-wave and D-wave scattering. The computational scaling with particle number suggests that alpha processes involving heavier nuclei are also within reach in the near future.
Ab initio alpha-alpha scattering
Elhatisari, Serdar; Rupak, Gautam; Epelbaum, Evgeny; Krebs, Hermann; Lähde, Timo A; Luu, Thomas; Meißner, Ulf-G
2015-01-01T23:59:59.000Z
Processes involving alpha particles and alpha-like nuclei comprise a major part of stellar nucleosynthesis and hypothesized mechanisms for thermonuclear supernovae. In an effort towards understanding alpha processes from first principles, we describe in this letter the first ab initio calculation of alpha-alpha scattering. We use lattice effective field theory to describe the low-energy interactions of nucleons and apply a technique called the adiabatic projection method to reduce the eight-body system to an effective two-cluster system. We find good agreement between lattice results and experimental phase shifts for S-wave and D-wave scattering. The computational scaling with particle number suggests that alpha processes involving heavier nuclei are also within reach in the near future.
Recent results from COMPASS muon scattering measurements
Capozza, Luigi [Irfu/SPhN - CEA Saclay, 91190 Gif-sur-Yvette (France); Collaboration: COMPASS Collaboration
2012-10-23T23:59:59.000Z
A sample of recent results in muon scattering measurements from the COMPASS experiment at CERN will be reviewed. These include high energy processes with longitudinally polarised proton and deuteron targets. High energy polarised measurements provide important constraints for studying the nucleon spin structure and thus permit to test the applicability of the theoretical framework of factorisation theorems and perturbative QCD. Specifically, latest results on longitudinal quark polarisation, quark helicity densities and gluon polarisation will be reviewed.
Scattering off the Color Glass Condensate
Heikki Mäntysaari
2015-06-24T23:59:59.000Z
In this thesis the Color Glass Condensate (CGC) framework, which describes quantum chromodynamics (QCD) at high energy, is applied to various scattering processes. Higher order corrections to the CGC evolution equations, known as the BK and JIMWLK equations, are also considered. It is shown that the leading order CGC calculations describe the experimental data from electron-proton deep inelastic scattering (DIS), proton-proton and proton-nucleus collisions. The initial condition for the BK evolution equation is obtained by performing a fit to deep inelastic scattering data. The fit result is used as an input to calculations of single particle spectra and nuclear suppression in proton-proton and proton-nucleus collisions, which are shown to be in agreement with RHIC and LHC measurements. In particular, the importance of a proper description of the nuclear geometry consistently with the DIS data fits is emphasized, as it results in a nuclear suppression factor $R_{pA}$ which is consistent with the available experimental data. In addition to single particle production, the correlations between two hadrons at forward rapidity are computed. The RHIC measurements are shown to be naturally explainable in the CGC framework, and the previous CGC calculations are improved by including the so called inelastic and double parton scattering contributions. This improvement is shown to be required in order to get results compatible with the experimentally measured correlations. Exclusive vector meson production, which can be a powerful tool to study the gluonic structure of nuclei at small Bjorken-$x$, is also considered. The cross sections are calculated within the CGC framework in the context of a future electron-ion collider. In particular, the cross section for incoherent diffractive vector meson production is derived and a centrality estimator for this process is proposed.
Spin effects in deeply virtual Compton scattering
A. V. Belitsky; A. Kirchner; D. Müller
2001-06-21T23:59:59.000Z
We consider the azimuthal angle dependence in the cross section of the hard leptoproduction of a photon on a nucleon target. We show that this dependence allows to define observables that isolate the twist-two and twist-three sectors in the deeply virtual Compton scattering amplitude. All twist-two and twist-three Compton form factors can be extracted from measurements of the charge odd part of the polarized cross section and give access to all generalized parton distributions.
Thompson Scattering in an Expanding Universe
James L. Anderson
1997-09-14T23:59:59.000Z
The Thompson cross section for scattering of electromagnetic waves by a free electron in an expanding universe is derived here. The equations of motion of the electron are obtained using the Einstein-Infeld-Hoffmann (EIH) surface integral method. These integrals are evaluated approximately by perturbing off an Einstein-deSitter cosmological field. It is found that the Thompson cross section varies with time as the inverse square of the cosmic scale factor R(t).
Deeply virtual Compton scattering off nuclei
Voutier, Eric
2009-01-01T23:59:59.000Z
Deeply virtual Compton scattering (DVCS) is the golden exclusive channel for the study of the partonic structure of hadrons, within the universal framework of generalized parton distributions (GPDs). This paper presents the aim and general ideas of the DVCS experimental program off nuclei at the Jefferson Laboratory. The benefits of the study of the coherent and incoherent channels to the understanding of the EMC (European Muon Collaboration) effect are discussed, along with the case of nuclear targets to access neutron GPDs.
Harmonic polylogarithms for massive Bhabha scattering
M. Czakon; J. Gluza; T. Riemann
2005-08-19T23:59:59.000Z
One- and two-dimensional harmonic polylogarithms, HPLs and GPLs, appear in calculations of multi-loop integrals. We discuss them in the context of analytical solutions for two-loop master integrals in the case of massive Bhabha scattering in QED. For the GPLs we discuss analytical representations, conformal transformations, and also their transformations corresponding to relations between master integrals in the s- and t-channel.
Thomson scattering for core plasma on DEMO
Mukhin, E. E.; Kurskiev, G. S.; Tolstyakov, S. Yu.; Bukreev, I. M.; Chernakov, P. V.; Kochergin, M. M.; Koval, A. N.; Litvinov, A. E.; Masyukevich, S. V.; Razdobarin, A. G.; Semenov, V. V. [Ioffe Physical Technical Institute, 26 Polytechnicheskaya St., St. Petersburg (Russian Federation); Kukushkin, A. B.; Sdvizhenskii, P. A. [NRC Kurchatov Institute, 1, Akademika Kurchatova pl., Moscow, 123182 (Russian Federation); Andrew, P. [ITER Organization, Route de Vinon sur Verdon, 13115 St Paul Lez Durance (France)
2014-08-21T23:59:59.000Z
This paper describes the challenges of Thomson scattering implementation for core plasma on DEMO and evaluates the capability to measure extremely high electron temperature range 0.5-40keV. A number of solutions to be developed for ITER diagnostics are suggested in consideration of their realization for DEMO. New approaches suggested for DEMO may also be of interest to ITER and currently operating magnetic confinement devices.
Scattering off the Color Glass Condensate
Mäntysaari, Heikki
2015-01-01T23:59:59.000Z
In this thesis the Color Glass Condensate (CGC) framework, which describes quantum chromodynamics (QCD) at high energy, is applied to various scattering processes. Higher order corrections to the CGC evolution equations, known as the BK and JIMWLK equations, are also considered. It is shown that the leading order CGC calculations describe the experimental data from electron-proton deep inelastic scattering (DIS), proton-proton and proton-nucleus collisions. The initial condition for the BK evolution equation is obtained by performing a fit to deep inelastic scattering data. The fit result is used as an input to calculations of single particle spectra and nuclear suppression in proton-proton and proton-nucleus collisions, which are shown to be in agreement with RHIC and LHC measurements. In particular, the importance of a proper description of the nuclear geometry consistently with the DIS data fits is emphasized, as it results in a nuclear suppression factor $R_{pA}$ which is consistent with the available exp...
Modeling light scattering from diesel soot particles
Hull, Patricia; Shepherd, Ian; Hunt, Arlon
2002-07-16T23:59:59.000Z
The Mie model is widely used to analyze light scattering from particulate aerosols. The Diesel Particle Scatterometer (DPS), for example, determines the size and optical properties of diesel exhaust particles that are characterized by measuring three angle-dependent elements of the Mueller scattering matrix. These elements are then fitted using Mie calculations with a Levenburg-Marquardt optimization program. This approach has achieved good fits for most experimental data. However, in many cases, the predicted real and imaginary parts of the index of refraction were less than that for solid carbon. To understand this result and explain the experimental data, we present an assessment of the Mie model by use of a light scattering model based on the coupled dipole approximation. The results indicate that the Mie calculation can be used to determine the largest dimension of irregularly shaped particles at sizes characteristic of Diesel soot and, for particles of known refractive index, tables can be constructed to determine the average porosity of the particles from the predicted index of refraction.
Scattering properties of dark atoms and molecules
James M. Cline; Zuowei Liu; Guy D. Moore; Wei Xue
2014-01-15T23:59:59.000Z
There has been renewed interest in the possibility that dark matter exists in the form of atoms, analogous to those of the visible world. An important input for understanding the cosmological consequences of dark atoms is their self-scattering. Making use of results from atomic physics for the potentials between hydrogen atoms, we compute the low-energy elastic scattering cross sections for dark atoms. We find an intricate dependence upon the ratio of the dark proton to electron mass, allowing for the possibility to "design" low-energy features in the cross section. Dependences upon other parameters, namely the gauge coupling and reduced mass, scale out of the problem by using atomic units. We derive constraints on the parameter space of dark atoms by demanding that their scattering cross section does not exceed bounds from dark matter halo shapes. We discuss the formation of molecular dark hydrogen in the universe, and determine the analogous constraints on the model when the dark matter is predominantly in molecular form.
Dynamical Outcomes of Planet-Planet Scattering
Sourav Chatterjee; Eric B. Ford; Soko Matsumura; Frederic A. Rasio
2008-05-15T23:59:59.000Z
Observations in the past decade have revealed extrasolar planets with a wide range of orbital semimajor axes and eccentricities. Based on the present understanding of planet formation via core accretion and oligarchic growth, we expect that giant planets often form in closely packed configurations. While the protoplanets are embedded in a protoplanetary gas disk, dissipation can prevent eccentricity growth and suppress instabilities from becoming manifest. However, once the disk dissipates, eccentricities can grow rapidly, leading to close encounters between planets. Strong planet--planet gravitational scattering could produce both high eccentricities and, after tidal circularization, very short-period planets, as observed in the exoplanet population. We present new results for this scenario based on extensive dynamical integrations of systems containing three giant planets, both with and without residual gas disks. We assign the initial planetary masses and orbits in a realistic manner following the core accretion model of planet formation. We show that, with realistic initial conditions, planet--planet scattering can reproduce quite well the observed eccentricity distribution. Our results also make testable predictions for the orbital inclinations of short-period giant planets formed via strong planet scattering followed by tidal circularization.
Scattering properties of dark atoms and molecules
Cline, James M; Moore, Guy; Xue, Wei
2013-01-01T23:59:59.000Z
There has been renewed interest in the possibility that dark matter exists in the form of atoms, analogous to those of the visible world. An important input for understanding the cosmological consequences of dark atoms is their self-scattering. Making use of results from atomic physics for the potentials between hydrogen atoms, we compute the low-energy elastic scattering cross sections for dark atoms. We find an intricate dependence upon the ratio of the dark proton to electron mass, allowing for the possibility to "design" low-energy features in the cross section. Dependences upon other parameters, namely the gauge coupling and reduced mass, scale out of the problem by using atomic units. We derive constraints on the parameter space of dark atoms by demanding that their scattering cross section does not exceed bounds from dark matter halo shapes. We discuss the formation of molecular dark hydrogen in the universe, and determine the analogous constraints on the model when the dark matter is predominantly in ...
Scattering Theory for Open Quantum Systems
J. Behrndt; M. M. Malamud; H. Neidhardt
2006-10-31T23:59:59.000Z
Quantum systems which interact with their environment are often modeled by maximal dissipative operators or so-called Pseudo-Hamiltonians. In this paper the scattering theory for such open systems is considered. First it is assumed that a single maximal dissipative operator $A_D$ in a Hilbert space $\\sH$ is used to describe an open quantum system. In this case the minimal self-adjoint dilation $\\widetilde K$ of $A_D$ can be regarded as the Hamiltonian of a closed system which contains the open system $\\{A_D,\\sH\\}$, but since $\\widetilde K$ is necessarily not semibounded from below, this model is difficult to interpret from a physical point of view. In the second part of the paper an open quantum system is modeled with a family $\\{A(\\mu)\\}$ of maximal dissipative operators depending on energy $\\mu$, and it is shown that the open system can be embedded into a closed system where the Hamiltonian is semibounded. Surprisingly it turns out that the corresponding scattering matrix can be completely recovered from scattering matrices of single Pseudo-Hamiltonians as in the first part of the paper. The general results are applied to a class of Sturm-Liouville operators arising in dissipative and quantum transmitting Schr\\"{o}dinger-Poisson systems.
Elastic scattering of Dirac fermions on Schwarzschild black holes
Ion I. Cotaescu; Cosmin Crucean; Ciprian A. Sporea
2015-02-11T23:59:59.000Z
Approximative analytic solutions of the Dirac equation in the Schwarzschild geometry are used for building the partial wave analysis of Dirac fermions scattered by black holes. The analytic expressions of the differential cross section and induced polarization degree are derived in terms of scattering angle, mass of the black hole, energy and mass of the fermion. We perform a graphical study of differential cross section analysing the forward/backward scattering (known also as glory scattering) and the polarization degree as functions of scattering angle. The graphical analysis shows the presence of oscillations in scattering intensity around forward/backward directions, phenomena known as spiral scattering. The energy dependence of the differential cross section is also established by using analytical and graphical methods.
Stone, Kevin H.
2014-07-14T23:59:59.000Z
Some polymer properties, such as conductivity, are very sensitive to short- and intermediate-range orientational and positional ordering of anisotropic molecular functional groups, and yet means to characterize orientational order in disordered systems are very limited. We demonstrate that resonant scattering at the carbon K-edge is uniquely sensitive to short-range orientation correlations in polymers through depolarized scattering at high momentum transfers, using atactic polystyrene as a well-characterized test system. Depolarized scattering is found to coexist with unpolarized fluorescence, and to exhibit pronounced anisotropy. We also quantify the spatially averaged optical anisotropy from low-angle reflectivity measurements, finding anisotropy consistent with prior visible, x-ray absorption, and theoretical studies. The average anisotropy is much smaller than that in the depolarized scattering and the two have different character. Both measurements exhibit clear spectral signatures from the phenyl rings and the polyethylene-like backbone. Discussion focuses on analysis considerations and prospects for using this depolarized scattering for studies of disorder in soft condensed matter.
Boothroyd, Andrew
Concepts of Neutron ScatteringConcepts of Neutron Scattering 66thth PSI Summer School on Condensed Andrew Boothroyd University of Oxford Basic features of neutron scattering Neutron diffraction Neutron on the lattice * * * #12;ScatteringScattering ``nuts and boltsnuts and bolts'' Neutrons, photons, electrons
Small angle neutron and X-ray scattering studies of carbons prepared using inorganic templates
Sandi, G.; Thiyagarajan, P.; Winans, R.E.; Carrado, K.A.
1997-09-01T23:59:59.000Z
Small angle neutron (SANS) and X-ray (SAXS) scattering analyses of carbons derived from organic-loaded inorganic template materials, used as anodes in lithium ion cells, have been performed. Two clays were used as templates to load the organic precursors, pillared montmorrillonite (PILC), a layered silicate clay whose sheets have been permanently propped open by sets of thermally stable molecular props, and sepiolite, a natural channeled clay. Five different organic precursors were used to load the PILC: pyrene, styrene, pyrene/trioxane copolymer, ethylene and propylene, whereas only propylene and ethylene were used to load sepiolite. Pyrolysis took place at 700{degrees}C under nitrogen. Values such as hole radius, fractal dimension, cutoff length and density of the final carbons will be compared as a function of the clay and carbon precursors.
Nonlinear pair production in scattering of photons on ultra-short laser pulses at high energy
Tuchin, Kirill
2009-01-01T23:59:59.000Z
We consider scattering of a photon on a short intense laser pulse at high energy. We argue that for ultra-short laser pulses the interaction is coherent over the entire length of the pulse. At low pulse intensity $I$ the total cross section for electron-positron pair production is proportional to $I$. However, at pulse intensities higher than the characteristic value $I_s$, the total cross section saturates -- it becomes proportional to the logarithm of intensity. This nonlinear effect is due to multi-photon interactions. We derive the total cross section for pair production at high energies by resuming the multi-photon amplitudes to all orders in intensity. We calculate the saturation intensity $I_s$ and show that it is significantly lower than the Schwinger's critical value. We discuss possible experimental tests.
Nonlinear pair production in scattering of photons on ultra-short laser pulses at high energy
Kirill Tuchin
2010-02-15T23:59:59.000Z
We consider scattering of a photon on a short intense laser pulse at high energy. We argue that for ultra-short laser pulses the interaction is coherent over the entire length of the pulse. At low pulse intensity $I$ the total cross section for electron-positron pair production is proportional to $I$. However, at pulse intensities higher than the characteristic value $I_s$, the total cross section saturates -- it becomes proportional to the logarithm of intensity. This nonlinear effect is due to multi-photon interactions. We derive the total cross section for pair production at high energies by resuming the multi-photon amplitudes to all orders in intensity. We calculate the saturation intensity $I_s$ and show that it is significantly lower than the Schwinger's critical value. We discuss possible experimental tests.
A Bunch Length Monitor for JLab 12 GeV Upgrade
Ahmad, Mahmoud Mohamad Ali [ODU; Freyberger, Arne P. [JLAB; Gubeli, Joseph F. [JLAB; Krafft, Geoffrey A. [JLAB
2013-12-01T23:59:59.000Z
A continuous non-invasive bunch length monitor for the 12 GeV upgrade of Jefferson Lab will be used to determine the bunch length of the beam. The measurement will be done at the fourth dipole of the injector chicane at 123 MeV using the coherent synchrotron light emitted from the dipole. The estimated bunch length is 333 fs. A vacuum chamber will be fabricated and a Radiabeam real time interferometer will be used. In this paper, background, the estimated calculations and the construction of the chamber will be discussed.
The effect of stride length alterations on running efficiency in beginning runners
James, Jerry Lynn
1980-01-01T23:59:59.000Z
summary table for caloric cost 2 Descriptive statistics for caloric cost 3 Duncan's New Nultiple Range Test for Stride Length 18 20 LIST OF FIGURES F1gure Page l The eff1cient range of a runner 2 The relat1ve roles of Stride Rate and Stride... Length in velocity changes 3 A two-by-three (sex-by-stride length) repeated measures design 4 A bar chart of the caloric cost means of SL-A, SL-B, and SL-C w1thout distinction between sexes l7 22 5 A bar chart of the caloric cost means of each...
Cudzinovic, M.; Sopori, B. [comp.] [comp.
1995-11-01T23:59:59.000Z
As was noted in the cover letter that accompanied the samples, the eleven bare silicon samples were from various manufacturers. Table I lists the codes for the samples and the manufacturer of each sample. It also notes if the sample was single or poly-crystalline. The samples had been polished on one side before being sent out for measurements, but no further processing was done. The participants of the study were asked to measure either the lifetime or diffusion length of each of the samples using their standard procedure. Table II shows the experimental conditions used by the groups who measured diffusion length. All the diffusion length measurements were performed using the Surface Photovoltage method (SPV). Table M shows the experimental conditions for the lifetime measurements. All the lifetime measurements were made using the Photoconductance Decay method (PCD) under low level injection. These tables show the diameter of the spot size used during the measurement (the effective sampling area), the locations where measurements were taken, and the number of measurements taken at each location. Table N shows the results of the measurements. The table is divided into diffusion length and lifetime measurements for each sample. The values listed are the average values reported by each group. One of the immediate artifacts seen in the data is the large variation in the lifetime measurements. The values from MIT and Mobil are generally close. However, the measurements from NCSU are typically an order of magnitude lower.
Limitations for heterodyne detection of Brillouin scattered light
Allemeier, R.T.; Wagner, J.W.; Telschow, K.L.
1995-01-01T23:59:59.000Z
One means by which elastic properties of a material may be determined is measuring sound wave velocities in the material, from which elastic moduli of interest can be computed. Velocity can be measured by conventional piezoelectric transduction techniques, by applying laser ultrasonics, or by using Brillouin-scattering methods. Brillouin-scattering techniques for determining the sound wave velocity are particularly attractive since they are completely noninvasive. Only a probe beam of light is required since the thermal energy in the material provides the elastic motion. Heterodyne methods for detection of Brillouin-scattered light are considered one possible means to increase the speed of the scattered light frequency detection. Results of experiments with simulated Brillouin scattering suggest that heterodyne detection of the Brillouin-scattered light is feasible. Experiments to detect Brillouin-scattered light, with water as the scattering medium, were designed and interpreted using the results of the simulated scattering experiments. Overall, results showed that it is difficult to narrow the linewidth for Brillouin scattering to an acceptable level. The results given indicate that heterodyne detection of the Brillouin components requires detection bandwidths that are quite small, perhaps 10 Hz or lower. These small bandwidths can be routinely achieved using lock-in amplifier techniques.
Observation of cooperative Mie scattering from an ultracold atomic cloud
Bender, H.; Stehle, C.; Slama, S.; Zimmermann, C. [Physikalisches Institut, Eberhardt-Karls-Universitaet Tuebingen, D-72076 Tuebingen (Germany); Kaiser, R. [Institut Non Lineaire de Nice, CNRS, Universite de Nice Sophia-Antipolis, F-06560 Valbonne (France); Piovella, N. [Dipartimento di Fisica, Universita Degli Studi di Milano, Via Celoria 16, I-20133 Milano (Italy); Courteille, Ph. W. [Physikalisches Institut, Eberhardt-Karls-Universitaet Tuebingen, D-72076 Tuebingen (Germany); Institut Non Lineaire de Nice, CNRS, Universite de Nice Sophia-Antipolis, F-06560 Valbonne (France); Instituto de Fisica de Sao Carlos, Universidade de Sao Paulo, 13560-970 Sao Carlos, SP (Brazil)
2010-07-15T23:59:59.000Z
Scattering of light at a distribution of scatterers is an intrinsically cooperative process, which means that the scattering rate and the angular distribution of the scattered light are essentially governed by bulk properties of the distribution, such as its size, shape, and density, although local disorder and density fluctuations may have an important impact on the cooperativity. Via measurements of the radiation pressure force exerted by a far-detuned laser beam on a very small and dense cloud of ultracold atoms, we are able to identify the respective roles of superradiant acceleration of the scattering rate and of Mie scattering in the cooperative process. They lead, respectively, to a suppression or an enhancement of the radiation pressure force. We observe a maximum in the radiation pressure force as a function of the phase shift induced in the incident laser beam by the cloud's refractive index. The maximum marks the borderline of the validity of the Rayleigh-Debye-Gans approximation from a regime, where Mie scattering is more complex. Our observations thus help to clarify the intricate relationship between Rayleigh scattering of light at a coarse-grained ensemble of individual scatterers and Mie scattering at the bulk density distribution.
Schock, Alfred
1995-08-01T23:59:59.000Z
Paper presented at the 29th IECEC in Monterey, CA in August 1994. The present paper describes the fabrication and testing of full-length prototypcial converters, both unfueled and fueled, and presents parametric results of electrically heated tests.
Korean ESL learners' pragmatic competence: motivation, amount of contact, and length of residence
Ahn, Soo Jin
2009-05-15T23:59:59.000Z
This study examined the motivation for learning English, the amount of contact with English, and length of residence in the target language area that affects Korean graduate students’ English pragmatic skills studying at Texas A&M University...
Length regulation of microtubules by molecular motors: Exact solution and density profiles
Arita, Chikashi; Santen, Ludger
2015-01-01T23:59:59.000Z
In this work we study a microtubule (MT) model , whose length is regulated by the action of processive kinesin motors. We treat the case of infinite processivity, i.e. particle exchange in the bulk is neglected. The exact results can be obtained for model parameters which correspond to a finite length of the MT. In contrast to the model with particle exchange we find that the lengths of the MT are exponentially distributed in this parameter regime. The remaining parameter space of the model, which corresponds to diverging MT lengths, is analyzed by means of extensive Monte-Carlo simulations and a macroscopic approach. For divergent MTs we find a complex structure of the phase diagram in terms of shapes of the density profile.
Kirkpatrick, Kenton C.
2010-01-16T23:59:59.000Z
Shape Memory Alloy actuators can be used for morphing, or shape change, by controlling their temperature, which is effectively done by applying a voltage difference across their length. Control of these actuators requires determination...
An evaluation of inductance loop detector lead length and optimal speed trap distance
Hamm, Robert Alan
1994-01-01T23:59:59.000Z
. Lead lengths were evaluated with five different design vehicles (large and small passenger cars, a pickup truck, a motorcycle, and a high profile truck) with several detector units. Both passenger cars and the pickup truck were always detected with 4000...
FAIR MATCHING ALGORITHM: FIXED-LENGTH FRAME SCHEDULING IN ALL-PHOTONIC NETWORKS
FAIR MATCHING ALGORITHM: FIXED-LENGTH FRAME SCHEDULING IN ALL-PHOTONIC NETWORKS Nahid Saberi email:nahid.saberi@mail.mcgill.ca, coates@ece.mcgill.ca Abstract Internal switches in all
Impact of carbon nanotube length on electron transport in aligned carbon nanotube networks
Lee, Jeonyoon
Here, we quantify the electron transport properties of aligned carbon nanotube (CNT) networks as a function of the CNT length, where the electrical conductivities may be tuned by up to 10× with anisotropies exceeding 40%. ...
Telomere Length in Circulating Leukocytes Is Associated with Lung Function and Disease
Nyholt, Dale R.
Telomere Length in Circulating Leukocytes Is Associated with Lung Function and Disease Eva Albrecht. Comprehensive Pneumology Center Munich (CPC-M), Member of the German Center for Lung Research, Munich, Germany
Viscosity of plant oils as a function of temperature, fatty acid chain length, and unsaturation
Neo, Tong Heng
1988-01-01T23:59:59.000Z
for the degree of MASTER OF SCIENCE December 1988 Major Subject: Agricultural Engineering VISCOSITY OF PLANT OILS AS A FUNCTION OF TEMPERATURE, FATTY ACID CHAIN LENGTH, AND UNSATURATION A Thesis by TONG HENG NEO Approved as to style and content by...: Vincent E. Sweat (Chairman of Committee) Ron L. Richter (Member) R. Engler (Member) Edward A. Hiler (Head of the Department) December 1988 ABSTRACT Viscosity of Plant Oils as a Function of Temperature, Fatty Acid Chain Length, and Unsaturation...
Hook Length Formulas for Trees by Han's Expansion William Y.C. Chen1
Chen, Bill
to unifications of the hook length formulas due to Du and Liu, Han, Gessel and Seo, and Postnikov. Keywords: hook as unifications of the formulas due to Du and Liu [3], Han [6, 7, 8], Gessel and Seo [5]. Let us give a quick given by Chen and Yang [2], and Seo [13]. Hook length formulas have been found for k-ary trees, plane
Bunch length measurement at the Fermilab A0 photoinjector using a Martin-Puplett interferometer
Thurman-Keup, Randy; Fliller, Raymond Patrick; Kazakevich, Grigory; /Fermilab
2008-05-01T23:59:59.000Z
We present preliminary measurements of the electron bunch lengths at the Fermilab A0 Photoinjector using a Martin-Puplett interferometer on loan from DESY. The photoinjector provides a relatively wide range of bunch lengths through laser pulse width adjustment and compression of the beam using a magnetic chicane. We present comparisons of data with simulations that account for diffraction distortions in the signal and discuss future plans for improving the measurement.
Neutron Scattering Experiment Automation with Python
Zolnierczuk, Piotr A [ORNL] [ORNL; Riedel, Richard A [ORNL] [ORNL
2010-01-01T23:59:59.000Z
The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory currently holds the Guinness World Record as the world most powerful pulsed spallation neutron source. Neutrons scattered off atomic nuclei in a sample yield important information about the position, motions, and magnetic properties of atoms in materials. A neutron scattering experiment usually involves sample environment control (temperature, pressure, etc.), mechanical alignment (slits, sample and detector position), magnetic field controllers, neutron velocity selection (choppers) and neutron detectors. The SNS Data Acquisition System (DAS) consists of real-time sub-system (detector read-out with custom electronics, chopper interface), data preprocessing (soft real-time) and a cluster of control and ancillary PCs. The real-time system runs FPGA firmware and programs running on PCs (C++, LabView) typically perform one task such as motor control and communicate via TCP/IP networks. PyDas is a set of Python modules that are used to integrate various components of the SNS DAS system. It enables customized automation of neutron scattering experiments in a rapid and flexible manner. It provides wxPython GUIs for routine experiments as well as IPython command line scripting. Matplotlib and numpy are used for data presentation and simple analysis. We will present an overview of SNS Data Acquisition System and PyDas architectures and implementation along with the examples of use. We will also discuss plans for future development as well as the challenges that have to be met while maintaining PyDas for 20+ different scientific instruments.
Electromagnetic scattering and absorption by aerosol agglomerates
Chen, Hsingyi.
1989-01-01T23:59:59.000Z
Calculation of scattering and absorption by smoke aerosols is required in many applications, including characterization of atmospheric aerosols, prediction of climatic impact of smoke, evaluation of smoke effectiveness in obscuration, calculation of heat transfer from flames, and evaluation of various scenarios of nuclear winter. In this dissertation two procedures were developed to accurately make these calculations utilizing realistic models of smoke agglomerates including oriented chains and fractal geometries. First the Iterative Extended Boundary Condition Method (IEBCM) was utilized to calculate the electromagnetic (EM) scattering and absorption of elongated aerosol particles. The computation efficiency and capability of IEBCM were improved by implementing the sectioning and the segmentation procedures. The sectioning procedure resulted in improving the computational efficiency and the segmentation method made it possible to make calculations for particles with aspect ratios as high as 250. The other procedure employed the Volume Integral Equation Formulation (VIEF) to compute the EM scattering and absorption by agglomerates of complex geometries. The validity of the procedure was checked first by comparing the obtained results with those obtained from the Mie solution for a spherical object and with the IEBCM for nonspherical objects. The comparison between results showed excellent agreement and hence validated the accuracy of the VIEF. The VIEF solution was then used to make calculations for five types of fractal agglomerates of smoke aerosol particles with fractal dimensions in the range from 1.7 to 1.9. The results obtained were compared with those based on the fractal theory recently published by Berry and Percival, and some differences were observed.
Age-related changes in the plasticity and toughness of human cortical bone at multiple length-scales
Zimmermann, Elizabeth A.; Schaible, Eric; Bale, Hrishikesh; Barth, Holly D.; Tang, Simon Y.; Reichert, Peter; Busse, Bjoern; Alliston, Tamara; Ager III, Joel W.; Ritchie, Robert O.
2011-08-10T23:59:59.000Z
The structure of human cortical bone evolves over multiple length-scales from its basic constituents of collagen and hydroxyapatite at the nanoscale to osteonal structures at nearmillimeter dimensions, which all provide the basis for its mechanical properties. To resist fracture, bone’s toughness is derived intrinsically through plasticity (e.g., fibrillar sliding) at structural-scales typically below a micron and extrinsically (i.e., during crack growth) through mechanisms (e.g., crack deflection/bridging) generated at larger structural-scales. Biological factors such as aging lead to a markedly increased fracture risk, which is often associated with an age-related loss in bone mass (bone quantity). However, we find that age-related structural changes can significantly degrade the fracture resistance (bone quality) over multiple lengthscales. Using in situ small-/wide-angle x-ray scattering/diffraction to characterize sub-micron structural changes and synchrotron x-ray computed tomography and in situ fracture-toughness measurements in the scanning electron microscope to characterize effects at micron-scales, we show how these age-related structural changes at differing size-scales degrade both the intrinsic and extrinsic toughness of bone. Specifically, we attribute the loss in toughness to increased non-enzymatic collagen cross-linking which suppresses plasticity at nanoscale dimensions and to an increased osteonal density which limits the potency of crack-bridging mechanisms at micron-scales. The link between these processes is that the increased stiffness of the cross-linked collagen requires energy to be absorbed by “plastic” deformation at higher structural levels, which occurs by the process of microcracking.
A Model for Fiber Length Attrition in Injection-Molded Long-Fiber Composites
TuckerIII, Charles L. [University of Illinois, Urbana-Champaign; Phelps, Jay H [University of Illinois, Urbana-Champaign; El-Rahman, Ahmed Abd [University of Illinois, Urbana-Champaign; Kunc, Vlastimil [ORNL
2013-01-01T23:59:59.000Z
Long-fiber thermoplastic (LFT) composites consist of an engineering thermoplastic matrix with glass or carbon reinforcing fibers that are initially 10 to 13 mm long. When an LFT is injection molded, flow during mold filling orients the fibers and degrades the fiber length. Fiber orientation models for injection molding are well developed, and special orientation models for LFTs have been developed. Here we present a detailed quantitative model for fiber length attrition in a flowing fiber suspension. The model tracks a discrete fiber length distribution (FLD) at each spatial node. Key equations are a conservation equation for total fiber length, and a breakage rate equation. The breakage rate is based on buckling of fibers due to hydrodynamic forces, when the fibers are in unfavorable orientations. The FLD model is combined with a mold filling simulation to predict spatial and temporal variations in fiber length distribution in a mold cavity during filling. The predictions compare well to experiments on a glassfiber/ PP LFT molding. Fiber length distributions predicted by the model are easily incorporated into micromechanics models to predict the stress-strain behavior of molded LFT materials. Author to whom correspondence should be addressed; electronic mail: ctucker@illinois.edu 1
Fano resonances in scattering: an alternative perspective
Lukas Schwarz; Holger Cartarius; Günter Wunner; Walter Dieter Heiss; Jörg Main
2015-06-24T23:59:59.000Z
In a previous paper it has been shown that the interference of the first and second order pole of the Green's function at an exceptional point, as well as the interference of the first order poles in the vicinity of the exceptional point, gives rise to asymmetric scattering cross section profiles. In the present paper we demonstrate that these line profiles are indeed well described by the Beutler-Fano formula, and thus are genuine Fano resonances. Also further away from the exceptional points excellent agreement can be found by introducing energy dependent Fano parameters.
Deeply Virtual Compton Scattering off the neutron
M. Mazouz; A. Camsonne; C. Muñoz Camacho; for the Jefferson Lab Hall A collaboration
2007-12-12T23:59:59.000Z
The present experiment exploits the interference between the Deeply Virtual Compton Scattering (DVCS) and the Bethe-Heitler processes to extract the imaginary part of DVCS amplitudes on the neutron and on the deuteron from the helicity-dependent D$({\\vec e},e'\\gamma)X$ cross section measured at $Q^2$=1.9 GeV$^2$ and $x_B$=0.36. We extract a linear combination of generalized parton distributions (GPDs) particularly sensitive to $E_q$, the least constrained GPD. A model dependent constraint on the contribution of the up and down quarks to the nucleon spin is deduced.
Positron scattering from neon and argon
Jones, A. C. L.; Makochekanwa, C.; Caradonna, P.; Slaughter, D. S.; Machacek, J. R.; McEachran, R. P.; Sullivan, J. P.; Buckman, S. J.; Stauffer, A. D.; Bray, I.; Fursa, D. V. [ARC Centre for Antimatter-Matter Studies, Research School of Physics and Engineering, Australian National University, Canberra 0200 Australia (Australia); Department of Physics, York University, Toronto (Canada); ARC Centre for Antimatter-Matter Studies, Curtin University of Technology, G.P.O. Box U1987, Perth, Western Australia 6845 (Australia)
2011-03-15T23:59:59.000Z
High-resolution measurements of positron interactions with Ne and Ar are presented, as well as theoretical treatments. The data extend over a range of 0.3 to 60 eV and comprise measurements of the grand total, positonium formation, and grand total minus positronium formation cross sections. Theoretical treatments of scattering from Ne and Ar are performed under the relativistic optical potential approach, as well as calculations using the convergent close-coupling method. Comparisons of the present measurements and theories are made with previous theoretical and experimental work.
Transient Rayleigh scattering from single semiconductor nanowires
Montazeri, Mohammad; Jackson, Howard E.; Smith, Leigh M. [Department of Physics, University of Cincinnati, Cincinnati, OH 45221-0011 (United States); Yarrison-Rice, Jan M. [Department of Physics, Miami University, Oxford, OH 45056 (United States); Kang, Jung-Hyun; Gao, Qiang; Tan, Hark Hoe; Jagadish, Chennupati [Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 0200 (Australia)
2013-12-04T23:59:59.000Z
Transient Rayleigh scattering spectroscopy is a new pump-probe technique to study the dynamics and cooling of photo-excited carriers in single semiconductor nanowires. By studying the evolution of the transient Rayleigh spectrum in time after excitation, one can measure the time evolution of the density and temperature of photo-excited electron-hole plasma (EHP) as they equilibrate with lattice. This provides detailed information of dynamics and cooling of carriers including linear and bimolecular recombination properties, carrier transport characteristics, and the energy-loss rate of hot electron-hole plasma through the emission of LO and acoustic phonons.
Deeply Virtual Compton Scattering at HERA II
Laurent Schoeffel
2007-05-22T23:59:59.000Z
A new measurement is presented of elastic deeply virtual Compton scattering (DVCS) based on data taken by the H1 detector during the complete HERA II period. The data are well described by QCD based calculations. For the first time, a beam charge asymmetry is obtained in a colliding mode, using data recorded in $e^-p$ and $e^+p$. A significant non zero value is measured, related to the interference of QCD and QED processes, namely the DVCS and Bethe-Heitler reactions.
Total Cross Sections for Neutron Scattering
C. R. Chinn; Ch. Elster; R. M. Thaler; S. P. Weppner
1994-10-19T23:59:59.000Z
Measurements of neutron total cross-sections are both extensive and extremely accurate. Although they place a strong constraint on theoretically constructed models, there are relatively few comparisons of predictions with experiment. The total cross-sections for neutron scattering from $^{16}$O and $^{40}$Ca are calculated as a function of energy from $50-700$~MeV laboratory energy with a microscopic first order optical potential derived within the framework of the Watson expansion. Although these results are already in qualitative agreement with the data, the inclusion of medium corrections to the propagator is essential to correctly predict the energy dependence given by the experiment.
Fano resonances in scattering: an alternative perspective
Schwarz, Lukas; Wunner, Günter; Heiss, Walter Dieter; Main, Jörg
2015-01-01T23:59:59.000Z
In a previous paper it has been shown that the interference of the first and second order pole of the Green's function at an exceptional point, as well as the interference of the first order poles in the vicinity of the exceptional point, gives rise to asymmetric scattering cross section profiles. In the present paper we demonstrate that these line profiles are indeed well described by the Beutler-Fano formula, and thus are genuine Fano resonances. Also further away from the exceptional points excellent agreement can be found by introducing energy dependent Fano parameters.
Quadratic electroweak corrections for polarized Moller scattering
A. Aleksejevs, S. Barkanova, Y. Kolomensky, E. Kuraev, V. Zykunov
2012-01-01T23:59:59.000Z
The paper discusses the two-loop (NNLO) electroweak radiative corrections to the parity violating electron-electron scattering asymmetry induced by squaring one-loop diagrams. The calculations are relevant for the ultra-precise 11 GeV MOLLER experiment planned at Jefferson Laboratory and experiments at high-energy future electron colliders. The imaginary parts of the amplitudes are taken into consideration consistently in both the infrared-finite and divergent terms. The size of the obtained partial correction is significant, which indicates a need for a complete study of the two-loop electroweak radiative corrections in order to meet the precision goals of future experiments.
Electrochromic control of thin film light scattering
Lindstroem, T.; Kullman, L.; Roennow, D.; Ribbing, C.; Granqvist, C.G. [Department of Technology, Uppsala University, P.O. Box 534, S-752 21, Uppsala (Sweden)] [Department of Technology, Uppsala University, P.O. Box 534, S-752 21, Uppsala (Sweden)
1997-02-01T23:59:59.000Z
Total and diffuse reflectance spectra were measured on Al surfaces covered with electrochromic W oxide films in colored and bleached states. Vector perturbation theory was used for analyzing the spectra. The diffuse reflectance appeared to originate from correlated (uncorrelated) interface roughness when the W oxide film was fully colored (bleached). Assuming partially correlated interfaces led to agreement between experimental and calculated spectra. The use of an electrochromic film appears a promising method to control the relative contributions of the interfaces to the resulting scattering. {copyright} {ital 1997 American Institute of Physics.}
Fano resonances in scattering: an alternative perspective
Lukas Schwarz; Holger Cartarius; Günter Wunner; Walter Dieter Heiss; Jörg Main
2015-03-30T23:59:59.000Z
In a previous paper it has been shown that the interference of the first and second order pole of the Green's function at an exceptional point, as well as the interference of the first order poles in the vicinity of the exceptional point, gives rise to asymmetric scattering cross section profiles. In the present paper we demonstrate that these line profiles are indeed well described by the Beutler-Fano formula, and thus are genuine Fano resonances. Also further away from the exceptional points excellent agreement can be found by introducing energy dependent Fano parameters.
Deep-inelastic photon-neutrino scattering
Huq, M.
1984-02-01T23:59:59.000Z
The moments of the structure functions scrF/sub T//sup( N/), scrF/sub 3//sup( N/), and scrF/sub L//sup( N/) in deep-inelastic photon-neutrino scattering have been calculated. Exactly calculable leading-order QCD corrections to the box-diagram contributions are large for scrF/sub T//sup( N/) and scrF/sub 3//sup( N/) increasing with N. For scrF/sub L//sup( N/) the corrections are very small except for small N. Dependence of the results on the number of flavors of quarks is very small.
Elastic and diffractive scattering at D0
Edwards, Tamsin; /Manchester U.
2004-04-01T23:59:59.000Z
The first search for diffractively produced Z bosons in the muon decay channel is presented, using a data set collected by the D0 detector at the Fermilab Tevatron at {radical}s = 1.96 TeV between April and September 2003, corresponding to an integrated luminosity of approximately 110 pb{sup -1}. The first dN/d|t| distribution for proton-antiproton elastic scattering at this c.o.m. energy is also presented, using data collected by the D0 Forward Proton Detector between January and May 2002. The measured slope is reproduced by theoretical predictions.
Neutron scattering and extra short range interactions
V. V. Nesvizhevsky; G. Pignol; K. V. Protasov
2007-11-14T23:59:59.000Z
The available data on neutron scattering were analyzed to constrain a hypothetical new short-range interaction. We show that these constraints are several orders of magnitude better than those usually cited in the range between 1 pm and 5 nm. This distance range occupies an intermediate space between collider searches for strongly coupled heavy bosons and searches for new weak macroscopic forces. We emphasise the reliability of the neutron constraints in so far as they provide several independent strategies. We have identified the most promising way to improve them.
Cold neutron scattering in imperfect deuterium crystals
Andrzej Adamczak
2010-12-10T23:59:59.000Z
The differential cross sections for cold neutron scattering in mosaic deuterium crystals have been calculated for various target temperatures. The theoretical results are compared with the recent experimental data for the neutron wavelengths $\\lambda\\approx$~1--9~\\AA. It is shown that the structures of observed Bragg peaks can be explained by the mosaic spread of about $3^{\\circ}$ and contributions from a~limited number of crystal orientations. Such a~crystal structure should be also taken into account in ultracold neutron upscattering due to the coherent phonon annihilation in solid deuterium.
Forward Helion Scattering and Neutron Polarization
Buttimore, N. H. [Trinity College Dublin (Ireland)
2009-03-23T23:59:59.000Z
The elastic scattering of spin half helium-3 nuclei at small angles can show a sufficiently large analyzing power to enable the level of helion polarization to be evaluated. As the helion to a large extent inherits the polarization of its unpaired neutron the asymmetry observed in helion collisions can be transformed into a measurement of the polarization of its constituent neutron. Neutron polarimetry therefore relies upon understanding the spin dependence of the electromagnetic and hadronic interactions in the region of interference where there is an optimal analyzing power.
Scattering in PT-symmetric quantum mechanics
Cannata, Francesco [Istituto Nazionale di Fisica Nucleare, Sezione di Bologna and Dipartimento di Fisica dell' Universita, Via Irnerio 46, I 40126 Bologna (Italy)]. E-mail: Francesco.Cannata@bo.infn.it; Dedonder, Jean-Pierre [GMPIB Universite Paris 7 - Denis-Diderot, 2 Place Jussieu, F-75251, Paris Cedex 05 (France)]. E-mail: dedonder@paris7.jussieu.fr; Ventura, Alberto [Ente Nuove Tecnologie, Energia e Ambiente, Bologna and Istituto Nazionale di Fisica Nucleare, Sezione di Bologna (Italy)]. E-mail: Alberto.Ventura@bologna.enea.it
2007-02-15T23:59:59.000Z
A general formalism is worked out for the description of one-dimensional scattering in non-hermitian quantum mechanics and constraints on transmission and reflection coefficients are derived in the cases of P, T or PT invariance of the Hamiltonian. Applications to some solvable PT-symmetric potentials are shown in detail. Our main original results concern the association of reflectionless potentials with asymptotic exact PT symmetry and the peculiarities of separable kernels of non-local potentials in connection with Hermiticity, T invariance and PT invariance.
Neutron Scattering Tutorials | Neutron Science | ORNL
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AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What's Possible for Renewable Energy:Nanowire Solar541,9337, 2011 at3,Neutron Scattering Tutorials SHARE
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AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What'sis Taking Over Our Instagram Secretary Moniz9Morgan ManagingW.tepidumAngle X-ray Scattering
What Does a Scattering Pattern Tell US?
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AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What'sis Taking Over OurThe Iron SpinPrincetonUsing Maps1DOETHEWeeklyTRUDoes a Scattering Pattern Tell
Plateau structures in potential scattering in a strong laser field
Cerkic, A. [Federal Meteorological Institute, Bardakcije 12, 71000 Sarajevo (Bosnia and Herzegowina); Milosevic, D.B. [Faculty of Science, University of Sarajevo, Zmaja od Bosne 35, 71000 Sarajevo (Bosnia and Herzegowina); Max-Born-Institut, Max-Born-Strasse 2a, 12489 Berlin (Germany)
2004-11-01T23:59:59.000Z
Electron-atom scattering in a strong laser field is analyzed using the strong-field approximation and modeling elastic scattering of electrons by atoms with a realistic analytical potential derived from an independent-particle model. The results that include both direct scattering and scattering with a repeated scattering (rescattering) are presented. In the latter case, in the intermediate step of the process, the electron can absorb the energy from the laser field and additional plateau structures appear. The features of these plateaus and their cutoffs are analyzed for various incident electron energies and scattering angles, for different laser intensities, and for various atomic gases. The boundaries of these plateaus are compared with classical estimates.
Scattering of short laser pulses from trapped fermions
T. Wong; Ozgur Mustecaplioglu; L. You; M. Lewenstein
2000-03-28T23:59:59.000Z
We investigate the scattering of intense short laser pulses off trapped cold fermionic atoms. We discuss the sensitivity of the scattered light to the quantum statistics of the atoms. The temperature dependence of the scattered light spectrum is calculated. Comparisons are made with a system of classical atoms who obey Maxwell-Boltzmann statistics. We find the total scattering increases as the fermions become cooler but eventually tails off at very low temperatures (far below the Fermi temperature). At these low temperatures the fermionic degeneracy plays an important role in the scattering as it inhibits spontaneous emission into occupied energy levels below the Fermi surface. We demonstrate temperature dependent qualitative changes in the differential and total spectrum can be utilized to probe quantum degeneracy of trapped Fermi gas when the total number of atoms are sufficiently large $(\\geq 10^6)$. At smaller number of atoms, incoherent scattering dominates and it displays weak temperature dependence.
Measurement of Dynamic Light Scattering Intensity in Gels
Rochas, Cyrille
2015-01-01T23:59:59.000Z
In the scientific literature little attention has been given to the use of dynamic light scattering (DLS) as a tool for extracting the thermodynamic information contained in the absolute intensity of light scattered by gels. In this article we show that DLS yields reliable measurements of the intensity of light scattered by the thermodynamic fluctuations, not only in aqueous polymer solutions, but also in hydrogels. In hydrogels, light scattered by osmotic fluctuations is heterodyned by that from static or slowly varying inhomogeneities. The two components are separable owing to their different time scales, giving good experimental agreement with macroscopic measurements of the osmotic pressure. DLS measurements in gels are, however, tributary to depolarised light scattering from the network as well as to multiple light scattering. The paper examines these effects, as well as the instrumental corrections required to determine the osmotic modulus. For guest polymers trapped in a hydrogel the measured intensity...
Quantum Monte Carlo calculations of neutron-alpha scattering
Kenneth M. Nollett; Steven C. Pieper; R. B. Wiringa; J. Carlson; G. M. Hale
2006-12-09T23:59:59.000Z
We describe a new method to treat low-energy scattering problems in few-nucleon systems, and we apply it to the five-body case of neutron-alpha scattering. The method allows precise calculations of low-lying resonances and their widths. We find that a good three-nucleon interaction is crucial to obtain an accurate description of neutron-alpha scattering.
Color transparency and Landshoff multiple-scattering processes
Botts, J. (Department of Physics, FM-15, University of Washington, Seattle, Washington (USA))
1991-11-01T23:59:59.000Z
In the following, the leading and nonleading contributions to fixed angle hadron-hadron elastic scattering are included in a qualitative analysis of {ital T}({ital s}), the transparency of {ital pN} quasielastic scattering. A simple model is given to predict the center-of-mass energies at which a target nuclei will become transparent to hard- and triple- (Landshoff-) scattered protons.
area scattering phase: Topics by E-print Network
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numerical value. Nathan Poliatzky 1993-04-04 7 Scattering phase asymptotics with fractal remainders Mathematical Physics (arXiv) Summary: For a Riemannian manifold (M,g)...
Coupled-channel scattering in 1 + 1 dimensional lattice model
Guo, Peng [JLAB
2013-07-01T23:59:59.000Z
Based on the Lippmann-Schwinger equation approach, a generalized Lüscher’s formula in 1+1 dimensions for two particles scattering in both the elastic and coupled-channel cases in moving frames is derived. A two-dimensional coupled-channel scattering lattice model is presented, which represents a two-coupled-channel resonant scattering scalars system. The Monte Carlo simulation is performed on finite lattices and in various moving frames. The two-dimensional generalized Lüscher’s formula is used to extract the scattering amplitudes for the coupled-channel system from the discrete finite-volume spectrum.
antineutrino nucleon scattering: Topics by E-print Network
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of the nucleon Nuclear Theory (arXiv) Summary: We calculate the ratio of proton and neutron yields in NC induced neutrino(antineutrino)-nucleus inelastic scattering at...
angle scattering studies: Topics by E-print Network
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report gives selected examples illustrating the use of specific techni- cal 2 Small-Angle Neutron Scattering Studies of Charged Carboxyl-Terminated Dendrimers in Solutions...
Deeply virtual Compton scattering and generalized parton distributions
S. Fazio; R. Fiore; L. L. Jenkovszky
2008-12-16T23:59:59.000Z
We present a comparison of a recently proposed model, which describes the Deeply Virtual Compton Scattering amplitude, to the HERA data.
Numerical solution of inverse scattering for near-field optics
2007-04-30T23:59:59.000Z
May 2, 2007 ... tering problem that arises in near-field optics, which reconstructs the scatterer of an inhomogeneous me- dium located on a substrate from data ...
Wavelet Analysis of Two Dimensional Quantum Scattering A thesis presented
Heller, Eric
Wavelet Analysis of Two Dimensional Quantum Scattering A thesis presented by Jonathan Dillwyn discretization based on the discrete wavelet transformation, which uses basis elements that can readily adapt
Electromagnetic scattering and induction models for spheroidal geometries
Barrowes, Benjamin E., 1973-
2004-01-01T23:59:59.000Z
Electromagnetic scattering from a medium containing randomly distributed discrete dielectric spheroidal inclusions is studied. Also, the broadband magnetoquasistatic solution for the induced magnetic field from a conducting ...
Proton-Proton Scattering at 340 MeV
Chamberlain, Owen; Wiegand, Clyde
2008-01-01T23:59:59.000Z
on Nuclear Physics. Basil. High yner gy Neutron- protonand Proton~proton Scattering 9 Helv. Phys. Acta (in press J a review
The Algebraic Approach to the Phase Problem for Neutron Scattering
A. Cervellino; S. Ciccariello
2004-01-27T23:59:59.000Z
The algebraic approach to the phase problem for the case of X-ray scattering from an ideal crystal is extended to the case of the neutron scattering, overcoming the difficulty related to the non-positivity of the scattering density. In this way, it is proven that the atomicity is the crucial assumption while the positiveness of the scattering density only affects the method for searching the basic sets of reflections. We also report the algebraic expression of the determinants of the Karle-Hauptman matrices generated by the basic sets with the most elongated shape along one of the reciprocal crystallographic axes.
Quasielastic neutron scattering study of water confined in carbon...
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Quasielastic neutron scattering study of water confined in carbon nanopores This article has been downloaded from IOPscience. Please scroll down to see the full text article. 2011...
Inelastic neutron scattering, Raman and DFT investigations of...
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Inelastic neutron scattering, Raman and DFT investigations of the adsorption of phenanthrenequinone on onion-like carbon Daniela M. Anjos a , Alexander I. Kolesnikov a , Zili Wu a...
Inverse medium scattering for the Helmholtz equation at fixed ...
2005-09-03T23:59:59.000Z
Feb 23, 2012 ... The plan of this paper is as follows. The analysis of ... our analysis. More importantly, we give an explicit energy estimate for the scattered field,.
11th LANSCE School on Neutron Scattering | Lecturers
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a window into the internal structure of Layer-by-Layer grown films. The dependence of neutron refractive index on nuclear rather than electronic scattering allows one to...
ORNL study uses neutron scattering, supercomputing to demystify...
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Morgan McCorkle Communications and Media Relations 865.574.7308 ORNL study uses neutron scattering, supercomputing to demystify forces at play in biofuel production This graphical...
11th LANSCE School on Neutron Scattering | School Abstract
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Materials at the Mesoscale The 11th LANSCE School on Neutron Scattering will focus on science of Materials at the Mesoscale: the influence of surfaces, interfaces, and...
Signal evaluations using singular value decomposition for Thomson scattering diagnostics
Tojo, H., E-mail: tojo.hiroshi@jaea.go.jp; Yatsuka, E.; Hatae, T.; Itami, K. [Japan Atomic Energy Agency, 801-1 Mukoyama, Naka 311-0193 (Japan); Yamada, I.; Yasuhara, R.; Funaba, H.; Hayashi, H. [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan)
2014-11-15T23:59:59.000Z
This paper provides a novel method for evaluating signal intensities in incoherent Thomson scattering diagnostics. A double-pass Thomson scattering system, where a laser passes through the plasma twice, generates two scattering pulses from the plasma. Evaluations of the signal intensities in the spectrometer are sometimes difficult due to noise and stray light. We apply the singular value decomposition method to Thomson scattering data with strong noise components. Results show that the average accuracy of the measured electron temperature (T{sub e}) is superior to that of temperature obtained using a low-pass filter (<20 MHz) or without any filters.
A Direct Imaging Method for Inverse Scattering Using the ...
Gang Bao; Kai Huang; Peijun Li; Hongkai Zhao
2014-02-21T23:59:59.000Z
1211292, the ONR grant N00014-12-1-0319, a Key Project of the Major ... Figure 1. Schematic of problem geometry. The scattered wave ...... MR2971173.
Analysis Of Multiple Scattering At Vesuvius Volcano, Italy, Using...
Scattering At Vesuvius Volcano, Italy, Using Data Of The Tomoves Active Seismic Experiment Jump to: navigation, search OpenEI Reference LibraryAdd to library Journal Article:...
Neutron Interactions: Q-Equation, Elastic Scattering
unknown authors
Since a neutron has no charge it can easily enter into a nucleus and cause a reaction. Neutrons interact primarily with the nucleus of an atom, except in the special case of magnetic scattering where the interaction involves the neutron spin and the magnetic moment of the atom. Because magnetic scattering is of no interest in this class, we can neglect the interaction between neutrons and electrons and think of atoms and nuclei interchangeably. Neutron reactions can take place at any energy, so one has to pay particular attention to the energy variation of the interaction cross section. In a nuclear reactor neutrons can have energies ranging from 10-3 ev (1 mev) to 10 7 ev (10 Mev). This means our study of neutron interactions, in principle, will have to cover an energy range of 10 ten orders of magnitude. In practice we will limit ourselves to two energy ranges, the slowing down region (ev to Kev) and the thermal region (around 0.025 ev). For a given energy region – thermal, epithermal, resonance, fast – not all the possible reactions are equally important. Which reaction is important depends on the target nucleus and the neutron energy. Generally speaking the important types of interactions, in the order of increasing complexity from the standpoint of theoretical
Stimulated Brillouin scattering in solid aerosols
Chitanvis, S.M.
1988-08-01T23:59:59.000Z
We estimate the differential scattering cross-section due to SBS in a glass bead which is much larger than the wavelength of a high energy laser beam which irradiates it. We consider three possible scenarios: neither the incident nor the Stokes wavelength is on a Mie resonance; only the Stokes wavelength is on resonance; and the incident wavelength and the Stokes wavelength are on a Mie resonance. For the first two cases, we find that the SBS scattering cross-section is extremely small compared to the geometric/Mie cross-section. It follows as a corollary that SBS in a glass bead will be insufficient to shatter it in these two cases. In the last case, it is quite possible that due to the buildup of high fields on-resonance within the spherical bead, the bead might be shattered. The chance of such an event occurring in a polydisperse distribution of spherical beads is generally not expected to be very high. 3 figs.
Mie scattering by a uniaxial anisotropic sphere
Geng Youlin; Wu Xinbao; Li Lewei; Guan Boran [Institute of Antenna and Microwaves, Hangzhou Dianzi University, Xiasha, Hangzhou, Zhejiang 310018 (China); Shanghai Research Institute of Microwave Technology, Wuning Road 423, Shanghai 200063 (China); Department of Electrical and Computer Engineering, National University of Singapore, Kent Ridge, Singapore 119260 (Singapore); Hangzhou Dianzi University, Xiasha, Hangzhou, Zhejiang 310018 (China)
2004-11-01T23:59:59.000Z
The field solution to the electromagnetic scattering of a plane wave by a uniaxial anisotropic sphere is obtained in terms of a spherical vector wave function expansion form. Using the source-free Maxwell's equations for uniaxial anisotropic media and making the Fourier transform of the field quantities, the electromagnetic fields in the spectral domain in uniaxial anisotropic media are assumed to have a form similar to the plane wave expanded also in terms of the spherical vector wave functions. Applying the continuous boundary conditions of electromagnetic fields on the surface between the air region and uniaxial anisotropic sphere, the coefficients of transmitted fields and the scattered fields in uniaxial anisotropic media can be obtained analytically in the expansion form of vector wave eigenfunctions. Numerical results for some special cases are obtained and compared with those of the classical Lorenz-Mie theory and the method of moments accelerated with the conjugate-gradient fast-Fourier-transform approach. We also present some new numerical results for the more general uniaxial dielectric material media.
Chin, Y.H.
2011-01-01T23:59:59.000Z
for a quick estimate of the FEL parameters which minimizefor the Optimization of the FEL Gain Length Including thet h e Optimization o f the FEL Gain Length Including t h e
Travelling times in scattering by obstacles
Lyle Noakes; Luchezar Stoyanov
2014-09-29T23:59:59.000Z
The paper deals with some problems related to recovering information about an obstacle in an Euclidean space from certain measurements of lengths of generalized geodesics in the exterior of the obstacle. The main result is that if two obstacles satisfy some generic regularity conditions and have (almost) the same traveling times, then the generalized geodesic flows in their exteriors are conjugate on the non-trapping part of their phase spaces with a time preserving conjugacy. In the case of a union of two strictly convex domains in the plane, a constructive algorithm is described to recover the obstacle from traveling times.
Molecular Mechanisms for Microtubule Length Regulation by Kinesin-8 and XMAP215 Proteins
Louis Reese; Anna Melbinger; Erwin Frey
2014-05-22T23:59:59.000Z
The cytoskeleton is regulated by a plethora of enzymes that influence the stability and dynamics of cytoskeletal filaments. Molecular motors of the kinesin-8 protein family depolymerise microtubules in a length-dependent manner, and experimental and theoretical evidence suggest a role for kinesin-8 in the dynamic regulation of microtubules. However, so far the detailed molecular mechanisms how these molecular motors interact with the growing microtubule tip remain elusive. Here we investigate two interaction scenarios for kinesin-8 and the microtubule tip. We give a comprehensive analysis of regimes where length-regulation is possible and characterise how the stationary length depends on the biochemical rates and the bulk concentrations of the various proteins. For a neutral scenario, where microtubules grow irrespective of whether the microtubule tip is occupied by a molecular motor, length regulation is possible only for a narrow range of biochemical rates and limited to small polymerisation rates. In contrast, for an inhibition scenario, where the presence of a motor at the microtubule tip inhibits microtubule growth, the regime of length regulation is extremely broad and includes high growth rates. These results also apply to situations where polymerising enzymes, like XMAP215, and kinesin-8 mutually exclude each other from the microtubule tip. We also investigate the stochastic dynamics of the two scenarios. While for the neutral scenario length is tightly controlled, length dynamics is intermittent for the inhibition scenario and exhibits extended periods of microtubule growth and shrinkage, reminiscent of microtubule dynamic instability. On a broader perspective, the set of models established in this work quite generally suggests that mutual exclusion of molecules at the ends of cytoskeletal filaments is an important factor for filament dynamics and regulation.
Liu, J; Bourland, J [Wake Forest University, Winston-salem, NC (United States)
2014-06-01T23:59:59.000Z
Purpose: To analytically estimate first-order x-ray scatter for kV cone beam x-ray imaging with high computational efficiency. Methods: In calculating first-order scatter using the Klein-Nishina formula, we found that by integrating the point-to-point scatter along an interaction line, a “pencil-beam” scatter kernel (BSK) can be approximated to a quartic expression when the imaging field is small. This BSK model for monoenergetic, 100keV x-rays has been verified on homogeneous cube and cylinder water phantoms by comparing with the exact implementation of KN formula. For heterogeneous medium, the water-equivalent length of a BSK was acquired with an improved Siddon's ray-tracing algorithm, which was also used in calculating pre- and post- scattering attenuation. To include the electron binding effect for scattering of low-kV photons, the mean corresponding scattering angle is determined from the effective point of scattered photons of a BSK. The behavior of polyenergetic x-rays was also investigated for 120kV x-rays incident to a sandwiched infinite heterogeneous slab phantom, with the electron binding effect incorporated. Exact computation and Monte Carlo simulations were performed for comparisons, using the EGSnrc code package. Results: By reducing the 3D volumetric target (o(n{sup 3})) to 2D pencil-beams (o(n{sup 2})), the computation expense can be generally lowered by n times, which our experience verifies. The scatter distribution on a flat detector shows high agreement between the analytic BSK model and exact calculations. The pixel-to-pixel differences are within (-2%, 2%) for the homogeneous cube and cylinder phantoms and within (0, 6%) for the heterogeneous slab phantom. However, the Monte Carlo simulation shows increased deviation of the BSK model toward detector periphery. Conclusion: The proposed BSK model, accommodating polyenergetic x-rays and electron binding effect at low kV, shows great potential in efficiently estimating the first-order scatter from small imaging fields. We are investigating more thoroughly to improve performance and explore applications.
Dynamics and correlation length scales of a glass-forming liquid in quiescent and sheared conditions
Wen-Sheng Xu; Zhao-Yan Sun; Li-Jia An
2012-05-10T23:59:59.000Z
We numerically study dynamics and correlation length scales of a colloidal liquid in both quiescent and sheared conditions to further understand the origin of slow dynamics and dynamic heterogeneity in glass-forming systems. The simulation is performed in a weakly frustrated two-dimensional liquid, where locally preferred order is allowed to develop with increasing density. The four-point density correlations and bond-orientation correlations, which have been frequently used to capture dynamic and static length scales $\\xi$ in a quiescent condition, can be readily extended to a system under steady shear in this case. In the absence of shear, we confirmed the previous findings that the dynamic slowing down accompanies the development of dynamic heterogeneity. The dynamic and static length scales increase with $\\alpha$-relaxation time $\\tau_{\\alpha}$ as power-law $\\xi\\sim\\tau_{\\alpha}^{\\mu}$ with $\\mu>0$. In the presence of shear, both viscosity and $\\tau_{\\alpha}$ have power-law dependence on shear rate in the marked shear thinning regime. However, dependence of correlation lengths cannot be described by power laws in the same regime. Furthermore, the relation $\\xi\\sim\\tau_{\\alpha}^{\\mu}$ between length scales and dynamics holds for not too strong shear where thermal fluctuations and external forces are both important in determining the properties of dense liquids. Thus, our results demonstrate a link between slow dynamics and structure in glass-forming liquids even under nonequilibrium conditions.
Photoelectron track length distributions measured in a negative ion time projection chamber
Prieskorn, Z R; Kaaret, P E; Black, J K
2014-01-01T23:59:59.000Z
We report photoelectron track length distributions between 3 and 8 keV in gas mixtures of Ne+CO2+CH3NO2 (260:80:10 Torr) and CO2+CH3NO2 (197.5: 15 Torr). The measurements were made using a negative ion time projection chamber (NITPC) at the National Synchrotron Light Source (NSLS) at the Brookhaven National Laboratory (BNL). We report the first quantitative analysis of photoelectron track length distributions in a gas. The distribution of track lengths at a given energy is best fit by a lognormal distribution. A powerlaw distribution of the form, f(E)=a(E/Eo)n, is found to fit the relationship between mean track length and energy. We find n=1.29 +/- 0.07 for Ne+CO2+CH3NO2 and n=1.20 +/- 0.09 for CO2+CH3NO2. Understanding the distribution of photoelectron track lengths in proportional counter gases is important for optimizing the pixel size and the dimensions of the active region in electron-drift time projection chambers (TPCs) and NITPC X-ray polarimeters.
Simulation-Length Requirements in the Loads Analysis of Offshore Floating Wind Turbines: Preprint
Haid, L.; Stewart, G.; Jonkman, J.; Robertson, A.; Lackner, M.; Matha, D.
2013-06-01T23:59:59.000Z
The goal of this paper is to examine the appropriate length of a floating offshore wind turbine (FOWT) simulation - a fundamental question that needs to be answered to develop design requirements. To examine this issue, a loads analysis of an example FOWT was performed in FAST with varying simulation lengths. The offshore wind system used was the OC3-Hywind spar buoy, which was developed for use in the International Energy Agency Code Comparison Collaborative Project and supports NREL's offshore 5-megawatt baseline turbine. Realistic metocean data from the National Oceanic and Atmospheric Administration and repeated periodic wind files were used to excite the structure. The results of the analysis clearly show that loads do not increase for longer simulations. In regards to fatigue, a sensitivity analysis shows that the procedure used for counting half cycles is more important than the simulation length itself. Based on these results, neither the simulation length nor the periodic wind files affect response statistics and loads for FOWTs (at least for the spar studied here); a result in contrast to the offshore oil and gas industry, where running simulations of at least 3 hours in length is common practice.
CP-violation in Compton scattering
Mikhail Gorchtein
2008-03-03T23:59:59.000Z
I consider Compton scattering off the nucleon in the presence of $CP$ violation. I construct the Compton tensor which possesses these features and consider low energy expansion (LEX) of the corresponding amplitudes. It allows to separate out the Born contribution which only depends on the static properties of the nucleon, such as the electric charge, the mass, the magnetic moment, and the electric dipole moment (EDM). I introduce new structure constants, the $T$-odd nucleon polarizabilities which parametrize the unknown non-Born part. These constants describe the response of the $T$-violating content of the nucleon to the external quasistatic electromagnetic field. As an estimate, I provide a HBChPT calculation for these new polarizabilities and discuss the implications for the experiment.
Deuteron Compton Scattering: A Random Walk
Harald W. Griesshammer
2004-10-01T23:59:59.000Z
In this sketch, some recent developments in Compton scattering off the deuteron are reviewed. The strong energy-dependence of the scalar magnetic dipole polarisability \\beta_M1 turns out to be crucial to understand the data from Saskatoon at 94 MeV. Chiral Effective Field Theory is used to extract the static iso-scalar dipole polarisabilities as \\bar{\\alpha}^s=12.6\\pm1.4_{stat}\\pm1.0_{wavefu} and \\bar{\\beta}^s=2.3\\pm1.7_{stat}\\pm0.8_{wavefu}, in units of 10^{-4} fm^3. Therefore, proton and neutron polarisabilities are identical within error bars. For details and a better list of references, consult the given references.
Unitary constraints on Deeply Virtual Compton Scattering
J.M. Laget
2007-11-01T23:59:59.000Z
At moderately low momentum transfer ($-t$ up to 1 GeV$^2$) the coupling to the vector meson production channels gives the dominant contribution to real Compton and deeply virtual Compton scattering (DVCS). Starting from a Regge Pole approach that successfully describes vector meson production, the singular part of the corresponding box diagrams (where the intermediate vector meson-baryon pair propagates on-shell) is evaluated without any further assumptions (unitarity). Such a treatment explains not only the unexpectedly large DVCS unpolarized cross section that has been recently measured at Jefferson Laboratory (JLab), but also all the beam spin and charge asymmetries that has been measured at JLab and Hermes, without explicit need of Generalized Parton Distributions (GPD). The issue of the relationship between the two approaches is addressed.
Quantum chaotic scattering in microwave resonators
Dietz, B.; Miski-Oglu, M.; Schaefer, F. [Institut fuer Kernphysik, Technische Universitaet Darmstadt, D-64289 Darmstadt (Germany); Friedrich, T. [Institut fuer Kernphysik, Technische Universitaet Darmstadt, D-64289 Darmstadt (Germany); GSI Helmholzzentrum fuer Schwerionenforschung GmbH, D-64291 Darmstadt (Germany); Harney, H. L.; Weidenmueller, H. A. [Max-Planck-Institut fuer Kernphysik, D-69029 Heidelberg (Germany); Richter, A. [Institut fuer Kernphysik, Technische Universitaet Darmstadt, D-64289 Darmstadt (Germany); ECT, Villa Tambosi, I-38100 Villazzano (Trento) (Italy)
2010-03-15T23:59:59.000Z
In a frequency range where a microwave resonator simulates a chaotic quantum billiard, we have measured moduli and phases of reflection and transmission amplitudes in the regimes of both isolated and of weakly overlapping resonances and for resonators with and without time-reversal invariance. Statistical measures for S-matrix fluctuations were determined from the data and compared with extant and/or newly derived theoretical results obtained from the random-matrix approach to quantum chaotic scattering. The latter contained a small number of fit parameters. The large data sets taken made it possible to test the theoretical expressions with unprecedented accuracy. The theory is confirmed by both a goodness-of-fit-test and the agreement of predicted values for those statistical measures that were not used for the fits, with the data.
Population of the Scattered Kuiper Belt
C. A. Trujillo; D. C. Jewitt; J. X. Luu
1999-12-20T23:59:59.000Z
We present the discovery of three new Scattered Kuiper Belt Objects (SKBOs) from a wide-field survey of the ecliptic. This continuing survey has to date covered 20.2 square degrees to a limiting red magnitude of 23.6. We combine the data from this new survey with an existing survey conducted at the University of Hawaii 2.2m telescope to constrain the number and mass of the SKBOs. The SKBOs are characterized by large eccentricities, perihelia near 35 AU, and semi-major axes > 50 AU. Using a maximum-likelihood model, we estimate the total number of SKBOs larger than 100 km in diameter to be N = 3.1 (+1.9/-1.3) x 10^4 (1 sigma) and the total mass of SKBOs to be about 0.05 Earth masses, demonstrating that the SKBOs are similar in number and mass to the Kuiper Belt inside 50 AU.
Coherence effects in deep inelastic scattering from nuclei
Ver Steeg, G. L. (Greg L.); Raufeisen, J. (Jorg)
2001-01-01T23:59:59.000Z
A complete theoretical picture of multiple scattering processes in QCD remains elusive. In deep inelastic scattering experiments (DIS), we hope to find out information about the internal structure of nuclei from inelastically scattering high-energy electrons off them. The electrons interact via virtual photon exchange with the target. In the target rest frame the virtual photon splits into a quark-antiquark pair which is then scattered off the target color field. At high energies, coherent multiple scattering within the nucleus takes place. We develop a model that uses a parameterization of scattering cross section of the quark-antiquark pair off the proton to predict the cross section suppression known as shadowing in larger nuclei. This model takes the possibility of multiple scattering into account using Glauber high-energy collision theory. In large nuclei we must also move beyond the eikonal approximation by correcting for the finite lifetime of the quark-antiquark pair inside the nucleus. Results and implications of this model in relation to available data will be discussed. Finally, application of this type of model to predicting gluon densities will be considered. Understanding this process can give us insights into the more oomplicated scattering taking place in heavy ion colliders such as RHIC and LHC.
angle neutron scattering: Topics by E-print Network
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