Science.gov

Sample records for gamma angular distributions

  1. 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.

  2. 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.

  3. 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.

  4. Directional Stand-off Detection of Fast Neutrons and Gammas Using Angular Scattering Distributions

    SciTech Connect

    Vanier P. e.; Dioszegi, I.; Salwen, C.; Forman, L.

    2009-10-25

    We have investigated the response of a DoubleScatter Neutron Spectrometer (DSNS) for sources at long distances (gr than 200 meters). We find that an alternative method for analyzing double scatter data avoids some uncertainties introduced by amplitude measurements in plastic scintillators.Time of flight is used to discriminate between gamma and neutron events, and the kinematic distributions of scattering angles are assumed to apply. Non-relativistic neutrons are most likely to scatter at 45°, while gammas with energies greater than 2 MeV are most likely to be forward scattered. The distribution of scattering angles of fission neutrons arriving from a distant point source generates a 45° cone, which can be back-projected to give the source direction. At the same time, the distribution of Compton-scattered gammas has a maximum in the forward direction, and can be made narrower by selecting events that deposit minimal energy in the first scattering event. We have further determined that the shape of spontaneous fission neutron spectra at ranges gr than 110 m is still significantly different from thecosmic ray background.

  5. Perturbed angular distribution of 237Np gamma rays from the 237U parent

    NASA Astrophysics Data System (ADS)

    Ansaldo, Eduardo J.

    1980-09-01

    The anisotropy was measured for the 208.0-59.54 keV gamma cascade in 237Np, corresponding to a positive sign for the M1-E2 mixing ratio of the 208.0 keV transition. The sources were prepared by means of the 238U(e, n) reaction. A discussion on the implications of the present results for the study of hyperfine interactions in neptunium compounds and alloys is included.

  6. Gamma-Ray Angular Distribution in Coulomb Excitation Experiments at Intermediate Energies as a Signature of Electromagnetic and Nuclear Forces in Peripheral Collisions

    NASA Astrophysics Data System (ADS)

    Bednarczyk, P.; Grębosz, J.; Maj, A.; Kmiecik, M.; Męczyński, W.; Styczeń, J.; Wollersheim, H. J.; Gerl, J.; Górska, M.; Reiter, P.; Bracco, A.; Camera, F.

    2009-03-01

    In Coulex experiments at intermediate beam energies besides electromagnetic forces the nuclear interaction may occur. These two excitation mechanisms result in emission of gamma -rays with a characteristic angular distribution W(theta ). Measurement of W(theta ) was performed at the RISING fast beam set-up to probe the electromagnetic-nuclear interface. Unexpectedly large hadronic-like contribution was observed when high Z projectiles were used.

  7. 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.

  8. The GAMMA-400 gamma-ray telescope angular resolution

    NASA Astrophysics Data System (ADS)

    Kheymits, Maxim; Leonov, Alexey

    The measurements of gamma-ray fluxes and cosmic-ray electrons and positrons in the energy range from 100 MeV to several TeV, which will be realized by the specially designed GAMMA-400 gamma-ray telescope, concern with the following broad range of science topics. Search for signatures of dark matter, surveying the celestial sphere in order to study point and extended sources of gamma-rays, measuring the energy spectra of Galactic and extragalactic diffuse gamma-ray emission, study of gamma-ray bursts and gamma-ray emission from the Sun. To clarify these scientific problems with the new experimental data the GAMMA-400 gamma-ray telescope possesses unique physical characteristics comparing with previous and present experiments. For gamma-ray energies more than 100 GeV GAMMA-400 provides the energy resolution nearby 1% and angular resolution better than 0.02 deg. The methods, developed to reconstruct the direction of incident gamma photon, are presented in this paper. The main point concerns with the space topology of high energy gamma photon interaction in the matter of GAMMA-400. Multiple secondary particles, generated inside gamma-ray telescope, produce significant problems to restore the direction of initial gamma photon. Also back-splash particles, i.e., charged particles and gamma photons generated in calorimeter and moved upward, mask the initial tracks of electron/positron pair from conversion of incident gamma photon. The processed methods allow us to reconstruct the direction of electromagnetic shower axis and extract the electron/positron trace. As a result, the direction of incident gamma photon with the energy of 100 GeV is calculated with an accuracy of more than 0.02 deg.

  9. Angular distribution measurement of gamma rays from inelastic neutron scattering on 56Fe at the nELBE time-of-flight facility

    NASA Astrophysics Data System (ADS)

    Dietz, Mirco; Bemmerer, Daniel; Beyer, Roland; Gohl, Stefan; Junghans, Arnd R.; Kögler, Toni; Massarczyk, Ralph; Müller, Stefan E.; Schwengner, Ronald; Szücs, Tamás; Takacs, Marcell P.; Wagner, Andreas; Wagner, Louis

    2017-09-01

    Inelastic neutron scattering from 56Fe was studied at the nELBE time-of-flight facility. The incoming neutron energy ranges from 100 keV to 10 MeV in the fast neutron spectrum, where high precision nuclear data are needed. A detector setup has been installed to investigate the γ-ray angular distributions. It contains five HPGe and five LaBr3 detectors positioned at 30, 55, 90, 125 and 150 degrees relative to the beam axis. The intrinsic and the neutron induced background from the setup was subtracted by cyclical measurements with and without the natural Fe-target. Corrections for extended source efficiency and gamma-self-absorption, inside the target, were done using GEANT4 simulations. The angular distributions measured with the HPGe detectors are compared with earlier data. High neutron energy resolution up to a few keV was obtained with the LaBr3 detectors due to their much better time resolution.

  10. 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.

  11. Spectra and angular distributions of atmospheric gamma rays from 0.3 to 10 MeV at lambda = 40 deg

    NASA Technical Reports Server (NTRS)

    Ling, J. C.; Gruber, D. E.

    1977-01-01

    Measurements of the spectral and angular distributions of atmospheric gamma sq cm rays in the energy range 0.3-10 MeV over Palestine, Texas, at residual depths of 2.5 and 70 g/sq cm are reported. In confirmation of the general features of a model prediction, the measurements show at 2.5 g/sq cm upward moving fluxes greater than the downward moving fluxes, the effect increasing with energy, and approximate isotropy at 70 g/sq cm. Numerous characteristic gamma-ray lines were observed, most prominently at 0.511, 1.6, 2.3, 4.4, and 6.1 MeV. Their intensities were also compared with model predictions. Observations were made with an actively shielded scintillator counter with two detectors, one of aperture 50 deg FWHM and the other of 120 deg FWHM. Above 1 MeV, contributions to the counting rate from photons penetrating the shield annulus and from neutron interactions were large; they were studied by means of a Monte Carlo code and are extensively discussed.

  12. Spectra and angular distributions of atmospheric gamma rays from 0.3 to 10 MeV at lambda = 40 deg

    NASA Technical Reports Server (NTRS)

    Ling, J. C.; Gruber, D. E.

    1977-01-01

    Measurements of the spectral and angular distributions of atmospheric gamma sq cm rays in the energy range 0.3-10 MeV over Palestine, Texas, at residual depths of 2.5 and 70 g/sq cm are reported. In confirmation of the general features of a model prediction, the measurements show at 2.5 g/sq cm upward moving fluxes greater than the downward moving fluxes, the effect increasing with energy, and approximate isotropy at 70 g/sq cm. Numerous characteristic gamma-ray lines were observed, most prominently at 0.511, 1.6, 2.3, 4.4, and 6.1 MeV. Their intensities were also compared with model predictions. Observations were made with an actively shielded scintillator counter with two detectors, one of aperture 50 deg FWHM and the other of 120 deg FWHM. Above 1 MeV, contributions to the counting rate from photons penetrating the shield annulus and from neutron interactions were large; they were studied by means of a Monte Carlo code and are extensively discussed.

  13. 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.

  14. Angular, spectral, and time distributions of highest energy protons and associated secondary gamma rays and neutrinos propagating through extragalactic magnetic and radiation fields

    SciTech Connect

    Aharonian, F. A.; Kelner, S. R.; Prosekin, A. Yu.

    2010-08-15

    The angular, spectral, and temporal features of the highest energy protons and, accompanying them, secondary neutrinos and synchrotron gamma rays propagating through the intergalactic magnetic and radiation fields are studied using the analytical solutions of the Boltzmann transport equation obtained in the limit of the small-angle and continuous-energy-loss approximation.

  15. Gamma-Gamma Angular Correlation Measurements With GRIFFIN

    NASA Astrophysics Data System (ADS)

    Maclean, Andrew; Griffin Collaboration

    2016-09-01

    The goal of this work was to explore the sensitivity of the Gamma-Ray Infrastructure For Fundamental Investigations of Nuclei (GRIFFIN) 16 clover-detector γ-ray spectrometer at TRIUMF-ISAC to such γ - γ angular correlations. The methodology was established using both experimental measurements and Geant4 simulations that were used to create angular correlation templates for the GRIFFIN geometry. Direct comparisons were made between experimental data sets and the simulated angular correlation templates. A first in-beam test of the γ - γ angular correlation measurements with GRIFFIN was performed with a radioactive beam of 66Ga. Mixing ratios of δ = - 2 . 1(2) and δ = - 0 . 08(3) were measured for the 2+ ->2+ ->0+ 833-1039 keV and 1+ ->2+ ->0+ 2752-1039 keV cascades in the daughter nucleus 66Zn. These results are in good agreement with pervious literature values and the mixing ratio for the 833-1039 keV cascade has a higher precision. Also, the sensitivity to the 1333-1039 keV cascade, with its pronounced 0+ ->2+ ->0+ angular correlation, was measured.A test measurement of the superallowed Fermi β emitter 62Ga will also be discussed. Canada Foundation of Innovation, Natural Sciences and Engineering Research Council of Canada, National Research Council of Canada and Canadian Research Chairs Program.

  16. Effects of rotation of fissioning nuclei in the angular distributions of prompt neutrons and gamma rays originating from the polarized-neutron-induced fission of 233U and 235U nuclei

    NASA Astrophysics Data System (ADS)

    Danilyan, G. V.; Klenke, J.; Kopach, Yu. N.; Krakhotin, V. A.; Novitsky, V. V.; Pavlov, V. S.; Shatalov, P. B.

    2014-06-01

    The results of an experiment devoted to searches for effects of rotation of fissioning nuclei in the angular distributions of prompt neutrons and gamma rays originating from the polarized-neutron-induced fission of 233U nuclei are presented. The effects discovered in these angular distributions are opposite in sign to their counterparts in the polarized-neutron-induced fission of 235U nuclei. This is at odds with data on the relative signs of respective effects in the angular distribution of alpha particles from the ternary fission of the same nuclei and may be indicative of problems in the model currently used to describe the effect in question. The report on which this article is based was presented at the seminar held at the Institute of Theoretical and Experimental Physics and dedicated to the 90th anniversary of the birth of Yu.G. Abov, corresponding member of Russian Academy of Sciences, Editor in Chief of the journal Physics of Atomic Nuclei.

  17. Angular and Energy Characteristics of Gamma Field at the New Safe Confinement Construction Sit

    SciTech Connect

    Batiy, Valeriy; Glebkin, S; Pavlovskiy, L; Pravdyvyi, O; Rudko, Vladimir; Shcherbin, Vladimir; Stojanov, O; Schmieman, Eric A.

    2005-08-08

    To results of measurements of angular y and energy distribution of gamma-radiation at the cites of New Safe Confinement erection. The data analysis permitted to identify the main sources of gamma-radiation and to systematize the obtained results.

  18. Alpha-Gamma Angular Correlation in 209Po Using TIGRESS Integrated Plunger

    NASA Astrophysics Data System (ADS)

    Wu, Frank(Tongan); Chester, Aaron; Domingo, Thomas; Starosta, Kris; Williams, Jonathan; Hackman, Greg; Henderson, Jack; Henderson, Robert; Ruotsalainen, Panu

    2016-09-01

    Alpha decay provides a powerful tool to study structure of heavy nuclei with Z>83 (above Pb and Bi). When a gamma ray is emitted following the alpha decay, the alpha-gamma angular correlation can be used to assess the height of Coulomb and centrifugal barriers, which determine the rate of the alpha-particle tunnelling. This correlation can also be used as a tool for spin and parity assignments for the nuclear states involved in the decay. For that reason, an apparatus to study this correlation has been set up at TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, through coupling of the CsI wall of the Tigress Integrated Plunger (TIP) device and TRIUMF-ISAC Gamma-Ray Escape Suppressed Spectrometer (TIGRESS). Alpha-gamma sources can be positioned at the centre of the TIP chamber, which is installed within the centre of TIGRESS. In this study, the sensitivity of the setup is investigated from a comparison of measured and predicted alpha-gamma angular distribution from 209Po decay. So far, around 8000 events with extremely high signal-to-noise ratio have been identified by applying alpha-gamma time correlation and CsI pulse shape identification. Initial angular groups between TIP and TIGRESS detector pairs have been assigned and analyzed. Efficiency of each angular group is currently being investigated. Analysis and results will be presented and discussed.

  19. Effects of overburden, biomass and atmospheric inversions on energy and angular distributions of gamma rays from U, K, Th, and airborne radon sources. Final report

    SciTech Connect

    Rubin, R.M.; Leggett, D.; Wells, M.B.

    1980-12-01

    This report describes a set of radiation transport calculations that were run with the AHISN S/sub n/ discrete ordinates code and a point kernel code to determine the energy, polar angle and height in air distributions of the total and direct gamma-ray flux densities from: (1) uranium sources of 3.2, 200 and 800 ppM in a sandstone orebody covered with biomass densities of 0, 10.2, 20.4, 51.0 and 102.0 kg/m/sup 2/; (2) thorium sources of 12, 25 and 80 ppM in a sandstone ore body covered with biomass densities of 0, 10.2, 20.4, 51.0 and 102.0 kg/m/sup 2/; (3) potassium source (2.5 wt %) in a sandstone ore body covered with biomass densities of 0, 10.2, 20.4, 51.0 and 102.0 kg/m/sup 2/; (4) constant airborne source with height for no inversion and for inversion layer heights of 65.22, 260.32 and 458.43 m; (5) exponentially decreasing airborne source for no inversion and inversion layer heights of 65.22, 260.32 and 458.43 m; (6) 3.2 ppM uranium source in overburden layers of 10.266, 17.110, 26.399 and 32.509 cm thick; (7) 12 ppM thorium source in overburden layers of 10.266, 17.110, 26.399 and 32.509 cm; (8) 2.5 wt % of potassium in overburden layers of 10.266, 17.110, 26.399 and 32.509 cm thick; and (9) 3.2 ppM, 200 ppM, and 800 ppM uranium source in sandstone orebody covered with overburden thicknesses of 10.266, 17.110, 26.399 and 32.509 cm. Gamma-ray emission from the decay of natural uranium, thorium, radon, and potassium are given in a 45-energy group structure applicable to the energy windows used to map the potential uranium ore reserves.

  20. Angular distributions in the radiative decays of the state of charmonium originating from polarized collisions

    NASA Astrophysics Data System (ADS)

    Wong, Cheuk-Ping; Mok, Alex W. K.; Sit, Wai-Yu

    2015-03-01

    Using the helicity formalism, we calculate the combined angular distribution function of the two gamma photons ( and ) and the electron () in the triple cascade process , when and are arbitrarily polarized. We also derive six different partially integrated angular distribution functions which give the angular distributions of one or two particles in the final state. Our results show that by measuring the two-particle angular distribution of and and that of and , one can determine the relative magnitudes as well as the relative phases of all the helicity amplitudes in the two charmonium radiative transitions and.

  1. Angular distribution of turbulence in wave space

    NASA Technical Reports Server (NTRS)

    Coleman, G.; Ferziger, J. H.; Bertoglio, J. P.

    1987-01-01

    An alternative to the one-point closure model for turbulence, the large eddy simulation (LES), together with its more exact relative, direct numerical simulation (DNS) are discussed. These methods are beginning to serve as partial substitutes for turbulence experiments. The eddy damped quasi-normal Markovian (EDQNM) theory is reviewed. Angular distribution of the converted data was examined in relationship to EDQNM.

  2. 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.

  3. The angular momentum distribution in galactic halos

    NASA Astrophysics Data System (ADS)

    Quinn, P. J.; Zurek, W. H.

    1988-08-01

    N-body simulations are used to model the formation of individual galactic halos from scale-free density perturbations in universes dominated by cold, nondissipative dark matter. In well-mixed halos, the angular momentum distribution is shown to have a systematic behavior with power law index n corresponding to that found for circular rotation curves. For a given n, the distribution of angular momentum has the same trend with radius and energy as that implied for a halo in which all the matter has its maximum possible angular momentum. Dynamical mixing during the relaxation of the halo redistributes both angular momentum and binding energy in an orderly manner. The organized nature of the collapse means that relaxation is not completely violent and that the secondary infall paradigm, in its simplest form, needs to be modified to include the organizing effects of dynamical friction. It is shown that the Mestel hypothesis is not consistent with the final collapsed state of halos, but may be applicable to the collapse of the disks of spirals.

  4. Generation of gamma-ray beam with orbital angular momentum in the QED regime

    NASA Astrophysics Data System (ADS)

    Liu, Chen; Shen, Baifei; Zhang, Xiaomei; Shi, Yin; Ji, Liangliang; Wang, Wenpeng; Yi, Longqing; Zhang, Lingang; Xu, Tongjun; Pei, Zhikun; Xu, Zhizhan

    2016-09-01

    We propose a scheme to generate high-energy gamma-ray photons with an orbital angular momentum (OAM) from laser-plasma interactions by irradiating a circularly polarized Laguerre-Gaussian laser on a thin plasma target. The spin angular momentum and OAM are first transferred to electrons from the driving laser, and then the OAM is transferred to the gamma-ray photons from the electrons through quantum radiation. This scheme has been demonstrated by using three-dimensional quantum electrodynamics particle-in-cell simulations. The topological charge, chirality, and carrier-envelope phase of the short ultra-intense vortex laser can be revealed according to the energy distribution of gamma-ray emission.

  5. 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.

  6. Measurement of Z/gamma*+jet+X angular distributions in p anti-p collisions at s**(1/2) = 1.96.TeV

    SciTech Connect

    Abazov, Victor Mukhamedovich; Abbott, Braden Keim; Abolins, Maris A.; Acharya, Bannanje Sripath; Adams, Mark Raymond; Adams, Todd; Aguilo, Ernest; Ahsan, Mahsana; Alexeev, Guennadi D.; Alkhazov, Georgiy D.; Alton, Andrew K.; /Michigan U. /Augustana Coll., Sioux Falls /Northeastern U.

    2009-07-01

    We present the first measurements at a hadron collider of differential cross sections for Z/{gamma}* + jet + X production in {Delta}{phi}(Z, jet), |{Delta}y(Z, jet)| and |y{sub boost}(Z + jet)|. Vector boson production in association with jets is an excellent probe of QCD and constitutes the main background to many small cross section processes, such as associated Higgs production. These measurements are crucial tests of the predictions of perturbative QCD and current event generators, which have varied success in describing the data. Using these measurements as inputs in tuning event generators will increase the experimental sensitivity to rare signals.

  7. Models and theory for precompound angular distributions

    SciTech Connect

    Blann, M.; Pohl, B.A.; Remington, B.A. ); Scobel, W.; Trabandt, M. . 1. Inst. fuer Experimentalphysik); Byrd, R.C. ); Foster, C.C. ); Bonetti, R.; Chiesa, C. . Ist. di Fisica Generale Applicata); Grimes, S.M. (Ohio Univ

    1990-06-06

    We compare angular distributions calculated by folding nucleon- nucleon scattering kernels, using the theory of Feshbach, Kerman and Koonin, and the systematics of Kalbach, with a wide range of data. The data range from (n,xn) at 14 MeV incident energy to (p,xn) at 160 MeV incident energy. The FKK theory works well with one adjustable parameter, the depth of the nucleon-nucleon interaction potential. The systematics work well when normalized to the hybrid model single differential cross section prediction. The nucleon- nucleon scattering approach seems inadequate. 9 refs., 10 figs.

  8. Axions and the galactic angular momentum distribution

    NASA Astrophysics Data System (ADS)

    Banik, N.; Sikivie, P.

    2013-12-01

    We analyze the behavior of axion dark matter before it falls into a galactic gravitational potential well. The axions thermalize sufficiently fast by gravitational self-interactions that almost all go to their lowest-energy state consistent with the total angular momentum acquired from tidal torquing. That state is a state of rigid rotation on the turnaround sphere. It predicts the occurrence and detailed properties of the caustic rings of dark matter for which observational evidence had been found earlier. We show that the vortices in the axion Bose-Einstein condensate (BEC) are attractive, unlike those in superfluid He4 and dilute gases. We expect that a large fraction of the vortices in the axion BEC join into a single big vortex along the rotation axis of the galaxy. The resulting enhancement of caustic rings explains the typical size of the rises in the Milky Way rotation curve attributed to caustic rings. We show that baryons and ordinary cold dark matter particles are entrained by the axion BEC and acquire the same velocity distribution. The resulting baryonic angular momentum distribution gives a good qualitative fit to the distributions observed in dwarf galaxies. We give estimates of the minimum fraction of dark matter that is composed of axions.

  9. 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.

  10. Angular Rate Estimation Using a Distributed Set of Accelerometers

    PubMed Central

    Park, Sungsu; Hong, Sung Kyung

    2011-01-01

    A distributed set of accelerometers based on the minimum number of 12 accelerometers allows for computation of the magnitude of angular rate without using the integration operation. However, it is not easy to extract the magnitude of angular rate in the presence of the accelerometer noises, and even worse, it is difficult to determine the direction of a rotation because the angular rate is present in its quadratic form within the inertial measurement system equations. In this paper, an extended Kalman filter scheme to correctly estimate both the direction and magnitude of the angular rate through fusion of the angular acceleration and quadratic form of the angular rate is proposed. We also provide observability analysis for the general distributed accelerometers-based inertial measurement unit, and show that the angular rate can be correctly estimated by general nonlinear state estimators such as an extended Kalman filter, except under certain extreme conditions. PMID:22346651

  11. gamma-Carboxyglutamic acid distribution.

    PubMed

    Zytkovicz, T H; Nelsestuen, G L

    1976-09-24

    The distribution of the vitamin K-dependent amino acid, gamma-carboxyglutamic acid was examined in proteins from a variety of sources. Proteins examined include purified rat and bovine coagulation proteins, barium citrate-adsorbing proteins from trout plasma, lamprey plasma, earthworm hemolymph, army worm hemolymph, lobster hemolymph, E. coli B/5, soybean leaf, the protein lysate from the hemolymph cell of the horseshoe crab and parathyroid extract. Other purified proteins examined included human alpha-1-antitrypsin, pepsinogen, S-100, fetuin, tropomyosin-troponin and complement protein C-3. Of these, only the blood-cotting proteins and the vertebrate plasma samples were shown to contain gamma-carboxyglutamic acid.

  12. Bow Ties in the Sky. I: The Angular Structure of Inverse Compton Gamma-Ray Halos in the Fermi Sky

    NASA Astrophysics Data System (ADS)

    Broderick, Avery E.; Tiede, Paul; Shalaby, Mohamad; Pfrommer, Christoph; Puchwein, Ewald; Chang, Philip; Lamberts, Astrid

    2016-12-01

    Extended inverse Compton halos are generally anticipated around extragalactic sources of gamma rays with energies above 100 GeV. These result from inverse Compton scattered cosmic microwave background photons by a population of high-energy electron/positron pairs produced by the annihilation of the high-energy gamma rays on the infrared background. Despite the observed attenuation of the high-energy gamma rays, the halo emission has yet to be directly detected. Here, we demonstrate that in most cases these halos are expected to be highly anisotropic, distributing the upscattered gamma rays along axes defined either by the radio jets of the sources or oriented perpendicular to a global magnetic field. We present a pedagogical derivation of the angular structure in the inverse Compton halo and provide an analytic formalism that facilitates the generation of mock images. We discuss exploiting this fact for the purpose of detecting gamma-ray halos in a set of companion papers.

  13. A new all-digital time differential {gamma}-{gamma} angular correlation spectrometer

    SciTech Connect

    Nagl, Matthias; Vetter, Ulrich; Uhrmacher, Michael; Hofsaess, Hans

    2010-07-15

    A new digital time differential perturbed angular correlation spectrometer, designed to measure the energy of and coincidence time between correlated detector signals, here correlated {gamma} photons, is presented. The system overcomes limitations of earlier digital approaches and features improved performance and handling. By consequently separating the data recording and evaluation, it permits the simultaneous measurement of decays with several {gamma}-ray cascades at once and avoids the necessity of premeasurement configuration. Tests showed that the spectrometer reaches a time resolution of 460 ps [using a {sup 60}Co sample and Lu{sub 1.8}Y{sub 0.2}SiO{sub 5}:Ce (LYSO) scintillators, otherwise better than 100 ps], an energy resolution that is equivalent to the limit of the used scintillation material, and a processing capability of more than 200 000 {gamma} quanta per detector and second. Other possible applications of the presented methods include nuclear spectroscopy, positron emission tomography, time of flight studies, lidar, and radar.

  14. 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.

  15. 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.

  16. 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.

  17. GEANT4 Simulations of Gamma-Gamma Angular Correlations with GRIFFIN

    NASA Astrophysics Data System (ADS)

    Natzke, Connor; Griffin Collaboration

    2016-09-01

    The structure of very neutron rich isotopes has been of recent experimental interest for both nuclear astrophysics and fundamental nuclear structure investigations. In beta-minus decay specifically, beta-delayed gamma cascades can help to shed light on the spin and parity of the states involved. One of the world's most powerful decay spectroscopy tool is the Gamma-Ray Infrastructure For Fundamental Investigations of Nuclei (GRIFFIN) spectrometer at TRIUMF-ISAC in Vancouver, Canada. To investigate the feasibility of these experimental studies, GEANT4 simulations of neutron-rich nuclei are critical, as they are able to provide realistic estimates of what the experimental results may look like. The first such nucleus investigated was 44P, and both the temporal and angular γγ correlations were extracted. Furthermore the simulations were used to model various multipole decay possibilities which provide a powerful tool analyzing collected data from such facilities. In the future, the Facility for Rare Isotope Beams (FRIB) at MSU will be an ideal site for such studies on the most exotic nuclei.

  18. 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.

  19. Angular Signatures of Dark Matter in the Diffuse Gamma Ray Spectrum

    SciTech Connect

    Hooper, Dan; Serpico, Pasquale D.; /Fermilab

    2007-02-01

    Dark matter annihilating in our Galaxy's halo and elsewhere in the universe is expected to generate a diffuse flux of gamma rays, potentially observable with next generation satellite-based experiments, such as GLAST. In this article, we study the signatures of dark matter in the angular distribution of this radiation. Pertaining to the extragalactic contribution, we discuss the effect of the motion of the solar system with respect to the cosmological rest frame, and anisotropies due to the structure of our local universe. For the gamma ray flux from dark matter in our own Galactic halo, we discuss the effects of the offset position of the solar system, the Compton-Getting effect, the asphericity of the Milky Way halo, and the signatures of nearby substructure. We explore the prospects for the detection of these features by the GLAST satellite and find that, if {approx} 10% or more of the diffuse gamma ray background observed by EGRET is the result of dark matter annihilations, then GLAST should be sensitive to anisotropies down to the 0.1% level. Such precision would be sufficient to detect many, if not all, of the signatures discussed in this paper.

  20. Effects of p-wave annihilation on the angular power spectrum of extragalactic gamma-rays from dark matter annihilation

    NASA Astrophysics Data System (ADS)

    Campbell, Sheldon; Dutta, Bhaskar

    2011-10-01

    We present a formalism for estimating the angular power spectrum of extragalactic gamma-rays produced by dark matter annihilating with any general velocity-dependent cross section. The relevant density and velocity distribution of dark matter is modeled as an ensemble of smooth, universal, rigid, disjoint, spherical halos with distribution and universal properties constrained by simulation data. We apply this formalism to theories of dark matter with p-wave annihilation, for which the relative-velocity-weighted annihilation cross section is σv=a+bv2. We determine that this significantly increases the gamma-ray power if b/a≳106. The effect of p-wave annihilation on the angular power spectrum is very similar for the sample of particle physics models we explored, suggesting that the important effect for a given b/a is largely determined by the cosmic dark matter distribution. If the dark matter relic from strong p-wave theories is thermally produced, the intensities of annihilation gamma-rays are strongly p-wave suppressed, making them difficult to observe. If an angular power spectrum consistent with a strong p wave were to be observed, it would likely indicate nonthermal production of dark matter in the early Universe.

  1. 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.

  2. 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.

  3. Physical Performance of GAMMA-400 Telescope. Angular Resolution, Proton and Electron Separation

    NASA Astrophysics Data System (ADS)

    Leonov, A. A.; Galper, A. O. Arkhangelskaja, I. V.; Arkhangelskiy, A. I.; Gusakov, Y. V.; Kadilin, V. V.; Kheymits, M. D.; Mikhailov, V. V.; Naumov, P. Y.; Runtso, M. F.; Suchkov, S. I.; Topchiev, N. P.; Yurkin, Y. T.; Zverev, V. G.

    The specially designed GAMMA-400 gamma-ray telescope will realize the measurements of gamma-ray fluxes and cosmic-ray electrons and positrons in the energy range from 100 MeV to several TeV. Such measurements concern with the following broad range of scientific topics. Search for signatures of dark matter, investigation of gamma-ray point and extended sources, studies of the energy spectra of Galactic and extragalactic diffuse emission, studies of gamma-ray bursts and gamma-ray emission from the active Sun, as well as high-precision measurements of spectra of high-energy electrons and positrons, protons, and nuclei up to the knee. To clarify these scientific problems with the new experimental data the GAMMA-400 gamma-ray telescope possesses unique physical characteristics comparing with previous and present experiments. For gamma-ray energies more than 100 GeV GAMMA-400 provides the energy resolution ∼1% and angular resolution better than 0.02 deg. The methods, developed to reconstruct the direction of incident gamma photon, are presented in this paper, as well as, the capability of the GAMMA-400 gamma-ray telescope to distinguish electrons and positrons from protons in cosmic rays is discussed.

  4. Orbital angular momentum in optical waves propagating through distributed turbulence.

    PubMed

    Sanchez, Darryl J; Oesch, Denis W

    2011-11-21

    This is the second of two papers demonstrating that photons with orbital angular momentum can be created in optical waves propagating through distributed turbulence. In the companion paper, it is shown that propagation through atmospheric turbulence can create non-trivial angular momentum. Here, we extend the result and demonstrate that this momentum is, at least in part, orbital angular momentum. Specifically, we demonstrate that branch points (in the language of the adaptive optic community) indicate the presence of photons with non-zero OAM. Furthermore, the conditions required to create photons with non-zero orbital angular momentum are ubiquitous. The repercussions of this statement are wide ranging and these are cursorily enumerated. © 2011 Optical Society of America

  5. 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.

  6. 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.

  7. Measurement of Dijet Angular Distributions and Search for Quark Compositeness

    NASA Astrophysics Data System (ADS)

    Abbott, B.; Abolins, M.; Acharya, B. S.; Adam, I.; Adams, D. L.; Adams, M.; Ahn, S.; Aihara, H.; Alves, G. A.; Amidi, E.; Amos, N.; Anderson, E. W.; Astur, R.; Baarmand, M. M.; Baden, A.; Balamurali, V.; Balderston, J.; Baldin, B.; Banerjee, S.; Bantly, J.; Bartlett, J. F.; Bazizi, K.; Belyaev, A.; Beri, S. B.; Bertram, I.; Bezzubov, V. A.; Bhat, P. C.; Bhatnagar, V.; Bhattacharjee, M.; Biswas, N.; Blazey, G.; Blessing, S.; Bloom, P.; Boehnlein, A.; Bojko, N. I.; Borcherding, F.; Boswell, C.; Brandt, A.; Brock, R.; Bross, A.; Buchholz, D.; Burtovoi, V. S.; Butler, J. M.; Carvalho, W.; Casey, D.; Casilum, Z.; Castilla-Valdez, H.; Chakraborty, D.; Chang, S.-M.; Chekulaev, S. V.; Chen, L.-P.; Chen, W.; Choi, S.; Chopra, S.; Choudhary, B. C.; Christenson, J. H.; Chung, M.; Claes, D.; Clark, A. R.; Cobau, W. G.; Cochran, J.; Cooper, W. E.; Cretsinger, C.; Cullen-Vidal, D.; Cummings, M. A.; Cutts, D.; Dahl, O. I.; Davis, K.; de, K.; del Signore, K.; Demarteau, M.; Denisov, D.; Denisov, S. P.; Diehl, H. T.; Diesburg, M.; di Loreto, G.; Draper, P.; Ducros, Y.; Dudko, L. V.; Dugad, S. R.; Edmunds, D.; Ellison, J.; Elvira, V. D.; Engelmann, R.; Eno, S.; Eppley, G.; Ermolov, P.; Eroshin, O. V.; Evdokimov, V. N.; Fahland, T.; Fatyga, M.; Fatyga, M. K.; Featherly, J.; Feher, S.; Fein, D.; Ferbel, T.; Finocchiaro, G.; Fisk, H. E.; Fisyak, Y.; Flattum, E.; Forden, G. E.; Fortner, M.; Frame, K. C.; Fuess, S.; Gallas, E.; Galyaev, A. N.; Gartung, P.; Geld, T. L.; Genik, R. J.; Genser, K.; Gerber, C. E.; Gibbard, B.; Glenn, S.; Gobbi, B.; Goforth, M.; Goldschmidt, A.; Gómez, B.; Gómez, G.; Goncharov, P. I.; González Solís, J. L.; Gordon, H.; Goss, L. T.; Gounder, K.; Goussiou, A.; Graf, N.; Grannis, P. D.; Green, D. R.; Green, J.; Greenlee, H.; Grim, G.; Grinstein, S.; Grossman, N.; Grudberg, P.; Grünendahl, S.; Guglielmo, G.; Guida, J. A.; Guida, J. M.; Gupta, A.; Gurzhiev, S. N.; Gutierrez, P.; Gutnikov, Y. E.; Hadley, N. J.; Haggerty, H.; Hagopian, S.; Hagopian, V.; Hahn, K. S.; Hall, R. E.; Hanlet, P.; Hansen, S.; Hauptman, J. M.; Hedin, D.; Heinson, A. P.; Heintz, U.; Hernández-Montoya, R.; Heuring, T.; Hirosky, R.; Hobbs, J. D.; Hoeneisen, B.; Hoftun, J. S.; Hsieh, F.; Hu, Ting; Hu, Tong; Huehn, T.; Ito, A. S.; James, E.; Jaques, J.; Jerger, S. A.; Jesik, R.; Jiang, J. Z.-Y.; Joffe-Minor, T.; Johns, K.; Johnson, M.; Jonckheere, A.; Jones, M.; Jöstlein, H.; Jun, S. Y.; Jung, C. K.; Kahn, S.; Kalbfleisch, G.; Kang, J. S.; Kehoe, R.; Kelly, M. L.; Kim, C. L.; Kim, S. K.; Klatchko, A.; Klima, B.; Klopfenstein, C.; Klyukhin, V. I.; Kochetkov, V. I.; Kohli, J. M.; Koltick, D.; Kostritskiy, A. V.; Kotcher, J.; Kotwal, A. V.; Kourlas, J.; Kozelov, A. V.; Kozlovski, E. A.; Krane, J.; Kirshnaswamy, M. R.; Krzywdzinski, S.; Kunori, S.; Lami, S.; Lan, H.; Lander, R.; Landry, F.; Landsberg, G.; Lauer, B.; Leflat, A.; Li, H.; Li, J.; Li-Demarteau, Q. Z.; Lima, J. G.; Lincoln, D.; Linn, S. L.; Linnemann, J.; Lipton, R.; Liu, Q.; Liu, Y. C.; Lobkowicz, F.; Loken, S. C.; Lökös, S.; Lueking, L.; Lyon, A. L.; Maciel, A. K.; Madaras, R. J.; Madden, R.; Magaña-Mendoza, L.; Mani, S.; Mao, H. S.; Markeloff, R.; Marshall, T.; Martin, M. I.; Mauritz, K. M.; May, B.; Mayorov, A. A.; McCarthy, R.; McDonald, J.; McKibben, T.; McKinley, J.; McMahon, T.; Melanson, H. L.; Merkin, M.; Merritt, K. W.; Miettinen, H.; Mincer, A.; Mishra, C. S.; Mokhov, N.; Mondal, N. K.; Montgomery, H. E.; Mooney, P.; da Motta, H.; Murphy, C.; Nang, F.; Narain, M.; Narasimham, V. S.; Narayanan, A.; Neal, H. A.; Negret, J. P.; Nemethy, P.; Nicola, M.; Norman, D.; Oesch, L.; Oguri, V.; Oltman, E.; Oshima, N.; Owen, D.; Padley, P.; Pang, M.; Para, A.; Park, Y. M.; Partridge, R.; Parua, N.; Paterno, M.; Perkins, J.; Peters, M.; Piegaia, R.; Piekarz, H.; Pischalnikov, Y.; Podstavkov, V. M.; Pope, B. G.; Prosper, H. B.; Protopopescu, S.; Qian, J.; Quintas, P. Z.; Raja, R.; Rajagopalan, S.; Ramirez, O.; Rasmussen, L.; Reucroft, S.; Rijssenbeek, M.; Rockwell, T.; Roe, N. A.; Rubinov, P.; Ruchti, R.; Rutherfoord, J.; Sánchez-Hernández, A.; Santoro, A.; Sawyer, L.; Schamberger, R. D.; Schellman, H.; Sculli, J.; Shabalina, E.; Shaffer, C.; Shankar, H. C.; Shivpuri, R. K.; Shupe, M.; Singh, H.; Singh, J. B.; Sirotenko, V.; Smart, W.; Smith, R. P.; Snihur, R.; Snow, G. R.; Snow, J.; Snyder, S.; Solomon, J.; Sood, P. M.; Sosebee, M.; Sotnikova, N.; Souza, M.; Spadafora, A. L.; Stephens, R. W.; Stevenson, M. L.; Stewart, D.; Stichelbaut, F.; Stoianova, D. A.; Stoker, D.; Strauss, M.; Streets, K.; Strovink, M.; Sznajder, A.; Tamburello, P.; Tarazi, J.; Tartaglia, M.; Thomas, T. L.; Thompson, J.; Trippe, T. G.; Tuts, P. M.; Varelas, N.; Varnes, E. W.; Vititoe, D.; Volkov, A. A.; Vorobiev, A. P.; Wahl, H. D.; Wang, G.; Warchol, J.; Watts, G.; Wayne, M.; Weerts, H.; White, A.; White, J. T.; Wightman, J. A.; Willis, S.; Wimpenny, S. J.; Wirjawan, J. V.; Womersley, J.; Won, E.; Wood, D. R.; Xu, H.; Yamada, R.; Yamin, P.; Yanagisawa, C.; Yang, J.; Yasuda, T.; Yepes, P.; Yoshikawa, C.; Youssef, S.; Yu, J.; Yu, Y.; Zhu, Z. H.; Zieminska, D.; Zieminski, A.; Zverev, E. G.; Zylberstejn, A.

    1998-01-01

    We have measured the dijet angular distribution in s = 1.8 TeV pp¯ collisions using the D0 detector. Order α3s QCD predictions are in good agreement with the data. At 95% confidence limit the data exclude models of quark compositeness in which the contact interaction scale is below 2 TeV.

  8. 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.

  9. Automated and angular time-synchronized directional gamma-ray scintillation sensor

    SciTech Connect

    Kronenberg, S.; Brucker, G.J.

    1998-12-31

    The authors` previous research resulted in directional sensors for gamma rays and X rays that have a 4{pi} solid angle of acceptance and, at the same time, a high angular resolution that is limited only by their ability to measure small angles. Angular resolution of {approximately}1 s of arc was achieved. These sensors are capable of operating and accurately detecting high and very low intensity radiation patterns. Such a system can also be used to image broad area sources and their scattering patterns. The principle of operation and design of directional sensors used in this study was described elsewhere; however, for convenience, a part of that text is repeated here. It was shown analytically that the angular distribution of radiation incident on the sensor is proportional to the first derivative of the scan data, that is, of the events` count rate versus orientation of the detector. The previously published results were obtained with a annual operating system. The detector assembly was set at a specific angle, and a pulse rate count was made. This was repeated at numerous other angles of orientation, a time-consuming and labor-intensive process. Recently, the authors automated this system, which is based on the detection of scintillations. The detector, which consists of a stack of plates of Lucite, plastic scintillator, and lead foils, rotates by means of a motor in front of a stationary photomultiplier tube (PMT). One revolution per second was chosen for the motor. At time zero, a trigger indicates that a revolution has started. The angle of orientation of the detector in the laboratory system is proportional to the time during one revolution. The process repeats itself a desired number of times. The trigger signal initiates a scan of a multichannel scalar (MCS). The detector assembly is allowed to rotate in the radiation field, and the MCS scans are repeated in an accumulated mode of operation until enough events are collected for the location of the

  10. Atmospheric gamma ray angle and energy distributions from 2 to 25 MeV

    NASA Technical Reports Server (NTRS)

    Ryan, J. M.; Moon, S. H.; Wilson, R. B.; Zych, A. D.; White, R. S.; Dayton, B.

    1977-01-01

    Results are given for gamma ray fluxes in six energy intervals from 2-25 MeV and five zenith angle intervals from 0-50 deg (downward moving) and five from 130-180 deg (upward moving). Observations were obtained with the University of California, Riverside double Compton scatter gamma ray telescope flown on a balloon to a 3.0 g/sq cm residual atmosphere at a geomagnetic cuttoff of 4.5 GV. It was found that the angular distribution of downward moving gamma rays is relatively flat, increasing slowly from 10-40 deg. The angular distribution of the upward moving gamma rays at 4.2 g/sq cm increases with angle from the vertical. Energy distributions of upward and downward moving gamma rays are in good agreement with the results of previous studies.

  11. Atmospheric gamma ray angle and energy distributions from 2 to 25 MeV

    NASA Technical Reports Server (NTRS)

    Ryan, J. M.; Moon, S. H.; Wilson, R. B.; Zych, A. D.; White, R. S.; Dayton, B.

    1977-01-01

    Results are given for gamma ray fluxes in six energy intervals from 2-25 MeV and five zenith angle intervals from 0-50 deg (downward moving) and five from 130-180 deg (upward moving). Observations were obtained with the University of California, Riverside double Compton scatter gamma ray telescope flown on a balloon to a 3.0 g/sq cm residual atmosphere at a geomagnetic cuttoff of 4.5 GV. It was found that the angular distribution of downward moving gamma rays is relatively flat, increasing slowly from 10-40 deg. The angular distribution of the upward moving gamma rays at 4.2 g/sq cm increases with angle from the vertical. Energy distributions of upward and downward moving gamma rays are in good agreement with the results of previous studies.

  12. Measurement of angularly dependent spectra of betatron gamma-rays from a laser plasma accelerator with quadrant-sectored range filters

    NASA Astrophysics Data System (ADS)

    Jeon, Jong Ho; Nakajima, Kazuhisa; Kim, Hyung Taek; Rhee, Yong Joo; Pathak, Vishwa Bandhu; Cho, Myung Hoon; Shin, Jung Hun; Yoo, Byung Ju; Jo, Sung Ha; Shin, Kang Woo; Hojbota, Calin; Bae, Lee Jin; Jung, Jaehyung; Cho, Min Sang; Sung, Jae Hee; Lee, Seong Ku; Cho, Byoung Ick; Choi, Il Woo; Nam, Chang Hee

    2016-07-01

    Measurement of angularly dependent spectra of betatron gamma-rays radiated by GeV electron beams from laser wakefield accelerators (LWFAs) are presented. The angle-resolved spectrum of betatron radiation was deconvolved from the position dependent data measured for a single laser shot with a broadband gamma-ray spectrometer comprising four-quadrant sectored range filters and an unfolding algorithm, based on the Monte Carlo code GEANT4. The unfolded gamma-ray spectra in the photon energy range of 0.1-10 MeV revealed an approximately isotropic angular dependence of the peak photon energy and photon energy-integrated fluence. As expected by the analysis of betatron radiation from LWFAs, the results indicate that unpolarized gamma-rays are emitted by electrons undergoing betatron motion in isotropically distributed orbit planes.

  13. Measurement of angularly dependent spectra of betatron gamma-rays from a laser plasma accelerator with quadrant-sectored range filters

    SciTech Connect

    Jeon, Jong Ho Nakajima, Kazuhisa Rhee, Yong Joo; Pathak, Vishwa Bandhu; Cho, Myung Hoon; Shin, Jung Hun; Yoo, Byung Ju; Jo, Sung Ha; Shin, Kang Woo; Kim, Hyung Taek; Sung, Jae Hee; Lee, Seong Ku; Choi, Il Woo; Hojbota, Calin; Bae, Lee Jin; Jung, Jaehyung; Cho, Min Sang; Cho, Byoung Ick; Nam, Chang Hee

    2016-07-15

    Measurement of angularly dependent spectra of betatron gamma-rays radiated by GeV electron beams from laser wakefield accelerators (LWFAs) are presented. The angle-resolved spectrum of betatron radiation was deconvolved from the position dependent data measured for a single laser shot with a broadband gamma-ray spectrometer comprising four-quadrant sectored range filters and an unfolding algorithm, based on the Monte Carlo code GEANT4. The unfolded gamma-ray spectra in the photon energy range of 0.1–10 MeV revealed an approximately isotropic angular dependence of the peak photon energy and photon energy-integrated fluence. As expected by the analysis of betatron radiation from LWFAs, the results indicate that unpolarized gamma-rays are emitted by electrons undergoing betatron motion in isotropically distributed orbit planes.

  14. Angular distribution and atomic effects in condensed phase photoelectron spectroscopy

    SciTech Connect

    Davis, R.F.

    1981-11-01

    A general concept of condensed phase photoelectron spectroscopy is that angular distribution and atomic effects in the photoemission intensity are determined by different mechanisms, the former being determined largely by ordering phenomena such as crystal momentum conservation and photoelectron diffraction while the latter are manifested in the total (angle-integrated) cross section. In this work, the physics of the photoemission process is investigated in several very different experiments to elucidate the mechanisms of, and correlation between, atomic and angular distribution effects. Theoretical models are discussed and the connection betweeen the two effects is clearly established. The remainder of this thesis, which describes experiments utilizing both angle-resolved and angle-integrated photoemission in conjunction with synchrotron radiation in the energy range 6 eV less than or equal to h ..nu.. less than or equal to 360 eV and laboratory sources, is divided into three parts.

  15. Angular Distributions of η Meson Production in pp Reactions

    NASA Astrophysics Data System (ADS)

    Fröhlich, I.; Balestra, F.; Bedfer, Y.; Bertini, R.; Bland, L. C.; Brenschede, A.; Brochard, F.; Bussa, M. P.; Choi, Seonho; Colantoni, M. L.; Dressler, R.; Dzemidzic, M.; Faivre, J.-Cl.; Ferrero, A.; Ferrero, L.; Foryciarz, J.; Frolov, V.; Garfagnini, R.; Grasso, A.; Heinz, S.; Jacobs, W. W.; Kühn, W.; Maggiora, A.; Maggiora, M.; Manara, A.; Panzieri, D.; Pfaff, H.-W.; Piragino, G.; Popov, A.; Ritman, J.; Salabura, P.; Tchalyshev, V.; Tosello, F.; Vigdor, S. E.; Zosi, G.

    With the DISTO spectrometer, exclusive η production in pp collisions have been measured at kinetic energies of Tbeam=2.15, 2.50 and 2.85 GeV, respectively, via the π+π-π0 decay channel. The resulting angular distributions of the η are important for the interpretation of dilepton spectra obtained in elementary as well as heavy ion reactions.

  16. 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.

  17. 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.

  18. 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.

  19. Accessing the quark orbital angular momentum with Wigner distributions

    SciTech Connect

    Lorce, Cedric

    2013-04-15

    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.

  20. 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.

  1. 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.

  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. 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.

  4. 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

  5. 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…

  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. Photoelectron angular distributions from liquid water: effects of electron scattering.

    PubMed

    Thürmer, Stephan; Seidel, Robert; Faubel, Manfred; Eberhardt, Wolfgang; Hemminger, John C; Bradforth, Stephen E; Winter, Bernd

    2013-10-25

    Photoelectron angular distributions (PADs) from the liquid-water surface and from bulk liquid water are reported for water oxygen-1s ionization. Although less so than for the gas phase, the measured PADs from the liquid are remarkably anisotropic, even at electron kinetic energies lower than 100 eV, when elastic scattering cross sections for the outgoing electrons with other water molecules are large. The PADs reveal that theoretical estimates of the inelastic mean free path are likely too long at low kinetic energies, and hence the electron probing depth in water, near threshold ionization, appears to be considerably smaller than so far assumed.

  8. 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.

  9. Angular power spectrum of the diffuse gamma-ray emission as measured by the Fermi Large Area Telescope and constraints on its dark matter interpretation

    SciTech Connect

    Fornasa, Mattia; Cuoco, Alessandro; Zavala, Jesús; Gaskins, Jennifer M.; Sánchez-Conde, Miguel A.; Gomez-Vargas, German; Komatsu, Eiichiro; Linden, Tim; Prada, Francisco; Zandanel, Fabio; Morselli, Aldo

    2016-12-09

    The isotropic gamma-ray background arises from the contribution of unresolved sources, including members of confirmed source classes and proposed gamma-ray emitters such as the radiation induced by dark matter annihilation and decay. Clues about the properties of the contributing sources are imprinted in the anisotropy characteristics of the gamma-ray background. We use 81 months of Pass 7 Reprocessed data from the Fermi Large Area Telescope to perform a measurement of the anisotropy angular power spectrum of the gamma-ray background. Here, we analyze energies between 0.5 and 500 GeV, extending the range considered in the previous measurement based on 22 months of data. We also compute, for the first time, the cross-correlation angular power spectrum between different energy bins. The derived angular spectra are compatible with being Poissonian, i.e. constant in multipole. Furthermore, the energy dependence of the anisotropy suggests that the signal is due to two populations of sources, contributing, respectively, below and above ~ 2 GeV . Finally, using data from state-of-the-art numerical simulations to model the dark matter distribution, we constrain the contribution from dark matter annihilation and decay in Galactic and extra-Galactic structures to the measured anisotropy. These constraints are competitive with those that can be derived from the average intensity of the isotropic gamma-ray background.

  10. Angular power spectrum of the diffuse gamma-ray emission as measured by the Fermi Large Area Telescope and constraints on its dark matter interpretation

    DOE PAGES

    Fornasa, Mattia; Cuoco, Alessandro; Zavala, Jesús; ...

    2016-12-09

    The isotropic gamma-ray background arises from the contribution of unresolved sources, including members of confirmed source classes and proposed gamma-ray emitters such as the radiation induced by dark matter annihilation and decay. Clues about the properties of the contributing sources are imprinted in the anisotropy characteristics of the gamma-ray background. We use 81 months of Pass 7 Reprocessed data from the Fermi Large Area Telescope to perform a measurement of the anisotropy angular power spectrum of the gamma-ray background. Here, we analyze energies between 0.5 and 500 GeV, extending the range considered in the previous measurement based on 22 monthsmore » of data. We also compute, for the first time, the cross-correlation angular power spectrum between different energy bins. The derived angular spectra are compatible with being Poissonian, i.e. constant in multipole. Furthermore, the energy dependence of the anisotropy suggests that the signal is due to two populations of sources, contributing, respectively, below and above ~ 2 GeV . Finally, using data from state-of-the-art numerical simulations to model the dark matter distribution, we constrain the contribution from dark matter annihilation and decay in Galactic and extra-Galactic structures to the measured anisotropy. These constraints are competitive with those that can be derived from the average intensity of the isotropic gamma-ray background.« less

  11. Angular power spectrum of the diffuse gamma-ray emission as measured by the Fermi Large Area Telescope and constraints on its dark matter interpretation

    NASA Astrophysics Data System (ADS)

    Fornasa, Mattia; Cuoco, Alessandro; Zavala, Jesús; Gaskins, Jennifer M.; Sánchez-Conde, Miguel A.; Gomez-Vargas, German; Komatsu, Eiichiro; Linden, Tim; Prada, Francisco; Zandanel, Fabio; Morselli, Aldo

    2016-12-01

    The isotropic gamma-ray background arises from the contribution of unresolved sources, including members of confirmed source classes and proposed gamma-ray emitters such as the radiation induced by dark matter annihilation and decay. Clues about the properties of the contributing sources are imprinted in the anisotropy characteristics of the gamma-ray background. We use 81 months of Pass 7 Reprocessed data from the Fermi Large Area Telescope to perform a measurement of the anisotropy angular power spectrum of the gamma-ray background. We analyze energies between 0.5 and 500 GeV, extending the range considered in the previous measurement based on 22 months of data. We also compute, for the first time, the cross-correlation angular power spectrum between different energy bins. We find that the derived angular spectra are compatible with being Poissonian, i.e. constant in multipole. Moreover, the energy dependence of the anisotropy suggests that the signal is due to two populations of sources, contributing, respectively, below and above ˜2 GeV . Finally, using data from state-of-the-art numerical simulations to model the dark matter distribution, we constrain the contribution from dark matter annihilation and decay in Galactic and extra-Galactic structures to the measured anisotropy. These constraints are competitive with those that can be derived from the average intensity of the isotropic gamma-ray background.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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 ) .

  19. Photoelectron angular distributions from two-photon ionizations of atoms

    NASA Astrophysics Data System (ADS)

    Haber, Louis Hamilton

    Photoelectron angular distributions provide detailed information about interferences between different quantum pathways of photoionization. Measurements of photoelectron energies and angular distributions from two-color two-photon ionizations of atoms using ultrashort pulses of extreme ultraviolet and optical light are performed using a novel, homebuilt experimental instrument. The setup is composed of an amplified femtosecond laser system, a high-order harmonic generation source, and an interaction region with photoelectron velocity map imaging The experimental temporal resolution is determined to be approximately 100 fs. Two different types of two-photon ionizations are investigated. Photoelectron angular distributions from resonant two-photon ionizations of helium are measured using the 15th high-order harmonic to excite from the ground state to either the 1s3p 1P1 state at 23.1 eV or to the 1s4p 1 P1 state at 23.7 eV and either 800, 400, or 267 nm to ionize. The anisotropy parameters allow for the determination of the energy-dependent ratios of radial dipole matrix elements and the phase shift differences between the S and D partial waves. Using available total cross section measurements, the absolute partial cross sections of the 1s3p1P 1 state are obtained, providing the complete information on photoionization. The experimental results are in excellent agreement with theoretical predictions using the one-electron model. Additional experiments are aimed at studying atomic free-free transitions. Two-color two-photon above threshold ionizations of helium and argon are investigated using selected high-order harmonics and perturbative infrared dressing fields. The measured anisotropy parameters and cross section ratios of the positive and negative above threshold ionization sidebands are compared to theoretical predictions using second-order perturbation theory and the soft-photon approximation. In general, deviations between the experimental results and the

  20. 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.

  1. 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.

  2. Angular Distribution of light emission in ELVES events

    NASA Astrophysics Data System (ADS)

    Mussa, Roberto

    2017-04-01

    The Pierre Auger Observatory, located in Malargüe (Argentina), is the largest facility (3000 kmq ) for the study of Ultra High Energy Cosmic Rays (E>0.3 EeV). The four sites of the Fluorescence Detector (FD) are continuously observing the night sky with moon fraction below 50% (13% duty cycle) with 100 ns time resolution and a space resolution below one degree. Since 2013, the Observatory has implemented a dedicated trigger for the study of ELVES events, produced by lightning activity in Northern Argentina during summer months. A network of ancillary devices (lidars, cloud cameras, weather stations, lightning sensors, E-field mills) complements the FD data to correct for the variation of atmospheric optical properties. This paper will report about the angular distribution of the light emission around the vertical above the lightning source and compare with existing models.

  3. 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.

  4. 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.

  5. 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.

  6. The Angular Power Spectrum of BATSE 3B Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Tegmark, Max; Hartmann, Dieter H.; Briggs, Michael S.; Meegan, Charles A.

    1996-01-01

    We compute the angular power spectrum C(sub l) from the BATSE 3B catalog of 1122 gamma-ray bursts and find no evidence for clustering on any scale. These constraints bridge the entire range from small scales (which probe source clustering and burst repetition) to the largest scales (which constrain possible anisotropics from the Galactic halo or from nearby cosmological large-scale structures). We develop an analysis technique that takes the angular position errors into account. For specific clustering or repetition models, strong upper limits can be obtained down to scales l approx. equal to 30, corresponding to a couple of degrees on the sky. The minimum-variance burst weighting that we employ is visualized graphically as an all-sky map in which each burst is smeared out by an amount corresponding to its position uncertainty. We also present separate bandpass-filtered sky maps for the quadrupole term and for the multipole ranges l = 3-10 and l = 11-30, so that the fluctuations on different angular scales can be inspected separately for visual features such as localized 'hot spots' or structures aligned with the Galactic plane. These filtered maps reveal no apparent deviations from isotropy.

  7. 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.

  8. Modelling complex geological angular data with the Projected Normal distribution and mixtures of von Mises distributions

    NASA Astrophysics Data System (ADS)

    Lark, R. M.; Clifford, D.; Waters, C. N.

    2013-12-01

    Angular data are commonly encountered in the earth sciences and statistical descriptions and inferences about such data are necessary in structural geology. In this paper we compare two statistical distributions appropriate for complex angular data sets: the mixture of von Mises and the projected normal distribution. We show how the number of components in a mixture of von Mises distribution may be chosen, and how one may chose between the projected normal distribution and mixture of von Mises for a particular data set. We illustrate these methods with some structural geological data, showing how the fitted models can complement geological interpretation and permit statistical inference. One of our data sets suggests a special case of the projected normal distribution which we discuss briefly.

  9. 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.

  10. 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.

  11. 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.

  12. Correction of measured Gamma-Knife output factors for angular dependence of diode detectors and PinPoint ionization chamber.

    PubMed

    Hršak, Hrvoje; Majer, Marija; Grego, Timor; Bibić, Juraj; Heinrich, Zdravko

    2014-12-01

    Dosimetry for Gamma-Knife requires detectors with high spatial resolution and minimal angular dependence of response. Angular dependence and end effect time for p-type silicon detectors (PTW Diode P and Diode E) and PTW PinPoint ionization chamber were measured with Gamma-Knife beams. Weighted angular dependence correction factors were calculated for each detector. The Gamma-Knife output factors were corrected for angular dependence and end effect time. For Gamma-Knife beams angle range of 84°-54°. Diode P shows considerable angular dependence of 9% and 8% for the 18 mm and 14, 8, 4 mm collimator, respectively. For Diode E this dependence is about 4% for all collimators. PinPoint ionization chamber shows angular dependence of less than 3% for 18, 14 and 8 mm helmet and 10% for 4 mm collimator due to volumetric averaging effect in a small photon beam. Corrected output factors for 14 mm helmet are in very good agreement (within ±0.3%) with published data and values recommended by vendor (Elekta AB, Stockholm, Sweden). For the 8 mm collimator diodes are still in good agreement with recommended values (within ±0.6%), while PinPoint gives 3% less value. For the 4 mm helmet Diodes P and E show over-response of 2.8% and 1.8%, respectively. For PinPoint chamber output factor of 4 mm collimator is 25% lower than Elekta value which is generally not consequence of angular dependence, but of volumetric averaging effect and lack of lateral electronic equilibrium. Diodes P and E represent good choice for Gamma-Knife dosimetry. Copyright © 2014 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  13. Distribution of Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Diaz Rodriguez, Mariangelly; Smith, M.; Tešic, G.

    2014-01-01

    Gamma-Ray Bursts (GRBs) are known to be bright, irregular flashes of gamma rays that typically last just a few seconds, believed to be caused by stellar collapse or the merger of a pair of compact objects. Through previous work, it has been found that GRBs are distributed roughly uniformly over the entire sky, rather than being confined to the relatively narrow band of the Milky Way. Using the Python programming language, we generated a model of GRBs over cosmological distances, based on current empirical GRB distributions. The grbsim python module uses the acceptance-rejection Monte Carlo method to simulate the luminosity and redshift of a large population of GRBs, including cosmological effects such as dark energy and dark matter terms that modify the large-scale structure of space-time. The results of running grbsim are demonstrated to match the distribution of GRBs observed by the Burst Alert Telescope on NASA’s Swift satellite. The grbsim module will subsequently be used to simulate gamma ray and neutrino events for the Astrophysical Multimessenger Observatory Network.

  14. 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.

  15. 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.

  16. High resolution gamma-ray spectroscopy and the fascinating angular momentum realm of the atomic nucleus

    NASA Astrophysics Data System (ADS)

    Riley, M. A.; Simpson, J.; Paul, E. S.

    2016-12-01

    In 1974 Aage Bohr and Ben Mottelson predicted the different ‘phases’ that may be expected in deformed nuclei as a function of increasing angular momentum and excitation energy all the way up to the fission limit. While admitting their picture was highly conjectural they confidently stated ‘...with the ingenious experimental approaches that are being developed, we may look forward with excitement to the detailed spectroscopic studies that will illuminate the behaviour of the spinning quantised nucleus’. High resolution gamma-ray spectroscopy has indeed been a major tool in studying the structure of atomic nuclei and has witnessed numerous significant advances over the last four decades. This article will select highlights from investigations at the Niels Bohr Institute, Denmark, and Daresbury Laboratory, UK, in the late 1970s and early 1980s, some of which have continued at other national laboratories in Europe and the USA to the present day. These studies illustrate the remarkable diversity of phenomena and symmetries exhibited by nuclei in the angular momentum-excitation energy plane that continue to surprise and fascinate scientists.

  17. 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.

  18. Statistical model with a standard Gamma distribution.

    PubMed

    Patriarca, Marco; Chakraborti, Anirban; Kaski, Kimmo

    2004-01-01

    We study a statistical model consisting of N basic units which interact with each other by exchanging a physical entity, according to a given microscopic random law, depending on a parameter lambda. We focus on the equilibrium or stationary distribution of the entity exchanged and verify through numerical fitting of the simulation data that the final form of the equilibrium distribution is that of a standard Gamma distribution. The model can be interpreted as a simple closed economy in which economic agents trade money and a saving criterion is fixed by the saving propensity lambda. Alternatively, from the nature of the equilibrium distribution, we show that the model can also be interpreted as a perfect gas at an effective temperature T(lambda), where particles exchange energy in a space with an effective dimension D(lambda).

  19. Statistical model with a standard Gamma distribution

    NASA Astrophysics Data System (ADS)

    Chakraborti, Anirban; Patriarca, Marco

    2005-03-01

    We study a statistical model consisting of N basic units which interact with each other by exchanging a physical entity, according to a given microscopic random law, depending on a parameter λ. We focus on the equilibrium or stationary distribution of the entity exchanged and verify through numerical fitting of the simulation data that the final form of the equilibrium distribution is that of a standard Gamma distribution. The model can be interpreted as a simple closed economy in which economic agents trade money and a saving criterion is fixed by the saving propensity λ. Alternatively, from the nature of the equilibrium distribution, we show that the model can also be interpreted as a perfect gas at an effective temperature T (λ), where particles exchange energy in a space with an effective dimension D (λ).

  20. Effects of W and Mo crystalline texture on the angular distribution of sputtered atoms

    NASA Astrophysics Data System (ADS)

    Rogov, A. V.; Martynenko, Yu. V.; Belova, N. E.; Shulga, V. I.

    2011-11-01

    The effects of W and Mo surface crystalline texture on the angular distribution of sputtered atoms were investigated experimentally and by computer simulation. A small-sized planar DC magnetron was used to sputter the target by 200-300 eV Ar+ ions. The crystalline texture was formed under rolling of metal foils and during the preparation of metal bars and was controlled by X-ray diffraction analysis. For W and Mo foils, a strong anisotropy of the angular distribution was found. The character of angular distribution was different in the planes oriented perpendicularly and in parallel to the direction of rolling. In the first case, the angular distribution was peaked at the polar angle θ=0, while in the second case, the angular distribution, in addition to a maximum at θ=0, revealed a pronounced maximum at θ≈ 57° and ≈60° for Mo and W, respectively. For bars, no azimuthal anisotropy was observed, but the angular distribution was peaked at θ=37° (Mo) and θ=45° (W). This is in contrast to the case of non-textured Mo and W polycrystals, for which the angular distribution had a maximum at θ=0. Computer simulation technique in combination with the results of X-ray analysis was used to clarify the above experimental findings. It was demonstrated that the angular distribution of sputtered atoms can be successfully used for the determination of the crystalline texture of metals.

  1. The Evolution of the Angular Momentum Distribution during Star Formation.

    PubMed

    Tomisaka

    2000-01-01

    If the angular momentum of the molecular cloud core were conserved during the star formation process, a newborn star would rotate much faster than its fission speed. This constitutes the angular momentum problem of newborn stars. In this Letter, the angular momentum transfer in the contraction of a rotating magnetized cloud is studied with axisymmetric MHD simulations. Because of the large dynamic range covered by the nested-grid method, the structure of the cloud in the range from 10 AU to 0.1 pc is explored. First, the cloud experiences a runaway collapse, and a disk forms perpendicularly to the magnetic field, in which the central density increases greatly in a finite timescale. In this phase, the specific angular momentum j of the disk decreases to about one-third of the initial cloud. After the central density of the disk exceeds approximately 1010 cm-3, the infall on to the central object develops. In this accretion stage, the rotation motion and thus the toroidal magnetic field drive the outflow. The angular momentum of the central object is transferred efficiently by the outflow as well as by the effect of the magnetic stress. In 7000 yr from the core formation, the specific angular momentum of the central 0.17 M middle dot in circle decreases a factor of 10-4 from the initial value (i.e., from 1020 to 1016 cm2 s-1).

  2. Spectrum, angular distribution and polarization of auroral hard X-rays

    NASA Astrophysics Data System (ADS)

    Khosa, P. N.; Rausaria, R. R.; Moza, K. L.

    1984-01-01

    Elastic and inelastic scattering cross section angular variations are computed, and used as the basis of Monte Carlo calculations of electron energy evolution and angular distributions at different heights in the ionosphere. Monoenergic, power law and exponential electron spectra with isotropic and monodirectional incidence, starting at 300 km altitude, have been used to obtain the angular and energy distributions at various height intervals. It is found that isotropic distribution incident at the top of the ionosphere becomes anisotropic, due to collisions at lower heights. The Sauter (1934) bremsstrahlung cross section, and the calculated electron flux, are used to compute the spectrum, angular distribution, and polarization of bremsstrahlung X-rays at different heights. Angular distribution and polarization studies can yield data about the nature of precipitating electron flux, and hence about the acceleration mechanism operating during electron precipitation.

  3. Torque distribution algorithm for effective use of reaction wheel torques and angular momentums

    NASA Astrophysics Data System (ADS)

    Sugita, Mikihiro

    2017-10-01

    In attitude control of spacecraft using more than three reaction wheels, the distribution of the attitude control torque to the wheels is not unique because of the redundancy. There are several wheel torque distribution algorithms which optimize the wheel torques or other factors. In particular, the optimal torque distribution algorithm is acknowledged as algorithm which minimizes the maximum wheel torque. This algorithm is advantageous to make maximum use of the wheel torques, because each wheel torque must be lower than the wheel torque capability and torque is the primary driver in many cases. However, as a result of minimizing the maximum wheel torque, the distribution of the wheel angular momentums is not calculated by a similar formula for the wheel torques distribution. In other words, the wheel angular momentums cannot be derived from the current attitude angular momentum. When certain wheel reaches maximum angular momentum earlier than the other wheels, this prohibits maximum use of the other wheels' capability. Therefore, minimizing the maximum wheel torque is not always effective when other constraint such as angular momentum matters. Recently, it has become more important that both wheel torques and angular momentums are used more effectively in order to improve the performance of the spacecraft agility, such as the high angular acceleration and rate, by using minimum spacecraft resources (i.e. minimum number of wheels which satisfies certain agility requirements). In this paper, shown is the wheel torque distribution algorithm which is effective in terms of both the wheel torques and angular momentums as much as possible. In the proposed algorithm, the wheel torques/angular momentums distributed from the current attitude torque/angular momentum can be optimal for particular direction like the spacecraft X/Y/Z axis. In addition, it is shown by numerical simulation that the proposed algorithm improves the usage of attitude control angular momentum by up

  4. Angular distributions of the polarized photons and electron in the decays of the state of charmonium

    NASA Astrophysics Data System (ADS)

    Mok, Alex W. K.; Wong, Cheuk-Ping; Sit, Wai-Yu

    2014-02-01

    We calculate the combined angular-distribution functions of the polarized photons ( and ) and electron () produced in the cascade process , when the colliding and are unpolarized. Our results are independent of any dynamical models and are expressed in terms of the spherical harmonics whose coefficients are functions of the angular-momentum helicity amplitudes of the individual processes. Once the joint angular distribution of (, ) and that of (, ) with the polarization of either one of the two particles are measured, our results will enable one to determine the relative magnitudes as well as the relative phases of all the angular-momentum helicity amplitudes in the radiative decay processes and.

  5. 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.

  6. Constraints on galactic distributions of gamma-ray burst sources from BATSE observations

    NASA Technical Reports Server (NTRS)

    Hakkila, Jon; Meegan, Charles A.; Pendleton, Geoffrey N.; Fishman, Gerald J.; Wilson, Robert B.; Paciesas, William S.; Brock, Martin N.; Horack, John M.

    1994-01-01

    The paradigm that gamma-ray bursts originate from Galactic sources is studied in detail using the angular and intensity distributions observed by the Burst and Transient Source Experiment (BATSE) on NASA's Compton Gamma Ray Observatory (CGRO). Monte Carlo models of gamma-ray burst spatial distributions and luminosity functions are used to simulate bursts, which are then folded through mathematical models of BATSE selection effects. The observed and computed angular intensity distributions are analyzed using modifications of standard statistical homogeneity and isotropy studies. Analysis of the BATSE angular and intensity distributions greatly constrains the origins and luminosities of burst sources. In particular, it appears that no single population of sources confined to a Galactic disk, halo, or localized spiral arm satisfactorily explains BATSE observations and that effects of the burst luminosity function are secondary when considering such models. One family of models that still satisfies BATSE observations comprises sources located in an extended spherical Galactic corona. Coronal models are limited to small ranges of burst luminosity and core radius, and the allowed parameter space for such models shrinks with each new burst BATSE observes. Multiple-population models of bursts are found to work only if (1) the primary population accounts for the general isotropy and inhomogeneity seen in the BATSE observations and (2) secondary populations either have characteristics similar to the primary population or contain numbers that are small relative to the primary population.

  7. 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.

  8. 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.

  9. Workability of a gamma titanium aluminide alloy during equal channel angular extrusion

    SciTech Connect

    Semiatin, S.L.; Segal, V.M.; Goforth, R.E.; Hartwig, T.; Goetz, R.L.

    1995-08-15

    Canned performs of the titanium aluminide Ti-45.5Al-2Cr-2Nb were hot worked via equal channel angular extrusion (ECAE). The following conclusions are drawn regarding the effects of extrusion temperature and microstructural condition on workability controlled by shear localization: (1) The tendency for nonuniform deformation during ECAE increases rapidly as the preheat temperature decrease. The trend is most pronounced for material in a cast + HIP`ed condition as compared to that in a wrought condition. The nonuniform flow may develop into well defined shear bands and shear cracks in the cast + HIP`ed titanium aluminide. (2) The occurrence of shear bands and the severity of flow localization within the shear bands can be correlated at least on a first-order basis to material flow behavior as quantified by the alpha parameter, the ratio of the normalized flow softening rate to the strain rate sensitivity exponent. (3) Multi-pass ECAE sequences to breakdown and refine the structure of near-gamma titanium aluminide ingot can be designed through proper consideration of the effect of temperature and material condition on flow localization tendencies. However, can design to minimize die chilling may play an important role in industrial implementation of the ECAE process for this alloy system.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Atomic jump frequencies in intermetallic compounds studied using perturbed angular correlation of gamma rays

    NASA Astrophysics Data System (ADS)

    Newhouse, Randal Leslie

    Atomic jump frequencies were determined in a variety of intermetallic compounds through analysis of nuclear relaxation of spectra measured using the nuclear hyperfine technique, perturbed angular correlation (PAC) of gamma rays. Observed at higher temperatures, this relaxation is attributed to fluctuations in the orientation or magnitude of electric field gradients (EFG) at nuclei of 111In/Cd probe atoms as the atoms make diffusive jumps. Jump frequencies were obtained by fitting dynamically relaxed PAC spectra using either an empirical relaxation function or using ab initio relaxation models created using the program PolyPacFit. Jump frequency activation enthalpies were determined from measurements over a range of temperatures. Diffusion was studied in the following systems: 1) Pseudo-binary alloys having the L12 crystal structure such as In3(La1-xPrx). The goal was to see how jump frequencies were affected by random disorder. 2) The family of layered phases, LanCoIn3n+2 ( n=0,1,2,3…∞). The goal was to see how jump frequencies varied with the spacing of Co layers, which were found to block diffusion. 3) Phases having the FeGa3 structure. The goal was to analyze dynamical relaxation for probe atoms having multiple inequivalent jump vectors. 4) Phases having the tetragonal Al4Ba structure. The goal was to search for effects in the PAC spectra caused by fluctuations in magnitudes of EFGs without fluctuations in orientations. Ab initio relaxation models were developed to simulate and fit dynamical relaxation for PAC spectra of FeGa3, and several phases with the Al4Ba structure in order to determine underlying microscopic jump frequencies. In the course of this work, site preferences also were observed for 111In/Cd probe atoms in several FeGa 3 and Al4Ba phases.

  19. 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.

  20. 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.

  1. A method to describe inelastic gamma field distribution in neutron gamma density logging.

    PubMed

    Zhang, Feng; Zhang, Quanying; Liu, Juntao; Wang, Xinguang; Wu, He; Jia, Wenbao; Ti, Yongzhou; Qiu, Fei; Zhang, Xiaoyang

    2017-08-21

    Pulsed neutron gamma density logging (NGD) is of great significance for radioprotection and density measurement in LWD, however, the current methods have difficulty in quantitative calculation and single factor analysis for the inelastic gamma field distribution. In order to clarify the NGD mechanism, a new method is developed to describe the inelastic gamma field distribution. Based on the fast-neutron scattering and gamma attenuation, the inelastic gamma field distribution is characterized by the inelastic scattering cross section, fast-neutron scattering free path, formation density and other parameters. And the contribution of formation parameters on the field distribution is quantitatively analyzed. The results shows the contribution of density attenuation is opposite to that of inelastic scattering cross section and fast-neutron scattering free path. And as the detector-spacing increases, the density attenuation gradually plays a dominant role in the gamma field distribution, which means large detector-spacing is more favorable for the density measurement. Besides, the relationship of density sensitivity and detector spacing was studied according to this gamma field distribution, therefore, the spacing of near and far gamma ray detector is determined. The research provides theoretical guidance for the tool parameter design and density determination of pulsed neutron gamma density logging technique. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. 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.

  3. Bivariate gamma distributions for image registration and change detection.

    PubMed

    Chatelain, Florent; Tourneret, Jean-Yves; Inglada, Jordi; Ferrari, André

    2007-07-01

    This paper evaluates the potential interest of using bivariate gamma distributions for image registration and change detection. The first part of this paper studies estimators for the parameters of bivariate gamma distributions based on the maximum likelihood principle and the method of moments. The performance of both methods are compared in terms of estimated mean square errors and theoretical asymptotic variances. The mutual information is a classical similarity measure which can be used for image registration or change detection. The second part of the paper studies some properties of the mutual information for bivariate Gamma distributions. Image registration and change detection techniques based on bivariate gamma distributions are finally investigated. Simulation results conducted on synthetic and real data are very encouraging. Bivariate gamma distributions are good candidates allowing us to develop new image registration algorithms and new change detectors.

  4. 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.

  5. 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.

  6. Angular distributions of molecular Auger electrons: The case of C 1s Auger emission in CO

    SciTech Connect

    Semenov, S. K.; Kuznetsov, V. V.; Cherepkov, N. A.; Bolognesi, P.; Feyer, V.; Lahmam-Bennani, A.; Casagrande, M. E. Staicu; Avaldi, L.

    2007-03-15

    The results of a study of the Auger-electron-photoelectron angular correlations in the case of the C 1s ionization of the CO molecule are presented and compared with theoretical calculations in the Hartree-Fock approximation based on the two-step model. The measurements have been performed at two photon energies, 305 and 318 eV, respectively, and at three angles of photoelectron emission relative to the light polarization vector: namely, 0 degree sign , 30 degree sign , and 60 degree sign . A general agreement is found between theory and experiment for the coincidence angular distributions and the relative magnitudes of the Auger-electron-photoelectron angular correlations. However, both experiment and theory show that the Auger-electron-photoelectron angular correlations are not sufficiently sensitive to the details of the Auger-electron wave function to allow a 'complete' Auger experiment in molecules. On the other hand, our calculations demonstrate that the Auger-electron angular distribution measured in the molecular frame is very sensitive to the individual contributions of different partial waves of the Auger electron. Therefore we conclude that the complete experiment for the Auger decay in molecules can be realized only measuring the Auger-electron angular distributions in the molecular frame.

  7. 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.

  8. Calculation of reflectance distribution using angular spectrum convolution in mesh-based computer generated hologram.

    PubMed

    Yeom, Han-Ju; Park, Jae-Hyeung

    2016-08-22

    We propose a method to obtain a computer-generated hologram that renders reflectance distributions of individual mesh surfaces of three-dimensional objects. Unlike previous methods which find phase distribution inside each mesh, the proposed method performs convolution of angular spectrum of the mesh to obtain desired reflectance distribution. Manipulation in the angular spectrum domain enables its application to fully-analytic mesh based computer generated hologram, removing the necessity for resampling of the spatial frequency grid. It is also computationally inexpensive as the convolution can be performed efficiently using Fourier transform. In this paper, we present principle, error analysis, simulation, and experimental verification results of the proposed method.

  9. 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.

  10. Angular distribution of atoms ejected by laser ablation of different metals

    SciTech Connect

    Konomi, I.; Motohiro, T.; Asaoka, T.

    2009-07-01

    Angular distributions of 13 different metals ejected by laser ablation using fourth harmonics (wavelength=266 nm) of neodymium doped yttrium aluminum garnet laser and a fluence close to near-threshold value (2.3 J/cm{sup 2}) have been investigated with a high angular resolution. The angular distribution which is characterized by the exponent n of cos{sup n} theta distribution showed very broad range of values between 3 and 24 for different metals. A simple relation that the exponent n is proportional to the square root of particle atomic weight as reported previously has not been observed. Instead, a general trend has been found that the metals with higher sublimation energy such as Ta and Zr show narrower angular distribution than those with lower sublimation energy such as Sn and In. While the sublimation energy of metals has a great influence on the angular distribution of ejected atoms, a simple consideration suggests that their thermal conductivity and specific heat have little effect on it.

  11. Statistical measurement of the gamma-ray source-count distribution as a function of energy

    SciTech Connect

    Zechlin, Hannes-S.; Cuoco, Alessandro; Donato, Fiorenza; Fornengo, Nicolao; Regis, Marco

    2016-07-29

    Statistical properties of photon count maps have recently been proven as a new tool to study the composition of the gamma-ray sky with high precision. Here, we employ the 1-point probability distribution function of six years of Fermi-LAT data to measure the source-count distribution dN/dS and the diffuse components of the high-latitude gamma-ray sky as a function of energy. To that aim, we analyze the gamma-ray emission in five adjacent energy bands between 1 and 171 GeV. It is demonstrated that the source-count distribution as a function of flux is compatible with a broken power law up to energies of ~50 GeV. Furthermore, the index below the break is between 1.95 and 2.0. For higher energies, a simple power-law fits the data, with an index of ${2.2}_{-0.3}^{+0.7}$ in the energy band between 50 and 171 GeV. Upper limits on further possible breaks as well as the angular power of unresolved sources are derived. We find that point-source populations probed by this method can explain ${83}_{-13}^{+7}$% (${81}_{-19}^{+52}$%) of the extragalactic gamma-ray background between 1.04 and 1.99 GeV (50 and 171 GeV). Our method has excellent capabilities for constraining the gamma-ray luminosity function and the spectra of unresolved blazars.

  12. Statistical Measurement of the Gamma-Ray Source-count Distribution as a Function of Energy

    NASA Astrophysics Data System (ADS)

    Zechlin, Hannes-S.; Cuoco, Alessandro; Donato, Fiorenza; Fornengo, Nicolao; Regis, Marco

    2016-08-01

    Statistical properties of photon count maps have recently been proven as a new tool to study the composition of the gamma-ray sky with high precision. We employ the 1-point probability distribution function of six years of Fermi-LAT data to measure the source-count distribution dN/dS and the diffuse components of the high-latitude gamma-ray sky as a function of energy. To that aim, we analyze the gamma-ray emission in five adjacent energy bands between 1 and 171 GeV. It is demonstrated that the source-count distribution as a function of flux is compatible with a broken power law up to energies of ˜50 GeV. The index below the break is between 1.95 and 2.0. For higher energies, a simple power-law fits the data, with an index of {2.2}-0.3+0.7 in the energy band between 50 and 171 GeV. Upper limits on further possible breaks as well as the angular power of unresolved sources are derived. We find that point-source populations probed by this method can explain {83}-13+7% ({81}-19+52%) of the extragalactic gamma-ray background between 1.04 and 1.99 GeV (50 and 171 GeV). The method has excellent capabilities for constraining the gamma-ray luminosity function and the spectra of unresolved blazars.

  13. Projectile-breakup-induced fission-fragment angular distributions in the 6Li+232Th reaction

    NASA Astrophysics Data System (ADS)

    Pal, A.; Santra, S.; Chattopadhyay, D.; Kundu, A.; Ramachandran, K.; Tripathi, R.; Roy, B. J.; Nag, T. N.; Sawant, Y.; Sarkar, D.; Nayak, B. K.; Saxena, A.; Kailas, S.

    2017-08-01

    Background: Experimental anisotropy in fission-fragment (FF) angular distribution in reactions involving weakly bound stable projectiles with actinide targets are enhanced compared to statistical saddle-point model (SSPM) predictions. Contributions from breakup- or transfer-induced fission to total fission are cited as possible reasons for such enhancement. Purpose: To identify the breakup- or transfer-induced fission channels in 6Li+232Th reaction and to investigate their effects on FF angular anisotropy. Methods: The FF angular distributions have been measured exclusively at three beam energies (28, 32, and 36 MeV) around the Coulomb barrier in coincidence with projectile breakup fragments like α , d , and p using Si strip detectors. The angular anisotropy obtained for different exclusive breakup- or transfer-induced fission channels are compared with that for total fission. SSPM and pre-equilibrium fission models have been employed to obtain theoretical FF angular anisotropy. Results: Angular anisotropy of the fission fragments produced by different transfer- or breakup-induced fission reactions have been obtained separately in the rest frame of respective recoiling nuclei. Some of these anisotropies were found to be stronger than those of the inclusive fission. Overall angular distributions of transfer or breakup fission, integrated over all possible recoil angles with weight factor proportional to differential cross section of the complementary breakup fragment emitted in coincidence in all possible directions, were obtained. It was observed that the overall FF angular anisotropy for each of these fission channels is less than or equal to the anisotropy of total fission at all the measured energies. Assuming isotropic out-of-plane correlations between the fission fragments and light-charged particles, the overall breakup- or transfer-induced fission fragment angular distributions do not explain the observed enhancement in FF anisotropy of total fission. Pre

  14. 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

  15. 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.

  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. 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.

  18. Measurement of the angular distribution of neutron-proton scattering at 10 MeV

    SciTech Connect

    Haight, R.C.; Bateman, F.B.; Grimes, S.M.; Brient, C.E.; Massey, T.N.; Wasson, O.A.; Carlson, A.D.; Zhou, H.

    1995-12-31

    The relative angular distribution of neutrons scattered from protons was measured at an incident neutron energy of 10 MeV at the Ohio University Accelerator Laboratory. An array of 11 detector telescopes at laboratory angles of 0 to 60 degrees was used to detect recoil protons from neutron interactions with a CH{sub 2} (polypropylene) target. Data for 7 of these telescopes were obtained with one set of electronics and are presented here. These data, from 108 to 180 degrees for the center-of-mass scattering angles, have a small slope which agrees better with angular distributions predicted by the Arndt phase shifts than with the ENDF/B-VI angular distribution.

  19. Monte-Carlo studies of the angular resolution of a future Cherenkov gamma-ray telescope

    SciTech Connect

    Funk, S.; Hinton, J. A.

    2008-12-24

    The current generation of Imaging Atmospheric telescopes (IACTs) has demonstrated the power of this observational technique, providing high sensitivity and an angular resolution of {approx}0.1 deg. per event above an energy threshold of {approx}100 GeV. Planned future arrays of IACTs such as AGIS or CTA are aiming at significantly improving the angular resolution. Preliminary results have shown that values down to {approx}1' might be achievable. Here we present the results of Monte-Carlo simulations that aim to exploring the limits of angular resolution for next generation IACTs and investigate how the resolution can be optimised by changes to array and telescope parameters such as the number of pixel in the camera, the field of view of the camera, the angular pixel size, the mirror size, and also the telescope separation.

  20. Effect of the corrected ionization potential and spatial distribution on the angular and energy distribution in tunnel ionization

    SciTech Connect

    Petrović, V. M.; Miladinović, T. B.

    2016-05-15

    Within the framework of the Ammosov–Delone–Krainov theory, we consider the angular and energy distribution of outgoing electrons due to ionization by a circularly polarized electromagnetic field. A correction of the ground ionization potential by the ponderomotive and Stark shift is incorporated in both distributions. Spatial dependence is analyzed.

  1. 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.

  2. 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.

  3. 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.

  4. Photon angular distribution and nuclear-state alignment in nuclear excitation by electron capture

    NASA Astrophysics Data System (ADS)

    Pálffy, Adriana; Harman, Zoltán; Surzhykov, Andrey; Jentschura, Ulrich D.

    2007-01-01

    The alignment of nuclear states resonantly formed in nuclear excitation by electron capture (NEEC) is studied by means of a density matrix technique. The vibrational excitations of the nucleus are described by a collective model and the electrons are treated in a relativistic framework. Formulas for the angular distribution of photons emitted in the nuclear relaxation are derived. We present numerical results for alignment parameters and photon angular distributions for a number of heavy elements in the case of E2 nuclear transitions. Our results are intended to help future experimental attempts to discern NEEC from radiative recombination, which is the dominant competing process.

  5. 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).

  6. Measurement of sputtered beryllium yield and angular distribution during nanostructure growth in a helium plasma

    NASA Astrophysics Data System (ADS)

    Hollmann, E. M.; Alegre, D.; Baldwin, M. J.; Chrobak, C. P.; Doerner, R. P.; Miyamoto, M.; Nishijima, D.

    2017-09-01

    The angular distribution and sputtering yield of beryllium exposed to helium plasma are estimated from analysis of line-integrated 2D imaging of Be-I line emission in a steady-state linear plasma device. As the surface nanostructure forms during plasma exposure on a ˜100 s timescale (corresponding to a fluence of order 1020/cm2) from nearly mono-energetic ion bombardment, a narrowing of the beryllium sputtering angle and a significant (˜5×) drop in sputtering yield are observed. These trends are found to be qualitatively consistent with modeling taking into account the effect of the surface morphology on sputtering yield and angular distribution.

  7. 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.

  8. 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.

  9. 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.

  10. Discontinuity induced angular distribution of photon plasmon coupling

    SciTech Connect

    Brissinger, D; Lereu, Aude; Salomon, L; Charvolin, T; Cluzel, B; Dumas, C; Passian, Ali; de Fornel, F

    2011-01-01

    Metal-dielectric transitions are important structures that can display a host of optical characteristics including excitation of plasmons. Metal-dielectric discontinuities can furthermore support plasmon excitation without a severe condition on the incident angle of the exciting photons. Using a semi-infinite thin gold film, we study surface plasmon (SP) excitation and the associated electromagnetic near-field distribution by recording the resulting plasmon interference patterns. In particular, we measure interference periods involving SPs at the scanable metal/air interface and the buried metal/glass one. Supported by optical near-field simulations and experiments, we demonstrate that the metal/glass surface plasmon is observable over a wide range of incident angles encompassing values above and below the critical incident angle. As a result, it is shown that scanning near-field microscopy can provide quantitative evaluation of the real part of the buried surface plasmon wavevector.

  11. 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.

  12. Angular distributions of H-induced HD and D2 desorptions from the Si(100) surfaces

    NASA Astrophysics Data System (ADS)

    Inanaga, S.; Kiyonaga, T.; Rahman, F.; Khanom, F.; Namiki, A.; Lee, J.

    2006-02-01

    We measured angular distributions of HD and D2 molecules desorbed via the reactions H +D/Si(100)→HD [abstraction (ABS)] and H +D/Si(100)→D2 [adsorption-induced-desorption (AID)], respectively. It was found that the angular distribution of HD molecules desorbed along ABS is broader than that of D2 molecules desorbed along AID, i.e., the former could be fit with cos2.0±0.2θ, while the latter with cos5.0±0.5θ. This difference of the angular distributions between the two reaction paths suggests that their dynamic mechanisms are different. The observed cos2θ distribution for the ABS reaction was reproduced by the classical trajectory calculations over the London-Eyring-Polanyi-Sato potential-energy surfaces. The simulation suggests that the HD desorption along the ABS path takes place along the direction of Si-D bonds, but the apparent angular distribution is comprised of multiple components reflecting the different orientations of D-occupied Si dimers in the (2×1) and (1×2) double domain structures.

  13. 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.

  14. Evolution of the angular distribution of laser-generated fast electrons due to resistive self-collimation

    NASA Astrophysics Data System (ADS)

    Robinson, A. P. L.; Schmitz, H.

    2015-10-01

    The evolution of the angular distribution of laser-generated fast electrons propagating in dense plasmas is studied by 3D numerical simulations. As resistively generated magnetic fields can strongly influence and even pinch the fast electron beam, the question of the effect on the angular distribution is of considerable interest. It was conjectured that in the limit of strong collimation, there will only be minimal changes to the angular distribution, whereas the largest reduction in the angular distribution will occur where there is only modest pinching of the fast electron beam and the beam is able to expand considerably. The results of the numerical simulations indicate this conjecture.

  15. 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.

  16. 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.

  17. 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

  18. 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.

  19. The dijet mass spectrum and angular distributions with the D0 detector

    SciTech Connect

    Abachi, S.

    1996-07-01

    We present preliminary results from an analysis of dijet data collected during the 1994-95 Tevatron Collider run with an integrated luminosity of 91 pb{sup -1}. Measurements of dijet mass spectra and dijet angular distributions in {anti p}p collisions at {radical}s- = 1.8 TeV are compared with next-to-leading order QCD theory.

  20. 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.

  1. Quadrupole effects in angular distributions of photoelectrons upon ionization of Kr by X-ray photons

    NASA Astrophysics Data System (ADS)

    Merem'yanin, A. V.; Chernov, V. E.; Gavrilov, G. E.; Naryshkin, Yu. G.; Zon, B. A.

    2017-05-01

    Implementation of promising control schemes for the intensity and position of X-ray-laser beams with a photon energy up to several tens of kiloelectronvolts requires knowledge of the angular dependence of cross sections for photoionization of noble gas atoms by hard photons. Estimates of quadrupole corrections to the cross section for photoionization of a Kr atom by X-ray photons with an energy of about 25 keV are reported in this paper. An analytic expression for the cross section of the process is parameterized in a compact form convenient for analyzing angular distributions with an arbitrary polarization of a photon beam.

  2. Angular distribution of beam electrons in a source with arc plasma emitter

    NASA Astrophysics Data System (ADS)

    Kurkuchekov, V.; Astrelin, V.; Kandaurov, I.; Trunev, Yu

    2017-05-01

    Results on studying the angular characteristics of an electron beam, generated in a multi-aperture diode with an arc-discharge plasma emitter are reported. The main beam parameters were as follows: the electron energy up to 120 keV, the emission current up to 100 A, the pulse duration 0.1 - 0.3 ms, and the initial diameter ca. 8 cm. The beam was formed and transported to a metal target in an adiabatically converging magnetic field. The diagnostic technique based on an X-ray imaging of the profiles of individual beamlets passed through the pepperpot-like mask was developed and used to investigate an angular distribution of the beam electrons. The spatial resolution of the diagnostic was evaluated in a special test experiment and found to be not worse than 4 lp/cm at a 10 % contrast level. It was demonstrated that an angular distribution of the beam electrons fits well by the Gaussian function with the RMS width ∼ 0.067 rad. The data on the angular distribution measured with pepperpot diagnostic are in a good agreement with those obtained in the experiments on the beam passage through a magnetic mirror.

  3. 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.

  4. Angular distribution of fusion products and x rays emitted by a small dense plasma focus machine

    SciTech Connect

    Castillo, F.; Herrera, J. J. E.; Gamboa, Isabel; Rangel, J.; Golzarri, J. I.; Espinosa, G.

    2007-01-01

    Time integrated measurements of the angular distributions of fusion products and x rays in a small dense plasma focus machine are made inside the discharge chamber, using passive detectors. The machine is operated at 37 kV with a stored energy of 4.8 kJ and a deuterium filling pressure of 2.75 torr. Distributions of protons and neutrons are measured with CR-39 Lantrack registered nuclear track detectors, on 1.8x0.9 cm{sup 2} chips, 500 {mu}m thick. A set of detectors was placed on a semicircular Teflon registered holder, 13 cm away from the plasma column, and covered with 15 {mu}m Al filters, thus eliminating tritium and helium-3 ions, but not protons and neutrons. A second set was placed on the opposite side of the holder, eliminating protons. The angular distribution of x rays is also studied within the chamber with TLD-200 dosimeters. While the neutron angular distributions can be fitted by Gaussian curves mounted on constant pedestals and the proton distributions are strongly peaked, falling rapidly after {+-}40 deg. , the x-ray distributions show two maxima around the axis, presumably as a result of the collision of a collimated electron beam against the inner electrode, along the axis.

  5. 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.

  6. 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.

  7. 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.

  8. 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).

  9. 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.

  10. 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.

  11. Fragment Angular Distributions in Neutron-Induced Fission of w235U and 239Pu using a Time Projection Chamber

    NASA Astrophysics Data System (ADS)

    Kleinrath, Verena

    2014-09-01

    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 235U and even more so for 239Pu, 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. Analysis of in-beam data collected at the Los Alamos Neutron Science Center with a 239Pu/235U target will provide angular distributions as a function of incident neutron energy for these isotopes. Preliminary angular distributions for 235U and 239Pu using the NIFFTE time projection chamber will be presented. 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 235U and even more so for 239Pu, 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. Analysis of in-beam data collected at the Los Alamos Neutron Science Center with a 239Pu/235U target will provide angular distributions as a function of incident neutron energy for these isotopes. Preliminary angular distributions for 235U and

  12. 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.

  13. Angular Resolution of an EAS Array for Gamma Ray Astronomy at Energies Greater Than 5 x 10 (13) Ev

    NASA Technical Reports Server (NTRS)

    Apte, A. R.; Gopalakrishnan, N. V.; Tonwar, S. C.; Uma, V.

    1985-01-01

    A 24 detector extensive air shower array is being operated at Ootacamund (2300 m altitude, 11.4 deg N latitude) in southern India for a study of arrival directions of showers of energies greater than 5 x 10 to the 13th power eV. Various configurations of the array of detectors have been used to estimate the accuracy in determination of arrival angle of showers with such an array. These studies show that it is possible to achieve an angular resolution of better than 2 deg with the Ooty array for search for point sources of Cosmic gamma rays at energies above 5 x 10 to the 13th power eV.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Near-threshold photoelectron angular distributions from two-photon resonant photoionization of He

    NASA Astrophysics Data System (ADS)

    O'Keeffe, P.; Mihelič, A.; Bolognesi, P.; Žitnik, M.; Moise, A.; Richter, R.; Avaldi, L.

    2013-01-01

    Two-photon resonant photoionization of helium is investigated both experimentally and theoretically. Ground state helium atoms are excited to the 1s4p, 1s5p and 1s6p 1P states by synchrotron radiation and ionized by a synchronized infrared pulsed picosecond laser. The photoelectron angular distributions of the emitted electrons are measured using a velocity map imaging (VMI) spectrometer. The measured asymmetry parameters of the angular distribution allow the phase differences and the ratios of the dipole matrix elements of the 1sɛs and 1sɛd channels to be determined. The experimental results agree with the calculated values obtained in a configuration-interaction calculation with a Coulomb-Sturmian basis set. The effects of the radiative decay of the intermediate state and the static electric field of the VMI spectrometer on the measurements are discussed.

  19. Measurements of neutron scattering angular distributions with a new scintillator setup

    NASA Astrophysics Data System (ADS)

    Pirovano, Elisa; Beyer, Roland; Junghans, Arnd; Nolte, Ralf; Nyman, Markus; Plompen, Arjan

    2017-09-01

    A new experimental setup for the measurement of neutron scattering cross sections and angular distributions is currently being developed at the neutron time-of-flight facility GELINA, at the JRC-Geel. Up to 32 liquid organic scintillators are employed for the detection of neutrons scattered from a sample of the investigated material. The differential cross section is measured at eight different angles, and the angle-integrated cross section is obtained from the differential data by numerical integration. Two experiments for the study of scattering on iron were carried out, one at GELINA and the other at nELBE (HZDR). The first results for the angular distributions of elastic scattering in the neutron energy range from 2 to 6 MeV are here presented and compared with evaluations from the major nuclear data libraries.

  20. 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}

  1. 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.

  2. Neutron spectra and angular distributions of concrete-moderated neutron calibration fields at JAERI.

    PubMed

    Yoshizawa, M; Tanimura, Y; Saegusa, J; Nemoto, H; Yoshida, M

    2004-01-01

    The Facility of Radiation Standards of Japan Atomic Energy Research Institute has been equipped with concrete-moderated neutron calibration fields as simulated workplace neutron fields. The fields use an 241Am-Be neutron source placed in the narrow space surrounded by concrete bricks, walls and floor. The neutron spectra and the neutron fluence rates of the fields were measured with the Bonner multi-sphere spectrometer system (BMS), spherical recoil-proton proportional counters, and a liquid scintillation counter (NE-213). The results were compared with each other. The reference values of H*(10) were determined from the results of BMS. The angular distributions of neutron fluence were calculated using MCNP-4B2 to obtain the reference values of Hp(10). The calculated results show that the scattered neutrons have a wide range of incident angles. The reference Hp(10) values considered the angular distribution were found to be 10-18% smaller than those without consideration.

  3. 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.

  4. 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.

  5. Predicting photoemission intensities and angular distributions with real-time density-functional theory

    NASA Astrophysics Data System (ADS)

    Dauth, M.; Kümmel, S.

    2016-02-01

    Photoemission spectroscopy is one of the most frequently used tools for characterizing the electronic structure of condensed matter systems. We discuss a scheme for simulating photoemission from finite systems based on time-dependent density-functional theory. It allows for the first-principles calculation of relative electron binding energies, ionization cross sections, and anisotropy parameters. We extract these photoemission spectroscopy observables from Kohn-Sham orbitals propagated in real time. We demonstrate that the approach is capable of estimating photoemission intensities, i.e., peak heights. It can also reliably predict the angular distribution of photoelectrons. For the example of benzene we contrast calculated angular distribution anisotropy parameters to experimental reference data. Self-interaction free Kohn-Sham theory yields meaningful outer valence single-particle states in the right energetic order. We discuss how to properly choose the complex absorbing potential that is used in the simulations.

  6. RADIAL ANGULAR MOMENTUM TRANSFER AND MAGNETIC BARRIER FOR SHORT-TYPE GAMMA-RAY-BURST CENTRAL ENGINE ACTIVITY

    SciTech Connect

    Liu Tong; Gu Weimin; Hou Shujin; Liang Enwei; Lei Weihua; Lin Lin; Zhang Shuangnan; Dai Zigao

    2012-11-20

    Soft extended emission (EE) following initial hard spikes up to 100 s was observed with Swift/BAT for about half of known short-type gamma-ray bursts (SGRBs). This challenges the conversional central engine models of SGRBs, i.e., compact star merger models. In the framework of black-hole-neutron-star merger models, we study the roles of radial angular momentum transfer in the disk and the magnetic barrier around the black hole in the activity of SGRB central engines. We show that radial angular momentum transfer may significantly prolong the lifetime of the accretion process, which may be divided into multiple episodes by the magnetic barrier. Our numerical calculations based on models of neutrino-dominated accretion flows suggest that disk mass is critical for producing the observed EE. In the case of the mass being {approx}0.8 M {sub Sun }, our model can reproduce the observed timescale and luminosity of both the main and the EE episodes in a reasonable parameter set. The predicted luminosity of the EE component is lower than the observed EE within about one order of magnitude and the timescale is shorter than 20 s if the disk mass is {approx}0.2 M {sub Sun }. Swift/BAT-like instruments may be not sensitive enough to detect the EE component in this case. We argue that the EE component could be a probe for the merger process and disk formation for compact star mergers.

  7. Radial Angular Momentum Transfer and Magnetic Barrier for Short-type Gamma-Ray-burst Central Engine Activity

    NASA Astrophysics Data System (ADS)

    Liu, Tong; Liang, En-Wei; Gu, Wei-Min; Hou, Shu-Jin; Lei, Wei-Hua; Lin, Lin; Dai, Zi-Gao; Zhang, Shuang-Nan

    2012-11-01

    Soft extended emission (EE) following initial hard spikes up to 100 s was observed with Swift/BAT for about half of known short-type gamma-ray bursts (SGRBs). This challenges the conversional central engine models of SGRBs, i.e., compact star merger models. In the framework of black-hole-neutron-star merger models, we study the roles of radial angular momentum transfer in the disk and the magnetic barrier around the black hole in the activity of SGRB central engines. We show that radial angular momentum transfer may significantly prolong the lifetime of the accretion process, which may be divided into multiple episodes by the magnetic barrier. Our numerical calculations based on models of neutrino-dominated accretion flows suggest that disk mass is critical for producing the observed EE. In the case of the mass being ~0.8 M ⊙, our model can reproduce the observed timescale and luminosity of both the main and the EE episodes in a reasonable parameter set. The predicted luminosity of the EE component is lower than the observed EE within about one order of magnitude and the timescale is shorter than 20 s if the disk mass is ~0.2 M ⊙. Swift/BAT-like instruments may be not sensitive enough to detect the EE component in this case. We argue that the EE component could be a probe for the merger process and disk formation for compact star mergers.

  8. 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

  9. 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.

  10. Beta-ray angular distributions of spin aligned 8Li and 8B

    NASA Astrophysics Data System (ADS)

    Sumikama, T.; Iwakoshi, T.; Nagatomo, T.; Ogura, M.; Nakashima, Y.; Fujiwara, H.; Matsuta, K.; Minamisono, T.; Mihara, M.; Fukuda, M.; Minamisono, K.; Yamaguchi, T.

    2004-12-01

    The alignment correlation terms in the β-ray angular distributions from spin aligned 8Li and 8B have been measured precisely. The difference of these terms between the mirror pair is compared with the prediction. As a result, the G-parity violating induced tensor term is found to be small. The significant contribution from the second-forbidden matrix elements is shown by comparing with the β- α correlation coefficients.

  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. Statistical measurement of the gamma-ray source-count distribution as a function of energy

    DOE PAGES

    Zechlin, Hannes-S.; Cuoco, Alessandro; Donato, Fiorenza; ...

    2016-07-29

    Statistical properties of photon count maps have recently been proven as a new tool to study the composition of the gamma-ray sky with high precision. Here, we employ the 1-point probability distribution function of six years of Fermi-LAT data to measure the source-count distribution dN/dS and the diffuse components of the high-latitude gamma-ray sky as a function of energy. To that aim, we analyze the gamma-ray emission in five adjacent energy bands between 1 and 171 GeV. It is demonstrated that the source-count distribution as a function of flux is compatible with a broken power law up to energies of ~50 GeV. Furthermore, the index below the break is between 1.95 and 2.0. For higher energies, a simple power-law fits the data, with an index ofmore » $${2.2}_{-0.3}^{+0.7}$$ in the energy band between 50 and 171 GeV. Upper limits on further possible breaks as well as the angular power of unresolved sources are derived. We find that point-source populations probed by this method can explain $${83}_{-13}^{+7}$$% ($${81}_{-19}^{+52}$$%) of the extragalactic gamma-ray background between 1.04 and 1.99 GeV (50 and 171 GeV). Our method has excellent capabilities for constraining the gamma-ray luminosity function and the spectra of unresolved blazars.« less

  13. 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.

  14. Angular distribution of GaAs sputtered under oblique Cs + bombardment

    NASA Astrophysics Data System (ADS)

    Verdeil, C.; Wirtz, T.; Scherrer, H.

    2009-08-01

    The angular distribution of Ga and As sputtered from Gallium Arsenide (1 0 0) by a Cs + ion beam was experimentally measured through a collector technique allowing modifications of the energy and incidence angle of the ion beam. The impact energy was varied in the range of 2-10 keV and the angle of incidence from 30° to 60°. The angular distributions of emitted matter are determined by means of SIMS depth profiles. Our series of experiments show an evolution of the preferential direction of emission as well as the spreading around this direction in function of the characteristics of the ion beam. The second objective is the study of the evolution of the stoichiometry of the deposit in function of the emission angle. A decrease of the As/Ga ratio around the preferential direction of emission and an increase of this ratio for oblique emission are observed for different conditions of primary bombardment. Considering that the angular distribution depends on the depth of origin, our results suggest that the Cs + bombardment changes the stoichiometry of the near-surface layers of the sample with an enrichment of As in the outmost layers while the sub-surface region is impoverished in As due to preferential sputtering.

  15. BATSE software for the analysis of the gamma ray burst spatial distribution

    NASA Technical Reports Server (NTRS)

    Hakkila, Jon

    1990-01-01

    The Burst and Transient Source Experiment (BATSE) on the Gamma Ray Observatory (GRO) is designed to study astronomical gamma ray sources and to provide better positional, spectral, and time resolution about these objects than has previously been possible from one experiment. The procedure to be used in the analysis of the gamma ray burst spatial distribution is presented. Data is input from BATSE via the Gamma Ray Burst Catalog (listing individual burst positions, flux values, and associated errors) and the Sky Sensitivity Map (which summarizes observational selection effects in table format). A FORTRAN program generates Monte Carlo burst catalogs, which are models to be compared to the actual distribution. The Monte Carlo models are then filtered through the Sky Sensitivity Map so that they suffer from the same selection effects as the actual catalog data. Additionally, each burst position is converted into a probability distribution to mimic BATSE positional sensitivity. The Burst Catalog, Monte Carlo burst catalog, and Sky Sensitivity Map are then passed onto an IDL program that compares the catalogs for statistical significance. The Sky Sensitivity Map is used to estimate how often each sky area is observed above the minimum flux level in question. Each burst found in this sky area is then weighted according to the frequency with which this sky area is observed. The catalogs are then compared via tests of homogeneity (based on their radial distributions) and isotropy (based upon their angular distributions). The results of the statistical comparisons along with graphs and charts of the summaries, are output from the IDL program for study.

  16. 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.

  17. Angular ion species distribution in droplet-based laser-produced plasmas

    SciTech Connect

    Giovannini, Andrea Z.; Gambino, Nadia; Rollinger, Bob; Abhari, Reza S.

    2015-01-21

    The angular distribution of the ion species generated from a laser irradiated droplet target is measured. The employed instrument was an electrostatic energy analyzer with differential pumping. Singly and doubly charged ions were detected at an argon ambient gas pressure of 2 × 10{sup −2} mbar. The amount of Sn{sup +} and Sn{sup 2+} and their kinetic energy is measured from 45° to 120° from the laser axis. Sn{sup +} expands approximately isotropically, and Sn{sup 2+} expansion is peaked towards the incoming laser radiation. The singly charged ion kinetic energy is close to constant over the measurement range, while it decreases by around 30% for Sn{sup 2+}. A calibrated model of the ion expansion that includes recombinations correctly predicts the mean ion charge distribution. The model is able to qualitatively estimate the influence of the laser wavelength on the mean ion charge distribution. The results show a more pronounced isotropic distribution for shorter wavelengths, and a more forward-peaked distribution for longer wavelengths. The ion charge distribution expected without the ambient gas is estimated through the measured ion kinetic energy. The presence of the ambient gas results in a decrease of the mean ion charge state and a decrease in angular anisotropy.

  18. 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.

  19. Intensity distributions of gamma-ray bursts

    SciTech Connect

    Band, D. L.

    2001-01-01

    Observations of individual bursts chosen by the vagaries of telescope availability demonstrated that bursts are not standard candles and that their apparent energy can be as great as 10{sup 54} erg. However, determining the distribution of their apparent energy (and of other burst properties) requires the statistical analysis of a well-defined burst sample; the sample definition includes the threshold for including a burst in the sample. Thus optical groups need to the criteria behind the decision to search for a spectroscopic redshift. Currently the burst samples are insufficient to choose between lognormal and power law functional forms of the distribution, and the parameter values for these functional forms differ between burst samples. Similarly, the actual intensity distribution may be broader than observed, with a low energy tail extending below the detection threshold.

  20. Angular distribution, kinetic energy distributions, and excitation functions of fast metastable oxygen fragments following electron impact of CO2

    NASA Technical Reports Server (NTRS)

    Misakian, M.; Mumma, M. J.; Faris, J. F.

    1975-01-01

    Dissociative excitation of CO2 by electron impact was studied using the methods of translational spectroscopy and angular distribution analysis. Earlier time of flight studies revealed two overlapping spectra, the slower of which was attributed to metastable CO(a3 pi) fragments. The fast peak is the focus of this study. Threshold energy, angular distribution, and improve time of flight measurements indicate that the fast peak actually consists of five overlapping features. The slowest of the five features is found to consist of metastable 0(5S) produced by predissociation of a sigma u + state of CO2 into 0(5S) + CO(a3 pi). Oxygen Rydberg fragments originating directly from a different sigma u + state are believed to make up the next fastest feature. Mechanisms for producing the three remaining features are discussed.

  1. 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.

  2. Proximal distributions from angular correlations: a measure of the onset of coarse-graining.

    PubMed

    Dyer, Kippi M; Pettitt, B Montgomery

    2013-12-07

    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.

  3. 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.

  4. 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.

  5. Galactic disc profiles and a universal angular momentum distribution from statistical physics

    NASA Astrophysics Data System (ADS)

    Herpich, Jakob; Tremaine, Scott; Rix, Hans-Walter

    2017-06-01

    We show that the stellar surface brightness profiles in disc galaxies - observed to be approximately exponential - can be explained if radial migration efficiently scrambles the individual stars' angular momenta while conserving the circularity of the orbits and the total mass and angular momentum. In this case, the disc's distribution of specific angular momenta j should be near a maximum entropy state and therefore approximately exponential, dN ∝ \\exp (-j/< j\\rangle ) dj. This distribution translates to a surface density profile that is generally not an exponential function of radius: Σ (R) ∝ \\exp [-R/R_e({R})]/ (R R_e({R}))(1+d{ log v_c (R)}/ d{ log R}), for a rotation curve v∞(R) and R_e({R})≡ < j\\rangle /v_c (R). We show that such a profile matches the observed surface brightness profiles of disc-dominated galaxies just as well as the empirical exponential profile. Disc galaxies that exhibit population gradients cannot have fully reached a maximum-entropy state but appear to be close enough that their surface brightness profiles are well fit by this idealized model.

  6. The energy spectrum for stochastic eddies with gamma distribution

    NASA Astrophysics Data System (ADS)

    Kara, Rukiye; Caglar, Mine

    2012-09-01

    Lundgren (1982) showed that strained spiral vortex model for turbulent fine structure has exponential Kolmogorov energy spectrum form. Caglar (2007) has generalized Cinlar velocity field which defined a similar structure with Lundgren vortex and computed the energy spectrum. In this study, we investigate the energy spectrum of the stochastic velocity field using Gamma distribution for small scale eddies.

  7. Measurement of angular distribution of sound emission from training projectiles in subsonic flight

    NASA Technical Reports Server (NTRS)

    Cho, Y. I.; Parthasarathy, S. P.; Harstad, K. G.; Back, L. H.

    1986-01-01

    Training projectiles with nose ring cavities that produce intense whistles in stationary free-jet tests were shot in a relatively straight-line trajectory. A ground based microphone was used to obtain the angular distribution of sound intensity produced from the subsonically flying projectile. Data reduction required calculation of Doppler and attenuation factors which were determined based on a non-linear trajectory. Also, the directional sensitivity of the microphone was measured and used in the data reduction. Significant angular variation of sound intensity produced from the projectile was found which can be used to plot an intensity contour map on the ground. A full-scale field test confirmed the validity of the aeroacoustic concept of producing a relatively intense whistle from the projectile, and the usefulness of a real-time data acquisition system.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Gamma-Ray Burst Intensity Distributions

    NASA Technical Reports Server (NTRS)

    Band, David L.; Norris, Jay P.; Bonnell, Jerry T.

    2004-01-01

    We use the lag-luminosity relation to calculate self-consistently the redshifts, apparent peak bolometric luminosities L(sub B1), and isotropic energies E(sub iso) for a large sample of BATSE bursts. We consider two different forms of the lag-luminosity relation; for both forms the median redshift, for our burst database is 1.6. We model the resulting sample of burst energies with power law and Gaussian dis- tributions, both of which are reasonable models. The power law model has an index of a = 1.76 plus or minus 0.05 (95% confidence) as opposed to the index of a = 2 predicted by the simple universal jet profile model; however, reasonable refinements to this model permit much greater flexibility in reconciling predicted and observed energy distributions.

  13. 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.

  14. 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.

  15. 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.

  16. 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.}

  17. Measurement of the Angular Distribution of the Electron from $W \\to e + \

    SciTech Connect

    Ramos, Manuel Martin

    1996-10-01

    The goal of this thesis is to scan the extensive literature dealing with the properties of the W and Z bosons. Iit is clear that, besides the measurements confirming the weak interactions theory, no specific work related to the angular distributions of the emerging particles from the leptonic decay of the boson has been done. The aim of the work is to obtain experimentally the values of α2, as function of the transverse momentum of the W, that appear in the expression 0.3 and to compare the values obtained with the theoretical predictions.

  18. Anomalous photoelectron angular distribution in ionization of Kr in intense ultraviolet laser fields

    NASA Astrophysics Data System (ADS)

    Nakano, Motoyoshi; Otobe, Tomohito; Itakura, Ryuji

    2017-06-01

    We investigate multiphoton ionization of Kr for the formation of the two spin-orbit split states 1/2 2P and 3/2 2P of Kr+ in intense ultraviolet femtosecond laser fields (λ ≈ 398 nm, τ ≈ 50 fs). As the laser intensity increases from 8 to 39 TW cm-2, the photoelectron angular distribution (PAD) exhibits the anomalous enhancement in the direction perpendicular to the laser polarization. With the support of the time-dependent density functional theory taking account of the spin-orbit interaction, the measured anomalous PAD is ascribed to the autoionization to 3/2 2P.

  19. 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.

  20. Angular distribution and polarization properties of radiation scattering in the classical framework

    NASA Astrophysics Data System (ADS)

    Boca, Madalina

    2017-06-01

    We study the scattering of intense electromagnetic radiation on free relativistic electrons in the classical formalism. Starting from the well known property that in the relativistic regime the radiation is emitted by an accelerated charged particle along its instantaneous velocity direction we discuss the effects of the radiation reaction on the shape of the angular distribution in Thomson effect for the case of linear and circular polarization of the incident light and for different collision geometries. We also study the polarization properties of the emitted radiation for several low intensity cases.

  1. 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.

  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. 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.

  5. A Device for Search of Gamma-Radiation Intensive Sources at the Radiation Accident Condition

    SciTech Connect

    Batiy, Valeriy; Klyuchnykov, A; Kochnev, N; Rudko, Vladimir; shcherbin, vladimir; Yegorov, V; Schmieman, Eric A.

    2005-08-08

    The procedure designed for measuring angular distributions of gamma radiation and for search of gamma radiation intensive sources is described. It is based on application of the original multidetector device ShD-1, for measuring an angular distribution in a complete solid angle (4 pi). The calibration results and data on the angular distributions of intensity of gamma radiation at the roof of Chornobyl NPP ''Shelter'' are presented.

  6. 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.

  7. The Poisson Gamma distribution for wind speed data

    NASA Astrophysics Data System (ADS)

    Ćakmakyapan, Selen; Özel, Gamze

    2016-04-01

    The wind energy is one of the most significant alternative clean energy source and rapidly developing renewable energy sources in the world. For the evaluation of wind energy potential, probability density functions (pdfs) are usually used to model wind speed distributions. The selection of the appropriate pdf reduces the wind power estimation error and also allow to achieve characteristics. In the literature, different pdfs used to model wind speed data for wind energy applications. In this study, we propose a new probability distribution to model the wind speed data. Firstly, we defined the new probability distribution named Poisson-Gamma (PG) distribution and we analyzed a wind speed data sets which are about five pressure degree for the station. We obtained the data sets from Turkish State Meteorological Service. Then, we modelled the data sets with Exponential, Weibull, Lomax, 3 parameters Burr, Gumbel, Gamma, Rayleigh which are used to model wind speed data, and PG distributions. Finally, we compared the distribution, to select the best fitted model and demonstrated that PG distribution modeled the data sets better.

  8. A Sensitivity Analysis of the Logarithmic-Poisson-Gamma Distribution.

    DTIC Science & Technology

    1981-12-01

    NUMBER 2. GOVT ACCE ION NO. RECIPIENT’S CATALOG NUMBER 4. TITLE (ond Suabtie) S . TYPE OF REPORT & PERIOD COVERED A Sensitivity Analysis of Logarithmic...Poisson NEM Gamma DistributionINEM 6. PERFORMING 01G. REPORT NUMBER ____________________________________ WP-81 -05 7. AUTHOR(.) S . CONTACT OR GRANT...NuMBER( s ) W. Steven Denuiy, and Steven Nahmias F33600-8O-C-0530 9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT. PROJECT. TASK( AREA

  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. Angular distribution of single-photon superradiance in a dilute and cold atomic ensemble

    NASA Astrophysics Data System (ADS)

    Kuraptsev, A. S.; Sokolov, I. M.; Havey, M. D.

    2017-08-01

    On the basis of a quantum microscopic approach we study the dynamics of the afterglow of a dilute Gaussian atomic ensemble excited by pulsed radiation. Taking into account the vector nature of the electromagnetic field we analyze in detail the angular and polarization distribution of single-photon superradiance of such an ensemble. The dependence of the angular distribution of superradiance on the length of the pulse and its carrier frequency as well as on the size and the shape of the atomic clouds is studied. We show that there is substantial dependence of the superradiant emission on the polarization and the direction of fluorescence. We observe essential peculiarities of superradiance in the region of the forward diffraction zone and in the area of the coherent backscattering cone. We demonstrate that there are directions for which the rate of fluorescence is several times more than the decay rate of the timed-Dicke state. We show also that single-photon superradiance can be excited by incoherent excitation when atomic polarization in the ensemble is absent. Besides a quantum microscopic approach, we analyze single-photon superradiance on the basis of the theory of incoherent multiple scattering in optically thick media (random walk theory). In the case of very short resonant and long nonresonant pulses we derive simple analytical expressions for the decay rate of single-photon superradiance for incoherent fluorescence in an arbitrary direction.

  11. 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.

  12. 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.

  13. Efficiency and Angular Distribution of Graphene-Plasmon Excitation by Electron Beam

    NASA Astrophysics Data System (ADS)

    Ochiai, Tetsuyuki

    2014-05-01

    We theoretically study the efficiency and angular distribution of a graphene-plasmon excitation by an electron beam. An electron beam incident on doped graphene induces the out-of-plane transition radiation and in-plane plasmon-polariton waves. At the same time the electron loses its kinetic energy by energy conservation. From the momentum-resolved energy-loss spectrum, we can determine how much kinetic energy of the electron is converted into the transition radiation and plasmon-polariton excitation. Numerical results are presented by changing the incident angle and electron velocity. We find that the graphene plasmon polariton of particular frequency can be excited by an electron beam of appropriate velocity. Moreover, a deeply tilted incidence of the electron beam very efficiently excites the graphene plasmon polariton with an angular distribution range from -30 to 30°. We also show that the transition radiation through graphene exhibits a peak at the threshold energy of the interband transition. These theoretical results are obtained under the local-response approximation of the optical conductivity as well as under the plasmon pole approximation. The results are also compared with those obtained in a thin metallic slab.

  14. Photoelectron angular distribution in two-pathway ionization of neon with femtosecond XUV pulses

    NASA Astrophysics Data System (ADS)

    Douguet, Nicolas; Gryzlova, Elena V.; Staroselskaya, Ekaterina I.; Bartschat, Klaus; Grum-Grzhimailo, Alexei N.

    2017-05-01

    We analyze the photoelectron angular distribution in two-pathway interference between nonresonant one-photon and resonant two-photon ionization of neon. We consider a bichromatic femtosecond XUV pulse whose fundamental frequency is tuned near the 2p53s atomic states of neon. The time-dependent Schrödinger equation is solved and the results are employed to compute the angular distribution and the associated anisotropy parameters at the main photoelectron line. We also employ a time-dependent perturbative approach, which allows obtaining information on the process for a large range of pulse parameters, including the steady-state case of continuous radiation, i.e., an infinitely long pulse. The results from the two methods are in relatively good agreement over the domain of applicability of perturbation theory. Contribution to the Topical Issue "Many Particle Spectroscopy of Atoms, Molecules, Clusters and Surfaces", edited by A.N. Grum-Grzhimailo, E.V. Gryzlova, Yu V. Popov, and A.V. Solov'yov.

  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. 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}.

  18. Quantum Key Distribution with High Order Fibonacci-like Orbital Angular Momentum States

    NASA Astrophysics Data System (ADS)

    Pan, Ziwen; Cai, Jiarui; Wang, Chuan

    2017-08-01

    The coding space in quantum communication could be expanded to high-dimensional space by using orbital angular momentum (OAM) states of photons, as both the capacity of the channel and security are enhanced. Here we present a novel approach to realize high-capacity quantum key distribution (QKD) by exploiting OAM states. The innovation of the proposed approach relies on a unique type of entangled-photon source which produces entangled photons with OAM randomly distributed among high order Fiboncci-like numbers and a new physical mechanism for efficiently sharing keys. This combination of entanglement with mathematical properties of high order Fibonacci sequences provides the QKD protocol immunity to photon-number-splitting attacks and allows secure generation of long keys from few photons. Unlike other protocols, reference frame alignment and active modulation of production and detection bases are unnecessary.

  19. 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.

  20. 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.

  1. 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

  2. Angular Correlation Between Kx-Rays and Gamma - in a Spherically-Deformed Nuclei and Measurement of Absolute Pair Production Cross-Sections Near Threshold Energies.

    NASA Astrophysics Data System (ADS)

    Khalil, Ali El Sayed

    1982-03-01

    (i) Measurements of the directional correlations between Kx-rays following internal conversion and (gamma) -rays in ('181)Ta have been made the correlation coefficients are:. A(,22)(K(alpha)(,1) - 133(gamma)) = 0.037 (+OR -) 0.012. A(,44)(K(alpha)(,1) - 133(gamma)) = 0.022 (+OR -) 0.017. A(,22)(K(alpha)(,2) - 133(gamma)) = 0.038 (+OR -) 0.017. A(,44)(K(alpha)(,2) - 133(gamma)) = 0.037 (+OR -) 0.029. The anisotropic correlation measurements in ('181)Ta establish the second known case of this phenomenon. The x-rays follow four internally converted transitions from which 38% of the Kx-rays follow electric-quadrupole internal conversion processes. This anisotropy is caused by the perturbation of the wave functions of the atomic electrons by the static nuclear quadrupole moment which causes a mixture of the two-coupled, two-electron states (VBAR)d'(,3/2), 1s(,1/2), J = 2 > and (VBAR)d'(,5/2), 1s(,1/2), J = 2 > with the unperturbed state (VBAR)1s(,1/2), 1s(,1/2), J = 0 >. The K-shell electrons are then in a quantum state which is an admixture of the three states mentioned above, and K-shell internal conversion results in a d'(,3/2) or d'(,5/2) vacancy in the mixed K-shell state. Accordingly, x-rays form the transition between either 2p(,3/2) or the 2p(,1/2) level, to a d'(,3/2) or d'(,5/2) vacancy, following internal conversion, can result in anisotropic x-ray angular distributions relative to the nuclear symmetry axis. This in turn results in anisotropic directional correlations between Kx-rays and nuclear (gamma)-rays. (ii) Absolute electron-positron pair production cross-sections near threshold energies have been screened. A new technique which is called internal source method is developed. Direct measurements of the cross-section using 2.615 Mev, a mixture of (1.33 + 1.77) Mev, and 1.12 Mev on target materials of Z = 26, 29, 50, 82 and 92 have been obtained. The experimental results agree well with the exact screening calculations for low Z materials; systematic

  3. Effect of transverse vibrations of fissile nuclei on the angular and spin distributions of low-energy fission fragments

    SciTech Connect

    Bunakov, V. E.; Kadmensky, S. G.; Lyubashevsky, D. E.

    2016-05-15

    It is shown that A. Bohr’s classic theory of angular distributions of fragments originating from low-energy fission should be supplemented with quantum corrections based on the involvement of a superposition of a very large number of angular momenta L{sub m} in the description of the relative motion of fragments flying apart along the straight line coincidentwith the symmetry axis. It is revealed that quantum zero-point wriggling-type vibrations of the fissile system in the vicinity of its scission point are a source of these angular momenta and of high fragment spins observed experimentally.

  4. A self-consistent hybrid model of a dual frequency sheath: Ion energy and angular distributions

    SciTech Connect

    Dai Zhongling; Xu Xiang; Wang Younian

    2007-01-15

    This paper presents a self-consistent hybrid model including the fluid model which can describe the characteristics of collisional sheaths driven by dual radio-frequency (DF) sources and Monte Carlo (MC) method which can determine the ion energy and angular distributions incident onto the dual rf powered electrode. The charge-exchange collisions between ions and neutrals are included in the MC model in which a self-consistent instantaneous electric field obtained from the fluid model is adopted. In the simulation, the driven method we used is either the current-driven method or the voltage-driven method. In the current-driven method, the rf current sources are assumed to apply to an electrode, which is the so-called the equivalent circuit model and is used to self-consistently determine the relationship between the instantaneous sheath potential and the sheath thickness. In the voltage-driven method, however, the rf voltage sources are assumed to apply to an electrode. The dual rf sheath potential, sheath thickness, ion flux, ion energy distributions (IEDs), and ion angular distributions (IADs) are calculated for different parameters. The numerical solutions show that some external parameters such as the bias frequency and power of the lower-frequency source as well as gas pressure are crucial for determining the structure of collisional dual rf sheaths and the IEDs. The shapes of the IADs, however, are determined mainly by the gas pressure. Furthermore, it is found that the results from the different driven methods behave in the same way although there are some differences in some quantities.

  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. 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.

  7. 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}

  8. 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

  9. Strong oscillations in the nondipole corrections to the photoelectron angular distributions from C{sub 60}

    SciTech Connect

    Toffoli, Daniele; Decleva, Piero

    2010-06-15

    Nondipolar corrections to the photoelectron angular distributions from C{sub 60} have been calculated for the highest occupied molecular orbital (HOMO), HOMO-1, and HOMO-2 photoemission bands. The computational method employed takes advantage of a parallel algorithm that uses a multicentric expansion of bound- and scattering-wave functions and a density-functional theory one-particle Hamiltonian. First-order nondipolar asymmetry parameters have been calculated from thresholds of up to 160 eV of photon energy. Strong oscillations, reminiscent of those found in the ratio of the HOMO and HOMO-1 partial cross sections, have been observed in the nondipolar asymmetry parameters as well. The oscillations have the same period, but a different phase, compared to the ones that characterize the HOMO-HOMO-1 intensity ratio.

  10. Optofluidic distributed feedback lasers with evanescent pumping: Reduced threshold and angular dispersion analysis

    NASA Astrophysics Data System (ADS)

    Karl, Markus; Whitworth, Guy L.; Schubert, Marcel; Dietrich, Christof P.; Samuel, Ifor D. W.; Turnbull, Graham A.; Gather, Malte C.

    2016-06-01

    We demonstrate an evanescently pumped water-based optofluidic distributed feedback (DFB) laser with a record low pump threshold of ETH=520 n J . The low threshold results from an optimized mode shape, which is achieved by a low refractive index substrate, and from the use of a mixed-order DFB grating. Investigating the photonic band structure via angular dispersion analysis both above and below lasing threshold allows us to measure the refractive index of the liquid gain layer and to determine the device parameters such as the waveguide core layer thickness. We show that it is possible to tailor the divergence of the lasing emission by varying the number of second order grating periods used for outcoupling.

  11. 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.

  12. 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..

  13. Photoionization of He above the N =2 threshold. II. Angular distribution of photoelectrons and asymmetry parameter

    SciTech Connect

    Sanchez, I.; Martin, F. )

    1992-04-01

    We report theoretical calculations for the {beta}{sub 2{ital p}}-asymmetry parameter in the photoionization of He(1{ital s}{sup 2}) above the {ital N}=2 ionization threshold. We use an extension of a method recently proposed (I. Sanchez and F. Martin, Phys. Rev. A 44, 7318 (1991)) that makes use of a Feshbach partitioning of the final-state wave function and an {ital L}{sup 2} representation of the coupled continuum states. Partial differential cross sections at emission angles 0{degree} and 90{degree} are also provided. Our results are in good agreement with the experimental data, thus showing the accuracy of the present method to study electron angular-distribution properties.

  14. 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.

  15. 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).

  16. 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%.

  17. 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.

  18. 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.

  19. Virtuality Distributions in application to gamma gamma* to pi^0 Transition Form Factor at Handbag Level

    SciTech Connect

    Radyushkin, Anatoly V.

    2014-07-01

    We outline basics of a new approach to transverse momentum dependence in hard processes. As an illustration, we consider hard exclusive transition process gamma*gamma -> to pi^0 at the handbag level. Our starting point is coordinate representation for matrix elements of operators (in the simplest case, bilocal O(0,z)) describing a hadron with momentum p. Treated as functions of (pz) and z^2, they are parametrized through a virtuality distribution amplitude (VDA) Phi (x, sigma), with x being Fourier-conjugate to (pz) and sigma Laplace-conjugate to z^2. For intervals with z^+=0, we introduce transverse momentum distribution amplitude (TMDA) Psi (x, k_\\perp), and write it in terms of VDA Phi (x, \\sigma). The results of covariant calculations, written in terms of Phi (x sigma) are converted into expressions involving Psi (x, k_\\perp. Starting with scalar toy models, we extend the analysis onto the case of spin-1/2 quarks and QCD. We propose simple models for soft VDAs/TMDAs, and use them for comparison of handbag results with experimental (BaBar and BELLE) data on the pion transition form factor. We also discuss how one can generate high-k_\\perp tails from primordial soft distributions.

  20. 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.

  1. Angular distribution of polarized light and its effect on light extraction efficiency in AlGaN deep-ultraviolet light-emitting diodes.

    PubMed

    Chen, Xinjuan; Ji, Cheng; Xiang, Yong; Kang, Xiangning; Shen, Bo; Yu, Tongjun

    2016-05-16

    Angular distribution of polarized light and its effect on light extraction efficiency (LEE) in AlGaN deep-ultraviolet (DUV) light-emitting diodes (LEDs) are investigated in this paper. A united picture is presented to describe polarized light's emission and propagation processes. It is found that the electron-hole recombinations in AlGaN multiple quantum wells produce three kinds of angularly distributed polarized emissions and propagation process can change their intensity distributions. By investigation the change of angular distributions in 277nm and 215nm LEDs, this work reveals that LEE can be significantly enhanced by modulating the angular distributions of polarized light of DUV LEDs.

  2. 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.

  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. Angular distribution of coherent Cherenkov radiation from a bunch passing through a vacuum channel in the dielectric target

    NASA Astrophysics Data System (ADS)

    Potylitsyn, A. P.; Gogolev, S. Yu.; Sukhikh, L. G.

    2017-07-01

    Coherent Cherenkov radiation (ChR) generated by an electron bunch passing through a vacuum channel in the dielectric target has been considered. Simulation of ChR characteristics has been carried out basing on polarization current method. Spectral-angular distributions of coherent ChR generated by the short electron bunches are presented for a flat target with a slit and a conical target with a vacuum channel. We demonstrate feasibility of using cesium iodide conical target for bunch length diagnostics. Bunch length of about 100 fs (rms) could be determined measuring the angular distribution of coherent ChR due to material frequency dispersion.

  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. 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.

  6. 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.}

  7. Variable Mixed Orbital Character in the Photoelectron Angular Distribution of NO_{2}

    NASA Astrophysics Data System (ADS)

    Laws, Benjamin A.; Cavanagh, Steven J.; Lewis, Brenton R.; Gibson, Stephen T.

    2017-06-01

    NO_{2} a key component of photochemical smog and an important species in the Earth's atmosphere, is an example of a molecule which exhibits significant mixed orbital character in the HOMO. In photoelectron experiments the geometric properties of the parent anion orbital are reflected in the photoelectron angular distribution (PAD), an area of research that has benefited largely from the ability of velocity-map imaging (VMI) to simultaneously record both the energetic and angular information, with 100% collection efficiency. Photoelectron spectra of NO_{2}^{-}, taken over a range of wavelengths (355nm-520nm) with the ANU's VMI spectrometer, reveal an anomalous jump in the anisotropy parameter near threshold. Consequently, the orbital behavior of NO_{2}^{-} appears to be quite different near threshold compared to detachment at higher photon energies. This surprising effect is due to the Wigner Threshold law, which causes p orbital character to dominate the photodetachment cross-section near threshold, before the mixed s/d orbital character becomes significant at higher electron kinetic energies. By extending recent work on binary character models to form a more general expression, the variable mixed orbital character of NO_{2}^{-} is able to be described. This study provides the first multi-wavelength NO_{2} anisotropy data, which is shown to be in decent agreement with much earlier zero-core model predictions of the anisotropy parameter. K. J. Reed, A. H. Zimmerman, H. C. Andersen, and J. I. Brauman, J. Chem. Phys. 64, 1368, (1976). doi:10.1063/1.432404 D. Khuseynov, C. C. Blackstone, L. M. Culberson, and A. Sanov, J. Chem. Phys. 141, 124312, (2014). doi:10.1063/1.4896241 W. B. Clodius, R. M. Stehman, and S. B. Woo, Phys. Rev. A. 28, 760, (1983). doi:10.1103/PhysRevA.28.760 Research supported by the Australian Research Council Discovery Project Grant DP160102585

  8. Photoelectron angular distribution from free SiO2 nanoparticles as a probe of elastic electron scattering.

    PubMed

    Antonsson, E; Langer, B; Halfpap, I; Gottwald, J; Rühl, E

    2017-06-28

    In order to gain quantitative information on the surface composition of nanoparticles from X-ray photoelectron spectroscopy, a detailed understanding of photoelectron transport phenomena in these samples is needed. Theoretical results on the elastic and inelastic scattering have been reported, but a rigorous experimental verification is lacking. We report in this work on the photoelectron angular distribution from free SiO2 nanoparticles (d = 122 ± 9 nm) after ionization by soft X-rays above the Si 2p and O 1s absorption edges, which gives insight into the relative importance of elastic and inelastic scattering channels in the sample particles. The photoelectron angular anisotropy is found to be lower for photoemission from SiO2 nanoparticles than that expected from the theoretical values for the isolated Si and O atoms in the photoelectron kinetic energy range 20-380 eV. The reduced angular anisotropy is explained by elastic scattering of the outgoing photoelectrons from neighboring atoms, smearing out the atomic distribution. Photoelectron angular distributions yield detailed information on photoelectron elastic scattering processes allowing for a quantification of the number of elastic scattering events the photoelectrons have undergone prior to leaving the sample. The interpretation of the experimental photoelectron angular distributions is complemented by Monte Carlo simulations, which take inelastic and elastic photoelectron scattering into account using theoretical values for the scattering cross sections. The results of the simulations reproduce the experimental photoelectron angular distributions and provide further support for the assignment that elastic and inelastic electron scattering processes need to be considered.

  9. Photoelectron angular distribution from free SiO2 nanoparticles as a probe of elastic electron scattering

    NASA Astrophysics Data System (ADS)

    Antonsson, E.; Langer, B.; Halfpap, I.; Gottwald, J.; Rühl, E.

    2017-06-01

    In order to gain quantitative information on the surface composition of nanoparticles from X-ray photoelectron spectroscopy, a detailed understanding of photoelectron transport phenomena in these samples is needed. Theoretical results on the elastic and inelastic scattering have been reported, but a rigorous experimental verification is lacking. We report in this work on the photoelectron angular distribution from free SiO2 nanoparticles (d = 122 ± 9 nm) after ionization by soft X-rays above the Si 2p and O 1s absorption edges, which gives insight into the relative importance of elastic and inelastic scattering channels in the sample particles. The photoelectron angular anisotropy is found to be lower for photoemission from SiO2 nanoparticles than that expected from the theoretical values for the isolated Si and O atoms in the photoelectron kinetic energy range 20-380 eV. The reduced angular anisotropy is explained by elastic scattering of the outgoing photoelectrons from neighboring atoms, smearing out the atomic distribution. Photoelectron angular distributions yield detailed information on photoelectron elastic scattering processes allowing for a quantification of the number of elastic scattering events the photoelectrons have undergone prior to leaving the sample. The interpretation of the experimental photoelectron angular distributions is complemented by Monte Carlo simulations, which take inelastic and elastic photoelectron scattering into account using theoretical values for the scattering cross sections. The results of the simulations reproduce the experimental photoelectron angular distributions and provide further support for the assignment that elastic and inelastic electron scattering processes need to be considered.

  10. 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.

  11. A comparison of the generalized gamma and exponentiated Weibull distributions.

    PubMed

    Cox, Christopher; Matheson, Matthew

    2014-09-20

    This paper provides a comparison of the three-parameter exponentiated Weibull (EW) and generalized gamma (GG) distributions. The connection between these two different families is that the hazard functions of both have the four standard shapes (increasing, decreasing, bathtub, and arc shaped), and in fact, the shape of the hazard is the same for identical values of the three parameters. For a given EW distribution, we define a matching GG using simulation and also by matching the 5 (th) , 50 (th) , and 95 (th) percentiles. We compare EW and matching GG distributions graphically and using the Kullback-Leibler distance. We find that the survival functions for the EW and matching GG are graphically indistinguishable, and only the hazard functions can sometimes be seen to be slightly different. The Kullback-Leibler distances are very small and decrease with increasing sample size. We conclude that the similarity between the two distributions is striking, and therefore, the EW represents a convenient alternative to the GG with the identical richness of hazard behavior. More importantly, these results suggest that having the four basic hazard shapes may to some extent be an important structural characteristic of any family of distributions. Copyright © 2014 John Wiley & Sons, Ltd.

  12. Simulations of a spectral gamma-ray logging tool response to a surface source distribution on the borehole wall

    SciTech Connect

    Wilson, R.D.; Conaway, J.G.

    1991-12-01

    We have developed Monte Carlo and discrete ordinates simulation models for the large-detector spectral gamma-ray (SGR) logging tool in use at the Nevada Test Site. Application of the simulation models produced spectra for source layers on the borehole wall, either from potassium-bearing mudcakes or from plate-out of radon daughter products. Simulations show that the shape and magnitude of gamma-ray spectra from sources distributed on the borehole wall depend on radial position with in the air-filled borehole as well as on hole diameter. No such dependence is observed for sources uniformly distributed in the formation. In addition, sources on the borehole wall produce anisotropic angular fluxes at the higher scattered energies and at the source energy. These differences in borehole effects and in angular flux are important to the process of correcting SGR logs for the presence of potassium mudcakes; they also suggest a technique for distinguishing between spectral contributions from formation sources and sources on the borehole wall. These results imply the existence of a standoff effect not present for spectra measured in air-filled boreholes from formation sources. 5 refs., 11 figs.

  13. 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.

  14. HARPO: beam characterization of a TPC for gamma-ray polarimetry and high angular-resolution astronomy in the MeV-GeV range

    NASA Astrophysics Data System (ADS)

    Wang, Shaobo; Bernard, Denis; Bruel, Philippe; Frotin, Mickael; Geerebaert, Yannick; Giebels, Berrie; Gros, Philippe; Horan, Deirdre; Louzir, Marc; Poilleux, Patrick; Semeniouk, Igor; Attié, David; Calvet, Denis; Colas, Paul; Delbart, Alain; Sizun, Patrick; Götz, Diego; Amano, Sho; Kotaka, Takuya; Hashimoto, Satoshi; Minamiyama, Yasuhito; Takemoto, Akinori; Yamaguchi, Masashi; Miyamoto, Shuji; Daté, Schin; Ohkuma, Haruo

    2015-11-01

    A time projection chamber (TPC) can be used to measure the polarization of gamma rays with excellent angular precision and sensitivity in the MeV-GeV energy range through the conversion of photons to e+e- pairs. The Hermetic ARgon POlarimeter (HARPO) prototype was built to demonstrate this concept. It was recently tested in the polarized photon beam at the NewSUBARU facility in Japan. We present this data-taking run, which demonstrated the excellent performance of the HARPO TPC.

  15. Cosmological Evolution and Distributions of Gamma-ray Bursts

    NASA Astrophysics Data System (ADS)

    Petrosian, Vahe

    2012-07-01

    Gamma-ray Bursts (GRBs), in virtue of their large redshifts are good candidates for the probe of the early universe, in particular the history of star formation and the build-up of the so-called metalicity. Moreover, discovery of a tight relation between a distance independent property (e.g photon energy or timescale) and a distance dependent one (e.g luminosity or emitted power) will allow one to use GRBs as "standard candles" for measurements of the global cosmological parameters. The achievement of these potentials requires determination of the distributions and cosmological evolutions of the relevant characteristics and the correlations between them. We have applied the non-parametric methods developed by Efron and Petrosian to GRB data from Swift and earlier satellites to determine the cosmological evolutions of the gamma-ray and X-ray luminosities, timescales and their formation rate. We also have determined the correlations between some of these quantities to test the possibility of using GRBs as standard candles. The results using the most current data will be presented. This work is done in collaboration with M. Dainotti, E. Kitanidis and D. Kocevski all at Stanford University.

  16. On the Angular Distribution of Neutrons Protons and X-Rays from a Small Dense Plasma Focus Machine

    SciTech Connect

    Herrera, J.J.E.; Castillo, F.; Gamboa, I.; Rangel, R.; Espinosa, G.; Golzarri, J. I.

    2006-01-05

    Time integrated measurements of the angular distributions of neutrons, protons and X-rays are made, inside the discharge chamber of the FN-II device, using passive detectors. A set of detectors was placed on a semi-circular Teflon registered holder, 13 cm. around the plasma column, and covered with 15 {mu}m Al filters, thus eliminating energetic ions from the expansion of the discharge, as well as tritium and helium-3 ions, but not protons and neutrons. A second set was placed on the opposite side of the holder, eliminating protons. It is found that the detectors on the upper side of the holder show two distinctively different distributions of track diameters. The distribution of the smaller ones, is sharper than that of the larger ones, and are presumably originated by a wide angle beam of protons. The distribution of the ones on the lower side of the holder, which can only be attributed to charged particles which result as a recoil of neutron collisions, are slightly shifted to larger diameters. The angular distribution of X-rays is also studied within the chamber with TLD-200 dosimeters. While the neutron and proton angular distributions can be fitted by single maximum distributions, the X-ray one shows two maxima around the axis.

  17. 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.

  18. 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.

  19. 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).

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  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. 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.

  11. 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}

  12. 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

  13. 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)].

  14. 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.

  15. 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.

  16. Fission prompt gamma-ray multiplicity distribution measurements and simulations at DANCE

    SciTech Connect

    Chyzh, A; Wu, C Y; Ullmann, J; Jandel, M; Bredeweg, T; Couture, A; Norman, E

    2010-08-24

    The nearly energy independence of the DANCE efficiency and multiplicity response to {gamma} rays makes it possible to measure the prompt {gamma}-ray multiplicity distribution in fission. We demonstrate this unique capability of DANCE through the comparison of {gamma}-ray energy and multiplicity distribution between the measurement and numerical simulation for three radioactive sources {sup 22}Na, {sup 60}Co, and {sup 88}Y. The prospect for measuring the {gamma}-ray multiplicity distribution for both spontaneous and neutron-induced fission is discussed.

  17. Gamma convolution models for self-diffusion coefficient distributions in PGSE NMR.

    PubMed

    Röding, Magnus; Williamson, Nathan H; Nydén, Magnus

    2015-12-01

    We introduce a closed-form signal attenuation model for pulsed-field gradient spin echo (PGSE) NMR based on self-diffusion coefficient distributions that are convolutions of n gamma distributions, n⩾1. Gamma convolutions provide a general class of uni-modal distributions that includes the gamma distribution as a special case for n=1 and the lognormal distribution among others as limit cases when n approaches infinity. We demonstrate the usefulness of the gamma convolution model by simulations and experimental data from samples of poly(vinyl alcohol) and polystyrene, showing that this model provides goodness of fit superior to both the gamma and lognormal distributions and comparable to the common inverse Laplace transform. Copyright © 2015 Elsevier Inc. All rights reserved.

  18. 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.

  19. 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

  20. 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.

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

    PubMed

    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.

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. Implementation of a new energy-angular distribution of particles emitted by deuteron induced nuclear reaction in transport simulations

    NASA Astrophysics Data System (ADS)

    Sauvan, Patrick; Koning, Arjan; Ogando, Francisco; Sanz, Javier

    2017-09-01

    MCUNED code is an MCNPX extension able to handle evaluated nuclear data library for light ion transport simulations. In this work the MCUNED code is improved to describe more accurately the neutron emission during deuteron induced nuclear reaction. This code update consists in introducing a new methodology to take into account the angular distribution of neutron produced by deuteron breakup reaction. To carry out this work a new formulation for the angular distribution of neutrons produced by breakup reaction has been proposed. The implementation of this new methodology requires the use of extra parameters which are provided by the nuclear code TALYS and stored in the ENDF file. This new methodology shows significant improvement in comparison with the former treatment of neutron emission kinematics, these results are in good agreement with experimental data.

  7. 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.

  8. Angular distributions of electrons photoemitted from core levels of oriented diatomic molecules: Multiple scattering theory in non-spherical potentials

    SciTech Connect

    Diez Muino, R.; Rolles, D.; Garcia de Abajo, F.J.; Fadley, C.S.; Van Hove, M.A.

    2001-09-06

    We use multiple scattering in non-spherical potentials (MSNSP) to calculate the angular distributions of electrons photoemitted from the 1s-shells of CO and N2 gas-phase molecules with fixed-in-space orientations. For low photoelectron kinetic energies (E<50 eV), as appropriate to certain shape-resonances, the electron scattering must be represented by non-spherical scattering potentials, which are naturally included in our formalism. Our calculations accurately reproduce the experimental angular patterns recently measured by several groups, including those at the shape-resonance energies. The MSNSP theory thus enhances the sensitivity to spatial electronic distribution and dynamics, paving the way toward their determination from experiment.

  9. 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.

  10. Stretched configuration of states as inferred from γ -ray angular distributions in 40Ar + 208Pb neutron transfer reactions

    NASA Astrophysics Data System (ADS)

    Čolović, P.; Szilner, S.; Corradi, L.; Mijatović, T.; Pollarolo, G.; Goasduff, A.; Montanari, D.; Chapman, R.; Fioretto, E.; Gadea, A.; Haas, F.; Jelavić Malenica, D.; Mărginean, N.; Mengoni, D.; Milin, M.; Montagnoli, G.; Scarlassara, F.; Smith, J. F.; Soić, N.; Stefanini, A. M.; Ur, C. A.; Valiente-Dobón, J. J.

    2017-08-01

    Angular distributions of γ -rays for selected transitions in 40, 41, 42Ar isotopes have been studied with the PRISMA magnetic spectrometer coupled to the CLARA γ array. These transitions were populated in Ar isotopes reached via neutron transfer in the 40Ar + 208Pb reaction. By comparison with the shape of the experimental angular distribution of the known E2 transitions we established more firmly the spin and parity of excited states. In particular, in 41Ar for the (11/2^-) state through the (11/2^-) → 7/2^- transition whose structure was discussed in terms of a phonon-fermion coupled state. The comparison with the expected fully aligned spin indicated that a high level of spin alignment has been reached.

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

    DOE PAGES

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

    2017-01-17

    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. In observing the photoejected electron in coincidence with an F+ atomic ion after Auger decay we see how selecting the dissociation path where the core hole was localized was 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 frommore » the Ne-like valence structure of the F(1s-1) core-excited atom.« less

  12. 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.

  13. Molecular frame photoelectron angular distributions for core ionization of ethane, carbon tetrafluoride and 1,1-difluoroethylene

    DOE PAGES

    Menssen, A.; Trevisan, C. S.; Schöffler, M. S.; ...

    2016-02-15

    Molecular frame photoelectron angular distributions (MFPADs) are measured in this paper in electron–ion momentum imaging experiments and compared with complex Kohn variational calculations for carbon K-shell ionization of carbon tetrafluoride (CF4), ethane (C2H6) and 1,1-difluoroethylene (C2H2F2). While in ethane the polarization averaged MFPADs show a tendency at low energies for the photoelectron to be emitted in the directions of the bonds, the opposite effect is seen in CF4. A combination of these behaviors is seen in difluoroethylene where ionization from the two carbons can be distinguished experimentally because of their different K-shell ionization potentials. Excellent agreement is found between experimentmore » and simple static-exchange or coupled two-channel theoretical calculations. Finally, however, simple electrostatics do not provide an adequate explanation of the suggestively simple angular distributions at low electron ejection energies.« less

  14. Measurements of angular distributions for7Li elastically scattered from58Ni at energies around the Coulomb barrier

    NASA Astrophysics Data System (ADS)

    Amador-Valenzuela, P.; Aguilera, E. F.; Martinez-Quiroz, E.; Lizcano, D.; Morales-Rivera, J. C.

    2017-07-01

    Recently, experimental measurements of elastic scattering angular distributions for the system7Li+58Ni at ten different energies around the Coulomb barrier were made by the Heavy-Ion Group. The measurements were made at the Tandem Van de Graaff Particle Accelerator Laboratory in the National Institute for Nuclear Research (ININ) in Mexico. In this work, preliminary elastic scattering angular distributions for five energies (E lab , = 12.0, 12.5, 13.0, 13.5 and 14.22 MeV) are presented. The preliminary experimental data were analyzed using the São Paulo Optical Model Potential (SPP) which is based on a double-folding potential, reproducing very well these data. A comparison is made with old data reported back in 1973 and in 2012. Further analysis is in progress in order to fully understand this particular system, specially because7Li is known to be a weakly bound nucleus.

  15. 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.

  16. Angular distribution functions in the decays of the 3 D 3 state of charmonium originating from unpolarized overline{p}p collisions

    NASA Astrophysics Data System (ADS)

    Mok, Alex W. K.; Wong, Cheuk-Ping; Sit, Wai-Yu

    2012-10-01

    Using the helicity formalism, we calculate the combined angular distribution function of the two photons (γ1 and γ2) and electron ( e -) in the cascade process overline{p}pto {}^3{D_3}to {}^3{P_2}+{γ_1}to ( {ψ +{γ_2}} )+{γ_1}to ( {{e+}+{e-}} )+{γ_2}+{γ_1},when overline{p} and p are unpolarized. We also derive six different partially integrated angular distribution functions which give the angular distributions of one or two particles in the final state. Once the angular distributions are measured, our expressions will enable one to determine the relative magnitudes as well as the cosines of the relative phases of all the angular-momentum helicity amplitudes in the radiative decay processes 3 D 3 → 3 P 2 + γ1 and 3 P 2 → ψ + γ2.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. Angular distributions of single- and double-electron capture in very-slow Ar sup 6+ -Ar collisions

    SciTech Connect

    Biedermann, C.; Levin, J.C.; Short, R.T.; Elston, S.B.; Gibbons, J.P.; Kimura, K.; Keller, N.; Sellin, I.A. . Dept. of Physics Oak Ridge National Lab., TN ); Cederquist, H.; Andersson, L.R.; Andersson, H.; Liljeby, L. )

    1990-01-01

    We have measured state-resolved angular distributions of one- and two-electron capture in 32 to 800 eV Ar{sup 6+} {minus} Ar collisions. The experimental energy-gain spectra show that single-electron capture mainly populates the 5s, 5p and 4f levels. We observe detailed structures in the corresponding angular distributions, but a final interpretation has to await a quantitative analysis of the collision dynamics. We tentatively ascribe the main features in the angular distribution of true double-electron capture at Q {approximately} 26 eV (4s4f and 4s5s) and Q {approximately} 42 eV (3d4d) to processes involving two consecutive one-electron transitions. For the transfer ionization process, we measure a Q-value of {approximately}eV, which we assign to autoionizing 4s5s (or 4s4f) levels. The 4s5s, 4s4f, and 3d4d levels all reside above the first ionization limit of Ar{sup 4+}, but we find that the 3d4d level stabilizes through radiative decay. 8 refs., 4 figs.

  3. 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.

  4. 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.

  5. A bivariate pseudo Gamma distribution with application to acid rain data

    NASA Astrophysics Data System (ADS)

    Pilz, J.; Mohsin, M.; Gebhardt, A.

    2012-04-01

    Univariate and bivariate Gamma distributions are extensively used for statistical modeling in climatology. In this paper, a bivariate pseudo Gamma distribution is used to model the proportion of acidity and major ions in rain. The model parameters of the bivariate pseudo Gamma distribution are estimated by the maximum likelihood method. The plots of the distribution of the proportions are compared to the histograms of the observed data of the proportions of acidity and major ions in rain. The fitted pdf appears to follow the general pattern in the histograms closely.

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

    PubMed

    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

    2010-11-07

    We present a comprehensive photoelectron imaging study of the O(2)(X  (3)Σ(g)(-),v(')=0-6)←O(2)(-)(X  (2)Π(g),v(")=0) and O(2)(a (1)Δ(g),v(')=0-4)←O(2)(-)(X  (2)Π(g),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 π(g)(∗) 2p highest occupied molecular orbital of O(2)(-). However, differences exist between the β(E) trends for detachment into different vibrational levels of the X  (3)Σ(g)(-) and a (1)Δ(g) electronic states of O(2). 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 O(2): 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.

  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. 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.

  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. PHEV Energy Use Estimation: Validating the Gamma Distribution for Representing the Random Daily Driving Distance

    SciTech Connect

    Lin, Zhenhong; Dong, Jing; Liu, Changzheng; Greene, David L

    2012-01-01

    The petroleum and electricity consumptions of plug-in hybrid electric vehicles (PHEVs) are sensitive to the variation of daily vehicle miles traveled (DVMT). Some studies assume DVMT to follow a Gamma distribution, but such a Gamma assumption is yet to be validated. This study finds the Gamma assumption valid in the context of PHEV energy analysis, based on continuous GPS travel data of 382 vehicles, each tracked for at least 183 days. The validity conclusion is based on the found small prediction errors, resulting from the Gamma assumption, in PHEV petroleum use, electricity use, and energy cost. The finding that the Gamma distribution is valid and reliable is important. It paves the way for the Gamma distribution to be assumed for analyzing energy uses of PHEVs in the real world. The Gamma distribution can be easily specified with very few pieces of driver information and is relatively easy for mathematical manipulation. Given the validation in this study, the Gamma distribution can now be used with better confidence in a variety of applications, such as improving vehicle consumer choice models, quantifying range anxiety for battery electric vehicles, investigating roles of charging infrastructure, and constructing online calculators that provide personal estimates of PHEV energy use.

  11. PHEV Energy Use Estimation: Validating the Gamma Distribution for Representing the Random Daily Driving Distance

    SciTech Connect

    Lin, Zhenhong; Dong, Jing; Liu, Changzheng; Greene, David L

    2012-01-01

    The petroleum and electricity consumptions of plug-in hybrid electric vehicles (PHEVs) are sensitive to the variation of daily vehicle miles traveled (DVMT). Some studies assume DVMT to follow a Gamma distribution, but such a Gamma assumption is yet to be validated. This study finds the Gamma assumption valid in the context of PHEV energy analysis, based on continuous GPS travel data of 382 vehicles, each tracked for at least 183 days. The validity conclusion is based on the found small prediction errors, resulting from the Gamma assumption, in PHEV petroleum use, electricity use, and energy cost. The finding that the Gamma distribution is valid and reliable is important. It paves the way for the Gamma distribution to be assumed for analyzing energy uses of PHEVs in the real world. The Gamma distribution can be easily specified with very few pieces of driver information and is relatively easy for mathematical manipulation. Given the validation in this study, the Gamma distribution can now be used with better confidence in a variety of applications, such as improving vehicle consumer choice models, quantifying range anxiety for battery electric vehicles, investigating roles of charging infrastructure, and constructing online calculators that provide personal estimates of PHEV energy use.

  12. Novel Radiobiological Gamma Index for Evaluation of 3-Dimensional Predicted Dose Distribution

    SciTech Connect

    Sumida, Iori; Yamaguchi, Hajime; Kizaki, Hisao; Aboshi, Keiko; Tsujii, Mari; Yoshikawa, Nobuhiko; Yamada, Yuji; Suzuki, Osamu; Seo, Yuji; Isohashi, Fumiaki; Yoshioka, Yasuo; Ogawa, Kazuhiko

    2015-07-15

    Purpose: To propose a gamma index-based dose evaluation index that integrates the radiobiological parameters of tumor control (TCP) and normal tissue complication probabilities (NTCP). Methods and Materials: Fifteen prostate and head and neck (H&N) cancer patients received intensity modulated radiation therapy. Before treatment, patient-specific quality assurance was conducted via beam-by-beam analysis, and beam-specific dose error distributions were generated. The predicted 3-dimensional (3D) dose distribution was calculated by back-projection of relative dose error distribution per beam. A 3D gamma analysis of different organs (prostate: clinical [CTV] and planned target volumes [PTV], rectum, bladder, femoral heads; H&N: gross tumor volume [GTV], CTV, spinal cord, brain stem, both parotids) was performed using predicted and planned dose distributions under 2%/2 mm tolerance and physical gamma passing rate was calculated. TCP and NTCP values were calculated for voxels with physical gamma indices (PGI) >1. We propose a new radiobiological gamma index (RGI) to quantify the radiobiological effects of TCP and NTCP and calculate radiobiological gamma passing rates. Results: The mean RGI gamma passing rates for prostate cases were significantly different compared with those of PGI (P<.03–.001). The mean RGI gamma passing rates for H&N cases (except for GTV) were significantly different compared with those of PGI (P<.001). Differences in gamma passing rates between PGI and RGI were due to dose differences between the planned and predicted dose distributions. Radiobiological gamma distribution was visualized to identify areas where the dose was radiobiologically important. Conclusions: RGI was proposed to integrate radiobiological effects into PGI. This index would assist physicians and medical physicists not only in physical evaluations of treatment delivery accuracy, but also in clinical evaluations of predicted dose distribution.

  13. Dependencies of lepton angular distribution coefficients on the transverse momentum and rapidity of Z bosons produced in p p collisions at the LHC

    NASA Astrophysics Data System (ADS)

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

    2017-09-01

    High precision data of lepton angular distributions for γ*/Z production in p p collisions at the LHC, covering broad ranges of dilepton transverse momenta (qT) and rapidity (y ), were recently reported. Strong qT dependencies were observed for several angular distribution coefficients, Ai, including A0-A4. Significant y dependencies were also found for the coefficients A1, A3 and A4, while A0 and A2 exhibit very weak rapidity dependence. Using an intuitive geometric picture, we show that the qT and y dependencies of the angular distributions coefficients can be well described.

  14. Angular and energy distribution of fragment ions in dissociative double photoionization of acetylene molecules at 39 eV

    SciTech Connect

    Alagia, M.; Callegari, C.; Richter, R.; Candori, P.; Falcinelli, S.; Vecchiocattivi, F.; Pirani, F.; Stranges, S.

    2012-05-28

    The two-body dissociation reactions of the dication, C{sub 2}H{sub 2}{sup 2+}, produced by 39.0 eV double photoionization of acetylene molecules, have been studied by coupling photoelectron-photoion-photoion coincidence and ion imaging techniques. The results provide the kinetic energy and angular distributions of product ions. The analysis of the results indicates that the dissociation leading to C{sub 2}H{sup +}+H{sup +} products occurs through a metastable dication with a lifetime of 108 {+-} 22 ns, and a kinetic energy release (KER) distribution exhibiting a maximum at {approx}4.3 eV with a full width at half maximum (FWHM) of about 60%. The reaction leading to CH{sub 2}{sup +}+C{sup +} occurs in a time shorter than the typical rotational period of the acetylene molecules (of the order of 10{sup -12} s). The KER distribution of product ions for this reaction, exhibits a maximum at {approx}4.5 eV with a FWHM of about 28%. The symmetric dissociation, leading to CH{sup +} + CH{sup +}, exhibits a KER distribution with a maximum at {approx}5.2 eV with a FWHM of 44%. For the first two reactions the angular distributions of ion products also indicate that the double photoionization of acetylene occurs when the neutral molecule is mainly oriented perpendicularly to the light polarization vector.

  15. Optimal angular dose distribution to acquire 3D and extra 2D images for digital breast tomosynthesis (DBT)

    NASA Astrophysics Data System (ADS)

    Park, Hye-Suk; Kim, Ye-Seul; Lee, Haeng-Hwa; Gang, Won-Suk; Kim, Hee-Joung; Choi, Young-Wook; Choi, JaeGu

    2015-08-01

    The purpose of this study is to determine the optimal non-uniform angular dose distribution to improve the quality of the 3D reconstructed images and to acquire extra 2D projection images. In this analysis, 7 acquisition sets were generated by using four different values for the number of projections (11, 15, 21, and 29) and total angular range (±14°, ±17.5°, ±21°, and ±24.5° ). For all acquisition sets, the zero-degree projection was used as the 2D image that was close to that of standard conventional mammography (CM). Exposures used were 50, 100, 150, and 200 mR for the zero-degree projection, and the remaining dose was distributed over the remaining projection angles. To quantitatively evaluate image quality, we computed the CNR (contrast-to-noise ratio) and the ASF (artifact spread function) for the same radiation dose. The results indicate that, for microcalcifications, acquisition sets with approximately 4 times higher exposure on the zero-degree projection than the average exposure for the remaining projection angles yielded higher CNR values and were 3% higher than the uniform distribution. However, very high dose concentrations toward the zero-degree projection may reduce the quality of the reconstructed images due to increasing noise in the peripheral views. The zero-degree projection of the non-uniform dose distribution offers a 2D image similar to that of standard CM, but with a significantly lower radiation dose. Therefore, we need to evaluate the diagnostic potential of extra 2D projection image when diagnose breast cancer by using 3D images with non-uniform angular dose distributions.

  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. 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.

  18. 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.

  19. 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.

  20. Interacting resonances in the F+H2 reaction revisited: complex terms, Riemann surfaces, and angular distributions.

    PubMed

    Sokolovski, D; Sen, S K; Aquilanti, V; Cavalli, S; De Fazio, D

    2007-02-28

    We study the effect of overlapping resonances on the angular distributions of the reaction F+H2(v=0,j=0)-->HF(v=2,j=0)+H in the collision energy range from 5 to 65 meV, i.e., under the reaction barrier. Reactive scattering calculations were performed using the hyperquantization algorithm on the potential energy surface of Stark and Werner [J. Chem. Phys. 104, 6515 (1996)]. The positions of the Regge and complex energy poles are obtained by Pade reconstruction of the scattering matrix element. The Sturmian theory is invoked to relate the Regge and complex energy terms. For two interacting resonances, a two-sheet Riemann surface is contracted and inverted. The semiclassical complex angular momentum analysis is used to decompose the scattering amplitude into the direct and resonance contributions.

  1. Relationships between log N-log S and celestial distribution of gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Nishimura, J.; Yamagami, T.

    1985-01-01

    The apparent conflict between log N-log S curve and isotropic celestial distribution of the gamma ray bursts is discussed. A possible selection effect due to the time profile of each burst is examined. It is shown that the contradiction is due to this selection effect of the gamma ray bursts.

  2. 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.

  3. 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.

  4. 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)

  5. 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.

  6. Monte Carlo models and analysis of galactic disk gamma-ray burst distributions

    NASA Technical Reports Server (NTRS)

    Hakkila, Jon

    1989-01-01

    Gamma-ray bursts are transient astronomical phenomena which have no quiescent counterparts in any region of the electromagnetic spectrum. Although temporal and spectral properties indicate that these events are likely energetic, their unknown spatial distribution complicates astrophysical interpretation. Monte Carlo samples of gamma-ray burst sources are created which belong to Galactic disk populations. Spatial analysis techniques are used to compare these samples to the observed distribution. From this, both quantitative and qualitative conclusions are drawn concerning allowed luminosity and spatial distributions of the actual sample. Although the Burst and Transient Source Experiment (BATSE) experiment on Gamma Ray Observatory (GRO) will significantly improve knowledge of the gamma-ray burst source spatial characteristics within only a few months of launch, the analysis techniques described herein will not be superceded. Rather, they may be used with BATSE results to obtain detailed information about both the luminosity and spatial distributions of the sources.

  7. Unfolding the fission prompt gamma-ray energy and multiplicity distribution measured by DANCE

    SciTech Connect

    Chyzh, A; Wu, C Y; Bredeweg, T; Couture, A; Jandel, M; Ullmann, J; Laptev, A

    2010-10-16

    The nearly energy independence of the {gamma}-ray efficiency and multiplicity response for the DANCE array, the unusual characteristic elucidated in our early technical report (LLNL-TR-452298), gives one a unique opportunity to derive the true prompt {gamma}-ray energy and multiplicity distribution in fission from the measurement. This unfolding procedure for the experimental data will be described in details and examples will be given to demonstrate the feasibility of reconstruction of the true distribution.

  8. In-Beam Gamma Spectroscopy

    NASA Astrophysics Data System (ADS)

    Mayank, .; Muralithar, S.; Sihotra, S.; Kumar, S.; Mehta, D.; Singh, R. P.; Rathore, Urvashi

    2016-09-01

    In-beam Gamma ray spectroscopic techniques have been studied using Indian National Gamma Array, IUAC which has a relative photo-peak efficiency of 5%. Data of a previous experiment where high angular momentum states of various nuclides were populated in the fusion-evaporation reaction 75As (28Si, 2p2n) at Elab = 120MeV. When gammas from populated nuclides are emanated during de-excitation, they are emitted with a certain angular distribution depending upon their multipolarity. Angular distribution of dipole and quadrupole transitions in 96Ru has been obtained from this data. The efficiency corrected angular distribution plot has been compared with the theoretical angular distribution function. The distribution co-efficients A2 and A4 for dipole and quadrupole were extracted from fitting the distribution with the equation: W (θ) = 1 +A2 *P2(cosθ) +A4 *P4(cosθ) . The Directional-correlation of Oriented Nuclei method was used to assign various other transitions as quadrupole or dipole. A DCO matrix between detectors at 1480 versus 900 was created using CANDLE. Intensities of transitions that have similar multipolarity as the gated transition would be equal in both the projected spectrums. In case of different multipolarity intensities would vary by a factor of 2. RDCO plots for 96Ru transitions have been obtained. To determine the nature of transitions whether magnetic or electric, a plot between polarization asymmetry (Δ) and DCO-ratio for transitions in 96Ru has been obtained.

  9. Two-dimensional resonances in Coulomb few body system and theory of electron energy and angular distribution

    SciTech Connect

    Ovchinnikov, S.Y.; Macek, J.H. |

    1994-12-31

    The two-dimensional resonances in the problem of two Coulomb centers are discussed. The ab initio calculation of electron energy and angular distributions of saddle-point and S-promotion electrons for ionization in proton-hydrogen atom collisions are presented. The calculation is based on an outgoing wave Sturmian expansion in the frequency domain. It goes beyond the usual Born-Oppenheimer separation of electron and nuclei motions and displays the ``{upsilon}/2`` peak and the continuum cusp, missing in previous theories.

  10. 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.

  11. 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.

  12. 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.

  13. Angular distribution of sputtered particles and surface morphology: the case of beryllium under a krypton beam at various incidences

    NASA Astrophysics Data System (ADS)

    Fournier, P.-G.; Nourtier, A.; Shulga, V. I.; Ait El Fqih, M.

    2005-04-01

    A beryllium target is bombarded with 5 keV krypton ions at incidence angles of 0° and 70°. The sputtered material is collected on a Mylar cylindrical foil surrounding the target, the foil is cut into pieces and the deposit on them is measured by inductively coupled plasma optical emission spectroscopy (ICP-OES). Experiment is combined with simulations using the computer code OKSANA. The method supplies accurate angular distributions of sputtered particles. The surface morphology is observed by scanning electron micrography. Depending on the incidence angle, sputtering forms craters and rippled areas or deep grooves. The resulting differences between simulations and experiment are explained qualitatively.

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

    NASA Astrophysics Data System (ADS)

    Mirazita, M.; Ronchetti, F.; Rossi, P.; de Sanctis, E.; Adams, G.; Ambrozewicz, P.; Anciant, E.; Anghinolfi, M.; Asavapibhop, B.; Audit, G.; Avakian, H.; Bagdasaryan, H.; Ball, J. P.; Barrow, S.; Battaglieri, M.; Beard, K.; Bektasoglu, M.; Bellis, M.; Benmouna, N.; Berman, B. L.; Bertozzi, W.; Bianchi, N.; Biselli, A. S.; Boiarinov, S.; Bonner, B. E.; Bouchigny, S.; Bradford, R.; Branford, D.; Briscoe, W. J.; Brooks, W. K.; Burkert, V. D.; Butuceanu, C.; Calarco, J. R.; Carman, D. S.; Carnahan, B.; Chen, S.; Cole, P. L.; Cords, D.; Corvisiero, P.; Crabb, D.; Crannell, H.; Cummings, J. P.; de Vita, R.; Degtyarenko, P. V.; Denizli, H.; Dennis, L.; Deppman, A.; Dharmawardane, K. V.; Dhuga, K. S.; Djalali, C.; Dodge, G. E.; Doughty, D.; Dragovitsch, P.; Dugger, M.; Dytman, S.; Dzyubak, O. P.; Egiyan, H.; Egiyan, K. S.; Elouadrhiri, L.; Empl, A.; Eugenio, P.; Fatemi, R.; Feuerbach, R. J.; Ficenec, J.; Forest, T. A.; Funsten, H.; Gai, M.; Gavalian, G.; Gilad, S.; Gilfoyle, G. P.; Giovanetti, K. L.; Gordon, C. I.; Griffioen, K.; Guidal, M.; Guillo, M.; Guo, L.; Gyurjyan, V.; Hadjidakis, C.; Hakobyan, R. S.; Hardie, J.; Heddle, D.; Hersman, F. W.; Hicks, K.; Hicks, R. S.; Holtrop, M.; Hu, J.; Hyde-Wright, C. E.; Ilieva, Y.; Ito, M. M.; Jenkins, D.; Joo, K.; Kellie, J. D.; Khandaker, M.; Kim, K. Y.; Kim, K.; Kim, W.; Klein, A.; Klein, F. J.; Klimenko, A. V.; Klusman, M.; Kossov, M.; Kramer, L. H.; Kuhn, J.; Kuhn, S. E.; Kuhn, J.; Lachniet, J.; Laget, J. M.; Lawrence, D.; Li, Ji; Lima, A. C.; Livingston, K.; Lukashin, K.; Manak, J. J.; Marchand, C.; McAleer, S.; McCarthy, J.; McNabb, J. W.; Mecking, B. A.; Mehrabyan, S.; Melone, J. J.; Mestayer, M. D.; Meyer, C. A.; Mikhailov, K.; Miskimen, R.; Mokeev, V.; Morand, L.; Morrow, S. A.; Muccifora, V.; Mueller, J.; Mutchler, G. S.; Napolitano, J.; Nasseripour, R.; Niccolai, S.; Niculescu, G.; Niculescu, I.; Niczyporuk, B. B.; Niyazov, R. A.; Nozar, M.; O'Brien, J. T.; O'Rielly, G. V.; Osipenko, M.; Ostrovidov, A.; Park, K.; Pasyuk, E.; Peterson, G.; Philips, S. A.; Pivnyuk, N.; Pocanic, D.; Pogorelko, O.; Polli, E.; Pozdniakov, S.; Preedom, B. M.; Price, J. W.; Prok, Y.; Protopopescu, D.; Qin, L. M.; Raue, B. A.; Riccardi, G.; Ricco, G.; Ripani, M.; Ritchie, B. G.; Rosner, G.; Rowntree, D.; Rubin, P. D.; Sabatié, F.; Salgado, C.; Santoro, J. P.; Sapunenko, V.; Schumacher, R. A.; Serov, V. S.; Sharabian, Y. G.; Shaw, J.; Simionatto, S.; Skabelin, A. V.; Smith, E. S.; Smith, L. C.; Sober, D. I.; Spraker, M.; Stavinsky, A.; Stepanyan, S.; Stokes, B.; Stoler, P.; Strakovsky, I. I.; Strauch, S.; Taiuti, M.; Taylor, S.; Tedeschi, D. J.; Thoma, U.; Thompson, R.; Tkabladze, A.; Todor, L.; Tur, C.; Ungaro, M.; Vineyard, M. F.; Vlassov, A. V.; Wang, K.; Weinstein, L. B.; Weller, H.; Weygand, D. P.; Whisnant, C. S.; Wolin, E.; Wood, M. H.; Yegneswaran, A.; Yun, J.; Zhang, B.; Zhou, Z.

    2004-07-01

    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° 160° . 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.

  15. 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.

  16. Neuronal model with distributed delay: analysis and simulation study for gamma distribution memory kernel.

    PubMed

    Karmeshu; Gupta, Varun; Kadambari, K V

    2011-06-01

    A single neuronal model incorporating distributed delay (memory)is proposed. The stochastic model has been formulated as a Stochastic Integro-Differential Equation (SIDE) which results in the underlying process being non-Markovian. A detailed analysis of the model when the distributed delay kernel has exponential form (weak delay) has been carried out. The selection of exponential kernel has enabled the transformation of the non-Markovian model to a Markovian model in an extended state space. For the study of First Passage Time (FPT) with exponential delay kernel, the model has been transformed to a system of coupled Stochastic Differential Equations (SDEs) in two-dimensional state space. Simulation studies of the SDEs provide insight into the effect of weak delay kernel on the Inter-Spike Interval(ISI) distribution. A measure based on Jensen-Shannon divergence is proposed which can be used to make a choice between two competing models viz. distributed delay model vis-á-vis LIF model. An interesting feature of the model is that the behavior of (CV(t))((ISI)) (Coefficient of Variation) of the ISI distribution with respect to memory kernel time constant parameter η reveals that neuron can switch from a bursting state to non-bursting state as the noise intensity parameter changes. The membrane potential exhibits decaying auto-correlation structure with or without damped oscillatory behavior depending on the choice of parameters. This behavior is in agreement with empirically observed pattern of spike count in a fixed time window. The power spectral density derived from the auto-correlation function is found to exhibit single and double peaks. The model is also examined for the case of strong delay with memory kernel having the form of Gamma distribution. In contrast to fast decay of damped oscillations of the ISI distribution for the model with weak delay kernel, the decay of damped oscillations is found to be slower for the model with strong delay kernel.

  17. Inferring the spatial and energy distribution of gamma-ray burst sources. 1: Methodology

    NASA Technical Reports Server (NTRS)

    Loredo, Thomas J.; Wasserman, Ira M.

    1995-01-01

    We describe Bayesian methods for analyzing the distribution of gamma-ray burst peak photon fluxes and directions. These methods fit the differential distribution, and have the following advantages over rival methods: (1) they do not destroy information by binning or averaging the data (as do, say, chi squared, the averaged value of V/V(sub max), and angular moment analyses); (2) they straightforwardly handle uncertainties in the measured quantities; (3) they analyze the strength and direction information jointly; (4) they use information available about nondetections; and (5) they automatically identify and account for biases and selection effects given a precise description of the experiment. In these methods, the most important information needed about the instrument threshold is not its value at the times of burst triggers, as is used in the average value of V/V(sub max) analyses, but rather the value of the threshold at times when no trigger occurred. We show that this information can be summarized as an average detection efficiency that is similar to the product of the exposure and efficiency reported in the First Burst and Transient Source Experiment (BATSE) Burst (1B) Catalog, but significantly different from it at low fluxes. We also quantify an important bias that results from estimating the peak flux by scanning the burst to find the peak number of counts in a window of specified duration, as was done for the 1B Catalog. When the duration of the peak of the light curve is longer than the window duration, a simple flux estimate based on the peak counts significantly overestimates the peak flux in a nonlinear fashion that distorts the shape of the log(N)-log(P) distribution. This distortion also corrupts analyses of the V/V(sub max) distribution that use ratios of counts above background to estimate V/V(sub max). The Bayesian calculation specifies how to account for this bias. Implementation of the Bayesian approach requires some changes in the way burst

  18. Distributed Attention Is Implemented through Theta-Rhythmic Gamma Modulation.

    PubMed

    Landau, Ayelet Nina; Schreyer, Helene Marianne; van Pelt, Stan; Fries, Pascal

    2015-08-31

    When subjects monitor a single location, visual target detection depends on the pre-target phase of an ∼8 Hz brain rhythm. When multiple locations are monitored, performance decrements suggest a division of the 8 Hz rhythm over the number of locations, indicating that different locations are sequentially sampled. Indeed, when subjects monitor two locations, performance benefits alternate at a 4 Hz rhythm. These performance alternations were revealed after a reset of attention to one location. Although resets are common and important events for attention, it is unknown whether, in the absence of resets, ongoing attention samples stimuli in alternation. Here, we examined whether spatially specific attentional sampling can be revealed by ongoing pre-target brain rhythms. Visually induced gamma-band activity plays a role in spatial attention. Therefore, we hypothesized that performance on two simultaneously monitored stimuli can be predicted by a 4 Hz modulation of gamma-band activity. Brain rhythms were assessed with magnetoencephalography (MEG) while subjects monitored bilateral grating stimuli for a unilateral target event. The corresponding contralateral gamma-band responses were subtracted from each other to isolate spatially selective, target-related fluctuations. The resulting lateralized gamma-band activity (LGA) showed opposite pre-target 4 Hz phases for detected versus missed targets. The 4 Hz phase of pre-target LGA accounted for a 14.5% modulation in performance. These findings suggest that spatial attention is a theta-rhythmic sampling process that is continuously ongoing, with each sampling cycle being implemented through gamma-band synchrony.

  19. A model of energy and angular distributions of fluxes to the substrate and resulting surface topology for plasma etching systems

    NASA Astrophysics Data System (ADS)

    Hoekstra, Robert John

    Plasma etching using high-density plasma (HDP) reactors is becoming predominant in the semiconductor fabrication industry due to its capability to produce highly anisotropic features at current and future linewidths (0.5 to 0.17 μm). The Computational Optical and Discharge Physics Group (CODPG) has developed a modularized computational simulation, the Hybrid Plasma Equipment Model (HPEM), to examine these systems. The two offline modules developed, the Plasma Chemistry Monte Carlo Model (PCMCM) and the Monte Carlo Feature Profile Model (MC-FPM), focus on the effect of the plasma on the wafer surface. Using the output from the main plasma simulation, the PCMCM self-consistently determines the energy and angular distributions of all plasma species at the wafer. This distribution information can then be used by the MC-FPM to determine the time evolution of etch features on the wafer based on an energy- and angular- dependent surface chemistry. This chemistry has been developed using experimental results by other researchers as described in this paper. An important process in semiconductor manufacturing is the etching of silicon and polysilicon for device fabrication. Chlorine-based chemistries are commonly used in industry today due to the capability of highly anisotropic feature etching allowing the necessary submicron feature production. In current HDP reactors, ``microtrench'' formation, sidewall slope, and charging effects play an important role in device performance. The MC-FPM has been used to examine the mechanisms, such as specular reflection and energy and angular dependence of etch yield, involved in the shaping of the etch feature. Parameterization of these mechanisms and comparison to experiment have allowed ``cradle- to-grave'' (reactor parameters to feature shape) predictive capability with the HPEM, PCMCM, and MC-FPM coupled models for HDP etching processes.

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. 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).

  7. Molecular frame photoelectron angular distributions for core ionization of ethane, carbon tetrafluoride and 1,1-difluoroethylene

    SciTech Connect

    Menssen, A.; Trevisan, C. S.; Schöffler, M. S.; Jahnke, T.; Bocharova, I.; Sturm, F.; Gehrken, N.; Gaire, B.; Gassert, H.; Zeller, S.; Voigtsberger, J.; Kuhlins, A.; Trinter, F.; Gatton, A.; Sartor, J.; Reedy, D.; Nook, C.; Berry, B.; Zohrabi, M.; Kalinin, A.; Ben-Itzhak, I.; Belkacem, A.; Dörner, R.; Weber, T.; Landers, A. L.; Rescigno, T. N.; McCurdy, C. W.; Williams, J. B.

    2016-02-15

    Molecular frame photoelectron angular distributions (MFPADs) are measured in this paper in electron–ion momentum imaging experiments and compared with complex Kohn variational calculations for carbon K-shell ionization of carbon tetrafluoride (CF4), ethane (C2H6) and 1,1-difluoroethylene (C2H2F2). While in ethane the polarization averaged MFPADs show a tendency at low energies for the photoelectron to be emitted in the directions of the bonds, the opposite effect is seen in CF4. A combination of these behaviors is seen in difluoroethylene where ionization from the two carbons can be distinguished experimentally because of their different K-shell ionization potentials. Excellent agreement is found between experiment and simple static-exchange or coupled two-channel theoretical calculations. Finally, however, simple electrostatics do not provide an adequate explanation of the suggestively simple angular distributions at low electron ejection energies.

  8. 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.

  9. Photoelectron angular distributions for states of any mixed character: An experiment-friendly model for atomic, molecular, and cluster anions

    SciTech Connect

    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{sup −} 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.

  10. 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.

  11. Charm hadroproduction cross-section up to 100 TeV from measurements of the cosmic-ray muon angular distribution Results of the Mount Blanc experiment

    NASA Astrophysics Data System (ADS)

    Castellina, A.; Dettorre Piazzoli, B.; Mannocchi, G.; Picchi, P.; Vernetto, S.; Bilokon, H.

    1985-02-01

    Accurate calculations of the angular distributions of underground conventional and prompt muons have been performed. The dependence of the angular enhancement functions on the primary spectrum, cross-sections, inclusive distributions, K/pi ratio and survival probability have been studied and found to be negligible. The results have been used to interpret the data from the Mont Blanc experiment in the depth range 4200-5800 hg/sq cm. Since the measurements extend over a limited angular range (lesser than 60 deg) the ratio between the flux of prompt to conventional muons of higher energy (greater than 1 TeV) is obtained with large associated statistical errors. In order to obtain the charm production cross-section in the energy region 50-100 TeV, accurate measurements over a very large angular range (greater than 70 deg) at depths higher than 5000 hg/sq cm are required.

  12. Distribution of cosmic gamma rays in the galactic anticenter region as observed by SAS-2

    NASA Technical Reports Server (NTRS)

    Kniffen, D. A.; Fichtel, C. E.; Hartman, R. C.; Thompson, D. J.; Ozel, M. E.; Tumer, T.; Bignami, G. F.; Ogelman, H.

    1975-01-01

    The high energy (above 35 MeV) gamma ray telescope flown on the second Small Astronomy Satellite has collected over one thousand gamma rays from the direction of the galactic anticenter. In addition to the diffuse galactic emission the distribution indicates a strong pulsed contribution from the Crab nebula with the same period and phase as the NP0532 pulsar. There also seems to be an excess in the direction of (gal. long. ? 195 deg; gal. lat ? +5 deg) where there is a region containing old supernova remnants. Search for gamma ray pulsations from other pulsars in the region do not show any statistically significant signal. The general intensity distribution of the gamma rays away from the plane appear to be similar to nonthermal radio emission brightness contours.

  13. 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.

  14. 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

  15. 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.

  16. Development of MCNPX-ESUT computer code for simulation of neutron/gamma pulse height distribution

    NASA Astrophysics Data System (ADS)

    Abolfazl Hosseini, Seyed; Vosoughi, Naser; Zangian, Mehdi

    2015-05-01

    In this paper, the development of the MCNPX-ESUT (MCNPX-Energy Engineering of Sharif University of Technology) computer code for simulation of neutron/gamma pulse height distribution is reported. Since liquid organic scintillators like NE-213 are well suited and routinely used for spectrometry in mixed neutron/gamma fields, this type of detectors is selected for simulation in the present study. The proposed algorithm for simulation includes four main steps. The first step is the modeling of the neutron/gamma particle transport and their interactions with the materials in the environment and detector volume. In the second step, the number of scintillation photons due to charged particles such as electrons, alphas, protons and carbon nuclei in the scintillator material is calculated. In the third step, the transport of scintillation photons in the scintillator and lightguide is simulated. Finally, the resolution corresponding to the experiment is considered in the last step of the simulation. Unlike the similar computer codes like SCINFUL, NRESP7 and PHRESP, the developed computer code is applicable to both neutron and gamma sources. Hence, the discrimination of neutron and gamma in the mixed fields may be performed using the MCNPX-ESUT computer code. The main feature of MCNPX-ESUT computer code is that the neutron/gamma pulse height simulation may be performed without needing any sort of post processing. In the present study, the pulse height distributions due to a monoenergetic neutron/gamma source in NE-213 detector using MCNPX-ESUT computer code is simulated. The simulated neutron pulse height distributions are validated through comparing with experimental data (Gohil et al. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 664 (2012) 304-309.) and the results obtained from similar computer codes like SCINFUL, NRESP7 and Geant4. The simulated gamma pulse height distribution for a 137Cs

  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. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Simulation of generation of bremsstrahlung gamma quanta upon irradiation of thin metal films by ultra-intense femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Andreev, Stepan N.; Garanin, Sergey G.; Rukhadze, Anri A.; Tarakanov, V. P.; Yakutov, B. P.

    2010-06-01

    We report the results of simulations of generation of bremsstrahlung gamma quanta upon irradiation of a thin-film metal target by ultra-intense femtosecond laser pulses. It is shown by the example of a thin gold target that the mean electron energy is twenty five times higher than the mean energy of gamma quanta generated by them. A simple approximating formula is proposed, which establishes a one-to-one relation between these quantities. The angular distributions of electrons and gamma quanta are studied. It is shown that only the angular distribution of high-energy gamma quanta repeats the angular distribution of the electrons leaving the target.

  19. pH-dependent structural change of reduced spinach plastocyanin studied by perturbed angular correlation of gamma-rays and dynamic light scattering.

    PubMed

    Sas, Klára Nárcisz; Haldrup, Anna; Hemmingsen, Lars; Danielsen, Eva; Øgendal, Lars Holm

    2006-06-01

    In this study the pH-dependent structural changes of reduced spinach plastocyanin were investigated using perturbed angular correlation (PAC) of gamma-rays and dynamic light scattering (DLS). PAC data of Ag-substituted plastocyanin indicated that the coordinating ligands are two histidine residues (His37, His87) and a cysteine residue (Cys84) in a planar configuration, whereas the methionine (Met92) found perpendicular to this plane is not a coordinating ligand at neutral pH. Two slightly different conformations with differences in the Cys-metal ion-His angles could be observed with PAC spectroscopy. At pH 5.3 a third coordination geometry appears which can be explained as the absence of the His87 residue and the coordination of Met92 as a ligand. With DLS the aggregation of reduced plastocyanin could be observed below pH 5.3, indicating that not only the metal binding site but also the aggregation properties of the protein change upon pH reduction. Both the structural changes at the metal binding site and the aggregation are shown to be reversible. These results support the hypothesis that the pH of the thylakoid lumen has to remain moderate during steady-state photosynthesis and indicate that low pH induced aggregation of plastocyanin might serve as a regulatory switch for photosynthesis.

  20. Angular distribution of particle fluxes in rotating systems. [application to plasmas in Jupiter magnetosphere

    NASA Technical Reports Server (NTRS)

    Northrop, T. G.

    1976-01-01

    Charged-particle pitch-angle distributions at one point on a magnetic drift surface in a rapidly rotating axisymmetric mirroring system (such as Jupiter's magnetosphere would be in the absence of the 10-deg dipole tilt) are related to those at another point by Liouville's theorem. If the distribution function in the rotating frame is gyrotropic; i.e., if it is independent of the phase angle of the gyration, it is gyrotropic at all points on that drift surface. Examples are given of 'pancake', 'dumbbell', and isotropic distributions when they are observed from the nonrotating frame at different points on a drift surface.

  1. 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.

  2. 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.

  3. Angular distributions for the inelastic scattering of NO(X2Π ) with O2(X3Σg-)

    NASA Astrophysics Data System (ADS)

    Brouard, M.; Gordon, S. D. S.; Nichols, B.; Squires, E.; Walpole, V.; Aoiz, F. J.; Stolte, S.

    2017-05-01

    The inelastic scattering of NO(X2Π ) by O2(X3Σg-) was studied at a mean collision energy of 550 cm-1 using velocity-map ion imaging. The initial quantum state of the NO(X2Π , v = 0, j = 0.5, Ω =0.5 , 𝜖 = -1 , f) molecule was selected using a hexapole electric field, and specific Λ-doublet levels of scattered NO were probed using (1 +1' ) resonantly enhanced multiphoton ionization. A modified "onion-peeling" algorithm was employed to extract angular scattering information from the series of "pancaked," nested Newton spheres arising as a consequence of the rotational excitation of the molecular oxygen collision partner. The extracted differential cross sections for NO(X) f →f and f →e Λ-doublet resolved, spin-orbit conserving transitions, partially resolved in the oxygen co-product rotational quantum state, are reported, along with O2 fragment pair-correlated rotational state population. The inelastic scattering of NO with O2 is shown to share many similarities with the scattering of NO(X) with the rare gases. However, subtle differences in the angular distributions between the two collision partners are observed.

  4. 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.

  5. 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).

  6. FUNDAMENTAL AREAS OF PHENOMENOLOGY (INCLUDING APPLICATIONS): Effects of Turbulent Aberrations on Probability Distribution of Orbital Angular Momentum for Optical Communication

    NASA Astrophysics Data System (ADS)

    Zhang, Yi-Xin; Cang, Ji

    2009-07-01

    Effects of atmospheric turbulence tilt, defocus, astigmatism and coma aberrations on the orbital angular momentum measurement probability of photons propagating in weak turbulent regime are modeled with Rytov approximation. By considering the resulting wave as a superposition of angular momentum eigenstates, the orbital angular momentum measurement probabilities of the transmitted digit are presented. Our results show that the effect of turbulent tilt aberration on the orbital angular momentum measurement probabilities of photons is the maximum among these four kinds of aberrations. As the aberration order increases, the effects of turbulence aberrations on the measurement probabilities of orbital angular momentum generally decrease, whereas the effect of turbulence defocus can be ignored. For tilt aberration, as the difference between the measured orbital angular momentum and the original orbital angular momentum increases, the orbital angular momentum measurement probability decreases.

  7. 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.

  8. 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.

  9. 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.

  10. Angular distribution of [ital K] Auger electrons ejected by highly charged ions interacting with an Al(111) surface

    SciTech Connect

    Koehrbrueck, R.; Grether, M.; Spieler, A.; Stolterfoht, N. ); Page, R.; Saal, A.; Bleck-Neuhaus, J. )

    1994-08-01

    Secondary electron spectra of the H-like Ne[sup 9+] ion incident with impact energies of 135 eV up to 90 keV on a solid Al(111) surface were measured. The dependence of the [ital K] Auger electron yield on the angle of observation is studied in detail. It is found to be cosine like in case of the 90-keV Ne[sup 9+] ions and to be more and more isotropic at lower ion energies although a clear anisotropy remains. Information about the rates of the filling of the [ital L] and [ital K] shells inside the solid is obtained from a comparison of the measured angular distributions with the calculation of a two-step model for the successive filling of the [ital L] and [ital K] shells. The data show clear evidence for Auger electron emission from below the surface for ion energies as low as 135 eV.

  11. 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.

  12. Precision analysis of electron energy spectrum and angular distribution of neutron β- decay with polarized neutron and electron

    NASA Astrophysics Data System (ADS)

    Ivanov, A. N.; Höllwieser, R.; Troitskaya, N. I.; Wellenzohn, M.; Berdnikov, Ya. A.

    2017-05-01

    We give a precision analysis of the correlation coefficients of the electron energy spectrum and angular distribution of the β- decay and radiative β- decay of the neutron with polarized neutron and electron to order 10-3. The calculation of correlation coefficients is carried out within the standard model, with contributions of order 10-3 caused by the weak magnetism and proton recoil taken to next-to-leading order in the large proton mass expansion, and with radiative corrections of order α /π ˜10-3 calculated to leading order in the large proton mass expansion. The obtained results can be used for the planning of experiments on the search for contributions of order 10-4 of interactions beyond the standard model.

  13. Fragment angular distribution in one- and two-color photodissociation by strong laser fields

    SciTech Connect

    Charron, E.; Giusti-Suzor, A.; Mies, F.H. Laboratoire de Chimie Physique, 11 rue Pierre et Marie Curie, 75231 Paris National Institute of Standards and Technology, Gaithersburg, Maryland 20899 )

    1994-02-01

    We present calculations for H[sub 2][sup +] photodissociation in intense short laser pulses where molecular rotation is fully included, resulting in the experimentally observed alignment of the photofragments. In addition, we show that by using a coherent superposition (phase-locked) of a fundamental radiation and its second harmonic, [ital a] [ital strong] [ital asymmetry] between the forwards and backwards proton distribution can be observed. Both the total dissociation probability and the asymmetry of the ion distribution are sensitive to the relative phase of the two colors and thus subject to coherent control.

  14. Time Evolving Fission Chain Theory and Fast Neutron and Gamma-Ray Counting Distributions

    SciTech Connect

    Kim, K. S.; Nakae, L. F.; Prasad, M. K.; Snyderman, N. J.; Verbeke, J. M.

    2015-11-01

    Here, we solve a simple theoretical model of time evolving fission chains due to Feynman that generalizes and asymptotically approaches the point model theory. The point model theory has been used to analyze thermal neutron counting data. This extension of the theory underlies fast counting data for both neutrons and gamma rays from metal systems. Fast neutron and gamma-ray counting is now possible using liquid scintillator arrays with nanosecond time resolution. For individual fission chains, the differential equations describing three correlated probability distributions are solved: the time-dependent internal neutron population, accumulation of fissions in time, and accumulation of leaked neutrons in time. Explicit analytic formulas are given for correlated moments of the time evolving chain populations. The equations for random time gate fast neutron and gamma-ray counting distributions, due to randomly initiated chains, are presented. Correlated moment equations are given for both random time gate and triggered time gate counting. There are explicit formulas for all correlated moments are given up to triple order, for all combinations of correlated fast neutrons and gamma rays. The nonlinear differential equations for probabilities for time dependent fission chain populations have a remarkably simple Monte Carlo realization. A Monte Carlo code was developed for this theory and is shown to statistically realize the solutions to the fission chain theory probability distributions. Combined with random initiation of chains and detection of external quanta, the Monte Carlo code generates time tagged data for neutron and gamma-ray counting and from these data the counting distributions.

  15. Reduction in T gamma delta cell numbers and alteration in subset distribution in systemic lupus erythematosus.

    PubMed Central

    Lunardi, C; Marguerie, C; Bowness, P; Walport, M J; So, A K

    1991-01-01

    We have studied the distribution of T gamma delta cells in the peripheral blood of 35 patients with systemic lupus erythematosus (SLE) and 36 age-matched controls. The monoclonal antibodies A13, BB3 and Ti gamma A, which are specific for the V delta 1, V delta 2 and V delta 9 gene products respectively, were used to define T gamma delta cell subsets. A significantly lower frequency of T gamma delta cells was found in peripheral blood lymphocytes of SLE patients compared with normal subjects (3.2% versus 5.9%). There was a marked reduction in the V delta 2+ subset of T gamma delta cells, which resulted in a reversal of the ratio of V delta 2+/V delta 1+ cells from 4.34 to 0.56. No correlation was found with either clinical or laboratory measures of disease activity. These results suggest that the observed changed in T gamma delta subset distribution are related to the SLE itself, and not secondary to changes in disease activity. PMID:1834377

  16. 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}.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. Utilizing angular distributions to measure the spin imparted to the continuum region of Gd nuclei by light-ion transfer reactions

    NASA Astrophysics Data System (ADS)

    Ross, T. J.; Beausang, C. W.; Hughes, R. O.; Allmond, J. M.; Angell, C. T.; Basunia, M. S.; Bleuel, D. L.; Burke, J. T.; Casperson, R. J.; Escher, J. E.; Fallon, P.; Hatarik, R.; Munson, J.; Paschalis, S.; Petri, M.; Phair, L.; Ressler, J. J.; Scielzo, N. D.; Thompson, I. J.

    2012-10-01

    Historically it has proven extremely difficult to probe the properties of low-spin highly-excited states far above the yrast line in the bound quasi-continuum. We present the first measurement of the initial spin distribution of this region, following (p,d) and (p,t) reactions on ^154Gd and ^158Gd targets. The 25 MeV proton beam was provided by the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory. A silicon telescope array, STARS, was used to detect light ions. We find that the spin transferred increases with excitation energy. Between 3 and 8 MeV, assuming a single dominant angular momentum transfer component, the measured angular distribution for the (p,d) reactions are well reproduced by DWBA calculations for δL=4 transfer, whilst the (p,t) reactions are better characterized by δL=5. A weighted combination of DWBA calculations, agrees excellently with experimental angular distributions.

  2. Shaped scintillation detector systems for measurements of gamma ray flux anisotropy

    NASA Technical Reports Server (NTRS)

    Trombka, J. I.; Vette, J. I.; Stecker, F. W.; Eller, E. L.; Wildes, W. T.

    1973-01-01

    The detection efficiencies of cylindrical detectors for various gamma ray photon angular distributions were studied in the energy range from .10 Mev to 15 Mev. These studies indicate that simple detector systems on small satellites can be used to measure flux anisotropy of cosmic gamma rays and the angular distribution of albedo gamma rays produced in planetary atmospheres. The results indicate that flat cylindrical detectors are most suitable for measuring flux anisotropy because of their angular response function. A general method for calculating detection efficiencies for such detectors is presented.

  3. Code CUGEL: A code to unfold Ge(Li) spectrometer polyenergetic gamma photon experimental distributions

    NASA Technical Reports Server (NTRS)

    Steyn, J. J.; Born, U.

    1970-01-01

    A FORTRAN code was developed for the Univac 1108 digital computer to unfold lithium-drifted germanium semiconductor spectrometers, polyenergetic gamma photon experimental distributions. It was designed to analyze the combination continuous and monoenergetic gamma radiation field of radioisotope volumetric sources. The code generates the detector system response matrix function and applies it to monoenergetic spectral components discretely and to the continuum iteratively. It corrects for system drift, source decay, background, and detection efficiency. Results are presented in digital form for differential and integrated photon number and energy distributions, and for exposure dose.

  4. 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.

  5. A gamma dose distribution evaluation technique using the k-d tree for nearest neighbor searching.

    PubMed

    Yuan, Jiankui; Chen, Weimin

    2010-09-01

    The authors propose an algorithm based on the k-d tree for nearest neighbor searching to improve the gamma calculation time for 2D and 3D dose distributions. The gamma calculation method has been widely used for comparisons of dose distributions in clinical treatment plans and quality assurances. By specifying the acceptable dose and distance-to-agreement criteria, the method provides quantitative measurement of the agreement between the reference and evaluation dose distributions. The gamma value indicates the acceptability. In regions where gamma < or = 1, the predefined criterion is satisfied and thus the agreement is acceptable; otherwise, the agreement fails. Although the concept of the method is not complicated and a quick naïve implementation is straightforward, an efficient and robust implementation is not trivial. Recent algorithms based on exhaustive searching within a maximum radius, the geometric Euclidean distance, and the table lookup method have been proposed to improve the computational time for multidimensional dose distributions. Motivated by the fact that the least searching time for finding a nearest neighbor can be an O (log N) operation with a k-d tree, where N is the total number of the dose points, the authors propose an algorithm based on the k-d tree for the gamma evaluation in this work. In the experiment, the authors found that the average k-d tree construction time per reference point is O (log N), while the nearest neighbor searching time per evaluation point is proportional to O (N(1/k), where k is between 2 and 3 for two-dimensional and three-dimensional dose distributions, respectively. Comparing with other algorithms such as exhaustive search and sorted list O (N), the k-d tree algorithm for gamma evaluation is much more efficient.

  6. Angular distribution of polarized spontaneous emissions and its effect on light extraction behavior in InGaN-based light emitting diodes

    NASA Astrophysics Data System (ADS)

    Yuan, Gangcheng; Chen, Xinjuan; Yu, Tongjun; Lu, Huimin; Chen, Zhizhong; Kang, Xiangning; Wu, Jiejun; Zhang, Guoyi

    2014-03-01

    Angular intensity distributions of differently polarized light sources in multiple quantum wells (MQWs) and their effects on extraction behavior of spontaneous emission from light emitting diode (LED) chips have been studied. Theoretical calculation based on k.p approximation, ray tracing simulation and angular electroluminescence measurement were applied in this work. It is found that the electron-hole recombination in the InGaN MQWs produces a spherical distribution of an s-polarized source and a dumbbell-shaped p-polarized source. Light rays from different polarized sources experience different extraction processes, determining the polarization degree of electro-luminescence and extraction efficiency of LEDs.

  7. Angular distribution of polarized spontaneous emissions and its effect on light extraction behavior in InGaN-based light emitting diodes

    SciTech Connect

    Yuan, Gangcheng; Chen, Xinjuan; Yu, Tongjun Lu, Huimin; Chen, Zhizhong; Kang, Xiangning; Wu, Jiejun; Zhang, Guoyi

    2014-03-07

    Angular intensity distributions of differently polarized light sources in multiple quantum wells (MQWs) and their effects on extraction behavior of spontaneous emission from light emitting diode (LED) chips have been studied. Theoretical calculation based on k·p approximation, ray tracing simulation and angular electroluminescence measurement were applied in this work. It is found that the electron-hole recombination in the InGaN MQWs produces a spherical distribution of an s-polarized source and a dumbbell-shaped p-polarized source. Light rays from different polarized sources experience different extraction processes, determining the polarization degree of electro-luminescence and extraction efficiency of LEDs.

  8. Use of the gamma distribution to represent monthly rainfall in Africa for drought monitoring applications

    USGS Publications Warehouse

    Husak, Gregory J.; Michaelsen, Joel C.; Funk, Christopher C.

    2007-01-01

    Evaluating a range of scenarios that accurately reflect precipitation variability is critical for water resource applications. Inputs to these applications can be provided using location- and interval-specific probability distributions. These distributions make it possible to estimate the likelihood of rainfall being within a specified range. In this paper, we demonstrate the feasibility of fitting cell-by-cell probability distributions to grids of monthly interpolated, continent-wide data. Future work will then detail applications of these grids to improved satellite-remote sensing of drought and interpretations of probabilistic climate outlook forum forecasts. The gamma distribution is well suited to these applications because it is fairly familiar to African scientists, and capable of representing a variety of distribution shapes. This study tests the goodness-of-fit using the Kolmogorov–Smirnov (KS) test, and compares these results against another distribution commonly used in rainfall events, the Weibull. The gamma distribution is suitable for roughly 98% of the locations over all months. The techniques and results presented in this study provide a foundation for use of the gamma distribution to generate drivers for various rain-related models. These models are used as decision support tools for the management of water and agricultural resources as well as food reserves by providing decision makers with ways to evaluate the likelihood of various rainfall accumulations and assess different scenarios in Africa. 

  9. Probe diagnostics of electron distributions in plasma with spatial and angular resolution

    SciTech Connect

    Demidov, V. I.; Kudryavtsev, A. A.

    2014-09-15

    This paper discusses the spatial resolution that is required to study inhomogeneous, low-temperature plasmas and is based on a review of low-temperature plasma electron kinetics and methods for probe measurements of electron energy distribution functions (EEDFs). It is stated that EEDFs can be extracted from probe measurements by applying an appropriate probe theory. The Druyvesteyn formula is most commonly used for this extraction and has been used in numerous publications, but more general theory can be used for a wider range of gas pressures. It is demonstrated that the Druyvesteyn formula can be obtained from the general theory as a limiting case. This paper justifies the application of wall probes in plasma studies of an energetic part of EEDFs. This justification is made for an idealized probe. We briefly review the methods for studying anisotropic plasmas and their usefulness in plasma research. It is demonstrated that to determine anisotropic electron energy distribution functions, a planar, one-sided probe is most convenient.

  10. Size distributions of air showers accompanied with high energy gamma ray bundles observed at Mt. Chacaltaya

    NASA Technical Reports Server (NTRS)

    Matano, T.; Machida, M.; Tsuchima, I.; Kawasumi, N.; Honda, K.; Hashimoto, K.; Martinic, N.; Zapata, J.; Navia, C. E.; Aquirre, C.

    1985-01-01

    Size distributions of air showers accompanied with bundle of high energy gamma rays and/or large size bursts under emulsion chambers, to study the composition of primary cosmic rays and also characteristics of high energy nuclear interaction. Air showers initiated by particles with a large cross section of interaction may develop from narrow region of the atmosphere near the top. Starting levels of air showers by particles with smaller cross section fluctuate in wider region of the atmosphere. Air showers of extremely small size accompanied with bundle of gamma rays may be ones initiated by protons at lower level after penetrating deep atmosphere without interaction. It is determined that the relative size distribution according to the total energy of bundle of gamma rays and the total burst size observed under 15 cm lead absorber.

  11. 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.

  12. 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.

  13. Angular distribution of Rh atoms desorbed from ion-bombarded Rh l brace 100 r brace : Effect of local environment

    SciTech Connect

    Maboudian, R.; Postawa, Z.; El-Maazawi, M.; Garrison, B.J.; Winograd, N. )

    1990-10-15

    Energy-resolved angular distributions of Rh atoms desorbed by 5 keV Ar-ion bombardment of the Rh{l brace}100{r brace} surface are measured with use of a multiphoton resonance ionization technique. The results are shown to be in good agreement with molecular-dynamics simulations of the ion-impact event using the same interaction potential optimized previously to describe desorption from Rh{l brace}111{r brace}. In addition, by analyzing contour plots of the surface potential energy, the trend in the experimental results for Rh{l brace}100{r brace} and those previously published for Rh{l brace}111{r brace} are well explained. Based on this analysis, it is concluded that the peak in the polar-angle distribution of neutral particles desorbed from ion-bombarded single crystals is mainly determined by the relative positions of surface atoms which influence the trajectory of an exiting particle via channeling and blocking. Moreover, the anisotropy of the momentum imparted to the surface atoms in the last collision leads to an enhancement of ejection along certain crystallographic directions.

  14. SPATIAL AND SPECTRAL MODELING OF THE GAMMA-RAY DISTRIBUTION IN THE LARGE MAGELLANIC CLOUD

    SciTech Connect

    Foreman, Gary; Chu, You-Hua; Gruendl, Robert; Fields, Brian; Ricker, Paul; Hughes, Annie

    2015-07-20

    We perform spatial and spectral analyses of the LMC gamma-ray emission collected over 66 months by the Fermi Gamma-ray Space Telescope. In our spatial analysis, we model the LMC cosmic-ray distribution and gamma-ray production using observed maps of the LMC interstellar medium, star formation history, interstellar radiation field, and synchrotron emission. We use bootstrapping of the data to quantify the robustness of spatial model performance. We model the LMC gamma-ray spectrum using fitting functions derived from the physics of π{sup 0} decay, Bremsstrahlung, and inverse Compton scattering. We find the integrated gamma-ray flux of the LMC from 200 MeV to 20 GeV to be 1.37 ± 0.02 × 10{sup −7} ph cm{sup −2} s{sup −1}, of which we attribute about 6% to inverse Compton scattering and 44% to Bremsstrahlung. From our work, we conclude that the spectral index of the LMC cosmic-ray proton population is 2.4 ± 0.2, and we find that cosmic-ray energy loss through gamma-ray production is concentrated within a few 100 pc of acceleration sites. Assuming cosmic-ray energy equipartition with magnetic fields, we estimate LMC cosmic rays encounter an average magnetic field strength ∼3 μG.

  15. Measurement of W boson angular distributions in events with high transverse momentum jets at s=8 TeV using the ATLAS detector

    DOE PAGES

    Aaboud, M.; Aad, G.; Abbott, B.; ...

    2016-12-06

    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 termsmore » of the absolute cross-section and the angular distributions of the muon from the leptonic W decay.« less

  16. 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. 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R.; Suzuki, S.; Svatos, M.; Swiatlowski, M.; Sykora, I.; Sykora, T.; Ta, D.; Taccini, C.; Tackmann, K.; Taenzer, J.; Taffard, A.; Tafirout, R.; Taiblum, N.; Takai, H.; Takashima, R.; Takeshita, T.; Takubo, Y.; Talby, M.; Talyshev, A. A.; Tan, K. G.; Tanaka, J.; Tanaka, M.; Tanaka, R.; Tanaka, S.; Tanioka, R.; Tannenwald, B. B.; Tapia Araya, S.; Tapprogge, S.; Tarem, S.; Tartarelli, G. F.; Tas, P.; Tasevsky, M.; Tashiro, T.; Tassi, E.; Tavares Delgado, A.; Tayalati, Y.; Taylor, A. C.; Taylor, G. N.; Taylor, P. T. E.; Taylor, W.; Teischinger, F. A.; Teixeira-Dias, P.; Temming, K. K.; Temple, D.; Ten Kate, H.; Teng, P. K.; Teoh, J. J.; Tepel, F.; Terada, S.; Terashi, K.; Terron, J.; Terzo, S.; Testa, M.; Teuscher, R. J.; Theveneaux-Pelzer, T.; Thomas, J. P.; Thomas-Wilsker, J.; Thompson, P. D.; Thompson, A. S.; Thomsen, L. A.; Thomson, E.; Tibbetts, M. J.; Ticse Torres, R. E.; Tikhomirov, V. O.; Tikhonov, Yu. A.; Timoshenko, S.; Tipton, P.; Tisserant, S.; Todome, K.; Todorov, T.; Todorova-Nova, S.; Tojo, J.; Tokár, S.; Tokushuku, K.; Tolley, E.; Tomlinson, L.; Tomoto, M.; Tompkins, L.; Toms, K.; Tong, B.; Tornambe, P.; Torrence, E.; Torres, H.; Torró Pastor, E.; Toth, J.; Touchard, F.; Tovey, D. R.; Trefzger, T.; Tricoli, A.; Trigger, I. M.; Trincaz-Duvoid, S.; Tripiana, M. F.; Trischuk, W.; Trocmé, B.; Trofymov, A.; Troncon, C.; Trottier-McDonald, M.; Trovatelli, M.; Truong, L.; Trzebinski, M.; Trzupek, A.; Tseng, J. C.-L.; Tsiareshka, P. V.; Tsipolitis, G.; Tsirintanis, N.; Tsiskaridze, S.; Tsiskaridze, V.; Tskhadadze, E. G.; Tsui, K. M.; Tsukerman, I. I.; Tsulaia, V.; Tsuno, S.; Tsybychev, D.; Tu, Y.; Tudorache, A.; Tudorache, V.; Tuna, A. N.; Tupputi, S. A.; Turchikhin, S.; Turecek, D.; Turgeman, D.; Turra, R.; Tuts, P. M.; Tyndel, M.; Ucchielli, G.; Ueda, I.; Ughetto, M.; Ukegawa, F.; Unal, G.; Undrus, A.; Unel, G.; Ungaro, F. C.; Unno, Y.; Unverdorben, C.; Urban, J.; Urquijo, P.; Urrejola, P.; Usai, G.; Usui, J.; Vacavant, L.; Vacek, V.; Vachon, B.; Valderanis, C.; Valdes Santurio, E.; Valencic, N.; Valentinetti, S.; Valero, A.; Valery, L.; Valkar, S.; Valls Ferrer, J. A.; Van Den Wollenberg, W.; Van Der Deijl, P. C.; van der Graaf, H.; van Eldik, N.; van Gemmeren, P.; Van Nieuwkoop, J.; van Vulpen, I.; van Woerden, M. C.; Vanadia, M.; Vandelli, W.; Vanguri, R.; Vaniachine, A.; Vankov, P.; Vardanyan, G.; Vari, R.; Varnes, E. W.; Varol, T.; Varouchas, D.; Vartapetian, A.; Varvell, K. E.; Vasquez, J. G.; Vasquez, G. A.; Vazeille, F.; Vazquez Schroeder, T.; Veatch, J.; Veeraraghavan, V.; Veloce, L. M.; Veloso, F.; Veneziano, S.; Ventura, A.; Venturi, M.; Venturi, N.; Venturini, A.; Vercesi, V.; Verducci, M.; Verkerke, W.; Vermeulen, J. C.; Vest, A.; Vetterli, M. C.; Viazlo, O.; Vichou, I.; Vickey, T.; Vickey Boeriu, O. E.; Viehhauser, G. H. 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.

  17. Comments on "a study of the collisional fragmentation problem using the gamma distribution approximation".

    PubMed

    Nadarajah, Saralees

    2007-04-15

    M. Kostoglou and A.J. Karabelas [J. Colloid Interface Sci. 303 (2006) 419-429] proposed using a gamma distribution approximation to study a collisional fragmentation problem. This approximation involved two types of integrals and the use of continued fraction expansions for their computation. In this Comment, explicit expressions are derived for computing the integrals.

  18. Gamma Dose Distribution Studies in Ducted Shield Material Having Different Configurations

    NASA Astrophysics Data System (ADS)

    Sayed Ahmed, F. M.

    In the present work the radial distribution of total gamma doses arising from the interaction of reactor neutrons and gamma radiations inside ilmenite heavy concrete shield are measured. The ilmenite concrete is pierced with neutral beam injector ducts having different diameters and lengths. The results obtained show a relative increase in radial gamma doses at a distance of 10 cm from the neutral beam end. An empirical formula was obtained, fitting the measured gamma doses at the peak position in good agreement within a factor of 1.27. Moreover the variation of the total gamma radiation was measured along straight filled ducted with different diameters and length. The experimental data obtained show a reasonable agreement with calculated ones. The scattered as well as unscattered components of the gamma radiation transmitted through a straight duct were investigated. An empirical formula describing this behaviour was obtained.Translated AbstractDie Untersuchung der Dosisverteilung in verschieden konfigurierten Schirmmaterialien mit DurchführungenIn der vorliegenden Arbeit wird die radiale Verteilung der totalen -Dosis gemessen, wie sie aus der Wechselwirkung von Reaktorneutronen und -Strahlung innerhalb eines Betonschirms entsteht. Der Beton ist mit verschieden großen und langen Durchführungen versehen. Die erhaltenen Resultate zeigen einen relativen Intensitätspik 10 cm vor Durchführungsende. Eine empirische Formel wird aufgestellt, die diese Verhältnisse relativ gut (um den Faktor 1.27) wiedergibt. Darüber hinaus wurde die Gamma-Strahlung entlang gerader, gefüllter Durchführungen unterschiedlicher Abmessungen gemessen. Übereinstimmung mit berechneten Werten konnte erzielt werden. Sowohl die gestreuten als auch die ungestreuten Komponenten der Gamma-Strahlung in einer geraden Durchführung wurden untersucht und eine beschriebene, empirische Formel dafür angegeben.

  19. A novel time dependent gamma evaluation function for dynamic 2D and 3D dose distributions.

    PubMed

    Podesta, Mark; Persoon, Lucas C G G; Verhaegen, Frank

    2014-10-21

    Modern external beam radiotherapy requires detailed verification and quality assurance so that confidence can be placed on both the delivery of a single treatment fraction and on the consistency of delivery throughout the treatment course. To verify dose distributions, a comparison between prediction and measurement must be made. Comparisons between two dose distributions are commonly performed using a Gamma evaluation which is a calculation of two quantities on a pixel by pixel basis; the dose difference, and the distance to agreement. By providing acceptance criteria (e.g. 3%, 3 mm), the function will find the most appropriate match within its two degrees of freedom. For complex dynamic treatments such as IMRT or VMAT it is important to verify the dose delivery in a time dependent manner and so a gamma evaluation that includes a degree of freedom in the time domain via a third parameter, time to agreement, is presented here. A C++ (mex) based gamma function was created that could be run on either CPU and GPU computing platforms that would allow a degree of freedom in the time domain. Simple test cases were created in both 2D and 3D comprising of simple geometrical shapes with well-defined boundaries varying over time. Changes of varying magnitude in either space or time were introduced and repeated gamma analyses were performed varying the criteria. A clinical VMAT case was also included, artificial air bubbles of varying size were introduced to a patient geometry, along with shifts of varying magnitude in treatment time. For all test cases where errors in distance, dose or time were introduced, the time dependent gamma evaluation could accurately highlight the errors.The time dependent gamma function presented here allows time to be included as a degree of freedom in gamma evaluations. The function allows for 2D and 3D data sets which are varying over time to be compared using appropriate criteria without penalising minor offsets of subsequent radiation fields

  20. A novel time dependent gamma evaluation function for dynamic 2D and 3D dose distributions

    NASA Astrophysics Data System (ADS)

    Podesta, Mark; CGG Persoon, Lucas; Verhaegen, Frank

    2014-10-01

    Modern external beam radiotherapy requires detailed verification and quality assurance so that confidence can be placed on both the delivery of a single treatment fraction and on the consistency of delivery throughout the treatment course. To verify dose distributions, a comparison between prediction and measurement must be made. Comparisons between two dose distributions are commonly performed using a Gamma evaluation which is a calculation of two quantities on a pixel by pixel basis; the dose difference, and the distance to agreement. By providing acceptance criteria (e.g. 3%, 3 mm), the function will find the most appropriate match within its two degrees of freedom. For complex dynamic treatments such as IMRT or VMAT it is important to verify the dose delivery in a time dependent manner and so a gamma evaluation that includes a degree of freedom in the time domain via a third parameter, time to agreement, is presented here. A C++ (mex) based gamma function was created that could be run on either CPU and GPU computing platforms that would allow a degree of freedom in the time domain. Simple test cases were created in both 2D and 3D comprising of simple geometrical shapes with well-defined boundaries varying over time. Changes of varying magnitude in either space or time were introduced and repeated gamma analyses were performed varying the criteria. A clinical VMAT case was also included, artificial air bubbles of varying size were introduced to a patient geometry, along with shifts of varying magnitude in treatment time. For all test cases where errors in distance, dose or time were introduced, the time dependent gamma evaluation could accurately highlight the errors. The time dependent gamma function presented here allows time to be included as a degree of freedom in gamma evaluations. The function allows for 2D and 3D data sets which are varying over time to be compared using appropriate criteria without penalising minor offsets of subsequent radiation

  1. The hump in the Cerenkov lateral distribution of gamma ray showers

    NASA Technical Reports Server (NTRS)

    Sinha, S.; Sao, M. V. S.

    1985-01-01

    The lateral distribution of atmospheric Cerenkov photons emitted by gamma ray showers of energy 100 GeV is calculated. The lateral distribution shows a characteristic hump at a distance of approx. 135 meter from the core. The hump is shown to be due to electrons of threshold energy 1 GeV, above which the mean scattering angle becomes smaller than the Cerenkov angle.

  2. Total Absorption Gamma-ray Spectrometer (TAGS) Intensity Distributions from INL's Gamma-Ray Spectrometry Center

    DOE Data Explorer

    Greenwood, R. E.

    A 252Cf fission-product source and the INL on-line isotope separator were used to supply isotope-separated fission-product nuclides to a total absorption -ray spectrometer. This spectrometer consisted of a large (25.4-cm diameter x 30.5-cm long) NaI(Tl) detector with a 20.3-cm deep axial well in which is placed a 300-mm2 x 1.0-mm Si detector. The spectra from the NaI(Tl) detector are collected both in the singles mode and in coincidence with the B-events detected in the Si detector. Ideally, this detector would sum all the energy of the B- rays in each cascade following the population of daughter level by B- decay, so that the event could be directly associated with a particular daughter level. However, there are losses of energy from attenuation of the rays before they reach the detector, transmission of rays through the detector, escape of secondary photons from Compton scattering, escape of rays through the detector well, internal conversion, etc., and the measured spectra are thus more complicated than the ideal case and the analysis is more complex. Analysis methods have been developed to simulate all of these processes and thus provide a direct measure of the B- intensity distribution as a function of the excitation energy in the daughter nucleus. These data yield more accurate information on the B- distribution than conventional decay-scheme studies for complex decay schemes with large decay energies, because in the latter there are generally many unobserved and observed but unplaced rays. The TAGS data have been analyzed and published [R. E. Greenwood et al., Nucl Instr. and metho. A390(1997)] for 40 fission product-nuclides to determine the B- intensity distributions. [Copied from the TAGS page at http://www.inl.gov/gammaray/spectrometry/tags.shtml]. Those values are listed on this page for quick reference.

  3. Time Evolving Fission Chain Theory and Fast Neutron and Gamma-Ray Counting Distributions

    DOE PAGES

    Kim, K. S.; Nakae, L. F.; Prasad, M. K.; ...

    2015-11-01

    Here, we solve a simple theoretical model of time evolving fission chains due to Feynman that generalizes and asymptotically approaches the point model theory. The point model theory has been used to analyze thermal neutron counting data. This extension of the theory underlies fast counting data for both neutrons and gamma rays from metal systems. Fast neutron and gamma-ray counting is now possible using liquid scintillator arrays with nanosecond time resolution. For individual fission chains, the differential equations describing three correlated probability distributions are solved: the time-dependent internal neutron population, accumulation of fissions in time, and accumulation of leaked neutronsmore » in time. Explicit analytic formulas are given for correlated moments of the time evolving chain populations. The equations for random time gate fast neutron and gamma-ray counting distributions, due to randomly initiated chains, are presented. Correlated moment equations are given for both random time gate and triggered time gate counting. There are explicit formulas for all correlated moments are given up to triple order, for all combinations of correlated fast neutrons and gamma rays. The nonlinear differential equations for probabilities for time dependent fission chain populations have a remarkably simple Monte Carlo realization. A Monte Carlo code was developed for this theory and is shown to statistically realize the solutions to the fission chain theory probability distributions. Combined with random initiation of chains and detection of external quanta, the Monte Carlo code generates time tagged data for neutron and gamma-ray counting and from these data the counting distributions.« less

  4. 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.

  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. Diffeomorphic metric mapping of high angular resolution diffusion imaging based on Riemannian structure of orientation distribution functions.

    PubMed

    Du, Jia; Goh, Alvina; Qiu, Anqi

    2012-05-01

    In this paper, we propose a novel large deformation diffeomorphic registration algorithm to align high angular resolution diffusion images (HARDI) characterized by orientation distribution functions (ODFs). Our proposed algorithm seeks an optimal diffeomorphism of large deformation between two ODF fields in a spatial volume domain and at the same time, locally reorients an ODF in a manner such that it remains consistent with the surrounding anatomical structure. To this end, we first review the Riemannian manifold of ODFs. We then define the reorientation of an ODF when an affine transformation is applied and subsequently, define the diffeomorphic group action to be applied on the ODF based on this reorientation. We incorporate the Riemannian metric of ODFs for quantifying the similarity of two HARDI images into a variational problem defined under the large deformation diffeomorphic metric mapping framework. We finally derive the gradient of the cost function in both Riemannian spaces of diffeomorphisms and the ODFs, and present its numerical implementation. Both synthetic and real brain HARDI data are used to illustrate the performance of our registration algorithm.

  7. 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.

  8. Above-threshold ionization of noble gases in elliptically polarized fields: Effects of atomic polarization on photoelectron angular distributions

    NASA Astrophysics Data System (ADS)

    Wang, YanLan; Yu, ShaoGang; Lai, XuanYang; Liu, XiaoJun; Chen, Jing

    2017-06-01

    We theoretically investigate the atomic polarization effect on photoelectron angular distributions (PADs) in above-threshold ionization of noble gases with elliptically polarized laser fields at wavelength of 800 nm, ellipticity of 0.25, and intensity of 1.5 ×1014W/cm2 . Simulations based on a semiclassical model that includes both the ionic Coulomb potential and the atomic polarization effect show surprisingly little difference between PADs for Ar, Kr, and Xe, which is in good agreement with recent experimental observations. Our calculations reveal that the atomic polarization effect increases the distance of the tunnel exit point of the photoelectron to the parent ion and weakens the strength of the interaction between the parent ion and the photoelectron on its subsequent classical propagation. As a result, the forward-scattering electrons which contribute to the main lobes in PADs are substantially suppressed. Our results indicate that the insensitivity of PADs for Ar, Kr, and Xe may be closely related to the influence of the atomic polarization effect on the photoelectron dynamics in the strong laser field.

  9. 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.

  10. Inspection of 56Fe γ-Ray angular distributions as a function of incident neutron energy using optical model approaches

    NASA Astrophysics Data System (ADS)

    Vanhoy, J. R.; Ramirez, A. P.; Alcorn-Dominguez, D. K.; Hicks, S. F.; Peters, E. E.; McEllistrem, M. T.; Mukhopadhyay, S.; Yates, S. W.

    2017-09-01

    Neutron inelastic scattering cross sections measured directly through (n,n) or deduced from γ-ray production cross sections following inelastic neutron scattering (n,n'γ) are a focus of basic and applied research at the University of Kentucky Accelerator Laboratory (www.pa.uky.edu/accelerator). For nuclear data applications, angle-integrated cross sections are desired over a wide range of fast neutron energies. Several days of experimental beam time are required for a data set at each incident neutron energy, which limits the number of angular distributions that can be measured in a reasonable amount of time. Approximations can be employed to generate cross sections with a higher energy resolution, since at 125o, the a2P2 term of the Legendre expansion is identically zero and the a4P4 is assumed to be very small. Provided this assumption is true, a single measurement at 125o would produce the γ-ray production cross section. This project tests these assumptions and energy dependences using the codes CINDY/SCAT and TALYS/ECIS06/SCAT. It is found that care must be taken when interpreting γ-ray excitation functions as cross sections when the incident neutron energy is < 1000 keV above threshold or before the onset of feeding.

  11. 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.

  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. Modelling the flux distribution function of the extragalactic gamma-ray background from dark matter annihilation

    NASA Astrophysics Data System (ADS)

    Feyereisen, Michael R.; Ando, Shin'ichiro; Lee, Samuel K.

    2015-09-01

    The one-point function (i.e., the isotropic flux distribution) is a complementary method to (anisotropic) two-point correlations in searches for a gamma-ray dark matter annihilation signature. Using analytical models of structure formation and dark matter halo properties, we compute the gamma-ray flux distribution due to annihilations in extragalactic dark matter halos, as it would be observed by the Fermi Large Area Telescope. Combining the central limit theorem and Monte Carlo sampling, we show that the flux distribution takes the form of a narrow Gaussian of `diffuse' light, with an `unresolved point source' power-law tail as a result of bright halos. We argue that this background due to dark matter constitutes an irreducible and significant background component for point-source annihilation searches with galaxy clusters and dwarf spheroidal galaxies, modifying the predicted signal-to-noise ratio. A study of astrophysical backgrounds to this signal reveals that the shape of the total gamma-ray flux distribution is very sensitive to the contribution of a dark matter component, allowing us to forecast promising one-point upper limits on the annihilation cross-section. We show that by using the flux distribution at only one energy bin, one can probe the canonical cross-section required for explaining the relic density, for dark matter of masses around tens of GeV.

  14. Modelling the flux distribution function of the extragalactic gamma-ray background from dark matter annihilation

    SciTech Connect

    Feyereisen, Michael R.; Ando, Shin'ichiro; Lee, Samuel K. E-mail: s.ando@uva.nl

    2015-09-01

    The one-point function (i.e., the isotropic flux distribution) is a complementary method to (anisotropic) two-point correlations in searches for a gamma-ray dark matter annihilation signature. Using analytical models of structure formation and dark matter halo properties, we compute the gamma-ray flux distribution due to annihilations in extragalactic dark matter halos, as it would be observed by the Fermi Large Area Telescope. Combining the central limit theorem and Monte Carlo sampling, we show that the flux distribution takes the form of a narrow Gaussian of 'diffuse' light, with an 'unresolved point source' power-law tail as a result of bright halos. We argue that this background due to dark matter constitutes an irreducible and significant background component for point-source annihilation searches with galaxy clusters and dwarf spheroidal galaxies, modifying the predicted signal-to-noise ratio. A study of astrophysical backgrounds to this signal reveals that the shape of the total gamma-ray flux distribution is very sensitive to the contribution of a dark matter component, allowing us to forecast promising one-point upper limits on the annihilation cross-section. We show that by using the flux distribution at only one energy bin, one can probe the canonical cross-section required for explaining the relic density, for dark matter of masses around tens of GeV.

  15. Gamma-tubulin distribution in the neuron: implications for the origins of neuritic microtubules

    PubMed Central

    1992-01-01

    Axons and dendrites contain dense microtubule (MT) assays that are not attached to a traditional MT nucleating structure such as the centrosome. Nevertheless, the MTs within these neurites are highly organized with respect to their polarity, and consist of a regular 13- protofilament lattice, the two known characteristics of MTs nucleated at the centrosome. These observations suggest either that axonal and dendritic MTs arise at the centrosome, or that they are nucleated locally, following a redistribution of MT nucleating material from the centrosome during neuronal development. To begin distinguishing between these possibilities, we have determined the distribution of gamma- tubulin within cultured sympathetic neurons. gamma-tubulin, a newly discovered protein which is specifically localized to the pericentriolar region of nonneuronal cells (Zheng, Y., M. K. Jung, and B. R. Oakley. 1991. Cell. 65:817-823; Stearns, T., L. Evans, and M. Kirschner. 1991. Cell. 65:825-836), has been shown to play a critical role in MT nucleation in vivo (Joshi, H. C., M. J. Palacios, L. McNamara, and D. W. Cleveland. 1992. Nature (Lond.). 356:80-83). Because the gamma-tubulin content of individual cells is extremely low, we relied principally on the high degree of resolution and sensitivity afforded by immunoelectron microscopy. Our studies reveal that, like the situation in nonneuronal cells, gamma-tubulin is restricted to the pericentriolar region of the neuron. Furthermore, serial reconstruction analyses indicate that the minus ends of MTs in both axons and dendrites are free of gamma-tubulin immunoreactivity. The absence of gamma-tubulin from the axon was confirmed by immunoblot analyses of pure axonal fractions obtained from explant cultures. The observation that gamma-tubulin is restricted to the pericentriolar region of the neuron provides compelling support for the notion that MTs destined for axons and dendrites are nucleated at the centrosome, and subsequently released for

  16. Gamma-tubulin distribution in the neuron: implications for the origins of neuritic microtubules.

    PubMed

    Baas, P W; Joshi, H C

    1992-10-01

    Axons and dendrites contain dense microtubule (MT) assays that are not attached to a traditional MT nucleating structure such as the centrosome. Nevertheless, the MTs within these neurites are highly organized with respect to their polarity, and consist of a regular 13-protofilament lattice, the two known characteristics of MTs nucleated at the centrosome. These observations suggest either that axonal and dendritic MTs arise at the centrosome, or that they are nucleated locally, following a redistribution of MT nucleating material from the centrosome during neuronal development. To begin distinguishing between these possibilities, we have determined the distribution of gamma-tubulin within cultured sympathetic neurons. gamma-tubulin, a newly discovered protein which is specifically localized to the pericentriolar region of nonneuronal cells (Zheng, Y., M. K. Jung, and B. R. Oakley. 1991. Cell. 65:817-823; Stearns, T., L. Evans, and M. Kirschner. 1991. Cell. 65:825-836), has been shown to play a critical role in MT nucleation in vivo (Joshi, H. C., M. J. Palacios, L. McNamara, and D. W. Cleveland. 1992. Nature (Lond.). 356:80-83). Because the gamma-tubulin content of individual cells is extremely low, we relied principally on the high degree of resolution and sensitivity afforded by immunoelectron microscopy. Our studies reveal that, like the situation in nonneuronal cells, gamma-tubulin is restricted to the pericentriolar region of the neuron. Furthermore, serial reconstruction analyses indicate that the minus ends of MTs in both axons and dendrites are free of gamma-tubulin immunoreactivity. The absence of gamma-tubulin from the axon was confirmed by immunoblot analyses of pure axonal fractions obtained from explant cultures. The observation that gamma-tubulin is restricted to the pericentriolar region of the neuron provides compelling support for the notion that MTs destined for axons and dendrites are nucleated at the centrosome, and subsequently released for

  17. Distribution of terrestrial gamma radiation dose rate in the eastern coastal area of Odisha, India.

    PubMed

    Gusain, G S; Rautela, B S; Sahoo, S K; Ishikawa, T; Prasad, G; Omori, Y; Sorimachi, A; Tokonami, S; Ramola, R C

    2012-11-01

    Terrestrial gamma radiation is one of the important radiation exposures on the earth's surface that results from the three primordial radionuclides (226)Ra, (232)Th and (40)K. The elemental concentration of these elements in the earth's crust could result in the anomalous variation of the terrestrial gamma radiation in the environment. The geology of the local area plays an important role in distribution of these radioactive elements. Environmental terrestrial gamma radiation dose rates were measured around the eastern coastal area of Odisha with the objective of establishing baseline data on the background radiation level. The values of the terrestrial gamma radiation dose rate vary significantly at different locations in the study area. The values of the terrestrial gamma dose rate ranged from 77 to 1651 nGy h(-1), with an average of 230 nGy h(-1). During the measurement of the terrestrial gamma dose rate, sand and soil samples were also collected for the assessment of natural radionuclides. The activities of (226)Ra, (232)Th and (40)K from these samples were measured using a gamma-ray spectrometry with a NaI(Tl) detector. Activity concentrations of (226)Ra, (232)Th and (40)K ranged from 15.6 to 69 Bq kg(-1) with an average of 46.7 Bq kg(-1), from 28.9 to 973 Bq kg(-1) with an average of 250 Bq kg(-1) and from 139 to 952 Bq kg(-1) with an average of 429, respectively. The detailed significance of these studies has been discussed from the radiation protection point of view.

  18. The Tromsø Study. Distribution and population determinants of gamma-glutamyltransferase.

    PubMed

    Nilssen, O; Førde, O H; Brenn, T

    1990-08-01

    Gamma-glutamyltransferase was measured in 10,942 males aged 12-62 years and 10,840 females aged 12-59 years screened in a health survey program. The distribution was right-skewed, with medians of 17 and 12 units/liter for males and females, respectively. Fewer than 5.5% of the males and 1.5% of the females had values exceeding 50 units/liter, reflecting the modest use of alcohol in Norway. In sex-specific multiple regression analyses, gamma-glutamyl-transferase showed a strong positive association with body mass index, alcohol use, and total serum cholesterol and a somewhat weaker positive association with serum triglycerides, high density lipoprotein cholesterol, heart rate, blood pressure, use of analgesics, and time since last meal. Strong negative associations were found for coffee consumption, hour of the day at which the examination was performed and, in males, physical activity. In females, use of oral contraceptives and menopause were positively associated with gamma-glutamyltransferase, whereas pregnant females had lower values. In conclusion, the gamma-glutamyltransferase level in the Tromsø population was low, with marked and consistent sex differences which probably are physiologic. Within its normal range, gamma-glutamyltransferase has many other, even stronger determinants than alcohol consumption.

  19. 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.

  20. 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)].

  1. Differential absorbed dose distributions in lineal energy for neutrons and gamma rays at the mono-energetic neutron calibration facility.

    PubMed

    Takada, M; Baba, M; Yamaguchi, H; Fujitaka, K

    2005-01-01

    Absorbed dose distributions in lineal energy for neutrons and gamma rays of mono-energetic neutron sources from 140 keV to 15 MeV were measured in the Fast Neutron Laboratory at Tohoku University. By using both a tissue-equivalent plastic walled counter and a graphite-walled low-pressure proportional counter, absorbed dose distributions in lineal energy for neutrons were obtained separately from those for gamma rays. This method needs no knowledge of energy spectra and dose distributions for gamma rays. The gamma-ray contribution in this neutron calibration field >1 MeV neutron was <3%, while for <550 keV it was >40%. The measured neutron absolute absorbed doses per unit neutron fluence agreed with the LA150 evaluated kerma factors. By using this method, absorbed dose distributions in lineal energy for neutrons and gamma rays in an unknown neutron field can be obtained separately.

  2. A Comparison of Gamma and Lognormal Distributions for Characterizing Satellite Rain Rates from the Tropical Rainfall Measuring Mission.

    NASA Astrophysics Data System (ADS)

    Cho, Hye-Kyung; Bowman, Kenneth P.; North, Gerald R.

    2004-11-01

    This study investigates the spatial characteristics of nonzero rain rates to develop a probability density function (PDF) model of precipitation using rainfall data from the Tropical Rainfall Measuring Mission (TRMM) satellite. The minimum χ2 method is used to find a good estimator for the rain-rate distribution between the gamma and lognormal distributions, which are popularly used in the simulation of the rain-rate PDF. Results are sensitive to the choice of dynamic range, but both the gamma and lognormal distributions match well with the PDF of rainfall data. Comparison with sample means shows that the parametric mean from the lognormal distribution overestimates the sample mean, whereas the gamma distribution underestimates it. These differences are caused by the inflated tail in the lognormal distribution and the small shape parameter in the gamma distribution. If shape constraint is given, the difference between the sample mean and the parametric mean from the fitted gamma distribution decreases significantly, although the resulting χ2 values slightly increase. Of interest is that a consistent regional preference between two test functions is found. The gamma fits outperform the lognormal fits in wet regions, whereas the lognormal fits are better than the gamma fits for dry regions. Results can be improved with a specific model assumption depending on mean rain rates, but the results presented in this study can be easily applied to develop the rainfall retrieval algorithm and to find the proper statistics in the rainfall data.


  3. The Truncated Lognormal Distribution as a Luminosity Function for SWIFT-BAT Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Zaninetti, Lorenzo

    2016-11-01

    The determination of the luminosity function (LF) in gamma ray bursts (GRBs) depends on the adopted cosmology, each one characterized by its corresponding luminosity distance. Here we analyse three cosmologies: the standard cosmology, the plasma cosmology, and the pseudo-Euclidean universe. The LF of the GRBs is firstly modeled by the lognormal distribution and the four broken power law, and secondly by a truncated lognormal distribution. The truncated lognormal distribution fits acceptably the range in luminosity of GRBs as a function of the redshift.

  4. Is the Narrow E-Peak Distribution of Gamma-Ray Bursts Real?

    NASA Technical Reports Server (NTRS)

    Brainerd, Jerome J.

    2000-01-01

    Over the performance period of the research grant, the authors conducted a study of the role that the detector response plays in the detection of gamma-ray bursts. The goal of the study was to determine whether the fact that the gamma-ray bursts observed by the BATSE instrument on the Compton Gamma-ray Observatory are characterized by approximately the same characteristic energy is a consequence of the instrument's characteristics, or whether the distribution is a physical attribute of gamma-ray bursts. The authors succeeded in showing that instrumental effects are mild, and that the observed characteristic energy is a physical attribute of bursts. In the course of this research, the authors ported the computer code for calculating the BATSE detector response matrices to the Sun Solaris platform, and created a version of the code that runs under any platform that supports a Fortran 77 compiler with DEC extensions. This code has already been used by other investigators to analyze BATSE data. The authors constructed a Monte Carlo simulation of the BATSE burst trigger, with which they determined the efficiency of detecting a burst as a function of characteristic burst spectral energy. The results were then applied to BATSE observations to determine the physical model for the distribution of burst characteristic energies.

  5. Is the Narrow E-Peak Distribution of Gamma-Ray Bursts Real?

    NASA Technical Reports Server (NTRS)

    Brainerd, Jerome J.

    2000-01-01

    Over the performance period of the research grant, the authors conducted a study of the role that the detector response plays in the detection of gamma-ray bursts. The goal of the study was to determine whether the fact that the gamma-ray bursts observed by the BATSE instrument on the Compton Gamma-ray Observatory are characterized by approximately the same characteristic energy is a consequence of the instrument's characteristics, or whether the distribution is a physical attribute of gamma-ray bursts. The authors succeeded in showing that instrumental effects are mild, and that the observed characteristic energy is a physical attribute of bursts. In the course of this research, the authors ported the computer code for calculating the BATSE detector response matrices to the Sun Solaris platform, and created a version of the code that runs under any platform that supports a Fortran 77 compiler with DEC extensions. This code has already been used by other investigators to analyze BATSE data. The authors constructed a Monte Carlo simulation of the BATSE burst trigger, with which they determined the efficiency of detecting a burst as a function of characteristic burst spectral energy. The results were then applied to BATSE observations to determine the physical model for the distribution of burst characteristic energies.

  6. 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.

  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. 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.

  9. 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.

  10. 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-.

  11. 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.

  12. Out-of-plane (e,2e) angular distributions and energy spectra of helium L = 0,1,2 autoionizing levels

    SciTech Connect

    Harak, B. A. de; Bartschat, K.; Martin, N. L. S.

    2010-12-15

    Angular distribution and spectral (e,2e) measurements are reported for the helium autoionizing levels (2s{sup 2}){sup 1}S, (2p{sup 2}){sup 1}D, and (2s2p){sup 1}P. A special out-of-plane geometry is used where the ejected electrons are emitted in a plane perpendicular to the scattered electron direction. The kinematics are chosen so that this plane contains the momentum-transfer direction. While the recoil peak almost vanishes in the angular distribution for direct ionization, it remains significant for the autoionizing levels and exhibits a characteristic shape for each orbital angular momentum L=0,1,2. A second-order model in the projectile-target interaction correctly reproduces the observed magnitudes of the recoil peaks, but is a factor of 2 too large in the central out-of-plane region. Observed (e,2e) energy spectra for the three resonances over the full angular range are well reproduced by the second-order calculation. Calculations using a first-order model fail to reproduce both the magnitudes of the recoil peaks and the spectral line profiles.

  13. Space and phase resolved ion energy and angular distributions in single- and dual-frequency capacitively coupled plasmas

    SciTech Connect

    Zhang, Yiting; Kushner, Mark J.; Moore, Nathaniel; Pribyl, Patrick; Gekelman, Walter

    2013-11-15

    The control of ion energy and angular distributions (IEADs) is critically important for anisotropic etching or deposition in microelectronic fabrication processes. With single frequency capacitively coupled plasmas (CCPs), the narrowing in angle and spread in energy of ions as they cross the sheath are definable functions of frequency, sheath width, and mean free path. With increases in wafer size, single frequency CCPs are finding difficulty in meeting the requirement of simultaneously controlling plasma densities, ion fluxes, and ion energies. Dual-frequency CCPs are being investigated to provide this flexible control. The high frequency (HF) is intended to control the plasma density and ion fluxes, while the ion energies are intended to be controlled by the low frequency (LF). However, recent research has shown that the LF can also influence the magnitude of ion fluxes and that IEADs are determined by both frequencies. Hence, separate control of fluxes and IEADs is complex. In this paper, results from a two-dimensional computational investigation of Ar/O{sub 2} plasma properties in an industrial reactor are discussed. The IEADs are tracked as a function of height above the substrate and phase within the rf cycles from the bulk plasma to the presheath and through the sheath with the goal of providing insights to this complexity. Comparison is made to laser-induced fluorescence experiments. The authors found that the ratios of HF/LF voltage and driving frequency are critical parameters in determining the shape of the IEADs, both during the transit of the ion through the sheath and when ions are incident onto the substrate. To the degree that contributions from the HF can modify plasma density, sheath potential, and sheath thickness, this may provide additional control for the IEADs.

  14. The effects of pure density evolution on the brightness distribution of cosmological gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Horack, J. M.; Emslie, A. G.; Hartmann, D. H.

    1995-01-01

    In this work, we explore the effects of burst rate density evolution on the observed brightness distribution of cosmological gamma-ray bursts. Although the brightness distribution of gamma-ray bursts observed by the BATSE experiment has been shown to be consistent with a nonevolving source population observed to redshifts of order unity, evolution of some form is likely to be present in the gamma-ray bursts. Additionally, nonevolving models place significant constraints on the range of observed burst luminosities, which are relaxed if evolution of the burst population is present. In this paper, three analytic forms of density evolution are examined. In general, forms of evolution with densities that increase monotonically with redshift require that the BATSE data correspond to bursts at larger redshifts, or to incorporate a wider range of burst luminosities, or both. Independent estimates of the maximum observed redshift in the BATSE data and/or the range of luminosity from which a large fraction of the observed bursts are drawn therefore allow for constraints to be placed on the amount of evolution that may be present in the burst population. Specifically, if recent measurements obtained from analysis of the BATSE duration distribution of the actual limiting redshift in the BATSE data at z(sub lim) = 2 are correct, the BATSE N(P) distribution in a Lambda = 0 universe is inconsistent at a level of approximately 3 alpha with nonevolving gamma-ray bursts and some form of evolution in the population is required. The sense of this required source evolution is to provide a higher density, larger luminosities, or both with increasing redshift.

  15. Modifications to Computer Program for Parameter Estimation for the Generalized Gamma Distribution,

    DTIC Science & Technology

    1977-05-01

    10 EVALUATION OF MAXIMUM LIKELIHOOD METHOD .. .. ..... 13 DIGITAL PROGRAM DESCRIPTION .. .... ...... .... 14 INPUT DATA...Unit Number 1-1506-012. INTRODUCTION A computerized procedure for evaluating the parameters of the generalized gamma distribution from a set of random...0n 0" 0" C/) Cd) V) 12 EVALUATION OF THE MAXIMUM LIKELIHOOD METHOD The method previously employed to determine estimation param- eters for the

  16. Graphical tests for the assumption of gamma and inverse Gaussian frailty distributions.

    PubMed

    Economou, P; Caroni, C

    2005-12-01

    The common choices of frailty distribution in lifetime data models include the Gamma and Inverse Gaussian distributions. We present diagnostic plots for these distributions when frailty operates in a proportional hazards framework. Firstly, we present plots based on the form of the unconditional survival function when the baseline hazard is assumed to be Weibull. Secondly, we base a plot on a closure property that applies for any baseline hazard, namely, that the frailty distribution among survivors at time t has the same form as the original distribution, with the same shape parameter but different scale parameter. We estimate the shape parameter at different values of t and examine whether it is constant, that is, whether plotted values form a straight line parallel to the time axis. We provide simulation results assuming Weibull baseline hazard and an example to illustrate the methods.

  17. 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.

  18. An analytical approach to the light transport in columnar phosphors. Detector Optical Gain, angular distribution and the CsI:Tl paradigm.

    PubMed

    Psichis, Konstantinos; Kalyvas, Nektarios; Kandarakis, Ioannis; Panayiotakis, George

    2017-03-01

    An analytical model has been developed for the light propagation in columnar phosphors, based on the optical photon propagation physical and geometrical principles. This model accounts for the multiple reflections on the sides of the crystal column, as well as for the infinite forward and backward reflections of the propagated optical photon beams created in the crystal bulk. Additionally it considers the lateral propagated optical photon beams after multiple refractions from the neighbor columns and the optical photon attenuation inside the scintillator. The model was used to predict the Detector Optical Gain (DOG), and the angular distribution, of the columnar CsI:Tl scintillators, used in medical imaging. The model was validated against CsI:Tl optical photon transmission published results and good agreement was observed. It was, also, found that the DOG is affected by the length of the columns, as well as the incident X-ray energy spectrum. The results of the angular distribution are in accordance with the theory that the longer crystal columns have more directional light distribution. The results of DOG are in accordance with the use of short crystal columns for lower energies (mammography) and the use of long crystal columns for higher energies (general radiology). Angular distribution was found more directive for long crystal columns. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  19. 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

  20. Using gamma distribution to determine half-life of rotenone, applied in freshwater.

    PubMed

    Rohan, Maheswaran; Fairweather, Alastair; Grainger, Natasha

    2015-09-15

    Following the use of rotenone to eradicate invasive pest fish, a dynamic first-order kinetic model is usually used to determine the half-life and rate at which rotenone dissipated from the treated waterbody. In this study, we investigate the use of a stochastic gamma model for determining the half-life and rate at which rotenone dissipates from waterbodies. The first-order kinetic and gamma models produced similar values for the half-life (4.45 days and 5.33 days respectively) and days to complete dissipation (51.2 days and 52.48 days respectively). However, the gamma model fitted the data better and was more flexible than the first-order kinetic model, allowing us to use covariates and to predict a possible range for the half-life of rotenone. These benefits are particularly important when examining the influence that different environmental factors have on rotenone dissipation and when trying to predict the rate at which rotenone will dissipate during future operations. We therefore recommend that in future the gamma distribution model is used when calculating the half-life of rotenone in preference to the dynamic first-order kinetics model. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. An improved technique for comparing Gamma Knife dose-volume distributions in stereotactic radiosurgery

    NASA Astrophysics Data System (ADS)

    Tozer-Loft, Stephen M.; Walton, Lee; Forster, David M. C.; Kemeny, Andras A.

    1999-08-01

    A function derived from the geometry of brachytherapy dose distributions is applied to stereotactic radiosurgery and an algorithm for the production of a novel dose-volume histogram, the Anderson inverse-square shifted dose-volume histogram (DVH), is proposed. The expected form of the function to be plotted is checked by calculating its value for single focus exposures, and its application to clinical examples of Gamma Knife treatments described. The technique is shown to provide a valuable tool for assessing the adequacy of radiosurgical plans and comparing and reporting dose distributions.

  2. 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

  3. 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

  4. 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.

  5. Angular distributions and anisotropy of fission fragments from neutron-induced fission in intermediate energy range 1-200 MeV

    NASA Astrophysics Data System (ADS)

    Vorobyev, Alexander S.; Gagarski, Alexei M.; Shcherbakov, Oleg A.; Vaishnene, Larisa A.; Barabanov, Alexei L.

    2017-09-01

    Angular distributions of fission fragments from the neutron-induced fission of 232Th, 233U, 235U, 238U and 209Bi have been measured in the energy range 1-200 MeV at the neutron TOF spectrometer GNEIS based on the spallation neutron source at 1 GeV proton synchrocyclotron of the PNPI (Gatchina, Russia). The multiwire proportional counters have been used as a position sensitive fission fragment detector. A description of the experimental equipment and measurement procedure is given. The anisotropy of fission fragments deduced from the data on measured angular distributions is presented in comparison with experimental data of other authors, first of all, the recent data from WNR at LANSCE (Los Alamos, USA) and n_TOF(CERN).

  6. 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.

  7. Direct Photon Center-of-Mass Angular Distributions in $p\\bar{p}$ Collisions at $\\sqrt{s}$ =1.8-TeV

    SciTech Connect

    Nakae, Leslie F.

    1992-04-01

    The center-of-mass angular distribution of direct photon events, resulting from protonantiproton collisions at a center-of-mass energy of 1.8 TeV, as measured by the Collider Detector at Fermilab ( CDF) during the 1988-1089 experimental run, is presented . The direct photon events are identified primarily through the direct photon's characteristic isolation from other particles. The main source of background is from rare fragmentation of QCD partons into single isolated neutral mesons, which decay into two or more photons. The background is removed statistically by exploitation of tile expected difference in the resulting shower profiles. The resulting angular distribution for direct photons, in the transverse momemtum range from 22 to 45 Ge V is found to agree favorably with the predictions of Quantum Cbromodynamics (QCD) for an interaction with a fermion (spin 1/2) propagator

  8. 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; Carrera, E; Carvalho, W; Casey, B C K; Castilla-Valdez, H; Chakrabarti, S; Chakraborty, D; Chan, K M; Chandra, A; Cheu, E; Cho, D K; Choi, S; Choudhary, B; Christoudias, T; Cihangir, S; Claes, D; Clutter, J; Cooke, M; Cooper, W E; Corcoran, M; Couderc, F; Cousinou, M-C; Crépé-Renaudin, S; Cutts, D; Cwiok, M; Das, A; Davies, G; De, K; de Jong, S J; De la Cruz-Burelo, E; DeVaughan, K; Déliot, F; Demarteau, M; Demina, R; Denisov, D; Denisov, S P; Desai, S; Diehl, H T; Diesburg, M; Dominguez, A; Dorland, T; Dubey, A; Dudko, L V; Duflot, L; Duggan, D; Duperrin, A; Dutt, S; Dyshkant, A; Eads, M; Edmunds, D; Ellison, J; Elvira, V D; Enari, Y; Eno, S; Escalier, M; Evans, H; Evdokimov, A; Evdokimov, V N; Facini, G; Ferapontov, A V; Ferbel, T; Fiedler, F; Filthaut, F; Fisher, W; Fisk, H E; Fortner, M; Fox, H; Fu, S; Fuess, S; Gadfort, T; Galea, C F; Garcia-Bellido, A; Gavrilov, V; Gay, P; Geist, W; Geng, W; Gerber, C E; Gershtein, Y; Gillberg, D; Ginther, G; Gómez, B; Goussiou, A; Grannis, P D; Greder, S; Greenlee, H; Greenwood, Z D; Gregores, E M; Grenier, G; Gris, Ph; Grivaz, J-F; Grohsjean, A; Grünendahl, S; Grünewald, M W; Guo, F; Guo, J; Gutierrez, G; Gutierrez, P; Haas, A; Haefner, P; Hagopian, S; Haley, J; Hall, I; Hall, R E; Han, L; Harder, K; Harel, A; Hauptman, J M; Hays, J; Hebbeker, T; Hedin, D; Hegeman, J G; Heinson, A P; Heintz, U; Hensel, C; Heredia-De la Cruz, I; Herner, K; Hesketh, G; Hildreth, M D; Hirosky, R; Hoang, T; Hobbs, J D; Hoeneisen, B; Hohlfeld, M; Hossain, S; Houben, P; Hu, Y; Hubacek, Z; Huske, N; Hynek, V; Iashvili, I; Illingworth, R; Ito, A S; Jabeen, S; Jaffré, M; Jain, S; Jakobs, K; Jamin, D; Jesik, R; Johns, K; Johnson, C; Johnson, M; Johnston, D; Jonckheere, A; Jonsson, P; Juste, A; Kajfasz, E; Karmanov, D; Kasper, P A; Katsanos, I; Kaushik, V; Kehoe, R; Kermiche, S; Khalatyan, N; Khanov, A; Kharchilava, A; Kharzheev, Y N; Khatidze, D; Kim, T J; Kirby, M H; Kirsch, M; Klima, B; Kohli, J M; Konrath, J-P; Kozelov, A V; Kraus, J; Kuhl, T; Kumar, A; Kupco, A; Kurca, T; Kuzmin, V A; Kvita, J; Lacroix, F; Lam, D; Lammers, S; Landsberg, G; Lebrun, P; Lee, W M; Leflat, A; Lellouch, J; Li, J; Li, L; Li, Q Z; Lietti, S M; Lim, J K; Lincoln, D; Linnemann, J; Lipaev, V V; Lipton, R; Liu, Y; Liu, Z; Lobodenko, A; Lokajicek, M; Love, P; Lubatti, H J; Luna-Garcia, R; Lyon, A L; Maciel, A K A; Mackin, D; Mättig, P; Magaña-Villalba, R; Magerkurth, A; Mal, P K; Malbouisson, H B; Malik, S; Malyshev, V L; Maravin, Y; Martin, B; McCarthy, R; McGivern, C L; Meijer, M M; Melnitchouk, A; Mendoza, L; Menezes, D; Mercadante, P G; Merkin, M; Merritt, K W; Meyer, A; Meyer, J; Mitrevski, J; Mondal, N K; Moore, R W; Moulik, T; Muanza, G S; Mulhearn, M; Mundal, O; Mundim, L; Nagy, E; Naimuddin, M; Narain, M; Neal, H A; Negret, J P; Neustroev, P; Nilsen, H; Nogima, H; Novaes, S F; Nunnemann, T; Obrant, G; Ochando, C; Onoprienko, D; Orduna, J; Oshima, N; Osman, N; Osta, J; Otec, R; Otero y Garzón, G J; Owen, M; Padilla, M; Padley, P; Pangilinan, M; Parashar, N; 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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.

  9. 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

  10. 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)

  11. 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.

  12. Search for new phenomena in dijet angular distributions in proton-proton collisions at s=8TeV measured with the ATLAS detector

    DOE PAGES

    Aad, G.

    2015-06-04

    In this study, 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 aremore » 8.9 TeV for the destructive interference scenario and 14.1 TeV for the constructive interference scenario.« less

  13. 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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