Science.gov

Sample records for scattering angular distribution

  1. Surface Roughness Metrology By Angular Distributions Of Scattered Light

    NASA Astrophysics Data System (ADS)

    Gilsinn, David E.; Vorburger, Theodore V.; Teague, E. Clayton; MeLay, Michael J.; Giauque, Charles; Scire, Fredric E.

    1985-09-01

    On-line industrial inspection of batch manufactured parts requires fast measurement techniques for surface finish quality. In order to develop the measurement basis for these techniques, a system has been built to determine surface roughness by measuring the angular distributions of scattered light. The system incorporates data gathered from the angular distribution instrument and traditional surface stylus instruments. These data are used both as input and as comparison data in order to test various mathematical models of optical scattering phenomena. The object is to develop a mathematical model that uses the angular distribution of scattered light to deduce surface roughness parameters such as Ra and surface wavelength. This paper describes the results of an experiment in which angular scattered data from surfaces with sinusoidal profiles was used to compute the surface R and wavelength. Stylus measurements of these parameters were made separately. A comparative table is given of the computed and measured values. Estimates of uncertainties are also given.

  2. Angular distribution of electrons elastically scattered from water vapor

    NASA Astrophysics Data System (ADS)

    Shyn, T. W.; Grafe, Alan

    1992-10-01

    The angular distributions of electrons elastically scattered from H2O have been measured by electron impact using a modulated crossed-beam method. The energy and angular range measured were from 30 to 200 eV and 12° to 156°, respectively. The present results show a high backward scattering for low incident energies, but this falls off for high incident energies. The present results are in qualitative agreement with the measurements of Danjo and Nishimura [J. Phys. Soc. Jpn. 54, 1224 (1985)] and in quantitative agreement with the measurements of Katase et al. [J. Phys. B 19, 2715 (1986)]. Agreement between the present results and the calculation of Jain, Tripathi, and Jain [Phys. Rev. A 37, 2893 (1988)] is good except at 200-eV impact.

  3. Visualization of scattering angular distributions with the SAP code

    NASA Astrophysics Data System (ADS)

    Fernandez, J. E.; Scot, V.; Basile, S.

    2010-07-01

    SAP (Scattering Angular distribution Plot) is a graphical tool developed at the University of Bologna to compute and plot Rayleigh and Compton differential cross-sections (atomic and electronic), form-factors (FFs) and incoherent scattering functions (SFs) for single elements, compounds and mixture of compounds, for monochromatic excitation in the range of 1-1000 keV. The computation of FFs and SFs may be performed in two ways: (a) by interpolating Hubbell's data from EPDL97 library and (b) by using semi-empirical formulas as described in the text. Two kinds of normalization permit to compare the plots of different magnitudes, by imposing a similar scale. The characteristics of the code SAP are illustrated with one example.

  4. Seemingly anomalous angular distributions in H + D₂ reactive scattering.

    PubMed

    Jankunas, Justin; Zare, Richard N; Bouakline, Foudhil; Althorpe, Stuart C; Herráez-Aguilar, Diego; Aoiz, F Javier

    2012-06-29

    When a hydrogen (H) atom approaches a deuterium (D(2)) molecule, the minimum-energy path is for the three nuclei to line up. Consequently, nearly collinear collisions cause HD reaction products to be backscattered with low rotational excitation, whereas more glancing collisions yield sideways-scattered HD products with higher rotational excitation. Here we report that measured cross sections for the H + D(2) → HD(v' = 4, j') + D reaction at a collision energy of 1.97 electron volts contradict this behavior. The anomalous angular distributions match closely fully quantum mechanical calculations, and for the most part quasiclassical trajectory calculations. As the energy available in product recoil is reduced, a rotational barrier to reaction cuts off contributions from glancing collisions, causing high-j' HD products to become backward scattered.

  5. Effects of Angular Scattering on Ion Velocity Distribution Functions

    NASA Astrophysics Data System (ADS)

    Wang, Huihui; Sukhomlinov, Vladimir; Kaganovich, Igor; Mustafaev, Alexander

    2016-09-01

    An approximation model for total elastic and charge exchange ion-atom angular differential scattering cross sections is developed for simulations of the ion velocity distribution functions (IVDF), which is validated by the experiment data of mobility and diffusion. IVDFs are simulated using the developed model and compared with recently published experimental data. The IVDFs obtained with this model are compared to that from two other conventional models of less accurate differential cross sections. The simulation results show the necessity to take into account the accurate differential cross sections, especially for strong E/ N. The study reveals that IVDF cannot be separated into product of two independent IVDFs in the transverse and parallel to the electric field directions due to the significant effect of scattering.

  6. Singularity in the Laboratory Frame Angular Distribution Derived in Two-Body Scattering Theory

    ERIC Educational Resources Information Center

    Dick, Frank; Norbury, John W.

    2009-01-01

    The laboratory (lab) frame angular distribution derived in two-body scattering theory exhibits a singularity at the maximum lab scattering angle. The singularity appears in the kinematic factor that transforms the centre of momentum (cm) angular distribution to the lab angular distribution. We show that it is caused in the transformation by the…

  7. Angular distribution of electrons elastically scattered from hydrogen atoms

    SciTech Connect

    Shyn, T. W.; Cho, S. Y.

    1989-08-01

    Absolute elastic differential cross sections of atomic hydrogen have been measured by a modulated crossed-beam method. The energy and angular range covered were from 5 to 30 eV and from 12/degree/ to 156/degree/, respectively. The present results agree with the previous measurements within the experimental uncertainty below 15 eV, but it is found that the present results show stronger backward scattering (/gt/120/degree/) than the previous measurement and theoretical results by more than a factor of 2 above 20 eV.

  8. Surface texture characterization by angular distributions of scattered light

    NASA Technical Reports Server (NTRS)

    Gilsinn, D. E.; Vorburger, T. V.; Scire, F. E.; Teague, E. C.; Mclay, M. J.

    1985-01-01

    Work at the National Bureau of Standards to develop an on-line optical measurement device and attendant algorithms for automated optical scattering measurements of machined metal surfaces are described. The surfaces could be milled, ground or lapped, and the system is intended to categorize the resulting surface characteristics. The optical device consists of a He-Ne laser which is shone on a surface. The scattered light is captured by a semicircular array of 87 detector elements rotated over the scanned area. The light signals are processed through a digital voltmeter and then an A/D converter. The signals are then stored for later comparisons with optical scattering data obtained by optical instruments used with stylus instruments for characterizing surface topographies. A theoretical model has been defined which relates light scattering and the characteristics of the surface roughness. Initial experimental results with a sinusoidal surface have indicated that although the system can follow the trend of the roughness, the roughness amplitude is as yet uncertainly defined and the computations require excessive time.

  9. Determination of angular distribution of radiation in an isotropically scattering slab

    NASA Astrophysics Data System (ADS)

    Cengel, Y. A.; Ozisik, M. N.; Yener, Y.

    1984-02-01

    Ozisik (1982) has employed the Galerkin method to arrive at a solution of the radiative transfer equation in an absorbing, emitting, isotropically scattering plane-parallel slab in order to predict radiation flux. This method is presently developed to accurately determine the angular distribution of radiation intensity anywhere in the medium, subject to general boundary conditions.

  10. Second order classical perturbation theory for atom surface scattering: Analysis of asymmetry in the angular distribution

    SciTech Connect

    Zhou, Yun Pollak, Eli; Miret-Artés, Salvador

    2014-01-14

    A second order classical perturbation theory is developed and applied to elastic atom corrugated surface scattering. The resulting theory accounts for experimentally observed asymmetry in the final angular distributions. These include qualitative features, such as reduction of the asymmetry in the intensity of the rainbow peaks with increased incidence energy as well as the asymmetry in the location of the rainbow peaks with respect to the specular scattering angle. The theory is especially applicable to “soft” corrugated potentials. Expressions for the angular distribution are derived for the exponential repulsive and Morse potential models. The theory is implemented numerically to a simplified model of the scattering of an Ar atom from a LiF(100) surface.

  11. Spatial and angular distribution of light incident on coatings using Mie-scattering Monte Carlo simulations.

    PubMed

    Yamada, Masako; Butts, Matthew D; Kalla, Karen K

    2005-01-01

    We show the results of Mie-scattering Monte Carlo models developed to simulate the optical properties of light incident on particle-containing coatings. The model accommodates mixtures of particles with different sizes and complex refractive indices, enabling the simulation of formulations, including pigments. The simulation tracks trajectories of photons as they propagate through the turbid medium, calculating both angular and spatial light intensity distributions. Scalar quantities such as total transmission and reflection, and haze and diffuse reflectance, are also calculated.

  12. Monte Carlo based angular distribution estimation method of multiply scattered photons for underwater imaging

    NASA Astrophysics Data System (ADS)

    Li, Shengfu; Chen, Guanghua; Wang, Rongbo; Luo, Zhengxiong; Peng, Qixian

    2016-12-01

    This paper proposes a Monte Carlo (MC) based angular distribution estimation method of multiply scattered photons for underwater imaging. This method targets on turbid waters. Our method is based on applying typical Monte Carlo ideas to the present problem by combining all the points on a spherical surface. The proposed method is validated with the numerical solution of the radiative transfer equation (RTE). The simulation results based on typical optical parameters of turbid waters show that the proposed method is effective in terms of computational speed and sensitivity.

  13. The calibration of elastic scattering angular distribution at low energies on HIRFL-RIBLL

    NASA Astrophysics Data System (ADS)

    Zhang, G. X.; Zhang, G. L.; Lin, C. J.; Qu, W. W.; Yang, L.; Ma, N. R.; Zheng, L.; Jia, H. M.; Sun, L. J.; Liu, X. X.; Chu, X. T.; Yang, J. C.; Wang, J. S.; Xu, S. W.; Ma, P.; Ma, J. B.; Jin, S. L.; Bai, Z.; Huang, M. R.; Zang, H. L.; Yang, B.; Liu, Y.

    2017-02-01

    The precise calibration of angular distribution of heavy-ion elastic scattering induced by Radioactive Ion Beams (RIBs) at energies around Coulomb barrier on the Radioactive Ion Beam Line in Lanzhou (RIBLL) at the Heavy-Ion Research Facility in Lanzhou (HIRFL) is presented. The beam profile and the scattering angles on the target are deduced by a measurement with two Multi Wire Proportional Chambers (MWPC), and four sets of detector telescopes (including Double-sided Silicon Strip Detectors (DSSD) placed systematically along the beam line, incorporating with Monte Carlo simulation. The MWPCs were used to determine the beam trajectory before the target, and the energies and the positions of scattered particles on the detectors were measured by the DSSDs. Minor corrections on the beam spot and the detector position are performed by assuming the pure Rutherford scattering at angles which are smaller than the related grazing angle. This method is applied for the elastic scattering of 17F on 89Y target at Elab=59 MeV and 50 MeV.

  14. Periodicity property of relativistic Thomson scattering with application to exact calculations of angular and spectral distributions of the scattered field

    SciTech Connect

    Popa, Alexandru

    2011-08-15

    We prove that the analytical expression of the intensity of the relativistic Thomson scattered field for a system composed of an electron interacting with a plane electromagnetic field can be written in the form of a composite periodic function of only one variable, that is, the phase of the incident field. This property is proved without using any approximation in the most general case in which the field is elliptically polarized, the initial phase of the incident field and the initial velocity of the electron are taken into consideration, and the direction in which the radiation is scattered is arbitrary. This property leads to an exact method for calculating the angular and spectral distributions of the scattered field, which reveals a series of physical details of these distributions, such as their dependence on the components of the initial electron velocity. Since the phase of the field is a relativistic invariant, it follows that the periodicity property is also valid when the analysis is made in the inertial system in which the initial velocity of the electron is zero in the case of interactions between very intense electromagnetic fields and relativistic electrons. Consequently, the calculation method can be used for the evaluation of properties of backscattered hard radiations generated by this type of interaction. The theoretical evaluations presented in this paper are in good agreement with the experimental data from literature.

  15. Multiple-scattering distributions and angular dependence of the energy loss of slow protons in copper and silver

    NASA Astrophysics Data System (ADS)

    Cantero, E. D.; Lantschner, G. H.; Eckardt, J. C.; Lovey, F. C.; Arista, N. R.

    2010-04-01

    Measurements of angular distributions and of the angular dependence of the energy loss of 4-, 6-, and 9-keV protons transmitted through thin Cu and Ag polycrystalline foils are presented. By means of standard multiple-scattering model calculations it is found that a V(r)∝r-2.8 potential leads to significantly better fits of the angular distributions than the standard Thomas Fermi, Lenz-Jensen, or Ziegler-Biersack-Littmark potentials. A theoretical model for the angular dependence of the energy loss based on considering geometric effects on a frictional inelastic energy loss plus an angular-dependent elastic contribution and the effects of foil roughness reproduces the experimental data. This agrees with previous results in Au and Al, therefore extending the applicability of the model to other metallic elements.

  16. SU-E-I-44: Some Preliminary Analysis of Angular Distribution of X-Ray Scattered On Soft Tissues

    SciTech Connect

    Ganezer, K; Krmar, M; Cvejic, Z; Rakic, S; Pajic, B

    2015-06-15

    Purpose: The angular distribution of x-radiation scattered at small angles (up to 16 degrees) from several different animal soft tissue (skin, fat, muscle, retina, etc) were measured using standard equipment devoted to study of crystal structure which provides excellent geometry conditions of measurements. showed measurable differences for different tissues. In the simplest possible case when measured samples do not differ in structure (different concentration solutions) it can be seen that intensity of scattered radiation is decreasing function of the concentration and the peak of the maximum of scattering distribution depends on the concentration as well. Methods: An x-ray scattering profile usually consists of sharp diffraction peak; however some properties of the spatial profiles of scattered radiation as intensity, the peak position, height, area, FWHM, the ratio of peak heights, etc. Results: The data contained measurable differences for different tissues. In the simplest possible case when measured samples do not differ in structure (different concentration solutions) it can be seen that intensity of scattered radiation is decreasing function of the concentration and the peak of the maximum of scattering distribution depends on the concentration as well. Measurements of different samples in the very preliminary phase showed that simple biological material used in study showed slightly different scattering pattern, especially at higher angles (around 10degrees). Intensity of radiation scattered from same tissue type is very dependent on water content and several more parameters. Conclusion: This preliminary study using animal soft tissues on the angular distributions of scattered x-rays suggests that angular distributions of X-rays scattered off of soft tissues might be useful in distinguishing healthy tissue from malignant soft tissue.

  17. Quasi-elastic scattering and transfer angular distribution for B,1110+232Th systems at near-barrier energies

    NASA Astrophysics Data System (ADS)

    Dubey, Shradha; Biswas, D. C.; Mukherjee, S.; Patel, D.; Gupta, Y. K.; Prajapati, G. K.; Joshi, B. N.; Danu, L. S.; Mukhopadhyay, S.; John, B. V.; Suryanarayana, S. V.; Vind, R. P.

    2016-12-01

    Quasi-elastic scattering and transfer angular distributions for B,1110+232Th reactions have been measured simultaneously in a wide range of bombarding energies around the Coulomb barrier. The quasi-elastic angular distribution data are analyzed using the optical model code ecis with phenomenological Woods-Saxon potentials. The obtained potential parameters suggest the presence of usual threshold anomaly, confirming tightly bound characteristics for both the projectiles. The reaction cross sections are obtained from the fitting of quasi-elastic angular distribution data. The reduced cross sections at sub-barrier energies compared with Li,76+232Th systems show a systematic dependence on projectile breakup energy. The angular distribution of the transfer products show similar behavior for both the systems.

  18. State-to-state and state-to-all-states reactive scattering angular distributions: F+H /sub 2/. -->. HF+H

    SciTech Connect

    Emmons, R.W.; Suck, S.H.

    1983-04-01

    How each state-to-state reactive transition determines nonundulatory ''state-to-all-states'' angular distribution has not yet been investigated. Here we present a complete exposure of state-to-state distorted-wave Born-approximation angular distributions in order to examine how the nonoscillatory and backward-peaked state-to-all-states reactive scattering angular distribution occurs.

  19. Angular and charge state distributions of highly charged ions scattered during low energy surface-channeling interactions with Au(110)

    SciTech Connect

    Meyer, F.W.; Folkerts, L.; Schippers, S.

    1994-10-01

    The authors have measured scattered projectile angular and charge state distributions for 3.75 keV/amu O{sup q+} (3 {le} q {le} 8) and 1.2 keV/amu Ar{sup 1+} (3 {le} q {le} 14) ions grazingly incident along the [110] and [100] directions of a Au(110) single crystal target. Scattered projectile angular distribution characteristic of surface channeling are observed. For both incident species, the dominant scattered charge fraction is neutral, which varies only by a few percent as a function of incident charge state. Significant O{sup {minus}} formation is observed, which manifests a distinct velocity threshold. For incident Ar projectiles with open L-shells, the positive scattered charge fractions, while always less than about 10%, increase linearly with increasing number of initial L-shell vacancies.

  20. Spectral and angular distribution of light scattered from the elytra of two carabid beetle species

    NASA Astrophysics Data System (ADS)

    Wu, X.; Erbe, A.; Fabritius, H.; Raabe, D.

    2010-06-01

    Color in living organisms is primarily generated by two mechanisms: selective absorption by pigments and structural coloration, or a combination of both. In this study, we investigated the coloration of cuticle from the wings (elytra) of the two ground beetle species Carabus auronitens and Carabus auratus. The greenish iridescent color of both species is created by a multilayer structure consisting of periodically alternating layers with different thicknesses and composition which is located in the 1-2 µm thick outermost layer of the cuticle (epicuticle). Illuminated with white light, reflectance spectra in both linear polarisation show an angle-dependent characteristic peak in the blue/green region of the spectrum. Furthermore, the reflected light is polarised linearly. Scattering experiments with laser illumination at 532 nm show diffuse scattering over a larger angular range. The polarisation dependence of the scattered light is consistent with the interpretation of small inhomogeneities as scattering centres in the elytra.

  1. Effect of the third π ∗ resonance on the angular distributions for electron-pyrimidine scattering

    NASA Astrophysics Data System (ADS)

    Mašín, Zdeněk; Gorfinkiel, Jimena D.

    2016-07-01

    We present a detailed analysis of the effect of the well known third π∗ resonance on the angular behaviour of the elastic cross section in electron scattering from pyrimidine. This resonance, occurring approximately at 4.7 eV, is of mixed shape and core-excited character. Experimental and theoretical results show the presence of a peak/dip behaviour in this energy range, that is absent for other resonances. Our investigations show that the cause of the peak/dip is an interference of background p-wave to p-wave scattering amplitudes with the amplitudes for resonant scattering. The equivalent resonance in pyrazine shows the same behaviour and the effect is therefore likely to appear in other benzene-like molecules. Contribution to the Topical Issue "Advances in Positron and Electron Scattering", edited by Paulo Limao-Vieira, Gustavo Garcia, E. Krishnakumar, James Sullivan, Hajime Tanuma and Zoran Petrovic.

  2. Differences in forward angular light scattering distributions between M1 and M2 macrophages.

    PubMed

    Halaney, David L; Zahedivash, Aydin; Phipps, Jennifer E; Wang, Tianyi; Dwelle, Jordan; Saux, Claude Jourdan Le; Asmis, Reto; Milner, Thomas E; Feldman, Marc D

    2015-11-01

    The ability to distinguish macrophage subtypes noninvasively could have diagnostic potential in cancer, atherosclerosis, and diabetes, where polarized M1 and M2 macrophages play critical and often opposing roles. Current methods to distinguish macrophage subtypes rely on tissue biopsy. Optical imaging techniques based on light scattering are of interest as they can be translated into biopsy-free strategies. Because mitochondria are relatively strong subcellular light scattering centers, and M2 macrophages are known to have enhanced mitochondrial biogenesis compared to M1, we hypothesized that M1 and M2 macrophages may have different angular light scattering profiles. To test this, we developed an in vitro angle-resolved forward light scattering measurement system. We found that M1 and M2 macrophage monolayers scatter relatively unequal amounts of light in the forward direction between 1.6 deg and 3.2 deg with M2 forward scattering significantly more light than M1 at increasing angles. The ratio of forward scattering can be used to identify the polarization state of macrophage populations in culture.

  3. Differences in forward angular light scattering distributions between M1 and M2 macrophages

    NASA Astrophysics Data System (ADS)

    Halaney, David L.; Zahedivash, Aydin; Phipps, Jennifer E.; Wang, Tianyi; Dwelle, Jordan; Saux, Claude Jourdan Le; Asmis, Reto; Milner, Thomas E.; Feldman, Marc D.

    2015-11-01

    The ability to distinguish macrophage subtypes noninvasively could have diagnostic potential in cancer, atherosclerosis, and diabetes, where polarized M1 and M2 macrophages play critical and often opposing roles. Current methods to distinguish macrophage subtypes rely on tissue biopsy. Optical imaging techniques based on light scattering are of interest as they can be translated into biopsy-free strategies. Because mitochondria are relatively strong subcellular light scattering centers, and M2 macrophages are known to have enhanced mitochondrial biogenesis compared to M1, we hypothesized that M1 and M2 macrophages may have different angular light scattering profiles. To test this, we developed an in vitro angle-resolved forward light scattering measurement system. We found that M1 and M2 macrophage monolayers scatter relatively unequal amounts of light in the forward direction between 1.6 deg and 3.2 deg with M2 forward scattering significantly more light than M1 at increasing angles. The ratio of forward scattering can be used to identify the polarization state of macrophage populations in culture.

  4. Differences in forward angular light scattering distributions between M1 and M2 macrophages

    PubMed Central

    Halaney, David L.; Zahedivash, Aydin; Phipps, Jennifer E.; Wang, Tianyi; Dwelle, Jordan; Saux, Claude Jourdan Le; Asmis, Reto; Milner, Thomas E.; Feldman, Marc D.

    2015-01-01

    Abstract. The ability to distinguish macrophage subtypes noninvasively could have diagnostic potential in cancer, atherosclerosis, and diabetes, where polarized M1 and M2 macrophages play critical and often opposing roles. Current methods to distinguish macrophage subtypes rely on tissue biopsy. Optical imaging techniques based on light scattering are of interest as they can be translated into biopsy-free strategies. Because mitochondria are relatively strong subcellular light scattering centers, and M2 macrophages are known to have enhanced mitochondrial biogenesis compared to M1, we hypothesized that M1 and M2 macrophages may have different angular light scattering profiles. To test this, we developed an in vitro angle-resolved forward light scattering measurement system. We found that M1 and M2 macrophage monolayers scatter relatively unequal amounts of light in the forward direction between 1.6 deg and 3.2 deg with M2 forward scattering significantly more light than M1 at increasing angles. The ratio of forward scattering can be used to identify the polarization state of macrophage populations in culture. PMID:26538329

  5. Vibrationally and rotationally resolved angular distributions for F+H2 --> HF(ν,j)+H reactive scattering

    NASA Astrophysics Data System (ADS)

    Dharmasena, Gamini; Phillips, Timothy R.; Shokhirev, Kirill N.; Parker, Gregory A.; Keil, Mark

    1997-06-01

    Angular distributions for individually resolved ν, j states from the F+H2→HF(ν,j)+H chemical reaction are measured for the first time. Vibrational and rotational resolution is achieved simultaneously by applying laser+bolometer detection techniques to crossed-beam reactive scattering. In addition to backward-scattering HF(ν=1, j=6) and HF(ν=2, j=5), we also observe HF(ν=1, j=6) products scattered into the forward hemisphere. The results are in qualitative agreement with fully three-dimensional exact quantum reactive scattering calculations [Castillo et al., J. Chem. Phys. 104, 6531 (1996)] which were conducted on an accurate potential-energy surface [Stark and Werner, J. Chem. Phys. 104, 6515 (1996)]. However, the forward-scattered HF(ν=1, j=6) observed in this experiment is not reproduced by quasi-classical calculations [Aoiz et al., Chem. Phys. Lett. 223, 215 (1994)] on the same potential-energy surface.

  6. Angular distributions of 5eV atomic oxygen scattered from solid surfaces on the LDEF satellite

    NASA Technical Reports Server (NTRS)

    Gregory, John C.; Peters, Palmer N.

    1992-01-01

    The angular distribution of 5eV atomic oxygen scattered off several smooth solid surfaces was measured by experiment A0114 which flew on board the Long Duration Exposure Facility (LDEF). Target surfaces were silver, vitreous carbon, and lithium fluoride crystal. The apparatus was entirely passive. It used the property of silver surfaces to absorb oxygen atoms with high efficiency; the silver is converted to optically transmissive silver oxide. A collimated beam of oxygen atoms is allowed to fall on the target surface at some pre-set angle. Reflected atoms are then intercepted by a silver film placed so that it subtends a considerable solid angle from the primary beam impact on the target surface. The silver films are evaporated onto flexible optically-clear polycarbonate sheets which are scanned later to determine oxygen uptake. While the silver detector cannot measure atom velocity or energy, its physical configuration allows easy coverage of large angular space both in the beam-plane (that which includes the incident beam and the surface normal), and in the azimuthal plane of the target surface.

  7. Analytical inversions in remote sensing of particle size distributions. I - Multispectral extinctions in the anomalous diffraction approximation. II Angular and spectral scattering in diffraction approximations

    NASA Technical Reports Server (NTRS)

    Fymat, A. L.

    1978-01-01

    Consideration is given to analytical inversions in the remote sensing of particle size distributions, noting multispectral extinctions in anomalous diffraction approximation and angular and spectral scattering in diffraction approximation. A closed-form analytical inverse solution is derived in order to reconstruct the size distribution of atmospheric aerosols. The anomalous diffraction approximation to Mie's solution is used to describe the particles. Experimental data yield the geometrical area of aerosol polydispersion. Size distribution is thus found from a set of multispectral extinction measurements. In terms of the angular and spectral scattering of light in a narrow forward cone, it is shown that an analytical inverse solution may also be found for the Fraunhofer approximation to the Kirchhoff diffraction, and for an improved expression of this approximation due to Penndorf (1962) and Shifrin-Punina (1968).

  8. Angular distributions in multifragmentation

    SciTech Connect

    Stoenner, R.W.; Klobuchar, R.L.; Haustein, P.E.; Virtes, G.J.; Cumming, J.B.; Loveland, W.

    2006-04-15

    Angular distributions are reported for {sup 37}Ar and {sup 127}Xe from 381-GeV {sup 28}Si+Au interactions and for products between {sup 24}Na and {sup 149}Gd from 28-GeV {sup 1}H+Au. Sideward peaking and forward deficits for multifragmentation products are significantly enhanced for heavy ions compared with protons. Projectile kinetic energy does not appear to be a satisfactory scaling variable. The data are discussed in terms of a kinetic-focusing model in which sideward peaking is due to transverse motion of the excited product from the initial projectile-target interaction.

  9. Angular distribution of 4.43-MeV γ-rays produced in inelastic scattering of 14.1-MeV neutrons by 12C nuclei

    NASA Astrophysics Data System (ADS)

    Bystritsky, V. M.; Grozdanov, D. N.; Zontikov, A. O.; Kopach, Yu. N.; Rogov, Yu. N.; Ruskov, I. N.; Sadovsky, A. B.; Skoy, V. R.; Barmakov, Yu. N.; Bogolyubov, E. P.; Ryzhkov, V. I.; Yurkov, D. I.

    2016-07-01

    The work is devoted to measuring the angular distribution of 4.43-MeV γ-rays produced in inelastic scattering of 14.1-MeV neutrons by 12C nuclei. A portable ING-27 neutron generator (designed and fabricated at VNIIA, Moscow) with a built-in 64-pixel silicon α-detector was used as a source of tagged neutrons. The γ-rays of characteristic nuclear radiation from 12C were detected with a spectrometric system that consisted of 22 γ-detectors based on NaI(Tl) crystals arranged around the carbon target. The measured angular distribution of 4.43-MeV γ-rays is analyzed and compared with the results of other published experimental works.

  10. Numerical study of particle-size distributions retrieved from angular light-scattering data using an evolution strategy with the Fraunhofer approximation.

    PubMed

    Vargas-Ubera, Javier; Sánchez-Escobar, Juan Jaime; Aguilar, J Félix; Gale, David Michel

    2007-06-10

    An algorithm is presented based on an evolution strategy to retrieve a particle size distribution from angular light-scattering data. The analyzed intensity patterns are generated using the Mie theory, and the algorithm retrieves a series of known normal, gamma, and lognormal distributions by using the Fraunhofer approximation. The distributions scan the interval of modal size parameters 100 < or = alpha < or = 150. The numerical results show that the evolution strategy can be successfully applied to solve this kind of inverse problem, obtaining a more accurate solution than, for example, the Chin-Shifrin inversion method, and avoiding the use of a priori information concerning the domain of the distribution, commonly necessary for reconstructing the particle size distribution when this analytical inversion method is used.

  11. Detector system for the angular distribution measurement of 12C + 12C elastic scattering at 200-400A MeV

    NASA Astrophysics Data System (ADS)

    Qu, W. W.; Zhang, G. L.; Terashima, S.; Guo, C. L.; Tanihata, I.; Le, X. Y.; Wang, T. F.; Zhang, X. H.; Sun, Z. Y.; Duan, L. M.; Hu, R. J.; Lu, C. G.; Ma, P.

    2016-10-01

    To obtain the angular distributions of 12C + 12C elastic scatterings with the incident energies of 200-400A MeV for the study of three-body forces, a detector system was constructed at second Radioactive Ion Beam Line in Lanzhou (RIBLL2) of Institute of Modern Physics (IMP). This system was composed of five plastic scintillation detectors with two read-outs for each detector, a Multi Wire Proportional Chamber (MWPC) and a 4×4 CsI(Tl) array. The 12C beam with the incident energy of 200A MeV on a natural carbon target was used to test this detector system. It is found that the plastic scintillation detector can give the good energy loss (Δ E) and time of flight (TOF) signals, it can also reflect the position information of scattered 12C events. MWPC can precisely provide the trajectories of scattered particles. This system has a very good particle identification ability and can clearly distinguish the scattered 12C particles from the fragments. It can be used for the study of the three-body forces effect for high energy heavy-ion scattering.

  12. Sensitivity of MCNP5 calculations for a spherical numerical benchmark problem to the angular scattering distributions for deuterium

    SciTech Connect

    Kozier, K. S.

    2006-07-01

    This paper examines the sensitivity of MCNP5 k{sub eff} results to various deuterium data files for a simple benchmark problem consisting of an 8.4-cm radius sphere of uranium surrounded by an annulus of deuterium at the nuclide number density corresponding to heavy water. This study was performed to help clarify why {Delta}k{sub eff} values of about 10 mk are obtained when different ENDF/B deuterium data files are used in simulations of critical experiments involving solutions of high-enrichment uranyl fluoride in heavy water, while simulations of low-leakage, heterogeneous critical lattices of natural-uranium fuel rods in heavy water show differences of <1 mk. The benchmark calculations were performed as a function of deuterium reflector thickness for several uranium compositions using deuterium ACE files derived from ENDF/B-VII.b1 (release beta 1), ENDF/B-VI.4 and JENDL-3.3, which differ primarily in the energy/angle distributions for elastic scattering <3.2 MeV. Calculations were also performed using modified ACE files having equiprobable cosine bin values in the centre-of-mass reference frame in a progressive manner with increasing energy. It was found that the {Delta}k{sub eff} values increased with deuterium reflector thickness and uranium enrichment. The studies using modified ACE files indicate that most of the reactivity differences arise at energies <1 MeV; hence, this energy range should be given priority if new scattering distribution measurements are undertaken. (authors)

  13. Time-dependent photoelectron angular distributions

    NASA Astrophysics Data System (ADS)

    Wang, Xiangyang

    1999-09-01

    I show that the angular distribution of electrons photoionized from gas phase targets by short light pulses is time-dependent, when the orbital momentum composition of the photocurrent changes with excitation energy so evolves with the time of detection. A theory of time- dependent photoionization is outlined and general formulas of time-dependent photoelectron flux and angular distribution are given. Two general propagator methods suitable to describe the time-dependent photoionization and scattering processes are developed. The photoionization process is viewed as a local excitation followed by a half scattering. The local excitation process is solved theoretically in a small region around the target core. This approach has been generalized to describe the evolution of a wavepacket in an unbound system. An asymptotic propagator theorem is discovered and used to derive analytic expressions for asymptotic propagators. The origin of the time dependence is explored by parameterizing the time delay and orbital momentum coupling in a two channel model. K-shell photoionization of N2 and CO are calculated with this time- dependent photoionization theory, implemented using a multiple scattering model. Numerical results demonstrate that the time dependence of photoelectron angular distributions is a realistic effect.

  14. Peculiarities of the angular distribution of laser radiation intensity scattered by laser-spark plasma in air

    SciTech Connect

    Malyutin, A A; Podvyaznikov, V A; Chevokin, V K

    2010-02-28

    The spatiotemporal study of the diagram of laser radiation scattering by the laser-spark plasma produced by 3-ns and 50-ns pulses is performed. It is shown that radiation appearing outside the laser beam cone is scattered during the first one - two nanoseconds after the air breakdown, when the spark plasma is located in the vicinity of the laser beam waist and has a shape close to spherical.

  15. Limitations of fitting angular scattering from single cells (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Fan, Xing; Cannaday, Ashley E.; Berger, Andrew J.

    2016-04-01

    The literature contains several reports of Mie-like fits to angular-domain elastic scattering measurements from multiple cells or isolated mitochondria. In these studies, the sampling volume typically contains hundreds or thousands of mitochondria, allowing for the size distribution of mitochondria to be modeled as a smooth function, (e.g. Gaussian or log-normal) with a small number of free parameters. In the case of a single-cell volume containing significantly fewer mitochondria, the true size distribution will no longer be as smooth. Increasing the number of free parameters can lead to unstable fits, however, as the forward-directed angular scattering pattern from such a population illuminated with 785 nm light is a monotonically decaying radial function with few distinct features. Using simulations, we have investigated the limitations of modeling single-cell mitochondrial scattering using smooth population distributions of Mie scatterers. In different instances, the fidelity of the estimated size information can be limited by the number of organelles, the angular detection range, or the non-ideality of the data (both speckle and shot noise). We will describe the conditions under which each of these effects dominates. We will also discuss whether mean and standard deviation are the best sizes to report from such Mie modeling, or if there are other size parameters that have greater fidelity to the true, non-smooth size distributions.

  16. The Far-Field Angular Distribution of High-Order Harmonics Produced in Light Scattering from a Thin Low - Gas Target

    NASA Astrophysics Data System (ADS)

    Peatross, Justin Bruce

    The far-field angular distributions of high-order optical harmonics have been measured. Harmonics up to the 41st order were observed in the light scattered from noble gas targets subjected to very intense pulses of laser radiation with wavelength 1053nm. The experimental conditions minimized collective effects such as phase-mismatch due to propagation or refractive index effects caused, for example, by free electrons arising in the ionization of the target Ar, Kr, or Xe atoms. The angular distributions of many harmonic orders, ranging from the low teens to the upper thirties, all of which emerge collinear to the laser beam, could be distinguished and recorded simultaneously. Gaussian laser pulses, 1.25 -times-diffraction-limited and 1.4ps duration, were focused to intensities ranging from 1times 10^ {13} W/cm^2 to 5times 10^{14} W/cm ^2 using f/70 optics. A novel gas target localized the gas distribution to a thickness of about 1mm, less than one tenth of the laser confocal parameter, at pressures of 1 Torr and less. The narrow and low-density gas distribution employed in these experiments allows the harmonics to be thought of as emerging from atoms lying in a single plane in the interaction region. This is in contrast with previously reported harmonic generation experiments in which propagation effects played strong roles. At these pressures, an order of magnitude below pressures used in other experiments, free electrons created by ionization of target atoms had a negligible effect on the far-field harmonic profiles. We have found that the far-field distributions of nearly all of the harmonics exhibit a narrow central peak surrounded by broad wings of about the same width as the emerging laser beam. The relative widths and strengths of the wings have been found to vary with harmonic order, laser intensity, and atomic species. Since the intensity varies radially across the laser beam in the atomic source plane, an intensity-dependent phase variation among the

  17. Atmospheric particulate analysis using angular light scattering

    NASA Technical Reports Server (NTRS)

    Hansen, M. Z.

    1980-01-01

    Using the light scattering matrix elements measured by a polar nephelometer, a procedure for estimating the characteristics of atmospheric particulates was developed. A theoretical library data set of scattering matrices derived from Mie theory was tabulated for a range of values of the size parameter and refractive index typical of atmospheric particles. Integration over the size parameter yielded the scattering matrix elements for a variety of hypothesized particulate size distributions. A least squares curve fitting technique was used to find a best fit from the library data for the experimental measurements. This was used as a first guess for a nonlinear iterative inversion of the size distributions. A real index of 1.50 and an imaginary index of -0.005 are representative of the smoothed inversion results for the near ground level atmospheric aerosol in Tucson.

  18. Integrated Raman and angular scattering microscopy (IRAM)

    NASA Astrophysics Data System (ADS)

    Smith, Zachary J.; Berger, Andrew J.

    2008-02-01

    A microscope system has been constructed that allows simultaneous acquisition of Raman scattering spectra and elastic scattering Fourier-plane data. The Raman scattering channel reports on chemical composition of the microscopic sample while the elastic scattering channel reports on morphological information about the sample. The system has been validated by acquiring data from single polystyrene beads and analyzing the elastic scattering signal using Generalized Lorenz-Mie Theory while comparing the Raman scattering signature to other polystyrene spectra from the literature. Monocytes and neutrophils, two immune cell types, have also been studied and show clear chemical and morphological differences between cell types.

  19. Glory and thresholds effects in H+D 2 reactive angular scattering

    NASA Astrophysics Data System (ADS)

    Sokolovski, D.

    2003-03-01

    We analyse H+D 2 reactive angular scattering using the S-matrix elements obtained by Aoiz et al. and Althorpe et al. Enhancement of small angle scattering in the v'=3← v=0 H+D 2 delayed reaction is attributed to a glory effect caused by threshold resonances in the v=3 vibrationally adiabatic channel. The oscillatory structures in the reactive angular distributions are shown to be of nearside-farside (NP) origin and are likely to arise from capture in a number of relatively short-lived barrier Regge states at large angular momenta. Padé reconstruction of the reactive matrix element is discussed in detail.

  20. Polarization resolved angular optical scattering of aerosol particles

    NASA Astrophysics Data System (ADS)

    Redding, B.; Pan, Y.; Wang, C.; Videen, G.; Cao, Hui

    2014-05-01

    Real-time detection and identification of bio-aerosol particles are crucial for the protection against chemical and biological agents. The strong elastic light scattering properties of airborne particles provides a natural means for rapid, non-invasive aerosol characterization. Recent theoretical predictions suggested that variations in the polarization dependent angular scattering cross section could provide an efficient means of classifying different airborne particles. In particular, the polarization dependent scattering cross section of aggregate particles is expected to depend on the shape of the primary particles. In order to experimentally validate this prediction, we built a high throughput, sampling system, capable of measuring the polarization resolved angular scattering cross section of individual aerosol particles flowing through an interrogating volume with a single shot of laser pulse. We calibrated the system by comparing the polarization dependent scattering cross section of individual polystyrene spheres with that predicted by Mie theory. We then used the system to study different particles types: Polystyrene aggregates composed 500 nm spheres and Bacillus subtilis (BG, Anthrax simulant) spores composed of elongated 500 nm × 1000 nm cylinder-line particles. We found that the polarization resolved scattering cross section depends on the shape of the constituent elements of the aggregates. This work indicates that the polarization resolved scattering cross section could be used for rapid discrimination between different bio-aerosol particles.

  1. Calculated angular distributions of energetic atmospheric neutrons

    NASA Technical Reports Server (NTRS)

    Merker, M.

    1975-01-01

    Calculated angular distributions of atmospheric leakage neutron fluxes from 19 MeV to 1 GeV are presented. Comparisons with the balloon measurements of Preszler et al. and Kanbach et al. are made and show substantial agreement, strengthening the belief in the importance of the CRAND (cosmic-ray albedo-neutron decay) contribution to the high-energy protons in the earth's inner radiation belt. The calculation is presented as a means for investigating features of atmospheric flux distributions.

  2. Investigation into angular and frequency dependence of scattering matrices of elastodynamic scatterers

    NASA Astrophysics Data System (ADS)

    Zhang, Jie; Felice, Maria; Velichko, Alexander; Wilcox, Paul

    2016-02-01

    The scattering behaviour of a finite-sized elastodynamic scatterer in a homogeneous isotropic medium can be encapsulated in a scattering matrix (S-matrix) for each wave mode combination. Each S-matrix is a continuous complex function of 3 variables: incident wave angle, scattered wave angle and frequency. In the paper, the S-matrices for various scatterers (circular holes, straight smooth cracks, rough cracks and 4 circular holes in an area of interest) are investigated. It is shown that, for a given scatterer, the continuous data in the angular dimensions of an S-matrix can be represented to a prescribed level of accuracy by a finite number of complex Fourier coefficients. The finding is that the number of angular orders required to characterise a scatterer is a function of scatterer size and is related to the Nyquist theorem. The variation of scattering behaviour with frequency is examined next and is found to show periodic oscillation with a period which is a function of scatterer size and its geometry. The shortest period of these oscillations indicates the maximum frequency increment required to accurately describe the scattering behaviour in a specific frequency range. Finally, the maximum angular order and frequency increments for the chosen scatterers in a specific frequency range are suggested.

  3. Two-body scattering without angular-momentum decomposition

    SciTech Connect

    Rodriguez-Gallardo, M.; Deltuva, A.; Cravo, E.; Fonseca, A. C.; Crespo, R.

    2008-09-15

    Two-body scattering is studied by solving the Lippmann-Schwinger equation in momentum space without angular-momentum decomposition for a local spin-dependent short-range interaction plus Coulomb. The screening and renormalization approach is employed to treat the Coulomb interaction. Benchmark calculations are performed by comparing our procedure with partial-wave calculations in configuration space for p-{sup 10}Be,p-{sup 16}O, and {sup 12}C-{sup 10}Be elastic scattering, using a simple optical potential model.

  4. Angular scattering of sound from solid particles in turbulent suspension.

    PubMed

    Moore, Stephanie A; Hay, Alex E

    2009-09-01

    Sound scattering by solid particles suspended in a turbulent jet is investigated. Measurements of the scattered amplitude were made in a bistatic geometry at frequencies between 1.5 and 4.0 MHz, and at scattering angles from 95 degrees to 165 degrees relative to the forward direction. Two types of particle were used: nearly spherical lead-glass beads and aspherical natural sand grains. For each particle type, experiments were carried out using approximately 200 and approximately 500 microm median diameter grain sizes, corresponding to 0.7 < or approximately ka < or approximately 4. The sphericity of the sand grains, defined as the ratio of projected perimeter size to projected area size, was 1.08. The lead-glass bead results are consistent with an elastic sphere model. A rigid movable sphere model provides the best fit to the sand data, and the best-fit diameter is within 4% of the equivalent volume size. However, the scattering pattern for sand is systematically smoother than predicted: that is, the undulations in the angular scattering pattern predicted by spherical scatterer theory are present, but muted. This observed departure from spherical scatterer theory is attributed to disruption of the interference among creeping waves by the irregular surfaces of natural sand grains.

  5. Quark structure of the nucleon and angular asymmetry of proton-neutron hard elastic scattering.

    PubMed

    Granados, Carlos G; Sargsian, Misak M

    2009-11-20

    We investigate an asymmetry in the angular distribution of hard elastic proton-neutron scattering with respect to the 90 degrees center of mass scattering angle and demonstrate that it's magnitude is related to the helicity-isospin symmetry of the quark wave function of the nucleon. Our estimate of the asymmetry within the quark-interchange model of hard scattering demonstrates that the quark wave function of a nucleon based on the exact SU(6) symmetry predicts an angular asymmetry opposite to that of experimental observations. We found that the quark wave function based on the diquark picture of the nucleon produces a correct asymmetry. Comparison with the data allowed us to show that the vector diquarks contribute around 10% in the nucleon wave function and they are in negative phase relative to the scalar diquarks. These observations are essential in constraining QCD models of a nucleon.

  6. Measurement of the Angular Distributions of Drell-Yan Dimuons

    NASA Astrophysics Data System (ADS)

    Bowen, Brandon; Fermilab E-906/SeaQuest Collaboration

    2011-10-01

    The angular differential cross section for the Drell-Yan (DY) process can be parametrized by dσ/dΩ ~ 1 + λcos2 θ + μsin 2 θcosφ +ν/2sin2 θcos 2 φ , where λ, μ, and ν are the angular distribution parameters vs pT. θ and φ denote the polar and azimuthal angles, respectively for the positive lepton produced. The Lam-Tung relation, 1 - λ = 2 ν , was validated by Fermilab E-866 for proton induced Drell-Yan scattering; However pion induced DY shows a much stronger cos2 θ angular dependence and a violation of the Lam-Tung relation. In pion induced DY the antiquark is a valance quark, whereas in proton induced DY (in a forward acceptance spectrometer) it is a sea quark, so E-866 probed the antiquark sea of the nucleon. The SeaQuest experiment, also using proton induced DY, will improve on the measurement of the angular dependencies at a lower energy (120 GeV), taking advantage lower backgrounds and an increase in Drell-Yan cross section at lower energies. The Boer-Mulders correlates the quark correlates between the quark transverse spin and momentum. Improved data from SeaQuest will help determine the Boer-Mulders function. Funding for this work was provided in part by the U.S. DOE Office of Science.

  7. Electron angular distributions above the dayside auroral oval

    NASA Technical Reports Server (NTRS)

    Craven, J. D.; Frank, L. A.

    1975-01-01

    An electrostatic analyzer was employed on the Ariel 4 satellite to determine pitch angle distributions of electron intensities over the dayside auroral oval. Two major precipitation zones were encountered: an equatorward zone of broad spectra with intensities of approximately 1000 electrons/(sq cm-sec-sr-eV) and a poleward zone, the polar cusp, with intensities typical of those of the magnetosheath. Angular distributions within the equatorward zone are generally isotropic outside of the atmospheric backscatter cone. The precipitation mechanism appears to be pitch angle scattering near the distant magnetic equator. In contrast, pitch angle distributions within the polar cusp are often found to be strongly field aligned with intensities within the atmospheric loss cone greater by factors of approximately 10 than the mirroring intensities. These distributions are qualititatively similar to those for the inverted V precipitation events at later local times, and probably share a common acceleration mechanism with the inverted V phenomenon.

  8. Integrated Raman and angular scattering of single biological cells

    NASA Astrophysics Data System (ADS)

    Smith, Zachary J.

    2009-12-01

    Raman, or inelastic, scattering and angle-resolved elastic scattering are two optical processes that have found wide use in the study of biological systems. Raman scattering quantitatively reports on the chemical composition of a sample by probing molecular vibrations, while elastic scattering reports on the morphology of a sample by detecting structure-induced coherent interference between incident and scattered light. We present the construction of a multimodal microscope platform capable of gathering both elastically and inelastically scattered light from a 38 mum2 region in both epi- and trans-illumination geometries. Simultaneous monitoring of elastic and inelastic scattering from a microscopic region allows noninvasive characterization of a living sample without the need for exogenous dyes or labels. A sample is illuminated either from above or below with a focused 785 nm TEM00 mode laser beam, with elastic and inelastic scattering collected by two separate measurement arms. The measurements may be made either simultaneously, if identical illumination geometries are used, or sequentially, if the two modalities utilize opposing illumination paths. In the inelastic arm, Stokes-shifted light is dispersed by a spectrograph onto a CCD array. In the elastic scattering collection arm, a relay system images the microscope's back aperture onto a CCD detector array to yield an angle-resolved elastic scattering pattern. Post-processing of the inelastic scattering to remove fluorescence signals yields high quality Raman spectra that report on the sample's chemical makeup. Comparison of the elastically scattered pupil images to generalized Lorenz-Mie theory yields estimated size distributions of scatterers within the sample. In this thesis we will present validations of the IRAM instrument through measurements performed on single beads of a few microns in size, as well as on ensembles of sub-micron particles of known size distributions. The benefits and drawbacks of the

  9. Incoherent source angular domain imaging through complex three-dimensional scattering structures

    NASA Astrophysics Data System (ADS)

    Cheng, Rongen L. K.; Chiang, Gary; Chapman, Glenn H.

    2012-03-01

    Scattering of photons in biological imaging is a known factor of degrading image resolution and quality. Angular Domain Imaging (ADI) is a technique which utilizes the angular distribution of photons to filter out multiple-scattering photons and accept only photons with small angular deviation from their original trajectories. The advantage of ADI is that it does not require a high optical quality, coherent, or pulsed source to acquire quality image. Initial experiments with Spatialfrequency Filter (SFF) ADI on simple liquid scattering test phantom showed good results as it can image through media with scattering ratio (SR) of 106:1. Previous work with complex 3D aquatic species eliminated scattering but showed optical interference patterns from the coherent laser sources. With SFF ADI, our target is to image through a complex 3D scattering structure with multilayer of different refractive indices and scattering coefficient from an Intralipid-infused polymer/agar, and a small species called Branchiostoma lanceolatum, a lancelet that is 5-8cm long and ~5mm thick. To remove interference, several narrow wavelength-band LEDs were used as illumination sources with one peaks at 630nm and the other peaks at 415nm. The LEDs are collimated and illuminates the 3D structure/lancelet in a water-filler container while a SFF removes the scattered photons before the imager. This allows us to reduce the optical interference and to study the impact of switching from coherent laser source into an incoherent narrow wavelength-band source. Hence, it allows us to investigate the enhancement of imaging the internal structures using the incoherent narrow wavelength-band source.

  10. Energy Dependence of Angular Distributions of Sputtered Particles by Ion-Beam Bombardment at Normal Incidence

    NASA Astrophysics Data System (ADS)

    Matsuda, Yoshinobu; Yamamura, Yasunori; Ueda, Yasutoshi; Uchino, Kiichiro; Muraoka, Katsunori; Maeda, Mitsuo; Akazaki, Masanori

    1986-01-01

    The angular distributions of sputtered Fe-atoms were measured using the laser fluorescence technique during Ar-ion bombardment for energies of 0.6, 1, 2 and 3 keV at normal incidence. The measured cosine distribution at 0.6 keV progressively deviated to an over-cosine distribution at higher energies, and at 3 keV the angular distribution was an over-cosine distribution of about 20%. The experimental results agree qualitatively with calculations by a recent computer simulation code, ACAT. The results are explained by the competition between surface scattering and the effects of primary knock-on atoms, which tend to make the angular distributions over-cosine and under-cosine, respectively.

  11. Angular Distributions of Synchrotron Radiation in the Nonrelativistic Approximation

    NASA Astrophysics Data System (ADS)

    Bagrov, V. G.; Loginov, A. S.

    2017-03-01

    The angular distribution functions of the polarized components of synchrotron radiation in the nonrelativistic approximation are investigated using methods of classical and quantum theory. Particles of zero spin (bosons) and spin 1/2 (electrons) are considered in the quantum theory. It is shown that in the first nonzero approximation the angular distribution functions, calculated by methods of classical and quantum theory, coincide identically. Quantum corrections to the angular distribution functions appear only in the subsequent approximation whereas the total radiated power contains quantum and spin corrections already in the first approximation.

  12. Quantum optimal control of photoelectron spectra and angular distributions

    NASA Astrophysics Data System (ADS)

    Goetz, R. Esteban; Karamatskou, Antonia; Santra, Robin; Koch, Christiane P.

    2016-01-01

    Photoelectron spectra and photoelectron angular distributions obtained in photoionization reveal important information on, e.g., charge transfer or hole coherence in the parent ion. Here we show that optimal control of the underlying quantum dynamics can be used to enhance desired features in the photoelectron spectra and angular distributions. To this end, we combine Krotov's method for optimal control theory with the time-dependent configuration interaction singles formalism and a splitting approach to calculate photoelectron spectra and angular distributions. The optimization target can account for specific desired properties in the photoelectron angular distribution alone, in the photoelectron spectrum, or in both. We demonstrate the method for hydrogen and then apply it to argon under strong XUV radiation, maximizing the difference of emission into the upper and lower hemispheres, in order to realize directed electron emission in the XUV regime.

  13. Energy and angular distributions of sputtered atoms at normal incidence

    NASA Astrophysics Data System (ADS)

    Yamamura, Y.; Takiguchi, T.; Ishida, M.

    1991-12-01

    The Monte Carlo simulation code ACAT has been applied to investigate the angular distribution and the energy distribution of atoms sputtered from Cu and Nb targets by normally incident Ar+ ions. It is found that there are two important effects which affect the angular distributions and the energy distributions of sputtered atoms, i.e., the anisotropic effect and the bulk recoil effect. The former effects means that the recoil flux keeps the memory of the incident ion-beam direction because of the incomplete cascade, while the latter one means the contributions of recoils generated at the deeper layer to the angular and the energy distributions of sputtered atoms. The anisotropic effect is important in the low energy region, and it makes the angular distribution under-cosine and the high energy tail of the energy distribution fall off faster than the Thompson distribution. The bulk recoil effect makes angular distribution be over-cosine and the peak position of the energy distribution be shifted to somewhat higher energies.

  14. Fourier transform light scattering angular spectroscopy using digital inline holography.

    PubMed

    Kim, Kyoohyun; Park, YongKeun

    2012-10-01

    A simple and practical method for measuring the angle-resolved light scattering (ARLS) from individual objects is reported. Employing the principle of inline holography and a Fourier transform light scattering technique, both the static and dynamic scattering patterns from individual micrometer-sized objects can be effectively and quantitatively obtained. First, the light scattering measurements were performed on individual polystyrene beads, from which the refractive index and diameter of each bead were retrieved. Also, the measurements of the static and dynamic light scattering from intact human red blood cells are demonstrated. Using the present method, an existing microscope can be directly transformed into a precise instrument for ARLS measurements.

  15. Spatial distributions of angular momenta in quantum and quasiclassical stereodynamics.

    PubMed

    de Miranda, Marcelo P; Aoiz, F Javier; Sáez-Rábanos, V; Brouard, Mark

    2004-11-22

    We have recently reported a derivation of the relationship between the quantum and classical descriptions of angular momentum polarization [M. P. de Miranda and F. Javier Aoiz, Phys. Rev. Lett. 93, 083201 (2004)]. This paper presents a detailed account of the derivation outlined in that paper, and discusses the implications of the new results. These include (i) a new expression of the role of the uncertainty principle in the broadening of angular momentum distributions, (ii) the attribution of azimuthal fluctuations of angular momentum distributions to spatial quantum beats, (iii) the definition of a new Fourier transform of the density matrix, distinct from those suggested in the past, that provides an alternative view of how the quantum description of angular momentum polarization approaches the classical one in the correspondence principle limit, (iv) a prescription for the determination of a quasiclassical angular momentum distribution function that does not suffer from problems encountered with its purely classical counterpart, and (v) a description of how angular momentum distributions commonly visualized with recourse to the classical vector model can be depicted with exact and well-defined quantum mechanics.

  16. Spatial distributions of angular momenta in quantum and quasiclassical stereodynamics

    NASA Astrophysics Data System (ADS)

    de Miranda, Marcelo P.; Aoiz, F. Javier; Sáez-Rábanos, V.; Brouard, Mark

    2004-11-01

    We have recently reported a derivation of the relationship between the quantum and classical descriptions of angular momentum polarization [M. P. de Miranda and F. Javier Aoiz, Phys. Rev. Lett. 93, 083201 (2004)]. This paper presents a detailed account of the derivation outlined in that paper, and discusses the implications of the new results. These include (i) a new expression of the role of the uncertainty principle in the broadening of angular momentum distributions, (ii) the attribution of azimuthal fluctuations of angular momentum distributions to spatial quantum beats, (iii) the definition of a new Fourier transform of the density matrix, distinct from those suggested in the past, that provides an alternative view of how the quantum description of angular momentum polarization approaches the classical one in the correspondence principle limit, (iv) a prescription for the determination of a quasiclassical angular momentum distribution function that does not suffer from problems encountered with its purely classical counterpart, and (v) a description of how angular momentum distributions commonly visualized with recourse to the classical vector model can be depicted with exact and well-defined quantum mechanics.

  17. Comparison of DTR spectral-angular characteristics of divergent beam of relativistic electrons in scattering geometry of Laue and Bragg

    NASA Astrophysics Data System (ADS)

    Blazhevich, S. V.; Koskova, T. V.; Ligidov, A. Z.; Noskov, A. V.

    2016-07-01

    Diffracted transition radiation (DTR) generated by a divergent beam of relativistic electrons crossing a single-crystal plate in different (Laue, Bragg) scattering geometry has been considered for the general case of asymmetric reflection of the electron coulomb field relative to the entrance target surface. The expressions for spectral-angular density of DTR and parametric X-ray Radiation (PXR) has been derived. Then DTR and PXR has been considered in case of a thin target, when multiple scattering of electron is negligibly small, which is important for divergence measurement in real time regime. Numerical calculation of spectral-angular density of DTR by a beam of relativistic electrons has been made using averaging over the bivariate Gauss distribution as angular distribution of relativistic electrons in the beam. It has been shown that in Bragg scattering geometry the angular density of DTR is bigger, than in Laue geometry, which can be explained by the existence of the frequency range, in which the incident wave propagation vector takes complex value even under absence of absorption. In this range, all of photons are reflected in Bragg direction. It means that the range of total reflection defines the width of DTR spectrum.

  18. Angular distribution of particles sputtered from metals and alloys

    SciTech Connect

    Wucher, A.; Reuter, W.

    1988-07-01

    The angular distributions of atoms sputtered from pure Cu and Be as well as Cu/sub 98/Be/sub 2/, Cu/sub 71/Zn/sub 29/, Co/sub 3/Au, and WSi/sub 2.3/ were investigated for bombardment with Ar/sup +/ ions of 250 eV and 2 keV under normal incidence. Between polar emission angles theta = 0/sup 0/ and 60/sup 0/, for the higher bombarding energy all observed angular distributions look very much alike and follow essentially a cos/sup 3/ theta law. For the low bombarding energy, however, significant differences between the angular distributions of the alloy constituents are found. The effect, which is most pronounced for CuBe, seems to scale with the atomic mass in the way that the lower mass particles are sputtered preferentially along the surface normal.

  19. Influence of the angular shape of the volume-scattering function and multiple scattering on remote sensing reflectance

    NASA Astrophysics Data System (ADS)

    Chami, Malik; McKee, David; Leymarie, Edouard; Khomenko, Gueorgui

    2006-12-01

    Scattering phase functions derived from measured (volume-scattering meter, VSM) volume-scattering functions (VSFs) from Crimean coastal waters were found to have systematic differences in angular structure from Fournier-Forand (FF) functions with equivalent backscattering ratios. Hydrolight simulations demonstrated that differences in the angular structure of the VSF could result in variations in modeled subsurface radiance reflectances of up to ±20%. Furthermore, differences between VSM and FF simulated reflectances were found to be nonlinear as a function of scattering and could not be explained with the single-scattering approximation. Additional radiance transfer modeling demonstrated that the contribution of multiple scattering to radiance reflectance increased exponentially from a minimum of 16% for pure water to a maximum of ˜94% for turbid waters. Monte Carlo simulations demonstrated that multiple forward-scattering events were the dominant contributors to the generation of radiance reflectance signals for turbid waters and that angular structures in the shape of the VSF at forward angles could have a significant influence in determining reflectance signals for turbid waters.

  20. Influence of the angular shape of the volume-scattering function and multiple scattering on remote sensing reflectance.

    PubMed

    Chami, Malik; McKee, David; Leymarie, Edouard; Khomenko, Gueorgui

    2006-12-20

    Scattering phase functions derived from measured (volume-scattering meter, VSM) volume-scattering functions (VSFs) from Crimean coastal waters were found to have systematic differences in angular structure from Fournier-Forand (FF) functions with equivalent backscattering ratios. Hydrolight simulations demonstrated that differences in the angular structure of the VSF could result in variations in modeled subsurface radiance reflectances of up to +/-20%. Furthermore, differences between VSM and FF simulated reflectances were found to be nonlinear as a function of scattering and could not be explained with the single-scattering approximation. Additional radiance transfer modeling demonstrated that the contribution of multiple scattering to radiance reflectance increased exponentially from a minimum of 16% for pure water to a maximum of approximately 94% for turbid waters. Monte Carlo simulations demonstrated that multiple forward-scattering events were the dominant contributors to the generation of radiance reflectance signals for turbid waters and that angular structures in the shape of the VSF at forward angles could have a significant influence in determining reflectance signals for turbid waters.

  1. THE ANGULAR DISTRIBUTION OF Ly{alpha} RESONANT PHOTONS EMERGING FROM AN OPTICALLY THICK MEDIUM

    SciTech Connect

    Yang Yang; Shu Chiwang; Roy, Ishani; Fang Lizhi

    2013-07-20

    We investigate the angular distribution of Ly{alpha} photons scattering or emerging from an optically thick medium. Since the evolution of specific intensity I in frequency space and angular space are coupled with each other, we first develop the WENO numerical solver to find the time-dependent solutions of the integro-differential equation of I in frequency and angular space simultaneously. We first show that the solutions with the Eddington approximation, which assume that I is linearly dependent on the angular variable {mu}, yield similar frequency profiles of the photon flux as those without the Eddington approximation. However, the solutions of the {mu} distribution evolution are significantly different from those given by the Eddington approximation. First, the angular distribution of I is found to be substantially dependent on the frequency of the photons. For photons with the resonant frequency {nu}{sub 0}, I contains only a linear term of {mu}. For photons with frequencies at the double peaks of the flux, the {mu}-distribution is highly anisotropic; most photons are emitted radially forward. Moreover, either at {nu}{sub 0} or at the double peaks, the {mu} distributions actually are independent of the initial {mu} distribution of photons of the source. This is because the photons with frequencies either at {nu}{sub 0} or the double peaks undergo the process of forgetting their initial conditions due to resonant scattering. We also show that the optically thick medium is a collimator of photons at the double peaks. Photons from the double peaks form a forward beam with a very small opening angle.

  2. Energy distribution of elastically scattered electrons from double layer samples

    NASA Astrophysics Data System (ADS)

    Tőkési, K.; Varga, D.

    2016-02-01

    We present a theoretical description of the spectra of electrons elastically scattered from thin double layered Au-C samples. The analysis is based on the Monte Carlo simulation of the recoil and Doppler effects in reflection and transmission geometries of the scattering at a fixed angle of 44.3 ° and a primary energy of 40 keV. The relativistic correction is taken into account. Besides the experimentally measurable energy distributions the simulations give many partial distributions separately, depending on the number of elastic scatterings (single, and multiple scatterings of different types). Furthermore, we present detailed analytical calculations for the main parameters of the single scattering, taking into account both the ideal scattering geometry, i.e. infinitesimally small angular range, and the effect of the real, finite angular range used in the measurements. We show our results for intensity ratios, peak shifts and broadenings for four cases of measurement geometries and layer thicknesses. While in the peak intensity ratios of gold and carbon for transmission geometries were found to be in good agreement with the results of the single scattering model, especially large deviations were obtained in reflection geometries. The separation of the peaks, depending on the geometry and the thickness, generally smaller, and the peak width generally larger than it can be expected from the nominal values of the primary energy, scattering angle, and mean kinetic energy of the atoms. We also show that the peaks are asymmetric even for the case of the single scattering due to the finite solid angle. Finally, we present a qualitative comparison with the experimental data. We find our resulting energy distribution of elastically scattered electrons to be in good agreement with recent measurements.

  3. Equilibrium Tail Distribution Due to Touschek Scattering

    SciTech Connect

    Nash,B.; Krinsky, S.

    2009-05-04

    Single large angle Coulomb scattering is referred to as Touschek scattering. In addition to causing particle loss when the scattered particles are outside the momentum aperture, the process also results in a non-Gaussian tail, which is an equilibrium between the Touschek scattering and radiation damping. Here we present an analytical calculation for this equilibrium distribution.

  4. Angular distribution of photoelectrons from atomic oxygen, nitrogen, and carbon

    NASA Technical Reports Server (NTRS)

    Manson, S. T.; Kennedy, D. J.; Starace, A. F.; Dill, D.

    1974-01-01

    The angular distribution of photoelectrons from atomic oxygen is investigated using Hartree-Fock (HF) wave functions. The correct formulation is used to compare HS and HF results. Agreement between these results is good and the HS calculations have been extended to atomic nitrogen and carbon as well.

  5. Laser-polarization-dependent photoelectron angular distributions from polar molecules.

    PubMed

    Zhu, Xiaosong; Zhang, Qingbin; Hong, Weiyi; Lu, Peixiang; Xu, Zhizhan

    2011-11-21

    Photoelectron angular distributions (PADs) of oriented polar molecules in response to different polarized lasers are systematically investigated. It is found that the PADs of polar CO molecules show three distinct styles excited by linearly, elliptically and circularly polarized lasers respectively. In the case of elliptical polarization, a deep suppression is observed along the major axis and the distribution concentrates approximately along the minor axis. Additionally, it is also found that the concentrated distributions rotate clockwise as the ellipticity increases. Our investigation presents a method to manipulate the motion and angular distribution of photoelectrons by varying the polarization of the exciting pulses, and also implies the possibility to control the processes in laser-molecule interactions in future work.

  6. Optimization of angular compounding in scatterer size estimation

    NASA Astrophysics Data System (ADS)

    Gerig, Anthony L.; Chen, Quan; Zagzebski, James A.

    2003-10-01

    Ultrasonic scatterer size estimates generally have large variances due to the inherent noise of the spectral estimates used to calculate size. Compounding partially correlated size estimates associated with the same tissue, but produced with data acquired from different angles of incidence, is an effective way to reduce the variance without making dramatic sacrifices in spatial resolution. This work derives theoretical approximations for the correlation between these size estimates, and between their associated spectral estimates, as functions of data acquisition and processing parameters, where a Gaussian spatial autocorrelation function is assumed to adequately model scatterer shape. Size results exhibit a fair degree of agreement with those of simulation experiments, while spectral results compare favorably with simulation outcomes. Utilization of the theoretical correlation expressions for data acquisition and processing optimization is discussed. Further simplifying approximations, such as the invariance of phase and amplitude terms with rotation angle, are made in order to obtain closed-form solutions to the derived spectral correlation, and permit an analytical optimization analysis. Results indicate that recommended parameter adjustments for performance improvement depend upon whether, for the system under consideration, the primary source of estimate decorrelation with rotation is scatterer phase change or field separation. [Work supported by NIH T32CA09206.

  7. Quantum mechanical angular distributions for the F+H2 reaction

    NASA Astrophysics Data System (ADS)

    Castillo, Jesus F.; Manolopoulos, David E.; Stark, Klaus; Werner, Hans-Joachim

    1996-05-01

    Quantum mechanical integral and differential cross sections have been calculated for the title reaction at the three collision energies studied in the 1985 molecular beam experiment of Lee and co-workers, using the new ab initio potential energy surface of Stark and Werner (preceding paper). Although the overall agreement between the calculated and experimental center-of-mass frame angular distributions is satisfactory, there are still some noticeable differences. In particular, the forward scattering of HF(v'=3) is more pronounced in the present calculations than it is in the experiment and the calculations also predict some forward scattering of HF(v'=2). A comparison with the quasiclassical trajectory results of Aoiz and co-workers on the same potential energy surface shows that the forward scattering is largely a quantum mechanical effect in both cases, being dominated by high orbital angular momenta in the tunneling region where the combined centrifugal and potential energy barrier prevents classical trajectories from reacting. The possible role of a reactive scattering resonance in contributing to the quantum mechanical forward scattering is also discussed in some detail.

  8. Calculation of angular distribution of 662 keV gamma rays by Monte Carlo method in copper medium.

    PubMed

    Kahraman, A; Ozmutlu, E N; Gurler, O; Yalcin, S; Kaynak, G; Gundogdu, O

    2009-12-01

    This paper presents results on the angular distribution of Compton scattering of 662 keV gamma photons in both forward and backward hemispheres in copper medium. The number of scattered events graph has been determined for scattered gamma photons in both the forward and backward hemispheres and theoretical saturation thicknesses have been obtained using these results. Furthermore, response function of a 51 x 51 mm NaI(Tl) detector at 60 degrees angle with incoming photons scattered from a 10mm thick copper layer has been determined using Monte Carlo method.

  9. Angular scattering of light by a homogeneous spherical particle in a zeroth-order Bessel beam and its relationship to plane wave scattering.

    PubMed

    Preston, Thomas C; Reid, Jonathan P

    2015-06-01

    The angular scattering of light from a homogeneous spherical particle in a zeroth-order Bessel beam is calculated using a generalized Lorenz-Mie theory. We investigate the dependence of the angular scattering on the semi-apex angle of the Bessel beam and discuss the major features of the resulting scattering plots. We also compare Bessel beam scattering to plane wave scattering and provide criterion for when the difference between the two cases can be considered negligible. Finally, we discuss a method for characterizing spherical particles using angular light scattering. This work is useful to researchers who are interested in characterizing particles trapped in optical beams using angular dependent light scattering measurements.

  10. Statistical mechanics of collisionless orbits. IV. Distribution of angular momentum

    SciTech Connect

    Williams, Liliya L. R.; Hjorth, Jens; Wojtak, Radosław E-mail: jens@dark-cosmology.dk

    2014-03-01

    It has been shown in previous work that DARKexp, which is a theoretically derived, maximum entropy, one shape parameter model for isotropic collisionless systems, provides very good fits to simulated and observed dark matter halos. Specifically, it fits the energy distribution, N(E), and the density profiles, including the central cusp. Here, we extend DARKexp N(E) to include the distribution in angular momentum, L {sup 2}, for spherically symmetric systems. First, we argue, based on theoretical, semi-analytical, and simulation results, that while dark matter halos are relaxed in energy, they are not nearly as relaxed in angular momentum, which precludes using maximum entropy to uniquely derive N(E, L {sup 2}). Instead, we require that when integrating N(E, L {sup 2}) over squared angular momenta one retrieves the DARKexp N(E). Starting with a general expression for N(E, L {sup 2}) we show how the distribution of particles in L {sup 2} is related to the shape of the velocity distribution function, VDF, and velocity anisotropy profile, β(r). We then demonstrate that astrophysically realistic halos, as judged by the VDF shape and β(r), must have linear or convex distributions in L {sup 2}, for each separate energy bin. The distribution in energy of the most bound particles must be nearly flat, and become more tilted in favor of radial orbits for less bound particles. These results are consistent with numerical simulations and represent an important step toward deriving the full distribution function for spherically symmetric dark matter halos.

  11. Low-energy Auger electron diffraction: influence of multiple scattering and angular momentum

    NASA Astrophysics Data System (ADS)

    Chassé, A.; Niebergall, L.; Kucherenko, Yu.

    2002-04-01

    The angular dependence of Auger electrons excited from single-crystal surfaces is treated theoretically within a multiple-scattering cluster model taking into account the full Auger transition matrix elements. In particular the model has been used to discuss the influence of multiple scattering and angular momentum of the Auger electron wave on Auger electron diffraction (AED) patterns in the region of low kinetic energies. Theoretical results of AED patterns are shown and discussed in detail for Cu(0 0 1) and Ni(0 0 1) surfaces, respectively. Even though Cu and Ni are very similar in their electronic and scattering properties recently strong differences have been found in AED patterns measured in the low-energy region. It is shown that the differences may be caused to superposition of different electron diffraction effects in an energy-integrated experiment. A good agreement between available experimental and theoretical results has been achieved.

  12. Accessing the quark orbital angular momentum with Wigner distributions

    NASA Astrophysics Data System (ADS)

    Lorcé, Cédric; Pasquini, Barbara

    2013-04-01

    The quark orbital angular momentum (OAM) has been recognized as an important piece of the proton spin puzzle. A lot of effort has been invested in trying to extract it quantitatively from the generalized parton distributions (GPDs) and the transverse-momentum dependent parton distributions (TMDs), which are accessed in high-energy processes and provide three-dimensional pictures of the nucleon. Recently, we have shown that it is more natural to access the quark OAM from the phase-space or Wigner distributions. We discuss the concept of Wigner distributions in the context of quantum field theory and show how they are related to the GPDs and the TMDs. We summarize the different definitions discussed in the literature for the quark OAM and show how they can in principle be extracted from the Wigner distributions.

  13. Properties of Angular Distributions in Drell-Yan Dilepton Production

    NASA Astrophysics Data System (ADS)

    McClellan, R. Evan; Peng, Jen-Chieh; Chang, Wen-Chen; Teryaev, Oleg

    2016-09-01

    We present a simple geometric model of the Drell-Yan process based on the unobserved `natural axis' (quark-anti-quark axis) in the dilepton rest frame. We utilize this model to interpret the recent high-precision Z-boson ``Drell-Yan'' angular distributions data from CMS. We find good agreement with the pT-dependence of the angular parameters, and extract the relative contributions from the quark-anti-quark and quark-gluon subprocesses, as well as the average degree of `non-coplanarity' between the quark axis and the hadron plane. We interpret the non-coplanarity as a result of higher-order QCD contributions, and as the cause of the observed Lam-Tung violation. Supported in part by the U.S. National Science Foundation (NSF PHY 15-06416) and the National Science Council of the Republic of China.

  14. Properties of Angular Distributions in Drell-Yan Dilepton Production

    NASA Astrophysics Data System (ADS)

    McClellan, R. Evan; Peng, Jen-Chieh; Chang, Wen-Chen; Teryaev, Oleg

    2017-01-01

    We present a simple geometric model of the Drell-Yan process based on the unobserved `natural axis' (quark-anti-quark axis) in the dilepton rest frame. We utilize this model to interpret the recent high-precision Z-boson ``Drell-Yan'' angular distributions data from CMS. We find good agreement with the pT-dependence of the angular parameters, and extract the relative contributions from the quark-anti-quark and quark-gluon subprocesses, as well as the average degree of `non-coplanarity' between the quark axis and the hadron plane. We interpret the non-coplanarity as a result of higher-order QCD contributions, and as the cause of the observed Lam-Tung violation.

  15. THE ANGULAR BROADENING OF THE GALACTIC CENTER PULSAR SGR J1745-29: A NEW CONSTRAINT ON THE SCATTERING MEDIUM

    SciTech Connect

    Bower, Geoffrey C.; Deller, Adam; Falcke, Heino; Demorest, Paul; Brunthaler, Andreas; Eatough, Ralph; Kramer, Michael; Lee, K. J.; Spitler, Laura

    2014-01-01

    The pulsed radio emission from the Galactic Center (GC) pulsar SGR J1745-29 probes the turbulent, magnetized plasma of the GC hyperstrong scattering screen through both angular and temporal broadening. We present measurements of the angular size of SGR J1745-29, obtained with the Very Long Baseline Array and the phased Very Large Array at 8.7 and 15.4 GHz. The source sizes are consistent with the scatter-broadened size of Sagittarius A* at each frequency, demonstrating that SGR J1745-29 is also located behind the same scattering medium. Combining the angular broadening with temporal scattering obtained from pulsar observations provides a complete picture of the scattering properties. A best-fit solution for the distance of a single thin screen is Δ = 5.8 ± 0.3 kpc, consistent with being located in the Scutum spiral arm. The scattering is also consistent with a uniform scattering medium or a series of thin screens distributed between the GC and the Earth. This result is a substantial revision of the previously held model in which the scattering screen is located very close to the GC. As also discussed in Spitler et al., these results suggest that GC searches can detect millisecond pulsars gravitationally bound to Sgr A* with observations at ≳ 10 GHz and ordinary pulsars at even lower frequencies.

  16. Stray, swing and scatter: angular momentum evolution of orbits and streams in aspherical potentials

    NASA Astrophysics Data System (ADS)

    Erkal, Denis; Sanders, Jason L.; Belokurov, Vasily

    2016-09-01

    In aspherical potentials orbital planes continuously evolve. The gravitational torques impel the angular momentum vector to precess, that is to slowly stray around the symmetry axis, and nutate, i.e. swing up and down periodically in the perpendicular direction. This familiar orbital pole motion - if detected and measured - can reveal the shape of the underlying gravitational potential, the quantity only crudely gauged in the Galaxy so far. Here we demonstrate that the debris poles of stellar tidal streams show a very similar straying and swinging behaviour, and give analytic expressions to link the amplitude and the frequency of the pole evolution to the flattening of the dark matter distribution. While these results are derived for near-circular orbits, we show they are also valid for eccentric orbits. Most importantly, we explain how the differential orbital plane precession leads to the broadening of the stream and show that streams on polar orbits ought to scatter faster. We provide expressions for the stream width evolution as a function of the axisymmetric potential flattening and the angle from the symmetry plane and prove that our models are in good agreement with streams produced in N-body simulations. Interestingly, the same intuition applies to streams whose progenitors are on short- or long-axis loops in a triaxial potential. Finally, we present a compilation of the Galactic cold stream data, and discuss how the simple picture developed here, along with stream modelling, can be used to constrain the symmetry axes and flattening of the Milky Way.

  17. Fission fragment angular distributions in pre-actinide nuclei

    NASA Astrophysics Data System (ADS)

    Banerjee, Tathagata; Nath, S.; Jhingan, A.; Kaur, Gurpreet; Dubey, R.; Yadav, Abhishek; Laveen, P. V.; Shamlath, A.; Shareef, M.; Gehlot, J.; Saneesh, N.; Prasad, E.; Sugathan, P.; Pal, Santanu

    2016-10-01

    Background: Complete fusion of two nuclei leading to formation of a heavy compound nucleus (CN) is known to be hindered by various fission-like processes, in which the composite system reseparates after capture of the target and the projectile inside the potential barrier. As a consequence of these non-CN fission (NCNF) processes, fusion probability (PCN) starts deviating from unity. Despite substantial progress in understanding, the onset and the experimental signatures of NCNF and the degree of its influence on fusion have not yet been unambiguously identified. Purpose: This work aims to investigate the presence of NCNF, if any, in pre-actinide nuclei by systematic study of fission angular anisotropies and fission cross sections (σfis) in a number of nuclear reactions carried out at and above the Coulomb barrier (VB) . Method: Fission fragment angular distributions were measured for six 28Si-induced reactions involving isotopically enriched targets of 169Tm,176Yb,175Lu,180Hf,181Ta, and 182W leading to probable formation of CN in the pre-actinide region, at a laboratory energy (Elab) range of 129-146 MeV. Measurements were performed with large angular coverage (θlab=41∘ -170∘) in which fission fragments (FFs) were detected by nine hybrid telescope (E -Δ E ) detectors. Extracted fission angular anisotropies and σfis were compared with statistical model (SM) predictions. Results: Barring two reactions involving targets with large non-zero ground state spin (J ) , viz., 175Lu(7/2+) and 181Ta(7/2+) , experimental fission angular anisotropies were found to be higher in comparison with predictions of the statistical saddle point model (SSPM), at Ec .m . near VB. Comparison of present results with those from neighboring systems revealed that experimental anisotropies increasingly deviated from SSPM predictions as one moved from pre-actinide to actinide nuclei. For reactions involving targets with large nonzero J , this deviation was subdued. Comparison between

  18. A Wigner Distribution Analysis of Scattering Dynamics

    NASA Astrophysics Data System (ADS)

    Weeks, David; Lacy, Brent

    2009-04-01

    Using the time dependent Channel Packet Method (CPM),ootnotetextD.E.Weeks, T.A.Niday, S.H.Yang, J Chem Phys. 125, 164301 (2006). a Fourier transformation of the correlation function between evolving wave packets is used to compute scattering matrix elements. The correlation function can also be used to compute a Wigner distribution as a function of time and energy. This scattering Wigner distribution is then used to investigate times at which various energetic contributions to the scattering matrix are made during a molecular collision. We compute scattering Wigner distributions for a variety of molecular systems and use them to characterize the associated molecular dynamics. In particular, the square well provides a simple and easily modified potential to study the relationship between the scattering Wigner distribution and wave packet dynamics. Additional systems that are being studied include the collinear H + H2 molecular reaction, and the non-adiabatic B + H2 molecular collision.

  19. Neutron angular distribution in plutonium-240 spontaneous fission

    NASA Astrophysics Data System (ADS)

    Marcath, Matthew J.; Shin, Tony H.; Clarke, Shaun D.; Peerani, Paolo; Pozzi, Sara A.

    2016-09-01

    Nuclear safeguards applications require accurate fission models that exhibit prompt neutron anisotropy. In the laboratory reference frame, an anisotropic neutron angular distribution is observed because prompt fission neutrons carry momentum from fully accelerated fission fragments. A liquid organic scintillation detector array was used with pulse shape discrimination techniques to produce neutron-neutron cross-correlation time distributions and angular distributions from spontaneous fission in a 252Cf, a 0.84 g 240Pueff metal, and a 1.63 g 240Pueff metal sample. The effect of cross-talk, estimated with MCNPX-PoliMi simulations, is removed from neutron-neutron coincidences as a function of the angle between detector pairs. Fewer coincidences were observed at detector angles near 90°, relative to higher and lower detector angles. As light output threshold increases, the observed anisotropy increases due to spectral effects arising from fission fragment momentum transfer to emitted neutrons. Stronger anisotropy was observed in Cf-252 spontaneous fission prompt neutrons than in Pu-240 neutrons.

  20. Angular dependence of multiple scattered photons and saturation thickness for certain elements by gamma scattering method

    NASA Astrophysics Data System (ADS)

    Kiran, K. U.; Ravindraswami, K.; Eshwarappa, K. M.; Somashekarappa, H. M.

    2016-02-01

    Multiple scattering of gamma photons obtained from 0.215 GBq 137Cs source in both forward and backward hemisphere for 4 elements viz., carbon, aluminium, iron and copper are detected by a 76 mm ×76 mm NaI(Tl) scintillation detector. The variation of saturation thicknesses of 4 elements are studied experimentally at 60°, 80°, 90°, 100°, 120° and 135°. Monte Carlo N-Particle (MCNP) simulation of multiple scattering and variation in saturation thicknesses is carried out for 40°, 60°, 80°, 90°, 100°, 120°, 135°, 160° and 180° for four elements. The variation of the intensity of multiple scattered photons in different scattering angles is found to be different in forward and backward hemispheres. The intensity of multiple scattered photons is found to be minimum at around 90°. Saturation thicknesses for 40° and 60° are found to be less than saturation thicknesses for 80°, 90°, 100°, 120°, 135°, 160° and 180° in spite of the fact that the scattered energy is more for lower scattering angles. The behaviour of variation of saturation thicknesses as a function of scattering angles obtained from MCNP simulation agrees well with experimentally obtained values.

  1. Laboratory experiments for inter-comparison of three volume scattering meters to measure angular scattering properties of hydrosols.

    PubMed

    Harmel, T; Hieronymi, M; Slade, W; Röttgers, R; Roullier, F; Chami, M

    2016-01-25

    Measurements of the volume scattering function (VSF) of hydrosols is of primary importance to investigate the interaction of light with hydrosols and to further interpret in situ and remote sensing data of ocean color. In this paper, a laboratory inter-comparison experiment of three recently developed VSF meters that are able to measure the scattered light for a wide range of scattering angle at 515 nm wavelength is performed using phytoplankton cultures and mineral-like hydrosols. A rigorous measurement protocol was employed to ensure good quality data. In particular, the protocol enabled removing the influence of bacteria on the hydrosols within the sample. The differences in the VSF measurements between the instruments vary from 10 to 25% depending on the composition of the hydrosols. The analysis of the angular features of the VSF revealed a sharp increase of the VSF beyond the scattering angle of 150° for some phytoplankton species. Such behavior is observed for two of the three VSF meters, thus suggesting that it is not due to instrumental artifacts but more likely to phytoplankton optical properties themselves. Moreover, comparisons with currently used theoretical phase functions show that the models are not able to reproduce satisfactorily the directional patterns in the backscattering region. This study suggests that a better modelling of the VSF shape of phytoplankton at high scattering angles is required to correctly represent the angular shape of the VSF in the backscattering hemisphere. Tabulated values of the measured phase functions are provided for scattering angles from 0.1 to 175°.

  2. Capillary-scale direct measurement of hemoglobin concentration of erythrocytes using photothermal angular light scattering.

    PubMed

    Kim, Uihan; Song, Jaewoo; Lee, Donghak; Ryu, Suho; Kim, Soocheol; Hwang, Jaehyun; Joo, Chulmin

    2015-12-15

    We present a direct, rapid and chemical-free detection method for hemoglobin concentration ([Hb]), based on photothermal angular light scattering. The iron oxides contained in hemoglobin molecules exhibit high absorption of 532-nm light and generate heat under the illumination of 532-nm light, which subsequently alters the refractive index of blood. We measured this photothermal change in refractive index by employing angular light scattering spectroscopy with the goal of quantifying [Hb] in blood samples. Highly sensitive [Hb] measurement of blood samples was performed by monitoring the shifts in angularly dispersed scattering patterns from the blood-loaded microcapillary tubes. Our system measured [Hb] over the range of 0.35-17.9 g/dL with a detection limit of ~0.12 g/dL. Our sensor was characterized by excellent correlation with a reference hematology analyzer (r>0.96), and yielded a precision of 0.63 g/dL for a blood sample of 9.0 g/dL.

  3. Ion angular distribution simulation of the HEMP Thruster

    NASA Astrophysics Data System (ADS)

    Duras, Julia; Koch, Norbert; Kahnfeld, Daniel; Bandelow, Gunnar; Matthias, Paul; Lüskow, Karl Felix; Schneider, Ralf; Kemnitz, Stefan

    2016-10-01

    Ion angular current and energy distributions are important parameters for ion thrusters, which are typically measured at a few tens of centimetres to a few meters distance from thruster exit. However, fully kinetic Particle-in-Cell simulations are not able to simulate such domain sizes, due to high computational costs. Therefore, a parallelisation strategy of the code is presented to reduce computational time. To map diagnostics information from the domain boundary of the calculational domain to the positions of experimental diagnostics the concept of transfer functions is introduced. The calculated ion beam angular distributions in the plume region are quite sensitive to boundary conditions of the potential, possible additional source contributions, e.g. from secondary electron emission at vessel walls, and charge exchange collisions. This work was supported by the Bavarian State Ministry of Education Science and the Arts and the German Space Agency DLR. We also like to thank R. Heidemann from THALES Electron Devices GmbH, for interesting and stimulating discussions.

  4. Long-term variations of muon flux angular distribution

    NASA Astrophysics Data System (ADS)

    Shutenko, V. V.; Astapov, I. I.; Barbashina, N. S.; Dmitrieva, A. N.; Kokoulin, R. P.; Kompaniets, K. G.; Petrukhin, A. A.; Yashin, I. I.

    2013-02-01

    Intensity of the atmospheric muon flux depends on a number of factors: energy spectrum of primary cosmic rays (PCR), heliospheric conditions, state of the magnetosphere and atmosphere of the Earth. The wide-aperture muon hodoscope URAGAN (Moscow, Russia, 55.7° N, 37.7° E, 173 m a.s.l.) makes it possible to investigate not only variations of the intensity of muon flux, but also temporal changes of its angular distribution. For the analysis of angular distribution variations, the vector of local anisotropy is used. The vector of local anisotropy is the sum of individual vectors (directions of the reconstructed muon tracks) normalized to the total number of reconstructed tracks. The vector of local anisotropy and its projections show different sensitivities to parameters of the processes of modulation of PCR in the heliosphere and the Earth's magnetosphere, and the passage of secondary cosmic rays through the terrestrial atmosphere. In the work, results of the analysis of long-term variations of hourly average projections of the vector of local anisotropy obtained from the URAGAN data during experimental series of 2007-2011 are presented.

  5. SASER action in optically excited ruby: Angular and spectral distribution

    NASA Astrophysics Data System (ADS)

    Tilstra, L. G.; Arts, A. F. M.; de Wijn, H. W.

    2007-12-01

    Selective pulsed optical excitation is used in 500-at.ppm ruby (Al2O3:Cr3+) at 1.4 K to prepare complete population inversion of the Zeeman-split bar E(2E) doublet in a zone of limited size. The inversion results in prolific stimulated emission of phonons resonant with the one-phonon transition connecting the doublet states. The phonons are detected via the R1 luminescence. The angular and spectral distributions of the associated acoustic wave are measured using a geometry with inverted zones at either end of the crystal, one serving as generator and the other as detector. The divergence appears to be governed by the geometry of the zone, while the spectral distribution is, within errors, in keeping with the inhomogeneously broadened phonon transition.

  6. Spin O decay angular distribution for interfering mesons in electroproduction

    SciTech Connect

    Funsten, H.; Gilfoyle, G.

    1994-04-01

    Self analyzing meson electroproduction experiments are currently being planned for the CEBAF CLAS detector. These experiments deduce the spin polarization of outgoing unstable spin s (?)0 mesons from their decay angular distribution, W({theta},{psi}). The large angular acceptance of the CLAS detector permits kinematic tracking of a sufficient number of these events to accurately determine electroproduction amplitudes from the deduced polarization. Maximum polarization information is obtained from W({theta},{psi}) for decay into spin 0 daughters. The helicity of the decaying meson is transferred to the daughter`s relative orbital angular momentum m-projection; none is {open_quotes}absorbed{close_quotes} into daughter helicities. The decaying meson`s helicity maximally appears in W({theta},{psi}). W({theta},{psi}) for spin 0 daughters has been derived for (1) vector meson electroproduction and (2) general interfering mesons produced by incident pions. This paper derives W({theta},{psi}) for electroproduction of two interfering mesons that decay into spin 0 daughters. An application is made to the case of interfering scalar and vector mesons. The derivation is an extension of work by Schil using the general decay formalism of Martin. The expressions can be easily extended to the case of N interfering mesons since interference occurs pairwise in the observable W ({theta},{psi}), a quadratic function of the meson amplitudes. The derivation uses the virtual photon density matrix of Schil which is transformed by a meson electroproduction transition operator, T. The resulting density matrix for the interfering mesons is then converted into a corresponding statistical tensor and contracted into the efficiency tensor for spin 0 daughters.

  7. DISTRIBUTION OF ACCRETING GAS AND ANGULAR MOMENTUM ONTO CIRCUMPLANETARY DISKS

    SciTech Connect

    Tanigawa, Takayuki; Ohtsuki, Keiji; Machida, Masahiro N.

    2012-03-01

    We investigate gas accretion flow onto a circumplanetary disk from a protoplanetary disk in detail by using high-resolution three-dimensional nested-grid hydrodynamic simulations, in order to provide a basis of formation processes of satellites around giant planets. Based on detailed analyses of gas accretion flow, we find that most of gas accretion onto circumplanetary disks occurs nearly vertically toward the disk surface from high altitude, which generates a shock surface at several scale heights of the circumplanetary disk. The gas that has passed through the shock surface moves inward because its specific angular momentum is smaller than that of the local Keplerian rotation, while gas near the midplane in the protoplanetary disk cannot accrete to the circumplanetary disk. Gas near the midplane within the planet's Hill sphere spirals outward and escapes from the Hill sphere through the two Lagrangian points L{sub 1} and L{sub 2}. We also analyze fluxes of accreting mass and angular momentum in detail and find that the distributions of the fluxes onto the disk surface are well described by power-law functions and that a large fraction of gas accretion occurs at the outer region of the disk, i.e., at about 0.1 times the Hill radius. The nature of power-law functions indicates that, other than the outer edge, there is no specific radius where gas accretion is concentrated. These source functions of mass and angular momentum in the circumplanetary disk would provide us with useful constraints on the structure and evolution of the circumplanetary disk, which is important for satellite formation.

  8. Evidence for the distribution of angular velocity inside the sun and stars

    NASA Technical Reports Server (NTRS)

    1972-01-01

    A round table discussion of problems of solar and stellar spindown and theory is presented. Observational evidence of the angular momentum of the solar wind is included, emphasizing the distribution of angular velocity inside the sun and stars.

  9. Mass distribution and mass resolved angular distribution of fission products in 28Si+232Th

    NASA Astrophysics Data System (ADS)

    Sodaye, Suparna; Tripathi, R.; John, B. V.; Ramachandran, K.; Pujari, P. K.

    2017-01-01

    Background: Fission process with heavier projectiles and actinide targets has contributions from processes, such as compound nucleus fission, transfer-induced fission, and noncompound nucleus fission. Mass distribution and mass-dependent anisotropy can be used to identify and delineate the contributions due to these different processes. Purpose: Mass distribution in 28Si+232Th has been studied at beam energies of 180 and 158 MeV to investigate the nature of mass distribution arising from complete and incomplete momentum-transfer fission events. Mass-dependent angular anisotropy has been measured at 166 MeV to investigate the dominant noncompound nucleus process contributing to the fission. Method: Mass distribution and mass resolved angular distribution of fission products were measured by the recoil catcher method followed by off-line γ -ray spectrometry. Results: Mass distributions for full momentum-transfer fission processes were found to be symmetric, and those for transfer-induced fission were found to be asymmetric at both beam energies. The relative contribution from transfer-induced fission was found to be higher at lower beam energy. The anisotropy of the fission product angular distribution was found to increase with decreasing mass asymmetry. Conclusions: The mass distribution indicates that, apart from the full momentum-transfer fission process, there is a significant contribution due to transfer-induced fission. The mass dependence of angular anisotropy indicated that preequilibrium fission is the dominant noncompound nucleus process in the present reaction system at near barrier energy (Ec .m ./VC=1.06 ) .

  10. Time-dependent treatment of electron-hydrogen scattering for higher angular momenta (L>0)

    NASA Astrophysics Data System (ADS)

    Odero, D. O.; Peacher, J. L.; Schultz, D. R.; Madison, D. H.

    2001-02-01

    The time-dependent approach to electron-atom scattering is emerging as an alternative to more conventional methods of treating atomic collisions. Solving the time-dependent Schrödinger equation directly has several very attractive features including a completely nonperturbative solution, dense representation of the nonphysical positive energy states, circumvention of the need to explicitly impose boundary conditions for ionization, and the convenience of being able to ``watch'' the electronic probability density evolve though the collision. Two principal approaches have so far been applied to treat electron-atom scattering, namely, the time-dependent close couping (TDCC) method and what we refer to as the time-dependent Hylleraas (TDH) method. The TDCC method solves coupled equations with two variables within a truncated infinite sum over individual angular momenta for each total angular momentum L of the system. In contrast, the TDH method avoids an infinite summation over the angular momenta of the individual electrons at the expense of solving a coupled equation with three variables for each L. The TDH method has previously been used for L=0 only. An important question, therefore, concerns whether the TDH method would represent a numerical advantage over the TDCC method for higher L values. This issue is investigated in this paper.

  11. Method for improving the angular resolution of a neutron scatter camera

    SciTech Connect

    Mascarenhas, Nicholas; Marleau, Peter; Gerling, Mark; Cooper, Robert Lee; Mrowka, Stanley; Brennan, James S.

    2012-12-25

    An instrument that will directly image the fast fission neutrons from a special nuclear material source wherein the neutron detection efficiency is increased has been described. Instead of the previous technique that uses a time-of-flight (TOF) between 2 widely spaced fixed planes of neutron detectors to measure scatter neutron kinetic energy, we now use the recoil proton energy deposited in the second of the 2 scatter planes which can now be repositioned either much closer together or further apart. However, by doubling the separation distance between the 2 planes from 20 cm to a distance of 40 cm we improved the angular resolution of the detector from about 12.degree. to about 10.degree.. A further doubling of the separation distance to 80 cm provided an addition improvement in angular resolution of the detector to about 6.degree. without adding additional detectors or ancillary electronics. The distance between planes also may be dynamically changed using a suitable common technique such as a gear- or motor-drive to toggle between the various positions. The angular resolution of this new configuration, therefore, is increased at the expanse of detection sensitivity. However, the diminished sensitivity may be acceptable for those applications where the detector is able to interrogate a particular site for an extended period.

  12. Photoelectron angular distributions of ultrathin Ni/Cu(001) films

    SciTech Connect

    Mankey, G.J.; Subramanian, K.; Stockbauer, R.L.; Kurtz, R.L.

    1996-12-31

    The authors present measurements of the evolution with film thickness of the 3d electronic states at the Fermi energy of ultrathin Ni films. The morphology and thickness of the films is determined from x-ray photoelectron spectroscopy, x-ray photoelectron diffraction and x-ray magnetic linear dichroism using synchrotron radiation. Photoelectron angular distributions were measured using an ellipsoidal mirror analyzer. Even at submonolayer Ni coverages, the 3d electronic states exhibit bulk-like properties. This is attributed to the short screening length of electrons in metals, the localization of the 3d electrons, the similarity of the Ni and Cu ion cores, and finally the interaction with the underlying fcc periodic potential.

  13. Photoelectron Angular Distribution and Molecular Structure in Multiply Charged Anions

    SciTech Connect

    Xing, Xiaopeng; Wang, Xue B.; Wang, Lai S.

    2009-02-12

    Photoelectrons emitted from multiply charged anions (MCAs) carry information of the intramolecular Coulomb repulsion (ICR), which is dependent on molecular structures. Using photoelectron imaging, we observed the effects of ICR on photoelectron angular distributions (PAD) of the three isomers of benzene dicarboxylate dianions C6H4(CO2)22– (o-, m- and p-BDC2–). Photoelectrons were observed to peak along the laser polarization due to the ICR, but the anisotropy was the largest for p-BDC2–, followed by the m- and o-isomer. The observed anisotropy is related to the direction of the ICR or the detailed molecular structures, suggesting that photoelectron imaging may allow structural information to be obtained for complex multiply charged anions.

  14. Threshold photoneutron angular distribution and polarization studies of nuclei

    SciTech Connect

    Holt, R.J.

    1980-01-01

    The photoneutron method was applied to the study of: (1) deuteron photodisintegration; (2) giant magnetic dipole resonances in heavy nuclei; (3) mechanism of radiative capture in light nuclei; and (4) isospin splitting of the giant dipole resonance in /sup 60/Ni. These studies were performed with the pulsed bremsstrahlung beam and high-resolution spectrometer available at the Argonne high-current electron linac. A threshold photoneutron polarization method was developed in order to search for the giant M1 resonance in heavy nuclei. A surprisingly small amount of M1 strength was found in /sup 208/Pb. Furthermore, the M1 strength for the 5.08-MeV excitation in /sup 17/O, the best example of a single-particle M1 resonance in nuclei, was found to be strongly quenched. In addition, the /sup 17/O(..gamma..,n/sub 0/)/sup 16/O reaction was found to provide an ideal example of the Lane-Lynn theory of radiative capture. The interplay among the three components of the theory, internal, channel and potential capture, were evident from the data. An electron beam transport system was developed which allows the bremsstrahlung to impinge on the photoneutron target on an axis perpendicular to the usual reaction plane. This system provides an accurate method for the measurement of relative angular distributions in (..gamma..,n) reactions. This system was applied to a high-accuracy measurement of the relative angular distribution for the D(..gamma..,n)H reaction. The question of isospin-splitting of the giant dipole resonance in /sup 60/Ni was studied by using the unique pico-pulse from the accelerator and the newly installed 25-m, neutron flight paths. The results provide clear evidence for the effect of isospin splitting.

  15. Influence of the angular scattering of electrons on the runaway threshold in air

    NASA Astrophysics Data System (ADS)

    Chanrion, O.; Bonaventura, Z.; Bourdon, A.; Neubert, T.

    2016-04-01

    The runaway electron mechanism is of great importance for the understanding of the generation of x- and gamma rays in atmospheric discharges. In 1991, terrestrial gamma-ray flashes (TGFs) were discovered by the Compton Gamma-Ray Observatory. Those emissions are bremsstrahlung from high energy electrons that run away in electric fields associated with thunderstorms. In this paper, we discuss the runaway threshold definition with a particular interest in the influence of the angular scattering for electron energy close to the threshold. In order to understand the mechanism of runaway, we compare the outcome of different Fokker-Planck and Monte Carlo models with increasing complexity in the description of the scattering. The results show that the inclusion of the stochastic nature of collisions smooths the probability to run away around the threshold. Furthermore, we observe that a significant number of electrons diffuse out of the runaway regime when we take into account the diffusion in angle due to the scattering. Those results suggest using a runaway threshold energy based on the Fokker-Planck model assuming the angular equilibrium that is 1.6 to 1.8 times higher than the one proposed by [1, 2], depending on the magnitude of the ambient electric field. The threshold also is found to be 5 to 26 times higher than the one assuming forward scattering. We give a fitted formula for the threshold field valid over a large range of electric fields. Furthermore, we have shown that the assumption of forward scattering is not valid below 1 MeV where the runaway threshold usually is defined. These results are important for the thermal runaway and the runaway electron avalanche discharge mechanisms suggested to participate in the TGF generation.

  16. Optical Properties Of Solid Particle Receiver Materials I: Angular Scattering And Extinction Characteristics Of Norton Masterbeads

    NASA Astrophysics Data System (ADS)

    Griffin, J. W.; Stahl, K. A.; Pettit, R. B.

    1985-12-01

    As part of the Solar Thermal Technology Program, the direct absorption of sunlight by free-falling particles inside a cavity receiver is being evaluated. The objective of the on-going optical properties measurement program is to obtain information to be used as input to radiation transfer models for prediction of receiver performance. Instrumenta tion and data analysis techniques have been developed to determine both the angular scattering properties and the scattering and absorption components of the extinction coefficient of candidate materials. This report summarizes the measurement procedures and presents data for an ion-doped alumina spheroid, Masterbeads, manufactured by Norton Chemical Company. This material exhibits good optical absorption properties over the solar insolation spectrum and favorable thermal and mechanical properties for temperatures up to 1000°C. Scattering and extinction measurements were performed at 632.8 nm in a falling curtain geometry of one-particle nominal thickness. Data were obtained over a range of mass flow rates and particle areal densities. Photographic documentation of curtain particle density enabled calculation of mean particle scattering and absorption loss components in the absence of multiple-particle optical interactions. Prediction of optical extinction properties at other wavelengths is anticipated to be straightforward using spectral hemispherical reflectance measurements on bulk samples. Additional scattering and extinction data were obtained on transparent glass microspheres for comparison and as a verification of the measurement apparatus and procedures.

  17. The distribution of mass and angular momentum in the solar system

    SciTech Connect

    Marochnik, L.S.; Mukhin, L.M.; Sagdeev, R.Z. )

    1989-01-01

    This book describes the contribution of the comets in the Oort cloud to the angular momentum of the solar system. Topics covered include: Nuclear mass of the new comets observed, Mass of the Oort cloud, Mass distribution in the solar system, Zone of comet formation, Angular momentum of the Oort cloud, and Angular momentum of the Hills cloud.

  18. On the angular dependence and scattering model of polar mesospheric summer echoes at VHF

    NASA Astrophysics Data System (ADS)

    Sommer, Svenja; Stober, Gunter; Chau, Jorge L.

    2016-01-01

    We present measurements of the angular dependence of polar mesospheric summer echoes (PMSE) with the Middle Atmosphere Alomar Radar System in Northern Norway (69.30° N, 16.04° E). Our results are based on multireceiver and multibeam observations using beam pointing directions with off-zenith angles up to 25° as well as on spatial correlation analysis (SCA) from vertical beam observations. We consider a beam filling effect at the upper and lower boundaries of PMSE in tilted beams, which determines the effective mean angle of arrival. Comparing the average power of the vertical beam to the oblique beams suggests that PMSE are mainly not as aspect sensitive as in contrast to previous studies. However, from SCA, times of enhanced correlation are found, indicating aspect sensitivity or a localized scattering mechanism. Our results suggest that PMSE consist of nonhomogeneous isotropic scattering and previously reported aspect sensitivity values might have been influenced by the inhomogeneous nature of PMSE.

  19. Angular source size measurements and interstellar scattering at 103 MHz using interplanetary scintillation

    NASA Astrophysics Data System (ADS)

    Janardhan, P.; Alurkar, S. K.

    1993-03-01

    Data obtained between 1984 and 1987, using a radio telescope (RT) with a 10,000 sq m dipole array operating at 103 MHz, was used to determine the angular diameters of fourteen strongly scintillating radio sources. The method used exploited the technique of interplanetary scintillation (IPS), wherein the systematic variation of scintillation index with solar elongation was used as a unique indicator of the source size. The method has been used before but these are the first measurements at 103 MHz. These values were then used in conjunction with similar available measurements at 151.5 MHz to determine the contribution of interstellar scattering (ISS) to source broadening at 103 MHz. Enhanced scattering due to ISS in the plane of the galaxy has been confirmed.

  20. Angular Distributions of Sputtered Atoms from Semiconductor Targets at Grazing Ion Beam Incidence Angles

    SciTech Connect

    Sekowski, M.; Burenkov, A.; Martinez-Limia, A.; Hernandez-Mangas, J.; Ryssel, H.

    2008-11-03

    Angular distributions of ion sputtered germanium and silicon atoms are investigated within this work. Experiments are performed for the case of grazing ion incidence angles, where the resulting angular distributions are asymmetrical with respect to the polar angle of the sputtered atoms. The performed experiments are compared to Monte-Carlo simulations from different programs. We show here an improved model for the angular distribution, which has an additional dependence of the ion incidence angle.

  1. Photoelectron angular distributions as a probe of anisotropic electron-ion interactions

    NASA Technical Reports Server (NTRS)

    Dill, D.; Manson, S. T.; Starace, A. F.

    1974-01-01

    Expressions are given for atomic photoelectron angular distributions in LS coupling in which the role of anisotropic final state electron-ion interactions emerges explicitly. Calculations of photoelectron angular distributions for atomic sulfur are presented in which these anisotropic interactions produce pronounced deviations from the predictions of the Cooper-Zare model. Such effects are expected to be a general feature of photoelectron angular distributions for most open shell atoms.

  2. Photoelectron angular distributions as a probe of anisotropic electron-ion interactions

    NASA Technical Reports Server (NTRS)

    Dill, D.; Manson, S. T.; Starace, A. F.

    1974-01-01

    Expressions are given for atomic photoelectron angular distributions in LS coupling in which the role of anisotropic final state electron-ion interactions emerges explicitly. Calculations of photoelectron angular distributions for atomic sulfur are presented in which these anisotropic interactions produce clear deviations from the predictions of the Cooper-Zare model. Such effects are expected to be a general feature of photoelectron angular distributions for most open-shell atoms.

  3. Polarized angular dependent light scattering from plasmonic nanoparticles: Modeling, measurements, and biomedical applications

    NASA Astrophysics Data System (ADS)

    Fu, Kun

    Several significant applications have been realized for light scattering in biomedical imaging. In order to improve imaging results with light scattering-based techniques, a variety of nanoparticles have been investigated as contrast agents, including gold nanoshells. As a method for studying the optical properties of plasmonic gold nanoparticles used as contrast agents for molecular imaging, we developed an automated goniometer instrumentation system. This system, which allows us to specifically study polarized angular-dependent light scattering of plasmonic nanoparticles, allowed us to perform a series of theoretical and experimental step-wise studies. The basic optical properties of the following gold nanoparticles were progressively investigated: (1) bare nanoshells at multipolar plasmonic resonances, (2) nanoshells with PEG modifications, (3) surface-textured nanoshells and (4) immunotargeted nanoshells (nanoshell-antibody bioconjugates) for cancer imaging. Based on the results from these studies, a new technique was developed to quantitatively measure the number of immunotargeted nanoparticles that bind to HER2-positive SKBR3 human breast cancer cells. Preliminary studies of determining the minimal incubation time of immunotargeted nanoshells with SKBR3 cells were also carried out to evaluate the potential clinical application of using gold nanoshells intraoperatively. We, therefore, anticipate that our findings will provide the theoretical groundwork required for further studies aimed at optimizing the application of plasmonic nanoparticles in scattering-based optical imaging techniques.

  4. Small Deflection Energy Analyzer for Energy and Angular Distributions

    NASA Technical Reports Server (NTRS)

    Herrero, Federico A.

    2009-01-01

    The development of the Small Deflection Energy Analyzer (SDEA) charged-particle spectrometer for energy and angle distributions responds to a longstanding need to measure the wind velocity vector in Earth s thermosphere, and to obtain the ion-drift vector in the ionosphere. The air and ions above 120 km are endowed with bulk velocities and temperatures just like air near the ground, but with separate spatial and temporal variations. It is important to understand these not only for study of the physics and chemistry of the Sun-Earth connection, but also for spacecraft orbit predictions, and communications through the ionosphere. The SDEA consists of a pair of parallel conducting plates separated by a small distance, with an entrance slit on one end, and an exit slit on the other. A voltage applied to these plates develops an electric field between the plates, and this field deflects ions passing through it. If an ion has too little energy, it will strike one of the plates. If it has too much, it will strike the back wall. An ion with the amount of energy being searched for will have its trajectory bent just enough to exit the back slit. The SDEA units are compact, rectangular, and operate with low voltages. The units can be built up into small arrays. These arrays could be used either to widen the field of view or to sharpen an existing one. This approach can also be used to obtain angular distributions in two planes simultaneously, thus cutting down the ion source power requirements in half. This geometry has enabled a new mass-spectrometer concept that can provide miniaturized mass spectrometers for use in industrial plants, air-pollution monitoring, and noxious-gas detection.

  5. The Angular Momentum Distribution within Dark Matter Halos

    NASA Astrophysics Data System (ADS)

    Chen, D.; Jing, Y.

    We study the angular momentum profile of dark matter halos for a statistical sample drawn from a set of high-resolution cosmological simulations of 2563 particles. Two typical Cold Dark Matter (CDM) models have been analyzed, and the halos are selected to have at least 3× 104 particles in order to reliably measure the angular momentum profile. In contrast with the recent claims of Bullock et al. (2001), we find that the degree of misalignment of angular momentum within a halo is very high. About 50 percent of halos have more than 10 percent of halo mass in the mass of negative angular momentum j. After the mass of negative j is excluded, the cumulative mass function M(angular momentum profile of halos in a Warm Dark Matter (WDM) model and a Self-Interacting Dark Matter (SIDM) model. We find that the angular momentum profile of halos in the WDM is statistically indistinguishable from that in the CDM model, but the angular momentum of halos in the SIDM is reduced by the self-interaction of dark matter.

  6. Over-cosine angular distributions of sputtered atoms at normal incidence

    NASA Astrophysics Data System (ADS)

    Yamamura, Y.; Muraoka, K.

    1989-06-01

    The angular distribution of sputtered atoms for normal incidence ions has been investigated theoretically and by computer simulation. For low energy ions the angular distribution is under-cosine, while for relatively high energy ions we obtain an over-cosine angular distribution for the sputtered atoms. It is found that the outward-peakness of the angular distribution for relatively high energy ions is due to the geometrical asymmetry near the surface. Using the Monte Carlo simulation code ACAT, which is based on the binary collision approximation, the angular distributions of sputtered atoms are calculated for various incident energies of Ar ions incident normally on an Fe target. It is found that one needs to take into account the surface roughness in order to obtain good agreement with experiment. The surface roughness is believed to reduce the degree of the over-cosine distribution because a rough surface has a larger effective surface area as compared with an unirradiated surface.

  7. Prediction of angular distributions for the F+H/sub 2/ and F+D/sub 2/ reactions

    SciTech Connect

    Hayes, E.F.; Walker, R.B.

    1988-05-01

    The bending corrected rotating linear model is used to predict angular distributions for the reactions F+H/sub 2/(v = 0)..-->..H+HF(v' = 2,3) and and F+D/sub 2/(v = 0)..-->..D+DF(v' = 3,4). The calculations were performed using the surface (No. 5A) that was reported recently by Steckler, Truhlar, and Garrett. The angular distributions obtained using this new surface differ in several important respects from distributions predicted in earlier quantal scattering studies using the Muckerman-5 surface. More importantly, these new predictions are in much better agreement with the high resolution molecular beam studies of these same reactions. The combination of these predictions with the results of the molecular beam studies provides additional evidence for the role of dynamical resonances in the two title reactions.

  8. Distributed angular double-slit interference with pseudo-thermal light

    NASA Astrophysics Data System (ADS)

    Gao, Lu; Hashemi Rafsanjani, Seyed Mohammad; Zhou, Yiyu; Yang, Zhe; Magaña-Loaiza, Omar S.; Mirhosseini, Mohammad; Zhao, Jiapeng; Gao, Boshen; Boyd, Robert W.

    2017-02-01

    We propose and perform an interference experiment involving a distributed angular double-slit and the orbital angular momentum (OAM) correlations of thermal light. In the experiment, two spatially separated angular apertures are placed in two correlated light beams generated by splitting the thermal light beam via a beam splitter. The superposition of the two spatially separated slits constitutes an angular double-slit in two-photon measurements. The angular interference pattern of the distributed double-slit is measured even though each beam interacts with a different part of the object. This scheme allows us to discriminate among different angular amplitude objects using a classical incoherent light source. This procedure has potential applications in remote sensing or optical metrology in the OAM domain.

  9. K-shell photoionization of CO: I. Angular distributions of photoelectrons from fixed-in-space molecules

    NASA Astrophysics Data System (ADS)

    Motoki, S.; Adachi, J.; Hikosaka, Y.; Ito, K.; Sano, M.; Soejima, K.; Yagishita, A.; Raseev, G.; Cherepkov, N. A.

    2000-10-01

    Angular distributions of photoelectrons from both C and O K-shells of the fixed-in-space CO molecule have been measured using the angle-resolved photoelectron-photoion coincidence technique. The measurements have been performed at several photon energies from the ionization thresholds up to about 30 eV above them, where the σ* shape resonances occur. Experimental results are compared with the multiple-scattering calculations of Dill et al (1976 J. Chem. Phys. 65 3158) and with our new calculations in the relaxed-core Hartree-Fock approximation. Our calculations are in a better agreement with the experimental data though numerical discrepancies remain. The experimental angular distributions are fitted by the expansion in Legendre polynomials containing up to ten terms and the extracted parameters are compared with the corresponding theoretical values.

  10. Stimulated scattering of electromagnetic waves carrying orbital angular momentum in quantum plasmas.

    PubMed

    Shukla, P K; Eliasson, B; Stenflo, L

    2012-07-01

    We investigate stimulated scattering instabilities of coherent circularly polarized electromagnetic (CPEM) waves carrying orbital angular momentum (OAM) in dense quantum plasmas with degenerate electrons and nondegenerate ions. For this purpose, we employ the coupled equations for the CPEM wave vector potential and the driven (by the ponderomotive force of the CPEM waves) equations for the electron and ion plasma oscillations. The electrons are significantly affected by the quantum forces (viz., the quantum statistical pressure, the quantum Bohm potential, as well as the electron exchange and electron correlations due to electron spin), which are included in the framework of the quantum hydrodynamical description of the electrons. Furthermore, our investigation of the stimulated Brillouin instability of coherent CPEM waves uses the generalized ion momentum equation that includes strong ion coupling effects. The nonlinear equations for the coupled CPEM and quantum plasma waves are then analyzed to obtain nonlinear dispersion relations which exhibit stimulated Raman, stimulated Brillouin, and modulational instabilities of CPEM waves carrying OAM. The present results are useful for understanding the origin of scattered light off low-frequency density fluctuations in high-energy density plasmas where quantum effects are eminent.

  11. A new low-complexity angular spread estimator in the presence of line-of-sight with angular distribution selection

    NASA Astrophysics Data System (ADS)

    Bousnina, Inès; Stéphenne, Alex; Affes, Sofiène; Samet, Abdelaziz

    2011-12-01

    This article treats the problem of angular spread (AS) estimation at a base station of a macro-cellular system when a line-of-sight (LOS) is potentially present. The new low-complexity AS estimator first estimates the LOS component with a moment-based K-factor estimator. Then, it uses a look-up table (LUT) approach to estimate the mean angle of arrival (AoA) and AS. Provided that the antenna geometry allows it, the new algorithm can also benefit from a new procedure that selects the angular distribution of the received signal from a set of possible candidates. For this purpose, a nonlinear antenna configuration is required. When the angular distribution is known, any antenna structure could be used a priori; hence, we opt in this case for the simple uniform linear array (ULA). We also compare the new estimator with other low-complexity estimators, first with Spread Root-MUSIC, after we extend its applicability to nonlinear antenna array structures, then, with a recently proposed two-stage algorithm. The new AS estimator is shown, via simulations, to exhibit lower estimation error for the mean AoA and AS estimation.

  12. Modification of the photoelectron angular distribution through laser-induced continuum structure

    SciTech Connect

    Nakajima, Takashi; Buica, Gabriela

    2005-01-01

    We theoretically investigate how the photoelectron angular distribution is altered by the introduction of a dressing laser. The physical mechanism underlying this alteration is the so-called laser-induced continuum structure; namely, a strong dressing laser induces quantum mechanical interference, the degree of which is different for different ionization channels. Therefore the branching ratio into different ionization channels changes as a function of laser detuning, and accordingly the photoelectron angular distribution is altered. After a general argument, we present specific theoretical results for the K atom, which indeed exhibit significant modification of the photoelectron angular distribution.

  13. Angular Scattering Reflectance and Polarization Measurements of Candidate Regolith Materials Measured in the Laboratory

    NASA Astrophysics Data System (ADS)

    Nelson, Robert M.; Boryta, Mark D.; Hapke, Bruce W.; Shkuratov, Yuriy; Vandervoort, Kurt; Vides, Christina L.

    2016-10-01

    The reflectance and polarization of light reflected from a solar system object indicates the chemical and textural state of the regolith. Remote sensing data are compared to laboratory angular scattering measurements and surface properties are determined.We use a Goniometric Photopolarimeter (GPP) to make angular reflectance and polarization measurements of particulate materials that simulate planetary regoliths. The GPP employs the Helmholtz Reciprocity Principle ( 2, 1) - the incident light is linearly polarized - the intensity of the reflected component is measured. The light encounters fewer optical surfaces improving signal to noise. The lab data are physically equivalent to the astronomical data.Our reflectance and polarization phase curves of highly reflective, fine grained, media simulate the regolith of Jupiter's satellite Europa. Our lab data exhibit polarization phase curves that are very similar to reports by experienced astronomers (4). Our previous reflectance phase curve data of the same materials agree with the same astronomical observers (5). We find these materials exhibit an increase in circular polarization ratio with decreasing phase angle (3). This suggests coherent backscattering (CB) of photons in the regolith (3). Shkuratov et al.(3) report that the polarization properties of these particulate media are also consistent with the CB enhancement process (5). Our results replicate the astronomical data indicating Europa's regolith is fine-grained, high porous with void space exceeding 90%.1. Hapke, B. W. (2012). ISBN 978-0-521-88349-82. Minnaert, M. (1941).Asrophys. J., 93, 403-410.3. Nelson, R. M. et al. (1998). Icarus, 131, 223-230.4. Rosenbush, V. et al. (2015). ISBN 978-1-107-04390-9, pp 340-359.5. Shkuratov, Yu. et al. (2002) Icarus 159, 396-416.

  14. Angular Scattering Dynamics of the CH4 + Cl → CH3 + HCl Reaction Using Nearside-Farside, Local Angular Momentum, and Resummation Theories.

    PubMed

    Totenhofer, A J; Connor, J N L; Nyman, Gunnar

    2016-03-03

    The differential cross section (DCS) for the CH4 + Cl → CH3 + HCl reaction is studied at six total energies where all of the species are in their ground states. The scattering (S) matrix elements have been calculated by the rotating line umbrella method for a dual-level ab initio analytic potential energy surface. We make the first application to this reaction of nearside-farside (NF) and local angular momentum (LAM) techniques, including resummation orders (r) of 0, 1, 2, and 3 for the partial-wave series representation of the full scattering amplitude. We find that resummation usually cleans the NF r = 0 DCSs of unphysical oscillations, especially at small angles. This cleaning effect is typically most pronounced when changing from no resummation (r = 0) to r = 1; further resummations from r = 1 to r = 2 and from r = 2 to r = 3 have smaller effects. The NF DCS analyses show that the reaction is N-dominated at sideward and large angles, whereas at small angles there are oscillations caused by NF interference. The NF LAM analysis provides consistent and complementary information, in particular for the total angular momenta that contribute to the reaction at different scattering angles. The NF analyses also provide justification for simpler N-dominant dynamical theories such as the semiclassical optical model, which provides an explanation for the distorted mirror image effect for the moduli of the S matrix elements and the DCSs, as well as the use of a hard-sphere DCS over limited angular ranges.

  15. Determination of the angular and energy dependence of hard constituent scattering from. pi. /sup 0/ pair events at the CERN intersecting storage rings

    SciTech Connect

    Angelis, A.L.S.; Besch, H.J.; Blumenfeld, B.J.

    1982-08-23

    We present data on proton-proton collisions, obtained at the CERN Intersecting Storage Rings, in which two roughly back-to-back ..pi../sup 0/'s of high transverse momentum (p/sub T/) were produced. The angular distribution of the dipion axis relative to the collision axis is found to be independent of both the effective mass m of the dipion system and the centre-of-mass energy ..sqrt..s of the proton-proton collision. The cross-sections dsigma/dm at the two values of ..sqrt..s satisfy a scaling law of the form dsigma/dm = G(x)/m/sup n/, where x = m(..pi../sup 0/,..pi../sup 0/)/..sqrt..s and n = 6.5 +- 0.5. We show from our data that the leading ..pi../sup 0/ carries most of the momentum of the scattered parton. Given this fact, the axis of the dipion system follows closely the direction of the scattered constituents, and we exploit this to determine the angular dependence of the hard-scattering subprocess. We also compare our data with the lowest order QCD predictions using structure functions as determined in deep-inelastic scattering and fragmentation functions from electron-positron annihilation.

  16. Molecular above-threshold-ionization angular distributions with attosecond bichromatic intense XUV laser pulses

    NASA Astrophysics Data System (ADS)

    Yuan, Kai-Jun; Bandrauk, André D.

    2012-01-01

    Angular distributions of molecular above-threshold ionization (MATI) in bichromatic attosecond extreme ultraviolet (XUV) linear polarization laser pulses have been theoretically investigated. Multiphoton ionization in a prealigned molecular ion H2+ produces clear MATI spectra which show a forward-backward asymmetry in angular and momentum distributions which is critically sensitive to the carrier envelope phase (CEP) φ, the time delay Δτ between the two laser pulses, and the photoelectron kinetic energies Ee. The features of the asymmetry in MATI angular distributions are described well by multiphoton perturbative ionization models. Phase differences of continuum electron wave functions can be extracted from the CEP φ and time delay Δτ dependent ionization asymmetry ratio created by interfering multiphoton ionization pathways. At large internuclear distances MATI angular distributions exhibit more complex features due to laser-induced electron diffraction where continuum electron wavelengths are less than the internuclear distance.

  17. Cross sections, momentum distributions, and neutron angular distributions for 11Be induced reactions on silicon

    NASA Astrophysics Data System (ADS)

    Negoita, F.; Borcea, C.; Carstoiu, F.; Lewitowicz, M.; Saint-Laurent, M. G.; Anne, R.; Guillemaud-Mueller, D.; Mueller, A. C.; Pougheon, F.; Sorlin, O.; Fomitchev, A.; Lukyanov, S.; Penionzhkevich, Yu.; Skobelev, N.; Dlouhy, Z.

    1999-04-01

    The halo neutron breakup cross section for 11Be on Si has been obtained in a wide energy range by applying an integral method and separately determining the contributions of stripping and dissociation mechanisms. A new breakup mechanism, for which the core energy is strongly dumped, has also been observed. Parallel momentum distributions of 10Be resulting from breakup have been deduced for both stripping and dissociation and angular and energy distributions of the neutrons coincident with different reaction products have been measured. Charge changing cross sections for 10,11Be complemented the measurements. An extended Glauber model has been elaborated in order to provide a unitary interpretation for all the data. It takes into account both the specific structure of 11Be and the reaction mechanism, practically without free parameters. The effects of reaction mechanisms on the widths of observed momentum distributions are particularly important.

  18. Nonstandard Higgs couplings from angular distributions in [Formula: see text].

    PubMed

    Buchalla, Gerhard; Catà, Oscar; D'Ambrosio, Giancarlo

    We compute the fully differential rate for the Higgs-boson decay [Formula: see text], with [Formula: see text]. For these processes we assume the most general matrix elements within an effective Lagrangian framework. The electroweak chiral Lagrangian we employ assumes minimal particle content and Standard Model gauge symmetries, but it is otherwise completely general. We discuss how information on new physics in the decay form factors may be obtained that is inaccessible in the dilepton-mass spectrum integrated over angular variables. The form factors are related to the coefficients of the effective Lagrangian, which are used to estimate the potential size of new-physics effects.

  19. Complete angular distribution measurements of two-body deuteron photodisintegration between 0.5 and 3 GeV

    SciTech Connect

    M. Mirazita; F. Ronchetti; P. Rossi; E. De Sanctis; CLAS Collaboration

    2004-07-12

    Nearly complete angular distributions of the two-body deuteron photodisintegration differential cross section have been measured using the CEBAF Large Acceptance Spectrometer detector and the tagged photon beam at the Thomas Jefferson National Accelerator Facility. The data cover photon energies between 0.5 and 3.0 GeV and center-of-mass proton scattering angles 10{sup o}-160{sup o}. The data show a persistent forward-backward angle asymmetry over the explored energy range, and are well described by the nonperturbative quark gluon string model.

  20. Angular Distribution of Ly(alpha) Resonant Photons Emergent from Optically Thick Medium

    DTIC Science & Technology

    2012-02-26

    solutions with the Eddington approximation, which assume I to be linearly dependent on the angular variable µ, yield similar frequency profiles of the photon...flux as that without the Eddington approximation. However, the solutions of the µ distribution evolution are significantly different from that given...by Eddington approximation. First, the angular distribution of I are found to be substantially de- pendent on the frequency of photons. For photons

  1. Effects of anisotropic electron-ion interactions in atomic photoelectron angular distributions

    NASA Technical Reports Server (NTRS)

    Dill, D.; Starace, A. F.; Manson, S. T.

    1975-01-01

    A summary of the angular momentum transfer formulation of the differential photoionization cross section is presented and photoionization amplitudes in LS coupling are considered. The application of the theoretical concepts and relations developed is illustrated with the aid of an example involving the calculation of the angular distribution of photoelectrons ionized from atomic sulfur according to a certain reaction. The investigation shows that anisotropic electron-ion interactions in atomic sulfur lead to measurable differences between photoelectron angular distribution asymmetry parameters corresponding to alternative ionic term levels.

  2. A FDTD solution of scattering of laser beam with orbital angular momentum by dielectric particles: Far-field characteristics

    NASA Astrophysics Data System (ADS)

    Sun, Wenbo; Hu, Yongxiang; Weimer, Carl; Ayers, Kirk; Baize, Rosemary R.; Lee, Tsengdar

    2017-02-01

    Electromagnetic (EM) beams with orbital angular momentum (OAM) may have great potential applications in communication technology and in remote sensing of the Earth-atmosphere system and outer planets. Study of their interaction with optical lenses and dielectric or metallic objects, or scattering of them by particles in the Earth-atmosphere system, is a necessary step to explore the advantage of the OAM EM beams. In this study, the 3-dimensional (3D) scattered-field (SF) finite-difference time domain (FDTD) technique with the convolutional perfectly matched layer (CPML) absorbing boundary conditions (ABC) is applied to calculate the scattering of the purely azimuthal (the radial mode number is assumed to be zero) Laguerre-Gaussian (LG) beams with the OAM by dielectric particles. We found that for OAM beam's interaction with dielectric particles, the forward-scattering peak in the conventional phase function (P11) disappears, and light scattering peak occurs at a scattering angle of 15° to 45°. The disappearance of forward-scattering peak means that, in laser communications most of the particle-scattered noise cannot enter the receiver, thus the received light is optimally the original OAM-encoded signal. This feature of the OAM beam also implies that in lidar remote sensing of the atmospheric particulates, most of the multiple-scattering energy will be off lidar sensors, and this may result in an accurate profiling of particle layers in the atmosphere or in the oceans by lidar, or even in the ground when a ground penetration radar (GPR) with the OAM is applied. This far-field characteristics of the scattered OAM light also imply that the optical theorem, which is derived from plane-parallel wave scattering case and relates the forward scattering amplitude to the total cross section of the scatterer, is invalid for the scattering of OAM beams by dielectric particles.

  3. Laboratory-Frame Photoelectron Angular Distributions in Anion Photodetachment: Insight into Electronic Structure and Intermolecular Interactions

    NASA Astrophysics Data System (ADS)

    Sanov, Andrei

    2014-04-01

    This article provides an overview of some recent advances in the modeling of photoelectron angular distributions in negative-ion photodetachment. Building on the past developments in threshold photodetachment spectroscopy that first tackled the scaling of the partial cross sections with energy, depending on the angular momentum quantum number ℓ, it examines the corresponding formulation of the central potential model and extends it to the more general case of hybrid molecular orbitals. Several conceptual approaches to understanding photoelectron angular distributions are discussed. In one approach, the angular distributions are examined based on the contributions of the symmetry-allowed s and p partial waves of the photodetached electron. In another related approach, the parent molecular orbitals are described based on their dominant s and p characters, whereas the continuum electron is described in terms of interference of the corresponding ℓ = ±1 photodetachment channels.

  4. Investigating the hohlraum radiation properties through the angular distribution of the radiation temperature

    NASA Astrophysics Data System (ADS)

    Zhang, H.; Yang, D.; Song, P.; Zou, S.; Zhao, Y.; Li, S.; Li, Z.; Guo, L.; Wang, F.; Zheng, W.; Gu, P.; Pei, W.; Zhu, S.; Jiang, S.; Ding, Y.

    2016-08-01

    The symmetric radiation drive is essential to the capsule implosion in the indirect drive fusion but is hard to achieve due to the non-uniform radiation distribution inside the hohlraum. In this work, the non-uniform radiation properties of both vacuum and gas-filled hohlraums are studied by investigating the angular distribution of the radiation temperature experimentally and numerically. It is found that the non-uniform radiation distribution inside the hohlraum induces the variation of the radiation temperature between different view angles. The simulations show that both the angular distribution of the radiation temperature and the hohlraum radiation distribution can be affected by the electron heat flux. The measured angular distribution of the radiation temperature is more consistent with the simulations when the electron heat flux limiter f e = 0.1 . Comparisons between the experiments and simulations further indicate that the x-ray emission of the blow-off plasma is overestimated in the simulations when it stagnates around the hohlraum axis. The axial position of the laser spot can also be estimated by the angular distribution of the radiation temperature due to their sensitive dependence. The inferred laser spot moves closer to the laser entrance hole in the gas-filled hohlraum than that in the vacuum hohlraum, consisting with the x-ray images taken from the framing camera. The angular distribution of the radiation temperature provides an effective way to investigate the hohlraum radiation properties and introduces more constraint to the numerical modeling of the hohlraum experiments.

  5. Rotationally inelastic scattering of NO(A(2)Σ(+)) + Ar: Differential cross sections and rotational angular momentum polarization.

    PubMed

    Sharples, Thomas R; Luxford, Thomas F M; Townsend, Dave; McKendrick, Kenneth G; Costen, Matthew L

    2015-11-28

    We present the implementation of a new crossed-molecular beam, velocity-map ion-imaging apparatus, optimized for collisions of electronically excited molecules. We have applied this apparatus to rotational energy transfer in NO(A(2)Σ(+), v = 0, N = 0, j = 0.5) + Ar collisions, at an average energy of 525 cm(-1). We report differential cross sections for scattering into NO(A(2)Σ(+), v = 0, N' = 3, 5, 6, 7, 8, and 9), together with quantum scattering calculations of the differential cross sections and angle dependent rotational alignment. The differential cross sections show dramatic forward scattered peaks, together with oscillatory behavior at larger scattering angles, while the rotational alignment moments are also found to oscillate as a function of scattering angle. In general, the quantum scattering calculations are found to agree well with experiment, reproducing the forward scattering and oscillatory behavior at larger scattering angles. Analysis of the quantum scattering calculations as a function of total rotational angular momentum indicates that the forward scattering peak originates from the attractive minimum in the potential energy surface at the N-end of the NO. Deviations in the quantum scattering predictions from the experimental results, for scattering at angles greater than 10°, are observed to be more significant for scattering to odd final N'. We suggest that this represents inaccuracies in the potential energy surface, and in particular in its representation of the difference between the N- and O-ends of the molecule, as given by the odd-order Legendre moments of the surface.

  6. Intensity distribution angular shaping - Practical approach for 3D optical beamforming

    NASA Astrophysics Data System (ADS)

    Wojtanowski, Jacek; Traczyk, Maciej; Zygmunt, Marek; Mierczyk, Zygmunt; Knysak, Piotr; Drozd, Tadeusz

    2014-12-01

    We present approach of optical design which enables to obtain aspheric lens shape optimized for providing the specific light power density distribution in space. Proposed method is based on the evaluation of corresponding angular intensity distribution which can be obtained by the decomposition of the desired spatial distribution into virtual light cones set and collapsing it to the equivalent angular fingerprint. Rigorous formulas have been derived to relate refractive aspheric shape and the corresponding intensity distribution which is used for lens optimization. Algorithms of modeling and optimization were implemented in Matlab© and the calculated designs were successfully tested in Zemax environment.

  7. Angular distribution of field emitted electrons from vertically aligned carbon nanotube arrays

    NASA Astrophysics Data System (ADS)

    Iacobucci, S.; Fratini, M.; Rizzo, A.; Scarinci, F.; Zhang, Y.; Mann, M.; Li, C.; Milne, W. I.; El Gomati, M. M.; Lagomarsino, S.; Stefani, G.

    2012-01-01

    Angular field emission (FE) properties of vertically aligned carbon nanotube arrays have been measured on samples grown by plasma enhanced chemical vapor deposition and characterized by scanning electron microscope and I-V measurements. These properties determine the angular divergence of electron beams, a crucial parameter in order to obtain high brilliance FE based cathodes. From angular distributions of the electron beam transmitted through extraction grids of different mesh size and by using ray-tracing simulations, the maximum emission angle from carbon nanotube tips has been determined to be about ± 30° around the tube main axis.

  8. Ion beam sputtering of Ti: Influence of process parameters on angular and energy distribution of sputtered and backscattered particles

    NASA Astrophysics Data System (ADS)

    Lautenschläger, T.; Feder, R.; Neumann, H.; Rice, C.; Schubert, M.; Bundesmann, C.

    2016-10-01

    In the present study, the influence of ion energy and geometrical parameters onto the angular and energy distribution of secondary particles for sputtering a Ti target with Ar ions is investigated. The angular distribution of the particle flux of the sputtered Ti atoms was determined by the collection method, i.e. by growing Ti films and measuring their thickness. The formal description of the particle flux can be realized by dividing it into an isotropic and an anisotropic part. The experimental data show that increasing the ion energy or decreasing the ion incidence angle lead to an increase of the isotropic part, which is in good agreement with basic sputtering theory. The energy distribution of the secondary ions was measured using an energy-selective mass spectrometer. The energy distribution of the sputtered target ions shows a maximum at an energy between 10 eV and 20 eV followed by a decay proportional to E-n, which is in principle in accordance with Thompson's theory, followed by a high energetic tail. When the sum of incidence angle and emission angle is increased, the high-energetic tail expands to higher energies and an additional peak due to direct sputtering events may occur. In the case of backscattered primary Ar ions, a maximum at an energy between 5 eV and 10 eV appears and, depending on the scattering geometry, an additional broad peak at a higher energy due to direct scattering events is observed. The center energy of the additional structure shifts systematically to higher energies with decreasing scattering angle or increasing ion energy. The experimental results are compared to calculations based on simple elastic two-particle-interaction theory and to simulations done with the Monte Carlo code SDTrimSP. Both confirm in principle the experimental findings.

  9. Annual variation of the angular distribution of the UV beneath public shade structures.

    PubMed

    Turnbull, D J; Parisi, A V

    2004-10-25

    Local governments provide many shade structures at parks and sporting ovals for public use. However, the question remains of how effective are public shade structures at reducing biologically effective UV radiation throughout the year? Broadband measurements of the angular distribution of scattered UV beneath three specific public shade structures was conducted for relatively clear skies and for a solar zenith angle (SZA) ranging from 13 degrees to 76 degrees. The ultraviolet protection factors (UPF) for the shade structures ranged from 18.3 to 1.5 for an increasing SZA. Measurements showed that the horizontal plane received the highest SUV levels from the SZA of 28 degrees to 75 degrees, 42 degrees to 76 degrees, and 50 degrees to 76 degrees for the small, medium and large structures, respectively. This was due to the angle of the sun causing the shade created by the shade structure to be outside the structure. For the small shade structure, the measurements directed to the west were the highest levels in the shade after approximately 28 degrees. For the medium and large shade structures, the measurements directed to the west and south were the highest levels in the shade after roughly 42 degrees and 50 degrees, respectively.

  10. Identifying and Understanding Strong Vibronic Interaction Effects Observed in the Asymmetry of Chiral Molecule Photoelectron Angular Distributions.

    PubMed

    Garcia, Gustavo A; Dossmann, Héloïse; Nahon, Laurent; Daly, Steven; Powis, Ivan

    2017-03-03

    Electron-ion coincidence imaging is used to study chiral asymmetry in the angular distribution of electrons emitted from randomly-oriented enantiomers of two molecules, methyloxirane and trifluoromethyloxirane, upon ionization by circularly polarized VUV synchrotron radiation. Vibrationally-resolved photoelectron circular dichroism (PECD) measurements of the outermost orbital ionization reveal unanticipated large fluctuations in the magnitude of the forward-backward electron scattering asymmetry, including even a complete reversal of direction. Identification and assignment of the vibrational excitations is supported by Franck-Condon simulations of the photoelectron spectra. A previously proposed quasi-diatomic model for PECD is developed and extended to treat polyatomic systems. The parametric dependence of the electronic dipole matrix elements on nuclear geometry is evaluated in the adiabatic approximation. It provokes vibrational level dependent shifts in amplitude and phase, to which the chiral photoelectron angular distributions are especially sensitive. It is shown that single quantum excitation of those vibrational modes, which experience only a relatively small displacement of the ion equilibrium geometry along the normal coordinate and which are then only weakly excited in the Franck-Condon limit, can be accompanied by big shifts in scattering phase; hence the observed big fluctuations in PECD asymmetry for such modes.

  11. Resonance Regge poles and the state-to-state F + H2 reaction: QP decomposition, parametrized S matrix, and semiclassical complex angular momentum analysis of the angular scattering

    NASA Astrophysics Data System (ADS)

    Connor, J. N. L.

    2013-03-01

    Three new contributions to the complex angular momentum (CAM) theory of differential cross sections (DCSs) for chemical reactions are reported. They exploit recent advances in the Padé reconstruction of a scattering (S) matrix in a region surrounding the {Renolimits} J axis, where J is the total angular momentum quantum variable, starting from the discrete values, J = 0, 1, 2, …. In particular, use is made of Padé continuations obtained by Sokolovski, Castillo, and Tully [Chem. Phys. Lett. 313, 225 (1999), 10.1016/S0009-2614(99)01016-7] for the S matrix of the benchmark F + H2(vi = 0, ji = 0, mi = 0) → FH(vf = 3, jf = 3, mf = 0) + H reaction. Here vi, ji, mi and vf, jf, mf are the initial and final vibrational, rotational, and helicity quantum numbers, respectively. The three contributions are: (1) A new exact decomposition of the partial wave (PW) S matrix is introduced, which is called the QP decomposition. The P part contains information on the Regge poles. The Q part is then constructed exactly by subtracting a rapidly oscillating phase and the PW P matrix from the input PW S matrix. After a simple modification, it is found that the corresponding scattering subamplitudes provide insight into the angular-scattering dynamics using simple partial wave series (PWS) computations. It is shown that the leading n = 0 Regge pole contributes to the small-angle scattering in the centre-of-mass frame. (2) The Q matrix part of the QP decomposition has simpler properties than the input S matrix. This fact is exploited to deduce a parametrized (analytic) formula for the PW S matrix in which all terms have a direct physical interpretation. This is a long sort-after goal in reaction dynamics, and in particular for the state-to-state F + H2 reaction. (3) The first definitive test is reported for the accuracy of a uniform semiclassical (asymptotic) CAM theory for a DCS based on the Watson transformation. The parametrized S matrix obtained in contribution (2) is used in both

  12. Angular distribution of ions and extreme ultraviolet emission in laser-produced tin droplet plasma

    SciTech Connect

    Chen, Hong; Duan, Lian; Lan, Hui; Wang, Xinbing Chen, Ziqi; Zuo, Duluo; Lu, Peixiang

    2015-05-21

    Angular-resolved ion time-of-flight spectra as well as extreme ultraviolet radiation in laser-produced tin droplet plasma are investigated experimentally and theoretically. Tin droplets with a diameter of 150 μm are irradiated by a pulsed Nd:YAG laser. The ion time-of-flight spectra measured from the plasma formed by laser irradiation of the tin droplets are interpreted in terms of a theoretical elliptical Druyvesteyn distribution to deduce ion density distributions including kinetic temperatures of the plasma. The opacity of the plasma for extreme ultraviolet radiation is calculated based on the deduced ion densities and temperatures, and the angular distribution of extreme ultraviolet radiation is expressed as a function of the opacity using the Beer–Lambert law. Our results show that the calculated angular distribution of extreme ultraviolet radiation is in satisfactory agreement with the experimental data.

  13. Detection of lung nodules in chest digital tomosynthesis (CDT): effects of the different angular dose distribution

    NASA Astrophysics Data System (ADS)

    Jo, Byungdu; Lee, Youngjin; Kim, Dohyeon; Lee, Dong-Hoon; Jin, Seong-Soo; Mu, Shou-Chih; Kim, Hye-Mi; Kim, Hee-Joung

    2015-03-01

    Chest digital tomosynthesis (CDT) is a recently introduced new imaging modality for better detection of high- and smallcontrast lung nodules compared to conventional X-ray radiography. In CDT system, several projection views need to be acquired with limited angular range. The acquisition of insufficient number of projection data can degrade the reconstructed image quality. This image degradation easily affected by acquisition parameters such as angular dose distribution, number of projection views and reconstruction algorithm. To investigate the imaging characteristics, we evaluated the impact of the angular dose distribution on image quality by simulation studies with Geant4 Application for Tomographic Emission (GATE). We designed the different angular dose distribution conditions. The results showed that the contrast-to-noise ratio (CNR) improves when exposed the higher dose at central projection views than peripheral views. While it was found that increasing angular dose distribution at central views improved lung nodule detectability, although both peripheral regions slightly suffer from image noise due to low dose distribution. The improvements of CNR by using proposed image acquisition technique suggest possible directions for further improvement of CDT system for lung nodule detection with high quality imaging capabilities.

  14. Intensity and polarization of light scattered by size distributions of randomly oriented nonspherical particles

    NASA Technical Reports Server (NTRS)

    Mishchenko, M. I.; Travis, L. D.

    1993-01-01

    Calculations of light scattering by small particles are important in many diverse fields of science and engineering. In many cases of practical interest, scattering particles are nonspherical and are distributed over sizes and orientations. However, accurate light scattering computations for ensembles of nonspherical particles are difficult and time-consuming, and the literature in which such calculations are reported is rather scarce. In this paper, the T-matrix approach, as extended recently to randomly oriented particles, is used to calculate rigorously light scattering by size distributions of randomly oriented axially symmetric particles. To model the variation of particle sizes in real ensembles, we use a power law distribution typical of some terrestrial aerosols. Contour plots of intensity and degree of linear polarization for polydisperse prolate and oblate spheroids of different aspect ratios and effective equivalent-sphere size parameters from 0 to 10 are calculated and compared with calculations for equivalent spheres. The angular scattering behavior of nonspherical polydispersions is found to be greatly different from that of spheres, while the scattering properties of oblate and prolate spheroids of the same aspect ratio are similar. With increasing particle size, both intensity and polarization become more shape-dependent. In general, nonspherical particles are stronger side scatterers and weaker backscatterers than equivalent spheres. With increasing aspect ratio of nonspherical particles polarization tends to be predominantly positive. Possible effects of particle nonsphericity on optical remote sensing of atmospheric aerosols are discussed.

  15. Dynamic approach to description of entrance channel effects in angular distributions of fission fragments

    NASA Astrophysics Data System (ADS)

    Eremenko, D. O.; Drozdov, V. A.; Fotina, O. V.; Platonov, S. Yu.; Yuminov, O. A.

    2016-07-01

    Background: It is well known that the anomalous behavior of angular anisotropies of fission fragments at sub- and near-barrier energies is associated with a memory of conditions in the entrance channel of the heavy-ion reactions, particularly, deformations and spins of colliding nuclei that determine the initial distributions for the components of the total angular momentum over the symmetry axis of the fissioning system and the beam axis. Purpose: We develop a new dynamic approach, which allows the description of the memory effects in the fission fragment angular distributions and provides new information on fusion and fission dynamics. Methods: The approach is based on the dynamic model of the fission fragment angular distributions which takes into account stochastic aspects of nuclear fission and thermal fluctuations for the tilting mode that is characterized by the projection of the total angular momentum onto the symmetry axis of the fissioning system. Another base of our approach is the quantum mechanical method to calculate the initial distributions over the components of the total angular momentum of the nuclear system immediately following complete fusion. Results: A method is suggested for calculating the initial distributions of the total angular momentum projection onto the symmetry axis for the nuclear systems formed in the reactions of complete fusion of deformed nuclei with spins. The angular distributions of fission fragments for the 16O+232Th,12C+235,236,238, and 13C+235U reactions have been analyzed within the dynamic approach over a range of sub- and above-barrier energies. The analysis allowed us to determine the relaxation time for the tilting mode and the fraction of fission events occurring in times not larger than the relaxation time for the tilting mode. Conclusions: It is shown that the memory effects play an important role in the formation of the angular distributions of fission fragments for the reactions induced by heavy ions. The

  16. Effects of laser polarization on photoelectron angular distribution through laser-induced continuum structure

    SciTech Connect

    Buica, Gabriela; Nakajima, Takashi

    2005-11-15

    We theoretically investigate the effects of laser polarization on the photoelectron angular distribution through laser-induced continuum structure. We focus on a polarization geometry where the probe and dressing lasers are both linearly polarized and change the relative polarization angle between them. We find that the total ionization yield and the branching ratio into different ionization channels change as a function of the relative polarization angle, and accordingly the photoelectron angular distribution is altered. We present specific results for the 4p{sub 1/2}-6p{sub 1/2} and 4p{sub 3/2}-6p{sub 3/2} systems of the K atom and show that the change of the polarization angle leads to a significant modification of the photoelectron angular distribution.

  17. Angular distribution of emitted electrons in sodium clusters: A semiclassical approach

    SciTech Connect

    Giglio, E.; Reinhard, P.-G.; Suraud, E.

    2003-04-01

    We present a theoretical study of the angular distribution of emitted electrons of a sodium cluster, irradiated by short and intense laser pulses. While the polarization of the excitation field tends to focus a directional emission, the dynamical correlations tend to thermalize the electrons, giving rise to a more isotropic ionization. The competition between these processes is investigated using a semiclassical model Vlasov-Uehling-Uhlenbeck, where the dynamical correlations are taken in account by the electron-electron correlations in the Markovian approximation, the widely known Uehling-Uhlenbeck collision term. The results are compared to a semiclassical pure mean-field propagation (Vlasov equation) to work out the influence of dynamical correlations on the angular distribution of the electron emission. The trends with laser intensity and frequency are explored. The time evolution of the angular distributions shows that direct emission processes are stronger in the early phase of the processs, while isotropic thermal emission dominates later.

  18. Model-independent constraints on the shape parameters of dilepton angular distributions

    NASA Astrophysics Data System (ADS)

    Faccioli, Pietro; Lourenço, Carlos; Seixas, João; Wöhri, Hermine K.

    2011-03-01

    The coefficients determining the dilepton decay angular distribution of vector particles obey certain positivity constraints and a rotation-invariant identity. These relations are a direct consequence of the covariance properties of angular momentum eigenstates and are independent of the production mechanism. The Lam-Tung relation can be derived as a particular case, simply recognizing that the Drell-Yan dilepton is always produced transversely polarized with respect to one or more quantization axes. The dilepton angular distribution continues to be characterized by a frame-independent identity also when the Lam-Tung relation is violated. Moreover, the violation can be easily characterized by measuring a one-dimensional distribution depending on one shape coefficient.

  19. Measurement of anisotropic angular distributions of photon energy spectra for I-125 brachytherapy sources.

    PubMed

    Unno, Yasuhiro; Yunoki, Akira; Kurosawa, Tadahiro; Yamada, Takahiro; Sato, Yasushi; Hino, Yoshio

    2012-09-01

    The angular distribution of photon energy spectra emitted from an I-125 brachytherapy source was measured using a specially designed jig in the range of ±70° in the plane of the long axis of the source. It is important to investigate the angular dependence of photon emissions from these sources for the calibration of the air kerma rate. The results show that the influence of the distributions between 0° and ±8° is small enough to allow a calibration using current primary instruments which have a large entrance window.

  20. Angular distribution in the dissociation of H2O by swift heavy ions

    NASA Astrophysics Data System (ADS)

    Cabrera-Trujillo, R.; Stolterfoht, N.; Öhrn, Y.; Deumens, E.; Sabin, J. R.

    2006-05-01

    In this work, we present calculations of the angular distribution of the products of the dissociation of water molecules when bombarded with He^q+ for projectile energies between 1 and 5 keV. Here q=0,1,2 is the charge of the incoming ion. Our theoretical results are based on the Electron-Nuclear Dynamics formalism (END). We present results for the dissociation cross section, charge transfer cross section, the stopping cross section (nuclear and electronic) for the projectiles, and the angular distribution of He^q+, H, OH, and O. E. Deumens, A. Diz, R. Longo, and Y. "Ohrn, Rev. Mod. Phys. 66, 917 (1994).

  1. Effects of transverse electron beam size on transition radiation angular distribution

    NASA Astrophysics Data System (ADS)

    Chiadroni, E.; Castellano, M.; Cianchi, A.; Honkavaara, K.; Kube, G.

    2012-05-01

    In this paper we consider the effect of the transverse electron beam size on the Optical Transition Radiation (OTR) angular distribution in case of both incoherent and coherent emission. Our results confute the theoretical argumentations presented first in Optics Communications 211, 109 (2002), which predicts a dependence of the incoherent OTR angular distribution on the beam size and emission wavelength. We present here theoretical and experimental data not only to validate the well-established Ginzburg-Frank theory, but also to show the impact of the transverse beam size in case of coherent emission.

  2. A Template Measurement of the Top Quark Angular Distribution Using Boosted Lepton + Jets Events

    NASA Astrophysics Data System (ADS)

    Eminizer, Nick; CMS Collaboration

    2017-01-01

    We present a template-based technique for measuring the angular distribution of top quark pairs decaying semileptonically using data collected by the CMS experiment at the LHC. The analysis is optimized for high-momentum ``boosted'' decays wherein the hadronically decaying top quark's jets become either partially or fully merged, and the final state lepton is not necessarily isolated from nearby jets. The technique can be used to examine multiple physics processes affecting the angular distribution of top pairs, including the parton-level top quark forward-backward asymmetry AFB and anomalous chromoelectric/chromomagnetic moments. CMS is the Compact Muon Solenoid experiment at the Large Hadron Collider.

  3. Angular distributions of the quenched energy flow from dijets with different radius parameters in CMS

    NASA Astrophysics Data System (ADS)

    McGinn, Christopher F.

    2016-12-01

    The flow of the quenched energy in imbalanced dijet events has been previously studied by transverse vector sum of charged particles with the CMS detector, namely the missing pT measurement. The results have led to new theoretical insights to order to explain the wide angle radiation. The missing pT technique has been improved so that it allows the study of angular distribution of the energy flow with respect to the dijet axis. The measurements are performed using different distance parameters R with the anti-kT clustering algorithm, which provide information about how the angular distribution of the quenched energy depends on the jet width.

  4. Angular distribution of Auger electrons due to 3d-shell impact ionization of krypton

    NASA Technical Reports Server (NTRS)

    Omidvar, K.

    1977-01-01

    Cross sections for electron impact ionization of krypton due to ejection of a 3d-shell electron have been calculated using screened hydrogenic and Hartree-Slater wavefunctions for the target atom. While the total ionization cross sections in the two approximations are within 10% of each other, the Auger electron angular distribution, related to cross sections for specific magnetic quantum numbers of the 3d electrons, are widely different in the two approximations. The angular distribution due to the Hartree-Slater approximation is in excellent agreement with measurement. The physical reason for the discrepancies in the two approximations is explained.

  5. Angular distribution of Auger electrons due to 3d-shell ionization of krypton

    NASA Technical Reports Server (NTRS)

    Omidvar, K.

    1977-01-01

    Cross sections for electron impact ionization of krypton due to ejection of a 3rd shell electron have been calculated using screened hydrogenic and Hartree-Slater wave functions for target atom. While the total ionization cross sections in the two approximations are within 10% of each other, the Auger electron angular distribution, related to cross sections for specific magnetic quantum numbers of the 3rd electrons, is widely different in the two approximations. The angular distribution due to Hartree-Slater approximation is in excellent agreement with measurement. The physical reason for the discrepancies in the two approximations is explained.

  6. Electron Scattering and Related Phenomena in Scattering with Angular Limitation Projection Electron Lithography (SCALPEL\\footnote{SCALPEL is a trademark of Lucent Technologies.})

    NASA Astrophysics Data System (ADS)

    Mkrtchyan, Masis M.

    2000-12-01

    Scattering with angular limitation projection electron lithography (SCALPEL) is a unique charged-particle projection imaging technique that employs a scattering mask with the pattern segmented between supporting struts. An aperture installed in the back-focal plane of the projection lens filters out the electrons scattered at large angles in the patterned area of the mask producing a high contrast aerial image. Various scattering phenomena involved with the energetic (100 keV) electrons carrying the mask pattern information to the wafer through the projection optics are responsible for the aerial image formation in SCALPEL@. These phenomena can be grouped into three major categories: (i) electron elastic scattering in the mask responsible for the aerial image intensity and contrast; (ii) electron inelastic scattering in the mask-membrane that might have negative effects, such as membrane charging, beam chromatic blur generation, mask heating, etc.; (iii) Coulomb interactions of electrons in the beam (space charge effect) generating a beam blur that links the system throughput and resolution. Analytical models developed to describe and quantitatively evaluate these phenomena are briefly reviewed. The implication of these models to the design and optimization of the electron projection lithography systems are discussed.

  7. Angularly-resolved elastic scatter from single particles collected over a large solid angle and with high resolution

    NASA Astrophysics Data System (ADS)

    Aptowicz, Kevin B.; Chang, Richard K.

    2005-01-01

    Elastic light scattering from a single non-spherical particle of various morphologies has been measured simultaneously with a large angular range (90° < θ < 165° and 0° < phi < 360°) and with high angular resolution (1024 pixels in θ and 512 pixels in phi). Because the single-shot laser pulse is short (pulse duration of 70 ns), the tumbling and flowing particle can be treated as frozen in space. The large angle two-dimensional angular optical scattering (hereafter referred to as LA TAOS) intensity pattern, I(θ,phi), has been measured for a variety of particle morphology, such as the following: (1) single polystyrene latex (PSL) sphere; (2) cluster of PSL spheres; (3) single Bacillus subtilis (BG) spore; (4) cluster of BG spores; (5) dried aggregates of bio-aerosols as well as background clutter aerosols. All these measurements were made using the second harmonic of a Nd:YAG laser (0.532 μm). Islands structures in the LA TAOS patterns seem to be the prominent feature. Efforts are being made to extract metrics from these islands and compare them to theoretical results based on the T-matrix method.

  8. Angular Momentum Distribution of Hot Gas and Implications for Disk Galaxy Formation

    NASA Astrophysics Data System (ADS)

    Chen, D. N.; Jing, Y. P.; Yoshikaw, Kohji

    2003-11-01

    We study the angular momentum profiles both for dark matter and for gas within virialized halos using a statistical sample of halos drawn from cosmological hydrodynamics simulations. Three simulations have been analyzed: one is the nonradiative simulation and the other two have radiative cooling. We find that the gas component, on average, has a larger spin and contains a smaller fraction of mass with negative angular momentum than its dark matter counterpart in the nonradiative model. As to the cooling models, the gas component shares approximately the same spin parameter as its dark matter counterpart, but the hot gas has a higher spin and is more aligned in angular momentum than dark matter, while the opposite holds for the cold gas. After the mass of negative angular momentum is excluded, the angular momentum profile of the hot gas component approximately follows the universal function originally proposed by Bullock et al. for dark matter, though the shape parameter μ is much larger for hot gas and is comfortably in the range required by observations of disk galaxies. Since disk formation is related to the distribution of hot gas that will cool, our study may explain the fact that the disk component of observed galaxies contains a smaller fraction of low angular momentum material than dark matter in halos.

  9. Angular Distributions of Drell-Yan Dimuons at Fermilab E-906/SeaQuest

    NASA Astrophysics Data System (ADS)

    Ramson, Bryan; Fermilab E-906/SeaQuest Collaboration

    2015-10-01

    Transverse momentum dependent (TMD) parton distribution functions (PDF), fragmentation functions, and their necessary theoretical framework provide a rich foundation from which to build a more descriptive, quantitative understanding of QCD and hadron structure. Fortuitously, TMD sensitive analyses of leptonic angular distributions have been a fixture in Drell-Yan experiments since the π+W CERN NA-10 of the 1980's, with particular focus on the violation of the Lam-Tung relation through a non-zero cos (2 ϕ) modulation in the angular distributions of the final-state leptons. The cos (2 ϕ) modulation is sensitive to the correlation between the motion and spin of transversely polarized (anti)quarks within their encompassing unpolarized hadron, described by the Boer-Mulders TMD PDF. In the mid-1990's, Fermilab E-866/NuSea investigated angular distributions of p+p and p+d Drell-Yan and found that the relative strength of the cos (2 ϕ) modulation, as compared to pion-induced Drell-Yan, is reduced. Fermilab E-906/SeaQuest provides an ideal laboratory in which to measure the cos (2 ϕ) modulation at a higher target xBj than possible with E-866. Recent progress in the analysis of the angular distributions from SeaQuest Drell-Yan dimuons will be shown.

  10. Scattering matrix theory for stochastic scalar fields.

    PubMed

    Korotkova, Olga; Wolf, Emil

    2007-05-01

    We consider scattering of stochastic scalar fields on deterministic as well as on random media, occupying a finite domain. The scattering is characterized by a generalized scattering matrix which transforms the angular correlation function of the incident field into the angular correlation function of the scattered field. Within the accuracy of the first Born approximation this matrix can be expressed in a simple manner in terms of the scattering potential of the scatterer. Apart from determining the angular distribution of the spectral intensity of the scattered field, the scattering matrix makes it possible also to determine the changes in the state of coherence of the field produced on scattering.

  11. Rapid Inversion of Angular Deflection Data for Certain Axisymmetric Refractive Index Distributions

    NASA Technical Reports Server (NTRS)

    Rubinstein, R.; Greenberg, P. S.

    1994-01-01

    Certain functions useful for representing axisymmetric refractive-index distributions are shown to have exact solutions for Abel transformation of the resulting angular deflection data. An advantage of this procedure over direct numerical Abel inversion is that least-squares curve fitting is a smoothing process that reduces the noise sensitivity of the computation

  12. Quantum mechanical method of fragment's angular and energy distribution calculation for binary and ternary fission

    SciTech Connect

    Kadmensky, S. G. Titova, L. V.; Pen'kov, N. V.

    2006-08-15

    In the framework of quantum-mechanical fission theory, the method of calculation for partial fission width amplitudes and asymptotic behavior of the fissile nucleus wave function with strong channel coupling taken into account has been suggested. The method allows one to solve the calculation problem of angular and energy distribution countation for binary and ternary fission.

  13. Angular distribution of undulator power for an arbitrary deflection parameter K

    SciTech Connect

    Kim, K.J.

    1985-08-01

    A calculation of the angular distribution of power generated from an undulator, integrated over all frequencies, is presented. The result, valid for any arbitrary value of the deflection parameter K, reduces to the known expressions in the cases K ..-->.. infinity and K ..-->.. 0.

  14. On the angular and energy distribution of solar neutrons generated in P-P reactions

    NASA Technical Reports Server (NTRS)

    Efimov, Y. E.; Kocharov, G. E.

    1985-01-01

    The problem of high energy neutron generation in P-P reactions in the solar atmosphere is reconsidered. It is shown that the angular distribution of emitted neutrons is anisotropic and the energy spectrum of neutrons depends on the angle of neutron emission.

  15. Time evolution analysis of the electron distribution in Thomson/Compton back-scattering

    SciTech Connect

    Petrillo, V.; Bacci, A.; Curatolo, C.; Maroli, C.; Serafini, L.; Rossi, A. R.

    2013-07-28

    We present the time evolution of the energy distribution of a relativistic electron beam after the Compton back-scattering with a counter-propagating laser field, performed in the framework of the Quantum Electrodynamics, by means of the code CAIN. As the correct angular distribution of the spontaneous emission is accounted, the main effect is the formation of few stripes, followed by the diffusion of the more energetic particles toward lower values in the longitudinal phase space. The Chapman-Kolmogorov master equation gives results in striking agreement with the numerical ones. An experiment on the Thomson source at SPARC-LAB is proposed.

  16. Time evolution analysis of the electron distribution in Thomson/Compton back-scattering

    NASA Astrophysics Data System (ADS)

    Petrillo, V.; Bacci, A.; Curatolo, C.; Maroli, C.; Serafini, L.; Rossi, A. R.

    2013-07-01

    We present the time evolution of the energy distribution of a relativistic electron beam after the Compton back-scattering with a counter-propagating laser field, performed in the framework of the Quantum Electrodynamics, by means of the code CAIN. As the correct angular distribution of the spontaneous emission is accounted, the main effect is the formation of few stripes, followed by the diffusion of the more energetic particles toward lower values in the longitudinal phase space. The Chapman-Kolmogorov master equation gives results in striking agreement with the numerical ones. An experiment on the Thomson source at SPARC-LAB is proposed.

  17. Unconventional application of the two-flux approximation for the calculation of the Ambartsumyan-Chandrasekhar function and the angular spectrum of the backward-scattered radiation for a semi-infinite isotropically scattering medium

    NASA Astrophysics Data System (ADS)

    Remizovich, V. S.

    2010-06-01

    It is commonly accepted that the Schwarzschild-Schuster two-flux approximation (1905, 1914) can be employed only for the calculation of the energy characteristics of the radiation field (energy density and energy flux density) and cannot be used to characterize the angular distribution of radiation field. However, such an inference is not valid. In several cases, one can calculate the radiation intensity inside matter and the reflected radiation with the aid of this simplest approximation in the transport theory. In this work, we use the results of the simplest one-parameter variant of the two-flux approximation to calculate the angular distribution (reflection function) of the radiation reflected by a semi-infinite isotropically scattering dissipative medium when a relatively broad beam is incident on the medium at an arbitrary angle relative to the surface. We do not employ the invariance principle and demonstrate that the reflection function exhibits the multiplicative property. It can be represented as a product of three functions: the reflection function corresponding to the single scattering and two identical h functions, which have the same physical meaning as the Ambartsumyan-Chandrasekhar function ( H) has. This circumstance allows a relatively easy derivation of simple analytical expressions for the H function, total reflectance, and reflection function. We can easily determine the relative contribution of the true single scattering in the photon backscattering at an arbitrary probability of photon survival Λ. We compare all of the parameters of the backscattered radiation with the data resulting from the calculations using the exact theory of Ambartsumyan, Chandrasekhar, et al., which was developed decades after the two-flux approximation. Thus, we avoid the application of fine mathematical methods (the Wiener-Hopf method, the Case method of singular functions, etc.) and obtain simple analytical expressions for the parameters of the scattered radiation

  18. Instability in the dense supernova neutrino gas with flavor-dependent angular distributions.

    PubMed

    Mirizzi, Alessandro; Serpico, Pasquale Dario

    2012-06-08

    The usual description of self-induced flavor conversions for neutrinos (ν's) in supernovae is based on the simplified assumption that all the ν's of the different species are emitted "half-isotropically" by a common neutrinosphere, in analogy to a blackbody emission. However, realistic supernova simulations show that ν angular distributions at decoupling are far from being half-isotropic and, above all, are flavor dependent. We show that flavor-dependent angular distributions may lead to crossing points in the angular spectra of different ν species (where F(ν(e))=F(ν(x)) and F(ν(e))=F(ν(x))) around which a new multiangle instability can develop. To characterize this effect, we carry out a linearized flavor stability analysis for different supernova neutrino angular distributions. We find that this instability can shift the onset of the flavor conversions toward low radii and produce a smearing of the splitting features found with trivial ν emission models. As a result the spectral differences among ν's of different flavors could be strongly reduced.

  19. Investigating the hohlraum radiation properties through the angular distribution of the radiation temperature

    NASA Astrophysics Data System (ADS)

    Yang, Dong; Zhang, Huasen; Song, Peng; Zou, Shiyang; Zhu, Shaoping; Li, Sanwei; Li, Zhichao; Guo, Liang; Jiang, Shaoen; Ding, Yongkun

    2016-10-01

    The symmetric radiation drive is essential to the capsule implosion in the indirect drive fusion, but is hard to achieve due to the non-uniform radiation distribution inside the hohlraum. The non-uniform radiation properties of both vacuum and gas-filled hohlraums are studied by investigating the angular distribution of the radiation temperature. The non-uniform radiation distribution inside the hohlraum induces the variation of the radiation temperature between different view angles. The simulations show that both the angular distribution of the radiation temperature and the hohlraum radiation distribution can be affected by the electron heat flux. Comparisons between the experiments and simulations further indicate that the x-ray emission of the blow-off plasma is overestimated in the simulations when it stagnates around the hohlraum axis. The axial position of the laser spot can also be estimated by the angular distribution of the radiation temperature due to their sensitive dependence. The inferred laser spot moves closer to the laser entrance hole in the gas-filled hohlraum than that in the vacuum hohlraum, consisting with the x-ray images taken from the framing camera.

  20. An alternative scheme of angular-dispersion analyzers for high-resolution medium-energy inelastic X-ray scattering.

    PubMed

    Huang, Xian Rong

    2011-11-01

    The development of medium-energy inelastic X-ray scattering optics with meV and sub-meV resolution has attracted considerable efforts in recent years. Meanwhile, there are also concerns or debates about the fundamental and feasibility of the involved schemes. Here the central optical component, the back-reflection angular-dispersion monochromator or analyzer, is analyzed. The results show that the multiple-beam diffraction effect together with transmission-induced absorption can noticeably reduce the diffraction efficiency, although it may not be a fatal threat. In order to improve the efficiency, a simple four-bounce analyzer is proposed that completely avoids these two adverse effects. The new scheme is illustrated to be a feasible alternative approach for developing meV- to sub-meV-resolution inelastic X-ray scattering spectroscopy.

  1. On the non-uniform distribution of the angular elements of near-Earth objects

    NASA Astrophysics Data System (ADS)

    JeongAhn, Youngmin; Malhotra, Renu

    2014-02-01

    We examine the angular distributions of near-Earth objects (NEOs) which are often regarded as uniform. The apparent distribution of the longitude of ascending node, Ω, is strongly affected by well-known seasonal effects in the discovery rate of NEOs. The deviation from the expected π-periodicity in the apparent distribution of Ω indicates that its intrinsic distribution is slightly enhanced along a mean direction, Ω‾=111°; approximately 53% of NEOs have Ω values within ±90° of Ω‾. We also find that each subgroup of NEOs (Amors, Apollos and Atens) has different observational selection effects which cause different non-uniformities in the apparent distributions of their arguments of perihelion ω, and longitudes of perihelion ϖ. For their intrinsic distributions, our analysis reveals that the Apollo asteroids have non-uniform ω due to secular dynamics associated with inclination-eccentricity-ω coupling, and the Amors’ ϖ distribution is peaked towards the secularly forced eccentricity vector. The Apollos’ ω distribution is axial, favoring values near 0° and 180°; the two quadrants centered at 0° and 180° account for 55% of the Apollos’ ω values. The Amors’ ϖ distribution peaks near ϖ‾=4°; 61% of Amors have ϖ within ±90° of this peak. We show that these modest but statistically significant deviations from uniform random distributions of angular elements are owed to planetary perturbations, primarily Jupiter’s. It is remarkable that this strongly chaotic population of minor planets reveals the presence of Jupiter in its angular distributions.

  2. Angular distribution of electrons directly accelerated by an intense tightly focused laser pulse

    NASA Astrophysics Data System (ADS)

    Vais, O. E.; Bochkarev, S. G.; Ter-Avetisyan, S.; Bychenkov, V. Yu.

    2017-02-01

    We report a study of spectral and angular distributions of electrons directly accelerated from an ultrathin nanofoil by a tightly focused, relativistically intense laser pulse. The approach applied is based on a realistic model describing the focusing of radiation by an off-axis parabolic mirror, the field distribution being simulated with the help of Stratton – Chu integrals. We have compared spectral and angular electron distributions for laser pulses having Gaussian transverse and rectangular intensity profiles on the mirror at the same laser pulse energy. It is shown that in the case of a pulse with a rectangular intensity profile, the energy of fast electrons is higher and the emission angles are smaller than those in the case of a pulse with a Gaussian profile. Presented at ECLIM2016 (Moscow, 18 – 23 September 2016).

  3. Effect of Orbital Angular Momentum on Valence-Quark Helicity Distributions

    SciTech Connect

    Harut Avakian; Stanley J. Brodsky; Alexandre Deur; Feng Yuan

    2007-08-01

    We study the quark helicity distributions at large x in perturbative QCD, taking into account contributions from the valence Fock states of the nucleon which have nonzero orbital angular momentum. These states are necessary to have a nonzero anomalous magnetic moment. We find that the quark orbital angular momentum contributes a large logarithm to the negative helicity quark distributions in addition to its power behavior, scaling as (1-x)^5\\log^2(1-x) in the limit of x\\to 1. Our analysis shows that the ratio of the polarized over unpolarized down quark distributions, \\Delta d/d, will still approach 1 in this limit. By comparing with the experimental data, we find that this ratio should cross zero at x\\approx 0.75.

  4. Complex angular momenta approach for scattering problems in the presence of both monopoles and short range potentials

    NASA Astrophysics Data System (ADS)

    Canfora, Fabrizio

    2016-10-01

    I analyze the quantum mechanical scattering off a topological defect (such as a Dirac monopole) as well as a Yukawa-like potential(s) representing the typical effects of strong interactions. This system, due to the presence of a short-range potential, can be analyzed using the powerful technique of the complex angular momenta which, so far, has not been employed in the presence of monopoles (nor of other topological solitons). Due to the fact that spatial spherical symmetry is achieved only up to internal rotations, the partial wave expansion becomes very similar to the Jacob-Wick helicity amplitudes for particles with spin. However, since the angular-momentum operator has an extra "internal" contribution, fixed cuts in the complex angular momentum plane appear. Correspondingly, the background integral in the Regge formula does not decrease for large values of |cos θ | (namely, large values of the Mandelstam variable s ). Hence, the experimental observation of this kind of behavior could be a direct signal of nontrivial topological structures in strong interactions. The possible relations of these results with the soft Pomeron are shortly analyzed.

  5. Ion energy and angular distributions in inductively coupled Argon RF discharges

    SciTech Connect

    Woodworth, J.R.; Riley, M.E.; Meister, D.C.

    1996-03-01

    We report measurements of the energies and angular distributions of positive ions in an inductively coupled argon plasma in a GEC reference cell. Use of two separate ion detectors allowed measurement of ion energies and fluxes as a function of position as well as ion angular distributions on the discharge centerline. The inductive drive on our system produced high plasma densities (up to 10{sup 12}/cm{sup 3} electron densities) and relatively stable plasma potentials. As a result, ion energy distributions typically consisted of a single feature well separated from zero energy. Mean ion energy was independent of rf power and varied inversely with pressure, decreasing from 29 eV to 12 eV as pressure increased form 2.4 m Torr to 50 mTorr. Half-widths of the ion angular distributions in these experiments varied from 5 degrees to 12.5 degrees, or equivalently, transverse temperatures varied form 0.2 to 0.5 eV with the distributions broadening as either pressure or RF power were increased.

  6. Ion energy and angular distributions in inductively driven RF discharges in chlorine

    SciTech Connect

    Woodworth, J.R.; Riley, M.E.; Hamilton, T.W.

    1996-03-01

    In this paper, the authors report values of ion energy distributions and ion angular distributions measured at the grounded electrode of an inductively-coupled discharge in pure chlorine gas. The inductive drive in the GEC reference cell produced high plasma densities (10{sup 11}/cm{sup 3} electron densities) and stable plasma potentials. As a result, ion energy distributions typically consisted of a single peak well separated from zero energy. Mean ion energy varied inversely with pressure, decreasing from 13 to 9 eV as the discharge pressure increased from 20 to 60 millitorr. Half-widths of the ion angular distributions in these experiments varied from 6 to 7.5 degrees, corresponding to transverse energies from 0.13 to 0.21 eV. Ion energies gradually dropped with time, probably due to the buildup of contaminants on the chamber walls. Cell temperature also was an important variable, with ion fluxes to the lower electrode increasing and the ion angular distribution narrowing as the cell temperature increased. Plasmas discharges are widely used to etch semiconductors, oxides and metals in the fabrication of integrated circuits.

  7. Integrated Raman and angular scattering microscopy reveals chemical and morphological differences between activated and nonactivated CD8+ T lymphocytes

    NASA Astrophysics Data System (ADS)

    Smith, Zachary J.; Wang, Jyh-Chiang E.; Quataert, Sally A.; Berger, Andrew J.

    2010-05-01

    Integrated Raman and angular-scattering microscopy (IRAM) is a multimodal platform capable of noninvasively probing both the chemistry and morphology of a single cell without prior labeling. Using this system, we are able to detect activation-dependent changes in the Raman and elastic-scattering signals from CD8+ T cells stimulated with either Staphylococcal enterotoxin B (SEB) or phorbol myristate acetate (PMA). In both cases, results obtained from the IRAM instrument correlate well with results obtained from traditional fluorescence-based flow cytometry for paired samples. SEB-mediated activation was distinguished from resting state in CD8+ T cells by an increase in the number and mean size of small (~500-nm) elastic scatterers as well as a decrease in Raman bands, indicating changes in nuclear content. PMA-mediated activation induced a different profile in CD8+ T cells from SEB, showing a similar increase in small elastic scatterers but a different Raman change, with elevation of cellular protein and lipid bands. These results suggest the potential of this multimodal, label-free optical technique for studying processes in single cells.

  8. Flat bands in metamaterials based on angularly layered metal–dielectric scatterers

    NASA Astrophysics Data System (ADS)

    El-Jallal, Said; Torrent, Daniel

    2017-03-01

    In this work, we propose the realization of electromagnetic metamaterials in two and three dimensions by means of highly anisotropic rods and spheres. The two-dimensional case is deeply analyzed, and the realization of an anisotropic rod by means of angularly layered cylinders is proposed. The band structure of a periodic arrangement of angularly layered rods is computed, showing a low frequency band gap and some flat modes within it which increases as a function of the number of sectors in the cylinder. The system is studied by means of an effective medium approach, and it is found that the flat bands correspond to a sharp frequency region where the effective metamaterial is doubly negative. A perfect agreement is found between the dispersion curves obtained by means of the effective medium model and the full band structure computed by the finite element method. It is also found that only four sectors in the angularly layered cylinder are enough to obtain the desired double negativity, which is a promising result in view of the fabrication of the presented structures. Finally, the three-dimensional version of these materials is analyzed by means of anisotropic spheres, showing similar results.

  9. Theoretical insights into highly transparent multi-sized conducting films with high-haze and wide-angular scattering for thin film solar cells

    NASA Astrophysics Data System (ADS)

    Bai, Lisha; Liu, Bofei; Chen, Ze; Huang, Qian; Li, Baozhang; Zhang, Dekun; Sun, Jian; Wei, Changchun; Zhao, Ying; Zhang, Xiaodan

    2015-11-01

    Recent advances in light trapping schemes open up new gateways for enhancing the absorption of solar energy that approaches and overcomes the Yablonovitch 4n2 limit based on isotropic Lambertian scatterers. Achieving wide-angular scattering while maintaining a strong scattering intensity is the key to realize a Lambertian-like scatterer that may have a great potential to approach the absorption upper limit. However, few current light trapping strategies can experimentally extend the scattering angular domains in absorbers while maintaining a high scattering intensity. In this paper, we theoretically and experimentally investigate multi-sized transparent conducting oxide (TCO) films, which are comprised of micro-sized, magnetron-sputtered and chemically etched aluminum-doped zinc oxide (ZnO:Al), coated with metal organic chemical vapor deposition (MOCVD) deposited nano-sized, boron-doped zinc oxide (ZnO:B) pyramids. We demonstrate that the multi-sized TCOs in this study can efficiently increase the total transmittance in the visible spectral range, enhance the scattering intensity, successfully extend the scattering angular domains to 90°, and improve the short-circuit current density and power output of solar cells. The combination of these factors endows the TCOs with the significant potential for realizing a Lambertian-like scatterer. Accordingly, the multi-sized architecture may inspire fresh ideas for realizing more innovative light-trapping architectures.

  10. Angular distribution of Cherenkov radiation from relativistic heavy ions taking into account deceleration in the radiator

    SciTech Connect

    Bogdanov, O. V. Fiks, E. I.; Pivovarov, Yu. L.

    2012-09-15

    Numerical methods are used to study the dependence of the structure and the width of the angular distribution of Vavilov-Cherenkov radiation with a fixed wavelength in the vicinity of the Cherenkov cone on the radiator parameters (thickness and refractive index), as well as on the parameters of the relativistic heavy ion beam (charge and initial energy). The deceleration of relativistic heavy ions in the radiator, which decreases the velocity of ions, modifies the condition of structural interference of the waves emitted from various segments of the trajectory; as a result, a complex distribution of Vavilov-Cherenkov radiation appears. The main quantity is the stopping power of a thin layer of the radiator (average loss of the ion energy), which is calculated by the Bethe-Bloch formula and using the SRIM code package. A simple formula is obtained to estimate the angular distribution width of Cherenkov radiation (with a fixed wavelength) from relativistic heavy ions taking into account the deceleration in the radiator. The measurement of this width can provide direct information on the charge of the ion that passes through the radiator, which extends the potentialities of Cherenkov detectors. The isotopic effect (dependence of the angular distribution of Vavilov-Cherenkov radiation on the ion mass) is also considered.

  11. Semiclassical complex angular momentum theory and Pade reconstruction for resonances, rainbows, and reaction thresholds

    SciTech Connect

    Sokolovski, D.; Msezane, A.Z.

    2004-09-01

    A semiclassical complex angular momentum theory, used to analyze atom-diatom reactive angular distributions, is applied to several well-known potential (one-particle) problems. Examples include resonance scattering, rainbow scattering, and the Eckart threshold model. Pade reconstruction of the corresponding matrix elements from the values at physical (integral) angular momenta and properties of the Pade approximants are discussed in detail.

  12. Angular distribution of photoelectrons from atomic oxygen, nitrogen and carbon. [in upper atmosphere

    NASA Technical Reports Server (NTRS)

    Manson, S. J.; Kennedy, D. J.; Starace, A. F.; Dill, D.

    1974-01-01

    The angular distributions of photoelectrons from atomic oxygen, nitrogen, and carbon are calculated. Both Hartree-Fock and Hartree-Slater (Herman-Skillman) wave functions are used for oxygen, and the agreement is excellent; thus only Hartree-Slater functions are used for carbon and nitrogen. The pitch-angle distribution of photoelectrons is discussed, and it is shown that previous approximations of energy-independent isotropic or sin squared theta distributions are at odds with the authors' results, which vary with energy. This variation with energy is discussed, as is the reliability of these calculations.

  13. Sideways-peaked angular distributions in hadron-induced multifragmentation: Shock waves, geometry, or kinematics?

    SciTech Connect

    Hsi, W.; Kwiatkowski, K.; Wang, G.; Bracken, D.S.; Cornell, E.; Ginger, D.S.; Viola, V.E.; Yoder, N.R.; Korteling, R.G.; Gimeno-Nogues, F.; Ramakrishnan, E.; Rowland, D.; Yennello, S.J.; Huang, R.; Lynch, W.G.; Tsang, M.B.; Xi, H.; Breuer, H.; Morley, K.B.; Gushue, S.; Remsberg, L.P.; Friedman, W.A.; Botvina, A.

    1998-07-01

    Exclusive studies of sideways-peaked angular distributions for intermediate-mass fragments (IMFs) produced in hadron-induced reactions have been performed with the Indiana silicon sphere (ISiS) detector array. The effect becomes prominent for beam momenta above about 10thinspGeV/c. Both the magnitude of the effect and the peak angle increase as a function of fragment multiplicity and charge. When gated on IMF kinetic energy, the angular distributions evolve from forward peaked to nearly isotropic as the fragment energy decreases. Fragment-fragment correlation studies show no evidence for a preferred angle that might signal a fast dynamic breakup mechanism. Moving-source and intranuclear cascade simulations suggest a possible kinematic origin arising from significant transverse momentum imparted to the recoil nucleus during the fast cascade. A two-step cascade and statistical multifragmentation calculation is consistent with the data. {copyright} {ital 1998} {ital The American Physical Society}

  14. Measurement of the angular distribution in anti-p p ---> psi(2S) ---> e+ e-

    SciTech Connect

    Ambrogiani, M.; Andreotti, M.; Argiro, S.; Bagnasco, S.; Baldini, W.; Bettoni, D.; Borreani, G.; Buzzo, A.; Calabrese, R.; Cester, R.; Cibinetto, G.; Dalpiaz, P.; Fan, X.; Garzoglio, G.; Gollwitzer, K.E.; Graham, M.; Hahn, A.; Hu, M.; Jin, S.; Joffe, D.; Kasper, J.; /Fermilab /INFN, Ferrara /Ferrara U. /INFN, Genoa /Genoa U. /INFN, Turin /Turin U. /Northwestern U. /UC, Irvine /Minnesota U.

    2004-12-01

    The authors present the first measurement of the angular distribution for the exclusive process {bar p}p {yields} {psi}(2S) {yields} e{sup +}e{sup -} based on a sample of 6844 events collected by the Fermilab E835 experiment. They find that the angular distribution is well described by the expected functional form dN/d cos {theta}* {proportional_to} 1 + {lambda} cos{sup 2} {theta}*, where {theta}* is the angle between the antiproton and the electron in the center of mass frame, with {lambda} = 0.67 {+-} 0.15(stat.) {+-} 0.04(sys.). The measured value for {lambda} implies a small but non zero {psi}(2S) helicity 0 formation amplitude in {bar p}p, comparable to what is observed in J/{psi} decays to baryon pairs.

  15. Effects due to adsorbed atoms upon angular and energy distributions of surface produced negative hydrogen ions

    NASA Astrophysics Data System (ADS)

    Wada, M.; Bacal, M.; Kasuya, T.; Kato, S.; Kenmotsu, T.; Sasao, M.

    2013-02-01

    Exposure to Cs added hydrogen discharge makes surface of plasma grid of a negative hydrogen ion source covered with Cs and hydrogen. A Monte-Carlo particle simulation code ACAT was run to evaluate the effects due to adsorbed Cs and H atoms upon the angular and energy distributions of H atoms leaving the surface. Accumulation of H atoms on the surface reduces particle reflection coefficients and the mean energy of backscattered H atoms. Angular distributions of H atoms reflected from the hydrogen covered surface tend to be under-cosine at lower energies. Desorption of adsorbed H atoms is more efficient for hydrogen positive ions than for Cs positive ions at lower incident energy. At higher energy more than 100 eV, Cs ions desorb adsorbed H atoms more efficiently than hydrogen ions.

  16. Photoelectron kinetic and angular distributions for the ionization of aligned molecules using a HHG source

    NASA Astrophysics Data System (ADS)

    Rouzée, Arnaud; Kelkensberg, Freek; Kiu Siu, Wing; Gademann, Georg; Lucchese, Robert R.; Vrakking, Marc J. J.

    2012-04-01

    We present an experimental and theoretical investigation of the angular distributions of electrons ejected in aligned molecules by extreme ultra-violet ionization using a high harmonic generation (HHG) source. Impulsive alignment in O2, N2 and CO molecules was achieved using a near-IR laser pulse and the photoelectron angular distribution after ionization by a fs harmonic comb composed of harmonic H11 to H29 (17.5-46 eV) was recorded at the maximum of both alignment and anti-alignment. The experiment reveals signatures that are specific for the electronic orbitals that are ionized as well as the onset of the influence of the molecular structure and is well reproduced by theoretical calculations based on the multichannel Schwinger configuration interaction method.

  17. Neutron angular distribution in a plasma focus obtained using nuclear track detectors.

    PubMed

    Castillo-Mejía, F; Herrera, J J E; Rangel, J; Golzarri, J I; Espinosa, G

    2002-01-01

    The dense plasma focus (DPF) is a coaxial plasma gun in which a high-density, high-temperature plasma is obtained in a focused column for a few nanoseconds. When the filling gas is deuterium, neutrons can be obtained from fusion reactions. These are partially due to a beam of deuterons which are accelerated against the background hot plasma by large electric fields originating from plasma instabilities. Due to a beam-target effect, the angular distribution of the neutron emission is anisotropic, peaked in the forward direction along the axis of the gun. The purpose of this work is to illustrate the use of CR-39 nuclear track detectors as a diagnostic tool in the determination of the time-integrated neutron angular distribution. For the case studied in this work, neutron emission is found to have a 70% contribution from isotropic radiation and a 30% contribution from anisotropic radiation.

  18. Drell-Yan Angular Distributions at the E906 SeaQuest Experiment

    NASA Astrophysics Data System (ADS)

    Kleinjan, David

    2016-09-01

    Measurement of Drell-Yan angular distributions in the Collins-Soper frame provide a unique study of QCD. Previous experimental results showed a violation of the Lam-Tung relation (1 - λ ≠ 2 ν). This violation could be described by a range of non-perturbative effects, including the naive T-odd Boer-Mulders TMD, which describes spin-momentum correlations in the nucleon. Presently, E906/SeaQuest experiment at Fermilab can measure Drell-Yan dimuon pairs produced from a 120 GeV unpolarized proton beam directed on various nuclear targets. The Drell-Yan angular distributions will be measured at higher-x than previous experiments, further disentangling the role the Boer-Mulders TMD and other non-perturbative effects play in the structure of the nucleon. SeaQuest.

  19. Retrieving orbital angular momentum distribution of light with plasmonic vortex lens

    PubMed Central

    Zhou, Hailong; Dong, Jianji; Zhang, Jihua; Zhang, Xinliang

    2016-01-01

    We utilize a plasmonic vortex lens (PVL) to retrieve the orbital angular momentum (OAM) distribution of light. The OAM modes are coupled to the surface plasmon polaritons (SPPs) in the form of various Bessel functions respectively. By decomposing the interference pattern of SPPs into these Bessel functions, we can retrieve the relative amplitude and the relative phase of input OAM modes simultaneously. Our scheme shows advantage in integration and can measure hybrid OAM states by one measurement. PMID:27255406

  20. Angular distributions for /sup 16/O(/gamma/,p)/sup 15/N at intermediate energies

    SciTech Connect

    Adams, G.S.; Kinney, E.R.; Matthews, J.L.; Sapp, W.W.; Soos, T.; Owens, R.O.; Turley, R.S.; Pignault, G.

    1988-12-01

    The photoproton knockout reaction on /sup 16/O leaving /sup 15/N in low-lying bound states has been observed over the photon energy range from 196 to 361 MeV. The angular distribution for the reaction populating the ground state of /sup 15/N develops sharp structure as the photon energy is increased but that for population of the excited states is smooth. The results are not explained by existing theoretical models.

  1. Angular velocity distribution of a granular planar rotator in a thermalized bath.

    PubMed

    Piasecki, J; Talbot, J; Viot, P

    2007-05-01

    The kinetics of a granular planar rotator with a fixed center undergoing inelastic collisions with bath particles is analyzed both numerically and analytically by means of the Boltzmann equation. The angular velocity distribution evolves from quasi-Gaussian in the Brownian limit to an algebraic decay in the limit of an infinitely light particle. In addition, we compare this model to that of a planar rotator with a free center and discuss the prospects for experimental confirmation of these results.

  2. Angular momentum distribution during the collapse of primordial star-forming clouds

    NASA Astrophysics Data System (ADS)

    Dutta, Jayanta

    2016-01-01

    It is generally believed that angular momentum is distributed during the gravitational collapse of the primordial star forming cloud. However, so far there has been little understanding of the exact details of the distribution. We use the modified version of the Gadget-2 code, a three-dimensional smoothed-particle hydrodynamics simulation, to follow the evolution of the collapsing gas in both idealized as well as more realistic minihalos. We find that, despite the lack of any initial turbulence and magnetic fields in the clouds the angular momentum profile follows the same characteristic power-law that has been reported in studies that employed fully self-consistent cosmological initial conditions. The fit of the power-law appears to be roughly constant regardless of the initial rotation of the cloud. We conclude that the specific angular momentum of the self-gravitating rotating gas in the primordial minihalos maintains a scaling relation with the gas mass as L ∝ M^{1.125}. We also discuss the plausible mechanisms for the power-law distribution.

  3. The internal energy distribution of NO and N 2 scattering from defective surfaces

    NASA Astrophysics Data System (ADS)

    Pierro, William; Castejón, Henry J.

    2008-11-01

    The internal energy distribution of NO and N 2 scattering from a defective surfaces has been studied using classical molecular dynamics. Stochastic trajectory simulations were used to calculate the final rotational excitation, angular distribution and trapping probabilities of N 2 and NO scattering from clean Ag(1 1 1) surfaces, with adatoms and with vacancies. Calculations reproduce well the experimental results for NO and N 2 scattering from clean surfaces. NO undergoes more extensive rotational excitation than N 2 on clean and defective surfaces. Scattering is more inelastic on defective surfaces and adatoms defects appear to promote rotational excitation more efficiently than vacancies. Trapping exhibits a complex behavior. Dynamical corrugation causes trapping of NO on clean Ag(1 1 1) to exhibit a "crossover" behavior. That is, the value of n in the standard functional dependence of trapping on the incident energy, Eicos nθi, switches sign as the incident energy increases. This behavior is also observed in the case of N 2 scattering from a surface with adatoms, but in this case is caused by the static corrugation. It appears that the breaking of the 2-D symmetry of the surface (i.e. static corrugation) compensates for the lack of anisotropy in the interaction potential (i.e. dynamical corrugation) for N 2/Ag(1 1 1). Adatom defects increase trapping for NO molecules impinging on the surface with glancing trajectories while vacancies have the opposite effect.

  4. Lifetime of reactive scattering resonances: Q-matrix analysis and angular momentum dependence for the F+H2 reaction by the hyperquantization algorithm.

    PubMed

    Aquilanti, Vincenzo; Cavalli, Simonetta; Simoni, Andrea; Aguilar, Antonio; Lucas, Josep Maria; De Fazio, Dario

    2004-12-15

    We report a study on the behavior with total angular momentum J of several resonances occurring at collision energies below or slightly above the reaction barrier in the F+H2-->HF+H reaction. Resonance positions and widths are extracted from exact time-independent quantum mechanical calculations using the hyperquantization algorithm and Smith's Q-matrix formalism which exploits complete S-matrix information. The results confirm previous work but provide much greater insight. Identification of quasi-bound states responsible for the resonances based on adiabatic models for the long-range atom-molecule interactions both in the entrance and exit channels, is successful except for the feature occurring at the lowest energy, which is found to overlap with an exit-channel resonance for J approximately 7. The two features are analyzed as overlapping resonances and their excellent Lorentzian fits, with well-behaved J-dependences of positions and widths, support the interpretation of the low-energy feature as a resonance to be associated to the triatomic transition state of the reaction. Resonance role on the reactive observables (integral cross sections and angular distributions) is investigated. The mechanism leading to forward scattering in the reactive differential cross section is commented, while the effects on rate constants, as well as the sensitivity of the resonance pattern to modification of the potential energy surface, are fully discussed elsewhere.

  5. Kinetic Energy and Angular Distributions of He and Ar Atoms Evaporating from Liquid Dodecane.

    PubMed

    Patel, Enamul-Hasan; Williams, Mark A; Koehler, Sven P K

    2017-01-12

    We report both kinetic energy and angular distributions for He and Ar atoms evaporating from C12H26. All results were obtained by performing molecular dynamics simulations of liquid C12H26 with around 10-20 noble gas atoms dissolved in the liquid and by subsequently following the trajectories of the noble gas atoms after evaporation from the liquid. Whereas He evaporates with a kinetic energy distribution of (1.05 ± 0.03) × 2RT (corrected for the geometry used in experiments: (1.08 ± 0.03) × 2RT, experimentally obtained value: (1.14 ± 0.01) × 2RT), Ar displays a kinetic energy distribution that better matches a Maxwell-Boltzmann distribution at the temperature of the liquid ((0.99 ± 0.04) × 2RT). This behavior is also reflected in the angular distributions, which are close to a cosine distribution for Ar but slightly narrower, especially for faster atoms, in the case of He. This behavior of He is most likely due to the weak interaction potential between He and the liquid hydrocarbon.

  6. Energy and angular distributions of electrons emitted by direct double auger decay.

    PubMed

    Viefhaus, Jens; Cvejanović, Slobodan; Langer, Burkhard; Lischke, Toralf; Prümper, Georg; Rolles, Daniel; Golovin, Alexander V; Grum-Grzhimailo, Alexei N; Kabachnik, Nikolai M; Becker, Uwe

    2004-02-27

    We have observed the direct L(2,3)MMM double Auger transition after photoionization of the 2p shell of argon by angle-resolved electron-electron coincidence spectroscopy. The process is responsible for about 20% of the observed Auger electron intensity. In contrast to the normal Auger lines, the spectra in double Auger decay show a continuous intensity distribution. The energy and angular distributions of the emitted electrons allow one to obtain information on the electron correlations giving rise to the double Auger process as well as the symmetry of the associated two-electron continuum state.

  7. Proximal distributions from angular correlations: A measure of the onset of coarse-graining

    NASA Astrophysics Data System (ADS)

    Dyer, Kippi M.; Pettitt, B. Montgomery

    2013-12-01

    In this work we examine and extend the theory of proximal radial distribution functions for molecules in solution. We point out two formal extensions, the first of which generalizes the proximal distribution function hierarchy approach to the complete, angularly dependent molecular pair distribution function. Second, we generalize from the traditional right-handed solute-solvent proximal distribution functions to the left-handed distributions. The resulting neighbor hierarchy convergence is shown to provide a measure of the coarse-graining of the internal solute sites with respect to the solvent. Simulation of the test case of a deca-alanine peptide shows that this coarse-graining measure converges at a length scale of approximately 5 amino acids for the system considered.

  8. Improved light trapping in microcrystalline silicon solar cells by plasmonic back reflector with broad angular scattering and low parasitic absorption

    NASA Astrophysics Data System (ADS)

    Tan, Hairen; Sivec, Laura; Yan, Baojie; Santbergen, Rudi; Zeman, Miro; Smets, Arno H. M.

    2013-04-01

    We show experimentally that the photocurrent of thin-film hydrogenated microcrystalline silicon (μc-Si:H) solar cells can be enhanced by 4.5 mA/cm2 with a plasmonic back reflector (BR). The light trapping performance is improved using plasmonic BR with broader angular scattering and lower parasitic absorption loss through tuning the size of silver nanoparticles. The μc-Si:H solar cells deposited on the improved plasmonic BR demonstrate a high photocurrent of 26.3 mA/cm2 which is comparable to the state-of-the-art textured Ag/ZnO BR. The commonly observed deterioration of fill factor is avoided by using μc-SiOx:H as the n-layer for solar cells deposited on plasmonic BR.

  9. An experimental investigation of the angular scattering and backscattering behaviors of the simulated clouds of the outer planets

    NASA Technical Reports Server (NTRS)

    Sassen, K.

    1984-01-01

    A cryogenic, 50 liter volume Planetary Cloud Simulation Chamber has been constructed to permit the laboratory study of the cloud compositions which are likely to be found in the atmospheres of the outer planets. On the basis of available data, clouds composed of water ice, carbon dioxide, and liquid and solid ammonia and methane, both pure and in various mixtures, have been generated. Cloud microphysical observations have been permitted through the use of a cloud particle slide injector and photomicrography. Viewports in the lower chamber have enabled the collection of cloud backscattering data using 633 and 838 nm laser light, including linear depolarization ratios and complete Stokes parameterization. The considerable technological difficulties associated with the collection of angular scattering patterns within the chamber, however, could not be completely overcome.

  10. Stochastic model of angular distributions of fragments originating from the fission of excited compound nuclei

    SciTech Connect

    Hiryanov, R. M.; Karpov, A. V.; Adeev, G. D.

    2008-08-15

    The anisotropy of angular distributions of fission fragments and the average multiplicity of prescission neutrons were calculated within a stochastic approach to fission dynamics on the basis of three-dimensional Langevin equations. This approach was combined with a Monte Carlo algorithm for the degree of freedom K (projection of the total angular momentum I onto the fission axis). The relaxation time {tau}{sub K} in the coordinate K was considered as a free parameter of the model; it was estimated on the basis of a fit to experimental data on the anisotropy of angular distributions. Specifically, the relaxation time {tau}{sub K} was estimated at 2 x 10{sup -21} s for the compound nuclei {sup 224}Th and {sup 225}Pa and at 4 x 10{sup -21} s for the heavier nuclei {sup 248}Cf, {sup 254}Fm, and {sup 264}Rf. The potential energy was calculated on the basis of the liquid-drop model with allowance for finiteness of the range of nuclear forces and for the diffuseness of the nuclear surface. A modified one-body viscosity mechanism featuring a coefficient k{sub s} that takes into account the reduction of the contribution from the wall formula was used to describe collective-energy dissipation. The coefficient k{sub s} was also treated as a free parameter and was estimated at 0.5 on the basis of a fit to experimental data on the average prescission multiplicity of neutrons.

  11. Angular Broadening of Intraday Variable AGNs II. Interstellar and Intergalactic Scattering

    DTIC Science & Technology

    2008-01-01

    scattering from any possible intergalactic contribution, we have searched for pulsars within 1 of theAGNs in our sample.We find no pulsars this close to any...of our sources.Given the relatively low density of pulsars on the sky, a significantly larger sample of AGNs would be required in order to make such a...in pulsar dynamic spectra (Hill et al. 2005). We can also use the difference between the scintillating and nonscintillating sources to set

  12. Correlation of ultrasonic scatterer size estimates for the statistical analysis and optimization of angular compounding

    NASA Astrophysics Data System (ADS)

    Gerig, Anthony; Chen, Quan; Zagzebski, James; Varghese, Tomy

    2004-09-01

    Ultrasonic scatterer size estimates generally have large variances due to the inherent noise of spectral estimates used to calculate size. Compounding partially correlated size estimates associated with the same tissue, but produced with data acquired from different angles of incidence, is an effective way to reduce the variance without making dramatic sacrifices in spatial resolution. This work derives theoretical approximations for the correlation between these size estimates, and the coherence between their associated spectral estimates, as functions of ultrasonic system parameters. A Gaussian spatial autocorrelation function is assumed to adequately model scatterer shape. Both approximations compare favorably with simulation results, which consider validation near the focus. Utilization of the correlation/coherence expressions for statistical analysis and optimization is discussed. Approximations, such as the invariance of phase and amplitude terms with angle, are made to obtain closed-form solutions to the derived spectral coherence near the focus and permit analytical optimization analysis. Results indicate that recommended parameter adjustments for performance improvement generally depend upon whether, for the system under consideration, the primary source of change in total coherence with rotation is phase term variation due to the change in the relative position of scattering sites, or field amplitude term variation due to beam movement.

  13. Core-Hole Molecular Frame X-Ray Photoelectron Angular Distributions as Molecular Geometry Probes

    NASA Astrophysics Data System (ADS)

    Trevisan, Cynthia; Williams, Joshua; Menssen, Adrian; Weber, Thorsten; Rescigno, Thomas; McCurdy, Clyde; Landers, Allen

    2014-05-01

    We present experimental and theoretical results for the angular dependence of electrons ejected from the core orbitals of ethane (C2H6) and tetrafluoromethane (CF4) in an effort to understand the origin of the imaging effect by which the molecular frame photoelectron angular distributions (MFPADs) for removing an electron from a 1s orbital effectively image the geometry of a class of molecules. At low energies, our calculations predict the same imaging effect in X2H6 previously found in CH4, H2O and NH3. By contrast, in experiment and calculations CF4 displays an anti-imaging effect, whereby the electron ejected by core photoionization has the tendency to avoid molecular bonds, if averaged over directions of polarization of the incident X-ray beam. Our measurements employ the COLTRIMS method and the calculations were performed with the Complex Kohn Variational method.

  14. Fast neutrino flavor conversions near the supernova core with realistic flavor-dependent angular distributions

    NASA Astrophysics Data System (ADS)

    Dasgupta, Basudeb; Mirizzi, Alessandro; Sen, Manibrata

    2017-02-01

    It has been recently pointed out that neutrino fluxes from a supernova can show substantial flavor conversions almost immediately above the core. Using linear stability analyses and numerical solutions of the fully nonlinear equations of motion, we perform a detailed study of these fast conversions, focussing on the region just above the supernova core. We carefully specify the instabilities for evolution in space or time, and find that neutrinos travelling towards the core make fast conversions more generic, i.e., possible for a wider range of flux ratios and angular asymmetries that produce a crossing between the zenith-angle spectra of νe and bar nue. Using fluxes and angular distributions predicted by supernova simulations, we find that fast conversions can occur within tens of nanoseconds, only a few meters away from the putative neutrinospheres. If these fast flavor conversions indeed take place, they would have important implications for the supernova explosion mechanism and nucleosynthesis.

  15. New Statistical Results on the Angular Distribution of Gamma-Ray Bursts

    SciTech Connect

    Balazs, Lajos G.; Horvath, Istvan; Vavrek, Roland

    2008-05-22

    We presented the results of several statistical tests of the randomness in the angular sky-distribution of gamma-ray bursts in BATSE Catalog. Thirteen different tests were presented based on Voronoi tesselation, Minimal spanning tree and Multifractal spectrum for five classes (short1, short2, intermediate, long1, long2) of gamma-ray bursts, separately. The long1 and long2 classes are distributed randomly. The intermediate subclass, in accordance with the earlier results of the authors, is distributed non-randomly. Concerning the short subclass earlier statistical tests also suggested some departure from the random distribution, but not on a high enough confidence level. The new tests presented in this article suggest also non-randomness here.

  16. Angular distribution of thick-target bremsstrahlung produced by electrons with initial energies ranging from 10 to 20 keV incident on Ag

    SciTech Connect

    Gonzales, D.; Cavness, B.; Williams, S.

    2011-11-15

    Experimental results are presented comparing the intensities of the bremsstrahlung produced by electrons with initial energies ranging from 10 to 20 keV incident on a thick Ag target, measured at forward angles in the range of 0 degree sign to 55 degree sign . When the data are corrected for attenuation due to photon absorption within the target, the results indicate that the detected radiation is distributed anisotropically only at photon energies k that are approximately equal to the initial energy of the incident electrons E{sub 0}. The results of our experiments suggest that, as k/E{sub 0}{yields} 0, the detected radiation essentially becomes isotropic due primarily to the scattering of electrons within the target. A comparison to the theory of Kissel et al.[At. Data Nucl. Data Tables 28, 381 (1983)] suggests that the angular distribution of bremsstrahlung emitted by electrons incident on thick targets is similar to the angular distribution of bremsstrahlung emitted by electrons incident on free-atom targets only when k/E{sub 0}{approx_equal} 1. The experimental data also are in approximate agreement with the angular distribution predictions of the Monte Carlo program penelope.

  17. Design method for a laser line beam shaper of a general 1D angular power distribution

    NASA Astrophysics Data System (ADS)

    Oved, E.; Oved, A.

    2016-05-01

    Laser line is a beam of laser, spanned in one direction using a beam shaper to form a fan of light. This illumination tool is important in laser aided machine vision, 3D scanners, and remote sensing. For some applications the laser line should have a specific angular power distribution. If the distribution is nonsymmetrical, the beam shaper is required to be nonsymmetrical freeform, and its design process using optical design software is time consuming due to the long optimization process which usually converges to some local minimum. In this paper we introduce a new design method of a single element refractive beam shaper of any predefined general 1D angular power distribution. The method makes use of a notion of "prism space", a geometrical representation of all double refraction prisms, and any 1D beam shaper can be described by a continuous curve in this space. It is shown that infinitely many different designs are possible for any given power distribution, and it is explained how an optimal design is selected among them, based on criteria such as high transmission, low surface slopes, robustness to manufacturing errors etc. The method is non-parametric and hence does not require initial guess of a functional form, and the resultant optical surfaces are described by a sequence of points, rather than by an analytic function.

  18. Ro-vibrational excitation, alignment and orientation distributions of fast non-dissociatively scattered molecules

    NASA Astrophysics Data System (ADS)

    Harder, R.; Snowdon, K. J.

    1997-12-01

    The ro-vibrational distribution of fast diatomic molecules scattered from an uncorrugated surface under strongly dissipative glancing incidence conditions is calculated. The classical trajectory simulation includes potential surface switching associated with hot-electron scattering processes. Both ro-vibrational excitation and strong alignment of the classical angular momentum vector in the surface plane ("cartwheel motion") are observed, independent of the occurrence of potential surface switching. Ro-vibrational excitation is enhanced strongly by transitions between potential surfaces. The resultant larger proportion of molecules in highly rotationally excited states leads to a higher fraction of cartwheel-aligned molecules in the scattered molecule ensemble. The molecules which dissociate in the simulation are characterised by surface normal peaked internuclear axis orientation distributions. This is in agreement with the results of recent experiments [A. Nesbitt et al., Surf. Sci. 331-333 (1995) 321]. We observe, in addition, an enhanced rotational population of "topspin" oriented molecules, which arises from differences in the surface parallel oriented friction forces acting on each atom of the molecule. Glancing incidence scattering from well-prepared close-packed metal surfaces would appear to provide an efficient, general method to obtain a beam of preferentially aligned fast neutral diatomic molecules.

  19. Measurement of angular distribution of neutron flux for the 6MeV race-track microtron based pulsed neutron source.

    PubMed

    Patil, B J; Chavan, S T; Pethe, S N; Krishnan, R; Dhole, S D

    2010-09-01

    The 6MeV race track microtron based pulsed neutron source has been designed specifically for the elemental analysis of short lived activation products, where the low neutron flux requirement is desirable. Electrons impinges on a e-gamma target to generate bremsstrahlung radiations, which further produces neutrons by photonuclear reaction in gamma-n target. The optimisation of these targets along with their spectra were estimated using FLUKA code. The measurement of neutron flux was carried out by activation of vanadium at different scattering angles. Angular distribution of neutron flux indicates that the flux decreases with increase in the angle and are in good agreement with the FLUKA simulation.

  20. Angular distributions of sputtered atoms for low-energy heavy ions, medium ions and light ions

    NASA Astrophysics Data System (ADS)

    Yamamura, Yasunori; Mizuno, Yoshiyuki; Kimura, Hidetoshi

    1986-03-01

    The angular distributions of sputtered atoms for the near-threshold sputtering of heavy ions, medium ions, and light ions have been investigated by a few-collision model and the ACAT computer simulation code. For heavy-ion sputtering the preferential angle of sputtered atoms is about 50° which is measured from the surface normal, while in the case of the near-threshold light-ion sputtering the preferential angles are nearly equal to the surface normal and do not depend on angle of incidence. It is found that the agreement between the ACAT preferential angles and theoretical values due to a few-collision model is very good.

  1. Alpha-Particle Angular Distributions of At and Rn Isotopes and Their Relation to Nuclear Structure

    SciTech Connect

    NICOLE Collaboration and ISOLDE Collaboration

    1996-12-01

    We report on an extensive on-line nuclear orientation study of the angular distribution of {alpha} particles emitted in the favored decay of neutron deficient At and Rn nuclei near the {ital N}=126 shell closure. Surprisingly large anisotropies were observed, showing pronounced changes from one isotope to another. Comparing these data with several theoretical models shows that anisotropic {alpha} emission in favored decays from near-spherical nuclei can well be explained within the shell model, implying that it is mainly determined by the structure of the decaying nucleus. {copyright} {ital 1996 The American Physical Society.}

  2. Probing molecular frame photoelectron angular distributions via high-order harmonic generation from aligned molecules

    NASA Astrophysics Data System (ADS)

    Lin, C. D.; Jin, Cheng; Le, Anh-Thu; Lucchese, R. R.

    2012-10-01

    We analyse the theory of single photoionization (PI) and high-order harmonic generation (HHG) by intense lasers from aligned molecules. We show that molecular-frame photoelectron angular distributions can be extracted from these measurements. We also show that, under favourable conditions, the phase of PI transition dipole matrix elements can be extracted from the HHG spectra. Furthermore, by varying the polarization axis of the HHG generating laser with respect to the polarization axis of the aligning laser, it is possible to extract angle-dependent tunnelling ionization rates for different subshells of the molecules.

  3. Angular distribution of isothermal expansions of non-quasi-neutral plasmas into a vacuum

    NASA Astrophysics Data System (ADS)

    Yongsheng, Huang; Xiaojiao, Duan; Yijin, Shi; Xiaofei, Lan; Zhixin, Tan; Naiyan, Wang; Xiuzhang, Tang; Yexi, He

    2008-04-01

    A two dimensional planar model is developed for self-similar isothermal expansions of non-quasi-neutral plasmas into a vacuum of solid targets heated by ultraintense laser pulses. The angular ion distribution and the dependence of the maximum ion velocity on laser parameters and target thicknesses are predicted. Considering the self-generated magnetic field of plasma beams as a perturbation, the ion energy on edge at the ion opening angle has an increase of 2% relative to that on the front center. Therefore, the self-generated magnetic field of plasma beams is not large enough to interpret for the ring structures.

  4. A Large-alphabet Quantum Key Distribution Protocol Using Orbital Angular Momentum Entanglement

    NASA Astrophysics Data System (ADS)

    Zhao, Sheng-Mei; Gong, Long-Yan; Li, Yong-Qiang; Yang, Hua; Sheng, Yu-Bo; Cheng, Wei-Wen

    2013-06-01

    We experimentally demonstrate a quantum key distribution protocol using entangled photon pairs in orbital angular momentum (OAM). Here Alice uses a fixed phase hologram to modulate her OAM state on one photon with a spatial light modulator (SLM), while Bob uses the designed N different phase holograms for his N-based keys on the other photon with his SLM. With coincidences, Alice can fully retrieve the keys sent by Bob without reconciliation. We report the experiment results with N = 3 and OAM eigenmodes |l = ±1>, and discuss the security from the light path and typical attacks.

  5. Analyzing angular distributions for two-step dissociation mechanisms in velocity map imaging.

    PubMed

    Straus, Daniel B; Butler, Lynne M; Alligood, Bridget W; Butler, Laurie J

    2013-08-15

    Increasingly, velocity map imaging is becoming the method of choice to study photoinduced molecular dissociation processes. This paper introduces an algorithm to analyze the measured net speed, P(vnet), and angular, β(vnet), distributions of the products from a two-step dissociation mechanism, where the first step but not the second is induced by absorption of linearly polarized laser light. Typically, this might be the photodissociation of a C-X bond (X = halogen or other atom) to produce an atom and a momentum-matched radical that has enough internal energy to subsequently dissociate (without the absorption of an additional photon). It is this second step, the dissociation of the unstable radicals, that one wishes to study, but the measured net velocity of the final products is the vector sum of the velocity imparted to the radical in the primary photodissociation (which is determined by taking data on the momentum-matched atomic cophotofragment) and the additional velocity vector imparted in the subsequent dissociation of the unstable radical. The algorithm allows one to determine, from the forward-convolution fitting of the net velocity distribution, the distribution of velocity vectors imparted in the second step of the mechanism. One can thus deduce the secondary velocity distribution, characterized by a speed distribution P(v1,2°) and an angular distribution I(θ2°), where θ2° is the angle between the dissociating radical's velocity vector and the additional velocity vector imparted to the product detected from the subsequent dissociation of the radical.

  6. Scattering by two-component random distributions of spheres.

    PubMed

    Burke, J E; Kays, T H; Kulp, J L; Twersky, V

    1968-12-01

    Theory and prototype (at wavelength lambda = 5 mm) partial coherence scattering data for optical applications in diagnostic measurements on two component suspensions or gases are presented. Results are given for equal volume mixtures of two sizes of moving randomly distributed large spheres for all realizable values of the fractional volume w (the fraction of the slab region container filled by scattering material). The relative index of refraction of the spheres was about 1.017, and their diameters were 6.52lambda and 3.33lambda (so that we used about eight times as many small spheres as large ones for each value of w). The spheres were of lightweight Styrofoam, and their motion arose from turbulent air streams (flowing through grids that form the top and bottom of a Styrofoam container), and the data were obtained in real time by processing the instantaneous phase quadrature components of the scattered field with an electronic analog computer. We give results for the forward scattered coherent phase, for the coherent, incoherent, and total intensities, and for the covariant magnitude and phase which (together with the incoherent intensity) provide the variances and covariance of the instantaneous phase quadrature components. We also consider certain reduced data records (from which the major effects of scatterer size and material have been eliminated) to indicate the dependence of the scattering on the fractional volume and to facilitate comparison with earlier data for distributions of identical spheres.

  7. Combining near-field hyperspectral imaging and far-field spectral-angular distribution to develop mid-field white LED optical models with spatial color deviation.

    PubMed

    Lee, Tsung-Xian; Lu, Tsung-Lin; Chen, Bo-Song

    2016-07-11

    The integration of spatial distribution of light intensity and color in the midfield is instrumental for LED optical design. On the basis of this rationale, we proposed an accurate and convenient method for developing white LED optical models. Near-field hyperspectral images and far-field spectral-angular distributions were integrated to illustrate changes in spatial light intensity and color distribution in the mid-field, to the exclusion of the absorption, conversion, and scattering of phosphors. The corresponding optical models were developed for three LED samples under different packaging conditions. Their normalized cross-correlation values for spatial light intensity and correlated-color-temperature distribution between simulation and measurement averaged as high as 0.995 and 0.99 respectively, which validated the accuracy and feasibility of the proposed method.

  8. W production at LHC: lepton angular distributions and reference frames for probing hard QCD

    NASA Astrophysics Data System (ADS)

    Richter-Was, E.; Was, Z.

    2017-02-01

    Precision tests of the Standard Model in the Strong and Electroweak sectors play a crucial role, among the physics program of LHC experiments. Because of the nature of proton-proton processes, observables based on the measurement of the direction and energy of final state leptons provide the most precise probes of such processes. In the present paper, we concentrate on the angular distribution of leptons from W → ℓ ν decays in the lepton-pair rest-frame. The vector nature of the intermediate state imposes that distributions are to a good precision described by spherical harmonics of at most second order. We argue, that contrary to general belief often expressed in the literature, the full set of angular coefficients can be measured experimentally, despite the presence of escaping detection neutrino in the final state. There is thus no principle difference with respect to the phenomenology of the Z/γ → ℓ ^+ ℓ ^- Drell-Yan process. We show also, that with the proper choice of the reference frames, only one coefficient in this polynomial decomposition remains sizable, even in the presence of one or more high p_T jets. The necessary stochastic choice of the frames relies on probabilities independent from any coupling constants. In this way, electroweak effects (dominated by the V-A nature of W couplings to fermions), can be better separated from the ones of strong interactions. The separation is convenient for the measurements interpretation.

  9. Interpretation of angular distributions of Z-boson production at colliders

    NASA Astrophysics Data System (ADS)

    Peng, Jen-Chieh; Chang, Wen-Chen; McClellan, Randall Evan; Teryaev, Oleg

    2016-07-01

    High precision data of dilepton angular distributions in γ* / Z production were reported recently by the CMS Collaboration covering a broad range of the dilepton transverse momentum, qT, up to ∼ 300 GeV. Pronounced qT dependencies of the λ and ν parameters, characterizing the cos2 ⁡ θ and cos ⁡ 2 ϕ angular distributions, were found. Violation of the Lam-Tung relation was also clearly observed. We show that the qT dependence of λ allows a determination of the relative contributions of the q q bar annihilation versus the qG Compton process. The violation of the Lam-Tung relation is attributed to the presence of a non-zero component of the q - q bar axis in the direction normal to the ;hadron plane; formed by the colliding hadrons. The magnitude of the violation of the Lam-Tung relation is shown to reflect the amount of this 'non-coplanarity;. The observed qT dependencies of λ and ν from the CMS and the earlier CDF data can be well described using this approach.

  10. Time-energy mapping of photoelectron angular distribution: application to photoionization stereodynamics of nitric oxide.

    PubMed

    Suzuki, Yoshi-Ichi; Tang, Ying; Suzuki, Toshinori

    2012-05-28

    The time-energy mapping of the photoionization integral cross section and laboratory-frame photoelectron angular distribution is used to study photoionization stereodynamics of a diatomic molecule. The general theoretical formalism [Y. Suzuki and T. Suzuki, Mol. Phys., 2007, 105, 1675] is simplified for application to a diatomic molecule, and a high-resolution photoelectron imaging apparatus is used to determine the transition dipole moments and phase shifts of photoelectron partial waves in near-threshold and non-dissociative photoionization of NO from the A(2)Σ(+) state. The transition dipoles and phase shifts thus determined are in reasonable agreement with those by state-to-state photoionization experiment and Schwinger variational calculations. The difference of the phase shifts from those expected from the quantum defects of Rydberg states suggests occurrence of weak hybridization of different l-waves, in addition to the well-known s-d super complex. The circular dichroism in photoelectron angular distribution is also simulated from our results.

  11. Angular scattering of 1-50 keV ions through graphene and thin carbon foils: potential applications for space plasma instrumentation.

    PubMed

    Ebert, Robert W; Allegrini, Frédéric; Fuselier, Stephen A; Nicolaou, Georgios; Bedworth, Peter; Sinton, Steve; Trattner, Karlheinz J

    2014-03-01

    We present experimental results for the angular scattering of ~1-50 keV H, He, C, O, N, Ne, and Ar ions transiting through graphene foils and compare them with scattering through nominal ~0.5 μg cm(-2) carbon foils. Thin carbon foils play a critical role in time-of-flight ion mass spectrometers and energetic neutral atom sensors in space. These instruments take advantage of the charge exchange and secondary electron emission produced as ions or neutral atoms transit these foils. This interaction also produces angular scattering and energy straggling for the incident ion or neutral atom that acts to decrease the performance of a given instrument. Our results show that the angular scattering of ions through graphene is less pronounced than through the state-of-the-art 0.5 μg cm(-2) carbon foils used in space-based particle detectors. At energies less than 50 keV, the scattering angle half width at half maximum, ψ(1/2), for ~3-5 atoms thick graphene is up to a factor of 3.5 smaller than for 0.5 μg cm(-2) (~20 atoms thick) carbon foils. Thus, graphene foils have the potential to improve the performance of space-based plasma instruments for energies below ~50 keV.

  12. Angular scattering of 1–50 keV ions through graphene and thin carbon foils: Potential applications for space plasma instrumentation

    SciTech Connect

    Ebert, Robert W.; Allegrini, Frédéric; Fuselier, Stephen A.; Nicolaou, Georgios; Bedworth, Peter; Sinton, Steve; Trattner, Karlheinz J.

    2014-03-15

    We present experimental results for the angular scattering of ∼1–50 keV H, He, C, O, N, Ne, and Ar ions transiting through graphene foils and compare them with scattering through nominal ∼0.5 μg cm{sup −2} carbon foils. Thin carbon foils play a critical role in time-of-flight ion mass spectrometers and energetic neutral atom sensors in space. These instruments take advantage of the charge exchange and secondary electron emission produced as ions or neutral atoms transit these foils. This interaction also produces angular scattering and energy straggling for the incident ion or neutral atom that acts to decrease the performance of a given instrument. Our results show that the angular scattering of ions through graphene is less pronounced than through the state-of-the-art 0.5 μg cm{sup −2} carbon foils used in space-based particle detectors. At energies less than 50 keV, the scattering angle half width at half maximum, ψ{sub 1/2}, for ∼3–5 atoms thick graphene is up to a factor of 3.5 smaller than for 0.5 μg cm{sup −2} (∼20 atoms thick) carbon foils. Thus, graphene foils have the potential to improve the performance of space-based plasma instruments for energies below ∼50 keV.

  13. Electroweak charge density distributions with parity-violating electron scattering

    NASA Astrophysics Data System (ADS)

    Liu, Jian; Ren, Zhongzhou; Xu, Chang; Xu, Renli

    2013-11-01

    Parity-violating electron scattering (PVS) is an accurate and model-independent way to investigate the weak-charge density distributions of nuclei. In this paper, we study parity-violating electron scattering with the Helm model where the effects of spin-orbit currents on nuclear weak skins are taken into account. The conditions of two PVS measurements to constrain the surface thickness σW of Helm weak-charge densities are investigated. According to the plane wave Born approximation, Apv is expressed in terms of parameters of the corresponding Helm charge and weak-charge densities. After fitting the results of Apv calculated from the phase-shift analysis method where the Coulomb distortion effects are incorporated, an empirical formula in terms of Helm model parameters for calculating Apv is obtained. If two PVS measurements with different scattering angles are carried out, the modeled weak-charge density distributions with two parameters could be extracted from this empirical formula.

  14. Atomic ionization by intense laser pulses of short duration: Photoelectron energy and angular distributions

    SciTech Connect

    Dondera, M.

    2010-11-15

    We introduce an adequate integral representation of the wave function in the asymptotic region, valid for the stage postinteraction between a one-electron atom and a laser pulse of short duration, as a superposition of divergent radial spherical waves. Starting with this representation, we derive analytic expressions for the energy and angular distributions of the photoelectrons and we show their connection with expressions used before in the literature. Using our results, we propose a method to extract the photoelectron distributions from the time dependence of the wave function at large distances. Numerical results illustrating the method are presented for the photoionization of hydrogenlike atoms from the ground state and several excited states by extreme ultraviolet pulses with a central wavelength of 13.3 nm and several intensities around the value I{sub 0}{approx_equal}3.51x10{sup 16} W/cm{sup 2}.

  15. Interference oscillations in the angular distribution of laser-ionized electrons near ionization threshold.

    PubMed

    Arbó, D G; Yoshida, S; Persson, E; Dimitriou, K I; Burgdörfer, J

    2006-04-14

    We analyze the two-dimensional momentum distribution of electrons ionized by few-cycle laser pulses in the transition regime from multiphoton absorption to tunneling by solving the time-dependent Schrödinger equation and by a classical-trajectory Monte-Carlo simulation with tunneling (CTMC-T). We find a complex two-dimensional interference pattern that resembles above threshold ionization (ATI) rings at higher energies and displays Ramsauer-Townsend-type diffraction oscillations in the angular distribution near threshold. CTMC-T calculations provide a semiclassical explanation for the dominance of selected partial waves. While the present calculation pertains to hydrogen, we find surprising qualitative agreement with recent experimental data for rare gases [A. Rudenko, J. Phys. B 37, L407 (2004)].

  16. Search for Z' --> e+ e- using dielectron mass and angular distribution.

    PubMed

    Abulencia, A; Acosta, D; Adelman, J; Affolder, T; Akimoto, T; Albrow, M G; Ambrose, D; Amerio, S; Amidei, D; Anastassov, A; Anikeev, K; Annovi, A; Antos, J; Aoki, M; Apollinari, G; Arguin, J-F; Arisawa, T; Artikov, A; Ashmanskas, W; Attal, A; Azfar, F; Azzi-Bacchetta, P; Azzurri, P; Bacchetta, N; Bachacou, H; Badgett, W; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Baroiant, S; Bartsch, V; Bauer, G; Bedeschi, F; Behari, S; Belforte, S; Bellettini, G; Bellinger, J; Belloni, A; Ben Haim, E; Benjamin, D; Beretvas, A; Beringer, J; Berry, T; Bhatti, A; Binkley, M; Bisello, D; Blair, R E; Blocker, C; Blumenfeld, B; Bocci, A; Bodek, A; Boisvert, V; Bolla, G; Bolshov, A; Bortoletto, D; Boudreau, J; Boveia, A; Brau, B; Bromberg, C; Brubaker, E; Budagov, J; Budd, H S; Budd, S; Burkett, K; Busetto, G; Bussey, P; Byrum, K L; Cabrera, S; Campanelli, M; Campbell, M; Canelli, F; Canepa, A; Carlsmith, D; Carosi, R; Carron, S; Casarsa, M; Castro, A; Catastini, P; Cauz, D; Cavalli-Sforza, M; Cerri, A; Cerrito, L; Chang, S H; Chapman, J; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Chlebana, F; Cho, I; Cho, K; Chokheli, D; Chou, J P; Chu, P H; Chuang, S H; Chung, K; Chung, W H; Chung, Y S; Ciljak, M; Ciobanu, C I; Ciocci, M A; Clark, A; Clark, D; Coca, M; Compostella, G; Convery, M E; Conway, J; Cooper, B; Copic, K; Cordelli, M; Cortiana, G; Cresciolo, F; Cruz, A; Cuenca Almenar, C; Cuevas, J; Culbertson, R; Cyr, D; DaRonco, S; D'Auria, S; D'Onofrio, M; Dagenhart, D; de Barbaro, P; De Cecco, S; Deisher, A; De Lentdecker, G; Dell'Orso, M; Delli Paoli, F; Demers, S; Demortier, L; Deng, J; Deninno, M; De Pedis, D; Derwent, P F; Dionisi, C; Dittmann, J R; DiTuro, P; Dörr, C; Donati, S; Donega, M; Dong, P; Donini, J; Dorigo, T; Dube, S; Ebina, K; Efron, J; Ehlers, J; Erbacher, R; Errede, D; Errede, S; Eusebi, R; Fang, H C; Farrington, S; Fedorko, I; Fedorko, W T; Feild, R G; Feindt, M; Fernandez, J P; Field, R; Flanagan, G; Flores-Castillo, L R; Foland, A; Forrester, S; Foster, G W; Franklin, M; Freeman, J C; Furic, I; Gallinaro, M; Galyardt, J; Garcia, J E; Garcia Sciveres, M; Garfinkel, A F; Gay, C; Gerberich, H; Gerdes, D; Giagu, S; Giannetti, P; Gibson, A; Gibson, K; Ginsburg, C; Giokaris, N; Giolo, K; Giordani, M; Giromini, P; Giunta, M; Giurgiu, G; Glagolev, V; Glenzinski, D; Gold, M; Goldschmidt, N; Goldstein, J; Gomez, G; Gomez-Ceballos, G; Goncharov, M; González, O; Gorelov, I; Goshaw, A T; Gotra, Y; Goulianos, K; Gresele, A; Griffiths, M; Grinstein, S; Grosso-Pilcher, C; Group, R C; Grundler, U; Guimaraes da Costa, J; Gunay-Unalan, Z; Haber, C; Hahn, S R; Hahn, K; Halkiadakis, E; Hamilton, A; Han, B-Y; Han, J Y; Handler, R; Happacher, F; Hara, K; Hare, M; Harper, S; Harr, R F; Harris, R M; Hatakeyama, K; Hauser, J; Hays, C; Heijboer, A; Heinemann, B; Heinrich, J; Herndon, M; Hidas, D; Hill, C S; Hirschbuehl, D; Hocker, A; Holloway, A; Hou, S; Houlden, M; Hsu, S-C; Huffman, B T; Hughes, R E; Huston, J; Incandela, J; Introzzi, G; Iori, M; Ishizawa, Y; Ivanov, A; Iyutin, B; James, E; Jang, D; Jayatilaka, B; Jeans, D; Jensen, H; Jeon, E J; Jindariani, S; Jones, M; Joo, K K; Jun, S Y; Junk, T R; Kamon, T; Kang, J; Karchin, P E; Kato, Y; Kemp, Y; Kephart, R; Kerzel, U; Khotilovich, V; Kilminster, B; Kim, D H; Kim, H S; Kim, J E; Kim, M J; Kim, S B; Kim, S H; Kim, Y K; Kirsch, L; Klimenko, S; Klute, M; Knuteson, B; Ko, B R; Kobayashi, H; Kondo, K; Kong, D J; Konigsberg, J; Korytov, A; Kotwal, A V; Kovalev, A; Kraan, A; Kraus, J; Kravchenko, I; Kreps, M; Kroll, J; Krumnack, N; Kruse, M; Krutelyov, V; Kuhlmann, S E; Kusakabe, Y; Kwang, S; Laasanen, A T; Lai, S; Lami, S; Lammel, S; Lancaster, M; Lander, R L; Lannon, K; Lath, A; Latino, G; Lazzizzera, I; LeCompte, T; Lee, J; Lee, J; Lee, Y J; Lee, S W; Lefèvre, R; Leonardo, N; Leone, S; Levy, S; Lewis, J D; Lin, C; Lin, C S; Lindgren, M; Lipeles, E; Liss, T M; Lister, A; Litvintsev, D O; Liu, T; Lockyer, N S; Loginov, A; Loreti, M; Loverre, P; Lu, R-S; Lucchesi, D; Lujan, P; Lukens, P; Lungu, G; Lyons, L; Lys, J; Lysak, R; Lytken, E; Mack, P; MacQueen, D; Madrak, R; Maeshima, K; Maki, T; Maksimovic, P; Malde, S; Manca, G; Margaroli, F; Marginean, R; Marino, C; Martin, A; Martin, V; Martínez, M; Maruyama, T; Matsunaga, H; Mattson, M E; Mazini, R; Mazzanti, P; McFarland, K S; McIntyre, P; McNulty, R; Mehta, A; Menzemer, S; Menzione, A; Merkel, P; Mesropian, C; Messina, A; von der Mey, M; Miao, T; Miladinovic, N; Miles, J; Miller, R; Miller, J S; Mills, C; Milnik, M; Miquel, R; Mitra, A; Mitselmakher, G; Miyamoto, A; Moggi, N; Mohr, B; Moore, R; Morello, M; Movilla Fernandez, P; Mülmenstädt, J; Mukherjee, A; Muller, Th; Mumford, R; Murat, P; Nachtman, J; Naganoma, J; Nahn, S; Nakano, I; Napier, A; Naumov, D; Necula, V; Neu, C; Neubauer, M S; Nielsen, J; Nigmanov, T; Nodulman, L; Norniella, O; Nurse, E; Ogawa, T; Oh, S H; Oh, Y D; Okusawa, T; Oldeman, R; Orava, R; Osterberg, K; Pagliarone, C; Palencia, E; Paoletti, R; Papadimitriou, V; Paramonov, A A; Parks, B; Pashapour, S; Patrick, J; Pauletta, G; Paulini, M; Paus, C; Pellett, D E; Penzo, A; Phillips, T J; Piacentino, G; Piedra, J; Pinera, L; Pitts, K; Plager, C; Pondrom, L; Portell, X; Poukhov, O; Pounder, N; Prakoshyn, F; Pronko, A; Proudfoot, J; Ptohos, F; Punzi, G; Pursley, J; Rademacker, J; Rahaman, A; Rakitin, A; Rappoccio, S; Ratnikov, F; Reisert, B; Rekovic, V; van Remortel, N; Renton, P; Rescigno, M; Richter, S; Rimondi, F; Ristori, L; Robertson, W J; Robson, A; Rodrigo, T; Rogers, E; Rolli, S; Roser, R; Rossi, M; Rossin, R; Rott, C; Ruiz, A; Russ, J; Rusu, V; Saarikko, H; Sabik, S; Safonov, A; Sakumoto, W K; Salamanna, G; Saltó, O; Saltzberg, D; Sanchez, C; Santi, L; Sarkar, S; Sartori, L; Sato, K; Savard, P; Savoy-Navarro, A; Scheidle, T; Schlabach, P; Schmidt, E E; Schmidt, M P; Schmitt, M; Schwarz, T; Scodellaro, L; Scott, A L; Scribano, A; Scuri, F; Sedov, A; Seidel, S; Seiya, Y; Semenov, A; Sexton-Kennedy, L; Sfiligoi, I; Shapiro, M D; Shears, T; Shepard, P F; Sherman, D; Shimojima, M; Shochet, M; Shon, Y; Shreyber, I; Sidoti, A; Sinervo, P; Sisakyan, A; Sjolin, J; Skiba, A; Slaughter, A J; Sliwa, K; Smith, J R; Snider, F D; Snihur, R; Soderberg, M; Soha, A; Somalwar, S; Sorin, V; Spalding, J; Spezziga, M; Spinella, F; Spreitzer, T; Squillacioti, P; Stanitzki, M; Staveris-Polykalas, A; St Denis, R; Stelzer, B; Stelzer-Chilton, O; Stentz, D; Strologas, J; Stuart, D; Suh, J S; Sukhanov, A; Sumorok, K; Sun, H; Suzuki, T; Taffard, A; Takashima, R; Takeuchi, Y; Takikawa, K; Tanaka, M; Tanaka, R; Tanimoto, N; Tecchio, M; Teng, P K; Terashi, K; Tether, S; Thom, J; Thompson, A S; Thomson, E; Tipton, P; Tiwari, V; Tkaczyk, S; Toback, D; Tokar, S; Tollefson, K; Tomura, T; Tonelli, D; Tönnesmann, M; Torre, S; Torretta, D; Tourneur, S; Trischuk, W; Tsuchiya, R; Tsuno, S; Turini, N; Ukegawa, F; Unverhau, T; Uozumi, S; Usynin, D; Vaiciulis, A; Vallecorsa, S; Varganov, A; Vataga, E; Velev, G; Veramendi, G; Veszpremi, V; Vidal, R; Vila, I; Vilar, R; Vine, T; Vollrath, I; Volobouev, I; Volpi, G; Würthwein, F; Wagner, P; Wagner, R G; Wagner, R L; Wagner, W; Wallny, R; Walter, T; Wan, Z; Wang, S M; Warburton, A; Waschke, S; Waters, D; Wester, W C; Whitehouse, B; Whiteson, D; Wicklund, A B; Wicklund, E; Williams, G; Williams, H H; Wilson, P; Winer, B L; Wittich, P; Wolbers, S; Wolfe, C; Wright, T; Wu, X; Wynne, S M; Yagil, A; Yamamoto, K; Yamaoka, J; Yamashita, T; Yang, C; Yang, U K; Yang, Y C; Yao, W M; Yeh, G P; Yoh, J; Yorita, K; Yoshida, T; Yu, G B; Yu, I; Yu, S S; Yun, J C; Zanello, L; Zanetti, A; Zaw, I; Zetti, F; Zhang, X; Zhou, J; Zucchelli, S

    2006-06-02

    We search for Z' bosons in dielectron events produced in pp collisions at square root of s = 1.96 TeV, using 0.45 fb(-1) of data accumulated with the Collider Detector at Fermilab II detector at the Fermilab Tevatron. To identify the Z' --> e+ e- signal, both the dielectron invariant mass distribution and the angular distribution of the electron pair are used. No evidence of a signal is found, and 95% confidence level lower limits are set on the Z' mass for several models. Limits are also placed on the mass and gauge coupling of a generic Z', as well as on the contact-interaction mass scales for different helicity structure scenarios.

  17. First Results on Angular Distributions of Thermal Dileptons in Nuclear Collisions

    SciTech Connect

    Arnaldi, R.; Colla, A.; Cortese, P.; Ferretti, A.; Oppedisano, C.; Scomparin, E.; Banicz, K.; Damjanovic, S.; Castor, J.; Devaux, A.; Fargeix, J.; Force, P.; Manso, F.; Chaurand, B.; Cicalo, C.; Falco, A. de; Floris, M.; Masoni, A.; Puddu, G.; Serci, S.

    2009-06-05

    The NA60 experiment at the CERN Super Proton Synchrotron has studied dimuon production in 158A GeV In-In collisions. The strong excess of pairs above the known sources found in the complete mass region 0.2angular distributions. Using the Collins-Soper reference frame, the structure function parameters {lambda}, {mu}, and {nu} are measured to be zero, and the projected distributions in polar and azimuth angles are found to be uniform. The absence of any polarization is consistent with the interpretation of the excess dimuons as thermal radiation from a randomized system.

  18. Search for Z' ---> e+ e- using dielectron mass and angular distribution

    SciTech Connect

    Abulencia, A.; Acosta, D.; Adelman, Jahred A.; Affolder, Anthony A.; Akimoto, T.; Albrow, M.G.; Ambrose, D.; Amerio, S.; Amidei, D.; Anastassov, A.; Anikeev, K.; /Taiwan, Inst. Phys. /Argonne /Barcelona, IFAE /Baylor U. /INFN, Bologna /Bologna U. /Brandeis U. /UC, Davis /UCLA /UC, San Diego /UC, Santa Barbara

    2006-02-01

    The authors search Z{prime} bosons in dielectron events produced in p{bar p} collisions at {radical}s = 1.96 TeV, using a 0.45 fb{sup -1} dataset accumulated with the CDF II detector at the Fermilab Tevatron. To identify the Z{prime} {yields} e{sup +}e{sup -} signal, both the dielectron invariant mass distribution and the angular distribution of the electron pair are used. No evidence of a signal is found, and 95% confidence level lower limits are set on the Z{prime} mass for several models. Limits are also placed on the mass and gauge coupling of a generic Z{prime}, as well as on the contact interaction mass scales for different helicity structure scenarios.

  19. The angular distribution of energetic electron and X-ray emissions from triggered lightning leaders

    NASA Astrophysics Data System (ADS)

    Schaal, M. M.; Dwyer, J. R.; Rassoul, H. K.; Hill, J. D.; Jordan, D. M.; Uman, M. A.

    2013-10-01

    We investigate individual X-ray bursts from lightning leaders to determine if energetic electrons at the source (and hence X-rays) are emitted isotropically or with some degree of anisotropy. This study was motivated by the work of Saleh et al. (2009), which found the falloff of X-rays in concentric radial annuli, covering all azimuthal directions in each annulus, from the lightning channel to be most consistent with an isotropic electron source. Here we perform a statistical analysis of angular and spatial distributions of X-rays measured by up to 21 NaI/PMT detectors at the International Center for Lightning Research and Testing site for 21 leader X-ray bursts from five leaders (including four dart-stepped leaders and one dart leader). Two procedures were used to complete this analysis. Procedure 1 found the first-order anisotropy, and procedure 2 tested whether or not the angular distribution was consistent with an isotropic distribution. Because higher-order anisotropies could be present in the data, a distribution that is not isotropic does not necessarily have a significant first-order anisotropy. Using these procedures, we find that at least 11 out of 21 X-ray bursts have a statistically significant first-order anisotropy, and hence those 11 are inconsistent with an isotropic emission. The remaining 10 bursts do not have significant first-order anisotropy. However, of those 10 bursts, 9 are inconsistent with isotropic emission, since they exhibit significant higher-order anisotropies. Since Saleh et al. (2009) did not consider anisotropies in the azimuthal direction, these new measurements of anisotropy do not necessarily contradict that work. Indeed, our analysis supports the finding that the X-ray emissions from lightning are inconsistent with a vertically downward beam. The level of anisotropy of the runaway electrons is important because it provides, in principle, information on the streamer zone in front of the leader and the electric field near the

  20. Comparative Performance of the Photomultiplier Tube and the Silicon Avalanche Photodiode When Used as Detectors in Angular Scattering Measurements

    NASA Astrophysics Data System (ADS)

    Kroner, D. O.; Nelson, R. M.; Boryta, M. D.; Hapke, B. W.; Manatt, K.; Smythe, W. D.

    2014-12-01

    We report the results of a comparative study of two types of photometric detectors that are commonly used for, spacecraft, ground-based telescope, and laboratory observations in support of precise angular scattering investigations of the type described in a companion paper (Nelson et al., this meeting). The performance of the state of the art Hamamatsu C12703-01 Silicon Avalanche photodiode (SAD) was compared to that of the Hamamatsu R928 Photomultiplier tube (PMT). The Hamamatsu R928 evolved from a sequence of photometric detectors with a long history of use in support of laboratory and remote sensing studies, tracing backwards to include the RCA 1P21 and the RCA 931A. Two newly acquired SADs were bench tested along with a new R928 photomultiplier tube that was thermoelectrically cooled to -10 deg C. The SAD's employed electronic thermal compensation supplied by the manufacturer. The SADs and PMT measured electromagnetic radiation from solid-state lasers of wavelength 635 nm after the radiation was reflected from diffusely-scattering surfaces of varying albedos. The SADs were housed on tripods that were co-aligned with the PMT and laser. The photometric detectors were placed 4.3 meters from a reflecting disk. The disk was rotated to reduce the effect of laser speckle. All detectors in the experiment were equipped with notch filters that transmit light only of the wavelength emitted by the laser. Three SR830 DSP Lock-in Amplifiers were connected to the detectors and various setting configurations were compared in order to optimize signal to noise. Neutral Density filters (ND 0,3 and ND 0,9) were placed in the light path to determine the linearity in the response function of the detectors. We conclude that in this application SADs and PMTs produce comparable photometric precision and fidelity. SADs offer greater convenience because thermal compensation circuitry is integrated with the detector. This work was partially supported by NASA's Cassini Science

  1. Electron back-scattered diffraction and nanoindentation analysis of nanostructured Al tubes processed by multipass tubular-channel angular pressing

    NASA Astrophysics Data System (ADS)

    Mesbah, Mohsen; Faraji, Ghader; Bushroa, A. R.

    2016-03-01

    Microstructural evolution and mechanical properties of nanostructured 1060 aluminum alloy tubes processed by tubular-channel angular pressing (TCAP) process were investigated using electron back-scattered diffraction (EBSD), transmission electron microscopy (TEM) and nanoindentation analyzes. EBSD scans revealed a homogeneous ultrafine grained microstructure after the third passes of the TCAP process. Apart from that the mean grain sizes of the TCAP processed tubes were refined to 566 nm, 500 nm and 480 nm respectively after the first, second and third passes. The results showed that after the three TCAP passes, the grain boundaries with a high angle comprised 78% of all the boundaries. This is in comparison to the first pass processed sample that includes approximately 20% HAGBs. The TEM inspection afforded an appreciation of the role of very low-angle misorientation boundaries in the process of refining microstructure. Nanoindentation results showed that hardness was the smallest form of an unprocessed sample while the largest form of the processed sample after the three passes of TCAP indicated the highest resistant of the material. In addition, the module of elasticity of the TCAP processed samples was greater from that of the unprocessed sample.

  2. The Angular Distribution of Quiet-time ~20-300 keV Superhalo Electrons in the Solar Wind

    NASA Astrophysics Data System (ADS)

    Yang, L.; Wang, L.; He, J.; Tu, C. Y.; Pei, Z.

    2014-12-01

    The angular distribution of solar wind superhalo electrons carries important information on the electron acceleration location and scattering in the interplanetary medium. Here we present a comprehensive study of the angular distribution of ~20-300 keV superhalo electrons measured at 1 AU by the WIND 3DP instrument during quiet-time periods from 1995 January through 2013 December. For quiet-time intervals, we re-bin the observed electron pitch angle distributions into the outward-traveling and inward-traveling bins, according the direction of interplanetary magnetic field (IMF). The inward-outward anisotropy of superhalo electrons at energy E is defined as A = 2(fout - fin)/(fout + fin), where fout (fin) is the average flux of outward-traveling (inward-traveling) electrons. We find that among all the ~640 quiet-time intervals, ~5% have an A > 0.1 (referred to as "outward events"), ~5% have an A < -0.1 (referred to as "inward events"), and ~90% have an |A| ≤ 0.1 (referred to as "isotropic events"). Isotropic events show no clear correlation with solar wind parameters (nSW, Vsw and Tp), IMF and solar wind turbulence spectrum. Inward and outward events also have no association with the IMF and nSW. But the occurrence ratio of outward (inward) events over all the events, α, roughly decreases (increases) with increasing VSW. Moreover, for outward (inward) events, α roughly increases with ρe/ρTp, where ρTp is the solar wind thermal proton gyroradius that is related to the separation between the turbulence inertial and dissipation ranges. These results suggest that quite-time superhalo electrons are generally isotropic due to the wave-particle interaction in the interplanetary medium; outward-traveling (inward-traveling) superhalo electrons may come from the acceleration occurring beyond (within) 1 AU, probably by CIRs or turbulence. We will also present a case study of several quiet-time electron events with the anisotropy A increasing with the electron energy E.

  3. Quasi-elastic light scattering determination of the size distribution of extruded vesicles.

    PubMed

    Kölchens, S; Ramaswami, V; Birgenheier, J; Nett, L; O'Brien, D F

    1993-04-01

    The size distribution of phospholipid vesicles prepared by the freeze thaw-extrusion method were determined by the non-perturbing technique of quasi-elastic light scattering (QELS) and compared to latex particles of known size. Multiangle QELS experiments were performed to avoid errors due to the angular dependence of the scattering function of the particles. The experimentally determined autocorrelation function was analyzed by multiple mathematical procedures, i.e. single exponential, CUMULANT, exponential sampling, non-negatively constrained least square and CONTIN, in order to select suitable models for vesicle characterization. The most consistent results were obtained with CUMULANT, non-negatively constrained least square and CONTIN. In many instances single exponential analysis gave comparable results to these procedures, which indicates the vesicles have a narrow distribution of sizes. The influence of filter pore size, extrusion pressure and lipid concentration on the size and size distribution of extruded vesicles was determined. Extrusion through 100-, 200- and 400-nm pore size filters produced a unimodal distribution of vesicles, with somewhat smaller diameters as the extrusion pressure increased. The larger the filter pore size, the more dependent the vesicle size was on applied pressure. The observed vesicle size was independent of the lipid concentration between 0.1 and 10 mg ml-1.

  4. Simulation of infrared scattering from ice aggregates by use of a size-shape distribution of circular ice cylinders.

    PubMed

    Baran, Anthony J

    2003-05-20

    The scalar optical properties (extinction coefficient, mass extinction coefficient, single-scattering albedo, and asymmetry parameter) of a distribution of randomly oriented ice aggregates are simulated generally to well within 4% accuracy by use of a size-shape distribution of randomly oriented circular ice cylinders at wavelengths in the terrestrial window region. The single-scattering properties of the ice aggregates are calculated over the whole size distribution function by the finite-difference time-domain and improved geometric optics methods. The single-scattering properties of the size-shape distribution of circular ice cylinders are calculated by the T-matrix method supplemented by scattering solutions obtained from complex-angular-momentum theory. Moreover, radiative-transfer studies demonstrate that the maximum error in brightness temperature space when the size-shape distribution of circular ice cylinders is used to represent scattering from ice aggregates is only approximately 0.4 K The methodology presented should find wide applicability in remote sensing of ice cloud and parameterization of cirrus cloud scalar optical properties in climate models.

  5. Production of black holes and their angular momentum distribution in models with split fermions

    NASA Astrophysics Data System (ADS)

    Dai, De-Chang; Starkman, Glenn D.; Stojkovic, Dejan

    2006-05-01

    In models with TeV-scale gravity it is expected that mini black holes will be produced in near-future accelerators. On the other hand, TeV-scale gravity is plagued with many problems like fast proton decay, unacceptably large n-n¯ oscillations, flavor changing neutral currents, large mixing between leptons, etc. Most of these problems can be solved if different fermions are localized at different points in the extra dimensions. We study the cross section for the production of black holes and their angular momentum distribution in these models with “split” fermions. We find that, for a fixed value of the fundamental mass scale, the total production cross section is reduced compared with models where all the fermions are localized at the same point in the extra dimensions. Fermion splitting also implies that the bulk component of the black hole angular momentum must be taken into account in studies of the black hole decay via Hawking radiation.

  6. Fuel areal density distributions derived from nuclear scattering signatures

    NASA Astrophysics Data System (ADS)

    Bionta, R. M.; Casey, D. T.; Cerjan, C. J.; Yeamans, C. B.; Gatu Johnson, M. G.

    2016-10-01

    The spatial variation of activities measured in the array of 20 Nuclear Activation Detectors mounted on the flanges around the NIF target chamber (FNADs) are correlated with asymmetries in the underlying fuel areal density of compressed ICF targets. The asymmetric areal density distributions cause variations in the neutron spectra with direction which are seen in the dsr (down scattered ratio) metric, the ratio of the number of 10-12 MeV neutrons to the number of 13-15 MeV neutrons. We show, using a simple physics based simulation of neutron scattering through an idealized non-uniform DT shell with a realistic neutron source, that for most shots an areal distribution can be found which reproduces both the FNAD activity and the dsr measurements. Furthermore, by linking the simulation to a Marquardt minimizer, we fit the areal distribution to a truncated set of spherical harmonics. Prepared by LLNL under Contract DE-AC52-07NA27344.

  7. Role of scattering distribution functions in spacecraft contamination control practices

    NASA Technical Reports Server (NTRS)

    Carosso, P. A.; Carosso, N. J. P.

    1986-01-01

    A method for spacecraft optical surface contamination monitoring based on the bidirectional reflectance distribution function (BRDF) and the bidirectional transmittance distribution function (BTDF) is described. In the experimental set up, BRDF/BTDF measurements were made at 0.6328 microns using a 35-mW He-Ne laser light source. A correlation of the second order between BRDF and cleanliness levels was observed. It is suggested that bidirectional scattering distribution functions measured on witness mirrors can give information about contamination in clean rooms or vacuum chambers, and that they can be adopted to establish contamination control criteria.

  8. Rotationally inelastic scattering of NO(A{sup 2}Σ{sup +}) + Ar: Differential cross sections and rotational angular momentum polarization

    SciTech Connect

    Sharples, Thomas R.; Luxford, Thomas F. M.; McKendrick, Kenneth G.; Costen, Matthew L.; Townsend, Dave

    2015-11-28

    We present the implementation of a new crossed-molecular beam, velocity-map ion-imaging apparatus, optimized for collisions of electronically excited molecules. We have applied this apparatus to rotational energy transfer in NO(A{sup 2}Σ{sup +}, v = 0, N = 0, j = 0.5) + Ar collisions, at an average energy of 525 cm{sup −1}. We report differential cross sections for scattering into NO(A{sup 2}Σ{sup +}, v = 0, N′ = 3, 5, 6, 7, 8, and 9), together with quantum scattering calculations of the differential cross sections and angle dependent rotational alignment. The differential cross sections show dramatic forward scattered peaks, together with oscillatory behavior at larger scattering angles, while the rotational alignment moments are also found to oscillate as a function of scattering angle. In general, the quantum scattering calculations are found to agree well with experiment, reproducing the forward scattering and oscillatory behavior at larger scattering angles. Analysis of the quantum scattering calculations as a function of total rotational angular momentum indicates that the forward scattering peak originates from the attractive minimum in the potential energy surface at the N-end of the NO. Deviations in the quantum scattering predictions from the experimental results, for scattering at angles greater than 10°, are observed to be more significant for scattering to odd final N′. We suggest that this represents inaccuracies in the potential energy surface, and in particular in its representation of the difference between the N- and O-ends of the molecule, as given by the odd-order Legendre moments of the surface.

  9. Energy and angular distributions of detached electrons in a solvable model of ion-atom collisions

    SciTech Connect

    Macek, J.H.; Ovchinnikov, S.Y. |; Solovev, E.A.

    1999-08-01

    Electron energy and angular distributions are computed for a model of atom{endash}negative-ion collisions. In this model, electron-atom interactions are represented by zero-range potentials in an approximation where two identical atoms move along straight-line classical trajectories in head-on collisions. Analytic expressions for the ionization amplitudes are interpreted in terms of Sturmian eigenvalues and eigenfunctions. At high velocity, the computed distributions exhibit direct excitation and continuum capture cusps in addition to the binary encounter ridge. At low velocities, a single feature corresponding to an electron distribution centered midway between the target and projectile emerges. For initial conditions corresponding to gerade symmetry a single broad peak appears, while for ungerade symmetry there is a node at the midpoint so that the peak splits into two parts. It is confirmed that the advanced adiabatic approximation gives an accurate description of the ungerade distribution at low and intermediate velocities. {copyright} {ital 1999} {ital The American Physical Society}

  10. Energy and angular distributions of detached electrons in a solvable model of ion-atom collisions

    SciTech Connect

    Macek, J.H.; Ovchinnikov, S.Y. Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831 ); Solovev, E.A. )

    1999-08-01

    Electron energy and angular distributions are computed for a model of atom[endash]negative-ion collisions. In this model, electron-atom interactions are represented by zero-range potentials in an approximation where two identical atoms move along straight-line classical trajectories in head-on collisions. Analytic expressions for the ionization amplitudes are interpreted in terms of Sturmian eigenvalues and eigenfunctions. At high velocity, the computed distributions exhibit direct excitation and continuum capture cusps in addition to the binary encounter ridge. At low velocities, a single feature corresponding to an electron distribution centered midway between the target and projectile emerges. For initial conditions corresponding to gerade symmetry a single broad peak appears, while for ungerade symmetry there is a node at the midpoint so that the peak splits into two parts. It is confirmed that the advanced adiabatic approximation gives an accurate description of the ungerade distribution at low and intermediate velocities. [copyright] [ital 1999] [ital The American Physical Society

  11. Angular Distributions and Dalitz plots for C^6+ ionization of He

    NASA Astrophysics Data System (ADS)

    Otranto, Sebastian; Olson, Ronald; Fiol, Juan

    2006-05-01

    Single ionization fully differential cross sections for 2 MeV/amu C^6+ + He collisions are presented and analyzed using the classical trajectory Monte Carlo (CTMC) and Continuum Distorted Wave (CDW) models. The present theoretical results are compared with recent experimental data of Fischer et al [1]. The published experimental conditions are considered in the theoretical models. The inclusion of the thermal motion of the target atom leads to an improved description of the forward electron emission [2]. Moreover, we present cross sections in the plane perpendicular to that of the collision, for which experimental angular distributions have not been yet reported. Dalitz plots for single ionization fully differential cross sections in ion-atom collisions are presented and are used to help elucidate the collision dynamics. [1] D. Fischer, R. Moshammer, M. Schulz, A. Voitkiv and J. Ullrich, J. Phys. B: At. Mol. Opt. Phys. 36, 3555 (2003). [2] R. E. Olson and J. Fiol, Phys. Rev. Lett. 95, 263203 (2005).

  12. Angular distribution of electrons in multiphoton ionisation of polarised Lithium atoms

    NASA Astrophysics Data System (ADS)

    Klimova, Yu. A.; Marmo, S. I.; Meremianin, A. V.

    2013-09-01

    The asymmetry of the angular distributions of photoelectrons in the photoionisation of polarised alkali atoms is investigated. The general formulas for the amplitude of the multiphoton ionisation of np-states are given. In these formulas the dynamical and kinematical factors are explicitly separated. Our calculations within Fues model potential approach demonstrate that, under the experimental conditions essentially similar to those employed in [M. Schuricke, Ganjun Zhu, J. Steinmann, K. Simeonidis, I. Ivanov, A. Kheifets, A.N. Grum-Grzhimailo, K. Bartschat, A. Dorn, J. Ullrich, Phys. Rev. A 83 (2011) 023413(11)], the relative magnitude of the linear magnetic dichroism in three-photon ionisation of Li can be as large as 30%.

  13. Angular distribution and altitude dependence of atmospheric neutrons from 10 to 100 MeV

    NASA Technical Reports Server (NTRS)

    Preszler, A. M.; Simmett, G. M.; White, R. S.

    1974-01-01

    The altitude dependence of atmospheric neutrons from ground level to 5 g/sq cm of residual atmosphere at neutron energies of 10 to 100 MeV is reported. Ground level measurements were taken at Cape Girardeau, Missouri, on Sept. 18, 1972. The other measurements were made during ascent and float on launch from Palestine, Texas, on Sept. 26, 1971. The intensity of both the downward- and the upward-moving neutrons is maximum at about 100 g/sq cm of residual atmosphere. Neutron angular distributions are reported from 20 to 80 deg and from 100 to 160 deg for 10- to 100-MeV neutrons. Omnidirectional fluxes at altitudes of 5, 50, 100, and 200 g/sq cm of residual atmosphere are in good agreement with recent theoretical calculations of Armstrong et al. (1973) in the three energy intervals of 10 to 30, 30 to 50, and 50 to 100 MeV.

  14. Photoelectron Angular Distribution Asymmetry Parameters for Photodetachment of Li^- and Al^-.

    NASA Astrophysics Data System (ADS)

    Liu, Chien-Nan; Starace, Anthony F.

    1997-04-01

    Calculation of photoelectron angular distribution asymmetry parameters for photodetachment precesses is a more stringent test for theory than calculation of partial or total cross sections. Since asymmetry parameters involve ratios of transition matrix elements of different channels, they are particularly sensitive to the resonance behavior of transition matrix elements. We present the asymmetry parameters for photodetachment of Li^- (2s^2 ^1S) and Al^- (3s^23p^2 ^3P) using the eigenchannel R-matrix method(U.Fano and C.M. Lee, Phys. Rev. Lett. 31), 1573 (1973)^,(C.H. Greene, in Fundamental Processes of Atomic Dynamics,) edited by J.S. Briggs, H. Kleinpoppen, and H.O. Lutz (Plenum, New York, 1988), pp.105-127.. Our results are in good agreement with the available Al^- photodetachment measurements(A.M. Covington et al.), U of Nevada-Reno, private communication..

  15. Measurements of the Angular Distributions in the Decays B→K(*)μ+μ- at CDF

    DOE PAGES

    Aaltonen, T.; Álvarez González, B.; Amerio, S.; ...

    2012-02-01

    We reconstruct the decays B → K(*) µ+µ- and measure their angular distributions in pp collisions at √s = 1.96 TeV using a data sample corresponding to an integrated luminosity of 6.8 fb-1. The transverse polarization asymmetry AT(2) and the time-reversal-odd charge-and-parity asymmetry Aim are measured for the first time, together with the K* longitudinal polarization fraction FL and the µ on forward-backward asymmetry AFB, for the decays B0→K*0µ+µ- and B0→K*+µ+µ-. Our results are among the most accurate to date and consistent with those from other experiments.

  16. Calculation of photodetachment cross sections and photoelectron angular distributions of negative ions using density functional theory.

    PubMed

    Liu, Yuan; Ning, Chuangang

    2015-10-14

    Recently, the development of photoelectron velocity map imaging makes it much easier to obtain the photoelectron angular distributions (PADs) experimentally. However, explanations of PADs are only qualitative in most cases, and very limited works have been reported on how to calculate PAD of anions. In the present work, we report a method using the density-functional-theory Kohn-Sham orbitals to calculate the photodetachment cross sections and the anisotropy parameter β. The spherical average over all random molecular orientation is calculated analytically. A program which can handle both the Gaussian type orbital and the Slater type orbital has been coded. The testing calculations on Li(-), C(-), O(-), F(-), CH(-), OH(-), NH2 (-), O2 (-), and S2 (-) show that our method is an efficient way to calculate the photodetachment cross section and anisotropy parameter β for anions, thus promising for large systems.

  17. A recursive regularization algorithm for estimating the particle size distribution from multiangle dynamic light scattering measurements

    NASA Astrophysics Data System (ADS)

    Li, Lei; Yang, Kecheng; Li, Wei; Wang, Wanyan; Guo, Wenping; Xia, Min

    2016-07-01

    Conventional regularization methods have been widely used for estimating particle size distribution (PSD) in single-angle dynamic light scattering, but they could not be used directly in multiangle dynamic light scattering (MDLS) measurements for lack of accurate angular weighting coefficients, which greatly affects the PSD determination and none of the regularization methods perform well for both unimodal and multimodal distributions. In this paper, we propose a recursive regularization method-Recursion Nonnegative Tikhonov-Phillips-Twomey (RNNT-PT) algorithm for estimating the weighting coefficients and PSD from MDLS data. This is a self-adaptive algorithm which distinguishes characteristics of PSDs and chooses the optimal inversion method from Nonnegative Tikhonov (NNT) and Nonnegative Phillips-Twomey (NNPT) regularization algorithm efficiently and automatically. In simulations, the proposed algorithm was able to estimate the PSDs more accurately than the classical regularization methods and performed stably against random noise and adaptable to both unimodal and multimodal distributions. Furthermore, we found that the six-angle analysis in the 30-130° range is an optimal angle set for both unimodal and multimodal PSDs.

  18. Product angular distributions in the ultraviolet photodissociation of N{sub 2}O

    SciTech Connect

    McBane, George C.; Schinke, Reinhard

    2012-01-28

    The angular distribution of products from the ultraviolet photodissociation of nitrous oxide yielding O({sup 1}D) and N{sub 2}(X {Sigma}{sub g}{sup +1}) was investigated using classical trajectory calculations. The calculations modeled absorption only to the 2 {sup 1}A{sup '} electronic state but used surface-hopping techniques to model nonadiabatic transitions to the ground electronic state late in the dissociation. Observed values of the anisotropy parameter {beta}, which decrease as the product N{sub 2} rotational quantum number j increases, could be well reproduced. The relatively low observed {beta} values arise principally from nonaxial recoil due to the very strong bending forces present in the excited state. In the main part of the product rotational distribution near 203 nm, an unusual dynamical effect produces the decrease in {beta} with increasing j; nonaxial recoil effects remain approximately constant while higher j product molecules arise from parent molecules that had their transition dipole moments aligned more closely along the molecular axis. In both low and high j tails of the rotational distribution, the variations in {beta} with j are caused by changes in the extent of nonaxial recoil. In the high-j tail, additional torque present on the ground state potential energy surface following nonadiabatic transitions causes both the additional rotational excitation and the lower {beta} values.

  19. Scattering of a laser beam on a wet blood smear and measurement of red cell size distribution

    NASA Astrophysics Data System (ADS)

    Yurchuk, Yu S.; Ustinov, V. D.; Nikitin, S. Yu; Priezzhev, A. V.

    2016-06-01

    We report an automated laser system that allows the red cell size distribution to be measured. Experiments are performed on laser light scattering by a suspension of oriented red blood cells (a wet blood smear). Based on an analysis of the angular distribution of light intensity in the diffraction pattern, we have restored the red cell size distribution. The average diameter of a red blood cell is determined with an error of less than 1%, and the spread of red blood cells in size - with an error of about 20%. We discuss the problems of photometry and processing of diffraction patterns, preparing blood samples and data processing algorithms, including methods for solving the inverse scattering problem.

  20. Spectral and angular dependence of mid-infrared diffuse scattering from explosives residues for standoff detection using external cavity quantum cascade lasers

    NASA Astrophysics Data System (ADS)

    Suter, Jonathan D.; Bernacki, Bruce; Phillips, Mark C.

    2012-09-01

    We present a study of the spectral and angular dependence of scattered mid-infrared light from surfaces coated with explosives residues (TNT, RDX, and tetryl) detected at a 2 m standoff distance. An external cavity quantum cascade laser provided tunable illumination between 7 and 8 μm. Important differences were identified in the spectral features between specular reflection and diffuse scattering which will impact most practical testing scenarios and complicate material identification. We discuss some of the factors influencing the dependence of observed spectra on the experimental geometry.

  1. Two dimensional expansion effects on angular distribution of 13.5 nm in-band extreme ultraviolet emission from laser-produced Sn plasma

    SciTech Connect

    Sequoia, K. L.; Tao, Y.; Yuspeh, S.; Burdt, R.; Tillack, M. S.

    2008-06-02

    The angular distribution of extreme ultraviolet emission at 13.5 nm within 2% bandwidth was characterized for laser irradiated, planar, Sn targets at prototypic conditions for a lithography system. We have found that two dimensional plasma expansion plays a key role in the distribution of in-band 13.5 nm emission under these conditions. The angular distribution was found to have two peaks at 45 deg. and 15 deg. This complex angular distribution arises from the shape of both the emitting plasma and the surrounding absorbing plasma. This research reveals that the detailed angular distribution can be important to the deduction of conversion efficiency.

  2. Analysis of the atmospheric aerosol size distribution information retrievable from near-limb angular radiance measurements taken on Mauna Loa, Hawaii

    SciTech Connect

    Grant, K.E.

    1981-12-01

    Angular radiance measurements of the near-limb solar aureole were analyzed for information regarding the light-scattering aerosol particles in the atmospheric column above Mauna Loa, Hawaii. The Mauna Loa Observatory, located at 19/sup 0/ 33' N latitude, 155/sup 0/ 35' W longitude, and 3460 metres elevation, is in unpolluted air above the easterly trade wind inversion and has been designated as a site for the Geophysical Monitoring for Climatic Change (GMCC) program. Circumsolar radiance and polarization measurements have been collected on Mauna Loa since 1963 by the High Altitude Observatory (HAO), National Center for Atmospheric Research (NCAR) as part of a program for the daily observation of the solar corona. Strip charts containing radiance measurements made from January 1976 through June 1978 were made available for this study. By the use of Mie scattering theory, generalized to treat the sun as a finite diameter light source with limb-darkening, a theoretical scattering matrix was calculated for observation angles between 17' and 300' measured from the center of the solar disk, and aerosol size parameters (2..pi..r/lambda) between 10 and 300. An information content criterion is presented, based on the expected relative norm of the measurement errors and on the eigenvalues of the radiance covariance matrix of the scattering matrix. The observed aureole radiance gradients and two test gradients were inverted to obtain aerosol size distributions using a constrained linear inversion algorithm.

  3. Asymmetric electron angular distributions in resonant dissociative photoionization of H{sub 2} with ultrashort xuv pulses

    SciTech Connect

    Perez-Torres, J. F.; Morales, F.; Martin, F.; Sanz-Vicario, J. L.

    2009-07-15

    Photoelectron angular distributions from fixed-in-space H{sub 2} molecules exposed to ultrashort xuv laser pulses have been evaluated. The theoretical method is based on the solution of the time-dependent Schroedinger equation in a basis of stationary states that include all electronic and vibrational degrees of freedom. Asymmetric angular distributions are observed as a consequence of the delayed ionization from the H{sub 2} doubly excited states, which induces interferences between gerade and ungerade ionization channels. The analysis of this asymmetry as a function of pulse duration can provide an estimate of the corresponding autoionization widths.

  4. Two-dimensional ion-imaging of fragment angular distributions after photolysis of state-selected and oriented triatomic molecules

    SciTech Connect

    Teule, J. M.; Hilgeman, M. H.; Janssen, M. H. M.; Chandler, D. W.; Taatjes, C. A.; Stolte, S.

    1997-01-15

    Photodissociation experiments of state-selected and oriented triatomics are presented. Selective ionization using REMPI in combination with two-dimensional ion-imaging allows us to measure both the internal energy and angular distribution of the fragments. The dissociation of N{sub 2}O is studied using one laser around 204 nm for both the dissociation of the molecule and the ionization of the fragments. The angular distributions of O({sup 1}D) and N{sub 2}(J) are presented and implications of these results on the dissociation dynamics are discussed.

  5. Two-dimensional ion-imaging of fragment angular distributions after photolysis of state-selected and oriented triatomic molecules

    SciTech Connect

    Teule, J.M.; Hilgeman, M.H.; Janssen, M.H.; Chandler, D.W.; Taatjes, C.A.; Stolte, S.

    1997-01-01

    Photodissociation experiments of state-selected and oriented triatomics are presented. Selective ionization using REMPI in combination with two-dimensional ion-imaging allows us to measure both the internal energy and angular distribution of the fragments. The dissociation of N{sub 2}O is studied using one laser around 204 nm for both the dissociation of the molecule and the ionization of the fragments. The angular distributions of O({sup 1}D) and N{sub 2}(J) are presented and implications of these results on the dissociation dynamics are discussed. {copyright} {ital 1997 American Institute of Physics.}

  6. Monte Carlo study of the effects of system geometry and antiscatter grids on cone-beam CT scatter distributions

    PubMed Central

    Sisniega, A.; Zbijewski, W.; Badal, A.; Kyprianou, I. S.; Stayman, J. W.; Vaquero, J. J.; Siewerdsen, J. H.

    2013-01-01

    Purpose: The proliferation of cone-beam CT (CBCT) has created interest in performance optimization, with x-ray scatter identified among the main limitations to image quality. CBCT often contends with elevated scatter, but the wide variety of imaging geometry in different CBCT configurations suggests that not all configurations are affected to the same extent. Graphics processing unit (GPU) accelerated Monte Carlo (MC) simulations are employed over a range of imaging geometries to elucidate the factors governing scatter characteristics, efficacy of antiscatter grids, guide system design, and augment development of scatter correction. Methods: A MC x-ray simulator implemented on GPU was accelerated by inclusion of variance reduction techniques (interaction splitting, forced scattering, and forced detection) and extended to include x-ray spectra and analytical models of antiscatter grids and flat-panel detectors. The simulator was applied to small animal (SA), musculoskeletal (MSK) extremity, otolaryngology (Head), breast, interventional C-arm, and on-board (kilovoltage) linear accelerator (Linac) imaging, with an axis-to-detector distance (ADD) of 5, 12, 22, 32, 60, and 50 cm, respectively. Each configuration was modeled with and without an antiscatter grid and with (i) an elliptical cylinder varying 70–280 mm in major axis; and (ii) digital murine and anthropomorphic models. The effects of scatter were evaluated in terms of the angular distribution of scatter incident upon the detector, scatter-to-primary ratio (SPR), artifact magnitude, contrast, contrast-to-noise ratio (CNR), and visual assessment. Results: Variance reduction yielded improvements in MC simulation efficiency ranging from ∼17-fold (for SA CBCT) to ∼35-fold (for Head and C-arm), with the most significant acceleration due to interaction splitting (∼6 to ∼10-fold increase in efficiency). The benefit of a more extended geometry was evident by virtue of a larger air gap—e.g., for a 16 cm

  7. Light scattering by hexagonal ice crystals with distributed inclusions

    NASA Astrophysics Data System (ADS)

    Panetta, R. Lee; Zhang, Jia-Ning; Bi, Lei; Yang, Ping; Tang, Guanlin

    2016-07-01

    Inclusions of air bubbles or soot particles have significant effects on the single-scattering properties of ice crystals, effects that in turn have significant impacts on the radiation budget of an atmosphere containing the crystals. This study investigates some of the single-scattering effects in the case of hexagonal ice crystals, including effects on the backscattering depolarization ratio, a quantity of practical importance in the interpretation of lidar observations. One distinguishing feature of the study is an investigation of scattering properties at a visible wavelength for a crystal with size parameter (x) above 100, a size regime where one expects some agreement between exact methods and geometrical optics methods. This expectation is generally borne out in a test comparison of how the sensitivity of scattering properties to the distribution of a given volume fraction of included air is represented using (i) an approximate Monte Carlo Ray Tracing (MCRT) method and (ii) a numerically exact pseudo-spectral time-domain (PSTD) method. Another distinguishing feature of the study is a close examination, using the numerically exact Invariant-Imbedding T-Matrix (II-TM) method, of how some optical properties of importance to satellite remote sensing vary as the volume fraction of inclusions and size of crystal are varied. Although such an investigation of properties in the x>100 regime faces serious computational burdens that force a large number of idealizations and simplifications in the study, the results nevertheless provide an intriguing glimpse of what is evidently a quite complex sensitivity of optical scattering properties to inclusions of air or soot as volume fraction and size parameter are varied.

  8. Angular distribution of {alpha} particles from oriented {sup 253,254}Es and {sup 255}Fm nuclei

    SciTech Connect

    Severijns, N.; Golovko, V.V.; Kraev, I.S.; Phalet, T.; Belyaev, A.A.; Lukhanin, A.A.; Noga, V.I.; Erzinkyan, A.L.; Parfenova, V.P.; Eversheim, P.-D.; Herzog, P.; Tramm, C.; Filimonov, V.T.; Toporov, Yu.G.; Zotov, E.; Gurevich, G.M.; Rusakov, A.V.; Vyachin, V.N.; Zakoucky, D.

    2005-04-01

    The anisotropy in the angular distribution of {alpha} particles from oriented {sup 253,254}Es and {sup 255}Fm nuclei, which are among the strongest deformed {alpha} emitters, was measured. Large {alpha} anisotropies have been observed for all three nuclei. The results are compared with calculations based on {alpha}-particle tunneling through a deformed Coulomb barrier.

  9. Modeling the matrix of articular cartilage using a continuous fiber angular distribution predicts many observed phenomena.

    PubMed

    Ateshian, Gerard A; Rajan, Vikram; Chahine, Nadeen O; Canal, Clare E; Hung, Clark T

    2009-06-01

    Cartilage is a hydrated soft tissue whose solid matrix consists of negatively charged proteoglycans enmeshed within a fibrillar collagen network. Though many aspects of cartilage mechanics are well understood today, most notably in the context of porous media mechanics, there remain a number of responses observed experimentally whose prediction from theory has been challenging. In this study the solid matrix of cartilage is modeled with a continuous fiber angular distribution, where fibers can only sustain tension, swelled by the osmotic pressure of a proteoglycan ground matrix. It is shown that this representation of cartilage can predict a number of observed phenomena in relation to the tissue's equilibrium response to mechanical and osmotic loading, when flow-dependent and flow-independent viscoelastic effects have subsided. In particular, this model can predict the transition of Poisson's ratio from very low values in compression (approximately 0.02) to very high values in tension (approximately 2.0). Most of these phenomena cannot be explained when using only three orthogonal fiber bundles to describe the tissue matrix, a common modeling assumption used to date. The main picture emerging from this analysis is that the anisotropy of the fibrillar matrix of articular cartilage is intimately dependent on the mechanism of tensed fiber recruitment, in the manner suggested by our recent theoretical study (Ateshian, 2007, ASME J. Biomech. Eng., 129(2), pp. 240-249).

  10. Calculation of photodetachment cross sections and photoelectron angular distributions of negative ions using density functional theory

    SciTech Connect

    Liu, Yuan; Ning, Chuangang

    2015-10-14

    Recently, the development of photoelectron velocity map imaging makes it much easier to obtain the photoelectron angular distributions (PADs) experimentally. However, explanations of PADs are only qualitative in most cases, and very limited works have been reported on how to calculate PAD of anions. In the present work, we report a method using the density-functional-theory Kohn-Sham orbitals to calculate the photodetachment cross sections and the anisotropy parameter β. The spherical average over all random molecular orientation is calculated analytically. A program which can handle both the Gaussian type orbital and the Slater type orbital has been coded. The testing calculations on Li{sup −}, C{sup −}, O{sup −}, F{sup −}, CH{sup −}, OH{sup −}, NH{sub 2}{sup −}, O{sub 2}{sup −}, and S{sub 2}{sup −} show that our method is an efficient way to calculate the photodetachment cross section and anisotropy parameter β for anions, thus promising for large systems.

  11. Energy and angular distributions of electron emission from diatomic molecules by bare ion impact

    NASA Astrophysics Data System (ADS)

    Mondal, A.; Mandal, C. R.; Purkait, M.

    2015-06-01

    The three-Coulomb wave model has been used extensively to study the energy and angular distributions of double-differential cross sections (DDCS) of electron emissions from hydrogen and nitrogen molecules by bare ion impact at intermediate and high energies. In the present model, we have expressed the molecular triple differential cross section in terms of the corresponding atomic triple differential cross section multiplied by the occupation number and the average Rayleigh interference factor, which accounts for the two-center interference effect. Here we have used an active electron approximation of the molecule as a whole in the initial channel. To account for the effect of passive electrons, we have constructed a model potential that satisfies the initial conditions and the corresponding wavefunction has been calculated from the model Hamiltonian of the active electron in the target. In the final channel, we have used a hydrogenic model with an effective nuclear charge that is calculated from its binding energy. In this model, the correlated motion of the particles in the exit channel of the reaction is considered by an adequate product of three-Coulomb functions. The emitted electron, the incident projectile ion and the residual ion are considered to be in same plane. The obtained results are compared with other recent theoretical and experimental findings. There is an overall agreement of the calculations with the experimental data for electron emission cross sections.

  12. Isomer production ratios and the angular momentum distribution of fission fragments

    NASA Astrophysics Data System (ADS)

    Stetcu, I.; Talou, P.; Kawano, T.; Jandel, M.

    2013-10-01

    Latest generation fission experiments provide an excellent testing ground for theoretical models. In this contribution we compare the measurements for 235U(nth,f), obtained with the Detector for Advanced Neutron Capture Experiments (DANCE) calorimeter at Los Alamos Neutron Science Center (LANSCE), with our full-scale simulation of the primary fragment de-excitation, using the recently developed cgmf code, based on a Monte Carlo implementation of the Hauser-Feshbach theoretical model. We compute the isomer ratios as a function of the initial angular momentum of the fission fragments, for which no direct information exists. Comparison with the available experimental data allows us to determine the initial spin distribution. We also study the dependence of the isomer ratio on the knowledge of the low-lying discrete spectrum input for nuclear fission reactions, finding a high degree of sensitivity. Finally, in the same Hauser-Feshbach approach, we calculate the isomer production ratio for thermal neutron capture on stable isotopes, where the initial conditions (spin, excitation energy, etc.) are well understood. We find that with the current parameters involved in Hauser-Feshbach calculations, we obtain up to a factor of 2 deviation from the measured isomer ratios.

  13. Random walk with nonuniform angular distribution biased by an external periodic pulse

    NASA Astrophysics Data System (ADS)

    Acharyya, Aranyak

    2016-11-01

    We studied the motion of a random walker in two dimensions with nonuniform angular distribution biased by an external periodic pulse. Here, we analytically calculated the mean square displacement (end-to-end distance of a walk after n time steps), without bias and with bias. We determined the average x-component of the final displacement of the walker. Interestingly, we noted that for a particular periodicity of the bias, this average x-component of the final displacement becomes approximately zero. The average y-component of the final displacement is found to be zero for any perodicity of the bias, and its reason can be attributed to the nature of the probability density function of the angle (subtended by the displacement vector with the x-axis). These analytical results are also supported by computer simulations. The present study may be thought of as a model for arresting the bacterial motion (along a preferred direction) by an external periodic bias. This article will be useful for undergraduate students of physics, statistics and biology as an example of an interdisciplinary approach to understand a way to control bacterial motion.

  14. Measurements of the angular distributions in the decays B→K(*)μ(+)μ(-) at CDF.

    PubMed

    Aaltonen, T; Alvarez González, B; Amerio, S; Amidei, D; Anastassov, A; Annovi, A; Antos, J; Apollinari, G; Appel, J A; Apresyan, A; Arisawa, T; Artikov, A; Asaadi, J; Ashmanskas, W; Auerbach, B; Aurisano, A; Azfar, F; Badgett, W; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Barria, P; Bartos, P; Bauce, M; Bauer, G; Bedeschi, F; Beecher, D; Behari, S; Bellettini, G; Bellinger, J; Benjamin, D; Beretvas, A; Bhatti, A; Binkley, M; Bisello, D; Bizjak, I; Bland, K R; Blocker, C; Blumenfeld, B; Bocci, A; Bodek, A; Bortoletto, D; Boudreau, J; Boveia, A; Brau, B; Brigliadori, L; Brisuda, A; Bromberg, C; Brucken, E; Bucciantonio, M; Budagov, J; Budd, H S; Budd, S; Burkett, K; Busetto, G; Bussey, P; Buzatu, A; Cabrera, S; Calancha, C; Camarda, S; Campanelli, M; Campbell, M; Canelli, F; Canepa, A; Carls, B; Carlsmith, D; Carosi, R; Carrillo, S; Carron, S; Casal, B; Casarsa, M; Castro, A; Catastini, P; Cauz, D; Cavaliere, V; Cavalli-Sforza, M; Cerri, A; Cerrito, L; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Chlebana, F; Cho, K; Chokheli, D; Chou, J P; Chung, W H; Chung, Y S; Ciobanu, C I; Ciocci, M A; Clark, A; Clark, D; Compostella, G; Convery, M E; Conway, J; Corbo, M; Cordelli, M; Cox, C A; Cox, D J; Crescioli, F; Cuenca Almenar, C; Cuevas, J; Culbertson, R; Dagenhart, D; d'Ascenzo, N; Datta, M; de Barbaro, P; De Cecco, S; De Lorenzo, G; Dell'Orso, M; Deluca, C; Demortier, L; Deng, J; Deninno, M; Devoto, F; d'Errico, M; Di Canto, A; Di Ruzza, B; Dittmann, J R; D'Onofrio, M; Donati, S; Dong, P; Dorigo, T; Ebina, K; Elagin, A; Eppig, A; Erbacher, R; Errede, D; Errede, S; Ershaidat, N; Eusebi, R; Fang, H C; Farrington, S; Feindt, M; Fernandez, J P; Ferrazza, C; Field, R; Flanagan, G; Forrest, R; Frank, M J; Franklin, M; Freeman, J C; Furic, I; Gallinaro, M; Galyardt, J; Garcia, J E; Garfinkel, A F; Garosi, P; Gerberich, H; Gerchtein, E; Giagu, S; Giakoumopoulou, V; Giannetti, P; Gibson, K; Ginsburg, C M; Giokaris, N; Giromini, P; Giunta, M; Giurgiu, G; Glagolev, V; Glenzinski, D; Gold, M; Goldin, D; Goldschmidt, N; Golossanov, A; Gomez, G; Gomez-Ceballos, G; Goncharov, M; González, O; Gorelov, I; Goshaw, A T; Goulianos, K; Gresele, A; Grinstein, S; Grosso-Pilcher, C; Group, R C; Guimaraes da Costa, J; Gunay-Unalan, Z; Haber, C; Hahn, S R; Halkiadakis, E; Hamaguchi, A; Han, J Y; Happacher, F; Hara, K; Hare, D; Hare, M; Harr, R F; Hatakeyama, K; Hays, C; Heck, M; Heinrich, J; Herndon, M; Hewamanage, S; Hidas, D; Hocker, A; Hopkins, W; Horn, D; Hou, S; Hughes, R E; Hurwitz, M; Husemann, U; Hussain, N; Hussein, M; Huston, J; Introzzi, G; Iori, M; Ivanov, A; James, E; Jang, D; Jayatilaka, B; Jeon, E J; Jha, M K; Jindariani, S; Johnson, W; Jones, M; Joo, K K; Jun, S Y; Junk, T R; Kamon, T; Karchin, P E; Kato, Y; Ketchum, W; Keung, J; Khotilovich, V; Kilminster, B; Kim, D H; Kim, H S; Kim, H W; Kim, J E; Kim, M J; Kim, S B; Kim, S H; Kim, Y K; Kimura, N; Klimenko, S; Kondo, K; Kong, D J; Konigsberg, J; Korytov, A; Kotwal, A V; Kreps, M; Kroll, J; Krop, D; Krumnack, N; Kruse, M; Krutelyov, V; Kuhr, T; Kurata, M; Kwang, S; Laasanen, A T; Lami, S; Lammel, S; Lancaster, M; Lander, R L; Lannon, K; Lath, A; Latino, G; Lazzizzera, I; LeCompte, T; Lee, E; Lee, H S; Lee, J S; Lee, S W; Leo, S; Leone, S; Lewis, J D; Lin, C-J; Linacre, J; Lindgren, M; Lipeles, E; Lister, A; Litvintsev, D O; Liu, C; Liu, Q; Liu, T; Lockwitz, S; Lockyer, N S; Loginov, A; Lucchesi, D; Lueck, J; Lujan, P; Lukens, P; Lungu, G; Lys, J; Lysak, R; Madrak, R; Maeshima, K; Makhoul, K; Maksimovic, P; Malik, S; Manca, G; Manousakis-Katsikakis, A; Margaroli, F; Marino, C; Martínez, M; Martínez-Ballarín, R; Mastrandrea, P; Mathis, M; Mattson, M E; Mazzanti, P; McFarland, K S; McIntyre, P; McNulty, R; Mehta, A; Mehtala, P; Menzione, A; Mesropian, C; Miao, T; Mietlicki, D; Mitra, A; Miyake, H; Moed, S; Moggi, N; Mondragon, M N; Moon, C S; Moore, R; Morello, M J; Morlock, J; Movilla Fernandez, P; Mukherjee, A; Muller, Th; Murat, P; Mussini, M; Nachtman, J; Nagai, Y; Naganoma, J; Nakano, I; Napier, A; Nett, J; Neu, C; Neubauer, M S; Nielsen, J; Nodulman, L; Norniella, O; Nurse, E; Oakes, L; Oh, S H; Oh, Y D; Oksuzian, I; Okusawa, T; Orava, R; Ortolan, L; Pagan Griso, S; Pagliarone, C; Palencia, E; Papadimitriou, V; Paramonov, A A; Patrick, J; Pauletta, G; Paulini, M; Paus, C; Pellett, D E; Penzo, A; Phillips, T J; Piacentino, G; Pianori, E; Pilot, J; Pitts, K; Plager, C; Pondrom, L; Potamianos, K; Poukhov, O; Prokoshin, F; Pronko, A; Ptohos, F; Pueschel, E; Punzi, G; Pursley, J; Rahaman, A; Ramakrishnan, V; Ranjan, N; Redondo, I; Renton, P; Rescigno, M; Rimondi, F; Ristori, L; Robson, A; Rodrigo, T; Rodriguez, T; Rogers, E; Rolli, S; Roser, R; Rossi, M; Ruffini, F; Ruiz, A; Russ, J; Rusu, V; Safonov, A; Sakumoto, W K; Santi, L; Sartori, L; Sato, K; Saveliev, V; Savoy-Navarro, A; Schlabach, P; Schmidt, A; Schmidt, E E; Schmidt, M P; Schmitt, M; Schwarz, T; Scodellaro, L; Scribano, A; Scuri, F; Sedov, A; Seidel, S; Seiya, Y; Semenov, A; Sforza, F; Sfyrla, A; Shalhout, S Z; Shears, T; Shepard, P F; Shimojima, M; Shiraishi, S; Shochet, M; Shreyber, I; Simonenko, A; Sinervo, P; Sissakian, A; Sliwa, K; Smith, J R; Snider, F D; Soha, A; Somalwar, S; Sorin, V; Squillacioti, P; Stanitzki, M; St Denis, R; Stelzer, B; Stelzer-Chilton, O; Stentz, D; Strologas, J; Strycker, G L; Sudo, Y; Sukhanov, A; Suslov, I; Takemasa, K; Takeuchi, Y; Tang, J; Tecchio, M; Teng, P K; Thom, J; Thome, J; Thompson, G A; Thomson, E; Ttito-Guzmán, P; Tkaczyk, S; Toback, D; Tokar, S; Tollefson, K; Tomura, T; Tonelli, D; Torre, S; Torretta, D; Totaro, P; Trovato, M; Tu, Y; Turini, N; Ukegawa, F; Uozumi, S; Varganov, A; Vataga, E; Vázquez, F; Velev, G; Vellidis, C; Vidal, M; Vila, I; Vilar, R; Vogel, M; Volpi, G; Wagner, P; Wagner, R L; Wakisaka, T; Wallny, R; Wang, S M; Warburton, A; Waters, D; Weinberger, M; Wenzel, H; Wester, W C; Whitehouse, B; Whiteson, D; Wicklund, A B; Wicklund, E; Wilbur, S; Wick, F; Williams, H H; Wilson, J S; Wilson, P; Winer, B L; Wittich, P; Wolbers, S; Wolfe, H; Wright, T; Wu, X; Wu, Z; Yamamoto, K; Yamaoka, J; Yang, T; Yang, U K; Yang, Y C; Yao, W-M; Yeh, G P; Yi, K; Yoh, J; Yorita, K; Yoshida, T; Yu, G B; Yu, I; Yu, S S; Yun, J C; Zanetti, A; Zeng, Y; Zucchelli, S

    2012-02-24

    We report an indirect search for nonstandard model physics using the flavor-changing neutral current decays B→K(*)μ(+)μ(-). We reconstruct the decays and measure their angular distributions, as a function of q(2)=M(μμ)(2)c(2), where M(μμ) is the dimuon mass, in pp¯ collisions at √s=1.96 TeV using a data sample corresponding to an integrated luminosity of 6.8 fb(-1). The transverse polarization asymmetry A(T)(2) and the time-reversal-odd charge-and-parity asymmetry A(im) are measured for the first time, together with the K* longitudinal polarization fraction F(L) and the muon forward-backward asymmetry A(FB) for the decays B(0)→K(*0)μ(+)μ(-) and B(+)→K(*+)μ(+)μ(-). The B→K*μ(+)μ(-) forward-backward asymmetry in the most sensitive kinematic regime, 1≤q(2)<6 GeV(2)/c(2), is measured to be A(FB)=0.29(-0.23)(+0.20)(stat)±0.07(syst), the most precise result to date. No deviations from the standard model predictions are observed.

  15. Modeling the Matrix of Articular Cartilage Using a Continuous Fiber Angular Distribution Predicts Many Observed Phenomena

    PubMed Central

    Ateshian, Gerard A.; Rajan, Vikram; Chahine, Nadeen O.; Canal, Clare E.; Hung, Clark T.

    2010-01-01

    Background Cartilage is a hydrated soft tissue whose solid matrix consists of negatively charged proteoglycans enmeshed within a fibrillar collagen network. Though many aspects of cartilage mechanics are well understood today, most notably in the context of porous media mechanics, there remain a number of responses observed experimentally whose prediction from theory has been challenging. Method of approach In this study the solid matrix of cartilage is modeled with a continuous fiber angular distribution, where fibers can only sustain tension, swelled by the osmotic pressure of a proteoglycan ground matrix. Results It is shown that this representation of cartilage can predict a number of observed phenomena in relation to the tissue’s equilibrium response to mechanical and osmotic loading, when flow-dependent and flow-independent viscoelastic effects have subsided. In particular, this model can predict the transition of Poisson’s ratio from very low values in compression (~0.02) to very high values in tension (~2.0). Most of these phenomena cannot be explained when using only three orthogonal fiber bundles to describe the tissue matrix, a common modeling assumption used to date. Conclusions The main picture emerging from this analysis is that the anisotropy of the fibrillar matrix of articular cartilage is intimately dependent on the mechanism of tensed fiber recruitment, in the manner suggested by our recent theoretical study (G. A. Ateshian. J Biomech Eng, 129(2):240-9, 2007). PMID:19449957

  16. Analysis of THz generation through the asymmetry of photoelectron angular distributions

    NASA Astrophysics Data System (ADS)

    Zhou, Zhaoyan; Wang, Xu; Lin, C. D.

    2017-03-01

    We analyze the mechanism of THz generation in a gas medium with intense two-color infrared lasers pulses. The dependence of the amplitude of THz emission on the relative phase between the fundamental color (800 nm) and its second harmonic (400 nm) is shown to be identical to the residual current as well as to the asymmetry of the above-threshold-ionization (ATI) photoelectrons along the left versus the right side of the linear polarization axis of the laser, thus confirming the validity of the semiclassical photocurrent model for the THz emission. We further analyze the even vs odd angular momentum distributions of the ATI electrons. The degree of overlap between the even-parity dominant electrons and the odd-parity dominant electrons within each ATI peak determines the strength of the THz emission, thus favoring the model that THz is generated through free-free transitions in the laser field. A model is also provided to obtain the same phase dependence as the four-wave mixing model.

  17. Role of screening and angular distributions in resonant soft-x-ray emission of CO

    SciTech Connect

    Skytt, P.; Glans, P.; Gunnelin, K.

    1997-04-01

    In the present work the authors focus on two particular properties of resonant X-ray emission, namely core hole screening of the excited electron, and anisotropy caused by the polarization of the exciting synchrotron radiation. The screening of the core hole by the excited electron causes energy shifts and intensity variations in resonant spectra compared to the non-resonant case. The linear polarization of the synchrotron radiation and the dipole nature of the absorption process create a preferential alignment selection of the randomly oriented molecules in the case of resonant excitation, producing an anisotropy in the angular distribution of the emitted X-rays. The authors have chosen CO for this study because this molecule has previously served as a showcase for non-resonant X-ray emission, mapping the valence electronic structure differently according to the local selection rules. With the present work they take interest in how this characteristic feature of the spectroscopy is represented in the resonant case.

  18. Dissociative electron attachment to halogen molecules: Angular distributions and nonlocal effects

    NASA Astrophysics Data System (ADS)

    Fabrikant, I. I.

    2016-11-01

    We study dissociative electron attachment (DEA) to the ClF and F2 molecules. We formulate a method for calculation of partial resonance widths and calculate the angular distributions of the products in the ClF case using the local and nonlocal versions of the complex potential theory of DEA. They show the dominance of the p wave except in a narrow energy region close to zero energy. Comparison of the local and nonlocal DEA cross sections show that the former are smaller than the latter by a factor of 2 in the energy region important for calculation of thermal rate coefficients. This result is confirmed by comparison of the local and nonlocal calculations for F2. Only at low energies below 30 meV the local cross sections exceed nonlocal due to the 1 /E divergence of the local results. On the other hand, the thermal rate coefficients generated from the local cross sections agree better with experiment than those calculated from the nonlocal cross sections. The most likely reason for this disagreement is the overestimated resonance width in the region of internuclear distances close to the point of crossing between the neutral and anion potential-energy curves.

  19. Efficient computation of the angularly resolved chord length distributions and lineal path functions in large microstructure datasets

    NASA Astrophysics Data System (ADS)

    Turner, David M.; Niezgoda, Stephen R.; Kalidindi, Surya R.

    2016-10-01

    Chord length distributions (CLDs) and lineal path functions (LPFs) have been successfully utilized in prior literature as measures of the size and shape distributions of the important microscale constituents in the material system. Typically, these functions are parameterized only by line lengths, and thus calculated and derived independent of the angular orientation of the chord or line segment. We describe in this paper computationally efficient methods for estimating chord length distributions and lineal path functions for 2D (two dimensional) and 3D microstructure images defined on any number of arbitrary chord orientations. These so called fully angularly resolved distributions can be computed for over 1000 orientations on large microstructure images (5003 voxels) in minutes on modest hardware. We present these methods as new tools for characterizing microstructures in a statistically meaningful way.

  20. The Center-of-mass angular distribution of direct photons at $S^{(1/2)}$ = 1.8-TeV observed with the D0 detector

    SciTech Connect

    Rubinov, Paul Michael

    1995-12-01

    The study of center-of-mass angular distribution of direct photons produced in p$\\bar{p}$ collisions at √s = 1.8TeV with the D0 detector is described. The photons are detected and identified using a liquid argon calorimeter, with charged particle rejection provided by tracking chambers. The photons are restricted to the central region (n ≤ 0.75), but center-of-mass system for the hard scattering is reconstructed using the information from reconstructed jets. A method for avoiding possible bias due to edges of the calorimeter is presented. The background, due mainly to rare fragmentations of a jet into a leading neutral meson, are subtracted statistically using the expected variation in the longitudinal profile of the electromagnetic shower. The angular distribution in the range of η* from 0 to 1.5 (cos θ* from 0 to 0.9) is compared to next-to-leading order QCD predictions, and found to be in good agreement.

  1. Generalized parton distributions from deep virtual compton scattering at CLAS

    DOE PAGES

    Guidal, M.

    2010-04-24

    Here, we have analyzed the beam spin asymmetry and the longitudinally polarized target spin asymmetry of the Deep Virtual Compton Scattering process, recently measured by the Jefferson Lab CLAS collaboration. Our aim is to extract information about the Generalized Parton Distributions of the proton. By fitting these data, in a largely model-independent procedure, we are able to extract numerical values for the two Compton Form Factorsmore » $$H_{Im}$$ and $$\\tilde{H}_{Im}$$ with uncertainties, in average, of the order of 30%.« less

  2. The angular momentum distribution within haloes in different dark matter models

    NASA Astrophysics Data System (ADS)

    Chen, D. N.; Jing, Y. P.

    2002-10-01

    We study the angular momentum profile of dark matter haloes for a statistical sample drawn from a set of high-resolution cosmological simulations of 2563 particles. Two typical cold dark matter (CDM) models have been analysed, and the haloes are selected to have at least 3 × 104 particles in order to measure the angular momentumprofile reliably. In contrast with the recent claims of Bullock et al., we find that the degree of misalignment of angular momentum within a halo is very high. Approximately 50 per cent of haloes have more than 10 per cent of the halo mass in the mass of negative angular momentum j. After the mass of negative j is excluded, the cumulative mass function M(angular momentum profile of haloes in a warm dark matter (WDM) model and a self-interacting dark matter (SIDM) model. We find that the angular momentum profile of haloes in the WDM is statistically indistinguishable from that in the CDM model, but the angular momentum of haloes in the SIDM is reduced by the self-interaction of dark matter.

  3. Exclusive studies of angular distributions in GeV hadron-induced reactions with {sup 197}Au

    SciTech Connect

    Hsi, W.; Kwiatkowski, K.; Wang, G.; Bracken, D.S.; Cornell, E.; Ginger, D.S.; Viola, V.E.; Korteling, R.G.; Morley, K.B.; Huang, R.; Lynch, W.G.; Tsang, M.B.; Xi, H.; Gimeno-Nogues, F.; Ramakrishnan, E.; Rowland, D.; Yennello, S.J.; Breuer, H.; Gushue, S.; Remsberg, L.P.; Botvina, A.; Friedman, W.A.

    1999-09-01

    Exclusive studies of angular distributions for intermediate-mass fragments (IMFs) produced in GeV hadron-induced reactions have been performed with the Indiana Silicon Sphere (ISiS) 4{pi} detector array. Special emphasis has been given to understanding the origin of sideways peaking, which becomes prominent in the angular distributions for beam momenta above about 10 GeV/c. Both the magnitude of the effect and the peak angle increase as a function of fragment multiplicity and charge. When gated on IMF kinetic energy, the angular distributions evolve from forward-peaked to near isotropy as the fragment kinetic energy decreases. Fragment-fragment angular-correlation analyses show no obvious evidence for a dynamic mechanism that might signal shock wave effects or the breakup of exotic geometric shapes such as bubbles or toroids. Moving-source and intranuclear cascade simulations suggest that the observed sideways peaking is of kinematic origin, arising from significant transverse momentum imparted to the heavy recoil nucleus during the fast cascade stage of the collision. A two-step cascade and statistical multifragmentation calculation is consistent with this assumption. {copyright} {ital 1999} {ital The American Physical Society}

  4. Exclusive studies of angular distributions in GeV hadron-induced reactions with [sup 197]Au

    SciTech Connect

    Hsi, W.; Kwiatkowski, K.; Wang, G.; Bracken, D.S.; Cornell, E.; Ginger, D.S.; Viola, V.E. ); Korteling, R.G. V5A I56); Morley, K.B. ); Huang, R.; Lynch, W.G.; Tsang, M.B.; Xi, H. ); Gimeno-Nogues, F.; Ramakrishnan, E.; Rowland, D.; Yennello, S.J. ); Breuer, H. ); Gushue, S.; Remsberg, L.P. ); Botvin

    1999-09-01

    Exclusive studies of angular distributions for intermediate-mass fragments (IMFs) produced in GeV hadron-induced reactions have been performed with the Indiana Silicon Sphere (ISiS) 4[pi] detector array. Special emphasis has been given to understanding the origin of sideways peaking, which becomes prominent in the angular distributions for beam momenta above about 10 GeV/c. Both the magnitude of the effect and the peak angle increase as a function of fragment multiplicity and charge. When gated on IMF kinetic energy, the angular distributions evolve from forward-peaked to near isotropy as the fragment kinetic energy decreases. Fragment-fragment angular-correlation analyses show no obvious evidence for a dynamic mechanism that might signal shock wave effects or the breakup of exotic geometric shapes such as bubbles or toroids. Moving-source and intranuclear cascade simulations suggest that the observed sideways peaking is of kinematic origin, arising from significant transverse momentum imparted to the heavy recoil nucleus during the fast cascade stage of the collision. A two-step cascade and statistical multifragmentation calculation is consistent with this assumption. [copyright] [ital 1999] [ital The American Physical Society

  5. Measurements of partial cross sections and photoelectron angular distributions for the photodetachment of Fe- and Cu- at visible photon wavelengths

    NASA Astrophysics Data System (ADS)

    Covington, A. M.; Duvvuri, Srividya S.; Emmons, E. D.; Kraus, R. G.; Williams, W. W.; Thompson, J. S.; Calabrese, D.; Carpenter, D. L.; Collier, R. D.; Kvale, T. J.; Davis, V. T.

    2007-02-01

    Photodetachment cross sections and the angular distributions of photoelectrons produced by the single-photon detachment of the transition metal negative ions Fe- and Cu- have been measured at four discrete photon wavelengths ranging from 457.9 to 647.1nm (2.71-1.92eV) using a crossed-beams laser photodetachment electron spectrometry (LPES) apparatus. Photodetachment cross sections were determined by comparing the photoelectron yields from the photodetachment of Fe- to those of Cu- and C- , which have known absolute photodetachment cross sections. Using the measured photodetachment cross sections, radiative electron attachment cross sections were calculated using the principle of detailed balance. Angular distributions were determined by measurements of laboratory frame, angle-, and energy-resolved photoelectrons as a function of the angle between the linear laser polarization vector and the momentum vector of the collected photoelectrons. Values of the asymmetry parameter have been determined by nonlinear least-squares fits to these angular distributions. The measured asymmetry parameters are compared to predictions of photodetachment models including Cooper and Zare’s dipole approximation theory [J. Cooper and R. N. Zare, J. Chem. Phys. 48, 942 (1968)], and the angular momentum transfer theory developed by Fano and Dill [Phys. Rev. A 6, 185 (1972)].

  6. Light scattering by lunar-like particle size distributions

    NASA Technical Reports Server (NTRS)

    Goguen, Jay D.

    1991-01-01

    A fundamental input to models of light scattering from planetary regoliths is the mean phase function of the regolith particles. Using the known size distribution for typical lunar soils, the mean phase function and mean linear polarization for a regolith volume element of spherical particles of any composition were calculated from Mie theory. The two contour plots given here summarize the changes in the mean phase function and linear polarization with changes in the real part of the complex index of refraction, n - ik, for k equals 0.01, the visible wavelength 0.55 micrometers, and the particle size distribution of the typical mature lunar soil 72141. A second figure is a similar index-phase surface, except with k equals 0.1. The index-phase surfaces from this survey are a first order description of scattering by lunar-like regoliths of spherical particles of arbitrary composition. They form the basis of functions that span a large range of parameter-space.

  7. Modeling angles in proteins and circular genomes using multivariate angular distributions based on multiple nonnegative trigonometric sums.

    PubMed

    Fernández-Durán, Juan José; Gregorio-Domínguez, María Mercedes

    2014-02-01

    Fernández-Durán, J. J. (2004): "Circular distributions based on nonnegative trigonometric sums," Biometrics, 60, 499-503, developed a family of univariate circular distributions based on nonnegative trigonometric sums. In this work, we extend this family of distributions to the multivariate case by using multiple nonnegative trigonometric sums to model the joint distribution of a vector of angular random variables. Practical examples of vectors of angular random variables include the wind direction at different monitoring stations, the directions taken by an animal on different occasions, the times at which a person performs different daily activities, and the dihedral angles of a protein molecule. We apply the proposed new family of multivariate distributions to three real data-sets: two for the study of protein structure and one for genomics. The first is related to the study of a bivariate vector of dihedral angles in proteins. In the second real data-set, we compare the fit of the proposed multivariate model with the bivariate generalized von Mises model of [Shieh, G. S., S. Zheng, R. A. Johnson, Y.-F. Chang, K. Shimizu, C.-C. Wang, and S.-L. Tang (2011): "Modeling and comparing the organization of circular genomes," Bioinformatics, 27(7), 912-918.] in a problem related to orthologous genes in pairs of circular genomes. The third real data-set consists of observed values of three dihedral angles in γ-turns in a protein and serves as an example of trivariate angular data. In addition, a simulation algorithm is presented to generate realizations from the proposed multivariate angular distribution.

  8. Angular and Linear Velocity Estimation for a Re-Entry Vehicle Using Six Distributed Accelerometers: Theory, Simulation and Feasibility

    SciTech Connect

    Clark, G

    2003-04-28

    This report describes a feasibility study. We are interested in calculating the angular and linear velocities of a re-entry vehicle using six acceleration signals from a distributed accelerometer inertial measurement unit (DAIMU). Earlier work showed that angular and linear velocity calculation using classic nonlinear ordinary differential equation (ODE) solvers is not practically feasible, due to mathematical and numerical difficulties. This report demonstrates the theoretical feasibility of using model-based nonlinear state estimation techniques to obtain the angular and linear velocities in this problem. Practical numerical and calibration issues require additional work to resolve. We show that the six accelerometers in the DAIMU are not sufficient to provide observability, so additional measurements of the system states are required (e.g. from a Global Positioning System (GPS) unit). Given the constraint that our system cannot use GPS, we propose using the existing on-board 3-axis magnetometer to measure angular velocity. We further show that the six nonlinear ODE's for the vehicle kinematics can be decoupled into three ODE's in the angular velocity and three ODE's in the linear velocity. This allows us to formulate a three-state Gauss-Markov system model for the angular velocities, using the magnetometer signals in the measurement model. This re-formulated model is observable, allowing us to build an Extended Kalman Filter (EKF) for estimating the angular velocities. Given the angular velocity estimates from the EKF, the three ODE's for the linear velocity become algebraic, and the linear velocity can be calculated by numerical integration. Thus, we do not need direct measurements of the linear velocity to provide observability, and the technique is mathematically feasible. Using a simulation example, we show that the estimator adds value over the numerical ODE solver in the presence of measurement noise. Calculating the velocities in the presence of

  9. The angular distributions of ultraviolet spectral irradiance at different solar elevation angles under clear sky conditions

    NASA Astrophysics Data System (ADS)

    Liu, Yan; Hu, LiWen; Wang, Fang; Gao, YanYan; Zheng, Yang; Wang, Yu; Liu, Yang

    2016-01-01

    To investigate the angular distributions of UVA, UVB, and effective UV for erythema and vitamin D (vitD) synthesis, the UV spectral irradiances were measured at ten inclined angles (from 0° to 90°) and seven azimuths (from 0° to 180°) at solar elevation angle (SEA) that ranged from 18.8° to 80° in Shanghai (31.22° N, 121.55° E) under clear sky and the albedo of ground was 0.1. The results demonstrated that in the mean azimuths and with the back to the sun, the UVA, UVB, and erythemally and vitD-weighted irradiances increased with the inclined angles and an increase in SEA. When facing toward the sun at 0°-60° inclined angles, the UVA first increased and then decreased with an increase in SEA; at other inclined angles, the UVA increased with SEA. At 0°-40° inclined angles, the UVB and erythemally and vitD-weighted irradiances first increased and then decreased with an increase in SEA, and their maximums were achieved at SEA 68.7°; at other inclined angles, the above three irradiances increased with an increase in SEA. The maximum UVA, UVB, and erythemally and vitD-weighted irradiances were achieved at an 80° inclined angle at SEA 80° (the highest in our measurements); the cumulative exposure of the half day achieved the maximum at a 60° inclined angle, but not on the horizontal. This study provides support for the assessment of human skin sun exposure.

  10. Polarization Imaging over Sea Surface - A Method for Measurements of Stokes Components Angular Distribution

    NASA Astrophysics Data System (ADS)

    Freda, W.; Piskozub, J.; Toczek, H.

    2015-12-01

    This article describes a method for determining the angular distribution of light polarization over a roughened surface of the sea. Our method relies on measurements of the Stokes vector elements using a polarization imaging camera that operates using the Division of Focal Plane (DoFP) method. It uses special monochrome CCD array in which the neighbouring cells, instead of recording different colours (red green and blue), are equipped with micropolarizers of four directions (0, 45, 90 and 135 degrees). We combined the camera with a fish-eye lens of Field of View (FoV) > 180 deg. Such a large FoV allowed us to crop out the fragment of the frame along the circular horizon, showing a view covering all directions of the hemisphere. Because of complicated optical design of the fish-eye lens (light refraction on surfaces of parts of the lens) connected to the sensor we checked the accuracy of the measurement system. A method to determine the accuracy of measured polarization is based on comparison of the experimentally obtained rotation matrix with its theoretical form. Such a comparison showed that the maximum error of Stokes vector elements depended on zenith angle and reached as much as 24% for light coming from just above the horizon, but decreased rapidly with decreasing zenith angle to the value of 12% for the angles 10° off the edge of FoV. Moreover we present the preliminary results prepared over rough sea surface. These results include total intensity of light, Degree of Linear Polarization (DoLP) and their standard deviations. The results have been averaged over one thousand frames of a movie. These results indicate that the maximum polarization is observed near the reflection of the sun, and the signal coming from below the surface may be observed at zenith angles far from the vertical direction.

  11. Diffraction pattern from thermal neutron incoherent elastic scattering and the holographic reconstruction of the coherent scattering length distribution

    SciTech Connect

    Sur, B.; Anghel, V.N.P.; Rogge, R.B.; Katsaras, J.

    2005-01-01

    The diffraction of spherical waves (S waves) interacting with a periodic scattering length distribution produces characteristic intensity patterns known as Kossel and Kikuchi lines (collectively called K lines). The K-line signal can be inverted to give the three-dimensional structure of the coherent scattering length distribution surrounding the source of S waves - a process known as 'Gabor holography' or, simply, 'holography'. This paper outlines a kinematical formulation for the diffraction pattern of monochromatic plane waves scattering from a mixed incoherent and coherent S-wave scattering length distribution. The formulation demonstrates that the diffraction pattern of plane waves incident on a sample with a uniformly random distribution of incoherent scatterers is the same as that from a sample with a single incoherent scatterer per unit cell. In practice, one can therefore reconstruct the holographic data from samples with numerous incoherent S-wave scatterers per unit cell. Thus atomic resolution thermal neutron holography is possible for materials naturally rich in incoherent thermal neutron scatterers, such as hydrogen (e.g., biological and polymeric materials). Additionally, holographic inversions from single-wavelength data have suffered from the so-called conjugate or twin-image problem. The formulation presented for holographic inversion - different from those used previously [e.g., T. Gog et al., Phys. Rev. Lett. 76, 3132 (1996)] - eliminates the twin-image problem for single-wavelength data.

  12. Angular Distributions of High-Mass Dilepton Production in Hadron Collisions

    SciTech Connect

    McClellan, Randall Evan

    2016-01-01

    λ has been performed, and the remaining difficulties in extracting ν have been evaluated. Although the results are not yet publishable, significant progress has been made in developing this very challenging angular distributions analysis. A simple scheme for correcting for the angular acceptances of the spectrometer, trigger, and reconstruction has been developed and demonstrated. A generally applicable correction for the kinematically-dependent, rate-dependent reconstruction efficiency has been developed and applied to all current analyses on SeaQuest data. This rate-dependence correction was the first major hurdle in the path to publication of many preliminary SeaQuest results. The last remaining major correction for all analyses, but especially important for the angular parameter extraction, is the full characterization, rate-dependence correction, and subtraction of the combinatoric background contribution to the reconstructed dimuon sample. Independently, an intuitive, kinematic derivation of the single-event definitions of the Drell-Yan angular parameters has been developed under the assumption of unpolarized annihilating quarks within unpolarized nuclei. At O(αs), where the quarks remain co-planar with the hadrons in the photon rest frame, this kinematic method reproduces the Lam-Tung relation and derives an additional equality for µ2, which is only interpretable for single-event parameters. This method has been extended to the case of quark non- coplanarity, and the coplanar equalities become inequalities. A new equality was discovered, which should be obeyed by single-event parameters even in the case of a non-coplanar quark axis. The non-coplanar parameter relations have been used to derive constraints on the experimentally accessible values of λ and ν. These constraints are compared with existing data and have been found consistent, except in the cases where significant contributions from non-zero Boer-Mulders functions are expected. Finally, the

  13. Angular dependence of the pp elastic-scattering analyzing power between 0.8 and 2.8 GeV. II. Results for higher energies

    SciTech Connect

    Allgower, C.E.; Beddo, M.E.; Grosnick, D.P.; Kasprzyk, T.E.; Lopiano, D.; Spinka, H.M.; Ball, J.; Chamouard, P.; Combet, M.; Fontaine, J.; Kunne, R.; Sans, J.; Janout, Z.; Kalinnikov, V.A.; Khachaturov, B.A.; Matafonov, V.N.; Pisarev, I.L.; Popov, A.A.; Usov, Y.A.; Prokofiev, A.N.; Vikhrov, V.V.; Zhdanov, A.A.

    1999-11-01

    Measurements at 18 beam kinetic energies between 1975 and 2795 MeV and at 795 MeV are reported for the pp elastic-scattering single spin parameter A{sub ooon}=A{sub oono}=A{sub N}=P. The c.m. angular range is typically 60{endash}100{degree}. These results are compared to previous data from Saturne II and other accelerators. A search for energy-dependent structure at fixed c.m. angles is performed, but no rapid changes are observed. {copyright} {ital 1999} {ital The American Physical Society}

  14. Angular distribution and recoil effect for 1 MeV Au+ ions through a Si3N4 thin foil

    SciTech Connect

    Jin, Ke; Zhu, Zihua; Manandhar, Sandeep; Liu, Jia; Chen, Chien-Hung; Shutthanandan, Vaithiyalingam; Thevuthasan, Suntharampillai; Weber, William J; Zhang, Yanwen

    2014-01-01

    The Stopping and Range of Ions in Matter (SRIM) code has been widely used to predict nuclear stopping power and angular distribution of ion-solid collisions. However, experimental validation of the predictions is insufficient for slow heavy ions in nonmetallic compounds. In this work, time-of-flight secondary ion mass spectrometry (ToF-SIMS) is applied to determine the angular distribution of 1 MeV Au ions after penetrating a Si3N4 foil with a thickness of ~100 nm. The exiting Au ions are collected by a Si wafer located ~14 mm behind the Si3N4 foil, and the resulting 2-dimensional distribution of Au ions on the Si wafer is measured by ToF-SIMS. The SRIM-predicted angular distribution of Au ions through the Si3N4 thin foil is compared with the measured results, indicating that SRIM slightly overestimates the nuclear stopping power by up to 10%. In addition, thickness reduction of the suspended Si3N4 foils induced by 1 MeV Au ion irradiation is observed with an average loss rate of ~107 atom/ion.

  15. High resolution Coulomb explosion spectra and angular distributions of fragment ions of N 2 in a femtosecond laser field

    NASA Astrophysics Data System (ADS)

    Shi, Mingyuan; Huang, Shaochuan; Xi, Wei; Liu, Zuoye; Du, Hongchuan; Ding, Baowei; Hu, Bitao

    2017-03-01

    Femtosecond laser field-induced ionization and Coulomb explosion are systematically investigated using high-resolution time-of-flight mass spectroscopy. Meanwhile a good alignment of the N2 is achieved geometrically. Based on the energy and momentum conservation laws, the events from different Coulomb explosion channels are identified accurately and further used to obtain the Kinetic Energy Release (KER) by the created molecular ion pairs and the angular distributions of the fragment ions. The KERs measured at laser intensities varying from 4 × 10^{14} W/cm2 to 2 × 10^{15} W/cm2 are found to stay constant. The angular distributions are measured at laser intensity of 9 × 10^{14} W/cm2. The atomic ions N+, N^{2+} and N^{3+} exhibit highly anisotropic distributions and for higher charge state, the angular distributions become narrower. With good exclusion of channel N(1,0), the non-zeroes normal to the laser polarization vector in channel N(1,1) still exist, which indicates the presence of geometric alignments (GA). The elusive shrink structure at θ=0° for channels N(1,1), N(1,2) and N(2,3) is observed, which implies that the non-sequential process exists, and the electron rescattering plays role in the ionization process.

  16. Search for quark compositeness in dijet angular distributions from pp collisions at sqrt(s) = 7 TeV

    SciTech Connect

    Chatrchyan, Serguei; et al.

    2012-05-01

    A search for quark compositeness using dijet angular distributions from pp collisions at sqrt(s) = 7 TeV is presented. The search has been carried out using a data sample corresponding to an integrated luminosity of 2.2 inverse femtobarns, recorded by the CMS experiment at the LHC. Normalized dijet angular distributions have been measured for dijet invariant masses from 0.4 TeV to above 3 TeV and compared with a variety of contact interaction models, including those which take into account the effects of next-to-leading-order QCD corrections. The data are found to be in agreement with the predictions of perturbative QCD, and lower limits are obtained on the contact interaction scale, ranging from 7.5 up to 14.5 TeV at 95% confidence level.

  17. Unambiguous observation of F-atom core-hole localization in CF4 through body-frame photoelectron angular distributions

    NASA Astrophysics Data System (ADS)

    McCurdy, C. W.; Rescigno, T. N.; Trevisan, C. S.; Lucchese, R. R.; Gaire, B.; Menssen, A.; Schöffler, M. S.; Gatton, A.; Neff, J.; Stammer, P. M.; Rist, J.; Eckart, S.; Berry, B.; Severt, T.; Sartor, J.; Moradmand, A.; Jahnke, T.; Landers, A. L.; Williams, J. B.; Ben-Itzhak, I.; Dörner, R.; Belkacem, A.; Weber, Th.

    2017-01-01

    A dramatic symmetry breaking in K -shell photoionization of the CF4 molecule in which a core-hole vacancy is created in one of four equivalent fluorine atoms is displayed in the molecular frame angular distribution of the photoelectrons. Observing the photoejected electron in coincidence with an F+ atomic ion after Auger decay is shown to select the dissociation path where the core hole was localized almost exclusively on that atom. A combination of measurements and ab initio calculations of the photoelectron angular distribution in the frame of the recoiling CF3+ and F+ atoms elucidates the underlying physics that derives from the Ne-like valence structure of the F(1 s-1 ) core-excited atom.

  18. Lidar measurements of cloud extinction coefficient distribution and its forward scattering phase function according to multiply scattered lidar returns

    NASA Technical Reports Server (NTRS)

    Qiu, Jinhuan; Huang, Qirong

    1992-01-01

    The study of the inversion algorithm for the single scatter lidar equation, for quantitative determination of cloud (or aerosol) optical properties, has received much attention over the last thirty years. Some of the difficulties associated with the solution of this equation are not yet solved. One problem is that a single scatter lidar equation has two unknowns. Because of this, the determination of the far-end boundary value, in the case of Klett's algorithm, is a problem if the atmosphere is optically inhomogeneous. Another difficulty concerns multiple scattering. There is a large error in the extinction distribution solution, in many cases, if only the single scattering component is considered, while neglecting the multiple scattering component. However, the use of multiple scattering in the remote sensing of aerosol or cloud optical properties is promising. In our early study, an inversion method for simultaneous determination of the cloud (or aerosol) Extinction Coefficient Distribution (ECD) and its Forward Scattering Phase Function (FSPF) was proposed according to multiply scattered lidar returns with two fields of view for the receiver. The method is based on a parameterized multiple scatter lidar equation. This paper is devoted to further numerical tests and an experimental study of lidar measurements of cloud ECD and FSPF using this method.

  19. Polarization of photons scattered by electrons in any spectral distribution

    SciTech Connect

    Chang, Zhe; Lin, Hai-Nan; Jiang, Yunguo

    2014-01-01

    On the basis of the quantum electrodynamics, we present a generic formalism of the polarization for beamed monochromatic photons scattered by electrons in any spectral distribution. The formulae reduce to the components of the Fano matrix when electrons are at rest. We mainly investigate the polarization in three scenarios, i.e., electrons at rest, isotropic electrons with a power-law spectrum, and thermal electrons. If the incident beam is polarized, the polarization is reduced significantly by isotropic electrons at large viewing angles; the degree of polarization caused by thermal electrons is about half of that caused by power-law electrons. If the incident bean is unpolarized, soft γ-rays can lead to about 15% polarization at viewing angles around π/4. For isotropic electrons, one remarkable feature is that the polarization as a function of the incident photon energy always peaks roughly at 1 MeV; this is valid for both the thermal and power-law cases. This feature can be used to distinguish the model of the inverse Compton scattering from that of the synchrotron radiation.

  20. Angular distribution of hypersatellite and satellite radiation emitted after resonant transfer and excitation into U{sup 91+} ions

    SciTech Connect

    Zakowicz, S.; Harman, Z.; Gruen, N.; Scheid, W.

    2003-10-01

    In collisions of heavy few-electron projectile ions with light targets, an electron can be transferred from the target with the simultaneous excitation of a projectile electron. We study the angular distribution of deexcitation x rays following the resonant capture process. Our results are compared to experimental values of Ma et al. [Phys. Rev. A 68, 042712 (2003)] for collisions of U{sup 91+} ions with a hydrogen gas target.

  1. Tracking hole localization in K -shell and core-valence-excited acetylene photoionization via body-frame photoelectron angular distributions

    NASA Astrophysics Data System (ADS)

    Rescigno, T. N.; Trevisan, C. S.; McCurdy, C. W.

    2015-02-01

    Asymmetry in the molecular-frame photoelectron angular distributions from core-hole- or core-valence-excited polyatomic targets with symmetry-equivalent atoms can provide direct evidence for core-hole localization. Using acetylene as an example, we contrast the small asymmetry that can be seen in direct core-level ionization, due to the competition between two competing pathways to the continuum, with ionization from core-valence-excited HCCH, which offers the prospect of observing markedly greater asymmetry.

  2. Rotational and angular distributions of NO products from NO-Rg(Rg = He, Ne, Ar) complex photodissociation

    DOE PAGES

    Heather L. Holmes-Ross; Hall, Gregory E.; Valenti, Rebecca J.; ...

    2016-01-29

    In this study, we present the results of an investigation into the rotational and angular distributions of the NO A~ state fragment following photodissociation of the NO-He, NO-Ne and NO-Ar van der Waals complexed excited via the A~ ← X~ transition. For each complex the dissociation is probed for several values of Ea, the available energy above the dissociation threshold.

  3. Rotational and angular distributions of NO products from NO-Rg(Rg = He, Ne, Ar) complex photodissociation

    SciTech Connect

    Heather L. Holmes-Ross; Hall, Gregory E.; Valenti, Rebecca J.; Yu, Hua -Gen; Lawrance, Warren D.

    2016-01-29

    In this study, we present the results of an investigation into the rotational and angular distributions of the NO A~ state fragment following photodissociation of the NO-He, NO-Ne and NO-Ar van der Waals complexed excited via the A~ ← X~ transition. For each complex the dissociation is probed for several values of Ea, the available energy above the dissociation threshold.

  4. Angular distribution of light emission from compound-eye cornea with conformal fluorescent coating

    NASA Astrophysics Data System (ADS)

    Martín-Palma, Raúl J.; Miller, Amy E.; Pulsifer, Drew P.; Lakhtakia, Akhlesh

    2014-09-01

    The complex morphology of the apposition compound eyes of insects of many species provides them a wide angular field of view. This characteristic makes these eyes attractive for bioreplication as artificial sources of light. The cornea of a blowfly eye was conformally coated with a fluorescent thin film with the aim of achieving wide field-of-view emission. On illumination by shortwave-ultraviolet light, the conformally coated eye emitted visible light whose intensity showed a weaker angular dependence than a fluorescent thin film deposited on a flat surface.

  5. Rotational and angular distributions of NO products from NO-Rg (Rg = He, Ne, Ar) complex photodissociation.

    PubMed

    Holmes-Ross, Heather L; Valenti, Rebecca J; Yu, Hua-Gen; Hall, Gregory E; Lawrance, Warren D

    2016-01-28

    We present the results of an investigation into the rotational and angular distributions of the NO à state fragment following photodissociation of the NO-He, NO-Ne, and NO-Ar van der Waals complexes excited via the à ← X̃ transition. For each complex, the dissociation is probed for several values of Ea, the available energy above the dissociation threshold. For NO-He, the Ea values probed were 59, 172, and 273 cm(-1); for NO-Ne they were 50 and 166 cm(-1); and for NO-Ar they were 44, 94, 194, and 423 cm(-1). The NO à state rotational distributions arising from NO-He are cold, with most products in low angular momentum states. NO-Ne leads to broader NO rotational distributions but they do not extend to the maximum possible given the energy available. In the case of NO-Ar, the distributions extend to the maximum allowed at that energy and show the unusual shapes associated with the rotational rainbow effect reported in previous studies. This is the only complex for which a rotational rainbow effect is observed at the chosen Ea values. Product angular distributions have also been measured for the NO à photodissociation product for the three complexes. NO-He produces nearly isotropic fragments, but the anisotropy parameter, β, for NO-Ne and NO-Ar photofragments shows a surprising change in sign from negative to positive as Ea increases within the unstructured excitation profile. Franck-Condon selection of a broader distribution of geometries including more linear geometries at lower excitation energies and more T-shaped geometries at higher energies can account for the changing recoil anisotropy. Two-dimensional wavepacket calculations are reported to model the rotational state distributions and the bound-continuum absorption spectra.

  6. Rotational and angular distributions of NO products from NO-Rg (Rg = He, Ne, Ar) complex photodissociation

    NASA Astrophysics Data System (ADS)

    Holmes-Ross, Heather L.; Valenti, Rebecca J.; Yu, Hua-Gen; Hall, Gregory E.; Lawrance, Warren D.

    2016-01-01

    We present the results of an investigation into the rotational and angular distributions of the NO A ˜ state fragment following photodissociation of the NO-He, NO-Ne, and NO-Ar van der Waals complexes excited via the A ˜ ←X ˜ transition. For each complex, the dissociation is probed for several values of Ea, the available energy above the dissociation threshold. For NO-He, the Ea values probed were 59, 172, and 273 cm-1; for NO-Ne they were 50 and 166 cm-1; and for NO-Ar they were 44, 94, 194, and 423 cm-1. The NO A ˜ state rotational distributions arising from NO-He are cold, with most products in low angular momentum states. NO-Ne leads to broader NO rotational distributions but they do not extend to the maximum possible given the energy available. In the case of NO-Ar, the distributions extend to the maximum allowed at that energy and show the unusual shapes associated with the rotational rainbow effect reported in previous studies. This is the only complex for which a rotational rainbow effect is observed at the chosen Ea values. Product angular distributions have also been measured for the NO A ˜ photodissociation product for the three complexes. NO-He produces nearly isotropic fragments, but the anisotropy parameter, β, for NO-Ne and NO-Ar photofragments shows a surprising change in sign from negative to positive as Ea increases within the unstructured excitation profile. Franck-Condon selection of a broader distribution of geometries including more linear geometries at lower excitation energies and more T-shaped geometries at higher energies can account for the changing recoil anisotropy. Two-dimensional wavepacket calculations are reported to model the rotational state distributions and the bound-continuum absorption spectra.

  7. Vibronic coupling in the superoxide anion: The vibrational dependence of the photoelectron angular distribution

    NASA Astrophysics Data System (ADS)

    Van Duzor, Matthew; Mbaiwa, Foster; Wei, Jie; Singh, Tulsi; Mabbs, Richard; Sanov, Andrei; Cavanagh, Steven J.; Gibson, Stephen T.; Lewis, Brenton R.; Gascooke, Jason R.

    2010-11-01

    We present a comprehensive photoelectron imaging study of the O2(X Σg-3,v '=0-6)←O2-(X Π2g,v ″=0) and O2(aΔ1g,v '=0-4)←O2-(X Π2g,v ″=0) photodetachment bands at wavelengths between 900 and 455 nm, examining the effect of vibronic coupling on the photoelectron angular distribution (PAD). This work extends the v'=1-4 data for detachment into the ground electronic state, presented in a recent communication [R. Mabbs, F. Mbaiwa, J. Wei, M. Van Duzor, S. T. Gibson, S. J. Cavanagh, and B. R. Lewis, Phys. Rev. A 82, 011401-R (2010)]. Measured vibronic intensities are compared to Franck-Condon predictions and used as supporting evidence of vibronic coupling. The results are analyzed within the context of the one-electron, zero core contribution (ZCC) model [R. M. Stehman and S. B. Woo, Phys. Rev. A 23, 2866 (1981)]. For both bands, the photoelectron anisotropy parameter variation with electron kinetic energy, β(E ), displays the characteristics of photodetachment from a d-like orbital, consistent with the πg∗ 2p highest occupied molecular orbital of O2-. However, differences exist between the β(E ) trends for detachment into different vibrational levels of the X Σg-3 and a Δ1g electronic states of O2. The ZCC model invokes vibrational channel specific "detachment orbitals" and attributes this behavior to coupling of the electronic and nuclear motion in the parent anion. The spatial extent of the model detachment orbital is dependent on the final state of O2: the higher the neutral vibrational excitation, the larger the electron binding energy. Although vibronic coupling is ignored in most theoretical treatments of PADs in the direct photodetachment of molecular anions, the present findings clearly show that it can be important. These results represent a benchmark data set for a relatively simple system, upon which to base rigorous tests of more sophisticated models.

  8. Angular distribution of particles sputtered from Si bottom in a CHF{sub 3} plasma

    SciTech Connect

    Lee, Jin-Kwan; Lee, Gyeo-Re; Min, Jae-Ho; Moon, Sang Heup

    2006-09-15

    The angular distribution (AD) of particles sputtered from a Si substrate in a CHF{sub 3} plasma at bias voltages between -200 and -400 V was investigated using a specially designed experimental setup for controlling the angle of incident ions on the substrate. Particles were sputtered from a primary target substrate, which was placed in a Faraday cage and on the horizontal cathode plane of a plasma etcher, by bombardment with ions incident in a direction normal to the substrate. The sputtered particles were redeposited on the surfaces of SiO{sub 2} secondary targets, which were fixed in small pieces at different positions on the convave surface of a circular sample holder, which was positioned above the primary target. A line connecting the primary and secondary targets defined the sputtering angle of the etch products. The redeposition rate was estimated from the difference in the thickness of the secondary target in two independent experiments, with and without the primary target. The redeposition rate was plotted as a function of sputtering angle and, the AD was then obtained from the plot. X-ray photoelectron spectroscopy analysis of a Si primary target subjected to etching indicated that a steady-state CF{sub x} film with a thickness of about 50 A was formed on the Si at a bias voltage of -400 V. This film was thicker than the ion-energy transfer depth (30 A ), and, as a result, it can be concluded that particles redeposited on the secondary target were sputtered from a steady-state CF{sub x} film that had been formed on the Si primary target. The AD of particles sputtered from the Si primary target showed an over-cosine dependence on the sputtering angle ({theta}), corresponding to cos{sup 3-4} {theta}, and the power of the over-cosine dependence increased with bias voltage. The characteristic changes in the AD support the view that particles contributing to the redeposition were generated largely by physical sputtering rather than by ion-enhanced chemical

  9. Angular distributions of photoelectrons and interatomic-Coulombic-decay electrons from helium dimers: Strong dependence on the internuclear distance

    SciTech Connect

    Havermeier, T.; Kreidi, K.; Wallauer, R.; Voss, S.; Schoeffler, M.; Schoessler, S.; Foucar, L.; Neumann, N.; Titze, J.; Sann, H.; Kuehnel, M.; Voigtsberger, J.; Schmidt-Boecking, H.; Doerner, R.; Jahnke, T.; Sisourat, N.; Schoellkopf, W.; Grisenti, R. E.

    2010-12-15

    In the present paper, we show that the absorption of a single photon can singly ionize both atoms of a helium dimer (He{sub 2}): ionization with simultaneous excitation of one atom followed by de-excitation via interatomic Coulombic decay leads to the ejection of an electron from each of the the two atoms of the dimer. Using the Cold Target Recoil Ion Momentum Spectroscopy technique (COLTRIMS), we obtained angular distributions of these electrons in the laboratory frame and the molecular frame. We observe a pronounced variation of these distributions for different regions of kinetic-energy releases of the ions.

  10. On angularly perturbed Laplace equations in the unit ball of IR{sup n+2} and their distributional boundary values

    SciTech Connect

    Massopust, P.R.

    1997-08-01

    All solutions of an in its angular coordinates continuously perturbed Laplace-Beltrami equation in the open unit ball IB{sup n+2} {contained_in} IR{sup n+2}, n {ge} 1, are characterized. Moreover, it is shown that such pertubations yield distributional boundary values which are different from, but algebraically and topologically equivalent to, the hyperfunctions of Lions & Magenes. This is different from the case of radially perturbed Laplace-Beltrami operators (cf. [7]) where one has stability of distributional boundary values under such perturbations.

  11. The effects of compensator design on scatter distribution and magnitude: a Monte Carlo study

    NASA Astrophysics Data System (ADS)

    Bootsma, G. J.; Verhaegen, F.; Jaffray, D. A.

    2011-03-01

    X-ray scatter has a significant impact on image quality in kV cone-beam CT (CBCT), its effects include: CT number inaccuracy, streak and cupping artifacts, and loss of contrast. Compensators provide a method for not only decreasing the magnitude of the scatter distribution, but also reducing the structure found in the scatter distribution. Recent Monte Carlo (MC) simulations examining X-ray scatter in CBCT projection images have shown that the scatter distribution in x-ray imaging contains structure largely induced by coherent scattering. In order to maximize the reduction of x-ray scatter induced artifacts a decrease in the magnitude and structure of the scatter distribution is sought through optimal compensator design. A flexible MC model that allows for separation of scattered and primary photons has been created to simulate the CBCT imaging process. The CBCT MC model is used to investigate the effectiveness of compensators in decreasing the magnitude and structure of the scatter distribution in CBCT projection images. The influence of the compensator designs on the scatter distribution are evaluated for different anatomy (abdomen, pelvis, and head and neck) and viewing angles using a voxelized anthropomorphic phantom. The effect of compensator material composition on the amount of contamination photons in an open field is also investigated.

  12. Phylogenetic analysis reveals a scattered distribution of autumn colours

    PubMed Central

    Archetti, Marco

    2009-01-01

    Background and Aims Leaf colour in autumn is rarely considered informative for taxonomy, but there is now growing interest in the evolution of autumn colours and different hypotheses are debated. Research efforts are hindered by the lack of basic information: the phylogenetic distribution of autumn colours. It is not known when and how autumn colours evolved. Methods Data are reported on the autumn colours of 2368 tree species belonging to 400 genera of the temperate regions of the world, and an analysis is made of their phylogenetic relationships in order to reconstruct the evolutionary origin of red and yellow in autumn leaves. Key Results Red autumn colours are present in at least 290 species (70 genera), and evolved independently at least 25 times. Yellow is present independently from red in at least 378 species (97 genera) and evolved at least 28 times. Conclusions The phylogenetic reconstruction suggests that autumn colours have been acquired and lost many times during evolution. This scattered distribution could be explained by hypotheses involving some kind of coevolutionary interaction or by hypotheses that rely on the need for photoprotection. PMID:19126636

  13. CFHTLenS and RCSLenS: testing photometric redshift distributions using angular cross-correlations with spectroscopic galaxy surveys

    NASA Astrophysics Data System (ADS)

    Choi, A.; Heymans, C.; Blake, C.; Hildebrandt, H.; Duncan, C. A. J.; Erben, T.; Nakajima, R.; Van Waerbeke, L.; Viola, M.

    2016-12-01

    We determine the accuracy of galaxy redshift distributions as estimated from photometric redshift probability distributions p(z). Our method utilizes measurements of the angular cross-correlation between photometric galaxies and an overlapping sample of galaxies with spectroscopic redshifts. We describe the redshift leakage from a galaxy photometric redshift bin j into a spectroscopic redshift bin i using the sum of the p(z) for the galaxies residing in bin j. We can then predict the angular cross-correlation between photometric and spectroscopic galaxies due to intrinsic galaxy clustering when i ≠ j as a function of the measured angular cross-correlation when i = j. We also account for enhanced clustering arising from lensing magnification using a halo model. The comparison of this prediction with the measured signal provides a consistency check on the validity of using the summed p(z) to determine galaxy redshift distributions in cosmological analyses, as advocated by the Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS). We present an analysis of the photometric redshifts measured by CFHTLenS, which overlaps the Baryon Oscillation Spectroscopic Survey (BOSS). We also analyse the Red-sequence Cluster Lensing Survey, which overlaps both BOSS and the WiggleZ Dark Energy Survey. We find that the summed p(z) from both surveys are generally biased with respect to the true underlying distributions. If unaccounted for, this bias would lead to errors in cosmological parameter estimation from CFHTLenS by less than ˜4 per cent. For photometric redshift bins which spatially overlap in 3D with our spectroscopic sample, we determine redshift bias corrections which can be used in future cosmological analyses that rely on accurate galaxy redshift distributions.

  14. State-selective influence of the Breit interaction on the angular distribution of emitted photons following dielectronic recombination

    NASA Astrophysics Data System (ADS)

    Amaro, Pedro; Shah, Chintan; Steinbrügge, Rene; Beilmann, Christian; Bernitt, Sven; López-Urrutia, José R. Crespo; Tashenov, Stanislav

    2017-02-01

    We report a measurement of K L L dielectronic recombination in charge states from Kr+34 through Kr+28 in order to investigate the contribution of the Breit interaction for a wide range of resonant states. Highly charged Kr ions were produced in an electron-beam ion trap, while the electron-ion collision energy was scanned over a range of dielectronic recombination resonances. The subsequent K α x rays were recorded both along and perpendicular to the electron-beam axis, which allowed the observation of the influence of the Breit interaction on the angular distribution of the x rays. Experimental results are in good agreement with distorted-wave calculations. We demonstrate, both theoretically and experimentally, that there is a strong state-selective influence of the Breit interaction that can be traced back to the angular and radial properties of the wave functions in the dielectronic capture.

  15. Interplay between theory and experiment for fission-fragment angular distributions from nuclei near the limits of stability

    NASA Astrophysics Data System (ADS)

    Freifelder, R.; Prakash, M.; Alexander, John M.

    1986-02-01

    We examine the application of transition-state theory for fission-fragment angular distributions to composite nuclei near the limits of stability. The possible roles of saddle-point and scission-point configurations are explored. For many heavy-ion reactions that involve large angular momenta, the observed anisotropies are between the predictions of the saddle-point and scisson-point models. Empirical correlations are shown between the effective moments of inertia and the spin and {Z 2}/{A} of the compound nucleus. These correlations provide evidence for a class of transition-state nuclei intermediate between saddle- and scission-point configurations. An important indication of these patterns is that the speed of collective deformation toward fission may well be slow enough to allow for statistical equilibrium in the tilting mode even for configurations well beyond the saddle point.

  16. Effects of anisotropic electron-ion interactions in atomic photoelectron angular distributions

    NASA Technical Reports Server (NTRS)

    Dill, D.; Starace, A. F.; Manson, S. T.

    1974-01-01

    The photoelectron asymmetry parameter beta in LS-coupling is obtained as an expansion into contributions from alternative angular momentum transfers j sub t. The physical significance of this expansion of beta is shown to be that: (1) the electric dipole interaction transfers to the atom a charcteristic single angular momentum j sub t = sub o, where sub o is the photoelectron's initial orbital momentum; and (2) angular momentum transfers indicate the presence of anisotropic interaction of the outgoing photoelectron with the residual ion. For open shell atoms the photoelectron-ion interaction is generally anisotropic; photoelectron phase shifts and electric dipole matrix elements depend on both the multiplet term of the residual ion and the total orbital momentum of the ion-photoelectron final state channel. Consequently beta depends on the term levels of the residual ion and contains contributions from all allowed values of j sub t. Numerical calculations of the asymmetry parameters and partial cross sections for photoionization of atomic sulfur are presented.

  17. Angular correlation measurements for {sup 12}C{sup 12}C,{sup 12}C{sup 12}C 3{sup -} scattering

    SciTech Connect

    Wuosmaa, A.H.; Betts, R.R.; Freer, M.

    1995-08-01

    Previous studies of inelastic {sup 12}C + {sup 12}C scattering to a variety of final states identified significant resonance behavior in a number of different reaction channels. These resonances can be interpreted as either potential scattering resonances, or as population of cluster structures in the compound nucleus {sup 24}Mg, or as some interplay between the two mechanisms. Currently, for many of these resonances the situation remains unclear. One example is a large peak observed in the excitation function for the 3{sup -} - g.s. excitation, identified in previous work performed at the Daresbury Laboratory in England. This peak is observed at the same center-of-mass energy as one observed in the O{sub 2}{sup +}-O{sub 2}{sup +} inelastic scattering channel. That structure was suggested to correspond to exotic deformed configurations in the compound nucleus {sup 24}Mg. As the peak in the 3{sup -} + g.s. exit channel occurs at precisely the same energy as the purported resonance, it is tempting to associate the two. Before such an association can be confirmed or ruled out, further information must be obtained about the 3{sup -} + g.s. structure. In particular, it is important to determine the angular momenta that dominate the 3{sup -} + g.s. structure.

  18. High resolution Dopplerimetry of correlated angular and quantum state-resolved CO(2) scattering dynamics at the gas-liquid interface.

    PubMed

    Perkins, Bradford G; Nesbitt, David J

    2010-11-14

    Full three dimensional (3D) translational distributions for quantum state-resolved scattering dynamics at the gas-liquid interface are presented for experimental and theoretical studies of CO(2) + perfluorinated surfaces. Experimentally, high resolution absorption profiles are measured as a function of incident (θ(inc)) and scattering (θ(scat)) angles for CO(2) that has been scattered from a 300 K perfluorinated polyether surface (PFPE) with an incident energy of E(inc) = 10.6(8) kcal mol(-1). Line shape analysis of the absorption profiles reveals non-equilibrium dynamics that are characterized by trapping-desorption (TD) and impulsive scattering (IS) components, with each channel simply characterized by an effective "temperature" that compares very well with previous results from rotational state analysis [Perkins and Nesbitt, J. Phys. Chem. A, 2008, 112, 9324]. From a theoretical perspective, molecular dynamics (MD) simulations of CO(2) + fluorinated self-assembled monolayer surface (F-SAMs) yield translational probability distributions that are also compared with experimental results. Trajectories are parsed by θ(scat) and J, with the results rigorously corrected by flux-to-density transformation and providing comparisons in near quantitative agreement with experiment. 3D flux and velocity distributions obtained from MD simulations are also presented to illustrate the role of in- and out-of-plane scattering.

  19. Electrolyte distribution around two like-charged rods: their effective attractive interaction and angular dependent charge reversal.

    PubMed

    Jiménez-Angeles, Felipe; Odriozola, Gerardo; Lozada-Cassou, Marcelo

    2006-04-07

    A simple model for two like-charged parallel rods immersed in an electrolyte solution is considered. We derived the three point extension (TPE) of the hypernetted chain/mean spherical approximation (TPE-HNC/MSA) and Poisson-Boltzmann (TPE-PB) integral equations. We numerically solve these equations and compare them to our results of Monte Carlo (MC) simulations. The effective interaction force, F(T), the charge distribution profiles, rho(el)(x,y), and the angular dependent integrated charge function, P(theta), are calculated for this system. The analysis of F(T) is carried out in terms of the electrostatic and entropic (depletion) contributions, F(E) and F(C). We studied several cases of monovalent and divalent electrolytes, for which the ionic size and concentration are varied. We find good qualitative agreement between TPE-HNC/MSA and MC in all the cases studied. The rod-rod force is found to be attractive when immersed in large size, monovalent or divalent electrolytes. In general, the TPE-PB has poor agreement with the MC. For large monovalent and divalent electrolytes, we find angular dependent charge reversal charge inversion and polarizability. We discuss the intimate relationship between this angular dependent charge reversal and rod-rod attraction.

  20. Fragment Angular Distributions in Neutron-Induced Fission of {sup 235}U and {sup 239}Pu using a Time Projection Chamber

    SciTech Connect

    Kleinrath, Verena

    2015-07-01

    Fission fragment angular distributions can lend insights into fission barrier shapes and level densities at the scission point, both important for fission theory development. Fragment emission anisotropies are also valuable for precision cross section ratio measurements, if the distributions are different for the two isotopes used in the ratio. Available angular data is sparse for {sup 235}U and even more so for {sup 239}Pu, especially at neutron energies above 5 MeV. The Neutron Induced Fission Fragment Tracking Experiment (NIFFTE) time projection chamber, which enables precise tracking of charged particles, can be used to study angular distributions and emission anisotropies of fission fragments in neutron-induced fission. In-beam data collected at the Los Alamos Neutron Science Center with a {sup 235}U/{sup 239}Pu target during the 2014 run-cycle will provide angular distributions as a function of incident neutron energy for these isotopes. (LA-UR-1426972). (authors)

  1. Mixed optical Cherenkov-Bremsstrahlung radiation in vicinity of the Cherenkov cone from relativistic heavy ions: Unusual dependence of the angular distribution width on the radiator thickness

    NASA Astrophysics Data System (ADS)

    Rozhkova, E. I.; Pivovarov, Yu. L.

    2016-07-01

    The Cherenkov radiation (ChR) angular distribution is usually described by the Tamm-Frank (TF) theory, which assumes that relativistic charged particle moves uniformly and rectilinearly in the optically transparent radiator. According to the TF theory, the full width at half maximum (FWHM) of the ChR angular distribution inversely depends on the radiator thickness. In the case of relativistic heavy ions (RHI) a slowing-down in the radiator may sufficiently change the angular distribution of optical radiation in vicinity of the Cherenkov cone, since there appears a mixed ChR-Bremsstrahlung radiation. As a result, there occurs a drastic transformation of the FWHM of optical radiation angular distribution in dependence on the radiator thickness: from inversely proportional (TF theory) to the linearly proportional one. In our paper we present the first analysis of this transformation taking account of the gradual velocity decrease of RHI penetrating through a radiator.

  2. EarthShadow: Calculator for dark matter particle velocity distribution after Earth-scattering

    NASA Astrophysics Data System (ADS)

    Kavanagh, Bradley; Catena, Riccardo; Kouvaris, Chris

    2016-11-01

    EarthShadow calculates the impact of Earth-scattering on the distribution of Dark Matter (DM) particles. The code calculates the speed and velocity distributions of DM at various positions on the Earth and also helps with the calculation of the average scattering probabilities. Tabulated data for DM-nuclear scattering cross sections and various numerical results, plots and animations are also included in the code package.

  3. Intensity distribution and impact of scatter for dual-source CT

    NASA Astrophysics Data System (ADS)

    Kyriakou, Yiannis; Kalender, Willi A.

    2007-12-01

    Apart from forward scatter, which is given for all CT scanners, dual-source CT (DSCT) is also affected by cross-scatter photons from the second tube-detector system arranged at 90°. We investigated the magnitude and distribution of scatter for DSCT and its impact on image quality. Simulations and measurements of homogeneous and anthropomorphic phantoms were conducted for a DSCT scanner (SOMATOM Definition, Siemens Medical Solutions, Forchheim, Germany) at tube voltages of 80 and 120 kV. The simulations of forward scatter were carried out using combined analytical and Monte Carlo simulation methods for a collimation of 19.2 mm for both tube-detector systems. Measurements of cross scatter were performed by switching one tube off, still reading out the corresponding detector. The relative scatter fractions and the distribution of cross scatter were registered for various imaging conditions. Additionally, a detailed noise analysis with respect to the correction of cross-scatter artifacts is provided to evaluate the performance of correction algorithms. The forward-scatter fraction increased with increasing phantom diameter from 0.02 up to 0.11 for PMMA phantoms of 80 to 400 mm diameter. For cross scatter, the mean intensity was equivalent to forward scatter for small phantoms but was larger for increased phantom size and resulted in severe artifacts in the reconstructed images. The outer dimensions and shape of the object are decisive for the cross-scatter intensity distribution whereas the influence of the degree of inhomogeneity of the respective phantom appears to be negligible. Scatter correction suppressed cross-scatter artifacts but increased noise as a function of the cross-scatter fraction. The magnitude of scatter is not negligible for DSCT systems and dedicated corrections are necessary for the assurance of unimpaired image quality.

  4. A measurement of the angular distribution of the diffuse optical transmittance of etched nuclear tracks in CR-39

    SciTech Connect

    Vázquez-López, C.; Zendejas-Leal, B. E.; Bogard, James S; Golzarri, J. I.; Espinosa Garcia, Guillermo

    2009-01-01

    This paper presents a device to measure the angular distribution of the diffuse optical transmittance produced by etched nuclear tracks in polyallyl diglycol carbonate (PADC) detector. The device makes use of a stepper motor to move an array of four photodetectors around the sample in 1.8-degree steps. The integrated transmitted light was observed to increase monotonically with the etched track density in a range from zero to 2.8 x 10^5 per cm^2, using a neutron Am Be source.

  5. Partial cross sections and angular distributions of resonant and nonresonant valence photoemission of C{sub 60}

    SciTech Connect

    Korica, Sanja; Rolles, Daniel; Reinkoester, Axel; Viefhaus, Jens; Cvejanovic, Slobodan; Becker, Uwe; Langer, Burkhard

    2005-01-01

    We have performed high-resolution measurements of photoelectrons emitted from the valence shell of C{sub 60}, for both gas phase and solid state, in order to obtain branching ratios, partial cross sections, and the angular distribution anisotropy parameters of the two highest occupied molecular orbitals. The analysis is based on the Fourier transform of the cross-section oscillations and the results are corroborated by different theoretical models. In contrast to this good overall agreement between theory and experiment there is a striking disagreement with respect to predicted discrete resonance structures in the partial cross sections. Possible reasons for this behavior are discussed.

  6. Angular distortion and through-thickness residual stress distribution in the friction-stir processed 6061-T6 aluminum alloy

    SciTech Connect

    Woo, Wan Chuck; Choo, Hahn; Brown, D. W.; Feng, Zhili; Liaw, Peter K; Hubbard, Camden R

    2006-01-01

    Residual stresses were measured through the thickness of friction-stir processed (FSP) 6061-T6 aluminum-alloy plates using neutron diffraction. Two different specimens were prepared to study the relationship between residual stress distributions through the thickness of the plate and angular distortion: (Case 1) a plate processed with both stirring pin and tool shoulder, i.e., a typical FSP plate subjected to both plastic deformation and frictional heat, and (Case 2) a plate processed only with the tool shoulder, i.e., subjected mainly to the frictional heating. The measured residual stress profiles show relatively small through-thickness residual stress variations in Case 1, while there is a significant through-thickness residual stress variations in Case 2. The main cause of the geometric angular distortion could be related to the non-uniform distribution of the frictional heat generated by the tool shoulder leading to the asymmetric distributions of the residual stress through the thickness of the FSP plate.

  7. Scattering of electromagnetic waves from a half-space of randomly distributed discrete scatterers and polarized backscattering ratio law

    NASA Technical Reports Server (NTRS)

    Zhu, P. Y.

    1991-01-01

    The effective-medium approximation is applied to investigate scattering from a half-space of randomly and densely distributed discrete scatterers. Starting from vector wave equations, an approximation, called effective-medium Born approximation, a particular way, treating Green's functions, and special coordinates, of which the origin is set at the field point, are used to calculate the bistatic- and back-scatterings. An analytic solution of backscattering with closed form is obtained and it shows a depolarization effect. The theoretical results are in good agreement with the experimental measurements in the cases of snow, multi- and first-year sea-ice. The root product ratio of polarization to depolarization in backscattering is equal to 8; this result constitutes a law about polarized scattering phenomena in the nature.

  8. Analysis of scattering statistics and governing distribution functions in optical coherence tomography

    PubMed Central

    Sugita, Mitsuro; Weatherbee, Andrew; Bizheva, Kostadinka; Popov, Ivan; Vitkin, Alex

    2016-01-01

    The probability density function (PDF) of light scattering intensity can be used to characterize the scattering medium. We have recently shown that in optical coherence tomography (OCT), a PDF formalism can be sensitive to the number of scatterers in the probed scattering volume and can be represented by the K-distribution, a functional descriptor for non-Gaussian scattering statistics. Expanding on this initial finding, here we examine polystyrene microsphere phantoms with different sphere sizes and concentrations, and also human skin and fingernail in vivo. It is demonstrated that the K-distribution offers an accurate representation for the measured OCT PDFs. The behavior of the shape parameter of K-distribution that best fits the OCT scattering results is investigated in detail, and the applicability of this methodology for biological tissue characterization is demonstrated and discussed. PMID:27446689

  9. Development of Multi-Field of view-Multiple-Scattering-Polarization Lidar : analysis of angular resolved backscattered signals

    NASA Astrophysics Data System (ADS)

    Makino, T.; Okamoto, H.; Sato, K.; Tanaka, K.; Nishizawa, T.; Sugimoto, N.; Matsui, I.; Jin, Y.; Uchiyama, A.; Kudo, R.

    2014-12-01

    We have developed a new type of ground-based lidar, Multi-Field of view-Multiple-Scattering-Polarization Lidar (MFMSPL), to analyze multiple scattering contribution due to low-level clouds. One issue of the ground based lidar is the limitation of optical thickness of about 3 due to the strong attenuation in the lidar signals so that only the cloud bottom part can be observed. In order to overcome the problem, we have proposed the MFMSPL that has been designed to observe similar degree of multiple scattering contribution expected from space-borne lidar CALIOP on CALIPSO satellite. The system consists of eight detectors; four telescopes for parallel channels and four for perpendicular channels. The four pairs of telescope have been mounted with four different off-beam angles, ranging from -5 to 35mrad, where the angle is defined as the one between the direction of laser beam and the direction of telescope. Consequently, similar large foot print (100m) as CALIOP can be achieved in the MFMSPL observations when the altitude of clouds is located at about 1km. The use of multi-field of views enables to measure depolarization ratio from optically thick clouds. The outer receivers attached with larger angles generally detect backscattered signals from clouds located at upper altitudes due to the enhanced multiple scattering compared with the inner receiver that detects signals only from cloud bottom portions. Therefore the information of cloud microphysics from optically thicker regions is expected by the MFMSPL observations compared with the conventional lidar with small FOV. The MFMSPL have been continuously operated in Tsukuba, Japan since June 2014.Initial analyses have indicated expected performances from the theoretical estimation by backward Monte-Carlo simulations. The depolarization ratio from deeper part of the clouds detected by the receiver with large off-beam angle showed much larger values than those from the one with small angle. The calibration procedures

  10. Pion production via proton synchrotron radiation in strong magnetic fields in relativistic field theory: Scaling relations and angular distributions

    SciTech Connect

    Maruyama, Tomoyuki; Cheoun, Myung-Ki; Kajino, Toshitaka; Mathews, Grant J.

    2016-03-26

    We study pion production by proton synchrotron radiation in the presence of a strong magnetic field when the Landau numbers of the initial and final protons are n(i, f) similar to 10(4)-10(5). We find in our relativistic field theory calculations that the pion decay width depends only on the field strength parameter which previously was only conjectured based upon semi-classical arguments. Moreover, we also find new results that the decay width satisfies a robust scaling relation, and that the polar angular distribution of emitted pion momenta is very narrow and can be easily obtained. This scaling implies that one can infer the decay width in more realistic magnetic fields of 10(15) G, where n(i, f) similar to 10(12)-10(13), from the results for n(i, f) similar to 10(4)-10(5). The resultant pion intensity and angular distributions for realistic magnetic field strengths are presented and their physical implications discussed. (C) 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP(3).

  11. Fission Fragment Angular Distribution measurements of 235U and 238U at CERN n_TOF facility

    NASA Astrophysics Data System (ADS)

    Leal-Cidoncha, E.; Durán, I.; Paradela, C.; Tarrío, D.; Leong, L. S.; Tassan-Got, L.; Audouin, L.; Altstadt, S.; Andrzejewski, J.; Barbagallo, M.; Bécares, V.; Bečvář, F.; Belloni, F.; Berthoumieux, E.; Billowes, J.; Boccone, V.; Bosnar, D.; Brugger, M.; Calviani, M.; Calviño, F.; Cano-Ott, D.; Carrapiço, C.; Cerutti, F.; Chiaveri, E.; Chin, M.; Colonna, N.; Cortés, G.; Cortés-Giraldo, M. A.; Diakaki, M.; Domingo-Pardo, C.; Dressler, R.; Dzysiuk, N.; Eleftheriadis, C.; Ferrari, A.; Fraval, K.; Ganesan, S.; García, A. R.; Giubrone, G.; Gómez-Hornillos, M. B.; Gonçalves, I. F.; González-Romero, E.; Griesmayer, E.; Guerrero, C.; Gunsing, F.; Gurusamy, P.; Hernández-Prieto, A.; Jenkins, D. G.; Jericha, E.; Kadi, Y.; Käppeler, F.; Karadimos, D.; Kivel, N.; Koehler, P.; Kokkoris, M.; Krtička, M.; Kroll, J.; Lampoudis, C.; Langer, C.; Lederer, C.; Leeb, H.; Lo Meo, S.; Losito, R.; Mallick, A.; Manousos, A.; Marganiec, J.; Martínez, T.; Massimi, C.; Mastinu, P. F.; Mastromarco, M.; Meaze, M.; Mendoza, E.; Mengoni, A.; Milazzo, P. M.; Mingrone, F.; Mirea, M.; Mondelaers, W.; Pavlik, A.; Perkowski, J.; Plompen, A.; Praena, J.; Quesada, J. M.; Rauscher, T.; Reifarth, R.; Riego, A.; Robles, M. S.; Roman, F.; Rubbia, C.; Sabaté-Gilarte, M.; Sarmento, R.; Saxena, A.; Schillebeeckx, P.; Schmidt, S.; Schumann, D.; Tagliente, G.; Tain, J. L.; Tsinganis, A.; Valenta, S.; Vannini, G.; Variale, V.; Vaz, P.; Ventura, A.; Versaci, R.; Vermeulen, M. J.; Vlachoudis, V.; Vlastou, R.; Wallner, A.; Ware, T.; Weigand, M.; Weiß, C.; Wright, T.; Žugec, P.

    2016-03-01

    Neutron-induced fission cross sections of 238U and 235U are used as standards in the fast neutron region up to 200 MeV. A high accuracy of the standards is relevant to experimentally determine other neutron reaction cross sections. Therefore, the detection effciency should be corrected by using the angular distribution of the fission fragments (FFAD), which are barely known above 20 MeV. In addition, the angular distribution of the fragments produced in the fission of highly excited and deformed nuclei is an important observable to investigate the nuclear fission process. In order to measure the FFAD of neutron-induced reactions, a fission detection setup based on parallel-plate avalanche counters (PPACs) has been developed and successfully used at the CERN-n_TOF facility. In this work, we present the preliminary results on the analysis of new 235U(n,f) and 238U(n,f) data in the extended energy range up to 200 MeV compared to the existing experimental data.

  12. Calculations of the anisotropy of the fission fragment angular distribution and neutron emission multiplicities prescission from Langevin dynamics

    SciTech Connect

    Jia Ying; Bao Jingdong

    2007-03-15

    The anisotropy of the fission fragment angular distribution defined at the saddle point and the neutron multiplicities emitted prior to scission for fissioning nuclei {sup 224}Th, {sup 229}Np, {sup 248}Cf, and {sup 254}Fm are calculated simultaneously by using a set of realistic coupled two-dimensional Langevin equations, where the (c,h,{alpha}=0) nuclear parametrization is employed. In comparison with the one-dimensional stochastic model without neck variation, our two-dimensional model produces results that are in better agreement with the experimental data, and the one-dimensional model is available only for low excitation energies. Indeed, to determine the temperature of the nucleus at the saddle point, we investigate the neutron emission during nucleus oscillation around the saddle point for different friction mechanisms. It is shown that the neutrons emitted during the saddle oscillation cause the temperature of a fissioning nuclear system at the saddle point to decrease and influence the fission fragment angular distribution.

  13. Photoelectron angular distributions for states of any mixed character: an experiment-friendly model for atomic, molecular, and cluster anions.

    PubMed

    Khuseynov, Dmitry; Blackstone, Christopher C; Culberson, Lori M; Sanov, Andrei

    2014-09-28

    We present a model for laboratory-frame photoelectron angular distributions in direct photodetachment from (in principle) any molecular orbital using linearly polarized light. A transparent mathematical approach is used to generalize the Cooper-Zare central-potential model to anionic states of any mixed character. In the limit of atomic-anion photodetachment, the model reproduces the Cooper-Zare formula. In the case of an initial orbital described as a superposition of s and p-type functions, the model yields the previously obtained s-p mixing formula. The formalism is further advanced using the Hanstorp approximation, whereas the relative scaling of the partial-wave cross-sections is assumed to follow the Wigner threshold law. The resulting model describes the energy dependence of photoelectron anisotropy for any atomic, molecular, or cluster anions, usually without requiring a direct calculation of the transition dipole matrix elements. As a benchmark case, we apply the p-d variant of the model to the experimental results for NO(-) photodetachment and show that the observed anisotropy trend is described well using physically meaningful values of the model parameters. Overall, the presented formalism delivers insight into the photodetachment process and affords a new quantitative strategy for analyzing the photoelectron angular distributions and characterizing mixed-character molecular orbitals using photoelectron imaging spectroscopy of negative ions.

  14. Pion production via proton synchrotron radiation in strong magnetic fields in relativistic field theory: Scaling relations and angular distributions

    DOE PAGES

    Maruyama, Tomoyuki; Cheoun, Myung-Ki; Kajino, Toshitaka; ...

    2016-03-26

    We study pion production by proton synchrotron radiation in the presence of a strong magnetic field when the Landau numbers of the initial and final protons are n(i, f) similar to 10(4)-10(5). We find in our relativistic field theory calculations that the pion decay width depends only on the field strength parameter which previously was only conjectured based upon semi-classical arguments. Moreover, we also find new results that the decay width satisfies a robust scaling relation, and that the polar angular distribution of emitted pion momenta is very narrow and can be easily obtained. This scaling implies that one canmore » infer the decay width in more realistic magnetic fields of 10(15) G, where n(i, f) similar to 10(12)-10(13), from the results for n(i, f) similar to 10(4)-10(5). The resultant pion intensity and angular distributions for realistic magnetic field strengths are presented and their physical implications discussed. (C) 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP(3).« less

  15. Application of Heisenberg's S matrix program to the angular scattering of the state-to-state F + H2 reaction.

    PubMed

    Shan, Xiao; Connor, J N L

    2014-08-21

    This paper makes two applications of Heisenberg's S matrix program (HSMP) to the differential cross section (DCS) of the benchmark reaction F + H2(vi = 0, ji = 0, mi = 0) → FH(vf = 3, jf = 3, mf = 0) + H, at a relative translational energy of 0.119 eV (total energy, 0.3872 eV), where v, j, m are vibrational, rotational, and helicity quantum numbers, respectively, for the initial and final states. (1) The first application employs a "weak" version of HSMP in which no potential energy surface (PES) is employed. It uses four simple S matrix parametrizations, two of which are piecewise continuous, and two are piecewise discontinuous, developed earlier by X. Shan and J. N. L. Connor (J. Phys. Chem. A 2012, 116, 11414-11426) for the state-to-state H + D2 reaction. We find that the small-angle DCS is reproduced for only θR ≲ 10° when compared with the DCS for a numerical S matrix obtained in a large-scale quantum scattering computation using a PES. Here θR is the reactive scattering angle. (2) In our second application, we ask the question "Can simple modifications to the parametrized S matrix be made in order to extend the agreement to larger angles?" To answer this question, we adopt a "hybrid" version of HSMP, as outlined by Shan and Connor (Phys. Chem. Chem. Phys. 2011, 13, 8392-8406), which indirectly uses PES information. We make simple Gaussian-type modifications to both the modulus and argument of the S matrix. We then obtain agreement between the DCSs for the modified and numerical S matrices up to θR ≲ 70°, a significant improvement compared with θR ≲ 10° for the unmodified parametrizations. We find that modifying the argument but not the modulus, or modifying the modulus but not the argument, fails to extend the agreement to larger angles. A semiclassical analysis is used to prove that the enhanced small-angle scattering for the "modified-modulus-modified-argument" parametrized S matrix is an example of a forward glory.

  16. Solar Wind Halo Formation by the Scattering of the Strahl via Direct Cluster/PEACE Observations of the 3D Velocity Distribution Function

    NASA Technical Reports Server (NTRS)

    Figueroa-Vinas, Adolfo; Gurgiolo, Chris A.; Nieves-Chinchilla, Teresa; Goldstein, Melvyn L.

    2010-01-01

    It has been suggested by a number of authors that the solar wind electron halo can be formed by the scattering of the strahl. On frequent occasions we have observed in electron angular skymaps (Phi/Theta-plots) of the electron 3D velocity distribution functions) a bursty-filament of particles connecting the strahl to the solar wind core-halo. These are seen over a very limited energy range. When the magnetic field is well off the nominal solar wind flow direction such filaments are inconsistent with any local forces and are probably the result of strong scattering. Furthermore, observations indicates that the strahl component is frequently and significantly anisotropic (Tper/Tpal approx.2). This provides a possible free energy source for the excitation of whistler waves as a possible scattering mechanism. The empirical observational evidence between the halo and the strahl suggests that the strahl population may be, at least in part, the source of the halo component.

  17. On The Distribution Of Angular Orbital Elements Of Near-earth Objects

    NASA Astrophysics Data System (ADS)

    JeongAhn, Youngmin; Malhotra, R.

    2012-05-01

    The longitude of ascending node Ω and the argument of periapsis ω are expected to be randomly distributed for near-Earth objects (NEOs). However, the distribution of these angles for the Apollo, Amor and Aten subclasses, considered separately, shows some striking non-random features. We explain how these features arise due to observational biases. The distribution of Ω has maxima near 0 and 180° and is affected by observational difficulty due to the galactic plane at the opposition and other seasonal effects. The ω distributions of Aten and Amor subclasses have minima at 90° and 270° while Apollos have minima at 0 and 180°. This is explained by the greater detectability of NEOs at close approach to Earth. The longitude of perihelion Ω+ω also has a strongly non-random distribution that may be owed to actual dynamical effects. Understanding the distribution of unobserved NEOs will help to improve planning for the next generation of NEO surveys. A better understanding of the intrinsic distribution of NEOs is important for estimating the impact hazard at Earth; it is also important for understanding the impact history of the Moon and the terrestrial planets.

  18. Measurements of Branching Fractions and CP Asymmetries and Studies of Angular Distributions for B to phi phi K Decays

    SciTech Connect

    Lees, J.P.; Poireau, V.; Prencipe, E.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Martinelli, M.; Milanes, D.A.; Palano, A.; Pappagallo, M.; Eigen, G.; Stugu, B.; Sun, L.; Brown, D.N.; Kerth, L.T.; Kolomensky, Yu.G.; Lynch, G.; Koch, H.; Schroeder, T.; Asgeirsson, D.J.; Hearty, C.; /British Columbia U. /Brunel U. /Novosibirsk, IYF /UC, Irvine /UC, Riverside /UC, Santa Barbara /UC, Santa Cruz /Caltech /Cincinnati U. /Colorado U. /Colorado State U. /Dortmund U. /Dresden, Tech. U. /Ecole Polytechnique /Edinburgh U. /INFN, Ferrara /INFN, Ferrara /Ferrara U. /INFN, Ferrara /Frascati /INFN, Genoa /Genoa U. /INFN, Genoa /INFN, Genoa /Genoa U. /INFN, Genoa /Indian Inst. Tech., Guwahati /Harvard U. /Harvey Mudd Coll. /Heidelberg U. /Humboldt U., Berlin /Imperial Coll., London /Iowa State U. /Iowa State U. /Johns Hopkins U. /Paris U., VI-VII /LLNL, Livermore /Liverpool U. /Queen Mary, U. of London /Royal Holloway, U. of London /Royal Holloway, U. of London /Louisville U. /Mainz U., Inst. Kernphys. /Manchester U. /Maryland U. /Massachusetts U., Amherst /MIT /McGill U. /INFN, Milan /Milan U. /INFN, Milan /INFN, Milan /Milan U. /Mississippi U. /Montreal U. /INFN, Naples /Naples U. /NIKHEF, Amsterdam /NIKHEF, Amsterdam /Notre Dame U. /Ohio State U. /Oregon U. /INFN, Padua /Padua U. /INFN, Padua /INFN, Padua /Padua U. /Paris U., VI-VII /INFN, Perugia /Perugia U. /INFN, Pisa /Pisa U. /INFN, Pisa /Pisa, Scuola Normale Superiore /INFN, Pisa /Pisa U. /INFN, Pisa /INFN, Pisa /Pisa U. /INFN, Pisa /Princeton U. /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /Rostock U. /Rutherford /DAPNIA, Saclay /SLAC /South Carolina U. /Southern Methodist U. /Stanford U., Phys. Dept. /SUNY, Albany /Tel Aviv U. /Tennessee U. /Texas Nuclear Corp., Austin /Texas U., Dallas /INFN, Turin /Turin U. /INFN, Trieste /Trieste U. /Valencia U. /Victoria U. /Warwick U. /Wisconsin U., Madison

    2011-08-15

    We present branching fraction and CP asymmetry measurements as well as angular studies of B {yields} {phi}{phi}K decays using 464 x 10{sup 6} B{bar B} events collected by the BABAR experiment. The branching fractions are measured in the {phi}{phi} invariant mass range below the {eta}{sub c} resonance (m{sub {phi}{phi}} < 2.85 GeV). We find {Beta}(B{sup +} {yields} {phi}{phi}K{sup +}) = (5.6 {+-} 0.5 {+-} 0.3) x 10{sup -6} and {Beta}(B{sup 0} {yields} {phi}{phi}K{sup 0}) = (4.5 {+-} 0.8 {+-} 0.3) x 10{sup -6}, where the first uncertaintiy is statistical and the second systematic. The measured direct CP asymmetries for the B{sup {+-}} decays are A{sub CP} = -0.10 {+-} 0.08 {+-} 0.02 below the {eta}{sub c} threshold (m{sub {phi}{phi}} < 2.85 GeV) and A{sub CP} = 0.09 {+-} 0.10 {+-} 0.02 in the {eta}{sub c} resonance region (m{sub {phi}{phi}} in [2.94,3.02] GeV). Angular distributions are consistent with J{sub P} = 0{sup -} in the {eta}{sub c} resonance region and favor J{sup P} = 0{sup +} below the {eta}{sub c} resonance.

  19. Molecular Frame Photoelectron Angular Distributions for Core Ionization of CF4 and C2H2F2

    NASA Astrophysics Data System (ADS)

    Trevisan, C. S.; Williams, J. B.; Menssen, A. J.; Rescigno, T. N.; Dorner, R.; McCurdy, C. W.

    2015-05-01

    We present experimental and theoretical results for the angular dependence of electrons ejected from the core orbitals of tetrafluoromethane (CF4) which display a tendency to avoid molecular bonds if averaged over directions of polarization of the incident X-ray beam, in contrast to earlier cases (CH4, H2O and NH3) studied by the same methods. To investigate whether the imaging effect can be used to detect the creation of core holes by photoionization from one of two atoms of the same type in a molecule, we computed and measured MFPADs of difluoroethylene (C2H2F2). Good agreement with the experimentally measured angular distributions show that the MFPADs contain the clear signature of the core-hole origin of the photoelectron, and validate the use of computed MFPADs as promising tools for the interpretation of such experiments. Our measurements employ the COLTRIMS method and the calculations were performed with the Complex Kohn Variational method. Work supported in part by the USDOE, Office of Science, Office of WDTS under the Visiting Faculty Program.

  20. The Angular Momentum Distribution and Baryon Content of Star-forming Galaxies at z ˜ 1-3

    NASA Astrophysics Data System (ADS)

    Burkert, A.; Förster Schreiber, N. M.; Genzel, R.; Lang, P.; Tacconi, L. J.; Wisnioski, E.; Wuyts, S.; Bandara, K.; Beifiori, A.; Bender, R.; Brammer, G.; Chan, J.; Davies, R.; Dekel, A.; Fabricius, M.; Fossati, M.; Kulkarni, S.; Lutz, D.; Mendel, J. T.; Momcheva, I.; Nelson, E. J.; Naab, T.; Renzini, A.; Saglia, R.; Sharples, R. M.; Sternberg, A.; Wilman, D.; Wuyts, E.

    2016-08-01

    We analyze the angular momenta of massive star-forming galaxies (SFGs) at the peak of the cosmic star formation epoch (z ˜ 0.8-2.6). Our sample of ˜360 log(M */M ⊙) ˜ 9.3-11.8 SFGs is mainly based on the KMOS3D and SINS/zC-SINF surveys of Hα kinematics, and collectively provides a representative subset of the massive star-forming population. The inferred halo scale angular momentum distribution is broadly consistent with that theoretically predicted for their dark matter halos, in terms of mean spin parameter < λ > ˜ 0.037 and its dispersion (σ logλ ˜ 0.2). Spin parameters correlate with the disk radial scale and with their stellar surface density, but do not depend significantly on halo mass, stellar mass, or redshift. Our data thus support the long-standing assumption that on average, even at high redshifts, the specific angular momentum of disk galaxies reflects that of their dark matter halos (j d = j DM). The lack of correlation between λ × (j d /j DM) and the nuclear stellar density Σ*(1 kpc) favors a scenario where disk-internal angular momentum redistribution leads to “compaction” inside massive high-redshift disks. For our sample, the inferred average stellar to dark matter mass ratio is ˜2%, consistent with abundance matching results. Including the molecular gas, the total baryonic disk to dark matter mass ratio is ˜5% for halos near 1012 M ⊙, which corresponds to 31% of the cosmologically available baryons, implying that high-redshift disks are strongly baryon dominated. Based on observations obtained at the Very Large Telescope of the European Southern Observatory, Paranal, Chile (ESO Programme IDs 075.A-0466, 076.A-0527, 079.A-0341, 080.A-0330, 080.A-0339, 080.A-0635, 081.B-0568, 081.A-0672, 082.A-0396, 183.A-0781, 087.A-0081, 088.A-0202, 088.A-0209, 091.A-0126, 092.A-0091, 093.A-0079, 094.A-0217, 095.A-0047, 096.A-0025).

  1. 1 Tbit/inch2 Recording in Angular-Multiplexing Holographic Memory with Constant Signal-to-Scatter Ratio Schedule

    NASA Astrophysics Data System (ADS)

    Hosaka, Makoto; Ishii, Toshiki; Tanaka, Asato; Koga, Shogo; Hoshizawa, Taku

    2013-09-01

    We developed an iterative method for optimizing the exposure schedule to obtain a constant signal-to-scatter ratio (SSR) to accommodate various recording conditions and achieve high-density recording. 192 binary images were recorded in the same location of a medium in approximately 300×300 µm2 using an experimental system embedded with a blue laser diode with a 405 nm wavelength and an objective lens with a 0.85 numerical aperture. The recording density of this multiplexing corresponds to 1 Tbit/in.2. The recording exposure time was optimized through the iteration of a three-step sequence consisting of total reproduced intensity measurement, target signal calculation, and recording energy density calculation. The SSR of pages recorded with this method was almost constant throughout the entire range of the reference beam angle. The signal-to-noise ratio of the sampled pages was over 2.9 dB, which is higher than the reproducible limit of 1.5 dB in our experimental system.

  2. Angular distributions of electrons of energy E sub e greater than 0.06 MeV in the Jovian magnetosphere

    NASA Technical Reports Server (NTRS)

    Sentman, D. D.; Vanallen, J. A.

    1975-01-01

    The results of an angular distribution analysis of the electron intensity data recorded near Jupiter for the period from 26 November to 14 December 1973 are presented. The data were from three directional particle detectors with effective integral electron energy thresholds of 0.06, 0.55, and 5.0 Mev, respectively. It was found that the central core of the magnetosphere, within 12 Jupiter radii, is dominated by pitch angle distributions strongly peaked at alpha = 90 deg, while the region from 12 to 25 Jupiter radii shows bidirectional and approximately equal maxima at alpha = 0 and 180 deg. Bidirectional angular distributions in the magnetodisc out to the radius of the magnetopause strongly suggest quasi-trapping on closed field lines as the predominant situation. Substantial field aligned, unidirectional streaming was detected on only two occasions. No distinctive effects on angular distributions were discerned near the L-shells of satellites.

  3. Two-photon state selection and angular momentum polarization probed by velocity map imaging: Application to H atom photofragment angular distributions from the photodissociation of two-photon state selected HCl and HBr

    SciTech Connect

    Manzhos, Sergei; Romanescu, Constantin; Loock, Hans-Peter; Underwood, Jonathan G.

    2004-12-15

    A formalism for calculating the angular momentum polarization of an atom or a molecule following two-photon excitation of a J-selected state is presented. This formalism is used to interpret the H atom photofragment angular distributions from single-photon dissociation of two-photon rovibronically state selected HCl and HBr prepared via a Q-branch transition. By comparison of the angular distributions measured using the velocity map imaging technique with the theoretical model it is shown that single-photon dissociation of two-photon prepared states can be used for pathway identification, allowing for the identification of the virtual state symmetry in the two-photon absorption and/or the symmetry of the dissociative state. It is also shown that under conditions of excitation with circularly polarized light, or for excitation via non-Q-branch transitions with linearly polarized light the angular momentum polarization is independent of the dynamics of the two-photon transition and analytically computable.

  4. Two-photon state selection and angular momentum polarization probed by velocity map imaging: application to H atom photofragment angular distributions from the photodissociation of two-photon state selected HCl and HBr.

    PubMed

    Manzhos, Sergei; Romanescu, Constantin; Loock, Hans-Peter; Underwood, Jonathan G

    2004-12-15

    A formalism for calculating the angular momentum polarization of an atom or a molecule following two-photon excitation of a J-selected state is presented. This formalism is used to interpret the H atom photofragment angular distributions from single-photon dissociation of two-photon rovibronically state selected HCl and HBr prepared via a Q-branch transition. By comparison of the angular distributions measured using the velocity map imaging technique with the theoretical model it is shown that single-photon dissociation of two-photon prepared states can be used for pathway identification, allowing for the identification of the virtual state symmetry in the two-photon absorption and/or the symmetry of the dissociative state. It is also shown that under conditions of excitation with circularly polarized light, or for excitation via non-Q-branch transitions with linearly polarized light the angular momentum polarization is independent of the dynamics of the two-photon transition and analytically computable.

  5. Temporal Distributions of Problem Behavior Based on Scatter Plot Analysis.

    ERIC Educational Resources Information Center

    Kahng, SungWoo; Iwata, Brian A.; Fischer, Sonya M.; Page, Terry J.; Treadwell, Kimberli R. H.; Williams, Don E.; Smith, Richard G.

    1998-01-01

    A large-scale analysis was conducted of problem behavior by observing 20 individuals living in residential facilities. Data were converted into scatter plot formats. When the data were transformed into aggregate "control charts," 12 of 15 sets of data revealed 30-minute intervals during which problem behavior was more likely to occur.…

  6. Installation for the study of the angular distribution of cosmic muons with super-high energies at large zenith angles

    NASA Technical Reports Server (NTRS)

    Borog, V. V.; Kirillov-Ugryumov, V. G.; Petrukhin, A. A.; Shestakov, V. V.

    1975-01-01

    An installation consisting of an ionization calorimeter and a counter hodoscope can be used to record cascade showers caused by the electromagnetic interactions of muons with superhigh energies in the cosmic ray horizontal flux. The direction of the muons is determined by a hodoscope consisting of 2196 counters. The information obtained makes it possible to restore the angular and energy distribution of the cosmic muons, which, in turn, makes it possible to determine the mechanism of their generation. The accuracy with which the angle of the passing particle is determined is discussed in detail in addition to the causes which can introduce distortions, such as shower accompaniment of neutrons, escape of shower electrons from the calorimeter, random coincidences, etc.

  7. Three-Dimensional Model of the Scatterer Distribution in Cirrhotic Liver

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Tadashi; Nakamura, Keigo; Hachiya, Hiroyuki

    2003-05-01

    Ultrasonic B-mode images are affected by changes in scatterer distribution. It is hard to estimate the relationship between the ultrasonic image and the tissue structure quantitatively because we cannot observe the continuous stages of liver cirrhosis tissue clinically, particularly the beginning stage. In this paper, we propose a three-dimensional modeling method of scatterer distribution for normal and cirrhotic livers to confirm the influence of the change in the form of scatterer distribution on echo information. The algorithm of the method includes parameters which determine the expansion of nodules and fibers. Using the B-mode images which are obtained from these scatterer distributions, we analyze the relationship between the changes in the form of biological tissue and the changes in the B-mode images during progressive liver cirrhosis.

  8. Example of scattering noise in radar data interpretation

    SciTech Connect

    Canavan, G.H.

    1996-10-01

    Radar data interpretation typically assumes well behaved, known particle distributions. Those assumptions are at variance with the unknown angular scattering characteristics of the particles measured. This note gives a simple example of how those characteristics complicate data interpretation.

  9. Sensitivity of cross sections for elastic nucleus-nucleus scattering to halo nucleus density distributions

    SciTech Connect

    Alkhazov, G. D.; Sarantsev, V. V.

    2012-12-15

    In order to clear up the sensitivity of the nucleus-nucleus scattering to the nuclear matter distributions in exotic halo nuclei, we have calculated differential cross sections for elastic scattering of the {sup 6}He and {sup 11}Li nuclei on several nuclear targets at the energy of 0.8 GeV/nucleon with different assumed nuclear density distributions in {sup 6}He and {sup 11}Li.

  10. Angular distribution of atoms emitted from a SrZrO{sub 3} target by laser ablation under different laser fluences and oxygen pressures

    SciTech Connect

    Konomi, I.; Motohiro, T.; Azuma, H.; Asaoka, T.; Nakazato, T.; Sato, E.; Shimizu, T.; Fujioka, S.; Sarukura, N.; Nishimura, H.

    2010-05-15

    Angular distributions of atoms emitted by laser ablation of perovskite-type oxide SrZrO{sub 3} have been investigated using electron probe microanalysis with wavelength-dispersive spectroscopy and charge-coupled device photography with an interference filter. Each constituent element has been analyzed as a two-modal distribution composed of a broad cos{sup m} {theta} distribution and a narrow cos{sup n} {theta} distribution. The exponent n characterizes the component of laser ablation while the exponent m characterizes that of thermal evaporation, where a larger n or m means a narrower angular distribution. In vacuum, O (n=6) showed a broader distribution than those of Sr (n=16) and Zr (n=17), and Sr{sup +} exhibited a spatial distribution similar to that of Sr. As the laser fluence was increased from 1.1 to 4.4 J/cm{sup 2}, the angular distribution of Sr became narrower. In the laser fluence range of 1.1-4.4 J/cm{sup 2}, broadening of the angular distribution of Sr was observed only at the fluence of 1.1 J/cm{sup 2} under the oxygen pressure of 10 Pa. Monte Carlo simulations were performed to estimate approximately the energy of emitted atoms, focusing on the broadening of the angular distribution under the oxygen pressure of 10 Pa. The energies of emitted atoms were estimated to be 1-20 eV for the laser fluence of 1.1 J/cm{sup 2}, and more than 100 eV for 2.2 and 4.4 J/cm{sup 2}.

  11. Distributions of /sup 35/S-sulfate and /sup 3/H-glucosamine in the angular region of the hamster: light and electron microscopic autoradiography

    SciTech Connect

    Ohnishi, Y.; Taniguchi, Y.

    1983-06-01

    The distribution of /sup 35/S-sulfate and /sup 3/H-glucosamine in the angular region of the hamster was studied by light and electron microscopic autoradiography following intraperitoneal injection of these compounds to hamsters. Exposed silver grains of /sup 35/S-sulfate were concentrated in the trabecular meshwork, sclera, and cornea, and grains of /sup 3/H-glucosamine were localized in the trabecular region. The radioactivity of both isotopes was observed in the Golgi apparatuses of the endothelial cells of the angular aqueous plexus and the trabecular meshwork. The grains were noted over the entire cytoplasm, except for the nucleus, and then were incorporated into the amorphous substance and collagen fibers in the region adjacent to the angular aqueous sinus. These results suggest that endothelial cells in the angular region synthesize and secrete the sulfated glycosaminoglycans and hyaluronic acid.

  12. Measurements of the Angular Distributions of Muons from Υ Decays in pp̄ Collisions at √s=1.96 TeV

    SciTech Connect

    Aaltonen, T.; Álvarez González, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J. A.; Arisawa, T.; Artikov, A.; Asaadi, J.; Ashmanskas, W.; Auerbach, B.; Aurisano, A.; Azfar, F.; Badgett, W.; Bae, T.; Barbaro-Galtieri, A.; Barnes, V. E.; Barnett, B. A.; Barria, P.; Bartos, P.; Bauce, M.; Bedeschi, F.; Behari, S.; Bellettini, G.; Bellinger, J.; Benjamin, D.; Beretvas, A.; Bhatti, A.; Bisello, D.; Bizjak, I.; Bland, K. R.; Blumenfeld, B.; Bocci, A.; Bodek, A.; Bortoletto, D.; Boudreau, J.; Boveia, A.; Brigliadori, L.; Bromberg, C.; Brucken, E.; Budagov, J.; Budd, H. S.; Burkett, K.; Busetto, G.; Bussey, P.; Buzatu, A.; Calamba, A.; Calancha, C.; Camarda, S.; Campanelli, M.; Campbell, M.; Canelli, F.; Carls, B.; Carlsmith, D.; Carosi, R.; Carrillo, S.; Carron, S.; Casal, B.; Casarsa, M.; Castro, A.; Catastini, P.; Cauz, D.; Cavaliere, V.; Cavalli-Sforza, M.; Cerri, A.; Cerrito, L.; Chen, Y. C.; Chertok, M.; Chiarelli, G.; Chlachidze, G.; Chlebana, F.; Cho, K.; Chokheli, D.; Chung, W. H.; Chung, Y. S.; Ciocci, M. A.; Clark, A.; Clarke, C.; Compostella, G.; Convery, M. E.; Conway, J.; Corbo, M.; Cordelli, M.; Cox, C. A.; Cox, D. J.; Crescioli, F.; Cuevas, J.; Culbertson, R.; Dagenhart, D.; d’Ascenzo, N.; Datta, M.; de Barbaro, P.; Dell’Orso, M.; Demortier, L.; Deninno, M.; Devoto, F.; d’Errico, M.; Di Canto, A.; Di Ruzza, B.; Dittmann, J. R.; D’Onofrio, M.; Donati, S.; Dong, P.; Dorigo, M.; Dorigo, T.; Ebina, K.; Elagin, A.; Eppig, A.; Erbacher, R.; Errede, S.; Ershaidat, N.; Eusebi, R.; Farrington, S.; Feindt, M.; Fernandez, J. P.; Field, R.; Flanagan, G.; Forrest, R.; Frank, M. J.; Franklin, M.; Freeman, J. C.; Funakoshi, Y.; Furic, I.; Gallinaro, M.; Garcia, J. E.; Garfinkel, A. F.; Garosi, P.; Gerberich, H.; Gerchtein, E.; Giagu, S.; Giakoumopoulou, V.; Giannetti, P.; Gibson, K.; Ginsburg, C. M.; Giokaris, N.; Giromini, P.; Giurgiu, G.; Glagolev, V.; Glenzinski, D.; Gold, M.; Goldin, D.; Goldschmidt, N.; Golossanov, A.; Gomez, G.; Gomez-Ceballos, G.; Goncharov, M.; González, O.; Gorelov, I.; Goshaw, A. T.; Goulianos, K.; Grinstein, S.; Grosso-Pilcher, C.; Group, R. C.; Guimaraes da Costa, J.; Hahn, S. R.; Halkiadakis, E.; Hamaguchi, A.; Han, J. Y.; Happacher, F.; Hara, K.; Hare, D.; Hare, M.; Harr, R. F.; Hatakeyama, K.; Hays, C.; Heck, M.; Heinrich, J.; Herndon, M.; Hewamanage, S.; Hocker, A.; Hopkins, W.; Horn, D.; Hou, S.; Hughes, R. E.; Hurwitz, M.; Husemann, U.; Hussain, N.; Hussein, M.; Huston, J.; Introzzi, G.; Iori, M.; Ivanov, A.; James, E.; Jang, D.; Jayatilaka, B.; Jeon, E. J.; Jindariani, S.; Jones, M.; Joo, K. K.; Jun, S. Y.; Junk, T. R.; Kamon, T.; Karchin, P. E.; Kasmi, A.; Kato, Y.; Ketchum, W.; Keung, J.; Khotilovich, V.; Kilminster, B.; Kim, D. H.; Kim, H. S.; Kim, J. E.; Kim, M. J.; Kim, S. B.; Kim, S. H.; Kim, Y. K.; Kim, Y. J.; Kimura, N.; Kirby, M.; Klimenko, S.; Knoepfel, K.; Kondo, K.; Kong, D. J.; Konigsberg, J.; Kotwal, A. V.; Kreps, M.; Kroll, J.; Krop, D.; Kruse, M.; Krutelyov, V.; Kuhr, T.; Kurata, M.; Kwang, S.; Laasanen, A. T.; Lami, S.; Lammel, S.; Lancaster, M.; Lander, R. L.; Lannon, K.; Lath, A.; Latino, G.; LeCompte, T.; Lee, E.; Lee, H. S.; Lee, J. S.; Lee, S. W.; Leo, S.; Leone, S.; Lewis, J. D.; Limosani, A.; Lin, C.-J.; Lindgren, M.; Lipeles, E.; Lister, A.; Litvintsev, D. O.; Liu, C.; Liu, H.; Liu, Q.; Liu, T.; Lockwitz, S.; Loginov, A.; Lucchesi, D.; Lueck, J.; Lujan, P.; Lukens, P.; Lungu, G.; Lys, J.; Lysak, R.; Madrak, R.; Maeshima, K.; Maestro, P.; Malik, S.; Manca, G.; Manousakis-Katsikakis, A.; Margaroli, F.; Marino, C.; Martínez, M.; Mastrandrea, P.; Matera, K.; Mattson, M. E.; Mazzacane, A.; Mazzanti, P.; McFarland, K. S.; McIntyre, P.; McNulty, R.; Mehta, A.; Mehtala, P.; Mesropian, C.; Miao, T.; Mietlicki, D.; Mitra, A.; Miyake, H.; Moed, S.; Moggi, N.; Mondragon, M. N.; Moon, C. S.; Moore, R.; Morello, M. J.; Morlock, J.; Movilla Fernandez, P.; Mukherjee, A.; Muller, Th.; Murat, P.; Mussini, M.; Nachtman, J.; Nagai, Y.; Naganoma, J.; Nakano, I.; Napier, A.; Nett, J.; Neu, C.; Neubauer, M. S.; Nielsen, J.; Nodulman, L.; Noh, S. Y.; Norniella, O.; Oakes, L.; Oh, S. H.; Oh, Y. D.; Oksuzian, I.; Okusawa, T.; Orava, R.; Ortolan, L.; Pagan Griso, S.; Pagliarone, C.; Palencia, E.; Papadimitriou, V.; Paramonov, A. A.; Patrick, J.; Pauletta, G.; Paulini, M.; Paus, C.; Pellett, D. E.; Penzo, A.; Phillips, T. J.; Piacentino, G.; Pianori, E.; Pilot, J.; Pitts, K.; Plager, C.; Pondrom, L.; Poprocki, S.; Potamianos, K.; Prokoshin, F.; Pranko, A.; Ptohos, F.; Punzi, G.; Rahaman, A.; Ramakrishnan, V.; Ranjan, N.; Redondo, I.; Renton, P.; Rescigno, M.; Riddick, T.; Rimondi, F.; Ristori, L.; Robson, A.; Rodrigo, T.; Rodriguez, T.; Rogers, E.; Rolli, S.; Roser, R.; Ruffini, F.; Ruiz, A.; Russ, J.; Rusu, V.; Safonov, A.; Sakumoto, W. K.; Sakurai, Y.; Santi, L.; Sato, K.; Saveliev, V.; Savoy-Navarro, A.; Schlabach, P.; Schmidt, A.; Schmidt, E. E.; Schwarz, T.; Scodellaro, L.; Scribano, A.; Scuri, F.; Seidel, S.; Seiya, Y.; Semenov, A.; Sforza, F.; Shalhout, S. Z.; Shears, T.; Shepard, P. F.; Shimojima, M.; Shochet, M.; Shreyber-Tecker, I.; Simonenko, A.; Sinervo, P.; Sliwa, K.; Smith, J. R.; Snider, F. D.; Soha, A.; Sorin, V.; Song, H.; Squillacioti, P.; Stancari, M.; St. Denis, R.; Stelzer, B.; Stelzer-Chilton, O.; Stentz, D.; Strologas, J.; Strycker, G. L.; Sudo, Y.; Sukhanov, A.; Suslov, I.; Takemasa, K.; Takeuchi, Y.; Tang, J.; Tecchio, M.; Teng, P. K.; Thom, J.; Thome, J.; Thompson, G. A.; Thomson, E.; Toback, D.; Tokar, S.; Tollefson, K.; Tomura, T.; Tonelli, D.; Torre, S.; Torretta, D.; Totaro, P.; Trovato, M.; Ukegawa, F.; Uozumi, S.; Varganov, A.; Vázquez, F.; Velev, G.; Vellidis, C.; Vidal, M.; Vila, I.; Vilar, R.; Vizán, J.; Vogel, M.; Volpi, G.; Wagner, P.; Wagner, R. L.; Wakisaka, T.; Wallny, R.; Wang, S. M.; Warburton, A.; Waters, D.; Wester, W. C.; Whiteson, D.; Wicklund, A. B.; Wicklund, E.; Wilbur, S.; Wick, F.; Williams, H. H.; Wilson, J. S.; Wilson, P.; Winer, B. L.; Wittich, P.; Wolbers, S.; Wolfe, H.; Wright, T.; Wu, X.; Wu, Z.; Yamamoto, K.; Yamato, D.; Yang, T.; Yang, U. K.; Yang, Y. C.; Yao, W.-M.; Yeh, G. P.; Yi, K.; Yoh, J.; Yorita, K.; Yoshida, T.; Yu, G. B.; Yu, I.; Yu, S. S.; Yun, J. C.; Zanetti, A.; Zeng, Y.; Zhou, C.; Zucchelli, S.

    2012-04-11

    The angular distributions of muons from Υ(1S,2S,3S)→μ⁺μ⁻ decays are measured using data from pp̄ collisions at √s=1.96 TeV corresponding to an integrated luminosity of 6.7 fb⁻¹ and collected with the CDF II detector at the Fermilab Tevatron. This analysis is the first to report the full angular distributions as functions of transverse momentum pT for Υ mesons in both the Collins-Soper and s-channel helicity frames. This is also the first measurement of the spin alignment of Υ(3S) mesons. Within the kinematic range of Υ rapidity |y|<0.6 and pT up to 40 GeV/c, the angular distributions are found to be nearly isotropic.

  13. Measurements of the Angular Distributions of Muons from Υ Decays in pp̄ Collisions at √s=1.96 TeV

    DOE PAGES

    Aaltonen, T.; Álvarez González, B.; Amerio, S.; ...

    2012-04-11

    The angular distributions of muons from Υ(1S,2S,3S)→μ⁺μ⁻ decays are measured using data from pp̄ collisions at √s=1.96 TeV corresponding to an integrated luminosity of 6.7 fb⁻¹ and collected with the CDF II detector at the Fermilab Tevatron. This analysis is the first to report the full angular distributions as functions of transverse momentum pT for Υ mesons in both the Collins-Soper and s-channel helicity frames. This is also the first measurement of the spin alignment of Υ(3S) mesons. Within the kinematic range of Υ rapidity |y|<0.6 and pT up to 40 GeV/c, the angular distributions are found to be nearlymore » isotropic.« less

  14. Measurements of the angular distributions of muons from Υ decays in pp collisions at sqrt[s] = 1.96  TeV.

    PubMed

    Aaltonen, T; Álvarez González, B; Amerio, S; Amidei, D; Anastassov, A; Annovi, A; Antos, J; Apollinari, G; Appel, J A; Arisawa, T; Artikov, A; Asaadi, J; Ashmanskas, W; Auerbach, B; Aurisano, A; Azfar, F; Badgett, W; Bae, T; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Barria, P; Bartos, P; Bauce, M; Bedeschi, F; Behari, S; Bellettini, G; Bellinger, J; Benjamin, D; Beretvas, A; Bhatti, A; Bisello, D; Bizjak, I; Bland, K R; Blumenfeld, B; Bocci, A; Bodek, A; Bortoletto, D; Boudreau, J; Boveia, A; Brigliadori, L; Bromberg, C; Brucken, E; Budagov, J; Budd, H S; Burkett, K; Busetto, G; Bussey, P; Buzatu, A; Calamba, A; Calancha, C; Camarda, S; Campanelli, M; Campbell, M; Canelli, F; Carls, B; Carlsmith, D; Carosi, R; Carrillo, S; Carron, S; Casal, B; Casarsa, M; Castro, A; Catastini, P; Cauz, D; Cavaliere, V; Cavalli-Sforza, M; Cerri, A; Cerrito, L; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Chlebana, F; Cho, K; Chokheli, D; Chung, W H; Chung, Y S; Ciocci, M A; Clark, A; Clarke, C; Compostella, G; Convery, M E; Conway, J; Corbo, M; Cordelli, M; Cox, C A; Cox, D J; Crescioli, F; Cuevas, J; Culbertson, R; Dagenhart, D; d'Ascenzo, N; Datta, M; de Barbaro, P; Dell'Orso, M; Demortier, L; Deninno, M; Devoto, F; d'Errico, M; Di Canto, A; Di Ruzza, B; Dittmann, J R; D'Onofrio, M; Donati, S; Dong, P; Dorigo, M; Dorigo, T; Ebina, K; Elagin, A; Eppig, A; Erbacher, R; Errede, S; Ershaidat, N; Eusebi, R; Farrington, S; Feindt, M; Fernandez, J P; Field, R; Flanagan, G; Forrest, R; Frank, M J; Franklin, M; Freeman, J C; Funakoshi, Y; Furic, I; Gallinaro, M; Garcia, J E; Garfinkel, A F; Garosi, P; Gerberich, H; Gerchtein, E; Giagu, S; Giakoumopoulou, V; Giannetti, P; Gibson, K; Ginsburg, C M; Giokaris, N; Giromini, P; Giurgiu, G; Glagolev, V; Glenzinski, D; Gold, M; Goldin, D; Goldschmidt, N; Golossanov, A; Gomez, G; Gomez-Ceballos, G; Goncharov, M; González, O; Gorelov, I; Goshaw, A T; Goulianos, K; Grinstein, S; Grosso-Pilcher, C; Group, R C; Guimaraes da Costa, J; Hahn, S R; Halkiadakis, E; Hamaguchi, A; Han, J Y; Happacher, F; Hara, K; Hare, D; Hare, M; Harr, R F; Hatakeyama, K; Hays, C; Heck, M; Heinrich, J; Herndon, M; Hewamanage, S; Hocker, A; Hopkins, W; Horn, D; Hou, S; Hughes, R E; Hurwitz, M; Husemann, U; Hussain, N; Hussein, M; Huston, J; Introzzi, G; Iori, M; Ivanov, A; James, E; Jang, D; Jayatilaka, B; Jeon, E J; Jindariani, S; Jones, M; Joo, K K; Jun, S Y; Junk, T R; Kamon, T; Karchin, P E; Kasmi, A; Kato, Y; Ketchum, W; Keung, J; Khotilovich, V; Kilminster, B; Kim, D H; Kim, H S; Kim, J E; Kim, M J; Kim, S B; Kim, S H; Kim, Y K; Kim, Y J; Kimura, N; Kirby, M; Klimenko, S; Knoepfel, K; Kondo, K; Kong, D J; Konigsberg, J; Kotwal, A V; Kreps, M; Kroll, J; Krop, D; Kruse, M; Krutelyov, V; Kuhr, T; Kurata, M; Kwang, S; Laasanen, A T; Lami, S; Lammel, S; Lancaster, M; Lander, R L; Lannon, K; Lath, A; Latino, G; LeCompte, T; Lee, E; Lee, H S; Lee, J S; Lee, S W; Leo, S; Leone, S; Lewis, J D; Limosani, A; Lin, C-J; Lindgren, M; Lipeles, E; Lister, A; Litvintsev, D O; Liu, C; Liu, H; Liu, Q; Liu, T; Lockwitz, S; Loginov, A; Lucchesi, D; Lueck, J; Lujan, P; Lukens, P; Lungu, G; Lys, J; Lysak, R; Madrak, R; Maeshima, K; Maestro, P; Malik, S; Manca, G; Manousakis-Katsikakis, A; Margaroli, F; Marino, C; Martínez, M; Mastrandrea, P; Matera, K; Mattson, M E; Mazzacane, A; Mazzanti, P; McFarland, K S; McIntyre, P; McNulty, R; Mehta, A; Mehtala, P; Mesropian, C; Miao, T; Mietlicki, D; Mitra, A; Miyake, H; Moed, S; Moggi, N; Mondragon, M N; Moon, C S; Moore, R; Morello, M J; Morlock, J; Movilla Fernandez, P; Mukherjee, A; Muller, Th; Murat, P; Mussini, M; Nachtman, J; Nagai, Y; Naganoma, J; Nakano, I; Napier, A; Nett, J; Neu, C; Neubauer, M S; Nielsen, J; Nodulman, L; Noh, S Y; Norniella, O; Oakes, L; Oh, S H; Oh, Y D; Oksuzian, I; Okusawa, T; Orava, R; Ortolan, L; Pagan Griso, S; Pagliarone, C; Palencia, E; Papadimitriou, V; Paramonov, A A; Patrick, J; Pauletta, G; Paulini, M; Paus, C; Pellett, D E; Penzo, A; Phillips, T J; Piacentino, G; Pianori, E; Pilot, J; Pitts, K; Plager, C; Pondrom, L; Poprocki, S; Potamianos, K; Prokoshin, F; Pranko, A; Ptohos, F; Punzi, G; Rahaman, A; Ramakrishnan, V; Ranjan, N; Redondo, I; Renton, P; Rescigno, M; Riddick, T; Rimondi, F; Ristori, L; Robson, A; Rodrigo, T; Rodriguez, T; Rogers, E; Rolli, S; Roser, R; Ruffini, F; Ruiz, A; Russ, J; Rusu, V; Safonov, A; Sakumoto, W K; Sakurai, Y; Santi, L; Sato, K; Saveliev, V; Savoy-Navarro, A; Schlabach, P; Schmidt, A; Schmidt, E E; Schwarz, T; Scodellaro, L; Scribano, A; Scuri, F; Seidel, S; Seiya, Y; Semenov, A; Sforza, F; Shalhout, S Z; Shears, T; Shepard, P F; Shimojima, M; Shochet, M; Shreyber-Tecker, I; Simonenko, A; Sinervo, P; Sliwa, K; Smith, J R; Snider, F D; Soha, A; Sorin, V; Song, H; Squillacioti, P; Stancari, M; St Denis, R; Stelzer, B; Stelzer-Chilton, O; Stentz, D; Strologas, J; Strycker, G L; Sudo, Y; Sukhanov, A; Suslov, I; Takemasa, K; Takeuchi, Y; Tang, J; Tecchio, M; Teng, P K; Thom, J; Thome, J; Thompson, G A; Thomson, E; Toback, D; Tokar, S; Tollefson, K; Tomura, T; Tonelli, D; Torre, S; Torretta, D; Totaro, P; Trovato, M; Ukegawa, F; Uozumi, S; Varganov, A; Vázquez, F; Velev, G; Vellidis, C; Vidal, M; Vila, I; Vilar, R; Vizán, J; Vogel, M; Volpi, G; Wagner, P; Wagner, R L; Wakisaka, T; Wallny, R; Wang, S M; Warburton, A; Waters, D; Wester, W C; Whiteson, D; Wicklund, A B; Wicklund, E; Wilbur, S; Wick, F; Williams, H H; Wilson, J S; Wilson, P; Winer, B L; Wittich, P; Wolbers, S; Wolfe, H; Wright, T; Wu, X; Wu, Z; Yamamoto, K; Yamato, D; Yang, T; Yang, U K; Yang, Y C; Yao, W-M; Yeh, G P; Yi, K; Yoh, J; Yorita, K; Yoshida, T; Yu, G B; Yu, I; Yu, S S; Yun, J C; Zanetti, A; Zeng, Y; Zhou, C; Zucchelli, S

    2012-04-13

    The angular distributions of muons from Υ(1S,2S,3S) → μ+ μ- decays are measured using data from pp collisions at sqrt[s] = 1.96  TeV corresponding to an integrated luminosity of 6.7  fb(-1) and collected with the CDF II detector at the Fermilab Tevatron. This analysis is the first to report the full angular distributions as functions of transverse momentum p(T) for Υ mesons in both the Collins-Soper and s-channel helicity frames. This is also the first measurement of the spin alignment of Υ(3S) mesons. Within the kinematic range of Υ rapidity |y|<0.6 and p(T) up to 40  GeV/c, the angular distributions are found to be nearly isotropic.

  15. Single particle momentum and angular distributions in hadron-hadron collisions at ultrahigh energies

    NASA Technical Reports Server (NTRS)

    Chou, T. T.; Chen, N. Y.

    1985-01-01

    The forward-backward charged multiplicity distribution (P n sub F, n sub B) of events in the 540 GeV antiproton-proton collider has been extensively studied by the UA5 Collaboration. It was pointed out that the distribution with respect to n = n sub F + n sub B satisfies approximate KNO scaling and that with respect to Z = n sub F - n sub B is binomial. The geometrical model of hadron-hadron collision interprets the large multiplicity fluctuation as due to the widely different nature of collisions at different impact parameters b. For a single impact parameter b, the collision in the geometrical model should exhibit stochastic behavior. This separation of the stochastic and nonstochastic (KNO) aspects of multiparticle production processes gives conceptually a lucid and attractive picture of such collisions, leading to the concept of partition temperature T sub p and the single particle momentum spectrum to be discussed in detail.

  16. Generalized parton distributions and Deeply Virtual Compton Scattering on proton at CLAS

    SciTech Connect

    R. De Masi

    2007-12-01

    Two measurements of target and beam spin asymmetries for the reaction ep→epγ were performed with CLAS at Jefferson Laboratory. Polarized 5.7 GeV electrons were impinging on a longitudinally polarized ammonia and liquid hydrogen target respectively. These measurements are sensitive to Generalized Parton Distributions. Sizable sin phi azimuthal angular dependences were observed in both experiments, indicating the dominance of leading twist terms and the possibility of extracting combinations of Generalized Parton Distributions on the nucleon.

  17. Dense medium radiative transfer theory for two scattering layers with a Rayleigh distribution of particle sizes

    SciTech Connect

    West, R.; Tsang, Leung; Winebrenner, D.P. )

    1993-03-01

    Dense medium radiative transfer theory is applied to a three-layer model consisting of two scattering layers overlying a homogeneous half space with a size distribution of particles in each layer. A model with a distribution of sizes gives quite different results than those obtained from a model with a single size. The size distribution is especially important in the low frequency limit when scattering is strongly dependent on particle size. The size distribution and absorption characteristics also affect the extinction behavior as a function of fractional volume. Theoretical results are also compared with experimental data. The sizes, permittivities, and densities used in the numerical illustrations are typical values for snow.

  18. Performance evaluation of a multiple-scattering Compton imager for distribution of prompt gamma-rays in proton therapy

    NASA Astrophysics Data System (ADS)

    Lee, Taewoong; Lee, Hyounggun; Kim, Younghak; Lee, Wonho

    2017-01-01

    The purpose of this study is to compare and evaluate the performance of a multiple-scattering Compton imager (MSCI) to measure prompt gamma-rays emitted during proton therapy. Because prompt gamma-rays are generated simultaneously during the proton beam delivery, the falloff position of the Bragg peak of the proton beam can be determined from the distribution of prompt gamma-rays. The detection system was designed using three CdZnTe detector layers that can track radiation of unknown energy on the basis of effective Compton scattering events. The simple back-projection, filtered back-projection, and maximum likelihood expectation maximization (MLEM) algorithms were applied for the reconstructed Compton images. The falloff positions of the Bragg peaks determined from individual MSCIs were compared with the theoretical values calculated using the Monte Carlo N-Particle eXtended code. Moreover, the performance of the MSCI was compared with that of a previously developed system based on a slit collimator gamma camera. In summary, the MSCI with the MLEM reconstruction algorithm was better than the other reconstruction methods in terms of the falloff position of the Bragg peak, the angular resolution, and the signal-to-noise ratio.

  19. Potential for measurement of the distribution of DNA folds in complex environments using Correlated X-ray Scattering

    NASA Astrophysics Data System (ADS)

    Schenk, Gundolf; Krajina, Brad; Spakowitz, Andrew; Doniach, Sebastian

    2016-12-01

    In vivo chromosomal behavior is dictated by the organization of genomic DNA at length scales ranging from nanometers to microns. At these disparate scales, the DNA conformation is influenced by a range of proteins that package, twist and disentangle the DNA double helix, leading to a complex hierarchical structure that remains undetermined. Thus, there is a critical need for methods of structural characterization of DNA that can accommodate complex environmental conditions over biologically relevant length scales. Based on multiscale molecular simulations, we report on the possibility of measuring supercoiling in complex environments using angular correlations of scattered X-rays resulting from X-ray free electron laser (xFEL) experiments. We recently demonstrated the observation of structural detail for solutions of randomly oriented metallic nanoparticles [D. Mendez et al., Philos. Trans. R. Soc. B 360 (2014) 20130315]. Here, we argue, based on simulations, that correlated X-ray scattering (CXS) has the potential for measuring the distribution of DNA folds in complex environments, on the scale of a few persistence lengths.

  20. Potential for measurement of the distribution of DNA folds in complex environments using Correlated X-ray Scattering

    PubMed Central

    Schenk, Gundolf; Krajina, Brad; Spakowitz, Andrew; Doniach, Sebastian

    2016-01-01

    In vivo chromosomal behavior is dictated by the organization of genomic DNA at length scales ranging from nanometers to microns. At these disparate scales, the DNA conformation is influenced by a range of proteins that package, twist and disentangle the DNA double helix, leading to a complex hierarchical structure that remains undetermined. Thus, there is a critical need for methods of structural characterization of DNA that can accommodate complex environmental conditions over biologically relevant length scales. Based on multiscale molecular simulations, we report on the possibility of measuring supercoiling in complex environments using angular correlations of scattered X-rays resulting from X-ray free electron laser (xFEL) experiments. We recently demonstrated the observation of structural detail for solutions of randomly oriented metallic nanoparticles [D. Mendez et al., Philos. Trans. R. Soc. B 360 (2014) 20130315]. Here, we argue, based on simulations, that correlated X-ray scattering (CXS) has the potential for measuring the distribution of DNA folds in complex environments, on the scale of a few persistence lengths. PMID:27127310

  1. Communication: direct comparison between theory and experiment for correlated angular and product-state distributions of the ground-state and stretching-excited O((3)P) + CH4 reactions.

    PubMed

    Czakó, Gábor

    2014-06-21

    Motivated by a recent experiment [H. Pan and K. Liu, J. Chem. Phys. 140, 191101 (2014)], we report a quasiclassical trajectory study of the O((3)P) + CH4(vk = 0, 1) → OH + CH3 [k = 1 and 3] reactions on an ab initio potential energy surface. The computed angular distributions and cross sections correlated to the OH(v = 0, 1) + CH3(v = 0) coincident product states can be directly compared to experiment for O + CH4(v3 = 0, 1). Both theory and experiment show that the ground-state reaction is backward scattered, whereas the angular distributions shift toward sideways and forward directions upon antisymmetric stretching (v3) excitation of the reactant. Theory predicts similar behavior for the O + CH4(v1 = 1) reaction. The simulations show that stretching excitation enhances the reaction up to about 15 kcal/mol collision energy, whereas the O + CH4(vk = 1) reactions produce smaller cross sections for OH(v = 1) + CH3(v = 0) than those of O + CH4(v = 0) → OH(v = 0) + CH3(v = 0). The former finding agrees with experiment and the latter awaits for confirmation. The computed cold OH rotational distributions of O + CH4(v = 0) are in good agreement with experiment.

  2. Measurement of W boson angular distributions in events with high transverse momentum jets at √{ s} = 8 TeV using the ATLAS detector

    NASA Astrophysics Data System (ADS)

    Aaboud, M.; Aad, G.; Abbott, B.; Abdallah, J.; Abdinov, O.; Abeloos, B.; Aben, R.; AbouZeid, O. S.; Abraham, N. L.; Abramowicz, H.; Abreu, H.; Abreu, R.; Abulaiti, Y.; Acharya, B. S.; Adachi, S.; Adamczyk, L.; Adams, D. L.; Adelman, J.; Adomeit, S.; Adye, T.; Affolder, A. A.; Agatonovic-Jovin, T.; Aguilar-Saavedra, J. A.; Ahlen, S. P.; Ahmadov, F.; Aielli, G.; Akerstedt, H.; Åkesson, T. P. A.; Akimov, A. V.; Alberghi, G. L.; Albert, J.; Albrand, S.; Alconada Verzini, M. J.; Aleksa, M.; Aleksandrov, I. N.; Alexa, C.; Alexander, G.; Alexopoulos, T.; Alhroob, M.; Ali, B.; Aliev, M.; Alimonti, G.; Alison, J.; Alkire, S. P.; Allbrooke, B. M. M.; Allen, B. W.; Allport, P. P.; Aloisio, A.; Alonso, A.; Alonso, F.; Alpigiani, C.; Alshehri, A. A.; Alstaty, M.; Alvarez Gonzalez, B.; Álvarez Piqueras, D.; Alviggi, M. G.; Amadio, B. T.; Amako, K.; Amaral Coutinho, Y.; Amelung, C.; Amidei, D.; Amor Dos Santos, S. P.; Amorim, A.; Amoroso, S.; Amundsen, G.; Anastopoulos, C.; Ancu, L. S.; Andari, N.; Andeen, T.; Anders, C. F.; Anders, G.; Anders, J. K.; Anderson, K. J.; Andreazza, A.; Andrei, V.; Angelidakis, S.; Angelozzi, I.; Angerami, A.; Anghinolfi, F.; Anisenkov, A. V.; Anjos, N.; Annovi, A.; Antel, C.; Antonelli, M.; Antonov, A.; Anulli, F.; Aoki, M.; Aperio Bella, L.; Arabidze, G.; Arai, Y.; Araque, J. P.; Arce, A. T. H.; Arduh, F. A.; Arguin, J.-F.; Argyropoulos, S.; Arik, M.; Armbruster, A. J.; Armitage, L. J.; Arnaez, O.; Arnold, H.; Arratia, M.; Arslan, O.; Artamonov, A.; Artoni, G.; Artz, S.; Asai, S.; Asbah, N.; Ashkenazi, A.; Åsman, B.; Asquith, L.; Assamagan, K.; Astalos, R.; Atkinson, M.; Atlay, N. B.; Augsten, K.; Avolio, G.; Axen, B.; Ayoub, M. K.; Azuelos, G.; Baak, M. A.; Baas, A. E.; Baca, M. J.; Bachacou, H.; Bachas, K.; Backes, M.; Backhaus, M.; Bagiacchi, P.; Bagnaia, P.; Bai, Y.; Baines, J. T.; Baker, O. K.; Baldin, E. M.; Balek, P.; Balestri, T.; Balli, F.; Balunas, W. K.; Banas, E.; Banerjee, Sw.; Bannoura, A. A. E.; Barak, L.; Barberio, E. L.; Barberis, D.; Barbero, M.; Barillari, T.; Barisits, M.-S.; Barklow, T.; Barlow, N.; Barnes, S. L.; Barnett, B. M.; Barnett, R. M.; Barnovska-Blenessy, Z.; Baroncelli, A.; Barone, G.; Barr, A. J.; Barranco Navarro, L.; Barreiro, F.; Barreiro Guimarães da Costa, J.; Bartoldus, R.; Barton, A. E.; Bartos, P.; Basalaev, A.; Bassalat, A.; Bates, R. L.; Batista, S. J.; Batley, J. R.; Battaglia, M.; Bauce, M.; Bauer, F.; Bawa, H. S.; Beacham, J. B.; Beattie, M. D.; Beau, T.; Beauchemin, P. H.; Bechtle, P.; Beck, H. P.; Becker, K.; Becker, M.; Beckingham, M.; Becot, C.; Beddall, A. J.; Beddall, A.; Bednyakov, V. A.; Bedognetti, M.; Bee, C. P.; Beemster, L. J.; Beermann, T. A.; Begel, M.; Behr, J. K.; Belanger-Champagne, C.; Bell, A. S.; Bella, G.; Bellagamba, L.; Bellerive, A.; Bellomo, M.; Belotskiy, K.; Beltramello, O.; Belyaev, N. L.; Benary, O.; Benchekroun, D.; Bender, M.; Bendtz, K.; Benekos, N.; Benhammou, Y.; Benhar Noccioli, E.; Benitez, J.; Benjamin, D. P.; Bensinger, J. R.; Bentvelsen, S.; Beresford, L.; Beretta, M.; Berge, D.; Bergeaas Kuutmann, E.; Berger, N.; Beringer, J.; Berlendis, S.; Bernard, N. R.; Bernius, C.; Bernlochner, F. U.; Berry, T.; Berta, P.; Bertella, C.; Bertoli, G.; Bertolucci, F.; Bertram, I. A.; Bertsche, C.; Bertsche, D.; Besjes, G. J.; Bessidskaia Bylund, O.; Bessner, M.; Besson, N.; Betancourt, C.; Bethani, A.; Bethke, S.; Bevan, A. J.; Bianchi, R. M.; Bianchini, L.; Bianco, M.; Biebel, O.; Biedermann, D.; Bielski, R.; Biesuz, N. V.; Biglietti, M.; Bilbao De Mendizabal, J.; Billoud, T. R. V.; Bilokon, H.; Bindi, M.; Binet, S.; Bingul, A.; Bini, C.; Biondi, S.; Bisanz, T.; Bjergaard, D. M.; Black, C. W.; Black, J. E.; Black, K. M.; Blackburn, D.; Blair, R. E.; Blanchard, J.-B.; Blazek, T.; Bloch, I.; Blocker, C.; Blue, A.; Blum, W.; Blumenschein, U.; Blunier, S.; Bobbink, G. J.; Bobrovnikov, V. S.; Bocchetta, S. S.; Bocci, A.; Bock, C.; Boehler, M.; Boerner, D.; Bogaerts, J. A.; Bogavac, D.; Bogdanchikov, A. G.; Bohm, C.; Boisvert, V.; Bokan, P.; Bold, T.; Boldyrev, A. S.; Bomben, M.; Bona, M.; Boonekamp, M.; Borisov, A.; Borissov, G.; Bortfeldt, J.; Bortoletto, D.; Bortolotto, V.; Bos, K.; Boscherini, D.; Bosman, M.; Bossio Sola, J. D.; Boudreau, J.; Bouffard, J.; Bouhova-Thacker, E. V.; Boumediene, D.; Bourdarios, C.; Boutle, S. K.; Boveia, A.; Boyd, J.; Boyko, I. R.; Bracinik, J.; Brandt, A.; Brandt, G.; Brandt, O.; Bratzler, U.; Brau, B.; Brau, J. E.; Breaden Madden, W. D.; Brendlinger, K.; Brennan, A. J.; Brenner, L.; Brenner, R.; Bressler, S.; Bristow, T. M.; Britton, D.; Britzger, D.; Brochu, F. M.; Brock, I.; Brock, R.; Brooijmans, G.; Brooks, T.; Brooks, W. K.; Brosamer, J.; Brost, E.; Broughton, J. H.; Bruckman de Renstrom, P. A.; Bruncko, D.; Bruneliere, R.; Bruni, A.; Bruni, G.; Bruni, L. S.; Brunt, BH; Bruschi, M.; Bruscino, N.; Bryant, P.; Bryngemark, L.; Buanes, T.; Buat, Q.; Buchholz, P.; Buckley, A. G.; Budagov, I. A.; Buehrer, F.; Bugge, M. K.; Bulekov, O.; Bullock, D.; Burckhart, H.; Burdin, S.; Burgard, C. D.; Burghgrave, B.; Burka, K.; Burke, S.; Burmeister, I.; Burr, J. T. P.; Busato, E.; Büscher, D.; Büscher, V.; Bussey, P.; Butler, J. M.; Buttar, C. M.; Butterworth, J. M.; Butti, P.; Buttinger, W.; Buzatu, A.; Buzykaev, A. R.; Cabrera Urbán, S.; Caforio, D.; Cairo, V. M.; Cakir, O.; Calace, N.; Calafiura, P.; Calandri, A.; Calderini, G.; Calfayan, P.; Callea, G.; Caloba, L. P.; Calvente Lopez, S.; Calvet, D.; Calvet, S.; Calvet, T. P.; Camacho Toro, R.; Camarda, S.; Camarri, P.; Cameron, D.; Caminal Armadans, R.; Camincher, C.; Campana, S.; Campanelli, M.; Camplani, A.; Campoverde, A.; Canale, V.; Canepa, A.; Cano Bret, M.; Cantero, J.; Cao, T.; Capeans Garrido, M. D. M.; Caprini, I.; Caprini, M.; Capua, M.; Carbone, R. M.; Cardarelli, R.; Cardillo, F.; Carli, I.; Carli, T.; Carlino, G.; Carminati, L.; Carney, R. M. D.; Caron, S.; Carquin, E.; Carrillo-Montoya, G. D.; Carter, J. R.; Carvalho, J.; Casadei, D.; Casado, M. P.; Casolino, M.; Casper, D. W.; Castaneda-Miranda, E.; Castelijn, R.; Castelli, A.; Castillo Gimenez, V.; Castro, N. F.; Catinaccio, A.; Catmore, J. R.; Cattai, A.; Caudron, J.; Cavaliere, V.; Cavallaro, E.; Cavalli, D.; Cavalli-Sforza, M.; Cavasinni, V.; Ceradini, F.; Cerda Alberich, L.; Cerqueira, A. S.; Cerri, A.; Cerrito, L.; Cerutti, F.; Cerv, M.; Cervelli, A.; Cetin, S. A.; Chafaq, A.; Chakraborty, D.; Chan, S. K.; Chan, Y. L.; Chang, P.; Chapman, J. D.; Charlton, D. G.; Chatterjee, A.; Chau, C. C.; Chavez Barajas, C. A.; Che, S.; Cheatham, S.; Chegwidden, A.; Chekanov, S.; Chekulaev, S. V.; Chelkov, G. A.; Chelstowska, M. A.; Chen, C.; Chen, H.; Chen, K.; Chen, S.; Chen, S.; Chen, X.; Chen, Y.; Cheng, H. C.; Cheng, H. J.; Cheng, Y.; Cheplakov, A.; Cheremushkina, E.; Cherkaoui El Moursli, R.; Chernyatin, V.; Cheu, E.; Chevalier, L.; Chiarella, V.; Chiarelli, G.; Chiodini, G.; Chisholm, A. S.; Chitan, A.; Chizhov, M. V.; Choi, K.; Chomont, A. R.; Chouridou, S.; Chow, B. K. B.; Christodoulou, V.; Chromek-Burckhart, D.; Chudoba, J.; Chuinard, A. J.; Chwastowski, J. J.; Chytka, L.; Ciapetti, G.; Ciftci, A. K.; Cinca, D.; Cindro, V.; Cioara, I. A.; Ciocca, C.; Ciocio, A.; Cirotto, F.; Citron, Z. H.; Citterio, M.; Ciubancan, M.; Clark, A.; Clark, B. L.; Clark, M. R.; Clark, P. J.; Clarke, R. N.; Clement, C.; Coadou, Y.; Cobal, M.; Coccaro, A.; Cochran, J.; Colasurdo, L.; Cole, B.; Colijn, A. P.; Collot, J.; Colombo, T.; Compostella, G.; Conde Muiño, P.; Coniavitis, E.; Connell, S. H.; Connelly, I. A.; Consorti, V.; Constantinescu, S.; Conti, G.; Conventi, F.; Cooke, M.; Cooper, B. D.; Cooper-Sarkar, A. M.; Cormier, K. J. 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A.; Viel, S.; Vigani, L.; Villa, M.; Villaplana Perez, M.; Vilucchi, E.; Vincter, M. G.; Vinogradov, V. B.; Vittori, C.; Vivarelli, I.; Vlachos, S.; Vlasak, M.; Vogel, M.; Vokac, P.; Volpi, G.; Volpi, M.; von der Schmitt, H.; von Toerne, E.; Vorobel, V.; Vorobev, K.; Vos, M.; Voss, R.; Vossebeld, J. H.; Vranjes, N.; Vranjes Milosavljevic, M.; Vrba, V.; Vreeswijk, M.; Vuillermet, R.; Vukotic, I.; Vykydal, Z.; Wagner, P.; Wagner, W.; Wahlberg, H.; Wahrmund, S.; Wakabayashi, J.; Walder, J.; Walker, R.; Walkowiak, W.; Wallangen, V.; Wang, C.; Wang, C.; Wang, F.; Wang, H.; Wang, H.; Wang, J.; Wang, J.; Wang, K.; Wang, R.; Wang, S. M.; Wang, T.; Wang, T.; Wang, W.; Wanotayaroj, C.; Warburton, A.; Ward, C. P.; Wardrope, D. R.; Washbrook, A.; Watkins, P. M.; Watson, A. T.; Watson, M. F.; Watts, G.; Watts, S.; Waugh, B. M.; Webb, S.; Weber, M. S.; Weber, S. W.; Weber, S. A.; Webster, J. S.; Weidberg, A. R.; Weinert, B.; Weingarten, J.; Weiser, C.; Weits, H.; Wells, P. S.; Wenaus, T.; Wengler, T.; Wenig, S.; Wermes, N.; Werner, M.; Werner, M. D.; Werner, P.; Wessels, M.; Wetter, J.; Whalen, K.; Whallon, N. L.; Wharton, A. M.; White, A.; White, M. J.; White, R.; Whiteson, D.; Wickens, F. J.; Wiedenmann, W.; Wielers, M.; Wiglesworth, C.; Wiik-Fuchs, L. A. M.; Wildauer, A.; Wilk, F.; Wilkens, H. G.; Williams, H. H.; Williams, S.; Willis, C.; Willocq, S.; Wilson, J. A.; Wingerter-Seez, I.; Winklmeier, F.; Winston, O. J.; Winter, B. T.; Wittgen, M.; Wittkowski, J.; Wolf, T. M. H.; Wolter, M. W.; Wolters, H.; Worm, S. D.; Wosiek, B. K.; Wotschack, J.; Woudstra, M. J.; Wozniak, K. W.; Wu, M.; Wu, M.; Wu, S. L.; Wu, X.; Wu, Y.; Wyatt, T. R.; Wynne, B. M.; Xella, S.; Xu, D.; Xu, L.; Yabsley, B.; Yacoob, S.; Yamaguchi, D.; Yamaguchi, Y.; Yamamoto, A.; Yamamoto, S.; Yamanaka, T.; Yamauchi, K.; Yamazaki, Y.; Yan, Z.; Yang, H.; Yang, H.; Yang, Y.; Yang, Z.; Yao, W.-M.; Yap, Y. C.; Yasu, Y.; Yatsenko, E.; Yau Wong, K. H.; Ye, J.; Ye, S.; Yeletskikh, I.; Yildirim, E.; Yorita, K.; Yoshida, R.; Yoshihara, K.; Young, C.; Young, C. J. S.; Youssef, S.; Yu, D. R.; Yu, J.; Yu, J. M.; Yu, J.; Yuan, L.; Yuen, S. P. Y.; Yusuff, I.; Zabinski, B.; Zaidan, R.; Zaitsev, A. M.; Zakharchuk, N.; Zalieckas, J.; Zaman, A.; Zambito, S.; Zanello, L.; Zanzi, D.; Zeitnitz, C.; Zeman, M.; Zemla, A.; Zeng, J. C.; Zeng, Q.; Zenin, O.; Ženiš, T.; Zerwas, D.; Zhang, D.; Zhang, F.; Zhang, G.; Zhang, H.; Zhang, J.; Zhang, L.; Zhang, M.; Zhang, R.; Zhang, R.; Zhang, X.; Zhang, Z.; Zhao, X.; Zhao, Y.; Zhao, Z.; Zhemchugov, A.; Zhong, J.; Zhou, B.; Zhou, C.; Zhou, L.; Zhou, L.; Zhou, M.; Zhou, N.; Zhu, C. G.; Zhu, H.; Zhu, J.; Zhu, Y.; Zhuang, X.; Zhukov, K.; Zibell, A.; Zieminska, D.; Zimine, N. I.; Zimmermann, C.; Zimmermann, S.; Zinonos, Z.; Zinser, M.; Ziolkowski, M.; Živković, L.; Zobernig, G.; Zoccoli, A.; zur Nedden, M.; Zwalinski, L.

    2017-02-01

    The W boson angular distribution in events with high transverse momentum jets is measured using data collected by the ATLAS experiment from proton-proton collisions at a centre-of-mass energy √{ s} = 8 TeV at the Large Hadron Collider, corresponding to an integrated luminosity of 20.3 fb-1. The focus is on the contributions to W +jets processes from real W emission, which is achieved by studying events where a muon is observed close to a high transverse momentum jet. At small angular separations, these contributions are expected to be large. Various theoretical models of this process are compared to the data in terms of the absolute cross-section and the angular distributions of the muon from the leptonic W decay.

  3. E1 and E2 S factors of {sup 12}C({alpha},{gamma}{sub 0}){sup 16}O from {gamma}-ray angular distributions with a 4 {pi}-detector array

    SciTech Connect

    Assuncao, M.; Lefebvre-Schuhl, A.; Kiener, J.; Tatischeff, V.; Boukari-Pelissie, C.; Coc, A.; Correia, J.J.; Grama, C.; Hannachi, F.; Korichi, A.; LeDu, D.; Lopez-Martens, A.; Meunier, R.; Thibaud, J.P.; Beck, C.; Courtin, S.

    2006-05-15

    A new experiment to determine the thermonuclear cross section of the {sup 12}C({alpha},{gamma}){sup 16}O reaction has been performed in regular kinematics using an intense {alpha}-particle beam of up to 340 {mu}A from the Stuttgart DYNAMITRON. For the first time, a 4{pi}-germanium-detector setup has been used to measure the angular distribution of the {gamma} rays at all angles simultaneously. It consisted of an array of nine EUROGAM high-purity Ge detectors in close geometry, actively shielded individually with bismuth germanate crystals. The {sup 12}C targets were isotopically enriched by magnetic separation during implantation. The depth profiles of the implanted carbon in the {sup 12}C targets were determined by Rutherford backscattering for purposes of cross-section normalization and absolute determination of the E1 and E2 S factors. Angular distributions of the {gamma} decay to the {sup 16}O ground state were measured in the energy range E{sub c.m.}=1.30-2.78 MeV and in the angular range (lab.) 30 deg. -130 deg. . From these distributions, astrophysical E1 and E2 S-factor functions vs energy were calculated, both of which are indispensable to the modeling of this reaction and the extrapolation toward lower energies. The separation of the E1 and E2 capture channels was done both by taking the phase value {phi}{sub 12} as a free parameter and by fixing it using the results of elastic {alpha}-particle scattering on {sup 12}C in the same energy range.

  4. Determination of solar flare accelerated ion angular distributions from SMM gamma ray and neutron measurements and determination of the He-3/H ratio in the solar photosphere from SMM gamma ray measurements

    NASA Technical Reports Server (NTRS)

    Lingenfelter, Richard E.

    1989-01-01

    Comparisons of Solar Maximum Mission (SMM) observations of gamma-ray line and neutron emission with theoretical calculation of their expected production by flare accelerated ion interactions in the solar atmosphere have led to significant advances in the understanding of solar flare particle acceleration and interaction, as well as the flare process itself. These comparisons have enabled the determination of, not only the total number and energy spectrum of accelerated ions trapped at the sun, but also the ion angular distribution as they interact in the solar atmosphere. The Monte Carlo program was modified to include in the calculations of ion trajectories the effects of both mirroring in converging magnetic fields and of pitch angle scattering. Comparing the results of these calculations with the SMM observations, not only the angular distribution of the interacting ions can be determined, but also the initial angular distribution of the ions at acceleration. The reliable determination of the solar photospheric He-3 abundance is of great importance for understanding nucleosynthesis in the early universe and its implications for cosmology, as well as for the study of the evolution of the sun. It is also essential for the determinations of the spectrum and total number of flare accelerated ions from the SMM/GRS gamma-ray line measurements. Systematic Monte Carlo calculations of the time dependence were made as a function of the He-3 abundance and other variables. A new series of calculations were compared for the time-dependent flux of 2.223 MeV neutron capture line emission and the ratio of the time-integrated flux in the 2.223 MeV line to that in the 4.1 to 6.4 MeV nuclear deexcitation band.

  5. Angular dependence of the pp elastic-scattering analyzing power between 0.8 and 2.8 GeV. I. Results for 1.80{endash}2.24 GeV

    SciTech Connect

    Allgower, C.E.; Beddo, M.E.; Grosnick, D.P.; Kasprzyk, T.E.; Lopiano, D.; Spinka, H.M.; Ball, J.; Beauvais, P.; Bedfer, Y.; Chamouard, P.; Combet, M.; Fontaine, J.; Kunne, R.; Lagniel, J.M.; Lemaire, J.L.; Milleret, G.; Sans, J.; Boutefnouchet, A.; Ghazikhanian, V.; Whitten, C.A.; Demierre, P.; Hess, R.; Janout, Z.F.; Rapin, D.; Vuaridel, B.; Prokofiev, A.N.; Vikhrov, V.V.; Zhdanov, A.A.

    1999-11-01

    Experimental results are presented for the pp elastic-scattering single spin observable A{sub oono}=A{sub ooon}=A{sub N}=P, or the analyzing power, at 19 beam kinetic energies between 1795 and 2235 MeV. The typical c.m. angular range is 60{endash}100{degree}. The measurements were performed at Saturne II with a vertically polarized beam and target (transverse to the beam direction and scattering plane), a magnetic spectrometer and a recoil detector, both instrumented with multiwire proportional chambers, and beam polarimeters. {copyright} {ital 1999} {ital The American Physical Society}

  6. Origin and orbital distribution of the trans-Neptunian scattered disc

    NASA Astrophysics Data System (ADS)

    Morbidelli, A.; Emel'yanenko, V. V.; Levison, H. F.

    2004-12-01

    We revisit the scenario proposed by Duncan and Levison in the late 1990s on the origin of the trans-Neptunian scattered disc. According to this scenario, the current scattered disc population is the remnant of a much more massive population that formed at the beginning of the Solar system, presumably when Neptune grew in mass. In order to compute the expected orbital distribution of the scattered disc bodies in the framework of this model, we have integrated the evolution of several thousands of test particles over the age of the Solar system, and looked at the orbital distribution of those surviving after more than 2 × 109 yr from their first scattering event. In order to compare this model distribution with the observed distribution, we have modelled the observational biases by generalizing a method originally introduced recently by Trujillo and Brown. Once the biases are taken into account, the model distribution matches the observed distribution fairly well. The most significant discrepancy is that the observed perihelion distance distribution is somewhat skewed towards larger perihelion distances than our model predicts. This is possibly due to the effects of planet migration (which tends to raise perihelion distances as recently shown by Gomes), which is not taken into account in our simulations.

  7. A diffusion approximation for ocean wave scatterings by randomly distributed ice floes

    NASA Astrophysics Data System (ADS)

    Zhao, Xin; Shen, Hayley

    2016-11-01

    This study presents a continuum approach using a diffusion approximation method to solve the scattering of ocean waves by randomly distributed ice floes. In order to model both strong and weak scattering, the proposed method decomposes the wave action density function into two parts: the transmitted part and the scattered part. For a given wave direction, the transmitted part of the wave action density is defined as the part of wave action density in the same direction before the scattering; and the scattered part is a first order Fourier series approximation for the directional spreading caused by scattering. An additional approximation is also adopted for simplification, in which the net directional redistribution of wave action by a single scatterer is assumed to be the reflected wave action of a normally incident wave into a semi-infinite ice cover. Other required input includes the mean shear modulus, diameter and thickness of ice floes, and the ice concentration. The directional spreading of wave energy from the diffusion approximation is found to be in reasonable agreement with the previous solution using the Boltzmann equation. The diffusion model provides an alternative method to implement wave scattering into an operational wave model.

  8. Angular and energy distribution for parent primaries of cosmic muons at the sea level using Geant4

    NASA Astrophysics Data System (ADS)

    Arslan, Halil; Bektasoglu, Mehmet

    2015-04-01

    The angular and energy distributions of the primary cosmic rays that are responsible for the muons reaching the sea level have been estimated using the Geant4 simulation package. The models used in the simulations were tested by comparing the simulation results for the differential muon flux with the BESS measurements performed in Lynn Lake, Canada. Then, direct relationship between the propagation directions of the muons and those of the responsible primary particles has been investigated. The median energies for the parent primaries of vertical muons reaching the sea level with the threshold energies (Eμ) in the range 0.5-300 GeV were obtained. Simulation results for the median primary energies, 15.5Eμ and 11.2Eμ for Eμ = 14 GeV and Eμ = 100 GeV, have been found to be in good agreement with the literature. Furthermore, median primary energies for the low energy muons with large zenith angle have been seen to be relatively higher than the ones for the muons with narrower angles.

  9. Angular distribution of energetic argon ions emitted by a 90 kJ Filippov-type plasma focus

    SciTech Connect

    Pestehe, S. J.; Mohammadnejad, M.

    2015-02-15

    Characteristics of the energetic argon ions emitted by a 90 kJ Filippov-type plasma focus are studied by employing an array of Faraday cups. The Faraday cups are designed to minimize the secondary electron emission effects on their response. Angular distribution of the ions is measured, and the results indicate a highly anisotropic emission with a dip at the device axis and a local maximum at the angle of 7° with respect to the axis. It has been argued that this kind of anisotropic emission may be related to the surfatron acceleration mechanism and shown that this behavior is independent of the working gas pressure. It has been also demonstrated that this mechanism is responsible for the generation of MeV ions. Measuring the total ion number at different working gas pressures gives an optimum pressure of 0.3 Torr. In addition, the energy spectrum of ions is measured by taking into account of the ambient gas effects on the energy and charge of the ions. The current neutralization effect of electrons trapped in the ion beam as well as the effect of conducting boundaries surrounding the beam, on the detected signals are investigated.

  10. Photoelectron angular distributions in molecular above threshold ionization by two colour circularly polarized ultrashort UV laser pulses

    NASA Astrophysics Data System (ADS)

    Yuan, Kai-Jun; Bandrauk, André D.

    2013-10-01

    Photoionization of an aligned molecular ion H? has been investigated with two colour circularly polarized ultrashort UV laser pulses by numerically solving the corresponding time dependent Schrödinger equation. Photoelectron angular distributions (PADs) in molecular above threshold ionization (MATI) exhibit: (i) asymmetry resulting from interference of coherent electron wave packets from multiple pathway ionization, which depends critically on the relative carrier envelope phase (CEP) ? between the two colour laser pulses and photoelectron kinetic energies; (ii) rotation with respect to the molecular symmetry axes due to effects of the nonspherical two center Coulomb potential. Such features are described by multi-photon perturbative theoretical ionization models. The ionization probability is functions of both the CEP ? and the angle ? between the electron emission and the molecular axis. The influence of pulse intensity and ellipticity on PADs in MATI is also investigated. It is found that the asymmetry depends on the pulse intensity whereas the rotation angle is shown to be sensitive to the pulse ellipticity, both reflecting the orientation dependence of molecular ionization probabilities.

  11. Theoretical description of circular dichroism in photoelectron angular distributions of randomly oriented chiral molecules after multi-photon photoionization

    NASA Astrophysics Data System (ADS)

    Goetz, R. E.; Isaev, T. A.; Nikoobakht, B.; Berger, R.; Koch, C. P.

    2017-01-01

    Photoelectron circular dichroism refers to the forward/backward asymmetry in the photoelectron angular distribution with respect to the propagation axis of circularly polarized light. It has recently been demonstrated in femtosecond multi-photon photoionization experiments with randomly oriented camphor and fenchone molecules [C. Lux et al., Angew. Chem., Int. Ed. 51, 4755 (2012) and C. S. Lehmann et al., J. Chem. Phys. 139, 234307 (2013)]. A theoretical framework describing this process as (2+1) resonantly enhanced multi-photon ionization is constructed, which consists of two-photon photoselection from randomly oriented molecules and successive one-photon ionization of the photoselected molecules. It combines perturbation theory for the light-matter interaction with ab initio calculations for the two-photon absorption and a single-center expansion of the photoelectron wavefunction in terms of hydrogenic continuum functions. It is verified that the model correctly reproduces the basic symmetry behavior expected under exchange of handedness and light helicity. When applied to fenchone and camphor, semi-quantitative agreement with the experimental data is found, for which a sufficient d wave character of the electronically excited intermediate state is crucial.

  12. The effect of the dipole bound state on AgF- vibrationally resolved photodetachment cross sections and photoelectron angular distributions

    NASA Astrophysics Data System (ADS)

    Dao, Diep Bich; Mabbs, Richard

    2014-10-01

    The first photoelectron spectra of AgF- are recorded over the energy range 1.61-1.85 eV using the velocity map imaging technique. The resolved vibrational structure of the AgF X', v' ← AgF- X″, v″ = 0 band yields an AgF electron affinity of 1.46 ± 0.01 eV and vibrational frequency of 500 ± 40 cm-1. For the v' = 2, 3, 4 channels, the photodetachment cross sections and angular distributions undergo rapid changes over a narrow electron kinetic energy range in the region of 50 meV (approximately 13 meV below the opening of the next vibrational channel). This is consistent with Fano-like behavior indicating autodetachment following excitation to a resonant anion state lying in the detachment continuum. EOM-CCSD calculations reveal this to be a dipole bound state. The consistency of the detachment data with the vibrational autodetachment propensity rule Δv = -1 shows that the autodetachment results from breakdown of the Born-Oppenheimer approximation, coupling the vibrational and electronic degrees of freedom.

  13. The temperature dependence of inelastic light scattering from small particles for use in combustion diagnostic instrumentation

    NASA Technical Reports Server (NTRS)

    Cloud, Stanley D.

    1987-01-01

    A computer calculation of the expected angular distribution of coherent anti-Stokes Raman scattering (CARS) from micrometer size polystyrene spheres based on a Mie-type model, and a pilot experiment to test the feasibility of measuring CARS angular distributions from micrometer size polystyrene spheres by simply suspending them in water are discussed. The computer calculations predict a very interesting structure in the angular distributions that depends strongly on the size and relative refractive index of the spheres.

  14. Accounting for the effects of sastrugi in the CERES clear-sky Antarctic shortwave angular distribution models

    NASA Astrophysics Data System (ADS)

    Corbett, J.; Su, W.

    2015-08-01

    The Cloud and the Earth's Radiant Energy System (CERES) instruments on NASA's Terra, Aqua and Soumi NPP satellites are used to provide a long-term measurement of Earth's energy budget. To accomplish this, the radiances measured by the instruments must be inverted to fluxes by the use of a scene-type-dependent angular distribution model (ADM). For permanent snow scenes over Antarctica, shortwave (SW) ADMs are created by compositing radiance measurements over the full viewing zenith and azimuth range. However, the presence of small-scale wind blown roughness features called sastrugi cause the BRDF (bidirectional reflectance distribution function) of the snow to vary significantly based upon the solar azimuth angle and location. This can result in monthly regional biases between -12 and 7.5 Wm-2 in the inverted TOA (top-of-atmosphere) SW flux. The bias is assessed by comparing the CERES shortwave fluxes derived from nadir observations with those from all viewing zenith angles, as the sastrugi affect fluxes inverted from the oblique viewing angles more than for the nadir viewing angles. In this paper we further describe the clear-sky Antarctic ADMs from Su et al. (2015). These ADMs account for the sastrugi effect by using measurements from the Multi-Angle Imaging Spectro-Radiometer (MISR) instrument to derive statistical relationships between radiance from different viewing angles. We show here that these ADMs reduce the bias and artifacts in the CERES SW flux caused by sastrugi, both locally and Antarctic-wide. The regional monthly biases from sastrugi are reduced to between -5 and 7 Wm-2, and the monthly-mean biases over Antarctica are reduced by up to 0.64 Wm-2, a decrease of 74 %. These improved ADMs are used as part of the Edition 4 CERES SSF (Single Scanner Footprint) data.

  15. Measurements of partial cross sections and photoelectron angular distributions for the photodetachment of Fe{sup -} and Cu{sup -} at visible photon wavelengths

    SciTech Connect

    Covington, A. M.; Duvvuri, Srividya S.; Emmons, E. D.; Kraus, R. G.; Williams, W. W.; Thompson, J. S.; Calabrese, D.; Carpenter, D. L.; Collier, R. D.; Kvale, T. J.; Davis, V. T.

    2007-02-15

    Photodetachment cross sections and the angular distributions of photoelectrons produced by the single-photon detachment of the transition metal negative ions Fe{sup -} and Cu{sup -} have been measured at four discrete photon wavelengths ranging from 457.9 to 647.1 nm (2.71-1.92 eV) using a crossed-beams laser photodetachment electron spectrometry (LPES) apparatus. Photodetachment cross sections were determined by comparing the photoelectron yields from the photodetachment of Fe{sup -} to those of Cu{sup -} and C{sup -}, which have known absolute photodetachment cross sections. Using the measured photodetachment cross sections, radiative electron attachment cross sections were calculated using the principle of detailed balance. Angular distributions were determined by measurements of laboratory frame, angle-, and energy-resolved photoelectrons as a function of the angle between the linear laser polarization vector and the momentum vector of the collected photoelectrons. Values of the asymmetry parameter have been determined by nonlinear least-squares fits to these angular distributions. The measured asymmetry parameters are compared to predictions of photodetachment models including Cooper and Zare's dipole approximation theory [J. Cooper and R. N. Zare, J. Chem. Phys. 48, 942 (1968)], and the angular momentum transfer theory developed by Fano and Dill [Phys. Rev. A 6, 185 (1972)].

  16. Angular Momentum Profiles of Warm Dark Matter Halos

    NASA Astrophysics Data System (ADS)

    Bullock, James S.; Kravtsov, and Andrey V.; Colín, Pedro

    2002-01-01

    We compare the specific angular momentum profiles of virialized dark halos in cold dark matter (CDM) and warm dark matter (WDM) models, using high-resolution dissipationless simulations. The simulations were initialized using the same set of modes, except on small scales, where the power was suppressed in WDM below the filtering length. Remarkably, WDM as well as CDM halos are well described by the two-parameter angular momentum profile of Bullock and coworkers, even though the halo masses are below the filtering scale of the WDM. Although the best-fit shape parameters change quantitatively for individual halos in the two simulations, we find no systematic variation in profile shapes as a function of the dark matter type. The scatter in shape parameters is significantly smaller for the WDM halos, suggesting that substructure and/or merging history plays a role in producing scatter about the mean angular momentum distribution, but that the average angular momentum profiles of halos originate from larger scale phenomena or a mechanism associated with the virialization process. The known mismatch between the angular momentum distributions of dark halos and disk galaxies is, therefore, present in WDM as well as CDM models. Our WDM halos tend to have a less coherent (more misaligned) angular momentum structure and smaller spin parameters than do their CDM counterparts, although we caution that this result is based on a small number of halos.

  17. Statistical properties of three-dimensional speckle distributions produced by crossed scattered waves.

    PubMed

    Okamoto, Takashi; Fujita, Shuhei

    2008-12-01

    The statistical properties of three-dimensional normal and fractal speckle fields produced by two or three scattered waves crossed orthogonally are studied theoretically. The probability density function and the autocorrelation function of intensity are derived for speckle fields superposed with and without interference. It is shown that the spatial anisotropy of intensity distributions exists even when three scattered waves interfere with one another. This spatial anisotropy affects the power-law distribution of intensity correlation for fractal speckles and leads to intensity patterns that are not self-similar in two or three dimensions. A potential application of the superposed speckle field is proposed.

  18. Subsidence monitoring in coal area using time-series InSAR combining persistent scatterers and distributed scatterers

    NASA Astrophysics Data System (ADS)

    Zhang, Zhengjia; Wang, Chao; Tang, Yixian; Fu, Qiaoyan; Zhang, Hong

    2015-07-01

    In coal mining areas, ground subsidence persistently happens, which produces serious environmental issues and affects the development of cities. To monitor the ground deformation due to coal mining, a modified time-series InSAR technique combining persistent scatterers (PSs) and distributed scatterers (DSs) is presented in this paper. In particular, DSs are efficiently identified using classified information and statistical characteristics. Furthermore, a two-scale network is introduced into traditional PSI to deal with PSs and DSs in a multi-layer framework by taking the advantage of the robust of PSs and the widely distribution of DSs. The proposed method is performed to investigate the subsidence of Huainan City, Anhui province (China), during 2012-2013 using 14 scenes of Radarsat-2 images. Experimental results show that the proposed method can ease the estimation complexity and significantly increase the spatial density of measurement points, which can provide more detailed deformation information. Result shows that there are obvious subsidence areas detected in the test site with subsidence velocity larger than 5 cm/year. The proposed method brings practical applications for non-urban area deformation monitoring.

  19. A POSSIBLE DIVOT IN THE SIZE DISTRIBUTION OF THE KUIPER BELT'S SCATTERING OBJECTS

    SciTech Connect

    Shankman, C.; Gladman, B. J.; Kaib, N.; Kavelaars, J. J.; Petit, J. M.

    2013-02-10

    Via joint analysis of a calibrated telescopic survey, which found scattering Kuiper Belt objects, and models of their expected orbital distribution, we explore the scattering-object (SO) size distribution. Although for D > 100 km the number of objects quickly rise as diameters decrease, we find a relative lack of smaller objects, ruling out a single power law at greater than 99% confidence. After studying traditional ''knees'' in the size distribution, we explore other formulations and find that, surprisingly, our analysis is consistent with a very sudden decrease (a divot) in the number distribution as diameters decrease below 100 km, which then rises again as a power law. Motivated by other dynamically hot populations and the Centaurs, we argue for a divot size distribution where the number of smaller objects rises again as expected via collisional equilibrium. Extrapolation yields enough kilometer-scale SOs to supply the nearby Jupiter-family comets. Our interpretation is that this divot feature is a preserved relic of the size distribution made by planetesimal formation, now ''frozen in'' to portions of the Kuiper Belt sharing a ''hot'' orbital inclination distribution, explaining several puzzles in Kuiper Belt science. Additionally, we show that to match today's SO inclination distribution, the supply source that was scattered outward must have already been vertically heated to the of order 10 Degree-Sign .

  20. Angular Momentum in Dwarf Galaxies

    NASA Astrophysics Data System (ADS)

    Del Popolo, A.

    We study the ``angular momentum catastrophe" in the framework of interaction among baryons and dark matter through dynamical friction. By means of Del Popolo (2009) model we simulate 14 galaxies similar to those investigated by van den Bosch, Burkert and Swaters (2001), and calculate the distribution of their spin parameters and the angular momenta. Our model gives the angular momentum distribution which is in agreement with the van den Bosch et al. observations. Our result shows that the ``angular momentum catastrophe" can be naturally solved in a model that takes into account the baryonic physics and the exchange of energy and angular momentum between the baryonic clumps and dark matter through dynamical friction.

  1. Angular Dependence of the Photoelectron Energy Distribution of InP(100) and GaAs(100) Negative Electron Affinity Photocathodes

    SciTech Connect

    Lee, Dong-Ick; Sun, Yun; Lu, Zhi; Sun, Shiyu; Pianetta, Piero; /SLAC, SSRL

    2007-10-15

    Energy distribution of the photoelectrons from InP(100) photocathodes are investigated with a photon energy range from 0.62eV to 2.76eV. When the photon energy is less than 1.8eV, only electrons emitted from the Gamma valley are observed in the energy distribution curves (EDC). At higher photon energies, electrons from the L valley are observed. The angular dependence of the electron energy distributions of InP and GaAs photocathodes are studied and compared. The electrons emitted from the L valley have a larger angular spread than the ones from the Gamma valley due to the larger effective mass of the L valley minimum.

  2. Modified polarimetric bidirectional reflectance distribution function with diffuse scattering: surface parameter estimation

    NASA Astrophysics Data System (ADS)

    Zhan, Hanyu; Voelz, David G.

    2016-12-01

    The polarimetric bidirectional reflectance distribution function (pBRDF) describes the relationships between incident and scattered Stokes parameters, but the familiar surface-only microfacet pBRDF cannot capture diffuse scattering contributions and depolarization phenomena. We propose a modified pBRDF model with a diffuse scattering component developed from the Kubelka-Munk and Le Hors et al. theories, and apply it in the development of a method to jointly estimate refractive index, slope variance, and diffuse scattering parameters from a series of Stokes parameter measurements of a surface. An application of the model and estimation approach to experimental data published by Priest and Meier shows improved correspondence with measurements of normalized Mueller matrix elements. By converting the Stokes/Mueller calculus formulation of the model to a degree of polarization (DOP) description, the estimation results of the parameters from measured DOP values are found to be consistent with a previous DOP model and results.

  3. A formalism for scattering of complex composite structures. II. Distributed reference points.

    PubMed

    Svaneborg, Carsten; Pedersen, Jan Skov

    2012-04-21

    Recently, we developed a formalism for the scattering from linear and acyclic branched structures build of mutually non-interacting sub-units. [C. Svaneborg and J. S. Pedersen, J. Chem. Phys. 136, 104105 (2012)] We assumed each sub-unit has reference points associated with it. These are well-defined positions where sub-units can be linked together. In the present paper, we generalize the formalism to the case where each reference point can represent a distribution of potential link positions. We also present a generalized diagrammatic representation of the formalism. Scattering expressions required to model rods, polymers, loops, flat circular disks, rigid spheres, and cylinders are derived, and we use them to illustrate the formalism by deriving the generic scattering expression for micelles and bottle-brush structures and show how the scattering is affected by different choices of potential link positions and sub-unit choices.

  4. Classical Calculations of Scattering Signatures from a Gravitational Singularity or the Scattering and Absorption Cross-Sections of a Black Hole

    NASA Astrophysics Data System (ADS)

    Difilippo, Felix C.

    2012-09-01

    Within the context of general relativity theory we calculate, analytically, scattering signatures around a gravitational singularity: angular and time distributions of scattered massive objects and photons and the time and space modulation of Doppler effects. Additionally, the scattering and absorption cross sections for the gravitational interactions are calculated. The results of numerical simulations of the trajectories are compared with the analytical results.

  5. Rotational branching ratios and photoelectron angular distributions in resonance enhanced multiphoton ionization of HBr via the F sup 1. Delta. sub 2 Rydberg state

    SciTech Connect

    Wang, K.; McKoy, V. )

    1991-12-01

    Results of theoretical studies of rotational ion distributions in the {ital X} {sup 2}{Pi}{sub 1/2} ground state of HBr{sup +} resulting from (2+1) resonance enhanced multiphoton ionization (REMPI) via the {ital S}(2) branch of the {ital F} {sup 1}{Delta}{sub 2} Rydberg state are reported. These results show a strongly parity-favored ion distribution with about 80% population in the ({minus}) component of the {Lambda} doublet of {ital J}{sup +} rotational levels. The 20% population in the other parity component of the {Lambda} doublet can be seen to be due to odd partial wave contributions to the photoelectron matrix elements which arise primarily from non-atomic-like behavior of the electronic continuum. This, in turn, is due to angular momentum coupling in the photoelectron orbital brought about by the torques of the nonspherical molecular ion potential. We demonstrate that the effect of alignment on these ion distributions, although not large, is important. Photoelectron angular distributions and alignment of the {ital J} levels of the HBr{sup +} ions are also presented. Rotational branching ratios and photoelectron angular distributions resulting from (2+1{prime}) REMPI of HBr via several {ital S} branches of the {ital F} {sup 1}{Delta}{sub 2} state are also shown for near-threshold photoelectron energies.

  6. Monte Carlo study of secondary electrons and X-rays produced by different angular distributions of primary precipitating electrons interacting with the atmosphere

    NASA Astrophysics Data System (ADS)

    Sheldon, W. R.; Andersen, V.; Pinsky, L. S.

    Electron precipitation from the outer belt is an important input of energy and electric charge to the atmosphere. Its effect on the electrodynamics of the atmosphere depends on the resulting ionization profile (ionization rate vs. altitude). It is likely that the ionization profile is strongly affected by the angular distribution of precipitating electrons absorbed by the atmosphere. Definitive measurements of precipitating electrons at the top of the atmosphere have not been made; the usual assumption for calculations of this problem is that they have an isotropic distribution over the zenithal hemisphere. However, consideration of the mechanism leading to the precipitation of outer belt electrons suggests a different distribution: a trapped electron in the process of mirroring encounters a region near the top of the atmosphere where its gyro-circumference is equal to its mean-free-path and thus collides with an atmospheric molecule. In this case, precipitating electrons are traveling horizontally when they are absorbed in the atmosphere. In order to investigate differences in the ionization profile that may depend on the angular distribution of precipitating electrons, we have conducted a Monte Carlo study of this problem using the FLUKA code. The two angular distributions described previously were assumed with an energy spectrum typical for outer belt electrons up to 10 MeV; both electrons and X-rays were followed down to energies of 100 keV. The Monte Carlo results are compared to measurements of electrons in the atmosphere below 80 km made from rocket-boosted, parachute-deployed payloads, and to measurements of X-rays made on balloon payloads at altitudes of about 35 km. Also, the flux and energy spectrum of backscattered electrons traveling upward from the atmosphere are determined for the two angular distributions of precipitating electrons, isotropic over the zenithal hemisphere and horizontal absorption.

  7. Generalized helicity formalism, higher moments, and the B →KJK(→K π )ℓ1 ¯ ℓ2 angular distributions

    NASA Astrophysics Data System (ADS)

    Gratrex, James; Hopfer, Markus; Zwicky, Roman

    2016-03-01

    We generalize the Jacob-Wick helicity formalism, which applies to sequential decays, to effective field theories of rare decays of the type B →KJ K(→K π )ℓ¯1ℓ2. This is achieved by reinterpreting local interaction vertices b ¯ Γμ1…μn 's ℓ ¯ Γμ1…μnℓ as a coherent sum of 1 →2 processes mediated by particles whose spin ranges between zero and n . We illustrate the framework by deriving the full angular distributions for B ¯→K ¯ℓ1ℓ¯2 and B ¯→K¯*(→K ¯π )ℓ1ℓ¯2 for the complete dimension-six effective Hamiltonian for nonequal lepton masses. Amplitudes and decay rates are expressed in terms of Wigner rotation matrices, leading naturally to the method of moments in various forms. We discuss how higher-spin operators and QED corrections alter the standard angular distribution used throughout the literature, potentially leading to differences between the method of moments and the likelihood fits. We propose to diagnose these effects by assessing higher angular moments. These could be relevant in investigating the nature of the current LHCb anomalies in RK=B (B →K μ+μ-)/B (B →K e+e-) as well as angular observables in B →K*μ+μ-.

  8. The Rotation Period Distributions of 4-10 Myr T Tauri Stars in Orion OB1: New Constraints on Pre-main-sequence Angular Momentum Evolution

    NASA Astrophysics Data System (ADS)

    Karim, Md Tanveer; Stassun, Keivan G.; Briceño, César; Vivas, A. Katherina; Raetz, Stefanie; Mateu, Cecilia; José Downes, Juan; Calvet, Nuria; Hernández, Jesús; Neuhäuser, Ralph; Mugrauer, Markus; Takahashi, Hidenori; Tachihara, Kengo; Chini, Rolf; Cruz-Dias, Gustavo A.; Aarnio, Alicia; James, David J.; Hackstein, Moritz

    2016-12-01

    Most existing studies of the angular momentum evolution of young stellar populations have focused on the youngest (≲1-3 Myr) T Tauri stars. In contrast, the angular momentum distributions of older T Tauri stars (˜4-10 Myr) have been less studied, even though they hold key insights to understanding stellar angular momentum evolution at a time when protoplanetary disks have largely dissipated and when models therefore predict changes in the rotational evolution that can in principle be tested. We present a study of photometric variability among 1974 confirmed T Tauri members of various subregions of the Orion OB1 association, and with ages spanning 4-10 Myr, using optical time series from three different surveys. For 564 of the stars (˜32% of the weak-lined T Tauri stars and ˜13% of the classical T Tauri stars in our sample) we detect statistically significant periodic variations, which we attribute to the stellar rotation periods, making this one of the largest samples of T Tauri star rotation periods yet published. We observe a clear change in the overall rotation period distributions over the age range 4-10 Myr, with the progressively older subpopulations exhibiting systematically faster rotation. This result is consistent with angular momentum evolution model predictions of an important qualitative change in the stellar rotation periods starting at ˜5 Myr, an age range for which very few observational constraints were previously available.

  9. Monte Carlo simulation of light scattering from size distributed homogenous and coated spherical particles

    NASA Astrophysics Data System (ADS)

    Gogoi, Ankur

    Light scattering is a subject of intensive research at the present time in diverse fields of research namely, physics, astronomy, meteorology, biology, nanotechnology, etc. Observation and theoretical calculation of the absorption and scattering properties of particles, whose size ranges from micrometer to nanometer, are not only essential to deduce their physical properties but also capable of giving useful information for better understanding of radiation transfer through a medium containing such scatterer. In addition to such experimental and theoretical studies on light scattering by particulate matter several other groups have been extensively using Monte Carlo (MC) method to simulate light (photon) propagation in scattering media. Importantly such methods of simulating light scattering properties of artificial particles are proving to be a very useful tool in verifying the experimental observations with real samples as well as providing new clues to improve the accuracy of the existing theoretical models. In this contribution we report a MC method developed by implementing Mie theory to simulate the light scattering pattern from size distributed homogenous and coated spherical particles in single scattering regime. The computer program was written in ANSI C-language. The accuracy, efficiency and reliability of the MC method were validated by comparing the results generated by using the MC method with other benchmark theoretical results and experimental results with standard samples. Notably the MC method reported here is found to be stable even for very large spherical particles (size parameters > 1000) with large values of real (= 10) and imaginary part (= 10) of the refractive index. The promising field of application of the reported MC method will be in simulating the light (or electromagnetic) scattering properties of different types of planetary and interplanetary dust particles.

  10. Efficient scatter distribution estimation and correction in CBCT using concurrent Monte Carlo fitting

    SciTech Connect

    Bootsma, G. J.; Verhaegen, F.; Jaffray, D. A.

    2015-01-15

    Purpose: X-ray scatter is a significant impediment to image quality improvements in cone-beam CT (CBCT). The authors present and demonstrate a novel scatter correction algorithm using a scatter estimation method that simultaneously combines multiple Monte Carlo (MC) CBCT simulations through the use of a concurrently evaluated fitting function, referred to as concurrent MC fitting (CMCF). Methods: The CMCF method uses concurrently run MC CBCT scatter projection simulations that are a subset of the projection angles used in the projection set, P, to be corrected. The scattered photons reaching the detector in each MC simulation are simultaneously aggregated by an algorithm which computes the scatter detector response, S{sub MC}. S{sub MC} is fit to a function, S{sub F}, and if the fit of S{sub F} is within a specified goodness of fit (GOF), the simulations are terminated. The fit, S{sub F}, is then used to interpolate the scatter distribution over all pixel locations for every projection angle in the set P. The CMCF algorithm was tested using a frequency limited sum of sines and cosines as the fitting function on both simulated and measured data. The simulated data consisted of an anthropomorphic head and a pelvis phantom created from CT data, simulated with and without the use of a compensator. The measured data were a pelvis scan of a phantom and patient taken on an Elekta Synergy platform. The simulated data were used to evaluate various GOF metrics as well as determine a suitable fitness value. The simulated data were also used to quantitatively evaluate the image quality improvements provided by the CMCF method. A qualitative analysis was performed on the measured data by comparing the CMCF scatter corrected reconstruction to the original uncorrected and corrected by a constant scatter correction reconstruction, as well as a reconstruction created using a set of projections taken with a small cone angle. Results: Pearson’s correlation, r, proved to be a

  11. Solar Wind Halo Formation by the Scattering of the Strahl: Direct Cluster/PEACE Observations of the 3D Velocity Distribution Function

    NASA Astrophysics Data System (ADS)

    Vinas, A. F.; Gurgiolo, C. A.; Nieves-Chinchilla, T.; Wendel, D. E.; Goldstein, M. L.; Fazakerley, A. N.

    2010-12-01

    The current hypothesis of the formation of the solar wind halo electrons is that they are produced from scattering of the strahl. This hypothesis is strengthened by direct observations of the strahl electrons being scattered into the halo in an isolated event. On frequent occasions we have observed in electron angular skymaps (Phi/Theta-plots) of the electron 3D velocity distribution functions, a bursty-filament of particles connecting the strahl to the solar wind core-halo. These are seen over a limited energy range. The observation implies that the formation of the halo is not a continuous process but occurs in bursts in regions where conditions for wave growth providing the scattering are optimum. Sometimes, observations indicates that the strahl component is anisotropic (Tper/Tpal ~ 2). This provides a possible free energy source for the excitation of whistler waves as a possible scattering mechanism, however this condition is not always observed. The empirical observational evidence between the halo and the strahl suggests that the strahl population may be, at least in part, the source of the halo component.

  12. Reduction of double Rayleigh scattering noise in distributed Raman amplifiers employing higher-order pumping.

    PubMed

    Bolognini, Gabriele; Bononi, Alberto

    2009-04-27

    We present a theoretical study of the performance of distributed Raman amplifiers with higher order pumping schemes, focusing in particular on double Rayleigh scattering (DRS) noise. Results show an unexpected significant DRS noise reduction for pumping order higher than third, allowing for an overall performance improvement of carefully designed distributed amplifiers, ensuring a large optical signal-to-noise ratio improvement together with reduced DRS-induced penalties.

  13. Angular distributions of evaporated particles, fission and intermediate-mass fragments : on the search for consistent models

    NASA Astrophysics Data System (ADS)

    Alexander, J. M.

    During the last two years there has been a true cacophony concerning the meaning of experimental angular distributions for fission and fission-like fragments. The heavily used, saddle-point, transition-state model has been shown to be of limited value for high-spin systems, and a wide variety of proposals has appeared often with mutual inconsistencies and conflicting views. Even though equilibrium statistical models for fragment emission and particle evaporation must have a very close kinship, this relationship, often left as murky, has now come onto center stage for understanding reactions at ≽ 100 MeV. Basic questions concern the nature of the decision-point configurations, their degrees of freedom, the role of deformation and the relevant moments of inertia. This paper points out serious inconsistencies in several recent scission-point models and discusses conditions for applicability of saddle-point and scission-point approaches. Au cours des deux dernières années, l'interprétation des distributions angulaires de fragments a donné lieu à une véritable cacophonie. Les limitations du modèle courant considérant le point selle comme un état de transition sont apparues clairement pour les systèmes à haut spin, et une grande variété de remèdes prescntant souvent des incohérences mutuelles et des points de vue conflictuels ont été proposés. Même si les modèles décrivant l'émission de fragments ou de particules légères doivent nécessairement posséder une parente naturelle, cette relation, souvent laissée dans l'ombre, se trouve maintenant au centre de la compréhension des mécanismes de réactions lorsque les énergies d'excitation dépassent 100 MeV. Les questions primordiales concernent la nature des configurations critiques du point de vue de l'évolution ultérieure du système, de leurs degrés de liberté, du rôle de la déformation, et des moments d'inertie concernés. Cet article met en évidence de sérieuses incohérences dans

  14. Top-of-Atmosphere Albedo Estimation from Angular Distribution Models using Scene Identification from Satellite Cloud Property Retrievals

    NASA Technical Reports Server (NTRS)

    Loeb, N. G.; Parol, F.; Buriez, J.-C.; Vanbauce, C.

    2000-01-01

    The next generation of Earth radiation budget satellite instruments will routinely merge estimates of global top-of-atmosphere radiative fluxes with cloud properties. This information will offer many new opportunities for validating radiative transfer models and cloud parameterizations in climate models. In this study, five months of POLarization and Directionality of the Earth's Reflectances (POLDER) 670 nm radiance measurements are considered in order to examine how satellite cloud property retrievals can be used to define empirical Angular Distribution Models (ADMs) for estimating top-of-atmosphere (TOA) albedo. ADMs are defined for 19 scene types defined by satellite retrievals of cloud fraction and cloud optical depth. Two approaches are used to define the ADM scene types: The first assumes there are no biases in the retrieved cloud properties and defines ADMs for fixed discrete intervals of cloud fraction and cloud optical depth (fixed-tau approach). The second approach involves the same cloud fraction intervals, but uses percentile intervals of cloud optical depth instead (percentile-tau approach). Albedos generated using these methods are compared with albedos inferred directly from the mean observed reflectance field. Albedos based on ADMs that assume cloud properties are unbiased (fixed-tau approach) show a strong systematic dependence on viewing geometry. This dependence becomes more pronounced with increasing solar zenith angle, reaching approximately equals 12% (relative) between near-nadir and oblique viewing zenith angles for solar zenith angles between 60 deg and 70 deg. The cause for this bias is shown to be due to biases in the cloud optical depth retrievals. In contrast, albedos based on ADMs built using percentile intervals of cloud optical depth (percentile-tau approach) show very little viewing zenith angle dependence and are in good agreement with albedos obtained by direct integration of the mean observed reflectance field (less than 1

  15. The use of electron scattering for studying atomic momentum distributions: the case of graphite and diamond.

    PubMed

    Vos, M; Moreh, R; Tokési, K

    2011-07-14

    The momentum distributions of C atoms in polycrystalline diamond (produced by chemical vapor deposition) and in highly oriented pyrolitic graphite (HOPG) are studied by scattering of 40 keV electrons at 135°. By measuring the Doppler broadening of the energy of the elastically scattered electrons, we resolve a Compton profile of the motion of the C atoms. The aim of the present work is to resolve long-standing disagreements between the calculated kinetic energies of carbon atoms in HOPG and in diamond films and the measured ones, obtained both by neutron Compton scattering (NCS) and by nuclear resonance photon scattering (NRPS). The anisotropy of the momentum distribution in HOPG was measured by rotating the HOPG sample relative to the electron beam. The obtained kinetic energies for the motion component along, and perpendicular to, the graphite planes were somewhat higher than those obtained from the most recent NCS data of HOPG. Monte Carlo simulations indicate that multiple scattering adds about 2% to the obtained kinetic energies. The presence of different isotopes in carbon affects the measurement at a 1% level. After correcting for these contributions, the kinetic energies are 3%-6% larger than the most recent NCS results for HOPG, but 15%-25% smaller than the NRPS results. For diamond, the corrected direction-averaged kinetic energy is ≈ 6% larger than the calculated value. This compares favorably to the ≈25% discrepancy between theory and both the NCS and NRPS results for diamond.

  16. Sky Radiance Distributions for Thermal Imaging Backgrounds.

    DTIC Science & Technology

    1987-12-01

    Monte Carlo selection we pick the scattering angle using the Henyey - Greenstein function ...its albedo and its scattering phase function . 2. The photon propagating through the cloud for a distance R, determined by a Monte Carlo selection...Scattering Model: This model calculates the angular distribution of the clouds by using the phase p function presented by Henyey and Greenstein [Ref.20

  17. Measurement of the angular distribution of electrons from W-->eν decays observed in pp¯ collisions at s=1.8 TeV

    NASA Astrophysics Data System (ADS)

    Abbott, B.; Abolins, M.; Abramov, V.; Acharya, B. S.; Adams, D. L.; Adams, M.; Alves, G. A.; Amos, N.; Anderson, E. W.; Baarmand, M. M.; Babintsev, V. V.; Babukhadia, L.; Baden, A.; Baldin, B.; Balm, P. W.; Banerjee, S.; Bantly, J.; Barberis, E.; Baringer, P.; Bartlett, J. F.; Bassler, U.; Bean, A.; Begel, M.; Belyaev, A.; Beri, S. B.; Bernardi, G.; Bertram, I.; Besson, A.; Bezzubov, V. A.; Bhat, P. C.; Bhatnagar, V.; Bhattacharjee, M.; Blazey, G.; Blessing, S.; Boehnlein, A.; Bojko, N. I.; Borcherding, F.; Brandt, A.; Breedon, R.; Briskin, G.; Brock, R.; Brooijmans, G.; Bross, A.; Buchholz, D.; Buehler, M.; Buescher, V.; Burtovoi, V. S.; Butler, J. M.; Canelli, F.; Carvalho, W.; Casey, D.; Casilum, Z.; Castilla-Valdez, H.; Chakraborty, D.; Chan, K. M.; Chekulaev, S. V.; Cho, D. K.; Choi, S.; Chopra, S.; Christenson, J. H.; Chung, M.; Claes, D.; Clark, A. R.; Cochran, J.; Coney, L.; Connolly, B.; Cooper, W. E.; Coppage, D.; Cummings, M. A.; Cutts, D.; Dahl, O. I.; Davis, G. A.; Davis, K.; de, K.; del Signore, K.; Demarteau, M.; Demina, R.; Demine, P.; Denisov, D.; Denisov, S. P.; Desai, S.; Diehl, H. T.; Diesburg, M.; di Loreto, G.; Doulas, S.; Draper, P.; Ducros, Y.; Dudko, L. V.; Duensing, S.; Dugad, S. R.; Dyshkant, A.; Edmunds, D.; Ellison, J.; Elvira, V. D.; Engelmann, R.; Eno, S.; Eppley, G.; Ermolov, P.; Eroshin, O. V.; Estrada, J.; Evans, H.; Evdokimov, V. N.; Fahland, T.; Feher, S.; Fein, D.; Ferbel, T.; Fisk, H. E.; Fisyak, Y.; Flattum, E.; Fleuret, F.; Fortner, M.; Frame, K. C.; Fuess, S.; Gallas, E.; Galyaev, A. N.; Gartung, P.; Gavrilov, V.; Genik, R. J.; Genser, K.; Gerber, C. E.; Gershtein, Y.; Gibbard, B.; Gilmartin, R.; Ginther, G.; Gómez, B.; Gómez, G.; Goncharov, P. I.; González Solís, J. L.; Gordon, H.; Goss, L. T.; Gounder, K.; Goussiou, A.; Graf, N.; Graham, G.; Grannis, P. D.; Green, J. A.; Greenlee, H.; Grinstein, S.; Groer, L.; Grudberg, P.; Grünendahl, S.; Gupta, A.; Gurzhiev, S. N.; Gutierrez, G.; Gutierrez, P.; Hadley, N. J.; Haggerty, H.; Hagopian, S.; Hagopian, V.; Hahn, K. S.; Hall, R. E.; Hanlet, P.; Hansen, S.; Hauptman, J. M.; Hays, C.; Hebert, C.; Hedin, D.; Heinson, A. P.; Heintz, U.; Heuring, T.; Hirosky, R.; Hobbs, J. D.; Hoeneisen, B.; Hoftun, J. S.; Hou, S.; Huang, Y.; Ito, A. S.; Jerger, S. A.; Jesik, R.; Johns, K.; Johnson, M.; Jonckheere, A.; Jones, M.; Jöstlein, H.; Juste, A.; Kahn, S.; Kajfasz, E.; Karmanov, D.; Karmgard, D.; Kehoe, R.; Kim, S. K.; Klima, B.; Klopfenstein, C.; Knuteson, B.; Ko, W.; Kohli, J. M.; Kostritskiy, A. V.; Kotcher, J.; Kotwal, A. V.; Kozelov, A. V.; Kozlovsky, E. A.; Krane, J.; Krishnaswamy, M. R.; Krzywdzinski, S.; Kubantsev, M.; Kuleshov, S.; Kulik, Y.; Kunori, S.; Kuznetsov, V. E.; Landsberg, G.; Leflat, A.; Lehner, F.; Li, J.; Li, Q. Z.; Lima, J. G.; Lincoln, D.; Linn, S. L.; Linnemann, J.; Lipton, R.; Lucotte, A.; Lueking, L.; Lundstedt, C.; Maciel, A. K.; Madaras, R. J.; Manankov, V.; Mao, H. S.; Marshall, T.; Martin, M. I.; Martin, R. D.; Mauritz, K. M.; May, B.; Mayorov, A. A.; McCarthy, R.; McDonald, J.; McMahon, T.; Melanson, H. L.; Meng, X. C.; Merkin, M.; Merritt, K. W.; Miao, C.; Miettinen, H.; Mihalcea, D.; Mincer, A.; Mishra, C. S.; Mokhov, N.; Mondal, N. K.; Montgomery, H. E.; Moore, R. W.; Mostafa, M.; da Motta, H.; Nagy, E.; Nang, F.; Narain, M.; Narasimham, V. S.; Neal, H. A.; Negret, J. P.; Negroni, S.; Norman, D.; Oesch, L.; Oguri, V.; Olivier, B.; Oshima, N.; Padley, P.; Pan, L. J.; Para, A.; Parashar, N.; Partridge, R.; Parua, N.; Paterno, M.; Patwa, A.; Pawlik, B.; Perkins, J.; Peters, M.; Peters, O.; Piegaia, R.; Piekarz, H.; Pope, B. G.; Popkov, E.; Prosper, H. B.; Protopopescu, S.; Qian, J.; Quintas, P. Z.; Raja, R.; Rajagopalan, S.; Ramberg, E.; Rapidis, P. A.; Reay, N. W.; Reucroft, S.; Rha, J.; Rijssenbeek, M.; Rockwell, T.; Roco, M.; Rubinov, P.; Ruchti, R.; Rutherfoord, J.; Santoro, A.; Sawyer, L.; Schamberger, R. D.; Schellman, H.; Schwartzman, A.; Sculli, J.; Sen, N.; Shabalina, E.; Shankar, H. C.; Shivpuri, R. K.; Shpakov, D.; Shupe, M.; Sidwell, R. A.; Simak, V.; Singh, H.; Singh, J. B.; Sirotenko, V.; Slattery, P.; Smith, E.; Smith, R. P.; Snihur, R.; Snow, G. R.; Snow, J.; Snyder, S.; Solomon, J.; Sorín, V.; Sosebee, M.; Sotnikova, N.; Soustruznik, K.; Souza, M.; Stanton, N. R.; Steinbrück, G.; Stephens, R. W.; Stevenson, M. L.; Stichelbaut, F.; Stoker, D.; Stolin, V.; Stoyanova, D. A.; Strauss, M.; Streets, K.; Strovink, M.; Stutte, L.; Sznajder, A.; Taylor, W.; Tentindo-Repond, S.; Thompson, J.; Toback, D.; Tripathi, S. M.; Trippe, T. G.; Turcot, A. S.; Tuts, P. M.; van Gemmeren, P.; Vaniev, V.; van Kooten, R.; Varelas, N.; Volkov, A. A.; Vorobiev, A. P.; Wahl, H. D.; Wang, H.; Wang, Z.-M.; Warchol, J.; Watts, G.; Wayne, M.; Weerts, H.; White, A.; White, J. T.; Whiteson, D.; Wightman, J. A.; Wijngaarden, D. A.; Willis, S.; Wimpenny, S. J.; Wirjawan, J. V.; Womersley, J.; Wood, D. R.; Yamada, R.; Yamin, P.; Yasuda, T.; Yip, K.; Youssef, S.; Yu, J.; Yu, Z.; Zanabria, M.; Zheng, H.; Zhou, Z.; Zhu, Z. H.; Zielinski, M.; Zieminska, D.; Zieminski, A.; Zutshi, V.; Zverev, E. G.; Zylberstejn, A.

    2001-04-01

    We present the first measurement of the electron angular distribution parameter α2 in W-->eν events produced in proton-antiproton collisions as a function of the W boson transverse momentum. Our analysis is based on data collected using the DØ detector during the 1994-1995 Fermilab Tevatron run. We compare our results with next-to-leading order perturbative QCD, which predicts an angular distribution of (1+/-α1 cos θ*+α2 cos2 θ*), where θ* is the polar angle of the electron in the Collins-Soper frame. In the presence of QCD corrections, the parameters α1 and α2 become functions of pWT, the W boson transverse momentum. This measurement provides a test of next-to-leading order QCD corrections which are a non-negligible contribution to the W boson mass measurement.

  18. Theoretical study of inner-shell electron-impact excitation of highly charged ions: Alignment and angular distribution of electron emission

    NASA Astrophysics Data System (ADS)

    Shi, Y. L.; Dong, C. Z.; Ma, X. Y.; Wu, Z. W.; Xie, L. Y.

    2014-04-01

    The influence of the Breit interaction, typically appears as a relativistic correction to the Coulomb repulsion acting among the electrons, on the alignment (i.e. the population of the magnetic sublevels) and the angular distribution of electron emission from the excited state have been investigated systematically. Detailed calculations have been carried out for the electron-impact excitation cross sections from the ground state to the individual magnetic sublevels of highly charged beryllium-like ions by using a fully relativistic distorted-wave (RDW) method. A remarkable change in the alignment and the electron angular distribution due to the Breit interaction is found, especially for the cases with high-energetic incident electron and high-Z target ions.

  19. Off-resonance photoemission dynamics studied by recoil frame F1s and C1s photoelectron angular distributions of CH{sub 3}F

    SciTech Connect

    Stener, M. Decleva, P.; Mizuno, T.; Yagishita, A.; Yoshida, H.

    2014-01-28

    F1s and C1s photoelectron angular distributions are considered for CH{sub 3}F, a molecule which does not support any shape resonance. In spite of the absence of features in the photoionization cross section profile, the recoil frame photoelectron angular distributions (RFPADs) exhibits dramatic changes depending on both the photoelectron energy and polarization geometry. Time-dependent density functional theory calculations are also given to rationalize the photoionization dynamics. The RFPADs have been compared with the theoretical calculations, in order to assess the accuracy of the theoretical method and rationalize the experimental findings. The effect of finite acceptance angles for both ionic fragments and photoelectrons has been included in the calculations, as well as the effect of rotational averaging around the fragmentation axis. Excellent agreement between theory and experiment is obtained, confirming the good quality of the calculated dynamical quantities (dipole moments and phase shifts)

  20. Search for New Phenomena in Dijet Angular Distributions in Proton-Proton Collisions at s = 8 TeV Measured with the ATLAS Detector

    DOE PAGES

    Aad, G.; Abbott, B.; Abdallah, J.; ...

    2015-06-04

    A search for new phenomena in LHC proton-proton collisions at a center-of-mass energy of √s=8 TeV was performed with the ATLAS detector using an integrated luminosity of 17.3 fb⁻¹. The angular distributions are studied in events with at least two jets; the highest dijet mass observed is 5.5 TeV. All angular distributions are consistent with the predictions of the standard model. In a benchmark model of quark contact interactions, a compositeness scale below 8.1 TeV in a destructive interference scenario and 12.0 TeV in a constructive interference scenario is excluded at 95% C.L.; median expected limits are 8.9 TeV formore » the destructive interference scenario and 14.1 TeV for the constructive interference scenario.« less

  1. Measurement of dijet angular distributions at square root(s) = 1.96 TeV and searches for quark compositeness and extra spatial dimensions.

    PubMed

    Abazov, V M; Abbott, B; Abolins, M; Acharya, B S; Adams, M; Adams, T; Aguilo, E; Ahsan, M; Alexeev, G D; Alkhazov, G; Alton, A; Alverson, G; Alves, G A; Ancu, L S; Andeen, T; Anzelc, M S; Aoki, M; Arnoud, Y; Arov, M; Arthaud, M; Askew, A; Asman, B; Atramentov, O; Avila, C; BackusMayes, J; Badaud, F; Bagby, L; Baldin, B; Bandurin, D V; Banerjee, S; Barberis, E; Barfuss, A-F; Bargassa, P; Baringer, P; Barreto, J; Bartlett, J F; Bassler, U; Bauer, D; Beale, S; Bean, A; Begalli, M; Begel, M; Belanger-Champagne, C; Bellantoni, L; Bellavance, A; Benitez, J A; Beri, S B; Bernardi, G; Bernhard, R; Bertram, I; Besançon, M; Beuselinck, R; Bezzubov, V A; Bhat, P C; Bhatnagar, V; Blazey, G; Blessing, S; Bloom, K; Boehnlein, A; Boline, D; Bolton, T A; Boos, E E; Borissov, G; Bose, T; Brandt, A; Brock, R; Brooijmans, G; Bross, A; Brown, D; Bu, X B; Buchholz, D; Buehler, M; Buescher, V; Bunichev, V; Burdin, S; Burnett, T H; Buszello, C P; Calfayan, P; Calpas, B; Calvet, S; Cammin, J; Carrasco-Lizarraga, M A; 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    2009-11-06

    We present the first measurement of dijet angular distributions in pp collisions at square root(s) = 1.96 TeV at the Fermilab Tevatron Collider. The measurement is based on a dataset corresponding to an integrated luminosity of 0.7 fb(-1) collected with the D0 detector. Dijet angular distributions have been measured over a range of dijet masses, from 0.25 TeV to above 1.1 TeV. The data are in good agreement with the predictions of perturbative QCD and are used to constrain new physics models including quark compositeness, large extra dimensions, and TeV(-1) scale extra dimensions. For all models considered, we set the most stringent direct limits to date.

  2. Measurement of dijet angular distributions at sqrt{s}=1.96TeV and searches for quark compositeness and extra spatial dimensions

    SciTech Connect

    Collaboration, D0

    2009-06-01

    We present the first measurement of dijet angular distributions in p{bar p} collisions at {radical}s = 1.96 TeV at the Fermilab Tevatron Collider. The measurement is based on a dataset corresponding to an integrated luminosity of 0.7 fb{sup -1} collected with the D0 detector. Dijet angular distributions have been measured over a range of dijet masses, from 0.25 TeV to above 1.1 TeV. The data are in good agreement with the predictions of perturbative QCD and are used to constrain new physics models including quark compositeness, large extra dimensions, and TeV{sup -1} scale extra dimensions. For all models considered, we set the most stringent direct limits to date.

  3. Search for New Phenomena in Dijet Angular Distributions in Proton-Proton Collisions at sqrt[s]=8 TeV Measured with the ATLAS Detector.

    PubMed

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Robinson, D; Robinson, J E M; Robson, A; Roda, C; Roe, S; Røhne, O; Rolli, S; Romaniouk, A; Romano, M; Romano Saez, S M; Romero Adam, E; Rompotis, N; Ronzani, M; Roos, L; Ros, E; Rosati, S; Rosbach, K; Rose, P; Rosendahl, P L; Rosenthal, O; Rossetti, V; Rossi, E; Rossi, L P; Rosten, R; Rotaru, M; Roth, I; Rothberg, J; Rousseau, D; Royon, C R; Rozanov, A; Rozen, Y; Ruan, X; Rubbo, F; Rubinskiy, I; Rud, V I; Rudolph, C; Rudolph, M S; Rühr, F; Ruiz-Martinez, A; Rurikova, Z; Rusakovich, N A; Ruschke, A; Russell, H L; Rutherfoord, J P; Ruthmann, N; Ryabov, Y F; Rybar, M; Rybkin, G; Ryder, N C; Saavedra, A F; Sabato, G; Sacerdoti, S; Saddique, A; Sadrozinski, H F-W; Sadykov, R; Safai Tehrani, F; Saimpert, M; Sakamoto, H; Sakurai, Y; Salamanna, G; Salamon, A; Saleem, M; Salek, D; Sales De Bruin, P H; Salihagic, D; Salnikov, A; Salt, J; Salvatore, D; Salvatore, F; Salvucci, A; Salzburger, A; Sampsonidis, D; Sanchez, A; Sánchez, J; Sanchez Martinez, V; Sandaker, H; Sandbach, R L; Sander, H G; Sanders, M P; 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Tassi, E; Tavares Delgado, A; Tayalati, Y; Taylor, F E; Taylor, G N; Taylor, W; Teischinger, F A; Teixeira Dias Castanheira, M; Teixeira-Dias, P; Temming, K K; Ten Kate, H; Teng, P K; Teoh, J J; Tepel, F; Terada, S; Terashi, K; Terron, J; Terzo, S; Testa, M; Teuscher, R J; Therhaag, J; Theveneaux-Pelzer, T; Thomas, J P; Thomas-Wilsker, J; Thompson, E N; Thompson, P D; Thompson, R J; Thompson, A S; Thomsen, L A; Thomson, E; Thomson, M; Thun, R P; Tibbetts, M J; Ticse Torres, R E; Tikhomirov, V O; Tikhonov, Yu A; Timoshenko, S; Tiouchichine, E; Tipton, P; Tisserant, S; Todorov, T; Todorova-Nova, S; Tojo, J; Tokár, S; Tokushuku, K; Tollefson, K; Tolley, E; Tomlinson, L; Tomoto, M; Tompkins, L; Toms, K; Torrence, E; Torres, H; Torró Pastor, E; Toth, J; Touchard, F; Tovey, D R; Trefzger, T; Tremblet, L; Tricoli, A; Trigger, I M; Trincaz-Duvoid, S; Tripiana, M F; Trischuk, W; Trocmé, B; Troncon, C; Trottier-McDonald, M; Trovatelli, M; True, P; Truong, L; Trzebinski, M; Trzupek, A; Tsarouchas, C; Tseng, J C-L; Tsiareshka, P V; Tsionou, D; Tsipolitis, G; Tsirintanis, N; Tsiskaridze, S; Tsiskaridze, V; Tskhadadze, E G; Tsukerman, I I; Tsulaia, V; Tsuno, S; Tsybychev, D; Tudorache, A; Tudorache, V; Tuna, A N; Tupputi, S A; Turchikhin, S; Turecek, D; Turra, R; Turvey, A J; Tuts, P M; Tykhonov, A; Tylmad, M; Tyndel, M; Ueda, I; Ueno, R; Ughetto, M; Ugland, M; Uhlenbrock, M; Ukegawa, F; Unal, G; Undrus, A; Unel, G; Ungaro, F C; Unno, Y; Unverdorben, C; Urban, J; Urquijo, P; Urrejola, P; Usai, G; Usanova, A; Vacavant, L; Vacek, V; Vachon, B; Valderanis, C; Valencic, N; Valentinetti, S; Valero, A; Valery, L; Valkar, S; Valladolid Gallego, E; Vallecorsa, S; Valls Ferrer, J A; Van Den Wollenberg, W; Van Der Deijl, P C; van der Geer, R; van der Graaf, H; Van Der Leeuw, R; van Eldik, N; van Gemmeren, P; Van Nieuwkoop, J; van Vulpen, I; van Woerden, M C; Vanadia, M; Vandelli, W; Vanguri, R; Vaniachine, A; Vannucci, F; Vardanyan, G; Vari, R; Varnes, E W; Varol, T; Varouchas, D; Vartapetian, A; 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Yao, W-M; Yasu, Y; Yatsenko, E; Yau Wong, K H; Ye, J; Ye, S; Yeletskikh, I; Yen, A L; Yildirim, E; Yorita, K; Yoshida, R; Yoshihara, K; Young, C; Young, C J S; Youssef, S; Yu, D R; Yu, J; Yu, J M; Yu, J; Yuan, L; Yurkewicz, A; Yusuff, I; Zabinski, B; Zaidan, R; Zaitsev, A M; Zalieckas, J; Zaman, A; Zambito, S; Zanello, L; Zanzi, D; Zeitnitz, C; Zeman, M; Zemla, A; Zengel, K; Zenin, O; Ženiš, T; Zerwas, D; Zhang, D; Zhang, F; Zhang, J; Zhang, L; Zhang, R; Zhang, X; Zhang, Z; Zhao, X; Zhao, Y; Zhao, Z; Zhemchugov, A; Zhong, J; Zhou, B; Zhou, C; Zhou, L; Zhou, L; Zhou, N; Zhu, C G; Zhu, H; Zhu, J; Zhu, Y; Zhuang, X; Zhukov, K; Zibell, A; Zieminska, D; Zimine, N I; Zimmermann, C; Zimmermann, S; Zinonos, Z; Zinser, M; Ziolkowski, M; Živković, L; Zobernig, G; Zoccoli, A; Zur Nedden, M; Zurzolo, G; Zwalinski, L

    2015-06-05

    A search for new phenomena in LHC proton-proton collisions at a center-of-mass energy of sqrt[s]=8 TeV was performed with the ATLAS detector using an integrated luminosity of 17.3 fb^{-1}. The angular distributions are studied in events with at least two jets; the highest dijet mass observed is 5.5 TeV. All angular distributions are consistent with the predictions of the standard model. In a benchmark model of quark contact interactions, a compositeness scale below 8.1 TeV in a destructive interference scenario and 12.0 TeV in a constructive interference scenario is excluded at 95% C.L.; median expected limits are 8.9 TeV for the destructive interference scenario and 14.1 TeV for the constructive interference scenario.

  4. Filtering reaction dynamics using nearside-farside theory and local angular momentum theory: application to the angular scattering of the H + D2(v(i) = 0, j(i) = 0) --> HD(v(f) = 3, j(f) = 0) + D reaction in the energy and time domains.

    PubMed

    Monks, P D D; Connor, J N L; Bouakline, F

    2009-04-23

    We investigate methods for filtering reaction mechanisms in the angular scattering of the state-to-state reaction, H + D(2)(v(i) = 0, j(i) = 0, m(i) = 0) --> HD(v(f) = 3, j(f) = 0, m(f) = 0) + D, where v(i), j(i), and m(i) and v(f), j(f), and m(f) are initial and final vibrational, rotational, and helicity quantum numbers, respectively. The input to our filtrations is a new set of accurate quantum scattering matrix elements for total energies in the range 1.52-2.50 eV (in steps of 0.01 eV) and for total angular momentum quantum numbers in the range, 0-40, in steps of unity. We filter reaction mechanisms in both the energy domain and the time domain. The time-domain calculations employ the plane wave packet formulation of time-dependent scattering. The theoretical tools used are nearside-farside (NF) analysis of partial wave series for scattering amplitudes, together with NF local angular momentum (LAM) theory. An energy-domain LAM analysis reveals the existence of an important dynamical feature in the N scattering, a "trench" which bisects the (energy, angle) plane. We use the location of this trench to approximately filter two reaction mechanisms. Transformation to the time domain demonstrates that the two reaction mechanisms correspond to direct and delayed (by about 25 fs) scattering. Further analysis, including filtration in the time domain, shows that the pronounced LAM trench arises from the interference of the energy-domain analogues of the time-direct and time-delayed scattering. Our theory and results provide the first successful demonstration of reaction mechanism filtering carried out directly in the (energy, angle) domain. The calculations and results in this paper extend and complement earlier research reported by Monks, Connor, and Althorpe (Monks, P. D. D.; Connor, J. N. L.; Althorpe, S. C. J. Phys. Chem. A 2006, 110, 741; J. Phys. Chem. A 2007, 111, 10302).

  5. Resonant structure of the 3d electron`s angular distribution in a free Mn{sup +}Ion

    SciTech Connect

    Amusia, M.Y.; Dolmatov, V.K.

    1995-08-01

    The 3d-electron angular anisotropy parameter of the free Mn{sup +} ion is calculated using the {open_quotes}spin-polarized{close_quotes} random-phase approximation with exchange. Strong resonance structure is discovered, which is due to interference with the powerful 3p {yields} 3d discrete excitation. The effect of the 3p {yields} 4s transition is also noticeable. The ordering of these respective resonances with phonon energy increase proved to be opposite in angular anisotropy parameter to that in 3d-photoionization cross section. A paper describing these results was published.

  6. Vector correlation analysis for inelastic and reactive collisions between partners possessing spin and orbital angular momentum.

    PubMed

    Balint-Kurti, Gabriel G; Vasyutinskii, Oleg S

    2009-12-31

    A general reactive collision of the type A + B --> C + D is considered where both the collision partners (A and B) or the products (C and D) may possess internal, i.e., spin, orbital or rotational, angular momenta. Compact expressions are derived using a rigorous quantum mechanical analysis for the angular momentum anisotropy of either of the products (C or D) arising from an initially polarized distribution of the reactant angular momentum. The angular momentum distribution of the product is expressed in terms of canonical spherical tensors multiplied by anisotropy-transforming coefficients c(K(i)q(k))(K)(K(r),L). These coefficients act as transformation coefficients between the angular momentum anisotropy of the reactants and that of the product. They are independent of scattering angle but depend on the details of the scattering dynamics. The relationship between the coefficients c(K(i)q(k))(K)(K(r),L) and the body-fixed scattering S matrix is given and the methodology for the quantum mechanical calculation of the anisotropy-transforming coefficients is clearly laid out. The anisotropy-transforming coefficients are amenable to direct experimental measurement in a similar manner to vector correlation and alignment parameters in photodissociation processes. A key aspect of the theory is the use of projections of both reactant and product angular momenta onto the product recoil vector direction. An important new conservation rule is revealed through the analysis, namely that if the state multipole for reactant angular momentum distribution has a projection q(k) onto the product recoil vector the state multipoles for the product angular momentum distribution all have this same projection. Expressions are also presented for the distribution of the product angular momentum when its components are evaluated relative to the space-fixed Z-axis. Notes with detailed derivations of all the formulas are available as Supporting Information.

  7. Monte Carlo modeling of coherent scattering: Influence of interference

    SciTech Connect

    Leliveld, C.J.; Maas, J.G.; Bom, V.R.; Eijk, C.W.E. van

    1996-12-01

    In this study, the authors present Monte Carlo (MC) simulation results for the intensity and angular distribution of scattered radiation from cylindrical absorbers. For coherent scattering the authors have taken into account the effects of interference by using new molecular form factor data for the AAPM plastic materials and water. The form factor data were compiled from X-ray diffraction measurements. The new data have been implemented in the authors` Electron Gamma Shower (EGS4) Monte Carlo system. The hybrid MC simulation results show a significant influence on the intensity and the angular distribution of coherently scattered photons. They conclude that MC calculations are significantly in error when interference effects are ignored in the model for coherent scattering. Especially for simulation studies of scattered radiation in collimated geometries, where small angle scattering will prevail, the coherent scatter contribution is highly overestimated when conventional form factor data are used.

  8. Characterizing the space of interatomic distance distribution functions consistent with solution scattering data.

    PubMed

    Kavathekar, Paritosh A; Craig, Bruce A; Friedman, Alan M; Bailey-Kellogg, Chris; Balkcom, Devin J

    2010-04-01

    Scattering of neutrons and X-rays from molecules in solution offers alternative approaches to the study of a wide range of macromolecular structures in their solution state without crystallization. We study one part of the problem of elucidating three-dimensional structure from solution scattering data, determining the distribution of interatomic distances, P(r), where r is the distance between two atoms in the protein molecule. This problem is known to be ill-conditioned: for a single observed diffraction pattern, there may be many consistent distance distribution functions, and there is a risk of overfitting the observed scattering data. We propose a new approach to avoiding this problem: accepting the validity of multiple alternative P(r) curves rather than seeking a single "best." We place linear constraints to ensure that a computed P(r) is consistent with the experimental data. The constraints enforce smoothness in the P(r) curve, ensure that the P(r) curve is a probability distribution, and allow for experimental error. We use these constraints to precisely describe the space of all consistent P(r) curves as a polytope of histogram values or Fourier coefficients. We develop a linear programming approach to sampling the space of consistent, realistic P(r) curves. On both experimental and simulated scattering data, our approach efficiently generates ensembles of such curves that display substantial diversity.

  9. An unambiguous signature in molecular frame photoelectron angular distributions of core hole localization in fluorine K-edge photoionization of CF4

    NASA Astrophysics Data System (ADS)

    McCurdy, C. W.; Rescigno, T. N.; Trevisan, C. S.; Lucchese, R. R.

    2016-05-01

    Molecular Frame Photoelectron Angular Distributions (MFPADs) are calculated using the Complex Kohn variational method for core-hole ionization of the carbon and fluorines in CF4 at photoelectron energies below 15 eV. The angular distributions for localized versus delocalized core-hole creation on the four equivalent fluorines are radically different. A strong propensity for the dissociation to take place via the mechanism hν +CF4 -->CF 4 + +e- -->CF 3 + +F(1s-1) -->CF 3 + +F+ + 2e- in which a core excited neutral fluorine atom ionizes during or after dissociation creates the conditions for experimental observation of core hole localization. Comparison with recent unpublished experiments at the Advanced Light Source that measured the Recoil Frame Photoelectron Angular Distributions (averaged over CF3 rotations around the recoil axis) for fluorine K-edge ionization gives unambiguous evidence that these experiments directly observed the creation of an almost completely localized core hole on the dissociating fluorine atom when the molecule was initially photoionized. Work supported by USDOE, OBES Chemical Sciences, Geosciences, and Biosciences Division.

  10. Angular distributions of absorbed dose of Bremsstrahlung and secondary electrons induced by 18-, 28- and 38-MeV electron beams in thick targets.

    PubMed

    Takada, Masashi; Kosako, Kazuaki; Oishi, Koji; Nakamura, Takashi; Sato, Kouichi; Kamiyama, Takashi; Kiyanagi, Yoshiaki

    2013-03-01

    Angular distributions of absorbed dose of Bremsstrahlung photons and secondary electrons at a wide range of emission angles from 0 to 135°, were experimentally obtained using an ion chamber with a 0.6 cm(3) air volume covered with or without a build-up cap. The Bremsstrahlung photons and electrons were produced by 18-, 28- and 38-MeV electron beams bombarding tungsten, copper, aluminium and carbon targets. The absorbed doses were also calculated from simulated photon and electron energy spectra by multiplying simulated response functions of the ion chambers, simulated with the MCNPX code. Calculated-to-experimental (C/E) dose ratios obtained are from 0.70 to 1.57 for high-Z targets of W and Cu, from 15 to 135° and the C/E range from 0.6 to 1.4 at 0°; however, the values of C/E for low-Z targets of Al and C are from 0.5 to 1.8 from 0 to 135°. Angular distributions at the forward angles decrease with increasing angles; on the other hand, the angular distributions at the backward angles depend on the target species. The dependences of absorbed doses on electron energy and target thickness were compared between the measured and simulated results. The attenuation profiles of absorbed doses of Bremsstrahlung beams at 0, 30 and 135° were also measured.

  11. Swimming speed distributions of bull spermatozoa as determined by quasi-elastic light scattering.

    PubMed Central

    Hallett, F R; Craig, T; Marsh, J

    1978-01-01

    88 semen samples from 39 bulls have been investigated by the quasi-elastic light scattering technique. Normal, defective, and dead cells each yielded characteristic autocorrelation functions. The form of these functions indicates that the swimming speed distribution of normal cells is a gamma distribution with two degrees of freedom while that for defective or circular swimmers is a gamma distribution with one degree of freedom. The resulting analysis of the experimental autocorrelation functions yields the fraction of the sample that is normal, the fraction that is defective, and the average speed of each group. The average helical swimming speed of normal cells was found to be 384 micron/s, while the average trajectory speed of the circular swimmers was found to be 103 micron/s. The overall quality of the semen samples as determined by light scattering is compared to quality determination on the same samples by technicians from the artificial insemination industry. PMID:630041

  12. Reconstruction evaluation of intensity ratio distribution for extraction of absorber information in homogeneous scattering medium

    NASA Astrophysics Data System (ADS)

    Yamaoki, Toshihiko; Matoba, Osamu

    2016-02-01

    To extract effectively the absorber information embedded in a homogeneous scattering medium in the transmission geometry, a method of taking the ratio of the output intensity in a measured medium to that in a reference medium is evaluated. The reference medium is a virtual one with the same scattering coefficient distribution as that of the measured medium, but with a uniform absorption coefficient distribution. Numerical results show that the proposed method can enhance the output signal by extracting the ballistic-like component. We also apply a backprojection method to reconstruct the single absorber using many pairs of input and output intensity ratio distributions. The reconstruction position error and the quantitative measurement of absorption coefficient are discussed.

  13. Free-space measurement-device-independent quantum-key-distribution protocol using decoy states with orbital angular momentum

    NASA Astrophysics Data System (ADS)

    Wang, Le; Zhao, Sheng-Mei; Gong, Long-Yan; Cheng, Wei-Wen

    2015-12-01

    In this paper, we propose a measurement-device-independent quantum-key-distribution (MDI-QKD) protocol using orbital angular momentum (OAM) in free space links, named the OAM-MDI-QKD protocol. In the proposed protocol, the OAM states of photons, instead of polarization states, are used as the information carriers to avoid the reference frame alignment, the decoy-state is adopted to overcome the security loophole caused by the weak coherent pulse source, and the high efficient OAM-sorter is adopted as the measurement tool for Charlie to obtain the output OAM state. Here, Charlie may be an untrusted third party. The results show that the authorized users, Alice and Bob, could distill a secret key with Charlie’s successful measurements, and the key generation performance is slightly better than that of the polarization-based MDI-QKD protocol in the two-dimensional OAM cases. Simultaneously, Alice and Bob can reduce the number of flipping the bits in the secure key distillation. It is indicated that a higher key generation rate performance could be obtained by a high dimensional OAM-MDI-QKD protocol because of the unlimited degree of freedom on OAM states. Moreover, the results show that the key generation rate and the transmission distance will decrease as the growth of the strength of atmospheric turbulence (AT) and the link attenuation. In addition, the decoy states used in the proposed protocol can get a considerable good performance without the need for an ideal source. Project supported by the National Natural Science Foundation of China (Grant Nos. 61271238 and 61475075), the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20123223110003), the Natural Science Research Foundation for Universities of Jiangsu Province of China (Grant No. 11KJA510002), the Open Research Fund of Key Laboratory of Broadband Wireless Communication and Sensor Network Technology, Ministry of Education, China (Grant No. NYKL2015011), and the

  14. Next-Generation Angular Distribution Models for Top-of-Atmosphere Radiative Flux Calculation from the CERES Instruments: Methodology

    NASA Technical Reports Server (NTRS)

    Su, W.; Corbett, J.; Eitzen, Z.; Liang, L.

    2015-01-01

    The top-of-atmosphere (TOA) radiative fluxes are critical components to advancing our understanding of the Earth's radiative energy balance, radiative effects of clouds and aerosols, and climate feedback. The Clouds and the Earth's Radiant Energy System (CERES) instruments provide broadband shortwave and longwave radiance measurements. These radiances are converted to fluxes by using scene-type-dependent angular distribution models (ADMs). This paper describes the next-generation ADMs that are developed for Terra and Aqua using all available CERES rotating azimuth plane radiance measurements. Coincident cloud and aerosol retrievals, and radiance measurements from the Moderate Resolution Imaging Spectroradiometer (MODIS), and meteorological parameters from Goddard Earth Observing System (GEOS) data assimilation version 5.4.1 are used to define scene type. CERES radiance measurements are stratified by scene type and by other parameters that are important for determining the anisotropy of the given scene type. Anisotropic factors are then defined either for discrete intervals of relevant parameters or as a continuous functions of combined parameters, depending on the scene type. Significant differences between the ADMs described in this paper and the existing ADMs are over clear-sky scene types and polar scene types. Over clear ocean, we developed a set of shortwave (SW) ADMs that explicitly account for aerosols. Over clear land, the SW ADMs are developed for every 1 latitude1 longitude region for every calendar month using a kernel-based bidirectional reflectance model. Over clear Antarctic scenes, SW ADMs are developed by accounting the effects of sastrugi on anisotropy. Over sea ice, a sea-ice brightness index is used to classify the scene type. Under cloudy conditions over all surface types, the longwave (LW) and window (WN) ADMs are developed by combining surface and cloud-top temperature, surface and cloud emissivity, cloud fraction, and precipitable water

  15. Next-generation angular distribution models for top-of-atmosphere radiative flux calculation from CERES instruments: methodology

    NASA Astrophysics Data System (ADS)

    Su, W.; Corbett, J.; Eitzen, Z.; Liang, L.

    2015-02-01

    The top-of-atmosphere (TOA) radiative fluxes are critical components to advancing our understanding of the Earth's radiative energy balance, radiative effects of clouds and aerosols, and climate feedback. The Clouds and the Earth's Radiant Energy System (CERES) instruments provide broadband shortwave and longwave radiance measurements. These radiances are converted to fluxes by using scene-type-dependent angular distribution models (ADMs). This paper describes the next-generation ADMs that are developed for Terra and Aqua using all available CERES rotating azimuth plane radiance measurements. Coincident cloud and aerosol retrievals, and radiance measurements from the Moderate Resolution Imaging Spectroradiometer (MODIS), and meteorological parameters from Goddard Earth Observing System (GEOS) data assimilation version 5.4.1 are used to define scene type. CERES radiance measurements are stratified by scene type and by other parameters that are important for determining the anisotropy of the given scene type. Anisotropic factors are then defined either for discrete intervals of relevant parameters or as a continuous functions of combined parameters, depending on the scene type. Significant differences between the ADMs described in this paper and the existing ADMs are over clear-sky scene types and polar scene types. Over clear ocean, we developed a set of shortwave (SW) ADMs that explicitly account for aerosols. Over clear land, the SW ADMs are developed for every 1° latitude × 1° longitude region for every calendar month using a kernel-based bidirectional reflectance model. Over clear Antarctic scenes, SW ADMs are developed by accounting the effects of sastrugi on anisotropy. Over sea ice, a sea-ice brightness index is used to classify the scene type. Under cloudy conditions over all surface types, the longwave (LW) and window (WN) ADMs are developed by combining surface and cloud-top temperature, surface and cloud emissivity, cloud fraction, and precipitable

  16. Monte Carlo eikonal scattering

    NASA Astrophysics Data System (ADS)

    Gibbs, W. R.; Dedonder, J. P.

    2012-08-01

    Background: The eikonal approximation is commonly used to calculate heavy-ion elastic scattering. However, the full evaluation has only been done (without the use of Monte Carlo techniques or additional approximations) for α-α scattering.Purpose: Develop, improve, and test the Monte Carlo eikonal method for elastic scattering over a wide range of nuclei, energies, and angles.Method: Monte Carlo evaluation is used to calculate heavy-ion elastic scattering for heavy nuclei including the center-of-mass correction introduced in this paper and the Coulomb interaction in terms of a partial-wave expansion. A technique for the efficient expansion of the Glauber amplitude in partial waves is developed.Results: Angular distributions are presented for a number of nuclear pairs over a wide energy range using nucleon-nucleon scattering parameters taken from phase-shift analyses and densities from independent sources. We present the first calculations of the Glauber amplitude, without further approximation, and with realistic densities for nuclei heavier than helium. These densities respect the center-of-mass constraints. The Coulomb interaction is included in these calculations.Conclusion: The center-of-mass and Coulomb corrections are essential. Angular distributions can be predicted only up to certain critical angles which vary with the nuclear pairs and the energy, but we point out that all critical angles correspond to a momentum transfer near 1 fm-1.

  17. Effect of Rayleigh-scattering distributed feedback on multiwavelength Raman fiber laser generation.

    PubMed

    El-Taher, A E; Harper, P; Babin, S A; Churkin, D V; Podivilov, E V; Ania-Castanon, J D; Turitsyn, S K

    2011-01-15

    We experimentally demonstrate a Raman fiber laser based on multiple point-action fiber Bragg grating reflectors and distributed feedback via Rayleigh scattering in an ~22-km-long optical fiber. Twenty-two lasing lines with spacing of ~100 GHz (close to International Telecommunication Union grid) in the C band are generated at the watt level. In contrast to the normal cavity with competition between laser lines, the random distributed feedback cavity exhibits highly stable multiwavelength generation with a power-equalized uniform distribution, which is almost independent on power.

  18. Estimating optical absorption, scattering, and Grueneisen distributions with multiple-illumination photoacoustic tomography.

    PubMed

    Shao, Peng; Cox, Ben; Zemp, Roger J

    2011-07-01

    While photoacoustic methods offer significant promise for high-resolution optical contrast imaging, quantification has thus far proved challenging. In this paper, a noniterative reconstruction technique for producing quantitative photoacoustic images of both absorption and scattering perturbations is introduced for the case when the optical properties of the turbid background are known and multiple optical illumination locations are used. Through theoretical developments and computational examples, it is demonstrated that multiple-illumination photoacoustic tomography (MI-PAT) can alleviate ill-posedness due to absorption-scattering nonuniqueness and produce quantitative high-resolution reconstructions of optical absorption, scattering, and Gruneisen parameter distributions. While numerical challenges still exist, we show that the linearized MI-PAT framework that we propose has orders of magnitude improved condition number compared with CW diffuse optical tomography.

  19. Generalized parton distributions and rapidity gap survival in exclusive diffractive pp scattering

    SciTech Connect

    Frankfurt, L.; Hyde, C. E.; Strikman, M.; Weiss, C.

    2007-03-01

    We study rapidity gap survival (RGS) in the production of high-mass systems (H=dijet, heavy quarkonium, Higgs boson) in double-gap exclusive diffractive pp scattering, pp{yields}p+(gap)+H+(gap)+p. Our approach is based on the idea that hard and soft interactions are approximately independent because they proceed over widely different time and distance scales. We implement this idea in a partonic description of proton structure, which allows for a model-independent treatment of the interplay of hard and soft interactions. The high-mass system is produced in a hard scattering process with exchange of two gluons between the protons, whose amplitude is calculable in terms of the gluon generalized parton distribution (GPD), measured in exclusive ep scattering. The hard scattering process is modified by soft spectator interactions, which we calculate neglecting correlations between hard and soft interactions (independent interaction approximation). We obtain an analytic expression for the RGS probability in terms of the phenomenological pp elastic scattering amplitude, without reference to the eikonal approximation. Contributions from inelastic intermediate states are suppressed. The onset of the black-disk limit in pp scattering at TeV energies strongly suppresses diffraction at small impact parameters and is the main factor in determining the RGS probability. Correlations between hard and soft interactions (e.g. due to scattering from the long-range pion field of the proton or due to possible short-range transverse correlations between partons) further decrease the RGS probability. We also investigate the dependence of the diffractive cross section on the transverse momenta of the final-state protons ('diffraction pattern'). By measuring this dependence one can perform detailed tests of the interplay of hard and soft interactions and even extract information about the gluon GPD in the proton. Such studies appear to be feasible with the planned forward detectors at the

  20. Timelike Compton Scattering at Jlab

    SciTech Connect

    Paremuzyan, Rafayel G.

    2014-01-01

    It is demonstrated, that with exclusive final state, data from electron scattering experiments that are recorded with loose trigger requirements can be used to analyze photoproduction reactions. A preliminary results on Timelike Compton Scattering using the electroproduction data from the CLAS detector at Jefferson Lab are presented. In particular, using final state (pe{sup -}e{sup +}) photoproduction of vector mesons and timelike photon is studied. Angular asymmetries in Timelike Compton Scattering region is compared with model predictions in the framework of Generalized Parton Distribution.

  1. Matched, mismatched, and robust scatter matrix estimation and hypothesis testing in complex t-distributed data

    NASA Astrophysics Data System (ADS)

    Fortunati, Stefano; Gini, Fulvio; Greco, Maria S.

    2016-12-01

    Scatter matrix estimation and hypothesis testing are fundamental inference problems in a wide variety of signal processing applications. In this paper, we investigate and compare the matched, mismatched, and robust approaches to solve these problems in the context of the complex elliptically symmetric (CES) distributions. The matched approach is when the estimation and detection algorithms are tailored on the correct data distribution, whereas the mismatched approach refers to the case when the scatter matrix estimator and the decision rule are derived under a model assumption that is not correct. The robust approach aims at providing good estimation and detection performance, even if suboptimal, over a large set of possible data models, irrespective of the actual data distribution. Specifically, due to its central importance in both the statistical and engineering applications, we assume for the input data a complex t-distribution. We analyze scatter matrix estimators derived under the three different approaches and compare their mean square error (MSE) with the constrained Cramér-Rao bound (CCRB) and the constrained misspecified Cramér-Rao bound (CMCRB). In addition, the detection performance and false alarm rate (FAR) of the various detection algorithms are compared with that of the clairvoyant optimum detector.

  2. OSSOS. II. A Sharp Transition in the Absolute Magnitude Distribution of the Kuiper Belt’s Scattering Population

    NASA Astrophysics Data System (ADS)

    Shankman, C.; Kavelaars, JJ.; Gladman, B. J.; Alexandersen, M.; Kaib, N.; Petit, J.-M.; Bannister, M. T.; Chen, Y.-T.; Gwyn, S.; Jakubik, M.; Volk, K.

    2016-02-01

    We measure the absolute magnitude, H, distribution, dN(H) ∝ 10αH, of the scattering Trans-Neptunian Objects (TNOs) as a proxy for their size-frequency distribution. We show that the H-distribution of the scattering TNOs is not consistent with a single-slope distribution, but must transition around Hg ˜ 9 to either a knee with a shallow slope or to a divot, which is a differential drop followed by second exponential distribution. Our analysis is based on a sample of 22 scattering TNOs drawn from three different TNO surveys—the Canada-France Ecliptic Plane Survey, Alexandersen et al., and the Outer Solar System Origins Survey, all of which provide well-characterized detection thresholds—combined with a cosmogonic model for the formation of the scattering TNO population. Our measured absolute magnitude distribution result is independent of the choice of cosmogonic model. Based on our analysis, we estimate that the number of scattering TNOs is (2.4-8.3) × 105 for Hr < 12. A divot H-distribution is seen in a variety of formation scenarios and may explain several puzzles in Kuiper Belt science. We find that a divot H-distribution simultaneously explains the observed scattering TNO, Neptune Trojan, Plutino, and Centaur H-distributions while simultaneously predicting a large enough scattering TNO population to act as the sole supply of the Jupiter-Family Comets.

  3. Neutron Scattering Measurements of Hydrogen Distribution in a Zircaloy-4 Alloy Charged with Hydrogen Gas

    SciTech Connect

    Garlea, Elena; Garlea, Vasile O; Choo, Hahn; Hubbard, Camden R; Liaw, Peter K; Rack, P. D.

    2007-01-01

    Neutron incoherent scattering measurements were conducted on Zircaloy-4 round bars. The specimens were charged in a tube furnace at 430 C, using a 12.5 vol. % hydrogen in an argon mixture for 30, 60, and 90 minutes at 13.8 kPa pressure. The volume-average neutron diffraction measurements showed the presence of the face-centered-cubic delta zirconium hydride ({delta}-ZrH{sub 2}) phase in the hydrogenated specimens. The assessment of the background in the diffraction profiles due to the incoherent scattering from the hydrogen atoms was carried out by performing inelastic scans around zero energy transfer and at a fixed two-theta value for which there was only flat background and no coherent scattering. To estimate the relative amount of hydrogen in the Zircaloy-4 samples, the increase in incoherent scattering intensities with hydrogen content was calibrated using samples for which the hydrogen content was known. Measurement of the background scattering from locations within the round bar was also performed to map the distribution of hydrogen content.

  4. Impact of Phonon Surface Scattering on Thermal Energy Distribution of Si and SiGe Nanowires

    PubMed Central

    Malhotra, Abhinav; Maldovan, Martin

    2016-01-01

    Thermal transport in nanostructures has attracted considerable attention in the last decade but the precise effects of surfaces on heat conduction have remained unclear due to a limited accuracy in the treatment of phonon surface scattering phenomena. Here, we investigate the impact of phonon-surface scattering on the distribution of thermal energy across phonon wavelengths and mean free paths in Si and SiGe nanowires. We present a rigorous and accurate description of phonon scattering at surfaces and predict and analyse nanowire heat spectra for different diameters and surface conditions. We show that the decrease in the diameter and increased roughness and correlation lengths makes the heat phonon spectra significantly shift towards short wavelengths and mean free paths. We also investigate the emergence of phonon confinement effects for small diameter nanowires and different surface scattering properties. Computed results for bulk materials show excellent agreement with recent experimentally-based approaches that reconstruct the mean-free-path heat spectra. Our phonon surface scattering model allows for an accurate theoretical extraction of heat spectra in nanowires and contributes to elucidate the development of critical phonon transport modes such as phonon confinement and coherent interference effects. PMID:27174699

  5. The estimation of space debris distribution by Kharkiv incoherent scatter radar data

    NASA Astrophysics Data System (ADS)

    Cherniak, Iurii

    Currently in near space are a large number of artificial origin objects. Among them are operable spacecrafts and the so-called "space debris". The Kharkiv radar is a sole incoherent scatter instrument on the middle latitudes of European region. The radar located near Kharkiv, Ukraine (geographic coordinates: 49.6N, 36.3E, geomagnetic coordinates: 45.7N, 117.8E). This powerful radar facility operates with 100-m zenith parabolic antenna at 158 MHz with peak transmitted power 2.0 MW, and can registered scattering of electromagnetic waves from small volumes (about ten square centimeters at distance 500 km). During the ionosphere parameters measurement by incoherent scatter radar are received different radar signals, different by nature from the signal, incoherent scattered ionosphere plasma. The paper presents the results of data analysis of several measurements cycles. It was obtained the distribution characteristics of the radar reflections from objects on Earth orbit. There are two main peak reflections appearance intensity at distances 800 km and 1000 km. Two other peaks at the altitude of 600 km and 1400 km. It is from distance above 1700 km the number of reflections is insignificant. Based on the experimental data was constructed height-temporal distribution of reflection signals. The total analysis time was about 200 hours. The intensity of reflections and their peak distances not significantly changed during day. The average number of observed reflections per day was about 500.

  6. New Scatterometer for Spatial Distribution Measurements of Light Scattering from Materials

    NASA Astrophysics Data System (ADS)

    Kawate, E.; Hain, M.

    2012-01-01

    A new scatterometer is composed of two ellipsoidal mirrors of revolution and an optical detection system. It enables us to absolutely measure diffuse reflectance and transmittance and to measure the spatial distribution of light scattering from almost all materials. The optical detection system has been developed both to measure total photo-intensity using a photodiode and to capture the imaging data using a CCD camera. This results in faster, more complete and often more accurate measurements than can be achieved with traditional goniometric methods and integrated sphere methods. The absolute total integrated reflectance and transmittance of well-known samples were measured and the spatial distribution of light scattering from a diffraction grating was captured and evaluated.

  7. The distribution of pelagic sound scattering layers across the southwest Indian Ocean

    NASA Astrophysics Data System (ADS)

    Boersch-Supan, Philipp H.; Rogers, Alex D.; Brierley, Andrew S.

    2017-02-01

    Shallow and deep scattering layers (SLs) were surveyed with split-beam echosounders across the southwest Indian Ocean (SWIO) to investigate their vertical and geographical distribution. Cluster analysis was employed to objectively classify vertical backscatter profiles. Correlations between backscatter and environmental covariates were modelled using generalized additive mixed models (GAMMs) with spatial error structures. Structurally distinct SL regimes were found across the Subantarctic Front. GAMMs indicated a close relationship between sea surface temperature and mean volume backscatter, with significantly elevated backscatter in the subtropical convergence zone. The heterogeneous distribution of scattering layer biota reflects the biogeographic zonation of the survey area and is likely to have implications for predator foraging and carbon cycling in the Indian Ocean.

  8. Estimation of the Scatterer Distribution of the Cirrhotic Liver using Ultrasonic Image

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Tadashi; Hachiya, Hiroyuki

    1998-05-01

    In the B-mode image of the liver obtained by an ultrasonic imaging system, the speckled pattern changes with the progression of the disease such as liver cirrhosis.In this paper we present the statistical characteristics of the echo envelope of the liver, and the technique to extract information of the scatterer distribution from the normal and cirrhotic liver images using constant false alarm rate (CFAR) processing.We analyze the relationship between the extracted scatterer distribution and the stage of liver cirrhosis. The ratio of the area in which the amplitude of the processing signal is more than the threshold to the entire processed image area is related quantitatively to the stage of liver cirrhosis.It is found that the proposed technique is valid for the quantitative diagnosis of liver cirrhosis.

  9. The measurement system of nanoparticle size distribution from dynamic light scattering data

    NASA Astrophysics Data System (ADS)

    Li, Zhenmei; Wang, Yajing; Shen, Jin; Liu, Wei; Sun, Xianming

    2014-05-01

    The measurement and analysis system of nanoparticle size distribution was developed by using virtual instrument technology, where the photon counting technology was applied in the system to replace the correlator; a high speed photon counter was designed with seamlessly counting technology to reduce the system cost and increase the accuracy. The data of nanoparticle dynamic light scattering (DLS) were analyzed in the mixed program of MATLAB and LabVIEW, where the autocorrelation functions of light scattering signals of 100 nm unimodal as well as 90 nm and 300 nm bimodal particles were inversed by truncated singular value decomposition arithmetic. Experiment results show that the peak position, peak width and symmetry of particle size distributions (PSDs) are very close to the real particles.

  10. High-energy Electron Scattering and the Charge Distributions of Selected Nuclei

    DOE R&D Accomplishments Database

    Hahn, B.; Ravenhall, D. G.; Hofstadter, R.

    1955-10-01

    Experimental results are presented of electron scattering by Ca, V, Co, In, Sb, Hf, Ta, W, Au, Bi, Th, and U, at 183 Mev and (for some of the elements) at 153 Mev. For those nuclei for which asphericity and inelastic scattering are absent or unimportant, i.e., Ca, V, Co, In, Sb, Au, and Bi, a partial wave analysis of the Dirac equation has been performed in which the nuclei are represented by static, spherically symmetric charge distributions. Smoothed uniform charge distributions have been assumed; these are characterized by a constant charge density in the central region of the nucleus, with a smoothed-our surface. Essentially two parameters can be determined, related to the radium and to the surface thickness. An examination of the Au experiments show that the functional forms of the surface are not important, and that the charge density in the central regions is probably fairly flat, although it cannot be determined very accurately.

  11. The Angular Momentum Dichotomy

    NASA Astrophysics Data System (ADS)

    Teklu, Adelheid; Remus, Rhea-Silvia; Dolag, Klaus; Burkert, Andreas

    2015-02-01

    In the context of the formation of spiral galaxies the evolution and distribution of the angular momentum of dark matter halos have been discussed for more than 20 years, especially the idea that the specific angular momentum of the halo can be estimated from the specific angular momentum of its disk (e.g. Fall & Efstathiou (1980), Fall (1983) and Mo et al. (1998)). We use a new set of hydrodynamic cosmological simulations called Magneticum Pathfinder which allow us to split the galaxies into spheroidal and disk galaxies via the circularity parameter ɛ, as commonly used (e.g. Scannapieco et al. (2008)). Here, we focus on the dimensionless spin parameter λ = J |E|1/2 / (G M5/2) (Peebles 1969, 1971), which is a measure of the rotation of the total halo and can be fitted by a lognormal distribution, e.g. Mo et al. (1998). The spin parameter allows one to compare the relative angular momentum of halos across different masses and different times. Fig. 1 reveals a dichotomy in the distribution of λ at all redshifts when the galaxies are split into spheroids (dashed) and disk galaxies (dash-dotted). The disk galaxies preferentially live in halos with slightly larger spin parameter compared to spheroidal galaxies. Thus, we see that the λ of the whole halo reflects the morphology of its central galaxy. For more details and a larger study of the angular momentum properties of disk and spheroidal galaxies, see Teklu et al. (in prep.).

  12. Optical angular momentum and atoms.

    PubMed

    Franke-Arnold, Sonja

    2017-02-28

    Any coherent interaction of light and atoms needs to conserve energy, linear momentum and angular momentum. What happens to an atom's angular momentum if it encounters light that carries orbital angular momentum (OAM)? This is a particularly intriguing question as the angular momentum of atoms is quantized, incorporating the intrinsic spin angular momentum of the individual electrons as well as the OAM associated with their spatial distribution. In addition, a mechanical angular momentum can arise from the rotation of the entire atom, which for very cold atoms is also quantized. Atoms therefore allow us to probe and access the quantum properties of light's OAM, aiding our fundamental understanding of light-matter interactions, and moreover, allowing us to construct OAM-based applications, including quantum memories, frequency converters for shaped light and OAM-based sensors.This article is part of the themed issue 'Optical orbital angular momentum'.

  13. Optical angular momentum and atoms

    NASA Astrophysics Data System (ADS)

    Franke-Arnold, Sonja

    2017-02-01

    Any coherent interaction of light and atoms needs to conserve energy, linear momentum and angular momentum. What happens to an atom's angular momentum if it encounters light that carries orbital angular momentum (OAM)? This is a particularly intriguing question as the angular momentum of atoms is quantized, incorporating the intrinsic spin angular momentum of the individual electrons as well as the OAM associated with their spatial distribution. In addition, a mechanical angular momentum can arise from the rotation of the entire atom, which for very cold atoms is also quantized. Atoms therefore allow us to probe and access the quantum properties of light's OAM, aiding our fundamental understanding of light-matter interactions, and moreover, allowing us to construct OAM-based applications, including quantum memories, frequency converters for shaped light and OAM-based sensors. This article is part of the themed issue 'Optical orbital angular momentum'.

  14. Test of the conserved vector current hypothesis by a {beta}-ray angular distribution measurement in the mass-8 system

    SciTech Connect

    Sumikama, T.; Matsuta, K.; Ogura, M.; Iwakoshi, T.; Nakashima, Y.; Fujiwara, H.; Fukuda, M.; Mihara, M.; Nagatomo, T.; Minamisono, K.; Yamaguchi, T.; Minamisono, T.

    2011-06-15

    The {beta}-ray angular correlations for the spin alignments of {sup 8}Li and {sup 8}B have been observed in order to test the conserved vector current (CVC) hypothesis. The alignment correlation terms were combined with the known {beta}-{alpha} angular correlation terms to determine all the matrix elements contributing to the correlation terms. The weak magnetism term, 7.5{+-}0.2, deduced from the {beta}-ray correlation terms was consistent with the CVC prediction 7.3{+-}0.2, deduced from the analog-{gamma} decay measurement based on the CVC hypothesis. However, there was no consistent CVC prediction for the second-forbidden term associated with the weak vector current. The experimental value for the second-forbidden term was 1.0{+-}0.3, while the CVC prediction was 0.1{+-}0.4 or 2.1{+-}0.5.

  15. Test of the conserved vector current hypothesis by a β-ray angular distribution measurement in the mass-8 system

    NASA Astrophysics Data System (ADS)

    Sumikama, T.; Matsuta, K.; Nagatomo, T.; Ogura, M.; Iwakoshi, T.; Nakashima, Y.; Fujiwara, H.; Fukuda, M.; Mihara, M.; Minamisono, K.; Yamaguchi, T.; Minamisono, T.

    2011-06-01

    The β-ray angular correlations for the spin alignments of Li8 and B8 have been observed in order to test the conserved vector current (CVC) hypothesis. The alignment correlation terms were combined with the known β-α angular correlation terms to determine all the matrix elements contributing to the correlation terms. The weak magnetism term, 7.5±0.2, deduced from the β-ray correlation terms was consistent with the CVC prediction 7.3±0.2, deduced from the analog-γ decay measurement based on the CVC hypothesis. However, there was no consistent CVC prediction for the second-forbidden term associated with the weak vector current. The experimental value for the second-forbidden term was 1.0±0.3, while the CVC prediction was 0.1±0.4 or 2.1±0.5.

  16. Next-Generation Angular Distribution Models for Top-of-Atmosphere Radiative Flux Calculation from CERES Instruments: Validation

    NASA Technical Reports Server (NTRS)

    Su, W.; Corbett, J.; Eitzen, Z.; Liang, L.

    2015-01-01

    Radiative fluxes at the top of the atmosphere (TOA) from the Clouds and the Earth's Radiant Energy System (CERES) instrument are fundamental variables for understanding the Earth's energy balance and how it changes with time. TOA radiative fluxes are derived from the CERES radiance measurements using empirical angular distribution models (ADMs). This paper evaluates the accuracy of CERES TOA fluxes using direct integration and flux consistency tests. Direct integration tests show that the overall bias in regional monthly mean TOA shortwave (SW) flux is less than 0.2Wm(exp -2) and the RMSE is less than 1.1Wm(exp -2). The bias and RMSE are very similar between Terra and Aqua. The bias in regional monthly mean TOA LW fluxes is less than 0.5Wm(exp -2) and the RMSE is less than 0.8Wm(exp -)2 for both Terra and Aqua. The accuracy of the TOA instantaneous flux is assessed by performing tests using fluxes inverted from nadir- and oblique-viewing angles using CERES along-track observations and temporally and spatially matched MODIS observations, and using fluxes inverted from multi-angle MISR observations. The averaged TOA instantaneous SW flux uncertainties from these two tests are about 2.3% (1.9Wm(exp -2) over clear ocean, 1.6% (4.5Wm(exp -2) over clear land, and 2.0% (6.0Wm(exp -) over clear snow/ice; and are about 3.3% (9.0Wm(exp -2), 2.7% (8.4Wm(exp -2), and 3.7% (9.9Wm(exp -2) over ocean, land, and snow/ice under all-sky conditions. The TOA SW flux uncertainties are generally larger for thin broken clouds than for moderate and thick overcast clouds. The TOA instantaneous daytime LW flux uncertainties derived from the CERESMODIS test are 0.5% (1.5Wm(exp -2), 0.8% (2.4Wm(exp -2), and 0.7% (1.3Wm(exp -2) over clear ocean, land, and snow/ice; and are about 1.5% (3.5Wm(exp -2), 1.0% (2.9Wm(exp -2), and 1.1% (2.1Wm(exp -2) over ocean, land, and snow/ice under all-sky conditions. The TOA instantaneous nighttime LW flux uncertainties are about 0.5-1% (<2.0Wm(exp -2) for all

  17. Spatial distribution of mineral dust single scattering albedo based on DREAM model

    NASA Astrophysics Data System (ADS)

    Kuzmanoski, Maja; Ničković, Slobodan; Ilić, Luka

    2016-04-01

    Mineral dust comprises a significant part of global aerosol burden. There is a large uncertainty in estimating role of dust in Earth's climate system, partly due to poor characterization of its optical properties. Single scattering albedo is one of key optical properties determining radiative effects of dust particles. While it depends on dust particle sizes, it is also strongly influenced by dust mineral composition, particularly the content of light-absorbing iron oxides and the mixing state (external or internal). However, an assumption of uniform dust composition is typically used in models. To better represent single scattering albedo in dust atmospheric models, required to increase accuracy of dust radiative effect estimates, it is necessary to include information on particle mineral content. In this study, we present the spatial distribution of dust single scattering albedo based on the Dust Regional Atmospheric Model (DREAM) with incorporated particle mineral composition. The domain of the model covers Northern Africa, Middle East and the European continent, with horizontal resolution set to 1/5°. It uses eight particle size bins within the 0.1-10 μm radius range. Focusing on dust episode of June 2010, we analyze dust single scattering albedo spatial distribution over the model domain, based on particle sizes and mineral composition from model output; we discuss changes in this optical property after long-range transport. Furthermore, we examine how the AERONET-derived aerosol properties respond to dust mineralogy. Finally we use AERONET data to evaluate model-based single scattering albedo. Acknowledgement We would like to thank the AERONET network and the principal investigators, as well as their staff, for establishing and maintaining the AERONET sites used in this work.

  18. Angular Momentum

    ERIC Educational Resources Information Center

    Shakur, Asif; Sinatra, Taylor

    2013-01-01

    The gyroscope in a smartphone was employed in a physics laboratory setting to verify the conservation of angular momentum and the nonconservation of rotational kinetic energy. As is well-known, smartphones are ubiquitous on college campuses. These devices have a panoply of built-in sensors. This creates a unique opportunity for a new paradigm in…

  19. Angular distributions of reflected and refracted relativistic electron beams crossing a thin planar target at a small angle to its surface

    SciTech Connect

    Serov, A. V.; Mamonov, I. A.; Kol’tsov, A. V.

    2015-10-15

    The scattering of electrons by aluminum, copper, and lead foils, as well as by bimetallic aluminum-lead and aluminum-copper foils, has been studied experimentally. A microtron with an energy of particles of 7.4 MeV has been used as a source of electrons. The beam of particles incident on a target at small angles is split into particles reflected from the foil, which constitute a reflected beam, and particles crossing the foil, which constitute a refracted beam. The effect of the material and thickness of the foil, as well as the angle between the initial trajectory of the beam and the plane of the target, on the direction of motion and the angular divergence of the beam crossing the foil and the beam reflected from the foil has been analyzed. Furthermore, the effect of the sequence of metal layers in bimetallic films on the angles of refraction and reflection of the beam has been examined.

  20. Small-angle light scattering from polymer-dispersed liquid-crystal films

    SciTech Connect

    Loiko, V. A. Maschke, U.; Zyryanov, V. Ya.; Konkolovich, A. V.; Misckevich, A. A.

    2008-10-15

    A method is developed for modeling and computing the angular distribution of light scattered forward from a single-layer polymer-dispersed liquid-crystal (PDLC) film. The method is based on effective-medium approximation, anomalous diffraction approximation, and far-field single-scattering approximation. The angular distribution of forward-scattered light is analyzed for PDLC films with droplet size larger than the optical wavelength. The method can be used to study field-and temperature-induced phase transitions in LC droplets with cylindrical symmetry by measuring polarized scattered light intensity.

  1. Angular Goos-Hänchen effect in curved dielectric microstructures.

    PubMed

    Tran, N H; Dutriaux, L; Balcou, P; Floch, A L; Bretenaker, F

    1995-06-01

    A macroscopic angular Goos-Hänchen effect at total reflection on curved interfaces is studied experimentally. The results are compared with the complex-angular-momentum model of quasi-critical scattering. An extremum in angular deflection, which has not yet been predicted by any theory other than exact Mie scattering computations, is identified at low size parameters.

  2. Scattering and diffraction of plane SH-waves by periodically distributed canyons

    NASA Astrophysics Data System (ADS)

    Ba, Zhenning; Liang, Jianwen; Zhang, Yanju

    2016-06-01

    A new method is presented to study the scattering and diffraction of plane SH-waves by periodically distributed canyons in a layered half-space. This method uses the indirect boundary element method combined with Green's functions of uniformly distributed loads acting on periodically distributed inclined lines. The periodicity feature of the canyons is exploited to limit the discretization effort to a single canyon, which avoids errors induced by the truncation of the infinite boundary, and the computational complexity and the demand on memory can be significantly reduced. Furthermore, the total wave fields are decomposed into the free field and scattered field in the process of calculation, which means that the method has definite physical meaning. The implementation of the method is described in detail and its accuracy is verified. Parametric studies are performed in the frequency domain by taking periodically distributed canyons of semi-circular and semi-elliptic cross-sections as examples. Numerical results show that the dynamic responses of periodically distributed canyons can be quite different from those for a single canyon and significant dynamic interactions exist between the canyons.

  3. State-to-state dynamics of high-n Rydberg H-atom scattering with H2: inelastic scattering and reactive scattering.

    PubMed

    Yu, Shengrui; Su, Shu; Dai, Dongxu; Yuan, Kaijun; Yang, Xueming

    2015-04-21

    The state-to-state dynamics of high-n Rydberg H-atom scattering with para-H2 at the collision energies of 0.45 and 1.07 eV have been studied using the H-atom Rydberg tagging time-of-flight technique. Both the inelastic scattering and reactive scattering are observed in the experimental time-of-flight spectra. The products H2(v', j' = odd) come only from reactive scattering and present clearly forward-backward asymmetric angular distributions, which differ from those of the corresponding ion-molecule reaction. The products H2(v', j' = even), however, come from both reactive scattering and inelastic scattering. Simulating the rotational distribution from reactive scattering, we found that most of the H2(v', j' = even) products come from inelastic scattering. The angular distributions of the product H2(v', j' = even) are consistent with what is predicted by the conventional textbook mechanism of inelastic scattering, and are a little different from those of the corresponding ion-molecule inelastic scattering. These results suggest that the effect of Rydberg electron could not be neglected in describing the differential cross sections of H* + para-H2 scattering. From the simulation, the branching ratios of the inelastic scattering channel were determined to be 66% and 79% at the collision energies of 0.45 and 1.07 eV, respectively.

  4. CONNECTING ANGULAR MOMENTUM AND GALACTIC DYNAMICS: THE COMPLEX INTERPLAY BETWEEN SPIN, MASS, AND MORPHOLOGY

    SciTech Connect

    Teklu, Adelheid F.; Remus, Rhea-Silvia; Dolag, Klaus; Beck, Alexander M.; Burkert, Andreas; Schulze, Felix; Steinborn, Lisa K.; Schmidt, Andreas S.

    2015-10-10

    The evolution and distribution of the angular momentum of dark matter (DM) halos have been discussed in several studies over the past decades. In particular, the idea arose that angular momentum conservation should allow us to infer the total angular momentum of the entire DM halo from measuring the angular momentum of the baryonic component, which is populating the center of the halo, especially for disk galaxies. To test this idea and to understand the connection between the angular momentum of the DM halo and its galaxy, we use a state-of-the-art, hydrodynamical cosmological simulation taken from the set of Magneticum Pathfinder simulations. Thanks to the inclusion of the relevant physical processes, the improved underlying numerical methods, and high spatial resolution, we successfully produce populations of spheroidal and disk galaxies self-consistently. Thus, we are able to study the dependence of galactic properties on their morphology. We find that (1) the specific angular momentum of stars in disk and spheroidal galaxies as a function of their stellar mass compares well with observational results; (2) the specific angular momentum of the stars in disk galaxies is slightly smaller compared to the specific angular momentum of the cold gas, in good agreement with observations; (3) simulations including the baryonic component show a dichotomy in the specific stellar angular momentum distribution when splitting the galaxies according to their morphological type (this dichotomy can also be seen in the spin parameter, where disk galaxies populate halos with slightly larger spin compared to spheroidal galaxies); (4) disk galaxies preferentially populate halos in which the angular momentum vector of the DM component in the central part shows a better alignment to the angular momentum vector of the entire halo; and (5) the specific angular momentum of the cold gas in disk galaxies is approximately 40% smaller than the specific angular momentum of the total DM halo

  5. Experimental validation of bidirectional reflection and transmission distribution measurements of specular and scattering materials

    NASA Astrophysics Data System (ADS)

    Grobe, Lars O.; Wittkopf, Stephen; Apian-Bennewitz, Peter; Jonsson, Jacob C.; Rubin, Mike

    2010-05-01

    The development of advanced materials for facades aims to achieve higher energy efficiency of buildings. Successful application of these materials depends on the availability of reliable characterization data. While data derived from integrated measurements of transmission and reflection is widely available, it does not allow to characterize the angular dependence of the performance of such materials. The Bidirectional Reflection-Transmission Distribution (BRTD) can be measured by commercially available Gonio-Photometers and, complimenting integrated transmittance and reflectance, allows the assessment of facade materials and thus supports both their development and application. Validation of the obtained data is crucial to back these measurements. Integration of validation procedures into the operation of a characterization laboratory allowing a well-defined approach to quality control is presented for a range of typical material and sample types: * consistency checks of measurement data * cross-checking of integrated material properties derived from BRTD data with integrating sphere measurements * round-robin comparison between laboratories using comparable devices The results of of these first measurements are discussed. Potential to further improve the availability of reliable angular resolved characterization data for the building sector is identified.

  6. Dynamical simulation of the fission process and anisotropy of the fission fragment angular distributions of excited nuclei produced in fusion reactions

    NASA Astrophysics Data System (ADS)

    Eslamizadeh, H.

    2016-10-01

    Abstract. A stochastic approach based on four-dimensional Langevin equations was applied to calculate the anisotropy of fission fragment angular distributions, average prescission neutron multiplicity, and the fission probability in a wide range of fissile parameters for the compound nuclei 197Tl,225Pa,248Cf , and 264Rf produced in fusion reactions. Three collective shape coordinates plus the projection of total spin of the compound nucleus to the symmetry axis K were considered in the four-dimensional dynamical model. In the dynamical calculations, nuclear dissipation was generated through the chaos-weighted wall and window friction formula. Furthermore, in the dynamical calculations the dissipation coefficient of K ,γk was considered as a free parameter, and its magnitude inferred by fitting measured data on the anisotropy of fission fragment angular distributions for the compound nuclei 197Tl,225Pa,248Cf , and 264Rf. Comparison of the calculated results for the anisotropy of fission fragment angular distributions with the experimental data showed that the results of the calculations are in good agreement with the experimental data by using values of the dissipation coefficient of K equal to (0.185-0.205), (0.175-0.192), (0.077-0.090), and (0.075-0.085) (MeVzs ) -1 /2 for the compound nuclei 197Tl,225Pa,248Cf , and 264Rf, respectively. It was also shown that the influence of the dissipation coefficient of K on the results of the calculations of the prescission neutron multiplicity and fission probability is small.

  7. Broadband diffuse terahertz wave scattering by flexible metasurface with randomized phase distribution

    PubMed Central

    Zhang, Yin; Liang, Lanju; Yang, Jing; Feng, Yijun; Zhu, Bo; Zhao, Junming; Jiang, Tian; Jin, Biaobing; Liu, Weiwei

    2016-01-01

    Suppressing specular electromagnetic wave reflection or backward radar cross section is important and of broad interests in practical electromagnetic engineering. Here, we present a scheme to achieve broadband backward scattering reduction through diffuse terahertz wave reflection by a flexible metasurface. The diffuse scattering of terahertz wave is caused by the randomized reflection phase distribution on the metasurface, which consists of meta-particles of differently sized metallic patches arranged on top of a grounded polyimide substrate simply through a certain computer generated pseudorandom sequence. Both numerical simulations and experimental results demonstrate the ultralow specular reflection over a broad frequency band and wide angle of incidence due to the re-distribution of the incident energy into various directions. The diffuse scattering property is also polarization insensitive and can be well preserved when the flexible metasurface is conformably wrapped on a curved reflective object. The proposed design opens up a new route for specular reflection suppression, and may be applicable in stealth and other technology in the terahertz spectrum. PMID:27225031

  8. Scattering Studies of Hydrophobic Monomers in Liposomal Bilayers: An Expanding shell Model of Monomer Distribution

    SciTech Connect

    Richter, Andrew G; Dergunov, Sergey; Ganus, Bill; Thomas, Zachary P; Pingali, Sai Venkatesh; Urban, Volker S; Liu, Yun; Porcar, Lionel; Pinkhassik, Eugene

    2011-01-01

    Hydrophobic monomers partially phase separate from saturated lipids when loaded into lipid bilayers in amounts exceeding a 1:1 monomer/lipid molar ratio. This conclusion is based on the agreement between two independent methods of examining the structure of monomer-loaded bilayers. Complete phase separation of monomers from lipids would result in an increase in bilayer thickness and a slight increase in the diameter of liposomes. A homogeneous distribution of monomers within the bilayer would not change the bilayer thickness and would lead to an increase in the liposome diameter. The increase in bilayer thickness, measured by the combination of small-angle neutron scattering (SANS) and small-angle X-ray scattering (SAXS), was approximately half of what was predicted for complete phase separation. The increase in liposome diameter, measured by dynamic light scattering (DLS), was intermediate between values predicted for a homogeneous distribution and complete phase separation. Combined SANS, SAXS, and DLS data suggest that at a 1.2 monomer/lipid ratio approximately half of the monomers are located in an interstitial layer sandwiched between lipid sheets. These results expand our understanding of using self-assembled bilayers as scaffolds for the directed covalent assembly of organic nanomaterials. In particular, the partial phase separation of monomers from lipids corroborates the successful creation of nanothin polymer materials with uniform imprinted nanopores. Pore-forming templates do not need to span the lipid bilayer to create a pore in the bilayer-templated films.

  9. Scattering Studies of Hydrophobic Monomers in Liposomal Bilayers: An Expanding Shell Model of Monomer Distribution

    SciTech Connect

    Richter, Andrew; Dergunov, Sergey; Ganus, Bill; Thomas, Zachary; Pingali, Sai Venkatesh; Urban, Volker S; Liu, Yun; Porcar, Lionel; Pinkhassik, Eugene

    2011-01-01

    Hydrophobic monomers partially phase separate from saturated lipids when loaded into lipid bilayers in amounts exceeding a 1:1 monomer/lipid molar ratio. This conclusion is based on the agreement between two independent methods of examining the structure of monomer-loaded bilayers. Complete phase separation of monomers from lipids would result in an increase in bilayer thickness and a slight increase in the diameter of liposomes. A homogeneous distribution of monomers within the bilayer would not change the bilayer thickness and would lead to an increase in the liposome diameter. The increase in bilayer thickness, measured by the combination of small-angle neutron scattering (SANS) and small-angle X-ray scattering (SAXS), was approximately half of what was predicted for complete phase separation. The increase in liposome diameter, measured by dynamic light scattering (DLS), was intermediate between values predicted for a homogeneous distribution and complete phase separation. Combined SANS, SAXS, and DLS data suggest that at a 1.2 monomer/lipid ratio approximately half of the monomers are located in an interstitial layer sandwiched between lipid sheets. These results expand our understanding of using self-assembled bilayers as scaffolds for the directed covalent assembly of organic nanomaterials. In particular, the partial phase separation of monomers from lipids corroborates the successful creation of nanothin polymer materials with uniform imprinted nanopores. Pore-forming templates do not need to span the lipid bilayer to create a pore in the bilayer-templated films.

  10. Scattering Studies of Hydrophobic Monomers in Liposomal Bilayers: an Expanding Shell Model of Monomer Distribution

    PubMed Central

    Richter, Andrew G.; Dergunov, Sergey A.; Ganus, Bill; Thomas, Zachary; Pingali, Sai Venkatesh; Urban, Volker; Liu, Yun; Porcar, Lionel; Pinkhassik, Eugene

    2011-01-01

    Hydrophobic monomers partially phase-separate from saturated lipids when loaded into lipid bilayers in amounts exceeding 1:1 monomer:lipid molar ratio. This conclusion is based on agreement between two independent methods of examining the structure of monomer-loaded bilayers. Complete phase separation of monomers from lipids would result in increase in bilayer thickness and slight increase in the diameter of liposomes. Homogeneous distribution of monomers within the bilayer would not change the bilayer thickness and would lead to the increase in the liposome diameter. The increase in bilayer thickness, measured by the combination of small angle neutron scattering (SANS) and small angle X-ray scattering (SAXS), was approximately one half of what was predicted for complete phase separation. The increase in liposome diameter, measured by dynamic light scattering (DLS), was in the middle between values predicted for homogeneous distribution and complete phase separation. Combined SANS, SAXS, and DLS data suggest that at 1.2 monomer:lipid ratio, approximately one half of monomers are located in an interstitial layer sandwiched between lipid sheets. These results expand our understanding of using self-assembled bilayers as scaffolds for directed covalent assembly of organic nanomaterials. In particular, partial phase separation of monomers from lipids corroborates successful creation of nanometer-thin polymer materials with uniform imprinted nanopores. Pore-forming templates do not need to span the lipid bilayer to create a pore in the bilayer-templated films. PMID:21391646

  11. Measurement of Dijet Angular Distributions and Search for Quark Compositeness in pp Collisions at $sqrt{s} = 7$ TeV

    SciTech Connect

    Khachatryan, Vardan; et al.

    2011-05-01

    Dijet angular distributions are measured over a wide range of dijet invariant masses in pp collisions at s√ = 7 TeV, at the CERN LHC. The event sample, recorded with the CMS detector, corresponds to an integrated luminosity of 36 inverse picobarns. The data are found to be in good agreement with the predictions of perturbative QCD, and yield no evidence of quark compositeness. With a modified frequentist approach, a lower limit on the contact interaction scale for left-handed quarks of Lambda = 5.6 TeV is obtained at the 95% confidence level.

  12. Auger resonant Raman spectroscopy used to study the angular distributions of the Xe 4d{sub 5/2} {yields} 6p decay spectrum

    SciTech Connect

    Langer, B.; Berrah, N.; Farhat, A.

    1997-04-01

    Auger resonant Raman spectroscopy is a powerful tool for studying the resonant Auger decay processes with a resolution narrower than the natural lifetime width of the initial inner-shell hole state. This effect has been used to analyze branching ratios of resonantly excited atoms and molecules. In this paper, the authors present results of a study of angular distributions of the spectator decay lines of Xe following 4d{sub 5/2}{r_arrow}6p excitation using the Auger resonant Raman effect and highly resolved photons from the Advanced Light Source (ALS).

  13. Angular Distributions for 3,4 Lambda H Bound States in the 3,4 He(e,e'K+) reaction

    SciTech Connect

    Dohrmann, Frank; Ahmidouch, Abdellah; Armstrong, Christopher; Arrington, John; Asaturyan, Razmik; Avery, Steven; Bailey, Kevin; Hu, Bitao; Breuer, Herbert; Brown, Daniel; Carlini, Roger; Cha, Jinseok; Chant, Nicholas; Christy, Michael; Cochran, Anthony; Cole, Leon; Crowder, J.; Danagoulian, Samuel; Elaasar, Mostafa; Ent, Rolf; Fenker, Howard; Fujii, Yu; Gan, Liping; Garrow, Kenneth; Gueye, Paul; Hafidi, Kawtar; Hinton, Wendy; Juengst, Henry; Keppel, Cynthia; Liang, Yongguang; Liu, Jinghua; Lung, Allison; Mack, David; Markowitz, Pete; Mitchell, Joseph; Miyoshi, Toshinobu; Mkrtchyan, Hamlet; Mtingwa, Sekazi; Mueller, Robert; Niculescu, Gabriel; Niculescu, Maria-Ioana; Potterveld, David; Raue, Brian; Reimer, Paul; Reinhold, Joerg; Roche, Julie; Sarsour, Murad; Sato, Yoshinori; Segel, Ralph; Semenov, Andrei; Stepanyan, Samuel; Tadevosyan, Vardan; Tajima, Shigeyuki; Tang, Liguang; Uzzle, Alicia; Wood, Stephen; Yamaguchi, Hiroshi; Yan, Chen; Yuan, Lulin; Zeidman, Benjamin; Zeier, Markus; Zihlmann, Benedikt

    2004-12-01

    The 3Lambda H and 4Lambda H hypernuclear bound states have been observed for the first time in kaon electroproduction on 3,4He targets. The production cross sections have been determined at Q**2= 0.35 GeV**2 and W= 1.91 GeV. For either hypernucleus the nuclear form factor is determined by comparing the angular distribution of the 3,4He(e,e'K+)3,4Lambda H processes to the elementary cross section 1H(e,e'K+) Lambda on the free proton, measured during the same experiment.

  14. Angular and energy distributions of fragment ions in dissociative double photoionization of acetylene molecules in the 31.9-50.0 eV photon energy range

    NASA Astrophysics Data System (ADS)

    Falcinelli, Stefano; Alagia, Michele; Farrar, James M.; Kalogerakis, Konstantinos S.; Pirani, Fernando; Richter, Robert; Schio, Luca; Stranges, Stefano; Rosi, Marzio; Vecchiocattivi, Franco

    2016-09-01

    The two-body dissociation reactions of the dication C2H2+2, initiated via double ionization of acetylene molecules by photons in the energy range 31.9-50.0 eV, have been studied by coupling photoelectron-photoion-photoion coincidence and ion imaging techniques. The angular distributions and kinetic energy of product ions, measured in the 31.9-50.0 eV energy range, exhibit significant differences for the three leading dissociation reactions with respect to a previous investigation carried out at a fixed energy of 39.0 eV, providing thus new information on the dynamical evolution of the system. The analysis of the results indicates that such dissociation reactions occur with a different mechanism. In particular, the symmetric dissociation in two CH+ ions is characterized by different dynamics, and the anisotropy of the angular distribution of ionic products increases with photon energy in a more pronounced way than the other two reactions. Moreover, the kinetic energy distribution of the symmetric dissociation reaction exhibits several components that change with photon energy. The new experimental findings cast light on the microscopic evolution of the system and can provide a laboratory reference for new theoretical calculations on specific features of the multidimensional potential energy surface, namely, the structure, energy and symmetry of dication states, the electronic state of dissociation products, energy barriers and their dependence on the geometry of the intermediate state.

  15. Investigation of Angular Distributions of Drell-Yan Dimuons in p+p and p+d Interactions with the E906/SeaQuest Experiment

    NASA Astrophysics Data System (ADS)

    Aidala, Christine; FNAL E906/SeaQuest Collaboration

    2011-10-01

    Striking cos 2 φ dependences in pion-induced Drell-Yan measurements were first observed in the 1980s, and proton- induced Drell-Yan measurements by the Fermilab E866 experiment on deuterium and hydrogen targets published in 2007 and 2009 reported smaller but non-zero azimuthal dependences of the Drell-Yan pairs. These azimuthal effects have been attributed to a correlation between the spin and transverse momentum of transversely polarized quarks within an unpolarized nucleon, parametrized by the Boer-Mulders transverse-momentum-dependent distribution function, with additional contributions from QCD effects. With data taking planned to start in the summer of 2011, the E906/SeaQuest experiment will use a 120 GeV/c proton beam extracted from the Fermilab Main Injector on liquid hydrogen and deuterium targets, extending the kinematic coverage of its predecessor experiment E866 to higher parton momentum fraction. Measurement of the dimuon angular distributions will also allow the Lam-Tung relation to be tested in an extended kinematic range compared to E866. The status of data taking and prospects for measurement of the angular distributions of Drell-Yan pairs will be presented.

  16. Angular and internal state distributions of H2+ generated by (2 + 1) resonance enhanced multiphoton ionization of H2 using time-of-flight mass spectrometry

    NASA Astrophysics Data System (ADS)

    Perreault, William E.; Mukherjee, Nandini; Zare, Richard N.

    2016-06-01

    We report direct measurement of the anisotropy parameter β for the angular distribution of the photoelectron and photoion in (2 + 1) resonance enhanced multiphoton ionization process of H2 X 1 Σg + (v = 0, J = 0) molecules through the intermediate H2 E,F 1 Σg + (v' = 0, J' = 0) level (λ = 201.684 nm) using a time-of-flight mass spectrometer. The time-of-flight spectra were recorded as the direction of polarization of the ionizing laser was varied with respect to the flight axis of the H2 molecular beam and were fitted to an angular distribution in an appropriately rotated coordinate system with the z-axis oriented along the time-of-flight axis. The anisotropy parameter β was found to be 1.72 ± 0.13 by fitting the time-of-flight spectra and agreed with previous measurements. Using secondary ionization with a delayed laser pulse of different wavelength, we also determined the vibrational energy distribution of the ions, showing that 98% ± 4% of the ions are generated in their ground vibrational state, in agreement with the calculated Franck-Condon factors between the H2 E,F 1 Σg + (v' = 0) and H 2+ X 1 Σg + (v″) vibrational levels.

  17. The method of joint probability distribution functions applied to the one-wavelength anomalous-scattering (OAS) case.

    PubMed

    Giacovazzo, C; Siliqi, D

    2001-01-01

    The method of the joint probability distribution function is applied to the case in which the positions of the anomalous scatterers are fully or partially known. The mathematical technique is able to handle errors both in the model structure of the located anomalous scatterers and in measurements. A criterion for ranking the more accurate phase estimates is given.

  18. Single and multiple scattering contributions to circumsolar radiation.

    PubMed

    Box, M A; Deepak, A

    1978-12-01

    Single and multiple scattering contributions to the circumsolar radiation along the almucantar and sun vertical have been computed by a Gauss-Seidel solution to the radiative transfer equation. In the near forward direction, the multiple scattering contributions are significant for optical depths of the order of 0.4. However, the shape of the angular distribution of almucantar radiance up to 10 degrees appears less sensitive to multiple scattering. The results have been compared against an existing radiative transfer code.

  19. Volume scattering function and space distribution of the interplanetary dust cloud

    NASA Astrophysics Data System (ADS)

    Lamy, P. L.; Perrin, J.-M.

    1986-07-01

    The Volume Scattering Function (VSF) and the spatial distribution of the interplanetary dust cloud are examined by inversion of the brightness integral of the F-corona and the zodiacal light. Intensity and polarization observations are used to produce functional representations in the plane of symmetry of the interplanetary cloud, in the meridian plane, and at selected ecliptic latitudes. A modified fan model is shown to be compatible with the brightness data at d = 1 and 0.3 AU, and indicates that the VSF and the local polarization depend upon the heliocentric distance of the observer, but are independent of the latitude. The variations of the VSF and the polarization with respect to the scattering angle may be explained by the preferential removal of absorbing grains as beta-meteoroids.

  20. Spectral and Spatial Distribution of the Scattered Radiation of AN Electron Radiotherapy Beam

    NASA Astrophysics Data System (ADS)

    Bartesaghi, G.; Conti, V.; Mascagna, V.; Prest, M.; Mozzanica, A.; Frigerio, G.; Monti, A.; Vallazza, E.

    2006-04-01

    The characterization of the radiation scattered by the collimating system of a linear accelerator for medical applications is becoming a must given the increase in the survival of the radio-treated patients. This paper describes both the spectral and spatial study of the scattered radiation of an electron beam in the energy range 6-20 MeV, produced by a Varian CLINAC 1800 accelerator at the Radiotherapy Unit of the Sant'Anna Hospital in Como. The detectors used are plastic and fiber scintillators characterized by a timing response of ≈ 25 nsec in order to cope with the high fluxes. The results have been compared with a Montecarlo simulation based on Geant 3.21 and are presented both in terms of spectral and dose distributions.

  1. The total scattering atomic pair distribution function: New methodology for nanostructure analysis

    NASA Astrophysics Data System (ADS)

    Masadeh, Ahmad

    The conventional xray diffration (XRD) methods probe for the presence of long-range order (periodic structure) which are reflected in the Bragg peaks. Local structural deviations or disorder mainly affect the diffuse scattering intensity. In order to obtain structural information about both long-range order and local structure disorder, a technique that takes in account both Bragg and diffuse scattering need to be employed, such as the atomic pair distribution function (PDF) technique. This work introduces a PDF based methodology to quantitatively investigate nanostructure materials in general. The introduced methodology can be applied to extract quantitatively structural information about structure, crystallinity level, core/shell size, nanoparticle size, and inhomogeneous internal strain in the measured nanoparticles. This method is generally applicable to the characterization of the nano-scale solid, many of which may exhibit complex disorder and strain

  2. THEORY OF COMPTON SCATTERING BY ANISOTROPIC ELECTRONS

    SciTech Connect

    Poutanen, Juri; Vurm, Indrek E-mail: indrek.vurm@oulu.f

    2010-08-15

    Compton scattering plays an important role in various astrophysical objects such as accreting black holes and neutron stars, pulsars, relativistic jets, and clusters of galaxies, as well as the early universe. In most of the calculations, it is assumed that the electrons have isotropic angular distribution in some frame. However, there are situations where the anisotropy may be significant due to the bulk motions, or where there is anisotropic cooling by synchrotron radiation or an anisotropic source of seed soft photons. Here we develop an analytical theory of Compton scattering by anisotropic distribution of electrons that can significantly simplify the calculations. Assuming that the electron angular distribution can be represented by a second-order polynomial over the cosine of some angle (dipole and quadrupole anisotropies), we integrate the exact Klein-Nishina cross section over the angles. Exact analytical and approximate formulae valid for any photon and electron energies are derived for the redistribution functions describing Compton scattering of photons with arbitrary angular distribution by anisotropic electrons. The analytical expressions for the corresponding photon scattering cross section on such electrons, as well as the mean energy of scattered photons, its dispersion, and radiation pressure force are also derived. We apply the developed formalism to the accurate calculations of the thermal and kinematic Sunyaev-Zeldovich effects for arbitrary electron distributions.

  3. Intra-Beam and Touschek Scattering Computations for Beam with Non-Gaussian Longitudinal Distributions

    SciTech Connect

    Xiao, A.; Borland, M.

    2015-01-01

    Both intra-beamscattering (IBS) and the Touschek effect become prominent formulti-bend-achromat- (MBA-) based ultra-low-emittance storage rings. To mitigate the transverse emittance degradation and obtain a reasonably long beam lifetime, a higher harmonic rf cavity (HHC) is often proposed to lengthen the bunch. The use of such a cavity results in a non-gaussian longitudinal distribution. However, common methods for computing IBS and Touschek scattering assume Gaussian distributions. Modifications have been made to several simulation codes that are part of the elegant [1] toolkit to allow these computations for arbitrary longitudinal distributions. After describing thesemodifications, we review the results of detailed simulations for the proposed hybrid seven-bend-achromat (H7BA) upgrade lattice [2] for the Advanced Photon Source.

  4. COEVOLUTION BETWEEN SUPERMASSIVE BLACK HOLES AND BULGES IS NOT VIA INTERNAL FEEDBACK REGULATION BUT BY RATIONED GAS SUPPLY DUE TO ANGULAR MOMENTUM DISTRIBUTION

    SciTech Connect

    Cen, Renyue

    2015-05-20

    We reason that without physical fine-tuning, neither the supermassive black holes (SMBHs) nor the stellar bulges can self-regulate or inter-regulate by driving away already fallen cold gas to produce the observed correlation between them. We suggest an alternative scenario where the observed mass ratios of the SMBHs to bulges reflect the angular momentum distribution of infallen gas such that the mass reaching the stable accretion disk is a small fraction of that reaching the bulge region, averaged over the cosmological timescales. We test this scenario using high-resolution, large-scale cosmological hydrodynamic simulations, without active galactic nucleus (AGN) feedback, assuming the angular momentum distribution of gas landing in the bulge region yields a Mestel disk that is supported by independent simulations resolving the Bondi radii of SMBHs. A mass ratio of 0.1%–0.3% between the very low angular momentum gas that free falls to the subparsec region to accrete to the SMBH and the overall star formation rate is found. This ratio is found to increase with increasing redshift to within a factor of ∼2, suggesting that the SMBH-to-bulge ratio is nearly redshift independent, with a modest increase with redshift, which is a testable prediction. Furthermore, the duty cycle of AGNs with high Eddington ratios is expected to increase significantly with redshift. Finally, while SMBHs and bulges are found to coevolve on ∼30–150 Myr timescales or longer, there is indication that on still smaller timescales, the SMBH accretion and star formation may be less correlated.

  5. Extracting water and ion distributions from solution x-ray scattering experiments.

    PubMed

    Nguyen, Hung T; Pabit, Suzette A; Pollack, Lois; Case, David A

    2016-06-07

    Small-angle X-ray scattering measurements can provide valuable information about the solvent environment around biomolecules, but it can be difficult to extract solvent-specific information from observed intensity profiles. Intensities are proportional to the square of scattering amplitudes, which are complex quantities. Amplitudes in the forward direction are real, and the contribution from a solute of known structure (and from the waters it excludes) can be estimated from theory; hence, the amplitude arising from the solvent environment can be computed by difference. We have found that this "square root subtraction scheme" can be extended to non-zero q values, out to 0.1 Å(-1) for the systems considered here, since the phases arising from the solute and from the water environment are nearly identical in this angle range. This allows us to extract aspects of the water and ion distributions (beyond their total numbers), by combining experimental data for the complete system with calculations for the solutes. We use this approach to test molecular dynamics and integral-equation (3D-RISM (three-dimensional reference interaction site model)) models for solvent structure around myoglobin, lysozyme, and a 25 base-pair duplex DNA. Comparisons can be made both in Fourier space and in terms of the distribution of interatomic distances in real space. Generally, computed solvent distributions arising from the MD simulations fit experimental data better than those from 3D-RISM, even though the total small-angle X-ray scattering patterns are very similar; this illustrates the potential power of this sort of analysis to guide the development of computational models.

  6. Impact of inhomogeneous optical scattering coefficient distribution on recovery of optical absorption coefficient maps using tomographic photoacoustic data.

    PubMed

    Li, Xiaoqi; Jiang, Huabei

    2013-02-21

    We present a study through extensive simulation that considers the impact of inhomogeneous optical scattering coefficient distribution on recovery of optical absorption coefficient maps using tomographic photoacoustic data collected from media mimicking breast tissue. We found that while the impact of scattering heterogeneities/targets is modest on photoacoustic recovery of optical absorption coefficients, the impact of scattering contrast caused by adipose tissue, a layer of normal tissue along the boundary of the breast, is dramatic on reconstruction of optical absorption coefficients using photoacoustic data-up to 25.8% relative error in recovering the absorption coefficient is estimated in such cases. To overcome this problem, we propose a new method to enhance photoacoustic recovery of the optical absorption coefficient in heterogeneous media by considering inhomogeneous scattering coefficient distribution provided by diffuse optical tomography (DOT). Results from extensive simulations show that photoacoustic recovery of absorption coefficient maps can be improved considerably with a priori scattering information from DOT.

  7. Polarization and Angular Distribution of Ll X-Ray Following Inner-Shell 2p3/2 Photoionization of Magnesium-Like Ions

    NASA Astrophysics Data System (ADS)

    Ma, Kun; Dong, Chen-Zhong; Xie, Lu-You; Ding, Xiao-Bin; Qu, Yi-Zhi

    2014-05-01

    The inner-shell 2p3/2 photoionization and the subsequent decay of Mg-like Fe14+, Cd36+, W62+ and U80+ ions are studied theoretically within the multiconfiguration Dirac—Fock method and the density matrix theory. Special attention is paid to exploring the influence of the non-dipole terms which arise from the multipole expansion of the electron-photon interaction in the photoionization process. The results show that the non-dipole contribution to the total cross section, the magnetic sublevels cross section of the photoionization process, the degree of linear polarization and angular distribution of the subsequent characteristic x-ray radiation become more important with the increase of photons energy and atomic nuclear Z. Especially for the cross section and the degree of linear polarization, the non-dipole contribution arrives at 50% for U80+ at four time energy threshold units. However, for the angular distribution, the maximum contribution does not exceed 4%, even for U80+ ions.

  8. Combined linear polarization and angular distribution measurements of x-rays for precise determination of multipole-mixing in characteristic transitions of high-Z systems

    NASA Astrophysics Data System (ADS)

    Weber, G.; Bräuning, H.; Surzhykov, A.; Brandau, C.; Fritzsche, S.; Geyer, S.; Grisenti, R. E.; Hagmann, S.; Hahn, C.; Hess, R.; Hess, S.; Kozhuharov, C.; Kühnel, M.; Märtin, R.; Petridis, N.; Spillmann, U.; Trotsenko, S.; Winters, D. F. A.; Stöhlker, Th

    2015-07-01

    By applying novel-type position sensitive x-ray detectors as Compton polarimeters we recently performed a study of the linear polarization of Lyman-{{α }1} radiation following radiative electron capture into initially bare uranium ions. It was found that a model-independent determination of the ratio of the E1 and M2 transition amplitudes, and consequently of the corresponding transition rates, is feasible by combining the linear polarization data with a measurement of the angular distribution of the emitted radiation. In this work a detailed description of the underlying experimental technique for combined measurements of the linear polarization and the angular distribution of characteristic transitions in high-Z ions is presented. Special emphasis is given to the application of two, two-dimensional position-sensitive x-ray detectors for Compton polarimetry of hard x-rays. Moreover, we demonstrate the polarimeter efficiency of such detector systems can be significantly improved if events, where the charge is spread over neighboring segments, are reconstructed to be used in the polarization analysis.

  9. Investigation of the local structure of mixtures of an ionic liquid with polar molecular species through molecular dynamics: cluster formation and angular distributions.

    PubMed

    Carrete, Jesús; Méndez-Morales, Trinidad; Cabeza, Óscar; Lynden-Bell, Ruth M; Gallego, Luis J; Varela, Luis M

    2012-05-24

    In this work, we used molecular dynamics simulations to analyze in detail the spatial distributions of the different constituents in mixtures of 1-butyl-3-methylimidazolium tetrafluoroborate with three polar molecular species: water and two alcohols of different chain lengths (methanol and ethanol). In particular, we report results regarding the influence of the chosen species and its concentration on the formation of ionic and molecular clusters over the whole miscibility range, as well as on the angular distribution of polar molecules around the anion and the cation in these systems. Both analyses showed that addition of a molecular species breaks down the polar network of the pure ionic liquid in clusters whose mean size decreases progressively as more molecules are added. At very high concentrations of the molecular species, the ions are found to be isolated in mixtures with water and methanol, but they tend to form pairs in ethanol. In mixtures with water we identified large clusters that form a water network at very high water concentrations, while at low water concentrations polar molecules tend to form smaller aggregates. In contrast, in mixtures with alkanols there is no evidence of the formation of large alcohol clusters at any concentration. Spatial order in alcohol was also studied by means of the Kirkwood G factor, reaching the conclusion that the angular correlations which appear in pure alcohols due to dipole interactions are destroyed by the ionic liquid, even when present only in tiny amounts.

  10. Multi-Temporal InSAR Analysis of Wenjiagou Landslide using Distributed Scatterers

    NASA Astrophysics Data System (ADS)

    Wang, Chao; Zhang, Zhengjia; Zhang, Hong; Tang, Yixian

    2015-05-01

    This paper presents a multi-temporal InSAR method to monitor landslide movement at wenjiagou using Distributed Scatterers (DS). In this study, TDX and TSX bistatic SAR data are processed to obtain high precision DEM of the pose-landslide. DSs are efficiently identified using classified information and statistical characteristics. A series of Radarsat-2 HH polarization images collected in Wenjiagou from 2014.6 to 2014.9 are used to generate the deformation of the giant landslide. The experimental results show that there are obvious ground movement detected in the depositing area of the landslide during the observation.

  11. Influence of planar oscillations on scattered ion energy distributions in transmission ion channeling

    NASA Astrophysics Data System (ADS)

    Bailes, A. A.; Seiberling, L. E.

    1999-06-01

    Utilizing the transmission ion channeling technique and a Monte Carlo simulation of the channeling of He ions in Si, we have been able to determine surface structure by comparing experimental to simulated scattered ion energy distributions. In analyzing data for {110} beam incidence, we have found that planar oscillations persist well past 2000 Å in our Monte Carlo simulations. These oscillations yield no benefit to this method of data analysis but can make analysis more difficult by the requirement for more accurate Si thickness determination.

  12. Simulating the Daylight Performance of Complex Fenestration Systems Using Bidirectional Scattering Distribution Functions within Radiance

    SciTech Connect

    Ward, Gregory; Mistrick, Ph.D., Richard; Lee, Eleanor; McNeil, Andrew; Jonsson, Ph.D., Jacob

    2011-01-21

    We describe two methods which rely on bidirectional scattering distribution functions (BSDFs) to model the daylighting performance of complex fenestration systems (CFS), enabling greater flexibility and accuracy in evaluating arbitrary assemblies of glazing, shading, and other optically-complex coplanar window systems. Two tools within Radiance enable a) efficient annual performance evaluations of CFS, and b) accurate renderings of CFS despite the loss of spatial resolution associated with low-resolution BSDF datasets for inhomogeneous systems. Validation, accuracy, and limitations of the methods are discussed.

  13. Hadron transverse momentum distributions in muon deep inelastic scattering at 160 GeV/ c

    NASA Astrophysics Data System (ADS)

    Adolph, C.; Alekseev, M. G.; Alexakhin, V. Yu.; Alexandrov, Yu.; Alexeev, G. D.; Amoroso, A.; Andrieux, V.; Austregesilo, A.; Badełek, B.; Balestra, F.; Barth, J.; Baum, G.; Bedfer, Y.; Berlin, A.; Bernhard, J.; Bertini, R.; Bicker, K.; Bieling, J.; Birsa, R.; Bisplinghoff, J.; Boer, M.; Bordalo, P.; Bradamante, F.; Braun, C.; Bravar, A.; Bressan, A.; Büchele, M.; Burtin, E.; Capozza, L.; Chiosso, M.; Chung, S. U.; Cicuttin, A.; Crespo, M. L.; Dalla Torre, S.; Dasgupta, S. S.; Dasgupta, S.; Denisov, O. Yu.; Donskov, S. V.; Doshita, N.; Duic, V.; Dünnweber, W.; Dziewiecki, M.; Efremov, A.; Elia, C.; Eversheim, P. D.; Eyrich, W.; Faessler, M.; Ferrero, A.; Filin, A.; Finger, M.; Finger, M.; Fischer, H.; Franco, C.; du Fresne von Hohenesche, N.; Friedrich, J. M.; Frolov, V.; Garfagnini, R.; Gautheron, F.; Gavrichtchouk, O. P.; Gerassimov, S.; Geyer, R.; Giorgi, M.; Gnesi, I.; Gobbo, B.; Goertz, S.; Grabmüller, S.; Grasso, A.; Grube, B.; Gushterski, R.; Guskov, A.; Guthörl, T.; Haas, F.; von Harrach, D.; Heinsius, F. H.; Herrmann, F.; Heß, C.; Hinterberger, F.; Höppner, Ch.; Horikawa, N.; d'Hose, N.; Huber, S.; Ishimoto, S.; Ivanshin, Yu.; Iwata, T.; Jahn, R.; Jary, V.; Jasinski, P.; Joosten, R.; Kabuß, E.; Kang, D.; Ketzer, B.; Khaustov, G. V.; Khokhlov, Yu. A.; Kisselev, Yu.; Klein, F.; Klimaszewski, K.; Koivuniemi, J. H.; Kolosov, V. N.; Kondo, K.; Königsmann, K.; Konorov, I.; Konstantinov, V. F.; Kotzinian, A. M.; Kouznetsov, O.; Krämer, M.; Kroumchtein, Z. V.; Kuchinski, N.; Kunne, F.; Kurek, K.; Kurjata, R. P.; Lednev, A. A.; Lehmann, A.; Levorato, S.; Lichtenstadt, J.; Maggiora, A.; Magnon, A.; Makke, N.; Mallot, G. K.; Mann, A.; Marchand, C.; Martin, A.; Marzec, J.; Matsuda, H.; Matsuda, T.; Meshcheryakov, G.; Meyer, W.; Michigami, T.; Mikhailov, Yu. V.; Morreale, A.; Nagaytsev, A.; Nagel, T.; Nerling, F.; Neubert, S.; Neyret, D.; Nikolaenko, V. I.; Novy, J.; Nowak, W.-D.; Nunes, A. S.; Olshevsky, A. G.; Ostrick, M.; Panknin, R.; Panzieri, D.; Parsamyan, B.; Paul, S.; Piragino, G.; Platchkov, S.; Pochodzalla, J.; Polak, J.; Polyakov, V. A.; Pretz, J.; Quaresma, M.; Quintans, C.; Rajotte, J.-F.; Ramos, S.; Reicherz, G.; Rocco, E.; Rodionov, V.; Rondio, E.; Rossiyskaya, N. S.; Ryabchikov, D. I.; Samoylenko, V. D.; Sandacz, A.; Sapozhnikov, M. G.; Sarkar, S.; Savin, I. A.; Sbrizzai, G.; Schiavon, P.; Schill, C.; Schlüter, T.; Schmidt, A.; Schmidt, K.; Schmitt, L.; Schmïden, H.; Schönning, K.; Schopferer, S.; Schott, M.; Shevchenko, O. Yu.; Silva, L.; Sinha, L.; Sirtl, S.; Slunecka, M.; Sosio, S.; Sozzi, F.; Srnka, A.; Steiger, L.; Stolarski, M.; Sulc, M.; Sulej, R.; Suzuki, H.; Sznajder, P.; Takekawa, S.; Ter Wolbeek, J.; Tessaro, S.; Tessarotto, F.; Thibaud, F.; Uhl, S.; Uman, I.; Vandenbroucke, M.; Virius, M.; Wang, L.; Weisrock, T.; Wilfert, M.; Windmolders, R.; Wiślicki, W.; Wollny, H.; Zaremba, K.; Zavertyaev, M.; Zemlyanichkina, E.; Zhuravlev, N.; Ziembicki, M.

    2013-08-01

    Multiplicities of charged hadrons produced in deep inelastic muon scattering off a 6LiD target have been measured as a function of the DIS variables x Bj , Q 2, W 2 and the final state hadron variables p T and z. The distributions are fitted with a single exponential function at low values of to determine the dependence of on x Bj , Q 2, W 2 and z. The z-dependence of is shown to be a potential tool to extract the average intrinsic transverse momentum squared of partons, , as a function of x Bj and Q 2 in a leading order QCD parton model.

  14. A New Modeling for the Changes in the Distribution of Scatterers in Cirrhotic Liver

    NASA Astrophysics Data System (ADS)

    Hara, Takashi; Hachiya, Hiroyuki

    2000-05-01

    The human liver is composed of small hexagonal structures called liver lobules. Cirrhosis destroys these liver lobules and replaces them with permanent connective tissue referred to as regenerative nodules. In this paper, we propose a new modeling technique for changes in the scatterer distribution in liver tissue considering the structure of liver lobules to obtain images of the cirrhotic liver over continuous stages. Using these images, we analyze the relationship between changes in characteristics of biological tissue and changes in B-mode images during progressive liver cirrhosis.

  15. Distributed data processing and analysis environment for neutron scattering experiments at CSNS

    NASA Astrophysics Data System (ADS)

    Tian, H. L.; Zhang, J. R.; Yan, L. L.; Tang, M.; Hu, L.; Zhao, D. X.; Qiu, Y. X.; Zhang, H. Y.; Zhuang, J.; Du, R.

    2016-10-01

    China Spallation Neutron Source (CSNS) is the first high-performance pulsed neutron source in China, which will meet the increasing fundamental research and technique applications demands domestically and overseas. A new distributed data processing and analysis environment has been developed, which has generic functionalities for neutron scattering experiments. The environment consists of three parts, an object-oriented data processing framework adopting a data centered architecture, a communication and data caching system based on the C/S paradigm, and data analysis and visualization software providing the 2D/3D experimental data display. This environment will be widely applied in CSNS for live data processing.

  16. ORBITAL DISTRIBUTIONS OF CLOSE-IN PLANETS AND DISTANT PLANETS FORMED BY SCATTERING AND DYNAMICAL TIDES

    SciTech Connect

    Nagasawa, M.; Ida, S.

    2011-12-01

    We investigated the formation of close-in planets (hot Jupiters) by a combination of mutual scattering, Kozai effect, and tidal circularization, through N-body simulations of three gas giant planets, and compared the results with discovered close-in planets. We found that in about 350 cases out of 1200 runs ({approx}30%), the eccentricity of one of the planets is excited highly enough for tidal circularization by mutual close scatterings followed by secular effects due to outer planets, such as the Kozai mechanism, and the planet becomes a close-in planet through the damping of eccentricity and semimajor axis. The formation probability of close-in planets by such scattering is not affected significantly by the effect of the general relativity and inclusion of inertial modes in addition to fundamental modes in the tides. Detailed orbital distributions of the formed close-in planets and their counterpart distant planets in our simulations were compared with observational data. We focused on the possibility for close-in planets to retain non-negligible eccentricities ({approx}> 0.1) on timescales of {approx}10{sup 9} yr and have high inclinations, because close-in planets in eccentric or highly inclined orbits have recently been discovered. In our simulations we found that as many as 29% of the close-in planets have retrograde orbits, and the retrograde planets tend to have small eccentricities. On the other hand, eccentric close-in planets tend to have orbits of small inclinations.

  17. Total Scattering and Pair Distribution Function Analysis in Modelling Disorder in PZN

    SciTech Connect

    Whitfield, Ross E.; Goossens, Darren J; Welberry, T. R.

    2016-01-01

    The ability of the pair distribution function (PDF) analysis of total scattering (TS) from a powder to determine the local ordering in ferroelectric PZN (PbZn1/3Nb2/3O3) has been explored by comparison with a model established using single-crystal diffuse scattering (SCDS). While X-ray PDF analysis is discussed, the focus is on neutron diffraction results because of the greater extent of the data and the sensitivity of the neutron to oxygen atoms, the behaviour of which is important in PZN. The PDF was shown to be sensitive to many effects not apparent in the average crystal structure, including variations in the B-site—O separation distances and the fact that (110) Pb2+ displacements are most likely. A qualitative comparison between SCDS and the PDF shows that some features apparent in SCDS were not apparent in the PDF. These tended to pertain to short-range correlations in the structure, rather than to interatomic separations. For example, in SCDS the short-range alternation of the B-site cations was quite apparent in diffuse scattering at (½ ½ ½), whereas it was not apparent in the PDF.

  18. Total Scattering and Pair Distribution Function Analysis in Modelling Disorder in PZN

    DOE PAGES

    Whitfield, Ross E.; Goossens, Darren J; Welberry, T. R.

    2016-01-01

    The ability of the pair distribution function (PDF) analysis of total scattering (TS) from a powder to determine the local ordering in ferroelectric PZN (PbZn1/3Nb2/3O3) has been explored by comparison with a model established using single-crystal diffuse scattering (SCDS). While X-ray PDF analysis is discussed, the focus is on neutron diffraction results because of the greater extent of the data and the sensitivity of the neutron to oxygen atoms, the behaviour of which is important in PZN. The PDF was shown to be sensitive to many effects not apparent in the average crystal structure, including variations in the B-site—O separationmore » distances and the fact that (110) Pb2+ displacements are most likely. A qualitative comparison between SCDS and the PDF shows that some features apparent in SCDS were not apparent in the PDF. These tended to pertain to short-range correlations in the structure, rather than to interatomic separations. For example, in SCDS the short-range alternation of the B-site cations was quite apparent in diffuse scattering