WorldWideScience

Sample records for atic electron observation

  1. Upturn observed in heavy nuclei to iron ratios by the ATIC-2 experiment

    CERN Document Server

    Panov, A D; Zatsepin, V I; Adams, J H; Ahn, H S; Bashindzhagyan, G L; Chang, J; Christl, M; Fazely, A R; Guzik, T G; Isbert, J; Kim, K C; Kouznetsov, E N; Panasyuk, M I; Seo, E S; Watts, J W; Wefel, J P; Wu, J; 10.1088/1742-6596/409/1/012036

    2013-01-01

    The ratios of fluxes of heavy nuclei from sulfur (Z=16) to chromium (Z=24) to the flux of iron were measured by the ATIC-2 experiment. The ratios are decreasing functions of energy from 5 GeV/n to approximately 80 GeV/n, as expected. However, an unexpected sharp upturn in the ratios are observed for energies above 100 GeV/n for all elements from Z=16 to Z=24. Similar upturn but with lower amplitude was also discovered in the ATIC-2 data for the ratio of fluxes of abundant even nuclei (C, O, Ne, Mg, Si) to the flux of iron. Therefore the spectrum of iron is significantly different from the spectra of other abundant even nuclei.

  2. PAMELA and ATIC Anomalies in Decaying Gravitino Dark Matter Scenario

    OpenAIRE

    Ishiwata, Koji; Matsumoto, Shigeki; Moroi, Takeo

    2009-01-01

    Motivated by the recent results from the PAMELA and ATIC, we study the cosmic-ray electron and positron produced by the decay of gravitino dark matter. We calculate the cosmic-ray electron and positron fluxes and discuss implications to the PAMELA and ATIC data. In this paper, we will show that the observed anomalous fluxes by the PAMELA and ATIC can be explained in such a scenario. We will also discuss the synchrotron radiation flux from the Galactic center in such a scenario.

  3. Upturn in the ratio of nuclei of Z=16–24 to iron observed in the ATIC experiment and the Local Bubble

    International Nuclear Information System (INIS)

    The ratios of heavy nuclei from Sulfur (Z=16) to Chromium (Z=24) fluxes to the flux of iron nuclei were measured recently in the ATIC-2 experiment. These ratios were the decreasing functions of energy from 5 GeV/n to approximately 50 GeV/n as expected. However, an unexpected sharp upturn in the ratios was observed at energy ∼ 50 GeV/n. In this paper, we revise the data and show that the statistical confidence of the observed upturn in the ATIC data is 99.7% and some additional arguments supporting the phenomenon are presented. A possible cause of the upturn is discussed and it is demonstrated that it can be partially understood within a model of ‘Closed Galaxy with Bubbles’ (CGB). Some features and problems of the CGB model are discussed

  4. Dark Matter Annihilation and the PAMELA, FERMI and ATIC Anomalies

    OpenAIRE

    El-Zant, A. A.; Khalil, S.; Okada, H.

    2009-01-01

    If dark matter (DM) annihilation accounts for the tantalizing excess of cosmic ray electron/positrons, as reported by the PAMELA, ATIC, HESS and FERMI observatories, then the implied annihilation cross section must be relatively large. This results, in the context of standard cosmological models, in very small relic DM abundances that are incompatible with astrophysical observations. We explore possible resolutions to this apparent conflict in terms of non-standard cosmological scenarios; pla...

  5. CMSSM Spectroscopy in light of PAMELA and ATIC

    CERN Document Server

    Gogoladze, Ilia; Shafi, Qaisar; Yuksel, Hasan

    2009-01-01

    Dark matter neutralinos in the constrained minimal supersymmetric model (CMSSM) may account for the recent cosmic ray electron and positron observations reported by the PAMELA and ATIC experiments either through self annihilation or via decay. However, to achieve this, both scenarios require new physics beyond the 'standard' CMSSM, and a unified explanation of the two experiments suggests a neutralino mass of order 700 GeV - 2 TeV. A relatively light neutralino with mass around 100 GeV (300 GeV) can accomodate the PAMELA but not the ATIC observations based on a model of annihilating (decaying) neutralinos. We study the implications of these scenarios for Higgs and sparticle spectroscopy in the CMSSM and highlight some benchmark points. An estimate of neutrino flux expected from the annihilating and decaying neutralino scenarios is provided.

  6. Beam tests of the balloon-borne ATIC experiment

    CERN Document Server

    Ganel, O; Ahn, H S; Ampe, J; Bashindzhagian, G L; Case, G; Chang, H; Ellison, S; Fazely, A; Gould, R; Granger, D; Gunasingha, R M; Guzik, T G; Han, Y J; Isbert, J; Kim, H J; Kim, K C; Kim, S K; Kwon, Y; Panasyuk, M Y; Panov, A; Price, B; Samsonov, G; Schmidt, W K H; Sen, M; Seo, E S; Sina, R; Sokolskaya, N; Stewart, M; Voronin, A; Wagner, D; Wang, J Z; Wefel, J P; Wu, J; Zatsepin, V

    2005-01-01

    The Advanced Thin Ionization Calorimeter (ATIC) balloon-borne experiment is designed to perform cosmic-ray elemental spectra measurements from 50 GeV to 100 TeV for nuclei from hydrogen to iron. These measurements are expected to provide information about some of the most fundamental questions in astroparticle physics today. ATIC's design centers on an 18 radiation length (X0) deep bismuth germanate (BGO) calorimeter, preceded by a 0.75λint graphite target. In September 1999, the ATIC detector was exposed to high-energy beams at CERN's SPS accelerator within the framework of the development program for the Advanced Cosmic-ray Composition Experiment for the Space Station (ACCESS). In December 2000–January 2001 and again in December 2002–January 2003, ATIC flew on the first two of a series of long-duration balloon (LDB) flights from McMurdo Station, Antarctica. We present here results from the 1999 beam tests, including energy resolutions for electrons and protons at several beam energies from 100 to 375 G...

  7. Albedo in the ATIC Experiment

    Science.gov (United States)

    Sokolskaya, N. V.; Adams, J. H., Jr.; Ahn, H. S.; Bashindzhagyan, G. L.; Batkov, K. E.; Case, G.; Christl, M.; Chang, J.; Fazely, A. R.; Ganel, O.; Six, N. Frank (Technical Monitor)

    2002-01-01

    ATIC(Advanced Thin Ionization Calorimeter) is a balloon borne experiment designed to measure the cosmic ray composition for elements from hydrogen to iron and their energy spectra from approx.50 GeV to near 100 TeV. It consists of a Si-matrix detector to determine the charge of a CR particle, a scintillator hodoscope for tracking, carbon interaction targets and a fully active BGO calorimeter. ATIC had its first 16-day flight from McMurdo, Antarctica from 28/12/2000 to 13/01/2000. The ATIC flight collected approximately 25 million events. To measure charge of primary particle in presence of radiation scattered back from the interaction and subsequent shower development in the calorimeter a charge detector must be a mosaic of small detector pads so that the pad containing the signal from the incident particle has no additional signal from albedo particles. Therefore the silicon matrix was built of 4480 individual silicon pads each 2 cm x 1.5 cm. The matrix consists of four planes of detectors and the active detector area, in these planes are partially overlapped to completely cover the aperture. The lateral and amplitude distributions of albedo signals in Si-matrix are analyzed for different primary nuclei and different energy deposits in BGO calorimeter. The greater part of albedo signals has Q near 1, where Q = square root of Amplitude(MIP). The albedo distribution exponentially decreases up to Q near 8. These high values are produced by slow protons and plans. There are also a small number of signals of Q > 8, mainly for heavy nucleus primaries. These signals are apparently generated by neutrons. The comparison of the experimental data and simulations with GEANT 3-21 code using QGSM generator for nucleus-nucleus interactions is presented.

  8. Results from PAMELA, ATIC and FERMI: Pulsars or dark matter?

    Indian Academy of Sciences (India)

    Debtosh Chowdhury; Sudhir K Vempati; Chanda J Jog

    2011-01-01

    It is well known that dark matter dominates the dynamics of galaxies and clusters of galaxies. Its constituents remain a mystery despite an assiduous search for them over the past three decades. Recent results from the satellite-based PAMELA experiment show an excess in the positron fraction at energies between 10 and 100 GeV in the secondary cosmic ray spectrum. Other experiments, namely ATIC, HESS and FERMI, show an excess in the total electron (+ + −) spectrum for energies greater than 100 GeV. These excesses in the positron fraction as well as the electron spectrum can arise in local astrophysical processes like pulsars, or can be attributed to the annihilation of the dark matter particles. The latter possibility gives clues to the possible candidates for the dark matter in galaxies and other astrophysical systems. In this article, we give a report of these exciting developments.

  9. Albedo in the ATIC Experiment: Results of Measurements and Simulation

    Science.gov (United States)

    Sokolskaya, N. V.; Adams, J. H., Jr.; Ahn, H. S.; Bashindzhagyan, G. L.; Batkov, K. E.; Chang, J.; Christl, M.; Fazely, A. R.; Ganel, O.; Gunasingha, R. M.

    2004-01-01

    Characteristics of albedo, or backscatter current, providing a 'background' for calorimeter experiments in high energy cosmic rays are analyzed. The comparison of experimental data obtained in the flights of the ATIC spectrometer is made with simulations performed using the GEANT 3.21 code. The influence of the backscatter on charge resolution in the ATIC experiment is discussed.

  10. Decaying Hidden Gaugino as a Source of PAMELA/ATIC Anomalies

    CERN Document Server

    Shirai, Satoshi; Yanagida, T T

    2009-01-01

    We study a scenario that a U(1) hidden gaugino constitutes the dark matter in the Universe and decays into a lepton and slepton pair through a mixing with a U(1)B-L gaugino. We find that the dark-matter decay can account for the recent PAMELA and ATIC anomalies in the cosmic-ray positrons and electrons without an overproduction of antiprotons.

  11. Suppression of the coal importation monopoly: ATIC Services succeeds to ATIC

    International Nuclear Information System (INIS)

    1994 has been a turning point in the history of ATIC organism in charge for 50 years of the coal importation monopoly for the French government. Anticipating the suppression of this monopoly, an anonymous society, ATIC Services, has been created with the principal coal consumers as shareholders. Nevertheless, ATIC maintains its missions of general interest such as: identification forms control, verification of solid mineral fuel technical characteristics, statistics and general information. The decay of coal importations has increased to reach 6.2% in 1994 (against 6.5% in 1993 and 9.3% in 1992). Importations from Australia have replace those from the United States and show a 6.3% increase due to the needs of metallurgy industry. 1994 importations represent 13121 kt with 1119 kt from CEE countries (Germany, Benelux, United Kingdom). Colombia remains the main productive for Electricite de France (500 Kt), followed by South Africa which remains the first productive for industry. Maritime transportation is the quasi-unique way of solid mineral fuels importation to France. (J.S.). 1 fig

  12. Double-action dark matter, PAMELA and ATIC

    CERN Document Server

    Cheung, Kingman; Yuan, Tzu-Chiang

    2009-01-01

    Motivated by a two-bump (or 1-peak plus 1-hump) structure in the ATIC data, we perform a statistical analysis fitting the PAMELA and ATIC data to a dark matter model, in which the dark matter particle can undergo both annihilation and decay. Using a chi-square analysis we show that both data can be simultaneously fitted better with such a double-action dark matter particle. We use an existing neutrino mass model in literature to illustrate the idea.

  13. Double-action dark matter, PAMELA and ATIC

    Energy Technology Data Exchange (ETDEWEB)

    Cheung Kingman [Department of Physics, National Tsing Hua University, Hsinchu 300, Taiwan (China); Physics Division, National Center for Theoretical Sciences, Hsinchu 300, Taiwan (China); Division of Quantum Phases and Devices, School of Physics, Konkuk University, Seoul 143-701 (Korea, Republic of)], E-mail: cheung@phys.nthu.edu.tw; Tseng, P.-Y. [Department of Physics, National Tsing Hua University, Hsinchu 300, Taiwan (China); Yuan, T.-C. [Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan (China)

    2009-07-20

    Motivated by a two-bump (or 1-peak plus 1-hump) structure in the ATIC data, we perform a statistical analysis fitting the PAMELA and ATIC data to a dark matter model, in which the dark matter particle can undergo both annihilation and decay. Using a chi-square analysis we show that both data can be simultaneously fitted better with such a double-action dark matter particle. We use an existing neutrino mass model in literature to illustrate the idea.

  14. Double-action dark matter, PAMELA and ATIC

    International Nuclear Information System (INIS)

    Motivated by a two-bump (or 1-peak plus 1-hump) structure in the ATIC data, we perform a statistical analysis fitting the PAMELA and ATIC data to a dark matter model, in which the dark matter particle can undergo both annihilation and decay. Using a chi-square analysis we show that both data can be simultaneously fitted better with such a double-action dark matter particle. We use an existing neutrino mass model in literature to illustrate the idea.

  15. Regular multivitamin supplement use, single nucleotide polymorphisms in ATIC, SHMT2 and SLC46A1 and risk of ovarian carcinoma

    Directory of Open Access Journals (Sweden)

    Linda E Kelemen

    2012-03-01

    Full Text Available ATIC, SHMT2 and SLC46A1 have essential roles in one-carbon (1-C transfer. The authors examined whether associations between ovarian carcinoma and 15 variants in these genes are modified by regular multivitamin use, a source of 1-C donors, among Caucasian participants from two U.S. case control studies. Using a phased study design, variant-by-multivitamin interactions were tested, and associations between variants and ovarian carcinoma were reported stratified by multivitamin supplement use. Per-allele risk associations were modified by multivitamin use at six variants among 655 cases and 920 controls (Phase 1. In a larger sample of 968 cases and 1,265 controls (Phases 1 and 2, interactions were significant (P≤0.03 for two variants, particularly among regular multivitamin users: ATIC rs7586969 (odds ratio [OR]=0.7, 95% confidence interval [CI]=0.6-0.9 and ATIC rs16853834 (OR=1.5, 95% CI=1.1-2.0. The two ATIC SNPs did not share the same haplotype; however, the haplotypes they comprised mirrored their SNP risk associations among regular multivitamin supplement users. A multi-variant analysis was also performed by comparing the observed likelihood ratio test statistic from adjusted models with and without the two ATIC variant-by-multivitamin interaction terms with a null distribution of test statistics generated by permuting case status 10,000 times. The corresponding observed P value of 0.001 was more extreme than the permutation-derived P value of 0.009, suggesting rejection of the null hypothesis of no association. In summary, there is little statistical evidence that the 15 variants are independently associated with risk of ovarian carcinoma. However, the statistical interaction of ATIC variants with regular multivitamin intake, when evaluated at both the SNP and gene level, may support these findings as relevant to ovarian health and disease processes.

  16. New twist on excited dark matter: Implications for INTEGRAL, PAMELA/ATIC/PPB-BETS, DAMA

    International Nuclear Information System (INIS)

    We show that the 511 keV gamma ray excess observed by INTEGRAL/SPI can be more robustly explained by exciting dark matter (DM) at the center of the galaxy, if there is a peculiar spectrum of DM states χ0, χ1, and χ2, with masses M0∼500 GeV, M1 0+2me, and M2=M1+δM > or approx. M0+2me. The small mass splitting δM should be 1 is stable but can be excited to χ2 by low-velocity DM scatterings near the Galactic center, which are Sommerfeld-enhanced by two of the 100 MeV gauge boson exchanges. The excited state χ2 decays to χ0 and nonrelativistic e+e-, mediated by the third gauge boson, which mixes with the photon and Z. Although such a small 100 keV splitting has been independently proposed for explaining the DAMA annual modulation through the inelastic DM mechanism, the need for stability of χ1 (and hence sequestering it from the standard model) implies that our scenario cannot account for the DAMA signal. It can, however, address the PAMELA/ATIC positron excess via DM annihilation in the galaxy, and it offers the possibility of a sharper feature in the ATIC spectrum relative to previously proposed models. The data are consistent with three new gauge bosons, whose couplings fit naturally into a broken SU(2) gauge theory where the DM is a triplet of the SU(2). We propose a simple model in which the SU(2) is broken by new Higgs triplet and 5-plet vacuum expectation values, giving rise to the right spectrum of DM and mixing of one of the new gauge bosons with the photon and Z boson. A coupling of the DM to a heavy Z' may also be necessary to get the right relic density and PAMELA/ATIC signals.

  17. Coarse-grained simulation of lipid vesicles with ``n-atic'' orientational order

    Science.gov (United States)

    Geng, Jun; Selinger, Jonathan; Selinger, Robin

    2012-02-01

    We perform coarse-grained simulation studies of fluid lipid vesicles with in-plane ``n-atic'' orientational order associated with the shape of lipid head group, to test the theoretical predictions of Park, Lubensky and MacKintosh [1] for resulting vesicle shape and defect structures. Our simulation model uses a single layer coarse-grained implicit-solvent approach proposed by Yuan et al [2], with addition of an extra vector degree of freedom representing in-plane orientational order. We carry out simulation studies for n=1 to 6, examining in each case the spatial distribution of defects and resulting deformation of the vesicle. An initially spherical vesicle (genus zero) with n-atic order has a ground state with 2n vortices of strength 1/n, as expected, but the observed equilibrium shapes are sometimes quite different from those predicted theoretically. For the n=1 case, we find that the vesicle may become trapped in a disordered, long-lived metastable state with extra +/- defects whose pair-annihilation is inhibited by local changes in membrane curvature, and thus may never reach its predicted ground state. [4pt] [1] J. Park, T. C. Lubensky, and F. C. MacKintosh, Europhys. Lett. 20, 279 (1992)[0pt] [2] H. Yuan, C. Huang, Ju Li, G. Lykotrafitis, and S. Zhang, Phys. Rev. E 82, 011905 (2010)

  18. Electron cloud observations: a retrospective

    International Nuclear Information System (INIS)

    A growing number of observations of electron cloud effects (ECEs) have been reported in positron and proton rings. Low-energy, background electrons ubiquitous in high-intensity particle accelerators. Amplification of electron cloud (EC) can occur under certain operating conditions, potentially giving rise to numerous effects that can seriously degrade accelerator performance. EC observations and diagnostics have contributed to a better understanding of ECEs, in particular, details of beam-induced multipacting and cloud saturation effects. Such experimental results can be used to provide realistic limits on key input parameters for modeling efforts and analytical calculations to improve prediction capability. Electron cloud effects are increasingly important phenomena in high luminosity, high brightness, or high intensity machines - Colliders, Storage rings, Damping rings, Heavy ion beams. EC generation and instability modeling increasingly complex and benchmarked against in situ data: (delta), (delta)0, photon reflectivity, and SE energy distributions important. Surface conditioning and use of solenoidal windings in field-free regions are successful cures: will they be enough? What are new observations and how do they contribute to body of work and understanding physics of EC?

  19. Optical electronics for meteor observations

    Science.gov (United States)

    Shafiev, R. I.; Mukhamednazarov, S.; Atamas, I. A.

    1987-01-01

    Spectral observations of meteors have been carried out for several years using an optical electronics facility. Interest has centered on faint meteors and their trails in the period of intensive meteor showers. Over 800 meteors were registered during the observation period, with spectrograms obtained for 170 of these. A total of 86 meteors were photographed from two sites and for 25 of these spectrograms of the meteors as well as their trails were obtained. All meteors have undergone routine processing in order to determine atmospheric characteristics. Results are discussed.

  20. Observing electron motion in molecules

    International Nuclear Information System (INIS)

    We study analytically the possibility for monitoring electron motion in a molecule using two ultrashort laser pulses. The first prepares a coherent superposition of two electronic molecular states whereas the second (attosecond pulse) photoionizes the molecule. We show that interesting information about electron dynamics can be obtained from measurement of the photoelectron spectra as a function of the time delay between two pulses. In particular, asymmetries in photoelectron angular distribution provide a simple signature of the electron motion within the initial time-dependent coherently coupled two molecular states. Both asymmetries and electron spectra show very strong two-centre interference patterns. We illustrate these effects using as an example a dissociating hydrogen molecular ion probed by the attosecond pulses

  1. Natural geometric representation for electron local observables

    International Nuclear Information System (INIS)

    An existence of the quartic identities for the electron local observables that define orthogonality relations for the 3D quantities quadratic in the electron observables is found. It is shown that the joint solution of the quartic and bilinear identities for the electron observables defines a unique natural representation of the observables. In the natural representation the vector type electron local observables have well-defined fixed positions with respect to a local 3D orthogonal reference frame. It is shown that the natural representation of the electron local observables can be defined in six different forms depending on a choice of the orthogonal unit vectors. The natural representation is used to determine the functional dependence of the electron wave functions on the local observables valid for any shape of the electron wave packet. -- Highlights: •Quartic identities that define the orthogonality relations for the electron local observables are found. •Joint solution of quartic and bilinear identities defines a unique natural representation of the electron local observables. •Functional dependence of the electron wave functions on the electron local observables is determined

  2. Observations of Obliquely Propagating Electron Bernstein Waves

    DEFF Research Database (Denmark)

    Armstrong, R. J.; Juul Rasmussen, Jens; Stenzel, R. L.;

    1981-01-01

    Plane electron Bernstein waves propagating obliquely to the magnetic field are investigated. The waves are excited by a plane grid antenna in a large volume magnetoplasma. The observations compare favorably with the predictions of the linear dispersion relation.......Plane electron Bernstein waves propagating obliquely to the magnetic field are investigated. The waves are excited by a plane grid antenna in a large volume magnetoplasma. The observations compare favorably with the predictions of the linear dispersion relation....

  3. Observation of Laser Wakefield Acceleration of Electrons

    CERN Document Server

    Amiranoff, F; Bernard, D; Cros, B; Descamps, D; Dorchies, F; Jacquet, F; Malka, V; Marqués, J R; Matthieussent, G; Miné, P; Modena, A; Mora, P; Morillo, J; Najmudin, Z

    1998-01-01

    The acceleration of electrons injected in a plasma wave generated by the laser wakefield mechanism has been observed. A maximum energy gain of 1.6~MeV has been measured and the maximum longitudinal electric field is estimated to 1.5~GV/m. The experimental data agree with theoretical predictions when 3D effects are taken into account. The duration of the plasma wave inferred from the number of accelerated electrons is of the order of 1~ps.

  4. MAXIS Balloon Observations of Electron Microburst Precipitation

    Science.gov (United States)

    Millan, R. M.; Hunter, A. E.; McCarthy, M. P.; Lin, R. P.; Smith, D. M.

    2003-12-01

    Quantifying and understanding losses is an integral part of understanding relativistic electron variability in the radiation belts. SAMPEX observations indicate that electron microburst precipitation is a major loss mechanism during active periods; the loss of relativistic electrons during a six hour period due to microburst precipitation was recently estimated to be comparable to the total number of trapped electrons in the outer zone (Lorentzen et al., 2001). Microburst precipitation was first observed from a balloon (Anderson and Milton, 1964), but these early measurements were only sensitive to MAXIS 2000 long duration balloon campaign. MAXIS was launched from McMurdo Station in Antarctica carrying a germanium spectrometer, a BGO scintillator and two X-ray imagers designed to measure the bremsstrahlung produced by precipitating electrons. The balloon circumnavigated the south pole in 18 days covering magnetic latitudes ranging from 58o-90o South. During the week following a moderate geomagnetic storm (with Dst reaching -91 nT), MAXIS detected a total of over 16 hours of microburst precipitation. We present high resolution spectra obtained with the MAXIS germanium spectrometer which allow us to determine the precipitating electron energy distribution. The precipitating distribution will then be compared to the trapped distribution measured by the GPS and LANL satellites. We also examine the spatial distribution of the precipitation.

  5. Electron Cloud observation in the LHC

    CERN Document Server

    Rumolo, G; Baglin, V; Bartosik, H; Biancacci, N; Baudrenghien, P; Bregliozzi, G; Chiggiato, P; Claudet, S; De Maria, R; Esteban-Muller, J; Favier, M; Hansen, C; Höfle, W; Jimenez, J M; Kain, V; Lanza, G; Li, K S B; Maury Cuna, G H I; Métral, E; Papotti, G; Pieloni, T; Roncarolo, F; Salvant, B; Shaposhnikova, E N; Steinhagen, R J; Tavian, L J; Valuch, D; Venturini Delsolaro, W; Zimmermann, F; Iriso, U; Dominguez, O; Koukovini-Platia, E; Mounet, N; Zannini, C; Bhat, C M

    2011-01-01

    Operation of LHC with bunch trains at different spacings has revealed the formation of an electron cloud inside the machine. The main observations of electron cloud build up are the pressure rise measured at the vacuum gauges in the warm regions, as well as the increase of the beam screen temperature in the cold regions due to an additional heat load. The effects of the electron cloud were also visible as instability and emittance growth affecting the last bunches of longer trains, which could be improved running with higher chromaticity or larger transverse emittances. A summary of the 2010 and 2011 observations and measurements and a comparison with models will be presented. The efficiency of scrubbing to improve the machine running performance will be briefly discussed.

  6. Observations on electron irradiation damage in vanadium

    International Nuclear Information System (INIS)

    Electron radiation damage in the form of dislocation loops has been introduced and observed simultaneously in vanadium irradiated at room temperature and at 3750C with the beam of the high voltage electron microscope. Loop concentrations of up to about 1020m-3 and typical loop sizes up to about 140 nm were observed at room temperature. The growth kinetics of the loops fitted the form d varies as tsup(n), where d is the loop diameter, t is the irradiation time and exponent n was found to be about 2/3. The nucleation time of the loops was found with the model due to Brown et al (Phil. Mag.; 19:721 (1969)) to be much less than 1 sec. Only 0.03 to 0.07% of the beam-induced point defects were retained in the foil, the foil surfaces acting as an important, but not the predominant, interstitial sink. The morphology of the electron damage at 3750C suggests that beam-induced vacancies may be influencing the details of loop nucleation and/or growth at this temperature. The calculated values of electron radiation hardening in vanadium were found to be less than corresponding values for neutron irradiated vanadium by factors of up to about ten. This discrepancy is attributed to the experimental difficulty in resolving small defect clusters by electron microscopy. (author)

  7. Real-time observations with electron microscopy

    Directory of Open Access Journals (Sweden)

    Eric A. Stach

    2008-01-01

    Full Text Available Dynamic transmission electron microscopy allows observation of changes in both the structure and properties of materials at resolutions from the nanometer to the Ångström. Here I review four significant developments in instrumentation and technique that are pushing the boundaries of these experiments, including new optics, new experimental geometries, new ways of imaging solids in liquid and gaseous environments, and developments in ultrafast imaging. These advances will significantly improve our understanding in many areas of materials science, nanoscience, and biological function.

  8. The Cosmic-Ray Positron and Electron Excess: An Experimentalist's Point of View

    OpenAIRE

    Schubnell, Michael

    2009-01-01

    The recent report by the PAMELA team of the observed rise in the cosmic-ray positron fraction above a few GeV and the report of an excess of cosmic-ray electrons around a few hundred GeV by the ATIC collaboration has resulted in a flurry of publications interpreting these observations either as a possible signature from the decay of dark matter or as a contribution from isolated astrophysical sources. While those interpretations are scientifically exciting, the possibility that measurements a...

  9. Enhanced Dark Matter Annihilation Rate for Positron and Electron Excesses from Q-ball Decay

    OpenAIRE

    McDonald, John

    2009-01-01

    We show that Q-ball decay in Affleck-Dine baryogenesis models can account for dark matter when the annihilation cross-section is sufficiently enhanced to explain the positron and electron excesses observed by PAMELA, ATIC and PPB-BETS. For Affleck-Dine baryogenesis along a d = 6 flat direction, the reheating temperature is approximately 30 GeV and the Q-ball decay temperature is in the range 10-100 MeV. The LSPs produced by Q-ball decay annihilate down to the observed dark matter density if t...

  10. Electron cloud observations through synchronous phase measurements

    CERN Document Server

    Esteban Müller, J F; Mastoridis, T; Papotti, G; Shaposhnikova, E; Valuch, D

    2012-01-01

    The electron cloud in vacuum pipes of accelerators of positively charged particle beams causes a beam energy loss which could be estimated from the synchronous phase. Measurements done with beams of 75 ns, 50 ns, and 25 ns bunch spacing in the LHC for some fills in 2010 and 2011 show that the average energy loss depends on the total beam intensity in the ring. Later measurements during the scrubbing run with 50 ns beams show the reduction of the electron cloud due to scrubbing. Finally, measurements of the individual bunch phase give us information about the electron cloud build-up inside the batch and from batch to batch.

  11. Observation of electron density using reflectometry

    Energy Technology Data Exchange (ETDEWEB)

    Itakura, A.; Goto, N.; Katoh, M. [University of Tsukuba, Plasma Research Center, Tsukuba, Ibaraki (JP)] [and others

    2001-05-01

    Two types of microwave reflectometer are installed in the GAMMA 10 device for electron density measurement. One is an ultrashort-pulse reflectometer in an ordinary wave mode. An impulse generator, 65 ps full-width at half maximum is used as its microwave source. The five-channel receiver system measures the time-of-flight. Their center frequencies are 7, 8, 9, 10 and 11 GHz. Location of reflected point is calculated from the time-of-flight. An electron density profile is reconstructed. The other is a fast frequency-sweep reflectometer in an extraordinary wave mode. A hyperabrupt varactor-tuned oscillator is used and is swept from 11.5 GHz to 18 GHz. Beat frequency between the injected wave and the reflected wave depends on the path length and the sweep frequency. It is adjusted not to match the ICRF heating frequency. A density profile is also reconstructed from the phase difference. This system has a rather simple receiving system. (author)

  12. Observation of muon-electron pairs in neutrino reactions

    International Nuclear Information System (INIS)

    The present thesis describes the observation of muon-electron pairs in neutrino reactions. This experiment was performed using an optical multiplate spark chamber in the broad band neutrino beam of the CERN proton synchrotron. (orig.)

  13. Deducing Electron Properties From Hard X-Ray Observations

    OpenAIRE

    Kontar, E.P.; Brown, J. C.; Emslie, A. G.; Hajdas, W.; Holman, G. D.; Hurford, G. J.; Kasparova, J.; Mallik, P. C. V.; Massone, A. M.; McConnell, M. L.; M. Piana; Prato, M.; Schmahl, E. J.; Suarez-Garcia, E.

    2011-01-01

    X-radiation from energetic electrons is the prime diagnostic of flare-accelerated electrons. The observed X-ray flux (and polarization state) is fundamentally a convolution of the cross-section for the hard X-ray emission process(es) in question with the electron distribution function, which is in turn a function of energy, direction, spatial location and time. To address the problems of particle propagation and acceleration one needs to infer as much information as possible on this electron ...

  14. Observing the motion of electrons in atoms and molecules

    International Nuclear Information System (INIS)

    The dynamic electronic structure of atoms and molecules can be directly observed by means of the (e,2e) reaction, which measures the distribution of energies and momenta of two electrons in coincidence after a knockout reaction initiated by an electron beam of known momentum incident on a molecular gas target. The molecular state for each event is identified by the electron separation energy. The recoil momentum for each event is known from the difference of measured initial and final momenta. It has been verified that values of this momentum are equal under suitable conditions to the momentum of the electron in the target immediately before knockout. Thus the spherically-averaged electron momentum distribution for each molecular orbital is measured. This is directly related to molecular orbitals calculated by the methods of quantum chemistry. Properties of different types of molecules obtained by this method are discussed

  15. Deducing Electron Properties from Hard X-ray Observations

    Science.gov (United States)

    Kontar, E. P.; Brown, J. C.; Emslie, A. G.; Hajdas, W.; Holman, G. D.; Hurford, G. J.; Kašparová, J.; Mallik, P. C. V.; Massone, A. M.; McConnell, M. L.; Piana, M.; Prato, M.; Schmahl, E. J.; Suarez-Garcia, E.

    2011-09-01

    X-radiation from energetic electrons is the prime diagnostic of flare-accelerated electrons. The observed X-ray flux (and polarization state) is fundamentally a convolution of the cross-section for the hard X-ray emission process(es) in question with the electron distribution function, which is in turn a function of energy, direction, spatial location and time. To address the problems of particle propagation and acceleration one needs to infer as much information as possible on this electron distribution function, through a deconvolution of this fundamental relationship. This review presents recent progress toward this goal using spectroscopic, imaging and polarization measurements, primarily from the Reuven Ramaty High Energy Solar Spectroscopic Imager ( RHESSI). Previous conclusions regarding the energy, angular (pitch angle) and spatial distributions of energetic electrons in solar flares are critically reviewed. We discuss the role and the observational evidence of several radiation processes: free-free electron-ion, free-free electron-electron, free-bound electron-ion, photoelectric absorption and Compton backscatter (albedo), using both spectroscopic and imaging techniques. This unprecedented quality of data allows for the first time inference of the angular distributions of the X-ray-emitting electrons and improved model-independent inference of electron energy spectra and emission measures of thermal plasma. Moreover, imaging spectroscopy has revealed hitherto unknown details of solar flare morphology and detailed spectroscopy of coronal, footpoint and extended sources in flaring regions. Additional attempts to measure hard X-ray polarization were not sufficient to put constraints on the degree of anisotropy of electrons, but point to the importance of obtaining good quality polarization data in the future.

  16. Cluster PEACE observations of electrons during magnetospheric flux transfer events

    Directory of Open Access Journals (Sweden)

    C. J. Owen

    Full Text Available During the first quarter of 2001 the apogees of the Cluster spacecraft quartet precessed through midday local times. This provides the first opportunity for 4 spacecraft studies of the bow shock, magnetosheath and the dayside magnetopause current layer and boundary layers. In this paper, we present observations of electrons in the energy range ~ 10 eV–26 keV made by the Plasma Electron And Current Experiment (PEACE located just inside the magnetopause boundary, together with supporting observations by the Flux Gate Magnetometer (FGM. During these observations, the spacecraft have separations of ~ 600 km. This scale size is of the order or less than the typical size of flux transfer events (FTEs, which are expected to be observed following bursts of reconnection on the dayside magnetopause. We study, in detail, the 3-D configuration of electron populations observed around a series of enhancements of magnetosheath-like electrons which were observed within the magnetosphere on 2 February 2001. We find that individual spacecraft observe magnetic field and electron signatures that are consistent with previous observations of magnetospheric FTEs. However, the differences in the signatures between spacecraft indicate that these FTEs have substructure on the scale of the spacecraft separation. We use these differences and the timings of the 4 spacecraft observations to infer the motions of the electron populations and thus the configuration of these substructures. We find that these FTEs are moving from noon towards dusk. The inferred size and speed of motion across the magnetopause, in one example, is ~ 0.8 RE and ~ 70 km s-1 respectively. In addition, we observe a delay in and an extended duration of the signature at the spacecraft furthest from the magnetopause. We discuss the implications of these 4 spacecraft observations for the structure of these FTEs. We suggest that these may include a compression of the closed

  17. High Energy Electron Signals from Dark Matter Annihilation in the Sun

    Energy Technology Data Exchange (ETDEWEB)

    Schuster, Philip; /SLAC; Toro, Natalia; /Stanford U., ITP; Weiner, Neal; Yavin, Itay; /New York U., CCPP

    2012-04-09

    In this paper we discuss two mechanisms by which high energy electrons resulting from dark matter annihilations in or near the Sun can arrive at the Earth. Specifically, electrons can escape the sun if DM annihilates into long-lived states, or if dark matter scatters inelastically, which would leave a halo of dark matter outside of the sun. Such a localized source of electrons may affect the spectra observed by experiments with narrower fields of view oriented towards the sun, such as ATIC, differently from those with larger fields of view such as Fermi. We suggest a simple test of these possibilities with existing Fermi data that is more sensitive than limits from final state radiation. If observed, such a signal will constitute an unequivocal signature of dark matter.

  18. First dedicated observations of runaway electrons in the COMPASS tokamak

    Directory of Open Access Journals (Sweden)

    Vlainić Miloš

    2015-06-01

    Full Text Available Runaway electrons present an important part of the present efforts in nuclear fusion research with respect to the potential damage of the in-vessel components. The COMPASS tokamak a suitable tool for the studies of runaway electrons, due to its relatively low vacuum safety constraints, high experimental flexibility and the possibility of reaching the H-mode D-shaped plasmas. In this work, results from the first experimental COMPASS campaign dedicated to runaway electrons are presented and discussed in preliminary way. In particular, the first observation of synchrotron radiation and rather interesting raw magnetic data are shown.

  19. What would it Mean to Directly Observe Electrons?

    Directory of Open Access Journals (Sweden)

    David Mitsuo Nixon

    2004-06-01

    Full Text Available In this paper it is argued that a proper understanding of the justification of perceptual beliefs leaves open the possibility that normal humans, unaided by microscopes, could genuinely know, by direct observation, of the existence of a theoretical entity like an electron. A particular theory of justification called perceptual responsibilism is presented. If successful, this kind of view would undercut one line of argument that has been given (for example, by Bas van Fraassen in support of scientific anti-realism. Various objections to the idea that electrons can be directly observed are also considered.

  20. Observations of Jovian electron events in the vicinity of earth

    International Nuclear Information System (INIS)

    A number of quiet-time enhancements in the intensity of interplanetary electrons over the range 0.22approximately-less-thanEapproximately-less-than2.5 MeV have been observed with the JHU/APL experiment on the earth orbiting near-circular (approx.32 by 38 R/sub e/) Explorer 47 (IMP-7) spacecraft during 1973 and 1974. These quiet-time increases last from approx.3 to approx.20 days and are observed both in the interplanetary medium and inside the magnetotail. The main features of the observations are as follows: The increases occur during the first 200 days of 1973 and from day approx.20 to approx.230 in 1974. The intensity onset is relatively slow (1 to 2 days) when compared to either solar electron events or magnetospheric electron bursts. The electron energy spectrum is quite distinct from that of solar or magnetospheric electrons and is consistent with γ=1.3+-0.3 in a differential power law spectrum. Significant anisotropies are present, several days after the onset of the increase. Some distinct fluctuations appear in some of the intensity profiles, suggesting the presence of a modulated source. The appearance of these enhancements occurs during times when the earth could be magnetically connected to the magnetosphere of Jupiter, assuming typical solar wind velocities. Further, the energy spectrum is not unlike that observed by instrumentation on Pioneer 10 in the vicinity of Jupiter. On the basis of the above it is reasonable to suggest that the observed electrons may be of Jovian origin. The implications of these results are discussed, and it is suggested that interconnection between the interplanetary and Jovian magnetic field takes place. Using this concept, a length of the Jovian magnetotail of approx.4.6 AU is computed

  1. Cluster PEACE observations of electrons of spacecraft origin

    Directory of Open Access Journals (Sweden)

    S. Szita

    Full Text Available The two PEACE (Plasma Electron And Current Experiment sensors on board each Cluster spacecraft sample the electron velocity distribution across the full 4 solid angle and the energy range 0.7 eV to 26 keV with a time resolution of 4 s. We present high energy and angular resolution 3D observations of electrons of spacecraft origin in the various environments encountered by the Cluster constellation, including a lunar eclipse interval where the spacecraft potential was reduced but remained positive, and periods of ASPOC (Active Spacecraft POtential Control operation which reduced the spacecraft potential. We demonstrate how the spacecraft potential may be found from a gradient change in the PEACE low energy spectrum, and show how the observed spacecraft electrons are confined by the spacecraft potential. We identify an intense component of the spacecraft electrons with energies equivalent to the spacecraft potential, the arrival direction of which is seen to change when ASPOC is switched on. Another spacecraft electron component, observed in the sunward direction, is reduced in the eclipse but unaffected by ASPOC, and we believe this component is produced in the analyser by solar UV. We find that PEACE anodes with a look direction along the spacecraft surfaces are more susceptible to spacecraft electron contamination than those which look perpendicular to the surface, which justifies the decision to mount PEACE with its field-of-view radially outward rather than tangentially.

    Key words. Magnetosheric physics (general or miscellaneous Space plasma physics (spacecraft sheaths, wakes, charging

  2. A New Approach for Direct Observation of Superconducting Electrons

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    @@ ASino-Japanese research team has succeeded in observing the superconducting electron directly by the photoemission spectroscopy with the highest yet resolution (360 μeV).Based on this, the researchers say,they will be able to solve problems regarding the exotic superconducting mechanism.

  3. Coordinated ATS 5 electron flux and simultaneous auroral observations

    International Nuclear Information System (INIS)

    All-sky camera (ASCA) observations were made at the field line conjugate of the ATS 5 satellite. The field of view of these cameras covered the region of the magnetosphere from L=5 to L=11 at the approximate longitude of the ATS field line conjugate. With this coverage, definite statements can be made concerning the correlation of the auroras observed by the ASCA's and the magnetospheric trapped fluxes. In general, auroral forms are not simply correlated with the synchronous altitude electron fluxes. The presence of hot plasma at the ATS 5 satellite is a necessary but not sufficient condition for the occurrence of local auroras. On quiet days the hot plasma does not penetrate into the magnetosphere far enough to reach the ATS 5 orbit. Under these conditions, no auroras are observed at the field line conjugate, but auroras are usually observed on higher-latitude field lines. On more disturbed days, auroral arcs are observed at lower latitudes when the plasma sheet penetrates into the ATS 5 orbit. There is no general correlation between the intensity of the trapped electron fluxes observed by ATS 5 and the intensity of auroras observed by the ASCA's. Auroral displays exhibit very fast fluctuations, whereas the ATS 5 electron fluxes change on a much slower time scale. However, significant qualitative correlation between the ASCA data and the trapped fluxes is observed when a local plasma injection event occurs near ATS 5. The clearest signature of the injection event is magnetic and is most pronounced as a recovery of a negative bay in the north-south component of the field at the ATS 5. The local injection generally produces structured auroras such as breakup events and sometimes westward-traveling surges. A significant correlation is observed with the intensification of a diffuse uniform glow accompanying the structured auroral activity

  4. Benchmarking headtail with electron cloud instabilities observed in the LHC

    CERN Document Server

    Bartosik, H; Iadarola, G; Papaphilippou, Y; Rumolo, G

    2013-01-01

    After a successful scrubbing run in the beginning of 2011, the LHC can be presently operated with high intensity proton beams with 50 ns bunch spacing. However, strong electron cloud effects were observed during machine studies with the nominal beam with 25 ns bunch spacing. In particular, fast transverse instabilities were observed when attempting to inject trains of 48 bunches into the LHC for the first time. An analysis of the turn-by-turn bunch-bybunch data from the transverse damper pick-ups during these injection studies is presented, showing a clear signature of the electron cloud effect. These experimental observations are reproduced using numerical simulations: the electron distribution before each bunch passage is generated with PyECLOUD and used as input for a set of HEADTAIL simulations. This paper describes the simulation method as well as the sensitivity of the results to the initial conditions for the electron build-up. The potential of this type of simulations and their clear limitations on th...

  5. Study of the NWC electrons belt observed on DEMETER Satellite

    CERN Document Server

    Li, Xinqiao; Wang, Ping; Wang, Huanyu; Lu, Hong; Zhang, Xuemin; Huang, Jianping; Shi, Feng; Yu, Xiaoxia; Xu, Yanbing; Meng, Xiangcheng; Wang, Hui; Zhao, Xiaoyun; Parrot, M

    2010-01-01

    We analyzed the data from 2007 to 2008, which is observed by IDP onboard DEMETER satellite, during ten months of NWC working and seven months of NWC shutdown. The characteristic of the space instantaneous electron belts, which come from the influence of the VLF transmitted by NWC, is studied comprehensively. The main distribution region of the NWC electron belts and the flux change are given. We also studied the distribution characteristic of the average energy spectrum in different magnetic shell at the height of DEMETER orbit and the difference of the average energy spectrum of the electrons in the drift loss-cone between day and night. As a result, the powerful power of NWC transmitter and the 19.8 kHz narrow bandwidth VLF emission not only created a momentary electrons enhancement region, which strides 180 degree in them longitude direction and from 1.6 to 1.9 in L value, with the rise of the electrons flux reaching to 3 orders of magnitude mostly, but also induced the enhancement or loss of electrons in ...

  6. Observations of electron vorticity in the inner plasma sheet

    Science.gov (United States)

    Gurgiolo, C.; Goldstein, M. L.; Viñas, A. F.; Matthaeus, W. H.; Fazakerley, A. N.

    2011-09-01

    From a limited number of observations it appears that vorticity is a common feature in the inner plasma sheet. With the four Cluster spacecraft and the four PEACE instruments positioned in a tetrahedral configuration, for the first time it is possible to directly estimate the electron fluid vorticity in a space plasma. We show examples of electron fluid vorticity from multiple plasma sheet crossings. These include three time periods when Cluster passed through a reconnection ion diffusion region. Enhancements in vorticity are seen in association with each crossing of the ion diffusion region.

  7. Electron microscope observation of single - crystalline beryllium thin foils

    International Nuclear Information System (INIS)

    Thin foils prepared from single crystalline beryllium simples deformed at room temperature, have been observed by transmission electron microscopy. The various deformation modes have been investigated separately, from their early stages and their characteristic dislocation configurations have been observed. Basal slip is characterized at is outset by the presence of numerous dipoles and elongated prismatic loops. More pronounced cold work leads to the formation of dislocation tangles and bundles which eventually give a cellular structure. Prismatic slip begins by the cross-slip of dislocations from the basal plane into the prismatic plane. A cellular structure is equally observed in heavily deformed samples. Sessile dislocations have been observed in twin boundaries; they are produced by reactions between slip dislocations and twin dislocations. Finally, the study of samples quenched from 1100 deg. C and annealed at 200 deg. C has shown that the observed loops lie in prismatic planes and have a Burgers vector b 1/3. (authors)

  8. Electron cloud observations at the ISIS Proton Synchrotron

    CERN Document Server

    Pertica, A

    2013-01-01

    The build up of electron clouds inside a particle accelerator vacuum chamber can produce strong transverse and longitudinal beam instabilities which in turn can lead to high levels of beam loss often requiring the accelerator to be run below its design specification. To study the behaviour of electron clouds at the ISIS Proton Synchrotron, a Micro-Channel Plate (MCP) based electron cloud detector has been developed. The detector is based on the Retarding Field Analyser (RFA) design and consists of a retarding grid, which allows energy analysis of the electron signal, and a MCP assembly placed in front of the collector plate. The MCP assembly provides a current gain over the range 300 to 25K, thereby increasing the signal to noise ratio and dynamic range of the measurements. This paper presents the first electron cloud observations at the ISIS Proton Synchrotron. These results are compared against signals from a beam position monitor and a fast beam loss monitor installed at the same location.

  9. Validation of electron density and temperature observed by DEMETER

    OpenAIRE

    Kakinami, Yoshihiro; KAMOGAWA,Masashi(Department of physics, Tokyo Gakugei University); Onishi, Tatsuo; Mochizuki, Kaori; Lebreton, Jean-Pierre; Watanabe, Shigeto; Yamamoto, Masa-yuki; MOGI, Toru

    2013-01-01

    Measuring electron density (Ne) and temperature (Te) using a DC Langmuir probe in the ionosphere is very often degraded by the electrode contamination. In order to examine the accuracy of DEMETER observations, we compared DEMETER Ne and Te with several other satellites observations and IRI2012 as reference data. DEMETER Ne and Te show well-known dependencies on the solar irradiance except for the range of F10.7 > 100. However, DEMETER Ne are about 70% lower than those of IRI in day time data ...

  10. Observation of relativistic electron precipitation during a rapid decrease of trapped relativistic electron flux

    Science.gov (United States)

    Millan, R. M.; Lin, R. P.; Smith, D. M.; McCarthy, M. P.

    2007-05-01

    We present the first quantitative comparison of precipitating and geomagnetically trapped electron flux during a relativistic electron depletion event. Intense bremsstrahlung X-ray emission from relativistic electron precipitation was observed on January 19-20, 2000 (21:20-00:45 UT) by the germanium spectrometer on the MAXIS balloon payload (-7.2 to -9.3 E, 74 S corresponding to IGRF L = 4.7, 1920-2240 MLT). A rapid decrease in the geosynchronous >2 MeV electron flux was simultaneously observed at GOES-8 and GOES-10, and between 0.34-3.6 MeV by GPS ns33 at L = 4.7. The observations show that electrons were lost to the atmosphere early in the flux depletion event, during a period of magnetic field stretching in the tail. The observed X-ray spectrum is well modeled by an exponential distribution of precipitating electrons with an e-folding energy of 290 keV and a lower-energy cut-off of 400 keV. The duration of the event implies precipitation extended over at least 3 hours of MLT, assuming a source fixed in local time. Comparison of the precipitation rate with the flux decrease measured at GPS implies that the loss cone flux was only ~1% of the equatorial flux. However, precipitation is sufficient to account for the rate of flux decrease if it extended over 2-3 hours of local time.

  11. Dark matter model selection and the ATIC/PPB-BETS anomaly

    International Nuclear Information System (INIS)

    We argue that we may be able to sort out dark matter models in which electrons are generated through the annihilation and/or decay of dark matter, by using a fact that the initial energy spectrum is reflected in the cosmic-ray electron flux observed at the Earth even after propagation through the Galactic magnetic field. To illustrate our idea we focus on three representative initial spectra: monochromatic, flat and double-peak ones. We find that those three cases result in significantly different energy spectra, which may be probed by the Fermi satellite in operation or an up-coming cosmic-ray detector such as CALET

  12. Dark Matter Model Selection and the ATIC/PPB-BETS anomaly

    OpenAIRE

    Chen, Chuan-Ren; Hamaguchi, Koichi; Nojiri, Mihoko M.; Takahashi, Fuminobu; Torii, Shoji

    2008-01-01

    We argue that we may be able to sort out dark matter models in which electrons are generated through the annihilation and/or decay of dark matter, by using a fact that the initial energy spectrum is reflected in the cosmic-ray electron flux observed at the Earth even after propagation through the galactic magnetic field. To illustrate our idea we focus on three representative initial spectra: (i)monochromatic (ii)flat and (iii)double-peak ones. We find that those three cases result in signifi...

  13. Observation of relativistic electron precipitation during a rapid decrease of trapped electron flux

    Science.gov (United States)

    Millan, R. M.; Lin, R. P.; Smith, D. M.; McCarthy, M. P.; Sample, J. G.; Shprits, Y.

    2006-12-01

    Rapid depletions of the trapped electron flux are often observed, and illustrate the important role played by losses in controlling electron variability in the radiation belts. The observed decrease may be partly due to adiabatic effects, but some of the electrons are lost either through magnetopause shadowing or through precipitation into Earth's atmosphere. On January 19, 2000, duskside precipitation was observed near the start of a rapid flux depletion event, during a period of magnetic field stretching in the tail. The observations were made with the germanium spectrometer on the MAXIS balloon payload and show that real losses were occurring during the initial decrease which has previously been attributed to purely adiabatic effects. A quantitative comparison of the precipitation rate with the change in electron flux measured at GPS implies that only ~1% of the loss cone was filled, however, precipitation alone is sufficient to account for the flux decrease if it extended over 2-3 hours of local time. We present these results and compare the observed loss rate with the theoretical loss rate expected for pitch-angle scattering by EMIC waves.

  14. Observation of Reactor Electron Antineutrino Disappearance at RENO

    International Nuclear Information System (INIS)

    The Reactor Experiment for Neutrino Oscillation (RENO) has obtained a definitive measurement of the smallest neutrino mixing angle of θ13 by observing the disappearance of electron antineutrinos emitted from a nuclear reactor, excluding the no-oscillation hypothesis at 4.9 σ. From the deficit, the best fit value of sin22θ13 is obtained as 0.113±0.013(stat.)±0.019(syst.) based on a rate-only analysis. Antineutrinos from six 2.8 GWth reactors at the Yonggwang Nuclear Power Plant in Korea, are detected by two identical detectors at 294 m and 1383 m, respectively, from the reactor array center. In the 229 day data-taking period between 11 August 2011 and 26 March 2012, the far (near) detector observed 17102 (154088) electron antineutrino candidate events with a background fraction of 5.5% (2.7%). The ratio of observed to expected numbers of the reactor antineutrinos in the far detector is 0.920±0.009(stat.)±0.014(syst.)

  15. Study of the NWC electrons belt observed on DEMETER Satellite

    OpenAIRE

    Li, Xinqiao; Ma, Yuqian; Ping WANG; Wang, Huanyu; Lu, Hong; Zhang, Xuemin; Huang, Jianping; Shi, Feng; Yu, Xiaoxia; Xu, Yanbing; Meng, Xiangcheng; Wang, Hui; Zhao, Xiaoyun; M. Parrot

    2010-01-01

    We analyzed observation data collected by the Instrument for the Detection of Particles (IDP) on board of DEMETER satellite during the period of total seventeen months in 2007 and 2008. In the meantime, the VLF transmitter located at NWC ground station was shutdown for seven months and working for total ten months. Our analysis, for the first time, revealed in details the transient properties of the space electrons induced by the man-made VLF wave emitted by the transmitter at NWC. First, we ...

  16. Energy Spectra of Abundant Nuclei of Primary Cosmic Rays from the Data of ATIC-2 Experiment: Final Results

    CERN Document Server

    Panov, A D; Ahn, H S; Bashinzhagyan, G L; Watts, J W; Wefel, J P; Wu, J; Ganel, O; Guzik, T G; Zatsepin, V I; Isbert, I; Kim, K C; Christl, M; Kouznetsov, E N; Panasyuk, M I; Seo, E S; Sokolskaya, N V; Chang, J; Schmidt, W K H; Fazely, A R

    2011-01-01

    The final results of processing the data from the balloon-born experiment ATIC-2 (Antarctica, 2002-2003) for the energy spectra of protons and He, C, O, Ne, Mg, Si, and Fe nuclei, the spectrum of all particles, and the mean logarithm of atomic weight of primary cosmic rays as a function of energy are presented. The final results are based on improvement of the methods used earlier, in particular, considerably increased resolution of the charge spectrum. The preliminary conclusions on the significant difference in the spectra of protons and helium nuclei (the proton spectrum is steeper) and the non-power character of the spectra of protons and heavier nuclei (flattening of carbon spectrum at energies above 10 TeV) are confirmed. A complex structure of the energy dependence of the mean logarithm of atomic weight is found.

  17. Observation of electron neutrino appearance in a muon neutrino beam.

    Science.gov (United States)

    Abe, K; Adam, J; Aihara, H; Akiri, T; Andreopoulos, C; Aoki, S; Ariga, A; Ariga, T; Assylbekov, S; Autiero, D; Barbi, M; Barker, G J; Barr, G; Bass, M; Batkiewicz, M; Bay, F; Bentham, S W; Berardi, V; Berger, B E; Berkman, S; Bertram, I; Bhadra, S; Blaszczyk, F D M; Blondel, A; Bojechko, C; Bordoni, S; Boyd, S B; Brailsford, D; Bravar, A; Bronner, C; Buchanan, N; Calland, R G; Caravaca Rodríguez, J; Cartwright, S L; Castillo, R; Catanesi, M G; Cervera, A; Cherdack, D; Christodoulou, G; Clifton, A; Coleman, J; Coleman, S J; Collazuol, G; Connolly, K; Cremonesi, L; Dabrowska, A; Danko, I; Das, R; Davis, S; de Perio, P; De Rosa, G; Dealtry, T; Dennis, S R; Densham, C; Di Lodovico, F; Di Luise, S; Drapier, O; Duboyski, T; Duffy, K; Dufour, F; Dumarchez, J; Dytman, S; Dziewiecki, M; Emery, S; Ereditato, A; Escudero, L; Finch, A J; Floetotto, L; Friend, M; Fujii, Y; Fukuda, Y; Furmanski, A P; Galymov, V; Gaudin, A; Giffin, S; Giganti, C; Gilje, K; Goeldi, D; Golan, T; Gomez-Cadenas, J J; Gonin, M; Grant, N; Gudin, D; Hadley, D R; Haesler, A; Haigh, M D; Hamilton, P; Hansen, D; Hara, T; Hartz, M; Hasegawa, T; Hastings, N C; Hayato, Y; Hearty, C; Helmer, R L; Hierholzer, M; Hignight, J; Hillairet, A; Himmel, A; Hiraki, T; Hirota, S; Holeczek, J; Horikawa, S; Huang, K; Ichikawa, A K; Ieki, K; Ieva, M; Ikeda, M; Imber, J; Insler, J; Irvine, T J; Ishida, T; Ishii, T; Ives, S J; Iyogi, K; Izmaylov, A; Jacob, A; Jamieson, B; Johnson, R A; Jo, J H; Jonsson, P; Jung, C K; Kaboth, A C; Kajita, T; Kakuno, H; Kameda, J; Kanazawa, Y; Karlen, D; Karpikov, I; Kearns, E; Khabibullin, M; Khotjantsev, A; Kielczewska, D; Kikawa, T; Kilinski, A; Kim, J; Kisiel, J; Kitching, P; Kobayashi, T; Koch, L; Kolaceke, A; Konaka, A; Kormos, L L; Korzenev, A; Koseki, K; Koshio, Y; Kreslo, I; Kropp, W; Kubo, H; Kudenko, Y; Kumaratunga, S; Kurjata, R; Kutter, T; Lagoda, J; Laihem, K; Lamont, I; Laveder, M; Lawe, M; Lazos, M; Lee, K P; Licciardi, C; Lindner, T; Lister, C; Litchfield, R P; Longhin, A; Ludovici, L; Macaire, M; Magaletti, L; Mahn, K; Malek, M; Manly, S; Marino, A D; Marteau, J; Martin, J F; Maruyama, T; Marzec, J; Mathie, E L; Matveev, V; Mavrokoridis, K; Mazzucato, E; McCarthy, M; McCauley, N; McFarland, K S; McGrew, C; Metelko, C; Mezzetto, M; Mijakowski, P; Miller, C A; Minamino, A; Mineev, O; Mine, S; Missert, A; Miura, M; Monfregola, L; Moriyama, S; Mueller, Th A; Murakami, A; Murdoch, M; Murphy, S; Myslik, J; Nagasaki, T; Nakadaira, T; Nakahata, M; Nakai, T; Nakamura, K; Nakayama, S; Nakaya, T; Nakayoshi, K; Naples, D; Nielsen, C; Nirkko, M; Nishikawa, K; Nishimura, Y; O'Keeffe, H M; Ohta, R; Okumura, K; Okusawa, T; Oryszczak, W; Oser, S M; Owen, R A; Oyama, Y; Palladino, V; Paolone, V; Payne, D; Pearce, G F; Perevozchikov, O; Perkin, J D; Petrov, Y; Pickard, L J; Pinzon Guerra, E S; Pistillo, C; Plonski, P; Poplawska, E; Popov, B; Posiadala, M; Poutissou, J-M; Poutissou, R; Przewlocki, P; Quilain, B; Radicioni, E; Ratoff, P N; Ravonel, M; Rayner, M A M; Redij, A; Reeves, M; Reinherz-Aronis, E; Retiere, F; Robert, A; Rodrigues, P A; Rojas, P; Rondio, E; Roth, S; Rubbia, A; Ruterbories, D; Sacco, R; Sakashita, K; Sánchez, F; Sato, F; Scantamburlo, E; Scholberg, K; Schwehr, J; Scott, M; Seiya, Y; Sekiguchi, T; Sekiya, H; Sgalaberna, D; Shiozawa, M; Short, S; Shustrov, Y; Sinclair, P; Smith, B; Smith, R J; Smy, M; Sobczyk, J T; Sobel, H; Sorel, M; Southwell, L; Stamoulis, P; Steinmann, J; Still, B; Suda, Y; Suzuki, A; Suzuki, K; Suzuki, S Y; Suzuki, Y; Szeglowski, T; Tacik, R; Tada, M; Takahashi, S; Takeda, A; Takeuchi, Y; Tanaka, H K; Tanaka, H A; Tanaka, M M; Terhorst, D; Terri, R; Thompson, L F; Thorley, A; Tobayama, S; Toki, W; Tomura, T; Totsuka, Y; Touramanis, C; Tsukamoto, T; Tzanov, M; Uchida, Y; Ueno, K; Vacheret, A; Vagins, M; Vasseur, G; Wachala, T; Waldron, A V; Walter, C W; Wark, D; Wascko, M O; Weber, A; Wendell, R; Wilkes, R J; Wilking, M J; Wilkinson, C; Williamson, Z; Wilson, J R; Wilson, R J; Wongjirad, T; Yamada, Y; Yamamoto, K; Yanagisawa, C; Yen, S; Yershov, N; Yokoyama, M; Yuan, T; Zalewska, A; Zalipska, J; Zambelli, L; Zaremba, K; Ziembicki, M; Zimmerman, E D; Zito, M; Zmuda, J

    2014-02-14

    The T2K experiment has observed electron neutrino appearance in a muon neutrino beam produced 295 km from the Super-Kamiokande detector with a peak energy of 0.6 GeV. A total of 28 electron neutrino events were detected with an energy distribution consistent with an appearance signal, corresponding to a significance of 7.3σ when compared to 4.92±0.55 expected background events. In the Pontecorvo-Maki-Nakagawa-Sakata mixing model, the electron neutrino appearance signal depends on several parameters including three mixing angles θ12, θ23, θ13, a mass difference Δm(32)(2) and a CP violating phase δ(CP). In this neutrino oscillation scenario, assuming |Δm(32)(2)|=2.4×10(-3)  eV(2), sin(2)θ(23)=0.5, and Δm322>0 (Δm(32)(2)<0), a best-fit value of sin(2)2θ(13)=0.140(-0.032)(+0.038) (0.170(-0.037)(+0.045)) is obtained at δ(CP)=0. When combining the result with the current best knowledge of oscillation parameters including the world average value of θ(13) from reactor experiments, some values of δ(CP) are disfavored at the 90% C.L. PMID:24580687

  18. Observation of Electron Neutrino Appearance in a Muon Neutrino Beam

    CERN Document Server

    Abe, K; Aihara, H; Akiri, T; Andreopoulos, C; Aoki, S; Ariga, A; Ariga, T; Assylbekov, S; Autiero, D; Barbi, M; Barker, G J; Barr, G; Bass, M; Batkiewicz, M; Bay, F; Bentham, S W; Berardi, V; Berger, B E; Berkman, S; Bertram, I; Bhadra, S; Blaszczyk, F d M; Blondel, A; Bojechko, C; Bordoni, S; Boyd, S B; Brailsford, D; Bravar, A; Bronner, C; Buchanan, N; Calland, R G; Rodríguez, J Caravaca; Cartwright, S L; Castillo, R; Catanesi, M G; Cervera, A; Cherdack, D; Christodoulou, G; Clifton, A; Coleman, J; Coleman, S J; Collazuol, G; Connolly, K; Cremonesi, L; Dabrowska, A; Danko, I; Das, R; Davis, S; de Perio, P; De Rosa, G; Dealtry, T; Dennis, S R; Densham, C; Di Lodovico, F; Di Luise, S; Drapier, O; Duboyski, T; Duffy, K; Dufour, F; Dumarchez, J; Dytman, S; Dziewiecki, M; Emery, S; Ereditato, A; Escudero, L; Finch, A J; Floetotto, L; Friend, M; Fujii, Y; Fukuda, Y; Furmanski, A P; Galymov, V; Gaudin, A; Giffin, S; Giganti, C; Gilje, K; Goeldi, D; Golan, T; Gomez-Cadenas, J J; Gonin, M; Grant, N; Gudin, D; Hadley, D R; Haesler, A; Haigh, M D; Hamilton, P; Hansen, D; Hara, T; Hartz, M; Hasegawa, T; Hastings, N C; Hayato, Y; Hearty, C; Helmer, R L; Hierholzer, M; Hignight, J; Hillairet, A; Himmel, A; Hiraki, T; Hirota, S; Holeczek, J; Horikawa, S; Huang, K; Ichikawa, A K; Ieki, K; Ieva, M; Ikeda, M; Imber, J; Insler, J; Irvine, T J; Ishida, T; Ishii, T; Ives, S J; Iyogi, K; Izmaylov, A; Jacob, A; Jamieson, B; Johnson, R A; Jo, J H; Jonsson, P; Jung, C K; Kaboth, A C; Kajita, T; Kakuno, H; Kameda, J; Kanazawa, Y; Karlen, D; Karpikov, I; Kearns, E; Khabibullin, M; Khotjantsev, A; Kielczewska, D; Kikawa, T; Kilinski, A; Kim, J; Kisiel, J; Kitching, P; Kobayashi, T; Koch, L; Kolaceke, A; Konaka, A; Kormos, L L; Korzenev, A; Koseki, K; Koshio, Y; Kreslo, I; Kropp, W; Kubo, H; Kudenko, Y; Kumaratunga, S; Kurjata, R; Kutter, T; Lagoda, J; Laihem, K; Lamont, I; Laveder, M; Lawe, M; Lazos, M; Lee, K P; Licciardi, C; Lindner, T; Lister, C; Litchfield, R P; Longhin, A; Ludovici, L; Macaire, M; Magaletti, L; Mahn, K; Malek, M; Manly, S; Marino, A D; Marteau, J; Martin, J F; Maruyama, T; Marzec, J; Mathie, E L; Matveev, V; Mavrokoridis, K; Mazzucato, E; McCarthy, M; McCauley, N; McFarland, K S; McGrew, C; Metelko, C; Mijakowski, P; Miller, C A; Minamino, A; Mineev, O; Mine, S; Missert, A; Miura, M; Monfregola, L; Moriyama, S; Mueller, Th A; Murakami, A; Murdoch, M; Murphy, S; Myslik, J; Nagasaki, T; Nakadaira, T; Nakahata, M; Nakai, T; Nakamura, K; Nakayama, S; Nakaya, T; Nakayoshi, K; Naples, D; Nielsen, C; Nirkko, M; Nishikawa, K; Nishimura, Y; O'Keeffe, H M; Ohta, R; Okumura, K; Okusawa, T; Oryszczak, W; Oser, S M; Owen, R A; Oyama, Y; Palladino, V; Paolone, V; Payne, D; Pearce, G F; Perevozchikov, O; Perkin, J D; Petrov, Y; Pickard, L J; Guerra, E S Pinzon; Pistillo, C; Plonski, P; Poplawska, E; Popov, B; Posiadala, M; Poutissou, J -M; Poutissou, R; Przewlocki, P; Quilain, B; Radicioni, E; Ratoff, P N; Ravonel, M; Rayner, M A M; Redij, A; Reeves, M; Reinherz-Aronis, E; Retiere, F; Robert, A; Rodrigues, P A; Rondio, E; Roth, S; Rubbia, A; Ruterbories, D; Sacco, R; Sakashita, K; Sánchez, F; Sato, F; Scantamburlo, E; Scholberg, K; Schwehr, J; Scott, M; Seiya, Y; Sekiguchi, T; Sekiya, H; Sgalaberna, D; Shiozawa, M; Short, S; Shustrov, Y; Sinclair, P; Smith, B; Smith, R J; Smy, M; Sobczyk, J T; Sobel, H; Sorel, M; Southwell, L; Stamoulis, P; Steinmann, J; Still, B; Suda, Y; Suzuki, A; Suzuki, K; Suzuki, S Y; Suzuki, Y; Szeglowski, T; Tacik, R; Tada, M; Takahashi, S; Takeda, A; Takeuchi, Y; Tanaka, H K; Tanaka, H A; Tanaka, M M; Terhorst, D; Terri, R; Thompson, L F; Thorley, A; Tobayama, S; Toki, W; Tomura, T; Totsuka, Y; Touramanis, C; Tsukamoto, T; Tzanov, M; Uchida, Y; Ueno, K; Vacheret, A; Vagins, M; Vasseur, G; Wachala, T; Waldron, A V; Walter, C W; Wark, D; Wascko, M O; Weber, A; Wendell, R; Wilkes, R J; Wilking, M J; Wilkinson, C; Williamson, Z; Wilson, J R; Wilson, R J; Wongjirad, T; Yamada, Y; Yamamoto, K; Yanagisawa, C; Yen, S; Yershov, N; Yokoyama, M; Yuan, T; Zalewska, A; Zalipska, J; Zambelli, L; Zaremba, K; Ziembicki, M; Zimmerman, E D; Zito, M; Żmuda, J

    2013-01-01

    The T2K experiment has observed electron neutrino appearance in a muon neutrino beam produced 295 km from the Super-Kamiokande detector with a peak energy of 0.6 GeV. A total of 28 electron neutrino events were detected with an energy distribution consistent with an appearance signal, corresponding to a significance of 7.3$\\sigma$ when compared to 4.92 $\\pm$ 0.55 expected background events. In the PMNS mixing model, the electron neutrino appearance signal depends on several parameters including three mixing angles $\\theta_{12}$, $\\theta_{23}$, $\\theta_{13}$, a mass difference $\\Delta m^2_{32}$ and a CP violating phase $\\delta_{\\mathrm{CP}}$. In this neutrino oscillation scenario, assuming $|\\Delta m^2_{32}| = 2.4 \\times 10^{-3}$ $\\rm eV^2$, $\\sin^2 \\theta_{23} = 0.5$, $\\delta_{\\mathrm{CP}}=0$, and $\\Delta m^2_{32} >0$ ($\\Delta m^2_{32} <0$), a best-fit value of $\\sin^2 2 \\theta_{13}$ = $0.140^{+0.038}_{-0.032}$ ($0.170^{+0.045}_{-0.037}$) is obtained.

  19. Electron Scale Solar Wind Turbulence: Cluster Observations and Theoretical Modeling

    International Nuclear Information System (INIS)

    Turbulence at MagnetoHydroDynamics (MHD) scales of the solar wind has been studied for more than three decades, using data analyzes, theoretical and numerical modeling. However smaller scales have not been explored until very recently. Here, we review recent results on the first observation of cascade and dissipation of the solar wind turbulence at the electron scales. Thanks to the high resolution magnetic and electric field data of the Cluster spacecraft, we computed the spectra of turbulence up to ∼100 Hz (in the spacecraft reference frame) and found two distinct breakpoints in the magnetic spectrum at 0.4 Hz and 35 Hz, which correspond, respectively, to the Doppler-shifted proton and electron gyroscales, fρp and fρe. Below fρp the spectrum follows a Kolmogorov scaling f-1.62, typical of spectra observed at 1 AU. Above fρp a second inertial range is formed with a scaling f-2.3 down to fρe. Above fρe the spectrum has a steeper power law ∼f-4.1 down to the noise level of the instrument. Solving numerically the linear Maxwell-Vlasov equations combined with recent theoretical predictions of the Gyro-Kinetic theory, we show that the present results are fully consistent with a scenario of a quasi-two-dimensional cascade into Kinetic Alfven modes (KAW).

  20. Inversion of Ionospheric Electron Density from GPS Beacon Observations

    Institute of Scientific and Technical Information of China (English)

    Zou Yu-hua; Xu Ji-sheng

    2003-01-01

    This paper studies the mathematical foundation of time-dependent three-dimensional (3-D) computerized ionospheric tomography (CIT) for reconstructing ionospheric electron density, Ne, from ground-based GPS beacon observations. After simplifying the relation between Ne and time,the time-dependent 3-D inversion in consideration is reduced to a 3-D tomography with incomplete projections.To see clearly the effects of the incompleteness on the quality of reconstruction under 3-D condition, the formula of 3-D parallel-beam tomography is deduced theoretically. After establishing the mathematical foundation, simulations based on actual GPS ray paths with the help of the IRI-90 model are performed,and reasonable time-dependent 3-D distribution images of Neare obtained when taking proper layout of the network and allowing variable resolutions. The quality of the reconstruction is rather good when compared with the images from the IRI-90 model directly. Therefore, results in this paper demon-strate that imaging of the ionospheric electron density distri-bution from GPS beacon observations is reasonable in theory and feasible in practice.

  1. Inversion of Ionospheric Electron Density from GPS Beacon Observations

    Institute of Scientific and Technical Information of China (English)

    ZouYu-hua; XuJi-sheng

    2003-01-01

    This paper studies the mathematical foundation of time-dependent three-dimensional (3-D) computerized ionospheric tomography (CIT) for reconstructing ionospheric electron density, N~, from ground-based GPS beacon observations. After simplifying the relation between N. and time,the time-dependent 3-D inversion in consideration is reduced to a 3-D tomography with incomplete projections. To see clearly the effects of the incompleteness on the quality of reconstruction under 3-D condition, the formula of 3-D parallelbeam tomogtTaphy is deduced theoretically. After establishing the mathematical foundation, simulations based on actual GPS ray paths with the help of the IRI-90 model are performed,and reasonable time-dependent 3-D distribution images of Ne are obtained when taking proper layout of the network and allowing variable resolutions. The quality of the reconstruction is rather good when compared with the images from the IRI-90 model directly. Therefore, results in this paper demonstrate that imaging of the ionospheric electron density distribution from GPS beacon observations is reasonable in theor yand feasible in practice.

  2. Voyager observations of Saturnian ion and electron phase space densities

    Energy Technology Data Exchange (ETDEWEB)

    Armstrong, T.P.; Paonessa, M.T.; Bell, E.V. II; Krimigis, S.M.

    1983-11-01

    Voyager 1 and 2 low-energy charged particle (LECP) observations of 30-keV to 2-MeV electron and ion energy spectra and angular distributions have been used to calculate phase space densities at constant first and second adiabatic invariant in the Saturnian magnetosphere. The results are generally consistent with inward radial diffusion from a external source. The data obtained also indicate a source of ions located within the orbital distance of enceladus capable of producing 10-to 40-MeV/Gauss ions as well as a source of electrons at about 3.5 R/sub S/ which produces particles at 100 to 200 MeV/Gauss. Higher magnetic moment (200--400 MeV/Gauss) ions extend from the sunward boundary between a plasma mantle and the region of durable trapping at R/sub S/: the behavior of the phase space density suggests inward diffusion of these particles from a source at the boundary. The identification of sources of low (10 to 200 MeV/Gauss) magnetic moment particles deep in the Saturnian magnetosphere is a new result of this work. Several analyses of the observed phase space densities in terms of time-independent radial diffusion are presented.

  3. Dark Matter Model Selection and the ATIC/PPB-BETS anomaly

    CERN Document Server

    Chen, Chuan-Ren; Nojiri, Mihoko M; Takahashi, Fuminobu; Torii, Shoji

    2008-01-01

    We argue that we may be able to sort out dark matter models in which electrons are generated through the annihilation and/or decay of dark matter, by using a fact that the initial energy spectrum is reflected in the cosmic-ray electron flux observed at the Earth even after propagation through the galactic magnetic field. To illustrate our idea we focus on three representative initial spectra: (i)monochromatic (ii)flat and (iii)double-peak ones. We find that those three cases result in significantly different energy spectra, which may be probed by the Fermi satellite in operation or an up-coming cosmic-ray detector such as CALET.

  4. Observations of multiple order parameters in 5f electron systems

    International Nuclear Information System (INIS)

    In this thesis, multiple order parameters originating in the same electronic system are studied. The multi-k magnetic structures, where more than one propagation wavevector, k, is observed in the same volume, are considered as prototypical models. The effect of this structure on the elastic and inelastic response is studied. In cubic 3-k uranium rock-salts, unexpected elastic diffraction events were observed at positions in reciprocal space where the structure factor should have been zero. These diffraction peaks are identified with correlations between the (orthogonal) magnetic order parameters. The 3-k structure also affects the observed dynamics; the spin-wave fluctuations in uranium dioxide as observed by inelastic neutron polarization analysis can only be explained on the basis of a 3-k structure. In the antiferromagnetic superconductor UPd2Al3 the magnetic order and the super-conducting state coexist, and are apparently generated by the same heavy fermions. The effect of an external magnetic field on both the normal and superconducting states is examined. In the normal state, the compound displays Fermi-liquid-like behaviour. The inelastic neutron response is strongly renormalized on entering the superconducting state, and high-precision measurements of the low-energy transfer part of this response confirm that the superconducting energy gap has the same symmetry as the antiferromagnetic lattice. (author)

  5. 3D Observation of GEMS by Electron Tomography

    Science.gov (United States)

    Matsuno, Junya; Miyake, Akira; Tsuchiyama, Akira; Nakamura-Messenger, Keiko; Messenger, Scott

    2014-01-01

    Amorphous silicates in chondritic porous interplanetary dust particles (CP-IDPs) coming from comets are dominated by glass with embedded metal and sulfides (GEMS). GEMS grains are submicron-sized rounded objects (typically 100-500) nm in diameter) with anaometer-sized (10-50 nm) Fe-Ni metal and sulfide grains embedded in an amorphous silicate matrix. Several formation processes for GEMS grains have been proposed so far, but these models are still being debated [2-5]. Bradley et al. proposed that GEMS grains are interstellar silicate dust that survived various metamorphism or alteration processes in the protoplanetary disk and that they are amorphiation products of crystalline silicates in the interstellar medium by sputter-deposition of cosmic ray irradiation, similar to space weathering [2,4]. This consideration is based on the observation of nano-sized crystals (approximately 10 nm) called relict grains in GEMS grains and their shapes are pseudomorphs to the host GEMS grains. On the other hand, Keller and Messenger proposed that most GEMS formed in the protoplanetary disk as condensates from high temperature gas [3,5]. This model is based on the fact that most GEMS grains have solar isotopic compositions and have extremely heterogeneous and non-solar elemental compositions. Keller and Messenger (2011) also reported that amorphous silicates in GEMS grains are surrounded by sulfide grains, which formed as sulfidization of metallic iron grains located on the GEMS surface. The previous studies were performed with 2D observation by using transmission electron microscopy (TEM) or scanning TEM (STEM). In order to understand the structure of GEMS grains described above more clearly, we observed 3D structure of GEMS grains by electron tomography using a TEM/STEM (JEM-2100F, JEOL) at Kyoto University. Electron tomography gives not only 3D structures but also gives higher spatial resolution (approximately a few nm) than that in conventional 2D image, which is restricted by

  6. Observation of strongly forbidden solid effect dynamic nuclear polarization transitions via electron-electron double resonance detected NMR

    OpenAIRE

    Smith, Albert A.; Corzilius, Björn; Haze, Olesya; Swager, Timothy M.; Griffin, Robert G.

    2013-01-01

    We present electron paramagnetic resonance experiments for which solid effect dynamic nuclear polarization transitions were observed indirectly via polarization loss on the electron. This use of indirect observation allows characterization of the dynamic nuclear polarization (DNP) process close to the electron. Frequency profiles of the electron-detected solid effect obtained using trityl radical showed intense saturation of the electron at the usual solid effect condition, which involves a s...

  7. Observations of underdense plasma lens focusing of relativistic electron beams

    International Nuclear Information System (INIS)

    Focusing of a 15 MeV, 19 nC electron bunch by an underdense plasma lens operated just beyond the threshold of the underdense condition has been demonstrated in experiments at the Fermilab NICADD Photoinjector Laboratory (FNPL). The strong 1.9 cm focal-length plasma-lens focused both transverse directions simultaneously and reduced the minimum area of the beam spot by a factor of 23. Analysis of the beam-envelope evolution observed near the beam waist shows that the spherical aberrations of this underdense lens are lower than those of an overdense plasma lens, as predicted by theory. Correlations between the beam charge and the properties of the beam focus corroborate this conclusion

  8. Observation of electron-antineutrino disappearance at Daya Bay

    CERN Document Server

    An, F P; Balantekin, A B; Band, H R; Beavis, D; Beriguete, W; Bishai, M; Blyth, S; Brown, R L; Cao, G F; Cao, J; Carr, R; Chan, W T; Chang, J F; Chang, Y; Chasman, C; Chen, H S; Chen, H Y; Chen, S J; Chen, S M; Chen, X C; Chen, X H; Chen, X S; Chen, Y; Chen, Y X; Cherwinka, J J; Chu, M C; Cummings, J P; Deng, Z Y; Ding, Y Y; Diwan, M V; Dong, L; Draeger, E; Du, X F; Dwyer, D A; Edwards, W R; Ely, S R; Fang, S D; Fu, J Y; Fu, Z W; Ge, L Q; Ghazikhanian, V; Gill, R L; Goett, J; Gonchar, M; Gong, G H; Gong, H; Gornushkin, Y A; Greenler, L S; Gu, W Q; Guan, M Y; Guo, X H; Hackenburg, R W; Hahn, R L; Hans, S; He, M; He, Q; He, W S; Heeger, K M; Heng, Y K; Hinrichs, P; Ho, T H; Hor, Y K; Hsiung, Y B; Hu, B Z; Hu, T; Hu, T; Huang, H X; Huang, H Z; Huang, P W; Huang, X; Huang, X T; Huber, P; Isvan, Z; Jaffe, D E; Jetter, S; Ji, X L; Ji, X P; Jiang, H J; Jiang, W Q; Jiao, J B; Johnson, R A; Kang, L; Kettell, S H; Kramer, M; Kwan, K K; Kwok, M W; Kwok, T; Lai, C Y; Lai, W C; Lai, W H; Lau, K; Lebanowski, L; Lee, J; Lee, M K P; Leitner, R; Leung, J K C; Leung, K Y; Lewis, C A; Li, B; Li, F; Li, G S; Li, J; Li, Q J; Li, S F; Li, W D; Li, X B; Li, X N; Li, X Q; Li, Y; Li, Z B; Liang, H; Liang, J; Lin, C J; Lin, G L; Lin, S K; Lin, S X; Lin, Y C; Ling, J J; Link, J M; Littenberg, L; Littlejohn, B R; Liu, B J; Liu, C; Liu, D W; Liu, H; Liu, J C; Liu, J L; Liu, S; Liu, X; Liu, Y B; Lu, C; Lu, H Q; Luk, A; Luk, K B; Luo, T; Luo, X L; Ma, L H; Ma, Q M; Ma, X B; Ma, X Y; Ma, Y Q; Mayes, B; McDonald, K T; McFarlane, M C; McKeown, R D; Meng, Y; Mohapatra, D; Morgan, J E; Nakajima, Y; Napolitano, J; Naumov, D; Nemchenok, I; Newsom, C; Ngai, H Y; Ngai, W K; Nie, Y B; Ning, Z; Ochoa-Ricoux, J P; Olshevski, A; Pagac, A; Patton, S; Pearson, C; Pec, V; Peng, J C; Piilonen, L E; Pinsky, L; Pun, C S J; Qi, F Z; Qi, M; Qian, X; Raper, N; Rosero, R; Roskovec, B; Ruan, X C; Seilhan, B; Shao, B B; Shih, K; Steiner, H; Stoler, P; Sun, G X; Sun, J L; Tam, Y H; Tanaka, H K; Tang, X; Themann, H; Torun, Y; Trentalange, S; Tsai, O; Tsang, K V; Tsang, R H M; Tull, C; Viren, B; Virostek, S; Vorobel, V; Wang, C H; Wang, L S; Wang, L Y; Wang, L Z; Wang, M; Wang, N Y; Wang, R G; Wang, T; Wang, W; Wang, X; Wang, X; Wang, Y F; Wang, Z; Wang, Z; Wang, Z M; Webber, D M; Wei, Y D; Wen, L J; Wenman, D L; Whisnant, K; White, C G; Whitehead, L; Whitten, C A; Wilhelmi, J; Wise, T; Wong, H C; Wong, H L H; Wong, J; Worcester, E T; Wu, F F; Wu, Q; Xia, D M; Xiang, S T; Xiao, Q; Xing, Z Z; Xu, G; Xu, J; Xu, J; Xu, J L; Xu, W; Xu, Y; Xue, T; Yang, C G; Yang, L; Ye, M; Yeh, M; Yeh, Y S; Yip, K; Young, B L; Yu, Z Y; Zhan, L; Zhang, C; Zhang, F H; Zhang, J W; Zhang, Q M; Zhang, K; Zhang, Q X; Zhang, S H; Zhang, Y C; Zhang, Y H; Zhang, Y X; Zhang, Z J; Zhang, Z P; Zhang, Z Y; Zhao, J; Zhao, Q W; Zhao, Y B; Zheng, L; Zhong, W L; Zhou, L; Zhou, Z Y; Zhuang, H L; Zou, J H

    2012-01-01

    The Daya Bay Reactor Neutrino Experiment has measured a non-zero value for the neutrino mixing angle $\\theta_{13}$ with a significance of 5.2 standard deviations. Antineutrinos from six 2.9 GW$_{\\rm th}$ reactors were detected in six antineutrino detectors deployed in two near (flux-weighted baseline 470 m and 576 m) and one far (1648 m) underground experimental halls. With 55 days of data, 10416 (80376) electron antineutrino candidates were detected at the far hall (near halls). The ratio of the observed to expected number of antineutrinos at the far hall is $R=0.940\\pm 0.011({\\rm stat}) \\pm 0.004({\\rm syst})$. A rate-only analysis finds $\\sin^22\\theta_{13}=0.092\\pm 0.016({\\rm stat})\\pm0.005({\\rm syst})$ in a three-neutrino framework.

  9. Electron Cloud Observations during LHC Operation with 25 ns Beams

    CERN Document Server

    Li, Kevin; Iadarola, Giovanni; Mether, Lotta; Romano, Annalisa; Rumolo, Giovanni; Schenk, Michael

    2016-01-01

    While during the Run 1 (2010-2012) of the Large Hadron Collider (LHC) most of the integrated luminosity was produced with 50 ns bunch spacing, for the Run 2 start-up (2015) it was decided to move to the nominal bunch spacing of 25 ns. As expected, with this beam configuration strong electron cloud effects were observed in the machine, which had to be mitigated with dedicated 'scrubbing' periods at injection energy. This enabled to start the operation with 25 ns beams at 6.5 TeV, but e-cloud effects continued to pose challenges while gradually increasing the number of circulating bunch trains. This contribution will review the encountered limitations and the mitigation measures that where put in place and will discuss possible strategies for further performance gain.

  10. Electron cloud observations at the ISIS Proton Synchrotron

    OpenAIRE

    Pertica, A.; Payne, S. J.

    2013-01-01

    The build up of electron clouds inside a particle accelerator vacuum chamber can produce strong transverse and longitudinal beam instabilities which in turn can lead to high levels of beam loss often requiring the accelerator to be run below its design specification. To study the behaviour of electron clouds at the ISIS Proton Synchrotron, a Micro-Channel Plate (MCP) based electron cloud detector has been developed. The detector is based on the Retarding Field Analyser (RFA) design and consis...

  11. Plasma electron observations in the vicinity of magnetic holes

    International Nuclear Information System (INIS)

    A search of Mariner 10 electron plasma and magnetic field measurements has revealed 14 examples of narrow, well-defined interplanetary field depressions. Eleven of these events are associated with electron enhancements, five with significant magnetic field direction changes, and six without. Thus even though such magnetic depressions usually coincide with electron enhancements at energies of approx.100 eV, these enhancements cannot always be the result of magnetic reconnection. It seems likely that some events involve local acceleration, possibly the result of reconnection, while others may involve electrons injected onto the field line at a remote point

  12. Observation of suprathermal electron fluxes during ionospheric modification experiments

    International Nuclear Information System (INIS)

    The temporal behavior of backscatter by ionospheric Langmuir waves was observed with the 430-MHz radar at Arecibo while a powerful HF wave was cycled 2 s on, 3 s off. The time resolution was 0.1 s. Late at night, in the absence of photoelectrons, using an HF equivalent radiated power of 80 MW at 3.175 MHz, the initial enhancement of about 6% above system noise of the backscattered power with Doppler shifts between -3.75 and -3.85 MHz was reached about 0.25 s after switching on the HF transmitter. In the following second the enhancement gradually decreased to about 3% and remained there until switching off. During the late afternoon, in the presence of photoelectrons, using the same HF power at 5.1 MHz, an initial enhancement by 25% of the backscattered power with Doppler shifts between -5.25 and -5.35 MHz appeared within less than 0.1 s after switching on the HF transmitter. The incoherent backscatter by Langmuir waves enhanced by photoelectrons was already above system noise by a factor greatly in excess of 10 before switching on the HF transmitter; the 25% enhancement thus corresponds to an enhancement greatly in excess of 250% above system noise. The enhancement drops to less than one tenth of its original value in less than a second. The nighttime effect is attributed to multiple acceleration of electrons from the high-energy tail of the Maxwellian distribution. The daytime effect is believed to be due to a modification in the distribution function of photoelectrons

  13. Seismo-ionospheric coupling appearing as equatorial electron density enhancements observed via DEMETER electron density measurements

    Science.gov (United States)

    Ryu, K.; Lee, E.; Chae, J. S.; Parrot, M.; Pulinets, S.

    2014-10-01

    We report the processes and results of statistical analysis on the ionospheric electron density data measured by the Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) satellite over a period of 6 years (2005-2010), in order to investigate the correlation between seismic activity and equatorial plasma density variations. To simplify the analysis, three equatorial regions with frequent earthquakes were selected and then one-dimensional time series analysis between the daily seismic activity indices and the equatorial ionization anomaly (EIA) intensity indices, which represent relative equatorial electron density increase, were performed for each region. The statistically significant values of the lagged cross-correlation function, particularly in the region with minimal effects of longitudinal asymmetry, indicate that some of the very large earthquakes with M > 5.0 in the low-latitude region can accompany observable precursory and concurrent EIA enhancements, even though the seismic activity is not the most significant driver of the equatorial ionospheric evolution. The physical mechanisms of the seismo-ionospheric coupling is consistent with our observation, and the possibility of earthquake prediction using the EIA intensity variation is discussed.

  14. Direct observation of electron dynamics in the attosecond domain.

    Science.gov (United States)

    Föhlisch, A; Feulner, P; Hennies, F; Fink, A; Menzel, D; Sanchez-Portal, D; Echenique, P M; Wurth, W

    2005-07-21

    Dynamical processes are commonly investigated using laser pump-probe experiments, with a pump pulse exciting the system of interest and a second probe pulse tracking its temporal evolution as a function of the delay between the pulses. Because the time resolution attainable in such experiments depends on the temporal definition of the laser pulses, pulse compression to 200 attoseconds (1 as = 10(-18) s) is a promising recent development. These ultrafast pulses have been fully characterized, and used to directly measure light waves and electronic relaxation in free atoms. But attosecond pulses can only be realized in the extreme ultraviolet and X-ray regime; in contrast, the optical laser pulses typically used for experiments on complex systems last several femtoseconds (1 fs = 10(-15) s). Here we monitor the dynamics of ultrafast electron transfer--a process important in photo- and electrochemistry and used in solid-state solar cells, molecular electronics and single-electron devices--on attosecond timescales using core-hole spectroscopy. We push the method, which uses the lifetime of a core electron hole as an internal reference clock for following dynamic processes, into the attosecond regime by focusing on short-lived holes with initial and final states in the same electronic shell. This allows us to show that electron transfer from an adsorbed sulphur atom to a ruthenium surface proceeds in about 320 as. PMID:16034414

  15. Low latitude electron temperature observed by the CHAMP satellite

    Czech Academy of Sciences Publication Activity Database

    Stolle, C.; Truhlík, Vladimír; Richards, P.; Olsen, N.

    Copernicus GmbH, 2012. ISSN 1607-7962 Institutional support: RVO:68378289 Keywords : Topside ionosphere * electron temperature * CHAMP http://meetingorganizer.copernicus.org/EGU2012/EGU2012-7753-1.pdf

  16. MESSENGER Observations of Suprathermal Electrons in Mercury's Magnetosphere

    Science.gov (United States)

    Ho, G. C.; Krimigis, S. M.; Starr, R. D.; Vandegriff, J. D.; Baker, D. N.; Gold, R. E.; Anderson, B. J.; Korth, H.; Schriver, D.; McNutt, R. L., Jr.; Solomon, S. C.

    2015-12-01

    The X-Ray Spectrometer (XRS) on the MESSENGER spacecraft, in orbit about Mercury from March 2011 to April 2015, routinely detected fluorescent X-rays induced by low-energy (1-10 keV) electrons. These electrons are in general below the threshold energy response of the Energetic Particle Spectrometer (EPS), one of two sensors on MESSENGER's Energetic Particle and Plasma Spectrometer (EPPS) instrument that measures electrons at energies above 35 keV. Hence, the XRS provided a measure of this lower-energy suprathermal electron population at Mercury. We devised an automated algorithm to select these events from the XRS data set from April 2011 to March 2015 on the basis of the duration, location, and spectral slope of the events. We identified 3102 events in 3900 orbits around Mercury, sampling all Mercury longitudes multiple times over the four-year period. It is evident that these suprathermal electrons were present near the planet at all local times, but the majority were on the nightside of the planet, and a dawn-dusk asymmetry is clearly seen in the data. When the event locations are plotted in simplified B versus L coordinates (where B is the magnitude of the magnetic field, L defines an axisymmetric surface of those lines of magnetic force from the dipole component of Mercury's internal field that intersect the magnetic equator at a distance L RM from the dipole center, and RM is Mercury's radius), several distinct clusters of events can be seen. We infer that all of these are signatures of accelerated electrons being injected from Mercury's tail region to form a quasi-trapped electron distribution at Mercury.

  17. The acceleration of energetic electrons associated with chorus observed by TC-2

    International Nuclear Information System (INIS)

    Flux of high energetic electrons in the Earth's outer radiation belt varies dramatically during enhanced magnetic activities. Local electron acceleration to relativistic energies is prevalent during the storm recovery. However, it is not fully understood. Data of Low frequency waves and high energy electron fluxes from TC-2 were used to study electron flux and the relationship with whistler mode chorus during the Nov. 7th-11th storm in year 2004. Relativistic electrons accelerated from a few hundred KeV seed electrons were observed, and meanwhile the fluxes of the seed electrons have been observed gone down

  18. Observation of Spherical Focus in an Electron Penning Trap

    International Nuclear Information System (INIS)

    We produce simultaneously dense and well-confined nonneutral plasmas by spherical focusing. A small (3mm radius) Penning trap has low-energy electrons injected at a single pole of the sphere. Precisely when the trap parameters are adjusted to produce a spherical well, the system self-organizes into a spherical state through a bootstrapping mechanism which produces a hysteresis. Additional confirmation of the dense spherical focus is provided by electrons scattered by the central core. Core densities up to 35 times the Brillouin density have been inferred from the data. copyright 1996 The American Physical Society

  19. Electron energetics in the expanding solar wind via Helios observations

    Czech Academy of Sciences Publication Activity Database

    Štverák, Štěpán; Trávníček, Pavel M.; Hellinger, Petr

    2015-01-01

    Roč. 120, č. 10 (2015), s. 8177-8193. ISSN 2169-9380 R&D Projects: GA ČR GAP209/12/2041; GA ČR GA15-17490S Institutional support: RVO:67985815 Keywords : solar wind * electrons energetics * transport processes Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 3.440, year: 2013

  20. Plasma wave observations during electron gun experiments on ISEE-1

    OpenAIRE

    Olsen, R. C.; F. S. Mozer; Anderson, R. R.

    1992-01-01

    Advances in Space Research, 12, (12)29 The ISEE-1 electron guns were operated during the final orbits of ISEE-1 in 1987 in tests designed to study the stimulation of plasma waves. The guns were operated in modes which varied from ...

  1. Environmental scanning electron microscope for observation in live nature

    Czech Academy of Sciences Publication Activity Database

    Neděla, Vilém; Tihlaříková, Eva; Shiojiri, M.

    Osaka: The Japanese Society of Microscopy, 2013. [Annual Meeting of the Japanese Society of Microscopy /69./. Osaka (JP), 20.05.2013-22.05.2013] Institutional support: RVO:68081731 Keywords : ESEM * AQUASEM II * biological samples * in-situ experiments Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  2. Environmental scanning electron microscope for observation of live nature

    Czech Academy of Sciences Publication Activity Database

    Neděla, Vilém; Tihlaříková, Eva

    Osaka: The Japanese Society of Microscopy, 2013. [Annual Meeting of the Japanese Society of Microscopy /69./. Osaka (JP), 20.05.2013-22.05.2013] Institutional support: RVO:68081731 Keywords : ESEM * AQUASEM II * live nature * detectors Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  3. A Security Focused Integration Architecture for an Electronic Observation Chart

    OpenAIRE

    Divic, Mirela; Huse, Ida Hveding

    2005-01-01

    An observation chart contains a collection of information from several different health information systems used at a hospital. Today, health personnel often has to access these health information systems during patient care and manually register information from them into the observation chart. Integration of the health information systems which constitute an observation chart is therefore needed. Integration means that systems used by a large amount of users are put together in such a way t...

  4. Experimental study of electron ejection by heavy ion irradiation of solids: Observation of forward and backward emitted electron jets

    Science.gov (United States)

    Zäpfel, T.; Hagmann, S.; Rothard, H.; Ullrich, J.; Kraft, G.; Schmidt-Böcking, H.; Groeneveld, K. O.

    2002-06-01

    Doubly differential cross sections for electron emission induced by the passage of swift heavy ions such as F q+ (1.5-2.0 MeV/u) through thin solid foil targets were measured at the Tandem accelerator of the JR Macdonald Laboratory at Kansas State University. The complete angular distribution of electron emission up to 4000 eV (beyond the maximum of the "binary encounter" electron peak) was determined as a function of the projectile charge state ( q=5 and 9) and the target material in a wide Z range: C ( Z=6), Al ( Z=13) and Au ( Z=79). Electrons emitted from the foils between 0 and ±180° with respect to the beam axis were energy and angle analysed by means of a toroidal electrostatic electron spectrometer equipped with a 2D position sensitive channelplate detector. In addition to low energy cascade electrons, electrons from collective excitation (plasmons), target Auger electrons, convoy electrons and binary encounter electrons, we also observe a new feature never before seen in electron angular distributions: narrow electron jets ("spikes") emitted along the ion beam axis in forward and backward directions. This observation is made possible by the good angular resolution of our spectrometer and the possibility to record the entire angular distribution in a single run.

  5. Observation of strongly forbidden solid effect dynamic nuclear polarization transitions via electron-electron double resonance detected NMR

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Albert A.; Corzilius, Björn; Haze, Olesya; Swager, Timothy M.; Griffin, Robert G., E-mail: rgg@mit.edu [Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2013-12-07

    We present electron paramagnetic resonance experiments for which solid effect dynamic nuclear polarization transitions were observed indirectly via polarization loss on the electron. This use of indirect observation allows characterization of the dynamic nuclear polarization (DNP) process close to the electron. Frequency profiles of the electron-detected solid effect obtained using trityl radical showed intense saturation of the electron at the usual solid effect condition, which involves a single electron and nucleus. However, higher order solid effect transitions involving two, three, or four nuclei were also observed with surprising intensity, although these transitions did not lead to bulk nuclear polarization—suggesting that higher order transitions are important primarily in the transfer of polarization to nuclei nearby the electron. Similar results were obtained for the SA-BDPA radical where strong electron-nuclear couplings produced splittings in the spectrum of the indirectly observed solid effect conditions. Observation of high order solid effect transitions supports recent studies of the solid effect, and suggests that a multi-spin solid effect mechanism may play a major role in polarization transfer via DNP.

  6. Observations of intense trapped electron fluxes at synchronous altitudes

    Science.gov (United States)

    Davidson, G. T.; Filbert, P. C.; Nightingale, R. W.; Imhof, W. L.; Reagan, J. B.

    1988-01-01

    The concept of flux limiting in the outer radiation belt proposed by Kennel and Petschek (1966) has been tested in a dynamic situation by using data acquired with instruments aboard the SCATHA satellite. A case-by-case analysis of 12 events for evidence of flux limiting under various magnetospheric conditions is made. The reuslts indicate qualitative agreement with the flux limiting theory for all the events studied. Even the quiescent events and hard-spectrum events are consistent with flux limiting. The limiting flux level at any instant appears to depend strongly on the recent history of the trapped electrons and plasma in the outer magnetosphere.

  7. First dedicated observations of runaway electrons in the COMPASS tokamak

    Czech Academy of Sciences Publication Activity Database

    Vlainić, M.; Mlynář, Jan; Weinzettl, Vladimír; Papřok, Richard; Imríšek, Martin; Ficker, Ondřej; Vondráček, Petr; Havlíček, Josef

    2015-01-01

    Roč. 60, č. 2 (2015), s. 249-255. ISSN 0029-5922. [Kudowa Summer School 2014 "Towards Fusion Energy"/12./. Kudowa Zdrój, 09.06.2014-13.06.2014] R&D Projects: GA MŠk(CZ) LM2011021 Institutional support: RVO:61389021 Keywords : plasma diagnostics * runaway electrons * tokamak Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.477, year: 2014 http://www.nukleonika.pl/www/back/full/vol60_2015/v60n2p249f.pdf

  8. Observation of Dislocation Dynamics in the Electron Microscope

    Energy Technology Data Exchange (ETDEWEB)

    Lagow, B W; Robertson, I M; Jouiad, M; Lassila, D H; Lee, T C; Birnbaum, H K

    2001-08-21

    Deformation experiments performed in-situ in the transmission electron microscope have led to an increased understanding of dislocation dynamics. To illustrate the capability of this technique two examples will be presented. In the first example, the processes of work hardening in Mo at room temperature will be presented. These studies have improved our understanding of dislocation mobility, dislocation generation, and dislocation-obstacle interactions. In the second example, the interaction of matrix dislocations with grain boundaries will be described. From such studies predictive criteria for slip transfer through grain boundaries have been developed.

  9. Observation of Live Ticks (Haemaphysalis flava) by Scanning Electron Microscopy under High Vacuum Pressure

    OpenAIRE

    ISHIGAKI, YASUHITO; Nakamura, Yuka; Oikawa, Yosaburo; Yano, Yasuhiro; Kuwabata, Susumu; Nakagawa, Hideaki; Tomosugi, Naohisa; Takegami, Tsutomu

    2012-01-01

    Scanning electron microscopes (SEM), which image sample surfaces by scanning with an electron beam, are widely used for steric observations of resting samples in basic and applied biology. Various conventional methods exist for SEM sample preparation. However, conventional SEM is not a good tool to observe living organisms because of the associated exposure to high vacuum pressure and electron beam radiation. Here we attempted SEM observations of live ticks. During 1.5×10−3 Pa vacuum pressure...

  10. Electron temperature fluctuation in the HT-7 tokamak plasma observed by electron cyclotron emission imaging

    Institute of Scientific and Technical Information of China (English)

    Xu Xiao-Yuan; Wang Jun; Yu Yi; Wen Yi-Zhi; Yu Chang-Xuan; Liu Wan-Dong; Wan Bao-Nian; Gao Xiang; N. C. Luhmann; C. W. Domier; Jian Wang; Z. G. Xia; Zuowei Shen

    2009-01-01

    The fluctuation of the electron temperature has been measured by using the electron cyclotron emission imaging in the Hefei Tokamak-7 (HT-7) plasma. The electron temperature fluctuation with a broadband spectrum shows that it propagates in the electron diamagnetic drift direction, and the mean poloidal wave-number kg is calculated to be about 1.58 cm-1, or keps ≈0.34. It indicates that the fluctuation should come from the electron drift wave turbulence. The linear global scaling of the electron temperature fluctuation with the gradient of electron temperature is consistent with the mixing length scale qualitatively. Evolution of spectrum of the fluctuation during the sawtooth oscillation phases is investigated, and the fluctuation is found to increase with the gradient of electron temperature increasing during most phases of the sawtooth oscillation. The results indicate that the electron temperature gradient is probably the driver of the fluctuation enhancement. The steady heat flux driven by electron temperature fluctuation is estimated and compared with the results from power balance estimation.

  11. Electron densities in quiescent prominences derived from eclipse observations

    Czech Academy of Sciences Publication Activity Database

    Jejčič, S.; Heinzel, Petr

    2009-01-01

    Roč. 254, č. 1 (2009), s. 89-100. ISSN 0038-0938 Grant ostatní: EU(XE) ESA-PECS project No. 98030 Institutional research plan: CEZ:AV0Z10030501 Keywords : prominences quiescent * eclipse observations * visible spectrum Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 3.628, year: 2009

  12. An Environmental Scanning Electron Microscopy and Observation if Live Nature

    Czech Academy of Sciences Publication Activity Database

    Neděla, Vilém; Tihlaříková, Eva; Shiojiri, M.

    Sapporo: -, 2014. s. 12-13. [ Japanese -Polish Joint Seminar on Micro and Nano Analysis /10./. 24.10.2014-26.10.2014, Sapporo] R&D Projects: GA ČR(CZ) GA14-22777S Institutional support: RVO:68081731 Keywords : SEM * observation of live nature

  13. Electron microscopic observations of hydrogen implantation in ilmenites

    Science.gov (United States)

    Blanford, G. E.

    1983-01-01

    Hydrogen ion beams were found to form submicrometer, bumpy textures on the surface of ilmenite grains. From this effect, it is believed that similar bumpy textures seen on lunar ilmenite, pyroxene, and olivine grains are likely to be caused by solar wind irradiation. As a consequence, the concentration of bumpy textured grains may be a useful index of surface maturity for lunar soils. An attempt was made to search for grains with these bumpy textures in interplanetary dust and lunar and meteoritic regolith breccias in order to obtain information about the duration of their exposure to the solar wind. Solar wind irradiation was simulated on natural, terrestrial ilmenite. Hydrogen ion beams were directed at small grains and polished sections which were then examined by electron microscopy.

  14. Observations of electron cloud phenomena at PETRA III

    CERN Document Server

    Wanzenberg, R

    2013-01-01

    PETRA III is a third generation synchrotron radiation facility at DESY, which is presently operated with positron beams. Regular user operation started in mid 2010 after a commissioning phase which began in April 2009. The design current of 100 mA has been achieved but with different number of bunches and bunch to bunch distances than originally foreseen since a strong vertical emittance growth was observed for the design bunch filling pattern with 960 bunches. During machine studies different bunch filling patterns have been tested. In 2012 two scrubbing runs with 480 bunches and a bunch to bunch spacing of 16 ns have been done. The recent measurements indicate that the scrubbing runs have mitigated the emittance growth. Furthermore conditioning effects have been observed during the user runs in 2011. The results from the measured emittances and tune spectra are reported.

  15. "Smoking-Gun" Observables of Magnetic Reconnection: Spatiotemporal Evolution of Electron Characteristics Throughout the Diffusion Region

    Science.gov (United States)

    Shuster, J. R.; Chen, L. J.; Bessho, N.; Li, G.; Torbert, R. B.; Wang, S.; Argall, M. R.; Daughton, W. S.

    2014-12-01

    Electron distribution functions can provide "smoking-gun" evidence for the detection of electron diffusion regions in collisionless magnetic reconnection. Knowledge of the spatiotemporal evolution of electron distributions during reconnection is significantly lacking, and will further elucidate the outstanding questions of how, where, and when electrons are energized during reconnection. Based on spacecraft observations and PIC simulations of symmetric reconnection, electrons in the inflow region are known to exhibit a temperature anisotropy Te// > Te⊥. Studies of exhaust electrons have reported hot and isotropic electrons, while others have reported anisotropic exhaust structures. Electron distributions in the vicinity of the X-line have a triangular, 3D velocity space structure with distinct striations corresponding to the number of times electrons reflect within the electron current layer. Here, we report the spatial and temporal evolution of electron distributions from the vicinity of the X-line to the end of the electron outflow jet, with the discovery that the discrete striations swirl and rotate as electrons re-magnetize, forming arc and ring structures. Highly structured, time-dependent electron anisotropy develops in the exhaust distributions only near or after the peak reconnection rate, explaining the previous discrepancy concerning the degree of electron anisotropy in the exhaust, and suggesting a technique to infer the evolution stage of reconnection using spacecraft measurements. We also present a theory for predicting the spacing of the striations of electron distributions in the vicinity of the X-line based on local measurements, which could be directly tested by spacecraft observations. Electron data from Cluster magnetotail reconnection inflows and exhausts exhibit many anisotropic structures as predicted by simulation. Observed distributions near the reconnection mid-plane (Bx ~ 0 nT) are often highly structured with populations exhibiting Te

  16. Non-thermal plasma mills bacteria: Scanning electron microscopy observations

    International Nuclear Information System (INIS)

    Non-thermal plasmas hold great promise for a variety of biomedical applications. To ensure safe clinical application of plasma, a rigorous analysis of plasma-induced effects on cell functions is required. Yet mechanisms of bacteria deactivation by non-thermal plasma remain largely unknown. We therefore analyzed the influence of low-temperature atmospheric plasma on Gram-positive and Gram-negative bacteria. Using scanning electron microscopy, we demonstrate that both Gram-positive and Gram-negative bacteria strains in a minute were completely destroyed by helium plasma. In contrast, mesenchymal stem cells (MSCs) were not affected by the same treatment. Furthermore, histopathological analysis of hematoxylin and eosin–stained rat skin sections from plasma–treated animals did not reveal any abnormalities in comparison to control ones. We discuss possible physical mechanisms leading to the shred of bacteria under non-thermal plasma irradiation. Our findings disclose how helium plasma destroys bacteria and demonstrates the safe use of plasma treatment for MSCs and skin cells, highlighting the favorability of plasma applications for chronic wound therapy

  17. In situ Transmission Electron Microscopy observation of Ag nanocrystal evolution by surfactant free electron-driven synthesis

    Science.gov (United States)

    Longo, Elson; Avansi, Waldir; Bettini, Jefferson; Andrés, Juan; Gracia, Lourdes

    2016-03-01

    The study of the interaction of electron irradiation with matter and the response of the material to the passage of electrons is a very challenging problem. However, the growth mechanism observed during nanostructural evolution appears to be a broad and promising scientific field in nanotechnology. We report the in situ TEM study of nanostructural evolution of electron-driven silver (Ag) nanocrystals through an additive-free synthetic procedure. Observations revealed the direct effect of the electron beam on the morphological evolution of Ag nanocrystals through different mechanisms, such as mass transport, site-selective coalescence, and an appropriate structural configuration after coalescence leading to a more stable configuration. A fundamental understanding of the growth and formation mechanisms of Ag nanocrystals, which interact with the electron beam, is essential to improve the nanocrystal shape-control mechanisms as well as the future design and study of nanomaterials.

  18. Contribution of proton and electron precipitation to the observed electron concentration in October-November 2003 and September 2005

    Energy Technology Data Exchange (ETDEWEB)

    Verronen, P.T.; Andersson, M.E.; Kauristie, K.; Palmroth, M. [Finnish Meteorological Institute, Helsinki (Finland). Earth Observation; Kero, A. [Oulu Univ., Sodankylae (Finland). Sodankylae Geophysical Observatory; Enell, C.F. [EISCAT Scientific Association, Kiruna (Sweden); Wissing, J.M. [Osnabrueck Univ. (Germany). Inst. of Environmental Systems Research; Talaat, E.R. [Johns Hopkins Univ., Laurel, MD (United States). Applied Physics Lab.; Sarris, T.E. [Democritus Univ. of Thrace, Xanthi (Greece). Space Research Lab.; Armandillo, E. [European Space Agency, Nordwijk (Netherlands). ESTEC

    2015-01-01

    Understanding the altitude distribution of particle precipitation forcing is vital for the assessment of its atmospheric and climate impacts. However, the proportion of electron and proton forcing around the mesopause region during solar proton events is not always clear due to uncertainties in satellite-based flux observations. Here we use electron concentration observations of the European Incoherent Scatter Scientific Association (EISCAT) incoherent scatter radars located at Tromsoe (69.58 N, 19.23 E) to investigate the contribution of proton and electron precipitation to the changes taking place during two solar proton events. The EISCAT measurements are compared to the results from the SodankylaeIon and Neutral Chemistry Model (SIC). The proton ionization rates are calculated by two different methods - a simple energy deposition calculation and the Atmospheric Ionization Model Osnabrueck (AIMOS v1.2), the latter providing also the electron ionization rates. Our results show that in general the combination of AIMOS and SIC is able to reproduce the observed electron concentration within 50% when both electron and proton forcing is included. Electron contribution is dominant above 90 km, and can contribute significantly also in the upper mesosphere especially during low or moderate proton forcing. In the case of strong proton forcing, the AIMOS electron ionization rates seem to suffer from proton contamination of satellite-based flux data. This leads to overestimation of modelled electron concentrations by up to 90% between 75-90 km and up to 100-150% at 70-75 km. Above 90 km, the model bias varies significantly between the events. Although we cannot completely rule out EISCAT data issues, the difference is most likely a result of the spatio-temporal fine structure of electron precipitation during individual events that cannot be fully captured by sparse in situ flux (point) measurements, nor by the statistical AIMOS model which is based upon these observations

  19. NOAA POES Observations of Relativistic Electron Precipitation during a Radiation Belt Depletion Event

    Science.gov (United States)

    Millan, R. M.; Yando, K.; Green, J. C.

    2008-12-01

    We present POES observations of relativistic electron precipitation during an electron depletion event observed by GOES and GPS. On January 19, 2000 NOAA-15 passed very near the MAXIS balloon payload (L=4.7) which detected an intense duskside precipitation event (Millan et al., 2007). Recent work has shown that the NOAA MEPED proton detector responds to electrons above ~700 keV. We combine data from this high energy channel with data from the MEPED electron detector to examine the energy distribution and spatial extent of precipitation during this period. The results are compared with the MAXIS balloon observations.

  20. Synchronous phase measurements in the LHC for electron cloud observations

    CERN Document Server

    Esteban Müller, JF

    2013-01-01

    This Note summarizes the e-cloud observations done in the LHC with 50 ns and 25 ns spaced beams during 2012. Bunch-by-bunch synchronous phase measurements were used to study the e-cloud build-up along bunch trains and to calculate the beam power loss due to e-cloud. The 50 ns beams did not present any sign of e-cloud from the beginning of the 2012 run, thanks to the conditioning achieved in the previous year. On the contrary, the e-cloud effect was strong at the beginning for 25 ns beams, but it was reduced after the scrubbing run and finally it was possible to accelerate 25 ns beams to 4 TeV and put them into collisions. Synchronous phase measurements presented in this paper allow to follow all these changes in the e-cloud effect.

  1. Fast and precise electron counting system for the observation of quantum mechanical electron intensity correlation

    International Nuclear Information System (INIS)

    A recent estimation showed that the intensity cross-corelation function g(2)(τ) measured by an apparatus with a coincidence resolving time T>>τc is expressed as g(2)(0) similar 1-Aτc/T, where A (≤1) is a factor depending upon the spatial coherence and the spin polarization. The antibunching signal Aτc/T may be detected by accumulating the data to reduce the statistical fluctuations of the measurement. A fast and accurate electron counting system with small dead time is therefore required to measure the correlation within a permissible period of time. In this letter, we describe such an electron counting system. It consists of avalance photodiodes (APDs) as electron detectors and a 5-GHz precision digital correlator. (orig.)

  2. Comparison of simulated and observed trapped and precipitating electron fluxes during a magnetic storm

    Science.gov (United States)

    Chen, Margaret W.; Lemon, Colby L.; Orlova, Ksenia; Shprits, Yuri; Hecht, James; Walterscheid, R. L.

    2015-10-01

    The ability to accurately model precipitating electron distributions is crucial for understanding magnetosphere-ionosphere-thermosphere coupling processes. We use the magnetically and electrically self-consistent Rice Convection Model-Equilibrium (RCM-E) of the inner magnetosphere to assess how well different electron loss models can account for observed electron fluxes during the large 10 August 2000 magnetic storm. The strong pitch angle scattering rate produces excessive loss on the morning and dayside at geosynchronous orbit (GEO) compared to what is observed by a Los Alamos National Laboratory satellite. RCM-E simulations with parameterized scattering due to whistler chorus outside the plasmasphere and hiss inside the plasmasphere are able to account simultaneously for trapped electron fluxes at 1.2 keV to ~100 keV observed at GEO and for precipitating electron fluxes and electron characteristic energies in the ionosphere at 833 km measured by the NOAA 15 satellite.

  3. Galileo observation of the motions of ion and electron plasmas in the magnetotail

    International Nuclear Information System (INIS)

    Here the authors report on observations of three dimensional ion and electron flow in the magnetotail at distances from the earth comparable to the earth-moon separation. This can be contrasted to previous measurements which were two dimensional and primarily looked at electron flow. Observations were made in the plasma sheet and the plasma mantle. In the mantle the electron and proton bulk drift velocities were observed to be the same. In the sheet, the electron drift velocity was observed to be considerably greater than the ion velocity. The electron velocity was found to mainly consist of field aligned current, as opposed to E x B convective drift. For the ions the velocities were often in different directions, and seemed to be much more convective in nature

  4. Spacecraft observations and analytic theory of crescent-shaped electron distributions in asymmetric magnetic reconnection

    CERN Document Server

    Egedal, J; Daughton, W; Wetherton, B; Cassak, P A; Chen, L -J; Lavraud, B; Trobert, R B; Dorelli, J; Gershman, D J; Avanov, L A

    2016-01-01

    Supported by a kinetic simulation, we derive an exclusion energy parameter $\\cal{E}_X$ providing a lower kinetic energy bound for an electron to cross from one inflow region to the other during magnetic reconnection. As by a Maxwell Demon, only high energy electrons are permitted to cross the inner reconnection region, setting the electron distribution function observed along the low density side separatrix during asymmetric reconnection. The analytic model accounts for the two distinct flavors of crescent-shaped electron distributions observed by spacecraft in a thin boundary layer along the low density separatrix.

  5. Observation of delayed electron emission in a two-phase liquid xenon detector

    International Nuclear Information System (INIS)

    Results of the experimental study of electron emission from liquid xenon via electroluminescence of the gas phase are presented. We report on observation of a peculiar kind of delayed electroluminescent signal following initial electroluminescence caused by ionizing particles. We also present the results of a study of spontaneous single electron emission following cosmic muon signals. It was found that the rate of spontaneous single electron signals strongly depends on the time passed since the initial electroluminescence happened. The analysis of experimental data showed that both spontaneous single electron signals and delayed electroluminescent signals are associated with ionization electrons which are trapped by the potential barrier at the interface

  6. Observation of Electron Cloud Instabilities and Emittance Dilution at the Cornell Electron-Positron Storage Ring Test Accelerator

    International Nuclear Information System (INIS)

    Electron cloud related emittance dilution and instabilities of bunch trains limit the performance of high intensity circular colliders. One of the key goals of the Cornell electron-positron storage ring Test Accelerator (CesrTA) research program is to improve our understanding of how the electron cloud alters the dynamics of bunches within the train. Single bunch beam diagnotics have been developed to measure the beam spectra, vertical beam size, two important dynamical effects of beams interacting with the electron cloud, for bunch trains on a turn-by-turn basis. Experiments have been performed at CesrTA to probe the interaction of the electron cloud with stored positron bunch trains. The purpose of these experiments was to characterize the dependence of beam-electron cloud interactions on the machine parameters such as bunch spacing, vertical chromaticity, and bunch current. The beam dynamics of the stored beam, in the presence of the electron cloud, was quantified using: 1) a gated beam position monitor (BPM) and spectrum analyzer to measure the bunch-by-bunch frequency spectrum of the bunch trains; 2) an x-ray beam size monitor to record the bunch-by-bunch, turn-by-turn vertical size of each bunch within the trains. In this paper we report on the observations from these experiments and analyze the effects of the electron cloud on the stability of bunches in a train under many different operational conditions

  7. Observation of Electron Cloud Instabilities and Emittance Dilution at the Cornell Electron-Positron Storage Ring Test Accelerator

    Science.gov (United States)

    Holtzapple, R. L.; Billing, M. G.; Campbell, R. C.; Dugan, G. F.; Flanagan, J.; McArdle, K. E.; Miller, M. I.; Palmer, M. A.; Ramirez, G. A.; Sonnad, K. G.; Totten, M. M.; Tucker, S. L.; Williams, H. A.

    2016-04-01

    Electron cloud related emittance dilution and instabilities of bunch trains limit the performance of high intensity circular colliders. One of the key goals of the Cornell electron-positron storage ring Test Accelerator (CesrTA) research program is to improve our understanding of how the electron cloud alters the dynamics of bunches within the train. Single bunch beam diagnotics have been developed to measure the beam spectra, vertical beam size, two important dynamical effects of beams interacting with the electron cloud, for bunch trains on a turn-by-turn basis. Experiments have been performed at CesrTA to probe the interaction of the electron cloud with stored positron bunch trains. The purpose of these experiments was to characterize the dependence of beam-electron cloud interactions on the machine parameters such as bunch spacing, vertical chromaticity, and bunch current. The beam dynamics of the stored beam, in the presence of the electron cloud, was quantified using: 1) a gated beam position monitor (BPM) and spectrum analyzer to measure the bunch-by-bunch frequency spectrum of the bunch trains; 2) an x-ray beam size monitor to record the bunch-by-bunch, turn-by-turn vertical size of each bunch within the trains. In this paper we report on the observations from these experiments and analyze the effects of the electron cloud on the stability of bunches in a train under many different operational conditions.

  8. A new twist on excited dark matter: implications for INTEGRAL, PAMELA/ATIC/PPB-BETS, DAMA

    CERN Document Server

    Chen, Fang; Frey, Andrew R

    2009-01-01

    We show that the 511 keV gamma ray excess observed by INTEGRAL/SPI can be more robustly explained by exciting dark matter (DM) at the center of the galaxy, if there is a peculiar spectrum of DM states chi_0, chi_1 and chi_2, with masses M_0 ~ 500 GeV, M_1 ~ M_0 + 2 m_e. The small mass splitting delta M should be <~ 100 keV. In addition, we require at least two new gauge bosons (preferably three), with masses ~100 MeV. With this spectrum, chi_1 is stable, but can be excited to chi_2 by low-velocity DM scatterings near the galactic center, which are Sommerfeld-enhanced by two of the 100 MeV gauge boson exchanges. The excited state chi_2 decays to chi_0 and nonrelativistic e+e-, mediated by the third gauge boson, which mixes with the photon and Z. Although such a small 100 keV splitting has been independently proposed for explaining the DAMA annual modulation through the inelastic DM mechanism, the need for stability of chi_1 (and hence seqestering it from the Standard Model) implies that our scenario cannot ...

  9. Field-Aligned Electrons in Polar Region Observed by Cluster on 30 September 2001

    International Nuclear Information System (INIS)

    The physical process in the Earth's polar region is very complex and still needs to be further studied. Using the data from Cluster satellite measurement, an analysis on field-aligned electrons in the mid-latitude cusp on 30 September 2001 has been performed. The satellite observed a down-flowing electron event in the low-latitude boundary and a sequential up-flowing electron event in the high-latitude boundary of the cusp region. The down-flowing electron had a velocity as high as 500 km/s and a flux of 2.0 × 109 cm−2·s−1. The up-flowing electron had a velocity up to 1200 km/s and a flux of 4.9 × 109 cm−2·s−1. Both the velocity and the flux observed in this event are the maximum values of the up-flowing electrons observed by all satellites to date. The electron is the main contributor for the field-aligned current in this event. The physical mechanism is also discussed. The down-flowing electron in the low-latitude boundary of the cusp region may result from solar wind injecting during the southward IMF, and the up-flowing electrons in the high-latitude boundary of cusp may result from mirroring of the solar wind, or from the ionospheric up-flowing electrons which have been accelerated

  10. Onsets and spectra of impulsive solar energetic electron events observed near the Earth

    CERN Document Server

    Kontar, E P

    2009-01-01

    Impulsive solar energetic electrons are often observed in the interplanetary space near the Earth and have an attractive diagnostic potential for poorly understood solar flare acceleration processes. We investigate the transport of solar flare energetic electrons in the heliospheric plasma to understand the role of transport to the observed onset and spectral properties of the impulsive solar electron events. The propagation of energetic electrons in solar wind plasma is simulated from the acceleration region at the Sun to the Earth, taking into account self-consistent generation and absorption of electrostatic electron plasma (Langmuir) waves, effects of non-uniform plasma, collisions and Landau damping. The simulations suggest that the beam-driven plasma turbulence and the effects of solar wind density inhomogeneity play a crucial role and lead to the appearance of a) spectral break for a single power-law injected electron spectrum, with the spectrum flatter below the break, b) apparent early onset of low-e...

  11. Regulation of the solar wind electron heat fluxfrom 1 to 5 AU: Ulysses observations

    Science.gov (United States)

    Scime, Earl E.; Bame, Samuel J.; Feldman, William C.; Gary, S. Peter; Phillips, John L.; Balogh, Andre

    1994-01-01

    In this study we use observations from the three-dimensional electron spectrometer and magnetometer aboard the Ulysses spacecraft to examine the solar wind electron heat flux from 1.2 to 5.4 AU in the ecliptic plane. Throughout Ulusses' transit to 5.4 AU, the electron heat flux decreases more rapidly (approximately R(exp -30)) than simple collisionless expansion along the local magnetic field and is smaller than expected for a thermal gradient heat flux, q(sub parallel e) (r) = - Kappa(sub parallel) del(sub parallel) T(sub e)(r). The radial gradients and magnitudes expected for a number of electron heat flux regulatory mechanisms are examined and compared to the observations. The best agreement is found for heat flux regulation by the whistler heat flux instability. The upper bound and radial scaling for the electron heat flux predicted for the whistler heat flux instability are consistent with the observations.

  12. Direct observation of ultrafast-electron-transfer reactions unravels high effectiveness of reductive DNA damage

    OpenAIRE

    Nguyen, Jenny; Ma, Yuhan; Luo, Ting; Bristow, Robert G; Jaffray, David A; Lu, Qing-Bin

    2011-01-01

    Both water and electron-transfer reactions play important roles in chemistry, physics, biology, and the environment. Oxidative DNA damage is a well-known mechanism, whereas the relative role of reductive DNA damage is unknown. The prehydrated electron (), a novel species of electrons in water, is a fascinating species due to its fundamental importance in chemistry, biology, and the environment. is an ideal agent to observe reductive DNA damage. Here, we report both the first in situ femtosec...

  13. ONSETS AND SPECTRA OF IMPULSIVE SOLAR ENERGETIC ELECTRON EVENTS OBSERVED NEAR THE EARTH

    International Nuclear Information System (INIS)

    Impulsive solar energetic electrons are often observed in the interplanetary space near the Earth and have an attractive diagnostic potential for poorly understood solar flare acceleration processes. We investigate the transport of solar flare energetic electrons in the heliospheric plasma to understand the role of transport to the observed onset and spectral properties of the impulsive solar electron events. The propagation of energetic electrons in solar wind plasma is simulated from the acceleration region at the Sun to the Earth, taking into account self-consistent generation and absorption of electrostatic electron plasma (Langmuir) waves, effects of nonuniform plasma, collisions, and Landau damping. The simulations suggest that the beam-driven plasma turbulence and the effects of solar wind density inhomogeneity play a crucial role and lead to the appearance of (1) a spectral break for a single power-law injected electron spectrum, with the spectrum flatter below the break, (2) apparent early onset of low-energy electron injection, and (3) the apparent late maximum of low-energy electron injection. We show that the observed onsets, spectral flattening at low energies, and formation of a break energy at tens of keV is the direct manifestation of wave-particle interactions in nonuniform plasma of a single accelerated electron population with an initial power-law spectrum.

  14. Observation of optical emission from high refractive index waveguide excited by traveling electron beam

    OpenAIRE

    Kuwamura, Yuji; Yamada, Minoru; Okamoto, Ryuichi; Kanai, Takeshi; Fares, Hesham

    2008-01-01

    A new scheme for optical emission using a high refractive index waveguide and the traveling electron beam in vacuum was demonstrated. Optical emission around wavelength of 1.5 pm was observed for electron acceleration voltage of 40KV. © 2008 Optical Society of America.

  15. Manufacture and scanning electron microscopic observation of human dermis collagen membrane

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    @@ Introduction Collagen is a kind of biomacromolecule and can be used as cover material for burn wounds. In this article,we report the scanning electron microscopic observation of human dermis collagen membrane prepared by three methods.

  16. Observation of electron temperature turbulence with a correlation electron cyclotron emission radiometer on LHD

    International Nuclear Information System (INIS)

    Turbulence measurement is important in the study of plasma confinement. We developed a multi-channel correlation electron cyclotron emission (cECE) radiometer system, using an existing conventional ECE radiometer system (RADH) on a large helical device (LHD) . The signal received by the RADH was split and fed to our cECE system, and then electron temperatures at three separate radial positions were measured by resolving frequency component with three narrow (200 MHz) band-pass filters. Data taken by the cECE system were compared with those taken by the RADH system. Turbulence-like signals below 10 kHz were detected by the cECE measurement using coherence analysis, but were not detected by RADH measurement. We considered this to be due to differences in the radial separation length between the two channels and in the radial measurement depth of each channel. The cECE system was able to detect higher frequency turbulence because its separation length and measurement depth in the radial direction was shorter than the correlation length of the turbulence

  17. Electron microscopy observations of surface morphologies and particle arrangement behaviors of magnetic fluids

    Institute of Scientific and Technical Information of China (English)

    SHEN; Hui; (沈辉); XU; Xueqing; (徐雪青); WANG; Wei; (王伟)

    2003-01-01

    The surface morphology of quasi-periodic stripe-shaped patterns of magnetite fluids was observed in applied perpendicular magnetic fields by means of scanning electron microscopy. The nanoparticles of the magnetite fluids are arranged in oriental quasilinear chains in applied perpendicular magnetic fields as observed using transmission electron microscopy. This arrangement results from particle-particle interactions and particle-carrier liquids interactions, which are eventually controlled by the magnetic fields distribution.

  18. Chorus, ECH, and Z mode emissions observed at Jupiter and Saturn and possible electron acceleration

    OpenAIRE

    Menietti, J.D.; Y. Y. Shprits; Horne, R. B.; E. E. Woodfield; Hospodarsky, G. B.; Gurnett, D. A.

    2012-01-01

    In this paper we compare and contrast chorus, electron cyclotron harmonics (ECH), and Z mode emissions observed at Jupiter and Saturn and relate them to recent work on electron acceleration at Earth. Intense chorus emissions are observed near the magnetic equator, the likely source region, but the strongest intensities are on either side of the magnetic equator. Chorus intensities at Jupiter are generally about an order of magnitude larger than at Saturn, and the bandwidth of chorus at Jupite...

  19. Simulating satellite observations of 100 kHz radio waves from relativistic electron beams above thunderclouds

    OpenAIRE

    M. Füllekrug; Hanuise, C.; M. Parrot

    2010-01-01

    Relativistic electron beams above thunderclouds emit 100 kHz radio waves which illuminate the Earth's atmosphere and near-Earth space. This contribution aims to clarify the physical processes which are relevant for the spatial spreading of the radio wave energy below and above the ionosphere and thereby enables simulating satellite observations of 100 kHz radio waves from relativistic electron beams above thunderclouds. The simulation uses the DEMETER satellite which observes 100 kHz ...

  20. Radiation belt electron acceleration during the 17 March 2015 geomagnetic storm: Observations and simulations

    Science.gov (United States)

    Li, W.; Ma, Q.; Thorne, R. M.; Bortnik, J.; Zhang, X.-J.; Li, J.; Baker, D. N.; Reeves, G. D.; Spence, H. E.; Kletzing, C. A.; Kurth, W. S.; Hospodarsky, G. B.; Blake, J. B.; Fennell, J. F.; Kanekal, S. G.; Angelopoulos, V.; Green, J. C.; Goldstein, J.

    2016-06-01

    Various physical processes are known to cause acceleration, loss, and transport of energetic electrons in the Earth's radiation belts, but their quantitative roles in different time and space need further investigation. During the largest storm over the past decade (17 March 2015), relativistic electrons experienced fairly rapid acceleration up to ~7 MeV within 2 days after an initial substantial dropout, as observed by Van Allen Probes. In the present paper, we evaluate the relative roles of various physical processes during the recovery phase of this large storm using a 3-D diffusion simulation. By quantitatively comparing the observed and simulated electron evolution, we found that chorus plays a critical role in accelerating electrons up to several MeV near the developing peak location and produces characteristic flat-top pitch angle distributions. By only including radial diffusion, the simulation underestimates the observed electron acceleration, while radial diffusion plays an important role in redistributing electrons and potentially accelerates them to even higher energies. Moreover, plasmaspheric hiss is found to provide efficient pitch angle scattering losses for hundreds of keV electrons, while its scattering effect on > 1 MeV electrons is relatively slow. Although an additional loss process is required to fully explain the overestimated electron fluxes at multi-MeV, the combined physical processes of radial diffusion and pitch angle and energy diffusion by chorus and hiss reproduce the observed electron dynamics remarkably well, suggesting that quasi-linear diffusion theory is reasonable to evaluate radiation belt electron dynamics during this big storm.

  1. Electron beam observations in the near-earth plasma sheet boundary layer during active periods

    International Nuclear Information System (INIS)

    Complete text of publication follows. Electron beams are known to play an important role in the dynamics of the plasma sheet boundary layer. The interaction between high-frequency waves and such electron beams have been studied in detail by in-situ observations and simulations. However, electron observations are usually limited to obtaining some pitch-angle distribution in a relatively lower time resolution compared to the time-scales of the fields. In this study we used data from the Electron Drift Instrument (EDI) together with those from Plasma Electron And Current Experiment (PEACE) onboard Cluster to study the characteristics of electron beams associated with electric field disturbances during active plasma sheet boundary layer crossing events in the near-Earth tail. Although the primary purpose of the detector of the EDI instrument is to measure the artificial electron beams to obtain the drift velocity of these electrons, the detectors can be also used to measure natural electron flux at 500 eV (or 1 keV) in parallel/anti-parallel or perpendicular to the magnetic field with high time resolution ( up to 8 ms). In order to obtain a sub-spin profile of the parallel electron anisotropy, which is required to resolve small-scale structures within the plasma sheet boundary layer, we performed a relative calibration analysis by obtaining the correction factors among the different detector look directions on an event-by-event basis. In this presentation we show several examples when the anisotropy of 500 eV electrons are observed associated with disturbances in electric field and magnetic fields and describe their detailed profiles including their relationship between electrons and fields at small scales.

  2. Observation of hot-electron ring instabilities in ELMO Bumpy Torus

    International Nuclear Information System (INIS)

    A high-frequency hot electron instability is observed in ELMO Bumpy Torus (EBT) plasmas when the hot electron-to-ion density ratio exceeds 0.4. Both the real frequency and the imaginary frequency are larger than the ion cyclotron frequency. The azimuthal mode number (m) is 7, and the instability rotates in the hot electron curvature drift direction. This instability is identified as a curvature-driven mode. When it is strongly excited, the equilibrium of the hot electron annuli and confined core plasmas are destroyed (disruption). Extensive ion heating and neutron bursts are associated with this instability

  3. Solar wind dependence of the electron flux variation at geostationary orbit observed by ETS-V

    OpenAIRE

    Yokoyama,N./Goka,T./Matsumoto,H./Koga,K./Koshiishi, H./Kimoto, Y.

    2001-01-01

    In this study we have examined the relationship between the energetic electron flux at geostationary orbit and the solar wind speed. We have compared the electron flux ( >0.4MeV) observed by the Engineering Test Satellite V (ETS-V) with solar wind speed measurements in the OMNI data set obtained from the National Space Science Data Center (NSSDC). The tendency has been observed for the logarithm of the electron flux to be proportional to the solar wind speed at solar minimum, but scattered at...

  4. Hard- and software problems of spaced meteor observations by optical electronics

    Science.gov (United States)

    Shafiev, R. I.; Mukhamednazarov, S.; Ataev, A. SH.

    1987-01-01

    An optical electronic facility is being used for meteor observations along with meteor radars and astronomical TV. The main parts of the facility are cameras using UM-92 optical electronic image tubes. The three cascade optical electronic image tube with magnetic focusing has a 40 mm cathode and resolution in the center of up to 30 pairs of lines/mm. The photocathode is of a multislit S-20 type. For meteor spectra observations, replica gratings of 200 and 300 lines/mm are used as the dispersive element.

  5. Observations at the planet Mercury by the plasma electron experiment, Mariner 10

    International Nuclear Information System (INIS)

    Plasma electron observations made onboard Mariner 10 are reported. Three encounters with the planet Mercury show that the planet interacts with the solar wind to form a bow shock and a permanent magnetosphere. The observations provide a determination of the dimensions and properties of the magnetosphere, independently of and in general agreement with magnetometer observations. The magnetosphere of Mercury appears to be similar in shape to that of the Earth but much smaller in relation to the size of the planet. Electron populations similar to those found in the Earth's magnetotail, within the plasma sheet and adjacent regions, were observed at Mercury; both their spatial location and the electron energy spectra within them bear qualitative and quantitative resemblance to corresponding observations at the Earth. The magnetosphere of Mercury resembles to a marked degree a reduced version of that of the Earth, with no significant differences of structure

  6. Observations at the planet Mercury by the plasma electron experiment, Mariner 10

    Science.gov (United States)

    Ogilvie, K. W.; Scudder, J. D.; Vasyliunas, V. M.; Hartle, R. E.; Siscoe, G. L.

    1976-01-01

    Plasma electron observations made onboard Mariner 10 are reported. Three encounters with the planet Mercury show that the planet interacts with the solar wind to form a bow shock and a permanent magnetosphere. The observations provide a determination of the dimensions and properties of the magnetosphere, independently of and in general agreement with magnetometer observations. The magnetosphere of Mercury appears to be similar in shape to that of the Earth but much smaller in relation to the size of the planet. Electron populations similar to those found in the Earth's magnetotail, within the plasma sheet and adjacent regions, were observed at Mercury; both their spatial location and the electron energy spectra within them bear qualitative and quantitative resemblance to corresponding observations at the Earth. The magnetosphere of Mercury resembles to a marked degree a reduced version of that of the Earth, with no significant differences of structure.

  7. Experimental observation of electron-temperature-gradient turbulence in a laboratory plasma.

    Science.gov (United States)

    Mattoo, S K; Singh, S K; Awasthi, L M; Singh, R; Kaw, P K

    2012-06-22

    We report the observation of electron-temperature-gradient (ETG) driven turbulence in the laboratory plasma of a large volume plasma device. The removal of unutilized primary ionizing and nonthermal electrons from uniform density plasma and the imposition and control of the gradient in the electron temperature (T[Symbol: see text] T(e)) are all achieved by placing a large (2 m diameter) magnetic electron energy filter in the middle of the device. In the dressed plasma, the observed ETG turbulence in the lower hybrid range of frequencies ν = (1-80 kHz) is characterized by a broadband with a power law. The mean wave number k perpendicular ρ(e) = (0.1-0.2) satisfies the condition k perpendicular ρ(e) ≤ 1, where ρ(e) is the electron Larmor radius. PMID:23004612

  8. Rhea's magnetospheric interaction: energetic electron observations by Cassini MIMI/LEMMS

    Science.gov (United States)

    Roussos, E.; Kollmann, P.; Krupp, N.; Paranicas, C.; Persoon, A.; Kriegel, H.; Simon, S.; Khurana, K.; Krimigis, S. M.; Mitchell, D. G.

    2012-04-01

    Although Rhea is a plasma absorbing moon, energetic particle observations in its vicinity show a variety of unexpected interaction features, besides the expected wake signature. Energetic electron data contain a series of flux depletions, some of which extend up to 8 moon radii on each side of the wake. The association of these depletions with absorption by dust and boulders orbiting within Rhea's Hill sphere was not confirmed, so in this study we review data from all four Cassini flybys of Rhea to date seeking for alternative interpretations. We focus on energetic electron observations, which are placed in context with magnetometer and cold plasma electron density data. The most interesting common structure in all flybys is that of narrow dropouts in energetic electron fluxes, visible near the wake flanks. These are typically seen together with narrow flux enhancements inside the wake. A phase-space-density analysis indicates that these structures form due to rapid transport of energetic electrons from the magnetosphere to the wake, through narrow channels. The possibility that this transport is a signature of a flute (interchange) instability that acts on the electrons is discussed. Besides the small structures, there are many more puzzling observations. For instance the electron number density appears unaffected during Rhea's wake crossings, although the magnetometer shows signatures consistent with plasma pressure loss due to ion absorption at Rhea. The impact of such observations in understanding Rhea's system is also discussed.

  9. Observation of 8600 K electron temperature in AlGaN/GaN high electron mobility transistors on Si substrate

    International Nuclear Information System (INIS)

    The electron temperature (T e) in AlGaN/GaN high electron mobility transistors (HEMTs) on Si was studied by spectroscopic measurements of its electroluminescence (EL). The EL spectrum has been followed by the Maxwell–Boltzmann distribution and no signal at equivalent energy as a band-gap of GaN has been observed. These experimental results imply that the EL is dominated by an intra-band transition. The highest T e of 8600 K in AlGaN/GaN HEMTs was extracted at the drain voltage of 60 V. The experimental results are in agreement with results previously predicted by a Monte Carlo simulation. (paper)

  10. Electron distributions observed with Langmuir waves in the plasma sheet boundary layer

    International Nuclear Information System (INIS)

    The present paper investigates the Langmuir turbulence driven by counter-streaming electron beams and its plausible association with observed features in the Earth's plasma sheet boundary layer region. A one-dimensional electrostatic particle-in-cell simulation code is employed in order to simulate broadband electrostatic waves with characteristic frequency in the vicinity of the electron plasma frequency ω/ωpe≃1.0. The present simulation confirms that the broadband electrostatic waves may indeed be generated by the counter-streaming electron beams. It is also found that the observed feature associated with low energy electrons, namely quasi-symmetric velocity space plateaus, are replicated according to the present simulation. However, the present investigation only partially succeeds in generating the suprathermal tails such that the origin of observed quasi power-law energetic population formation remains outstanding

  11. The observations of high energy electrons and associated waves by DSP satellites during substorm

    International Nuclear Information System (INIS)

    Double Star Program (DSP) is a CNSA-ESA cooperation mission. DSP consists of two satellites: Equatorial satellite (TC-1) and Polar satellite (TC-2). This paper presents important observations of long duration loss of high energetic electrons and relevant waves in the recovery phase of substorm, that are made by LFEW and HEED of the polar satellite of DSP (TC-2). The HEED of TC-2 observed a loss event of high energetic electrons which lasted about 4 minute. At the same time, the LFEW of TC-2 observed a wave burst. The wave burst began 1 minute earlier than the loss event of energetic electrons. The frequency of waves ranges form 600 Hz to over 10 kHz. The analyses of wave characteristics indicate that the wave was whistler-mode. Thus it is very possible that the loss of high energy electrons was caused by wave activities through wave-particle interactions

  12. OBSERVATION OF HEATING BY FLARE-ACCELERATED ELECTRONS IN A SOLAR CORONAL MASS EJECTION

    International Nuclear Information System (INIS)

    We report a Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) observation of flare-accelerated electrons in the core of a coronal mass ejection (CME) and examine their role in heating the CME. Previous CME observations have revealed remarkably high thermal energies that can far surpass the CME's kinetic energy. A joint observation by RHESSI and the Atmospheric Imaging Assembly of a partly occulted flare on 2010 November 3 allows us to test the hypothesis that this excess energy is collisionally deposited by flare-accelerated electrons. Extreme ultraviolet (EUV) images show an ejection forming the CME core and sheath, with isothermal multifilter analysis revealing temperatures of ∼11 MK in the core. RHESSI images reveal a large (∼100 × 50 arcsec2) hard X-ray (HXR) source matching the location, shape, and evolution of the EUV plasma, indicating that the emerging CME is filled with flare-accelerated electrons. The time derivative of the EUV emission matches the HXR light curve (similar to the Neupert effect observed in soft and HXR time profiles), directly linking the CME temperature increase with the nonthermal electron energy loss, while HXR spectroscopy demonstrates that the nonthermal electrons contain enough energy to heat the CME. This is the most direct observation to date of flare-accelerated electrons heating a CME, emphasizing the close relationship of the two in solar eruptive events

  13. Conversion from electron plasma waves to type III solar radio bursts with 'HELIOS' observations

    International Nuclear Information System (INIS)

    The purpose of this paper is to introduce new HELIOS observation which confirm the basic mechanism of type 3 solar radio bursts and then to compare them with ground and/or near earth satellite observations. It is considered that the bursts are generated by a two-step process. The process is the production of localized electron plasma oscillation and the conversion of this plasma oscillation to escaping electromagnetic radiation. Variations of the characteristic frequency of solar radio bursts come from the gradual decrease in the electron plasma frequency encountered. Examples of the temporal distributions of electron plasma oscillations and associated type 3 solar radio bursts are shown. The so-called ''forward drift'' is seen. Another example shows that the burst sources are distributed along a spiral magnetic field in the interplanetary space. The result of comparison of conventional ground and recent HELIOS observations is presented. The frequency range of the type 3 bursts is from 10 to 200 kHz in case of HELIOS, which is much lower than the frequency observed on the ground. Source location, dynamic spectrum, duration time of burst, drift rate, flare electron velocity, electron plasma oscillation, location of EPO or solar flare electrons, intensities of fundamental and harmonic frequencies, and polarization were also compared between ground and HELIOS observations. (Kato, T.)

  14. An observer study for direct comparison of clinical efficacy of electronic to film portal images

    International Nuclear Information System (INIS)

    Purpose: To directly compare clinical efficacy of electronic to film portal images. Methods and Materials: An observer study was designed to compare clinical efficacy of electronic to film portal images acquired using a liquid matrix ion-chamber electronic portal imaging device and a conventional metal screen/film system. Both images were acquired simultaneously for each treatment port and the electronic portal images were printed on gray-level thermal paper. Four radiation oncologists served as observers and evaluated a total of 44 sets of images for four different treatment sites: lung, pelvis, brain, and head/neck. Each set of images included a simulation image, a double-exposure portal film, and video paper prints of electronic portal images. Eight to nine anatomical landmarks were selected from each treatment site. Each observer was asked to rate each landmark in terms of its clinical visibility and to rate the ease of making the pertinent verification decision in the corresponding electronic and film portal images with the aid of the simulation image. Results: Ratings for the visibility of landmarks and for the verification decision of treatment ports were similar for electronic and film images for most landmarks. However, vertebral bodies and several landmarks in the pelvis such as the acetabulum and pubic symphysis were more visible in the portal film images than in the electronic portal images. Conclusion: The visibility of landmarks in electronic portal images is comparable to that in film portal images. Verification of treatment ports based only on electronic portal images acquired using an electronic portal imaging device is generally achievable

  15. Electron Cloud Observations with LHC-Type Beams in the SPS

    CERN Document Server

    Arduini, Gianluigi; Gröbner, Oswald; Hilleret, Noël; Höfle, Wolfgang; Jiménez, J M; Laurent, Jean Michel; Moulard, G; Pivi, M; Weiss, K P

    2000-01-01

    In August 1999, strong pressure increases were observed in the SPS in the presence of the new LHC-type beams. This paper reports on observations of the electron cloud phenomenon and the related pressure increase as a function of parameters such as the number of protons per bunch, the number of bunches per batch, the shape of the vacuum chamber and the electron current collected on pick-ups. Results of the observed clean-up, "beam scrubbing" will be presented as well as the consequences of the e-cloud phenomenon on the SPS operation with the LHC nominal beam intensity.

  16. Density response to central electron heating: theoretical investigations and experimental observations in ASDEX Upgrade

    International Nuclear Information System (INIS)

    Theory of ion temperature gradient (ITG) and trapped electron modes (TEMs) is applied to the study of particle transport in experimental conditions with central electron heating. It is shown that in the unstable domain of TEMs, the electron thermo diffusive flux is directed outwards. By means of such a flux, a mechanism is identified likely to account for density flattening with central electron heating. Theoretical predictions are compared with experimental observations in ASDEX Upgrade. A parameter domain (including L- and H-mode plasmas) is identified, in which flattening with central electron heating is observed in the experiments. In general, this domain turns out to be the same domain in which the dominant plasma instability is a TEM. On the contrary, the dominant instability is an ITG in plasmas whose density profile is not affected significantly by central electron heating. The flattening predicted by quasi-linear theory for low density L-mode plasmas is too small compared to the experimental observations. At very high density, even when the dominant instability is an ITG, electron heating can provide density flattening, via the coupling with the ion heat channel. In these conditions the anomalous diffusivity increases in response to the increased ion heat flux, while the large collisionality makes the anomalous pinch small and the Ware pinch important. (author)

  17. Rocket observation of energetic electrons in the low-altitude auroral ionosphere during the DELTA campaign

    Science.gov (United States)

    Ogasawara, K.; Asamura, K.; Takashima, T.; Saito, Y.; Mukai, T.

    2006-09-01

    This paper reports on properties of energetic electrons observed by the Auroral Particle Detector (APD) on board the sounding rocket S-310-35, which was launched from And/0ya Rocket Range, Norway, at 0033:00 UT on 13 December 2004 during the DELTA campaign. The APD was designed to measure energy spectra of energetic electrons in the range of 3.5 to 65 keV every 10 ms using avalanche photodiodes. The measurement was done at altitudes of 90-140 km (apogee height of the rocket flight), which corresponded to the collisional interaction region of precipitating electrons with the atmospheric constituents. The overall profile of energetic electron precipitations was consistent with auroral images taken from the ground. The downward fluxes almost always exceeded those of upward electrons, and the ratio of downward to upward fluxes increased with energy and also with altitude. This is reasonably understood in terms of the effect of collisions between the energetic electrons and the atmospheric constituents. An interesting feature in energy spectra of precipitating electrons is the existence of non-thermal electrons at higher energies, regardless of inside or outside of auroral arcs. In order to predict the incident downward spectra at the top of the atmosphere, we have applied an analytic method of Luhmann (1976) to evaluate the collisional effect on the electron spectra. As a result, most of the observed energy spectra of precipitating electrons are well expressed by kappa distributions with the thermal energy of a few hundreds of eV and kappa of 5-8, while the spectrum inside a strong arc is better fitted by the sum of a Maxwellian distribution on the lower energy side and a power law at higher energies. To the authors' knowledge, this is the first direct and reliable measurement of energy spectra of electrons in the 10-keV energy range in the auroral ionosphere.

  18. Suprathermal Electrons in Titan’s Sunlit Ionosphere: Model–Observation Comparisons

    Science.gov (United States)

    Vigren, E.; Galand, M.; Wellbrock, A.; Coates, A. J.; Cui, J.; Edberg, N. J. T.; Lavvas, P.; Sagnières, L.; Snowden, D.; Vuitton, V.; Wahlund, J.-E.

    2016-08-01

    The dayside ionosphere of the Saturnian satellite Titan is generated mainly from photoionization of N2 and CH4. We compare model-derived suprathermal electron intensities with spectra measured by the Cassini Plasma Spectrometer/Electron Spectrometer (CAPS/ELS) in Titan's sunlit ionosphere (altitudes of 970–1250 km) focusing on the T40, T41, T42, and T48 Titan flybys by the Cassini spacecraft. The model accounts only for photoelectrons and associated secondary electrons, with a main input being the impinging solar EUV spectra as measured by the Thermosphere Ionosphere Mesosphere Energy and Dynamics/Solar EUV Experiment and extrapolated to Saturn. Associated electron-impact electron production rates have been derived from ambient number densities of N2 and CH4 (measured by the Ion Neutral Mass Spectrometer/Closed Source Neutral mode) and related energy-dependent electron-impact ionization cross sections. When integrating up to electron energies of 60 eV, covering the bulk of the photoelectrons, the model-based values exceed the observationally based values typically by factors of ˜3 ± 1. This finding is possibly related to current difficulties in accurately reproducing the observed electron number densities in Titan's dayside ionosphere. We compare the utilized dayside CAPS/ELS spectra with ones measured in Titan's nightside ionosphere during the T55–T59 flybys. The investigated nightside locations were associated with higher fluxes of high-energy (>100 eV) electrons than the dayside locations. As expected, for similar neutral number densities, electrons with energies <60 eV give a higher relative contribution to the total electron-impact ionization rates on the dayside (due to the contribution from photoelectrons) than on the nightside.

  19. Suprathermal Electrons in Titan’s Sunlit Ionosphere: Model–Observation Comparisons

    Science.gov (United States)

    Vigren, E.; Galand, M.; Wellbrock, A.; Coates, A. J.; Cui, J.; Edberg, N. J. T.; Lavvas, P.; Sagnières, L.; Snowden, D.; Vuitton, V.; Wahlund, J.-E.

    2016-08-01

    The dayside ionosphere of the Saturnian satellite Titan is generated mainly from photoionization of N2 and CH4. We compare model-derived suprathermal electron intensities with spectra measured by the Cassini Plasma Spectrometer/Electron Spectrometer (CAPS/ELS) in Titan's sunlit ionosphere (altitudes of 970–1250 km) focusing on the T40, T41, T42, and T48 Titan flybys by the Cassini spacecraft. The model accounts only for photoelectrons and associated secondary electrons, with a main input being the impinging solar EUV spectra as measured by the Thermosphere Ionosphere Mesosphere Energy and Dynamics/Solar EUV Experiment and extrapolated to Saturn. Associated electron-impact electron production rates have been derived from ambient number densities of N2 and CH4 (measured by the Ion Neutral Mass Spectrometer/Closed Source Neutral mode) and related energy-dependent electron-impact ionization cross sections. When integrating up to electron energies of 60 eV, covering the bulk of the photoelectrons, the model-based values exceed the observationally based values typically by factors of ∼3 ± 1. This finding is possibly related to current difficulties in accurately reproducing the observed electron number densities in Titan's dayside ionosphere. We compare the utilized dayside CAPS/ELS spectra with ones measured in Titan's nightside ionosphere during the T55–T59 flybys. The investigated nightside locations were associated with higher fluxes of high-energy (>100 eV) electrons than the dayside locations. As expected, for similar neutral number densities, electrons with energies <60 eV give a higher relative contribution to the total electron-impact ionization rates on the dayside (due to the contribution from photoelectrons) than on the nightside.

  20. FURTHER OBSERVATION OF THE SPERMATOZOA OF LEFT-EYE FLOUNDER PARALICHTHYS OLIVACEUS BY ELECTRONIC MICROSCOPY

    Institute of Scientific and Technical Information of China (English)

    王宏田; 张培军; 谢嘉琳; 姜明

    2002-01-01

    The spermatozoon ultrastructure of left-eye flounder, Paralichthys olivaceus, was observed by electronic microscopy, and shown to consist of head, midpiece and tail. Some nuclear vacuoles were observed inside and along the outer part of the nucleus and double-membrane structures were observed between the nuclear membrane and plasma membrane. The sperm sleeve consisted of four independent parts and had more than four mitochondria. Along the sperm tail there were wing-like lateral fins.``

  1. In-situ observation of electron kappa distributions associated with discrete auroral arcs

    Science.gov (United States)

    Ogasawara, Keiichi; Livadiotis, George; Samara, Marilia; Michell, Robert; Grubbs, Guy

    2016-04-01

    The Medium-energy Electron SPectrometer (MESP) sensor aboard a NASA sounding rocket was launched from Poker Flat Research Range on 3 March 2014 as a part of Ground-to-Rocket Electrodynamics-Electrons Correlative Experiment (GREECE) mission. GREECE targeted to discover convergent E-field structures at low altitude ionosphere to find their contribution to the rapid fluid-like structures of aurora, and MESP successfully measured the precipitating electrons from 2 to 200 keV within multiple discrete auroral arcs with the apogee of 350 km. MESP's unprecedented electron energy acceptance and high geometric factor made it possible to investigate precise populations of the suprathermal components measured in the inverted-V type electron energy distributions. The feature of these suprathermal electrons are explained by the kappa distribution functions with the parameters (densty, temperature, and kappa) consistent with the near-Earth tail plasma sheet, suggesting the source population of the auroral electrons. The kappa-values are different between each arc observed as a function of latitude, but are almost stable within one discrete arc. We suggest that this transition of kappa reflects the probagation history of source electrons through the plasma sheet by changing its state from non-equilibrium electron distributions to thermal ones.

  2. VLF wave emissions by pulsed and dc electron beams in space. I - Spacelab 2 observations

    Science.gov (United States)

    Reeves, G. D.; Banks, P. M.; Neubert, T.; Bush, R. I.; Williamson, P. R.

    1988-01-01

    The properties of radio waves generated by electron beams in space were investigated using data from the wideband wave receiver on the Spacelab 2. The VLF observations were found to confirm the results of the STS 3/OSS-1 mission. It was found that a 1-keV electron beam injected from the orbiter produced copious broadband electromagnetic emissions. When the electron beam was square-wave modulated, narrow-band emissions at the pulsing frequency and harmonics of that frequency were produced along with the broadband emissions. The observations indicated that dc 50-mA electron beams and pulsed 50-percent duty-cycle 100-mA beams produce broadband radiation which is comparable in intensity and spectral shape at all points for which the wave field was sampled.

  3. Precipitation of radiation belt electrons by EMIC waves, observed from ground and space

    Energy Technology Data Exchange (ETDEWEB)

    Jordanova, Vania K [Los Alamos National Laboratory; Miyoski, Y [NAGOYA UNIV; Sakaguchi, K [NAGOYA UNIV; Shiokawa, K [NAGOYA UNIV; Evans, D S [NOAA, BOULDER; Albert, Jay [AFRL; Connors, M [UNIV OF ATHABASCA

    2008-01-01

    We show evidence that left-hand polarised electromagnetic ion cyclotron (EMIC) plasma waves can cause the loss of relativistic electrons into the atmosphere. Our unique set of ground and satellite observations shows coincident precipitation of ions with energies of tens of keY and of relativistic electrons into an isolated proton aurora. The coincident precipitation was produced by wave-particle interactions with EMIC waves near the plasmapause. The estimation of pitch angle diffusion coefficients supports that the observed EMIC waves caused coincident precipitation ofboth ions and relativistic electrons. This study clarifies that ions with energies of tens of ke V affect the evolution of relativistic electrons in the radiation belts via cyclotron resonance with EMIC waves, an effect that was first theoretically predicted in the early 1970's.

  4. Direct Observation of a Semi-Bare Electron Coulomb Field Recover

    CERN Document Server

    Naumenko, G; Shevelev, M

    2011-01-01

    The problem of "semi-bare electron" was first considered in frame of quantum electrodynamics by E.L. Feinberg in 1980. In theory in frame of classical electrodynamics this problem was touched on in articles of N.F. Shul'ga and X. Artru. In 2008 the experimental investigations of this phenomenon in millimeter wavelength region were started by the group of scientists, including authors of this article. Used technique allowed us to study this effect in macroscopic mode. In this paper we present the results of direct observation of a semi-bare electron coulomb field recovery. The semi-bare state was obtained by passing of electron beam through the hole in a conductive screen. Measured spatial distribution of electromagnetic field shows the process of recover of the electron coulomb field, which is followed by a forward radiation. The experiments were performed on the relativistic electron beam of the microtron of Tomsk Polytechnic University.

  5. Observation of electron-temperature fluctuations triggered by supersonic gas puffing in the LHD

    International Nuclear Information System (INIS)

    Non-local transport and electron temperature fluctuations triggered by supersonic gas puffing (SSGP) in high-temperature helical plasmas in the Large Helical Device (LHD) are reported. After a short-pulse SSGP, the core electron temperature increased while the edge electron temperature decreased. SSGP triggered a longer core temperature increase than that triggered by a small impurity pellet injection. The temperature profile, which was relatively flat inside the half minor radius before SSGP, became parabolic after non-local transport was triggered. Fluctuations were excited in the electron temperature signals around the half minor radius. The frequency of these fluctuations increased from ∼ 400 Hz to ∼ 1 kHz within ∼ 0.1 s and the amplitude decreased correspondingly. The temperature fluctuations inside and outside of the half minor radius had opposite phases. Magnetic fluctuations resonating near the half minor radius were observed simultaneously with the electron temperature fluctuations. (author)

  6. Electron fluxes and pitch-angle distributions at dipolarization fronts: THEMIS multipoint observations

    Science.gov (United States)

    Runov, A.; Angelopoulos, V.; Gabrielse, C.; Zhou, X.-Z.; Turner, D.; Plaschke, F.

    2013-02-01

    Taking advantage of multipoint observations from a Cluster-like Time History of Events and Macroscale Interactions during Substorms (THEMIS) probe configuration repeated in three events, we study pitch-angle distributions (PAD) of lower energy (0.2-keV) electrons and omnidirectional energy-time spectrograms of higher energy (30-500 keV) electrons observed at and near dipolarization fronts in the plasma sheet. Recent observations have shown that dipolarization fronts in the plasma sheet provide an impulsive electric field suggested to cause electron energization and dispersionless injections. Increase and decrease in energetic electron flux are equally probable at the fronts, however. Our case studies demonstrate increased energetic electron flux in the front's central region but decreased flux on its dusk side, where diverted plasma flow forms a vortex. An electric field associated with this vortex causes the electron flux decrease. We also find that shorter-term energetic flux decreases, often observed before injections, coincide with a dip in the northward magnetic field ahead of the front. We attribute these decreases to particle energy loss via the inverse betatron effect. Our case studies reveal that pancake-type (maximum at 90° pitch angle) and cigar-type (maxima at 0 and 180°) PADs coexist at the same front. Our data analysis suggests that energetic electron PADs are mainly pancake type near the neutral sheet (|Bx| cigar type at |Bx| > 10 nt. These results, to be confirmed in statistical studies, provide important constraints for further modeling of electron energization and transport toward the inner magnetosphere.

  7. Near-Curie magnetic anomaly at the Ni/C interface observed by Electron Holography

    DEFF Research Database (Denmark)

    Ferrari, Loris; Matteucci, Giorgio; Schofield, Marvin A;

    2010-01-01

    We analyze with electron holography carried out in a transmission electron microscope the near-Curie behavior of magnetism at the edge of a Nickel thin film coated with Carbon. In-situ experiments with finely controlled variations of the sample temperature reveal an anomaly in the ferromagnetic to...... features of the observed signal. The model is developed in terms of an anisotropic, temperature dependent exchange coupling between the Nickel moments at the Carbon interface that favors their vertical alignment at low temperatures....

  8. Ultrafast electron diffraction and direct observation of transient structures in a chemical reaction

    OpenAIRE

    Cao, Jianming; Ihee, Hyotcherl; Zewail, Ahmed H.

    1999-01-01

    Ultrafast electron diffraction is a unique method for the studies of structural changes of complex molecular systems. In this contribution, we report direct ultrafast electron diffraction study of the evolution of short-lived intermediates in the course of a chemical change. Specifically, we observe the transient intermediate in the elimination reaction of 1,2-diiodotetrafluoroethane (C2F4I2) to produce the corresponding ethylene derivative by the breakage of two carbon-iodine, C---I, bonds. ...

  9. Observation and characterization of laser-driven Phase Space Electron Holes

    OpenAIRE

    Sarri, Gianluca; Dieckmann, Mark Eric; Brown, C. R. D.; Cecchetti, Carlo; Hoarty, D.J.; James, S.F.; Jung, R.; Kourakis, Ioannis; Schamel, H.; Willi, O.; Borghesi, Marco

    2010-01-01

    The direct observation and full characterization of a phase space electron hole (EH) generated during laser-matter interaction is presented. This structure, propagating in a tenuous, nonmagnetized plasma, has been detected via proton radiography during the irradiation with a ns laser pulse (I?2 ˜ 1014 W/cm2) of a gold hohlraum. This technique has allowed the simultaneous detection of propagation velocity, potential, and electron density spatial profile across the EH with fine spatial and temp...

  10. POES SEM-2 observations of radiation belt dynamics and energetic electron precipitation in to the atmosphere

    International Nuclear Information System (INIS)

    Complete text of publication follows. The coupling of the Van Allen radiation belts to the Earth's atmosphere through the effects of precipitating particles is an area of intense scientific interest. Currently, there are significant uncertainties surrounding the precipitating characteristics of medium energy electrons (>20 keV), and even more uncertainties for relativistic electrons. In this paper we examine roughly ten-years of measurements of trapped and precipitating electrons available from the Polar Orbiting Environmental Satellites (POES)/Space Environment Monitor (SEM-2) which has provided long-term global data in this energy range. Relativistic electron increases are associated with both interplanetary Coronal Mass Ejections (ICMEs) and periodic high speed solar wind streams (HSSWS). The processes triggered by ICMEs are roughly twice as effective at enhancing POES-observed electrons to relativistic energies as the processes triggered by HSSWS. We find that ICME-associated increases can extend down to L∼2, while other enhancements are generally limited to L>3.5. Finally, during HSSWS conditions there is an energy-dependent time delay observed in the POES/SEM-2 observations, with the >800 keV relativistic electron enhancement delayed by ∼1-week relative to the >30 keV electron enhancement, probably due to the timescales of the acceleration processes. One possible interpretation of this is a two-stage process, where relatively rapid acceleration initially takes place near the geomagnetic equator as predicted by theory and observed experimentally. This is followed by a much slower process, where the relativistic electrons scatter towards the atmosphere loss cone at a rate which is energy dependent. Such large delays should have consequences for the timing of the atmospheric impact of HSSWS-triggered geomagnetic storms.

  11. Electron microscopic observation of montmorillonite swelled by water with the aid of hydrophilic ionic liquid

    International Nuclear Information System (INIS)

    The morphology and structure of hydrous montmorillonite in different swelling condition have been observed with the aid of hydrophilic ionic liquid (IL; 1-Butyl-3-methylimidazolium Tetrafluoroborate) using electron microscope. The observation mechanism of hydrous montmorillonite with layer structure using IL was revealed by swelling behavior as measured by X-ray diffraction (XRD) and transmission electron microscopy (TEM) with selected area electron diffraction pattern (SAED). The morphology of hydrous montmorillonite containing a large amount of water was also successfully observed by field emission electron microscope (FE-SEM). In addition, the inductively coupled plasma (ICP) and thermogravimetric – differential thermal analysis (TG-DTA) results showed the ion-exchange behavior of hydrous montmorillonite during the IL treatment. The technique allowed the exact morphology to be observed of hydrated materials with layer structure in civil engineering, cosmetics, medical and agricultural fields. - Highlights: • Observation of two different conditions of hydrated montmorillonite was investigated. • The swelling structure by water molecules was characterized by TEM. • The observation mechanism of hydrous montmorillonite was revealed. • Ionic liquid is useful for characterization of hydrated materials with layer structure

  12. Electron microscopic observation of montmorillonite swelled by water with the aid of hydrophilic ionic liquid

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Chisato [Advanced Ceramics Research Center, Nagoya Institute of Technology, Honmachi 3-101-1, Tajimi, Gifu 507-0033 (Japan); Department of Pharmaceutical Engineering, School of Pharmacy, Aichi Gakuin University, Kusumoto 1-100, Chikusa, Nagoya, Aichi 464-8650 (Japan); Shirai, Takashi [Advanced Ceramics Research Center, Nagoya Institute of Technology, Honmachi 3-101-1, Tajimi, Gifu 507-0033 (Japan); Fuji, Masayoshi, E-mail: fuji@nitech.ac.jp [Advanced Ceramics Research Center, Nagoya Institute of Technology, Honmachi 3-101-1, Tajimi, Gifu 507-0033 (Japan)

    2013-09-16

    The morphology and structure of hydrous montmorillonite in different swelling condition have been observed with the aid of hydrophilic ionic liquid (IL; 1-Butyl-3-methylimidazolium Tetrafluoroborate) using electron microscope. The observation mechanism of hydrous montmorillonite with layer structure using IL was revealed by swelling behavior as measured by X-ray diffraction (XRD) and transmission electron microscopy (TEM) with selected area electron diffraction pattern (SAED). The morphology of hydrous montmorillonite containing a large amount of water was also successfully observed by field emission electron microscope (FE-SEM). In addition, the inductively coupled plasma (ICP) and thermogravimetric – differential thermal analysis (TG-DTA) results showed the ion-exchange behavior of hydrous montmorillonite during the IL treatment. The technique allowed the exact morphology to be observed of hydrated materials with layer structure in civil engineering, cosmetics, medical and agricultural fields. - Highlights: • Observation of two different conditions of hydrated montmorillonite was investigated. • The swelling structure by water molecules was characterized by TEM. • The observation mechanism of hydrous montmorillonite was revealed. • Ionic liquid is useful for characterization of hydrated materials with layer structure.

  13. Note: Coherent resonances observed in the dissociative electron attachment to carbon monoxide

    International Nuclear Information System (INIS)

    Succeeding our previous finding about coherent interference of the resonant states of CO− formed by the low-energy electron attachment [Tian et al. Phys. Rev. A 88, 012708 (2013)], here we provide further evidence of the coherent interference. The completely backward distributions of the O− fragment of the temporary CO− are observed with anion velocity map imaging technique in an electron energy range of 11.3–12.6 eV and explained as the results of the coherent interferences of three resonant states. Furthermore, the state configuration of the interference is changed with the increase of electron attachment energy

  14. On measuring the electron heat diffusion coefficient in a tokamak from sawtooth oscillation observations

    International Nuclear Information System (INIS)

    A number of new methods are discussed for determining the electron heat conduction coefficient chisub(e) in a tokamak from the experimental observation of the space-time evolution of the temperature perturbations induced by internal disruptions. In the Oak Ridge Tokamak (ORMAK) the various average values of chisub(e) and the radial dependence of chisub(e) are found to be consistent with and more precise than the chisub(e)(r) determined by conventionally analysing the electron power balance equation. The net result of these measurements is to conclusively prove that the dominant radial electron heat transport mechanism in tokamaks is a microscopic, diffusive process. (author)

  15. Observations of fast magnetospheric echoes of artificially injected electrons above an auroral arc

    International Nuclear Information System (INIS)

    Electron beam experiments using rocket-borne instrumentation have confirmed earlier observations of fast magnetospheric echoes of artificially injected energetic electrons. These experiments were jointly carried out by the University of Minnesota, the National Research Council of Canada and the Max-Planck-Institut fuer Aeronomie. A total of 234 echoes have been observed in a pitch angle range from 00 to 1100 at energies of 1.87 and 3.90 keV. Out of this number, 95 echoes could unambiguously be identified with known accelerator operations at 2, 4 or 8 keV energy and highest current levels resulting in the determination of transit times of typically 400 ms. In most cases, when echoes were present in both energy channels, the higher energy electrons led the lower energy ones by approximately 50 ms. No echoes have been found in the 7.9 keV-detector channels. Adiabatic theory applied to these observations yields a reflection height of 3000 to 4000 km. The injection process is briefly discussed as the strong beam-plasma interaction that occurred near the electron accelerator appears to be instrumental in generating the source of heated electrons required for successful echo detection. Two consequences of this interaction, namely, strong energy and pitch angle diffusion and electron acceleration are illustrated with several examples. (orig.)

  16. Ulysses observations of electron and proton components in a magnetic cloud and related wave activity

    Science.gov (United States)

    Osherovich, V. A.; Fainberg, J.; Stone, R. G.; MacDowall, R. J.; Phillips, J. L.; Balogh, A.

    1995-01-01

    In addition to a smooth rotation of the magnetic field vector, magnetic clouds have a low proton temperature T(sub p). Their expansion in the solar wind leads to depletion and therefore the ion component cools down. It has been shown recently that the electron component in magnetic clouds behaves differently: when the cloud expands, electron temperature Te anti correlates with density and therefore Te increases in the cloud, creating favorable conditions for the rise of ion-acoustic waves. For the magnetic cloud observed by Ulysses on June 10 - 12, 1993 at 4.64 AU at S 32.5 deg, we present observations for both electron and proton components and related plasma wave activity. Our results confirm the anti correlation between T(sub e) and electron density and also exhibit a high ratio of T(sub e)/T(sub P) in the cloud. Since Landau damping is not effective for T(sub e)/T(sub p) much greater than 1, Doppler shifted ion acoustic waves are expected in the cloud. Calculation of ion acoustic wave frequencies in the cloud and comparison with observed wave activity confirm this expectation. As in our previous work, we show that the electron component in the cloud obeys a polytropic law with gamma is less than 1 (gamma approximately equals 0.3-0.4). The dynamics of the magnetic cloud are determined to a large degree by the dominating electron pressure.

  17. In Situ Observations of Ion Scale Current Sheets and Associated Electron Heating in Turbulent Space Plasmas

    Science.gov (United States)

    Chasapis, A.; Retino, A.; Sahraoui, F.; Greco, A.; Vaivads, A.; Khotyaintsev, Y. V.; Sundkvist, D. J.; Canu, P.

    2014-12-01

    We present a statistical study of ion-scale current sheets in turbulent space plasma. The study was performed using in situ measurements from the Earth's magnetosheath downstream of the quasi-parallel shock. Intermittent structures were identified using the Partial Variance of Increments method. We studied the distribution of the identified structures as a function of their magnetic shear angle, the PVI index and the electron heating. The properties of the observed current sheets were different for high (>3) and low (PVI index. We observed a distinct population of high PVI (>3) structures that accounted for ~20% of the total. Those current sheets have high magnetic shear (>90 degrees) and were observed mostly in close proximity to the bow shock with their numbers reducing towards the magnetopause. Enhancement of the estimated electron temperature within these current sheets suggest that they are important for local electron heating and energy dissipation.

  18. Optical phenomena observed in low-energy ion and electron bombardment of silica surfaces

    International Nuclear Information System (INIS)

    Optical spectroscopy has been used to characterize the interaction of ionizing radiation with glasses, including ions with energies in the 3--10 keV range, and electrons with energies ranging from 320 to 640 eV. Characteristic line emission spectra of desorbed excited atoms, as well as luminescence spectra from the near-surface bulk, were observed. A search for possible changes in desorption mechanisms as a function of radiation dose was carried out by observing the time dependence of integrated intensity and spectral linewidth for desorbed silicon and the trace element calcium. Defect formation in the near-surface bulk was monitored by spectrally resolved, time-dependent measurements of the bulk luminescence and by electron paramagnetic resonance spectroscopy. These spectroscopic observations are correlated with identifiable differences in the manufacturing processes of several silicas, and thus can be related to one particular kind of surface radiation damage, namely, ion- and electron-induced desorption

  19. Electron microscopy observations of titanium irradiated with GeV heavy ions

    International Nuclear Information System (INIS)

    GeV heavy ions induce the creation of damage in some metallic targets via electronic excitation. We report here on room temperature electron microscopy observations of titanium irradiated at 15 or 90 K by xenon, tantalum and lead ions. For sufficiently high electronic energy losses (> or approx.2.5 keV A-1), black dots aligned along the incident ion beam direction are observed. The ratio of the number of such alignments to that of impinging ions depends strongly on the irradiation conditions, namely the irradiation temperature and fluence. A tentative explanation of these observations is proposed. It involves the mechanism of point defect clustering resulting either from thermally activated migration or from athermal processes occurring in the wake of the incident ions. (orig.)

  20. ''Electron Conic'' Signatures observed in the nightside auroral zone and over the polar cap

    International Nuclear Information System (INIS)

    A preliminary search of the Dynamics Explorer 1 high-altitude plasma instrument data base has yielded examples of ''electron conic'' signatures. The three example passes show an association with regions of downward electron acceleration and upward ion beams, but this is not true of all the electron conic events. The electron conic signatures are clearly discernible on energy-flux-versus-time color spectrograms as pairs of discrete vertical bands which are symmetric about a pitch angle of approximately 1800. One of the examples is a polar cap pass with electron conic signatures observed at invariant latitudes from 840 to 750. The other two cases are nightside auroral zone passes in which the regions of detectable electron conics are spatially more confined, covering only about 10 in invariant latitude. The conic signatures have been found at energies that range from 50 eV0 is larger than expected for a loss cone feature. If the electrons conserve the first adiabatic invariant in a dipole magnetic field, and in some cases a parallel electric field, the mirroring altitude varies between about 500 km and 8000 km, which is above the atmospheric loss region. For this reason, and in analogy with the formation of ion conics, we suggest that the conic signatures are produced by heating of the electrons perpendicular to the magnetic field

  1. Subionospheric VLF Observations of Transmitter-Induced Precipitation of Inner Radiation Belt Electrons

    Science.gov (United States)

    Golkowski, M.; Inan, U.; Peter, W.

    2006-12-01

    Ionospheric effects of energetic electron precipitation induced by controlled injection of VLF signals from a ground based transmitter are observed via subionospheric VLF remote sensing. The 21.4 kHz NPM transmitter in Lualualei, Hawaii is keyed ON-OFF in a periodic sequence lasting 30 minutes. The same periodicity is observed in the amplitude and phase of the sub-ionospherically propagating signals of the 24.8 kHz NLK (Jim Creek, Washington) and 25.2 kHz NLM (LaMoure, North Dakota) transmitters measured at Midway Island. The NLM and NLK signal paths pass underneath the region of electron precipitation induced by the NPM transmitter, as predicted theoretically on the basis of cyclotron resonance interaction between energetic electrons and obliquely propagating whistler-mode waves injected by NPM. The ionospheric disturbances are consistent with that caused by conductivity enhancements resulting from secondary ionization produced by the precipitation of pitch angle scattered electrons in the 100-300 keV energy range. Periodic perturbations of the NLK signal observed at Palmer, Antarctica suggest that energetic electrons are scattered into both the bounce and drift loss cones. Utilizing a comprehensive model of magnetospheric wave-particle interaction, ionospheric energy deposition, and subionospheric VLF propagation, the precipitated energy flux is estimated to peak at L ~ 2 and ~ 3 x 10-4 [ergs s-1 cm-2

  2. Electron Microscopic Observation of Clays of Calcareous and Noncalcareous Soils in Bangladesh

    OpenAIRE

    ALAM, Md. Lutfe; KAKOI, Teruzane; MIYAUCHI, Nobufumi; SHINAGAWA, Akio; カコイ, テルザネ; ミヤウチ, ノブフミ; シナガワ, アキオ

    1993-01-01

    Electron microscopic observation of calcareous and noncalcareous floodplain soils of Bangladesh were carried out by TEM and SEM. Morphological changes in relation to clay formation and weathering process were investigated. Unweathered, partially weathered and weathered micaceous mineralsaccompanying with poorly crystallized kaolinite and halloysite and other primary minerals were observed in silt and coarse clay of both calcareous and noncalcareous soil. Smectite and vermiculite which aredomi...

  3. Electron Microscopic Observation of Clays of Calcareous and Noncalcareous Soils in Bangladesh

    OpenAIRE

    ALAM, Md. Lutfe; KAKOI, Teruzane; MIYAUCHI, Nobufumi; SHINAGAWA, Akio; カコイ, テルザネ; ミヤウチ, ノブフミ; シナガワ, アキオ

    1993-01-01

    Electron microscopic observation of calcareous and noncalcareous floodplain soils of Bangladesh were carried out by TEM and SEM. Morphological changes in relation to clay formation and weathering process were investigated. Unweathered, partially weathered and weathered micaceous minerals accompanying with poorly crystallized kaolinite and halloysite and other primary minerals were observed in silt and coarse clay of both calcareous and noncalcareous soil. Smectite and vermiculite which are...

  4. Simple observation of Streptococcus mutans biofilm by scanning electron microscopy using ionic liquids

    OpenAIRE

    Asahi, Yoko; Miura, Jiro; Tsuda, Tetsuya; Kuwabata, Susumu; Tsunashima, Katsuhiko; Noiri, Yuichiro; Sakata, Takao; Ebisu, Shigeyuki; Hayashi, Mikako

    2015-01-01

    Scanning electron microscopy (SEM) has been successfully used to image biofilms because of its high resolution and magnification. However, conventional SEM requires dehydration and metal coating of biological samples before observation, and because biofilms consist mainly of water, sample dehydration may influence the biofilm structure. When coated with an ionic liquid, which is a kind of salt that exists in the liquid state at room temperature, biological samples for SEM observation do not r...

  5. Pitch angle distributions of electrons at dipolarization sites during geomagnetic activity: THEMIS observations

    Science.gov (United States)

    Wang, Kaiti; Lin, Ching-Huei; Wang, Lu-Yin; Hada, Tohru; Nishimura, Yukitoshi; Turner, Drew L.; Angelopoulos, Vassilis

    2014-12-01

    Changes in pitch angle distributions of electrons with energies from a few eV to 1 MeV at dipolarization sites in Earth's magnetotail are investigated statistically to determine the extent to which adiabatic acceleration may contribute to these changes. Forty-two dipolarization events from 2008 and 2009 observed by Time History of Events and Macroscale Interactions during Substorms probes covering the inner plasma sheet from 8 RE to 12 RE during geomagnetic activity identified by the AL index are analyzed. The number of observed events with cigar-type distributions (peaks at 0° and 180°) decreases sharply below 1 keV after dipolarization because in many of these events, electron distributions became more isotropized. From above 1 keV to a few tens of keV, however, the observed number of cigar-type events increases after dipolarization and the number of isotropic events decreases. These changes can be related to the ineffectiveness of Fermi acceleration below 1 keV (at those energies, dipolarization time becomes comparable to electron bounce time). Model-calculated pitch angle distributions after dipolarization with the effect of betatron and Fermi acceleration tested indicate that these adiabatic acceleration mechanisms can explain the observed patterns of event number changes over a large range of energies for cigar events and isotropic events. Other factors still need to be considered to assess the observed increase in cigar events around 2 keV. Indeed, preferential directional increase/loss of electron fluxes, which may contribute to the formation of cigar events, was observed. Nonadiabatic processes to accelerate electrons in a parallel direction may also be important for future study.

  6. Observations of multiple order parameters in 5f electron systems; Observations de parametres d'ordre multiples dans les systemes d'electrons 5f

    Energy Technology Data Exchange (ETDEWEB)

    Blackburn, E

    2005-12-15

    In this thesis, multiple order parameters originating in the same electronic system are studied. The multi-k magnetic structures, where more than one propagation wavevector, k, is observed in the same volume, are considered as prototypical models. The effect of this structure on the elastic and inelastic response is studied. In cubic 3-k uranium rock-salts, unexpected elastic diffraction events were observed at positions in reciprocal space where the structure factor should have been zero. These diffraction peaks are identified with correlations between the (orthogonal) magnetic order parameters. The 3-k structure also affects the observed dynamics; the spin-wave fluctuations in uranium dioxide as observed by inelastic neutron polarization analysis can only be explained on the basis of a 3-k structure. In the antiferromagnetic superconductor UPd{sub 2}Al{sub 3} the magnetic order and the super-conducting state coexist, and are apparently generated by the same heavy fermions. The effect of an external magnetic field on both the normal and superconducting states is examined. In the normal state, the compound displays Fermi-liquid-like behaviour. The inelastic neutron response is strongly renormalized on entering the superconducting state, and high-precision measurements of the low-energy transfer part of this response confirm that the superconducting energy gap has the same symmetry as the antiferromagnetic lattice. (author)

  7. MESSENGER observations of transient bursts of energetic electrons in Mercury's magnetosphere.

    Science.gov (United States)

    Ho, George C; Krimigis, Stamatios M; Gold, Robert E; Baker, Daniel N; Slavin, James A; Anderson, Brian J; Korth, Haje; Starr, Richard D; Lawrence, David J; McNutt, Ralph L; Solomon, Sean C

    2011-09-30

    The MESSENGER spacecraft began detecting energetic electrons with energies greater than 30 kilo-electron volts (keV) shortly after its insertion into orbit about Mercury. In contrast, no energetic protons were observed. The energetic electrons arrive as bursts lasting from seconds to hours and are most intense close to the planet, distributed in latitude from the equator to the north pole, and present at most local times. Energies can exceed 200 keV but often exhibit cutoffs near 100 keV. Angular distributions of the electrons about the magnetic field suggest that they do not execute complete drift paths around the planet. This set of characteristics demonstrates that Mercury's weak magnetic field does not support Van Allen-type radiation belts, unlike all other planets in the solar system with internal magnetic fields. PMID:21960629

  8. Three-dimensional observation of TiO2 nanostructures by electron tomography

    KAUST Repository

    Suh, Young Joon

    2013-03-01

    Three-dimensional nanostructures of TiO2 related materials including nanotubes, electron acceptor materials in hybrid polymer solar cells, and working electrodes of dye sensitized solar cells (DSSCs) were visualized by electron tomography as well as TEM micrographs. The regions on the wall of TiO2 nanotubes where the streptavidins were attached were elucidated by electron tomogram analysis. The coverage of TiO2 nanotubes by streptavidin was also investigated. The TiO2 nanostructures in hybrid polymer solar cells made by sol-gel and atomic layer deposition (ALD) methods and the morphologies of pores between TiO2 particles in DSSCs were also observed by reconstructed three-dimensional images made by electron tomography. © 2012 Elsevier Ltd.

  9. Observation of runaway electron beams by visible color camera in the Experimental Advanced Superconducting Tokamak

    International Nuclear Information System (INIS)

    The synchrotron radiation originated from the energetic runaway electrons has been measured by a visible complementary metal oxide semiconductor camera working in the wavelength ranges of 380-750 nm in the Experimental Advanced Superconducting Tokamak [H. Q. Liu et al., Plasma Phys. Contr. Fusion 49, 995 (2007)]. With a tangential viewing into the plasma in the direction of electron approach on the equatorial plane, the synchrotron radiation from the energetic runaway electrons was measured in full poloidal cross section. The synchrotron radiation diagnostics provides a direct pattern of the runaway beam inside the plasma. The energy and pitch angle of runaway electrons have been obtained according to the synchrotron radiation pattern. A stable shell shape of synchrotron radiation has been observed in a few runaway discharges.

  10. Observations of rotation in JET plasmas with electron heating by ion cyclotron resonance heating

    DEFF Research Database (Denmark)

    Hellsten, T.; Johnson, T. J.; Van Eester, D.;

    2012-01-01

    constant angular rotation. The core rotation is stronger in magnitude than observed for scenarios with dominating ion cyclotron absorption. Two scenarios are considered: the inverted mode conversion scenarios and heating at the second harmonic He-3 cyclotron resonance in H plasmas. In the latter case......The rotation of L-mode plasmas in the JET tokamak heated by waves in the ion cyclotron range of frequencies (ICRF) damped on electrons, is reported. The plasma in the core is found to rotate in the counter-current direction with a high shear and in the outer part of the plasma with an almost......, electron absorption of the fast magnetosonic wave by transit time magnetic pumping and electron Landau damping (TTMP/ELD) is the dominating absorption mechanism. Inverted mode conversion is done in (He-3)-H plasmas where the mode converted waves are essentially absorbed by electron Landau damping. Similar...

  11. Dynamic Low-Vacuum Scanning Electron Microscope Freeze Drying Observation for Fresh Water Algae

    International Nuclear Information System (INIS)

    A new perpetration method for serving in dynamic examinations of the fresh water algae is developed in connection with the Low-Vacuum Scanning Electron Microscope (LV-SEM) freeze drying technique. Specimens are collected from fresh water of Ismailia channel then transferred directly to freeze by liquid nitrogen and dried in the chamber of the scanning electron microscope in the low vacuum mode. Scanning electron micrographs revealed that the drying method presented the microstructure of algae. Dehydration in a graded ethanol series is not necessary in the new method. Dried algae specimen is observed in SEM high vacuum mode after conductive coating at higher resolution. Low-vacuum SEM freeze drying technique is a simple, time-saving and reproducible method for scanning electron microscopy that is applicable to various aquatic microorganisms covered with soft tissues.

  12. Observations of visual sensations produced by Cerenkov radiation from high-energy electrons

    International Nuclear Information System (INIS)

    Ten cancer patients whose eyes were therapeutically irradiated with 6-18 MeV electrons reported visual light sensations. Nine reported seeing blue light and one reported seeing white light. Controls reported seeing no light. Additionally, tests with patients ruled out the x-ray contamination of the electron beam as being important. The photon yield due to Cerenkov radiation produced by radium and its daughters for both electrons and gamma rays was calculated; it was found to account for a turn-of-the-century human observation of the radium phosphene. We conclude that the dominant mechanism of this phosphene is Cerenkov radiation, primarily from betas. From our own patient data, based on the color seen and the Cerenkov production rates, we conclude that the dominant mechanism is Cerenkov radiation and that high-energy electrons are an example of particle induced visual sensations

  13. Observation at the planet Mercury by the plasma electron experiment: Mariner Mariner 10

    International Nuclear Information System (INIS)

    Plasma electron observations made on board Mariner 10 during its three encounters with the planet Mercury show that the planet interacts with the solar wind to form a bow shock and a permanent magnetosphere. The observations provide a determination of the dimensions and properties of the magnetosphere, independently of and in general agreement with magnetometer observations. The magnetosphere of Mercury appears to be similar in shape to that of the earth but much smaller in relation to the size of the planet. The average distance from the center of Mercury to the subsolar point of the magnetopause is approx.1.4 planetary radii. Electron populations similar to those found in the earth's magneto-tail, within the plasma sheet and adjacent regions, were observed at Mercury; both their spatial location and the electron energy spectra within them bear qualitative and quantitative resemblance to corresponding observations at the earth. In general, the magnetosphere of Mercury resembles to a marked degree a reduced version of that of the earth, there being no significant differences of structure revealed by the Mariner 10 observations. Quantities in the two magnetospheres are related by simple scaling laws. The size of Mercury relative to its magnetosphere precludes, however, the existence of stably trapped particle belts and of inner magnetosphere (Lapproximately-less-than8 at the earth) phenomena generally

  14. Observation of strong reflection of electron waves exiting a ballistic channel at low energy

    Science.gov (United States)

    Vaz, Canute I.; Liu, Changze; Campbell, Jason P.; Ryan, Jason T.; Southwick, Richard G., III; Gundlach, David; Oates, Anthony S.; Huang, Ru; Cheung, Kin. P.

    2016-06-01

    Wave scattering by a potential step is a ubiquitous concept. Thus, it is surprising that theoretical treatments of ballistic transport in nanoscale devices, from quantum point contacts to ballistic transistors, assume no reflection even when the potential step is encountered upon exiting the device. Experiments so far seem to support this even if it is not clear why. Here we report clear evidence of coherent reflection when electron wave exits the channel of a nanoscale transistor and when the electron energy is low. The observed behavior is well described by a simple rectangular potential barrier model which the Schrodinger's equation can be solved exactly. We can explain why reflection is not observed in most situations but cannot be ignored in some important situations. Our experiment also represents a direct measurement of electron injection velocity - a critical quantity in nanoscale transistors that is widely considered not measurable.

  15. The HERA polarimeter and the first observation of electron spin polarization at HERA

    International Nuclear Information System (INIS)

    Electron spin polarizations of about 8% were observed at HERA in November 1991. In runs during 1992 utilizing special orbit corrections, polarization values close to 60% have been achieved. In this paper the polarimeter, the machine conditions, the data analysis, the first results and plans for future measurements are described. (orig.)

  16. Observation of electron multiplication in liquid xenon with a microstrip plate

    International Nuclear Information System (INIS)

    We report here on the observation of electron multiplication in liquid xenon in a microstrip chamber with an amplification factor of the order of 10. The measurements were carried out at a temperature between 208 and 215 K (liquid density of about 2.7 g/cm3). (orig.)

  17. Modification of Skin Surface Biopsy for Scanning Electron Microscopic Observation of Superficial Fungal Infection

    OpenAIRE

    高垣, 謙二; 山田, 義貴; 川崎, 洋司; 大畑, 力; 地土井, 襄爾

    1984-01-01

    A modified skin surface biopsy for scanning electron microscopic observation of superficial fungal infection was introduced. Our method has the following advantages which are adequate for routine ultrastructural investigation on superficial fungal infections : 1) atraumatic, 2) convenient, 3) able to obtain a wide area, and 4) minimal chance of getting artifacts.

  18. Direct observation of surface reconstruction and termination on a complex metal oxide catalyst by electron microscopy

    KAUST Repository

    Zhu, Yihan

    2012-03-19

    On the surface: The surface reconstruction of an MoVTeO complex metal oxide catalyst was observed directly by various electron microscopic techniques and the results explain the puzzling catalytic behavior. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Observation results of relativistic electrons detected by Fengyun-1 satellite and analysis of relativistic electron enhancement (REE) events

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The space particle component detector on Fengyun-1 satellite which works at the sun-synchronous orbit of about 870 km altitude has detected relativistic electrons for a long time. In comparison with the SAMPEX satellite observations during 1999 -2004, the relativistic electron data from Fengyun-1 satellite from June 1999 to 2005 are used to analyze the relativistic electron enhancement (REE) events at the low earth orbit, and the possible correlation among REE events at the low earth orbit, high-speed solar wind and geomagnetic storms is discussed. The statistical result presents that 45 REE events are found in total during this time period, and the strong REE events with the maximum daily average flux > 400 cm?2·sr?1·s?1 occur mostly during the transition period from solar maximum to solar minimum. Among these 45 REE events, four strong REE events last a longer time period from 26- to 51-day and correlate closely with high speed solar wind and strong geo- magnetic storms. Meanwhile, several strong geomagnetic storms occur continu- ously before these REE events, and these continuous geomagnetic storms would be an important factor causing these long-lasting strong REE events. The correlation analysis for overall 45 events indicates that the strength of the REE events corre- lates with the solar wind speed and the strength of the geomagnetic storm, and the correlation for strong REE events is much stronger than that for weak REE events.

  20. Observation of Fast-Electron-Driven Alfevenic Modes in the HSX Stellarator

    International Nuclear Information System (INIS)

    In the helically-symmetric experiment (HSX) stellarator device, the plasma is both produced and heated by use of electron cyclotron resonance heating (ECRH) at the 2''nd harmonic X-mode resonance. This heating configuration generates a nonthermal energetic electron population. The HSX device is the first of a new generation of stellarators that exploit the concept of quasi-symmetric magnetic fields. Herein, we report on the first experimental evidence of fast-electron-driven Global Alfven Eigenmode (GAE). This mode has previously been observed in both tokamaks and stellarators but it was always driven by energetic ions, not electrons. This instability is observed for quasi-helically symmetric HSX plasmas. Measurements presented in this paper provide two new results; (1) fast electrons can drive the GAE instability, and (2) quasi-symmetry makes a difference by better confining the particles that drive the instability as compared to the conventional stellarator configuration. We report on several features of this fluctuation. It is a coherent, m=1 mode that exhibits both electromagnetic and electrostatic components that are directly measured in the plasma core and edge. Magnetic field fluctuations are measured using external Mirnov coils while interferometry and langmuir probes diagnostics are employed to measure perturbations in the plasma electron density and potential. Fluctuations are observed in the frequency range of 20-120 kHz and scale with ion density and mass according to expectations for Alfvenic modes. The mode is observed to be global and is present in quasi helically symmetric HSX plasma. When quasi-helical symmetry is broken, fast electron confinement deteriorates and the mode is no longer observed. Theory predicts a GAE mode in the gap below the Alfven continua can be excited in the frequency range of the measured fluctuations. By employing a biased electrode inserted into the plasma, flows can be generated. Under these conditions, the Alfvenic mode

  1. Poker Flat Incoherent Scatter Radar observations of anomalous electron heating in the E region

    Science.gov (United States)

    Makarevich, R. A.; Koustov, A. V.; Nicolls, M. J.

    2013-07-01

    A comprehensive 2-year dataset collected with the Poker Flat Incoherent Scatter Radar (PFISR) located near Fairbanks, Alaska (MLAT = 65.4° N) is employed to identify and analyse 22 events of anomalous electron heating (AEH) in the auroral E region. The overall AEH occurrence probability is conservatively estimated to be 0.3% from nearly-continuous observations of the E region by PFISR, although it increases to 0.7-0.9% in the dawn and dusk sectors where all AEH events were observed. The AEH occurrence variation with MLT is broadly consistent with those of events with high convection velocity (>1000 m s-1) or electron temperature (> 800 K), except for much smaller AEH probability and absence of AEH events near magnetic midnight. This suggests that high convection electric field by itself is necessary but not sufficient for measurable electron heating by two-stream plasma waves. The multi-point observations are utilised to investigate the fundamental dependence of the electron temperature on the convection electric field, focusing on the previously-proposed saturation effects at extreme electric fields. The AEH dataset was found to exhibit considerable scatter and, on average, similar rate of the electron temperature increase with the electric field up to 100 mV m-1 as compared with previous studies. At higher (highest) electric fields, the electron temperatures are below the linear trend on average (within uncertainty). By employing a simple fluid model of AEH, it is demonstrated that some of this deviation from the linear trend may be due to a stronger vibrational cooling at very large temperatures and electric fields.

  2. Photoelectron spectroscopy of hexachloroplatinate-nucleobase complexes: Nucleobase excited state decay observed via delayed electron emission

    International Nuclear Information System (INIS)

    We report low-temperature photoelectron spectra of isolated gas-phase complexes of the hexachloroplatinate dianion bound to the nucleobases uracil, thymine, cytosine, and adenine. The spectra display well-resolved, distinct peaks that are consistent with complexes where the hexachloroplatinate dianion is largely intact. Adiabatic electron detachment energies for the hexachloroplatinate-nucleobase complexes are measured as 2.26-2.36 eV. The magnitudes of the repulsive Coulomb barriers (RCBs) of the complexes are all ∼1.7 eV, values that are lower than the RCB of the uncomplexed PtCl62− dianion as a result of charge solvation by the nucleobases. In addition to the resolved spectral features, broad featureless bands indicative of delayed electron detachment are observed in the 193 nm photoelectron spectra of the four clusters. The 266 nm spectra of the PtCl62− ⋅ thymine and PtCl62− ⋅ adenine complexes also display very prominent delayed electron emission bands. These results mirror recent results on the related Pt(CN)42− ⋅ nucleobase complexes [A. Sen et al., J. Phys. Chem. B 119, 11626 (2015)]. The observation of delayed electron emission bands in the PtCl62− ⋅ nucleobase spectra obtained in this work, as for the previously studied Pt(CN)42− ⋅ nucleobase complexes, is attributed to one-photon excitation of nucleobase-centred excited states that can effectively couple to the electron detachment continuum, producing strong electron detachment. Moreover, the selective, strong excitation of the delayed emission bands in the 266 nm spectra is linked to fundamental differences in the individual nucleobase photophysics at this excitation energy. This strongly supports our previous suggestion that the dianion within these clusters can be viewed as a “dynamic tag” which has the propensity to emit electrons when the attached nucleobase decays over a time scale long enough to allow autodetachment

  3. Photoelectron Spectroscopy of Hexachloroplatinate-Nucleobase Complexes: Nucleobase Excited State Decay Observed via Delayed Electron Emission

    Energy Technology Data Exchange (ETDEWEB)

    Sen, Ananya; Matthews, Edward M.; Hou, Gao-Lei; Wang, Xue B.; Dessent, Caroline

    2015-11-14

    We report low-temperature photoelectron spectra of isolated gas-phase complexes of the hexachloroplatinate dianion bound to the nucleobases uracil, thymine, cytosine and adenine. The spectra display well-resolved, distinct peaks that are consistent with complexes where the hexachloroplatinate dianion is largely intact. Adiabatic electron detachment energies for the hexachloroplatinate-nucleobase complexes are measured as 2.26-2.36 eV. The magnitudes of the repulsive Coulomb barriers (RCBs) of the complexes are all ~1.7 eV, values that are lower than the RCB of the uncomplexed PtCl6 2- dianion as a result of charge solvation by the nucleobases. In addition to the resolved spectral features, broad featureless bands indicative of delayed electron detachment are observed in the 193 nm photoelectron spectra of the four clusters. The 266 nm spectra of the PtCl6 2-∙thymine and PtCl6 2-∙adenine complexes also display very prominent delayed electron emission bands. These results mirror recent results on the related Pt(CN)4 2-∙nucleobase complexes [Sen et al, J. Phys. Chem. B, 119, 11626, 2015]. The observation of delayed electron emission bands in the PtCl6 2-∙nucleobase spectra obtained in this work, as for the previously studied Pt(CN)4 2-∙nucleobase complexes, is attributed to onephoton excitation of nucleobase-centred excited states that can effectively couple to the electron detachment continuum, producing strong electron detachment. Moreover, the selective, strong excitation of the delayed emission bands in the 266 nm spectra is linked to fundamental differences in the individual nucleobase photophysics at this excitation energy. This strongly supports our previous suggestion that the dianion within these clusters can be viewed as a “dynamic tag” which has the propensity to emit electrons when the attached nucleobase decays over a timescale long enough to allow autodetachment.

  4. Communication: Coherences observed in vivo in photosynthetic bacteria using two-dimensional electronic spectroscopy

    Science.gov (United States)

    Dahlberg, Peter D.; Norris, Graham J.; Wang, Cheng; Viswanathan, Subha; Singh, Ved P.; Engel, Gregory S.

    2015-09-01

    Energy transfer through large disordered antenna networks in photosynthetic organisms can occur with a quantum efficiency of nearly 100%. This energy transfer is facilitated by the electronic structure of the photosynthetic antennae as well as interactions between electronic states and the surrounding environment. Coherences in time-domain spectroscopy provide a fine probe of how a system interacts with its surroundings. In two-dimensional electronic spectroscopy, coherences can appear on both the ground and excited state surfaces revealing detailed information regarding electronic structure, system-bath coupling, energy transfer, and energetic coupling in complex chemical systems. Numerous studies have revealed coherences in isolated photosynthetic pigment-protein complexes, but these coherences have not been observed in vivo due to the small amplitude of these signals and the intense scatter from whole cells. Here, we present data acquired using ultrafast video-acquisition gradient-assisted photon echo spectroscopy to observe quantum beating signals from coherences in vivo. Experiments were conducted on isolated light harvesting complex II (LH2) from Rhodobacter sphaeroides, whole cells of R. sphaeroides, and whole cells of R. sphaeroides grown in 30% deuterated media. A vibronic coherence was observed following laser excitation at ambient temperature between the B850 and the B850∗ states of LH2 in each of the 3 samples with a lifetime of ˜40-60 fs.

  5. Communication: Coherences observed in vivo in photosynthetic bacteria using two-dimensional electronic spectroscopy

    International Nuclear Information System (INIS)

    Energy transfer through large disordered antenna networks in photosynthetic organisms can occur with a quantum efficiency of nearly 100%. This energy transfer is facilitated by the electronic structure of the photosynthetic antennae as well as interactions between electronic states and the surrounding environment. Coherences in time-domain spectroscopy provide a fine probe of how a system interacts with its surroundings. In two-dimensional electronic spectroscopy, coherences can appear on both the ground and excited state surfaces revealing detailed information regarding electronic structure, system-bath coupling, energy transfer, and energetic coupling in complex chemical systems. Numerous studies have revealed coherences in isolated photosynthetic pigment-protein complexes, but these coherences have not been observed in vivo due to the small amplitude of these signals and the intense scatter from whole cells. Here, we present data acquired using ultrafast video-acquisition gradient-assisted photon echo spectroscopy to observe quantum beating signals from coherences in vivo. Experiments were conducted on isolated light harvesting complex II (LH2) from Rhodobacter sphaeroides, whole cells of R. sphaeroides, and whole cells of R. sphaeroides grown in 30% deuterated media. A vibronic coherence was observed following laser excitation at ambient temperature between the B850 and the B850∗ states of LH2 in each of the 3 samples with a lifetime of ∼40-60 fs

  6. Communication: Coherences observed in vivo in photosynthetic bacteria using two-dimensional electronic spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Dahlberg, Peter D. [Graduate Program in the Biophysical Sciences, Institute for Biophysical Dynamics, and The James Franck Institute, The University of Chicago, Chicago, Illinois 60637 (United States); Norris, Graham J.; Wang, Cheng; Viswanathan, Subha; Singh, Ved P.; Engel, Gregory S., E-mail: gsengel@uchicago.edu [Department of Chemistry, Institute for Biophysical Dynamics, and The James Franck Institute, The University of Chicago, Chicago, Illinois 60637 (United States)

    2015-09-14

    Energy transfer through large disordered antenna networks in photosynthetic organisms can occur with a quantum efficiency of nearly 100%. This energy transfer is facilitated by the electronic structure of the photosynthetic antennae as well as interactions between electronic states and the surrounding environment. Coherences in time-domain spectroscopy provide a fine probe of how a system interacts with its surroundings. In two-dimensional electronic spectroscopy, coherences can appear on both the ground and excited state surfaces revealing detailed information regarding electronic structure, system-bath coupling, energy transfer, and energetic coupling in complex chemical systems. Numerous studies have revealed coherences in isolated photosynthetic pigment-protein complexes, but these coherences have not been observed in vivo due to the small amplitude of these signals and the intense scatter from whole cells. Here, we present data acquired using ultrafast video-acquisition gradient-assisted photon echo spectroscopy to observe quantum beating signals from coherences in vivo. Experiments were conducted on isolated light harvesting complex II (LH2) from Rhodobacter sphaeroides, whole cells of R. sphaeroides, and whole cells of R. sphaeroides grown in 30% deuterated media. A vibronic coherence was observed following laser excitation at ambient temperature between the B850 and the B850{sup ∗} states of LH2 in each of the 3 samples with a lifetime of ∼40-60 fs.

  7. METHOD FOR OBSERVATION OF DEEMBEDDED SECTIONS OF FISH GONAD BY SCANNING ELECTRON MICROSCOPY

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This article reports a method for examining the intracellular structure of fish gonads using a scanning electron microscope(SEM). The specimen preparation procedure is similar to that for transmission electron microscopy wherein samples cut into semi-thin sections are fixed and embedded in plastic. The embedment matrix was removed by solvents. Risen-free specimens could be observed by SEM. The morphology of matured sperms in the gonad was very clear, and the oocyte internal structures appeared in three-dimensional images. Spheroidal nucleoli and yolk vesicles and several bundles of filaments adhered on the nucleoli could be viewed by SEM for the first time.

  8. Observation of topologically isolated energetic electrons in e+e- interactions

    International Nuclear Information System (INIS)

    In e+e- interactions at 34 GeV center of mass energy, using an integrated luminosity of 7.4 pb-1, 18 events are observed where an electron (positron) appears with an energy above 4 GeV, at large angle with respect to the beam direction, and well separated from other emerging charged and neutral particles. The characteristics of these events are found to be in agreement with the event characteristics expected from deep inelastic electron-photon scattering and inelastic Compton scattering, together with at most a small contribution from multihadron annihilation. (orig.)

  9. Observer based temperature control for reduced thermal cycling in power electronic cooling

    International Nuclear Information System (INIS)

    This paper presents an advanced dynamic cooling strategy for multi-layer structured power electronic modules. A observer based feedback controller is proposed to reduce a power device or module's thermal cycle amplitude during operation, with the aim of improving reliability and lifetime. The full-state observer design is based on a developed Cauer type thermal model. The observer enables estimation and control of the temperature at reliability critical locations only measuring one accessible location. This makes the method particularly powerful and suitable for application in power systems. The designed strategy is confirmed experimentally. Although the experiment is developed for a specific application scenario, the proposed strategy is of general validity. - Highlights: •An observer based temperature control strategy is proposed. •This strategy aims at improving power module's reliability and lifetime. •Reduce temperature change under various power dissipations and ambient temperatures. •The observer can estimate temperature without direct sensing

  10. First Observation of Electron Transfer Mediated Decay in Aqueous Solutions: A Novel Probe of Ion Pairing

    CERN Document Server

    Unger, I; Thürmer, S; Aziz, E F; Cederbaum, L S; Muchová, E; Slavíček, P; Winter, B; Kryzhevoi, N V

    2016-01-01

    A major goal of many spectroscopic techniques is to provide comprehensive information on the local chemical environment. Electron transfer mediated decay (ETMD) is a sensitive probe of the environment since it is actively involved in this non-local radiationless decay process through electron and energy transfer steps. We report the first experimental observation of ETMD in the liquid phase. Using liquid-jet X-ray photoelectron spectroscopy we explore LiCl aqueous solution, and detect low-energy electrons unambiguously emerging from the ETMD processes of core-ionized Li+. We interpret the experimental results with molecular dynamics and high-level ab initio calculations. By considering various solvation-structure models we show that both water molecules and Cl- anions can participate in ETMD, with each process having its characteristic spectral fingerprint. Different ion associations lead to different spectral shapes. The potential application of the unique sensitivity of the ETMD spectroscopy to the local hy...

  11. Electron channelling contrast observations in deformed Mg alloys prepared with ion milling

    International Nuclear Information System (INIS)

    Electron channelling contrast imaging (ECCI) was used in the cold-field emission scanning electron microscope (CFE-SEM) to image the microstructure on deformed bulk specimen. Imaging was conducted with a pole-piece mounted silicon photodiode detector at 5 keV to collect backscattered electrons generated from a low-tilted (0 – 3 degrees) specimen. Broad ion beam milling surface preparation technique was used to remove surface layers and reveal near-surface deformation features. The uniaxial hot-compression tests were conducted on Mg-0.3 wt% Al-0.2 wt% Ca alloy. ECCI observations on deformed bulk specimen showed irregular and complex channelling contrast variations inside parent grains and low angle grain boundaries originated from parent grain boundaries. ECCI on an ion milled prepared surface provides non-destructive and rapid visualisation and characterisation of strain fields along with near-surface deformation substructures in CFE-SEM

  12. Atomistic observations and analyses of lattice defects in transmission electron microscopes

    CERN Document Server

    Abe, H

    2003-01-01

    The transmission electron microscope (TEM) -accelerators was developed. TEM-Accelerator made possible to observe in situ experiments of ion irradiation and implantation. The main results are the experimental proof of new lattice defects by irradiation, the formation process and synthesized conditions of carbon onion by ion implantation, the microstructure and phase transformation conditions of graphite by ion irradiated phase transformation, the irradiation damage formation process by simultaneous irradiation of electron and ion and behavior of fullerene whisker under irradiation. The microstructural evolution of defect clusters in copper irradiated with 240-keV Cu sup + ions and a high resolution electron micrograph of carbon onions synthesized by ion implantation are explained as the examples of recent researches. (S.Y.)

  13. Observation of pulsed x-ray trains produced by laser-electron Compton scatterings

    International Nuclear Information System (INIS)

    X-ray generation based on laser-electron Compton scattering is one attractive method to achieve a compact laboratory-sized high-brightness x-ray source. We have designed, built, and tested such a source; it combines a 50 MeV multibunch electron linac with a mode-locked 1064 nm laser stored and amplified in a Fabry-Perot optical cavity. We directly observed trains of pulsed x rays using a microchannel plate detector; the resultant yield was found to be 1.2x105 Hz in good agreement with prediction. We believe that the result has demonstrated good feasibility of linac-based compact x-ray sources via laser-electron Compton scatterings.

  14. Observation of vacuum-enhanced electron spin resonance of levitated nanodiamonds

    CERN Document Server

    Hoang, Thai M; Bang, Jaehoon; Li, Tongcang

    2015-01-01

    Electron spins of diamond nitrogen-vacancy (NV) centers are important quantum resources for nanoscale sensing and quantum information. Combining such NV spin systems with levitated optomechanical resonators will provide a hybrid quantum system for many novel applications. Here we optically levitate a nanodiamond and demonstrate electron spin control of its built-in NV centers in low vacuum. We observe that the strength of electron spin resonance (ESR) is enhanced when the air pressure is reduced. To better understand this novel system, we also investigate the effects of trap power and measure the absolute internal temperature of levitated nanodiamonds with ESR after calibration of the strain effect. Our results show that optical levitation of nanodiamonds in vacuum not only can improve the mechanical quality of its oscillation, but also enhance the ESR contrast, which pave the way towards a novel levitated spin-optomechanical system for studying macroscopic quantum mechanics. The results also indicate potenti...

  15. CLUSTER observations of electron outflowing beams carrying downward currents above the polar cap by northward IMF

    Directory of Open Access Journals (Sweden)

    A. Teste

    2007-05-01

    Full Text Available Above the polar cap, at about 5–9 Earth radii (RE altitude, the PEACE experiment onboard CLUSTER detected, for the first time, electron beams outflowing from the ionosphere with large and variable energy fluxes, well collimated along the magnetic field lines. All these events occurred during periods of northward or weak interplanetary magnetic field (IMF.

    These outflowing beams were generally detected below 100 eV and typically between 40 and 70 eV, just above the photoelectron level. Their energy gain can be explained by the presence of a field-aligned potential drop below the spacecraft, as in the auroral zone. The careful analysis of the beams distribution function indicates that they were not only accelerated but also heated. The parallel heating is estimated to about 2 to 20 eV and it globally tends to increase with the acceleration energy. Moreover, WHISPER observed broadband electrostatic emissions around a few kHz correlated with the outflowing electron beams, which suggests beam-plasma interactions capable of triggering plasma instabilities.

    In presence of simultaneous very weak ion fluxes, the outflowing electron beams are the main carriers of downward field-aligned currents estimated to about 10 nA/m2. These electron beams are actually not isolated but surrounded by wider structures of ion outflows. All along its polar cap crossings, Cluster observed successive electron and ion outflows. This implies that the polar ionosphere represents a significant source of cold plasma for the magnetosphere during northward or weak IMF conditions. The successive ion and electron outflows finally result in a filamented current system of opposite polarities which connects the polar ionosphere to distant regions of the magnetosphere.

  16. Whistler mode waves and the electron heat flux in the solar wind: cluster observations

    International Nuclear Information System (INIS)

    The nature of the magnetic field fluctuations in the solar wind between the ion and electron scales is still under debate. Using the Cluster/STAFF instrument, we make a survey of the power spectral density and of the polarization of these fluctuations at frequencies f in [1, 400] Hz, during five years (2001-2005), when Cluster was in the free solar wind. In ∼10% of the selected data, we observe narrowband, right-handed, circularly polarized fluctuations, with wave vectors quasi-parallel to the mean magnetic field, superimposed on the spectrum of the permanent background turbulence. We interpret these coherent fluctuations as whistler mode waves. The lifetime of these waves varies between a few seconds and several hours. Here, we present, for the first time, an analysis of long-lived whistler waves, i.e., lasting more than five minutes. We find several necessary (but not sufficient) conditions for the observation of whistler waves, mainly a low level of background turbulence, a slow wind, a relatively large electron heat flux, and a low electron collision frequency. When the electron parallel beta factor β e∥ is larger than 3, the whistler waves are seen along the heat flux threshold of the whistler heat flux instability. The presence of such whistler waves confirms that the whistler heat flux instability contributes to the regulation of the solar wind heat flux, at least for β e∥ ≥ 3, in slow wind at 1 AU.

  17. Observation of O+ (4P-4D0 lines in electron aurora over Svalbard

    Directory of Open Access Journals (Sweden)

    K. Throp

    2004-09-01

    Full Text Available This work reports on observations of O+ lines in aurora over Svalbard, Norway. The Spectrographic Imaging Facility measures auroral spectra in three wavelength intervals (Hβ, N+2 1N(0,2 and N+2 1N(1,3. The oxygen ion multiplet (4639-4696Å is blended with the band. It is found that in electron aurora, the brightness of this multiplet, is on average, about 0.1 of the total brightness. A joint optical and incoherent scatter radar study of an electron aurora event shows that the ratio is enhanced when the ionisation in the upper E-layer (140-190km is significant with respect to the E-layer peak below 130km. Rayed arcs were observed on one such occasion, whereas on other occasions the auroral intensity was below the threshold of the imager. A one-dimensional electron transport model is used to estimate the cross section for production of the multiplet in electron collisions, yielding 0.18x10-18cm2.

  18. Observation of MWCNTs with low-energy electron point source microscope

    Institute of Scientific and Technical Information of China (English)

    Yu Jie; Bai Xin; Zhang Zhao-Xiang; Zhang Geng-Min; Guo Deng-Zhu; Xue Zeng-Quan

    2006-01-01

    The low-energy electron point source (LEEPS) microscope, which creates enlarged projection images with lowenergy field emission electron beams, can be used to observe the projection image of nano-scale samples and to characterize the coherence of the field emission beam. In this paper we report the design and test operation performance of a home-made LEEPS microscope. Multi-walled carbon nanotubes (MWCNTs) synthesized by the CVD method were observed by LEEPS microscope using a conventional tungsten tip, and projection images with the magnification of up to 104 was obtained. The resolution of the acquired images is ~10 nm. A higher resolution and a larger magnification can be expected when the AC magnetic field inside the equipment is shielded and the vibration of the instrument reduced.

  19. Three-Dimensional Microstructure of a Polymer-Dispersed Liquid Crystal Observed by Transmission Electron Microscopy

    Science.gov (United States)

    Pierron, Jean; Tournier-Lasserve, Valérie; Sopena, Pierre; Boudet, Alain; Sixou, Pierre; Mitov, Michel

    1995-11-01

    A film consisting of an amorphous photo-crosslinkable polymer matrix and a dispersion of microinclusions of a cholesteric polymer was investigated by transmission electron microscopy (TEM). The polymerization procedure of the blend provides a composite with many small nodules of spherical or ellipsoidal shapes, with sizes between 0.4 and 6 μm. The cholesteric stratification is well evidenced in transmission electron microscopy by dark lines due to diffraction contrast. The 3D organization was reconstructed by the observation of successive ultramicrotomed sections. Six types of nodules were distinguished according to the number of defects (foci or disclination lines), among which only three had already been observed and theoretically calculated. The confined geometry inherent in the size of the nodules, close to the cholesteric pitch, is responsible of these unexpected structures. In these conditions, the surface forces are in tight competition with the cholesteric elastic forces.

  20. Direct observation of spatio-temporal dynamics of short electron bunches in storage rings

    CERN Document Server

    Evain, C; Parquier, M Le; Szwaj, C; Tordeux, M -A; Manceron, L; Brubach, J -B; Roy, P; Bielawski, S

    2016-01-01

    In recent synchrotron radiation facilities, the use of short (picosecond) electron bunches is a powerful method for producing giant pulses of Terahertz Coherent Synchrotron Radiation (THz CSR). Here we report on the first direct observation of these pulse shapes with a few picoseconds resolution, and of their dynamics over a long time. We thus confirm in a very direct way the theories predicting an interplay between two physical processes. Below a critical bunch charge, we observe a train of identical THz pulses (a broadband Terahertz comb) stemming from the shortness of the electron bunches. Above this threshold, a large part of the emission is dominated by drifting structures, which appear through spontaneous self-organization. These challenging single-shot THz recordings are made possible by using a recently developed photonic time stretch detector with a high sensitivity. The experiment has been realized at the SOLEIL storage ring.

  1. Improvement of the accuracy of phase observation by modification of phase-shifting electron holography

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Takahiro; Aizawa, Shinji; Tanigaki, Toshiaki [Advanced Science Institute, RIKEN, Hirosawa 2-1, Wako, Saitama 351-0198 (Japan); Ota, Keishin, E-mail: ota@microphase.co.jp [Microphase Co., Ltd., Onigakubo 1147-9, Tsukuba, Ibaragi 300-2651 (Japan); Matsuda, Tsuyoshi [Japan Science and Technology Agency, Kawaguchi-shi, Saitama 332-0012 (Japan); Tonomura, Akira [Advanced Science Institute, RIKEN, Hirosawa 2-1, Wako, Saitama 351-0198 (Japan); Okinawa Institute of Science and Technology, Graduate University, Kunigami, Okinawa 904-0495 (Japan); Central Research Laboratory, Hitachi, Ltd., Hatoyama, Saitama 350-0395 (Japan)

    2012-07-15

    We found that the accuracy of the phase observation in phase-shifting electron holography is strongly restricted by time variations of mean intensity and contrast of the holograms. A modified method was developed for correcting these variations. Experimental results demonstrated that the modification enabled us to acquire a large number of holograms, and as a result, the accuracy of the phase observation has been improved by a factor of 5. -- Highlights: Black-Right-Pointing-Pointer A modified phase-shifting electron holography was proposed. Black-Right-Pointing-Pointer The time variation of mean intensity and contrast of holograms were corrected. Black-Right-Pointing-Pointer These corrections lead to a great improvement of the resultant phase accuracy. Black-Right-Pointing-Pointer A phase accuracy of about 1/4000 rad was achieved from experimental results.

  2. Determining the spectra of radiation belt electron losses: Fitting DEMETER electron flux observations for typical and storm times

    Science.gov (United States)

    Whittaker, Ian C.; Gamble, Rory J.; Rodger, Craig J.; Clilverd, Mark A.; Sauvaud, Jean-André

    2013-12-01

    The energy spectra of energetic electron precipitation from the radiation belts are studied in order to improve our understanding of the influence of radiation belt processes. The Detection of Electromagnetic Emissions Transmitted from Earthquake Regions (DEMETER) microsatellite electron flux instrument is comparatively unusual in that it has very high energy resolution (128 channels with 17.9 keV widths in normal survey mode), which lends itself to this type of spectral analysis. Here electron spectra from DEMETER have been analyzed from all six years of its operation, and three fit types (power law, exponential, and kappa-type) have been applied to the precipitating flux observations. We show that the power law fit consistently provides the best representation of the flux and that the kappa-type is rarely valid. We also provide estimated uncertainties in the flux for this instrument as a function of energy. Average power law gradients for nontrapped particles have been determined for geomagnetically nondisturbed periods to get a typical global behavior of the spectra in the inner radiation belt, slot region, and outer radiation belt. Power law spectral gradients in the outer belt are typically -2.5 during quiet periods, changing to a softer spectrum of ˜-3.5 during geomagnetic storms. The inner belt does the opposite, hardening from -4 during quiet times to ˜-3 during storms. Typical outer belt e-folding values are ˜200 keV, dropping to ˜150 keV during geomagnetic storms, while the inner belt e-folding values change from ˜120 keV to >200 keV. Analysis of geomagnetic storm periods show that the precipitating flux enhancements evident from such storms take approximately 13 days to return to normal values for the outer belt and slot region and approximately 10 days for the inner belt.

  3. Observation results of relativistic electrons detected by Fengyun-1 satellite and analysis of relativistic electron enhancement (REE) events

    Institute of Scientific and Technical Information of China (English)

    YANG XiaoChao; WANG Shidin

    2008-01-01

    The space particle component detector on Fengyun-1 satellite which works at the sun-synchronous orbit of about 870 km altitude has detected relativistic electrons for a long time.In comparison with the SAMPEX satellite observations during 1999--2004,the relativistic electron data from Fengyun-1 satellite from June 1999 to 2005 are used to analyze the relativistic electron enhancement (REE) events at the low earth orbit,and the possible correlation among REE events at the low earth orbit,high-speed solar wind and geomagnetic storms is discussed.The statistical result presents that 45 REE events are found in total during this time period,and the strong REE events with the maximum daily average flux > 400 cm-2.sr-1.s-1 occur mostly during the transition period from solar maximum to solar minimum.Among these 45 REE events,four strong REE events last a longer time period from 26- to 51-day and correlate closely with high speed solar wind and strong geo-magnetic storms.Meanwhile,several strong geomagnetic storms occur continu-ously before these REE events,and these continuous geomagnetic storms would be an important factor causing these long-lasting strong REE events.The correlation analysis for overall 45 events indicates that the strength of the REE events corre-lates with the solar wind speed and the strength of the geomagnetic storm,and the correlation for strong REE events is much stronger than that for weak REE events.

  4. Electron microscopic observation of hepatitis B virus budding from hepatocytes into bile canaliculi.

    OpenAIRE

    Ymadada, Gotaro; Sakamoto,Yuji; Mizuno, Motowo; Kobayashi, Toshinari; Nagashima,Hideo

    1980-01-01

    In electron microscopic observation of a liver biopsy obtained from a hepatitis B surface antigen-positive patient, noncoated core particles were occasionally seen budding into the hepatocytic cisterni and many Dane particles were found in the pericanalicular vesicles of hepatocytes. Noncoated core particles were also localized in clusters within the bleb of microvilli. There were some core particles being protruded from microvilli into the lumen of bile canaliculi by budding. These findings ...

  5. Scanning electron microscopic observation of Bruch's membrane with the osmium tetroxide treatment.

    OpenAIRE

    Yamamoto, T; Yamashita, H.

    1989-01-01

    Scanning electron microscopic observation of Bruch's membrane was performed after removal of retinal pigment epithelium (RPE) with the osmium tetroxide treatment. Eight human eyes from subjects at various ages (from newborn to 77 years old) were examined in order to investigate aging changes in Bruch's membrane. The collagen fibres of the inner collagenous zone in young eyes formed a tightly interwoven membrane, and the meshes were regular and fine. In old eyes the meshes were irregular and c...

  6. Observation of a new plasma regime with stationary electron temperature oscillations on Tore Supra

    Energy Technology Data Exchange (ETDEWEB)

    Artaud, J.F.; Giruzzi, G.; Imbeaux, F.; Segui, J.L.; Garbet, X

    2003-07-01

    This document is a copy of the slides presented on the 9. joint US-European Transport Task Force meeting. The first part is devoted to the experimental observations of a new tokamak plasma regime with stationary electron temperature oscillations. The oscillations appear on ECE spontaneously, sometimes associated with a transition to the LHEP regime. The second part presents an interpretation of these oscillations by analogy with a predator-prey system. (A.L.B.)

  7. Observation of a new plasma regime with stationary electron temperature oscillations on Tore Supra

    International Nuclear Information System (INIS)

    This document is a copy of the slides presented on the 9. joint US-European Transport Task Force meeting. The first part is devoted to the experimental observations of a new tokamak plasma regime with stationary electron temperature oscillations. The oscillations appear on ECE spontaneously, sometimes associated with a transition to the LHEP regime. The second part presents an interpretation of these oscillations by analogy with a predator-prey system. (A.L.B.)

  8. Direct observation of defect structure in protein crystals by atomic force and transmission electron microscopy.

    OpenAIRE

    Devaud, G; Furcinitti, P S; Fleming, J. C.; Lyon, M K; Douglas, K

    1992-01-01

    We have examined the structure of S-layers isolated from Sulfolobus acidocaldarius using atomic force microscopy (AFM) and transmission electron microscopy (TEM). From the AFM images, we were able to directly observe individual dimers of the crystal, defects in the crystal structure, and twin boundaries. We have identified two types of boundaries, one defined by a mirror plane and the other by a glide plane. This work shows that twin boundaries are highly structured regions that are directly ...

  9. The Pathogenesis of Candida Infections in a Human Skin Model: Scanning Electron Microscope Observations

    OpenAIRE

    Raz-Pasteur, A.; Ullmann, Y.; Berdicevsky, I.

    2011-01-01

    Cutaneous candidiasis is an opportunistic infection that arises, in most cases, from endogenous, saprophytic candidal blastospores that selectively colonize oral, gastrointestinal, vaginal, and cutaneous epithelium. Candida albicans has been regarded as the most common causative agent in human fungal infections. However, other Candida species have become a significant cause of infection. Scanning electron microscope (SEM) observations were used to analyze the capability of C. albicans, C. tro...

  10. Observations at the planet Mercury by the plasma electron experiment - Mariner 10

    Science.gov (United States)

    Ogilvie, K. W.; Scudder, J. D.; Vasyliunas, V. M.; Hartle, R. E.; Siscoe, G. L.

    1977-01-01

    Two nightside encounters with Mercury's magnetosphere by Mariner 10 revealed bow shock and magnetosheath signatures in the plasma electron data that are entirely consistent with the geometry expected for an interaction between a planet-centered magnetic dipole and the solar wind. The geometrically determined distance between the planet's center and the solar wind stagnation point is 1.4 plus or minus 0.1 R sub M. Both diffuse and sharp shock crossings were observed on the two magnetosphere encounters.

  11. New electronic states of NH and ND observed by resonance enhanced multiphoton ionization spectroscopy

    Science.gov (United States)

    Johnson, Russell D., III; Hudgens, Jeffrey W.

    1990-01-01

    Resonance Enhanced MultiPhoton Ionization (REMPI) spectra of NH and ND, which reveal four new electronic states are presented. Transitions from NH a 1 delta to 3s and 3p Rydberg states in both NH and ND have been observed and rotationally analyzed. The transitions were observed in the wavelength range of 258 to 288 nm. The state assignments are: e 1 pi (3s sigma) at 82857/cm, f 1 pi (3p sigma) at 86378/cm, g 1 delta (3p pi) at 88141/cm and h 1 sigma (3p pi) at 89151/cm.

  12. THREE-DIMENSIONAL OBSERVATIONS ON THICK BIOLOGICAL SPECIMENS BY HIGH VOLTAGE ELECTRON MICROSCOPY

    Directory of Open Access Journals (Sweden)

    Tetsuji Nagata

    2011-05-01

    Full Text Available Thick biological specimens prepared as whole mount cultured cells or thick sections from embedded tissues were stained with histochemical reactions, such as thiamine pyrophosphatase, glucose-6-phosphatase, cytochrome oxidase, acid phosphatase, DAB reactions and radioautography, to observe 3-D ultrastructures of cell organelles producing stereo-pairs by high voltage electron microscopy at accerelating voltages of 400-1000 kV. The organelles demonstrated were Golgi apparatus, endoplasmic reticulum, mitochondria, lysosomes, peroxisomes, pinocytotic vesicles and incorporations of radioactive compounds. As the results, those cell organelles were observed 3- dimensionally and the relative relationships between these organelles were demonstrated.

  13. High-energy electron observations by PPB-BETS flight in Antarctica

    CERN Document Server

    Torii, S; Tamura, T; Yoshida, K; Kitamura, H; Anraku, K; Chang, J; Ejiri, M; Iijima, I; Kadokura, A; Kasahara, K; Katayose, Y; Kobayashi, T; Komori, Y; Matsuzaka, Y; Mizutani, K; Murakami, H; Namiki, M; Nishimura, J; Ohta, S; Saitô, Y; Shibata, M; Tateyama, N; Yamagishi, H; Yamashita, T; Yuda, T

    2008-01-01

    We have observed cosmic-ray electrons from 10 GeV to 800 GeV by a long duration balloon flight using Polar Patrol Balloon (PPB) in Antarctica. The observation was carried out for 13 days at an average altitude of 35 km in January 2004. The detector is an imaging calorimeter composed of scintillating-fiber belts and plastic scintillators inserted between lead plates with 9 radiation lengths. The performance of the detector has been confirmed by the CERN-SPS beam test and also investigated by Monte-Carlo simulations. New telemetry system using a commercial satellite of Iridium, power supply by solar batteries, and automatic level control using CPU have successfully been developed and operated during the flight. From the long duration balloon observations, we derived the energy spectrum of cosmic-ray electrons in the energy range from 100 GeV to 800 GeV. In addition, for the first time we derived the electron arrival directions above 100 GeV, which is consistent with the isotropic distribution.

  14. Spectral evolution of GRB 060904A observed with Swift and Suzaku -- Possibility of Inefficient Electron Acceleration

    CERN Document Server

    Yonetoku, Daisuke; Murakami, Toshio; Emura, Naomi; Aoyama, Yuka; Kidamura, Takashi; Kodaira, Hironobu; Kodama, Yoshiki; Kozaka, Ryota; Nashimoto, Takuro; Okuno, Shinya; Yokota, Satoshi; Yoshinari, Satoru; Abe, Keiichi; Onda, Kaori; Tashiro, Makoto S; Urata, Yuji; Nakagawa, Yujin E; Sugita, Satoshi; Yamaoka, Kazutaka; Yoshida, Atsumasa; Ishimura, Takuto; Kawai, Nobuyuki; Shimokawabe, Takashi; Kinugasa, Kenzo; Kohmura, Takayoshi; Kubota, Kaori; Sugiyasu, Kei; Ueda, Yoshihiro; Masui, Kensuke; Nakazawa, Kazuhiro; Takahashi, Tadayuki; Maeno, Shouta; Sonoda, Eri; Yamauchi, Makoto; Kuwahara, Makoto; Tamagawa, Toru; Matsuura, Daisuke; Suzuki, Motoko; Barthelmy, Scott; Gehrels, Neil; Nousek, John

    2007-01-01

    We observed an X-ray afterglow of GRB 060904A with the Swift and Suzaku satellites. We found rapid spectral softening during both the prompt tail phase and the decline phase of an X-ray flare in the BAT and XRT data. The observed spectra were fit by power-law photon indices which rapidly changed from $\\Gamma = 1.51^{+0.04}_{-0.03}$ to $\\Gamma = 5.30^{+0.69}_{-0.59}$ within a few hundred seconds in the prompt tail. This is one of the steepest X-ray spectra ever observed, making it quite difficult to explain by simple electron acceleration and synchrotron radiation. Then, we applied an alternative spectral fitting using a broken power-law with exponential cutoff (BPEC) model. It is valid to consider the situation that the cutoff energy is equivalent to the synchrotron frequency of the maximum energy electrons in their energy distribution. Since the spectral cutoff appears in the soft X-ray band, we conclude the electron acceleration has been inefficient in the internal shocks of GRB 060904A. These cutoff spectr...

  15. Electron microscopic observation of the respiratory tract of SPF piglets inoculated with Mycoplasma hyopneumoniae

    International Nuclear Information System (INIS)

    Seven hysterectomy derived piglets were repeatedly challenged with Mycoplasma hyopneumoniae during the first week of life. Samples of trachea, bronchi and lung tissue collected 2-11 weeks post-inoculation (p.i.) were examined using light and electron microscopy. Autoradiography was used to study in more detail the site of M. hyopneumoniae multiplication. Gross lesions were observed in lung tissue and were characterized by hyperplasia of the epithelium and an increased mononuclear cell accumulation in perivascular and peribronchiolar areas. Mild lesions of the trachea and the bronchi, including epithelial hyperplasia and infiltration of the lamina propria by inflammatory cells, were noted. Electron microscopy showed that, 2-6 weeks p.i., changes in the mid-trachea and bronchi surface consisted of the loss of cilia. Mycoplasmas covered tufts of cilia remaining on the epithelial cell surface. Scanning and transmission electron micrographs showed that they were predominantly found closely associated with the top of cilia. No specialized terminal structure could be seen and no mycoplasma cells were identified lying free in the lumen nor in close contact with the plasma membrane of cells or microvilli. Some fine fibrils radiating from one mycoplasma to another or to cilia were seen at higher magnification by scanning electron microscopy. Six to eleven weeks p.i., a disrupted epithelial surface lacking cilia was observed. Cells were desquamated and shed into the lumen with cellular remains containing droplets of mucus. Autoradiography revealed that label corresponded to the observed mycoplasma distribution. At the top of cilia, a high density of labeling was visible in the zone of high mycoplasma concentration. Therefore, incorporation of the label in the mycoplasma is proof or their multiplication in the trachea. The intimate association between the mycoplasma and cilia may be an important factor in the pathogenesis of the disease caused by M. hyopneumoniae (swine

  16. Photoelectron spectroscopy of hexachloroplatinate-nucleobase complexes: Nucleobase excited state decay observed via delayed electron emission

    Energy Technology Data Exchange (ETDEWEB)

    Sen, Ananya; Matthews, Edward M.; Dessent, Caroline E. H., E-mail: caroline.dessent@york.ac.uk, E-mail: xuebin.wang@pnnl.gov [Department of Chemistry, University of York, Heslington, York YO10 5DD (United Kingdom); Hou, Gao-Lei; Wang, Xue-Bin, E-mail: caroline.dessent@york.ac.uk, E-mail: xuebin.wang@pnnl.gov [Physical Sciences Division, Pacific Northwest National Laboratory, MS K8-88, P.O. Box 999, Richland, Washington 99352 (United States)

    2015-11-14

    We report low-temperature photoelectron spectra of isolated gas-phase complexes of the hexachloroplatinate dianion bound to the nucleobases uracil, thymine, cytosine, and adenine. The spectra display well-resolved, distinct peaks that are consistent with complexes where the hexachloroplatinate dianion is largely intact. Adiabatic electron detachment energies for the hexachloroplatinate-nucleobase complexes are measured as 2.26-2.36 eV. The magnitudes of the repulsive Coulomb barriers (RCBs) of the complexes are all ∼1.7 eV, values that are lower than the RCB of the uncomplexed PtCl{sub 6}{sup 2−} dianion as a result of charge solvation by the nucleobases. In addition to the resolved spectral features, broad featureless bands indicative of delayed electron detachment are observed in the 193 nm photoelectron spectra of the four clusters. The 266 nm spectra of the PtCl{sub 6}{sup 2−} ⋅ thymine and PtCl{sub 6}{sup 2−} ⋅ adenine complexes also display very prominent delayed electron emission bands. These results mirror recent results on the related Pt(CN){sub 4}{sup 2−} ⋅ nucleobase complexes [A. Sen et al., J. Phys. Chem. B 119, 11626 (2015)]. The observation of delayed electron emission bands in the PtCl{sub 6}{sup 2−} ⋅ nucleobase spectra obtained in this work, as for the previously studied Pt(CN){sub 4}{sup 2−} ⋅ nucleobase complexes, is attributed to one-photon excitation of nucleobase-centred excited states that can effectively couple to the electron detachment continuum, producing strong electron detachment. Moreover, the selective, strong excitation of the delayed emission bands in the 266 nm spectra is linked to fundamental differences in the individual nucleobase photophysics at this excitation energy. This strongly supports our previous suggestion that the dianion within these clusters can be viewed as a “dynamic tag” which has the propensity to emit electrons when the attached nucleobase decays over a time scale long enough to

  17. Direct observation of ultrafast-electron-transfer reactions unravels high effectiveness of reductive DNA damage.

    Science.gov (United States)

    Nguyen, Jenny; Ma, Yuhan; Luo, Ting; Bristow, Robert G; Jaffray, David A; Lu, Qing-Bin

    2011-07-19

    Both water and electron-transfer reactions play important roles in chemistry, physics, biology, and the environment. Oxidative DNA damage is a well-known mechanism, whereas the relative role of reductive DNA damage is unknown. The prehydrated electron (e(pre)-), a novel species of electrons in water, is a fascinating species due to its fundamental importance in chemistry, biology, and the environment. e(pre)- is an ideal agent to observe reductive DNA damage. Here, we report both the first in situ femtosecond time-resolved laser spectroscopy measurements of ultrafast-electron-transfer (UET) reactions of e(pre)- with various scavengers (KNO(3), isopropanol, and dimethyl sulfoxide) and the first gel electrophoresis measurements of DNA strand breaks induced by e(pre)- and OH(•) radicals co-produced by two-UV-photon photolysis of water. We strikingly found that the yield of reductive DNA strand breaks induced by each e(pre)- is twice the yield of oxidative DNA strand breaks induced by each OH(•) radical. Our results not only unravel the long-standing mystery about the relative role of radicals in inducing DNA damage under ionizing radiation, but also challenge the conventional notion that oxidative damage is the main pathway for DNA damage. The results also show the potential of femtomedicine as a new transdisciplinary frontier and the broad significance of UET reactions of e(pre)- in many processes in chemistry, physics, biology, and the environment. PMID:21730183

  18. Thomson Scattering Observation of Non-Maxwellian EEDF and the Effect of Local Electron Heating

    Science.gov (United States)

    Kono, A.; Funahashi, H.

    2001-10-01

    Laser Thomson scattering measurements were carried out to study electron energy distribution function (EEDF) of inductively coupled plasmas using C_4F_8/Ar and CF_4/Ar mixture gases. The plasma was produced using a one-turn coil antenna immersed in the plasma at a total pressure of 25 mTorr. A specially designed triple-grating spectrometer was used, which produces Thomson spectra on the output focal plane with the interfering Rayleigh and stray components highly suppressed; an ICCD camera operated in the photon-counting mode was used for multichannel detection of the spectrum. At a RF (13.56 MHz) input power of 300 W in the case of pure Ar plasma, EEDF was Maxwellian with an enectron density >10^12 cm-3. Upon mixing of C_4F8 as well as CF_4, decrease in the electron density and upward bend of the plot of the Thomson spectrum (energy vs. logarithmic scattering intensity) at energies around 5 eV was observed. The mechanism for producing this bend was studied via Monte-Carlo particle simulation. The results indicate that electron heating in a uniform electric field does not lead to upward bend; electrons should be heated locally near the antenna surface where the RF electric field is strong and cooled in other part of the plasma by inelastic collisions.

  19. Observation of two-center interference effects for electron impact ionization of N2

    Science.gov (United States)

    Chaluvadi, Hari; Nur Ozer, Zehra; Dogan, Mevlut; Ning, Chuangang; Colgan, James; Madison, Don

    2015-08-01

    In 1966, Cohen and Fano (1966 Phys. Rev. 150 30) suggested that one should be able to observe the equivalent of Young’s double slit interference if the double slits were replaced by a diatomic molecule. This suggestion inspired many experimental and theoretical studies searching for double slit interference effects both for photon and particle ionization of diatomic molecules. These effects turned out to be so small for particle ionization that this work proceeded slowly and evidence for interference effects were only found by looking at cross section ratios. Most of the early particle work concentrated on double differential cross sections for heavy particle scattering and the first evidence for two-center interference for electron-impact triple differential cross section (TDCS) did not appear until 2006 for ionization of H2. Subsequent work has now firmly established that two-center interference effects can be seen in the TDCS for electron-impact ionization of H2. However, in spite of several experimental and theoretical studies, similar effects have not been found for electron-impact ionization of N2. Here we report the first evidence for two-center interference for electron-impact ionization of N2.

  20. Gradual Diffusion and Punctuated Phase Space Density Enhancements of Highly Relativistic Electrons: Van Allen Probes Observations

    Science.gov (United States)

    Baker, D. N.; Jaynes, A. N.; Li, X.; Henderson, M. G.; Kanekal, S. G.; Reeves, G. D.; Spence, H. E.; Claudepierre, S. G.; Fennell, J. F.; Hudson, M. K.

    2014-01-01

    The dual-spacecraft Van Allen Probes mission has provided a new window into mega electron volt (MeV) particle dynamics in the Earth's radiation belts. Observations (up to E (is) approximately 10MeV) show clearly the behavior of the outer electron radiation belt at different timescales: months-long periods of gradual inward radial diffusive transport and weak loss being punctuated by dramatic flux changes driven by strong solar wind transient events. We present analysis of multi-MeV electron flux and phase space density (PSD) changes during March 2013 in the context of the first year of Van Allen Probes operation. This March period demonstrates the classic signatures both of inward radial diffusive energization and abrupt localized acceleration deep within the outer Van Allen zone (L (is) approximately 4.0 +/- 0.5). This reveals graphically that both 'competing' mechanisms of multi-MeV electron energization are at play in the radiation belts, often acting almost concurrently or at least in rapid succession.

  1. First observation of neutral current proton electron scattering at √s = 300 GeV

    International Nuclear Information System (INIS)

    Neutral current proton electron scattering at center of mass energy 295 GeV was observed for the first time, using the newly built proton electron collider HERA (Hadron Elektron Ring Anlage) and the general purpose detector ZEUS. The distributions of Q2, Bjorken-x(x) and Bjorken-y(y) were compared with the expectation based on the standard electroweak theory and QCD. Regarding the investigation of high-Q2 region, an event of Q2 ∼ 1000 GeV2 was observed for the first time. From the x-distribution of the events, a limit on the mass and the coupling of an exotic s-channel resonance of a quark-lepton system (leptoquark) was obtained. The mass limit is 72 GeV(97 GeV) at 95% confidence level for a scalar type leptoquark with a left-handed (right-handed) electromagnetic coupling to ordinary leptons. The leptoquark is assumed to be weak-isoscalar. To realize this experiment a uranium scintillator sandwich type calorimeter was developed. Equal response to electrons and hadrons (e/h = 1), which is essential for the good energy resolution for hadrons, has been achieved. One of the main characteristics of this calorimeter is a possibility of calibration utilizing of its own uranium radioactivity. The grain variation of each channel can be detected with an accuracy of ± 1 %. (J.P.N.) 65 refs

  2. Scanning Electron Microscopic Observation on Morphologic Characteristics of Sperms in Uremic Patients

    Institute of Scientific and Technical Information of China (English)

    Long-gen XU; Shi-fang SHI; Hai-zhen ZHONG; Xiao-feng HUANG; Xiao-ping QI; Qi-zhe SONG; Xin-hong WANG; Li YAN; Zong-fu SHAO

    2004-01-01

    Objective To observe the morphologic characteristics of spermatozoon ultramicro scopic structure in uremic subjects Method Semen sample from 10 patients with uremia and 5 healthy men were observed under light microscope and scanning electronic microscope.Results Abnormalities were found in sperms of uremic patients either in the sperm head (acrosome, acrosomic deficit, nuclear abnormality, pointed head, headless and double head of spermatozoon), neck (rupture, separation and enlargement), or tail (mitochondrial swelling, mitochondrial deficit, tailless, double tail, short tail and curled tail); whereas none of the above-mentioned abnormalities was observed in healthy men.Conclusion Sperms of uremic patients had many morphologic and structural abnor malities in the head, neck and tail.

  3. Observation of electron excitation into silicon conduction band by slow-ion surface neutralization

    CERN Document Server

    Shchemelinin, S

    2016-01-01

    Bare reverse biased silicon photodiodes were exposed to 3eV He+, Ne+, Ar+, N2+, N+ and H2O+ ions. In all cases an increase of the reverse current through the diode was observed. This effect and its dependence on the ionization energy of the incident ions and on other factors are qualitatively explained in the framework of Auger-type surface neutralization theory. Amplification of the ion-induced charge was observed with an avalanche photodiode under high applied bias. The observed effect can be considered as ion-induced internal potential electron emission into the conduction band of silicon. To the best of our knowledge, no experimental evidence of such effect was previously reported. Possible applications are discussed.

  4. Transmission electron microscopic observations of nanobubbles and their capture of impurities in wastewater

    Directory of Open Access Journals (Sweden)

    Soejima Koichi

    2011-01-01

    Full Text Available Abstract Unique properties of micro- and nanobubbles (MNBs, such as a high adsorption of impurities on their surface, are difficult to verify because MNBs are too small to observe directly. We thus used a transmission electron microscope (TEM with the freeze-fractured replica method to observe oxygen (O2 MNBs in solutions. MNBs in pure water and in 1% NaCl solutions were spherical or oval. Their size distribution estimated from TEM images close to that of the original solution is measured by light-scattered methods. When we applied this technique to the observation of O2 MNBs formed in the wastewater of a sewage plant, we found the characteristic features of spherical MNBs that adsorbed surrounding impurity particles on their surface. PACS: 68.03.-g, 81.07.-b, 92.40.qc

  5. Electron microscopic observation and rotational diffusion measurement of bacteriorhodopsin in lipid vesicles

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The morphology of bacteriorhodopsin reconstituted into dimyristoylphosphatidylcholine and egg-phosphatidylcholine vesicles was observed by freeze-fracture electron microscopy. The rotational diffusion of bacteriorhodopsin at different concentrations of melittin was measured by observing flash-induced transient dichroism in dimyristoylphosphatidylcholine vesicles. In the presence of melittin, bacteriorhodopsin molecules in dimyristoylphosphatidylcholine vesicles were aggregated into large particles or patches, and the ability of rotational diffusion of bacteriorhodop sin in vesicles was decreased. This suggests that melittin produces its effect via direct electrostatic interaction with bacteriorhodopsin. Low temperature-induced aggregation of bacteriorhodopsin was also observed in dimyristoylphosphatidylcholine vesicles. Low temperature may cause phase separation. Bacteriorhodopsin was also successfully reconstituted into egg-phosphatidylcholine vesicles, but Iow temperature-induced aggregation of bacteriorhodopsin in dimyristoylphosphati dylcholine cannot appear in egg-phosphatidylcholine vesicles. This suggests that different lipids have different effects on bacteriorhodopsin in vesicles.

  6. Observations of low-aberration plasma lens focusing of relativistic electron beams at the underdense threshold

    International Nuclear Information System (INIS)

    Focusing of a 15 MeV electron bunch by a plasma lens operated at the threshold of the underdense regime has been demonstrated. The strong, 1.7 cm focal length, plasma lens focused both transverse directions simultaneously and reduced the minimum area of the beam spot by a factor of 23. It is shown through analytic analysis and simulation that the observed spherical aberration of this underdense lens, when expressed as the fractional departure of the focusing strength from its linear expectation, is ΔK/K=0.08±0.04. This is significantly lower than the minimum theoretical value for the spherical aberration of an overdense plasma lens. Parameter scans showing the dependence of focusing performance on beam charge, as well as time resolved measurements of the focused electron bunch, are reported.

  7. Observation of surface discharge on polymer films irradiated by electron beam

    International Nuclear Information System (INIS)

    The surface discharge on dielectric surfaces of a spacecraft caused by spacecraft charging is simulated by using a high vacuum chamber equipped with an electron beam gun. Fluoroethylene-propylene (FEP) and polyethleneterephthalate (PET) films frequently employed as thermal control materials are irradiated by an electron beam until surface discharges occur, then the spectrum and waveform of emitted light of discharge, together with the current waveform of the discharge and the mass spectrum of the gas in the vacuum chamber are measured. In the range of 300 through 700 nm of the wavelength, light emission from CN radicals, C2 radicals, CH radicals and hydrogen atoms are detected. From this result, it is suggested that water molecules in the residual gas and molecules in the structure of the specimen contribute the light emission. The spectroscopic observation of the light emission suggests that the discharge energy is concentrated on PET more than that on FEP. (author)

  8. Direct observation of multistep energy transfer in LHCII with fifth-order 3D electronic spectroscopy

    Science.gov (United States)

    Zhang, Zhengyang; Lambrev, Petar H.; Wells, Kym L.; Garab, Győző; Tan, Howe-Siang

    2015-07-01

    During photosynthesis, sunlight is efficiently captured by light-harvesting complexes, and the excitation energy is then funneled towards the reaction centre. These photosynthetic excitation energy transfer (EET) pathways are complex and proceed in a multistep fashion. Ultrafast two-dimensional electronic spectroscopy (2DES) is an important tool to study EET processes in photosynthetic complexes. However, the multistep EET processes can only be indirectly inferred by correlating different cross peaks from a series of 2DES spectra. Here we directly observe multistep EET processes in LHCII using ultrafast fifth-order three-dimensional electronic spectroscopy (3DES). We measure cross peaks in 3DES spectra of LHCII that directly indicate energy transfer from excitons in the chlorophyll b (Chl b) manifold to the low-energy level chlorophyll a (Chl a) via mid-level Chl a energy states. This new spectroscopic technique allows scientists to move a step towards mapping the complete complex EET processes in photosynthetic systems.

  9. Real-time observation of interfering crystal electrons in high-harmonic generation

    CERN Document Server

    Hohenleutner, M; Schubert, O; Knorr, M; Huttner, U; Koch, S W; Kira, M; Huber, R

    2016-01-01

    Accelerating and colliding particles has been a key strategy to explore the texture of matter. Strong lightwaves can control and recollide electronic wavepackets, generating high-harmonic (HH) radiation which encodes the structure and dynamics of atoms and molecules and lays the foundations of attosecond science. The recent discovery of HH generation in bulk solids combines the idea of ultrafast acceleration with complex condensed matter systems and sparks hope for compact solid-state attosecond sources and electronics at optical frequencies. Yet the underlying quantum motion has not been observable in real time. Here, we study HH generation in a bulk solid directly in the time-domain, revealing a new quality of strong-field excitations in the crystal. Unlike established atomic sources, our solid emits HH radiation as a sequence of subcycle bursts which coincide temporally with the field crests of one polarity of the driving terahertz waveform. We show that these features hallmark a novel non-perturbative qua...

  10. Observation of the continuous stern-gerlach effect on an electron bound in an atomic Ion

    Science.gov (United States)

    Hermanspahn; Haffner; Kluge; Quint; Stahl; Verdu; Werth

    2000-01-17

    We report on the first observation of the continuous Stern-Gerlach effect on an electron bound in an atomic ion. The measurement was performed on a single hydrogenlike ion ( 12C5+) in a Penning trap. The measured g factor of the bound electron, g = 2.001 042(2), is in excellent agreement with the theoretical value, confirming the relativistic correction at a level of 0.1%. This proves the possibility of g-factor determinations on atomic ions to high precision by using the continuous Stern-Gerlach effect. The result demonstrates the feasibility of conducting experiments on single heavy highly charged ions to test quantum electrodynamics in the strong electric field of the nucleus. PMID:11015930

  11. Observation and applications of single-electron charge signals in the XENON100 experiment

    CERN Document Server

    Aprile, E; Arisaka, K; Arneodo, F; Balan, C; Baudis, L; Bauermeister, B; Behrens, A; Beltrame, P; Bokeloh, K; Brown, A; Brown, E; Bruenner, S; Bruno, G; Budnik, R; Cardoso, J M R; Chen, W -T; Choi, B; Colijn, A P; Contreras, H; Cussonneau, J P; Decowski, M P; Duchovni, E; Fattori, S; Ferella, A D; Fulgione, W; Gao, F; Garbini, M; Ghag, C; Giboni, K -L; Goetzke, L W; Grignon, C; Gross, E; Hampel, W; Itay, R; Kaether, F; Kessler, G; Kish, A; Lamblin, J; Landsman, H; Lang, R F; Calloch, M Le; Levy, C; Lim, K E; Lin, Q; Lindemann, S; Lindner, M; Lopes, J A M; Lung, K; Undagoitia, T Marrodan; Massoli, F V; Fernandez, A J Melgarejo; Meng, Y; Messina, M; Molinario, A; Naganoma, J; Ni, K; Oberlack, U; Orrigo, S E A; Pantic, E; Persiani, R; Piastra, F; Plante, G; Priel, N; Rizzo, A; Rosendahl, S; Santos, J M F dos; Sartorelli, G; Schreiner, J; Schumann, M; Lavina, L Scotto; Selvi, M; Shagin, P; Simgen, H; Teymourian, A; Thers, D; Vitells, O; Wang, H; Weber, M; Weinheimer, C

    2014-01-01

    The XENON100 dark matter experiment uses liquid xenon in a time projection chamber (TPC) to measure xenon nuclear recoils resulting from the scattering of dark matter Weakly Interacting Massive Particles (WIMPs). In this paper, we report the observation of single-electron charge signals which are not related to WIMP interactions. These signals, which show the excellent sensitivity of the detector to small charge signals, are explained as being due to the photoionization of impurities in the liquid xenon and of the metal components inside the TPC. They are used as a unique calibration source to characterize the detector. We explain how we can infer crucial parameters for the XENON100 experiment: the secondary-scintillation gain, the extraction yield from the liquid to the gas phase and the electron drift velocity.

  12. Statistical characteristics of EMIC wave-driven relativistic electron precipitation with observations of POES satellites: Revisit

    Science.gov (United States)

    Wang, Zhenzhen; Yuan, Zhigang; Li, Ming; Li, Huimin; Wang, Dedong; Li, Haimeng; Huang, Shiyong; Qiao, Zheng

    2014-07-01

    Electromagnetic ion cyclotron (EMIC) waves play an important role in the magnetospheric dynamics and can scatter relativistic electrons in the outer radiation belt into the loss cone leading to the rapid loss of relativistic electrons. In this paper, we present characteristics of EMIC wave-driven relativistic electron precipitation (REP) with observations of six Polar Orbiting Environmental Satellites (POES). Based on the simultaneity between spikes in the P1 0° (Ep = 30 keV-80 keV) and P6 0° (Ee > 1 MeV) channels, in comparison with the criterion of Carson et al. (2013), we improve the algorithm and make it stricter. A total of 436,286 individual half orbits between 1998 and 2010 are inspected by this algorithm. The majority of selected events are observed at L values within the outer radiation belt (3 < L < 7) and more common in 1800-2200 magnetic local time. The distribution of normalized events follows the location of plasmapause contracting toward lower L value with the decrease of the Dst index, implying a strong link between detected events and the plasmapause. The cluster of normalized events moves to later afternoon sector where the peak occurrence of plasmaspheric plumes is located during geomagnetic storms. It is suggested that there is a connection between plasmaspheric plumes and detected events. Corresponding to the peak of event occurrence in 2003, solar wind dynamic pressure has a same peak. In addition, the minimum values of them are coincident. These results indicate that the increase of the solar wind dynamic pressure enhances the likelihood of EMIC wave-driven relativistic electron precipitation.

  13. Electron Temperatures in W51 Complex from High Resolution, Low Frequency Radio Observations

    Indian Academy of Sciences (India)

    P. K. Srivastava; A. Pramesh Rao

    2010-03-01

    W51 is a giant radio complex lying along the tangent to the Sagitarius arm at a distance of about 7 kpc from the Sun, with an extension of about 1° in the sky. It is divided into three components A, B, C where W51A and W51B consist of many compact HII regions while W51C is a supernova remnant. We have made continuum radio observations of these HII regions of the W51 complex at 240, 610, 1060 and 1400 MHz using GMRT with lower resolution (20'' × 15'') at the lowest frequency. The observed spectra of the prominent thermal subcomponents of W51 have been fitted to a free-free emission spectrum and their physical properties like electron temperatures and emission measures have been estimated. The electron temperatures from continuum spectra are found to be lower than the temperatures reported from radio recombination line (RRL) studies of these HII regions indicating the need for a filling factor even at this resolution. Also, the observed brightness at 240 MHz is found to be higher than expected from the best fits suggesting the need for a multicomponent model for the region.

  14. Benchmarking Electron-Cloud Build-Up and Heat-Load Simulations against Large-Hadron-Collider Observations

    OpenAIRE

    Dominguez, O; Iriso, U; Maury, H.; Rumolo, G.; Zimmermann, F

    2011-01-01

    After reviewing the basic features of electron clouds in particle accelerators, the pertinent vacuum-chamber surface properties, and the electron-cloud simulation tools in use at CERN, we report recent observations of electron-cloud phenomena at the Large Hadron Collider (LHC) and ongoing attempts to benchmark the measured LHC vacuum pressure increases and heat loads against electron-cloud build-up simulations aimed at determining the actual surface parameters and at monitoring the so-called ...

  15. Whistler mode waves and the electron heat flux in the solar wind: Cluster observations

    OpenAIRE

    Lacombe, Catherine; Alexandrova, Olga; Matteini, Lorenzo; Santolik, Ondrej; Cornilleau-Wehrlin, Nicole; Mangeney, Andre; de Conchy, Yvonne; Maksimovic, Milan

    2014-01-01

    The nature of the magnetic field fluctuations in the solar wind between the ion and electron scales is still under debate. Using the Cluster/STAFF instrument, we make a survey of the power spectral density and of the polarization of these fluctuations at frequencies $f\\in[1,400]$ Hz, during five years (2001-2005), when Cluster was in the free solar wind. In $\\sim 10\\%$ of the selected data, we observe narrow-band, right-handed, circularly polarized fluctuations, with wave vectors quasi-parall...

  16. Laboratory Observation of Resistive Electron Tearing in a Two-Fluid Reconnecting Current Sheet.

    Science.gov (United States)

    Jara-Almonte, Jonathan; Ji, Hantao; Yamada, Masaaki; Yoo, Jongsoo; Fox, William

    2016-08-26

    The spontaneous formation of plasmoids via the resistive electron tearing of a reconnecting current sheet is observed in the laboratory. These experiments are performed during driven, antiparallel reconnection in the two-fluid regime within the Magnetic Reconnection Experiment. It is found that plasmoids are present even at a very low Lundquist number, and the number of plasmoids scales with both the current sheet aspect ratio and the Lundquist number. The reconnection electric field increases when plasmoids are formed, leading to an enhanced reconnection rate. PMID:27610861

  17. Real-time transmission electron microscope observation of nanofriction at a single Ag asperity

    International Nuclear Information System (INIS)

    The observation of nanoscale deformation in real time is a significant step toward understanding the mechanisms of friction and lubrication. Our experimental setup of a micromachine combined with a transmission electron microscope allowed us to measure the deformation, force and cross-sectional area of a single Ag asperity during shear testing. The experimental results provided insight into one of the parameters that determines the frictional coefficient. Furthermore, we demonstrated that the energy loss associated with a shear fracture event is strongly correlated with the increase in total surface energy of the two surfaces formed here after the fracture of the nanocontact. (paper)

  18. Transmission electron microscopy observations of fracture of single-wall carbon nanotubes under axial tension

    Science.gov (United States)

    Lourie, O.; Wagner, H. D.

    1998-12-01

    Well-aligned bundles of single-wall carbon nanotubes under tensile stresses were observed to fracture in real-time by transmission electron microscopy. The expansion of elliptical holes in the polymer matrix results in a tensile force in bridging nanotubes. The polymer matrix at both ends of the bundles deforms extensively under the tension force, and fracture of the nanotubes occurs in tension within the polymer hole region rather than in shear within the gripping polymer region at the ends of the bundles. This provides evidence of significant polymer-nanotube wetting and interfacial adhesion.

  19. Observations of Energetic Ions and Electrons in the Distant Heliosphere: 2001 - 2005.0

    International Nuclear Information System (INIS)

    As Voyager 1 (V1) moves closer to the heliospheric termination shock (TS), a new energetic particle population is observed: Termination Shock Particle events (TSP). Interplanetary disturbances in the form of merged interaction regions (MIRs) -- identified using Voyager 2 (V2) data -- have a major effect on the V1 TSP events from their onset to termination along with triggering episodic increases in higher energy ions (35 MeV H) and MeV electrons. The nature of these interactions appear to evolve as V1 moves closer to the TS

  20. Dynamics of Supported Metal Nanoparticles Observed in a CS Corrected Environmental Transmission Electron Microscope

    DEFF Research Database (Denmark)

    Hansen, Thomas Willum; Dunin-Borkowski, Rafal E.; Wagner, Jakob Birkedal

    resulting in the formation of larger particles and a loss of catalytic performance. Several models of sintering in different systems have been put forward [1,2]. However, most investigations have been post mortem studies, revealing only the final state of the catalyst. Transmission electron microscopy (TEM...... behavior of the nanoparticles were recorded. Under these conditions, mobility of the particles was clearly visible, while maintaining lattice resolution of both the BN support and the Au particles. Some particles remained immobile during observation while others behaved dynamically on the support. Some...

  1. Implications of Voyager 1 observations beyond the heliopause for the local interstellar electron spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Bisschoff, D.; Potgieter, M. S., E-mail: 20056950@nwu.ac.za [Centre for Space Research, North-West University, 2520 Potchefstroom (South Africa)

    2014-10-20

    Cosmic-ray observations made by the Voyager 1 spacecraft outside the dominant modulating influence of the heliosphere finally allow the comparison of computed galactic spectra with experimental data at lower energies. These computed spectra, based on galactic propagation models, can now be compared with observations at low energies by Voyager 1 and at high energies by the PAMELA space detector at Earth. This improves understanding of basic propagation effects and also provides solar modulation studies with reliable input spectra from 1 MeV to 100 GeV. We set out to reproduce the Voyager 1 electron observations in the energy range of 6-60 MeV, as well as the PAMELA electron spectrum above 10 GeV, using the GALPROP code. By varying the source spectrum and galactic diffusion parameters, specifically the rigidity dependence of spatial diffusion, we find local interstellar spectra that agree with both power-law spectra observed by Voyager 1 beyond the heliopause. The local interstellar spectrum between ∼1 MeV and 100 GeV indicates that it is the combination of two power laws, with E {sup –(1.45} {sup ±} {sup 0.15)} below ∼100 MeV and E {sup –(3.15} {sup ±} {sup 0.05)} above ∼100 MeV. A gradual turn in the spectral shape matching the power laws is found, between 2.0 ± 0.5) GeV and (100 ± 10) MeV. According to our simplified modeling, this transition is caused primarily by galactic propagation effects. We find that the intensity beyond the heliopause at 10 MeV is (350 ± 50) electrons m{sup –2} s{sup –1} sr{sup –1} MeV{sup –1}, decreasing to (50 ± 5) electrons m{sup –2} s{sup –1} sr{sup –1} MeV{sup –1} at 100 MeV.

  2. Observation of Einstein-Podolsky-Rosen type correlations with an electron multiplying CCD camera

    CERN Document Server

    Edgar, Matthew P; Izdebski, Frauke; Warburton, Ryan E; Leach, Jonathan; Agnew, Megan; Buller, Gerald S; Boyd, Robert W; Padgett, Miles J

    2012-01-01

    The light produced by parametric down-conversion shows strong spatial entanglement that leads to violations of EPR criteria for separability. Historically, such studies have been performed by scanning a single-element, single-photon detector across a detection plane. Here we show that modern electron-multiplying CCD cameras can measure correlations in both position and momentum across a multi-pixel field of view. This capability allows us to observe entanglement of around 2500 spatial states and demonstrate EPR-type correlations by more than two orders of magnitude. More generally, our work shows that such cameras can lead to important new capabilities in quantum optics and quantum information science.

  3. Study of the North West Cape electron belts observed by DEMETER satellite

    OpenAIRE

    Li, Xinqiao; Ma, Yuqian; Ping WANG; Wang, Huanyu; Lu, Hong; Zhang, Xuemin; Huang, Jianping; Shi, Feng; Yu, Xiaoxia; Xu, Yanbing; Meng, Xiangcheng; Wang, Hui; Zhao, Xiaoyun; Parrot, Michel

    2012-01-01

    [1] We analyzed observation data collected by the Instrument for the Detection of Particles (IDP) on board the DEMETER satellite during a period of 17 months in 2007 and 2008. In the meantime, the VLF transmitter located at North West Cape (NWC) ground station was shut down during 7 months and working for a total of 10 months. By an (on-off) method, our analysis for the first time revealed in detail the transient properties of the space electron precipitation belt which is induced by the man-...

  4. X-ray laser–induced electron dynamics observed by femtosecond diffraction from nanocrystals of Buckminsterfullerene

    Science.gov (United States)

    Abbey, Brian; Dilanian, Ruben A.; Darmanin, Connie; Ryan, Rebecca A.; Putkunz, Corey T.; Martin, Andrew V.; Wood, David; Streltsov, Victor; Jones, Michael W. M.; Gaffney, Naylyn; Hofmann, Felix; Williams, Garth J.; Boutet, Sébastien; Messerschmidt, Marc; Seibert, M. Marvin; Williams, Sophie; Curwood, Evan; Balaur, Eugeniu; Peele, Andrew G.; Nugent, Keith A.; Quiney, Harry M.

    2016-01-01

    X-ray free-electron lasers (XFELs) deliver x-ray pulses with a coherent flux that is approximately eight orders of magnitude greater than that available from a modern third-generation synchrotron source. The power density of an XFEL pulse may be so high that it can modify the electronic properties of a sample on a femtosecond time scale. Exploration of the interaction of intense coherent x-ray pulses and matter is both of intrinsic scientific interest and of critical importance to the interpretation of experiments that probe the structures of materials using high-brightness femtosecond XFEL pulses. We report observations of the diffraction of extremely intense 32-fs nanofocused x-ray pulses by a powder sample of crystalline C60. We find that the diffraction pattern at the highest available incident power significantly differs from the one obtained using either third-generation synchrotron sources or XFEL sources operating at low output power and does not correspond to the diffraction pattern expected from any known phase of crystalline C60. We interpret these data as evidence of a long-range, coherent dynamic electronic distortion that is driven by the interaction of the periodic array of C60 molecular targets with intense x-ray pulses of femtosecond duration.

  5. Electron microscopy observations of radiation damage in irradiated and annealed tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Grzonka, J., E-mail: j.grzonka@inmat.pw.edu.pl [Warsaw University of Technology, Wołoska 141 St., PL-02507 Warsaw (Poland); Ciupiński, Ł., E-mail: lciupinski@gmail.com [Warsaw University of Technology, Wołoska 141 St., PL-02507 Warsaw (Poland); Smalc-Koziorowska, J., E-mail: julita@unipress.waw.pl [Institute of High Pressure Physics PAS, Sokołowska 29/37, PL-01142 Warsaw (Poland); Ogorodnikova, O.V., E-mail: igra32@rambler.ru [Max Planck Institute of Plasma Physics, Boltzmannstr. 2, D-85748 Garching (Germany); National Research Nuclear University “MEPHI”, Kashirskoe sh.31, Moscow (Russian Federation); Mayer, M., E-mail: Matej.Mayer@ipp.mpg.de [Max Planck Institute of Plasma Physics, Boltzmannstr. 2, D-85748 Garching (Germany); Kurzydłowski, K.J., E-mail: kjk@inmat.pw.edu.pl [Warsaw University of Technology, Wołoska 141 St., PL-02507 Warsaw (Poland)

    2014-12-01

    In the present work tungsten samples were irradiated with W{sup 6+} ions with a kinetic energy of 20 MeV in order to simulate radiation damage by fast neutrons. Two samples with cumulative damage of 2.3 and 6.36 displacements per atom were produced. The scanning transmission electron microscopy investigations were carried out in order to determine structure changes resulting from the irradiation. The evolution of the damage with post implantation annealing in the temperature range 673–1100 K was also assessed. Damage profiles were studied at cross-sections. Scanning transmission electron microscopy studies of the lamellae after annealing revealed aggregation of defects and rearrangement as well as partial healing of dislocations at higher temperatures. The results confirm the higher density of radiation-induced dislocations in the near surface area of the sample (1.8 * 10{sup 14} m{sup −2}) in comparison with a deeper damage area (1.5 * 10{sup 14} m{sup −2}). Significant decrease of dislocation density was observed after annealing with a concurrent growth of dislocation loops. Transmission electron microscopy analyses show that the dislocation loops are perfect dislocations with the Burgers vectors of b = ½[ 1 1 1].

  6. In situ observations of ion scale current sheet and associated electron heating in Earth's magnetosheath turbulence

    Science.gov (United States)

    Chasapis, Alexandros; Retinò, Alessandro; Sahraoui, Fouad; Greco, Antonella; Vaivads, Andris; Sundkvist, David; Canu, Patrick

    2014-05-01

    Magnetic reconnection occurs in thin current sheets that form in turbulent plasmas. Numerical simulations indicate that turbulent reconnection contributes to the dissipation of magnetic field energy and results in particle heating and non-thermal acceleration. Yet in situ measurements are required to determine its importance as a dissipation mechanism at those scales. The Earth's magnetosheath downstream of the quasi-parallel shock is a turbulent near-Earth environment that offers a privileged environment for such a study. Here we present a study of the properties of thin current sheets by using Cluster data. We studied the distribution of the current sheets as a function of their magnetic shear angle, the PVI index and the electron heating. The properties of the observed current sheets were different for high shear (θ > 90 degrees) and low shear current sheets (θ < 90 degrees). These high-shear current sheets account for about ˜ 20% of the total and have an average thickness comparable to the ion inertial length. Enhancement of electron temperature within these current sheets suggest that they are important for local electron heating and energy dissipation.

  7. Simulating satellite observations of 100 kHz radio waves from relativistic electron beams above thunderclouds

    Directory of Open Access Journals (Sweden)

    M. Füllekrug

    2010-10-01

    Full Text Available Relativistic electron beams above thunderclouds emit 100 kHz radio waves which illuminate the Earth's atmosphere and near-Earth space. This contribution aims to clarify the physical processes which are relevant for the spatial spreading of the radio wave energy below and above the ionosphere and thereby enables simulating satellite observations of 100 kHz radio waves from relativistic electron beams above thunderclouds. The simulation uses the DEMETER satellite which observes 100 kHz radio waves from fifty terrestrial Long Range Aid to Navigation (LORAN transmitters. Their mean luminosity patch in the plasmasphere is a circular area with a radius of 300 km and a power density of 22 μW/Hz as observed at 660km height above the ground. The luminosity patches exhibit a southward displacement of 450 km with respect to the locations of the LORAN transmitters. The displacement is reduced to 150 km when an upward propagation of the radio waves along the geomagnetic field line is assumed. This residual displacement indicates that the radio waves undergo 150 km sub-ionospheric propagation prior to entering a magnetospheric duct and escaping into near-Earth space. The residual displacement at low (L<2.14 and high (L>2.14 geomagnetic latitudes ranges from 100 km to 200 km which suggests that the smaller inclination of the geomagnetic field lines at low latitudes helps to trap the radio waves and to keep them in the magnetospheric duct. Diffuse luminosity areas are observed northward of the magnetic conjugate locations of LORAN transmitters at extremely low geomagnetic latitudes (L<1.36 in Southeast Asia. This result suggests that the propagation along the geomagnetic field lines results in a spatial spreading of the radio wave energy over distances of 1 Mm. The summative assessment of the electric field intensities measured in space show that nadir observations of terrestrial 100 kHz radio waves, e.g., from relativistic electron beams

  8. Real-time observation of graphene oxidation on Pt(111) by low-energy electron microscopy

    Science.gov (United States)

    Johánek, Viktor; Cushing, Gregory W.; Navin, Jason K.; Harrison, Ian

    2016-02-01

    A monolayer of graphene was prepared by thermal decomposition of ethylene gas on Pt(111). The graphene can be readily removed by dosing O2 at pressures in 10- 8 mbar range and surface temperatures (Ts) near 1000 K. Residual gas analysis during the oxygen treatment of graphene layer detected CO to be the only formed product. The oxidation process has been continuously imaged by Low-energy Electron Microscope (LEEM) operated in mirror-electron mode. LEEM observations revealed that the oxidation of graphene on Pt(111) occurs simultaneously at the outer island perimeter and in the interior of the graphene island. Symmetric hexagonal pits were observed to form continuously within graphene sheets, the pits proceeded isotropically. The etch rate was determined to be equal for both modes and independent of the surface environment with the exception of areas above Pt step edges. The pit growth rate at constant oxygen pressure was found to increase exponentially with respect to temperature over the investigated Ts range of 927-1014 K, yielding an apparent activation energy of 479 kJ/mol.

  9. Comparison of F-region electron density observations by satellite radio tomography and incoherent scatter methods

    Science.gov (United States)

    Nygrén, T.; Markkanen, M.; Lehtinen, M.; Tereshchenko, E. D.; Khudukon, B. Z.; Evstafiev, O. V.; Pollari, P.

    1996-12-01

    In November 1995 a campaign of satellite radiotomography supported by the EISCAT incoherent scatter radar and several other instruments was arranged in Scandinavia. A chain of four satellite receivers extending from the north of Norway to the south of Finland was installed approximately along a geomagnetic meridian. The receivers carried out difference Doppler measurements using signals from satellites flying along the chain. The EISCAT UHF radar was simultaneously operational with its beam swinging either in geomagnetic or in geographic meridional plane. With this experimental set-up latitudinal scans of F-region electron density are obtained both from the radar observations and by tomographic inversion of the phase observations given by the difference Doppler experiment. This paper shows the first results of the campaign and compares the electron densities given by the two methods. Acknowledgements. This work has been supported by the UK Particle-Physics and Astronomy Research Council. The assistance of the director and staff of the EISCAT Scientific Association, the staff of the Norsk Polarinstitutt and the director and staff of the Swedish Institute of Space Physics is gratefully acknowledged. In addition the authors would like to thank Professor Evgeny Tereshchenko of the Polar Geophysical Institute in Mumansk, Russia and Dr Tuomo Nygrén of the University of Oulu, Finland for provision of data from EISCAT special program time during the November 1995 campaign. Topical Editor D. Alcaydé thanks E. J. Fremouw and another referee for their help in evaluating this paper.--> Correspondence to: I. K. Walker-->

  10. Observed relation between magnetic field aligned electric fields and downward electron energy fluxes in the vicinity of auroral forms

    International Nuclear Information System (INIS)

    Using electron observations in the vicinity of, and over, auroral forms obtained from three rocket flights, we have found that the net downward electron energy flux generally varied as V2, where V is the magnetic-field-aligned electric potential difference inferred from the peak in the observed energy spectra of precipitating electrons. We show that this relation implies that V is proportional to the net downward number flux of electrons from the magnetosphere to the auroral ionosphere and thus that increases in V and increases in the net downward number flux of electrons are equally responsible for the enhanced electron energy deposition responsible for auroral forms. This also indicates a direct physical connection may exist between V and the net downward electron number flux

  11. Statistics of counter-streaming solar wind suprathermal electrons at solar minimum: STEREO observations

    Directory of Open Access Journals (Sweden)

    B. Lavraud

    2010-01-01

    Full Text Available Previous work has shown that solar wind suprathermal electrons can display a number of features in terms of their anisotropy. Of importance is the occurrence of counter-streaming electron patterns, i.e., with "beams" both parallel and anti-parallel to the local magnetic field, which is believed to shed light on the heliospheric magnetic field topology. In the present study, we use STEREO data to obtain the statistical properties of counter-streaming suprathermal electrons (CSEs in the vicinity of corotating interaction regions (CIRs during the period March–December 2007. Because this period corresponds to a minimum of solar activity, the results are unrelated to the sampling of large-scale coronal mass ejections, which can lead to CSE owing to their closed magnetic field topology. The present study statistically confirms that CSEs are primarily the result of suprathermal electron leakage from the compressed CIR into the upstream regions with the combined occurrence of halo depletion at 90° pitch angle. The occurrence rate of CSE is found to be about 15–20% on average during the period analyzed (depending on the criteria used, but superposed epoch analysis demonstrates that CSEs are preferentially observed both before and after the passage of the stream interface (with peak occurrence rate >35% in the trailing high speed stream, as well as both inside and outside CIRs. The results quantitatively show that CSEs are common in the solar wind during solar minimum, but yet they suggest that such distributions would be much more common if pitch angle scattering were absent. We further argue that (1 the formation of shocks contributes to the occurrence of enhanced counter-streaming sunward-directed fluxes, but does not appear to be a necessary condition, and (2 that the presence of small-scale transients with closed-field topologies likely also contributes to the occurrence of counter-streaming patterns, but only in the slow solar wind prior to

  12. Observations of the scatter-free solar-flare electrons in the energy range 20-1000 keV

    Science.gov (United States)

    Wang, J. R.; Fisk, L. A.; Lin, R. P.

    1971-01-01

    Observations of the scatter-free electron events from solar active region McMath No. 8905 are presented. The measurements were made on Explorer 33 satellite. The data show that more than 80% of the electrons from these events undergo no or little scattering and that these electrons travel only approximately 1.5 a.u. between the sun and the earth. The duration of these events cannot be accounted fully by velocity dispersion alone. It is suggested that these electrons could be continuously injected into interplanetary medium for a time interval of approximately 2 to 3 minutes. Energy spectra of these electrons are discussed.

  13. Cluster observations in the magnetosheath – Part 2: Intensity of the turbulence at electron scales

    Directory of Open Access Journals (Sweden)

    J.-M. Bosqued

    2006-12-01

    Full Text Available The Cluster STAFF Spectral Analyser measures the magnetic and electric power spectral densities (PSD δB2 and δE2 in the magnetosheath between 8 Hz and 4 kHz, i.e. between about the lower hybrid frequency and 10 times the proton plasma frequency. We study about 23 h of data on four different days. We do not consider the whistler waves and the electrostatic pulses (which are not always observed but the underlying permanent fluctuations. Paper 1 (Mangeney et al., 2006 shows why the permanent PSD at a given frequency f depends strongly on the angle ΘBV between the magnetic field B and the flow velocity V: this is observed for the electromagnetic (e.m. fluctuations, δB2 and δEem2, below the electron cyclotron frequency fce, and for the electrostatic (e.s. fluctuations δEes2 at and above fce. This dependence is due to the Doppler shift of fluctuations which have a highly anisotropic distribution of the intensity of the wave vector k spectrum, and have a power law intensity ∝k−ν with ν≃3 to 4. In the present paper, we look for parameters, other than ΘBV, which control the intensity of the fluctuations. At f≃10 Hz, δB2 and δE2em increase when the solar wind dynamic pressure PDYNSW increases. When PDYNSW increases, the magnetosheath PDYNMS∝N V2 also increases, so that the local Doppler shift (k.V increases for a given k. If V increases, a given frequency f will be reached by fluctuations with a smaller k, which are more intense: the variations of δB2 (10 Hz with PDYNSW are only due to the Doppler shift in the spacecraft frame. We show that the e.m. spectrum in the plasma frame has an invariant shape I1D∝Aem (kc/ωpe−ν related to the electron inertial length c/ωpe: the intensity Aem does not depend on PDYN, nor on the electron to proton temperature ratio Te/Tp, nor on the upstream bow shock angle θBN. Then, we show results of 3-D MHD numerical simulations of the magnetosheath plasma, which map the regions where the angle

  14. Direct observation of electron-beam-induced densification and hardening of silica nanoballs by in situ transmission electron microscopy and finite element method simulations

    International Nuclear Information System (INIS)

    We report on the use of in situ transmission electron microscopy techniques and finite element method simulations to study the influence of electron beam irradiation on the deformation behavior and mechanical properties of nanoscale amorphous silica balls. We show that, on the nanometer scale, electron beam irradiation of silica results in athermal densification and simultaneous material hardening. It is demonstrated how the amount of densification can be controlled via the irradiation dose, using specific beam current densities inside a transmission electron microscope. The electron-beam-induced densification is interpreted as the direct reason for the observed hardening effect. Finite element method simulations are used to model the mechanical response of the silica balls, confirming that the intrinsic properties (such as the Young’s modulus) of amorphous silica can be tailored with the electron beam on the nanoscale

  15. Light and electron microscopic observation of the active peripheral regions of the keloids following electron ray irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Yamaguchi, Hiroshi [Kanazawa Medical univ., Uchinada, Ishikawa (Japan)

    1995-03-01

    The present study was designed to investigate changes in the active peripheral region of keloid before and after irradiation with 4 MeV electrons in 25 patients. Thirteen patients were treated with a daily dose of 5 Gy for consecutive 5 days (a total dose of 25 Gy) one week after total keloid excision and the other 12 were treated conservatively with a weekly dose of 4 Gy 3 times (one course) to a total of 3 courses at intervals of 2 months (a total dose of 36 Gy). Specimens were collected from the active peripheral region of keloids before and after electron irradiation for light and electron microscopy. Light microscopy revealed that the number of mast cells was significantly decreased after electron irradiation, corresponding to the clinical improvement. Electron microscopic findings before irradiation included active fibroblasts containing well-developed rough endoplasmic reticulum, nucleus having sharp indentations towards its center, and immature elastic fibers in the extracellular space. After irradiation, electron microscopy revealed that fibroblasts were less active and the rough endoplasmic reticulum and Golgi apparatus appeared to be undeveloped with many vacuoles. In the extracellular space, elastosis was found. The average diameter of the collagen fibrils in the peripheral region of the keloid tissue was increased. Electron irradiation may correct abnormal wound healing of keloids by suppressing the abnormal production of collagen by fibroblasts. In addition, electron irradiation promote the maturation of the existing extracellular matrix, leading to the formation of a mature scar. Furthermore, the low recurrence rate suggests that the effect of the electrons against keloid tissue is persistent. (N.K.).

  16. Direct Observation of Wet Biological Samples by Graphene Liquid Cell Transmission Electron Microscopy.

    Science.gov (United States)

    Park, Jungwon; Park, Hyesung; Ercius, Peter; Pegoraro, Adrian F; Xu, Chen; Kim, Jin Woong; Han, Sang Hoon; Weitz, David A

    2015-07-01

    Recent development of liquid phase transmission electron microscopy (TEM) enables the study of specimens in wet ambient conditions within a liquid cell; however, direct structural observation of biological samples in their native solution using TEM is challenging since low-mass biomaterials embedded in a thick liquid layer of the host cell demonstrate low contrast. Furthermore, the integrity of delicate wet samples is easily compromised during typical sample preparation and TEM imaging. To overcome these limitations, we introduce a graphene liquid cell (GLC) using multilayer graphene sheets to reliably encapsulate and preserve biological samples in a liquid for TEM observation. We achieve nanometer scale spatial resolution with high contrast using low-dose TEM at room temperature, and we use the GLC to directly observe the structure of influenza viruses in their native buffer solution at room temperature. The GLC is further extended to investigate whole cells in wet conditions using TEM. We also demonstrate the potential of the GLC for correlative studies by TEM and fluorescence light microscopy imaging. PMID:26065925

  17. Microstructure of NiTi orthodontic wires observations using transmission electron microscopy

    Directory of Open Access Journals (Sweden)

    J. Ferčec

    2014-10-01

    Full Text Available This work presents the results of the microstructure observation of six different types of NiTi orthodontic wires by using Transmission Electron Microscopy (TEM. Within these analyses the chemical compositions of each wire were observed in different places by applying the EDS detector. Namely, the chemical composition in the orthodontic wires is very important because it shows the dependence between the phase temperatures and mechanical properties. Microstructure observations showed that orthodontic wires consist of nano-sized grains containing precipitates of Ti2Ni and/or TiC. The first precipitated Ti2Ni are rich in Ti, while the precipitated TiC is rich in C. Further investigation showed that there was a difference in average grain size in the NiTi matrix. The sizes of grains in orthodontic wires are in the range from approximately 50 to 160 nm and the sizes of precipitate are in the range from 0,3 μm to 5 μm.

  18. Electron-microscopic observations of the gravity receptor epithelia of normal and spinner juvenile Octopus maya.

    Science.gov (United States)

    Fermin, C D; Colmers, W F; Igarashi, M

    1985-01-01

    Light and electron microscopy of the gravity receptor epithelia (maculae) of statocysts of normal and "spinner" juvenile Octopus maya showed differences between the structures of the hair cells, supporting cells, and afferent neurons of these cephalopods. The maculae of spinner animals were approximately 30% smaller in their surface area and had 40% fewer hair cells. Moreover, the average distance between randomly-chosen hair bundles in scanning electron micrographs of maculae of normal animals was significantly greater (4.33 +/- 6.47 microns) than those of maculae of spinner animals (3.38 +/- 4.90 microns; P less than 0.0001). The sectional area of the supporting cell's microvilli in spinner maculae was larger (0.16 +/- 0.18 microns) than those of normal (0.10 +/- 0.10 micron; P less than 0.0001) O. maya. The morphological differences observed between certain structural components of the maculae of normal and spinner O. maya may be related to the absence and/or malformation of the neuroepithelial suprastructures in spinners. This may have direct or indirect effects to their inability to orient to gravity with these organs. PMID:2861903

  19. Turbulent cross-field transport of non-thermal electrons in coronal loops: theory and observations

    CERN Document Server

    Bian, N; McKinnon, A

    2011-01-01

    A fundamental problem in astrophysics is the interaction between magnetic turbulence and charged particles. It is now possible to use \\emph{Ramaty High Energy Solar Spectroscopic Imager (RHESSI)} observations of hard X-rays (HXR) emitted by electrons to identify the presence of turbulence and to estimate the magnitude of the magnetic field line diffusion coefficient at least in dense coronal flaring loops.} {We discuss the various possible regimes of cross-field transport of non-thermal electrons resulting from broadband magnetic turbulence in coronal loops. The importance of the Kubo number $K$ as a governing parameter is emphasized and results applicable in both the large and small Kubo number limits are collected.} {Generic models, based on concepts and insights developed in the statistical theory of transport, are applied to the coronal loops and to the interpretation of hard X-ray imaging data in solar flares. The role of trapping effects, which become important in the non-linear regime of transport, is ...

  20. The first observation of titanate nanotubes by spherical aberration corrected high-resolution transmission electron microscopy

    Science.gov (United States)

    Miao, L.; Tanemura, S.; Jiang, T.; Tanemura, M.; Yoshida, K.; Tanaka, N.; Xu, G.

    2009-07-01

    Multi-wall titanate nanotubes (MW-TNNTs) with high aspect ratio, large surface area and good uniformity were produced by alkaline hydrothermal treatment of grounded TiO 2 aerogels and further by applying freeze-drying. Not only the crystal phase and diameter, but also morphology of the starting materials impact on the aspect ratio and transformation efficiency of the obtained nanotubes. Other parameters, such as pH value during neutralization process and drying method for the final products, are important to control length and dispersion of MW-TNNTs. By spherical aberration corrected high-resolution transmission-electron-microscopy (Cs-corrected HRTEM) with lateral space resolution of 0.14 nm at 200 kV accelerating voltage and electron energy loss spectrum (EELS), the detailed structural analysis of MW-TNNTs reveals that (1) diameters of inner and outer tubes are about 4-7 nm and 10 nm, respectively, (2) numbers of layers are different from part to part along the longitudinal tube axis, (3) the walls of the tubes have interlayer spacing of 0.70-0.80 nm and the lateral fringes which are vertical to the walls have spacing of 0.32 nm, (4) each layer of MW-TNNT is the nanosheet composed by the arrayed TiO 6 octahedrons, and respective octahedron being slightly strained, and (5) no chirality of MW-TNNT tubular structure is observed.

  1. A Few Observations and Remarks on Time Effectiveness of Interactive Electronic Testing

    Directory of Open Access Journals (Sweden)

    Martin MAGDIN

    2015-04-01

    Full Text Available In the paper, we point out several observations and remarks on time effectiveness of electronic testing, in particular of its new form (interactive tests. A test is often used as an effective didactic tool for evaluating the extent of gained cognitive capabilities. According to authors Rudman (1989 and Wang (2003 it is provable that the relationship towards e-testing depends on the degree of previous experiences with this form of examination. Conducted experiments (not only by these authors show that students using the traditional testing form (putting answers down on a paper are happy to have the opportunity to use a computer for testing. The reason is the fact that they are usually used to a complete explanation of the educational content, frontal examination during the lesson and also in the course of the school year and more limited possibilities to use the Internet for educational purposes. Most of them do not even know about the possibilities of e-learning and electronic evaluation. On the other hand, the group of students who are being tested using the traditional form and at the same time using computers usually prefer the traditional form, while using multimedia tools is more or less normal to them.

  2. Ionospheric total electron content variations observed before earthquakes: Possible physical mechanism and modeling

    CERN Document Server

    Namgaladze, A A; Zakharenkova, I E; Shagimuratov, I I; Martynenko, O V

    2009-01-01

    The GPS derived anomalous TEC disturbances before earthquakes were discovered in the last years using global and regional TEC maps, measurements over individual stations as well as measurements along individual GPS satellite passes. For strong mid-latitudinal earthquakes the seismo-ionospheric anomalies look like local TEC enhancements or decreases located in the vicinity of the forthcoming earthquake epicenter In case of strong low-latitudinal earthquakes there are effects related with the modification of the equatorial F2-region anomaly: deepening or filling of the ionospheric electron density trough over the magnetic equator. We consider that the most probable reason of the NmF2 and TEC disturbances observed before the earthquakes is the vertical drift of the F2-region ionospheric plasma under the influence of the zonal electric field of seismic origin. To check this hypothesis, the model calculations have been carried out with the use of the Upper Atmosphere Model. The electric potential distribution at t...

  3. Scanning Electron Microscope Observation of Carbon Nanotubes with Room Temperature Ionic Liquids: Effect of Their Hydrophilicities.

    Science.gov (United States)

    Hyono, Atsushi; Abe, Shigeaki; Kawai, Koji; Yonezawa, Tetsu

    2015-11-01

    In this study, we succeeded in acquiring scanning electron microscope (SEM) images of carbon nanotube (CNT) derivatives with different surface properties based on an electro-conductive pretreatment using a room temperature ionic liquid (IL). The quality of the obtained SEM images depended on their surface properties and the hydrophilicities of IL used. When the hydrophilicities of both the sample surface and the IL were close, the obtained SEM images had a high resolution. In contrast, SEM imges of samples pretreated with an IL, which had different hydrophilicities from the sample, was observed with low resolution and low quality. This result suggests that the relationship between both hydrophilicities is the dominant factor for this visualization method. PMID:26726681

  4. Observation of single-electron charging effect in NbN submicron bridges

    International Nuclear Information System (INIS)

    Submicron NbN bridges whose thickness, width and length are 10nm, 100nm and 100-300nm respectively, have been fabricated, and their conduction properties and electrical field effect are measured. The samples having resistances larger than ∼100kΩ exhibit nonlinear I-V characteristics with offset voltage of 2mV∼12mV at 4.2K which are obviously similar to those of the single-electron charging effect in small tunnel junction arrays. The field effect modulation of the junction conductance is observed by applying a voltage to a gate electrode which is made over the NbN bridge. These charging effects are thought to arise from the granular structure of NbN bridges. The simulation result using one-dimensional SET junction arrays coincide well with experimental result. (orig.)

  5. Observation of amplification of light by Langmuir waves and its saturation on the electron kinetic timescale

    Science.gov (United States)

    Kirkwood, R. K.; Ping, Y.; Wilks, S. C.; Meezan, N.; Michel, P.; Williams, E.; Clark, D.; Suter, L.; Landen, O.; Fisch, N. J.; Valeo, E. J.; Malkin, V.; Turnbull, D.; Suckewer, S.; Wurtele, J.; Wang, T. L.; Martins, S. F.; Joshi, C.; Yin, L.; Albright, B. J.; Rose, H. A.; Bowers, K. J.

    2011-08-01

    Experiments demonstrate the ~77× amplification of 0.5 to 3.5-ps pulses of seed light by interaction with Langmuir waves in a low density (1.2 × 1019 cm-3) plasma produced by a 1-ns, 230-J, 1054-nm pump beam with 1.2 × 1014 W/cm2 intensity. The waves are strongly damped (kλD = 0.38, Te = 244 eV) and grow over a ~ 1 mm length, similar to what is experienced by scattered light when it interacts with crossing beams as it exits an ignition target. The amplification reduces when the seed intensity increases above ~1 × 1011 W/cm2, indicating that saturation of the plasma waves on the electron kinetic time scale (<0.5 ps) limits the scatter to ~1% of the available pump energy. The observations are in agreement with 2D PIC simulations in this case.

  6. In Situ Transmission Electron Microscopy Observation of Nanostructural Changes in Phase-Change Memory

    KAUST Repository

    Meister, Stefan

    2011-04-26

    Phase-change memory (PCM) has been researched extensively as a promising alternative to flash memory. Important studies have focused on its scalability, switching speed, endurance, and new materials. Still, reliability issues and inconsistent switching in PCM devices motivate the need to further study its fundamental properties. However, many investigations treat PCM cells as black boxes; nanostructural changes inside the devices remain hidden. Here, using in situ transmission electron microscopy, we observe real-time nanostructural changes in lateral Ge2Sb2Te5 (GST) PCM bridges during switching. We find that PCM devices with similar resistances can exhibit distinct threshold switching behaviors due to the different initial distribution of nanocrystalline and amorphous domains, explaining variability of switching behaviors of PCM cells in the literature. Our findings show a direct correlation between nanostructure and switching behavior, providing important guidelines in the design and operation of future PCM devices with improved endurance and lower variability. © 2011 American Chemical Society.

  7. Observing Muon Neutrino to Electron Neutrino Oscillations in the NOνA Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Xin, Tian [Iowa State U.

    2016-01-01

    Neutrino oscillations offers an insight on new physics beyond the Standard Model. The three mixing angles (θ12, θ13 and θ23) and the two mass splittings (Δm2 and Αm2 ) have been measured by different neutrino oscillation experiments. Some other parameters including the mass ordering of different neutrino mass eigenstates and the CP violation phase are still unknown. NOνA is a long-baseline accelerator neutrino experiment, using neutrinos from the NuMI beam at Fermilab. The experiment is equipped with two functionally identical detectors about 810 kilometers apart and 14 mrad off the beam axis. In this configuration, the muon neutrinos from the NuMI beam reach the disappearance maximum in the far detector and a small fraction of that oscillates into electron neutrinos. The sensitivity to the mass ordering and CP viola- tion phase determination is greately enhanced. This thesis presents the νeappearance analysis using the neutrino data collected with the NOνA experiment between February 2014 and May 2015, which corresponds to 3.45 ×1020 protons-on-target (POT). The νe appearance analysis is performed by comparing the observed νe CC-like events to the estimated background at the far detector. The total background is predicted to be 0.95 events with 0.89 originated from beam events and 0.06 from cosmic ray events. The beam background is obtained by extrapolating near detector data through different oscillation channels, while the cosmic ray background is calculated based on out-of-time NuMI trigger data. A total of 6 electron neutrino candidates are observed in the end at the far detector which represents 3.3 σ excess over the predicted background. The NOνA result disfavors inverted mass hierarchy for δcp ϵ [0, 0.6π] at 90% C.L.

  8. Observation of electron weak localization and correlation effects in disordered graphene

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    We have studied the electron transport properties of a disordered graphene sample, where the disorder was intentionally strengthened by Ga+ ion irradiation. The magneto-conductance of the sample exhibits a typical two-dimensional electron weak localization behavior, with electron-electron interaction as the dominant dephasing mechanism. The absence of electron anti-weak localization in the sample implies strong intersublattice and/or intervalley scattering caused by the disorders. The temperature and bias-voltage dependencies of conductance clearly reveal the suppression of conductance at low energies, indicating opening of a Coulomb gap due to electron-electron interaction in the disordered graphene sample.

  9. Scanning tunneling microscope observation of plasmid DNA under electron irradiation at 8-40 eV

    International Nuclear Information System (INIS)

    The structural changes in plasmid DNA adsorbed onto graphite following low-energy electron irradiation were investigated. Using a scanning tunneling microscope (STM), we observed networks or islands of DNA consisting of entangled molecules and compared the shapes of the DNA before and after electron irradiation at 8-40 eV field emitted from the tip of the STM. The shape of the DNA changed depending on the electron energy. Electrons with very low energy, such as 8 or 13 eV, extended the area of a DNA island, while the electrons at 18 or 38 eV degraded it. Both types of changes tend to saturate as the electron dose increases. We also discuss the above results in terms of the chemical reactions, such as strand breaks or molecular dissociation, induced by low-energy electrons

  10. The nature of the observed free-electron-like state in a PTCDA monolayer on Ag(111)

    OpenAIRE

    Dyer, Matthew S.; Persson, Mats

    2009-01-01

    A free-electron like band has recently been observed in a monolayer of PTCDA (3,4,9,10-perylene tetracarboxylic dianhydride) molecules on Ag(111) by two-photon photoemission [Schwalb et al., Phys. Rev. Lett. 101, 146801 (2008)] and scanning tunneling spectroscopy [Temirov et al., Nature 444, 350 (2006)]. Using density functional theory calculations, we find that the observed free-electron like band originates from the Shockley surface state band being dramatically shifted up in energy by the ...

  11. First Observation of Self-Amplified Spontaneous Emission in a Free-Electron Laser at 109 nm Wavelength

    CERN Document Server

    Andruszków, J; Ayvazyan, V T; Baboi, N I; Bakker, R; Balakin, V; Barni, D; Bazhan, A; Bernard, M; Bosotti, A; Bourdon, J C; Brefeld, W; Brinkmann, R; Bühler, S; Carneiro, J P; Castellano, M G; Castro, P; Catani, L; Chel, S; Cho, Y; Choroba, S; Colby, E R; Decking, W; Den Hartog, P; Desmons, M; Dohlus, M; Edwards, D; Edwards, H T; Faatz, B; Feldhaus, J; Ferrario, M; Fitch, M J; Flöttmann, K; Fouaidy, M; Gamp, A; Garvey, Terence; Geitz, M A; Gluskin, E S; Gretchko, V; Hahn, U; Hartung, W H; Hubert, D; Hüning, M; Ischebek, R; Jablonka, M; Joly, J M; Juillard, M; Junquera, T; Jurkiewicz, P; Kabel, A C; Kahl, J; Kaiser, H; Kamps, T; Katelev, V V; Kirchgessner, J L; Körfer, M; Kravchuk, L V; Kreps, G; Krzywinski, J; Lokajczyk, T; Lange, R; Leblond, B; Leenen, M; Lesrel, J; Liepe, M; Liero, A; Limberg, T; Lorenz, R; Lu, H H; Lu, F H; Magne, C; Maslov, M A; Materlik, G; Matheisen, A; Menzel, J; Michelato, P; Möller, W D; Mosnier, A; Müller, U C; Napoly, O; Novokhatskii, A V; Omeich, M; Padamsee, H; Pagani, C; Peters, F; Petersen, B; Pierini, P; Pflüger, J; Piot, P; Phung Ngoc, B; Plucinski, L; Proch, D; Rehlich, K; Reiche, S; Reschke, D; Reyzl, I; Rosenzweig, J; Rossbach, J; Roth, S; Saldin, E L; Sandner, W; Sanok, Z; Schlarb, H; Schmidt, G; Schmüser, P; Schneider, J R; Schneidmiller, E A; Schreiber, H J; Schreiber, S; Schütt, P; Sekutowicz, J; Serafini, L; Sertore, D; Setzer, S; Simrock, S; Sonntag, B F; Sparr, B; Stephan, F; Sytchev, V V; Tazzari, S; Tazzioli, F; Tigner, Maury; Timm, M; Tonutti, M; Trakhtenberg, E; Treusch, R; Trines, D; Verzilov, V A; Vielitz, T; Vogel, V; Von Walter, G; Wanzenberg, R; Weiland, T; Weise, H; Weisend, J G; Wendt, M; Werner, M; White, M M; Will, I; Wolff, S; Yurkov, M V; Zapfe, K; Zhogolev, P; Zhou, F

    2000-01-01

    We present the first observation of Self-Amplified Spontaneous Emission (SASE) in a free-electron laser (FEL) in the Vacuum Ultraviolet regime at 109 nm wavelength (11 eV). The observed free-electron laser gain (approx. 3000) and the radiation characteristics, such as dependency on bunch charge, angular distribution, spectral width and intensity fluctuations all corroborate the existing models for SASE FELs.

  12. Observation of autoionization dynamics and sub-cycle quantum beating in electronic molecular wave packets

    Science.gov (United States)

    Reduzzi, M.; Chu, W.-C.; Feng, C.; Dubrouil, A.; Hummert, J.; Calegari, F.; Frassetto, F.; Poletto, L.; Kornilov, O.; Nisoli, M.; Lin, C.-D.; Sansone, G.

    2016-03-01

    The coherent interaction with ultrashort light pulses is a powerful strategy for monitoring and controlling the dynamics of wave packets in all states of matter. As light presents an oscillation period of a few femtoseconds (T = 2.6 fs in the near infrared spectral range), an external optical field can induce changes in a medium on the sub-cycle timescale, i.e. in a few hundred attoseconds. In this work, we resolve the dynamics of autoionizing states on the femtosecond timescale and observe the sub-cycle evolution of a coherent electronic wave packet in a diatomic molecule, exploiting a tunable ultrashort extreme ultraviolet pulse and a synchronized infrared field. The experimental observations are based on measuring the variations of the extreme ultraviolet radiation transmitted through the molecular gas. The different mechanisms contributing to the wave packet dynamics are investigated through theoretical simulations and a simple three level model. The method is general and can be extended to the investigation of more complex systems.

  13. Observations in equatorial anomaly region of total electron content enhancements and depletions

    Directory of Open Access Journals (Sweden)

    N. Dashora

    2005-10-01

    Full Text Available A GSV 4004A GPS receiver has been operational near the crest of the equatorial anomaly at Udaipur, India for some time now. The receiver provides the line-of-sight total electron content (TEC, the phase and amplitude scintillation index, σφ and S4, respectively. This paper presents the first results on the nighttime TEC depletions associated with the equatorial spread F in the Indian zone. The TEC depletions are found to be very well correlated with the increased S4 index. A new feature of low-latitude TEC is also reported, concerning the observation of isolated and localized TEC enhancements in the nighttime low-latitude ionosphere. The TEC enhancements are not correlated with the S4 index. The TEC enhancements have also been observed along with the TEC depletions. The TEC enhancements have been interpreted as the manifestation of the plasma density enhancements reported by Le et al. (2003.

    Keywords. Ionosphere (Equatorial ionosphere; Ionospheric irregularities

  14. Observation of Shell Structure, Electronic Screening, and Energetic Limiting in Sparks.

    Science.gov (United States)

    Bataller, A; Putterman, S; Pree, S; Koulakis, J

    2016-08-19

    We study the formation of micron-sized spark discharges in high-pressure xenon on the nanosecond time scale. The spark's energy per length is measured through the expansion dynamics of the generated shock wave, and is observed to scale linearly with the spark radius. At the same time, the surface temperature of the spark channel remains constant. Together, these observations allow us to conclude that the spark channel, up to 40  μm in overall radius, is actually an energetically hollow shell about 20  μm thick. Further, the energy per nucleus in the shell is about 15 eV, independent of size and density. To reconcile these findings with the opacity to visible light, we appeal to collective screening processes that dramatically lower the effective ionization potential, allowing a much higher electron density than is otherwise expected. Thus, nanosecond measurements of sparks provide access to the thermodynamics and kinetics of strongly correlated plasmas. PMID:27588861

  15. Competing Two-phase Coexistence in Doped Manganites: Direct Observations by in situ Lorentz Electron Microscopy

    International Nuclear Information System (INIS)

    We examined thin epitaxial films La5/8-yPryCa3/8MnO3 (LPCMO:y=0.275-0.3) in situ by Lorentz transmission electron microscopy (TEM) and other microscopy methods. Clear evidence was obtained for the competing two-phase coexistence of antiferromagnetic charge-ordered (CO) and ferromagnetic (FM) phases that exhibit mesoscale phase separation below the metal-to-insulator transition (MIT) at -164 K. In addition, we observed some regions of mixed CO- and FM-domain contrast attributed earlier to formation of the new CO-FM phase. Using in situ heating/cooling TEM experiments, we interpret this effect as the interfacial wetting phenomenon inherent to the first-order CO-FM phase transition, rather than to the formation of new CO-FM phase. It is evidenced by the partial magnetic melting of CO phase at interfaces with the FM phase, thereby creating charge-disordered spin-glass metastates. For coexisting CO- and FM-domain configurations, we directly refined the relationship between charge-orbital and spin-ordering vectors, consistent with FM moments pinned by (101)-crystal twins in LPCMO films. We also discuss the striking linear dependence observed below MIT for the log-resistance behavior and the CO fraction in LPCMO directly measured by TEM. Such linear dependence does not follow typical percolation equations, suggesting that percolation model needs further revisions for transport description of manganites.

  16. Observation of Exclusive Electron-Positron Production in Hadron-Hadron Collisions

    CERN Document Server

    Abulencia, A; 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; 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; 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; Bölla, G; Bolshov, A; Bortoletto, D; Boudreau, J; Boveia, A; Brau, B; Brigliadori, L; Bromberg, C; Brubaker, E; Budagov, Yu A; Budd, H S; Budd, S; Budroni, S; Burkett, K; Busetto, G; Bussey, P; Byrum, K L; Cabrera, S; Campanelli, M; Campbell, M; Canelli, F; Canepa, A; Carillo, S; Carlsmith, D; Caron, B; Carosi, R; Casarsa, M; Castro, A; Catastini, P; Cauz, D; Cavalli-Sforza, M; Cerri, A; Cerrito, L; Chang, S H; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Chlebana, F; Cho, I; Cho, K; Chokheli, D; Chou, J P; Choudalakis, G; 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; Crescioli, F; Cuenca-Almenar, C; Cuevas-Maestro, J; Culbertson, R; Cully, J C; Cyr, D; Da Ronco, S; D'Auria, S; Davies, T; D'Onofrio, M; Dagenhart, D; De Barbaro, P; De Cecco, S; Deisher, A; De Lentdecker, G; Dell'Orso, Mauro; Delli Paoli, F; Demortier, L; Deng, J; Deninno, M; De Pedis, D; Derwent, P F; Di Giovanni, G P; Dionisi, C; Di Ruzza, B; Dittmann, J R; Di Turo, P; Dorr, C; Donati, S; Donega, M; Dong, P; Donini, J; Dorigo, T; Dube, S; Efron, J; Erbacher, R; Errede, D; Errede, S; Eusebi, R; Fang, H C; Farrington, S; Fedorko, I; Fedorko, W T; Feild, R G; Feindt, M; Fernández, J P; Field, R; Flanagan, G; Foland, A; Forrester, S; Foster, G W; Franklin, M; Freeman, J C; Furic, I; Gallinaro, M; Galyardt, J; García, J E; Garberson, F; Garfinkel, A F; Gay, C; Gerberich, H; Gerdes, D; Giagu, S; Giannetti, P; Gibson, A; Gibson, K; Gimmell, J L; Ginsburg, C; Giokaris, N; Giordani, M; Giromini, P; Giunta, M; Giurgiu, G; Glagolev, V; Glenzinski, D; Gold, M; Goldschmidt, N; Goldstein, J; Gómez, G; Gómez-Ceballos, G; Goncharov, M; González, O; Gorelov, I; Goshaw, A T; Goulianos, K; Gresele, A; Griffiths, M; Grinstein, S; Grosso-Pilcher, C; Group, R C; Grundler, U; Guimarães da Costa, J; Gunay-Unalan, Z; Haber, C; Hahn, K; Hahn, S R; 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; Hartz, M; Hatakeyama, K; Hauser, J; Heijboer, A; Heinemann, B; Heinrich, J; Henderson, C; Herndon, M; Heuser, J; Hidas, D; Hill, C S; Hirschbuehl, D; Höcker, A; Holloway, A; Hou, S; Houlden, M; Hsu, S C; Huffman, B T; Hughes, R E; Husemann, U; Huston, J; Incandela, J R; 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; Jung, J E; Junk, T R; Kamon, T; 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; Kimura, N; Kirsch, L; Klimenko, S; Klute, M; Knuteson, B; Ko, B R; Kondo, K; Kong, D J; Konigsberg, J; Korytov, A; Kotwal, A V; Kovalev, A; Kraan, A C; Kraus, J; Kravchenko, I; Kreps, M; Kroll, J; Krumnack, N; Kruse, M; Krutelyov, V; Kubo, T; Kuhlmann, S E; Kuhr, T; 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, 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; Lister, A; Litvintsev, D O; Liu, T; Lockyer, N S; Loginov, A; Loreti, M; Loverre, P F; 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; Makhoul, K; Mäki, T; Maksimovic, P; Malde, S; Manca, G; Margaroli, F; Marginean, R; Marino, C; Marino, C P; Martin, A; Martin, M; Martin, V; Martínez, M; Maruyama, T; Mastrandrea, P; Masubuchi, T; Matsunaga, H; Mattson, M E; Mazini, R; Mazzanti, P; McFarland, K S; McIntyre, P; McNulty, R; Mehta, A; Mehtälä, P; Menzemer, S; Menzione, A; Merkel, P; Mesropian, C; Messina, A; Miao, T; Miladinovic, N; Miles, J; Miller, R; Mills, C; Milnik, M; Mitra, A; Mitselmakher, G; Miyamoto, A; Moed, S; Moggi, N; Mohr, B; Moore, R; Morello, M; Movilla-Fernández, P A; Mülmenstädt, J; Mukherjee, A; Müller, T; Mumford, R; Murat, P; Nachtman, J; Nagano, A; Naganoma, J; Nakano, I; Napier, A; Necula, V; Neu, C; Neubauer, M S; Nielsen, J; Nigmanov, T; Nodulman, L; Norniella, O; Nurse, E; Oh, S H; Oh, Y D; Oksuzian, I; Okusawa, T; Oldeman, R; Orava, R; Österberg, K; Pagliarone, C; Palencia, E; Papadimitriou, V; Paramonov, A A; Parks, B; Pashapour, S; Patrick, J; Pauletta, G; Paulini, M; Paus, C; Pellett, D E; Penzo, Aldo L; Phillips, T J; Piacentino, G; Piedra, J; Pinera, L; Pinfold, J 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; Ranjan, N; Rappoccio, S; Reisert, B; Rekovic, V; Renton, P B; Rescigno, M; Richter, S; Rimondi, F; Ristori, L; Robson, A; Rodrigo, T; Rogers, E; Rolli, S; Roser, R; Rossi, M; Rossin, R; Ruiz, A; Russ, J; Rusu, V; Saarikko, H; Sabik, S; Safonov, A; Sakumoto, W K; Salamanna, G; Salto, O; Saltzberg, D; Sánchez, 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; Sfyrla, A; Shapiro, M D; Shears, T G; Shepard, P F; Sherman, D; Shimojima, M; Shochet, M; Shon, Y; Shreyber, I; Sidoti, A; Sinervo, P; Sisakian, A; Sjölin, J; Slaughter, A J; Slaunwhite, J; Sliwa, K; Smith, J R; Snider, F D; Snihur, R; Söderberg, M; Soha, A; Somalwar, S; Sorin, V; Spalding, J; Spinella, F; Spreitzer, T; Squillacioti, P; Stanitzki, M; Staveris-Polykalas, A; Saint-Denis, R; Stelzer, B; Stelzer-Chilton, O; Stentz, D; Strologas, J; Stuart, D; Suh, J S; Sukhanov, A; Sun, H; Suzuki, T; Taffard, A; Takashima, R; Takeuchi, Y; Takikawa, K; Tanaka, M; Tanaka, R; Tecchio, M; Teng, P K; Terashi, K; Thom, J; Thompson, A S; Thomson, E; Tipton, P; Tiwari, V; Tkaczyk, S; Toback, D; Tokar, S; Tollefson, K; Tomura, T; Tonelli, D; Torre, S; Torretta, D; Tourneur, S; Trischuk, W; Tsuchiya, R; Tsuno, S; Turini, N; Ukegawa, F; Unverhau, T; Uozumi, S; Usynin, D; Vallecorsa, S; Van Remortel, N; Varganov, A; Vataga, E; Vázquez, F; Velev, G; Veramendi, G; Veszpremi, V; Vidal, R; Vila, I; Vilar, R; Vine, T; Vollrath, I; Volobuev, I P; Volpi, G; Würthwein, F; Wagner, P; Wagner, R G; Wagner, R L; Wagner, J; Wagner, W; Wallny, R; 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; Zhang, X; Zhou, J; Zucchelli, S

    2006-01-01

    We present the first observation of exclusive $e^+e^-$ production in hadron-hadron collisions, using $p\\bar{p}$ collision data at \\mbox{$\\sqrt{s}=1.96$ TeV} taken by the Run II Collider Detector at Fermilab, and corresponding to an integrated luminosity of \\mbox{532 pb$^{-1}$}. We require the absence of any particle signatures in the detector except for an electron and a positron candidate, each with transverse energy {$E_T>5$ GeV} and pseudorapidity {$|\\eta|<2$}. With these criteria, 16 events are observed compared to a background expectation of {$1.9\\pm0.3$} events. These events are consistent in cross section and properties with the QED process \\mbox{$p\\bar{p} \\to p + e^+e^- + \\bar{p}$} through two-photon exchange. The measured cross section is \\mbox{$1.6^{+0.5}_{-0.3}\\mathrm{(stat)}\\pm0.3\\mathrm{(syst)}$ pb}. This agrees with the theoretical prediction of {$1.71 \\pm 0.01$ pb}.

  17. Large-scale drifts observed on electron temperature measurements on JET plasmas

    CERN Document Server

    Gerbaud, Thomas; Alper, Barry; Beausang, Kieran; Beurskens, Marc; Flanagan, Joanne; Kempenaars, Mark; Sirinelli, Antoine; Maslov, Mikhail; Dif-Pradalier, Guilhem; Contributors, JET EFDA

    2012-01-01

    Between 1995 and 2009, electron temperature (Te) measurements of more than 15000 plasmas produced in the Joint European Torus (JET) have been carefully reviewed using the two main diagnostics available over this time period: Michelson interferometer and Thomson scattering systems. Long term stability of JET Te is experimentaly observed by defining the ECE TS ratio as the ratio of central Te measured by Michelson and LIDAR. This paper, based on a careful review of Te measurement from 15 years of JET plasmas, concludes that JET Te exhibits a 15-20% effective uncertainty mostly made of large-scale temporal drifts, and an overall uncertainty of 16-22%. Variations of 18 plasma parameters are checked in another data set, made of a "reference data set" made of ohmic pulses as similar as possible between 1998 and 2009. Time drifts of ECE TS ratios appear to be mostly disconnected from the variations observed on these 18 plasma parameters, except for the very low amplitude variations of the field which are well correl...

  18. Variation of electron temperature and density observed by DEMETER with other satellites and their empirical model

    Science.gov (United States)

    Kakinami, Yoshihiro; Lebreton, Jean-Pierre; Watanabe, Shigeto; Kamogawa, Masashi; Mogi, Toru

    2012-07-01

    Electron density (Ne) and temperature (Te) observed by the DEMETER satellite are validated comparing with various satellites and empirical models of ionosphere/thermosphere such as Hinotori, Dynamic Explorer 2 (DE2), AE-series, and FORMOSAT3/COMSMIC, models based on satellite mass spectrometer and ground-based incoherent scatter data (the MSIS models) and International Reference Ionosphere (IRI). The results show that the Ne and Te of DEMETER are lower and higher that those observed with the other satellites. Such differences are probably originated from the contamination of the Langmuir probe mounted on DEMETER. Since global-scale ionospheric structures such as wave 4 pattern were clearly seen, the relative values of the Ne and Te is expected to be useful to evaluation. However, tiny variations should be carefully discussed for the research. Using Ne and Te measured by the DEMETER satellite, we construct empirical models of Ne and Te for day (1030 local time) and night time (2230 local time) under the geomagnetic quiet condition (Kp trigonometric and linear function fitting. The empirical model derives Ne and Te as functions of day of year, longitude, latitude and solar activity. The results of the empirical models are compared with IRI and discussed.

  19. Whistler mode waves and the electron heat flux in the solar wind: Cluster observations

    CERN Document Server

    Lacombe, Catherine; Matteini, Lorenzo; Santolik, Ondrej; Cornilleau-Wehrlin, Nicole; Mangeney, Andre; de Conchy, Yvonne; Maksimovic, Milan

    2014-01-01

    The nature of the magnetic field fluctuations in the solar wind between the ion and electron scales is still under debate. Using the Cluster/STAFF instrument, we make a survey of the power spectral density and of the polarization of these fluctuations at frequencies $f\\in[1,400]$ Hz, during five years (2001-2005), when Cluster was in the free solar wind. In $\\sim 10\\%$ of the selected data, we observe narrow-band, right-handed, circularly polarized fluctuations, with wave vectors quasi-parallel to the mean magnetic field, superimposed on the spectrum of the permanent background turbulence. We interpret these coherent fluctuations as whistler mode waves. The life time of these waves varies between a few seconds and several hours. Here we present, for the first time, an analysis of long-lived whistler waves, i.e. lasting more than five minutes. We find several necessary (but not sufficient) conditions for the observation of whistler waves, mainly a low level of the background turbulence, a slow wind, a relative...

  20. Experimental observation of spin-dependent electron many-body effects in CdTe

    International Nuclear Information System (INIS)

    In semiconductors, the spin degree of freedom is usually disregarded in the theoretical treatment of electron many-body effects such as band-gap renormalization and screening of the Coulomb enhancement factor. Nevertheless, as was observed experimentally in GaAs, not only the single-particle phase-space filling but also many-body effects are spin sensitive. In this paper, we report on time- and polarization-resolved differential transmission pump-probe measurements in CdTe, which has the same zincblende crystal structure but different material parameters compared to that of GaAs. We show experimentally that at room temperature in CdTe—unlike in GaAs—the pump-induced decrease of transmission due to the band-gap renormalization can even exceed the transmission increase due to the phase-space filling, which enables to measure directly the spin-sensitivity of the band-gap renormalization. We also observed that the influence of the band-gap renormalization is more prominent at low temperatures

  1. Experimental observation of spin-dependent electron many-body effects in CdTe

    Energy Technology Data Exchange (ETDEWEB)

    Horodyská, P.; Němec, P., E-mail: nemec@karlov.mff.cuni.cz; Novotný, T.; Trojánek, F.; Malý, P. [Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 3, 121 16 Prague 2 (Czech Republic)

    2014-08-07

    In semiconductors, the spin degree of freedom is usually disregarded in the theoretical treatment of electron many-body effects such as band-gap renormalization and screening of the Coulomb enhancement factor. Nevertheless, as was observed experimentally in GaAs, not only the single-particle phase-space filling but also many-body effects are spin sensitive. In this paper, we report on time- and polarization-resolved differential transmission pump-probe measurements in CdTe, which has the same zincblende crystal structure but different material parameters compared to that of GaAs. We show experimentally that at room temperature in CdTe—unlike in GaAs—the pump-induced decrease of transmission due to the band-gap renormalization can even exceed the transmission increase due to the phase-space filling, which enables to measure directly the spin-sensitivity of the band-gap renormalization. We also observed that the influence of the band-gap renormalization is more prominent at low temperatures.

  2. Anisotropies of wide-spread solar energetic electron events observed with STEREO and ACE

    International Nuclear Information System (INIS)

    STEREO, in combination with near-Earth observatories as ACE or Wind provides three well separated viewpoints, which are perfectly suited to investigate SEP events and their longitudinal dependences. We collected a list of 21 near-relativistic wide-spread electron events in the period from 2009 to mid 2013, where we request a minimum longitudinal separation angle of 80 degrees between the source active region at the Sun and the magnetic footpoint of one spacecraft observing the event. Anisotropies are investigated to disentangle source and transport mechanisms leading to the wide particle spreads. One favorable mechanism is efficient perpendicular transport in the IP medium leading to vanishing anisotropies at well-separated positions. Another scenario is a large particle spread close to the Sun either due to a coronal shock or due to coronal transport. Here, we expect significant anisotropy at 1 AU due to the wide injection range at the Sun and the afterwards focusing during the outwards propagation. For both of the above scenarios we find events in our sample, which suit the expected observations and even further events, which do not agree with these.

  3. S-wave threshold in electron attachment - observations and cross sections in CCl4 and SF6 at ultralow electron energies

    International Nuclear Information System (INIS)

    The threshold photoionization method was used to study low-energy electron attachment phenomena in and cross sections of CCl4 and SF6 compounds, which have applications in the design of gaseous dielectrics and diffuse discharge opening switches. Measurements were made at electron energies from below threshold to 140 meV at resolutions of 6 and 8 meV. A narrow resolution-limited structure was observed in electron attachment to CCl4 and SF6 at electron energies below 10 meV, which is attributed to the divergence of the attachment cross section in the limit epsilon, l approaches zero. The results are compared with experimental collisional-ionization results, electron-swarm unfolded cross sections, and earlier threshold photoionization data. 34 refs

  4. s-wave threshold in electron attachment - Observations and cross sections in CCl4 and SF6 at ultralow electron energies

    Science.gov (United States)

    Chutjian, A.; Alajajian, S. H.

    1985-01-01

    The threshold photoionization method was used to study low-energy electron attachment phenomena in and cross sections of CCl4 and SF6 compounds, which have applications in the design of gaseous dielectrics and diffuse discharge opening switches. Measurements were made at electron energies from below threshold to 140 meV at resolutions of 6 and 8 meV. A narrow resolution-limited structure was observed in electron attachment to CCl4 and SF6 at electron energies below 10 meV, which is attributed to the divergence of the attachment cross section in the limit epsilon, l approaches zero. The results are compared with experimental collisional-ionization results, electron-swarm unfolded cross sections, and earlier threshold photoionization data.

  5. Inhibition of type III radio emissions due to the interaction between two electron beams: Observations and simulations

    OpenAIRE

    Briand, C; Henri, P.; Hoang, S

    2014-01-01

    We report the peculiar interaction of two type III bursts observed in the solar wind. As electronbeams propagating on the same magnetic field lines cross, a spectacular depletion of the type III radioemission is observed. We combine observations from the WAVES experiment on board the STEREO missiontogether with kinetic plasma simulations to study the extinction of type III radio emission resulting fromthe interaction between two electron beams. The remote observations enable to follow the ele...

  6. Comparison between POES energetic electron precipitation observations and riometer absorptions: Implications for determining true precipitation fluxes

    Science.gov (United States)

    Rodger, Craig J.; Kavanagh, Andrew J.; Clilverd, Mark A.; Marple, Steve R.

    2013-12-01

    electron precipitation (EEP) impacts the chemistry of the middle atmosphere with growing evidence of coupling to surface temperatures at high latitudes. To better understand this link, it is essential to have realistic observations to properly characterize precipitation and which can be incorporated into chemistry-climate models. The Polar-orbiting Operational Environmental Satellite (POES) detectors measure precipitating particles but only integral fluxes and only in a fraction of the bounce loss cone. Ground-based riometers respond to precipitation from the whole bounce loss cone; they measure the cosmic radio noise absorption (CNA), a qualitative proxy with scant direct information on the energy flux of EEP. POES observations should have a direct relationship with ΔCNA and comparing the two will clarify their utility in studies of atmospheric change. We determined ionospheric changes produced by the EEP measured by the POES spacecraft in ~250 overpasses of an imaging riometer in northern Finland. The ΔCNA modeled from the POES data is 10-15 times less than the observed ΔCNA when the >30 keV flux is reported as <106 cm-2 s-1 sr-1. Above this level, there is relatively good agreement between the space-based and ground-based measurements. The discrepancy occurs mostly during periods of low geomagnetic activity, and we contend that weak diffusion is dominating the pitch angle scattering into the bounce loss cone at these times. A correction to the calculation using measurements of the trapped flux considerably reduces the discrepancy and provides further support to our hypothesis that weak diffusion leads to underestimates of the EEP.

  7. The collisional relaxation of electrons in hot flaring plasma and inferring the properties of solar flare accelerated electrons from X-ray observations

    CERN Document Server

    Jeffrey, Natasha; Emslie, Gordon; Bian, Nicolas

    2015-01-01

    X-ray observations are a direct diagnostic of fast electrons produced in solar flares, energized during the energy release process and directed towards the Sun. Since the properties of accelerated electrons can be substantially changed during their transport and interaction with the background plasma, a model must ultimately be applied to X-ray observations in order to understand the mechanism responsible for their acceleration. A cold thick target model is ubiquitously used for this task, since it provides a simple analytic relationship between the accelerated electron spectrum and the emitting electron spectrum in the X-ray source, with the latter quantity readily obtained from X-ray observations. However, such a model is inappropriate for the majority of solar flares in which the electrons propagate in a hot megaKelvin plasma, because it does not take into account the physics of thermalization of fast electrons. The use of a more realistic model, properly accounting for the properties of the background pla...

  8. Monitoring the progress of LHC electron-cloud scrubbing by benchmarking simulations and pressure-rise observations

    CERN Document Server

    Dominguez, Octavio; Arduini, Gianluigi; Metral, Elias; Rumolo, Giovanni; Zimmermann, Frank

    2012-01-01

    Electron bombardment of a surface has been proven to reduce drastically the secondary electron yield of a material. This technique, known as scrubbing, provides a mean to suppress electron cloud build-up and its undesired effects (e.g. vacuum pressure rise, heat load, beam instabilities) in particle accelerators operating with intense beams. Its effectiveness has been already observed at the LHC. In this paper we present the latest observations on the vacuum chamber conditioning and a proposal to optimize the scrubbing process by means of the map formalism.

  9. Magnetospheric Multiscale Satellite Observations of Parallel Electron Acceleration in Magnetic Field Reconnection by Fermi Reflection from Time Domain Structures

    Science.gov (United States)

    Mozer, F. S.; Agapitov, O. A.; Artemyev, A.; Burch, J. L.; Ergun, R. E.; Giles, B. L.; Mourenas, D.; Torbert, R. B.; Phan, T. D.; Vasko, I.

    2016-04-01

    The same time domain structures (TDS) have been observed on two Magnetospheric Multiscale Satellites near Earth's dayside magnetopause. These TDS, traveling away from the X line along the magnetic field at 4000 km /s , accelerated field-aligned ˜5 eV electrons to ˜200 eV by a single Fermi reflection of the electrons by these overtaking barriers. Additionally, the TDS contained both positive and negative potentials, so they were a mixture of electron holes and double layers. They evolve in ˜10 km of space or 7 ms of time and their spatial scale size is 10-20 km, which is much larger than the electron gyroradius (<1 km ) or the electron inertial length (4 km at the observation point, less nearer the X line).

  10. Indium hydroxide to oxide decomposition observed in one nanocrystal during in situ transmission electron microscopy studies

    Energy Technology Data Exchange (ETDEWEB)

    Miehe, Gerhard; Lauterbach, Stefan; Kleebe, Hans-Joachim [Technische Universitaet Darmstadt, Fachbereich Material- und Geowissenschaften, Petersenstr. 23, 64287 Darmstadt (Germany); Gurlo, Aleksander, E-mail: gurlo@materials.tu-darmstadt.de [Technische Universitaet Darmstadt, Fachbereich Material- und Geowissenschaften, Petersenstr. 23, 64287 Darmstadt (Germany)

    2013-02-15

    The high-resolution transmission electron microscopy (HR-TEM) is used to study, in situ, spatially resolved decomposition in individual nanocrystals of metal hydroxides and oxyhydroxides. This case study reports on the decomposition of indium hydroxide (c-In(OH){sub 3}) to bixbyite-type indium oxide (c-In{sub 2}O{sub 3}). The electron beam is focused onto a single cube-shaped In(OH){sub 3} crystal of {l_brace}100{r_brace} morphology with ca. 35 nm edge length and a sequence of HR-TEM images was recorded during electron beam irradiation. The frame-by-frame analysis of video sequences allows for the in situ, time-resolved observation of the shape and orientation of the transformed crystals, which in turn enables the evaluation of the kinetics of c-In{sub 2}O{sub 3} crystallization. Supplementary material (video of the transformation) related to this article can be found online at (10.1016/j.jssc.2012.09.022). After irradiation the shape of the parent cube-shaped crystal is preserved, however, its linear dimension (edge) is reduced by the factor 1.20. The corresponding spotted selected area electron diffraction (SAED) pattern representing zone [001] of c-In(OH){sub 3} is transformed to a diffuse strongly textured ring-like pattern of c-In{sub 2}O{sub 3} that indicates the transformed cube is no longer a single crystal but is disintegrated into individual c-In{sub 2}O{sub 3} domains with the size of about 5-10 nm. The induction time of approximately 15 s is estimated from the time-resolved Fourier transforms. The volume fraction of the transformed phase (c-In{sub 2}O{sub 3}), calculated from the shrinkage of the parent c-In(OH){sub 3} crystal in the recorded HR-TEM images, is used as a measure of the kinetics of c-In{sub 2}O{sub 3} crystallization within the framework of Avrami-Erofeev formalism. The Avrami exponent of {approx}3 is characteristic for a reaction mechanism with fast nucleation at the beginning of the reaction and subsequent three-dimensional growth of

  11. Scanning electron microscopic observation: three-dimensional architecture of the collagen in hepatic fibrosis rats

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao-hong; ZHAO Jing; ZHANG Wei-guang; ZHANG Li-ying; MA Rui-qiong; WANG Li-qin; ZHANG Shu-yong; TIAN Long

    2007-01-01

    Background In the process of hepatic fibrosis, the accumulation of collagen fibers is strongly related to the hepatic function. The aim of this study was to investigate the three-dimensional architecture of the collagen network in the liver of rats with hepatic fibrosis.Methods Healthy adult male Wistar rats (n=32) were randomly divided into a control group (n=16) and a hepatic fibrosis group (n=16). In the control group, the rats were treated with peanut oil while the rats in hepatic fibrosis group were treated for 10 weeks with 60% CCl4 diluted in peanut oil. The quantity of collagen fibers was detected by Western blotting; distribution of the collagen was detected by sirius red staining and polarized microscope; the three-dimensional architecture of collagen in the liver was observed under the scanning electron microscope after fixed tissues were treated with cell-maceration using NaOH. Statistical analysis was performed using the u test.Results The quantity of collagen fibers increased significantly in the hepatic fibrosis group. With the aggravation of hepatic fibrosis, collagen fibers gradually accumulated. They interlaced the reticulation compartment and formed a round or ellipse liver tissue conglomeration like a grape framework that was disparate and wrapped up the normal liver Iobule.The deposition of collagen fibers was obvious in adjacent hepatic parenchyma, especially around the portal tracts.Conclusion Our experiment showed the collagen proliferation and displays clearly the three-dimensional architecture of collagen fibers in rat liver with hepatic fibrosis by scanning electron microscope. It can provide a morphological foundation for the mechanisms of changed haemodynamics and portal hypertension in hepatic fibrosis.

  12. Observation of temporal electric fields emitted by electron beams using a photoconductive antenna

    International Nuclear Information System (INIS)

    Generation of femtosecond electron bunches has been investigated for a light source based on electron bunches and improvement of time resolution in time-resolved measurements. In this study, temporal electric fields from electron bunches using a photoconductive antenna (PCA) with radial microstructures were measured. Radially polarized terahertz (THz) pulses from femtosecond electron bunches were generated by coherent transition radiation (CTR). Photo-induced current depending on THz electric field was measured. (author)

  13. Some characteristics of the parallel electric field acceleration of electrons over discrete auroral arcs as observed from two rocket flights

    International Nuclear Information System (INIS)

    Measurements of energetic electrons from two rocket flights, both crossing discrete auroral arc structures, are examined with respect to low altitude parallel potential drops accelerating electrons of magnetospheric origin downward. In both flights the traversals of magnetic field lines connected to discrete auroral arc structures were associated with inverted V like electron spectral features with the highest peak energies closely related to the brightest auroral forms. The most equatorward inverted V structures, associated with the main arc, seems to mark a boundary south of which the magnetospheric electron population had a higher temperature than north of it. The magnitude and altitude of the potential drop can in principle be obtained by using a model for the acceleration applied to the observed energy and pitch angle distribution of the energetic electrons. A method to study the acceleration mechanism by means of some relations connected to integral flux measurements (eg energy flux and current density of energetic electrons) is suggested. (author)

  14. Observations of electron gyroharmonic waves and the structure of the Io torus. [jupiter 1 spacecraft radio astronomy experiment

    Science.gov (United States)

    Birmingham, T. J.; Alexander, J. K.; Desch, M. D.; Hubbard, R. F.; Pedersen, B. M.

    1980-01-01

    Narrow-banded emissions were observed by the Planetary Radio Astronomy experiment on the Voyager 1 spacecraft as it traversed the Io plasma torus. These waves occur between harmonics of the electron gyrofrequency and are the Jovian analogue of electrostatic emissions observed and theoretically studied for the terrestrial magnetosphere. The observed frequencies always include the component near the upper hybrid resonant frequency, (fuhr) but the distribution of the other observed emissions varies in a systematic way with position in the torus. A refined model of the electron density variation, based on identification of the fuhr line, is included. Spectra of the observed waves are analyzed in terms of the linear instability of an electron distribution function consisting of isotropic cold electrons and hot losscone electrons. The positioning of the observed auxiliary harmonics with respect to fuhr is shown to be an indicator of the cold to hot temperature ratio. It is concluded that this ratio increases systematically by an overall factor of perhaps 4 or 5 between the inner and outer portions of the torus.

  15. Van Allen Probe Observations: Near-Earth injections of Mev Electrons Associated with Intense Substorm Electric Fields

    Science.gov (United States)

    Dai, L.; Wygant, J. R.; Bonnell, J. W.; Cattell, C. A.; Kletzing, C.; Baker, D. N.; Li, X.; Malaspina, D.; Blake, J. B.; Fennell, J.; Claudepierre, S. G.; Takahashi, K.; Funsten, H. O.; Reeves, G. D.; Spence, H. E.; Angelopoulos, V.; Glassmeier, K. H.; Turner, D. L.; Thaller, S. A.; Breneman, A. W.; Kersten, K.; Tang, X.; Tao, X.

    2014-12-01

    With their unique orbit, the Van Allen Probes (RBSP) spacecraft are well suited to investigate near-Earth substorm injections that penetrate into the heart of outer radiation belts. Substorms are generally conceived to inject 10s-100s keV electrons but intense substorm electric fields have been shown capable of injecting ~MeV electrons as well at the geosynchronous altitude. An intriguing question is whether such MeV electron injections can penetrate to lower L shells and directly contribute to the relativistic electron population of the outer radiation belt. In this talk, we present RBSP observations of near-Earth substorm injection of MeV relativistic particles and associated intense dipolarization electric field at L ~5.5. The substorm injection occurred during a moderate storm (DST~-30 to -20) with steady solar wind conditions. RBSP-A observed dispersionless injection of electrons from 10s keV up to 3 MeV in the pre-mid night sector (MLT=22UT). The injection was associated with unusually large (60mV/m) dipolarization electric fields that lasted 1 minute. At about the same time, THEMIS-D observed energy-dispersive injection of electrons at energies as high as at least 720keV at L~6.8 in the pre-dawn sector. Injection of energetic protons (~1MeV) and proton drift echos were observed at RBSP-A as well. RBSP-A observed a broad spectrum of nonlinear electric field structures but no whistler waves at the injection. The properties of the observed dipolarization electric field constrain the acceleration mechanism responsible for the MeV electron injection. We will discuss the implications of these observations on the direct impact of substorms on the outer radiation belt.

  16. Observation of coherent transition radiation using relativistic pico second electron pulse

    International Nuclear Information System (INIS)

    When an electron beams passes through boundaries of two different media with different dielectric constants, it generates radiation. The radiation emitted by the prebunched electron beam becomes coherent if the size of the bunch is smaller than the wavelength. Therefore, transition radiation can be considered as a possible broad band radiation source as well as a probe to the pico second and sub picosecond electron beam profiles. Using 1.2 MeV, 200 mA, macropulse electron beam, transition radiation was generated. The electron gun consists of 2.856 GHz Klystron, thermionic cathode. The emitted electron beam was bunched by passing through an alpha magnet. As a result of the combination, a pico second pulse (1.2 MeV, up to 80 A micropulse) was obtained. Experimental results, comparisons with the theory, and simulated electron beam profiles will be presented

  17. Observation of the avalanche of runaway electrons in air in a strong electric field.

    Science.gov (United States)

    Gurevich, A V; Mesyats, G A; Zybin, K P; Yalandin, M I; Reutova, A G; Shpak, V G; Shunailov, S A

    2012-08-24

    The generation of an avalanche of runaway electrons is demonstrated for the first time in a laboratory experiment. Two flows of runaway electrons are formed sequentially in an extended air discharge gap at the stage of delay of a pulsed breakdown. The first, picosecond, runaway electron flow is emitted in the cathode region where the field is enhanced. Being accelerated in the gap, this beam generates electrons due to impact ionization. These secondary electrons form a delayed avalanche of runaway electrons if the field is strong enough. The properties of the avalanche correspond to the existing notions about the runaway breakdown in air. The measured current of the avalanche exceeds up to an order the current of the initiating electron beam. PMID:23002751

  18. Observation of the Avalanche of Runaway Electrons in Air in a Strong Electric Field

    Science.gov (United States)

    Gurevich, A. V.; Mesyats, G. A.; Zybin, K. P.; Yalandin, M. I.; Reutova, A. G.; Shpak, V. G.; Shunailov, S. A.

    2012-08-01

    The generation of an avalanche of runaway electrons is demonstrated for the first time in a laboratory experiment. Two flows of runaway electrons are formed sequentially in an extended air discharge gap at the stage of delay of a pulsed breakdown. The first, picosecond, runaway electron flow is emitted in the cathode region where the field is enhanced. Being accelerated in the gap, this beam generates electrons due to impact ionization. These secondary electrons form a delayed avalanche of runaway electrons if the field is strong enough. The properties of the avalanche correspond to the existing notions about the runaway breakdown in air. The measured current of the avalanche exceeds up to an order the current of the initiating electron beam.

  19. Low frequency radio observations of bi-directional electron beams in the solar corona

    CERN Document Server

    Carley, Eoin P; Vilmer, Nicole; Gallagher, Peter T

    2015-01-01

    The radio signature of a shock travelling through the solar corona is known as a type II solar radio burst. In rare cases these bursts can exhibit a fine structure known as `herringbones', which are a direct indicator of particle acceleration occurring at the shock front. However, few studies have been performed on herringbones and the details of the underlying particle acceleration processes are unknown. Here, we use an image processing technique known as the Hough transform to statistically analyse the herringbone fine structure in a radio burst at $\\sim$20-90 MHz observed from the Rosse Solar-Terrestrial Observatory on 2011 September 22. We identify 188 individual bursts which are signatures of bi-directional electron beams continuously accelerated to speeds of 0.16$_{-0.10}^{+0.11} c$. This occurs at a shock acceleration site initially at a constant altitude of $\\sim$0.6 R$_{\\odot}$ in the corona, followed by a shift to $\\sim$0.5 R$_{\\odot}$. The anti-sunward beams travel a distance of 170$_{-97}^{+174}$ ...

  20. Ultrastructure of Plant Leaf Cuticles in relation to Sample Preparation as Observed by Transmission Electron Microscopy

    Science.gov (United States)

    Guzmán, Paula; Fernández, Victoria; García, María Luisa; Fernández, Agustín; Gil, Luis

    2014-01-01

    The leaf cuticular ultrastructure of some plant species has been examined by transmission electron microscopy (TEM) in only few studies. Attending to the different cuticle layers and inner structure, plant cuticles have been grouped into six general morphological types. With the aim of critically examining the effect of cuticle isolation and preparation for TEM analysis on cuticular ultrastructure, adaxial leaf cuticles of blue-gum eucalypt, grey poplar, and European pear were assessed, following a membrane science approach. The embedding and staining protocols affected the ultrastructure of the cuticles analysed. The solubility parameter, surface tension, and contact angles with water of pure Spurr's and LR-White resins were within a similar range. Differences were however estimated for resin : solvent mixtures, since Spurr's resin is combined with acetone and LR-White resin is mixed with ethanol. Given the composite hydrophilic and lipophilic nature of plant cuticles, the particular TEM tissue embedding and staining procedures employed may affect sample ultrastructure and the interpretation of the results in physicochemical and biological terms. It is concluded that tissue preparation procedures may be optimised to facilitate the observation of the micro- and nanostructure of cuticular layers and components with different degrees of polarity and hydrophobicity. PMID:24895682

  1. Short unligated sticky ends enable the observation of circularised DNA by atomic force and electron microscopies.

    Science.gov (United States)

    Révet, B; Fourcade, A

    1998-05-01

    A comparative study of the stabilisation of DNA sticky ends by divalent cations was carried out by atomic force microscopy (AFM), electron microscopy and agarose gel electrophoresis. At room temperature, molecules bearing such extremities are immediately oligomerised or circularised by addition of Mg2+or Ca2+. This phenomenon, more clearly detected by AFM, requires the presence of uranyl salt, which stabilises the structures induced by Mg2+or Ca2+. DNA fragments were obtained by restriction enzymes producing sticky ends of 2 or 4 nucleotides (nt) in length with different guanine plus cytosine (GC) contents. The stability of the pairing is high when ends of 4 nt display a 100% GC-content. In that case, 95% of DNA fragments are maintained circular by the divalent cations, although 2 nt GC-sticky ends are sufficient for a stable pairing. DNA fragments with one blunt end and the other sticky appear as dimers in the presence of Mg2+. Dimerisation was analysed by varying the lengths and concentrations of DNA fragments, the base composition of the sticky ends, and also the temperature. Our observation provides a new powerful tool for construction of inverted dimers, and circularisation, ligation analysis or short bases sequence interaction studies. PMID:9547265

  2. Total electron content variations observed at a low latitude GPS station in association to geomagnetic storms

    Science.gov (United States)

    Mendes da Costa, A.; Fonseca Junior, E.; Vilas Boas, J.

    Total electron content (TEC) has been continuously monitored since January 1997, using a GPS dual frequency receiver located at Presidente Prudente (22o 07'S, 51o 22' W). In this paper the enhancements observed in the ionspheric TEC are associated with geomagnetic field variations for six geomagnetic storms that occurred from 1997 to 2000. The events were selected according to the integrity and availability of data. The purpose of this study is to provide a better knowledge of the low-latitude behavior of TEC in association to geomagnetic storms. Quiet-time TEC values were obtained by the average of the five magnetically less disturbed days of the month. These values were subtracted from the TEC hourly averages measured during the period of the magnetic storms. Magnetic field intensity measured on the ground was used for the identification of the storm time variations and the Dst indices were also included as a reference for the latitudes considered. The results showed that moderate geomagnetic storms produce small effects in TEC, intense and super intense (Dst < ~150 nT) geomagnetic storms produce well defined and long lasting TEC enhancements. The super intense storms cause the GPS signals to loose their track and the corresponding TEC values cannot be derived.

  3. Analysis of the electron cloud observations with 25 ns bunch spacing at LHC

    CERN Document Server

    Iadarola, G; Rumolo, G; Arduini, G; Baglin, V; Banfi, D; Claudet, S; Dominguez, O; Esteban Müller, J; Pieloni, T; Shaposhnikova, E; Tavian, L; Zannini, C; Zimmermann, F

    2014-01-01

    Electron Cloud (EC) effects have been identified as a major performance limitation for the Large Hadron Collider (LHC) when operating with the nominal bunch spacing of 25 ns. During the LHC Run 1 (2010 - 2013) the luminosity production mainly used beams with 50 ns spacing, while 25 ns beams were only employed for short periods in 2011 and 2012 for test purposes. On these occasions, observables such as pressure rise, heat load in the cold sections as well as clear signatures on bunch-by-bunch emittance blow up, particle loss and energy loss indicated the presence of an EC in a large portion of the LHC. The analysis of the recorded data, together with EC build up simulations, has led to a significant improvement of our understanding of the EC effect in the different components of the LHC. Studies were carried out both at injection energy (450 GeV) and at top energy (4 TeV) aiming at determining the energy dependence of the EC formation and its impact on the quality of the proton beam.

  4. Non linear electron temperature oscillations on Tore Supra: Experimental observations and modelling by the CRONOS code

    International Nuclear Information System (INIS)

    Full text: The recently discovered plasma regime characterised by stationary electron temperature oscillations (O-regime), has been the object of further experimental investigation and of extensive modelling by the integrated plasma simulation code CRONOS. The experiments include the observation of the O-regime in discharges at exactly zero loop voltage, oscillations trigger by ECCD and the study of the interplay of the O-regime with MHD activity. The possibility of feedback control of the amplitude and frequency of the oscillations using the LH power as an actuator has been investigated. Simulations with the CRONOS code have revealed the nature of the temperature oscillations, which are originated by a non-linear coupling of temperature and current density profiles, of the predator-prey type. It has been shown that oscillating solutions of the coupled heat and current diffusion equations are possible only for a selected class of heat transport models. Therefore, this regime represents a sharp test for transport theories and for integrated plasma simulation codes. (author)

  5. Geneva University: Observation of electron-antineutrino disappearance at Daya Bay

    CERN Document Server

    Université de Genève

    2012-01-01

    GENEVA UNIVERSITY École de physique Département de physique nucléaire et corspusculaire 24, quai Ernest-Ansermet 1211 Genève 4 Tél.: (022) 379 62 73 Fax: (022) 379 69 92 Monday 19 March 2012 COLLOQUE DE PHYSIQUE 5 p.m. - École de Physique, Auditoire Stueckelberg Observation of electron-antineutrino disappearance at Daya Bay  Professor Yifang Wang Institute of High Energy Physics of the Chinese Academy of Sciences Beijing The Daya Bay Reactor Neutrino Experiment, a multinational collaboration operating in the south of China, today reported the first results of its search for the last, most elusive piece of a long-standing puzzle: how is it that neutrinos can appear to vanish as they travel? The surprising answer opens a gateway to a new understanding of fundamental physics and may eventually solve the riddle of why there is far more ordinary matter than antimatter in the Universe today....

  6. Light and electron microscope observations on Nephroselmis gaoae sp. nov. (Prasinophyceae)

    Science.gov (United States)

    Tseng, C. K.; Jiao-Fen, Chen; Zhe-Fu, Zhang; Hui-Qi, Zhang

    1994-09-01

    Nephroselmis gaoae sp. nov. is described on the basis of light and electron microscope observations of cultured material originally collected and isolated from seawater of Jiaozhou Bay, Qingdao, China. The periplasts on the cell body and flagella are covered by five types of scales, two types on the flagella and three on the body. Among these, the morphology and the number of spines of large stellate body scales differ remarkably from those of previously described species of Nephroselmis. Apart from these, the unusual fine structure of the eyespot (stigma) is very characteristic. As in the other species of Nephroselmis, the eyespot lies immediately under the two-membraned chloroplast envelope; unlike the others, however, it is not composed of a number of osmiophilic globules, but consists of about 14 curved rod-shaped osmiophilic bodies arranged loosely and randomly. This feature distinguishes the present new species not only from the other species of Nephroselmis but also from the other motile algal species, the eyespots structure of which had been previously described.

  7. Observation of Lambda H-4 hyperhydrogen by decay-pion spectroscopy in electron scattering

    CERN Document Server

    Esser, A; Schulz, F; Achenbach, P; Gayoso, C Ayerbe; Böhm, R; Borodina, O; Bosnar, D; Bozkurt, V; Debenjak, L; Distler, M O; Friščić, I; Fujii, Y; Gogami, T; Hashimoto, O; Hirose, S; Kanda, H; Kaneta, M; Kim, E; Kohl, Y; Kusaka, J; Margaryan, A; Merkel, H; Mihovilovič, M; Müller, U; Nakamura, S N; Pochodzalla, J; Rappold, C; Reinhold, J; Saito, T R; Lorente, A Sanchez; Majos, S Sánchez; Schlimme, B S; Schoth, M; Sfienti, C; Širca, S; Tang, L; Thiel, M; Tsukada, K; Weber, A; Yoshida, K

    2015-01-01

    At the Mainz Microtron MAMI, the first high-resolution pion spectroscopy from decays of strange systems was performed by electron scattering off a Be-9 target in order to study the ground-state masses of Lambda-hypernuclei. Positively charged kaons were detected by a short-orbit spectrometer with a broad momentum acceptance at zero degree forward angles with respect to the beam, efficiently tagging the production of strangeness in the target nucleus. In coincidence, negatively charged decay-pions were detected by two independent high-resolution spectrometers. About 10^3 pionic weak decays of hyperfragments and hyperons were observed. The pion momentum distribution shows a monochromatic peak at p_pi ~ 133 MeV/c, corresponding to the unique signature for the two-body decay of hyperhydrogen Lambda H-4 -> He-4 + pi-, stopped inside the target. Its binding energy was determined to be B_Lambda = 2.12 +- 0.01 (stat.) +- 0.09 (syst.) MeV with respect to the H-3 + Lambda mass.

  8. COMPARISON OF ELECTRON MICROSCOPIC OBSERVATION BETWEEN EXPANSIVE TYPE AND INFILTRATIVE TYPE OF HEPATOCELLULAR CARCINOMA

    Institute of Scientific and Technical Information of China (English)

    HUANG Zhizhi; SHEN Yanqin; LIANG Yingrui

    1999-01-01

    Objective: To study the ultrastructure and biological characteristics of expansive type of hepatocellular carcinoma (EHCC). Methods:Examination of EHCC and infiltrative type of hepatocellular carcinoma (IHCC) (each 20 cases) by electron microscope (EM) to compare their ultrastructure. Results: The 40 cases were divided into 3 groups: 16 cases of well differentiated EIICC, 4 cases of poorly differentiated EHCC, and 20 cases of poorly differentiated IHCC. The ultrastructure of well differentiated EHCC was similar to the surrounding non-cancer hepatocytes; the characteristics of them were as follows: 1. Cell membrane was developed well and cell border was clear; 2. Round nucleus was of regular shape; nuclear membrane was smooth; 3.Nucleoli were round, regular and bigger than normal;and 4. Plentiful endoplasmic reticulum and mitochondria were well developed. The ultrastructure of poorly differentiated EHCC and IHCC were identical: 1.Membrane was poorly developed; 2. Irregular nuclei were deeply indented or iobulated and many pseudoinclusions were seen; 3. Majority of the nucleoli were big, sponges or ring-formed; 4. Organelles were plentiful or scanty and tended to be degenerated.Conclusion: Most of the EHCC were mature by EM observation; this explained the EHCC's slow growth pattern, but some still had invasive potential.

  9. Observation of free electron cyclotron resonance in NaAlSi3O8 feldspar: Direct determination of the effective electron mass

    DEFF Research Database (Denmark)

    Poolton, N.R.J.; Nicholis, J.E.; Bøtter-Jensen, L.; Smith, G.M.; Riedi, P.C.

    2001-01-01

    We report the first observation of cyclotron resonances in alkali feldspars, using highly sensitive optical detection methods. In Na-feldspar (NaAlSi3O8). a near isotropic effective electron mass value of m(c)(*) = 0.79m, has been determined. The significance of this measurement in terms of the...

  10. Further observations on the operation of a GaAs polarized electron source

    Energy Technology Data Exchange (ETDEWEB)

    Guo, X.Q.; Crowe, D.M.; Lubell, M.S.; Tang, F.C.; Vasilakis, A. (Department of Physics, The City College of CUNY, New York, New York 10031 (USA)); Eminyan, M. (Laboratoire de Physique Atomique, Tour 24, Universite Paris VII, F-75251 Paris (France)); Slevin, J. (Department of Experimental Physics, St. Patrick' s College, Maynooth, County Kildare (Ireland))

    1990-07-01

    We report on several important features of GaAs polarized electron source operation. Specifically we point out the beneficial effect on crystal lifetime produced by the constant low-level application of cesium from a dispenser embedded in an extraction anode. Using our experience in low-energy polarized electron-atom scattering as a reference, we also discuss the importance of frequent energy calibrations of GaAs electron beams for high-resolution investigations.

  11. Further observations on the operation of a GaAs polarized electron source

    International Nuclear Information System (INIS)

    We report on several important features of GaAs polarized electron source operation. Specifically we point out the beneficial effect on crystal lifetime produced by the constant low-level application of cesium from a dispenser embedded in an extraction anode. Using our experience in low-energy polarized electron-atom scattering as a reference, we also discuss the importance of frequent energy calibrations of GaAs electron beams for high-resolution investigations

  12. Observation of conformers with laser electronic spectroscopy in supersonic molecular beams

    Science.gov (United States)

    Philis, John G.; Kosmidis, Constantine E.; Tsekeris, Pericles

    1998-07-01

    We discuss the ability and effectiveness of electronic spectroscopy to reveal rotational isomerism by presenting some examples of the S1 implied by S0 electronic spectra of non-rigid molecules. One or two photon electronic spectra have multiple features when the molecule has more than one conformational preference. Torsional bands showing up in the spectrum complicate the assignment of conformers. Hole burning experiments give definite conclusions on the existence of rotational isomerism and an example from the literature is given.

  13. Spatially-resolved Energetic Electron Properties for the 21 May 2004 Flare from Radio Observations and 3D Simulations

    CERN Document Server

    Kuznetsov, Alexey

    2014-01-01

    We investigate in detail the 21 May 2004 flare using simultaneous observations of the Nobeyama Radioheliograph, Nobeyama Radiopolarimeters, Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and Solar and Heliospheric Observatory (SOHO). The flare images in different spectral ranges reveal the presence of a well-defined single flaring loop in this event. We have simulated the gyrosynchrotron microwave emission using the recently developed interactive IDL tool GX Simulator. By comparing the simulation results with the observations, we have deduced the spatial and spectral properties of the non-thermal electron distribution. The microwave emission has been found to be produced by the high-energy electrons ($>100$ keV) with a relatively hard spectrum ($\\delta\\simeq 2$); the electrons were strongly concentrated near the loop top. At the same time, the number of high-energy electrons near the footpoints was too low to be detected in the RHESSI images and spatially unresolved data. The SOHO Extreme-ultra...

  14. Observation of Electron Clouds in the ANKA Undulator by Means of the Microwave Transmission Method

    CERN Document Server

    Sonnad, K G; Casalbuoni, S; Huttel, E; Mashkina, E M; Saez de Jauregui, D; Smale, N J; Caspers, Friedhelm; Muller, A S; Sonnad, K G; Weigel, R

    2010-01-01

    A superconducting undulator is installed in the ANKA electron storage ring. Electron clouds could potentially contribute to the heat load of this device. A microwave transmission type electron cloud diagnostic has been installed for the undulator section of the ANKA machine. We present the system layout with particular emphasis on the electron machine aspects. Hardware transfer function results and e-cloud data for different machine settings are discussed. Special care has been taken for front end filter design both on the microwave injection and pick-up side.

  15. Direct observation of Space Charge Dynamics by picosecond Low Energy Electron Scattering

    OpenAIRE

    Cirelli, C; Hengsberger, M.; Dolocan, A; Over, H.; Osterwalder, J; Greber, T.

    2008-01-01

    The electric field governing the dynamics of space charge produced by high intensity femtosecond laser pulses focused on a copper surface is investigated by time-resolved low-energy-electron-scattering. The pump-probe experiment has a measured temporal resolution of better than 35 ps at 55 eV probe electron energy. The probe electron acceleration due to space charge is reproduced within a 3-dimensional non-relativistic model, which determines an effective number of electrons in the space char...

  16. Cross Sections for Electron Impact Excitation of Ions Relevant to Planetary Atmospheres Observation

    Science.gov (United States)

    Tayal, Swaraj S.

    1998-01-01

    The goal of this research grant was to calculate accurate oscillator strengths and electron collisional excitation strengths for inelastic transitions in atomic species of relevance to Planetary Atmospheres. Large scale configuration-interaction atomic structure calculations have been performed to obtain oscillator strengths and transition probabilities for transitions among the fine-structure levels and R-matrix method has been used in the calculations of electron-ion collision cross sections of C II, S I, S II, S III, and Ar II. A number of strong features due to ions of sulfur have been detected in the spectra of Jupiter satellite Io. The electron excitation cross sections for the C II and S II transitions are studied in collaboration with the experimental atomic physics group at the Jet Propulsion Laboratory. There is excellent agreement between experiment and theory which provide an accurate and broad-base test of the ability of theoretical methods used in the calculation of atomic processes. Specifically, research problems have been investigated for: electron impact excitation cross sections of C II: electron impact excitation cross sections of S III; energy levels and oscillator strengths for transitions in S III; collision strengths for electron collisional excitation of S II; electron impact excitation of inelastic transitions in Ar II; oscillator strengths of fine-structure transitions in neutral sulfur; cross sections for inelastic scattering of electrons from atomic nitrogen; and excitation of atomic ions by electron impact.

  17. Benchmarking Electron-Cloud Build-Up and Heat-Load Simulations against Large-Hadron-Collider Observations

    CERN Document Server

    Dominguez, O; Maury, H; Rumolo, G; Zimmermann, F

    2011-01-01

    After reviewing the basic features of electron clouds in particle accelerators, the pertinent vacuum-chamber surface properties, and the electron-cloud simulation tools in use at CERN, we report recent observations of electron-cloud phenomena at the Large Hadron Collider (LHC) and ongoing attempts to benchmark the measured LHC vacuum pressure increases and heat loads against electron-cloud build-up simulations aimed at determining the actual surface parameters and at monitoring the so-called scrubbing process. Finally, some other electron-cloud studies related to the LHC are mentioned, and future study plans are described. Presented at MulCoPim2011, Valencia, Spain, 21-23 September 2011.

  18. Observation of hole accumulation in Ge/Si core/shell nanowires using off-axis electron holography.

    Science.gov (United States)

    Li, Luying; Smith, David J; Dailey, Eric; Madras, Prashanth; Drucker, Jeff; McCartney, Martha R

    2011-02-01

    Hole accumulation in Ge/Si core/shell nanowires (NWs) has been observed and quantified using off-axis electron holography and other electron microscopy techniques. The epitaxial [110]-oriented Ge/Si core/shell NWs were grown on Si (111) substrates by chemical vapor deposition through the vapor-liquid-solid growth mechanism. High-angle annular-dark-field scanning transmission electron microscopy images and off-axis electron holograms were obtained from specific NWs. The excess phase shifts measured by electron holography across the NWs indicated the presence of holes inside the Ge cores. Calculations based on a simplified coaxial cylindrical model gave hole densities of (0.4 ± 0.2) /nm(3) in the core regions. PMID:21244011

  19. Experimental Observation of a 100-Femtosecond Single Electron Bunch in Photocathode Linac with Longitudinal Emittance Compensation Technique

    CERN Document Server

    Yang Jin Feng; Kondoh, Takafumi; Kozawa, Takahiro; Tagawa, Seiichi; Yoshida, Yoichi

    2005-01-01

    The realization of a 100fs electron pulse is important for the studies of ultrafast physical/chemical phenoena with a pump-probe method. We have developed a photocathode linear accelerator (linac) to generate such electron pulse with a magnetic pulse compressor. The nonlinear effect of the magnetic fields in the pulse compression was compensated carefully by optimizing the magnetic fields and the booster linac RF phase. A 105fs(rms) electron bunch with electron charge of 0.1nC was observed experimentally by using a femtosecond streak camera. The beam energy was 35MeV, and the normalized teraservers emittance was lower than 3mm-mrad. The dependences of the pulse length and the emittance on the electron charge were also measured and compared with the theoretical calculations.

  20. Experimental simulation of satellite observations of 100 kHz radio waves from relativistic electron beams above thunderclouds

    OpenAIRE

    M. Füllekrug; Hanuise, C.; M. Parrot

    2011-01-01

    Relativistic electron beams above thunderclouds emit 100 kHz radio waves which illuminate the Earth's atmosphere and near-Earth space. This contribution aims to clarify the physical processes which are relevant for the spatial spreading of the radio wave energy below and above the ionosphere and thereby enables an experimental simulation of satellite observations of 100 kHz radio waves from relativistic electron beams above thunderclouds. The simulation uses the DEMETER satellite which...

  1. Direct observation of children’s preferences and activity levels during interactive and on-line electronic games

    OpenAIRE

    McKenzie, TL; Sit, CHP; Lam, JWK

    2010-01-01

    BACKGROUND: Interactive electronic games have recently been popularized and are believed to help promote children's physical activity (PA). The purpose of the study was to examine preferences and PA levels during interactive and online electronic games among overweight and nonoverweight boys and girls. METHODS: Using a modification of the SOFIT, we systematically observed 70 Hong Kong Chinese children (35 boys, 35 girls; 50 nonoverweight, 20 overweight), age 9 to 12 years, during 2 60-minute ...

  2. Observation of Hot Electrons in Surface-Wave Plasmas Excited by Surface Plasmon Polaritons

    Institute of Scientific and Technical Information of China (English)

    HU Ye-Lin; CHEN Zhao-Quan; LIU Ming-Hai; HONG Ling-Li; LI Ping; ZHENG Xiao-Liang; XIA Guang-Qing; HU Xi-Wei

    2011-01-01

    The electron energy distribution functions (EEDFs) are studied in the planar-type surface-wave plasma (SWP)caused by resonant excitation of surface plasmon polaritons (SPPs) using a single cylindrical probe.Sustained plasma characteristics can be considered as a bi-Maxwellian EEDF,which correspond to a superposition of the bulk low-temperature electron and the high-energy electron beam-like part.The beam component energy is pronounced at about 10eV but the bulk part is lower than 3.5eV.The hot electrons included in the proposed plasmas play a significant role in plasma heating and further affect the discharge chemistry.During the past several years,in the fabrication ofamorphous or crystalline silicon films,diamond film synthesis and carbon nanotube growth,the large-area overdense plasma source has been useful.In electronic device fabrication techniques such as etching,ashing or plasma chemical vapor deposition,overdense electrons and radicals are required,especially hot electrons.Among the various plasma devices,the planar-type surface-wave plasma (SWP) source is an advanced plasma source,which is a type of promising plasma source satisfying the above rigorous requirements for large-area plasma processing.%The electron energy distribution functions (EEDFs) are studied in the planar-type surface-wave plasma (SWP) caused by resonant excitation of surface plasmon polaritons (SPPs) using a single cylindrical probe. Sustained plasma characteristics can be considered as a bi-Maxwellian EEDF, which correspond to a superposition of the bulk low-temperature electron and the high-energy electron beam-like part. The beam component energy is pronounced at about 10 eV but the bulk part is lower than 3.5 eV. The hot electrons included in the proposed plasmas play a significant role in plasma heating and further affect the discharge chemistry.

  3. Kinetic observation of rapid electron transfer between thymine and thymidine anion radicals and caffeic acid: a pulse radiolysis study

    International Nuclear Information System (INIS)

    Rapid electron transfer from thymine or thymidine anion radicals to caffeic acid with rate constant of 1 x 109 M-1s-1 was observed by pulse radiolysis, leading to the formation of anion radicals of caffeic acid which is characterized with absorption maximum at 360nm. Caffeic acid has a higher one-electron reduction potential than the target molecule (thymine or thymidine) and acts as a electrophilic protector which prevent the target anion radical from its irreversible protonation at C6 leading to its 5-yl radical via fast electron transfer. The kinetic demonstrations have provided dynamic evidence of charge transfer protection mechanism. (author)

  4. Observations of charge-ordered and magnetic domains in LuFe2O4 using transmission electron microscopy

    Science.gov (United States)

    Maruyama, T.; Murakami, Y.; Shindo, D.; Abe, N.; Arima, T.

    2012-08-01

    Both charge-ordered and magnetic domains produced in LuFe2O4, which have attracted significant attention due to the interplay of electronic and magnetic degrees of freedom, have been studied using transmission electron microscopy techniques. Dark-field images, obtained using a weak satellite reflection, revealed the nanometer-scale charge-ordered domains, which were observed over a wide temperature range below TCO (critical temperature of charge ordering; ˜310 K). Electron holography demonstrated an aspect of the long-range magnetic order wherein the magnetic flux lines were completely parallel to the c axis of LuFe2O4, in a specimen cooled to 17 K under an applied magnetic field. In contrast, there was no appreciable magnetic signal observed in a specimen cooled in a negligible magnetic field. These observations provide useful information for further understanding of the complex magnetic phase transitions in this compound.

  5. Direct observations of the MOF (UiO-66) structure by transmission electron microscopy

    KAUST Repository

    Zhu, Liangkui

    2013-01-01

    As a demonstration of ab initio structure characterizations of nano metal organic framework (MOF) crystals by high resolution transmission electron microscopy (HRTEM) and electron diffraction tomography methods, a Zr-MOF (UiO-66) structure was determined and further confirmed by Rietveld refinements of powder X-ray diffraction. HRTEM gave direct imaging of the channels. © 2013 The Royal Society of Chemistry.

  6. Angle-differential observation of plasmon electrons in the double-differential cross-section spectra of fast-ion-induced electron ejection from C60

    Science.gov (United States)

    Kelkar, A. H.; Gulyás, L.; Tribedi, Lokesh C.

    2015-11-01

    We report on the measurement of double-differential distribution of soft electron emission from C60 fullerene, induced by a fast-moving Coulomb field of 76 MeV energy bare fluorine ions. A broad "plasmon-electron" peak, riding on the Coulomb-ionization continuum, is observed due to the deexcitation of the giant dipole plasmon resonance state in C60. The angular distribution of the plasmon electrons goes through a dip around 90°, which is contrary to that observed in ion-atom collisions measured in situ, indicating the alignment of the induced dipole moment along the projectile beam direction. A model based on the photoelectron angular distribution which is modified due to the ion-induced postcollisional interaction provides an excellent agreement with the observed asymmetric distribution. The distribution smoothly changes from a dip at 90° to a peak with the variation of ejected electron energy indicating transition from a collective plasmon behavior of the whole system to a single ion-atom interaction. The single-differential cross section was also derived, which preserves the signature of the collective excitation.

  7. The nature of the observed free-electron-like state in a PTCDA monolayer on Ag(111)

    Energy Technology Data Exchange (ETDEWEB)

    Dyer, Matthew S; Persson, Mats, E-mail: msd30@liv.ac.u [Surface Science Research Centre, University of Liverpool, Liverpool L69 3BX (United Kingdom)

    2010-06-15

    A free-electron-like band has recently been observed in a monolayer of 3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA) molecules on Ag(111) by two-photon photoemission (Schwalb et al 2008 Phys. Rev. Lett. 101 146801) and scanning tunneling spectroscopy (Temirov et al 2006 Nature 444 350). Using density functional theory calculations, we find that the observed free-electron-like band originates from the Shockley surface state band being dramatically shifted up in energy by the interaction with the adsorbed molecules, while it also acquires a substantial admixture with a molecular band.

  8. The nature of the observed free-electron-like state in a PTCDA monolayer on Ag(111)

    International Nuclear Information System (INIS)

    A free-electron-like band has recently been observed in a monolayer of 3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA) molecules on Ag(111) by two-photon photoemission (Schwalb et al 2008 Phys. Rev. Lett. 101 146801) and scanning tunneling spectroscopy (Temirov et al 2006 Nature 444 350). Using density functional theory calculations, we find that the observed free-electron-like band originates from the Shockley surface state band being dramatically shifted up in energy by the interaction with the adsorbed molecules, while it also acquires a substantial admixture with a molecular band.

  9. Electron impact ionization rates for interstellar neutral H and He atoms near interplanetary shocks: Ulysses observations

    Science.gov (United States)

    Feldman, W. C.; Phillips, J. L.; Gosling, J. T.; Isenberg, P. A.

    1995-01-01

    During average solar wind flow conditions at 1 AU, ionization rates of interstellar neutrals that penetrate into the inner heliosphere are dominated by charge exchange with solar wind protons for H atoms, and by photoionization for He atoms. During occurrences of strong, coronal mass ejection (CME)-driven interplanetary shock waves near 1 AU, electron impact ionization can make substantial, if not dominating, contributions to interstellar neutral ionization rates in the regions downstream of the shocks. However, electron impact ionization is expected to be relatively less important with increasing heliocentric distance because of the decrease in electron temperature. Ulysses encountered many CME-driven shocks during its journey to and beyond Jupiter, and in addition, encountered a number of strong corotating interaction region (CIR) shocks. These shocks generally occur only beyond approximately 2 AU. Many of the CIR shocks were very strong rivalling the Earth's bow shock in electron heating. We have compared electron impact ionization rates calculated from electron velocity distributions measured downstream from CIR shocks using the Ulysses SWOOPS experiment to charge-exchange rates calculated from measured proton number fluxes and the photoionization rate estimated from an assumed solar photon spectrum typical of solar maximum conditions. We find that, although normally the ratio of electron-impact ionization rates to charge-exchange (for H) and to photoionization (for He) rates amounts to only about one and a few tens of percent, respectively, downstream of some of the stronger CIR shocks they amount to more than 10% and greater than 100%, respectively.

  10. Validation of ionospheric electron density profiles inferred from GPS occultation observations of the GPS/MET experiment

    Science.gov (United States)

    Kawakami, Todd Mori

    In April of 1995, the launch of the GPS Meteorology Experiment (GPS/MET) onboard the Orbview-1 satellite, formerly known as Microlab-1, provided the first technology demonstration of active limb sounding of the Earth's atmosphere with a low Earth orbiting spacecraft utilizing the signals transmitted by the satellites of the Global Positioning System (GPS). Though the experiment's primary mission was to probe the troposphere and stratosphere, GPS/MET was also capable of making radio occultation observations of the ionosphere. The application of the GPS occultation technique to the upper atmosphere created a unique opportunity to conduct ionospheric research with an unprecedented global distribution of observations. For operational support requirements, the Abel transform could be employed to invert the horizontal TEC profiles computed from the L1 and L2 phase measurements observed by GPS/MET into electron density profiles versus altitude in near real time. The usefulness of the method depends on how effectively the TEC limb profiles can be transformed into vertical electron density profiles. An assessment of GPS/MET's ability to determine electron density profiles needs to be examined to validate the significance of the GPS occultation method as a new and complementary ionospheric research tool to enhance the observational databases and improve space weather modeling and forecasting. To that end, simulations of the occultation observations and their inversions have been conducted to test the Abel transform algorithm and to provide qualitative information about the type and range of errors that might be experienced during the processing of real data. Comparisons of the electron density profiles inferred from real GPS/MET observations are then compared with coincident in situ measurements from the satellites of Defense Meteorological Satellite Program (DMSP) and ground-based remote sensing from digisonde and incoherent scatter radar facilities. The principal focus of

  11. Observation and spectroscopy of a two-electron Wigner molecule in an ultraclean carbon nanotube

    DEFF Research Database (Denmark)

    Pecker, S.; Kuemmeth, Ferdinand; Secchi, A.; Rontani, M.; Ralph, D.C.; McEuen, P.L.; IIani, S.

    2013-01-01

    Two electrons on a string form a simple model system where Coulomb interactions are expected to play an interesting role. In the presence of strong interactions, these electrons are predicted to form a Wigner molecule, separating to the ends of the string. This spatial structure is believed to be...... two interacting carriers, electrons or holes, and identify seven low-energy states characterized by their exchange symmetries. The formation of a Wigner molecule is evident from a tenfold quenching of the fundamental excitation energy as compared with the non-interacting value. Our ability to tune the...

  12. Direct observation of space charge dynamics by picosecond low-energy electron scattering

    OpenAIRE

    Cirelli, C.; Hengsberger, M.; Dolocan, A.; Over, H.; Osterwalder, J.; Greber, T.

    2009-01-01

    The transient electric field governing the dynamics of space charge is investigated by time- and energy-resolved low-energy electron scattering. The space charge above a copper target is produced by high-intensity femtosecond laser pulses. The pump-probe experiment has a measured temporal resolution of better than 35 ps at 55 eV probe electron energy. The probe electron acceleration due to space charge is reproduced within a 3-dimensional non-relativistic model, which determines an effective ...

  13. Coherent Resonances Observed in the Dissociative Electron Attachments to Carbon Monoxide

    CERN Document Server

    Wang, Xu-Dong; Luo, Yi; Tian, Shan Xi

    2015-01-01

    Succeeding our previous finding about coherent interference of the resonant states of CO^- formed by the low-energy electron attachment [Phys. Rev. A 88, 012708 (2013)], here we provide more evidences of the coherent interference, in particular, we find the state configuration change in the interference with the increase of electron attachment energy by measuring the completely backward distributions of the O^- fragment ion of the temporary CO^- in an energy range 11.3-12.6 eV. Therefore, different pure states, namely, coherent resonances, can be formed when the close-lying resonant states are coherently superposed by a broad-band electron pulse.

  14. Nambu--Goldstone Dark Matter and Cosmic Ray Electron and Positron Excess

    Energy Technology Data Exchange (ETDEWEB)

    Ibe, Masahiro; /SLAC; Nakayama, Yu; /UC, Berkeley /LBL, Berkeley; Murayama, Hitoshi; /UC, Berkeley /LBL, Berkeley /Tokyo U., IPMU; Yanagida, Tsutomu T.; /Tokyo U. /Tokyo U., IPMU

    2009-06-19

    We propose a model of dark matter identified with a pseudo-Nambu-Goldstone boson in the dynamical supersymmetry breaking sector in a gauge mediation scenario. The dark matter particles annihilate via a below-threshold narrow resonance into a pair of R-axions each of which subsequently decays into a pair of light leptons. The Breit-Wigner enhancement explains the excess electron and positron fluxes reported in the recent cosmic ray experiments PAMELA, ATIC and PPB-BETS without postulating an overdensity in halo, and the limit on anti-proton flux from PAMELA is naturally evaded.

  15. Electron-optical observations of ordered FeNi in the Estherville meteorite

    Science.gov (United States)

    Mehta, S.; Novotny, P. M.; Williams, D. B.; Goldstein, J. I.

    1980-01-01

    Electron optical studies of the ordered FeNi (taenite) phase in the Estherville meteorite are reported. A thin section of the meteorite containing a large area of continuous anisotropic taenite was studied by crossed polar reflected light microscopy, and electron probe microanalysis, transmission electron microscopy, scanning transmission electron microscopy and X-ray energy dispersive spectrometry. Results reveal the presence of preferentially ion-etched regions of clear taenite corresponding to single crystals, with superlattice reflections in the fundamental FeNi reciprocal lattice arising from long-range ordering. The presence of antiphase domain boundaries within the regions also confirms the presence of ordering. It is thus proposed that clear taenite in the Estherville meteorite contains regions of ordered FeNi phase in a disordered gamma-phase matrix.

  16. Direct observation of space charge dynamics by picosecond low-energy electron scattering

    Science.gov (United States)

    Cirelli, C.; Hengsberger, M.; Dolocan, A.; Over, H.; Osterwalder, J.; Greber, T.

    2009-01-01

    The transient electric field governing the dynamics of space charge is investigated by time- and energy-resolved low-energy electron scattering. The space charge above a copper target is produced by high-intensity femtosecond laser pulses. The pump-probe experiment has a measured temporal resolution of better than 35 ps at 55 eV probe electron energy. The probe electron acceleration due to space charge is reproduced within a 3-dimensional non-relativistic model, which determines an effective number of electrons in the space charge cloud and its initial diameter. Comparison of the simulations with the experiments indicates a Coulomb explosion, which is consistent with transients in the order of 1 ns, the terminal kinetic energy of the cloud and the thermoemission currents predicted by the Richardson-Dushman formula.

  17. Investigation of the aluminium-aluminium oxide reversible transformation as observed by hot stage electron microscopy.

    Science.gov (United States)

    Grove, C. A.; Judd, G.; Ansell, G. S.

    1972-01-01

    Thin foils of high purity aluminium and an Al-Al2O3 SAP type of alloy were oxidised in a specially designed hot stage specimen chamber in an electron microscope. Below 450 C, amorphous aluminium oxide formed on the foil surface and was first detectable at foil edges, holes, and pits. Islands of aluminium then nucleated in this amorphous oxide. The aluminium islands displayed either a lateral growth with eventual coalescence with other islands, or a reoxidation process which caused the islands to disappear. The aluminium island formation was determined to be related to the presence of the electron beam. A mechanism based upon electron charging due to the electron beam was proposed to explain the nucleation, growth, coalescence, disappearance, and geometry of the aluminium islands.

  18. A Statistical Analysis on the Precipitated and Trapped Electron Fluxes Using Long-term POES Observations

    Science.gov (United States)

    Zhou, C.; Ni, B.; Li, W.; Zhao, Z.; Gu, X.; Shi, R.; Hu, Z.

    2013-12-01

    We present a statistical analysis on the electron precipitation and trapped fluxes using NOAA POES data from 1998 to 2013, which covers more than an entire solar circle. The data of precipitation and trapped electron fluxes and the ratios between them are comprehensively investigated as a function of L-shell, magnetic local time (MLT), and geomagnetic conditions. Our results will help establish the major features of precipitated and trapped electron dynamics in the inner magnetosphere and their dependence on the level of geomagnetic activity, spatial location and phase of a solar cycle. We also investigate electron precipitation near the area of the South Atlantic Anomaly and compare the results with other regions where the ambient magnetic field configuration is normal. By doing so, we intend to explore the effect of precipitation caused by drift loss cone in contrast to that caused by bounce loss cone.

  19. Observation of inhibited electron-ion coupling in strongly heated graphite

    OpenAIRE

    White, T. G.; Vorberger, J.; Brown, C. R. D.; Crowley, B. J. B.; Davis, P; Glenzer, S H; Harris, J. W. O.; Hochhaus, D. C.; Le Pape, S.; Ma, T; C. D. Murphy; P. Neumayer; Pattison, L. K.; Richardson, S.; D. O. Gericke

    2012-01-01

    Creating non-equilibrium states of matter with highly unequal electron and lattice temperatures (T ele≠T ion) allows unsurpassed insight into the dynamic coupling between electrons and ions through time-resolved energy relaxation measurements. Recent studies on low-temperature laser-heated graphite suggest a complex energy exchange when compared to other materials. To avoid problems related to surface preparation, crystal quality and poor understanding of the energy deposition and transport m...

  20. Conditions of observation of electrode masses in environmental scanning electron microscope

    Czech Academy of Sciences Publication Activity Database

    Drnovský, Radek; Michálek, Martin

    Prague: Czech Technical University in Prague, Faculty of Mechanical Engineering, 2000 - (Starý, V.; Horák, K.; Voňková, V.), s. 200 ISBN 80-01-02176-9. [EMAS 2000 - Regional Workshop on Electron Probe Microanalysis Today /4./. Třešť (CZ), 17.05.2000-20.05.2000] Institutional research plan: CEZ:AV0Z2065902 Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  1. 4D Nanoscale Diffraction Observed by Convergent-Beam Ultrafast Electron Microscopy

    OpenAIRE

    Yurtsever, Aycan; Zewail, Ahmed H.

    2009-01-01

    Diffraction with focused electron probes is among the most powerful tools for the study of time-averaged nanoscale structures in condensed matter. Here, we report four-dimensional (4D) nanoscale diffraction, probing specific site dynamics with 10 orders of magnitude improvement in time resolution, in convergent-beam ultrafast electron microscopy (CB-UEM). As an application, we measured the change of diffraction intensities in laser-heated crystalline silicon as a function of time and fluence....

  2. Observation of the substructure in the electron bunch on the ACO storage ring

    International Nuclear Information System (INIS)

    In the future, one interesting point of the SRFEL at Orsay will be the microtemporal analysis of the laser beam correlated with that of the electron bunch. In a first time, we have only analysed the temporal structure of the electron bunch with an Electrophotonic streak camera. The first results seem to indicate that the bunch is not an homogeneous bunch but presents a substructure. We discuss with details this data

  3. Rocket observations of the precipitation of electrons by ground VLF transmitters

    International Nuclear Information System (INIS)

    Below an altitude of 400 km or less over the NASA Wallops Island range, stably trapped particles do not exist because of the South Atlantic Anomaly. In an experiment to measure scattered electrons at these altitudes (NASA flight 36:013), electron detectors clearly measured two monoenergetic electron peaks above the low background. The two monoernergetic peaks are attributed to the resonant interaction of electrons with VLF waves from Navy ground transmitters at Cutler, Maine, and Annapolis, Maryland. The transmitter signals were measured with electric and magnetic receivers aboard the rocket, and their propagation through the ionosphere and correlation with the precipitated electrons are discussed. In addition, energetic ions were also measured to be in the bounce loss cone during this rocket flight. Because of increased geomagnetic activity, it apears that the ring current extended inward to at least the L=2.5 magnetic shell and enhanced convection eroded the plasmasphere. The inward movement or compression of the plasmapause is consistent with a steep gradient in the equatorial cold plasma density and a localized equatorial interaction region needed to account for the monoenergetic elecrtron precipitation. The role of the geomagnetic activity in ''priming'' the trapped electron population for cyclotron resonance with VLF waves such that there is continuous scattering into the bounce loss cone remains uncertain. copyright American Geophysical Union 1989

  4. On forbidden high-energy electrons as a source of background in X-ray and gamma-ray observations

    CERN Document Server

    Suvorova, Alla V

    2014-01-01

    The study is devoted to a problem of electron-induced contaminant to X-ray and gamma-ray astrophysical measurements on board low-orbiting satellites. We analyzed enhancements of electron fluxes in energy range 100 - 300 keV observed at equatorial and low latitudes by a fleet of NOAA/POES low-orbiting satellites over the time period from 2003 to 2005. It was found that 100-300 keV electron fluxes in the forbidden zone below the inner radiation belt enhanced by several orders of magnitude during geomagnetic storms and/or under strong compressions of the magnetosphere. The enhancements are related to high substorm activity and occurred at any local time. Intense fluxes of the energetic electrons in the forbidden zone can be considered as an essential contaminant to X-ray and gamma-ray measurements at low-latitude and low-altitude orbits.

  5. Electron kinetics inferred from observations of microwave bursts during edge localised modes in the Mega-Amp Spherical Tokamak

    CERN Document Server

    Freethy, S J; Chapman, S C; Dendy, R O; Lai, W N; Pamela, S J P; Shevchenko, V F; Vann, R G L

    2014-01-01

    Recent measurements of microwave and X-ray emission during edge localised mode (ELM) activity in tokamak plasmas provide a fresh perspective on ELM physics. It is evident that electron kinetics, which are not incorporated in standard (fluid) models for the instability that drives ELMs, play a key role in the new observations. These effects should be included in future models for ELMs and the ELM cycle. The observed radiative effects paradoxically imply acceleration of electrons parallel to the magnetic field combined with rapid acquisition of perpendicular momentum. It is shown that this paradox can be resolved by the action of the anomalous Doppler instability which enables fast collective radiative relaxation, in the perpendicular direction, of electrons accelerated in the parallel direction by inductive electric fields generated by the initial ELM instability.

  6. Electron kinetics inferred from observations of microwave bursts during edge localized modes in the mega-amp spherical tokamak.

    Science.gov (United States)

    Freethy, S J; McClements, K G; Chapman, S C; Dendy, R O; Lai, W N; Pamela, S J P; Shevchenko, V F; Vann, R G L

    2015-03-27

    Recent measurements of microwave and x-ray emission during edge localized mode (ELM) activity in tokamak plasmas provide a fresh perspective on ELM physics. It is evident that electron kinetics, which are not incorporated in standard (fluid) models for the instability that drives ELMs, play a key role in the new observations. These effects should be included in future models for ELMs and the ELM cycle. The observed radiative effects paradoxically imply acceleration of electrons parallel to the magnetic field combined with rapid acquisition of perpendicular momentum. It is shown that this paradox can be resolved by the action of the anomalous Doppler instability which enables fast collective radiative relaxation, in the perpendicular direction, of electrons accelerated in the parallel direction by inductive electric fields generated by the initial ELM instability. PMID:25860751

  7. Space and Astrophysical Plasmas : Dromion solutions for an electron acoustic wave and its application to space observations

    Indian Academy of Sciences (India)

    S S Ghosh; A Sen; G S Lakhina

    2000-11-01

    The nonlinear evolution of an electron acoustic wave is shown to obey the Davey–Stewartson I equation which admits so called dromion solutions. The importance of these two dimensional localized solutions for recent satellite observations of wave structures in the day side polar cap regions is discussed and the parameter regimes for their existence is delineated.

  8. Solar Wind Electron Strahls Associated with a High-Latitude CME: Ulysses Observations

    Science.gov (United States)

    Lazar, M.; Pomoell, J.; Poedts, S.; Dumitrache, C.; Popescu, N. A.

    2014-11-01

    Counterstreaming beams of electrons are ubiquitous in coronal mass ejections (CMEs) - although their existence is not unanimously accepted as a necessary and/or sufficient signature of these events. We continue the investigation of a high-latitude CME registered by the Ulysses spacecraft on 18 - 19 January 2002 (Dumitrache, Popescu, and Oncica, Solar Phys. 272, 137, 2011), by surveying the solar-wind electron distributions associated with this event. The temporal evolution of the pitch-angle distributions reveals populations of electrons that are distinguishable through their anisotropy, with clear signatures of i) electron strahls, ii) counter-streaming in the magnetic clouds and their precursors, and iii) unidirectionality in the fast wind preceding the CME. The analysis of the counter-streams inside the CME allows us to elucidate the complexity of the magnetic-cloud structures embedded in the CME and to refine the borders of the event. Identifying such strahls in CMEs, which preserve properties of the low β [<1] coronal plasma, gives more support to the hypothesis that these populations are remnants of the hot coronal electrons that escape from the electrostatic potential of the Sun into the heliosphere.

  9. Observation of inhibited electron-ion coupling in strongly heated graphite

    CERN Document Server

    White, T G; Brown, C R D; Crowley, B J B; Davis, P; Glenzer, S H; Harris, J W O; Hochhaus, D C; Pape, S Le; Ma, T; Murphy, C D; Neumayer, P; Pattison, L K; Richardson, S; Gericke, D O; Gregori, G; 10.1038/srep00889

    2013-01-01

    Creating non-equilibrium states of matter with highly unequal electron and lattice temperatures allows unsurpassed insight into the dynamic coupling between electrons and ions through time-resolved energy relaxation measurements. Recent studies on low-temperature laser-heated graphite suggest a complex energy exchange when compared to other materials. To avoid problems related to surface preparation, crystal quality and poor understanding of the energy deposition and transport mechanisms, we apply a different energy deposition mechanism, via laser-accelerated protons, to isochorically and non-radiatively heat macroscopic graphite samples up to temperatures close to the melting threshold. Using time-resolved x ray diffraction, we show clear evidence of a very small electron-ion energy transfer, yielding approximately three times longer relaxation times than previously reported. This is indicative of the existence of an energy transfer bottleneck in non-equilibrium warm dense matter.

  10. Young's double-slit interference observation of hot electrons in semiconductors.

    Science.gov (United States)

    Furuya, Kazuhito; Ninomiya, Yasunori; Machida, Nobuya; Miyamoto, Yasuyuki

    2003-11-21

    We have carried out Young's double-slit experiment for the hot-electron wave in man-made semiconductor structures with a 25-nm-space double slit in an InP layer buried within GaInAs, a 190-nm-thick GaInAsP hot-electron wave propagation layer, and a collector array of 80 nm pitch. At 4.2 K, dependences of the collector current on the magnetic field were measured and found to agree clearly with the double-slit interference theory. The present results show evidence for the wave front spread of hot electrons using the three-dimensional state in materials, for the first time, and the possibility of using top-down fabrication techniques to achieve quantum wave front control in materials. PMID:14683328

  11. Observation of resonance recombination lines in electron excited Auger spectra of Gd

    International Nuclear Information System (INIS)

    Combined measurements of electron excited Nsub(4,5) Auger spectra and photoelectron emission on clean and oxidized Gd lead to a distinction between Auger lines originating from 4d → continuum and 4d → 4f resonance excitations. Several Auger structures are identified as due to the direct recombination of 4d94f8 states with the 4f and valence electrons. The shape of the most prominent Auger line for oxidized Gd agrees perfectly with the Fano profile of the 4f photoemission intensity. (orig.)

  12. Direct observation of spin-resolved full and empty electron states in ferromagnetic surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Berti, G., E-mail: giulia.berti@polimi.it; Calloni, A.; Brambilla, A.; Bussetti, G.; Duò, L.; Ciccacci, F. [Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133, Milano (Italy)

    2014-07-15

    We present a versatile apparatus for the study of ferromagnetic surfaces, which combines spin-polarized photoemission and inverse photoemission spectroscopies. Samples can be grown by molecular beam epitaxy and analyzed in situ. Spin-resolved photoemission spectroscopy analysis is done with a hemispherical electron analyzer coupled to a 25 kV-Mott detector. Inverse photoemission spectroscopy experiments are performed with GaAs crystals as spin-polarized electron sources and a UV bandpass photon detector. As an example, measurements on the oxygen passivated Fe(100)-p(1×1)O surface are presented.

  13. Observations of DCO/plus/ - The electron abundance in dark clouds

    Science.gov (United States)

    Guelin, M.; Langer, W. D.; Snell, R. L.; Wootten, H. A.

    1977-01-01

    The J equals 2-1 rotational line of DCO(plus) has been definitely detected in five molecular clouds, including three dark clouds, L63, L134, and L134 N, and marginally detected in four others. The DCO(plus) emission has been mapped in L134 N and extends over a region of 3 arcmin. The DCO(plus)/HCO(plus) abundance ratio found at the centers of dark clouds is large and implies a fractional electron abundance of less than one hundred millionth. This low electron density sets constraints on the metals and possibly CO as well as on the hydrogen density.

  14. Long-range protein electron transfer observed at the single-molecule level

    DEFF Research Database (Denmark)

    Chi, Qijin; Farver, Ole; Ulstrup, Jens

    2005-01-01

    A biomimetic long-range electron transfer (ET) system consisting of the blue copper protein azurin, a tunneling barrier bridge, and a gold single-crystal electrode was designed on the basis of molecular wiring self-assembly principles. This system is sufficiently stable and sensitive in a quasi...

  15. Microdomain fluctuations in lead scandium tantalate (PST) observed by high resolution transmission electron microscopy

    International Nuclear Information System (INIS)

    The value of the high-resolution transmission electron microscopy (HRTEM) and dark-field imaging techniques for obtaining nanocrystalline structural information is demonstrated for lead scandium tantalite (PST). Chemical domain textures, polar domain fluctuations and HRTEM images of disordered and ordered PTS are discussed. 5 refs., 5 figs

  16. Observation of the lowest triplet state in silane by electron energy loss spectroscopy

    International Nuclear Information System (INIS)

    The electron energy loss spetra of silane was recorded at several impact energies and angles. It is concluded that the lowest triplet state of silane is formed from configuration mixing of the 4s Rydberg state with a valence state of the same symmetry

  17. Morphologic differences observed by scanning electron microscopy according to the reason for pseudophakic IOL explantation

    DEFF Research Database (Denmark)

    Fernandez-Buenaga, Roberto; Alio, Jorge L.; Ramirez, Jose M.;

    2015-01-01

    Purpose To compare variations in surface morphology, as studied by scanning electron microscopy (SEM), of explanted intraocular lenses (IOLs) concerning the cause leading to the explantation surgery. Methods In this prospective multicenter study, explanted IOLs were analyzed by SEM and energy-dis...

  18. Implications of X-Ray Observations for Electron Acceleration and Propagation in Solar Flares

    Science.gov (United States)

    Holman, G. D.; Aschwanden, M. J.; Aurass, H.; Battaglia, M.; Grigis, P. C.; Kontar, E. P.; Liu, W.; Saint-Hilaire, P.; Zharkova, V. V.

    2011-01-01

    High-energy X-rays and gamma-rays from solar flares were discovered just over fifty years ago. Since that time, the standard for the interpretation of spatially integrated flare X-ray spectra at energies above several tens of keV has been the collisional thick-target model. After the launch of the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) in early 2002, X-ray spectra and images have been of sufficient quality to allow a greater focus on the energetic electrons responsible for the X-ray emission, including their origin and their interactions with the flare plasma and magnetic field. The result has been new insights into the flaring process, as well as more quantitative models for both electron acceleration and propagation, and for the flare environment with which the electrons interact. In this article we review our current understanding of electron acceleration, energy loss, and propagation in flares. Implications of these new results for the collisional thick-target model, for general flare models, and for future flare studies are discussed.

  19. Observation of dislocations in crystals using X-ray and electron transmission

    International Nuclear Information System (INIS)

    Two approaches of the dynamical theory of diffraction (EWALD's and AUTHIER's) are recalled briefly. In the light of these theories, one then considers what information concerning the dislocations existing in a crystal can be obtained by X-Ray as well as electron diffraction. (author)

  20. Observing incidental harbour porpoise Phocoena phocoena bycatch by remote electronic monitoring

    DEFF Research Database (Denmark)

    Kindt-Larsen, Lotte; Dalskov, Jørgen; Stage, Bjarne;

    2012-01-01

    to document bycatch of marine mammals, 6 Danish commercial gillnetters (10 to15 m in length) operating under the Danish catch quota management system were equipped with Remote Electronic Monitoring (REM) systems. The REM systems provided video footage, time and position of all net hauls and bycatches...

  1. Direct observation of the collapse of the delocalized excess electron in water

    Czech Academy of Sciences Publication Activity Database

    Savolainen, J.; Uhlig, Frank; Ahmed, S.; Hamm, P.; Jungwirth, Pavel

    2014-01-01

    Roč. 6, č. 8 (2014), s. 697-701. ISSN 1755-4330 R&D Projects: GA ČR GBP208/12/G016 Institutional support: RVO:61388963 Keywords : hydrated electron * THz spectroscopy * ab initio molecular dynamics Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 25.325, year: 2014

  2. Penetration and establishment of Phakopsora pachyrhizi in soybean leaves as observed by transmission electron microscopy

    Science.gov (United States)

    Transmission electron microscopy revealed that the usual location of appressorial formation by P. pachyrhizi on the leaf surface of soybean was over the anticlinal wall depression between adjacent epidermal cells. A fibril-like matrix appeared to act as an anchor for the appressorium to attach to t...

  3. Thermal stability of catalytically grown multi-walled carbon nanotubes observed in transmission electron microscopy

    DEFF Research Database (Denmark)

    Wang, Cheng-Yu; Liu, Chuan-Pu; Boothroyd, Chris

    2009-01-01

    The thermal stability of multi-walled carbon nanotubes (MWCNTs) was assessed in situ by transmission electron microscopy. Upon heating, Ni catalysts in MWC-NTs containing bamboo structures shrank from the tail due to evaporation, leading to additional bamboo formation and tube elongation at 800...

  4. Study of the grasping spines and teeth of 6 chaetognath species observed by scanning electron microscopy.

    Science.gov (United States)

    Moreno, I

    1979-01-01

    The grasping spines and teeth of 6 species of Chaetognatha have been studied with the scanning electron microscope, describing in the grasping spines: curvature, surface, ridge and insertion and in the teeth, its characters and their arrangement on the head. PMID:507374

  5. Experimental observations of the characteristics of hot electron and nonlinear processes produced in special material

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Making use of disk targets composed of several peculiar materials (foam Au, foam C8H8)and hohlraum with a special structure, experiments have been done at"Xing Guang - II" laser facility,which study the characteristics of hot electrons and therelated nonlinear processes such as StimulatedRaman Scattering (SRS), Two Plasma Decay (TPD), StimulatedBrillouin Scattering (SBS), etc.

  6. Electron Compton defect observed in He, H2, D2, N2, and Ne profiles

    International Nuclear Information System (INIS)

    A high-energy electron-impact spectroscopy (HEEIS) apparatus has been constructed for high-precision Compton-scattering experiments. Electron-Compton-scattering experiments are performed by crossing a beam of high energy, but nonrelativistic, electrons with a beam of atoms or molecules and measuring the energy-loss spectrum of the scattered electrons over a range of scattering angles. The improvements of design and technique, the method of data analysis, and the theory used to convert cross sections to Compton profiles are discussed fully. It was found that the energy-loss spectra taken over a range of scattering angles do not reduce by means of the binary-encounter approximation (impulse approximation) to Compton profiles in agreement with theory. This disagreement is most apparent in a shift of the experimental Compton peak: the Compton defect: from the peak predicted by the binary-encounter theory. The Compton defect has been studied in detail for momentum transfers from 1.5--12 a.u. for both He and H2. Defect measurements for D2, N2, and Ne have also been made and it was found that the N2 and Ne defects were opposite in direction from the He and H2 defects. The D2 defect was identical to that for H2. The electron Compton defect is discussed in relation to other recent defect measurements using x-ray and (e,2e) techniques as well as recent theoretical results. An evaluation of the theory used to convert cross sections to Compton profiles is presented and, on the basis of the defect measurements, it is suggested that, even when the binary-encounter conditions have been attained at large momentum transfers, the binary-encounter theory breaks down in the high accuracy (1%) limit. An explanation for this breakdown is given and recent theories, which at least qualitatively account for the Compton defect, are discussed

  7. X-ray observations of MeV electron precipitation with a balloon-borne germanium spectrometer

    Science.gov (United States)

    Millan, R. M.; Lin, R. P.; Smith, D. M.; Lorentzen, K. R.; McCarthy, M. P.

    2002-12-01

    The high-resolution germanium detector aboard the MAXIS (MeV Auroral X-ray Imaging and Spectroscopy) balloon payload detected nine X-ray bursts with significant flux extending above 0.5 MeV during an 18 day flight over Antarctica. These minutes-to-hours-long events are characterized by an extremely flat spectrum (~E-2) similar to the first MeV event discovered in 1996, indicating that the bulk of parent precipitating electrons is at relativistic energies. The MeV bursts were detected between magnetic latitudes 58°-68° (L-values of 3.8-6.7) but only in the late afternoon/dusk sectors (14:30-00:00 MLT), suggesting scattering by EMIC (electromagnetic ion cyclotron) waves as a precipitation mechanism. We estimate the average flux of precipitating E >= 0.5 MeV electrons to be ~360 cm-2s-1, corresponding to about 5 × 1025 such electrons precipitated during the eight days at L = 3.8-6.7, compared to ~2 × 1025 trapped 0.5-3.6 MeV electrons estimated from dosimeter measurements on a GPS spacecraft. These observations show that MeV electron precipitation events are a primary loss mechanism for outer zone relativistic electrons.

  8. Intense energetic electron flux enhancements in Mercury's magnetosphere: An integrated view with high-resolution observations from MESSENGER

    Science.gov (United States)

    Baker, Daniel N.; Dewey, Ryan M.; Lawrence, David J.; Goldsten, John O.; Peplowski, Patrick N.; Korth, Haje; Slavin, James A.; Krimigis, Stamatios M.; Anderson, Brian J.; Ho, George C.; McNutt, Ralph L.; Raines, Jim M.; Schriver, David; Solomon, Sean C.

    2016-03-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission to Mercury has provided a wealth of new data about energetic particle phenomena. With observations from MESSENGER's Energetic Particle Spectrometer, as well as data arising from energetic electrons recorded by the X-Ray Spectrometer and Gamma-Ray and Neutron Spectrometer (GRNS) instruments, recent work greatly extends our record of the acceleration, transport, and loss of energetic electrons at Mercury. The combined data sets include measurements from a few keV up to several hundred keV in electron kinetic energy and have permitted relatively good spatial and temporal resolution for many events. We focus here on the detailed nature of energetic electron bursts measured by the GRNS system, and we place these events in the context of solar wind and magnetospheric forcing at Mercury. Our examination of data at high temporal resolution (10 ms) during the period March 2013 through October 2014 supports strongly the view that energetic electrons are accelerated in the near-tail region of Mercury's magnetosphere and are subsequently "injected" onto closed magnetic field lines on the planetary nightside. The electrons populate the plasma sheet and drift rapidly eastward toward the dawn and prenoon sectors, at times executing multiple complete drifts around the planet to form "quasi-trapped" populations.

  9. Energetic-electron flux enhancements in Mercury's magnetosphere: An integrated view with high-resolution observations from MESSENGER

    Science.gov (United States)

    Baker, Daniel N.

    2016-04-01

    The MESSENGER mission to Mercury has provided a wealth of new data about energetic particle phenomena. With observations from MESSENGER's Energetic Particle Spectrometer (EPS), as well as data arising from energetic electrons recorded by the X-Ray Spectrometer (XRS) and Gamma-Ray and Neutron Spectrometer (GRNS) instruments, recent work greatly extends our record of the acceleration, transport, and loss of energetic electrons at Mercury. The combined data sets include measurements from a few keV up to several hundred keV in electron kinetic energy and have permitted relatively good spatial and temporal resolution for many events. We focus here on the detailed nature of energetic electron bursts measured by the GRNS system, and we place these events in the context of solar wind and magnetospheric forcing at Mercury. Our examination of data at high temporal resolution (10 ms) during the period March 2013 through October 2014 supports strongly the view that energetic electrons are accelerated in the near-tail region of Mercury's magnetosphere and are subsequently "injected" onto closed magnetic field lines on the planetary night side. The electrons populate the plasma sheet and drift rapidly eastward toward the dawn and pre-noon sectors, at time executing multiple complete drifts around the planet to form "quasi-trapped" populations.

  10. Backscattered electron SEM imaging of resin sections from plant specimens: observation of histological to subcellular structure and CLEM.

    Science.gov (United States)

    Rizzo, N W; Duncan, K E; Bourett, T M; Howard, R J

    2016-08-01

    We have refined methods for biological specimen preparation and low-voltage backscattered electron imaging in the scanning electron microscope that allow for observation at continuous magnifications of ca. 130-70 000 X, and documentation of tissue and subcellular ultrastructure detail. The technique, based upon early work by Ogura & Hasegawa (1980), affords use of significantly larger sections from fixed and resin-embedded specimens than is possible with transmission electron microscopy while providing similar data. After microtomy, the sections, typically ca. 750 nm thick, were dried onto the surface of glass or silicon wafer and stained with heavy metals-the use of grids avoided. The glass/wafer support was then mounted onto standard scanning electron microscopy sample stubs, carbon-coated and imaged directly at an accelerating voltage of 5 kV, using either a yttrium aluminum garnet or ExB backscattered electron detector. Alternatively, the sections could be viewed first by light microscopy, for example to document signal from a fluorescent protein, and then by scanning electron microscopy to provide correlative light/electron microscope (CLEM) data. These methods provide unobstructed access to ultrastructure in the spatial context of a section ca. 7 × 10 mm in size, significantly larger than the typical 0.2 × 0.3 mm section used for conventional transmission electron microscopy imaging. Application of this approach was especially useful when the biology of interest was rare or difficult to find, e.g. a particular cell type, developmental stage, large organ, the interface between cells of interacting organisms, when contextual information within a large tissue was obligatory, or combinations of these factors. In addition, the methods were easily adapted for immunolocalizations. PMID:26708578

  11. Observation of longitudinal phase space fragmentation at the TESLA test facility free-electron laser

    International Nuclear Information System (INIS)

    It has been reproducibly observed that the energy distribution of the beam, when fully longitudinally compressed for SASE operation, breaks up into several peaks. In this paper a description of the experimental setup, beam operating conditions, and observations is presented to enable further theoretical studies of this effect

  12. Observation of longitudinal phase space fragmentation at the TESLA test facility free-electron laser

    Science.gov (United States)

    Hüning, M.; Piot, Ph.; Schlarb, H.

    2001-12-01

    It has been reproducibly observed that the energy distribution of the beam, when fully longitudinally compressed for SASE operation, breaks up into several peaks. In this paper a description of the experimental setup, beam operating conditions, and observations is presented to enable further theoretical studies of this effect.

  13. Observation of longitudinal phase space fragmentation at the TESLA test facility free-electron laser

    CERN Document Server

    Hüning, M; Schlarb, H

    2001-01-01

    It has been reproducibly observed that the energy distribution of the beam, when fully longitudinally compressed for SASE operation, breaks up into several peaks. In this paper a description of the experimental setup, beam operating conditions, and observations is presented to enable further theoretical studies of this effect.

  14. Observations of total electron content perturbations on GPS signals caused by a ground level explosion

    Science.gov (United States)

    Fitzgerald, T. Joseph

    1997-05-01

    We have measured perturbations of electron density in the ionosphere caused by a ground level explosion with an energy release of 2 kt (8.5 × 1012 J) using transmissions from Global Positioning System (GPS) satellites to monitor integrated electron density. The frequencies of the transmissions were 1575.42 MHz (L1) and 1227.60 MHz (L2). The detected perturbation showed a maximum excursion of 0.14 TEC units and had a duration of 80 s beginning at 565 s after the explosion. The acoustic disturbance necessary to produce such a perturbation is well modeled as an N wave with a dimension of 35 km and a relative amplitude of 12% propagating radially at a speed of 0.7 km/s. The majority of the TEC perturbation occurred at an altitude of approximately 200 km.

  15. 4D nanoscale diffraction observed by convergent-beam ultrafast electron microscopy.

    Science.gov (United States)

    Yurtsever, Aycan; Zewail, Ahmed H

    2009-10-30

    Diffraction with focused electron probes is among the most powerful tools for the study of time-averaged nanoscale structures in condensed matter. Here, we report four-dimensional (4D) nanoscale diffraction, probing specific site dynamics with 10 orders of magnitude improvement in time resolution, in convergent-beam ultrafast electron microscopy (CB-UEM). As an application, we measured the change of diffraction intensities in laser-heated crystalline silicon as a function of time and fluence. The structural dynamics (change in 7.3 +/- 3.5 picoseconds), the temperatures (up to 366 kelvin), and the amplitudes of atomic vibrations (up to 0.084 angstroms) are determined for atoms strictly localized within the confined probe area (10 to 300 nanometers in diameter). We anticipate a broad range of applications for CB-UEM and its variants, especially in the studies of single particles and heterogeneous structures. PMID:19900928

  16. Insights into magnetosphere-ionosphere-thermosphere coupling revealed in GPS total electron content observations from ground and space (Invited)

    Science.gov (United States)

    Mannucci, A. J.; Verkhoglyadova, O. P.; Tsurutani, B.; Miladinovich, D.; Butala, M. D.; Komjathy, A.

    2013-12-01

    The continuous global availability of GPS total electron content (TEC) observations is enabling new insights into how solar wind energy modifies the upper atmosphere during magnetic storm intervals. Detailed studies over a range of storm intensities are revealing a comprehensive and complex picture of the global TEC response. During the main phase of intense geomagnetic storms, large rapid (1-2 hour) increases in TEC are the signature of prompt penetration electric fields causing the daytime superfountain. However, such a response is not always observed. Recent research suggests the TEC response may be affected by high latitude electrodynamics, as driven by the interplanetary magnetic field orientation. We also present the global TEC response to moderate intensity storms driven by coronal mass ejections. Another type of geomagnetic storm is caused by solar wind high speed streams (HSSs) and associated co-rotating interaction regions (CIRs). Focused study on HSS/CIR storms reveals daytime TEC increases and nighttime decreases, but understanding the TEC response during these extended but less intense storms is currently in its infancy. TEC observations are also available from orbiting platforms such as the COSMIC satellite constellation that measure TEC in a limb-sounding geometry. Electron density differences in the E and F region ionosphere are clearly distinguished by these data. At high latitudes, these data provide information on the presence of energetic electron precipitation that is complementary to current high latitude networks of radar and optical observatories. Recently analyzed high latitude observations from COSMIC are presented.

  17. In-situ observation of salt crystallization using environmental scanning electron microscopy

    Czech Academy of Sciences Publication Activity Database

    Runštuk, Jiří; Neděla, Vilém; Čudek, P.; Jirák, J.

    Graz : Verlag der Technischen Universität, 2009, Vol. 1: 225-226. ISBN 978-3-85125-062-6. [MC 2009 - Joint Meeting of Dreiländertagung and Multinational Congress on Microscopy /9./. Graz (AT), 30.08.2009-04.09.2009] Institutional research plan: CEZ:AV0Z20650511 Keywords : crystallization * in-situ study * environmental SEM * salt Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering http://www.univie.ac.at/asem/Graz_MC_09/papers/97905.pdf

  18. Electron microscope observations on the cytoplasmic granules of a freshwater teleost (Pimelodus maculatus) leucocyte.

    Science.gov (United States)

    Ferri, S; Hernandez Blazquez, F J

    1987-01-01

    In the present study, a hitherto undescribed granule type in the leucocytes of the freshwater teleost Pimelodus maculatus is reported. This membrane bounded elliptic granule contains straight tubules measuring from 8 to 10 nm in diameter. Almost all granules present 1 or 2 electron dense inclusions more often than not with a geometrical form. A comparison with the granules found in Prochilodus scrofa leucocytes is made. PMID:3631529

  19. Stable propagation of a high-current electron beam: experimental observations and computational modeling

    International Nuclear Information System (INIS)

    Experimental studies of self-focused, high-current electron-beam propagation phenomena are compared with the results of computational modeling. The model includes the radial structure of the beam-plasma system, a full electromagnetic field description, primary and secondary gas ionization processes, and a linear theory of the hose-like distortions. Good agreement between the experimental results and the computations strengthens the premise that hose instability is the principal limitation to propagation at high pressure

  20. Real-time observation of interfering crystal electrons in high-harmonic generation

    OpenAIRE

    Hohenleutner, M.; Langer, F.; Schubert, O.; Knorr, M.; Huttner, U.; Koch, S. W.; Kira, M.; Huber, R.

    2016-01-01

    Accelerating and colliding particles has been a key strategy to explore the texture of matter. Strong lightwaves can control and recollide electronic wavepackets, generating high-harmonic (HH) radiation which encodes the structure and dynamics of atoms and molecules and lays the foundations of attosecond science. The recent discovery of HH generation in bulk solids combines the idea of ultrafast acceleration with complex condensed matter systems and sparks hope for compact solid-state attosec...

  1. Transmission-scanning electron microscopic observations of selected Eikenella corrodens strains.

    OpenAIRE

    Progulske, A; Holt, S C

    1980-01-01

    The morphology of Eikenella corrodens 333/54-55 (ATCC 23834) and two human periodontal lesion isolates, strains 470 and 373, was examined by transmission and scanning electron microscopy. All strains exhibited a cell envelope characteristic of gram-negative bacteria. Staining with ruthenium red and alcian blue revealed a loosely organized fibrous slime layer associated with the outer surface of the outer membrane. Slime "stabilization" was achieved by incubation of cells with antisera prepare...

  2. Marcus Bell-Shaped Electron Transfer Kinetics Observed in an Arrhenius Plot.

    Science.gov (United States)

    Waskasi, Morteza M; Kodis, Gerdenis; Moore, Ana L; Moore, Thomas A; Gust, Devens; Matyushov, Dmitry V

    2016-07-27

    The Marcus theory of electron transfer predicts a bell-shaped dependence of the reaction rate on the reaction free energy. The top of the "inverted parabola" corresponds to zero activation barrier when the electron-transfer reorganization energy and the reaction free energy add up to zero. Although this point has traditionally been reached by altering the chemical structures of donors and acceptors, the theory suggests that it can also be reached by varying other parameters of the system including temperature. We find here dramatic evidence of this phenomenon from experiments on a fullerene-porphyrin dyad. Following photoinduced electron transfer, the rate of charge recombination shows a bell-shaped dependence on the inverse temperature, first increasing with cooling and then decreasing at still lower temperatures. This non-Arrhenius rate law is a result of a strong, approximately hyperbolic temperature variation of the reorganization energy and the reaction free energy. Our results provide potentially the cleanest confirmation of the Marcus energy gap law so far since no modification of the chemical structure is involved. PMID:27379373

  3. Cyclic bending experiments on free-standing Cu micron lines observed by electron backscatter diffraction

    International Nuclear Information System (INIS)

    Polycrystalline Cu samples 20 × 20 μm2 in size were cyclically bent inside a scanning electron microscope until fracture occurred. The microstructural changes were investigated by secondary electron imaging and electron backscatter diffraction. The in situ experiments revealed that, for the coarse-grained samples, it is not the external stress that dominates the cyclic deformation, but the local internal strength. This is in strong contrast to macroscopic bending samples, where deformation always happens near the fixed end of the bending beam and decreases constantly with increasing distance from the fixation. For micron-sized polycrystalline samples, the grain dimensions, dislocation density evolution and grain orientation (Taylor factor) can define the location of failure if the grain size and sample diameter become similar in size. A comparison with cyclic in situ tension–tension experiments (ratio of minimum stress to maximum stress R ≈ 0) reveals that cyclic bending experiments (R ≈ −1) undergo bulk-like fatigue deformation with extrusions/intrusions, in contrast to the experiments with R ≈ 0. Both the cyclic tension–tension and bending experiments can be described by a Basquin equation, although different mechanisms lead to failure of the samples

  4. Neutrino Signals from Annihilating/Decaying Dark Matter in the Light of Recent Measurements of Cosmic Ray Electron/Positron Fluxes

    OpenAIRE

    Hisano, Junji; Kawasaki, Masahiro; Kohri, Kazunori; Nakayama, Kazunori

    2008-01-01

    The excess of cosmic-ray electron and positron fluxes measured by the PAMELA satellite and ATIC balloon experiments may be interpreted as the signals of the dark matter annihilation or decay into leptons. In this letter we show that the dark matter annihilation/decay which reproduces the electron/positron excess may yield a significant amount of high-energy neutrinos from the Galactic center. In the case, future kilometer-square size experiments may confirm such a scenario, or even the Super-...

  5. Observation of strong electron correlations in YBa2Cu3O7-δ by hv-dependent photoelectron spectroscopy

    International Nuclear Information System (INIS)

    We present photoemission spectra from single-phase YBa2Cu3O7-δ which have been measured in the photon energy range (17(division)130)eV, at T=80 K, T=300 K and intermediate temperatures using synchrotron radiation. Intense satellites associated with the Cu3d and O2p bands are observed to undergo resonances at the Cu3p and O2s core level excitation thresholds, respectively, indicating the presence of holes in the Cu and O hybrid bands on both Cu and O sites. The strong correlation effects for the valence electrons suggest that one-electron calculations may not be appropriate for a detailed description of the electronic properties of this material

  6. Comparison of plasmaspheric electron content over sea and land using Jason-2 observations

    Science.gov (United States)

    Gulyaeva, Tamara; Cherniak, Iurii; Zakharenkova, Irina

    2016-07-01

    The Global Ionospheric Maps of Total Electron Content, GIM-TEC, may suffer from model assumptions, in particular, over the oceans where relatively few measurements are available due to a scarcity of ground-based GPS receivers network only on seashores and islands which involve more assumptions or interpolations imposed on GIM mapping techniques. The GPS-derived TEC represents the total electron content integrated through the ionosphere, iTEC, and the plasmasphere, pTEC. The sea/land differences in the F2 layer peak electron density, NmF2, and the peak height, hmF2, gathered with topside sounding data exhibit tilted ionosphere along the seashores with denser electron population at greater peak heights over the sea. Derivation of a sea/land proportion of total electron content from the new source of the satellite-based measurements would allow improve the mapping GIM-TEC products and their assimilation by the ionosphere-plasmasphere IRI-Plas model. In this context the data of Jason-2 mission provided through the NOAA CLASS Website (http://www.nsof.class.noaa.gov/saa/products/catSearch) present a unique database of pTEC measured through the plasmasphere over the Jason-2 orbit (1335 km) to GPS orbit (20,200 km) which become possible from GPS receivers placed onboard of Jason-2 with a zenith looking antenna that can be used not only for precise orbit determination (POD), but can also provide new data on the plasma density distribution in the plasmasphere. Special interest represents possibility of the potential increase of the data volume in two times due to the successful launch of the Jason-3 mission on 17 January 2016. The present study is focused on a comparison of plasmasphere electron content, pTEC, over the sea and land with a unique data base of the plasmasphere electron content, pTEC, using measurements onboard Jason-2 satellite during the solar minimum (2009) and solar maximum (2014). Slant TEC values were scaled to estimate vertical pTEC using a geometric

  7. Intense energetic-electron flux enhancements in Mercury's magnetosphere: An integrated view with high-resolution observations from MESSENGER

    Science.gov (United States)

    Dewey, R. M.; Baker, D. N.; Slavin, J. A.; Raines, J. M.; Lawrence, D. J.; Goldsten, J. O.; Peplowski, P. N.; Korth, H.; Krimigis, S. M.; Anderson, B. J.; Ho, G. C.; McNutt, R. L., Jr.; Schriver, D.; Solomon, S. C.

    2015-12-01

    One of the surprising observations by Mariner 10 during its March 1974 flyby of Mercury was the detection of intense bursts of energetic particles in Mercury's magnetosphere in association with substorm-like magnetic field reconfigurations. A full understanding of where, when, and how such particle bursts occur was not possible from the limited Mariner 10 data. The MESSENGER mission to Mercury has provided a wealth of new data about energetic particle phenomena. With observations from MESSENGER's Energetic Particle Spectrometer (EPS), as well as data arising from energetic electrons recorded by the X-Ray Spectrometer (XRS) and Gamma-Ray and Neutron Spectrometer (GRNS) instruments, recent work has greatly extended our record of the acceleration, transport, and loss of energetic electrons at Mercury. The combined data sets include measurements from a few keV up to several hundred keV in electron kinetic energy and have permitted relatively good spatial and temporal resolution for many events. We focus here on the detailed nature of energetic electron bursts measured by the GRNS system, and we place these events in the context of solar wind and magnetospheric forcing at Mercury. Our examination of data at high temporal resolution (10 ms) during the period March 2013 through October 2014 supports strongly the view that energetic electrons are accelerated in the near-tail region of Mercury's magnetosphere and are subsequently "injected" onto closed magnetic field lines on the planetary night side. The electrons evidently fill the plasma sheet volume and drift rapidly eastward toward the dawn and pre-noon sectors, at time executing multiple complete drifts around the planet to form "quasi-trapped" populations.

  8. BARREL observations of an ICME-shock impact with the magnetosphere and the resultant radiation belt electron loss

    Science.gov (United States)

    Halford, A. J.; McGregor, S. L.; Murphy, K. R.; Millan, R. M.; Hudson, M. K.; Woodger, L. A.; Cattel, C. A.; Breneman, A. W.; Mann, I. R.; Kurth, W. S.; Hospodarsky, G. B.; Gkioulidou, M.; Fennell, J. F.

    2015-04-01

    The Balloon Array for Radiation belt Relativistic Electron Losses (BARREL) mission of opportunity working in tandem with the Van Allen Probes was designed to study the loss of radiation belt electrons to the ionosphere and upper atmosphere. BARREL is also sensitive to X-rays from other sources. During the second BARREL campaign, the Sun produced an X-class flare followed by a solar energetic particle event (SEP) associated with the same active region. Two days later on 9 January 2014, the shock generated by the coronal mass ejection (CME) originating from the active region hits the Earth while BARREL was in a close conjunction with the Van Allen Probes. Time History Events and Macroscale Interactions during Substorms (THEMIS) satellite observed the impact of the interplanetary CME (ICME) shock near the magnetopause, and the Geostationary Operational Environmental Satellites (GOES) were on either side of the BARREL/Van Allen Probe array. The solar interplanetary magnetic field was not ideally oriented to cause a significant geomagnetic storm, but compression from the shock impact led to the loss of radiation belt electrons. We propose that an azimuthal electric field impulse generated by magnetopause compression caused inward electron transport and minimal loss. This process also drove chorus waves, which were responsible for most of the precipitation observed outside the plasmapause. Observations of hiss inside the plasmapause explain the absence of loss at this location. ULF waves were found to be correlated with the structure of the precipitation. We demonstrate how BARREL can monitor precipitation following an ICME-shock impact at Earth in a cradle-to-grave view; from flare, to SEP, to electron precipitation.

  9. Multi-spacecraft Observations and Transport Modeling of Energetic Electrons for a Series of Solar Particle Events in August 2010

    Science.gov (United States)

    Dröge, W.; Kartavykh, Y. Y.; Dresing, N.; Klassen, A.

    2016-08-01

    During 2010 August a series of solar particle events was observed by the two STEREO spacecraft as well as near-Earth spacecraft. The events, occurring on August 7, 14, and 18, originated from active regions 11093 and 11099. We combine in situ and remote-sensing observations with predictions from our model of three-dimensional anisotropic particle propagation in order to investigate the physical processes that caused the large angular spreads of energetic electrons during these events. In particular, we address the effects of the lateral transport of the electrons in the solar corona that is due to diffusion perpendicular to the average magnetic field in the interplanetary medium. We also study the influence of two coronal mass ejections and associated shock waves on the electron propagation, and a possible time variation of the transport conditions during the above period. For the August 18 event we also utilize electron observations from the MESSENGER spacecraft at a distance of 0.31 au from the Sun for an attempt to separate between radial and longitudinal dependencies in the transport process. Our modelings show that the parallel and perpendicular diffusion mean free paths of electrons can vary significantly not only as a function of the radial distance, but also of the heliospheric longitude. Normalized to a distance of 1 au, we derive values of λ ∥ in the range of 0.15–0.6 au, and values of λ ⊥ in the range of 0.005–0.01 au. We discuss how our results relate to various theoretical models for perpendicular diffusion, and whether there might be a functional relationship between the perpendicular and the parallel mean free path.

  10. Scanning electron microscopic observations of fibrous structure of cemento-dentinal junction in healthy teeth

    Directory of Open Access Journals (Sweden)

    B Pratebha

    2014-01-01

    Results: The CDJ appeared to be a fibril poor groove with a width of 2-4 µm. Few areas of collagen fiber intermingling could be appreciated. A detailed observation of these tissues has been presented.

  11. Electrons

    International Nuclear Information System (INIS)

    Fast electrons are used to produce isotopes for studying the cooper metabolism: Cu-64 in a cyclotron and Cu-67 in a linear accelerator. Localized electrons are responsible for the chemical and physiological characteristics of the trace elements. Studied are I, Cu, Co, Zn, Mo, Mn, Fe, Se, Mg. The Cu/Mo and Cu/Zn interactions are investigated. The levels of molybdenum, sulfate and zinc in the food are analysed. The role of the electrons in free radicals is discussed. The protection action of peroxidases and super oxidases against electron dangerous effect on normal physiology is also considered. Calculation of radiation damage and radiation protection is made. (author)

  12. Multifrequency Doppler Radar Observations of Electron Gyroharmonic Effects during Electromagnetic Pumping of the Ionosphere

    International Nuclear Information System (INIS)

    Experimental results of multifrequency HF Doppler radar studies during electromagnetic pumping of the ionosphere from the ground are reported. The Doppler shifts of the radar waves after turn-on of the vertically injected HF pump wave depend on the pump frequency and exhibit, at relatively large reflection altitudes, opposite signs for pump frequencies above or below an electron gyroharmonic. The results are interpreted in terms of pump-induced plasma expulsion and enhanced ionization. For pump frequencies at a gyroharmonic, a minimum of plasma perturbation is detected with the radars. copyright 1997 The American Physical Society

  13. Direct observation of polyelectrolyte brushes under wet and dry conditions by atmospheric scanning electron microscopy.

    Science.gov (United States)

    Higuchi, Takeshi; Konyuba, Yuji; Nishiyama, Hidetoshi; Suga, Mitsuo; Takahara, Atsushi; Jinnai, Hiroshi

    2016-04-01

    Polyelectrolyte brushes are polyelectrolyte polymers with one end fixed to a substrate. In this study, direct nano-scale visualization of polyelectrolyte brushes was carried out under 'aqueous conditions' by atmospheric scanning electron microscopy. The thickness of the polyelectrolyte brush layer was measured under both dry and aqueous conditions, experimentally confirming the swollen state of the brushes. These experimental findings qualitatively agreed with the results from previous neutron reflectivity experiments using similar polyelectrolyte brushes. Such direct visualization of polymer brushes in real space opens up a new route for better understanding their surface properties, such as friction, adhesion and wettability. PMID:26581481

  14. Observation of polarization reversal and electron cyclotron damping directly associated with obliquely propagating left-hand polarized wave

    International Nuclear Information System (INIS)

    The polarization reversal from a left-hand (LHPW) to a right-hand polarized wave (RHPW) and the resultant electron cyclotron damping of the LHPW are experimentally observed for the first time. Our experimental results indicate that the polarization reversal arises simultaneously with the conversion of the propagation angle of the wave, in which finite-plasma boundary conditions are considered to be inherent. (author)

  15. Heights of generation of runaway electrons in bright cosmic ray events observed on the ground during thunderstorms

    International Nuclear Information System (INIS)

    The brightest events with enhancements of the intensity of the soft component of secondary cosmic rays observed during thunderstorms in the Baksan Valley are analyzed. These experimental data were obtained during thunderstorm seasons of 2003-2008. Assuming bremsstrahlung photons from cascades of runaway electrons to be the main source of the enhancements, the height of generation level is estimated for every event. It is shown that for a half of all events the region of particle generation is located in the stratosphere.

  16. Observation of triple-photon decay in positron-electron pair annihilation: a triple coincidence setup for the undergraduate laboratory

    OpenAIRE

    Elbasher, M. E. A.; Erasmus, W.; Khaleel, E. A. M.; Ndayishimye, J.; Papka, P.

    2011-01-01

    The positron-electron pair annihilation in two photons is known for its numerous applications using PET scanners. The decay of Positronium (Ps) from a standard sealed source in more than two photons is less likely but can be observed with a relatively simple setup. The main goal of this experiment was to verify momentum and total angular momentum conservation principles at subatomic level through the Ps annihilation. The two spin configurations of Ps are produced with a beta+ source. The deca...

  17. Comparison between POES energetic electron precipitation observations and riometer absorptions:implications for determining true precipitation fluxes

    OpenAIRE

    Rodger, Craig J.; Kavanagh, Andrew J.; Clilverd, Mark A.; Marple, Steve R.

    2013-01-01

    Energetic Electron Precipitation (EEP) impacts the chemistry of the middle atmosphere with growing evidence of coupling to surface temperatures at high latitudes. To better understand this link it is essential to have realistic observations to properly characterise precipitation and which can be incorporated into chemistry-climate models. The Polar-orbiting Operational Environmental Satellites (POES) detectors measure precipitating particles but only integral fluxes and only in a fraction of ...

  18. Channelling phenomenon in the gamma irradiated Benzo-quinone and other compounds observed under the scanning electron microscope

    International Nuclear Information System (INIS)

    Scanning Electron Microscope (S.E.M.), has been used to examine the gamma irradiated pure crystals of Benzo-quinone and other compounds in the polycrystaline form. After gamma irradiation, shallow lines (channels) were observed on the crystal's surfaces when the crystal layers arrangements are parallel to the photons beam direction. Holes were also observed when those layers of the crystals are in the nonparallel case. The phenomenon has been studied and analysed in connected with the H-atom bonds disruption, and H-atoms migration through the crystal's layers. (author)

  19. First observation of alkyne radical anions by electron spin resonance spectroscopy: Hexyne/n-hexane mixed crystals

    International Nuclear Information System (INIS)

    The radical anions of alkynes have been first observed by electron spin resonance spectroscopy following alkene anions previously studied. Hexyne radical anions were formed in 1-, 2-, or 3-hexyne/n--hexane mixed crystals irradiated at 4.2 or 77 K. The characters of the anions were as follows; (a) the α-proton hyperfine coupling is very large (∼4.5 mT for the 1-hexyne anion), (b) the β-proton couplings are very small (∼1.0 mT for C--Hβ proton with the conformational angle of 0 degree), and (c) the radicals show a negative g shift (2.0014). From these observations, it was found that the anions have a nonlinear(bent) molecule structure in the anticonfiguration (trans C--C≡C--C) with the bend angle ∼60 degree, and that the unpaired electron orbital is approximately composed of the anticombination of the sp2 hybrid orbitals of the C≡C carbon atoms. A discussion based on complete neglect of differential overlap (CNDO) molecular orbital (MO) calculations was given for the observed negative g shift, which was shown to be characteristic of the alkyne anions which have a high-lying unpaired electron orbital and an antibonding 2p--2p π carbon orbital just above it on the upper energy side

  20. Observing the Growth of Metal-Organic Frameworks by In-Situ Liquid Cell Transmission Electron Microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Patterson, Joseph P.; Abellan Baeza, Patricia; Denny, Michael S.; Park, Chiwoo; Browning, Nigel D.; Cohen, Seth M.; Evans, James E.; Gianneschi, Nathan C.

    2015-06-17

    Liquid Cell Transmission Electron Microscopy (LCTEM) can provide direct observations of solution phase nanoscale materials, and holds great promise as a tool for monitoring dynamic self assembly processes. Control over particle behavior within the liquid cell, and under electron beam irradiation, is of paramount importance for this technique to contribute to our understanding of chemistry and materials science at the nanoscale. However, this type of control has not been demonstrated for complex, organic macromolecular materials, which form the basis for all biological systems, all of polymer science, and encompass important classes of advanced porous materials. Here we show that by controlling the liquid cell surface chemistry and electron beam effects, the dynamics and self-assembly of metal-organic frameworks (MOFs) can be observed. Our results demonstrate that hybrid organic/inorganic beam sensitive materials can be analyzed with LCTEM and at least in the case of Zif-8 dynamics, the results correlate with observations from bulk growth or other standard synthetic conditions. We anticipate that direct, nanoscale imaging by LCTEM of MOF nucleation and growth mechanisms, may provide insight into controlled MOF crystal morphology, domain composition, and processes influencing defect formation.

  1. In-situ observation of the alpha/beta cristobalite transition using high voltage electron microscopy

    International Nuclear Information System (INIS)

    A high temperature water vapor phase is expected to persist in the vicinity of high level radioactive waste packages for several hundreds of years. The authors have begun an investigation of the structural and chemical effects of water on cristobalite because of its abundance in the near field environment. A high voltage transmission electron microscope (HVEM) investigation of bulk synthesized α-cristobalite to be used in single phase dissolution and precipitation kinetics experiments revealed the presence β-cristobalite, quartz and amorphous silica, in addition to α-cristobalite. Consequently, this apparent metastable persistence of β-cristobalite and amorphous silica during the synthesis of α-cristobalite was investigated using a heating stage and an environmental cell installed in the HVEM that allowed the introduction of either dry CO2 or a CO2 + H2O vapor. Preliminary electron diffraction evidence suggests that the presence of water vapor affected the α-β transition temperature. Water vapor may also be responsible for the development of an amorphous silica phase at the transition that may persist over an interval of several tens of degrees. The amorphous phase was not documented during the dry heating experiments. 20 refs., 7 figs., 5 tabs

  2. Nucleation and growth of carbon onions by means of simultaneous electron microscopic observation under ion implantation

    International Nuclear Information System (INIS)

    In-situ and ex-situ TEM observation was performed in copper implanted with carbon ions at temperature from 570 K to 973 K. Carbon clusters, such as carbon onions (concentric graphic spheres) and nanocapsules (concentric graphitic spheres with cavities), were observed with amorphous carbon layers. Statistics of cluster size as a function of implantation temperature, ion fluence and substrate crystallinity revealed the nucleation processes of the clusters. One is the formation of graphitic layers on grain boundaries. The other is the nucleation of graphitic cages, probably fullerenes, due to both high concentration of carbon atoms and high amount of radiation damage. Simultaneous observation of microstructural evolution under implantation revealed that onions were formed inside the substrate not surface and that they segregate at surface due to radiation-enhanced evaporation. (author)

  3. Evaluating effectiveness and safety toward electronic cigarette among Malaysian vapers: One-month observational study

    Directory of Open Access Journals (Sweden)

    Azizur Rahman

    2016-01-01

    Conclusion: A month follow-up showed a good smoking cessation rate among Malaysian vapers mainly in single users, whereas less number of quitters but the high reduction in tobacco cigarette consumption observed in dual users without any harmful effects. Furthermore, extended period studies are warranted to confirm its long-term safety and effectiveness among different Malaysian population.

  4. Stereoscan electron microscope observations on opisthobranch radulae and shell-sculpture

    NARCIS (Netherlands)

    Thompson, T.E.; Hinton, H.E.

    1968-01-01

    Traditional methods of observation applied to the sculpture of tectibranch shells and to the radulae of gastropods in general, have yielded a great deal of information regarding the structure of these organs, which are so important in taxonomy. In the genus Philine, for instance, the numerous Europe

  5. Lithium-ion Battery Charge Methodologies Observed with Portable Electronic Equipment

    Science.gov (United States)

    Jeevarajan, Judith

    2009-01-01

    Commercial lithium-ion batteries in portable electronic equipment has been used by NASA for space applications since 1999. First battery that was certified for flight and flown for Shuttle use was the Canon BP 927 (2.7 Ah) battery pack. Since then, numerous portable equipment with li-ion batteries have been certified and flown and remain on-orbit for crew usage. Laptops (two generations with third one being worked on now) Camcorder Camera PDA 2 versions (second one being li-ion polymer cells) Satellite Phone Due to expense and time, certified batteries are used with different equipment with the help of adapters or by working with the manufacturer of the equipment to build the appropriate battery compartment and connector. Certified and dedicated chargers are available on Shuttle and on the ISS for safe charging.

  6. Dendritic membrane from insect olfactory hairs: isolation method and electron microscopic observations.

    Science.gov (United States)

    Klein, U; Keil, T A

    1984-12-01

    Sensory hairs from antennae of male saturniid moths (Antheraea polyphemus) were separated while deep-frozen by shaking antennal branches with glass beads. The hairs were collected through their differential adhesion to the surface of a petri dish. The yield, determined by the length of the isolated hair fragments, was about 38% of the estimated total hair length per antenna. The dendritic membrane was separated from the hair fragments by centrifugation through Sephadex and further purified by ultracentrifugation in sucrose buffers. Transmission electron microscopy was used to monitor the steps of the hair and membrane isolation and to investigate the membrane pellet. Some membrane vesicles bound cationized ferritin, thus indicating a negatively charged cell surface coat. Negatively stained membrane vesicles exhibited a pattern of repetitive substructures irregularly distributed over the vesicle surface. The units had a diameter of about 3 nm and a maximal density of 30,000/micron2. PMID:6532523

  7. Real-time observation of ultrafast electron injection at graphene–Zn porphyrin interfaces

    KAUST Repository

    Masih, Dilshad

    2015-02-25

    We report on the ultrafast interfacial electron transfer ( ET) between zinc( II) porphyrin ( ZnTMPyP) and negatively charged graphene carboxylate ( GC) using state- of- the- art femtosecond laser spectroscopy with broadband capabilities. The steady- state interaction between GC and ZnTMPyP results in a red- shifted absorption spectrum, providing a clear indication for the binding affinity between ZnTMPyP and GC via electrostatic and p- p stacking interactions. Ultrafast transient absorption ( TA) spectra in the absence and presence of three different GC concentrations reveal ( i) the ultrafast formation of singlet excited ZnTMPyP*, which partially relaxes into a long- lived triplet state, and ( ii) ET from the singlet excited ZnTMPyP* to GC, forming ZnTMPyP + and GC , as indicated by a spectral feature at 650- 750 nm, which is attributed to a ZnTMPyP radical cation resulting from the ET process.

  8. Observations of MeV electrons and scattered light from intense, subpicosecond laser-plasma interactions

    International Nuclear Information System (INIS)

    In this paper the authors present work in progress in their experimental investigation of the coupling of intense, subpicosecond laser pulses with plasmas preformed on solid targets. (This situation is to be contrasted with the interaction of intense laser fields with solid-density matter. A subject which has generated considerable interest in the last several years.) The characterization of the energy distribution of energetic electrons which escape a solid target irradiated by an intense laser is discussed. The authors have also performed experiments to study the excitation of parametric instabilities near the quarter-critical layer and second-harmonic generation near the critical layer in the plasma. They discuss some preliminary scattered light spectroscopy measurements

  9. ELECTRON HEAT FLUX IN THE SOLAR WIND: ARE WE OBSERVING THE COLLISIONAL LIMIT IN THE 1 AU DATA?

    International Nuclear Information System (INIS)

    Using statistically significant data at 1 AU, it has recently been shown (Bale et al.) that in the solar wind, when the Knudsen number K T (the ratio between the electron mean free path and the electron temperature scale height) drops below about 0.3, the electron heat flux q intensity rapidly approaches the classical collisional Spitzer-Härm limit. Using a fully kinetic model including the effect of Coulomb collisions and the expansion of the solar wind with heliocentric distance, we observe that the heat flux strength does indeed approach the collisional value for Knudsen numbers smaller than about 0.3 in very good agreement with the observations. However, closer inspection of the heat flux properties, such as its variation with the heliocentric distance and its dependence on the plasma parameters, shows that for Knudsen numbers between 0.02 and 0.3 the heat flux is not conveniently described by the Spitzer-Härm formula. We conclude that even though observations at 1 AU seem to indicate that the electron heat flux intensity approaches the collisional limit when the Knudsen drops below ∼0.3, the collisional limit is not a generally valid closure for a Knudsen larger than 0.01. Moreover, the good agreement between the heat flux from our model and the heat flux from solar wind measurements in the high-Knudsen number regime seems to indicate that the heat flux at 1 AU is not constrained by electromagnetic instabilities as both wave-particle and wave-wave interactions are neglected in our calculations

  10. Direct observation of radiation belt electrons precipitation by the controlled injection of VLF signals from a ground-based transmitter

    International Nuclear Information System (INIS)

    Radiation belt electrons precipitated by controlled injection of VLF signals from a ground based transmitter have been directly observed for the first time. These observations were part of the SEEP (Stimulated Emission of Energetic Particles) experiment conducted during May-December 1982. Key elements of SEEP were the controlled modulation of VLF transmitters and a sensitive low altitude satellite payload to detect the precipitation. An outstanding example of time-correlated wave and particle data occurred from 8680 to 8740 seconds. U. T. on 17 August 1982 when the satellite passed near the VLF transmitter at Cutler, Maine (NAA) as it was being modulated with a repeated ON (3--s)/OFF (2--s) pattern. During each of twelve consecutive pulses from the transmitter the electron counting rate increased significantly after start of the ON period and reached a maximum about 2 seconds later. The measured energy spectra revealed that approximately 15 to 50 percent of the enhanced electron flux was concentrated near the resonant energies for first order cyclotron interactions occurring close to the magnetic equator with the nearly monochromatic waves emitted from the transmitter

  11. Letter to the Editor: First direct observations of the reduced striations at pump frequencies close to the electron gyroharmonics

    Directory of Open Access Journals (Sweden)

    M. T. Rietveld

    Full Text Available It is well known that the ionospheric plasma response to high-power HF radio waves changes drastically as the heater frequency approaches harmonics of the electron gyrofrequency. These include changes in the spectrum of the stimulated electromagnetic emission, reduction in the anomalous absorption of low-power diagnostic waves propagating through the heated volume, and reduction in the large scale F-region heating. Theoretical models as well as previous experimental evidence point towards the absence of small-scale field-aligned plasma density irregularities at pump frequencies close to electron gyroharmonics as the main cause of these changes. Results presented in this paper are the first direct observations of the reduced striations at the 3rd gyroharmonic made by the CUTLASS radar. In addition, simultaneous EISCAT observations have revealed that the "enhanced ion-line" usually present in the EISCAT ion-line spectrum during the first few seconds after heater switch on, persisted at varying strengths while the heater was transmitting at frequencies close to the 3rd electron gyroharmonics.Key words. Ionosphere (active experiments; ionospheric irregularities · Radio science (ionospheric physics

  12. Structure and development of viruses observed in the electron microscope. II. Vaccinia and fowl pox viruses.

    Science.gov (United States)

    MORGAN, C; ELLISON, S A; ROSE, H M; MOORE, D H

    1954-09-01

    Vaccinia and fowl pox viruses were visualized by the electron microscope in sections of infected chorioallantoic membrane of chicken embryos. The viruses were of similar structure and size, averaging 200 x 300 mmicro with considerable individual variation. Intracytoplasmic viral particles contained a dense, nucleus-like body (nucleoid) separated from granular material (viroplasm) by a zone of lesser density. They were enclosed by a single membrane. Near the surface of the host cell and in the extracellular space the particles consisted of a central body of variable shape and density enclosed by a double membrane. The initial sites of development were confined to the cytoplasm of the host cell. Before release from the host cell the viral nucleoids appeared to enlarge and to occupy a central position within the particle, which became enclosed by a double limiting membrane. The brick-shaped forms found after removal of the embedding plastic from thick sections indicated that drying caused characteristic distortion of certain viral particles. PMID:13192254

  13. Direct observation of dipolar chains in ferrofluids in zero field using cryogenic electron microscopy

    CERN Document Server

    Butter, K; Frederik, P M; Vroege, G J; Philipse, A P

    2003-01-01

    The particle structure of ferrofluids is studied in situ, by cryogenic electron microscopy, on vitrified films of iron and magnetite dispersions. By means of synthesis of iron colloids with controlled particle size and different types of surfactant, dipolar particle interactions can be varied over a broad range, which significantly influences the ferrofluid particle structure. Our experiments on iron dispersions (in contrast to magnetite dispersions) for the first time demonstrate, in ferrofluids in zero field, a transition with increasing particle size from separate particles to linear chains of particles (Butter K, Bomans P H, Frederik P M, Vroege G J and Philipse A P 2003 Nature Mater. 2 88). These chains, already predicted theoretically by de Gennes and Pincus (de Gennes P G and Pincus P A 1970 Phys. Kondens. Mater. 11 189), very much resemble the fluctuating chains found in simulations of dipolar fluids (Weis J J 1998 Mol. Phys. 93 361, Chantrell R W, Bradbury A, Popplewell J and Charles S W 1982 J. Appl...

  14. Structures in Multicomponent Polymer Films: Their Formation, Observation and Applications in Electronics and Biotechnology

    International Nuclear Information System (INIS)

    Several strategies to form multicomponent films of functional polymers, with micron, submicron and nanometer structures, intended for plastic electronics and biotechnology are presented. These approaches are based on film deposition from polymer solution onto a rotating substrate (spin-casting), a method implemented already on manufacturing lines. Film structures are determined with compositional (nanometer) depth profiling and (submicron) imaging modes of dynamic secondary ion mass spectrometry, near-field scanning optical microscopy (with submicron resolution) and scanning probe microscopy (revealing nanometer features). Self-organization of spin-cast polymer mixtures is discussed in detail, since it offers a one-step process to deposit and align simultaneously domains, rich in different polymers, forming various device elements: (i) Surface segregation drives self-stratification of nanometer lamellae for solar cells and anisotropic conductors. (ii) Cohesion energy density controls morphological transition from lamellar (optimal for encapsulated transistors) to lateral structures (suggested for light emitting diodes with variable color). (iii) Selective adhesion to substrate microtemplates, patterned chemically, orders lateral structures for plastic circuitries. (iv) Submicron imprints of water droplets (breath figures) decorate selectively micron-sized domains, and can be used in devices with hierarchic structure. In addition, selective protein adsorption to regular polymer micropatterns, formed with soft lithography after spin-casting, suggests applications in protein chip technology. An approach to reduce lateral blend film structures to submicron scale is also presented, based on (annealed) films of multicomponent nanoparticles. (authors)

  15. Observation of latent heavy-ion tracks in polyimide by means of transmission electron microscopy

    International Nuclear Information System (INIS)

    The structure of latent tracks produced by high-energy heavy ions in an organic material has been revealed for the first time by transmission electron microscopy. The experiments involved 9.3 MeV/A 197Au and 11.1 MeV/A 208Pb ion beams and ∼50-nm thick polyimide foils (ion stopping power ∼110 MeV mg-1 cm2). Two-week old tracks are open channels, indicating the importance of violent energy equilibration events. Four-month old tracks engulf small amounts of material. Hence, damage sites exhibit chemical activity on a timescale of months, with possible absorption of material from the atmosphere. The change of material density at the track boundary is sharp. The track width distribution is broad. This may have resulted from the inhomogeneity of the polymer density on a molecular scale. The mean track diameter is 8.1±1.7 nm. There is no evidence for any severe structural alteration outside the track core

  16. Monitoring the three-dimensional ionospheric electron density distribution using GPS observations over China

    Indian Academy of Sciences (India)

    Wen Debao; Yuan Yunbin; Ou Jikun

    2007-06-01

    In this paper, an IRI model assisted GPS-based Computerized Ionospheric Tomography (CIT) technique is developed to inverse the ionospheric electron density (IED) distribution over China. Essentially, an improved algebraic reconstruction technique (IART) is first proposed to reconstruct the ionospheric images with high resolution and high efficiency. A numerical experiment is used to validate the reliability of the method and its advantages to the classical algebraic reconstruction technique (ART). This is then used to reconstruct the IED images using the GPS data in China. The variations of the IED during magnetically quiet and disturbed days are reported and analyzed here. Reconstructed results during magnetically quiet days show some prominent ionospheric features such as the development of equatorial anomaly and the tilt of ionization crest. Meanwhile, ionospheric storm phase effects and disturbed features can also be revealed from the reconstructed IED image under storm conditions. Research shows that the positive storm phase effects usually happen in southern China, and the negative storm phase effects mainly occur in northern China. The equatorial anomaly crest moved to the north in the main phase of the storm. Ionosonde data recorded at Wuhan station provides the verification for the reliability of GPS-based CIT technique.

  17. UHF Radar observations at HAARP with HF pump frequencies near electron gyro-harmonics and associated ionospheric effects

    Science.gov (United States)

    Watkins, Brenton; Fallen, Christopher; Secan, James

    Results for HF modification experiments at the HAARP facility in Alaska are presented for experiments with the HF pump frequency near third and fourth electron gyro-harmonics. A UHF diagnostic radar with range resolution of 600 m was used to determine time-dependent altitudes of scattering from plasma turbulence during heating experiments. Experiments were conducted with multiple HF frequencies stepped by 20 kHz above and below the gyro-harmonic values. During times of HF heating the HAARP facility has sufficient power to enhance large-scale ionospheric densities in the lower ionosphere (about 150-200 km altitude) and also in the topside ionosphere (above about 350 km). In the lower ionosphere, time-dependent decreases of the altitude of radar scatter result from electron density enhancements. The effects are substantially different even for relatively small frequency steps of 20 kHz. In all cases the time-varying altitude decrease of radar scatter stops about 5-10 km below the gyro-harmonic altitude that is frequency dependent; we infer that electron density enhancements stop at this altitude where the radar signals stop decreasing with altitude. Experiments with corresponding total electron content (TEC) data show that for HF interaction altitudes above about 170 km there is substantial topside electron density increases due to upward electron thermal conduction. For lower altitudes of HF interaction the majority of the thermal energy is transferred to the neutral gas and no significant topside density increases are observed. By selecting an appropriate HF frequency a little greater than the gyro-harmonic value we have demonstrated that the ionospheric response to HF heating is a self-oscillating mode where the HF interaction altitude moves up and down with a period of several minutes. If the interaction region is above about 170 km this also produces a continuously enhanced topside electron density and upward plasma flux. Experiments using an FM scan with the HF

  18. Electronic learning can facilitate student performance in undergraduate surgical education: a prospective observational study

    Directory of Open Access Journals (Sweden)

    Gorey Thomas

    2005-06-01

    Full Text Available Abstract Background Our institution recently introduced a novel internet accessible computer aided learning (iCAL programme to complement existing surgical undergraduate teaching methods. On graduation of the first full cycle of undergraduate students to whom this resource was available we assessed the utility of this new teaching facility. Method The computer programme prospectively records usage of the system on an individual user basis. We evaluated the utilisation of the web-based programme and its impact on class ranking changes from an entry-test evaluation to an exit examination in surgery. Results 74.4% of students were able to access iCAL from off-campus internet access. The majority of iCAL usage (64.6% took place during working hours (08:00–18:00 with little usage on the weekend (21.1%. Working hours usage was positively associated with improvement in class rank (P = 0.025, n = 148 but out-of hours usage was not (P = 0.306. Usage during weekdays was associated with improved rank (P = 0.04, whereas weekend usage was not (P = 0.504. There were no significant differences in usage between genders (P = 0.3. Usage of the iCAL system was positively correlated with improvement in class rank from the entry to the exit examination (P = 0.046. Students with lower ranks on entry examination, were found to use the computer system more frequently (P = 0.01. Conclusion Electronic learning complements traditional teaching methods in undergraduate surgical teaching. Its is more frequently used by students achieving lower class ranking with traditional teaching methods, and this usage is associated with improvements in class ranking.

  19. Observation of Electron Neutrino Appearance in the NuMI Beam with the NOvA Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Niner, Evan David [Indiana Univ., Bloomington, IN (United States)

    2015-01-01

    NOvA is a long-baseline neutrino oscillation experiment that uses two functionally identical detectors separated by 810 kilometers at locations 14 milliradians off-axis from the NuMI muon neutrino beam at Fermilab. At these locations the beam energy peaks at 2 GeV. This baseline is the longest in the world for an accelerator-based neutrino oscillation experiment, which enhances the sensitivity to the neutrino mass ordering. The experiment studies oscillations of the muon neutrino and anti-neutrino beam that is produced. Both detectors completed commissioning in the summer of 2014 and continue to collect data. One of the primary physics goals of the experiment is the measurement of electron neutrino appearance in the muon neutrino beam which yields measurements of the oscillation parameters sin213, δ , and the neutrino mass ordering within the standard model of neutrino oscillations. This thesis presents the analysis of data collected between February 2014 and May 2015, corresponding to 3.52 X 1020 protons-on-target. In this first analysis NOvA recorded 6 electron neutrino candidates, which is a 3.3σ observation of electron neutrino appearance. The T2K experiment performs the same measurement on a baseline of 295 kilometers and has a 1 σ preference for the normal mass ordering over the inverted ordering over the phase space of the CP violating parameter δ, which is also weakly seen in the NOvA result. By the summer of 2016 NOvA will triple its statistics due to increased beam power and a completed detector. If electron neutrinos continue to be observed at the current rate NOvA will be able to establish a mass ordering preference at a similar confidence level to T2K.

  20. Observation of Electron Neutrino Appearance in the NuMI Beam with the NOvA Experiment

    International Nuclear Information System (INIS)

    NOvA is a long-baseline neutrino oscillation experiment that uses two functionally identical detectors separated by 810 kilometers at locations 14 milliradians off-axis from the NuMI muon neutrino beam at Fermilab. At these locations the beam energy peaks at 2 GeV. This baseline is the longest in the world for an accelerator-based neutrino oscillation experiment, which enhances the sensitivity to the neutrino mass ordering. The experiment studies oscillations of the muon neutrino and anti-neutrino beam that is produced. Both detectors completed commissioning in the summer of 2014 and continue to collect data. One of the primary physics goals of the experiment is the measurement of electron neutrino appearance in the muon neutrino beam which yields measurements of the oscillation parameters sin22θ13, δ, and the neutrino mass ordering within the standard model of neutrino oscillations. This thesis presents the analysis of data collected between February 2014 and May 2015, corresponding to 3.52 x 1020 protons-on-target. In this first analysis NOvA recorded 6 electron neutrino candidates, which is a 3.3σ observation of electron neutrino appearance. The T2K experiment performs the same measurement on a baseline of 295 kilometers and has a 1 σ preference for the normal mass ordering over the inverted ordering over the phase space of the CP violating parameter δ, which is also weakly seen in the NOvA result. By the summer of 2016 NOvA will triple its statistics due to increased beam power and a completed detector. If electron neutrinos continue to be observed at the current rate NOvA will be able to establish a mass ordering preference at a similar confidence level to T2K.

  1. Observation of antideuteron production in electron-positron annihilation at 10 GeV center of mass energy

    International Nuclear Information System (INIS)

    The production of antideuterons has been observed in electron-positron annihilations at center-of-mass energies around 10 GeV. Antideuterons have been identified unambiguously by their energy loss in the drift chamber, their time-of-flight and the pattern of their energy deposition in the shower counters of the ARGUS detector. The production rate in the momentum range (0.6-1.8)GeV/c is (1.6sub(-0.7)sup(+1.0))) X 10-5 per hadronic event. (orig.)

  2. Transmission electron microscope observation of organic–inorganic hybrid thin active layers of light-emitting diodes

    OpenAIRE

    Jitsui, Yusuke; Ohtani, Naoki

    2012-01-01

    We performed transmission electron microscope (TEM) observation of organic–inorganic hybrid thin films fabricated by the sol–gel reaction and used as the active layers of organic light-emitting diodes. The cross-sectional TEM images show that the films consist of a triple-layer structure. To evaluate the composition of these layers, the distribution of atoms in them was measured by energy-dispersive X-ray fluorescence spectroscopy. As a result, most of the organic emissive material, poly(9,9-...

  3. Electron microscopic observations and DNA chain fragmentation studies on apoptosis in bone tumor cells induced by 153Sm—EDTMP

    Institute of Scientific and Technical Information of China (English)

    ZhuShou-Peng; XiaoDong; 等

    1997-01-01

    The morphological changes observed by electron microscopy indicate that after internal irradiation with 153Sm-ESTMP bone tumor cells displayed feature of apoptosis,such as margination of condensed chromatin,chromatin fragmentation.as well as the membranebouded apoptotic bodies formation.THe quantification analysis of fragmentation DNA for bone tumor cells induced by 153Sm-EDTMP shows that the DNA fragmentation is enhanced with the prolongation of internally irradiated time.These characteristics suggest that 153Sm-EDTMP internal irradiation could induce bone tumor cells to go9 to apoptosis.

  4. Electron microscopic observations and DNA chain fragmentation studies on apoptosis in bone tumor cells induced by 153Sm-EDTMP

    International Nuclear Information System (INIS)

    The morphological changes observed by electron microscopy indicate that after internal irradiation with 153Sm-EDTMP bone tumor cells displayed feature of apoptosis, such as margination of condensed chromatin, chromatin fragmentation, as well as the membrane bounded apoptotic bodies formation. The quantification analysis of fragmentation DNA for bone tumor cells induced by 153Sm-EDTMP shows that the DNA fragmentation is enhanced with the prolongation of internally irradiated time. These characteristics suggest that 153Sm-EDTMP internal irradiation could induce bone tumor cells to go to apoptosis

  5. Observation of lens aberrations for high resolution electron microscopy II: Simple expressions for optimal estimates

    International Nuclear Information System (INIS)

    This paper lists simple closed-form expressions estimating aberration coefficients (defocus, astigmatism, three-fold astigmatism, coma / misalignment, spherical aberration) on the basis of image shift or diffractogram shape measurements as a function of injected beam tilt. Simple estimators are given for a large number of injected tilt configurations, optimal in the sense of least-squares fitting of all the measurements, and so better than most reported previously. Standard errors are given for most, allowing different approaches to be compared. Special attention is given to the measurement of the spherical aberration, for which several simple procedures are given, and the effect of foreknowledge of this on other aberration estimates is noted. Details and optimal expressions are also given for a new and simple method of analysis, requiring measurements of the diffractogram mirror axis direction only, which are simpler to make than the focus and astigmatism measurements otherwise required. - Highlights: • Optimal estimators for CTEM lens aberrations are more accurate and/or use fewer observations. • Estimators have been found for defocus, astigmatism, three-fold astigmatism, coma and spherical aberration. • Estimators have been found relying on diffractogram shape, image shift and diffractogram orientation only, for a variety of beam tilts. • The standard error for each estimator has been found

  6. Observation of lens aberrations for high resolution electron microscopy II: Simple expressions for optimal estimates

    Energy Technology Data Exchange (ETDEWEB)

    Saxton, W. Owen, E-mail: wos1@cam.ac.uk

    2015-04-15

    This paper lists simple closed-form expressions estimating aberration coefficients (defocus, astigmatism, three-fold astigmatism, coma / misalignment, spherical aberration) on the basis of image shift or diffractogram shape measurements as a function of injected beam tilt. Simple estimators are given for a large number of injected tilt configurations, optimal in the sense of least-squares fitting of all the measurements, and so better than most reported previously. Standard errors are given for most, allowing different approaches to be compared. Special attention is given to the measurement of the spherical aberration, for which several simple procedures are given, and the effect of foreknowledge of this on other aberration estimates is noted. Details and optimal expressions are also given for a new and simple method of analysis, requiring measurements of the diffractogram mirror axis direction only, which are simpler to make than the focus and astigmatism measurements otherwise required. - Highlights: • Optimal estimators for CTEM lens aberrations are more accurate and/or use fewer observations. • Estimators have been found for defocus, astigmatism, three-fold astigmatism, coma and spherical aberration. • Estimators have been found relying on diffractogram shape, image shift and diffractogram orientation only, for a variety of beam tilts. • The standard error for each estimator has been found.

  7. Scanning electron microscopical observation of an osteoblast/osteoclast co-culture on micropatterned orthopaedic ceramics.

    Science.gov (United States)

    Halai, Mansur; Ker, Andrew; Meek, Rm Dominic; Nadeem, Danish; Sjostrom, Terje; Su, Bo; McNamara, Laura E; Dalby, Matthew J; Young, Peter S

    2014-01-01

    In biomaterial engineering, the surface of an implant can influence cell differentiation, adhesion and affinity towards the implant. On contact with an implant, bone marrow-derived mesenchymal stromal cells demonstrate differentiation towards bone forming osteoblasts, which can improve osteointegration. The process of micropatterning has been shown to improve osteointegration in polymers, but there are few reports surrounding ceramics. The purpose of this study was to establish a co-culture of bone marrow-derived mesenchymal stromal cells with osteoclast progenitor cells and to observe the response to micropatterned zirconia toughened alumina ceramics with 30 µm diameter pits. The aim was to establish whether the pits were specifically bioactive towards osteogenesis or were generally bioactive and would also stimulate osteoclastogenesis that could potentially lead to osteolysis. We demonstrate specific bioactivity of micropatterns towards osteogenesis, with more nodule formation and less osteoclastogenesis compared to planar controls. In addition, we found that that macrophage and osteoclast-like cells did not interact with the pits and formed fewer full-size osteoclast-like cells on the pitted surfaces. This may have a role when designing ceramic orthopaedic implants. PMID:25383174

  8. HF radar observations of E region plasma irregularities produced by oblique electron streaming

    International Nuclear Information System (INIS)

    Data obtained with the Applied Physics Laboratory HF radar located in Goose Bay, Labrador, have been used to determine the characteristic features of high-latitude ionospheric irregularities at decameter wavelengths. In this paper, we describe a set of four events exhibiting particular characteristics. These observations took place in the postmidnight sector at E region altitudes. The scanning capabilities of the radar indicated that arclike regions of irregularities were moving approximately along L contours with a drift velocity of the order of 200 m/s or less. For periods of a few minutes to a few tens of minutes, localized regions of irregularities exhibiting high Doppler velocities (350 to 650 m/s) and large signal to noise ratios appeared within the radar arcs. Among the high Doppler velocity signals, two distinct types have been identified. Both types can be present simultaneously. One type is distributed between 320 and 550 m/s and has an average value of 445 m/s, while the other is distributed between 500 and 650 m/s and has an average value of 580 m/s. If one assumes the lower of the high-velocity signals to be the ion acoustic velocity C/sub s/, the higher velocity can be interpreted as electrostatic ion cyclotron (EIC) waves produced by NO+ ions. These EIC waves follow perfectly the dispersion relation established from the fluid approximation ω/sub r/ = (Ω2/sub i/+k2 C2/sub s/)/sup 1/2/. The radar echoes with low Doppler velocities are associated with irregularities produced by the gradient drift instability which presumably was operative at the top of the E layer

  9. Electronics

    International Nuclear Information System (INIS)

    Some of the electronic equipment used in pulse counting and mean current radiation detection systems is described. This includes the high voltage supply, amplifier, amplitude discriminator, scalers or counters, ratemeters, single-channel pulse height analyser, multi-channel pulse height analyser, d.c. amplifiers, coincidence and anticoincidence units and gain stabilisers

  10. Emulsion chamber observations of primary cosmic-ray electrons in the energy range 30-1000 GeV

    Science.gov (United States)

    Nishimura, J.; Fujii, M.; Taira, T.; Aizu, E.; Hiraiwa, H.; Kobayashi, T.; Niu, K.; Ohta, I.; Golden, R. L.; Koss, T. A.

    1980-01-01

    The results of a series of emulsion exposures, beginning in Japan in 1968 and continued in the U.S. since 1975, which have yielded a total balloon-altitude exposure of 98,700 sq m sr s, are presented. The data are discussed in terms of several models of cosmic-ray propagation. Interpreted in terms of the energy-dependent leaky-box model, the spectrum results suggest a galactic electron residence time of 1.0(+2.0, -0.5) x 10 to the 7th yr, which is consistent with results from Be-10 observations. Finally, the possibility that departures from smooth power law behavior in the spectrum due to individual nearby sources will be observable in the energy range above 1 TeV is discussed.

  11. Earthquake Related Variation of Total Electron Content in Ionosphere over Chinese Mainland Derived from Observations of a Nationwide GNSS Network

    Science.gov (United States)

    Gan, Weijun

    2016-07-01

    Crustal Movement Observation Network of China (CMONOC) is a key national scientific infrastructure project carried out during 1997-2012 with 2 phases. The network is composed of 260 continuously observed GNSS stations (CORS) and 2081 campaign mode GNSS stations, with the main purpose to monitor the crustal movement, perceptible water vapor (PWV), total electron content (TEC), and many other tectonic and environmental elements around mainland China, by mainly using the Global Navigation Satellite System (GNSS) technology. Here, based on the GNSS data of 260 CORS of COMNOC for about 5 years, we investigated the characteristics of TEC in ionosphere over Chinese Mainland and discussed if there was any abnormal change of TEC before and after a big earthquake. our preliminary results show that it is hard to see any convincing precursor of TEC before a big earthquake. However, the huge energy released by a big earthquake can obviously disturb the TEC over meizoseismal area.

  12. Transmon-based simulator of nonlocal electron-phonon coupling: A platform for observing sharp small-polaron transitions

    Science.gov (United States)

    Stojanović, Vladimir M.; Vanević, Mihajlo; Demler, Eugene; Tian, Lin

    2014-04-01

    We propose an analog superconducting quantum simulator for a one-dimensional model featuring momentum-dependent (nonlocal) electron-phonon couplings of Su-Schrieffer-Heeger and "breathing-mode" types. Because its corresponding coupling vertex function depends on both the electron and phonon quasimomenta, this model does not belong to the realm of validity of the Gerlach-Löwen theorem that rules out any nonanalyticities in single-particle properties. The superconducting circuit behind the proposed simulator entails an array of transmon qubits and microwave resonators. By applying microwave driving fields to the qubits, a small-polaron Bloch state with an arbitrary quasimomentum can be prepared in this system within times several orders of magnitude shorter than the typical qubit decoherence times. We demonstrate that—by varying the externally tunable parameters—one can readily reach the critical coupling strength required for observing the sharp transition from a nondegenerate (single-particle) ground state corresponding to zero quasimomentum (Kgs=0) to a twofold-degenerate small-polaron ground state at nonzero quasimomenta Kgs and -Kgs. Through exact numerical diagonalization of our effective Hamiltonian, we show how this nonanalyticity is reflected in the relevant single-particle properties (ground-state energy, quasiparticle residue, average number of phonons). We also show that the proposed setup provides an ideal testbed for studying the nonequilibrium dynamics of small-polaron formation in the presence of strongly momentum-dependent electron-phonon interactions.

  13. Dramatic enhancement of fullerene anion formation in polymer solar cells by thermal annealing: Direct observation by electron spin resonance

    International Nuclear Information System (INIS)

    Using electron spin resonance (ESR), we clarified the origin of the efficiency degradation of polymer solar cells containing a lithium-fluoride (LiF) buffer layer created by a thermal annealing process after the deposition of an Al electrode (post-annealing). The device structure was indium-tin-oxide/ poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate)/poly (3-hexylthiophene):phenyl-C61-butyric acid methyl ester (P3HT:PCBM)/LiF/Al. Three samples consisting of quartz/P3HT:PCBM/LiF/Al, quartz/P3HT:PCBM/Al, and quartz/PCBM/LiF/Al were investigated and compared. A clear ESR signal from radical anions on the PCBM was observed after LiF/Al was deposited onto a P3HT:PCBM layer because of charge transfer at the interface between the PCBM and the LiF/Al, which indicated the formation of PCBM−Li+ complexes. The number of radical anions on the PCBM was enhanced remarkably by the post-annealing process; this enhancement was caused by the surface segregation of PCBM and by the dissociation of LiF at the Al interface by the post-annealing process. The formation of a greater number of anions enhanced the electron scattering, decreased the electron-transport properties of the PCBM molecules, and caused an energy-level shift at the interface. These effects led to degradation in the device performance.

  14. Phase transitions in a LiMn2O4 nanowire battery observed by operando electron microscopy.

    Science.gov (United States)

    Lee, Soyeon; Oshima, Yoshifumi; Hosono, Eiji; Zhou, Haoshen; Kim, Kyungsu; Chang, Hansen M; Kanno, Ryoji; Takayanagi, Kunio

    2015-01-27

    Fast charge-discharge process has been reported to give a high capacity loss. A nanobattery consisting of a single LiMn2O4 nanowire cathode, ionic liquid electrolyte and lithium titanium oxide anode was developed for in situ transmission electron microscopy. When it was fully charged or discharged within a range of 4 V in less than half an hour (corresponding average C rate: 2.5C), Li-rich and Li-poor phases were observed to be separated by a transition region, and coexisted during whole process. The phase transition region moved reversibly along the nanowire axis which corresponds to the [011] direction, allowing the volume fraction of both phases to change. In the electron diffraction patterns, the Li-rich phase was seen to have the (100) orientation with respect to the incident electron beam, while the Li-poor phase had the (111̅) orientation. The orientation was changed as the transition region moved. However, the nanowire did not fracture. This suggests that a LiMn2O4 nanowire has the advantage of preventing capacity fading at high charge rates. PMID:25513896

  15. Experimental simulation of satellite observations of 100 kHz radio waves from relativistic electron beams above thunderclouds

    Directory of Open Access Journals (Sweden)

    M. Füllekrug

    2011-01-01

    Full Text Available Relativistic electron beams above thunderclouds emit 100 kHz radio waves which illuminate the Earth's atmosphere and near-Earth space. This contribution aims to clarify the physical processes which are relevant for the spatial spreading of the radio wave energy below and above the ionosphere and thereby enables an experimental simulation of satellite observations of 100 kHz radio waves from relativistic electron beams above thunderclouds. The simulation uses the DEMETER satellite which observes 100 kHz radio waves from fifty terrestrial Long Range Aid to Navigation (LORAN transmitters. Their mean luminosity patch in the plasmasphere is a circular area with a radius of 300 km and a power density of 22 μW/Hz as observed at 660 km height above the ground. The luminosity patches exhibit a southward displacement of 450 km with respect to the locations of the LORAN transmitters. The displacement is reduced to 150 km when an upward propagation of the radio waves along the geomagnetic field line is assumed. This residual displacement indicates that the radio waves undergo 150 km sub-ionospheric propagation prior to entering a magnetospheric duct and escaping into near-Earth space. The residual displacement at low (L < 2.14 and high (L > 2.14 geomagnetic latitudes ranges from 100 km to 200 km which suggests that the smaller inclination of the geomagnetic field lines at low latitudes helps to trap the radio waves and to keep them in the magnetospheric duct. Diffuse luminosity areas are observed northward of the magnetic conjugate locations of LORAN transmitters at extremely low geomagnetic latitudes (L < 1.36 in Southeast Asia. This result suggests that the propagation along the geomagnetic field lines results in a spatial spreading of the radio wave energy over distances of 1 Mm. The summative assessment of the electric field intensities measured in space show that nadir observations of terrestrial 100 kHz radio waves, e.g., from

  16. Enhanced N2 and O2 densities inferred from EISCAT observations of Pc5 waves and associated electron precipitation

    Science.gov (United States)

    Sydorenko, D.; Rankin, R.; Yau, A. W.

    2016-01-01

    An advanced two-dimensional numerical model of the coupled ionosphere and magnetosphere is used to analyze EISCAT observations of ULF waves that are accompanied by electron precipitation with a wide energy spectrum. The observations show columns of significantly enhanced electron density produced by pulsating precipitation at altitudes between 150 km and 300 km. After each precipitation pulse, the plasma density returns to its initial value within 2 min. Simulations reveal that such a high-density decay rate cannot be reproduced with the composition of neutrals corresponding to a quiet time provided by the Mass Spectrometer Incoherent Scatter model. To explain the rapid density decay rate using the model of the coupled ionosphere and magnetosphere, the density of nitrogen and oxygen molecules was increased, while the density of oxygen atoms was decreased. The modified neutral densities improved not only the decay rate but also the altitude profile of plasma density which had no F2 layer maximum before the wave and the pulsating precipitation started.

  17. Electron spin resonance observation of dehydration-induced spin excitations in quasi-one-dimensional iodo-bridged diplatinum complexes

    Science.gov (United States)

    Tanaka, Hisaaki; Kuroda, Shin-Ichi; Iguchi, Hiroaki; Takaishi, Shinya; Yamashita, Masahiro

    2012-02-01

    Electron spin resonance (ESR) measurements have been performed on a series of quasi-one-dimensional iodo-bridged diplatinum complexes K2[C3H5R(NH3)2][Pt2(pop)4I]·4H2O (pop = P2H2O52-; R = H, CH3, or Cl), where dehydration/rehydration of the crystalline water switches the electronic state reversibly with retention of single crystallinity. We have observed a nonmagnetic nature in as-grown samples, whereas in the dehydrated samples, a clear enhancement of the spin susceptibility has been observed above ˜80 K with the activation energy ranging 50-60 meV. The activated spins originate from isolated Pt3+ state on the chain, as confirmed from the principal g values. Concomitantly, the ESR linewidth exhibits a prominent motional narrowing, suggesting that the activated Pt3+ spins are mobile solitons generated in the doubly degenerate charge-density-wave states of the dehydrated salts.

  18. Electron density and plasma waves in mid-latitude sporadic-E layer observed during the SEEK-2 campaign

    Directory of Open Access Journals (Sweden)

    H. Mori

    2005-10-01

    Full Text Available The SEEK-2 campaign was carried out over Kyushu Island in Japan on 3 August 2002, by using the two sounding rockets of S310-31 and S310-32. This campaign was planned to elucidate generation mechanisms of Quasi-Periodic Echoes (QPEs associated with mid-latitude sporadic-E (Es layers. Electron number densities were successfully measured in the Es layers by using the impedance probe on board two rockets. The plasma waves in the VLF and ELF ranges were also observed on board the S310-32 rocket. Results of electron density measurement showed that there were one or two major peaks in the Es layers along the rockets' trajectories near the altitude of about 10km. There were some smaller peaks associated with the main Es layers in the altitude range from 90 to 120 km. These density peaks were distributed in a very large extent during the SEEK-2 campaign. The Es layer structure is also measured by using the Fixed Bias Probe (FBP, which has a high spatial resolution of several meters (the impedance probe has an altitude resolution of about 400 m. The comparison with the total electron content (TEC measured by the Dual Band Beacon revealed that the Es layer was also modulated in the horizontal direction with the scale size of 30–40 km. It was shown that the QP echoes observed by the ground-based coherent radar come from the major density peak of the Es layer. The plasma wave instrument detected the enhancement of VLF and ELF plasma waves associated with the operation of the TMA release, and also with the passage of the Es layers. Keywords. Ionosphere (Ionospheric irregularities; Midlatitude ionosphere; Plasma temeperature and density

  19. Correlated light and electron microscopy observations of the uterine epithelial cell actin cytoskeleton using fluorescently labeled resin-embedded sections.

    Science.gov (United States)

    Moore, Chad L; Cheng, Delfine; Shami, Gerald J; Murphy, Christopher R

    2016-05-01

    In order to perform correlative light and electron microscopy (CLEM) more precisely, we have modified existing specimen preparation protocols allowing fluorescence retention within embedded and sectioned tissue, facilitating direct observation across length scales. We detail a protocol which provides a precise correlation accuracy using accessible techniques in biological specimen preparation. By combining a pre-embedding uranyl acetate staining step with the progressive lowering of temperature (PLT) technique, a methacrylate embedded tissue specimen is ultrathin sectioned and mounted onto a TEM finder grid for immediate viewing in the confocal and electron microscope. In this study, the protocol is applied to rat uterine epithelial cells in vivo during early pregnancy. Correlative overlay data was used to track changes in filamentous actin that occurs in these cells from fertilization (Day 1) to implantation on Day 6 as part of the plasma membrane transformation, a process essential in the development of uterine receptivity in the rat. CLEM confirmed that the actin cytoskeleton is disrupted as apical microvilli are progressively lost toward implantation, and revealed the thick and continuous terminal web is replaced by a thinner and irregular actin band, with individually distinguishable filaments connecting actin meshworks which correspond with remaining plasma membrane protrusions. PMID:26930006

  20. Observation of resonant transfer and excitation in O5+ + He collisions through high resolution O0 Auger electron spectroscopy

    International Nuclear Information System (INIS)

    In this paper we present new evidence that (resonant transfer and excitation) RTE is an important mechanism for the production of Be-like doubly excited states in energetic collisions of Li-like O5+ ions incident on He. We have measured the cross sections for the production of Auger electrons from the decay of the (1s2s2p2)3D and the (1s2s2p2)1D states in O4+ in high resolution at O0, as a function of the incident ion energy. We observe a resonant increase in the Auger cross section with a maximum at approx.13 MeV and full-width-at-half-maximum of approx.7 MeV. This feature is seen to sit on a non-resonant NTE background, which populates the same intermediate states through a two step capture and excitation process governed by the electron-nucleus Coulomb interaction. 13 ref., 3 figs

  1. Observation of Diffuse Cosmic and Atmospheric Gamma Rays at Balloon Altitudes with an Electron-tracking Compton Camera

    CERN Document Server

    Takada, Atsushi; Nishimura, Hironobu; Ueno, Kazuki; Hattori, Kaori; Kabuki, Shigeto; Kurosawa, Shunsuke; Miuchi, Kentaro; Mizuta, Eiichi; Nagayoshi, Tsutomu; Nonaka, Naoki; Okada, Yoko; Orito, Reiko; Sekiya, Hiroyuki; Takeda, Atsushi; Tanimori, Toru

    2011-01-01

    We observed diffuse cosmic and atmospheric gamma rays at balloon altitudes with the Sub-MeV gamma-ray Imaging Loaded-on-balloon Experiment I (SMILE-I) as the first step toward a future all-sky survey with a high sensitivity. SMILE-I employed an electron-tracking Compton camera comprised of a gaseous electron tracker as a Compton-scattering target and a scintillation camera as an absorber. The balloon carrying the SMILE-I detector was launched from the Sanriku Balloon Center of the Institute of Space and Astronomical Science/Japan Space Exploration Agency on September 1, 2006, and the flight lasted for 6.8 hr, including level flight for 4.1 hr at an altitude of 32-35 km. During the level flight, we successfully detected 420 downward gamma rays between 100 keV and 1 MeV at zenith angles below 60 degrees. To obtain the flux of diffuse cosmic gamma rays, we first simulated their scattering in the atmosphere using Geant4, and for gamma rays detected at an atmospheric depth of 7.0 g cm-2, we found that 50% and 21% ...

  2. High-accuracy diagnostic tool for electron cloud observation in the LHC based on synchronous phase measurements

    Science.gov (United States)

    Esteban Müller, J. F.; Baudrenghien, P.; Mastoridis, T.; Shaposhnikova, E.; Valuch, D.

    2015-11-01

    Electron cloud effects, which include heat load in the cryogenic system, pressure rise, and beam instabilities, are among the main intensity limitations for the LHC operation with 25 ns spaced bunches. A new observation tool was proposed and developed to monitor the e-cloud activity and it has already been used successfully during the LHC run 1 (2010-2012) and it is being intensively used in operation during the start of the LHC run 2 (2015-2018). It is based on the fact that the power loss of each bunch due to e-cloud can be estimated using bunch-by-bunch measurement of the synchronous phase. The measurements were done using the existing beam phase module of the low-level rf control system. In order to achieve the very high accuracy required, corrections for reflection in the cables and for systematic errors need to be applied followed by a post-processing of the measurements. Results clearly show the e-cloud buildup along the bunch trains and its time evolution during each LHC fill as well as from fill to fill. Measurements during the 2012 LHC scrubbing run reveal a progressive reduction in the e-cloud activity and therefore a decrease in the secondary electron yield. The total beam power loss can be computed as a sum of the contributions from all bunches and compared with the heat load deposited in the cryogenic system.

  3. Observation of edge electron heating during 800 MHS lower hybrid fast wave experiments of the Versator II tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Villasenor, J.; Porkolab, M.; Gibson, G.; Colborn, J.; Squire, J. (MIT Plasma Fusion Center and Research Laboratory of Electronics, Cambridge, Massachusetts 02139 (United States))

    1994-10-15

    High power injection of fast waves (P[sub RF][lt]25 kW) at the lower hybrid frequency of 800 MHz using a dielectrically loaded waveguide array has failed to produce any form of current drive or central heating, as shown by measurements using hard x-ray detectors. Miniature retarding potential analyzer probes have detected a thin region at the plasma edge where electrons are heated from 5--10 eV to as high as 100 eV. This region has a spatial extent of [similar to]1 cm in depth and 2 cm in height, and is located just behind the limiter edge along the midplane of the tokamak (coplanar with the antenna array). No heating was observed elsewhere. Parametric decay spectra was also measured at different toroidal and poloidal locations. The parametric decay activity has a measured threshold of P[sub RF][congruent]200 W and corresponds with that of edge electron heating.

  4. High-accuracy diagnostic tool for electron cloud observation in the LHC based on synchronous phase measurements

    CERN Document Server

    Esteban Müller, J F; Shaposhnikova, E; Valuch, D; Mastoridis, T

    2014-01-01

    Electron cloud effects such as heat load in the cryogenic system, pressure rise and beam instabilities are among the main limitations for the LHC operation with 25 ns spaced bunches. A new observation tool was developed to monitor the e-cloud activity and has been successfully used in the LHC during Run 1 (2010-2012). The power loss of each bunch due to the e-cloud can be estimated using very precise bunch-by-bunch measurement of the synchronous phase shift. In order to achieve the required accuracy, corrections for reflection in the cables and some systematic errors need to be applied followed by a post-processing of the measurements. Results clearly show the e-cloud build-up along the bunch trains and its evolution during each LHC fill as well as from fill to fill. Measurements during the 2012 LHC scrubbing run reveal a progressive reduction in the e-cloud activity and therefore a decrease in the secondary electron yield (SEY). The total beam power loss can be computed as a sum of the contributions from all...

  5. Polymorphic transition of solid-fats dispersed systems — its characterization by a novel method and scanning electron microscopy observation

    Science.gov (United States)

    Hirokawa, Norio; Ueda, Masahiro; Harano, Yoshio

    1994-08-01

    Solid-fats dispersed systems, such as margarine, butter and cacao-butter, were characterized by a novel method based on liquid permeation under pressure, for the simultaneous measurement of a solid-content ɛ p and an average diameter dp of solid particles (fats crystals) in them. Further, micro-structures of these systems were observed by a scanning electron microscope (SEM). As the result, it has been clarified that the spherical fats crystals of several μm in size appeared in the initial solid-fats products are agglomerates of fine particles of ca. 0.1 μm and that these fine particles are uniformly redispersed during an annealing treatment accompanying the reduction of ɛ p and dp. It is strongly suggested that this phenomenon is caused by a transition of fat crystals into a more stable polymorph.

  6. Transmission electron microscope observation of organic-inorganic hybrid thin active layers of light-emitting diodes

    Science.gov (United States)

    Jitsui, Yusuke; Ohtani, Naoki

    2012-10-01

    We performed transmission electron microscope (TEM) observation of organic-inorganic hybrid thin films fabricated by the sol-gel reaction and used as the active layers of organic light-emitting diodes. The cross-sectional TEM images show that the films consist of a triple-layer structure. To evaluate the composition of these layers, the distribution of atoms in them was measured by energy-dispersive X-ray fluorescence spectroscopy. As a result, most of the organic emissive material, poly(9,9-dioctyl-fluorene-co- N-4-butylphenyl-diphenylamine (TFB), was found to be distributed in the middle layer sandwiched by SiO and SiO2 layers. The surface SiO layer was fabricated due to the lack of oxygen. This means that the best sol-gel condition was changed due to the TFB doping; thus, the novel best condition should be found.

  7. Electronic transitions of Ho in Pb2Sr2HoCu3O8 observed by inelastic neutron scattering

    Science.gov (United States)

    Soderholm, L.; Loong, C.-K.; Xue, J. S.; Hammonds, J. P.; Greedan, J. E.; Maric, M.

    1993-05-01

    The electronic behavior of the 5I8 Russell Saunders ground multiplet of Ho3+ in Pb2Sr2HoCu3O8 has been investigated using inelastic neutron scattering. We observe ten peaks in the excitation spectra that are associated with crystal field transitions. The peaks are only slightly broader than expected from instrument resolution, indicating that there are no strong interactions between the local Ho f states and the CuO conduction states. Comparing the energies and intensities of the experimental peaks with those expected from modeling convinces us that there are at least three states populated at the temperature of our experiment (15 K), making the assignments of transitions very difficult in the absence of further data.

  8. Electronic transitions of Ho in Pb2Sr2HoCu3O8 observed by inelastic neutron scattering

    International Nuclear Information System (INIS)

    The electronic behavior of the 5I8 Russell Saunders ground multiplet of Ho3+ in Pb2Sr2HoCu3O8 has been investigated using inelastic neutron scattering. We observe ten peaks in the excitation spectra that are associated with crystal field transitions. The peaks are only slightly broader than expected from instrument resolution, indicating that there are no strong interactions between the local Ho f states and the CuO conduction states. Comparing the energies and intensities of the experimental peaks with those expected from modeling convinces us that there are at least three states populated at the temperature of our experiment (15 K), making the assignments of transitions very difficult in the absence of further data

  9. FTIR spectroscopy and scanning electron microscopic analysis of pretreated biosorbent to observe the effect on Cr (VI) remediation.

    Science.gov (United States)

    Kiran, Bala; Rani, Nisha; Kaushik, Anubha

    2016-11-01

    Various chemical and physical treatments have been applied to indigenously isolated cyanobacterial strain, Lyngbya putealis HH-15, to observe the effect on chromium removal capacity. Pretreatment with hydrochloric acid (99.1%) and nitric acid (98.5%) resulted in enhanced chromium removal as compared to untreated control biosorbent (98.1%). Pretreatment with acetic acid (97.9%), methanol (97.0%), calcium chloride (96.0%), hot water (95.2%), and sodium hydroxide (93.9%) did not improve the chromium removal capacity of biosorbent. Fourier transform infrared spectrometry (FTIR) and scanning electron microscopy (SEM) analysis identified changes in biomass functionality and availability after physical and chemical modification-the results of which were in agreement with metal removal studies. In conclusion, this acid-treated biosorbent represents a suitable candidate to replace conventional removal technologies for metal-bearing wastewaters. PMID:27185214

  10. Comment on Phys. Rev. Lett. 108, 191802 (2012): "Observation of Reactor Electron Antineutrino Disappearance in the RENO Experiment"

    CERN Document Server

    Lasserre, Thierry; Cribier, Michel; Collin, Antoine; Durand, Vincent; Fischer, Vincent; Gaffiot, Jonathan; Lhuillier, David; Letourneau, Alain; Vivier, Matthieu

    2012-01-01

    The RENO experiment recently reported the disappearance of reactor electron antineutrinos consistent with neutrino oscillations, with a significance of 4.9 standard deviations. The published ratio of observed to expected number of antineutrinos in the far detector is R=0.920 +-0.009(stat.) +-0.014(syst.) and corresponds to sin^2 2theta13 = 0.113 +-0.013(stat.) +-0.019(syst), using a rate-only analysis. In this letter we reanalyze the data and we find a ratio R=0.903 +-0.01(stat.), leading to sin^2 2theta13 = 0.135. Moreover we show that the sin^2 2theta13 measurement still depend of the prompt high energy bound beyond 4 MeV, contrarily to the expectation based on neutrino oscillation.

  11. In situ reflection high-energy electron diffraction observation of epitaxial LaNiO3 thin films

    Science.gov (United States)

    Chen, P.; Xu, S. Y.; Zhou, W. Z.; Ong, C. K.; Cui, D. F.

    1999-03-01

    Epitaxial LaNiO3 (LNO) thin films were grown on (001) SrTiO3 substrates by laser molecular-beam epitaxy. The growth process of the LNO films was monitored by in situ reflection high-energy electron diffraction (RHEED). Clear RHEED patterns and the intensity oscillation of RHEED were observed during the epitaxial growth process. The morphology of the films was studied by atomic force microscopy. The results show that the films grown by this method have a nanoscale smooth surface with the root-mean-square surface roughness smaller than 7 nm on an area of 1×1 μm2. X-ray diffraction patterns indicate that the crystalline LNO films exhibited preferred (00l) orientation. The resistivity of the thin film is 0.28 mΩ cm at 278 K and 0.06 mΩ cm at 80 K, respectively.

  12. The solar activity dependence of nonmigrating tides in electron density at low and middle latitudes observed by CHAMP and GRACE

    Science.gov (United States)

    Zhou, Yun-Liang; Wang, Li; Xiong, Chao; Lühr, Hermann; Ma, Shu-Ying

    2016-04-01

    In this paper we use more than a decade of in situ electron density observations from CHAMP and GRACE satellites to investigate the solar activity dependence of nonmigrating tides at both low and middle latitudes. The results indicate that the longitudinal patterns of F region electron density vary with season and latitude, which are exhibiting a wavenumber 4 (WN4) pattern around September equinox at low latitudes and WN1/WN2 patterns during local summer at the southern/northern middle latitudes. These wave patterns in the F region ionosphere can clearly be seen during both solar maximum and minimum years. At low latitudes the absolute amplitudes of DE3 (contributing to the WN4 pattern) are found to be highly related to the solar activity, showing larger amplitudes during solar maximum years. Similarly a solar activity dependence can also be found for the absolute amplitudes of D0, DW2 and DE1 (contributing to the WN1 and WN2 pattern) at middle latitudes. The relative amplitudes (normalized by the zonal mean) of these nonmigrating tides at both low and middle altitudes show little dependence on solar activity. We further found a clear modulation by the quasi-biennial oscillation (QBO) of the relative DE3 amplitudes in both satellite observations, which is consistent with the QBO dependence as reported for the E region temperatures and zonal wind. It also supports the strong coupling of the low-latitude nonmigrating tidal activity between the E and F regions. However, the QBO dependence cannot be found for the relative amplitudes of the nonmigrating tides at middle latitudes, which implies that these tides are generated in situ at F region altitudes.

  13. Large enhancement of highly energetic electrons in the outer radiation belt and its transport into the inner radiation belt inferred from MDS-1 satellite observations

    Science.gov (United States)

    Obara, T.; Matsumoto, H.

    2016-03-01

    We have examined a large increase of relativistic electrons in the outer radiation belt and its penetration into the inner radiation belt over slot region using the MDS-1 satellite observations. Result of analyses demonstrates that a large increase took place in the spring and autumn seasons, and we have newly confirmed that the penetration of outer belt electrons to the inner radiation zone took place during the big magnetic storms by examining a pitch angle distribution of the penetrating electrons.

  14. Apoptosis of endothelial cells of cerebral basilar arteries in symptomatic cerebral vasospasm rabbit models Electron microscopic observation

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    BACKGROUND: Recent researchers report that vasospasm is caused by that, on one hand, damage of endothelial cells reduces synthesis and liberation of vessel dilator; on the other hand, defluxion of endothelial cells directly exposure vascular smooth muscles in active materials of vasoconstriction in blood.OBJECTIVE: To study whether apoptosis of cerebrovascular cells occurs in symptomatic cerebral vasospasm (CVS) rabbit models by using transmission electron microscope.DESIGN: Contrast observation.SETTINGS: The Fifth Endemic Area, the 89 Hospital of Chinese PLA; Minimally Invasive Neurosurgical Center, Tangdu Hospital, the Fourth Military Medical University of Chinese PLA.MATERIALS: A total of 24 New Zealand rabbits, of either sex, weighing 2.4 - 3.0 kg, of clear grade, were selected from the Experimental Animal Center of the Fourth Military Medical University of Chinese PLA.JEM-2000EX transmission electron microscope was made in Japan.METHODS: The experiment was carried out in the Laboratory of Anatomy (National Key Laboratory), the Fourth Military Medical University of Chinese PLA from April 2001 to April 2002. ① Preparation of symptomatic CVS models: Eighteen animals which were successfully modeled were randomly divided into experimental group (n =13) and control group (n =5). Animals in the experimental group were poured with blood into cavitas subarachnoidealis; while, animals in the control group were poured with the same volume of saline into cavitas subarachnoidealis. At the 5th day injection, three rabbits selected from the experimental group were anesthetized and perfused into left ventricle. And then, aorta pectoralis and caval vein were blocked by using ring clamp. Cranium was rapidly cut open to obtain cerebral basilar artery and a few of brain tissues. Both of them were fixed for 8 hours. Two rabbits selected from the control group were perfused with the same method to obtain basilar artery and brain tissues and fix. ② After fixation by using optic

  15. Transmission electron microscopic observations of acrosome and head abnormalities in impala (Aepyceros melampus sperm from the Kruger National Park

    Directory of Open Access Journals (Sweden)

    D.J. Ackerman

    1997-01-01

    Full Text Available Sperm morphological features play an important role in semen evaluation. Exposure to a variety of chemical compounds, especially environmental endocrine disrupters, elicit abnormalities in sperm of certain species. Baseline data on ultrastructure of normal sperm as well as abnormalities observed concomitantly, are required before causal links between such substances and abnormalities can be established. Live spermatozoa were collected from the cauda epididymis of 64 impala rams in the Kruger National Park and studied by transmission electron microscopy to document normal sperm features and abnormalities. The following abnormalities of the acrosome and sperm head were documented from micrographs: Loose acrosome in various stages of disintegration, lip forming of the acrosome; bizarre head, crater defect, poor condensation of the nucleus and the Dag defect. The observed abnormalities were very similar to those reported for other members of the Bovidae. Different forms of a hollow sphere, formed by the nucleus and covered by an abnormal acrosome have not previously been described for other species.

  16. Oxidation state of the lower mantle: In situ observations of the iron electronic configuration in bridgmanite at extreme conditions

    Science.gov (United States)

    Kupenko, I.; McCammon, C.; Sinmyo, R.; Cerantola, V.; Potapkin, V.; Chumakov, A. I.; Kantor, A.; Rüffer, R.; Dubrovinsky, L.

    2015-08-01

    We have investigated the electronic configuration of iron in Fe-, Al-containing magnesium silicate perovskite, i.e., bridgmanite, the main component of the lower mantle, at conditions of the deep Earth's interior using the energy domain Synchrotron Mössbauer Source technique. We show that the high ferric iron content observed previously in quenched samples is preserved at high temperatures and high pressures. Our data are consistent with high-spin to intermediate-spin (HS-IS) crossover in Fe2+ at high pressures and ambient temperature. We see no evidence of spin crossover in Fe3+ occupying the A-position of bridgmanite. On laser heating at pressures above ∼40 GPa we observe a new doublet with relative area below 5% which is assigned to Fe3+ in the octahedral (B-site) position in bridgmanite. We conclude that at lower mantle conditions Fe3+ remains predominantly in the HS state, while Fe2+ occurs solely in the IS state.

  17. Cluster observations in the magnetosheath – Part 1: Anisotropies of the wave vector distribution of the turbulence at electron scales

    Directory of Open Access Journals (Sweden)

    J.-M. Bosqued

    2006-12-01

    Full Text Available We analyse the power spectral density δB2 and δE2 of the magnetic and electric fluctuations measured by Cluster 1 (Rumba in the magnetosheath during 23 h, on four different days. The frequency range of the STAFF Spectral Analyser (f=8 Hz to 4 kHz extends from about the lower hybrid frequency, i.e. the electromagnetic (e.m. range, up to about 10 times the proton plasma frequency, i.e. the electrostatic (e.s. range. In the e.m. range, we do not consider the whistler waves, which are not always observed, but rather the underlying, more permanent fluctuations. In this e.m. range, δB2 (at 10 Hz increases strongly while the local angle ΘBV between the magnetic field B and the flow velocity V increases from 0° to 90°. This behaviour, also observed in the solar wind at lower frequencies, is due to the Doppler effect. It can be modelled if we assume that, for the scales ranging from kc/ωpe≃0.3 to 30 (c/ωpe is the electron inertial length, the intensity of the e.m. fluctuations for a wave number k (i varies like k−ν with ν>≃3, (ii peaks for wave vectors k perpendicular to B like |sinθkB|µ with µ>≃100. The shape of the observed variations of δB2 with f and with ΘBV implies that the permanent fluctuations, at these scales, statistically do not obey the dispersion relation for fast/whistler waves or for kinetic Alfvén waves: the fluctuations have a vanishing frequency in the plasma frame, i.e. their phase velocity is negligible with respect to V (Taylor hypothesis. The electrostatic waves around 1 kHz behave differently: δE2 is minimum for ΘBV>≃90°. This can be modelled, still with the Doppler effect, if we assume that, for the scales ranging from k λDe>≃0.1 to 1 (λDe is the Debye length, the intensity of the e.s. fluctuations (i varies like k−ν with ν>≃4, (ii peaks for k parallel to B like |cosθkB|µ with µ>≃100. These e.s. fluctuations may have a vanishing frequency in the plasma frame, or may be ion acoustic

  18. Observation of antisite domain boundaries in Cu2ZnSnS4 by atomic-resolution transmission electron microscopy

    Science.gov (United States)

    Kattan, N. A.; Griffiths, I. J.; Cherns, D.; Fermín, D. J.

    2016-07-01

    Atomic resolution transmission electron microscopy has been used to examine antisite defects in Cu2ZnSnS4 (CZTS) kesterite crystals grown by a hot injection method. High angle annular dark field (HAADF) imaging at sub-0.1 nm resolution, and lower magnification dark field imaging using reflections sensitive to cation ordering, are used to reveal antisite domain boundaries (ADBs). These boundaries, typically 5-20 nm apart, and extending distances of 100 nm or more into the crystals, lie on a variety of planes and have displacements of the type ½[110] or ¼[201], which translate Sn, Cu and Zn cations into antisite positions. It is shown that some ADBs describe a change in the local stoichiometry by removing planes of S and either Cu or Zn atoms, implying that these boundaries can be electrically charged. The observations also showed a marked increase in cation disorder in regions within 1-2 nm of the grain surfaces suggesting that growth of the ordered crystal takes place at the interface with a disordered shell. It is estimated that the ADBs contribute on average ~0.1 antisite defect pairs per unit cell. Although this is up to an order of magnitude less than the highest antisite defect densities reported, the presence of high densities of ADBs that may be charged suggests these defects may have a significant influence on the efficiency of CZTS solar cells.Atomic resolution transmission electron microscopy has been used to examine antisite defects in Cu2ZnSnS4 (CZTS) kesterite crystals grown by a hot injection method. High angle annular dark field (HAADF) imaging at sub-0.1 nm resolution, and lower magnification dark field imaging using reflections sensitive to cation ordering, are used to reveal antisite domain boundaries (ADBs). These boundaries, typically 5-20 nm apart, and extending distances of 100 nm or more into the crystals, lie on a variety of planes and have displacements of the type ½[110] or ¼[201], which translate Sn, Cu and Zn cations into antisite

  19. Biochemical, electron microscopic and immunohistological observations of cationic detergent-extracted cells: detection and improved preservation of microextensions and ultramicroextensions

    Directory of Open Access Journals (Sweden)

    Nakamura Fumihiko

    2001-06-01

    Full Text Available Abstract Background Filopodia, retraction fibers and microvilli, are fragile microextensions of the plasma membrane that are easily damaged by mechanical force during specimen preparation for microscopy. To preserve these structures for electron microscopy glutaraldehyde is generally used, but it often causes antigen masking. By contrast, formaldehyde is generally used for immunofluorescence light microscopy, but few studies have been concerned with the loss of microextensions. Results We demonstrate in biochemical experiments that cultured cells needed to be kept in 4% formaldehyde for at least 60 min at room temperature or for 20 min at 37°C to irreversibly crosslink most of the polypeptides. Also, fragmentation of fragile microextensions was observed after Triton X-100 extraction depending on concentration and extent of crosslinking. We also report on a novel fixation procedure that includes the cationic detergent dodecyltrimethylammonium chloride (DOTMAC. Treatment of NIH3T3 cells with DOTMAC resulted in complete removal of membrane lipids and in good preservation of the cytoskeleton in microextensions as well as preservation of ultramicroextensions of Conclusions Some microextensions were fragmented by the standard Triton X-100 permeabilization method. By contrast, DOTMAC completely extracted membrane lipids while maintaining the cytoskeleton of microextensions. Thus, DOTMAC treatment may provide a valuable new tool for the reliable visualization of previously undetectable or poorly detectable antigens while preserving the actin cytoskeleton of microextensions.

  20. Comparison of mapped and measured total ionospheric electron content using global positioning system and beacon satellite observations

    International Nuclear Information System (INIS)

    Total ionospheric electron contents (TEC) were measured by global positioning system (GPS) dual-frequency receivers developed by the Jet Propulsion Laboratory. The measurements included P-code (precise ranging code) and carrier phase data for six GPS satellites during multiple five-hour observing sessions. A set of these GPS TEC measurements were mapped from the GPS lines of sight to the line of sight of a Faraday beacon satellite by statistically fitting the TEC data to a simple model of the ionosphere. The mapped GPS TEC values were compared with the Faraday rotation measurements. Because GPS transmitter offsets are different for each satellite and because some GPS receiver offsets were uncalibrated, the sums of the satellite and receiver offsets were estimated simultaneously with the TEC in a least squares procedure. The accuracy of this estimation procedure is evaluated indicating that the error of the GPS-determined line of sight TEC can be at or below 1 x 10 to the 16th el/sq cm. Consequently, the current level of accuracy is comparable to the Faraday rotation technique; however, GPS provides superior sky coverage. 15 references

  1. Direct observation of intrinsic Josephson junction characteristics in electron-doped Sm2-xCexCuO4-δ

    Science.gov (United States)

    Kawakami, Tsuyoshi; Suzuki, Minoru

    2007-10-01

    We have investigated the current-voltage (CV) characteristics of the intrinsic Josephson junctions (IJJs) in the electron-doped high- Tc superconductor Sm2-xCexCuO4-δ by using a small mesa structure fabricated on a single crystal surface. It is found that multiple resistive branches, i.e., typical IJJ characteristics, are observed in the CV characteristics when the junction area of a mesa is 10μm2 or less. It is also found that a typical Josephson critical current density Jc is 7.5kA/cm2 at 4.2K for Tc=20.7K . The Josephson penetration depth is experimentally estimated to be 1.0-1.6μm from the size dependence of Jc . Both Jc and Tc are found to decrease with the carrier doping level, as is found for hole-doped Bi2Sr2CaCu2O8+δ in the heavily overdoped region. These results are discussed in relation to the current locking in terms of the coupled Josephson junction stack model.

  2. High-resolution transmission electron microscopy observations on textured rapidly quenched NdFeB permanent magnets

    Science.gov (United States)

    Li, Lin; Luzzi, D. E.; Graham, C. D., Jr.

    1991-11-01

    High-resolution transmission electron microscopy (HRTEM) has been used to examine the microstructures of NdFeB magnets made by rapid solidification. The samples were General Motors MQ-3 magnets, and also MQ-3 magnets that had been recompressed perpendicular to the original compression axis. A major finding is that the Nd-rich grain-boundary phase is not uniformly distributed on all grain boundaries of the Nd2Fe14B phase. Some boundaries are completely clean, and where the Nd-rich phase does appear, its thickness varies widely. The grain-boundary phase (whose structure has been variously identified) is partially ordered at room temperature after slow cooling. Ordered domains and antiphase boundaries have been observed in this phase by HRTEM. Using the Nd2Fe14B fringe spacing as calibration, the lattice parameter of the grain-boundary phase is found to be 5.58 Å. In the completely ordered state, this phase is neither bcc nor fcc; it is simple cubic with a lower-symmetry space group Pm3m.

  3. Observing and Improving Hand Hygiene Compliance: Implementation and Refinement of an Electronic-Assisted Direct-Observer Hand Hygiene Audit Program

    OpenAIRE

    Chen, Luke F.; Carriker, Charlene; Staheli, Russell; Isaacs, Pamela; Elliott, Brandon; Miller, Becky A.; Anderson, Deverick J.; Moehring, Rebekah W.; Vereen, Sheila; Bringhurst, Judie; Rhodes, Lisa; Strittholt, Nancy; Sexton, Daniel J.

    2012-01-01

    We implemented a direct-observer hand hygiene audit program that used trained observers, wireless data entry devices, and an intranet portal. We improved the reliability and utility of the data by standardizing audit processes, regularly retraining auditors, developing an audit guidance tool, and reporting weighted composite hand hygiene compliance scores.

  4. Use of POES SEM-2 observations to examine radiation belt dynamics and energetic electron precipitation into the atmosphere

    OpenAIRE

    Rodger, Craig J.; Clilverd, Mark A.; Green, Janet C.; Lam, Mai Mai

    2010-01-01

    The coupling of the Van Allen radiation belts to the Earth's atmosphere through precipitating particles is an area of intense scientific interest. Currently, there are significant uncertainties surrounding the precipitating characteristics of medium energy electrons (> 20 keV), and even more uncertainties for relativistic electrons. In this paper we examine roughly 10 years of measurements of trapped and precipitating electrons available from the Polar Orbiting Environmental Satellites (POES)...

  5. Statistical study of the location and size of the electron edge of the Low-Latitude Boundary Layer as observed by Cluster at mid-altitudes

    Directory of Open Access Journals (Sweden)

    Y. V. Bogdanova

    2006-10-01

    Full Text Available The nature of particle precipitations at dayside mid-altitudes can be interpreted in terms of the evolution of reconnected field lines. Due to the difference between electron and ion parallel velocities, two distinct boundary layers should be observed at mid-altitudes between the boundary between open and closed field lines and the injections in the cusp proper. At lowest latitudes, the electron-dominated boundary layer, named the "electron edge" of the Low-Latitude Boundary Layer (LLBL, contains soft-magnetosheath electrons but only high-energy ions of plasma sheet origin. A second layer, the LLBL proper, is a mixture of both ions and electrons with characteristic magnetosheath energies. The Cluster spacecraft frequently observe these two boundary layers. We present an illustrative example of a Cluster mid-altitude cusp crossing with an extended electron edge of the LLBL. This electron edge contains 10–200 eV, low-density, isotropic electrons, presumably originating from the solar wind halo population. These are occasionally observed with bursts of parallel and/or anti-parallel-directed electron beams with higher fluxes, which are possibly accelerated near the magnetopause X-line. We then use 3 years of data from mid-altitude cusp crossings (327 events to carry out a statistical study of the location and size of the electron edge of the LLBL. We find that the equatorward boundary of the LLBL electron edge is observed at 10:00–17:00 magnetic local time (MLT and is located typically between 68° and 80° invariant latitude (ILAT. The location of the electron edge shows a weak, but significant, dependence on some of the external parameters (solar wind pressure, and IMF BZ- component, in agreement with expectations from previous studies of the cusp location. The latitudinal extent of the electron edge has been estimated using new multi-spacecraft techniques. The Cluster tetrahedron crosses the electron and ion boundaries of

  6. Reconstruction of energetic electron spectra in the upper atmosphere: balloon observations of auroral X-rays coordinated with measurements from the EISCAT radar

    International Nuclear Information System (INIS)

    Energetic electron precipitation in the auroral zone has been studied using coordinated auroral X-ray measurements from balloons, altitude profiles of the ionospheric electron density measured by the EISCAT radar above the balloons, and cosmic noise absorption data from the Scandinavian riometer network. The data were obtained during the Coordinated EISCAT and Balloon Observations (CEBO) campaign in August 1984. The energy spectral variations of both the X-ray fluxes and the primary precipitating electrons were examined for two precipitation events in the morning sector. As far as reasonably can be concluded from observations of magnetic activity in the auroral zone, and from the temporal development of the energy spectra, the two precipitation events can be interpreted in the frame of present models of energetic electron precipitation on the mordning side of the auroral zone. 96 refs., 70 figs., 11 tabs

  7. State-Selective Quantum Interference Observed in the Recombination of Highly Charged Hg75+···78+ Mercury Ions in an Electron Beam Ion Trap

    International Nuclear Information System (INIS)

    We present experimental data on the state-selective quantum interference between different pathways of photorecombination, namely, radiative and dielectronic recombination, in the KLL resonances of highly charged mercury ions. The interference, observed for well resolved electronic states in the Heidelberg electron beam ion trap, manifests itself in the asymmetry of line shapes, characterized by ''Fano factors,'' which have been determined with unprecedented precision, as well as their excitation energies, for several strong dielectronic resonances

  8. Differential and integral cross sections for excitation of the electronic states of nitric oxide by low energy electron impact: Observation of a {sup 2}{Pi}{sub r} {yields} {sup 2}{Phi} excitation process

    Energy Technology Data Exchange (ETDEWEB)

    Mojarrabi, B.; Campbell, L.; Teubner, P.J.O.; Brunger, M.J. [Flinders Univ. of South Australia, Adelaide, SA (Australia). Electronic Structure of Materials Centre; Cartwright, D.C. [Los Alamos National Lab., NM (United States)

    1996-06-01

    Low energy (E{sub o} = 15 - 40 eV), high energy-resolution, electron energy loss spectra of nitric oxide (NO) have been measured and spectrally deconvolved. This process yielded the first direct absolute differential cross sections (DCS) for electron-impact excitation of the electronic states of the NO molecule. Integration of these DCS give integral cross sections (ICS) which confirm earlier estimates that the magnitudes of the NO ICS are one to two orders smaller that the analogues transitions in N{sub 2} and O{sub 2}. In this letter is presented a clear evidence for the observation of the L/{sup 2}{Phi} electronic state, this being the first time a {sup 2}{Pi}{sub r}{yields}{sup 2}{Phi} excitation transition has been seen in an electron scattering experiment. 38 refs., 3 figs.

  9. In-situ electron and ion measurements and observed gravity wave effects in the polar mesosphere during the MaCWAVE program

    Directory of Open Access Journals (Sweden)

    C. L. Croskey

    2006-07-01

    Full Text Available Langmuir probe electron and ion measurements from four instrumented rockets flown during the MaCWAVE (Mountain and Convective Waves Ascending VErtically program are reported. Two of the rockets were launched from Andøya Rocket Range, Norway, in the summer of 2002. Electron scavenging by ice particulates produced reductions of the electron density in both sharp narrow (≈1–2 km layers and as a broad (≈13 km depletion. Small-scale irregularities were observed in the altitude regions of both types of electron depletion. The scale of the irregularities extended to wavelengths comparable to those used by ground-based radars in observing PMSE. In regions where ice particles were not present, analysis of the spectral signatures provided reasonable estimates of the energy deposition from breaking gravity waves.

    Two more instrumented rockets were flown from Esrange, Sweden, in January 2003. Little turbulence or energy deposition was observed during one flight, but relatively large values were observed during the other flight. The altitude distribution of the observed turbulence was consistent with observations of a semidiurnal tide and gravity wave instability effects as determined by ground-based lidar and radar measurements and by falling sphere measurements of the winds and temperatures (Goldberg et al., 2006; Williams et al., 2006.

  10. Muons for spintronics: Photo-induced conduction electron polarization in n-type GaAs observed by the muonium method

    International Nuclear Information System (INIS)

    The spin-dependent exchange scattering between the muonium (Mu) electron and polarized conduction electrons excited by circularly polarized 831 nm laser light was observed in n-type GaAs with 3.6x1016 cm-3 Si doping at low temperature by measuring a change in the polarization of Mu against the conduction electron polarization (CEP) direction. Correct signal response was confirmed with respect to the laser power. These results are encouraging for the Mu technique to be applied to probe CEP in various spintronics material systems.

  11. Observations of Reduced Electron Gyroscale Fluctuations in National Spherical Torus Experiment H-Mode Plasmas with Large ExB Flow Shear

    International Nuclear Information System (INIS)

    Electron gyroscale fluctuation measurements in National Spherical Torus Experiment H-mode plasmas with large toroidal rotation reveal fluctuations consistent with electron temperature gradient (ETG) turbulence. Large toroidal rotation in National Spherical Torus Experiment plasmas with neutral beam injection generates ExB flow shear rates comparable to ETG linear growth rates. Enhanced fluctuations occur when the electron temperature gradient is marginally stable with respect to the ETG linear critical gradient. Fluctuation amplitudes decrease when the ExB flow shear rate exceeds ETG linear growth rates. The observations indicate that ExB flow shear can be an effective suppression mechanism for ETG turbulence.

  12. Observations of Reduced Electron Gyro-scale Fluctuations in National Spherical Torus Experiment H-mode Plasmas with Large E × B Flow Shear

    Energy Technology Data Exchange (ETDEWEB)

    Smith, D. R.; Kaye, S. M.; Lee, W.; Mazzucato, E.; Park, H. K.; Bell, R. E.; Domier, C. W.; LeBlanc, B. P.; Levinton, F. M.; Luhmann, Jr., N. C.; Menard, J. E.; Yu, H.

    2009-02-13

    Electron gyro-scale fluctuation measurements in National Spherical Torus Experiment (NSTX) H-mode plasmas with large toroidal rotation reveal fluctuations consistent with electron temper- ature gradient (ETG) turbulence. Large toroidal rotation in NSTX plasmas with neutral beam injection generates E × B flow shear rates comparable to ETG linear growth rates. Enhanced fluctuations occur when the electron temperature gradient is marginally stable with respect to the ETG linear critical gradient. Fluctuation amplitudes decrease when the E × B flow shear rate exceeds ETG linear growth rates. The observations indicate E × B flow shear can be an effective suppression mechanism for ETG turbulence.

  13. Observations of Reduced Electron Gyro-scale Fluctuations in National Spherical Torus Experiment H-mode Plasmas with Large E x B Flow Shear

    International Nuclear Information System (INIS)

    Electron gyro-scale fluctuation measurements in National Spherical Torus Experiment (NSTX) H-mode plasmas with large toroidal rotation reveal fluctuations consistent with electron temperature gradient (ETG) turbulence. Large toroidal rotation in NSTX plasmas with neutral beam injection generates E x B flow shear rates comparable to ETG linear growth rates. Enhanced fluctuations occur when the electron temperature gradient is marginally stable with respect to the ETG linear critical gradient. Fluctuation amplitudes decrease when the E x B flow shear rate exceeds ETG linear growth rates. The observations indicate E x B flow shear can be an effective suppression mechanism for ETG turbulence

  14. Magnetite magnetosome and fragmental chain formation of Magnetospirillum magneticum AMB-1: transmission electron microscopy and magnetic observations

    Science.gov (United States)

    Li, Jinhua; Pan, Yongxin; Chen, Guanjun; Liu, Qingsong; Tian, Lanxiang; Lin, Wei

    2009-04-01

    Stable single-domain (SD) magnetite formed intracellularly by magnetotactic bacteria is of fundamental interest in sedimentary and environmental magnetism. In this study, we studied the time course of magnetosome growth and magnetosome chain formation (0-96 hr) in Magnetospirillum magneticum AMB-1 by transmission electron microscopy (TEM) observation and rock magnetism. The initial non-magnetic cells were microaerobically batch cultured at 26 °C in a modified magnetic spirillum growth medium. TEM observations indicated that between 20 and 24 hr magnetosome crystals began to mineralize simultaneously at multiple sites within the cell body, followed by a phase of rapid growth lasting up to 48 hr cultivation. The synthesized magnetosomes were found to be assembled into 3-5 subchains, which were linearly aligned along the long axis of the cell, supporting the idea that magnetosome vesicles were linearly anchored to the inner membrane of cell. By 96 hr cultivation, 14 cubo-octahedral magnetosome crystals in average with a mean grain size of ~44.5 nm were formed in a cell. Low-temperature (10-300 K) thermal demagnetization, room-temperature hysteresis loops and first-order reversal curves (FORCs) were conducted on whole cell samples. Both coercivity (4.7-18.1 mT) and Verwey transition temperature (100-106 K) increase with increasing cultivation time length, which can be explained by increasing grain size and decreasing non-stoichiometry of magnetite, respectively. Shapes of hysteresis loops and FORCs indicated each subchain behaving as an `ideal' uniaxial SD particle and extremely weak magnetostatic interaction fields between subchains. Low-temperature thermal demagnetization of remanence demonstrated that the Moskowitz test is valid for such linear subchain configurations (e.g. δFC/δZFC > 2.0), implying that the test is applicable to ancient sediments where magnetosome chains might have been broken up into short chains due to disintegration of the organic scaffold

  15. Observation of Single Isolated Electrons of High Transverse Momentum in Events with Missing Transverse Energy at the CERN pp Collider

    DEFF Research Database (Denmark)

    Banner, M.; Kofoed-Hansen, O.

    1983-01-01

    We report the results of a search for single isolated electrons of high transverse momentum at the CERN collider. Above 15 GeV/c, four events are found having large missing transverse energy along a direction opposite in azimuth to that of the high-pT electron. Both the configuration of the events...

  16. Observation of electrons produced in association with hard jets and large missing transverse momentum in panti p collisions at √s = 540 GeV

    International Nuclear Information System (INIS)

    Using a sample of events collected by UA2 and corresponding to an integrated luminosity of 116 nb-1, we have searched for electron-'neutrino' pairs in which the transverse momenta of the electron and of the 'neutrino' exceed 15 GeV/c and 25 GeV/c respectively. A total of 35 events are observed in low background conditions. Most events can be interpreted in terms of Wsup(+-) production from QCD processes. Events in which the observation of hard jets makes this interpretation unlikely are described in detail. Possible sources of background contamination are considered. (orig.)

  17. Three-dimensional shapes and distribution of FePd nanoparticles observed by electron tomography using high-angle annular dark-field scanning transmission electron microscopy

    Science.gov (United States)

    Sato, Kazuhisa; Aoyagi, Kenta; Konno, Toyohiko J.

    2010-01-01

    We have studied three-dimensional shapes and distribution of FePd nanoparticles, prepared by electron beam deposition and postdeposition annealing, by means of single-axis tilt tomography using atomic number contrasts obtained by high-angle annular dark-field scanning transmission electron microscopy. Particle size, shape, and locations were reconstructed by weighted backprojection (WBP), as well as by simultaneous iterative reconstruction technique (SIRT). We have also estimated the particle size by simple extrapolation of tilt-series original data sets, which proved to be quite powerful. The results of the two algorithms for reconstruction have been compared quantitatively with those obtained by the extrapolation method and those independently reported by electron holography. It was found that the reconstructed intensity map by WBP contains a small amount of dotlike artifacts, which do not exist in the results by SIRT, and that the particle surface obtained by WBP is rougher than that by SIRT. We demonstrate, on the other hand, that WBP yields a better estimation of the particle size in the z direction than SIRT does, most likely due to the presence of a "missing wedge" in the original data set.

  18. Excitation and decay at Stark-mixed n = 2 states of hydrogen observed in an electron-photon coincidence experiment

    International Nuclear Information System (INIS)

    Measurements have been made of the Lyman-α intensity from Stark-mixed n = 2 states of hydrogen, using the electron-photon coincidence technique at an incident electron energy of 350 eV. The data are related to a combination of excitation amplitudes, including a term which depends on the relative phase of S and P amplitudes. Field-free measurements of lambda and R have also been made at this energy. Comparison is made with several theoretical results. (author)

  19. Long-term observations of keV ion and electron variability in the outer radiation belt from CRRES

    International Nuclear Information System (INIS)

    The distribution of energetic electrons and ions with L-value (LST. These enhancements decay over less than 30 days. There is evidence of a magnetospheric electron and ion acceleration mechanism of considerable strength and efficiency. Very intense periods of activity can lead to the creation of an additional, high-energy belt in the slot region, which persists over a a period of many months. 11 refs., 1 fig

  20. Observation of 690 MV m-1 Electron Accelerating Gradient with a Laser-Driven Dielectric Microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Wootton, K.P.; Wu, Z.; /SLAC; Cowan, B.M.; /Tech-X, Boulder; Hanuka, A.; /SLAC /Technion; Makasyuk, I.V.; /SLAC; Peralta, E.A.; Soong, K.; Byer, R.L.; /Stanford U.; England, R.J.; /SLAC

    2016-06-27

    Acceleration of electrons using laser-driven dielectric microstructures is a promising technology for the miniaturization of particle accelerators. In this work, experimental results are presented of relativistic electron acceleration with 690±100 MVm-1 gradient. This is a record-high accelerating gradient for a dielectric microstructure accelerator, nearly doubling the previous record gradient. To reach higher acceleration gradients the present experiment employs 90 fs duration laser pulses.

  1. The global morphology of the plasmaspheric electron content during Northern winter 2009 based on GPS/COSMIC observation and GSM TIP model results

    Science.gov (United States)

    Klimenko, M. V.; Klimenko, V. V.; Zakharenkova, I. E.; Cherniak, Iu. V.

    2015-04-01

    We studied the contribution of the global plasmaspheric and ionospheric electron content (PEC and IEC) into total electron content (TEC). The experimental PEC was estimated by comparison of GPS TEC observations and FORMOSAT-3/COSMIC radio occultation IEC measurements. Results are retrieved for the winter solstice (January and December 2009) conditions. Global maps of COSMIC-derived IEC, PEC and GPS TEC were compared with Global Self-consistent Model of the Thermosphere, Ionosphere and Protonosphere (GSM TIP) results. In addition, we used GSM TIP model results in order to estimate the contribution of plasmaspheric electron content into TEC value at the different altitudinal regions. The advantages and problems of the outer ionospheric/plasmaspheric parameters (O+/H+ transition height, TEC and electron density at height above F2 layer peak) representation by the IRI (International Reference Ionosphere) model are discussed.

  2. Direct observation of gliding dislocations interactions with defects in irradiated niobium single crystals by means of the high voltage electronic microscopy (HVEM)

    International Nuclear Information System (INIS)

    The interactions of gliding dislocations with defects in irradiated niobium that result in the formation of dislocations channels. The effects in the mechanical behaviour of [941]- and [441]- oriented Nb single crystals due to oxygen addition, neutron and electron irradiation was observed either by macroscopic deformation in a Instron machine or 'in-situ' deformation in the HVEM-High Voltage Electron Microscope. Some specimens were irradiated at IPNS-Intense Pulsed Neutron Source, at 325 K, with 5 x 1017 n/cm2, others were irradiated with electrons in the HVEM. The interactions between gliding dislocations with clusters point defects and dislocations were observed. The primary mechanism for removal of the clusters by the gliding dislocations was the 'sweeping' of the clusters along with the gliding dislocations. As to the point defects, they were 'swept' by the gliding dislocations and left as aligned loops close to the intersections of the gliding dislocations with the upper and lower specimen surfaces. For the illustration of this phenomena, a schematic drawing was made. The mechanism of 'bowing-out' interaction of dislocations with defect clusters was also observed. The reported anomalous slip observed to operate in the [941]- oriented Nb was also directly observed and a qualitive explanation along with a schematic drawing was proposed. This would explain the softenig observed after the yield stress in the [941]- oriented Nb deformed in the Instron machine. (Author)

  3. TRANS4: a new coupled electron/proton transport code – comparison to observations above Svalbard using ESR, DMSP and optical measurements

    Directory of Open Access Journals (Sweden)

    W. F. Denig

    2007-03-01

    Full Text Available We present for the first time a numerical kinetic/fluid code for the ionosphere coupling proton and electron effects. It solves the fluid transport equations up to the eighth moment, and the kinetic equations for suprathermal particles. Its new feature is that for the latter, both electrons and protons are taken into account, while the preceding codes (TRANSCAR only considered electrons. Thus it is now possible to compute in a single run the electron and ion densities due to proton precipitation. This code is successfully applied to a multi-instrumental data set recorded on 22 January 2004. We make use of measurements from the following set of instruments: the Defence Meteorological Satellite Program (DMSP F-13 measures the precipitating particle fluxes, the EISCAT Svalbard Radar (ESR measures the ionospheric parameters, the thermospheric oxygen lines are measured by an all-sky camera and the Hα line is given by an Ebert-Fastie spectrometer located at Ny-Ålesund. We show that the code computes the Hα spectral line profile with an excellent agreement with observations, providing some complementary information on the physical state of the atmosphere. We also show the relative effects of protons and electrons as to the electron densities. Computed electron densities are finally compared to the direct ESR measurements.

  4. Primary oral Penicillium marneffei infection diagnosed by PCR-based molecular identification and transmission electron microscopic observation from formalin-fixed paraffin-embedded tissues

    OpenAIRE

    Hua, Xia; Zhang, Ruifeng; Yang, Hanjun; Song LEI; Zhang, Yizhi; Ran, Yuping

    2012-01-01

    We report a case of primary oral Penicillium marneffei infection in a 39-year-old man without HIV infection. Although fungal culture was negative, the patient was finally confirmed to have P. marneffei infection by PCR-based molecular identification and transmission electron microscopic observation from formalin-fixed, paraffin-embedded tissues. The patient was cured with taking itraconazole for 3 months.

  5. Electronic Excited State and Vibrational Dynamics of Water Solution of Cytosine Observed by Time-resolved Transient Absorption Spectroscopy with Sub-10fs Deep Ultraviolet Laser Pules

    Directory of Open Access Journals (Sweden)

    Kobayashi Takayoshi.

    2013-03-01

    Full Text Available Time-resolved transient absorption spectroscopy for water solution of cytosine with sub-10fs deep ultraviolet laser pulse is reported. Ultrafast electronic excited state dynamics and coherent molecular vibrational dynamics are simultaneously observed and their relaxation mechanisms are discussed.

  6. Observing Tin-Lead Alloys by Scanning Electron Microscopy: A Physical Chemistry Experiment Investigating Macro-Level Behaviors and Micro-Level Structures

    Science.gov (United States)

    Wang, Yue; Xu, Xinhua; Wu, Meifen; Hu, Huikang; Wang, Xiaogang

    2015-01-01

    Scanning electron microscopy (SEM) was introduced into undergraduate physical chemistry laboratory curriculum to help students observe the phase composition and morphology characteristics of tin-lead alloys and thus further their understanding of binary alloy phase diagrams. The students were captivated by this visual analysis method, which…

  7. Density and temperature of energetic electrons in the Earth's magnetotail derived from high-latitude GPS observations during the declining phase of the solar cycle

    Directory of Open Access Journals (Sweden)

    M. H. Denton

    2011-10-01

    Full Text Available Single relativistic-Maxwellian fits are made to high-latitude GPS-satellite observations of energetic electrons for the period January 2006–November 2010; a constellation of 12 GPS space vehicles provides the observations. The derived fit parameters (for energies ~0.1–1.0 MeV, in combination with field-line mapping on the nightside of the magnetosphere, provide a survey of the energetic electron density and temperature distribution in the magnetotail between McIlwain L-values of L=6 and L=22. Analysis reveals the characteristics of the density-temperature distribution of energetic electrons and its variation as a function of solar wind speed and the Kp index. The density-temperature characteristics of the magnetotail energetic electrons are very similar to those found in the outer electron radiation belt as measured at geosynchronous orbit. The energetic electron density in the magnetotail is much greater during increased geomagnetic activity and during fast solar wind. The total electron density in the magnetotail is found to be strongly correlated with solar wind speed and is at least a factor of two greater for high-speed solar wind (VSW=500–1000 km s−1 compared to low-speed solar wind (VSW=100–400 km s−1. These results have important implications for understanding (a how the solar wind may modulate entry into the magnetosphere during fast and slow solar wind, and (b if the magnetotail is a source or a sink for the outer electron radiation belt.

  8. Evaluating the Uncertainties in the Electron Temperature and Radial Speed Measurements Using White Light Corona Eclipse Observations

    Science.gov (United States)

    Reginald, Nelson L.; Davilla, Joseph M.; St. Cyr, O. C.; Rastaetter, Lutz

    2014-01-01

    We examine the uncertainties in two plasma parameters from their true values in a simulated asymmetric corona. We use the Corona Heliosphere (CORHEL) and Magnetohydrodynamics Around the Sphere (MAS) models in the Community Coordinated Modeling Center (CCMC) to investigate the differences between an assumed symmetric corona and a more realistic, asymmetric one. We were able to predict the electron temperatures and electron bulk flow speeds to within +/-0.5 MK and +/-100 km s(exp-1), respectively, over coronal heights up to 5.0 R from Sun center.We believe that this technique could be incorporated in next-generation white-light coronagraphs to determine these electron plasma parameters in the low solar corona. We have conducted experiments in the past during total solar eclipses to measure the thermal electron temperature and the electron bulk flow speed in the radial direction in the low solar corona. These measurements were made at different altitudes and latitudes in the low solar corona by measuring the shape of the K-coronal spectra between 350 nm and 450 nm and two brightness ratios through filters centered at 385.0 nm/410.0 nm and 398.7 nm/423.3 nm with a bandwidth of is approximately equal to 4 nm. Based on symmetric coronal models used for these measurements, the two measured plasma parameters were expected to represent those values at the points where the lines of sight intersected the plane of the solar limb.

  9. Observations on the post-mortem investigation of electron beam welds and other micro-structural features of JET Hypervapotrons

    International Nuclear Information System (INIS)

    A metallurgical post-mortem investigation has been carried out on Mark 1 Hypervapotron elements from the Joint European Tokamak (JET), with the aim of aiding engineers in improving the future design of such high heat flux (HHF) component. Optical and electron microscopy and X-ray techniques have been utilised. Work has predominately focused on the electron beam (EB) welded and vacuum brazed joints of the Hypervapotron. Scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX) has been used to assess the chemical composition while micro and nano indentation testing has been used to study the hardness profiles of these joints. Poor quality control of the vacuum brazing process resulted in nickel based filler material, contaminating internal surfaces. Variable penetration and entrapped voids in the EB welds suggested weld spiking occurred during the joining process. Details of these findings and a critical assessment of the potential implications are given where appropriate.

  10. MeV gamma-ray Compton camera using a gaseous electron tracker for background-suppressed observation

    Science.gov (United States)

    Takada, A.; Tanimori, T.; Kubo, H.; Parker, J. D.; Mizumoto, T.; Mizumura, Y.; Sawano, T.; Nakamura, K.; Matsuoka, Y.; Komura, S.; Nakamura, S.; Oda, M.; Miuchi, K.; Kurosawa, S.

    2014-07-01

    As a next generation MeV gamma-ray telescope, we develop an electron-tracking Compton camera (ETCC) that consists of a gaseous electron tracker surrounded by pixel scintillator arrays. The tracks of the Compton-recoil electron measured by the tracker restrict the incident gamma-ray direction to an arc region on the sky and reject background by using the energy loss rate dE/dx and a Compton-kinematics test. In 2013, we constructed, for a balloon experiment, a 30-cm-cubic ETCC with an effective area of ~1 cm2 for detecting sub-MeV gamma rays (5 σ detection of the Crab Nebula for 4 h). In future work, we will extend this ETCC to an effective area of ~10 cm2. In the present paper, we report the performance of the current ETCC.

  11. Observation of transverse and longitudinal modes in non-neutral electron clouds confined in a magnetic mirror

    International Nuclear Information System (INIS)

    Electrostatic modes on non-neutral electron clouds confined in a magnetic mirror field have been investigated. The cloud contains 2 x 1011 electrons at an average kinetic energy of 0.3 MeV for a magnetic field with a peak intensity of 9 kG at the midplane. It was found that the cloud is moving azimuthally as well as longitudinally. The azimuthal motion has an m=1 spatial nature. The longitudinal modes have a more complicated nature, but their frequency equals that of the azimuthal mode

  12. Observation of deep levels and their hole capture behavior in p-type 4H-SiC epilayers with and without electron irradiation

    International Nuclear Information System (INIS)

    To design SiC bipolar devices, information on deep levels acting as recombination centers is essential. In this paper, we report on the observation of deep levels in p-type 4H-SiC epilayers with and without electron irradiation before and after annealing at 1000 °C. We performed current deep level transient spectroscopy (I-DLTS) for the samples, and the observed deep levels were located near the valence band (with the activation energies less than 0.35 eV) in all the samples. Based on the change of I-DLTS spectra by the electron irradiation or the annealing, we discussed the origins of the deep levels. Then we estimated the time constants of hole capture by the deep levels and discussed the possibility that the observed deep levels behave as recombination centers. (author)

  13. Reconstruction of energetic electron spectra in the upper atmosphere: balloon observations of auroral X-rays coordinated with measurements from the Eiscat radar

    International Nuclear Information System (INIS)

    Energetic electron precipitation in the auroral zone has been studied using coordinated auroral X-ray measurements from balloons, altitude profiles of the ionospheric electron density measured by the EISCAT radar above the balloons, and cosmic noise absorption data from the Scandinavian riometer network. The data were obtained during the coordinated EISCAT and balloon observation campaign in August 1984. A method by which an estimate of the energy spectrum of precipitating energetic electrons can be obtained from balloon measurements of bremsstrahlung X-rays is described. The energy spectral variation of both the X-ray fluxes and the primary precipitating electrons were examined for two precipitation events in the morning sector. As far as reasonably can be concluded from observations of magnetic activity in the auroral zone, and from the temporal development of the energy spectra, the two precipitation events can be interpreted in the frame of present models of energetic electron precipitation on the morning side of the auroral zone. 96 refs

  14. Sudden Intensity Increases and Radial Gradient Changes of Cosmic Ray MeV Electrons and Protons Observed at Voyager 1 beyond 111 AU in the Heliosheath

    CERN Document Server

    Webber, W R; Cummings, A C; Stone, E C; Heikkila, B; Lal, N

    2011-01-01

    Voyager 1 has entered regions of different propagation conditions for energetic cosmic rays in the outer heliosheath beginning at a distance of about 111 AU from the Sun. This conclusion is based on the fact that the low energy 6-14 MeV galactic electron intensity suddenly increased by ~20% over a time period \\leg 10 days and the electron radial intensity gradient abruptly decreased from ~19%/AU to ~8%/AU at 2009.7 at a radial distance of 111.2 AU. A sudden radial gradient change was also observed at this time for >200 MeV protons. The gradients were constant during the time period before and after the electron increase. At about 2011.2 at a distance of 116.6 AU a second abrupt intensity increase was observed, this time for both electrons and protons. The increase for electrons was ~25% and occurred over a time period ~15 days or less. For >200 MeV protons the increase at this time was ~5% (unusually large) and occurred over a longer time period ~50 days. Between about 2011.2 and 2011.6, radial intensity grad...

  15. Radial evolution of nonthermal electron populations in the low-latitude solar wind: Helios, Cluster, and Ulysses Observations

    Czech Academy of Sciences Publication Activity Database

    Štverák, Štěpán; Maksimovic, M.; Trávníček, Pavel M.; Marsch, E.; Fazakerley, A. N.; Scime, E. E.

    2009-01-01

    Roč. 114, - (2009), A05104/1-A05104/15. ISSN 0148-0227 Institutional research plan: CEZ:AV0Z30420517; CEZ:AV0Z10030501 Keywords : solar wind * radial evolution * non-thermal electron properties Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.082, year: 2009

  16. Fermi LAT observations of cosmic-ray electrons from 7 GeV to 1 TeV

    International Nuclear Information System (INIS)

    We present the results of our analysis of cosmic-ray electrons using about 8x106 electron candidates detected in the first 12 months on-orbit by the Fermi Large Area Telescope. This work extends our previously published cosmic-ray electron spectrum down to 7 GeV, giving a spectral range of approximately 2.5 decades up to 1 TeV. We describe in detail the analysis and its validation using beam-test and on-orbit data. In addition, we describe the spectrum measured via a subset of events selected for the best energy resolution as a cross-check on the measurement using the full event sample. Our electron spectrum can be described with a power law ∝E-3.08±0.05 with no prominent spectral features within systematic uncertainties. Within the limits of our uncertainties, we can accommodate a slight spectral hardening at around 100 GeV and a slight softening above 500 GeV.

  17. Scanning electron-microscopic and X-ray-microanalytic observation of diesel-emission particles associated with mutagenicity

    International Nuclear Information System (INIS)

    The particles formed by diesel combustion, which may contain various mutagenic chemicals like polycyclic aromatic hydrocarbons (PAH), are analyzed in their morphology by scanning electron microscopy; their sulfur content is detected by X-ray microanalysis, and mutagenicity is tested with a Salmonella typhimurium bioassay. The authors find a close correlation between sulfur content and mutagenicity of PAH. (Auth.)

  18. Potential-induced electronic structure changes in supercapacitor electrodes observed by in operando soft X-ray spectroscopy.

    Science.gov (United States)

    Bagge-Hansen, Michael; Wood, Brandon C; Ogitsu, Tadashi; Willey, Trevor M; Tran, Ich C; Wittstock, Arne; Biener, Monika M; Merrill, Matthew D; Worsley, Marcus A; Otani, Minoru; Chuang, Cheng-Hao; Prendergast, David; Guo, Jinghua; Baumann, Theodore F; van Buuren, Tony; Biener, Jürgen; Lee, Jonathan R I

    2015-03-01

    The dynamic physiochemical response of a functioning graphene-based aerogel supercapacitor is monitored in operando by soft X-ray spectroscopy and interpreted through ab initio atomistic simulations. Unanticipated changes in the electronic structure of the electrode as a function of applied voltage bias indicate structural modifications across multiple length scales via independent pseudocapacitive and electric double layer charge storage channels. PMID:25503328

  19. Solar flare soft-X-ray spectra from Very Low Frequency observations of ionospheric modulations: Possibility of uninterrupted observation of non-thermal electron-plasma interaction in solar atmosphere.

    Science.gov (United States)

    Palit, Sourav; Chakrabarti, Sandip Kumar; Ray, Suman

    2016-07-01

    The hard and soft X-ray regions of a solar flare spectrum are the manifestation of interaction, namely of bremsstrahlung radiation of the non-thermal electrons moving inward in the denser part of the solar atmosphere with the plasma heated by those energetic electrons. The continuous and uninterrupted knowledge of X-ray photon spectra of flares are of great importance to derive information on the electron acceleration and hence time-evolution of energy transport and physics during solar flares. Satellite observations of solar X-ray spectrum are often limited by the restricted windows in each duty cycle to avoid the interaction of detectors and instruments with harmful energetic charge particles. In this work we have tried to tackle the problem by examining the possibility of using Earth's ionosphere and atmosphere as the detector of such transient events. Earth's lower ionosphere and upper atmosphere are the places where the X-rays and gamma-rays from such astronomical sources are absorbed. The electron-ion production rates due to the ionization of such energetic photons at different heights depend on the intensity and wavelength of the injected spectra and hence vary from one source to another. Obviously the electron and ion density vs. altitude profile has the imprint of the incident photon spectrum. As a preliminary exercise we developed a novel deconvolution method to extract the soft X-ray part of spectra of some solar flares of different classes from the electron density profiles obtained from Very Low Frequency (VLF) observation of lower ionosphere during those events. The method presented here is useful to carry out a similar exercise to infer the higher energy part of solar flare spectra and spectra of more energetic events such as the GRBs, SGRs etc. with the possibilities of probing even lower parts of the atmosphere.

  20. 应用全站仪观测地表移动的新方法%The New Method of Surface Movement Observation with Electronic Total Station

    Institute of Scientific and Technical Information of China (English)

    刘剑刚

    2015-01-01

    The paper based on the requirement of surface movement observation data require effectiveness and accuracy, it explores the prac-ticality of surface movement with Electronic Total Station, starting from the Electronic Total Station itself strong distance, angle measurement capabilities and internal data processing system. And it assesses sources of error, the accuracy assessment and adjustment method based on the characteristics of surface movement observation data with Electronic Total Station. The research results provide the theoretical support data analysis methods for observations of surface movement with Electronic Total Station.%地表移动观测数据的获取讲求实效性和精确性,本文以此为基础,从全站仪自身强大的距离、角度测量能力和内部数据处理系统出发,探讨了全站仪在地表移动观测中的实用性,并基于数据获取方式和数据特点评定了全站仪地表移动观测数据的误差来源、精度评定和平差方法。为全站仪地表移动观测的实施提供理论支撑和数据分析方法。