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Sample records for experimental study electronic

  1. Experimental studies of electron capture

    International Nuclear Information System (INIS)

    Pedersen, E.H.

    1983-01-01

    This thesis discusses the main results of recent experimental studies of electron capture in asymmetric collisions. Most of the results have been published, but the thesis also contains yet unpublished data, or data presented only in unrefereed conference proceedings. The thesis aims at giving a coherent discussion of the understanding of the experimental results, based first on simple qualitative considerations and subsequently on quantitative comparisons with the best theoretical calculations currently available. (Auth.)

  2. Experimental study on secondary electron emission characteristics of Cu

    Science.gov (United States)

    Liu, Shenghua; Liu, Yudong; Wang, Pengcheng; Liu, Weibin; Pei, Guoxi; Zeng, Lei; Sun, Xiaoyang

    2018-02-01

    Secondary electron emission (SEE) of a surface is the origin of the multipacting effect which could seriously deteriorate beam quality and even perturb the normal operation of particle accelerators. Experimental measurements on secondary electron yield (SEY) for different materials and coatings have been developed in many accelerator laboratories. In fact, the SEY is just one parameter of secondary electron emission characteristics which include spatial and energy distribution of emitted electrons. A novel experimental apparatus was set up in China Spallation Neutron Source, and an innovative method was applied to obtain the whole characteristics of SEE. Taking Cu as the sample, secondary electron yield, its dependence on beam injection angle, and the spatial and energy distribution of secondary electrons were achieved with this measurement device. The method for spatial distribution measurement was first proposed and verified experimentally. This contribution also tries to give all the experimental results a reasonable theoretical analysis and explanation.

  3. Experimental study on generation of large area uniform electron beam

    International Nuclear Information System (INIS)

    Tang Ying; Yi Aiping; Liu Jingru; Qian Hang; Huang Xin; Yu Li; Su Jiancang; Ding Zhenjie; Ding Yongzhong; Yu Jianguo

    2007-01-01

    In the experiment of gas laser pumped by electron beam, large area uniform electron beam is important to generate high efficiency laser output. The experimental study on generation of large area uniform electron beam with SPG-200 pulsed power generator is introduced. SPG-200 is an all-solid-state components pulsed power generator based on SOS, and its open voltage is more than 350 kV. The cathode have the area of 24 mm x 294 mm, and the anode-cathode(A-C)gap spacing is adjustable from 0 to 49 mm. The electron beam of cathode emission is transported to the laser chamber through the diode pressure foil, which sepa-rates the vacuum chamber from the laser chamber. Velvet and graphite cathodes are studied, each generates large area electron beam. The diode parameters are presented, and the uniformity of e-beam is diagnosed. The experimental results show that the diode voltage of the graphite cathode is 240-280 kV, and the diode current is 0.7-1.8 kA. The diode voltage of the velvet cathode is 200-250 kV, and the diode current is 1.5-1.7 kA. The uniformity of the velvet cathode emission is better than that of the graphite cathode. (authors)

  4. Experimental study of parametric dependence of electron-scale turbulence in a spherical tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Y.; Guttenfelder, W.; Kaye, S. M.; Mazzucato, E.; Bell, R. E.; Diallo, A.; LeBlanc, B. P. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Domier, C. W.; Lee, K. C. [University of California at Davis, Davis, California 95616 (United States); Smith, D. R. [University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Yuh, H. [Nova Photonics, Inc., Princeton, New Jersey 08540 (United States)

    2012-05-15

    Electron-scale turbulence is predicted to drive anomalous electron thermal transport. However, experimental study of its relation with transport is still in its early stage. On the National Spherical Tokamak Experiment (NSTX), electron-scale density fluctuations are studied with a novel tangential microwave scattering system with high radial resolution of {+-}2 cm. Here, we report a study of parametric dependence of electron-scale turbulence in NSTX H-mode plasmas. The dependence on density gradient is studied through the observation of a large density gradient variation in the core induced by an edge localized mode (ELM) event, where we found the first clear experimental evidence of density gradient stabilization of electron-gyro scale turbulence in a fusion plasma. This observation, coupled with linear gyro-kinetic calculations, leads to the identification of the observed instability as toroidal electron temperature gradient (ETG) modes. It is observed that longer wavelength ETG modes, k{sub Up-Tack }{rho}{sub s} Less-Than-Or-Equivalent-To 10 ({rho}{sub s} is the ion gyroradius at electron temperature and k{sub Up-Tack} is the wavenumber perpendicular to local equilibrium magnetic field), are most stabilized by density gradient, and the stabilization is accompanied by about a factor of two decrease in electron thermal diffusivity. Comparisons with nonlinear ETG gyrokinetic simulations show ETG turbulence may be able to explain the experimental electron heat flux observed before the ELM event. The collisionality dependence of electron-scale turbulence is also studied by systematically varying plasma current and toroidal field, so that electron gyroradius ({rho}{sub e}), electron beta ({beta}{sub e}), and safety factor (q{sub 95}) are kept approximately constant. More than a factor of two change in electron collisionality, {nu}{sub e}{sup *}, was achieved, and we found that the spectral power of electron-scale turbulence appears to increase as {nu}{sub e}{sup *} is

  5. Experimental study of fast electron transport in dense plasmas

    International Nuclear Information System (INIS)

    Vaisseau, Xavier

    2014-01-01

    The framework of this PhD thesis is the inertial confinement fusion for energy production, in the context of the electron fast ignition scheme. The work consists in a characterization of the transport mechanisms of fast electrons, driven by intense laser pulses (10 19 - 10 20 W/cm 2 ) in both cold-solid and warm-dense matter. The first goal was to study the propagation of a fast electron beam, characterized by a current density ≥ 10 11 A/cm 2 , in aluminum targets initially heated close to the Fermi temperature by a counter-propagative planar shock. The planar compression geometry allowed us to discriminate the energy losses due to the resistive mechanisms from collisional ones by comparing solid and compressed targets of the same initial areal densities. We observed for the first time a significant increase of resistive energy losses in heated aluminum samples. The confrontation of the experimental data with the simulations, including a complete characterization of the electron source, of the target compression and of the fast electron transport, allowed us to study the time-evolution of the material resistivity. The estimated resistive electron stopping power in a warm-compressed target is of the same order as the collisional one. We studied the transport of the fast electrons generated in the interaction of a high-contrast laser pulse with a hollow copper cone, buried into a carbon layer, compressed by a counter-propagative planar shock. A X-ray imaging system allowed us to visualize the coupling of the laser pulse with the cone at different moments of the compression. This diagnostic, giving access to the fast electron spatial distribution, showed a fast electron generation in the entire volume of the cone for late times of compression, after shock breakout from the inner cone tip. For earlier times, the interaction at a high-contrast ensured that the source was contained within the cone tip, and the fast electron beam was collimated into the target depth by

  6. Theoretical and experimental studies of runaway electrons in the TEXTOR tokamak

    International Nuclear Information System (INIS)

    Abdullaev, S.S.; Finken, K.H.; Wongrach, K.; Willi, O.

    2016-01-01

    Theoretical and experimental studies of runaway electrons in tokamaks and their mitigations, particularly the recent studies performed by a group of the Heinrich-Heine University Duesseldorf in collaboration with the Institute of Energy and Climate Research of the Research Centre (Forschungszentrum) of Juelich are reviewed. The main topics focus on (i) runaway generation mechanisms, (ii) runaway orbits in equilibrium plasma, (iii) transport in stochastic magnetic fields, (iv) diagnostics and investigations of transport of runaway electron and their losses in low density discharges (v) runaway electrons during plasma disruptions, and (vi) runaway mitigation methods. The development of runaway diagnostics enables the measurement of runaway electrons in both the centre and edge of the plasma. The diagnostics provide an absolute runaway energy resolved measurement, the radial decay length of runaway electrons and, the structure and dynamics of runaway electron beams. The new mechanism of runaway electron formation during plasma disruptions is discussed.

  7. Theoretical and experimental studies of runaway electrons in the TEXTOR tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Abdullaev, S.S.; Finken, K.H.; Wongrach, K.; Willi, O.

    2016-07-01

    Theoretical and experimental studies of runaway electrons in tokamaks and their mitigations, particularly the recent studies performed by a group of the Heinrich-Heine University Duesseldorf in collaboration with the Institute of Energy and Climate Research of the Research Centre (Forschungszentrum) of Juelich are reviewed. The main topics focus on (i) runaway generation mechanisms, (ii) runaway orbits in equilibrium plasma, (iii) transport in stochastic magnetic fields, (iv) diagnostics and investigations of transport of runaway electron and their losses in low density discharges (v) runaway electrons during plasma disruptions, and (vi) runaway mitigation methods. The development of runaway diagnostics enables the measurement of runaway electrons in both the centre and edge of the plasma. The diagnostics provide an absolute runaway energy resolved measurement, the radial decay length of runaway electrons and, the structure and dynamics of runaway electron beams. The new mechanism of runaway electron formation during plasma disruptions is discussed.

  8. Experimental studies of VpxB electron linear accelerator

    International Nuclear Information System (INIS)

    Taura, T.; Onihashi, H.; Otsuka, K.; Nishida, Y.; Yugami, N.

    1989-01-01

    In order to demonstrate a new electron linear accelerator an electron beam is accelerated either in the conventional linear accelerator scheme or in the V p xB scheme in a same machine and higher energy gain of about 18 % is observed in the V p xB scheme as is expected from the designed values. The experimental results are compared with the numerical simulation to show reasonable agreement. (author)

  9. Experimental study of intensive electron beam scattering in melting channel

    International Nuclear Information System (INIS)

    Balagura, V.S.; Kurilko, V.I.; Safronov, B.G.

    1988-01-01

    Multiple scattering of an intensive electron beam at 28 keV energy passing through a melting channel in iron targets is experimentally studied. The dependence of scattering on the melting current value is established. The material density in the channel on the basis of the binary collision method is evaluated. It is shown that these density values are of three orders less than the estimations made on the basis of the data on energy losses of electrons in the channel. 6 refs.; 4 figs

  10. Experimental and theoretical study of the electron cascade induced in a gas by laser light

    International Nuclear Information System (INIS)

    Louis-Jacquet, Michel.

    1978-10-01

    In a laser gas interaction experiment, first electrons created by multiphoton ionization of atoms gain sufficient energy in the laser E.M. wave to promote collisional ionization of other atoms. An experimental and theoretical study of the electron-neutral atom inverse bremsstrahlung process and the consecutive electron cascade is presented. The main basic idea is to create an initial electron population and to study its evolution versus the photon density. A Boltzman equation including several collision terms can describe such a plasma. The resolution by a general eigen values method shows that the electron density growth rate is inversely proportionnal to both neutral atom density and laser light illumination. Experimental conditions were defined in order to insure negligible secondary mechanisms (multiphoton ionization, diffusion, recombination, ...). Using a macroscopic description of the interaction, the growth rate can be deduced from the experimental results. Values are in a rather good agreement with the theoretical ones. Moreover evidence is given of influence of the excited atoms on the multiplication process [fr

  11. Experimental Electron Cloud Studies in the CERN Proton Synchrotron

    CERN Document Server

    Mahner, E; Caspers, Friedhelm

    2008-01-01

    Indications for a beam-induced electron cloud build-up are observed since 2000 for the nominal LHC beam in the PS to SPS transfer line and during the last turns before ejection from the PS. A new electron cloud setup was designed, built, and installed in the PS. It contains shielded button-type pickups, a dipole magnet, a vacuum gauge, and a dedicated stripline electrode to experimentally verify the beneficial effect of electron cloud clearing electrodes. During the 2007 run, the electron cloud effect was also clearly observed in the PS and efficient electron cloud suppression has been obtained for negative and positive bias voltages on the clearing electrode. Here, we present electron cloud measurements with different filling patterns and bunch spacings in the PS.

  12. Experimental study of the electron-atom Bremsstrahlung emission in an argon plasma jet

    International Nuclear Information System (INIS)

    Ranson, P.; Vallee, O.; Chapelle, J.

    1977-01-01

    Electron-neutral atom bremsstrahlung is studied between 0.4 μm and 5 μm in a decaying argon plasma jet; in visible and infra-red range, some discrepancies appear between experimental results and theoretical calculations of different authors (Geltman, Stallcop). In the infra-red, the discrepancy can be partly explained because theoretical elastic cross sections are higher than experimental values in the vicinity of the Ramsauer minimum. In the visible range, a very small amount of fast electrons due to superelastic and recombination collisions explain the observed discrepancy [fr

  13. Experimental Study of Electronic Quantum Interference, Photonic Crystal Cavity, Photonic Band Edge Effects for Optical Amplification

    Science.gov (United States)

    2016-01-26

    AFRL-RV-PS- AFRL-RV-PS- TR-2016-0003 TR-2016-0003 EXPERIMENTAL STUDY OF ELECTRONIC QUANTUM INTERFERENCE , PHOTONIC CRYSTAL CAVITY, PHOTONIC BAND...EDGE EFFECTS FOR OPTICAL AMPLIFICATION Shawn-Yu Lin Rensselaer Polytechnic Institute 110 8th Street Troy, New York 12180 26 Jan 2016 Final Report...2014 – 11 Jan 2016 4. TITLE AND SUBTITLE Experimental Study of Electronic Quantum Interference , Photonic Crystal Cavity, Photonic Band Edge Effects

  14. Vibrational and electronic spectra of 2-nitrobenzanthrone: An experimental and computational study

    Science.gov (United States)

    Onchoke, Kefa K.; Chaudhry, Saad N.; Ojeda, Jorge J.

    2016-01-01

    The environmental pollutant 2-nitrobenzanthrone (2-NBA) poses human health hazards, and is formed by atmospheric reactions of NOX gases with atmospheric particulates. Though its mutagenic effects have been studied in biological systems, its comprehensive spectroscopic experimental data are scarce. Thus, vibrational and optical spectroscopic analysis (UV-Vis, and fluorescence) of 2-NBA was studied using both experimental and density functional theory employing B3LYP method with 6-311 + G(d,p) basis set. The scaled theoretical vibrational frequencies show good agreement to experiment to within 5 cm- 1 and NBA, respectively. On the basis of normal coordinate analysis complete assignments of harmonic experimental infrared and Raman bands are made. The influence of the nitro group substitution upon the benzanthrone structure and symmetric CH vibrations, and electronic spectra is noted. This study is useful for the development of spectroscopy-mutagenicity relationships in nitrated polycyclic aromatic hydrocarbons.

  15. Experimental Investigation of Runaway Electron Generation in Textor

    NARCIS (Netherlands)

    R. Jaspers,; Finken, K.H.; Mank, G.; Hoenen, F.; Boedo, J. A.; Cardozo, N. J. L.; Schüller, F. C.

    1993-01-01

    An experimental study of the generation of runaway electrons in TEXTOR has been performed. From the infrared synchrotron radiation emitted by relativistic electrons, the number of runaway electrons can be obtained as a function of time. In low density discharges (n(e)BAR < 1 X 10(19) m-3)

  16. Experimental study of single-electron loss by Ar+ ions in rare-gas atoms

    Science.gov (United States)

    Reyes, P. G.; Castillo, F.; Martínez, H.

    2001-04-01

    Absolute differential and total cross sections for single-electron loss were measured for Ar+ ions on rare-gas atoms in the laboratory energy range of 1.5 to 5.0 keV. The electron loss cross sections for all the targets studied are found to be in the order of magnitude between 10-19 and 10-22 cm2, and show a monotonically increasing behaviour as a function of the incident energy. The behaviour of the total single-electron loss cross sections with the atomic target number, Zt, shows different dependences as the collision energy increases. In all cases the present results display experimental evidence of saturation in the single-electron loss cross section as the atomic number of the target increases.

  17. Atomic holography with electrons and x-rays: Theoretical and experimental studies

    International Nuclear Information System (INIS)

    Len, P.M.

    1997-06-01

    Gabor first proposed holography in 1948 as a means to experimentally record the amplitude and phase of scattered wavefronts, relative to a direct unscattered wave, and to use such a open-quotes hologramclose quotes to directly image atomic structure. But imaging at atomic resolution has not yet been possible in the way he proposed. Much more recently, Szoeke in 1986 noted that photoexcited atoms can emit photoelectron of fluorescent x-ray wavefronts that are scattered by neighboring atoms, thus yielding the direct and scattered wavefronts as detected in the far field that can then be interpreted as holographic in nature. By now, several algorithms for directly reconstructing three-dimensional atomic images from electron holograms have been proposed (e.g. by Barton) and successfully tested against experiment and theory. Very recently, Tegze and Faigel, and Grog et al. have recorded experimental x-ray fluorescence holograms, and these are found to yield atomic images that are more free of the kinds of aberrations caused by the non-ideal emission or scattering of electrons. The basic principles of these holographic atomic imaging methods are reviewed, including illustrative applications of the reconstruction algorithms to both theoretical and experimental electron and x-ray holograms. The author also discusses the prospects and limitations of these newly emerging atomic structural probes

  18. Theoretical and experimental study of image formation in scanning transmission electron microscopy

    International Nuclear Information System (INIS)

    Prunier epouse Mory, Claudie

    1985-01-01

    This thesis contains a theoretical and experimental study of image formation in a dedicated scanning transmission electron microscope (STEM). Using a detailed description of the different optical elements between the field emission source and the specimen, one calculates the shape and size of the primary probe of electrons impinging on the sample. This modelization enables to estimate the spatial resolution in the different imaging or microanalytical modes. The influence of the specimen and the role of the various detectors are taken into account to calculate the point spread function of the instrument in STEM imaging modes. An experimental study of the characteristic properties of phase contrast bright field micrographs and incoherent dark field ones is performed by comparison of digitally recorded images in similar conditions. Spatial resolution, contrast and signal/noise ratio are assessed by correlation methods, Fourier analysis and statistical considerations; one can deduce the optimum focusing conditions. Limits such as the point resolution on quasi-atomic metallic clusters are determined and an analysis of the capabilities of signal mixing concludes this work. Applications are offered in various domains such as the visualisation of small metallic particles, biomolecules and unstained biological sections. (author) [fr

  19. Experimental study of fast electron transport in the framework of fast ignition for inertial fusion

    International Nuclear Information System (INIS)

    Vauzour, B.

    2012-01-01

    The framework of this PhD thesis is the validation of the fast ignition scheme for the nuclear fusion by inertial confinement. It consists in the experimental study of the various processes involved in fast electron beams propagation, produced by intense laser pulses (10 19 W.cm -2 ), through dense matter either solid or compressed. In this work we present the results of three experiments carried out on different laser facilities in order to generate fast electron beams in various conditions and study their propagation in different states of matter, from the cold solid to the warm and dense plasma.The first experiment was performed with a high intensity contrast on the UHI100 laser facility (CEA Saclay). The study of fast electron energy deposition inside thin aluminium targets highlights a strong target heating at shallow depths, where the collective effects are predominant, thus producing a steep temperature profile between front (300 eV) and rear (20 eV) sides over 20μm thickness. A numerical simulation of the experiment shows that this temperature gradient induces the formation of a shock wave, breaking through the rear side of the target and thus leading to increase the thermal emission. The experimental chronometry of the shock breakthrough allowed validating the model of the collective transport of electrons.Two other experiments were dedicated to the study of fast electron beam propagation inside compressed targets. In the first experiment on the LULI2000 laser facility, the plane compression geometry allowed to precisely dissociate the energy losses due to resistive effects from those due to the collisional ones. By comparing our experimental results with simulations, we observed a significative increase of the fast electron beam energy losses with the compression and the target heating to temperatures close to the Fermi temperature. The second experiment, performed in a cylindrical geometry, demonstrated a fast electron beam guiding phenomenon due to

  20. Simulation and experimental studies on electron cloud effects in particle accelerators

    CERN Document Server

    Romano, Annalisa; Cimino, Roberto; Iadarola, Giovanni; Rumolo, Giovanni

    Electron Cloud (EC) effects represent a serious limitation for particle accelerators operating with intense beams of positively charged particles. This Master thesis work presents simulation and experimental studies on EC effects carried out in collaboration with the European Organization for Nuclear Research (CERN) in Geneva and with the INFN-LNF laboratories in Frascati. During the Long Shut- down 1 (LS1, 2013-2014), a new detector for EC measurements has been installed in one of the main magnets of the CERN Proton Synchrotron (PS) to study the EC formation in presence of a strong magnetic field. The aim is to develop a reli- able EC model of the PS vacuum chamber in order to identify possible limitation for the future high intensity and high brightness beams foreseen by Large Hadron Collider (LHC) Injectors Upgrade (LIU) project. Numerical simulations with the new PyECLOUD code were performed in order to quantify the expected signal at the detector under different beam conditions. The experimental activity...

  1. Experimental transmission electron microscopy studies and phenomenological model of bismuth-based superconducting compounds

    International Nuclear Information System (INIS)

    Elboussiri, Khalid

    1991-01-01

    The main part of this thesis is devoted to an experimental study by transmission electron microscopy of the different phases of the superconducting bismuth cuprates Bi_2Sr_2Ca_n_-_1Cu_nO_2_n_+_4. In high resolution electron microscopy, the two types of incommensurate modulation realized in these compounds have been observed. A model of structure has been proposed from which the simulated images obtained are consistent with observations. The medium resolution images correlated with the electron diffraction data have revealed existence of a multi-soliton regime with latent lock in phases of commensurate periods between 4b and 10b. At last, a description of different phases of these compounds as a result of superstructures from a disordered perovskite type structure is proposed (author) [fr

  2. Experimental study of single-electron loss by Ar{sup +} ions in rare-gas atoms

    Energy Technology Data Exchange (ETDEWEB)

    Reyes, P.G. [Facultad de Ciencias, UNAM, Coyoacan (Mexico); Castillo, F. [Instituto de Ciencias Nucleares, UNAM, Coyoacan (Mexico); Martinez, H. [Centro de Ciencias Fisicas, UNAM, Cuernavaca, Morelos (Mexico)]. E-mail: hm@fis.unam.mx

    2001-04-28

    Absolute differential and total cross sections for single-electron loss were measured for Ar{sup +} ions on rare-gas atoms in the laboratory energy range of 1.5 to 5.0 keV. The electron loss cross sections for all the targets studied are found to be in the order of magnitude between 10{sup -19} and 10{sup -22} cm{sup 2}, and show a monotonically increasing behaviour as a function of the incident energy. The behaviour of the total single-electron loss cross sections with the atomic target number, Z{sub t}, shows different dependences as the collision energy increases. In all cases the present results display experimental evidence of saturation in the single-electron loss cross section as the atomic number of the target increases. (author)

  3. Electronic structure of copper phthalocyanine : An experimental and theoretical study of occupied and unoccupied levels

    NARCIS (Netherlands)

    Evangelista, Fabrizio; Carravetta, Vincenzo; Stefani, Giovanni; Jansik, Branislav; Alagia, Michele; Stranges, Stefano; Ruocco, Alessandro

    2007-01-01

    An experimental and theoretical study of the electronic structure of copper phthalocyanine (CuPc) molecule is presented. We performed x-ray photoemission spectroscopy (XPS) and photoabsorption [x-ray absorption near-edge structure (XANES)] gas phase experiments and we compared the results with

  4. Experimental and theoretical studies on X-ray induced secondary electron yields in Ti and TiO2

    International Nuclear Information System (INIS)

    Iyasu, Takeshi; Tamura, Keiji; Shimizu, Ryuichi; Vlaicu, Mihai Aurel; Yoshikawa, Hideki

    2006-01-01

    Generation of X-ray induced secondary electrons in Ti and TiO 2 was studied from both experimental and theoretical approaches, using X-ray photoelectron spectroscopy (XPS) attached to a synchrotron radiation facility and Monte Carlo simulation, respectively. The experiment revealed that the yields of secondary electrons induced by X-rays (electrons/photon) at photon energies to 4950 and 5000eV for Ti and TiO 2 are δ Ti (4950eV)=0.002 and δ Ti (5000eV)=0.014 while those for TiO 2 are δ TiO 2 (4950eV)=0.003 and δ TiO 2 (5000eV)=0.018. A novel approach to obtain the escape depth of secondary electrons has been proposed and applied to Ti and TiO 2 . The approach agreed very well with the experimental data reported so far. The Monte Carlo simulation predicted; δ Ti * (4950eV)=0.002 and δ Ti * (5000eV)=0.011 while δ TiO 2 * (4950eV)=0.003 and δ TiO 2 * (5000eV)=0.015. An experimental examination on the contribution of X-ray induced secondary electrons to photocatalysis in TiO 2 has also been proposed

  5. Experimental and numerical studies of sheet electron beam propagation through a planar wiggler magnet

    International Nuclear Information System (INIS)

    Zhang, Ze Xiang; Granatstein, V.L.; Destler, W.W.; Rodgers, J.; Cheng, S.; Antonsen, T.M. Jr.; Levush, B.; Bidwell, S.W.

    1993-01-01

    Detailed experimental studies on sheet relativistic electron beam propagation through a long planar wiggler are reported and compared with numerical simulations. The planar wiggler has 56 periods with a period of 9.6 mm. Typically, the wiggler field peak amplitude is 5 kG. The experimental efforts have been focused on control of the deviation of the beam toward the side edge of the planar wiggler along the wide transverse direction. It is found that a suitably tapered magnetic field configuration at the wiggler entrance can considerably reduce the rate of the deviation. The effects of the following techniques on beam transport efficiency are also discussed: side focusing, beam transverse velocity tuning at the wiggler entrance, and beam spread limiting. High beam transport efficiency (almost 100%) of a 15 A beam has been obtained in some cases. The results are relevant to development of a free electron laser amplifier for application to stabilizing and heating of plasma in magnetic fusion research

  6. Theoretical and experimental study on electron interactions with chlorobenzene: Shape resonances and differential cross sections

    Energy Technology Data Exchange (ETDEWEB)

    Barbosa, Alessandra Souza [Departamento de Física, Universidade Federal do Paraná, CP 19044, 81531-990 Curitiba, Paraná (Brazil); Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Varella, Márcio T. do N. [Instituto de Física, Universidade de São Paulo, Rua do Matão 1731, 05508-090 São Paulo, SP (Brazil); Sanchez, Sergio d’A.; Bettega, Márcio H. F., E-mail: bettega@fisica.ufpr.br [Departamento de Física, Universidade Federal do Paraná, CP 19044, 81531-990 Curitiba, Paraná (Brazil); Ameixa, João; Limão-Vieira, Paulo; Ferreira da Silva, Filipe [Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Blanco, Francisco [Departamento de Física Atómica, Molecular y Nuclear, Facultad de Ciencias Físicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain); and others

    2016-08-28

    In this work, we report theoretical and experimental cross sections for elastic scattering of electrons by chlorobenzene (ClB). The theoretical integral and differential cross sections (DCSs) were obtained with the Schwinger multichannel method implemented with pseudopotentials (SMCPP) and the independent atom method with screening corrected additivity rule (IAM-SCAR). The calculations with the SMCPP method were done in the static-exchange (SE) approximation, for energies above 12 eV, and in the static-exchange plus polarization approximation, for energies up to 12 eV. The calculations with the IAM-SCAR method covered energies up to 500 eV. The experimental differential cross sections were obtained in the high resolution electron energy loss spectrometer VG-SEELS 400, in Lisbon, for electron energies from 8.0 eV to 50 eV and angular range from 7{sup ∘} to 110{sup ∘}. From the present theoretical integral cross section (ICS) we discuss the low-energy shape-resonances present in chlorobenzene and compare our computed resonance spectra with available electron transmission spectroscopy data present in the literature. Since there is no other work in the literature reporting differential cross sections for this molecule, we compare our theoretical and experimental DCSs with experimental data available for the parent molecule benzene.

  7. Study and realisation of an ion source obtained by electronic bombardment - experimentation with phosphorus

    International Nuclear Information System (INIS)

    Schneider, Philippe

    1979-01-01

    This research thesis reports the study and development of an ion source by electronic bombardment. In order to solve some practical difficulties (cathode destruction, source instability, and so on), the design of each component has been very careful, notably for the electron gun. The author first briefly discusses the exiting ionisation processes, gives a list of ion which can be produced, with a focus on phosphorus for which the ionisation cross section is defined and assessed. After an assessment of different ionisation processes, and an indication of performance of the best existing sources, the author explains the choice for a totally different process. In the second part, he describes the experimental device, and particularly the electron gun as its design has been an important part of this research work. The source operation is described and its characteristics and performance are studied. Finally, the author outlines that some improvements are still possible to obtain a totally exploitable source [fr

  8. Experimental study of electron temperature gradient influence on impurity turbulent transport in fusion plasmas

    International Nuclear Information System (INIS)

    Villegas, D.

    2010-01-01

    Understanding impurity transport is a key to an optimal regime for a future fusion device. In this thesis, the theoretical and experimental influence of the electron temperature gradient R/L Te on heavy impurity transport is analyzed both in Tore Supra and ASDEX Upgrade. The electron temperature profile is modified locally by heating the plasma with little ECRH power deposited at two different radii. Experimental results have been obtained with the impurity transport code (ITC) which has been completed with a genetic algorithm allowing to determine the transport coefficient profiles with more accuracy. Transport coefficient profiles obtained by a quasilinear gyrokinetic code named QuaLiKiz are consistent with the experimental ones despite experimental uncertainties on gradients. In the core dominated by electron modes, the lower R/L Te the lower the nickel diffusion coefficient. The latter tends linearly to the neoclassical level when the instability threshold is approached. The experimental threshold is in agreement with the one computed by QuaLiKiz. Further out, where the plasma is dominated by ITG, which are independent of R/L Te , both experimental and simulated results show no modification in the diffusion coefficient profile. Furthermore, the convection velocity profile is not modified. This is attributed to a very small contribution of the thermodiffusion (1/Z dependence) in the total convection. On ASDEX, the preliminary results, very different from the Tore Supra ones, show a internal transport barrier for impurities located at the same radius as the strong ECRH power deposit. (author) [fr

  9. Experimental investigation of focusing and transport of heavy-current electron beams

    International Nuclear Information System (INIS)

    Baranchikov, E.I.; Gordeev, A.V.; Koba, Yu.V.; Korolev, V.D.; Pen'kina, V.S.; Rudakov, L.I.; Smirnov, V.P.; Sukhov, A.D.; Tarumov, E.Z.

    The results of an experimental and theoretical study of beam transfer through transverse magnetic fields are outlined. The injection and transport of an annular relativistic electron beam due to a magnetic trap of acute-angle geometry are experimentally studied

  10. Experimental and theoretical study of electronic structure of aluminum in extreme conditions with X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Festa, Floriane

    2013-01-01

    Matter in extreme conditions belongs to Warm Dense Matter regime which lays between dense plasma regime and condensed matter. This regime is still not well known, indeed it is very complex to generate such plasma in the laboratory to get experimental data and validate models. The goal of this thesis is to study electronic structure of aluminum in extreme conditions with X-ray absorption spectroscopy. Experimentally aluminum has reached high densities and high temperatures, up to now unexplored. An X-ray source has also been generated to probe highly compressed aluminum. Two spectrometers have recorded aluminum absorption spectra and aluminum density and temperature conditions have been deduced thanks to optical diagnostics. Experimental spectra have been compared to ab initio spectra, calculated in the same conditions. The theoretical goal was to validate the calculation method in high densities and high temperatures regime with the study of K-edge absorption modifications. We also used absorption spectra to study the metal-non metal transition which takes place at low density (density ≤ solid density). This transition could be study with electronic structure modifications of the system. (author) [fr

  11. EBTS: DESIGN AND EXPERIMENTAL STUDY

    International Nuclear Information System (INIS)

    PIKIN, A.; ALESSI, J.; BEEBE, E.; KPONOU, A.; PRELEC, K.; KUZNETSOV, G.; TIUNOV, M.

    2000-01-01

    Experimental study of the BNL Electron Beam Test Stand (EBTS), which is a prototype of the Relativistic Heavy Ion Collider (RHIC) Electron Beam Ion Source (EBIS), is currently underway. The basic physics and engineering aspects of a high current EBIS implemented in EBTS are outlined and construction of its main systems is presented. Efficient transmission of a 10 A electron beam through the ion trap has been achieved. Experimental results on generation of multiply charged ions with both continuous gas and external ion injection confirm stable operation of the ion trap

  12. Experimental and numerical study of flow deflection effects on electronic air-cooling

    International Nuclear Information System (INIS)

    Arfaoui, Ahlem; Ben Maad, Rejeb; Hammami, Mahmoud; Rebay, Mourad; Padet, Jacques

    2009-01-01

    This work present a numerical and experimental investigation of the influence of transversal flow deflector on the cooling of a heated block mounted on a flat plate. The deflector is inclined and therefore it guides the air flow to the upper surface of the block. This situation is simulating the air-cooling of a rectangular integrated circuit or a current converter mounted on an electronic board. The electronic component are assumed dissipating a low or medium heat flux (with a density lower than 5000 W/m 2 ), as such the forced convection air cooling without fan or heat sink is still sufficient. The study details the effects of the angle of deflector on the temperature and the heat transfer coefficient along the surface of the block and around it. The results of the numerical simulations and the InfraRed camera measurements show that the deviation caused by deflector may significantly enhance the heat transfer on the top face of block

  13. Experimental and theoretical study of very-low-energy inelastic processes in electron-molecule collisions, March 20, 1981-March 20, 1982

    International Nuclear Information System (INIS)

    Golden, D.E.; Morrison, M.

    1982-01-01

    We have undertaken a comprehensive theoretical and experimental study of very-low-energy electron-impact excitation of molecules. The objective of the first phase of this program is a comprehensive study of near-threshold electron-impact ro-vibrational excitation cross sections in H 2 in order to resolve serious discrepancies that exist between the cross sections for this process as determined by beam and swarm experiments. The program consists of experimental measurements of these cross sections using a cross-beam time-of-flight apparatus being developed in our laboratory and fully ab-initio theoretical calculations of these cross sections using a coupled-channels formulation with a highly-accurate interaction potential. Progress is reported

  14. Experimental core electron density of cubic boron nitride

    DEFF Research Database (Denmark)

    Wahlberg, Nanna; Bindzus, Niels; Bjerg, Lasse

    as well as experimental result. The redistribution of electron density will, if not accounted for, result in increased thermal parameters. It is estimated that 1.7-2 electrons is transferred from boron to nitrogen. [1]: N. Bindzus, T. Straasø, N. Wahlberg, J. Becker, L. Bjerg, N. Lock, A.-C. Dippel, and B......Experimental core electron density of cubic boron nitride Nanna Wahlberg*, Niels Bindzus*, Lasse Bjerg*, Jacob Becker*, and Bo B. Iversen* *Aarhus University, Department of Chemistry, CMC, Langelandsgade 140, 8000 Århus, Denmark The resent progress in powder diffraction provides data of quality...... obtained. The displacement parameters reported here are significantly lower than those previously reported, stressing the importance of an adequate description of the core density. The charge transfer from boron to nitrogen clearly affects the inner electron density, which is evident from theoretical...

  15. Experimental determination of the electron-avalanche and the electron-ion recombination coefficient

    NARCIS (Netherlands)

    Ernst, G.J.; Boer, A.G.

    1980-01-01

    The electron-ion recombination coefficient γ and the avalanche coefficient δ = (α − a) · vd, where α and a are the ionizat ion and attachment coefficients respectively and vd the drift velocity of the electrons, have been experimentally determined in a self-sustained CO2-laser system (1:1:3 mixture)

  16. Electron scattering at interfaces in nano-scale vertical interconnects: A combined experimental and ab initio study

    Science.gov (United States)

    Lanzillo, Nicholas A.; Restrepo, Oscar D.; Bhosale, Prasad S.; Cruz-Silva, Eduardo; Yang, Chih-Chao; Youp Kim, Byoung; Spooner, Terry; Standaert, Theodorus; Child, Craig; Bonilla, Griselda; Murali, Kota V. R. M.

    2018-04-01

    We present a combined theoretical and experimental study on the electron transport characteristics across several representative interface structures found in back-end-of-line interconnect stacks for advanced semiconductor manufacturing: Cu/Ta(N)/Co/Cu and Cu/Ta(N)/Ru/Cu. In particular, we evaluate the impact of replacing a thin TaN barrier with Ta while considering both Co and Ru as wetting layers. Both theory and experiment indicate a pronounced reduction in vertical resistance when replacing TaN with Ta, regardless of whether a Co or Ru wetting layer is used. This indicates that a significant portion of the total vertical resistance is determined by electron scattering at the Cu/Ta(N) interface. The electronic structure of these nano-sized interconnects is analyzed in terms of the atom-resolved projected density of states and k-resolved transmission spectra at the Fermi level. This work further develops a fundamental understanding of electron transport and material characteristics in nano-sized interconnects.

  17. Effect of Electron Seeding on Experimentally Measured Multipactor Discharge Threshold

    Science.gov (United States)

    Noland, Jonathan; Graves, Timothy; Lemon, Colby; Looper, Mark; Farkas, Alex

    2012-10-01

    Multipactor is a vacuum phenomenon in which electrons, moving in resonance with an externally applied electric field, impact material surfaces. If the number of secondary electrons created per primary electron impact averages more than unity, the resonant interaction can lead to an electron avalanche. Multipactor is a generally undesirable phenomenon, as it can cause local heating, absorb power, or cause detuning of RF circuits. In order to increase the probability of multipactor initiation, test facilities often employ various seeding sources such as radioactive sources (Cesium 137, Strontium 90), electron guns, or photon sources. Even with these sources, the voltage for multipactor initiation is not certain as parameters such as material type, RF pulse length, and device wall thickness can all affect seed electron flux and energy in critical gap regions, and hence the measured voltage threshold. This study investigates the effects of seed electron source type (e.g., photons versus beta particles), material type, gap size, and RF pulse length variation on multipactor threshold. In addition to the experimental work, GEANT4 simulations will be used to estimate the production rate of low energy electrons (< 5 keV) by high energy electrons and photons. A comparison of the experimental fluxes to the typical energetic photon and particle fluxes experienced by spacecraft in various orbits will also be made. Initial results indicate that for a simple, parallel plate device made of aluminum, there is no threshold variation (with seed electrons versus with no seed electrons) under continuous-wave RF exposure.

  18. Recent experimental progress in the study of electron and proton beating for fast ignition

    International Nuclear Information System (INIS)

    Key, M. H.; Akli, K.; Beg, F.; Chen, M. H.; Chen, Z.; Chung, H. K.; Fournier, K.; Freeman, R. R.; Green, J. S.; Gu, P.; Gregori, J.; Habara, H.; Hatchett, S. P.; Hey, D.; Hill, J. M.; Izawa, Y.; King, J. A.; Kitagawa, Y.; Kodama, R.; Koch, J. A.; Lancaster, K.; Lasinski, B. F.; Langdon, B.; MacKinnon, A. J.; Lei, A.; Moon, S. J.; Murphy, C. D.; Norreys, P. A.; Park, H. S.; Patel, N.; Patel, P.; Pasley, J.; Snavely, R. A.; Stephens, R. B.; Stoeckl, C.; Tabak, M.; Tampo, M.; Theobold, W.; Tanaka, K. A.; Town, R. J. P.; Toyama, Y.; Tsutsumi, T.; Wilks, S. C.; Yabuuchi, T.; Zhang, B.; Zheng, J.

    2005-01-01

    The results of recent collaborative experimental campaigns at the RAL PW and 100 TW and Gekko PW laser facilities, which have extended our understanding of electron and proton heating for fast ignition are presented. Heating by electrons has been measured by imaging Cu Ka fluorescence, from crystal and single hit CCD spectroscopy of Cu K shell emission, from two color XUV imaging (68eV and 270 eV) and from streaked 68eV imaging. Heating in solid foil targets, ultra- low mass foil targets and cone targets coupled to fibers and other FI surrogates has been studied using 0.5 to 10 ps pulse duration and powers up to 1 PW. Cone coupling to an imploded plasma has been examined using Cu Ka to diagnose the electron flux in the imploded material. Heating by focused proton beams generated at the concave inside surface of a hemi shell has been studied with similar diagnostic methods. Temperatures at the rear surface of proton heated solid foils have exceeded those produced by direct electron heating. Variation of heating with depth and the transverse pattern of heating have been measured. The spatial distribution of electron flux in a Cu hemi- shell used as a proton source has been determined by imaging Ka fluorescence. Conversion efficiency to protons has been measured from radio-chromic film data. Conclusions from the experiments, links to theoretical understanding and relevance to fast ignition are outlined. This work was performed under the auspices of the U.S. Department of Energy by University of California Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48. (Author)

  19. Experimental study of matrix carbon field-emission cathodes and computer aided design of electron guns for microwave power devices, exploring these cathodes

    International Nuclear Information System (INIS)

    Grigoriev, Y.A.; Petrosyan, A.I.; Penzyakov, V.V.; Pimenov, V.G.; Rogovin, V.I.; Shesterkin, V.I.; Kudryashov, V.P.; Semyonov, V.C.

    1997-01-01

    The experimental study of matrix carbon field-emission cathodes (MCFECs), which has led to the stable operation of the cathodes with current emission values up to 100 mA, is described. A method of computer aided design of TWT electron guns (EGs) with MCFEC, based on the results of the MCFEC emission experimental study, is presented. The experimental MCFEC emission characteristics are used to define the field gain coefficient K and the cathode effective emission area S eff . The EG program computes the electric field upon the MCFEC surface, multiplies it by the K value and uses the Fowler Nordheim law and the S eff value to calculate the MCFEC current; the electron trajectories are computed as well. copyright 1997 American Vacuum Society

  20. Experimental study for angular distribution of the hot electrons generated by femtosecond laser interaction with solid targets

    International Nuclear Information System (INIS)

    Cai, D.F.; Gu, Y.Q.; Zheng, Z.J.; Wen, T.S.; Chunyu, S.T.; Wang, Z.B.; Yang, X.D.

    2003-01-01

    The experimental results of angular distribution of hot electrons in the interaction of a 60 fs, 125 mJ, 800 nm, ∼10 17 W cm -2 laser pulse with Al targets are reported. Three obvious peaks of hot electrons emission have been observed, as there is a weak normal component of the laser electric field. These emission peaks are located in the directions of the specular reflection of the laser, the target normal, and the backreflection of the laser, respectively. In the case of the P-polarized laser pulse, which has a strong normal component of the laser electric field, the peak in the backreflection of the laser disappeared, and only two obvious peaks of hot electron emissions existed. It shows that the different directions of hot electrons emission are dominated by different absorption or acceleration mechanisms. The experimental result of the hot electrons energy spectrum at the target normal shows that the effective temperature of hot electrons is about 190 keV, which is consistent with a scaling law of the resonance absorption

  1. Electron sputtering in the analytical electron microscope: Calculations and experimental data

    International Nuclear Information System (INIS)

    Zaluzec, N.J.; Mansfield, J.F.

    1987-03-01

    The environment of the electron microscope is particularly severe when one considers the energy deposited in a specimen during typical experimental conditions. Conventional imaging experiments tend to employ electron current densities ranging from ∼0.1 to 1 A/cm 2 while during microanalysis conditions probe current densities can range from 10 to values as high as 10 5 A/cm 2 . At 100 kV this corresponds to power densities from 100 Kilowatts/cm 2 to 10 4 Megawatts/cm 2 . These energy deposition rates can result in electron irradiation damage which can substantially alter the structure and composition of a specimen through either ionization damage in organics or by displacement damage in inorganics and/or combinations thereof. For the most part materials scientists operating an analytical electron microscope (AEM) in the 100 to 200 kV regime studying metallic and/or ceramic specimens have been spared the need to consider either of these effects as their specimens have tended to be sufficiently resilient. However, the advent of the new medium voltage microscopes operating in the 300 to 400 kV regime with high brightness guns and clean or ultrahigh vacuum systems has necessitated a reevaluation of the effects of higher voltage operation in light of the destructive nature of the electron beam particularly under microanalysis conditions

  2. Off-axis and inline electron holography: Experimental comparison

    International Nuclear Information System (INIS)

    Latychevskaia, Tatiana; Formanek, Petr; Koch, C.T.; Lubk, Axel

    2010-01-01

    Electron holography is a very powerful technique for mapping static electric and magnetic potentials down to atomic resolution. While electron holography is commonly considered synonymous with its off-axis variant in the high energy electron microscopy community, inline electron holography is widely applied in low-energy electron microscopy, where the realization of the off-axis setup is still an experimental challenge. This paper demonstrates that both inline and off-axis holography may be used to recover amplitude and phase shift of the very same object, in our example latex spheres of 90 and 200 nm in diameter, producing very similar results, provided the object does not charge under the electron beam.

  3. Experimental (e, 2e) study of exchange interferences in the resonant Auger decay of Ar induced by electron impact

    International Nuclear Information System (INIS)

    Paripás, Béla; Palásthy, Béla; Žitnik, Matjaz

    2013-01-01

    Highlights: •The interference of autoionizing resonances with a common final ionic state is measured. •We have developed a method to experimentally verify for the exchange interference effect. •The sum of kinetic energies of the two detected electrons is kept constant. •Mainly the interference effects of [2p 3/2 ]4p and [2p 1/2 ]4p resonances in argon are studied. •The results possibly indicate small exchange interference effects. -- Abstract: Any two autoionizing resonances with a common final ionic state can be made to interfere by an appropriate selection of electron impact energy. To reveal the exchange interference effects a selective detection of electron pairs related to the selected final state is desired. We have performed a constant ionic state (e, 2e) experiment (CIS) isolating the final state by keeping the sum of transmission energies of two independent electron spectrometers constant. In the focus of this work are the exchange interference effects of 2p 3/2 −1 4p and 2p 1/2 −1 4p resonances in argon decaying to the 3p −2 ( 1 D)4p 2 P, 2 D final ionic state with energy E F = 37.3 ± 0.2 eV. We have developed a method to experimentally verify for the exchange interference effect. It is based on a comparison of the CIS spectrum recorded at the critical primary electron energy that activates the interferences, and the constructed, interference-free CIS spectrum that is build up from the CIS spectrum measured at primary electron energy away from the critical value. The results possibly indicate small exchange interference effects that may have been considerably smeared out at present experimental energy resolution

  4. Molecular studies by electron spectroscopy

    International Nuclear Information System (INIS)

    Hansteen, J.M.

    1977-01-01

    Experience gained in experimental nuclear physics has played a large role in the development of electron spectroscopy as a powerful tool for studying chemical systems. The use of ESCA (Electron Spectroscopy for Chemical Analysis) for the mapping of molecular properties connected with inner as well as outer electron shells is reviewed, mainly from a phenomological point of view. Molecular Auger electron spectroscopy is described as a means of gaining information on details in molecular structure, simultaneously being extensively applied for surface studies. Future highly promising research areas for molecular electron spectroscopy are suggested to be (e,2e) processes as well as continued exploitation of synchrotron radiation from high energy nuclear devices. (Auth.)

  5. Electronic and magnetic properties of the [Ni(salophen]: An experimental and DFT study

    Directory of Open Access Journals (Sweden)

    Rodrigo A. Mendes

    2018-01-01

    Full Text Available The effect of the coordination of a Ni(II ion on the electronic and magnetic properties of the ligand salophen were experimentally and theoretically evaluated. The complex [Ni(salophen] was synthesized and characterized through FTIR and an elemental analysis. Spectral data obtained using DMSO as a solvent showed that the ligand absorption profile was significantly disturbed after the coordination of the metal atom. In addition to a redshift of the salophen ligand absorption bands, mainly composed by π → π∗electronic transitions, additional bands of around 470 nm were observed, resulting in a partial metal-to-ligand charge transfer. Furthermore, a significant increment of its band intensities was observed, favoring a more intense absorption in a broader range of the visible spectrum, which is a desired characteristic for applications in the field of organic electronics. This finding is related to an increment of the planarity and consequent electron delocalization of the macrocycle in the complex, which was estimated by the calculation of the current strengths at the PBE0/cc-pVTZ (Dyall.v3z for Ni(II level.

  6. Feasibility study for mega-electron-volt electron beam tomography.

    Science.gov (United States)

    Hampel, U; Bärtling, Y; Hoppe, D; Kuksanov, N; Fadeev, S; Salimov, R

    2012-09-01

    Electron beam tomography is a promising imaging modality for the study of fast technical processes. But for many technical objects of interest x rays of several hundreds of keV energy are required to achieve sufficient material penetration. In this article we report on a feasibility study for fast electron beam computed tomography with a 1 MeV electron beam. The experimental setup comprises an electrostatic accelerator with beam optics, transmission target, and a single x-ray detector. We employed an inverse fan-beam tomography approach with radiographic projections being generated from the linearly moving x-ray source. Angular projections were obtained by rotating the object.

  7. Electron-beam generated porous dextran gels: experimental and quantum chemical studies.

    Science.gov (United States)

    Naumov, Sergej; Knolle, Wolfgang; Becher, Jana; Schnabelrauch, Matthias; Reichelt, Senta

    2014-06-01

    The aim of this work was to investigate the reaction mechanism of electron-beam generated macroporous dextran cryogels by quantum chemical calculation and electron paramagnetic resonance measurements. Electron-beam radiation was used to initiate the cross-linking reaction of methacrylated dextran in semifrozen aqueous solutions. The pore morphology of the resulting cryogels was visualized by scanning electron microscopy. Quantum chemical calculations and electron paramagnetic resonance studies provided information on the most probable reaction pathway and the chain growth radicals. The most probable reaction pathway was a ring opening reaction and the addition of a C-atom to the double-bond of the methacrylated dextran molecule. First detailed quantum chemical calculation on the reaction mechanism of electron-beam initiated cross-linking reaction of methacrylated dextran are presented.

  8. Using an Electron Scanning Microscope to Assess the Penetrating Abilities of an Experimental Preparation with Features of a Dental Infiltrant: Preliminary Study.

    Science.gov (United States)

    Skucha-Nowak, Małgorzata; Mertas, Anna; Tanasiewicz, Marta

    2016-01-01

    The resin infiltration technique is one of the micro-invasive methods whose aim is the penetration of demineralized enamel with a low viscosity resin. This technique allows the dentist to avoid the application of mechanical means of treatment. The objective of this preliminary study was to attempt to determine the possibilities of using an electron microscope to assess the penetrating abilities of an experimental preparation with features of a dental infiltrant and to compare the depth of infiltration of the designed experimental preparation with an infiltrant available on the market. A bioactive methacrylate monomer based on PMMAn with built-in metronidazole was synthesized. The commercially available Icon solution (with contrast agent YbF3) and the experimental solution were applied to the relevant parts of teeth. The dissected sections along the long tooth axis and polished surfaces were then examined with use of an electron scanning microscope. The backscattered electron technique gives much better results than the secondary electron method as it makes it possible to localize even very small YbF3 particles. The authors concluded that the backscattered electron technique gives much better results than the secondary electron method as it makes it possible to localize even very small particles of the contrast agent. In order to prevent blockage of decalcified enamel tissue by ytterbium trifluoride (YbF3) grains, a nanoparticle form of that compound should be used (that is, particles with sizes in the range of 10-9 m).

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

    Science.gov (United States)

    Angioni, C.; Peeters, A. G.; Garbet, X.; Manini, A.; Ryter, F.; ASDEX Upgrade Team

    2004-08-01

    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 thermodiffusive 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.

  10. Experimental study of K-electron capture probability in the decay of {sup 111}In

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, N.R.; Kalyani, V.D.M.L.; Maldhusudhana Rao, P.V.; Vara Prasad, N.V.; Chandrasekhar Rao, M.V.S.; Satyanarayana, G.; Sastry, D.L. [Visakhapatnam, Andhra Univ. (India). Swami Jnanananda Lab. for Nuclear Research; Chintalapudi, S.N. [Calcutt, Inter-Univ. Consortium for DAEW Facilities (India)

    1998-03-01

    The K-electron capture probability in the decay of {sup 111}In to the 416.64 keV level of the daughter nucleus {sup 111}Cd was measured to be 0.853 {+-}0.037 in agreement with the theoretical value 0.865. The experimental value is seen to be consistent with the mass prediction of the relationship due to Wapstra and Bos.

  11. Equation of state and electronic properties of EuVO4: A high-pressure experimental and computational study

    International Nuclear Information System (INIS)

    Paszkowicz, Wojciech; López-Solano, Javier; Piszora, Paweł; Bojanowski, Bohdan; Mujica, Andrés; Muñoz, Alfonso; Cerenius, Yngve; Carlson, Stefan; Dąbkowska, Hanna

    2015-01-01

    Structural, elastic and electronic properties of zircon-type and scheelite-type EuVO 4 are investigated experimentally, by in-situ X-ray diffraction using synchrotron radiation, and theoretically within the framework of the density functional theory (DFT) and using the PBE prescription of the exchange-correlation energy. This study was motivated by the fact that the previous knowledge of the equation of state (EOS) was inconclusive due to a large scatter of the experimental and theoretical data, and by the lack of information on the dependence of the electronic structure with pressure. Under the applied experimental conditions, the zircon-type structure transforms to a scheelite-type one at 7.4(2) GPa, whereas the calculations yield a lower zircon–scheelite-coexistence pressure of 4.8 GPa. The experimental part of the study shows that the bulk modulus of the zircon-type phase is 119(3) GPa, perfectly supported by the DFT-calculated value, 119.1 GPa. The bulk modulus for the scheelite-type polymorph is higher, with an experimental value of 135(7) GPa and a theoretical one of 137.4 GPa. Compared to those reported in previous experimental and DFT or semiempirical works, the present values for the zircon-type phase are comparable or slightly lower, whereas those for the scheelite-type phase are markedly lower. Discrepancies between the present results and earlier reported ones are attributed to differences in details of the experimental method such as the pressure transmitting medium and the pressure calibration method. The calculated band structure confirms that zircon-type EuVO 4 is a direct-gap semiconductor, with a bandgap energy at zero pressure of 2.88 eV. Under compression, the bandgap of the zircon phase increases with a coefficient of 10.3 meV/GPa up to the transition pressure, at which point the present calculations show a small drop of the bandgap energy. Above the transition pressure, the bandgap energy of the scheelite phase becomes almost constant, with

  12. Electron Microscopic Changes of Rabbit Retina after Chromovitrectomy Using Combined Dyes (Experimental Study

    Directory of Open Access Journals (Sweden)

    B. M. Aznabaev

    2018-01-01

    Full Text Available Purpose: to evaluate on experimental model electron-microscopic changes of rabbit retina after staining of the posterior eye segmentwith combined dyes based on Trypan blue and Brilliant blue G for the assessment of their safety. Methods. The study was performed onChinchilla breed rabbits. Combined dyes based on Trypan blue and Brilliant blue were used: MembraneBlue-Dual (DORC, Netherlandsand “Staining solution for ophthalmic surgery” (JCS “Optimedservis”, Russia. Standard three-port vitrectomy technique was used. After vitreous removal dyes were injected in vitreous cavity and exposed for 10 seconds and then removed. The vitreous cavity was filled by a balanced salt solution. An electron-microscopic evaluation was performed on 5, 14 and 30 days after surgery. Eyes were enucleated in 20 minutes after animal was killed by air embolization. Intact eyes were used as a control, all samples were prepared in same сonditions. The damage of the retina architectonics and the presence of intracellular inclusions were evaluated. Results. The staged character of pathomorphological changes was revealed. On the 5th day moderate edema and hydropic dystrophy of neurons were registered. On the 14th day, there was no negative dynamics. On day 30, the signs of edema and dystrophy of neurons practically disappeared, which may indicate a fundamental reversibility of the registered changes. Conclusion. Investigated dyes for staining intraocular structures based on Trypan blue and Brilliant blue did not cause significant histomorphological changes and toxic effects on retinal cell structures. Detected electron microscopic changes were insignificant, had reversible character and could be mostly caused by a surgical injury.

  13. Studies of electron cyclotron emission on text

    International Nuclear Information System (INIS)

    Gandy, R.F.

    1990-07-01

    The Auburn University electron cyclotron emission (ECE) system has made many significant contributions to the TEXT experimental program during the past five years. Contributions include electron temperature information used in the following areas of study: electron cyclotron heating (ECH), pellet injection, and impurity/energy transport. Details of the role which the Auburn ECE system has played will now be discussed

  14. Principal and experimental study of source of polarized electrons

    International Nuclear Information System (INIS)

    Shang Rencheng; Gao Junfang; Xiao Yuan; Pang Wenning; Deng Jingkang

    1999-01-01

    The getting of polarized electrons was briefly introduced, that is the source of polarized electrons. The measurement of polarization in future, the application of polarized electrons in atomic and molecular physics, condensed physics, biological physics, nuclear and particle physics were discussed

  15. An experimental study of electron transfer and emission during particle-surface interactions

    International Nuclear Information System (INIS)

    McGrath, C.T.

    2000-09-01

    A new coincidence technique has been developed and used to study the secondary electron emission that arises during the interaction of ions with surfaces. This coincidence technique allows the secondary electron emission statistics due to the impact of singly, doubly and multiply charged ions on surfaces to be measured in coincidence with reflected particles, in specific charge states and with specific post-collision trajectories. This system has been used to study the impact of 8 keV H + ions on polycrystalline copper and aluminium targets. Under these conditions the potential emission contribution is negligible and the electron emission is almost entirely due to kinetic emission processes. The sub-surface contribution to the observed electron emission has been isolated using two newly developed models. These models provide valuable information about the depth and amount of surface penetration and on the probability for subsequent electron transport to the surface. The impact of 2 - 100 keV Xe q+ (q = 1 - 10) ions on polycrystalline copper has also been studied using this system. From the subsequent data the potential and kinetic contributions to secondary electron emission have been separated using a previously established model for potential emission. The resulting kinetic emission yield increases with increasing ion impact energy, consistent with current concepts on quasimolecular ionisation. For ions impacting at large incident angles evidence for sub-surface emission has also been observed. The degree of penetration increases with ion impact energy, consistent with current concepts on this effect. The formation of H - ions from incident H + ions has also been studied by measuring the secondary electron emission statistics in coincidence with reflected particles in specific final charge states. This preliminary data is consistent with a two-step process of Auger neutralisation followed by resonant electron capture to the affinity level. However this mechanism

  16. Equation of state and electronic properties of EuVO{sub 4}: A high-pressure experimental and computational study

    Energy Technology Data Exchange (ETDEWEB)

    Paszkowicz, Wojciech, E-mail: paszk@ifpan.edu.pl [Institute of Physics, Polish Academy of Sciences, al. Lotników 32/46, 02-668 Warsaw (Poland); López-Solano, Javier [Departamento de Física, MALTA Consolider Team, and Instituto de Materiales y Nanotecnología, Universidad de La Laguna, Tenerife 38205 (Spain); Izaña Atmospheric Research Center, Agencia Estatal de Meteorología (AEMET), Tenerife 38071 (Spain); Piszora, Paweł [Department of Materials Chemistry, Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89b, 61-614 Poznań (Poland); Bojanowski, Bohdan [Institute of Physics, Szczecin University of Technology, Aleja Piastów 48, 70-310 Szczecin (Poland); Mujica, Andrés; Muñoz, Alfonso [Departamento de Física, MALTA Consolider Team, and Instituto de Materiales y Nanotecnología, Universidad de La Laguna, Tenerife 38205 (Spain); Cerenius, Yngve; Carlson, Stefan [MAX IV Laboratory, Lund University, P.O. Box 118, SE-221 00 Lund (Sweden); Dąbkowska, Hanna [Brockhouse Institute for Materials Research, McMaster University, Hamilton, Ontario L8S 4M1 (Canada)

    2015-11-05

    Structural, elastic and electronic properties of zircon-type and scheelite-type EuVO{sub 4} are investigated experimentally, by in-situ X-ray diffraction using synchrotron radiation, and theoretically within the framework of the density functional theory (DFT) and using the PBE prescription of the exchange-correlation energy. This study was motivated by the fact that the previous knowledge of the equation of state (EOS) was inconclusive due to a large scatter of the experimental and theoretical data, and by the lack of information on the dependence of the electronic structure with pressure. Under the applied experimental conditions, the zircon-type structure transforms to a scheelite-type one at 7.4(2) GPa, whereas the calculations yield a lower zircon–scheelite-coexistence pressure of 4.8 GPa. The experimental part of the study shows that the bulk modulus of the zircon-type phase is 119(3) GPa, perfectly supported by the DFT-calculated value, 119.1 GPa. The bulk modulus for the scheelite-type polymorph is higher, with an experimental value of 135(7) GPa and a theoretical one of 137.4 GPa. Compared to those reported in previous experimental and DFT or semiempirical works, the present values for the zircon-type phase are comparable or slightly lower, whereas those for the scheelite-type phase are markedly lower. Discrepancies between the present results and earlier reported ones are attributed to differences in details of the experimental method such as the pressure transmitting medium and the pressure calibration method. The calculated band structure confirms that zircon-type EuVO{sub 4} is a direct-gap semiconductor, with a bandgap energy at zero pressure of 2.88 eV. Under compression, the bandgap of the zircon phase increases with a coefficient of 10.3 meV/GPa up to the transition pressure, at which point the present calculations show a small drop of the bandgap energy. Above the transition pressure, the bandgap energy of the scheelite phase becomes almost

  17. Electronic transport in VO2—Experimentally calibrated Boltzmann transport modeling

    International Nuclear Information System (INIS)

    Kinaci, Alper; Rosenmann, Daniel; Chan, Maria K. Y.; Kado, Motohisa; Ling, Chen; Zhu, Gaohua; Banerjee, Debasish

    2015-01-01

    Materials that undergo metal-insulator transitions (MITs) are under intense study, because the transition is scientifically fascinating and technologically promising for various applications. Among these materials, VO 2 has served as a prototype due to its favorable transition temperature. While the physical underpinnings of the transition have been heavily investigated experimentally and computationally, quantitative modeling of electronic transport in the two phases has yet to be undertaken. In this work, we establish a density-functional-theory (DFT)-based approach with Hubbard U correction (DFT + U) to model electronic transport properties in VO 2 in the semiconducting and metallic regimes, focusing on band transport using the Boltzmann transport equations. We synthesized high quality VO 2 films and measured the transport quantities across the transition, in order to calibrate the free parameters in the model. We find that the experimental calibration of the Hubbard correction term can efficiently and adequately model the metallic and semiconducting phases, allowing for further computational design of MIT materials for desirable transport properties

  18. Studies of runaway electrons via Cherenkov effect in tokamaks

    Science.gov (United States)

    Zebrowski, J.; Jakubowski, L.; Rabinski, M.; Sadowski, M. J.; Jakubowski, M. J.; Kwiatkowski, R.; Malinowski, K.; Mirowski, R.; Mlynar, J.; Ficker, O.; Weinzettl, V.; Causa, F.; COMPASS; FTU Teams

    2018-01-01

    The paper concerns measurements of runaway electrons (REs) which are generated during discharges in tokamaks. The control of REs is an important task in experimental studies within the ITER-physics program. The NCBJ team proposed to study REs by means of Cherenkov-type detectors several years ago. The Cherenkov radiation, induced by REs in appropriate radiators, makes it possible to identify fast electron beams and to determine their spatial- and temporal-characteristics. The results of recent experimental studies of REs, performed in two tokamaks - COMPASS in Prague and FTU in Frascati, are summarized and discussed in this paper. Examples of the electron-induced signals, as recorded at different experimental conditions and scenarios, are presented. Measurements performed with a three-channel Cherenkov-probe in COMPASS showed that the first fast electron peaks can be observed already during the current ramp-up phase. A strong dependence of RE-signals on the radial position of the Cherenkov probe was observed. The most distinct electron peaks were recorded during the plasma disruption. The Cherenkov signals confirmed the appearance of post-disruptive RE beams in circular-plasma discharges with massive Ar-puffing. During experiments at FTU a clear correlation between the Cherenkov detector signals and the rotation of magnetic islands was identified.

  19. Experimental studies of the magnetized friction force

    International Nuclear Information System (INIS)

    Fedotov, A. V.; Litvinenko, V. N.; Gaalnander, B.; Lofnes, T.; Ziemann, V.; Sidorin, A.; Smirnov, A.

    2006-01-01

    High-energy electron cooling, presently considered as an essential tool for several applications in high-energy and nuclear physics, requires an accurate description of the friction force which ions experience by passing through an electron beam. Present low-energy electron coolers can be used for a detailed study of the friction force. In addition, parameters of a low-energy cooler can be chosen in a manner to reproduce regimes expected in future high-energy operation. Here, we report a set of dedicated experiments in CELSIUS aimed at a detailed study of the magnetized friction force. Some results of the accurate comparison of experimental data with the friction force formulas are presented

  20. Study of electron transmission through thin metallic films by the electron moessbauer spectroscopy

    International Nuclear Information System (INIS)

    Babikova, Yu.F.; Vakar, O.M.; Gruzin, O.M.; Petrikin, Yu.V.

    1983-01-01

    Results of the experimental study of the transmission of conversion electrons through aluminium, iron, tin and gold films are presented. Absorption of resonance electrons of the Moessbauer nuclide 57 Fe, formed during target irradiation with γ-quanta of 57 Co source in chromium matrix has been studied. It is asserted that absorption of conversion electrons in films of different elements is similar; at that, like in the case of β-particles, the law of absorption of resonance electrons, emitted from the flat layer, is exponential For conversion electrons of the Moessbauer nuclide 57 Fe the absorption coefficient is (0.025+-0.002) cm 2 /μg, which in the case of iron absorbing film corresponds to (20.0+-1.0)x10 4 cm -1

  1. Experimental Study of Dust Grain Charging

    Science.gov (United States)

    Spann, James F; Venturini, Catherine C.; Comfort, Richard H.; Mian, Abbas M.

    1999-01-01

    The results of an experimental study of the charging mechanisms of micron size dust grains are presented. Individual dust grains are electrodynamically suspended and exposed to an electron beam of known energy and flux, and to far ultraviolet radiation of known wavelength and intensity. Changes in the charge-to-mass ratio of the grain are directly measured as a function of incident beam (electron and/or photon), grain size and composition. Comparisons of our results to theoretical models that predict the grain response are presented.

  2. An experimental and theoretical investigation into the excited electronic states of phenol

    Energy Technology Data Exchange (ETDEWEB)

    Jones, D. B.; Chiari, L. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Silva, G. B. da [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Universidade Federal de Mato Grosso, Barra do Garças, Mato Grosso (Brazil); Neves, R. F. C. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Departamento de Física, UFJF, Juiz de Fora, MG (Brazil); Instituto Federal do Sul de Minas Gerais, Campus Poços de Caldas, Minas Gerais (Brazil); Duque, H. V. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Departamento de Física, UFJF, Juiz de Fora, MG (Brazil); Oliveira, E. M. de; Lima, M. A. P. [Instituto de Física “Gleb Wataghin,” Universidade Estadual de Campinas, 13083-859 Campinas, São Paulo (Brazil); Lopes, M. C. A. [Departamento de Física, UFJF, Juiz de Fora, MG (Brazil); Costa, R. F. da [Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, 09210-580 Santo André, São Paulo (Brazil); Varella, M. T. do N. [Instituto de Física, Universidade de São Paulo, CP 66318, 05315-970 São Paulo (Brazil); Bettega, M. H. F. [Departamento de Física, Universidade Federal do Paraná, CP 19044, 81531-990 Curitiba, Paraná (Brazil); and others

    2014-08-21

    We present experimental electron-energy loss spectra (EELS) that were measured at impact energies of 20 and 30 eV and at angles of 90° and 10°, respectively, with energy resolution ∼70 meV. EELS for 250 eV incident electron energy over a range of angles between 3° and 50° have also been measured at a moderate energy resolution (∼0.9 eV). The latter spectra were used to derive differential cross sections and generalised oscillator strengths (GOS) for the dipole-allowed electronic transitions, through normalization to data for elastic electron scattering from benzene. Theoretical calculations were performed using time-dependent density functional theory and single-excitation configuration interaction methods. These calculations were used to assign the experimentally measured spectra. Calculated optical oscillator strengths were also compared to those derived from the GOS data. This provides the first investigation of all singlet and triplet excited electronic states of phenol up to the first ionization potential.

  3. Experimental perforating injury with high energy electrons to inhibit intraocular proliferation

    International Nuclear Information System (INIS)

    Velikay, M.; Binder, S.; Stolba, U.; Wedrich, AJ.; Datlinger, P.; Handl-Zeller, L.

    1994-01-01

    Since 1980, the fibroblast model creating experimental proliferative vitreoretinopathy has been used to evaluate the antiproliferative effect of various drugs. In previous studies radiation therapy was found to reduce effectively intraocular proliferation in this model. We therefore investigated the effect of high energy electrons in a standard perforating injury model creating a traumatic proliferative vitreoretinopathy. In 36 eyes we performed a 8 mm pars plana incision and injected 0.4 ml of 80% fibronection solution intravitreally. Ten rabbits (20 eyes) received radiation therapy with a Betatron accelerator in a total dosage of 3000 cGy to each eye divided into 10 single fractions starting on the first post-operative day. Maximum concentration of the dose was focused to the posterior vitreous. The other 9 rabbits, 18 eyes, served as control. In our perforating injury model we observed a reduction of retinal detachment rate of 72% in the controls to 55% in the treated group. The effect of radiation therapy with high energy electrons and total dosage of 3000 cGy was not statistically significant in experimental traumatic proliferative vitreoretinopathy. (au) (12 refs.)

  4. Chemical activation of molecules by metals: Experimental studies of electron distributions and bonding

    International Nuclear Information System (INIS)

    Lichienberger, D.L.

    1990-10-01

    This quarter has witnessed further progress both in our experimental methods of photoelectron spectroscopy and in our understanding the fundamental relationships between ionization energies and the chemistry of transition metal species. Progress continues on the new gas phase photoelectron spectrometer that combine improved capabilities for HeI/HeII UPS, XPS, and Auger investigations of organometallic molecules. Several measurements have been accomplished this year that were not possible previously. We have published the formal relationship between measured molecular ionization energies and thermodynamic bond dissociation energies, and applied the relationships to homonuclear and heteronuclear diatomic molecules, multiple bonds, and metal-ligand bonds. Studies of C-H bond activation have continued with examination of different degrees of Si-H bond addition to metals. the electronic effects of intermolecular interactions have been observed by comparing the ionizations of metal complexes in the gas phase with the ionizations of monolayer solid organometallic films prepared in ultra-high vacuum. The orientations of the molecules have been determined by scanning tunneling microscopy. Especially interesting has been the recent application of these techniques to the characterization of the soccer-ball shaped C 60 molecule, buckminsterfullerene. Studies of the following complexes are described : Fe, Os, Nb, Mo, Rh, Re, Al, and Mn. 19 refs

  5. Experimental Setups for Single Event Effect Studies

    OpenAIRE

    N. H. Medina; V. A. P. Aguiar; N. Added; F. Aguirre; E. L. A. Macchione; S. G. Alberton; M. A. G. Silveira; J. Benfica; F. Vargas; B. Porcher

    2016-01-01

    Experimental setups are being prepared to test and to qualify electronic devices regarding their tolerance to Single Event Effect (SEE). A multiple test setup and a new beam line developed especially for SEE studies at the São Paulo 8 UD Pelletron accelerator were prepared. This accelerator produces proton beams and heavy ion beams up to 107Ag. A Super conducting Linear accelerator, which is under construction, may fulfill all of the European Space Agency requirements to qualify electronic...

  6. Windowless Electron Beam Experimental Irradiation WEBExplr

    International Nuclear Information System (INIS)

    Heyse, J.

    2009-01-01

    The design of the MYRRHA/XT-ADS, the European eXperimental Accelerator Driven System for the demonstration of Transmutation, includes a high power windowless spallation target operating with liquid LBE (Lead-Bismuth Eutectic) that will be irradiated with a 600 MeV proton beam at currents of up to 2.5 mA. When considering such a high power windowless target design, a number of questions need to be addressed, such as the stability of the free surface flow and its ability to remove the power deposited by the proton beam by forced convection, the compatibility of a large hot LBE reservoir with the beam line vacuum and the outgassing of the LBE in the spallation target circuit. These issues have been studied during previous experiments supported by numerical simulations. Another crucial point in the development of the spallation target is the demonstration of the safe and stable operation of the free LBE surface during irradiation with a high power proton beam. As a first step in this program, the WEBExpIr (Windowless target Electron Beam Experimental Irradiation) experiment was set up. The purpose of the WEBExpIr experiment was to investigate the influence of LBE surface heating caused by a charged particle beam in a situation representative of the MYRRHA/XT-ADS. More in particular, we wanted to assess possible free surface distortion or shockwave effects in nominal conditions and during sudden beam on/off transient situations, as well as possible enhanced evaporation

  7. Experimental studies of stable confined electron clouds using Gabor lenses

    CERN Document Server

    Meusel, O.; Glaeser, B.; Schulte, K.

    2013-04-22

    Based on the idea of D. Gabor [1] space charge lenses are under investigation to be a powerful focussing device for intense ion beams. A stable confined electron column is used to provide strong radially symmetric electrostatic focussing, e.g. for positively charged ion beams. The advantages of Gabor lenses are a mass independent focussing strength, space charge compensation of the ion beam and reduced magnetic or electric fields compared to conventional focussing devices. Collective phenomena of the electron cloud result in aberrations and emittance growth of the ion beam. The knowledge of the behaviour of the electron cloud prevents a decrease of the beam brilliance. Numerical models developed to describe the electron confinement and dynamics within a Gabor lens help to understand the interaction of the ion beam with the electron column and show the causes of non-neutral plasma instabilities. The diagnosis of the electron cloud properties helps to evaluate the numerical models and to investigate the influen...

  8. New experimental initiatives using very highly charged ions from an 'electron beam ion trap'

    International Nuclear Information System (INIS)

    Schneider, D.

    1996-01-01

    A short review of the experimental program in highly-charged heavy ion physics conducted at the Lawrence Livermore National Laboratory Electron Beam Ion Trap (EBIT) facility is presented. The heavy-ion research, involving ions up to fully stripped U 92+ , includes precision x-ray spectroscopy and lifetime studies, electron impact ionization and excitation cross section measurements. The investigations of ion-surface interactions following the impact of high-Z highly charged ions on surfaces are aimed to study the neutralization dynamics effecting the ion and the response of the surface as well. (author)

  9. Present status of the ETL electron linac and associated experimental facilities

    International Nuclear Information System (INIS)

    Tomimasu, T.

    1983-01-01

    The 500-MeV electron linac ''TELL'' is operated since Dec. 1980. The main features of TELL are high efficiency, high current - high power acceleration and economical beam sharing to four experimental rooms at the same time. The available beam current is 240 mA (--180 μA ) at 300 MeV at present. A pion channel ( QQDQ ) with solid angle larger than 0.15 sr is under construction. Research on establishing spectro-dosimetric standards of high energy - high intensity electrons, X-rays and pions are in progress. The 600-MeV storage ring ''TERAS'' is operated since Oct. 1981. The circumference is 31.45 m and lambdasub(p) is 22 A. The maximum stored current is 150 mA and 1/e lifetime is 1.5 hours at present. Studies on photometry and soft X ray standards, electronic materials and lithography technology are in progress using synchrotron radiation. (author)

  10. Experimental investigations of interaction of supercritical electron beams with plasma

    International Nuclear Information System (INIS)

    Chupikov, P.T.; Medvedev, D.V.; Onishchenko, I.N.; Panasenko, B.D.; Faehl, R.J.

    2002-01-01

    The first section of the collective ions acceleration based on simultaneous temporal and spatial modulation of relativistic electron beam (REB) was studied experimentally. The virtual cathode was originated in the electrodynamic structure consisting of two tubes with different diameters (jump of electrodynamics) by REB, produced in magnetically insulated diode. At plasma assistance the low-frequency oscillations of REB current and the low-frequency microwave radiation were obtained due to the virtual cathode periodical relaxation in the processes of charge compensation by ionized residual gas

  11. Status of experimental studies of electron cloud effects at the Los Alamos proton storage ring

    International Nuclear Information System (INIS)

    Macek, R.J.; Browman, A.A.; Borden, M.J.; Fitzgerald, D.H.; McCrady, R.C.; Spickermann, T.J.; Zaugg, T.J.

    2004-01-01

    Various electron cloud effects (ECE) including the two-stream (e-p) instability at the Los Alamos Proton Storage Ring (PSR) have been studied extensively for the past five years with the goal of understanding the phenomena, mitigating the instability and ultimately increasing beam intensity. The specialized diagnostics used in the studies are two types of electron detectors, the retarding field analyzer and the electron sweepmg detector - which have been employed to measure characteristics of the electron cloud as functions of time, location in the ring and various influential beam parameters - plus a short stripline beam position monitor used to measure high frequency motion of the beam centroid. Highlights of this research program are summarized along with more detail on recent results obtained since the ECLOUD'02 workshop. Recent work mcludes a number of parametric studies of the various factors that affect the electron cloud signals, studies of the sources of initial or 'seed' electrons, additional observations of electron cloud dissipation after the beam pulse is extracted, studies of the 'first pulse instability' issue, more data on electron suppression as a cure for the instability, and observations of the effect of a one-turn weak kick on intense beams in the presence of a significant electron cloud.

  12. WEBEXPIR: Windowless target electron beam experimental irradiation

    International Nuclear Information System (INIS)

    Dierckx, Marc; Schuurmans, Paul; Heyse, Jan; Rosseel, Kris; Tichelen, Katrien Van; Nactergal, Benoit; Vandeplassche, Dirk; Aoust, Thierry; Abs, Michel; Guertin, Arnaud; Buhour, Jean-Michel; Cadiou, Arnaud; Abderrahim, Hamid Ait

    2008-01-01

    The windowless target electron beam experimental irradiation (WEBEXPIR) program was set-up as part of the MYRRHA/XT-ADS R and D effort on the spallation target design to investigate the interaction of a proton beam with a liquid lead-bismuth eutectic (LBE) free surface. In particular, possible free surface distortion or shockwave effects in nominal conditions and during sudden beam on/off transient situations, as well as possible enhanced evaporation were assessed. An experiment was conceived at the IBA TT-1000 Rhodotron, where a 7 MeV electron beam was used to simulate the high power deposition at the MYRRHA/XT-ADS LBE free surface. The geometry and the LBE flow characteristics in the WEBEXPIR set-up were made as representative as possible of the actual situation in the MYRRHA/XT-ADS spallation target. Irradiation experiments were carried out at beam currents of up to 10 mA, corresponding to 40 times the nominal beam current necessary to reproduce the MYRRHA/XT-ADS conditions. Preliminary analyses show that the WEBEXPIR free surface flow was not disturbed by the interaction with the electron beam and that vacuum conditions stayed well within the design specifications

  13. Experimental and DFT studies of (E)-2-[2-(2,6-dichlorophenyl)ethenyl]-8-hydroxyquinoline: Electronic and vibrational properties

    Science.gov (United States)

    Sun, Wenqi; Yuan, Guozan; Liu, Jingxin; Ma, Li; Liu, Chengbu

    2013-04-01

    The title molecule (E)-2-[2-(2,6-dichlorophenyl)ethenyl]-8-hydroxyquinoline (DPEQ) was synthesized and characterized by FT-IR, UV-vis, NMR spectroscopy. The molecular geometry, vibrational frequencies and gauge independent atomic orbital (GIAO) 1H and 13C NMR chemical shift values of the compound in the ground state have been calculated by using the density functional theory (DFT) method. All the assignments of the theoretical frequencies were performed by potential energy distributions using VEDA 4 program. The calculated results indicate that the theoretical vibrational frequencies, 1H and 13C NMR chemical shift values show good agreement with experimental data. The electronic properties like UV-vis spectral analysis and HOMO-LUMO analysis of DPEQ have been reported and compared with experimental data. Information about the size, shape, charge density distribution and site of chemical reactivity of the molecule has been obtained by mapping electron density isosurface with molecular electrostatic potential (MEP).

  14. Electron density measurement in an evolving plasma. Experimental devices

    International Nuclear Information System (INIS)

    Consoli, Terenzio; Dagai, Michel

    1960-01-01

    The experimental devices described here allow the electron density measurements in the 10 16 e/m 3 to 10 20 e/m 3 interval. Reprint of a paper published in Comptes rendus des seances de l'Academie des Sciences, t. 250, p. 1223-1225, sitting of 15 February 1960 [fr

  15. Experimental Search for a Heavy Electron

    Science.gov (United States)

    Boley, C. D.; Elias, J. E.; Friedman, J. I.; Hartmann, G. C.; Kendall, H. W.; Kirk, P.N.; Sogard, M. R.; Van Speybroeck, L. P.; de Pagter, J. K.

    1967-09-01

    A search for a heavy electron of the type considered by Low and Blackmon has been made by studying the inelastic scattering of 5 BeV electrons from hydrogen. The search was made over a range of values of the mass of the heavy electron from 100 t0 1300 MeV. No evidence for such a particle was observed. Upper limits on the production cross sections were determined and employed to deducelimits on the values of the electron-photon-heavy electron coupling constant in Low and Blackmon=s theory.

  16. Electron microscopic study of spontaneous and experimentally induced leukemia in IRC mice

    International Nuclear Information System (INIS)

    Hiraki, S.; Ranadive, K.J.; Dmochowski, L.

    1974-01-01

    Spontaneous, serially transplanted, and experimentally induced leukemias of ICRC mice were studied by electron microscopy in an attempt to detect the presence of virus particles, if any, and to observe the influence of chemical and hormonal treatment on the presence of these virus particles. The first series of experiments included spontaneous, serially transplanted, and radiation-induced leukemia. The paucity of type C virus particles was quite conspicuous in spontaneous leukemia. Serially transplanted and radiation-accelerated leukemic lesions showed the presence of some type C and intracisternal type A particles. Found in two of these leukemic lesions (thymus and lymphosarcoma), in addition to type C virus particles, were budding and some mature type B virus particles, and numerous intracytoplasmic type A particles. ''Viropexis'' of type B virus particles has been observed in the lymphosarcoma and in a leukemic thymus gland. The second series of experiments included leukemia induced in ovariectomized ICRC mice with 20-methylcholanthrene (MCA), pituitary transplants, and ovarian hormones (estradiol and estradiol-progesterone). In ovariectomized ICRC mice, leukemic lesions induced by MCA or pituitary transplants, or by MCA and pituitary transplants, showed type C virus particles and, in most cases, intracisternal type A particles. In leukemia induced in ovariectomized ICRC mice by MCA and estradiol, numerous intracytoplasmic type A particles were observed but no type C virus particles

  17. Automation and instrument control applied to an experimental study of electron transport dynamics in an avalanche mode resistive plater chamber

    International Nuclear Information System (INIS)

    Ridenti, Marco A.; Pascholati, Paulo R.

    2009-01-01

    In this work it is presented a computer based instrumentation system which was developed to perform data acquisition and integrate the control of different devices in an experimental study of electron transport dynamics in an avalanche mode resistive plate chamber detector in the Radiation Technology Center (CTR) at IPEN/CNEN-SP. System control and data acquisition was performed by a computer program called RPCLabOperator written in MatLab environment running on a LeCroy WavePro 7000 digital oscilloscope. (author)

  18. An experimental study of the role of autoionizing states of H2 (D2) in the production of energetic protons (deuterons) by electron impact

    International Nuclear Information System (INIS)

    Landau, M.

    1982-06-01

    The autoionizing state study seemed interesting to be taken up again in energy ranges corresponding to formation thresholds, a device well adapted to this range was available concerning electron measurements. Among other things, the overlapping autoionizing states have been displayed; proton kinetic energy distribution appropriate to each state at its formation threshold have been got. The whole of these results represents a proton (and D + ) production mechanism study contribution via autoionizing states. The theory used to describe autoionization cross-section calculations are recalled. Experimental results are presented, discussed, compared to experimental results and theoretical predictions [fr

  19. FIRST EXPERIMENTAL RESULTS FROM DEGAS, THE QUANTUM LIMITED BRIGHTNESS ELECTRON SOURCE

    International Nuclear Information System (INIS)

    Zolotorev, Max S.; Commins, Eugene D.; Oneill, James; Sannibale, Fernando; Tremsin, Anton; Wan, Weishi

    2008-01-01

    The construction of DEGAS (DEGenerate Advanced Source), a proof of principle for a quantum limited brightness electron source, has been completed at the Lawrence Berkeley National Laboratory. The commissioning and the characterization of this source, designed to generate coherent single electron 'bunches' with brightness approaching the quantum limit at a repetition rate of few MHz, has been started. In this paper the first experimental results are described

  20. Experimental study of the stability of a neutralized electron beam

    International Nuclear Information System (INIS)

    Kudelainen, V.I.; Parkhomchuk, V.V.; Pestrikov, D.V.

    1983-01-01

    Results are reported from measurements of the spectral properties of a long neutralized electron beam in the NAP-M proton storage ring. It is shown that when the number of secondary electrons is small, both the longitudinal and the transverse oscillations are strongly damped, so that beam instability is suppressed. The current density of the neutralized electron beam produced in the experiments was approx.10 2 times greater than the theoretical value determined from the instability threshold for nonaxisymmetric oscillations

  1. Electronic transport in VO{sub 2}—Experimentally calibrated Boltzmann transport modeling

    Energy Technology Data Exchange (ETDEWEB)

    Kinaci, Alper; Rosenmann, Daniel; Chan, Maria K. Y., E-mail: debasish.banerjee@toyota.com, E-mail: mchan@anl.gov [Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Kado, Motohisa [Higashifuji Technical Center, Toyota Motor Corporation, Susono, Shizuoka 410-1193 (Japan); Ling, Chen; Zhu, Gaohua; Banerjee, Debasish, E-mail: debasish.banerjee@toyota.com, E-mail: mchan@anl.gov [Materials Research Department, Toyota Motor Engineering and Manufacturing North America, Inc., Ann Arbor, Michigan 48105 (United States)

    2015-12-28

    Materials that undergo metal-insulator transitions (MITs) are under intense study, because the transition is scientifically fascinating and technologically promising for various applications. Among these materials, VO{sub 2} has served as a prototype due to its favorable transition temperature. While the physical underpinnings of the transition have been heavily investigated experimentally and computationally, quantitative modeling of electronic transport in the two phases has yet to be undertaken. In this work, we establish a density-functional-theory (DFT)-based approach with Hubbard U correction (DFT + U) to model electronic transport properties in VO{sub 2} in the semiconducting and metallic regimes, focusing on band transport using the Boltzmann transport equations. We synthesized high quality VO{sub 2} films and measured the transport quantities across the transition, in order to calibrate the free parameters in the model. We find that the experimental calibration of the Hubbard correction term can efficiently and adequately model the metallic and semiconducting phases, allowing for further computational design of MIT materials for desirable transport properties.

  2. First experimental results of the BNL inverse free electron laser accelerator

    International Nuclear Information System (INIS)

    Steenbergen, A. van; Gallardo, J.; Babzien, M.; Skaritka, J.; Wang, X.J.; Sandweiss, J.; Fang, J.M.; Qiu, X.

    1996-10-01

    A 40 MeV electron beam, using the inverse3e free-electron laser interaction, has been accelerated by ΔE/E = 2.5% over a distance of 0.47 m. The electrons interact with a 1--2 GW CO 2 laser beam bounded by a 2.8 mm ID sapphire circular waveguide in the presence of a tapered wiggler with Bmax ∼ 1 T and a period 2.89 cm ≤ λ w ≤ 3.14 cm. The experimental results of ΔE/E as a function of electron energy E, peak magnetic field Bw and laser power W 1 compare well with analytical and 1-D numerical simulations and permit scaling to higher laser power and electron energy

  3. Automation of electron channeling investigations into crystals on the experimental stand

    International Nuclear Information System (INIS)

    Kolodin, L.G.; Kupchishin, A.A.; Bunegin, V.V.

    1995-01-01

    Automated control system of technological processes of the experimental stand is proposed for electron channeling investigation into crystals. The system is proposed for stand control automation and registration of corresponding radiations. There are four main parts in stand complex: Ehlu-6 type electron accelerator; forming and transporting system of electron beams; goniometer system; radiation detection system. Purposes of the automated system creation are following: - improvement of EhLU accelerator operating stability by of automation stabilization of its parameters; - quality improvement of electron beam monochromatization by of automation of monochromator electromagnet control; - simplification of crystal adjustment process relatively of primary electron beam and crystal transporting to the position by of goniometer automation control; - providing of automating collection and processing of data of physical experiments

  4. Ultrafast electron diffraction studies of optically excited thin bismuth films

    International Nuclear Information System (INIS)

    Rajkovic, Ivan

    2008-01-01

    This thesis contains work on the design and the realization of an experimental setup capable of providing sub-picosecond electron pulses for ultrafast electron diffraction experiments, and performing the study of ultrafast dynamics in bismuth after optical excitation using this setup. (orig.)

  5. Ultrafast electron diffraction studies of optically excited thin bismuth films

    Energy Technology Data Exchange (ETDEWEB)

    Rajkovic, Ivan

    2008-10-21

    This thesis contains work on the design and the realization of an experimental setup capable of providing sub-picosecond electron pulses for ultrafast electron diffraction experiments, and performing the study of ultrafast dynamics in bismuth after optical excitation using this setup. (orig.)

  6. Experimental and theoretical study of the signal electron motion in fully depleted silicon

    International Nuclear Information System (INIS)

    Kimmel, N.; Andritschke, R.; Hartmann, R.; Holl, P.; Meidinger, N.; Richter, R.; Strueder, L.

    2010-01-01

    Imaging spectrometers based on a fully depleted silicon substrate are sensitive over the whole device volume. Therefore, a high detection efficiency for X-rays of up to 20 keV is achieved. Our experimental method facilitates measurements of the detected signal pulse height in a pixel as a function of the photon conversion position in the pixel array. Further analysis of the measurements delivers the size of a signal electron cloud after its drift from the photon conversion position to the storage cells. These results can be used to reconstruct the conversion position of each detected X-ray photon. A reconstruction accuracy of 1μm can be achieved with a pixel size of 51μm. Complementary to the measurements, we have created a physical model of the signal electron collection process. The change of the drift mobility with the electric drift field strength in the detection volume is considered in order to correctly describe the drift speed of the charge cloud. The electric field values and the values of the charge density in the detector volume are delivered by numerical device simulations with the software package 'TeSCA'. Comparisons of the simulations with the measurements confirmed the correctness of the applied physical model. We have thus established a method which enables device designers to simulate the process of signal charge collection in future detector concepts.

  7. Experimental modelling of the dipole magnet for the electron storage ring DELSY

    CERN Document Server

    Meshkov, I N; Syresin, E M

    2003-01-01

    In the Joint Institute for Nuclear Research (Dubna) the project of Dubna Electron Synchrotron (DELSY) with an electron energy of 1.2 GeV is developed. The electron storage ring in the DELSY project is planned to be created on the basis of magnetic elements, which were used earlier in the storage ring AmPS (NIKHEF, Amsterdam). The optics of the ring is necessary to be changed, its perimeter to be reduced approximately in one and a half time, the energy of electrons to be increased. The paper is devoted to the development of a modified dipole magnet of the storage ring. The preliminary estimation of geometry of the magnet pole is carried out by means of computer modelling using two- and three- dimensional codes of the magnetic field calculation SUPERFISH and RADIA. The experimental stand for the measurements of the dipole magnetic field is described. As the result of calculational and experimental modelling for the dipole magnet, the geometry of its poles was estimated, providing in the horizontal aperture +- 3...

  8. Experimental study of humidity distribution inside electronic enclosure and effect of internal heating

    DEFF Research Database (Denmark)

    Conseil, Helene; Jellesen, Morten Stendahl; Ambat, Rajan

    2016-01-01

    on the humidity and temperature profile inside typical electronic enclosures. Defined parameters include external temperature and humidity conditions, temperature and time of the internal heat cycle, thermal mass, and ports/openings size. The effect of the internal humidity on electronic reliability has been......Corrosion reliability of electronic products is a key factor for electronics industry, and today there is a large demand for performance reliability in a wide range of temperature and humidity during day and night time periods. Corrosion failures are still a challenge due to the combined effects...... of temperature, humidity and corrosion accelerating species in the atmosphere. Moreover the surface region of printed circuit board assemblies is often contaminated by various aggressive chemical species.This study describes the overall effect of the exposure to severe climate conditions and internal heat cycles...

  9. Experimental and theoretical double differential cross sections for electron impact ionization of methane

    Energy Technology Data Exchange (ETDEWEB)

    Yavuz, Murat; Ozer, Zehra Nur, E-mail: zehraerengil@aku.edu.tr; Ulu, Melike; Dogan, Mevlut [e-COL Laboratory, Department of Physics, Afyon Kocatepe University, Afyonkarahisar 03200 (Turkey); Champion, Christophe [Centre d’Etudes Nucléaires de Bordeaux Gradignan, CNRS/IN2P3, Université de Bordeaux, Gradignan 33170 (France)

    2016-04-28

    Experimental and theoretical double differential cross sections (DDCSs) for electron-induced ionization of methane (CH{sub 4}) are here reported for primary energies ranging from 50 eV to 350 eV and ejection angles between 25° and 130°. Experimental DDCSs are compared with theoretical predictions performed within the first Born approximation Coulomb wave. In this model, the initial molecular state is described by using single center wave functions, the incident (scattered) electron being described by a plane wave, while a Coulomb wave function is used for modeling the secondary ejected electron. A fairly good agreement may be observed between theory and experiment with nevertheless an expected systematic overestimation of the theory at low-ejection energies (<50 eV).

  10. Experimental study on nonlinear vibrating of aluminum foam using electronic speckle pattern interferometry

    Science.gov (United States)

    Yang, Fujun; Ma, Yinhang; Tao, Nan; He, Xiaoyuan

    2017-06-01

    Due to its multi properties, including excellent stiffness-to-weight and strength-to-weight ratios, closed-cell aluminum and its alloy foams become candidate materials for use in many high-technology industries, such as the automotive and aerospace industries. For the efficient use of closed-cell foams in structural applications, it is necessary and important to detailly understand their mechanical characteristics. In this paper, the nonlinear vibration responses of the cantilever beams of closed-cell aluminum foams were investigated by use of electronic speckle pattern interferometry (ESPI). The nonlinear resonant mode shapes of testing specimens under harmonic excitation were measured. It is first time to obtain from the experimental results that there exist super-harmonic responses when the cantilever beams of closed-cell aluminum foam were forced to vibrate, which was caused by its specific cellular structures.

  11. Experimental research of double-pulse linear induction electron accelerator

    International Nuclear Information System (INIS)

    Liao Shuqing; Cheng Cheng; Zheng Shuxin; Tang Chuanxiang; Lin Yuzheng; Jing Xiaobing; Mu Fan; Pan Haifeng

    2009-01-01

    The Mini-LIA is a double-pulse linear induction electron accelerator with megahertz repetition rates, which consists of a double-pulse power system, a thermal cathode electron gun, two induction cells, beam transportation systems and diagnosis systems, etc. Experiments of the Mini-LIA have been conducted. The double-pulse high voltage was obtained with several hundred nanosecond pulse intervals (i. e. megahertz repetition rate) and each pulse had an 80 kV amplitude with a FWHM of 80 ns. In the gap of the induction cell, the double-pulse accelerating electric field was measured via E-field probes, and the double-pulse electron beam with a current about 1.1 A has been obtained at the Mini-LIA exit. These experimental results show that the double-pulse high voltage with megahertz repetition rates can be generated by an insulation and junction system. And they also indicate that the induction cell with metglas as the ferromagnetic material and the LaB 6 thermal cathode electron gun suit the double-pulse operation with megahertz repetition rates. (authors)

  12. Experimental and theoretical study of very-low-energy inelastic processes in electron-molecule collisions. Progress report, March 20, 1982-March 20, 1983

    International Nuclear Information System (INIS)

    Golden, D.E.; Morrison, M.

    1983-01-01

    Objectives of this research are: to determine accurate integrated and differential cross sections for low energy electron-molecule elastic scattering, excitation and ionization; to develop, implement, and test new experimental and theoretical procedures for studying low energy collision processes; and to contribute to basic understanding of a fundamental problem in atomic collision physics, the interaction of a charged particle with a non-spherical target that is rich in structure

  13. Theoretical and experimental studies of elementary physics

    International Nuclear Information System (INIS)

    Bodek, A.; Ferbel, T.; Melissinos, A.C.; Slattery, P.; Tipton, P.; Das, A.; Hagen, C.R.; Rajeev, S.G.; Okubo, S.; Orr, L.

    1993-01-01

    The various components of the high-energy physics research program at the University of Rochester are presented. (I)Fixed-target experimentation at FNAL includes studies of direct photon production by p and π on H, Be, and Cu, and hybrid mesons and other physics issues in Coulomb excitation at high energies. (II)The status of the GEM (Gammas, Electrons, and Muons) Experiment at the SSC is given. (III)The D-Zero experiment at FNAL is reviewed. (IV)Deep inelastic lepton--nucleon scattering experiments are summarized: electron scattering experiments at SLAC, FNAL neutrino quad triplet runs, FNAL neutrino sign selected experiments, and SDC cosmic ray test and test beam calibration. (V)Studies of nonlinear QED at SLAC concentrated on a study of QED at critical field strength in intense laser--high-energy electron collisions. (VI)Development work on the Collider Detector at Fermilab (CDF) emphasized the CDF silicon vertex detector, the end plug calorimeter, and the SDC tile/fiber calorimetry. (VII)The theoretical physics effort is sketched

  14. Contribution to the study of electron paramagnetic resonance and relaxation

    International Nuclear Information System (INIS)

    Theobald, Jean-Gerard

    1962-01-01

    This research thesis reports an experimental work which comprises the development of a very practical and very sensitive electron paramagnetic resonance spectrometer, and the use of this equipment for the study of irradiated substances and carbons. By studying electronic resonance signals by fast modulation of the magnetic field, the author studied phenomena of quick passage in electronic resonance, and showed that the study of these phenomena requires observation systems with a particularly large bandwidth. He reports the measurement of the line width of packs of spins of inhomogeneous lines by two different methods [fr

  15. EBIT (Electron Beam Ion Trap), N-Division Experimental Physics. Annual report, 1994

    International Nuclear Information System (INIS)

    Schneider, D.

    1995-10-01

    The experimental groups in the Electron Beam Ion Trap (EBIT) program continue to perform front-line research with trapped and extracted highly charged ions (HCI) in the areas of ion/surface interactions, atomic spectroscopy, electron-ion interaction and structure measurements, highly charged ion confinement, and EBIT development studies. The ion surface/interaction studies which were initiated five years ago have reached a stage where they an carry out routine investigations, as well as produce breakthrough results towards the development of novel nanotechnology. At EBIT and SuperEBIT studies of the x-ray emission from trapped ions continue to produce significant atomic structure data with high precision for few electron systems of high-Z ions. Furthermore, diagnostics development for magnetic and laser fusion, supporting research for the x-ray laser and weapons programs, and laboratory astrophysics experiments in support of NASA's astrophysics program are a continuing effort. The two-electron contributions to the binding energy of helium like ions were measured for the first time. The results are significant because their precision is an order of magnitude better than those of competing measurements at accelerators, and the novel technique isolates the energy corrections that are the most interesting. The RETRAP project which was initiated three years ago has reached a stage where trapping, confining and electronic cooling of HCI ions up to Th 80+ can be performed routinely. Measurements of the rates and cross sections for electron transfer from H 2 performed to determine the lifetime of HCI up to Xe q+ and Th q+ (35 ≤ q ≤ 80) have been studied at mean energies estimated to be ∼ 5 q eV. This combination of heavy ions with very high charges and very low energies is rare in nature, but may be encountered in planned fusion energy demonstration devices, in highly charged ion sources, or in certain astrophysical events

  16. Some recent studies of electron swarms in gases

    International Nuclear Information System (INIS)

    Tagashira, H.

    1992-01-01

    Some recent studies of electron swarms in gases under the action of an electric field are introduced. The studies include a new type of continuity equation for electrons having a form in which the partial derivative of the electron density with respect to position and to time are interchanged, a method to deduce the time-of-flight and arrival-time-spectrum swarm parameters based on a Fourier-transformed Boltzmann equation, an examination of the correspondence between experimental and theoretical electron drift velocities, and an automatic technique to deduce the electron-gas molecule collision cross section from electron drift velocity data. A method for the deduction of electron collision cross sections with gas molecules having vibrational excitation cross sections greater than the elastic momentum transfer cross section by using a gas mixture technique, an integral type of method for solution of the Boltzmann equation with salient numerical stability, a quantitative analysis of the effect of Penning ionisation, and the behaviour of electron swarms under radio frequency electric fields, are also briefly discussed. 28 refs., 3 figs

  17. Study of the electron heat transport in Tore-Supra tokamak

    International Nuclear Information System (INIS)

    Harauchamps, E.

    2004-01-01

    This work presents analytical solutions to the electron heat transport equation involving a damping term and a convection term in a cylindrical geometry. These solutions, processed by Matlab, allow the determination of the evolution of the radial profile of electron temperature in tokamaks during heating. The modulated injection of waves around the electron cyclotron frequency is an efficient tool to study heat transport experimentally in tokamaks. The comparison of these analytical solutions with experimental results from Tore-Supra during 2 discharges (30550 and 31165) shows the presence of a sudden change for the diffusion and damping coefficients. The hypothesis of the presence of a pinch spread all along the plasma might explain the shape of the experimental temperature profiles. These analytical solutions could be used to determine the time evolution of plasma density as well or of any parameter whose evolution is governed by a diffusion-convection equation. (A.C.)

  18. Study of fast electrons from hard-X radiation

    International Nuclear Information System (INIS)

    Arslanbekov, R.

    1995-01-01

    The goal of this thesis is the study of fast electron dynamics by means of the hard X-ray diagnosis installed in TORE SUPRA and numerical simulations. Fast electrons are generated in the plasma in the presence of the injected lower hybrid (LH) waves. Two aspects are studied in detail: the lower hybrid wave propagation and absorption in a periodically perturbed media and 2-D Fokker-Planck modelling of the fast electron dynamics in the presence of the LH power. Ripple effects on lower hybrid wave propagation and absorption are investigated using the ray tracing technique. A cylindrical equilibrium is first studied and a strong modification of the ray dynamics is predicted. Calculations are carried out in a real toroidal geometry corresponding to TORE SUPRA. It is shown that the lack of toroidal axisymmetry of the magnetic field may result in a modification of the ray evolution even if the global ray evolution is governed by the larger poloidal inhomogeneity. Simulation of LH experiments are performed for TORE SUPRA tokamak which has a large magnetic ripple (7% at the plasma edge). By considering ripple perturbation in LH current drive simulations, a better agreement is found with experimental results, in particular with the hard-X spectra and the current density profiles. In the second part of the thesis, a 2-D modeling of the fast electron dynamics in the velocity phase space is considered, based on the 2-D relativistic electron Fokker-Planck equation. Electron distribution functions obtained are used to calculate non-thermal Bremsstrahlung emission for different TORE SUPRA shots in a wide range of experimental conditions. (J.S.). 168 refs., 93 figs., 1 tab., 3 appendix

  19. Study of loading by beam of dual-resonator structure of linear electron accelerator

    International Nuclear Information System (INIS)

    Milovanov, O.S.; Smirnov, I.A.

    1988-01-01

    Loading by the beam of the accelerating structure of an Argus dual-resonator linear electron accelerator with a kinetic energy of ∼ 1 MeV and a pulsed beam current of up to 0.5 A is studied experimentally. It is shown that the conditions for stable single-frequency operation of the magnetron are disrupted and the acceleration process is cut off at certain electron-beam currents. Experimental curves of the maximum beam current and maximum electron efficiency of the Argus linear electron accelerator as functions of rf power are given

  20. Theoretical and experimental differential cross sections for electron impact excitation of the electronic bands of furfural

    Science.gov (United States)

    Jones, D. B.; Neves, R. F. C.; Lopes, M. C. A.; da Costa, R. F.; do N. Varella, M. T.; Bettega, M. H. F.; Lima, M. A. P.; García, G.; Limão-Vieira, P.; Brunger, M. J.

    2016-03-01

    We report results from a joint experimental and theoretical investigation into electron scattering from the important industrial species furfural (C5H4O2). Specifically, differential cross sections (DCSs) have been measured and calculated for the electron-impact excitation of the electronic states of C5H4O2. The measurements were carried out at energies in the range 20-40 eV, and for scattered-electron angles between 10° and 90°. The energy resolution of those experiments was typically ˜80 meV. Corresponding Schwinger multichannel method with pseudo-potential calculations, for energies between 6-50 eV and with and without Born-closure, were also performed for a sub-set of the excited electronic-states that were accessed in the measurements. Those calculations were undertaken at the static exchange plus polarisation-level using a minimum orbital basis for single configuration interaction (MOB-SCI) approach. Agreement between the measured and calculated DCSs was qualitatively quite good, although to obtain quantitative accord, the theory would need to incorporate even more channels into the MOB-SCI. The role of multichannel coupling on the computed electronic-state DCSs is also explored in some detail.

  1. Theoretical and experimental differential cross sections for electron impact excitation of the electronic bands of furfural

    International Nuclear Information System (INIS)

    Jones, D. B.; Neves, R. F. C.; Lopes, M. C. A.; Costa, R. F. da; Varella, M. T. do N; Bettega, M. H. F.; Lima, M. A. P.; García, G.

    2016-01-01

    We report results from a joint experimental and theoretical investigation into electron scattering from the important industrial species furfural (C 5 H 4 O 2 ). Specifically, differential cross sections (DCSs) have been measured and calculated for the electron-impact excitation of the electronic states of C 5 H 4 O 2 . The measurements were carried out at energies in the range 20–40 eV, and for scattered-electron angles between 10° and 90°. The energy resolution of those experiments was typically ∼80 meV. Corresponding Schwinger multichannel method with pseudo-potential calculations, for energies between 6–50 eV and with and without Born-closure, were also performed for a sub-set of the excited electronic-states that were accessed in the measurements. Those calculations were undertaken at the static exchange plus polarisation-level using a minimum orbital basis for single configuration interaction (MOB-SCI) approach. Agreement between the measured and calculated DCSs was qualitatively quite good, although to obtain quantitative accord, the theory would need to incorporate even more channels into the MOB-SCI. The role of multichannel coupling on the computed electronic-state DCSs is also explored in some detail.

  2. Experimental study of spatial distribution of Ar glow discharge plasma

    International Nuclear Information System (INIS)

    Guo, X.M.; Zhou, T.D.; Pai, S.T.

    1996-01-01

    The characteristics of the spatial distribution of Ar glow discharge plasma were experimentally investigated. By means of direct comparisons between theory and experiment, the effects of the variation of gap separation, gas pressure, and electrode radius on the spatial distributions of electron density and electric field were studied. Results indicate that the maximum electron density moves toward the cathode as the gap separation or gas pressure increases while variation of electrode radius produces little effect. Predictions from a theoretical model have been experimentally verified. General agreements between theory and experiment were found to be reasonably good except in the cathode region, where discrepancy exists. copyright 1996 American Institute of Physics

  3. Use of electronic cigarettes among Romanian university students: a cross-sectional study.

    Science.gov (United States)

    Lotrean, Lucia Maria

    2015-04-11

    Because electronic cigarettes are relatively new, data on usage patterns and factors which influence them are sparse. Hence, this study aims at assessing awareness, beliefs about electronic cigarettes and experimentation with them among university students from Romania- a country where the sales and marketing of these products are widespread. Secondly, correlates of electronic cigarette experimentation will also be investigated. A cross-sectional study was performed by means of anonymous questionnaires among 480 students, aged 19-24, from Cluj-Napoca, Romania, between April-May 2013. The results show that 92.5% of the students have heard about e-cigarettes; out of these, one quarter (53.3% of the smokers, 25% of the ex-smokers, 5.5% of the non-smokers) have tried electronic cigarettes at least once during lifetime. The results of the multinomial logistic regression point out that the correlates of electronic cigarette experimentation were: male gender, being a smoker of traditional cigarettes, having friends who experimented with electronic cigarettes, having stronger beliefs that electronic cigarettes could help them quit smoking and being less convinced that they are used only by smokers. The explained variance was 59%. The results underline the importance of addressing the issue of e-cigarette use through health education programs and regulatory interventions, since e-cigarettes are a reality faced by the Romanian youth.

  4. A combined experimental and analytical approach for interface fracture parameters of dissimilar materials in electronic packages

    International Nuclear Information System (INIS)

    Kay, N.R.; Ghosh, S.; Guven, I.; Madenci, E.

    2006-01-01

    This study concerns the development of a combined experimental and analytical technique to determine the critical values of fracture parameters for interfaces between dissimilar materials in electronic packages. This technique utilizes specimens from post-production electronic packages. The mechanical testing is performed inside a scanning electron microscope while the measurements are achieved by means of digital image correlation. The measured displacements around the crack tip are used as the boundary conditions for the analytical model to compute the energy release rate. The critical energy release rate values obtained from post-production package specimens are obtained to be lower than those laboratory specimens

  5. Study of runaway electron generation during major disruptions in JET

    International Nuclear Information System (INIS)

    Plyusnin, V.V.; Riccardo, V.; Jaspers, R.; Alper, B.; Kiptily, V.G.; Mlynar, J.; Popovichev, S.; Luna, E. de La; Andersson, F.

    2006-01-01

    Extensive analysis of disruptions in JET has helped advance the understanding of trends of disruption-generated runaway electrons. Tomographic reconstruction of the soft x-ray emission has made possible a detailed observation of the magnetic flux geometry evolution during disruptions. With the aid of soft and hard x-ray diagnostics runaway electrons have been detected at the very beginning of disruptions. A study of runaway electron parameters has shown that an approximate upper bound for the conversion efficiency of pre-disruptive plasma currents into runaways is about 60% over a wide range of plasma currents in JET. Runaway generation has been simulated with a test particle model in order to verify the results of experimental data analysis and to obtain the background for extrapolation of the existing results onto larger devices such as ITER. It was found that close agreement between the modelling results and experimental data could be achieved if in the calculations the post-disruption plasma electron temperature was assumed equal to 10 eV and if the plasma column geometry evolution is taken into account in calculations. The experimental trends and numerical simulations show that runaway electrons are a critical issue for ITER and, therefore, the development of mitigation methods, which suppress runaway generation, is an essential task

  6. ELECTRONIC SYSTEM FOR EXPERIMENTATION IN AC ELECTROGRAVIMETRY I: TECHNIQUE FUNDAMENTALS

    Directory of Open Access Journals (Sweden)

    Róbinson Torres

    Full Text Available Basic fundamentals of AC electrogravimetry are introduced. Their main requirements and characteristics are detailed to establish the design of an electronic system that allows the appropriate extraction of data needed to determine the electrogravimetric transfer function (EGTF and electrochemical impedance (EI, in an experimental set-up for the AC electrogravimetry technique.

  7. Experimental Investigation of Charging Properties of Interstellar Type Silica Dust Grains by Secondary Electron Emissions

    Science.gov (United States)

    Tankosic, D.; Abbas, M. M.

    2013-01-01

    The dust charging by electron impact is an important dust charging processes in astrophysical and planetary environments. Incident low energy electrons are reflected or stick to the grains charging the dust grains negatively. At sufficiently high energies electrons penetrate the grains, leading to excitation and emission of electrons referred to as secondary electron emission (SEE). Available classical theoretical models for calculations of SEE yields are generally applicable for neutral, planar, or bulk surfaces. These models, however, are not valid for calculations of the electron impact charging properties of electrostatically charged micron/submicron-size dust grains in astrophysical environments. Rigorous quantum mechanical models are not yet available, and the SEE yields have to be determined experimentally for development of more accurate models for charging of individual dust grains. At the present time, very limited experimental data are available for charging of individual micron-size dust grains, particularly for low energy electron impact. The experimental results on individual, positively charged, micron-size lunar dust grains levitated carried out by us in a unique facility at NASA-MSFC, based on an electrodynamic balance, indicate that the SEE by electron impact is a complex process. The electron impact may lead to charging or discharging of dust grains depending upon the grain size, surface potential, electron energy, electron flux, grain composition, and configuration (Abbas et al, 2010, 2012). In this paper, we discuss SEE charging properties of individual micron-size silica microspheres that are believed to be analogs of a class of interstellar dust grains. The measurements indicate charging of the 0.2m silica particles when exposed to 25 eV electron beams and discharging when exposed to higher energy electron beams. Relatively large size silica particles (5.2-6.82m) generally discharge to lower equilibrium potentials at both electron energies

  8. An experimental study on cyclotron-Cherenkov radiation

    Energy Technology Data Exchange (ETDEWEB)

    Lee, C Y; Masuzaki, M; Yoshida, H; Toyosugi, N; Kamada, K; Ando, R [Kanazawa Univ. (Japan). Department of Physics

    1997-12-31

    Dielectric-loaded cylindrical waveguide configurations with an injected electron beam in which the growth rate of the cyclotron-Cherenkov instability surpasses that of the Cherenkov instability were sought by numerical treatment, and one configuration of this kind was found. This configuration consists of a metallic core and an outer metallic cylinder with a dielectric liner on the inner surface. Based on the calculations, an experimental device was designed and assembled to investigate experimentally radiation due to the cyclotron-Cherenkov instability. Beam propagation in the dielectric-loaded coaxial waveguide and microwave radiation due to the cyclotron-Cherenkov instability and the Cherenkov instability were studied. (author). 6 figs., 10 refs.

  9. Experimental study of collective processes in REB

    Energy Technology Data Exchange (ETDEWEB)

    Bogdanov, L Yu; Sominskij, G G [St. Petersburg Technical University (Russian Federation)

    1997-12-31

    The role of collective processes at relativistic electron beam formation and transportation was studied experimentally by using new low-disturbing techniques. In particular, local mirror-like enhancements of the external magnetic field were introduced and their influence of the beam space charge oscillations was investigated. The amplitude-frequency characteristics of the space charge oscillations in different parts of the drift channel were measured by a set of high-frequency probes. On the base of the collected experimental data two possible mechanisms of development of the beam space charge oscillations are discussed: the two-stream instability and the diocotron instability. (J.U.). 2 figs., 4 refs.

  10. Experimental investigation of the trapping and energy loss mechanisms of intense relativistic electron rings in hydrogen gas and plasma

    International Nuclear Information System (INIS)

    Smith, A.C. Jr.

    1977-01-01

    The results of an experimental study on the trapping and energy loss mechanisms of intense, relativistic electron rings confined in Astron-like magnetic field geometries are presented. The work is subdivided into four sections: gas trapping; average ring electron energetics; plasma trapping, and hollow-beam cusp-injection into gas and plasma. The mechanisms by which the injected beam coalesces into a current ring in the existing Cornell RECE-Berta facility are considered. To investigate the nature of ring electron energy loss mechanisms following completion of the trapping process, a diagnostic was developed utilizing multi-foil X-ray absorption spectroscopy to analyze the Bremsstrahlung generated by the electrons as they impinge upon a thin tungsten wire target suspended in the circulating current. Finally, a set of preliminary experimental results is presented in which an annular electron beam was passed through a coaxial, non-adiabatic magnetic cusp located at one end of a magnetic mirror well

  11. Study of heliumlike neon using an electron beam ion trap

    International Nuclear Information System (INIS)

    Wargelin, B.J.; Kahn, S.M.; Beiersdorfer, P.

    1992-01-01

    The 2-to-1 spectra of several astrophysically abundant He-like ions are being studied using the Electron Beam Ion Trap (EBIT) at Lawrence Livermore National Laboratory. Spectra are recorded for a broad range of plasma parameters, including electron density, energy, and ionization balance. We describe the experimental equipment and procedure and present some typical data

  12. Ab initio study on electron excitation and electron transfer in tryptophan-tyrosine system

    International Nuclear Information System (INIS)

    Tong Jing; Li Xiangyuan

    2002-01-01

    In this article, ab initio calculation has been performed to evaluate the transition energy of electronic excitation in tryptophan and tyrosine by using semiempirical molecular orbital method AM1 and complete active space self-consistent field method. The solvent effect has been considered by means of the conductor-like screening model. After geometric optimizations of isolated tryptophan and tyrosine, and their corresponding radicals and cations, reaction heat of these electron transfer reactions have been obtained by the means of complete active space self-consistent field method. The transition energies from the ground state, respectively, to the lowest excited state and to the lowest triplet state of these two amino acids are also calculated and compared with the experimentally observed values. The ionization potential and electron affinity are also calculated for tryptophan and tyrosine employing Koopmans' theorem and ab initio calculation. Compared with the experimental measurements, the theoretical results are found satisfactory. Theoretical results give good explanations on the experimental phenomena that N 3 · can preferably oxide the side chain of tryptophan residue and then the electron transfer from tyrosine residue to tryptophan residue follows in peptides involving tryptophan and tyrosine

  13. Theoretical and experimental differential cross sections for electron impact excitation of the electronic bands of furfural

    Energy Technology Data Exchange (ETDEWEB)

    Jones, D. B. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Neves, R. F. C. [Instituto Federal do Sul de Minas Gerais, Câmpus Poços de Caldas, Minas Gerais (Brazil); Departamento de Física, UFJF, Juiz de Fora, Minas Gerais 36036-900 (Brazil); Lopes, M. C. A. [Departamento de Física, UFJF, Juiz de Fora, Minas Gerais 36036-900 (Brazil); Costa, R. F. da [Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Santo André, São Paulo 09210-580 (Brazil); Instituto de Física “Gleb Wataghin,” Universidade Estadual de Campinas, Campinas, São Paulo 13083-859 (Brazil); Varella, M. T. do N [Instituto de Física, Universidade de São Paulo, CP 66318, 05315-970 São Paulo (Brazil); Bettega, M. H. F. [Departamento de Física, Universidade Federal do Paraná, CP 19044, Curitiba, Paraná 81531-990 (Brazil); Lima, M. A. P., E-mail: maplima@ifi.unicamp.br [Instituto de Física “Gleb Wataghin,” Universidade Estadual de Campinas, Campinas, São Paulo 13083-859 (Brazil); García, G. [Instituto de Física Fundamental, CSIC, Serrano 113-bis, 28006 Madrid (Spain); and others

    2016-03-28

    We report results from a joint experimental and theoretical investigation into electron scattering from the important industrial species furfural (C{sub 5}H{sub 4}O{sub 2}). Specifically, differential cross sections (DCSs) have been measured and calculated for the electron-impact excitation of the electronic states of C{sub 5}H{sub 4}O{sub 2}. The measurements were carried out at energies in the range 20–40 eV, and for scattered-electron angles between 10° and 90°. The energy resolution of those experiments was typically ∼80 meV. Corresponding Schwinger multichannel method with pseudo-potential calculations, for energies between 6–50 eV and with and without Born-closure, were also performed for a sub-set of the excited electronic-states that were accessed in the measurements. Those calculations were undertaken at the static exchange plus polarisation-level using a minimum orbital basis for single configuration interaction (MOB-SCI) approach. Agreement between the measured and calculated DCSs was qualitatively quite good, although to obtain quantitative accord, the theory would need to incorporate even more channels into the MOB-SCI. The role of multichannel coupling on the computed electronic-state DCSs is also explored in some detail.

  14. Ab initio study of hot electrons in GaAs

    OpenAIRE

    Bernardi, Marco; Vigil-Fowler, Derek; Ong, Chin Shen; Neaton, Jeffrey B.; Louie, Steven G.

    2015-01-01

    Hot carrier dynamics critically impacts the performance of electronic, optoelectronic, photovoltaic, and plasmonic devices. Hot carriers lose energy over nanometer lengths and picosecond timescales and thus are challenging to study experimentally, whereas calculations of hot carrier dynamics are cumbersome and dominated by empirical approaches. In this work, we present ab initio calculations of hot electrons in gallium arsenide (GaAs) using density functional theory and many-body perturbation...

  15. Experimental study of neoclassical currents

    International Nuclear Information System (INIS)

    Zarnstorff, M.C.; Prager, S.C.

    1985-05-01

    A detailed experimental study is presented of the bootstrap and Pfirsch-Schlueter currents that are predicted by neoclassical transport theory. In a toroidal octupole, on magnetic surfaces within the separatrix, the observed parallel plasma currents are in excellent quantitative agreement with neoclassical theory with regard to the spatial structure (along a magnetic surface), collisionality dependence and toroidal magnetic field dependence. On magnetic surfaces outside the separatrix, the ion portion of the parallel current is in agreement with neoclassical theory but the electron parallel current is observed to obtain a unidirectional component which deviates from and exceeds the theoretical prediction

  16. Studies of electron correlation in the photoionization process

    Energy Technology Data Exchange (ETDEWEB)

    Rosenberg, Richard Allen [Univ. of California, Berkeley, CA (United States)

    1979-03-01

    Electron correlation is a result of the interaction of two or more electrons confined in a region of space, and may conveniently be treated under the formalism of configuration interaction (CI). Photoionization provides a rather direct experimental method for studying configuration interaction. The types of CI involved in the photoionization process can be divided into three categories: initial state configuration interaction (ISCI), final ionic state configuration interaction (FISCI), and continuum state configuration interaction (CSCI). This thesis deals with experimental studies which reveal how the various types of CI may become manifested in photoionization. The experimental methods utilized in this work are photoelectron spectroscopy (PES), electron impact spectroscopy (EIS), and time-resolved fluorescence spectroscopy. The EIS was carried out following the discovery that the UV lamp on a Perkin-Elmer photoelectron spectrometer could be utilized as a source of low energy electrons. The time-resolved fluorescence work utilized both the tunability and the time structure of the radiation available at the Stanford Synchrotron Radiation Laboratory (SSRL). A commercial photoelectron spectrometer equipped with a conventional UV lamp (Hei, Nei) was employed for some of the PES studies, and a novel time-of-flight photoelectron spectrometer was developed for the PES work performed using synchrotron radiation. The PES of Ba, Sm, Eu, and Yb was studied using both Hei (22.22 eV) and Nei (16.85 eV) radiation. Satellite structure observed in these spectra using Nei (and for Yb, Hei also) radiation could be satisfactorily explained by ISCI alone. The Hei spectra of Sm, Eu, and, in particular, Ba showed dramatic changes in the satellite population which could only be explained by a new mechanism, autoionization, which is a special form of CSCI. The detailed nature of this mechanism was explored in Ba using synchrotron radiation. It was found that the autoionizing level decays

  17. CALCULATION-EXPERIMENTAL METHOD OF RESEARCH IN A METALLIC CONDUCTOR WITH THE PULSE CURRENT OF ELECTRONIC WAVEPACKAGES AND DE BROGLIE ELECTRONIC HALF-WAVES

    Directory of Open Access Journals (Sweden)

    M. I. Baranov

    2016-12-01

    Full Text Available Purpose. Development of calculation-experimental method for a discovery and study of electronic wavepackages (EWP and of de Broglie electronic half-waves in a metallic conductor with the pulse axial-flow current of high density. Methodology. Theoretical bases of the electrical engineering, bases of quantum physics, electrophysics bases of technique of high voltage and large pulsecurrents, and also bases of technique of measuring of permanent and variable electric value. Results. On the basis of generalization of results of research of features of the longitudinal wave periodic distributing of negatively charged transmitters of electric current of conductivity in the thin round continuous zincked steel wire offered and approved in the conditions of high-voltage laboratory method for a discovery and direct determination in him of geometrical parameters of «hot» and «cold» longitudinal areas quantized periodic longitudinal EWP and accordingly the mediated determination of values of the quantized lengths formative their de Broglie electronic half-waves. It is shown that results of close quantum mechanical calculations of EWP and quantized lengths λenz/2 of longitudinal de Broglie half-waves for the probed wire long l0 well comport with the results of the executed high temperature experiments on the powerful high-voltage generator of homopolar large pulse current of millisecond duration. Originality. First calculation-experimental a way the important for the theory of electricity fact of existence is set in a round metallic explorer with the impulsive axial-flow current of the quantized coherent de Broglie electronic half-waves, amplitudes of which at the quantum number of n=1,3,9 correspond the middles of «hot» longitudinal areas of EWP. Calculation quantum mechanical correlation of type of λenz/2=l0/n got experimental confirmation, in obedience to which on length of l0 conductor the integer of quantized electronic half-waves is always laid

  18. Isomer depletion as experimental evidence of nuclear excitation by electron capture

    Science.gov (United States)

    Chiara, C. J.; Carroll, J. J.; Carpenter, M. P.; Greene, J. P.; Hartley, D. J.; Janssens, R. V. F.; Lane, G. J.; Marsh, J. C.; Matters, D. A.; Polasik, M.; Rzadkiewicz, J.; Seweryniak, D.; Zhu, S.; Bottoni, S.; Hayes, A. B.; Karamian, S. A.

    2018-02-01

    The atomic nucleus and its electrons are often thought of as independent systems that are held together in the atom by their mutual attraction. Their interaction, however, leads to other important effects, such as providing an additional decay mode for excited nuclear states, whereby the nucleus releases energy by ejecting an atomic electron instead of by emitting a γ-ray. This ‘internal conversion’ has been known for about a hundred years and can be used to study nuclei and their interaction with their electrons. In the inverse process—nuclear excitation by electron capture (NEEC)—a free electron is captured into an atomic vacancy and can excite the nucleus to a higher-energy state, provided that the kinetic energy of the free electron plus the magnitude of its binding energy once captured matches the nuclear energy difference between the two states. NEEC was predicted in 1976 and has not hitherto been observed. Here we report evidence of NEEC in molybdenum-93 and determine the probability and cross-section for the process in a beam-based experimental scenario. Our results provide a standard for the assessment of theoretical models relevant to NEEC, which predict cross-sections that span many orders of magnitude. The greatest practical effect of the NEEC process may be on the survival of nuclei in stellar environments, in which it could excite isomers (that is, long-lived nuclear states) to shorter-lived states. Such excitations may reduce the abundance of the isotope after its production. This is an example of ‘isomer depletion’, which has been investigated previously through other reactions, but is used here to obtain evidence for NEEC.

  19. Experimental design of high energy electron gun by means of scaling rules

    International Nuclear Information System (INIS)

    Wojcicki, S.

    1996-01-01

    The possibility of the design of a new family of electron guns by means of scaling theory of electron-optical devices (EOD) is presented. According to the theory, EOD with a relatively big space charge, as in high energy Pierce type electron guns used in technological equipment, generally cannot be scaled, because of their nonlinear space charge nature. Therefore, the scaling rules are applied here only to the anode zone of the gun, where the electron beam perveance is small, and the cathode lens of gun with considerable space charge remains unchanged. The procedure for scaling a 25 kV and 150 mA gun with cylindrical electron beam into a high voltage 75 kV and 150 mA electron system is given. An experimental investigation proved the high technological quality of a high voltage gun constructed according to the above conception. (author)

  20. Experimental and theoretical electron-scattering cross-section data for dichloromethane

    Science.gov (United States)

    Krupa, K.; Lange, E.; Blanco, F.; Barbosa, A. S.; Pastega, D. F.; Sanchez, S. d'A.; Bettega, M. H. F.; García, G.; Limão-Vieira, P.; Ferreira da Silva, F.

    2018-04-01

    We report on a combination of experimental and theoretical investigations into the elastic differential cross sections (DCSs) and integral cross sections for electron interactions with dichloromethane, C H2C l2 , in the incident electron energy over the 7.0-30 eV range. Elastic electron-scattering cross-section calculations have been performed within the framework of the Schwinger multichannel method implemented with pseudopotentials (SMCPP), and the independent-atom model with screening-corrected additivity rule including interference-effects correction (IAM-SCAR+I). The present elastic DCSs have been found to agree reasonably well with the results of IAM-SCAR+I calculations above 20 eV and also with the SMC calculations below 30 eV. Although some discrepancies were found for 7 eV, the agreement between the two theoretical methodologies is remarkable as the electron-impact energy increases. Calculated elastic DCSs are also reported up to 10000 eV for scattering angles from 0° to 180° together with total cross section within the IAM-SCAR+I framework.

  1. EBIT (Electron Beam Ion Trap), N-Division Experimental Physics. Annual report, 1994

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, D. [ed.

    1995-10-01

    The experimental groups in the Electron Beam Ion Trap (EBIT) program continue to perform front-line research with trapped and extracted highly charged ions (HCI) in the areas of ion/surface interactions, atomic spectroscopy, electron-ion interaction and structure measurements, highly charged ion confinement, and EBIT development studies. The ion surface/interaction studies which were initiated five years ago have reached a stage where they an carry out routine investigations, as well as produce breakthrough results towards the development of novel nanotechnology. At EBIT and SuperEBIT studies of the x-ray emission from trapped ions continue to produce significant atomic structure data with high precision for few electron systems of high-Z ions. Furthermore, diagnostics development for magnetic and laser fusion, supporting research for the x-ray laser and weapons programs, and laboratory astrophysics experiments in support of NASA`s astrophysics program are a continuing effort. The two-electron contributions to the binding energy of helium like ions were measured for the first time. The results are significant because their precision is an order of magnitude better than those of competing measurements at accelerators, and the novel technique isolates the energy corrections that are the most interesting. The RETRAP project which was initiated three years ago has reached a stage where trapping, confining and electronic cooling of HCI ions up to Th{sup 80+} can be performed routinely. Measurements of the rates and cross sections for electron transfer from H{sub 2} performed to determine the lifetime of HCI up to Xe{sup q+} and Th{sup q+} (35 {le} q {le} 80) have been studied at mean energies estimated to be {approximately} 5 q eV. This combination of heavy ions with very high charges and very low energies is rare in nature, but may be encountered in planned fusion energy demonstration devices, in highly charged ion sources, or in certain astrophysical events.

  2. Experimental studies on the electronic structure of pyrite FeS2 films prepared by thermally sulfurizing iron films

    International Nuclear Information System (INIS)

    Zhang Hui; Wang Baoyi; Zhang Rengang; Zhang Zhe; Wei Long; Qian Haijie; Su Run; Kui Rexi

    2006-01-01

    Pyrite FeS 2 films have been prepared by thermally sulfurizing iron films deposited by magnetron sputtering. The electronic structures were studies by X-ray absorption near edge structure and X-ray photoemission spectrum. The results show that an S 3p valence band with relatively higher intensity compared to the calculation exists in 2-10 eV range and a high density below the Fermi level of Fe 3d states were detected. A second gap of 2.8 eV in the unoccupied density of states was found above the conduction band which was 2.4 eV by experimentally calculation. The difference between t 2g and e g which were formed in an octahedral crystal field was computed to be 2.1 eV. (authors)

  3. Experimental and numerical investigation of heat dissipation from an electronic component in a closed enclosure

    Directory of Open Access Journals (Sweden)

    George Bobin Saji

    2018-01-01

    Full Text Available Intensifying electronic component power dissipation levels, shortening product design cycle times, and greater than before requirement for more compact and reliable electronic systems with greater functionality, has heightened the need for thermal design tools that enable accurate solutions to be generated and quickly assessed. The present numerical study aims at developing a computational tool in OpenFOAM that can predict the heat dissipation rate and temperature profile of any electronic component in operation. A suitable computational domain with defined aspect ratio is chosen. For analyzing, “buoyant Boussinesq Simple Foam“ solver available with OpenFOAM is used. It was modified for adapting to the investigation with specified initial and boundary conditions. The experimental setup was made with the dimensions taken up for numerical study. Thermocouples were calibrated and placed in specified locations. For different heat input, the temperatures are noted down at steady state and compared with results from the numerical study.

  4. A combined experimental and theoretical study on vibrational and electronic properties of (5-methoxy-1H-indol-1-yl(5-methoxy-1H-indol-2-ylmethanone

    Directory of Open Access Journals (Sweden)

    Al-Wabli Reem I.

    2017-11-01

    Full Text Available (5-Methoxy-1H-indol-1-yl(5-methoxy-1H-indol-2-ylmethanone (MIMIM is a bis-indolic derivative that can be used as a precursor to a variety of melatonin receptor ligands. In this work, the energetic and spectroscopic profiles of MIMIM were studied by a combined DFT and experimental approach. The IR, Raman, UV-Vis, 1H NMR and 13C NMR spectra were calculated by PBEPBE and B3LYP methods, and compared with experimental ones. Results showed good agreement between theoretical and experimental values. Mulliken population and natural bond orbital analysis were also performed by time-dependent DFT approach to evaluate the electronic properties of the title molecule.

  5. Electron microscopic studies on experimental skin cancer after combination treatment with X-ray, hematoporphyrin oligomer and caffeine

    International Nuclear Information System (INIS)

    Ueda, Keiichi; Ishiguro, Kazumori; Takaishi, Kimiko; Hatcho, Masahiro; Nakagawa, Shigemori

    1992-01-01

    The effect of combination treatment with X-ray, hematoporphyrin oligomer (HpO) and caffeine (Caf) was compared electron microscopically with that of a single use of these treatments. In experimental skin cancer, ultrastructural changes of nuclei and cytoplasm of tumor cells after combination treatment with HpO, X-ray and Caf showed more remarkable changes than in single X-ray irradiation and in HpO and X-ray irradiation. It is concluded that the combination treatment of HpO, X-ray and Caf is useful to the skin cancers in clinical practice. (author)

  6. Electron microscopic studies on experimental skin cancer after combination treatment with X-ray, hematoporphyrin oligomer and caffeine

    Energy Technology Data Exchange (ETDEWEB)

    Ueda, Keiichi; Ishiguro, Kazumori; Takaishi, Kimiko; Hatcho, Masahiro; Nakagawa, Shigemori (Fukui Medical School, Matsuoka (Japan))

    1992-05-01

    The effect of combination treatment with X-ray, hematoporphyrin oligomer (HpO) and caffeine (Caf) was compared electron microscopically with that of a single use of these treatments. In experimental skin cancer, ultrastructural changes of nuclei and cytoplasm of tumor cells after combination treatment with HpO, X-ray and Caf showed more remarkable changes than in single X-ray irradiation and in HpO and X-ray irradiation. It is concluded that the combination treatment of HpO, X-ray and Caf is useful to the skin cancers in clinical practice. (author).

  7. Silicon passivation study under low energy electron irradiation conditions

    International Nuclear Information System (INIS)

    Cluzel, R.

    2010-01-01

    Backside illuminated thinned CMOS (Complementary Metal Oxide Semiconductor) imaging system is a technology developed to increase the signal to noise ratio and the sensibility of such sensors. This configuration is adapted to the electrons detection from the energy range of [1 - 12 keV]. The impinging electron creates by multiplication several hundreds of secondary electrons close to the surface. A P ++ highly-doped passivation layer of the rear face is required to reduce the secondary electron surface recombination rate. Thanks to the potential barrier induced by the P ++ layer, the passivation layer increases the collected charges number and so the sensor collection gain. The goal of this study is to develop some experimental methods in order to determine the effect of six different passivation processes on the collection gain. Beforehand, the energy profile deposited by an incident electron is studied with the combination of Monte-Carlo simulations and some analytical calculations. The final collection gain model shows that the mirror effect from the passivation layer is a key factor at high energies whereas the passivation layer has to be as thin as possible at low energies. A first experimental setup which consists in irradiating P ++ /N large diodes allows to study the passivation process impacts on the surface recombinations. Thanks to a second setup based on a single event upset directly on thinned CMOS sensor, passivation techniques are discriminated in term of mirror effect and the implied spreading charges. The doping atoms activation laser annealing is turn out to be a multiplication gain inhomogeneity source impacting directly the matrix uniformity. (author)

  8. Theoretical and experimental study of an energy-reinforced braking radiation photon beam

    International Nuclear Information System (INIS)

    Bertin, Pierre-Yves

    1966-01-01

    This research thesis reports the theoretical study of a photon beam raised towards high energies, its experimental implementation, the definition of a gamma spectrometry method which aimed at checking various hypotheses used in the beam theoretical study. After a presentation of the theory of phenomena of electron braking radiation, of materialisation of photons into positon-negaton pair, and of issues related to multiple Coulomb diffusion, the author reports the study of the different solutions which allow a photon beam to be obtained. A braking radiation of mono-kinetic electron has been used. This braking radiation is reinforced by absorption of low energy protons in a column of lithium hydride. The author describes how the beam is built up, and the experimental approach. He describes how raw data are processed to get rid of the influence of the multiple Coulomb diffusion and of the braking radiation. Experimental results are compared with those obtained by convolution of photon spectra and differential cross section

  9. Electronic properties of Fe charge transfer complexes – A combined experimental and theoretical approach

    International Nuclear Information System (INIS)

    Ferreira, Hendrik; Eschwege, Karel G. von; Conradie, Jeanet

    2016-01-01

    Highlights: • Experimental and computational study of Fe II -phen, -bpy & -tpy compleesx. • Close correlations between experimental redox and spectral, and computational data. • Computational methods fast-track DSSC research. - Abstract: Dye-sensitized solar cell technology holds huge potential in renewable electricity generation of the future. Due to demand urgency, ways need to be explored to reduce research time and cost. Against this background, quantum computational chemistry is illustrated to be a reliable tool at the onset of studies in this field, simulating charge transfer, spectral (solar energy absorbed) and electrochemical (ease by which electrons may be liberated) tuning of related photo-responsive dyes. Comparative experimental and theoretical DFT studies were done under similar conditions, involving an extended series of electrochemically altered phenanthrolines, bipyridyl and terpyridyl complexes of Fe II . Fe II/III oxidation waves vary from 0.363 V for tris(3,6-dimethoxybipyridyl)Fe II to 0.894 V (versus Fc/Fc + ) for the 5-nitrophenanthroline complex. Theoretical DFT computed ionization potentials in the bipyridyl sub-series achieved an almost 100% linear correlation with experimental electrochemical oxidation potentials, while the phenanthroline sub-series gave R 2 = 0.95. Apart from the terpyridyl complex which accorded an almost perfect match, in general, TDDFT oscillators were computed at slightly lower energies than what was observed experimentally, while molecular HOMO and LUMO renderings reveal desired complexes with directional charge transfer propensities.

  10. Is the thermal-spike model consistent with experimentally determined electron temperature?

    International Nuclear Information System (INIS)

    Ajryan, Eh.A.; Fedorov, A.V.; Kostenko, B.F.

    2000-01-01

    Carbon K-Auger electron spectra from amorphous carbon foils induced by fast heavy ions are theoretically investigated. The high-energy tail of the Auger structure showing a clear projectile charge dependence is analyzed within the thermal-spike model framework as well as in the frame of another model taking into account some kinetic features of the process. A poor comparison results between theoretically and experimentally determined temperatures are suggested to be due to an improper account of double electron excitations or due to shake-up processes which leave the system in a more energetic initial state than a statically screened core hole

  11. Study on tamper-indicating technology in electronic seals system

    International Nuclear Information System (INIS)

    Xu Xiong; Han Feng; Zuo Guangxia; Zhao Xin; Zhang Quanhu; Di Yuming

    2009-01-01

    To strengthen our national arms control verification technical storage and deepen electronic seals' research, this paper mainly introduces seals' characteristics, functions and work principle, studies on tamper-indicating technology which is a key technology in electronic seals, designs some hardware circuit such as optical transceiver, temperature detection circuit, move detection circuit, re-prized circuit and so on, also designs a software program which is used for recording the destroying or tampering events' information. Experimental results show that electronic seals system can record the destroying or tampering events' information accurately and quickly, and give corresponding tamper-indication. (authors)

  12. Electronic processes in organic electronics bridging nanostructure, electronic states and device properties

    CERN Document Server

    Kudo, Kazuhiro; Nakayama, Takashi; Ueno, Nobuo

    2015-01-01

    The book covers a variety of studies of organic semiconductors, from fundamental electronic states to device applications, including theoretical studies. Furthermore, innovative experimental techniques, e.g., ultrahigh sensitivity photoelectron spectroscopy, photoelectron yield spectroscopy, spin-resolved scanning tunneling microscopy (STM), and a material processing method with optical-vortex and polarization-vortex lasers, are introduced. As this book is intended to serve as a textbook for a graduate level course or as reference material for researchers in organic electronics and nanoscience from electronic states, fundamental science that is necessary to understand the research is described. It does not duplicate the books already written on organic electronics, but focuses mainly on electronic properties that arise from the nature of organic semiconductors (molecular solids). The new experimental methods introduced in this book are applicable to various materials (e.g., metals, inorganic and organic mater...

  13. Diffuse Scattering of the Conduction Electrons of a Metallic Substrate by an Adsorbate: an Experimental Study Using Synchrotron Infrared Radiation

    International Nuclear Information System (INIS)

    Hein, M.; Otto, A.; Dumas, P.; Williams, G. P.

    1999-01-01

    Due to its intrinsic high brightness, high stability, and proportionality to the stored electron beam current, synchrotrons IR spectroscopy has revealed itself as an unique tool to experimentally test a physical phenomenon occurring at metallic interfaces, the theory for which was motivated by previous observations. Any adsorbate induces inelastic scattering of the conduction electrons, which causes a broadband IR reflectance change, and was predicted to induce a concomitant DC resistivity change. By choosing a well ordered single crystal thin film of Cu(111), we have checked that the DC resistivity change, and the asymptotic limit of the IR reflectance change are linearly dependent, but independent of the nature of the adsorbate. Coadsorption experiments which have been used to modify the induced density of states at the Fermi level, have further demonstrated that the friction coefficient, which is responsible for the elastic scattering phenomenon, is chemically specific. This article describes the use of synchrotron radiation as an absolute source and its application to the study of dynamics of adsorbates on surfaces

  14. Experimental procedures to mitigate electron beam induced artifacts during in situ fluid imaging of nanomaterials

    International Nuclear Information System (INIS)

    Woehl, Taylor J.; Jungjohann, Katherine L.; Evans, James E.; Arslan, Ilke; Ristenpart, William D.; Browning, Nigel D.

    2013-01-01

    Scanning transmission electron microscopy of various fluid and hydrated nanomaterial samples has revealed multiple imaging artifacts and electron beam–fluid interactions. These phenomena include growth of crystals on the fluid stage windows, repulsion of particles from the irradiated area, bubble formation, and the loss of atomic information during prolonged imaging of individual nanoparticles. Here we provide a comprehensive review of these fluid stage artifacts, and we present new experimental evidence that sheds light on their origins in terms of experimental apparatus issues and indirect electron beam sample interactions with the fluid layer. A key finding is that many artifacts are a result of indirect electron beam interactions, such as production of reactive radicals in the water by radiolysis, and the associated crystal growth. The results presented here will provide a methodology for minimizing fluid stage imaging artifacts and acquiring quantitative in situ observations of nanomaterial behavior in a liquid environment

  15. Experimental procedures to mitigate electron beam induced artifacts during in situ fluid imaging of nanomaterials

    Energy Technology Data Exchange (ETDEWEB)

    Woehl, Taylor J., E-mail: tjwoehl@ucdavis.edu [Department of Chemical Engineering and Materials Science, University of California, Davis, Davis, CA 95616 (United States); Jungjohann, Katherine L. [Department of Chemical Engineering and Materials Science, University of California, Davis, Davis, CA 95616 (United States); Evans, James E. [Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616 (United States); Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Arslan, Ilke [Department of Chemical Engineering and Materials Science, University of California, Davis, Davis, CA 95616 (United States); Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Ristenpart, William D. [Department of Chemical Engineering and Materials Science, University of California, Davis, Davis, CA 95616 (United States); Department of Food Science and Technology, University of California, Davis, Davis, CA 95616 (United States); Browning, Nigel D. [Department of Chemical Engineering and Materials Science, University of California, Davis, Davis, CA 95616 (United States); Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616 (United States); Pacific Northwest National Laboratory, Richland, WA 99352 (United States)

    2013-04-15

    Scanning transmission electron microscopy of various fluid and hydrated nanomaterial samples has revealed multiple imaging artifacts and electron beam–fluid interactions. These phenomena include growth of crystals on the fluid stage windows, repulsion of particles from the irradiated area, bubble formation, and the loss of atomic information during prolonged imaging of individual nanoparticles. Here we provide a comprehensive review of these fluid stage artifacts, and we present new experimental evidence that sheds light on their origins in terms of experimental apparatus issues and indirect electron beam sample interactions with the fluid layer. A key finding is that many artifacts are a result of indirect electron beam interactions, such as production of reactive radicals in the water by radiolysis, and the associated crystal growth. The results presented here will provide a methodology for minimizing fluid stage imaging artifacts and acquiring quantitative in situ observations of nanomaterial behavior in a liquid environment.

  16. Experimental studies to the dose distribution from pendulum irradiation of the middle part of the ESOPHAGUS with electrons and X-rays from a 42 MeV betatron

    International Nuclear Information System (INIS)

    Bark, R.

    1973-01-01

    Experimental studies of the dose distributions in the area of the middle esophagus resulting from pendulum irradiation with electrons and X-rays are reported. In these studies the energy and the arrangement of the pendulum angle were to be varied so as to generate the maximum possible dose decrease from the focal area to the healthy tissue. The electron energies used were 30 and 42 MeV, the energies of ultrahard X-rays were 42 MV. All studies carried out with the different pendulum angles indicated that electron therapy is in no way capable of meeting the existing requirements in terms of low exposures of the lung, bone marrow and skin. However, the use of ultrahard X-rays offers much better dose distribution conditions. These can be achieved only by bi-segmental pendulum irradiation under a bilateral angle of 70 0 (30 0 dorsal, 40 0 ventral). (orig./RF) [de

  17. Factors associated with experimentation of electronic cigarettes among Parisian teenagers in 2013.

    Science.gov (United States)

    Dautzenberg, Bertrand; Berlin, Ivan; Tanguy, Marie-Laure; Rieu, Nicole; Birkui, Pierre

    2015-01-01

    Electronic cigarettes (e-cig.) became widely used among adults. Data are insufficient about e-cig. experimentation among youth. To assess prevalence of e-cig. experimentation and associated factors among the 12 to 19 years old we analyse a cross sectional school based survey in the city of Paris, France in 2013 on a randomly selected sample of 2 % of schoolchildren (n = 3 279). Self-report questionnaire include demographic, individual and family smoking characteristics and questions about e-cig: "Have you ever used an e-cigarette?"- "Did you use e-cigarette in the last 30 days?"-"Did you try e-cigarette as a first tobacco product?". In 2013, 17.9 % (564) schoolchildren reported having experienced the e-cig (boys: 19.0 %, girls: 16.8 %) compared to 9.8 % in 2012. Experimentation rate increases from 5 % among the 12 to 30 % among the 16-year-old. E-cig. experimentation was significantly associated with 11 parameters including : age >15 years (OR: 0.66 (IC95 % = 0.46-0.94)); smoking 10 cigarettes or more (OR = 5.67 (IC95 % = 3.11-10.34)), best friends and siblings smoker (OR = 1.54 (IC95 % = 1.11-2.14)) and (OR = 1.88 (IC95 % = 1.41-2.52)); experimentation of shisha (OR = 2.60 (IC95 % = 1.75-3.86)), cannabis use (OR = 1.90 (IC95 % = 1.32-2.72)); having two parents who forbid smoking (OR = 2.32 (IC95 % = 1.63-3.30)). Only 5.6 % of the study population (and 32.5 % of e-cig. experimenters (183/564)) have used it in the last 30 days; 1.7 % of the study population and 10.0 % of e-cig. experimenters were non-smokers (56/564). Rate of e-cig. experimentation among schoolchildren increased by 8.1 % in 1 year. Non-smoking youth may use e-cig. Prospective studies are urgently needed to assess the evolution of e-cig. use both among smoking and non-smoking youth.

  18. Study of SPM tolerances of electronically compensated DML based systems.

    Science.gov (United States)

    Papagiannakis, I; Klonidis, D; Birbas, Alexios N; Kikidis, J; Tomkos, I

    2009-05-25

    This paper experimentally investigates the effectiveness of electronic dispersion compensation (EDC) for signals limited by self phase modulation (SPM) and various dispersion levels. The sources considered are low-cost conventional directly modulated lasers (DMLs), fabricated for operation at 2.5 Gb/s but modulated at 10 Gb/s. Performance improvement is achieved by means of electronic feed-forward and decision-feedback equalization (FFE/DFE) at the receiver end. Experimental studies consider both transient and adiabatic chirp dominated DMLs sources. The improvement is evaluated in terms of required optical signal-to-noise ratio (ROSNR) for bit-error-rate (BER) values of 10(-3) versus launch power over uncompensated links of standard single mode fiber (SSMF).

  19. An experimental and ab initio study of the electronic spectrum of the jet-cooled F{sub 2}BO free radical

    Energy Technology Data Exchange (ETDEWEB)

    Grimminger, Robert; Clouthier, Dennis J., E-mail: dclaser@uky.edu [Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506-0055 (United States); Sheridan, Phillip M. [Department of Chemistry and Biochemistry, Canisius College, Buffalo, New York 14208 (United States)

    2014-04-28

    We have studied the B{sup ~} {sup 2}A{sub 1}–X{sup ~} {sup 2}B{sub 2} laser-induced fluorescence (LIF) spectrum of the jet-cooled F{sub 2}BO radical for the first time. The transition consists of a strong 0{sub 0}{sup 0} band at 446.5 nm and eight weak sequence bands to shorter wavelengths. Single vibronic level emission spectra obtained by laser excitation of individual levels of the B{sup ~} state exhibit two electronic transitions: a very weak, sparse B{sup ~}–X{sup ~} band system in the 450–500 nm region and a stronger, more extensive set of B{sup ~} {sup 2}A{sub 1}–A{sup ~} {sup 2}B{sub 1} bands in the 580–650 nm region. We have also performed a series of high level ab initio calculations to predict the electronic energies, molecular structures, vibrational frequencies, and rotational and spin-rotation constants in the X{sup ~} {sup 2}B{sub 2}, A{sup ~2}B{sub 1} and B{sup ~} {sup 2}A{sub 1} electronic states as an aid to the analysis of the experimental data. The theoretical results have been used as input for simulations of the rotationally resolved B{sup ~} {sup 2}A{sub 1}–X{sup ~} {sup 2}B{sub 2} 0{sub 0}{sup 0} LIF band and Franck-Condon profiles of the LIF and single vibronic level emission spectra. The agreement between the simulations obtained with purely ab initio parameters and the experimental spectra validates the geometries calculated for the ground and excited states and the conclusion that the radical has C{sub 2v} symmetry in the X{sup ~}, A{sup ~}, and B{sup ~} states. The spectra provide considerable new information about the vibrational energy levels of the X{sup ~} and A{sup ~} states, but very little for the B{sup ~} state, due to the very restrictive Franck-Condon factors in the LIF spectra.

  20. Study of hot electrons in a ECR ion source

    International Nuclear Information System (INIS)

    Barue, C.

    1992-12-01

    The perfecting of diagnosis connected with hot electrons of plasma, and then the behaviour of measured parameters of plasma according to parameters of source working are the purpose of this thesis. The experimental results obtained give new information on hot electrons of an ECR ion source. This thesis is divided in 4 parts: the first part presents an ECR source and the experimental configuration (ECRIS physics, minimafios GHz, diagnosis used); the second part, the diagnosis (computer code of cyclotron emission and calibration); the third part gives experimental results in continuous regime (emission cyclotron diagnosis, bremsstrahlung); the fourth part, experimental results in pulsed regime (emission cyclotron diagnosis, diamagnetism) calibration)

  1. Experimental and theoretical study on chemically semi-amplified resist AR-P 6200

    Science.gov (United States)

    Kostic, I.; Vutova, K.; Andok, R.; Barak, V.; Bencurova, A.; Ritomsky, R.; Tanaka, T.

    2018-03-01

    Experimental and simulation results are presented and discussed on electron-beam lithography (EBL) nano-structuring using the positive chemically semi-amplified electron-beam resist AR-P 6200 (CSAR 62), which provides high sensitivity and allows achievement of high resolutions (sub-100 nm). The influence of the e-beam lithography process parameters, namely, exposure dose, development process conditions, and proximity effects on the obtained developed images was studied for the case of 40-keV electron energy.

  2. Experimental Study of Electron and Phonon Dynamics in Nanoscale Materials by Ultrafast Laser Time-Domain Spectroscopy

    Science.gov (United States)

    Shen, Xiaohan

    With the rapid advances in the development of nanotechnology, nowadays, the sizes of elementary unit, i.e. transistor, of micro- and nanoelectronic devices are well deep into nanoscale. For the pursuit of cheaper and faster nanoscale electronic devices, the size of transistors keeps scaling down. As the miniaturization of the nanoelectronic devices, the electrical resistivity increases dramatically, resulting rapid growth in the heat generation. The heat generation and limited thermal dissipation in nanoscale materials have become a critical problem in the development of the next generation nanoelectronic devices. Copper (Cu) is widely used conducting material in nanoelectronic devices, and the electron-phonon scattering is the dominant contributor to the resistivity in Cu nanowires at room temperature. Meanwhile, phonons are the main carriers of heat in insulators, intrinsic and lightly doped semiconductors. The thermal transport is an ensemble of phonon transport, which strongly depends on the phonon frequency. In addition, the phonon transport in nanoscale materials can behave fundamentally different than in bulk materials, because of the spatial confinement. However, the size effect on electron-phonon scattering and frequency dependent phonon transport in nanoscale materials remain largely unexplored, due to the lack of suitable experimental techniques. This thesis is mainly focusing on the study of carrier dynamics and acoustic phonon transport in nanoscale materials. The weak photothermal interaction in Cu makes thermoreflectance measurement difficult, we rather measured the reflectivity change of Cu induced by absorption variation. We have developed a method to separately measure the processes of electron-electron scattering and electron-phonon scattering in epitaxial Cu films by monitoring the transient reflectivity signal using the resonant probe with particular wavelengths. The enhancement on electron-phonon scattering in epitaxial Cu films with thickness

  3. Origin of electronic properties of PbGa2Se4 crystal: Experimental and theoretical investigations

    International Nuclear Information System (INIS)

    Babuka, T.; Kityk, I.V.; Parasyuk, O.V.; Myronchuk, G.; Khyzhun, O.Y.; Fedorchuk, A.O.; Makowska-Janusik, M.

    2015-01-01

    Graphical abstract: In the presented work the structural and electronic properties of the PbGa 2 Se 4 single crystal were investigated experimentally as well as theoretically. The XPS spectra, Urbach’s rule and steepness parameters of PbGa 2 Se 4 single crystal have been investigated for the first time. The quantum chemical calculations were also never performed before for the studied structure. The theoretically obtained data help to explain the properties of material. - Highlights: • Urbach’s rule and steepness parameters for PbGa 2 Se 4 crystals explored for the first time. • Non-reactivity of the PbGa 2 Se 4 surface was established by XPS. • DFT approach shows its efficiency to describe electronic properties of PbGa 2 Se 4 . • Electronic parameters are affected by existence of electron–phonon interaction. - Abstract: The PbGa 2 Se 4 crystal is a promising material for optoelectronic applications. It is caused by coexistence of the large polarized Pb cations and a huge contribution of anharmonic phonon subsystem caused by chalcogenide anions. In the present work the electronic and optical properties of the mentioned material were studied theoretically as well as experimentally by optical and X-ray photoelectron spectroscopy methods. The DFT approach has been used for the quantum chemical electronic properties calculations. Urbach rule and steepness parameters of the PbGa 2 Se 4 crystal have been evaluated for the first time. These parameters and Urbach energies increase with increasing temperature of the samples that is typical for the semiconducting materials. The XPS measurements of the investigated crystal reveal that all the spectral features are originated from core-level states of the constituent elements. Simultaneously these results also confirm non-reactivity of the PbGa 2 Se 4 surface. However, the titled single crystal possesses a number of intrinsic structural defects and vacancies thereby affecting its electronic properties. The

  4. Experimental Observation of a Current-Driven Instability in a Neutral Electron-Positron Beam

    Science.gov (United States)

    Warwick, J.; Dzelzainis, T.; Dieckmann, M. E.; Schumaker, W.; Doria, D.; Romagnani, L.; Poder, K.; Cole, J. M.; Alejo, A.; Yeung, M.; Krushelnick, K.; Mangles, S. P. D.; Najmudin, Z.; Reville, B.; Samarin, G. M.; Symes, D. D.; Thomas, A. G. R.; Borghesi, M.; Sarri, G.

    2017-11-01

    We report on the first experimental observation of a current-driven instability developing in a quasineutral matter-antimatter beam. Strong magnetic fields (≥1 T ) are measured, via means of a proton radiography technique, after the propagation of a neutral electron-positron beam through a background electron-ion plasma. The experimentally determined equipartition parameter of ɛB≈10-3 is typical of values inferred from models of astrophysical gamma-ray bursts, in which the relativistic flows are also expected to be pair dominated. The data, supported by particle-in-cell simulations and simple analytical estimates, indicate that these magnetic fields persist in the background plasma for thousands of inverse plasma frequencies. The existence of such long-lived magnetic fields can be related to analog astrophysical systems, such as those prevalent in lepton-dominated jets.

  5. Experimental study of the negative glow and cathode sheath of an electron beam discharge

    International Nuclear Information System (INIS)

    Zeller, Philippe

    1988-01-01

    This research thesis reports the study of a middle-pressure (0.1-5 Torr) discharge in which a negative-glow-type plasma is created by a continuous electron beam (1 to 10 keV, 1 to 30 mA/cm 2 ). Such a discharge is characterised by a highly abnormal cathodic drop with a beam generation displaying an electric efficiency close to 1. In a first part, the author presents the main operation characteristics, discharge regimes and emission spectrum, and discusses bibliographical data related to cathode emission processes and to the distribution function of plasma electron velocities. The author then describes an original method of measurement of plasma conductivity. In the next part, he reports the study of the cathode region in which the electron beam generation occurs. The electric field has been measured in this region by using spatially resolved laser opto-galvanic spectroscopy. Results highlight an essentially linear spatial decay of the field. Besides, and based on these results, the author indicates scale laws leading to simple relationships between discharge parameters [fr

  6. Effects of using mobile device-based academic electronic medical records for clinical practicum by undergraduate nursing students: A quasi-experimental study.

    Science.gov (United States)

    Choi, Mona; Lee, HyeongSuk; Park, Joon Ho

    2018-02-01

    The academic electronic medical record (AEMR) system is applied with the expectation that nursing students will be able to attain competence in healthcare decision-making and nursing informatics competencies. However, there is insufficient evidence regarding the advantage of applying mobile devices to clinical practicum. This study aimed to examine the effect of an experiment that introduced a mobile AEMR application for undergraduate nursing students in their practicum. A quasi-experimental design was used. The subjects were 75 third-year nursing students enrolled in clinical practicum and were divided into an experimental (practicum with AEMR) and a control (conventional practicum) group. Nursing informatics competencies, critical thinking disposition, and satisfaction with clinical practicum were measured before and after the clinical practicum for each group. The usability of the AEMR application was also examined for the experimental group after the experiment. After the experiment, the experimental group showed a significant increase in the informatics knowledge domain of nursing informatics competencies in the post-test. The difference in critical thinking between the experimental and control groups was not statistically significant. Regarding satisfaction with the clinical practicum, the experimental group exhibited a significantly higher level of satisfaction in "preparation of a diagnostic test or laboratory test and understanding of the results" and "nursing intervention and documentation" than the control group. Students who participated in the practicum using the AEMR application considered it useful. The AEMR application was an effective educational method for practicing the immediate documentation of students' observations and interventions and was available at the patients' bedsides. To improve critical thinking, it is necessary to apply a variety of approaches when solving clinical problems. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. The electron

    International Nuclear Information System (INIS)

    Hestenes, David; Weingartshofer, Antonio

    1991-01-01

    The stupendous successes of the Dirac equation and quantum electro-dynamics have established the electron as the best understood of the fundamental constituents of matter. Nevertheless, physicists agree that the electron still has secrets to reveal. Moreover, powerful new theoretical and experimental tools for probing those secrets have been sharpened during the last decade. This workshop was organized to bring theorists and experimentalists together to discuss their common goal of knowing the electron. Present state and future prospects for progress toward that goal are here described. The theoretical papers encompass a wide range of views on the electron. Several argue that the 'Zitter-bewegung' is more than a mathematical peculiarity of the Dirac equation, that it may well be a real physical phenomenon and worthy of serious study, theoretically and experimentally. Besides generating the electron spin and magnetic moment, the 'Zitterbewegung' may be a vital clue to electron structure and self-interaction. Some of the papers employ a radical new formulation of the Dirac theory which reveals a hidden geo-metric structure in the theory that supports a 'Zitterbewegung' inter-pretation. For the last half century the properties of electrons have been probed primarily by scattering experiments at ever higher energies. Recently, however, two powerful new experimental techniques have emerged capable of giving alternative experimental views of the electron. First, techniques for confining single electrons for long term study have led to the most accurate measurements of the electron magnetic moment. Second, the interaction of high intensity laser fields with atoms and electrons have revealed striking new phenomena such as multiphoton ionization. refs.; figs.; tabs

  8. Polarization Studies for the eRHIC Electron Storage Ring

    Energy Technology Data Exchange (ETDEWEB)

    Gianfelice-Wendt, Eliana [Fermilab; Tepikian, S. [Brookhaven

    2018-04-01

    A hadron/lepton collider with polarized beams has been under consideration by the scientific community since some years, in the U.S. and Europe. Among the various proposals, those by JLAB and BNL with polarized electron and proton beams are currently under closer study in the U.S. Experimenters call for the simultaneous storage of electron bunches with both spin helicity. In the BNL based Ring-Ring design, electrons are stored at top energy in a ring to be accommodated in the existing RHIC tunnel. The transversely polarized electron beam is injected into the storage ring at variable energies, between 5 and 18 GeV. Polarization is brought into the longitudinal direction at the IP by a couple of spin rotators. In this paper results of first studies of the attainable beam polarization level and lifetime in the storage ring at 18 GeV are presented.

  9. Approaching an experimental electron density model of the biologically active trans -epoxysuccinyl amide group-Substituent effects vs. crystal packing

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Ming W.; Stewart, Scott G.; Sobolev, Alexandre N.; Dittrich, Birger; Schirmeister, Tanja; Luger, Peter; Hesse, Malte; Chen, Yu-Sheng; Spackman, Peter R.; Spackman, Mark A.; Grabowsky, Simon (Heinrich-Heine); (Freie); (UC); (Bremen); (JG-UM); (UWA)

    2017-01-24

    The trans-epoxysuccinyl amide group as a biologically active moiety in cysteine protease inhibitors such as loxistatin acid E64c has been used as a benchmark system for theoretical studies of environmental effects on the electron density of small active ingredients in relation to their biological activity. Here, the synthesis and the electronic properties of the smallest possible active site model compound are reported to close the gap between the unknown experimental electron density of trans-epoxysuccinyl amides and the well-known function of related drugs. Intramolecular substituent effects are separated from intermolecular crystal packing effects on the electron density, which allows us to predict the conditions under which an experimental electron density investigation on trans-epoxysuccinyl amides will be possible. In this context, the special importance of the carboxylic acid function in the model compound for both crystal packing and biological activity is revealed through the novel tool of model energy analysis.

  10. Study of fast electrons from hard-X radiation; Etude des electrons rapides a partir du rayonnement X-dur

    Energy Technology Data Exchange (ETDEWEB)

    Arslanbekov, R.

    1995-12-19

    The goal of this thesis is the study of fast electron dynamics by means of the hard X-ray diagnosis installed in TORE SUPRA and numerical simulations. Fast electrons are generated in the plasma in the presence of the injected lower hybrid (LH) waves. Two aspects are studied in detail: the lower hybrid wave propagation and absorption in a periodically perturbed media and 2-D Fokker-Planck modelling of the fast electron dynamics in the presence of the LH power. Ripple effects on lower hybrid wave propagation and absorption are investigated using the ray tracing technique. A cylindrical equilibrium is first studied and a strong modification of the ray dynamics is predicted. Calculations are carried out in a real toroidal geometry corresponding to TORE SUPRA. It is shown that the lack of toroidal axisymmetry of the magnetic field may result in a modification of the ray evolution even if the global ray evolution is governed by the larger poloidal inhomogeneity. Simulation of LH experiments are performed for TORE SUPRA tokamak which has a large magnetic ripple (7% at the plasma edge). By considering ripple perturbation in LH current drive simulations, a better agreement is found with experimental results, in particular with the hard-X spectra and the current density profiles. In the second part of the thesis, a 2-D modeling of the fast electron dynamics in the velocity phase space is considered, based on the 2-D relativistic electron Fokker-Planck equation. Electron distribution functions obtained are used to calculate non-thermal Bremsstrahlung emission for different TORE SUPRA shots in a wide range of experimental conditions. (J.S.). 168 refs., 93 figs., 1 tab., 3 appendix.

  11. Calculated and experimental low-loss electron energy loss spectra of dislocations in diamond and GaN

    CERN Document Server

    Jones, R; Gutiérrez-Sosa, A; Bangert, U; Heggie, M I; Blumenau, A T; Frauenheim, T; Briddon, P R

    2002-01-01

    First-principles calculations of electron energy loss (EEL) spectra for bulk GaN and diamond are compared with experimental spectra acquired with a scanning tunnelling electron microscope offering ultra-high-energy resolution in low-loss energy spectroscopy. The theoretical bulk low-loss EEL spectra, in the E sub g to 10 eV range, are in good agreement with experimental data. Spatially resolved spectra from dislocated regions in both materials are distinct from bulk spectra. The main effects are, however, confined to energy losses lying above the band edge. The calculated spectra for low-energy dislocations in diamond are consistent with the experimental observations, but difficulties remain in understanding the spectra of threading dislocations in GaN.

  12. Study and realization of an electron linear accelerator. Dynamics of accelerated electrons

    International Nuclear Information System (INIS)

    Bernard, J.

    1966-12-01

    The theoretical characteristics of the electron linear accelerator are: 30 MeV for the energy W S and 250 mA for the peak current I c . The main utilization is the intense production of fast neutrons by the reactions (γ,n) and (γ,f) induced in a target of natural uranium by the accelerated electrons. In the first part of the thesis, relative to the study and the realization of the accelerator, a new equation of dispersion is established analytically when the guide is loaded with round-edged irises. The relation is compared with the equation established by CHU and Hansen, WALKINSHAW, KVASIL in the case of a guide loaded with flat-edged irises. The experimental and theoretical curves of dispersion are compared. The accuracy of every relation of dispersion is estimated. The second part of the thesis is relative to the theoretical study of the electrons dynamics in the guide; it allows the derivation of the parameters of the beam: dispersion of phase, energy, dispersion of energy and the relation W S = f (I c ). The results relative to the first experiments are given and compared with the theoretical expectations. (author) [fr

  13. Broad photoelectron spectrum and lowered electron affinity due to hydrogen in ZnOH: A joint experimental and theoretical study

    Science.gov (United States)

    Iordanov, I.; Gunaratne, K. D. D.; Harmon, C. L.; Sofo, J. O.; Castleman, A. W.

    2012-06-01

    We report a combined experimental and theoretical photoelectron spectroscopy study of ZnOH-. We find that the electron binding energy spectrum of ZnOH- reveals a broad and featureless peak between 1.4 and 2.4 eV in energy. The vertical detachment energy (VDE) of ZnOH- is determined to be 1.78 eV, which is lower than the 2.08 eV VDE of ZnO-. Our theoretical calculations match the VDE of ZnOH- accurately, but we find that the broadness of the peak cannot be explained by rotational or vibrational state excitation. The broadness of this peak is in strong contrast to the narrow and easily understood first peak of the ZnO spectrum, which features a well-resolved vibrational progression that can be readily explained by calculating the Franck-Condon transition factors. This study provides spectroscopic evidence of the effect of hydrogen on diatomic ZnO.

  14. Ultraviolet and soft X-ray free-electron lasers introduction to physical principles, experimental results, technological challenges

    CERN Document Server

    Schmüser, Peter; Rossbach, Jörg; Fujimori, A; Kühn, J; Müller, T; Steiner, F; Trümper, J; Varma, C; Wölfle, P

    2008-01-01

    In the introduction accelerator-based light sources are considered and a comparison is made between free-electron lasers and conventional quantum lasers. The motion and radiation of relativistic electrons in undulator magnets is discussed. The principle of a low-gain free-electron laser is explained and the pendulum equations are introduced that characterize the electron dynamics in the field of a light wave. The differential equations of the high-gain FEL are derived from the Maxwell equations of electrodynamics. Analytical and numerical solutions of the FEL equations are presented and important FEL parameters are defined, such as gain length, FEL bandwidth and saturation power. A detailed numerical study of the all-important microbunching process is presented. The mechanism of Self Amplified Spontaneous Emission is described theoretically and illustrated with numerous experimental results. Three-dimensional effects such as betatron oscillations and optical diffraction are addressed and their impact on the F...

  15. Molecular dynamics simulations with electronic stopping can reproduce experimental sputtering yields of metals impacted by large cluster ions

    Science.gov (United States)

    Tian, Jiting; Zhou, Wei; Feng, Qijie; Zheng, Jian

    2018-03-01

    An unsolved problem in research of sputtering from metals induced by energetic large cluster ions is that molecular dynamics (MD) simulations often produce sputtering yields much higher than experimental results. Different from the previous simulations considering only elastic atomic interactions (nuclear stopping), here we incorporate inelastic electrons-atoms interactions (electronic stopping, ES) into MD simulations using a friction model. In this way we have simulated continuous 45° impacts of 10-20 keV C60 on a Ag(111) surface, and found that the calculated sputtering yields can be very close to the experimental results when the model parameter is appropriately assigned. Conversely, when we ignore the effect of ES, the yields are much higher, just like the previous studies. We further expand our research to the sputtering of Au induced by continuous keV C60 or Ar100 bombardments, and obtain quite similar results. Our study indicates that the gap between the experimental and the simulated sputtering yields is probably induced by the ignorance of ES in the simulations, and that a careful treatment of this issue is important for simulations of cluster-ion-induced sputtering, especially for those aiming to compare with experiments.

  16. Experimental Observation of a Current-Driven Instability in a Neutral Electron-Positron Beam.

    Science.gov (United States)

    Warwick, J; Dzelzainis, T; Dieckmann, M E; Schumaker, W; Doria, D; Romagnani, L; Poder, K; Cole, J M; Alejo, A; Yeung, M; Krushelnick, K; Mangles, S P D; Najmudin, Z; Reville, B; Samarin, G M; Symes, D D; Thomas, A G R; Borghesi, M; Sarri, G

    2017-11-03

    We report on the first experimental observation of a current-driven instability developing in a quasineutral matter-antimatter beam. Strong magnetic fields (≥1  T) are measured, via means of a proton radiography technique, after the propagation of a neutral electron-positron beam through a background electron-ion plasma. The experimentally determined equipartition parameter of ε_{B}≈10^{-3} is typical of values inferred from models of astrophysical gamma-ray bursts, in which the relativistic flows are also expected to be pair dominated. The data, supported by particle-in-cell simulations and simple analytical estimates, indicate that these magnetic fields persist in the background plasma for thousands of inverse plasma frequencies. The existence of such long-lived magnetic fields can be related to analog astrophysical systems, such as those prevalent in lepton-dominated jets.

  17. Generation and study of relativistic electron beam

    International Nuclear Information System (INIS)

    Iyyengar, S.K.; Ron, P.H.; Mittal, K.C.; Goel, A.K.; Ramaswamy, V.; Rohatgi, V.K.

    1977-01-01

    Pulsed Electron Beam (REB) technology has progressed rapidly in recent years because of applications in various fields like radiation sources, high power laser development, plasma heating and fusion research. The REB development programme at the Plasma Physics Section of Bhabha Atomic Research Centre, Bombay, has been described. The design features of the 375 KV, 3500 A, 75 Joule REB generator are discussed. The diagnostic equipment developed for the studies is described. The present experimental studies and some preliminary results on beam characterisation are presented. (author)

  18. Chemical activation of molecules by metals: Experimental studies of electron distributions and bonding

    International Nuclear Information System (INIS)

    Lichtenberger, D.L.

    1991-10-01

    The formal relationship between measured molecular ionization energies and thermodynamic bond dissociation energies has been developed into a single equation which unifies the treatment of covalent bonds, ionic bonds, and partially ionic bonds. This relationship has been used to clarify the fundamental thermodynamic information relating to metal-hydrogen, metal-alkyl, and metal-metal bond energies. We have been able to obtain a direct observation and measurement of the stabilization energy provided by the agostic interaction of the C-H bond with the metal. The ionization energies have also been used to correlate the rates of carbonyl substitution reactions of (η 5 -C 5 H 4 X)Rh(CO) 2 complexes, and to reveal the electronic factors that control the stability of the transition state. The extent that the electronic features of these bonding interactions transfer to other chemical systems is being investigated in terms of the principle of additivity of ligand electronic effects. Specific examples under study include metal- phosphines, metal-halides, and metallocenes. Especially interesting has been the recent application of these techniques to the characterization of the soccer-ball shaped C 60 molecule, buckminsterfullerene, and its interaction with a metal surface. The high-resolution valence ionizations in the gas phase reveal the high symmetry of the molecule, and studies of thin films of C 60 reveal weak intermolecular interactions. Scanning tunneling and atomic force microscopy reveal the arrangement of spherical molecules on gold substrates, with significant delocalization of charge from the metal surface. 21 refs

  19. Analytical and experimental study of two delay-coupled excitable units.

    Science.gov (United States)

    Weicker, Lionel; Erneux, Thomas; Keuninckx, Lars; Danckaert, Jan

    2014-01-01

    We investigate the onset of time-periodic oscillations for a system of two identical delay-coupled excitable (nonoscillatory) units. We first analyze these solutions by using asymptotic methods. The oscillations are described as relaxation oscillations exhibiting successive slow and fast changes. The analysis highlights the determinant role of the delay during the fast transition layers. We then study experimentally a system of two coupled electronic circuits that is modeled mathematically by the same delay differential equations. We obtain quantitative agreements between analytical and experimental bifurcation diagrams.

  20. Study on discrete space charge effects in electron beams and guns

    International Nuclear Information System (INIS)

    Tang Tiantong

    1990-01-01

    The discrete space charge effects in electron beams are studied and a statistical dynamics equation of the ensemble of beam electrons is derived. An approximated analytical solution of this equation is given. This equation has been applied to beam crossover and field-emission and thermal-emission gun problems. The computer calculation results agree on the whole with those of Monte Carlo simulation and experimental data. (orig.)

  1. Secondary electron emission yield in the limit of low electron energy

    CERN Document Server

    Andronov, A.N.; Kaganovich, I.D.; Startsev, E.A.; Raitses, Y.; Demidov, V.I.

    2013-04-22

    Secondary electron emission (SEE) from solids plays an important role in many areas of science and technology.1 In recent years, there has been renewed interest in the experimental and theoretical studies of SEE. A recent study proposed that the reflectivity of very low energy electrons from solid surface approaches unity in the limit of zero electron energy2,3,4, If this was indeed the case, this effect would have profound implications on the formation of electron clouds in particle accelerators,2-4 plasma measurements with electrostatic Langmuir probes, and operation of Hall plasma thrusters for spacecraft propulsion5,6. It appears that, the proposed high electron reflectivity at low electron energies contradicts to numerous previous experimental studies of the secondary electron emission7. The goal of this note is to discuss possible causes of these contradictions.

  2. Beam studies and experimental facility for the AWAKE experiment at CERN

    International Nuclear Information System (INIS)

    Bracco, Chiara; Gschwendtner, Edda; Petrenko, Alexey; Timko, Helga; Argyropoulos, Theodoros; Bartosik, Hannes; Bohl, Thomas; Esteban Müller, Juan; Goddard, Brennan; Meddahi, Malika; Pardons, Ans; Shaposhnikova, Elena; Velotti, Francesco M.; Vincke, Helmut

    2014-01-01

    A Proton Driven Plasma Wakefield Acceleration Experiment has been proposed as an approach to eventually accelerate an electron beam to the TeV energy range in a single plasma section. To verify this novel technique, a proof of principle R and D experiment, AWAKE, is planned at CERN using 400 GeV proton bunches from the SPS. An electron beam will be injected into the plasma cell to probe the accelerating wakefield. The AWAKE experiment will be installed in the CNGS facility profiting from existing infrastructure where only minor modifications need to be foreseen. The design of the experimental area and the proton and electron beam lines are shown. The achievable SPS proton bunch properties and their reproducibility have been measured and are presented. - Highlights: • A proton driven plasma wakefield experiment using the first time protons as drive beam is proposed. • The integration of AWAKE experiment, the proton, laser and electron beam line in an existing CERN facility is demonstrated. • The necessary modifications in the experimental facility are presented. • Proton beam optics and a new electron beam line are adapted to match with the required beam parameters. • Short high-intensity bunches were studied in the SPS to guide the design parameters of the AWAKE project

  3. Multipurpose modular experimental station for the DiProI beamline of Fermi-Elettra free electron laser

    Energy Technology Data Exchange (ETDEWEB)

    Pedersoli, Emanuele; Capotondi, Flavio; Cocco, Daniele; Kaulich, Burkhard; Menk, Ralf H; Locatelli, Andrea; Mentes, Tevfik O; Spezzani, Carlo; Sandrin, Gilio; Bacescu, Daniel M; Kiskinova, Maya [Fermi, Elettra Sincrotrone Trieste, SS 14 - km 163.5, 34149 Basovizza, Trieste (Italy); Zangrando, Marco [Fermi, Elettra Sincrotrone Trieste, SS 14 - km 163.5, 34149 Basovizza, Trieste (Italy); IOM CNR, Laboratorio TASC, SS 14 - km 163.5, 34149 Basovizza, Trieste (Italy); Bajt, Sasa; Barthelmess, Miriam [Photon Science, DESY, Notkestrasse 85, 22607 Hamburg (Germany); Barty, Anton; Schulz, Joachim; Gumprecht, Lars [Centre for Free-Electron Laser Science, DESY, Notkestrasse 85, 22607 Hamburg (Germany); Chapman, Henry N [Centre for Free-Electron Laser Science, DESY, Notkestrasse 85, 22607 Hamburg (Germany); University of Hamburg, Notkestrasse 85, 22607 Hamburg (Germany); Nelson, A J; Frank, Matthias [Physical and Life Sciences, LLNL, 7000 East Avenue, Livermore, California 94550 (United States); others, and

    2011-04-15

    We present a compact modular apparatus with a flexible design that will be operated at the DiProI beamline of the Fermi-Elettra free electron laser (FEL) for performing static and time-resolved coherent diffraction imaging experiments, taking advantage of the full coherence and variable polarization of the short seeded FEL pulses. The apparatus has been assembled and the potential of the experimental setup is demonstrated by commissioning tests with coherent synchrotron radiation. This multipurpose experimental station will be open to general users after installation at the Fermi-Elettra free electron laser in 2011.

  4. Multipurpose modular experimental station for the DiProI beamline of Fermi-Elettra free electron laser

    International Nuclear Information System (INIS)

    Pedersoli, Emanuele; Capotondi, Flavio; Cocco, Daniele; Kaulich, Burkhard; Menk, Ralf H.; Locatelli, Andrea; Mentes, Tevfik O.; Spezzani, Carlo; Sandrin, Gilio; Bacescu, Daniel M.; Kiskinova, Maya; Zangrando, Marco; Bajt, Sasa; Barthelmess, Miriam; Barty, Anton; Schulz, Joachim; Gumprecht, Lars; Chapman, Henry N.; Nelson, A. J.; Frank, Matthias

    2011-01-01

    We present a compact modular apparatus with a flexible design that will be operated at the DiProI beamline of the Fermi-Elettra free electron laser (FEL) for performing static and time-resolved coherent diffraction imaging experiments, taking advantage of the full coherence and variable polarization of the short seeded FEL pulses. The apparatus has been assembled and the potential of the experimental setup is demonstrated by commissioning tests with coherent synchrotron radiation. This multipurpose experimental station will be open to general users after installation at the Fermi-Elettra free electron laser in 2011.

  5. Electronic and optical properties of Fe, Pd, and Ti studied by reflection electron energy loss spectroscopy

    International Nuclear Information System (INIS)

    Tahir, Dahlang; Kraaer, Jens; Tougaard, Sven

    2014-01-01

    We have studied the electronic and optical properties of Fe, Pd, and Ti by reflection electron energy-loss spectroscopy (REELS). REELS spectra recorded for primary energies in the range from 300 eV to 10 keV were corrected for multiple inelastically scattered electrons to determine the effective inelastic-scattering cross section. The dielectric functions and optical properties were determined by comparing the experimental inelastic-electron scattering cross section with a simulated cross section calculated within the semi-classical dielectric response model in which the only input is Im(−1/ε) by using the QUEELS-ε(k,ω)-REELS software package. The complex dielectric functions ε(k,ω), in the 0–100 eV energy range, for Fe, Pd, and Ti were determined from the derived Im(−1/ε) by Kramers-Kronig transformation and then the refractive index n and extinction coefficient k. The validity of the applied model was previously tested and found to give consistent results when applied to REELS spectra at energies between 300 and 1000 eV taken at widely different experimental geometries. In the present paper, we provide, for the first time, a further test on its validity and find that the model also gives consistent results when applied to REELS spectra in the full range of primary electron energies from 300 eV to 10000 eV. This gives confidence in the validity of the applied method.

  6. Experimental efforts at NIST towards one-electron ions in circular Rydberg states

    International Nuclear Information System (INIS)

    Tan, Joseph N; Guise, Nicholas D; Brewer, Samuel M

    2011-01-01

    Experimental effort is underway at NIST to enable tests of theory with one-electron ions synthesized in circular Rydberg states from captured bare nuclei. Problematic effects that limit the accuracy of predicted energy levels for low-lying states are vanishingly small for high-angular-momentum (high-L) states; in particular, the nuclear size correction for high-L states is completely negligible for any foreseeable improvement of measurement precision. As an initial step towards realizing such states, highly charged ions are extracted from the NIST electron beam ion trap (EBIT) and steered through the electrodes of a Penning trap. The goal is to capture bare nuclei in the Penning trap for experiments to make one-electron atoms in circular Rydberg states with dipole (E1) transitions in the optical domain accessible to a frequency comb.

  7. Experimental study on the kinetically induced electronic excitation in atomic collisional cascades

    International Nuclear Information System (INIS)

    Meyer, S.

    2006-01-01

    the present thesis deals with the ion-collision-induced electronic excitation of metallic solids. For this for the first time metal-insulator-metal layer systems are used for the detection of this electronic excitation. The here applied aluminium/aluminium oxide/silver layer sytems have barrier heights of 2.4 eV on the aluminium respectively 3.3 eV on the silver side. With the results it could uniquely be shown that the electronic excitation is generated by kinetic processes, this excitation dependenc on the kinetic energy of the colliding particles, and the excitation dependes on the charge state of the projectile

  8. Experimental studies of thermal and non-thermal electron cyclotron phenomena in tokamaks

    International Nuclear Information System (INIS)

    McDermott, F.S.

    1984-12-01

    A direct measurement of wave absorption in the ISX-B tokamak at the second harmonic of the electron cyclotron frequency is reported. Measurements of the absorption of a wave polarized in the extraordinary mode and propagating perpendicular to the toroidal magnetic field are in agreement with the absorption predicted by the linearized Vlasov equation for a thermal plasma. Agreement is found both for an analytic approximation to the wave absorption and for a numerical simulation of ray propagation in toroidal geometry. Observations are also reported on a non-linear, three-wave interaction process occurring during high power electron cyclotron resonance heating in the Versator II tokamak. The measured spectra and the threshold power are consistent with a model in which the incident power in the extraordinary mode of polarization decays at the upper hybrid resonance layer into a lower hybrid wave and an electron Bernstein wave. Finally, measurements of non-thermal emission at the second harmonic of the electron cyclotron frequency and below the electron plasma frequency are reported from low density, non-Maxwellian plasma in the Versator II tokamak. The emission spectra are in agreement with a model in which waves are driven unstable at the anomalous Doppler resonance, while only weakly damped at the Cerenkov resonance

  9. Transition radiation electron beam diagnostic study at ATF

    International Nuclear Information System (INIS)

    Qiu, X.Z.; Wang, X.J.; Batchelor, K.; Ben-Zvi, I.

    1995-01-01

    Recently we have started a program to develop transition radiation based electron beam diagnostics at the Accelerator Test Facility at Brookhaven National Laboratory. In this paper, we will discuss a technique to estimate the lower limit in electron beam divergence measurement with single foil transition radiation and two-foil transition radiation interferometer. Preliminary experimental data from 4.5 MeV electron beam will be presented

  10. Theoretical and experimental study of the relaxation of excited states of the DCM laser dye. Intra-molecular electron transfer and photo-isomerization. Solvent effects

    International Nuclear Information System (INIS)

    Marguet, Sylvie

    1992-01-01

    This research thesis reports the study of a styrenic laser dye, the 4-(dicyanomethylene)-2-methyl-6-[p-(dimethylamino) styryl]-4H-pyrane or DCM for the characterization of the first electronic states and of the influence of the solvent on efficiencies of different relaxation processes of the first excited state S1 of the DCM. Due to the presence of a combination of a donor group and acceptor group, this compound has interesting properties of intra-molecular charge transfer and of photo-isomerization which highly depend on solvent polarity. Two approaches have been adopted to study these complementary processes: an experimental approach (determination of rate constants of the different deactivation ways of the S1 state by measuring fluorescence quantum efficiencies, photo-isomerization quantum efficiencies, and fluorescence lifetimes of DCM in about twenty solvent of increasing polarity), and a computational approach (a CS-INDO-MRI type quantum chemistry calculation to obtain potential energy curves, charge distributions, and dipolar moments of DCM first electronic states) [fr

  11. Experimental study of the Hall effect and electron diffusion region during magnetic reconnection in a laboratory plasma

    International Nuclear Information System (INIS)

    Ren Yang; Yamada, Masaaki; Ji Hantao; Dorfman, Seth; Gerhardt, Stefan P.; Kulsrud, Russel

    2008-01-01

    The Hall effect during magnetic reconnection without an external guide field has been extensively studied in the laboratory plasma of the Magnetic Reconnection Experiment [M. Yamada et al., Phys. Plasmas 4, 1936 (1997)] by measuring its key signature, an out-of-plane quadrupole magnetic field, with magnetic probe arrays whose spatial resolution is on the order of the electron skin depth. The in-plane electron flow is deduced from out-of-plane magnetic field measurements. The measured in-plane electron flow and numerical results are in good agreement. The electron diffusion region is identified by measuring the electron outflow channel. The width of the electron diffusion region scales with the electron skin depth (∼5.5-7.5c/ω pe ) and the peak electron outflow velocity scales with the electron Alfven velocity (∼0.12-0.16V eA ), independent of ion mass. The measured width of the electron diffusion region is much wider and the observed electron outflow is much slower than those obtained in 2D numerical simulations. It is found that the classical and anomalous dissipation present in the experiment can broaden the electron diffusion region and slow the electron outflow. As a consequence, the electron outflow flux remains consistent with numerical simulations. The ions, as measured by a Mach probe, have a much wider outflow channel than the electrons, and their outflow is much slower than the electron outflow everywhere in the electron diffusion region

  12. Effect of static electronic advertising signs on road safety: an experimental case study.

    Science.gov (United States)

    Izadpanah, Pedram; Omrani, Reza; Koo, Sheldon; Hadayeghi, Ali

    2014-01-01

    As technology continues to advance, the outdoor advertising industry is taking advantage of electronic signs, some of which are static electronic signs (SES), with the ability to automatically change the message shown on the sign at regular intervals. Studies indicate that SES has a negative impact on the drivers' visual attention and on vehicle control. However, the actual effects of the SES on the number of collisions have been difficult to prove conclusively. The objective of this article is to generate a clear understanding of the safety impacts of SES on the number collisions by conducting a before-and-after analysis with comparison groups. The analysis was based on a total of 10 SES along the Highway 27 and the Gardiner Expressway of the city of Toronto. The results of the before-and-after study revealed that there was not enough evidence to suggest that these signs have any impact on road safety along the adjacent roadway sections at a 95% confidence interval. The same results were obtained by comparing collisions that occurred during daylight and artificial light.

  13. Flat Miniature Heat Pipes for Electronics Cooling: State of the Art, Experimental and Theoretical Analysis

    OpenAIRE

    M.C. Zaghdoudi; S. Maalej; J. Mansouri; M.B.H. Sassi

    2011-01-01

    An experimental study is realized in order to verify the Mini Heat Pipe (MHP) concept for cooling high power dissipation electronic components and determines the potential advantages of constructing mini channels as an integrated part of a flat heat pipe. A Flat Mini Heat Pipe (FMHP) prototype including a capillary structure composed of parallel rectangular microchannels is manufactured and a filling apparatus is developed in order to charge the FMHP. The heat transfer im...

  14. Experimental Study on Rebar Corrosion Using the Galvanic Sensor Combined with the Electronic Resistance Technique

    Science.gov (United States)

    Xu, Yunze; Li, Kaiqiang; Liu, Liang; Yang, Lujia; Wang, Xiaona; Huang, Yi

    2016-01-01

    In this paper, a new kind of carbon steel (CS) and stainless steel (SS) galvanic sensor system was developed for the study of rebar corrosion in different pore solution conditions. Through the special design of the CS and SS electronic coupons, the electronic resistance (ER) method and zero resistance ammeter (ZRA) technique were used simultaneously for the measurement of both the galvanic current and the corrosion depth. The corrosion processes in different solution conditions were also studied by linear polarization resistance (LPR) and the measurements of polarization curves. The test result shows that the galvanic current noise can provide detailed information of the corrosion processes. When localized corrosion occurs, the corrosion rate measured by the ER method is lower than the real corrosion rate. However, the value measured by the LPR method is higher than the real corrosion rate. The galvanic current and the corrosion current measured by the LPR method shows linear correlation in chloride-containing saturated Ca(OH)2 solution. The relationship between the corrosion current differences measured by the CS electronic coupons and the galvanic current between the CS and SS electronic coupons can also be used to evaluate the localized corrosion in reinforced concrete. PMID:27618054

  15. Experimental Study on Rebar Corrosion Using the Galvanic Sensor Combined with the Electronic Resistance Technique

    Directory of Open Access Journals (Sweden)

    Yunze Xu

    2016-09-01

    Full Text Available In this paper, a new kind of carbon steel (CS and stainless steel (SS galvanic sensor system was developed for the study of rebar corrosion in different pore solution conditions. Through the special design of the CS and SS electronic coupons, the electronic resistance (ER method and zero resistance ammeter (ZRA technique were used simultaneously for the measurement of both the galvanic current and the corrosion depth. The corrosion processes in different solution conditions were also studied by linear polarization resistance (LPR and the measurements of polarization curves. The test result shows that the galvanic current noise can provide detailed information of the corrosion processes. When localized corrosion occurs, the corrosion rate measured by the ER method is lower than the real corrosion rate. However, the value measured by the LPR method is higher than the real corrosion rate. The galvanic current and the corrosion current measured by the LPR method shows linear correlation in chloride-containing saturated Ca(OH2 solution. The relationship between the corrosion current differences measured by the CS electronic coupons and the galvanic current between the CS and SS electronic coupons can also be used to evaluate the localized corrosion in reinforced concrete.

  16. Electronic structure of MnSi : The role of electron-electron interactions

    NARCIS (Netherlands)

    Carbone, F; Zangrando, M; Brinkman, A; Nicolaou, A; Bondino, F; Magnano, E; Nugroho, A. A.; Parmigiani, F; Jarlborg, T; van der Marel, D

    We present an experimental study of the electronic structure of MnSi. Using x-ray absorption spectroscopy (XAS), x-ray photoemission, and x-ray fluorescence, we provide experimental evidence that MnSi has a mixed valence ground state. We show that self-consistent local density approximation

  17. Electronic structure of MnSi: The role of electron-electron interactions

    NARCIS (Netherlands)

    Carbone, F.; Zangrando, M.; Brinkman, Alexander; Nicolaou, A.; Bondino, F.; Magnano, E.; Nugroho, A.A.; Parmigiani, F.; Jarlborg, Th.; van der Marel, D.

    2006-01-01

    We present an experimental study of the electronic structure of MnSi. Using x-ray absorption spectroscopy (XAS), x-ray photoemission, and x-ray fluorescence, we provide experimental evidence that MnSi has a mixed valence ground state. We show that self-consistent local density approximation

  18. An extended model of electrons: experimental evidence from high-resolution scanning tunneling microscopy

    International Nuclear Information System (INIS)

    Hofer, Werner A

    2012-01-01

    In a recent paper we introduced a model of extended electrons, which is fully compatible with quantum mechanics in the formulation of Schrödinger. However, it contradicts the current interpretation of electrons as point-particles. Here, we show by a statistical analysis of high-resolution scanning tunneling microscopy (STM) experiments, that the interpretation of electrons as point particles and, consequently, the interpretation of the density of electron charge as a statistical quantity will lead to a conflict with the Heisenberg uncertainty principle. Given the precision in these experiments we find that the uncertainty principle would be violated by close to two orders of magnitude, if this interpretation were correct. We are thus forced to conclude that the density of electron charge is a physically real, i.e. in principle precisely measurable quantity, as derived in a recent paper. Experimental evidence to the contrary, in particular high-energy scattering experiments, is briefly discussed. The finding is expected to have wide implications in condensed matter physics, chemistry, and biology, scientific disciplines which are based on the properties and interactions of electrons.

  19. Studies of dynamics of electron clouds in STAR silicon drift detectors

    CERN Document Server

    Bellwied, R; Brandon, N; Caines, H; Chen, W; Dimassimo, D; Dyke, H; Hall, J R; Hardtke, D; Hoffmann, G W; Humanic, T J; Kotova, A I; Kotov, I V; Kraner, H W; Li, Z; Lynn, D; Middelkamp, P; Ott, G; Pandey, S U; Pruneau, C A; Rykov, V L; Schambach, J; Sedlmeir, J; Sugarbaker, E R; Takahashi, J; Wilson, W K

    2000-01-01

    The dynamics of electrons generated in silicon drift detectors was studied using an IR LED. Electrons were generated at different drift distances. In this way, the evolution of the cloud as a function of drift time was measured. Two methods were used to measure the cloud size. The method of cumulative functions was used to extract the electron cloud profiles. Another method obtains the cloud width from measurements of the charge collected on a single anode as a function of coordinate of the light spot. The evolution of the electron cloud width with drift time is compared with theoretical calculations. Experimental results agreed with theoretical expectations.

  20. Coherent Electron Focussing in a Two-Dimensional Electron Gas.

    NARCIS (Netherlands)

    Houten, H. van; Wees, B.J. van; Mooij, J.E.; Beenakker, C.W.J.; Williamson, J.G.; Foxon, C.T.

    1988-01-01

    The first experimental realization of ballistic point contacts in a two-dimensional electron gas for the study of transverse electron focussing by a magnetic field is reported. Multiple peaks associated with skipping orbits of electrons reflected specularly by the channel boundary are observed. At

  1. Secondary electron emission studied by secondary electron energy loss coincidence spectroscopy (SE2ELCS)

    International Nuclear Information System (INIS)

    Khalid, R.

    2013-01-01

    Emission of secondary electrons is of importance in many branches of fundamental and applied science. It is widely applied in the electron microscope for the investigation of the structure and electronic state of solid surfaces and particle detection in electron multiplier devices, and generally it is related to the energy dissipation of energetic particles moving inside a solid. The process of secondary electron emission is a complex physical phenomenon, difficult to measure experimentally and treat theoretically with satisfactory accuracy. The secondary electron spectrum measured with single electron spectroscopy does not provide detailed information of the energy loss processes responsible for the emission of secondary electrons. This information can be accessed when two correlated electron pairs are measured in coincidence and the pair consists of a backscattered electron after a given energy loss and a resulting emitted secondary electron. To investigate the mechanisms responsible for the emission of secondary electrons, a reflection (e,2e) coincidence spectrometer named Secondary Electron Electron Energy Loss Coincidence Spectrometer (SE2ELCS) has been developed in the framework of this thesis which allows one to uncover the relation between the features in the spectra which are due to energy losses and true secondary electron emission structures. The correlated electron pairs are measured with a hemispherical mirror analyzer (HMA) and a time of flight analyzer (TOF) by employing a continuous electron beam. An effort has been made to increase the coincidence count rate by increasing the effective solid angle of the TOF analyzer and optimizing the experimental parameters to get optimum energy resolution. Double differential coincidence spectra for a number of materials namely, nearly free electron metals (Al, Si), noble metals (Ag, Au, Cu, W) and highly oriented pyrolytic graphite (HOPG) have been measured using this coincidence spectrometer. The

  2. Experimental and Numerical Studies on the Proposed Application of Hollow Electron Beam Collimation for the LHC at CERN

    Energy Technology Data Exchange (ETDEWEB)

    Moens, Vince [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

    2013-01-01

    This thesis work was carried out in the framework of the U.S. LHC Accelerator Research Program (USLARP), a collaboration between the European Organization for Nuclear Research (CERN) and the U.S. Department of Energy. The first half of the work was completed at Fermilab (USA), the location of the Tevatron, a proton-antiproton collider and the second largest particle collider in the world. The second half was completed at CERN (Switzerland), the location of the largest proton collider in the world (Large Hadron Collider (LHC)). This thesis characterizes a Hollow Electron Beam (HEB) for possible usage at the LHC to enhance its collimation through Hollow Electron Beam Lenses (HEBLs). Collimation is a long established principle in high energy particle accelerators. Hollow Electron Beam Collimation (HEBC) aims to enhance current collimation systems by controlling diffusion of primary halo particles into the limiting aperture. It works on the principle of a transverse radial electric field that kicks the primary halo particles outwards upon each pass in a multi-pass system. The transverse field is produced by a HEB that is coaxially aligned with the accelerator beam, producing a negligible electric field in the center and a strong transverse electric field at amplitudes higher than the inner radius of the electron beam. Ideally, halo particles are affected without perturbation of the beam core. One of the main advantages of this system is to decrease the dependence on instantaneous loss spikes and beam jitter. A solid experimental basis of HEBC was accumulated at the Tevatron. The application of this technique at the LHC is now under investigation. The aim of this thesis is to present a preliminary report to support a future optimal conceptual design report. It characterizes the available hardware in order to facilitate the design of a Hollow Electron Gun (HEG) for the LHC, characterizes the effect on beam diffusion by determining the transverse electric fields of the

  3. Experimental study of water absorption of electronic components and internal local temperature and humidity into electronic enclosure

    DEFF Research Database (Denmark)

    Conseil, Helene; Jellesen, Morten Stendahl; Ambat, Rajan

    2014-01-01

    Corrosion reliability of electronic products is a key factor for electronics industry, and today there is a large demand for performance reliability in large spans of temperature and humidity during day and night shifts. Corrosion failures are still seen due to the effects of temperature, humidity......, differential humidity, and temperature effects simulating day/night, and the use of desiccants....

  4. Experimental investigation of the generation of harmonic photons from the interaction of free electrons with intense laser radiation

    International Nuclear Information System (INIS)

    Englert, T.J.

    1983-01-01

    An experimental investigation of the generation of second harmonic photons through the interaction of free electrons with an intense laser beam has been performed. Second harmonic photons with a wavelength of 530nm generated from the interaction of free electrons with 1060nm photons from a neodymium-glass laser are implied by observing Doppler shifted photons with wavelengths of 490nm and 507nm. The observed photon wavelengths results from a Doppler shift of the laser photon wavelengths as viewed in the rest frame of the electrons combined with a Doppler shift of the second harmonic photons emitted from 1600eV and 500eV electrons. Comparison of experimental results with those predicted by cross sections, derived using classical and quantum electrodynamics, shows reasonable agreement with both theories. Although second harmonic photons are created, the dynamics of second harmonic photon generation (accelerated electron motion due to the electromagnetic field or actual two-photon interaction with the electron) cannot be resolved without further experiment

  5. Experimental study of the single electron response of the DELPHI Barrel RICH MWPC's

    International Nuclear Information System (INIS)

    Dracos, M.

    1989-01-01

    We present herewith the results of an experimental study of the multiwire proportionnal chambers (MWPC's) used in the Barrel RICH particle identifier of the LEP-DELPHI experiment. Emphasis is given to the problem of detection efficiency and to the measurements of the charge induced by a single photoelectron

  6. Experimental realization of millimeter-wave amplification by a sheet beam free electron laser

    International Nuclear Information System (INIS)

    Zhang, Z.; Destler, W.W.; Granatstein, V.L.; Antonsen, T.M. Jr.; Levush, B.; Rodgers, J.; Cheng, S.

    1994-01-01

    We report an observation of millimeter-wave (94 GHz) amplification in a sheet beam, short period, planar wiggler, free electron laser amplifier. The observed gain is about 5 dB for a 530 keV, 4 A beam through a 54 cm wiggler. Wave energy absorption was also observed when the beam energy is off-resonance. Experimental results are in good agreement with numerical simulation. This amplifier configuration has potential for producing equally high output power but at relatively low voltage compared with longer period free electron lasers

  7. Theoretical and experimental study of the electron distribution function in the plasma of an electron cyclotron resonance ion source

    International Nuclear Information System (INIS)

    Girard, A.; Perret, C.; Bourg, F.; Khodja, H.; Melin, G.; Lecot, C.

    1997-01-01

    Electron Cyclotron Resonance Ion Sources (ECRIS) are mirror machines which can deliver important fluxes of Highly Charged Ions (HCI). These performances are strongly correlated with hot electrons sustained by an RF wave. This paper presents an analysis of the EDF in an ECR source. In the first part of the paper a one-dimensional Fokker-Planck code for the Electron Distribution Function is presented: this code includes a quasilinear diffusion operator for the RF wave, a collision term and a source term due to electron impact ionization. The present status of this code is presented. In the second part of the paper experiments related to the measurement of the EDF are presented: electron density, diamagnetism, electron endloss current have been measured at the Quadrumafios ECRIS. With these results it is possible to give a precise description of the EDF. (author)

  8. Study and realization of an electron gun at low energy

    International Nuclear Information System (INIS)

    Camus, P.

    1977-01-01

    This work presents the theoretical concepts and experimental design of an electron gun. This gun is working in the weak energy range and the focus position is independant of electron energy measurements and analysis methods of the electron beam are described [fr

  9. Experimental investigation of electron cooling and stacking of lead ions in a low energy accumulation ring

    CERN Document Server

    Bosser, Jacques; Chanel, M; Hill, C; Lombardi, A M; MacCaferri, R; Maury, S; Möhl, D; Molinari, G; Rossi, S; Tanke, E; Tranquille, G; Vretenar, Maurizio

    1999-01-01

    This report gives the results of a programme of experimental investigations, which were carried out to test stacking of lead ions in a storage ring (the former Low Energy Antiproton Ring, LEAR) at 4.2 MeV per nucleon. The motivation was to demonstrate the feasibility of gaining the large factor in the phase-space density required for injection into the LHC. In the first part of the report, the layout of the experiments is described, the choice of the parameters of the electron cooling system used for stacking is reported and the multi-turn injection using horizontal- and longitudinal- (and in the final project also vertical-) phase space is discussed. In the second part the experimental results are presented. Factors of vital importance are the stacking efficiency, the beam life-time and the cooling time of the ions. The beam decay owing to charge exchange with the residual gas and to recombination by the capture of cooling electrons was intensively studied. Beam instabilities and space-charge effects in the ...

  10. A coincidence study between photo- and Auger electrons

    International Nuclear Information System (INIS)

    Ricz, S.; Koever, A.; Varga, D.; Molnar, J.; Aksela, S.; Jurvansuu, M.

    2000-01-01

    Complete text of publication follows. The investigation of double differential cross sections of photon induced Auger electrons provides very sensitive method for studying the rearrangement process, especially when the angular correlation between photo- and Auger electrons is also studied. Such type of measurements could reveal a new aspect in studying the electron-electron, hole-electron and photoelectron - Auger electron interactions. It enables one to separate the overlapping Auger lines belonging to different initial holes. The traditional coincidence measurement is very time consuming and causes serious calibration problems. In order to overcome these experimental difficulties a new electron-spectrometer (ESA-22) was developed in ATOMKI, Debrecen in cooperation with the Electron spectroscopy group of University of Oulu, Finland. The analyzer consists of a spherical and a cylindrical part. It is very similar to the ESA-21 analyzer. The main differences is that the focal ring can be set different diameters thus either a series of channel detectors can be used to detect the electrons at different angles or a position sensitive channel plate can be applied for simultaneous angular recording of electrons. Furthermore the outer sphere and cylinder are cut into two parts so the spectrometer is capable to analyze two independent angularly resolved electron spectra (in the 0 deg - 180 deg region) at different energy regions, simultaneously. A special electronic control and data handling electronics and software was worked out to control the analyzer. The first results were presented in. In the last year the ESA-22 electron-spectrometer was transported to the I411 beam line of MAX-II synchrotron in Lund, Sweden. The advanced properties of the spectrometer was investigated by measuring coincidences between the photoelectrons originated from the Ar L 3 subshell and the Ar Auger electrons in the 203-207 eV energy region. Fig. 1 shows the single and the coincidence spectra

  11. Ab initio study of the electron-phonon coupling at the Cr(001) surface

    Science.gov (United States)

    Peters, L.; Rudenko, A. N.; Katsnelson, M. I.

    2018-04-01

    It is experimentally well established that the Cr(001) surface exhibits a sharp resonance around the Fermi level. However, there is no consensus about its physical origin. It is proposed to be either due to a single particle dz2 surface state renormalized by electron-phonon coupling or the orbital Kondo effect involving the degenerate dx z/ dy z states. In this paper we examine the electron-phonon coupling of the Cr(001) surface by means of ab-initio calculations in the form of density functional perturbation theory. More precisely, the electron-phonon mass-enhancement factor of the surface layer is investigated for the 3d states. For the majority and minority spin dz2 surface states we find values of 0.19 and 0.16. We show that these calculated electron-phonon mass-enhancement factors are not in agreement with the experimental data even if we use realistic values for the temperature range and surface Debye frequency for the fit of the experimental data. More precisely, then experimentally an electron-phonon mass-enhancement factor of 0.70 ±0.10 is obtained, which is not in agreement with our calculated values of 0.19 and 0.16. Our findings suggest that the experimentally observed resonance at the Cr(001) surface is not due to electron-phonon effects but due to electron-electron correlation effects.

  12. A theoretical and (e,2e) experimental investigation into the complete valence electronic structure of (1.1.1) propellane

    Energy Technology Data Exchange (ETDEWEB)

    Adcock, W.; Clark, C.I. [Flinders Univ. of South Australia, Bedford Park, SA (Australia); Brunger, M.J.; McCarthy, I.E. [Flinders Univ. of South Australia, Bedford Park, SA (Australia). School of Physical Sciences; Michalewicz, M.T. [CSIRO, Carlton, VIC (Australia). Division of Information Technology; Von Niessen, W. [Technische Univ., Braunschweig (Germany). Institute fur Physikalische and Theoretische Chemie; Weigold, E. [Australian National Univ., Canberra, ACT (Australia). Inst. of Advanced Studies; Winkler, D.A. [Commonwealth Scientific and Industrial Research Organisation (CSIRO), Clayton, VIC (Australia). Div. of Chemical Physics

    1996-08-01

    The first comprehensive electronic structural study of the complete valence shell of [1.1.1] propellane is reported. Binding energy spectra were measured in the energy regime 3.5-46.5 eV over a range of different target electron momentum so that individual orbital momentum profiles could also be determined. These binding energy spectra were collected using an energy dispersive multichannel electron momentum spectrometer at a total energy of 1000 eV, with a coincidence energy resolution of 1.38 eV and a momentum resolution of about 0.1 a.u. The experimental orbital electron momentum profiles are compared with those calculated in the plane wave impulse approximation (PWIA) using both a triple zeta plus polarisation level SCF wavefunction and a further 13 basis sets as calculated using Density Functional Theory (DFT). A critical comparison between the experimental an theoretical momentum distributions (MDs) allows to determine the optimum wavefunction for [1.1.1]propellane. In general, the level of agreement between the experimental and theoretical MDs for the optimum wavefunction for all of the respective valence orbitals was very good. The determination of this wavefunction then allowed to derive the chemically interesting molecular properties of [1.1.1]propellane. These include infrared spectra, bond lengths, bond orders, electron densities and many others. A summary of these results and a comparison of them with the previous results of other workers is presented with the level of agreement typically being good. In particular, the existence of the C1-C3 bridging bond with a bond order of 0.70 was confirmed. 59 refs., 4 tabs., 11 figs.

  13. Experimentation and correlates of electronic nicotine delivery system (electronic cigarettes) among university students – A cross sectional study

    OpenAIRE

    K.H. Awan

    2016-01-01

    Objective: E-cigarettes are becoming popular among youth as safe nicotine delivery systems. Many have expressed concern, however, that e-cigarettes may serve as a gateway to future smoking, given their low perceived risk, or that their use may prevent regular smokers from quitting by maintaining their nicotine addiction. The aim of this study was to assess experimentation with and correlates of e-cigarette use among university students. Material and methods: A cross-sectional study was car...

  14. Experimental evidence of nitrous acid formation in the electron beam treatment of flue gas

    International Nuclear Information System (INIS)

    Maetzing, H.; Namba, H.; Tokunaga, O.

    1994-01-01

    In the Electron Beam Dry Scrubbing (EBDS) process, flue gas from fossil fuel burning power plants is irradiated with accelerated (300-800 keV) electrons. Thereby, nitrogen oxide (NO x ) and sulfur dioxide (SO 2 ) traces are transformed into nitric and sulfuric acids, respectively, which are converted into particulate ammonium nitrate and sulfate upon the addition of ammonia. The powdery product can be filtered from the main gas stream and can be sold as agricultural fertilizer. A lot of experimental investigations have been performed on the EBDS process and computer models have been developed to interpret the experimental results and to predict economic improvements. According to the model calculations, substantial amounts of intermediate nitrous acid (HNO 2 ) are formed in the electron beam treatment of flue gas. The first experimental investigation about the formation of nitrous acid in an irradiated mixture of NO in synthetic air has been undertaken. Under these conditions, aerosol formation is avoided. UV spectra of the irradiated gas were recorded in the wavelength range λ = 345-375 nm. Both NO 2 and HNO 2 have characteristic absorption bands in this wavelength range. Calibration spectra of NO 2 were subtracted from the sample spectra. The remaining absorption bands can clearly be assigned to nitrous acid. The concentration of nitrous acid was determined by differential optical absorption. It was found lower than the model prediction. The importance of nitrous acid formation in the EBDS process needs to be clarified. (author)

  15. Molecular and electronic structures of oxo-bis(benzene-1,2-dithiolato)chromate(V) monoanions. A combined experimental and density functional study.

    Science.gov (United States)

    Kapre, Ruta; Ray, Kallol; Sylvestre, Isabelle; Weyhermüller, Thomas; DeBeer George, Serena; Neese, Frank; Wieghardt, Karl

    2006-05-01

    Two oxo-bis(benzene-1,2-dithiolato)chromate(V) complexes, namely, [CrO(L(Bu))2]1- and [CrO(L(Me))2]1-, have been synthesized and studied by UV-vis, EPR, magnetic circular dichroism (MCD), and X-ray absorption spectroscopy and by X-ray crystallography; their electro- and magnetochemistries are reported. H2L(Bu) represents the pro-ligand 3,5-di-tert-butylbenzene-1,2-dithiol, and H2L(Me) is the corresponding 4-methyl-benzene-1,2-dithiol. A structural feature of interest for both the complexes is the folding of the dithiolate ligands about the S-S vector providing Cs symmetry to the complexes. Geometry optimizations using all-electron density functional theory with scalar relativistic corrections at the second-order Douglas-Kroll-Hess (DKH2) and zeroth-order regular approximation (ZORA) levels result in excellent agreement with the experimentally determined structures and electronic and S K-edge X-ray absorption spectra. From DFT calculations, the Cs instead of C2v symmetry for the complexes is attributed to the strong S(3p) --> Cr(3d(x2-y2)) pi-donation in Cs geometry providing additional stability to the complexes.

  16. Electron microscope studies

    International Nuclear Information System (INIS)

    Crewe, A.V.; Kapp, O.H.

    1992-01-01

    This is a report covering the research performed in the Crewe laboratory between 1964 and 1992. Because of limitations of space we have provided relatively brief summaries of the major research directions of the facility during these years. A complete bibliography has been included and we have referenced groups of pertinent publications at the beginning of each section. This report summarizes our efforts to develop better electron microscopes and chronicles many of the experimental programs, in materials science and biology, that acted both as a stimulus to better microscope design and also as a testing ground for many instrumental innovations

  17. Electron microscope studies

    Energy Technology Data Exchange (ETDEWEB)

    Crewe, A.V.; Kapp, O.H.

    1992-07-01

    This is a report covering the research performed in the Crewe laboratory between 1964 and 1992. Because of limitations of space we have provided relatively brief summaries of the major research directions of the facility during these years. A complete bibliography has been included and we have referenced groups of pertinent publications at the beginning of each section. This report summarizes our efforts to develop better electron microscopes and chronicles many of the experimental programs, in materials science and biology, that acted both as a stimulus to better microscope design and also as a testing ground for many instrumental innovations.

  18. Study on radiation damage of electron and γ-rays and mechanism of nuclear hardening

    International Nuclear Information System (INIS)

    Jing Tao

    2001-01-01

    Radiation damage effects of electrons and γ-rays are presented. The damage defects are studied by experimental methods. On the basis of these studies the damage mechanism and nuclear hardening techniques are studied

  19. Structural studies of glasses by transmission electron microscopy and electron diffraction

    International Nuclear Information System (INIS)

    Kashchieva, E.P.

    1997-01-01

    The purpose of this work is to present information about the applications of transmission electron microscopy (TEM) and electron diffraction (ED) for structural investigations of glasses. TEM investigations have been carried out on some binary and on a large number of ternary borate-telluride systems where glass-forming oxides, oxides of transitional elements and modified oxides of elements from I, II and III groups in the periodic table, are used as third component. The large experimental data given by TEM method allows the fine classification of the micro-heterogeneities. A special case of micro-heterogeneous structure with technological origin occurs near the boundary between the 2 immiscible liquids obtained at macro-phase separation. TEM was also used for the direct observation of the glass structure and we have studied the nano-scale structure of borate glasses obtained at slow and fast cooling of the melts. The ED possesses advantages for analysis of amorphous thin films or micro-pastilles and it is a very useful technique for study in materials containing simultaneously light and heavy elements. A comparison between the possibilities of the 3 diffraction techniques (X-ray diffraction, neutron diffraction and ED) is presented

  20. A computer code package for Monte Carlo photon-electron transport simulation Comparisons with experimental benchmarks

    International Nuclear Information System (INIS)

    Popescu, Lucretiu M.

    2000-01-01

    A computer code package (PTSIM) for particle transport Monte Carlo simulation was developed using object oriented techniques of design and programming. A flexible system for simulation of coupled photon, electron transport, facilitating development of efficient simulation applications, was obtained. For photons: Compton and photo-electric effects, pair production and Rayleigh interactions are simulated, while for electrons, a class II condensed history scheme was considered, in which catastrophic interactions (Moeller electron-electron interaction, bremsstrahlung, etc.) are treated in detail and all other interactions with reduced individual effect on electron history are grouped together using continuous slowing down approximation and energy straggling theories. Electron angular straggling is simulated using Moliere theory or a mixed model in which scatters at large angles are treated as distinct events. Comparisons with experimentally benchmarks for electron transmission and bremsstrahlung emissions energy and angular spectra, and for dose calculations are presented

  1. Electronic excitation of Na atom by electron impact

    International Nuclear Information System (INIS)

    Bielschowsky, C.E.; Souza, G.G.B. de; Lucas, C.A.; Nogueira, J.C.

    1988-01-01

    Electronic excitation of the 3s-3p transition in the Na atom was studied by intermediate energy electron impact spectroscopy. Differential Cross Sections (DCS) and Generalized Oscillator Strenghts (GOS) were determined experimentally for 1 KeV electrons. Theoretical results within the First Born Approximation as well as Glauber theory, were also performed. (A.C.A.S.) [pt

  2. Experimental study of parametric instabilities and anomalous heating in plasma

    International Nuclear Information System (INIS)

    Batanov, G.M.; Rabinovich, M.S.

    1975-01-01

    Over the last few years the study of the dissipation of electromagnetic wave energy in a hot plasma has become perhaps one of the main problems of high-temperature plasma physics and controlled thermonuclear fusion. The focus of attention is on the processes by which electromagnetic energy is transformed into potential plasma waves and the processes involving relaxation of the latter. In this paper the authors summarize the experimental research into these processes conducted at the Lebedev Physics Institute over the 10 cm wave band. In the case of an isotropic plasma the authors recorded non-linear generation of Langmuir noise, the energy density of which was found to be comparable, in order of magnitude, with that of a pump wave. They detected the generation of fast-electron streams, the non-stationary character of the latter with respect to time, and non-linear transmissivity of the plasma layer. In the case of a magnetoactive plasma they studied the parametric excitation of oscillations at the upper hybrid frequency during its resonance with the first overtone of the pump wave. Excitation of plasma noise was found to be accompanied by a flux of fast-electrons, in the energy spectrum of which separate groups were detected. It was also found that the effective collision frequency increased by 1-3 orders, compared to the pari-collision frequency. In the region of magnetic waves close to the electron cyclotron resonance the authors observed forced Mandel'shtam-Brillouin scattering and kinetic instability of the plasma. It was found that the excitation of ionic Langmuir noise preceded ''anomalous absorption'' of waves and ''anomalous heating'' of electrons. The authors further consider the possibility of an experimental study of anomalous heating in plasma in the region of the lower hybrid frequencies, using the Institute's L-2 stellarator. (author)

  3. Experimental observation of exploding electron bubbles

    International Nuclear Information System (INIS)

    Classen, J.; Su, C.K.; Hall, S.C.; Pettersen, M.S.; Maris, H.J.

    1996-01-01

    Since free electrons form small voids in liquid helium they are expected to be preferred sites for nucleating macroscopic bubbles when the liquid is exposed to sufficiently large negative pressures. We have performed a series of cavitation experiments using focussed ultrasound where free electrons were introduced into the liquid by a radioactive source. The electron bubbles are found to explode at negative pressures significantly lower than those required for homogeneous nucleation. We present measurements of the thresholds for cavitation at electrons in the temperature range 1 - 4.5 K. Reasonable agreement with a simple model for the stability limit of the electron bubble is obtained. (author)

  4. Study of radiation-thermal effect of electron beam on steel and cast iron

    International Nuclear Information System (INIS)

    Machurin, E.S.; Lonchin, G.M.

    1980-01-01

    Studied is the influence of radiation-heat treatment by high energy (3-4.5 MeV) electron beam on the structure and properties of carbon steels (65G, 90KhF) and cast iron. Metallography and electron microscopy methods are used to study microstructure. It is shown that after the treatment by the electron beam there is observed noticeable structure grinding, sample fracture viscosity (even in a quenched state), increase of hardness and impact strength. The mechanism of metal heating process by electron beam is calculated and temperature field is defined in a heating region accounting for electron beam characteristics, medium and geometric factor. Theoretical data are close to experimental ones obtained in a course of determining the microhardness of irradiated samples for the cases of electron treatment duration up to 10 s

  5. Experimental studies of the laser-controlled collective ion accelerator

    International Nuclear Information System (INIS)

    Destler, W.W.; Rodgers, J.; Segalov, Z.

    1989-01-01

    Detailed experimental studies of a collective acceleration experiment in which a time-sequenced laser-generated ionization channel is used to control the propagation of an intense relativistic electron beamfront are presented. Ions trapped in the potential well at the beamfront are accelerated as the velocity of the beamfront is increased in a manner controlled by the time-dependent axial extent of the ionization channel. Beamfront propagation data for two different accelerating gradients are presented, together with results of ion acceleration studies for both gradients

  6. Electron spectroscopy in the fundamental process of electron-nucleus bremsstrahlung

    International Nuclear Information System (INIS)

    Hillenbrand, Pierre-Michel

    2013-07-01

    Within the scope of this thesis the fundamental process of electron-nucleus bremsstrahlung was studied in inverse kinematics at the Experimental Storage Ring ESR at GSI. For the system U 88+ + N 2 at 90 MeV/u it was shown, that by using inverse kinematics coincidence measurements between the scattered electron and the emitted photon can be performed for the case, in which the incoming electron transfers almost all of its kinetic energy onto the emitted photon. The sensitivity to the fundamental process could be achieved by measuring triple differential cross sections as a function of the emission angle of the photon and the scattered electron as well as the energy of the scattered electron. The optics of the magnetic electron spectrometer used were thoroughly revised and optimized to the experimental requirements. Analyzing different coincidences in this collision system, it was possible to determine the contributions to the electron distribution arising from radiative electron capture to the projectile continuum, nonradiative electron capture to the projectile continuum, and electron loss to the projectile continuum. The experimental results of each of these processes were compared to theoretical calculations. The electron spectra for the radiative and the nonradiative electron capture to continuum clearly reproduce the opposite asymmetry predicted by theory. Furthermore electron spectra for collisions of U 28+ with different gases were measured.

  7. Study and impact of fast electrons diagnosed by electron cyclotron radiation on Tore-Supra tokamak

    International Nuclear Information System (INIS)

    Gomez, P.

    1999-12-01

    This thesis aims at characterizing the dynamics of fast electrons generated by the Landau absorption of the hybrid wave and studying their effects on electron cyclotron radiation. The different processes involved in the propagation and resonant absorption of the hybrid wave in plasmas are described. A method such as ray-tracing allows the characterization of the dynamics of heating but this method relies on the hypothesis of geometrical optics. Whenever absorption rate is low as it is in Tore-Supra, the hybrid wave undergoes a series of successive reflections on the edge of the plasma before being completely absorbed. These reflections generate an electromagnetic chaos in which geometrical optics hypothesis are no longer valid. A statistical treatment of the Fokker-Planck equation allows the calculation of the mean distribution function of electrons in the plasma submitted to hybrid wave. The electron cyclotron radiation is then deduced and by assuming that plasma behaves like a black body, a theoretical radiative temperature is calculated. The confrontation of this theoretical temperature profile with experimental values allows the validation of this modeling and the estimation of the effects of fast electrons on temperature measurements. (A.C.)

  8. Experimental Observations of In-Situ Secondary Electron Yield Reduction in the PEP-II Particle Accelerator Beam Line

    International Nuclear Information System (INIS)

    Pivi, Mauro

    2010-01-01

    Beam instability caused by the electron cloud has been observed in positron and proton storage rings and it is expected to be a limiting factor in the performance of the positron Damping Ring (DR) of future Linear Colliders (LC) such as ILC and CLIC. To test a series of promising possible electron cloud mitigation techniques as surface coatings and grooves, in the Positron Low Energy Ring (LER) of the PEP-II accelerator, we have installed several test vacuum chambers including (i) a special chamber to monitor the variation of the secondary electron yield of technical surface materials and coatings under the effect of ion, electron and photon conditioning in situ in the beam line; (ii) chambers with grooves in a straight magnetic-free section; and (iii) coated chambers in a dedicated newly installed 4-magnet chicane to study mitigations in a magnetic field region. In this paper, we describe the ongoing R and D effort to mitigate the electron cloud effect for the LC damping ring, focusing on the first experimental area and on results of the reduction of the secondary electron yield due to in situ conditioning.

  9. Ab initio study of low-energy electron collisions with ethylene

    International Nuclear Information System (INIS)

    Trevisan, C.S.; Orel, A.E.; Rescigno, T.N.

    2003-01-01

    We present the results of an investigation of elastic electron scattering by ethylene C 2 H 4 with incident electron energies ranging from 0.5 to 20 eV, using the complex Kohn variational method. These fully ab initio calculations accurately reproduce experimental angular differential cross sections at energies below 3 eV. Low-energy electron scattering by ethylene is sensitive to the inclusion of electronic correlation and target-distortion effects. We therefore report results that describe the dynamic polarization of the target by the incident electron and involve calculations over a range of different geometries, including the effects of nuclear motion in the resonant 2 B 2g symmetry with an adiabatic nuclei treatment of the C-C stretch mode. The inclusion of dynamic polarization and the effect of nuclear motion are equally critical in obtaining accurate results. The calculated cross sections are compared with recent experimental measurements

  10. Design and experimental results of a new electron gun using a magnetic multipole plasma generator

    International Nuclear Information System (INIS)

    Tanaka, S.; Yokoyama, K.; Akiba, M.; Araki, M.; Dairaku, M.; Inoue, T.; Mizuno, M.; Okumura, Y.; Ohara, Y.; Seki, M.; Watanabe, K.

    1991-01-01

    A new electron gun utilizing a magnetic multipole plasma generator was designed and fabricated as the heat source of the high heat flux test facility, called JEBIS (JAERI electron beam irradiation stand). By changing the acceleration grids, this electron gun is able to produce a pencil to a sheetlike electron beams up to 4 A at 100 keV for 1 ms to continuous mode. In this electron gun, magnetic lens system is not adopted to focus the electron beam, but the space charge neutralization effect by the beam plasma produced downstream of the electron gun is utilized to prevent the blow-up of the electron beam. In addition, high permeability metal is embedded in the first and the second grids to magnetically shield the earth field and the stray field from the beam bending magnet. It was experimentally demonstrated that wide range of heat flux from 0.2 MW/m 2 to over 2000 MW/m 2 can be realized at the test sample position about 1.7 m downstream of the electron gun

  11. Experimental comparison between different configurations of PCM based heat sinks for cooling electronic components

    International Nuclear Information System (INIS)

    Gharbi, Salma; Harmand, Souad; Jabrallah, Sadok Ben

    2015-01-01

    The thermal control of electronic components is aimed at ensuring their use in a temperature range compatible with their performances. This paper presents an experimental study of the behavior of phase change materials (PCMs) as the cooling system for electronic devices. Four configurations are used to control the increase in the system temperature: pure PCM, PCM in a silicone matrix, PCM in a graphite matrix and pure PCM in a system of fins. Thermo-physical properties of different PCMs are determined and found to be desirable for application in this study. Solid liquid interface visualization and temperature evolution are employed to understand the mechanism of heat transfer during the different stages. Results indicated that the inclusion of PCM can lower component increase temperature and extends twice the critical time of the heat sink. The use of Graphite matrix filled by PCM showed more improvement on system thermal performance than silicon matrix. Also, for the same fraction of copper, it was found that incorporating long copper fins with suitable spacing into PCM, can enhance heat distribution into PCM leading to longer remain component temperature below the critical limit. This work therefore shows that the combination of PCM and long, well-spaced fins presents an effective means for thermal control of electronic devices. - Highlights: • Study on thermal performance of different PCM based heat sink in electronic cooling. • Examination of heat transfer mechanism into heat sink for different conditions. • Graphite matrix shows more efficiency than silicon. • Inclusion PCM can reduce temperature increasing. • Heat sink with longer well spaced fins can extend longer the critical time

  12. Experimental techniques for the study of radiation damage in metals and alloys

    International Nuclear Information System (INIS)

    Novion, C.H. de.

    1983-06-01

    In this review, one presents the main experimental techniques used to study point defects and defect clusters introduced by irradiation in metals and alloys; emphasis will be put on some recent techniques. In particular, the studies allowing to analyse the very small agglomerates of point defects (Huang and small angle scattering, positron annihilation, electron microscopy) will be compared [fr

  13. November 2013 Analysis of High Energy Electrons on the Japan Experimental Module (JEM: Kibo)

    Science.gov (United States)

    Badavi, Francis F.; Matsumoto, Haruhisa; Koga, Kiyokazu; Mertens, Christopher J.; Slaba, Tony C.; Norbury, John W.

    2015-01-01

    Albedo (precipitating/splash) electrons, created by galactic cosmic rays (GCR) interaction with the upper atmosphere move upwards away from the surface of the earth. In the past validation work these particles were often considered to have negligible contribution to astronaut radiation exposure on the International Space Station (ISS). Estimates of astronaut exposure based on the available Computer Aided Design (CAD) models of ISS consistently underestimated measurements onboard ISS when the contribution of albedo particles to exposure were neglected. Recent measurements of high energy electrons outside ISS Japan Experimental Module (JEM) using Exposed Facility (EF), Space Environment Data Acquisition Equipment - Attached Payload (SEDA-AP) and Standard DOse Monitor (SDOM), indicates the presence of high energy electrons at ISS altitude. In this presentation the status of these energetic electrons is reviewed and mechanism for the creation of these particles inside/outside South Atlantic Anomaly (SAA) region explained. In addition, limited dosimetric evaluation of these electrons at 600 MeV and 10 GeV is presented.

  14. Electron and impurity transport studies in the TCV Tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, D.

    2013-05-15

    In this thesis electron and impurity transport are studied in the Tokamak à Configuration Variable (TCV) located at CRPP-EPFL in Lausanne. Understanding particle transport is primordial for future nuclear fusion power plants. Modeling of experiments in many specific plasma scenarios can help to understand the common elements of the physics at play and to interpret apparently contradictory experiments on the same machine and across different machines. The first part of this thesis deals with electron transport in TCV high confinement mode plasmas. It was observed that the electron density profile in these plasmas flatten when intense electron heating is applied, in contrast to observations on other machines where the increase of the profile peakedness was reported. It is shown with quasi-linear gyrokinetic simulations that this effect, usually interpreted as collisionality dependence, stems from the combined effect of many plasma parameters. The influence of the collisionality, electron to ion temperature ratio, the ratio of temperature gradients, and the Ware-pinch are studied with detailed parameter scans. It is shown that the complex interdependence of the various plasma parameters is greatly simplified when the simulation results are interpreted as a function of the average frequency of the main modes contributing to radial transport. In this way the model is able to explain the experimental results. It was also shown that the same basic understanding is at play in L-modes, H-modes and electron internal transport barriers. The second part of the thesis is devoted to impurity transport. A multi-purpose gas injection system is developed, commissioned and calibrated. It is shown that the system is capable of massive gas injections to provoke disruptions and delivering small puffs of gaseous impurities for perturbative transport experiments. This flexible tool is exploited in a series of impurity transport measurements with argon and neon injections. The impurities

  15. Electron and impurity transport studies in the TCV Tokamak

    International Nuclear Information System (INIS)

    Wagner, D.

    2013-05-01

    In this thesis electron and impurity transport are studied in the Tokamak à Configuration Variable (TCV) located at CRPP-EPFL in Lausanne. Understanding particle transport is primordial for future nuclear fusion power plants. Modeling of experiments in many specific plasma scenarios can help to understand the common elements of the physics at play and to interpret apparently contradictory experiments on the same machine and across different machines. The first part of this thesis deals with electron transport in TCV high confinement mode plasmas. It was observed that the electron density profile in these plasmas flatten when intense electron heating is applied, in contrast to observations on other machines where the increase of the profile peakedness was reported. It is shown with quasi-linear gyrokinetic simulations that this effect, usually interpreted as collisionality dependence, stems from the combined effect of many plasma parameters. The influence of the collisionality, electron to ion temperature ratio, the ratio of temperature gradients, and the Ware-pinch are studied with detailed parameter scans. It is shown that the complex interdependence of the various plasma parameters is greatly simplified when the simulation results are interpreted as a function of the average frequency of the main modes contributing to radial transport. In this way the model is able to explain the experimental results. It was also shown that the same basic understanding is at play in L-modes, H-modes and electron internal transport barriers. The second part of the thesis is devoted to impurity transport. A multi-purpose gas injection system is developed, commissioned and calibrated. It is shown that the system is capable of massive gas injections to provoke disruptions and delivering small puffs of gaseous impurities for perturbative transport experiments. This flexible tool is exploited in a series of impurity transport measurements with argon and neon injections. The impurities

  16. Theoretical study of electronic absorption spectroscopy of propadienylidene molecule vis-â-vis the observed diffuse interstellar bands

    International Nuclear Information System (INIS)

    Reddy, Samala Nagaprasad; Mahapatra, S.

    2012-01-01

    Highlights: ► Theoretical study of spectroscopy and dynamics of electronically excited l-C 3 H 2 . ► Construction of ab initio electronic potential energy and diabatic coupling surfaces. ► First principles study of nuclear dynamics on excited electronic states. ► Findings reveal l-C 3 H 2 is a potential molecular carrier of diffuse interstellar bands. ► Electronically excited l-C 3 H 2 decays by ultrafast nonradiative internal conversion. -- Abstract: Observation of broad and diffuse interstellar bands (DIBs) at 4881 Å and 5440 Å assigned to the optical absorption spectrum of Y-shaped propadienylidene (H 2 C=C=C:) molecule is theoretically examined in this paper. This molecule apparently absorbs in the same wavelength region as the observed DIBs and was suggested to be a potential carrier of these DIBs. This assignment mostly relied on the experimental data from radioastronomy and laboratory measurements. Motivated by these available experimental data we attempt here a theoretical study and investigate the detailed electronic structure and nuclear dynamics underlying the electronic absorption bands of propadienylidene molecule. Our results show that this molecule indeed absorbs in the wavelength region of the recorded DIBs. Strong nonadiabatic coupling between its energetically low-lying electronic states plays major role, initiates ultrafast internal conversion and contributes to the spectral broadening. Theoretical findings are finally compared with the available experimental and theoretical data and discussed in connection with the recorded DIBs.

  17. Study of suprathermal electron transport in solid or compressed matter for the fast-ignitor scheme

    International Nuclear Information System (INIS)

    Perez, F.

    2010-01-01

    The inertial confinement fusion (ICF) concept is widely studied nowadays. It consists in quickly compressing and heating a small spherical capsule filled with fuel, using extremely energetic lasers. Since approximately 15 years, the fast-ignition (FI) technique has been proposed to facilitate the fuel heating by adding a particle beam - electrons generated by an ultra-intense laser - at the exact moment when the capsule compression is at its maximum. This thesis constitutes an experimental study of these electron beams generated by picosecond-scale lasers. We present new results on the characteristics of these electrons after they are accelerated by the laser (energy, divergence, etc.) as well as their interaction with the matter they pass through. The experimental results are explained and reveal different aspects of these laser-accelerated fast electrons. Their analysis allowed for significant progress in understanding several mechanisms: how they are injected into solid matter, how to measure their divergence, and how they can be automatically collimated inside compressed matter. (author) [fr

  18. Study of electron beams within ISTTOK tokamak by means of a multi-channel Cherenkov detector; their correlation with hard X-rays

    Energy Technology Data Exchange (ETDEWEB)

    Jakubowski, L., E-mail: Lech.Jakubowski@ipj.gov.p [Andrzej Soltan Institute for Nuclear Studies, 05-400 Otwock-Swierk (Poland); Malinowski, K.; Sadowski, M.J.; Zebrowski, J. [Andrzej Soltan Institute for Nuclear Studies, 05-400 Otwock-Swierk (Poland); Plyusnin, V.V. [Association Euratom/IST, Instituto de Plasmas e Fusao Nuclear, Instituto Superior Tecnico, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Rabinski, M. [Andrzej Soltan Institute for Nuclear Studies, 05-400 Otwock-Swierk (Poland); Fernandes, H.; Silva, C.; Duarte, P. [Association Euratom/IST, Instituto de Plasmas e Fusao Nuclear, Instituto Superior Tecnico, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Jakubowski, M.J. [Andrzej Soltan Institute for Nuclear Studies, 05-400 Otwock-Swierk (Poland)

    2010-11-11

    The paper describes experimental studies of electron beams emitted from a plasma torus within the ISTTOK tokamak, which were performed by means of a new four-channel detector of the Cherenkov type. A range of electron energy was estimated. There were also measured hard X-rays, and their correlation with the fast run-away electron beams was investigated experimentally.

  19. Theory of local and global processes which affect solar wind electrons. 2. Experimental support

    International Nuclear Information System (INIS)

    Scudder, J.D.; Olbert, S.

    1979-01-01

    We have extended the theoretical considerations of Scudder and Olbert (1979) (hereafter called paper 1) to show from the microscopic characteristics of the Coulomb cross section that there are three natural subpopulations for plasma electrons: the subthermals with local kinetic energy E 7kT/sub c/. We present experimental support from three experimental groups on three different spacecraft over a radial range in the interplanetary medium for the five interrelations projected in paper 1 between solar wind electron properties and changes in the interplanetary medium: (1) subthermals respond primarily to local changes (compressions and rarefactions) in stream dynamics: (2) the extrathermal fraction of the ambient electron density should be anticorrelated with the asymptotic bulk speed; (3) the extrathermal 'temperature' should be anticorrelated with the local wind speed at 1 AU; (4) the heat flux carried by electrons should be anticorrelated with the local bulk speed; and (5) the extrathermal differential 'temperature' should be nearly independent of radius within 1 Au. From first principles and the spatial inhomogeneity of the plasma we show that the velocity dependence of Coulomb collisions in the solar wind plasmaproduces a bifurcation in the solar wind electron distribution function at a transition energy E*. This energy is theoretically shown to scale with the local thermal temperature as E*(r) approx. =GAMMAkT/sub c/(r). This scaling is observationally supported over the radial range from 0.45 to 0.9 AU and at 1 AU. The extrathermals, defined on the basis of Coulomb collisions, are synonymous with the subpopulation previously labeled in the literature as the 'halo' or 'hot' component

  20. Numerical modelling and experimental study of liquid evaporation during gel formation

    Science.gov (United States)

    Pokusaev, B. G.; Khramtsov, D. P.

    2017-11-01

    Gels are promising materials in biotechnology and medicine as a medium for storing cells for bioprinting applications. Gel is a two-phase system consisting of solid medium and liquid phase. Understanding of a gel structure evolution and gel aging during liquid evaporation is a crucial step in developing new additive bioprinting technologies. A numerical and experimental study of liquid evaporation was performed. In experimental study an evaporation process of an agarose gel layer located on Petri dish was observed and mass difference was detected using electronic scales. Numerical model was based on a smoothed particle hydrodynamics method. Gel in a model was represented as a solid-liquid system and liquid evaporation was modelled due to capillary forces and heat transfer. Comparison of experimental data and numerical results demonstrated that model can adequately represent evaporation process in agarose gel.

  1. Experimental Route to Scanning Probe Hot Electron Nanoscopy (HENs) Applied to 2D Material

    KAUST Repository

    Giugni, Andrea

    2017-06-09

    This paper presents details on a new experimental apparatus implementing the hot electron nanoscopy (HENs) technique introduced for advanced spectroscopies on structure and chemistry in few molecules and interface problems. A detailed description of the architecture used for the laser excitation of surface plasmons at an atomic force microscope (AFM) tip is provided. The photogenerated current from the tip to the sample is detected during the AFM scan. The technique is applied to innovative semiconductors for applications in electronics: 2D MoS2 single crystal and a p-type SnO layer. Results are supported by complementary scanning Kelvin probe microscopy, traditional conductive AFM, and Raman measurements. New features highlighted by HEN technique reveal details of local complexity in MoS2 and polycrystalline structure of SnO at nanometric scale otherwise undetected. The technique set in this paper is promising for future studies in nanojunctions and innovative multilayered materials, with new insight on interfaces.

  2. Ab initio study of dissociative attachment of low-energy electrons to F2

    International Nuclear Information System (INIS)

    Hazi, A.U.; Orel, A.E.; Rescigno, T.N.

    1981-01-01

    Adiabatic-nuclei resonance theory has been applied to the study of dissociative attachment of low-energy electrons to F 2 . Stieltjes moment theory was used to derive fixed-nuclei electronic resonance parameters from large scale configuration-interaction calculations on F 2 and F 2 - . Dissociative attachment cross sections are reported for the four lowest vibrational levels of F 2 and compared to available experimental data

  3. The transition radiation. 2. experimental study of the optical transition radiation

    International Nuclear Information System (INIS)

    Couillaud, Ch.; Haouat, G.; Seguin, S.; Striby, S.

    1999-01-01

    Optical-transition-radiation-based diagnostics have been widely used for many years on electron accelerators in order to measure beam energy and transverse and longitudinal emittances. These diagnostics are very attractive for high brightness electron beams used as drivers for radiation sources. Such diagnostics have been performed on the ELSA facility (18 MeV electron energy, 100 A peak current) using both a single interface and an OTR-Wartski interferometer. We present the accelerator, the experimental set-up and the method for analyzing the OTR angular distribution. Then, the experimental results are described and compared with those from the three gradient method. In addition, we present a beam energy measurement using OTR interferogram analysis. (author)

  4. Electronic processes in TTF-derived complexes studied by IR spectroscopy

    Science.gov (United States)

    Graja, Andrzej

    2001-09-01

    We focus our attention on the plasma-edge-like dispersion of the reflectance spectra of the selected bis(ethylenodithio)tetrathiafulvalene (BEDT-TTF)-derived organic conductors. The standard procedure to determine the electron transport parameters in low-dimensional organic conductors consists of fitting the appropriate theoretical models with the experimental reflectance data. This procedure provides us with basic information like plasma frequency, the optical effective mass of charge carriers, their number, mean free path and damping constant. Therefore, it is concluded that the spectroscopy is a powerful tool to study the electronic processes in conducting organic solids.

  5. Study on the compensation of electron beam space charge in facilittes with electron cooling

    International Nuclear Information System (INIS)

    Dikanskij, N.S.; Kudelajnen, V.I.; Parkhomchuk, V.V.; Pestrikov, D.V.

    1981-01-01

    The results of experimental investigations of a compensated electron beam on the NAP-M facility are presented. The electron beam is compensated by electrostatic plugs preventing ion leakage along the beam. Cut-off electrodes have the shape of cutted cylinders encircling the electron beam. To eliminate electron accumulation around the plugs one of the electrodes has a zero potential, which results in formation of an transverse electric field causing ionization electron drift in the transverse direction to the electric and magnetic fields. The effect of wave damping, in the compensated beam is observed, that demonstrates the possibility of gaining great current densities in long compensated beams necessary for antiproton storage. For the NAP-M at the 10 10 cm/s electron velocity, 300 cm length of ion column, and 1 kOe field intensity the threshold beam current density is 0.96 A/cm 2 [ru

  6. Studies of electron correlation in the photoionization process

    International Nuclear Information System (INIS)

    Rosenberg, R.A.

    1979-03-01

    Electron correlation is a result of the interaction of two or more electrons confined in a region of space, and may conveniently be treated under the formalism of configuration interaction (CI). Photoionization provides a rather direct experimental method for studying CI. The types of CI involved in the photoionization process can be divided into three categories: initial-state configuration interaction (ISCI), final-ionic-state configuration interaction (FISCI), and continuum-state configuration interaction (CSCI). The photoelecton spectroscopy of Ba, Sm, Eu, and Yb was studied using both HeI (22.22 eV) and NeI (16.85 eV) radiation. Satellite structure observed in these spectra using NeI (and for Yb, HeI also) radiation could be satisfactorily explained by ISCI alone. The HeI spectra of Sm, Eu, and, in particular, Ba showed dramatic changes in the satellite population which could only be explained by autoionization, a special form of CSCI. The detailed nature of this mechanism was explored in Ba with synchrotron radiation. It was found that the autoionizing level decays preferentially via an Auger-type mechanism. Further insight into autoionization was gained in the electron impact/ejected electron spectra of Ba (5p 6 6s 2 ) and Yb (5p 6 4f 14 6s 2 ). Autoionizing levels excited above the first (5p) -1 threshold decayed primarily in a two-step Auger process, leading to a relatively large number of doubly charged ions. For autoionizing states below the (5p) -1 limit, decay appears to go to ground and excited states of the singly charged ion. The first experimental determination of the lifetime of the XeII 5s5p 6 2 S/sub 1/2/ state yielded a value of 34.4(6) ns. Reasonable agreement with theory could only be reached by including both FISCI and relativistic effects in calculating the lifetime. 173 references, 43 figures, 10 tables

  7. Experimental and theoretical studies of 3-benzyloxy-2-nitropyridine

    Science.gov (United States)

    Sun, Wenting; Cui, Yu; Liu, Huimin; Zhao, Haitao; Zhang, Wenqin

    2012-10-01

    The structure of 3-benzyloxy-2-nitropyridine has been investigated both experimentally and theoretically. The X-ray crystallography results show that the nitro group is tilted out of the pyridine ring plane by 66.4(4)°, which is mainly attributed to the electron-electron repulsions of the lone pairs in O atom of the 3-benzyloxy moiety with O atom in nitro group. An interesting centrosymmetric π-stacking molecular pair has been found in the crystalline state, which results in the approximate coplanarity of the pyridine ring with the benzene ring. The calculated results show that the dihedral angle between the nitro group and pyridine ring from the X3LYP method is much closer to the experimental data than that from the M06-2X one. The existing two conformational isomers of 3-benzyloxy-2-nitropyridine with equal energy explain well the disorder of the nitro group at room temperature. In addition, the vibrational frequencies are also calculated by the X3LYP and M06-2X methods and compared with the experimental results. The prediction from the X3LYP method coincides with the locations of the experimental frequencies well.

  8. Elise: a new facility for unprecedented experimental nuclear fission studies

    International Nuclear Information System (INIS)

    Taieb, J.; Belier, G.; Chatillon, A.; Granier, T.; Kelic, A.; Ricciardi, V.; Schmidt, K.H.; Voss, B.; Coste-Delclaux, M.; Diop, C.; Jouanne, C.; Schmitt, C.; Aiche, M.; Czajkowski, S.; Jurado, B.; Audouin, L.; Peyre, J.; Rosier, P.; Tassan-Got, L.; Bertoumieux, E.; Dore, D.; Dupont, E.; Letourneau, A.; Panebianco, S.

    2009-01-01

    A novel experimental program aiming to study the properties of fragments and neutrons emitted in the fission process has been initiated. The experiment will be held at the ELISe electron-ion collider to be constructed at GSI, Darmstadt in the framework of the FAIR extension of the facility. The experiment will take advantage of the inverse kinematics allowing, in particular, a total mass and charge resolution for all fission fragments. (authors)

  9. Studies on electronic structure of GaN(0001) surface

    CERN Document Server

    Xie Chang Kun; Xu Fa Qiang; Deng Rui; Liu Feng; Yibulaxin, K

    2002-01-01

    An electronic structure investigation on GaN(0001) is reported. The authors employ a full-potential linearized augmented plane-wave (FPLAPW) approach to calculate the partial density of state, which is in agreement with previous experimental results. The effects of the Ga3d semi-core levels on the electronic structure of GaN are discussed. The valence-electronic structure of the wurtzite GaN(0001) surface is investigated using synchrotron radiation excited angle-resolved photoemission spectroscopy. The bulk bands dispersion along GAMMA A direction in the Brillouin zones is measured using normal-emission spectra by changing photon-energy. The band structure derived from authors' experimental data is compared well with the results of authors' FPLAPW calculation. Furthermore, off-normal emission spectra are also measured along the GAMMA K and GAMMA M directions. Two surface states are identified, and their dispersions are characterized

  10. Study of warm dense plasma electronic dynamics by optical interferometry

    International Nuclear Information System (INIS)

    Deneuville, F.

    2013-01-01

    The Warm Dense Matter (WDM) regime is characterised by a density close to the solid density and an electron temperature close to the Fermi temperature. In this work, the nonequilibrium Warm Dense Matter is studied during the solid to liquid phase transition induced by an ultra short laser interacting with a solid. A 30 femtosecond time resolution pump-probe experiment (FDI) is set up, yielding to the measurement of the heated sample complex reflectivity for both S and P polarisation. We have determined a criterion based on the measured reflectivities, which permits to control the interface shape of the probed matter. For pump laser fluences around 1 J/cm 2 , the hydrodynamics of the heated matter is studied and experimental results are compared to the two-temperatures code ESTHER. Furthermore, the evolution of the dielectric function at 800 nm and 400 nm is inferred from our measurements on a sub-picosecond time-scale. Within the Drude-Lorentz model for the conduction electrons, the dielectric function yields information such as ionisation state, electronic temperature and electron collision frequency. (author) [fr

  11. Experimental study of rf pulsed heating

    CERN Document Server

    Laurent, L; Nantista, C; Dolgashev, V; Higashi, Y; Aicheler, M; Tantawi, S; Wuensch, W

    2011-01-01

    Cyclic thermal stresses produced by rf pulsed heating can be the limiting factor on the attainable reliable gradients for room temperature linear accelerators. This is especially true for structures that have complicated features for wakefield damping. These limits could be pushed higher by using special types of copper, copper alloys, or other conducting metals in constructing partial or complete accelerator structures. Here we present an experimental study aimed at determining the potential of these materials for tolerating cyclic thermal fatigue due to rf magnetic fields. A special cavity that has no electric field on the surface was employed in these studies. The cavity shape concentrates the magnetic field on one flat surface where the test material is placed. The materials tested in this study have included oxygen free electronic grade copper, copper zirconium, copper chromium, hot isostatically pressed copper, single crystal copper, electroplated copper, Glidcop (R), copper silver, and silver plated co...

  12. Theoretical study of the lowest-lying electronic states of Aluminium monoiodide

    International Nuclear Information System (INIS)

    Taher, F.; Kabbani, A.; Ani-El Houte, W.

    2004-01-01

    Full text.The spectroscopic study of Aluminium monohalides, especially the Aluminium monoiodide, is important for monitoring such species in high temperature fast-flow reactors. Theoretical calculations of AlI are not available, whereas several studies have been done for the other aluminium monohalides. In this work, CAS-SCF/MRCI calculations are performed for the lowest-lying electronic states of AlI in a range of internuclear distance between 2.30 A and 2.80 A. Ab-initio calculations have been effectuated by using the computational chemistry program Molpro. The basis set used in this study for aluminium atom is that used by Langhoff for aluminium monohalides, of contractions using atomic natural orbitals and a pseudopotential is used for iode. Accurate theoretical spectroscopic constants and potential curves are obtained for the ground state X 1 Σ + and the first excited states a 3 Π and A 1 Π. The calculated values of Te, ωe, ωexe and re of these states are compatible with the experimental results. An ordering of states is represented for the lowest five predicted singlet and lowest five predicted triplet states. These results provide a big support to determine the analogy in the ordering of the electronic states in AlF, AlBr and AlI respectively at lower energies. These theoretical results identify a set of electronic singlet and triplet states unobserved experimentally

  13. Oblique propagation of electron thermal modes below the electron plasma frequency without boundary effects

    International Nuclear Information System (INIS)

    Ohnuma, T.; Watanabe, T.; Sanuki, H.

    1981-08-01

    Propagation characteristics and refractive effects of an oblique electron thermal mode without boundary effects below the electron plasma frequency are studied experimentally and theoretically in an inhomogeneous magnetized plasma. The behavior of this mode observed experimentally was confirmed by the theoretical analysis based on a new type of ray theory. (author)

  14. Empirical pseudo-potential studies on electronic structure

    Indian Academy of Sciences (India)

    Theoretical investigations of electronic structure of quantum dots is of current interest in nanophase materials. Empirical theories such as effective mass approximation, tight binding methods and empirical pseudo-potential method are capable of explaining the experimentally observed optical properties. We employ the ...

  15. Dynamic investigation of electron trapping and charge decay in electron-irradiated Al sub 2 O sub 3 in a scanning electron microscope: Methodology and mechanisms

    CERN Document Server

    Fakhfakh, S; Belhaj, M; Fakhfakh, Z; Kallel, A; Rau, E I

    2002-01-01

    The charging and discharging of polycrystalline Al sub 2 O sub 3 submitted to electron-irradiation in a scanning electron microscope (SEM) are investigated by means of the displacement current method. To circumvent experimental shortcomings inherent to the use of the basic sample holder, a redesign of the latter is proposed and tests are carried out to verify its operation. The effects of the primary beam accelerating voltage on charging, flashover and discharging phenomena during and after electron-irradiation are studied. The experimental results are then analyzed. In particular, the divergence between the experimental data and those predicted by the total electron emission yield approach (TEEYA) is discussed. A partial discharge was observed immediately after the end of the electron-irradiation exposure. The experimental data suggests, that the discharge is due to the evacuation to the ground, along the insulator surface, of released electrons from shallow traps at (or in the close vicinity of) the insulat...

  16. Study of Cr52 and Ca40 nuclei by electron scattering

    International Nuclear Information System (INIS)

    Blum, Daniel

    1966-01-01

    As high energy electron scattering is a powerful mean to study nuclear structure, this research thesis first reports and comments results obtained while taking the Born approximation into account, and which are useful to interpret electron scattering experiments. The author describes how nucleus charge distribution parameters are obtained from these results of elastic scattering, and then addresses the case of inelastic scattering. Three nuclear models are presented. Then, after a brief presentation of the characteristics of the experimental installation, the author describes how raw results are processed to obtain cross sections, and discusses errors. The last parts address the study of chromium 52 and calcium 40 nuclei

  17. The importance of accurate adiabatic interaction potentials for the correct description of electronically nonadiabatic vibrational energy transfer: A combined experimental and theoretical study of NO(v = 3) collisions with a Au(111) surface

    Energy Technology Data Exchange (ETDEWEB)

    Golibrzuch, Kai; Shirhatti, Pranav R.; Kandratsenka, Alexander; Wodtke, Alec M.; Bartels, Christof [Institute for Physical Chemistry, Georg August University of Göttingen, Göttingen 37077 (Germany); Max Planck Institute for Biophysical Chemistry, Göttingen 37077 (Germany); Rahinov, Igor [Department of Natural Sciences, The Open University of Israel, Ra' anana 4353701 (Israel); Auerbach, Daniel J. [Institute for Physical Chemistry, Georg August University of Göttingen, Göttingen 37077 (Germany); Max Planck Institute for Biophysical Chemistry, Göttingen 37077 (Germany); Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106 (United States)

    2014-01-28

    We present a combined experimental and theoretical study of NO(v = 3 → 3, 2, 1) scattering from a Au(111) surface at incidence translational energies ranging from 0.1 to 1.2 eV. Experimentally, molecular beam–surface scattering is combined with vibrational overtone pumping and quantum-state selective detection of the recoiling molecules. Theoretically, we employ a recently developed first-principles approach, which employs an Independent Electron Surface Hopping (IESH) algorithm to model the nonadiabatic dynamics on a Newns-Anderson Hamiltonian derived from density functional theory. This approach has been successful when compared to previously reported NO/Au scattering data. The experiments presented here show that vibrational relaxation probabilities increase with incidence energy of translation. The theoretical simulations incorrectly predict high relaxation probabilities at low incidence translational energy. We show that this behavior originates from trajectories exhibiting multiple bounces at the surface, associated with deeper penetration and favored (N-down) molecular orientation, resulting in a higher average number of electronic hops and thus stronger vibrational relaxation. The experimentally observed narrow angular distributions suggest that mainly single-bounce collisions are important. Restricting the simulations by selecting only single-bounce trajectories improves agreement with experiment. The multiple bounce artifacts discovered in this work are also present in simulations employing electronic friction and even for electronically adiabatic simulations, meaning they are not a direct result of the IESH algorithm. This work demonstrates how even subtle errors in the adiabatic interaction potential, especially those that influence the interaction time of the molecule with the surface, can lead to an incorrect description of electronically nonadiabatic vibrational energy transfer in molecule-surface collisions.

  18. An experimental investigation of wastewater treatment using electron beam irradiation

    Science.gov (United States)

    Emami-Meibodi, M.; Parsaeian, M. R.; Amraei, R.; Banaei, M.; Anvari, F.; Tahami, S. M. R.; Vakhshoor, B.; Mehdizadeh, A.; Fallah Nejad, N.; Shirmardi, S. P.; Mostafavi, S. J.; Mousavi, S. M. J.

    2016-08-01

    Electron beam (EB) is used for disinfection and treatment of different types of sewage and industrial wastewater. However, high capital investment required and the abundant energy consumed by this process raise doubts about its cost-effectiveness. In this paper, different wastewaters, including two textile sewages and one municipal wastewater are experimentally studied under different irradiation strategies (i.e. batch, 60 l/min and 1000 m3/day) in order to establish the reliability and the optimum conditions for the treatment process. According to the results, EB improves the efficiency of traditional wastewater treatment methods, but, for textile samples, coagulation before EB irradiation is recommended. The cost estimation of EB treatment compared to conventional methods shows that EB has been more expensive than chlorination and less expensive than activated sludge. Therefore, EB irradiation is advisable if and only if conventional methods of textile wastewater treatment are insufficient or chlorination of municipal wastewater is not allowed for health reasons. Nevertheless, among the advanced oxidation processes (AOP), EB irradiation process may be the most suitable one in industrial scale operations.

  19. Experimental investigation on the development characteristics of initial electrons in a gas pressurized closing switch under DC voltage

    Science.gov (United States)

    Rongxiao, ZHAI; Mengtong, QIU; Weixi, LUO; Peitian, CONG; Tao, HUANG; Jiahui, YIN; Tianyang, ZHANG

    2018-04-01

    As one of the most important elements in linear transformer driver (LTD) based systems, the gas pressurized closing switches are required to operate with a very low prefire probability during the DC-charging process to ensure reliable operation and stable output of the whole pulsed power system. The most direct and effective way to control the prefire probability is to select a suitable working coefficient. The study of the development characteristics of the initially generated electrons is useful for optimizing the working coefficient and improving the prefire characteristic of the switches. In this paper an ultraviolet pulsed laser is used to generate initial electrons inside the gap volume. A current measuring system is used to measure the time-dependent current generated by the growth of the initial electrons so as to study the development characteristics of the electrons under different working coefficients. Experimental results show that the development characteristics of the initial electrons are influenced obviously by the working coefficient. With the increase of the working coefficient, the development degree of the electrons increases consequently. At the same times, there is a threshold of working coefficient which produces the effect of ionization on electrons. The range of the threshold has a slow growth but remains close to 65% with the gas pressure increase. When the working coefficient increases further, γ processes are starting to be generated inside the gap volume. In addition, an optimal working coefficient beneficial for improving the prefire characteristic is indicated and further tested.

  20. Positron lifetime studies of electron irradiated copper

    International Nuclear Information System (INIS)

    Hadnagy, T.D.

    1976-01-01

    Single-crystal copper was irradiated with 4.5-MeV electrons producing simple Frenkel defects as well as a significant concentration of divacancies. Mean positron lifetime characteristics, which are sensitive to the presence of vacancies and multivacancies in copper, was monitored after isochronal anneals between 80 and 800 0 K to determine the relative change of characteristic mean lifetimes and their associated intensities. Also a study of the dependence of the mean positron lifetime on the total electron fluence was made and compared with existing theories relating these lifetimes to vacancy or multivacancy concentrations. Numerical data from curve fitting procedures using a conventional trapping model for defect-induced changes in positron lifetimes indicate that upon irradiation with 4.5-MeV electrons at 80 0 K, about 8 percent of the defects produced are divacancy units. Divacancy units appear to be several times more effective in trapping positrons than are monovacancies. Further, the experimental data suggest that the stage III annealing processes in electron-irradiated copper most probably involve the motion and removal of both monovacancies and divacancies. A conglomerate (multivacancy) unit appears to exist as a stable entity even after annealing procedures are carried out at temperatures slightly above the stage III region. Such a stable unit could serve as a nucleation center for the appearance of voids

  1. Experimental study of fast electron transport and of the propagation of shock waves generated by laser in the framework of inertial fusion

    International Nuclear Information System (INIS)

    Sakaki, T.

    2016-01-01

    This document presents 3 experiments carried out within the framework of inertial fusion. The first experiment was devoted to the study of fast electron beam transport in a compressed target. The implosion of the target with a cylindrical geometry was carried out with the GEKKO XII laser facility (ILE Osaka, Japan). The fast electron beam was generated by the LFEX laser (∼10"1"9 W/cm"2) and its propagation through the compressed cylinder was observed with several X-ray diagnostics. This experiment showed the guiding effect of the electron beam resulting from self-generated magnetic fields. Furthermore, the results of this experiment were in good agreement with numerical simulations. Two other experiments were performed to study the propagation of strong shock waves created by lasers in a plasma. They were carried out with different laser systems. In the first experiment with the Gekko XII laser, we observed the creation and the propagation of two successive shock waves in an ablation plasma in CH and Be. The objective of characterizing the amplification of a transmitted shock by the collision of two counter-propagating shocks has been partially realized. The comparison of the experimental results with the hydrodynamic simulations enabled us to confirm an amplification of the shock by a factor 2 in pressure in the condition of this experiment. The shot with a Be target allowed the development and validation of the diagnostic method of X-ray radiography for shock wave propagation. The second experiment was performed with PHELIX GSI laser (Darmstadt, Germany). The purpose of this experiment was to study the generation of strong shocks. They were applied to study the equation of state of carbon in the WDM state. The condition of pressure and density for the carbon were obtained by deducing the pressure and the velocity of the shock wave chronometric diagnostics employed in this experiment. In this experiment, diamond was at the metallic liquid phase with a pressure

  2. Reasons for Electronic Cigarette Experimentation and Discontinuation Among Adolescents and Young Adults.

    Science.gov (United States)

    Kong, Grace; Morean, Meghan E; Cavallo, Dana A; Camenga, Deepa R; Krishnan-Sarin, Suchitra

    2015-07-01

    Understanding why young people try and stop electronic cigarette (e-cigarette) use is critical to inform e-cigarette regulatory efforts. We conducted 18 focus groups (N = 127) in 1 middle school (MS), 2 high schools (HSs), and 2 colleges in Connecticut to assess themes related to e-cigarette experimentation and discontinuation. We then conducted surveys to evaluate these identified themes in 2 MSs, 4 HSs, and 1 college (N = 1,175) to explore whether reasons for e-cigarette experimentation and/or discontinuation differed by school level or cigarette smoking status. From the focus groups, we identified experimentation themes (i.e., curiosity, flavors, family/peer influence, easy access, and perceptions of e-cigarettes as "cool" and as a healthier/better alternative to cigarettes) and discontinuation themes (i.e., health concerns, loss of interest, high cost, bad taste, and view of e-cigarettes as less satisfying than cigarettes). The survey data showed that the top reasons for experimentation were curiosity (54.4%), appealing flavors (43.8%), and peer influences (31.6%), and the top reasons for discontinuation were responses related to losing interest (23.6%), perceiving e-cigarettes as "uncool" (16.3%), and health concerns (12.1%). Cigarette smokers tried e-cigarettes because of the perceptions that they can be used anywhere and to quit smoking and discontinued because they were not as satisfying as cigarettes. School level differences were detected. E-cigarette prevention efforts toward youth should include limiting e-cigarette flavors, communicating messages emphasizing the health risks of use, and changing social norms surrounding the use of e-cigarettes. The results should be interpreted in light of the limitations of this study. © The Author 2014. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  3. Contribution to the theoretical and experimental study of the electron-volt effect in N-P junctions

    International Nuclear Information System (INIS)

    Nguyen Van, Dong

    1959-07-01

    The proposed aim of this work is to study the behaviour of a semi-conducting junction under the action of β radiation. These studies were directed on the one hand to direct conversion of the energy radiated by a radioactive source to electric energy usable by means of N-P junctions, and on the other hand to the kinetics of defects produced in the semi-conductor crystals by high energy β rays. In the first part of this work, an attempt has been made to complete the earlier theories of the electron-volt effect in junctions by analysing the effect mathematically. This has led to a single equation containing the electrical and geometric parameters of the semi-conductor and of the junction, and the properties of the incident radiation. Apart from this, the diffusion current of the charge carriers created by the bombardment has been studied in more detail, taking into account all the factors which play a part in the expression of the efficiency of charge collection of a junction. In the second part, where experiments on the irradiation of N-P junctions have been carried out with a 90 Sr- 90 Y source, mention is made of the particular advantages of a gallium arsenide junction capable of operating at relatively high temperatures (in the region of 100 deg. C). The third part presents the study of defects created in a semi-conductor crystal by high-energy β rays, according to the method of electron-volt effect. It is shown here that from a study of the degradation of the short-circuit current of the junction it may be possible to determine the recombination level and the probabilities of electron and hole capture, as from a study of the lifetime decay of minority carriers in a crystal of known type. Experiments on the bombardment of Ge junctions by 2 MeV electrons were performed with a Van de Graaff. Very clear anomalies of the electron-volt effect at 100 deg. K were observed. An attempt was made at interpretation of these anomalies in the junction, taking into account

  4. Electron tunneling in lithium-ammonia solutions probed by frequency-dependent electron spin relaxation studies.

    Science.gov (United States)

    Maeda, Kiminori; Lodge, Matthew T J; Harmer, Jeffrey; Freed, Jack H; Edwards, Peter P

    2012-06-06

    Electron transfer or quantum tunneling dynamics for excess or solvated electrons in dilute lithium-ammonia solutions have been studied by pulse electron paramagnetic resonance (EPR) spectroscopy at both X- (9.7 GHz) and W-band (94 GHz) frequencies. The electron spin-lattice (T(1)) and spin-spin (T(2)) relaxation data indicate an extremely fast transfer or quantum tunneling rate of the solvated electron in these solutions which serves to modulate the hyperfine (Fermi-contact) interaction with nitrogen nuclei in the solvation shells of ammonia molecules surrounding the localized, solvated electron. The donor and acceptor states of the solvated electron in these solutions are the initial and final electron solvation sites found before, and after, the transfer or tunneling process. To interpret and model our electron spin relaxation data from the two observation EPR frequencies requires a consideration of a multiexponential correlation function. The electron transfer or tunneling process that we monitor through the correlation time of the nitrogen Fermi-contact interaction has a time scale of (1-10) × 10(-12) s over a temperature range 230-290 K in our most dilute solution of lithium in ammonia. Two types of electron-solvent interaction mechanisms are proposed to account for our experimental findings. The dominant electron spin relaxation mechanism results from an electron tunneling process characterized by a variable donor-acceptor distance or range (consistent with such a rapidly fluctuating liquid structure) in which the solvent shell that ultimately accepts the transferring electron is formed from random, thermal fluctuations of the liquid structure in, and around, a natural hole or Bjerrum-like defect vacancy in the liquid. Following transfer and capture of the tunneling electron, further solvent-cage relaxation with a time scale of ∼10(-13) s results in a minor contribution to the electron spin relaxation times. This investigation illustrates the great

  5. Electron Tunneling in Lithium Ammonia Solutions Probed by Frequency-Dependent Electron-Spin Relaxation Studies

    Science.gov (United States)

    Maeda, Kiminori; Lodge, Matthew T.J.; Harmer, Jeffrey; Freed, Jack H.; Edwards, Peter P.

    2012-01-01

    Electron transfer or quantum tunneling dynamics for excess or solvated electrons in dilute lithium-ammonia solutions have been studied by pulse electron paramagnetic resonance (EPR) spectroscopy at both X- (9.7 GHz) and W-band (94 GHz) frequencies. The electron spin-lattice (T1) and spin-spin (T2) relaxation data indicate an extremely fast transfer or quantum tunneling rate of the solvated electron in these solutions which serves to modulate the hyperfine (Fermi-contact) interaction with nitrogen nuclei in the solvation shells of ammonia molecules surrounding the localized, solvated electron. The donor and acceptor states of the solvated electron in these solutions are the initial and final electron solvation sites found before, and after, the transfer or tunneling process. To interpret and model our electron spin relaxation data from the two observation EPR frequencies requires a consideration of a multi-exponential correlation function. The electron transfer or tunneling process that we monitor through the correlation time of the nitrogen Fermi-contact interaction has a time scale of (1–10)×10−12 s over a temperature range 230–290K in our most dilute solution of lithium in ammonia. Two types of electron-solvent interaction mechanisms are proposed to account for our experimental findings. The dominant electron spin relaxation mechanism results from an electron tunneling process characterized by a variable donor-acceptor distance or range (consistent with such a rapidly fluctuating liquid structure) in which the solvent shell that ultimately accepts the transferring electron is formed from random, thermal fluctuations of the liquid structure in, and around, a natural hole or Bjerrum-like defect vacancy in the liquid. Following transfer and capture of the tunneling electron, further solvent-cage relaxation with a timescale of ca. 10−13 s results in a minor contribution to the electron spin relaxation times. This investigation illustrates the great potential

  6. Electron-molecule collisions

    International Nuclear Information System (INIS)

    Shimamura, I.; Takayanagi, K.

    1984-01-01

    The study of collision processes plays an important research role in modern physics. Many significant discoveries have been made by means of collision experiments. Based on theoretical, experimental, and computational studies, this volume presents an overview detailing the basic processes of electron-molecule collisions. The editors have collected papers-written by a group of international experts-that consider a diverse range of phenomena occurring in electronmolecule collisions. The volume discusses first the basic formulation for scattering problems and then gives an outline of the physics of electron-molecule collisions. The main topics covered are rotational transitions, vibrational transitions, dissociation of molecules in slow collisions, the electron-molecule collision as a spectroscopic tool for studying molecular electronic structures, and experimental and computational techniques for determining the cross sections. These well-referenced chapters are self-contained and can be read independently or consecutively. Authoritative and up-to-date, Electron-Molecule Collisions is a useful addition to the libraries of students and researchers in the fields of atomic, molecular, and chemical physics, and physical chemistry

  7. Influence of Experimental Conditions on Electronic Tongue Results—Case of Valsartan Minitablets Dissolution

    Directory of Open Access Journals (Sweden)

    Małgorzata Wesoły

    2016-08-01

    Full Text Available A potentiometric electronic tongue was applied to study the release of valsartan from pharmaceutical formulations, i.e., minitablets uncoated and coated with Eudragit E. Special attention was paid to evaluate the influence of medium temperature and composition, as well as to compare the performances of the sensor arrays working in various hydrodynamic conditions. The drug dissolution profiles registered with the ion-sensitive electrodes were compared with standard dissolution tests performed with USP Apparatus 2 (paddle. Moreover, the signal changes of all sensors were processed by principal component analysis to visualize the release modifications, related to the presence of the coating agent. Finally, the importance and influence of the experimental conditions on the results obtained using potentiometric sensor arrays were discussed.

  8. Joint Experimental and Theoretical Study on Vibrational Excitation Cross Sections for Electron Collisions with Diacetylene

    Czech Academy of Sciences Publication Activity Database

    Čurík, Roman; Paidarová, Ivana; Allan, M.; Čársky, Petr

    2014-01-01

    Roč. 118, č. 41 (2014), s. 9734-9744 ISSN 1089-5639 R&D Projects: GA ČR GAP208/11/0452; GA MŠk LD14088 Institutional support: RVO:61388955 Keywords : diacetylenes * electron collision * theoretical study Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.693, year: 2014

  9. Experimental and theoretical studies of cylindrical Hall thrusters

    International Nuclear Information System (INIS)

    Smirnov, Artem; Raitses, Yegeny; Fisch, Nathaniel J.

    2007-01-01

    The Hall thruster is a mature electric propulsion device that holds considerable promise in terms of the propellant saving potential. The annular design of the conventional Hall thruster, however, does not naturally scale to low power. The efficiency tends to be lower and the lifetime issues are more aggravated. Cylindrical geometry Hall thrusters have lower surface-to-volume ratio than conventional thrusters and, thus, seem to be more promising for scaling down. The cylindrical Hall thruster (CHT) is fundamentally different from the conventional design in the way the electrons are confined and the ion space charge is neutralized. The performances of both the large (9-cm channel diameter, 600-1000 W) and miniaturized (2.6-cm channel diameter, 50-300 W) CHTs are comparable with those of the state-of-the-art conventional (annular) design Hall thrusters of similar sizes. A comprehensive experimental and theoretical study of the CHT physics has been conducted, addressing the questions of electron cross-field transport, propellant ionization, plasma-wall interaction, and formation of the electron distribution function. Probe measurements in the harsh plasma environment of the microthruster were performed. Several interesting effects, such as the unusually high ionization efficiency and enhanced electron transport, were observed. Kinetic simulations suggest the existence of the strong fluctuation-enhanced electron diffusion and predict the non-Maxwellian shape of the electron distribution function. Through the acquired understanding of the new physics, ways for further optimization of this means for low-power space propulsion are suggested. Substantial flexibility in the magnetic field configuration of the CHT is the key tool in achieving the high-efficiency operation

  10. Experimental study of a swept reflectometer with a single antenna for plasma density profile measurement

    International Nuclear Information System (INIS)

    Calderon, M.A.G.; Simonet, F.

    1984-12-01

    The feasibility of a swept microwave reflectometer, with one antenna only, for plasma electron density measurement is studied. Experimental results obtained in the laboratory by simulating the plasma with a metallic mirror are presented

  11. New experimental results on electron cooling at COSY-Juelich

    International Nuclear Information System (INIS)

    Dietrich, J.; Maier, R.; Prasuhn, D.; Stein, H.J.; Kobets, A.; Meshkov, I.; Sidorin, A.; Smirnov, A.

    2007-01-01

    Recent results of electron cooling of proton beams at COSY-Juelich are reported. Cooling at an electron energy of 70 keV has been studied for the first time. At the injection energy level of COSY, corresponding to 24.5 keV electron energy, the features of the cooled proton beam at extremely low intensities have been investigated in order to find out whether an ordering of the proton beam can be achieved. Such investigations are motivated by the results of a numerical simulation of the ordering process by the BETACOOL code. (author)

  12. A Combined Theoretical and Experimental Study for Silver Electroplating

    Science.gov (United States)

    Liu, Anmin; Ren, Xuefeng; An, Maozhong; Zhang, Jinqiu; Yang, Peixia; Wang, Bo; Zhu, Yongming; Wang, Chong

    2014-01-01

    A novel method combined theoretical and experimental study for environmental friendly silver electroplating was introduced. Quantum chemical calculations and molecular dynamic (MD) simulations were employed for predicting the behaviour and function of the complexing agents. Electronic properties, orbital information, and single point energies of the 5,5-dimethylhydantoin (DMH), nicotinic acid (NA), as well as their silver(I)-complexes were provided by quantum chemical calculations based on density functional theory (DFT). Adsorption behaviors of the agents on copper and silver surfaces were investigated using MD simulations. Basing on the data of quantum chemical calculations and MD simulations, we believed that DMH and NA could be the promising complexing agents for silver electroplating. The experimental results, including of electrochemical measurement and silver electroplating, further confirmed the above prediction. This efficient and versatile method thus opens a new window to study or design complexing agents for generalized metal electroplating and will vigorously promote the level of this research region.

  13. A Combined Theoretical and Experimental Study for Silver Electroplating

    Science.gov (United States)

    Liu, Anmin; Ren, Xuefeng; An, Maozhong; Zhang, Jinqiu; Yang, Peixia; Wang, Bo; Zhu, Yongming; Wang, Chong

    2014-01-01

    A novel method combined theoretical and experimental study for environmental friendly silver electroplating was introduced. Quantum chemical calculations and molecular dynamic (MD) simulations were employed for predicting the behaviour and function of the complexing agents. Electronic properties, orbital information, and single point energies of the 5,5-dimethylhydantoin (DMH), nicotinic acid (NA), as well as their silver(I)-complexes were provided by quantum chemical calculations based on density functional theory (DFT). Adsorption behaviors of the agents on copper and silver surfaces were investigated using MD simulations. Basing on the data of quantum chemical calculations and MD simulations, we believed that DMH and NA could be the promising complexing agents for silver electroplating. The experimental results, including of electrochemical measurement and silver electroplating, further confirmed the above prediction. This efficient and versatile method thus opens a new window to study or design complexing agents for generalized metal electroplating and will vigorously promote the level of this research region. PMID:24452389

  14. A theory of local and global processes which affect solar wind electrons. 2. Experimental support

    International Nuclear Information System (INIS)

    Scudder, J.D.; Olbert, S.

    1979-05-01

    The microscopic characteristics of the Coulomb cross section show that there are three natural subpopulations for plasma electrons: the subthermals; the transthermals; and the extrathermals. Data from three experimental groups on three different spacecraft in the interplanetary medium over a radial range are presented to support the five interrelations projected between solar wind electron properties and changes in the interplanetary medium: (1) subthermals respond primarily to local changes (compression and rarefactions) in stream dynamics; (2) the extrathermal fraction of the ambient electron density should be anti-correlated with the asymptotic bulk speed; (3) the extrathermal 'temperature' should be anti-correlated with the local wind speed at 1 AU; (4) the heat flux carried by electrons should be anti-correlated with the local bulk speed; and (5) the extrathermal differential 'temperature' should be nearly independent of radius within 1 AU

  15. Experimental and numerical investigation of flow field and heat transfer from electronic components in a rectangular channel with an impinging jet

    Directory of Open Access Journals (Sweden)

    Calisir Tamer

    2015-01-01

    Full Text Available Thermal control of electronic components is a continuously emerging problem as power loads keep increasing. The present study is mainly focused on experimental and numerical investigation of impinging jet cooling of 18 (3 × 6 array flash mounted electronic components under a constant heat flux condition inside a rectangular channel in which air, following impingement, is forced to exit in a single direction along the channel formed by the jet orifice plate and impingement plate. Copper blocks represent heat dissipating electronic components. Inlet flow velocities to the channel were measured by using a Laser Doppler Anemometer (LDA system. Flow field observations were performed using a Particle Image Velocimetry (PIV and thermocouples were used for temperature measurements. Experiments and simulations were conducted for Re = 4000 – 8000 at fixed value of H = 10 × Dh. Flow field results were presented and heat transfer results were interpreted using the flow measurement observations. Numerical results were validated with experimental data and it was observed that the results are in agreement with the experiments.

  16. Experimental results from a DC photocathode electron gun for an IR FEL

    International Nuclear Information System (INIS)

    Kehne, D.; Engwall, D.; Legg, R.; Shinn, M.

    1997-01-01

    A 350 keV DC photocathode gun capable of delivering the high-brightness CW electron beam necessary for Jefferson Lab's infrared free-electron laser is described. The gun is to be used with a superconducting radiofrequency linac operating at 1.497 GHz and is mode-locked to the 40th subharmonic of the fundamental using a Nd:YLF drive laser. The gun provides 20--25 ps bunches at up to 135 pC/bunch. Experimental measurements of transverse and longitudinal beam properties are presented. Transverse emittance is measured using a slit-wire scanner emittance meter, and energy spread is measured using the slit and a spectrometer magnet. Longitudinal emittance is measured using a combination of sampling aperture, kicker cavity, slit and spectrometer. Measurements for bunch charges of 135 pC are described and compared with simulations

  17. Experimental and theoretical studies of buoyant-thermo capillary flow

    International Nuclear Information System (INIS)

    Favre, E.; Blumenfeld, L.; Soubbaramayer

    1996-01-01

    In the AVLIS process, uranium metal is evaporated using a high power electron gun. We have prior discussed the power balance equation in the electron beam evaporation process and pointed out, among the loss terms, the importance of the power loss due to the convective flow in the molten pool driven by buoyancy and thermo capillarity. An empirical formula has been derived from model experiments with cerium, to estimate the latter power loss and that formula can be used practically in engineering calculations. In order to complete the empirical approach, a more fundamental research program of theoretical and experimental studies have been carried out in Cea-France, with the objective of understanding the basic phenomena (heat transport, flow instabilities, turbulence, etc.) occurring in a convective flow in a liquid layer locally heated on its free surface

  18. An apparatus to study the energy and angular distributions of electron-bremsstrahlung photons from gaseous targets

    International Nuclear Information System (INIS)

    Yadav, Namita; Bhatt, Pragya; Singh, Raj; Singh, B.K.; Quarles, C.A.; Shanker, R.

    2014-01-01

    An apparatus is developed to measure the energy- and angular distributions of bremsstrahlung generated from collisions of energetic electrons with isolated atoms and molecules. A considerable reduction of thick target bremsstrahlung (TTB) background produced by scattered electrons from the chamber wall is achieved. Details of the experimental setup with regard to design of its components, experimental technique, data acquisition and analysis etc. are given and discussed. The reliability and performance of the setup are demonstrated by obtaining some test results on angular- and energy distributions of bremsstrahlung produced in collisions of 4.0 keV electrons with free argon atoms. These results are compared with the theoretical predictions of the ordinary- and the polarization bremsstrahlung emissions. In this comparison, the experimental data for energy distributions of BS photons are found to be in reasonable agreement while they are found to have noticeable differences in shape of angular distributions. - Highlights: • Experimental setup is developed to study DDCS of electron-bremsstrahlung from gaseous targets. • TTB from scattering chamber's wall is reduced appreciably by using a teflon cylinder. • Shape of DDCS of bremsstrahlung compared with the theories shows a satisfactory match. • Angular distributions of bremsstrahlung show anisotropy but still affected by TTB background photons

  19. Simulation and experimental study of high power microwave damage effect on AlGaAs/InGaAs pseudomorphic high electron mobility transistor

    International Nuclear Information System (INIS)

    Yu Xin-Hai; Chai Chang-Chun; Liu Yang; Yang Yin-Tang; Xi Xiao-Wen

    2015-01-01

    The high power microwave (HPM) damage effect on the AlGaAs/InGaAs pseudomorphic high electron mobility transistor (pHEMT) is studied by simulation and experiments. Simulated results suggest that the HPM damage to pHEMT is due to device burn-out caused by the emerging current path and strong electric field beneath the gate. Besides, the results demonstrate that the damage power threshold decreases but the energy threshold slightly increases with the increase of pulse-width, indicating that HPM with longer pulse-width requires lower power density but more energy to cause the damage to pHEMT. The empirical formulas are proposed to describe the pulse-width dependence. Then the experimental data validate the pulse-width dependence and verify that the proposed formula P = 55τ −0.06 is capable of quickly and accurately estimating the HPM damage susceptibility of pHEMT. Finally the interior observation of damaged samples by scanning electron microscopy (SEM) illustrates that the failure mechanism of the HPM damage to pHEMT is indeed device burn-out and the location beneath the gate near the source side is most susceptible to burn-out, which is in accordance with the simulated results. (paper)

  20. Theoretical and Experimental Studies of New Polymer-Metal High-Dielectric Constant Nanocomposites

    Science.gov (United States)

    Ginzburg, Valeriy; Elwell, Michael; Myers, Kyle; Cieslinski, Robert; Malowinski, Sarah; Bernius, Mark

    2006-03-01

    High-dielectric-constant (high-K) gate materials are important for the needs of electronics industry. Most polymers have dielectric constant in the range 2 materials with K > 10 it is necessary to combine polymers with ceramic or metal nanoparticles. Several formulations based on functionalized Au-nanoparticles (R ˜ 5 -— 10 nm) and PMMA matrix polymer are prepared. Nanocomposite films are subsequently cast from solution. We study the morphology of those nanocomposites using theoretical (Self-Consistent Mean-Field Theory [SCMFT]) and experimental (Transmission Electron Microscopy [TEM]) techniques. Good qualitative agreement between theory and experiment is found. The study validates the utility of SCMFT as screening tool for the preparation of stable (or at least metastable) polymer/nanoparticle mixtures.

  1. Electrochemistry of chlorogenic acid: experimental and theoretical studies

    Energy Technology Data Exchange (ETDEWEB)

    Namazian, Mansoor [Department of Chemistry, Yazd University, P.O. Box 89195-741, Yazd (Iran, Islamic Republic of)]. E-mail: namazian@yazduni.ac.ir; Zare, Hamid R. [Department of Chemistry, Yazd University, P.O. Box 89195-741, Yazd (Iran, Islamic Republic of)

    2005-08-10

    Cyclic voltammetry, chronoamperometry and rotating disk electrode voltammetry as well as quantum chemical methods, are used for electrochemical study of chlorogenic acid, as an important biological molecule. The standard formal potential, diffusion coefficient, and heterogeneous electron transfer rate constant of chlorogenic acid in aqueous solution are investigated. Acidic dissociation constant of chlorogenic acid is also obtained. Quantum mechanical calculations on oxidation of chlorogenic acid in aqueous solution, using density functional theory are presented. The change of Gibbs free energy and entropy of oxidation of chlorogenic acid are calculated using thermochemistry calculations. The calculations in aqueous solution are carried out with the use of polarizable continuum solvation method. Theoretical standard electrode potential of chlorogenic acid is achieved to be 0.580 V versus standard calomel electrode (SCE) which is in agreement with the experimental value of 0.617 V obtained experimentally in this work. The difference is consistent with the values we previously reported for other quinone derivatives.

  2. Cell for studying electron-adsorbed gas interactions; Cellule d'etudes des interactions electron-gaz adsorbe

    Energy Technology Data Exchange (ETDEWEB)

    Golowacz, H; Degras, D A [Commissariat a l' Energie Atomique, 91 - Saclay (France). Centre d' Etudes Nucleaires, Deptartement de Physique des Plasmas et de la Fusion Controlee, Service de Physique Appliquee, Service de Physique des Interractions Electroniques, Section d' Etude des Interactions Gaz-Solides

    1967-07-01

    The geometry and the technology of a cell used for investigations on electron-adsorbed gas interactions are described. The resonance frequencies of the surface ions which are created by the electron impact on the adsorbed gas are predicted by simplified calculations. The experimental data relative to carbon monoxide and neon are in good agreement with these predictions. (authors) [French] Les caracteristiques geometriques et technologiques generales d'une cellule d'etude des interactions entre un faisceau d'electrons et un gaz adsorbe sont donnees. Un calcul simplifie permet de prevoir les frequences de resonance des ions de surface crees par l'impact des electrons sur le gaz adsorbe. Les donnees experimentales sur l'oxyde de carbone et le neon confirment les previsions du calcul. (auteurs)

  3. Experimental observation of the improvement in MTF from backthinning a CMOS direct electron detector

    International Nuclear Information System (INIS)

    McMullan, G.; Faruqi, A.R.; Henderson, R.; Guerrini, N.; Turchetta, R.; Jacobs, A.; Hoften, G. van

    2009-01-01

    The advantages of backthinning monolithic active pixel sensors (MAPS) based on complementary metal oxide semiconductor (CMOS) direct electron detectors for electron microscopy have been discussed previously; they include better spatial resolution (modulation transfer function or MTF) and efficiency at all spatial frequencies (detective quantum efficiency or DQE). It was suggested that a 'thin' CMOS detector would have the most outstanding properties because of a reduction in the proportion of backscattered electrons. In this paper we show, theoretically (using Monte Carlo simulations of electron trajectories) and experimentally that this is indeed the case. The modulation transfer functions of prototype backthinned CMOS direct electron detectors have been measured at 300 keV. At zero spatial frequency, in non-backthinned 700-μm-thick detectors, the backscattered component makes up over 40% of the total signal but, by backthinning to 100, 50 or 35 μm, this can be reduced to 25%, 15% and 10%, respectively. For the 35 μm backthinned detector, this reduction in backscatter increases the MTF by 40% for spatial frequencies between 0.1 and 1.0 Nyquist. As discussed in the main text, reducing backscattering in backthinned detectors should also improve DQE.

  4. Experimental and theoretical study of X-ray absorption around the chlorine L edge in vinyl chloride

    International Nuclear Information System (INIS)

    Kawerk, Elie; Carniato, Stéphane; Iwayama, Hiroshi; Shigemasa, Eiji; Piancastelli, Maria Novella; Wassaf, Joseph; Khoury, Antonio; Simon, Marc

    2013-01-01

    Highlights: ► We measured the X-ray absorption spectrum of C 2 H 3 Cl around the chlorine L edge. ► Ab-initio calculations of the spectrum shed light on eventual electronic resonances. ► Vibrational substructures for particular core excited states are considered. ► The potential energy surfaces of the core excited electronic states are evaluated. ► Sharp or narrow spectral bands are associated to bound or dissociative surfaces. -- Abstract: We present a combined experimental and theoretical study of the high-resolution chlorine L edge X-ray absorption spectrum in gas-phase vinyl chloride (C 2 H 3 Cl). With the help of ab-initio calculations, we interpret the experimental spectrum and attribute each band to its corresponding electronic transitions terminating at states characterized by an either binding or dissociative potential energy surface (PES). Vibrational substructures in some specific core-excited electronic states are taken into account

  5. Experimental and theoretical study of X-ray absorption around the chlorine L edge in vinyl chloride

    Energy Technology Data Exchange (ETDEWEB)

    Kawerk, Elie, E-mail: elie.kawerk@etu.upmc.fr [Université Pierre et Marie Curie, Laboratoire de Chimie Physique-Matière et Rayonnement, UMR 7614, 11 rue Pierre et Marie Curie, 75231 Paris Cedex 05 (France); Université Libanaise, Faculté des Sciences II Fanar, Laboratoire de Physique Appliquée, 90656 Jdeidet el Metn (Lebanon); Carniato, Stéphane [Université Pierre et Marie Curie, Laboratoire de Chimie Physique-Matière et Rayonnement, UMR 7614, 11 rue Pierre et Marie Curie, 75231 Paris Cedex 05 (France); Iwayama, Hiroshi; Shigemasa, Eiji [Ultraviolet Synchrotron Orbital Radiation Facility, Institute for Molecular Science, Okazaki 444-8585 (Japan); Piancastelli, Maria Novella [Université Pierre et Marie Curie, Laboratoire de Chimie Physique-Matière et Rayonnement, UMR 7614, 11 rue Pierre et Marie Curie, 75231 Paris Cedex 05 (France); Wassaf, Joseph; Khoury, Antonio [Université Libanaise, Faculté des Sciences II Fanar, Laboratoire de Physique Appliquée, 90656 Jdeidet el Metn (Lebanon); Simon, Marc [Université Pierre et Marie Curie, Laboratoire de Chimie Physique-Matière et Rayonnement, UMR 7614, 11 rue Pierre et Marie Curie, 75231 Paris Cedex 05 (France)

    2013-02-15

    Highlights: ► We measured the X-ray absorption spectrum of C{sub 2}H{sub 3}Cl around the chlorine L edge. ► Ab-initio calculations of the spectrum shed light on eventual electronic resonances. ► Vibrational substructures for particular core excited states are considered. ► The potential energy surfaces of the core excited electronic states are evaluated. ► Sharp or narrow spectral bands are associated to bound or dissociative surfaces. -- Abstract: We present a combined experimental and theoretical study of the high-resolution chlorine L edge X-ray absorption spectrum in gas-phase vinyl chloride (C{sub 2}H{sub 3}Cl). With the help of ab-initio calculations, we interpret the experimental spectrum and attribute each band to its corresponding electronic transitions terminating at states characterized by an either binding or dissociative potential energy surface (PES). Vibrational substructures in some specific core-excited electronic states are taken into account.

  6. A theoretical study on electronic predissociation in the NeBr2 van der Waals molecule

    International Nuclear Information System (INIS)

    Hernández-Lamoneda, Ramón; Sanz-Sanz, Cristina; Roncero, Octavio; Pio, Jordan M.; Taylor, Molly A.; Janda, Kenneth C.

    2012-01-01

    Graphical abstract: What is the chance that the Rg atom induces electronic coupling before it is ejected by vibrational predissociation? How does the competition depend on the initial vibrational level? Ab initio curve couplings are used in a wave packet calculation to successfully simulate experimental results. Highlights: ► We perform ab initio calculations of NeBr 2 PES’s in valence excited states. ► The ab initio PES’s and couplings are used in subsequent WP calculations. ► These WP calculations model the competition between EP and VP. ► The WP results using the ab initio data agree well with experimental results. - Abstract: We present the first comprehensive ab initio study of the Ne–Br 2 potential energy surfaces and the non-adiabatic couplings between the valence excited electronic states. These ab initio results are used to obtain 3-D approximate potentials for each electronic state, and these potentials are used in a wave packet calculation of the competing electronic predissociation and vibrational predissociation dynamics. The results of this calculation are in excellent agreement with both experimental results and a previous empirical fit to the experiments. The calculations allow us to observe not only the competition between vibrational and electronic dynamics for the dimer, but also the competition between two different electronic channels. Coupling to the 2 g state dominates for the levels studied here, but coupling to the C state is progressively more important for low vibrational levels, and may dominate at levels below which the current results pertain. The ability of ab initio surfaces and couplings to so accurately reproduce experimental data raises the hope of a complete understanding of the VP and EP dynamics for other Rg-halogen dimers. Success in the case presented here is largely due to the fact that the VP dynamics for the vibrational levels in this study are in the simple, direct regime. Understanding the simple case so

  7. Atomic and molecular photoelectron and Auger-electron-spectroscopy studies using synchrotron radiation

    International Nuclear Information System (INIS)

    Southworth, S.H.

    1982-01-01

    Electron spectroscopy, combined with synchrotron radiation, was used to measure the angular distributions of photoelectrons and Auger electrons from atoms and molecules as functions of photon energy. The branching ratios and partial cross sections were also measured in certain cases. By comparison with theoretical calculations, the experimental results are interpreted in terms of the characteristic electronic structure and ionization dynamics of the atomic or molecular sample. The time structure of the synchrotron radiation source was used to record time-of-flight (TOF) spectra of the ejected electrons. The double-angle-TOF method for the measurement of photoelectron angular distributions is discussed. This technique offers the advantages of increased electron collection efficiency and the elimination of certain systematic errors. An electron spectroscopy study of inner-shell photoexcitation and ionization of Xe, photoelectron angular distributions from H 2 and D 2 , and photoionization cross sections and photoelectron asymmetries of the valence orbitals of NO are reported

  8. Studies of transfer reactions of photosensitized electrons involving complexes of transition metals in view of solar energy storage

    International Nuclear Information System (INIS)

    Takakubo, Masaaki

    1984-01-01

    This research thesis addresses electron transfer reactions occurring during photosynthesis, for example, photosensitized reaction in which chlorophyll is the sensitizer. More specifically, the author studied experimentally electron photo-transfers with type D sensitizers (riboflavin, phenoxazine and porphyrin), and various complexes of transition metals. After a presentation of these experiments, the author describes the photosensitisation process (photo-physics of riboflavin, oxygen deactivation, sensitized photo-oxidation and photo-reduction). The theoretical aspect of electron transfer is then addressed: generalities, deactivation of the riboflavin triplet, initial efficiency of electron transfer. Experimental results on three basic processes (non-radiative deactivation, energy transfer, electron transfer) are interpreted in a unified way by using the non-radiative transfer theory. Some applications are described: photo-electrochemical batteries, photo-oxidation and photo-reduction of the cobalt ion

  9. A high-repetition rate LWFA for studies of laser propagation and electron generation

    Science.gov (United States)

    He, Zhaohan; Easter, James; Hou, Bixue; Krushelnick, Karl; Nees, John; Thomas, Alec

    2010-11-01

    Advances in ultrafast optics today have enabled laser systems to deliver ever shorter and more intense pulses. When focused, such laser pulses can easily exceed relativistic intensities where the wakefield created by the strong laser electric field can be used to accelerate electrons. Laser wakefield acceleration of electrons holds promise for future compact electron accelerators or drivers of other radiation sources in many scientific, medical and engineering applications. We present experimental studies of laser wakefield acceleration using the λ-cubed laser at the University of Michigan -- a table-top high-power laser system operating at 500 Hz repetition rate. The high repetition rate allows statistical studies of laser propagation and electron acceleration which are not accessible with typical sub-0.1 Hz repetition rate systems. In addition, we compare the experiments with particle-in-cell simulations using the code OSIRIS.

  10. Electron attachment rate constant measurement by photoemission electron attachment ion mobility spectrometry (PE-EA-IMS)

    International Nuclear Information System (INIS)

    Su, Desheng; Niu, Wenqi; Liu, Sheng; Shen, Chengyin; Huang, Chaoqun; Wang, Hongmei; Jiang, Haihe; Chu, Yannan

    2012-01-01

    Photoemission electron attachment ion mobility spectrometry (PE-EA-IMS), with a source of photoelectrons induced by vacuum ultraviolet radiation on a metal surface, has been developed to study electron attachment reaction at atmospheric pressure using nitrogen as the buffer gas. Based on the negative ion mobility spectra, the rate constants for electron attachment to tetrachloromethane and chloroform were measured at ambient temperature as a function of the average electron energy in the range from 0.29 to 0.96 eV. The experimental results are in good agreement with the data reported in the literature. - Highlights: ► Photoemission electron attachment ion mobility spectrometry (PE-EA-IMS) was developed to study electron attachment reaction. ► The rate constants of electron attachment to CCl 4 and CHCl 3 were determined. ► The present experimental results are in good agreement with the previously reported data.

  11. Monte-Carlo study of electron noise in compensated InSb

    International Nuclear Information System (INIS)

    Ašmontas, S; Raguotis, R; Bumelienė, S

    2015-01-01

    The results of Monte Carlo simulations of the electron noise in lightly doped and strongly compensated n-type InSb are presented. The strong electron scattering by ionized impurities is established to change essentially the electron distribution function, spectral density of velocity fluctuations and the dependence of noise temperature on the electric field strength. It is found that the electron noise temperature in strongly compensated InSb with low electron density at liquid nitrogen temperature is close to the lattice temperature in a wide range of electric field strength in which the electron gas cooling effect takes place. The increase of electron density is shown to weaken the electron gas cooling effect due to more intensive electron–electron collisions stimulating delocalization of electrons from the bottom of the conduction band. A satisfactory agreement between calculations and available experimental data is obtained. (paper)

  12. Study of residual stresses in CT test specimens welded by electron beam

    Science.gov (United States)

    Papushkin, I. V.; Kaisheva, D.; Bokuchava, G. D.; Angelov, V.; Petrov, P.

    2018-03-01

    The paper reports result of residual stress distribution studies in CT specimens reconstituted by electron beam welding (EBW). The main aim of the study is evaluation of the applicability of the welding technique for CT specimens’ reconstitution. Thus, the temperature distribution during electron beam welding of a CT specimen was calculated using Green’s functions and the residual stress distribution was determined experimentally using neutron diffraction. Time-of-flight neutron diffraction experiments were performed on a Fourier stress diffractometer at the IBR-2 fast pulsed reactor in FLNP JINR (Dubna, Russia). The neutron diffraction data estimates yielded a maximal stress level of ±180 MPa in the welded joint.

  13. Studies of electron collisions with polyatomic molecules using distributed-memory parallel computers

    International Nuclear Information System (INIS)

    Winstead, C.; Hipes, P.G.; Lima, M.A.P.; McKoy, V.

    1991-01-01

    Elastic electron scattering cross sections from 5--30 eV are reported for the molecules C 2 H 4 , C 2 H 6 , C 3 H 8 , Si 2 H 6 , and GeH 4 , obtained using an implementation of the Schwinger multichannel method for distributed-memory parallel computer architectures. These results, obtained within the static-exchange approximation, are in generally good agreement with the available experimental data. These calculations demonstrate the potential of highly parallel computation in the study of collisions between low-energy electrons and polyatomic gases. The computational methodology discussed is also directly applicable to the calculation of elastic cross sections at higher levels of approximation (target polarization) and of electronic excitation cross sections

  14. Measurement of the electron and ion temperatures by the x-ray imaging crystal spectrometer on joint Texas experimental tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Yan, W.; Chen, Z. Y., E-mail: zychen@hust.edu.cn; Huang, D. W.; Tong, R. H.; Wang, S. Y.; Wei, Y. N.; Ma, T. K.; Zhuang, G. [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, School of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan (China); Jin, W. [Center of Interface Dynamics for Sustainability, China Academy of Engineering Physics, Chengdu, Sichuan 610200 (China); Lee, S. G. [National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Shi, Y. J. [Department of Nuclear Engineering, Seoul National University, Seoul 08826 (Korea, Republic of)

    2016-11-15

    An x-ray imaging crystal spectrometer has been developed on joint Texas experimental tokamak for the measurement of electron and ion temperatures from the K{sub α} spectra of helium-like argon and its satellite lines. A two-dimensional multi-wire proportional counter has been applied to detect the spectra. The electron and ion temperatures have been obtained from the Voigt fitting with the spectra of helium-like argon ions. The profiles of electron and ion temperatures show the dependence on electron density in ohmic plasmas.

  15. A study of microwave interferometers for electron density measurements in REB-plasma experiments

    International Nuclear Information System (INIS)

    Saxena, A.C.; Paithankar, A.S.; Iyyengar, S.K.; Rohatgi, V.K.

    1981-01-01

    In order to select a suitable microwave interferometer for electron density measurements in Relativistic Electron Beam (REB)-Plasma Experiments, a study has been carried out of four types of interferometers, viz. simple interferometer, standing-wave interferometer, frequency and phase modulated interferometers. Various direct reading interferometers which give a voltage proportional to the phase shift, are also discussed. Systems have been analysed in terms of time resolution, phase sensitivity, system stability, ease of measurement etc. Theoretical and experimental limitations of various systems have been indicated. Summary of the various systems is presented in a table to aid the experimentalist to select the most appropriate system for the prevailina experimental conditions. Finally, an attempt has been made to find out the interferometer system best suited for REB-Plasma Experiments. (author)

  16. Oblique electron cyclotron emission for electron distribution studies (invited)

    International Nuclear Information System (INIS)

    Preische, S.; Efthimion, P.C.; Kaye, S.M.

    1997-01-01

    Electron cyclotron emission (ECE) at an oblique angle to the magnetic field provides a means of probing the electron distribution function both in energy and physical space through changes in and constraints on the relativistic electron cyclotron resonance condition. Diagnostics based on this Doppler shifted resonance are able to study a variety of electron distributions through changes in the location of the resonance in physical or energy space accomplished by changes in the viewing angle and frequency, and the magnetic field. For the case of observation across a changing magnetic field, such as across the tokamak midplane, the constraint on the resonance condition for real solutions to the dispersion relation can constrain the physical location of optically thin emission. A new Oblique ECE diagnostic was installed and operated on the PBX-M tokamak for the study of energetic electrons during lower hybrid current drive. It has a view 33 degree with respect to perpendicular in the tokamak midplane, receives second harmonic X-mode emission, and is constrained to receive single pass emission by SiC viewing dumps on the tokamak walls. Spatial localization of optically thin emission from superthermal electrons (50 endash 100 keV) was obtained by observation of emission upshifted from a thermal cyclotron harmonic. The localized measurements of the electron energy distribution and the superthermal density profile made by this diagnostic demonstrate its potential to study the spatial transport of energetic electrons on fast magnetohydrodynamic time scales or anomalous diffusion time scales. Oblique ECE can also be used to study electron distributions that may have a slight deviation from a Maxwellian by localizing the emission in energy space. (Abstract Truncated)

  17. Defect studies in electron-irradiated ZnO and GaN

    International Nuclear Information System (INIS)

    Tuomisto, F.; Look, D.C.; Farlow, G.C.

    2007-01-01

    We present experimental results obtained with positron annihilation spectroscopy in room-temperature electron-irradiated n-type ZnO and GaN. The cation vacancies act as important compensating centers in 2 MeV electron-irradiated samples, even though their introduction rates are different by 2 orders of magnitude. In addition, negatively charged non-open volume defects that also compensate the n-type conductivity are produced together with the cation vacancies at similar introduction rates. The low introduction rates of compensating defects in ZnO demonstrate the radiation hardness of the material. Isochronal thermal annealings were performed to study the dynamics of the irradiation-induced defects. In 2 MeV electron-irradiated ZnO, all the defects introduced in the irradiation disappear already at 600 K, while 1100 K is needed in GaN. Several separate annealing stages of the defects are observed in both materials, the first at 400 K

  18. Defect studies in electron-irradiated ZnO and GaN

    Energy Technology Data Exchange (ETDEWEB)

    Tuomisto, F. [Laboratory of Physics, Helsinki University of Technology, 02015 TKK Espoo (Finland)], E-mail: filip.tuomisto@tkk.fi; Look, D.C. [Semiconductor Research Center, Wright State University, Dayton, OH 45435 (United States); Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, OH 45433 (United States); Farlow, G.C. [Physics Department, Wright State University, Dayton, OH 45435 (United States)

    2007-12-15

    We present experimental results obtained with positron annihilation spectroscopy in room-temperature electron-irradiated n-type ZnO and GaN. The cation vacancies act as important compensating centers in 2 MeV electron-irradiated samples, even though their introduction rates are different by 2 orders of magnitude. In addition, negatively charged non-open volume defects that also compensate the n-type conductivity are produced together with the cation vacancies at similar introduction rates. The low introduction rates of compensating defects in ZnO demonstrate the radiation hardness of the material. Isochronal thermal annealings were performed to study the dynamics of the irradiation-induced defects. In 2 MeV electron-irradiated ZnO, all the defects introduced in the irradiation disappear already at 600 K, while 1100 K is needed in GaN. Several separate annealing stages of the defects are observed in both materials, the first at 400 K.

  19. Experimental study and modelling of X-ray photo-triggering of a discharge for exciplex laser

    International Nuclear Information System (INIS)

    Louvet, Yolande

    1986-01-01

    As the excitation of the laser medium by using a photo-triggered discharge revealed to be more reliable that an excitation by pre-ionised discharge, this research thesis reports the use of such an excitation and the study of initiation mechanisms for discharges photo-triggered by X rays. The author first recalls the main characteristics of excimer and exciplex systems, and presents the principle of discharge photo-triggering. He presents the experimental set-up, and reports the use of an original method to characterise the X radiation. This method uses theoretical data related to Bremsstrahlung emission, and results are validated by experimental tests. Realistic data regarding X ray properties are introduced into the theoretical model which also takes X-ray-induced ionisation reactions and photo-electron energetic degradation into account. By using this model, the author determines the electron distribution function produced by the X pre-ionisation, and the resulting thermalized electron density [fr

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

    OpenAIRE

    Fullekrug, Martin; Hanuise, C; Parrot, M

    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. Study of single-electron excitations by electron microscopy

    International Nuclear Information System (INIS)

    Craven, A.J.; Gibson, J.M.; Howie, A.; Spalding, D.R.

    1978-01-01

    The inelastic scattering of fast electrons by the excitation of L-shell electrons at a stacking fault in silicon has been studied with a scanning transmission electron microscope. It was found that the bright-field stacking fault contrast is preserved in the filtered L-shell-loss signal at 100 eV. This result is discussed in terms of the delocalization of the excitation mechanism. It is concluded that localization effects will typically become significant only for energy transfers greater than 1 keV from a fast electron of energy 80 keV. (author)

  2. Experimental atomic physics

    International Nuclear Information System (INIS)

    Anon.

    1985-01-01

    The experimental atomic physics program within the physics division is carried out by two groups, whose reports are given in this section. Work of the accelerator atomic physics group is centered around the 6.5-MV EN tandem accelerator; consequently, most of its research is concerned with atomic processes occurring to, or initiated by, few MeV/amu heavy ions. Other activities of this group include higher energy experiments at the Holifield Heavy Ion Research Facility (HHIRF), studies of electron and positron channeling radiation, and collaborative experiments at other institutions. The second experimental group concerns itself with lower energy atomic collision physics in support of the Fusion Energy Program. During the past year, the new Electron Cyclotron Resonance Source has been completed and some of the first data from this facility is presented. In addition to these two activities in experimental atomic physics, other chapters of this report describe progress in theoretical atomic physics, experimental plasma diagnostic development, and atomic data center compilation activities

  3. An improved energy-range relationship for high-energy electron beams based on multiple accurate experimental and Monte Carlo data sets

    International Nuclear Information System (INIS)

    Sorcini, B.B.; Andreo, P.; Hyoedynmaa, S.; Brahme, A.; Bielajew, A.F.

    1995-01-01

    A theoretically based analytical energy-range relationship has been developed and calibrated against well established experimental and Monte Carlo calculated energy-range data. Only published experimental data with a clear statement of accuracy and method of evaluation have been used. Besides published experimental range data for different uniform media, new accurate experimental data on the practical range of high-energy electron beams in water for the energy range 10-50 MeV from accurately calibrated racetrack microtrons have been used. Largely due to the simultaneous pooling of accurate experimental and Monte Carlo data for different materials, the fit has resulted in an increased accuracy of the resultant energy-range relationship, particularly at high energies. Up to date Monte Carlo data from the latest versions of the codes ITS3 and EGS4 for absorbers of atomic numbers between four and 92 (Be, C, H 2 O, PMMA, Al, Cu, Ag, Pb and U) and incident electron energies between 1 and 100 MeV have been used as a complement where experimental data are sparse or missing. The standard deviation of the experimental data relative to the new relation is slightly larger than that of the Monte Carlo data. This is partly due to the fact that theoretically based stopping and scattering cross-sections are used both to account for the material dependence of the analytical energy-range formula and to calculate ranges with the Monte Carlo programs. For water the deviation from the traditional energy-range relation of ICRU Report 35 is only 0.5% at 20 MeV but as high as - 2.2% at 50 MeV. An improved method for divergence and ionization correction in high-energy electron beams has also been developed to enable use of a wider range of experimental results. (Author)

  4. Sounding rocket study of auroral electron precipitation

    International Nuclear Information System (INIS)

    McFadden, J.P.

    1985-01-01

    Measurement of energetic electrons in the auroral zone have proved to be one of the most useful tools in investigating the phenomena of auroral arc formation. This dissertation presents a detailed analysis of the electron data from two sounding rocket campaigns and interprets the measurements in terms of existing auroral models. The Polar Cusp campaign consisted of a single rocket launched from Cape Parry, Canada into the afternoon auroral zone at 1:31:13 UT on January 21, 1982. The results include the measurement of a narrow, magnetic field aligned electron flux at the edge of an arc. This electron precipitation was found to have a remarkably constant 1.2 eV temperature perpendicular to the magnetic field over a 200 to 900 eV energy range. The payload also made simultaneous measurements of both energetic electrons and 3-MHz plasma waves in an auroral arc. Analysis has shown that the waves are propagating in the upper hybrid band and should be generated by a positive slope in the parallel electron distribution. A correlation was found between the 3-MHz waves and small positive slopes in the parallel electron distribution but experimental uncertainties in the electron measurement were large enough to influence the analysis. The BIDARCA campaign consisted of two sounding rockets launched from Poker Flat and Fort Yukon, Alaska at 9:09:00 UT and 9:10:40 UT on February 7, 1984

  5. Experimental determination of pcav factors for cylindrical ionisation chambers in electron beams

    International Nuclear Information System (INIS)

    Palm, Aa.; Mattsson, O.

    2000-01-01

    The electron beam method recommended for calibrating plane parallel ionisation chambers involves cavity correction factors for cylindrical chambers. The cavity correction factors in the IAEA TRS-381 Code of Practice are based on measurements at R 100 in a PMMA phantom using PMMA cylindrical chambers having different cavity radii. In the present work the recommended data were confirmed for electron beams delivered by modern medical accelerators by using the very same phantom and ionisation chambers that were used in the original work. From another series of measurements, using four specially designed wall-less chambers in a graphite phantom, the linear relation between p cav and the chamber radius that is the basis for the experimental method, was verified. The method was also used to determine the cavity correction factors for a set of Farmer-like graphite chambers placed in water. Compared to the TRS-381 Code of Practice a smaller correction was found for the cavity perturbation for the graphite chambers used in water. (author)

  6. An experimental study of the ion energy balance of a magnetized plasma

    International Nuclear Information System (INIS)

    Pots, B.F.M.; Hooff, P. van; Schram, D.C.; Sijde, B. van der

    1981-01-01

    A report is given on an experimental study of the ion energy balance of the magnetized and current-driven plasma f a hollow cathode discharge. The balance appears to be classical. At the axis of the plasma column the electron-ion Coulomb interaction is in equilibrium with the ion-neutral interaction. No significant influence on the energy balance by the spontaneously appearing plasma turbulence is formed. (author)

  7. Experimental study on a cold neutron source of solid methylbenzene

    Energy Technology Data Exchange (ETDEWEB)

    Utsuro, M; Sugimoto, M; Fujita, Y [Kyoto Univ., Kumatori, Osaka (Japan). Research Reactor Inst.

    1975-10-01

    An experimental study to produce cold neutrons with low temperature solid mesitylene as cold moderator in liquid helium and liquid nitrogen cryostats is reported. Measured cold neutron spectra by using an electron linac and time-of-flight method shows that this material is a better cold moderator than light water ice, giving the cold neutron output not so much inferior to that of solid methane in the temperature range above about 20 K and in the neutron energy region above about 1 MeV.

  8. Dynamic electron arc radiotherapy (DEAR): a feasibility study

    International Nuclear Information System (INIS)

    Rodrigues, Anna; Yin, Fang-Fang; Wu, Qiuwen

    2014-01-01

    Compared to other radiation therapy modalities, clinical electron beam therapy has remained practically unchanged for the past few decades even though electron beams with multiple energies are widely available on most linacs. In this paper, we present the concept of dynamic electron arc radiotherapy (DEAR), a new conformal electron therapy technique with synchronized couch motion. DEAR utilizes combination of gantry rotation, couch motion, and dose rate modulation to achieve desirable dose distributions in patient. The electron applicator is kept to minimize scatter and maintain narrow penumbra. The couch motion is synchronized with the gantry rotation to avoid collision between patient and the electron cone. In this study, we investigate the feasibility of DEAR delivery and demonstrate the potential of DEAR to improve dose distributions on simple cylindrical phantoms. DEAR was delivered on Varian's TrueBeam linac in Research Mode. In conjunction with the recorded trajectory log files, mechanical motion accuracies and dose rate modulation precision were analyzed. Experimental and calculated dose distributions were investigated for different energies (6 and 9 MeV) and cut-out sizes (1×10 cm 2  and 3×10 cm 2  for a 15×15 cm 2  applicator). Our findings show that DEAR delivery is feasible and has the potential to deliver radiation dose with high accuracy (root mean square error, or RMSE of <0.1 MU, <0.1° gantry, and <0.1 cm couch positions) and good dose rate precision (1.6 MU min −1 ). Dose homogeneity within ±2% in large and curved targets can be achieved while maintaining penumbra comparable to a standard electron beam on a flat surface. Further, DEAR does not require fabrication of patient-specific shields. These benefits make DEAR a promising technique for conformal radiotherapy of superficial tumors. (paper)

  9. Understanding the role of fast electrons in the heating of dense matter: experimental techniques and recent results

    International Nuclear Information System (INIS)

    Freeman, R.; Anderson, C.; Hill, J.M.; King, J.; Snavely, R.; Hatchett, S.; Key, M.; Koch, J.; MacKinnon, A.; Stephens, R.; Cowan, T.

    2003-01-01

    An intense laser impinging upon dense matter converts a large fraction of its energy into fast electrons. (Here we take 'fast' to mean electrons that are much more energetic than the normal Boltzmann-like distribution measured in the tens to hundreds of eV.) Upon transiting the interior of the dense matter, these electrons are responsible for isochoric heating of the material. Just how these electrons traverse the material, and various interfaces within the material, is a subject of substantial amounts of computation and theory, and recently, experiments. Here we outline the nature of the heating mechanisms, and the current level of understanding of the complex physical processes. In particular we discuss new experimental techniques to record essential features of this transport problem

  10. Angular differential studies of electron transfer in collisions of He-like ions with Na(3s) : The role of electron saddle crossings

    NARCIS (Netherlands)

    Blank, I.; Otranto, S.; Meinema, C.; Olson, R. E.; Hoekstra, R.

    2013-01-01

    We present a systematic experimental and theoretical study of angular differential cross sections of single-electron transfer in collisions of N5+, O6+, and Ne8+ with ground-state Na(3s) in the collision energy range from 1 to 8 keV/amu. Experiments were performed using recoil-ion momentum

  11. A novel experimental scheme of electron scattering off unstable nuclei with a self-confining radioactive ion target (SCRIT)

    International Nuclear Information System (INIS)

    Wakasugi, Masanori

    2005-01-01

    We proposed a new experimental scheme of an electron scattering off unstable nuclei using a Self-Confining Radioactive Ion Target (SCRIT). The SCRIT is an unstable ion target formed in the electron storage ring, and is based on completely new idea. We constructed prototype of the SCRIT device and installed it in the electron storage ring KSR in Kyoto University. In the test experiment, 10 7 -Cs ions are confined in the SCRIT with the lifetime of about 2 s and the feasibility of the SCRIT as the target has been confirmed. (author)

  12. Experimental and analytical study of the bremsstrahlung radiation production at low energies

    International Nuclear Information System (INIS)

    Moran, P.; Gonzales, L.; Delgado, V.; Lopez, A.; Vano, E.

    1986-01-01

    The bremsstrahlung photon beam from an X-ray tube with chromium anode has been studied, for an electron energy of 60 Kev. In the experimental step, a new measurement method has been developed. This is based on the detection and measurement of the fluorescence produced when the photons from the tube impinge on targets which are used as calibrated flux monitors. The composition and physical characteristics of the targets are well-known. In the steps of experimental data treatment, an analytical study of the theoretical models describing thick target bremsstrahlung yield is performed. A factorization which accounts for the elemental physical processes is obtained, employing simple mathematical functions. The characteristic parameters found in the numerical fit process lead to results in good agreement with the experimental observations from other authors and predict theoretical exposure values in perfect agreement with the exposures measured for X-ray beams generated in several operating conditions. (author)

  13. Comparative study of runaway electron diffusion in the rise phase of ...

    Indian Academy of Sciences (India)

    The behaviour of runaway electrons in the SINP tokamak, which can be operated in a normal edge safety factor () (NQ) discharge configuration as well as in a low (LQ) configuration, was experimentally investigated, during the initial plasma generation phase. An energy analysis of the runaway electron dynamics in ...

  14. A Study of High Transverse Momentum Electrons Produced in pp Collisions at 540 GeV

    DEFF Research Database (Denmark)

    Bagnaia, P; Kofoed-Hansen, O.

    1984-01-01

    The production of electrons with very high transverse momentum has been studied in the UA2 experiment at the CERN [`(p)]ppp collider ( Öss =540 GeV). From a sample of events containing an electron candidate withp T >15 GeV/c, we extract a clear signal resulting from the production of the charged...... intermediate vector bosonW ±, which subsequently decays into an electron and a neutrino. We study theW production and decay properties. Further-more, we refine our results on the production and decay of the neutral vector bosonZ 0. Finally, we compare the experimental results to the predictions of the standard...

  15. Photo-physical properties of dimers formed by tri-aryl pyrylium salts: experimental and theoretical study

    International Nuclear Information System (INIS)

    Lampre, Isabelle

    1996-01-01

    This research thesis reports the study of dimers formed in solution by aggregation of tri-aryl pyrylium salts, in order to establish a direct correlation between properties and electronic structure of components, on the one hand, and molecular pattern, on the other hand. The author adopted a multidisciplinary approach by using experimental techniques and calculations based on the excitonic theory and methods of quantum chemistry. First, the properties of the first excited states of cationic chromophores have been studied (characterisation of electronic transitions, relaxation at the singlet excited state, formation of triplet state). Then, the author analysed dimerisation processes and showed that each dimer is formed by two pairs of ions. She discusses some original optical properties of dimers. The geometry of dimers is theoretically determined by minimising the system interaction potential energy. Electronic transitions are then determined as linear combinations of transitions of two monomers. Properties are thus calculated and are in agreement with those deduced from spectral analysis. The experimentally noticed polarisation change and large Stokes displacement are then explained in terms of emission for a localised state on a chromophore [fr

  16. Experimental study on the ionizing radiation field in absorbers irradiated by the 0.8 GeV and 1.2 GeV electrons

    International Nuclear Information System (INIS)

    Ambrosimov, V.K.; Kalmykov, N.N.; Kovalenko, G.D.

    1987-01-01

    The measurement results of spatial distribution of aluminium detector energy release and radioactivity in absorbers irradiated by 0.8 and 1.2 GeV electrons are given. Absorbers are made of aluminium, iron and lead, 30x30 cm size across the thickness is about 18 radiation length units. Thermoluminescence dosimeters LiF and radiochromium film dosimeters have been used to measure energy release. Induced activity of 18 F and 24 Na nuclides is determined in aluminium detectors. The experimental data are compared with the results of calculation carried out by the Monte-Carlo method

  17. Transmission Electron Microscopy of Single Wall Carbon Nanotube/Polymer Nanocomposites: A First-Principles Study

    Science.gov (United States)

    Sola, Francisco; Xia, Zhenhai; Lebrion-Colon, Marisabel; Meador, Michael A.

    2012-01-01

    The physics of HRTEM image formation and electron diffraction of SWCNT in a polymer matrix were investigated theoretically on the basis of the multislice method, and the optics of a FEG Super TWIN Philips CM 200 TEM operated at 80 kV. The effect of nanocomposite thickness on both image contrast and typical electron diffraction reflections of nanofillers were explored. The implications of the results on the experimental applicability to study dispersion, chirality and diameter of nanofillers are discussed.

  18. Study of Electron Cloud E ects in the DAFNE PHI-Factory for the KLOE-2 Run

    CERN Document Server

    Demma, T

    2011-01-01

    A strong horizontal instability has been observed in the the DAFNE positron ring since 2003. Experimental observations suggest an electron cloud induced coupled bunbh instability as a possible explanation. Here is reported a simulation study of the electron cloud effects in the positron ring of the DAFNE PHI factory with particular reference to the machine configuration designed for the KLOE-2 experiment.

  19. Experimental study on the production of high density electron bunches from a GaAs photocathode

    International Nuclear Information System (INIS)

    Calabrese, R.; Masoli, F.; Gong, J.M.; Guidi, V.; Tecchio, L.

    1991-01-01

    In order to obtain a high charge, low emittance electron source, useful for FEL electron injector and for e + e - collider experiments, we performed a test experiment on a gallium arsenide photocathode, activated by negative electron affinity technique and illuminated with a 10 ns long laser pulse of 532 nm wavelength. We measured a maximum charge delivered, at relatively low potentials, of about 18 nC/bunch. The mean lifetime is greater than 60 h. (orig.)

  20. Experimental determination of electron shock excitation cross sections for a singly charged gadolinium ion

    International Nuclear Information System (INIS)

    Smirnov, Yu.M.

    1995-01-01

    The trends observed in the processes of excitation with simultaneous ionization have received little study. This is particularly so for rare-earth elements having electron shells of complex structure and optical spectra very rich in lines. Among the basic factors responsible for such a situation, we should mention two: the difficulty presented by theoretical analysis of the processes discussed and the absence of factual information about the excitation cross sections with simultaneous ionization for the majority of rare-earth elements. The aim of the present work is to investigate the excitation of a singly charged gadolinium ion in the collisions of monokinetic electrons with gadolinium atoms. Up to the present time, only the excitation cross sections of a gadolinium atom have been measured, where investigation of the electron shock excitation of gadolinium atoms in their free state is associated with overcoming large experimental difficulties. About 160 crosss sections for the excitation of a singly charged gadolinium ion were measured and for a third of the cross sections; the energy dependences were recorded for the change in energy of the elecrons from the excitation threshold up to 200 eV. Included are tables of the wavelength, transistion, internal quantum number, the energy of the lowere and upper levels, and the values of cross sections for the charged gadolinium ion. Diagrams of the transistion energy states of Gd (II) and spectroscopy are presented and explained

  1. RF Electron Gun with Driven Plasma Cathode

    CERN Document Server

    Khodak, Igor

    2005-01-01

    It's known that RF guns with plasma cathodes based on solid-state dielectrics are able to generate an intense electron beam. In this paper we describe results of experimental investigation of the single cavity S-band RF gun with driven plasma cathode. The experimental sample of the cathode based on ferroelectric ceramics has been designed. Special design of the cathode permits to separate spatially processes of plasma development and electron acceleration. It has been obtained at RF gun output electron beam with particle energy ~500 keV, pulse current of 4 A and pulse duration of 80 ns. Results of experimental study of beam parameters are referred in. The gun is purposed to be applied as the intense electron beam source for electron linacs.

  2. Comparative study of runaway electron diffusion in the rise phase of ...

    Indian Academy of Sciences (India)

    Abstract. The behaviour of runaway electrons in the SINP tokamak, which can be operated in a normal edge safety factor (qa) (NQ) discharge configuration as well as in a low qa (LQ) configuration, was experimentally investigated, during the initial plasma generation phase. An energy analysis of the runaway electron ...

  3. Experimental observation of IFEL micro-bunching using coherent transition radiation

    International Nuclear Information System (INIS)

    Liu, Y.; Cline, D.B.; Wang, X.J.; Babzien, M.

    1997-01-01

    Electron beam bunching in the optical wavelength was observed experimentally for the first time at the Brookhaven Accelerator Test Facility (ATF) using the Inverse Free Electron (IFEL) accelerator. The micro-bunched electron beam has been studied by measuring the coherent transition radiation (CTR). The authors have experimentally observed a quadratic dependency of the CTR signal with the charge of the electron beam and the observation distance

  4. Radiative electron capture studied in relativistic heavy-ion--atom collisions

    International Nuclear Information System (INIS)

    Stoehlker, T.; Kozhuharov, C.; Mokler, P.H.; Warczak, A.; Bosch, F.; Geissel, H.; Moshammer, R.; Scheidenberger, C.; Eichler, J.; Ichihara, A.; Shirai, T.; Stachura, Z.; Rymuza, P.

    1995-01-01

    The process of radiative electron capture (REC) in relativistic collisions of high-Z ions with low-Z gaseous and solid targets is studied experimentally and theoretically. The observed x-ray spectra are analyzed with respect to photon angular distributions as well as to total K-REC cross sections. The experimental results for angle-differential cross sections are well reproduced by exact relativistic calculations which yield significant deviations from standard sin 2 θ distributions. Total cross sections for K-REC are shown to follow a simple scaling rule obtained from exact relativistic calculations as well as from a nonrelativistic dipole approximation. The agreement between these different theoretical approaches must be regarded as fortuitous, but it lends support to the use of the nonrelativistic approach for practical purposes

  5. Experimental Study of RF Pulsed Heating on Oxygen Free Electronic Copper

    Energy Technology Data Exchange (ETDEWEB)

    Pritzkau, David P.

    2003-02-10

    When the thermal stresses induced by RF pulsed heating are larger than the elastic limit, microcracks and surface roughening will occur due to cyclic fatigue. Therefore, pulsed heating limits the maximum surface magnetic field and through it the maximum achievable accelerating gradient. An experiment using circularly cylindrical cavities operating in the TE{sub 011} mode at a resonant frequency of 11.424 GHz was designed to study pulsed heating on Oxygen Free Electronic (OFE) copper. An X-band klystron delivered up to 10 MW to the cavities in 1.5 {micro}s pulses at 60 Hz repetition rate. One run was executed at a temperature rise of 120 K for 56 x 10{sup 6} pulses. Cracks at grain boundaries, slip bands and cracks associated with these slip bands were observed. The second run consisted of 86 x 10{sup 6} pulses with a temperature rise of 82 K, and cracks at grain boundaries and slip bands were seen. Additional information can be derived from the power-coupling iris, and we conclude that a pulsed temperature rise of 250 K for several million pulses leads to destruction of copper. These results can be applied to any mode of any OFE copper cavity.

  6. Studies on a laser driven photoemissive high-brightness electron source and novel photocathodes

    International Nuclear Information System (INIS)

    Geng Rongli; Song Jinhu; Yu Jin

    1997-01-01

    A laser driven photoemissive high-brightness electron source at Beijing University is reported. Through a DC accelerating gap of 100 kV voltage, the device is capable of delivering high-brightness electron beam of 35-100 ps pulse duration when irradiated with a mode-locked YAG laser. The geometry of the gun is optimized with the aid of simulation codes EGUN and POISSON. The results of experimental studies on ion implanted photocathode and cesium telluride photocathode are given. The proposed laser driven superconducting RF gun is also discussed

  7. Nucleation of diamond by pure carbon ion bombardment--a transmission electron microscopy study

    International Nuclear Information System (INIS)

    Yao, Y.; Liao, M.Y.; Wang, Z.G.; Lifshitz, Y.; Lee, S.

    2005-01-01

    A cross-sectional high-resolution transmission electron microscopy (HRTEM) study of a film deposited by a 1 keV mass-selected carbon ion beam onto silicon held at 800 deg. C is presented. Initially, a graphitic film with its basal planes perpendicular to the substrate is evolving. The precipitation of nanodiamond crystallites in upper layers is confirmed by HRTEM, selected area electron diffraction, and electron energy loss spectroscopy. The nucleation of diamond on graphitic edges as predicted by Lambrecht et al. [W. R. L. Lambrecht, C. H. Lee, B. Segall, J. C. Angus, Z. Li, and M. Sunkara, Nature, 364 607 (1993)] is experimentally confirmed. The results are discussed in terms of our recent subplantation-based diamond nucleation model

  8. Assessment of electronic component failure rates on the basis of experimental data

    International Nuclear Information System (INIS)

    Nitsch, R.

    1991-01-01

    Assessment and prediction of failure rates of electronic systems are made using experimental data derived from laboratory-scale tests or from the practice, as for instance from component failure rate statistics or component repair statistics. Some problems and uncertainties encountered in an evaluation of such field data are discussed in the paper. In order to establish a sound basis for comparative assessment of data from various sources, the items of comparison and the procedure in case of doubt have to be defined. The paper explains two standard methods proposed for practical failure rate definition. (orig.) [de

  9. An experimental study on the effects of high-pressure and multiple injection strategies on DI diesel engine emissions

    KAUST Repository

    Yang, Seung Yeon; Chung, Suk-Ho

    2013-01-01

    An experimental study on effects of high-pressure injections in conjunction with split fuel injections were conducted on an AVL single cylinder DI diesel engine. Various injection schemes were studied through the use of an electronically controlled

  10. A theoretical and experimental study on the molecular and electronic structures of artemisinin and related drug molecules

    International Nuclear Information System (INIS)

    Galasso, V.; Kovac, B.; Modelli, A.

    2007-01-01

    The equilibrium structures of artemisinin and a selection of its derivatives (potent antimalarial drugs) have been studied with the density functional theory ansatz B3LYP. Of the five rings of the artemisinin framework, it is only the pyranose ring B that exhibits a marked conformational flexibility, especially on addition of a pendant side chain at C-10. For the derivatives, the β isomer with the axial substituent group is found to be energetically more stable than the α isomer with the equatorial group. The assignment of the vibrational fundamentals has been supported by calculations on related model molecules and a normal coordinate analysis. This allows for a reliable characterization of the normal modes, mainly involving the peroxide linkage, in the claimed fingerprint region of 1,2,4-trioxanes. The electronic structures have also been studied by measuring and calculating significant features of the NMR, photoelectron and electron transmission spectra. In particular, a representative set of NMR chemical shifts and nuclear spin-spin coupling constants, obtained with DFT formalisms, compares favourably with experiment and fits expectation in terms of stereoelectronic effects of the vicinal oxygen lone pairs. Based on ab initio outer valence Green's function calculations, a consistent interpretation of the uppermost bands in the photoelectron spectra of artemisinin and derivatives has been advanced. The top ionization energies reflect a complex interaction of the various oxygen lone pair orbitals. Electron transmission spectroscopy is applied for the first time to compounds containing the peroxide bond and elucidates the empty level electronic structure of artemisinin and derivatives in the 0-6 eV energy range, with the support of MO calculations and comparison with the spectra of reference molecules. Electron attachment to the lowest-lying empty σ* MO, mainly localized on the O-O bridge, occurs at an energy (1.7 eV) exceptionally low for compounds not

  11. Experimental Benchmarking of Pu Electronic Structure

    International Nuclear Information System (INIS)

    Tobin, J.G.; Moore, K.T.; Chung, B.W.; Wall, M.A.; Schwartz, A.J.; Ebbinghaus, B.B.; Butterfield, M.T.; Teslich, N.E. Jr.; Bliss, R.A.; Morton, S.A.; Yu, S.W.; Komesu, T.; Waddill, G.D.; van der Laan, G.; Kutepov, A.L.

    2008-01-01

    The standard method to determine the band structure of a condensed phase material is to (1) obtain a single crystal with a well defined surface and (2) map the bands with angle resolved photoelectron spectroscopy (occupied or valence bands) and inverse photoelectron spectroscopy (unoccupied or conduction bands). Unfortunately, in the case of Pu, the single crystals of Pu are either nonexistent, very small and/or having poorly defined surfaces. Furthermore, effects such as electron correlation and a large spin-orbit splitting in the 5f states have further complicated the situation. Thus, we have embarked upon the utilization of unorthodox electron spectroscopies, to circumvent the problems caused by the absence of large single crystals of Pu with well-defined surfaces. Our approach includes the techniques of resonant photoelectron spectroscopy, x-ray absorption spectroscopy, electron energy loss spectroscopy, Fano Effect measurements, and Bremstrahlung Isochromat Spectroscopy, including the utilization of micro-focused beams to probe single-crystallite regions of polycrystalline Pu samples.

  12. An experimental study of perovskite-structured mixed ionic- electronic conducting oxides and membranes

    Science.gov (United States)

    Zeng, Pingying

    In recent decades, ceramic membranes based on mixed ionic and electronic conducting (MIEC) perovskite-structured oxides have received many attentions for their applications for air separation, or as a membrane reactor for methane oxidation. While numerous perovskite oxide materials have been explored over the past two decades; there are hardly any materials with sufficient practical economic value and performance for large scale applications, which justifies continuing the search for new materials. The main purposes of this thesis study are: (1) develop several novel SrCoO3-delta based MIEC oxides, SrCoCo1-xMxO3-delta, based on which membranes exhibit excellent oxygen permeability; (2) investigate the significant effects of the species and concentration of the dopants M (metal ions with fixed valences) on the various properties of these membranes; (3) investigate the significant effects of sintering temperature on the microstructures and performance of oxygen permeation membranes; and (4) study the performance of oxygen permeation membranes as a membrane reactor for methane combustion. To stabilize the cubic phase structure of the SrCoO3-delta oxide, various amounts of scandium was doped into the B-site of SrCoO 3-delta to form a series of new perovskite oxides, SrScxCoCo 1-xO3-delta (SSCx, x = 0-0.7). The significant effects of scandium-doping concentration on the phase structure, electrical conductivity, sintering performance, thermal and structural stability, cathode performance, and oxygen permeation performance of the SSCx membranes, were systematically studied. Also for a more in-depth understanding, the rate determination steps for the oxygen transport process through the membranes were clarified by theoretical and experimental investigation. It was found that only a minor amount of scandium (5 mol%) doping into the B-site of SrCoO3-delta can effectively stabilize the cubic phase structure, and thus significantly improve the electrical conductivity and

  13. Modeling and Experimental Validation of the Electron Beam Selective Melting Process

    Directory of Open Access Journals (Sweden)

    Wentao Yan

    2017-10-01

    Full Text Available Electron beam selective melting (EBSM is a promising additive manufacturing (AM technology. The EBSM process consists of three major procedures: ① spreading a powder layer, ② preheating to slightly sinter the powder, and ③ selectively melting the powder bed. The highly transient multi-physics phenomena involved in these procedures pose a significant challenge for in situ experimental observation and measurement. To advance the understanding of the physical mechanisms in each procedure, we leverage high-fidelity modeling and post-process experiments. The models resemble the actual fabrication procedures, including ① a powder-spreading model using the discrete element method (DEM, ② a phase field (PF model of powder sintering (solid-state sintering, and ③ a powder-melting (liquid-state sintering model using the finite volume method (FVM. Comprehensive insights into all the major procedures are provided, which have rarely been reported. Preliminary simulation results (including powder particle packing within the powder bed, sintering neck formation between particles, and single-track defects agree qualitatively with experiments, demonstrating the ability to understand the mechanisms and to guide the design and optimization of the experimental setup and manufacturing process.

  14. Thermodynamic study of 2-aminothiazole and 2-aminobenzothiazole: Experimental and computational approaches

    International Nuclear Information System (INIS)

    Silva, Ana L.R.; Monte, Manuel J.S.; Morais, Victor M.F.; Ribeiro da Silva, Maria D.M.C.

    2014-01-01

    Highlights: • Combustion of 2-aminothiazole and 2-aminobenzothiazole by rotating bomb calorimetry. • Enthalpies of sublimation of 2-aminothiazole and 2-aminobenzothiazole. • Gaseous enthalpies of formation of 2-aminothiazole and 2-aminobenzothiazole. • Gaseous enthalpies of formation calculated from high-level MO calculations. • Gas-phase enthalpies of formation estimated from G3(MP2)//B3LYP approach. - Abstract: This work reports an experimental and computational thermochemical study of two aminothiazole derivatives, namely 2-aminothiazole and 2-aminobenzothiazole. The standard (p° = 0.1 MPa) molar energies of combustion of these compounds were measured by rotating bomb combustion calorimetry. The standard molar enthalpies of sublimation, at T = 298.15 K, were derived from the temperature dependence of the vapor pressures of these compounds, measured by the Knudsen-effusion technique and from high temperature Calvet microcalorimetry. The conjugation of these experimental results enabled the calculation of the standard molar enthalpies of formation in the gaseous state, at T = 298.15 K, for the compounds studied. The corresponding standard Gibbs free energies of formation in crystalline and gaseous phases were also derived, allowing the analysis of their stability, in these phases. We have also estimated the gas-phase enthalpies of formation from high-level molecular orbital calculations at the G3(MP2)//B3LYP level of theory, the estimates revealing very good agreement with the experimental ones. The importance of some stabilizing electronic interactions occurring in the title molecules has been studied and quantitatively evaluated through Natural Bonding Orbital (NBO) of the corresponding wavefunctions and their Nucleus Independent Chemical Shifts (NICS) parameters have been calculated in order to rationalize the effect of electronic delocalization upon stability

  15. Electronic energy states of HfSe/sub 2/ and NbSe/sub 2/ by low energy electron loss spectroscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Ito, T; Iwami, M; Hiraki, A [Osaka Univ., Suita (Japan). Faculty of Engineering

    1981-06-01

    Low energy electron loss spectroscopy (ELS) study was performed on 1T-HfSe/sub 2/ (group IVB metal compound) and 2H-NbSe/sub 2/ (group VB metal compound) by using incident electron energies of 30-250 eV. From the loss data in the second derivative form, maxima in density-of-states in the conduction band of the compounds were deduced through the information on the filled core states by X-ray photoelectron spectroscopy. The conduction band of the transition-metal dichalcogenides could be divided into two parts. The results are discussed in relation to the previous work on WS/sub 2/ (group VIB metal compound), and also to proposals based on band calculations and experimental studies on the transition-metal dichalcogenides with constituent metals of group IVB, VB and VIB.

  16. Methods of experimental physics

    CERN Document Server

    Williams, Dudley

    1962-01-01

    Methods of Experimental Physics, Volume 3: Molecular Physics focuses on molecular theory, spectroscopy, resonance, molecular beams, and electric and thermodynamic properties. The manuscript first considers the origins of molecular theory, molecular physics, and molecular spectroscopy, as well as microwave spectroscopy, electronic spectra, and Raman effect. The text then ponders on diffraction methods of molecular structure determination and resonance studies. Topics include techniques of electron, neutron, and x-ray diffraction and nuclear magnetic, nuclear quadropole, and electron spin reson

  17. Optical potential study of electron scattering by rubidium

    Energy Technology Data Exchange (ETDEWEB)

    Chin, J. H.; Ratnavelu, K. [University of Malaya, Kuala Lumpur (Malaysia); Zhou, Y. [Harbin Institute of Technology, Harbin (China)

    2011-10-15

    The coupled-channel optical method (CCOM) has been implemented in a study of electronrubidium scattering. This method includes the continuum effect in the calculation via an ab-initio optical potential. Eight atomic states (5s, 5p, 4d, 6s, 6p, 5d, 7s, 7p) were used together with the continuum optical potential in the 5s-5s, 5s-5p, and 5p-5p coupling. The elastic, inelastic and total cross sections for electron-rubidium scattering at low and intermediate energies, ranging from 10 eV to 100 eV, are reported. The results are compared with available experimental and theoretical data.

  18. Studying electron-PAG interactions using electron-induced fluorescence

    Science.gov (United States)

    Narasimhan, Amrit; Grzeskowiak, Steven; Ostrander, Jonathan; Schad, Jonathon; Rebeyev, Eliran; Neisser, Mark; Ocola, Leonidas E.; Denbeaux, Gregory; Brainard, Robert L.

    2016-03-01

    In extreme ultraviolet (EUV) lithography, 92 eV photons are used to expose photoresists. Typical EUV resists are organic-based and chemically amplified using photoacid generators (PAGs). Upon exposure, PAGs produce acids which catalyze reactions that result in changes in solubility. In EUV lithography, photo- and secondary electrons (energies of 10- 80 eV) play a large role in PAG acid-production. Several mechanisms for electron-PAG interactions (e.g. electron trapping, and hole-initiated chemistry) have been proposed. The aim of this study is to explore another mechanism - internal excitation - in which a bound PAG electron can be excited by receiving energy from another energetic electron, causing a reaction that produces acid. This paper explores the mechanism of internal excitation through the analogous process of electron-induced fluorescence, in which an electron loses energy by transferring that energy to a molecule and that molecule emits a photon rather than decomposing. We will show and quantify electron-induced fluorescence of several fluorophores in polymer films to mimic resist materials, and use this information to refine our proposed mechanism. Relationships between the molecular structure of fluorophores and fluorescent quantum yield may aid in the development of novel PAGs for EUV lithography.

  19. Studies on the dose distribution and treatment technique of high energy electron beams

    International Nuclear Information System (INIS)

    Lee, D.H.; Chu, S.S.

    1978-01-01

    Some important properties of high energy electron beams from the linear accelerator, LMR-13, installed in the Yonsei Cancer Center were studied. The results of experimental studies on the problems associated with the 8, 10, and 12 MeV electron beam therapy were as followings; The ionization type dosemeters calibrated by 90 Sr standard source were suitable to the measurements of the outputs and the obsorbed doses in accuracy point of view, and dose measurements using ionization chambers were difficult when measuring doses in small field size and the regions of rapid fall off. The electron energies were measured precisely with an energy spectrometer, and the practical electron energy was calculated within 5% error in the maximum range of the high energy electron beam in water. The correcting factors of perturbated dose distributions owing to radiation field, energy, and materials of the treatment cone were checked and described systematically and thus the variation of dose distributions due to the non-homogeneities of tissues and slopping skin surfaces were completely compensated. The electron beams were adequately diffused using the scatterers, and minimized the bremsstrahlung, irradiation field size, and materials of scatterers. Thus, the therapeutic capacity with the limited electron energy could be extended by improving the dose distributions. (author)

  20. Application of Degenerately Doped Metal Oxides in the Study of Photoinduced Interfacial Electron Transfer.

    Science.gov (United States)

    Farnum, Byron H; Morseth, Zachary A; Brennaman, M Kyle; Papanikolas, John M; Meyer, Thomas J

    2015-06-18

    Degenerately doped In2O3:Sn semiconductor nanoparticles (nanoITO) have been used to study the photoinduced interfacial electron-transfer reactivity of surface-bound [Ru(II)(bpy)2(4,4'-(PO3H2)2-bpy)](2+) (RuP(2+)) molecules as a function of driving force over a range of 1.8 eV. The metallic properties of the ITO nanoparticles, present within an interconnected mesoporous film, allowed for the driving force to be tuned by controlling their Fermi level with an external bias while their optical transparency allowed for transient absorption spectroscopy to be used to monitor electron-transfer kinetics. Photoinduced electron transfer from excited-state -RuP(2+*) molecules to nanoITO was found to be dependent on applied bias and competitive with nonradiative energy transfer to nanoITO. Back electron transfer from nanoITO to oxidized -RuP(3+) was also dependent on the applied bias but without complication from inter- or intraparticle electron diffusion in the oxide nanoparticles. Analysis of the electron injection kinetics as a function of driving force using Marcus-Gerischer theory resulted in an experimental estimate of the reorganization energy for the excited-state -RuP(3+/2+*) redox couple of λ* = 0.83 eV and an electronic coupling matrix element, arising from electronic wave function overlap between the donor orbital in the molecule and the acceptor orbital(s) in the nanoITO electrode, of Hab = 20-45 cm(-1). Similar analysis of the back electron-transfer kinetics yielded λ = 0.56 eV for the ground-state -RuP(3+/2+) redox couple and Hab = 2-4 cm(-1). The use of these wide band gap, degenerately doped materials provides a unique experimental approach for investigating single-site electron transfer at the surface of oxide nanoparticles.

  1. Experimental studies of radioactive new formations of object 'Shelter'

    International Nuclear Information System (INIS)

    Vishnevskij, A.S.; Kuz'mina, I.E.; Tkach, V.N.; Tokarevskij, V.V.

    1996-01-01

    Chemical and phase composition of radioactive new-formations of object 'Shelter ' have been experimentally studied by the X-ray and local electronic probe methods of the substance analysis. Leaching of uranium is shown to be a result of attack by alkali-carbonate solutions, migration of uranium take place in the form of double alkali-carbonate system Na 4 [U O 2 (CO 3 ) 3 ]. Carbonates, sulphates, halite and probably sulphates-carbonates were found in the mineral association of new-formations. A hypothesis of formation of sodium uranyltetracarbonate Na 6 (U O 2 )(CO 3 ) 4 , under conditions of object 'Shelter' which was not described in scientific literature before has been advanced

  2. A study of tearing modes via electron cyclotron emission from tokamak plasmas

    International Nuclear Information System (INIS)

    Ren, C.

    1998-07-01

    This thesis studies several tearing mode problems from both theoretical and experimental points of view. A major part of this thesis is to demonstrate that Electron Cyclotron Emission (ECE) is an excellent diagnostic for studying an MHD mode structure and its properties in a tokamak plasma. It is shown that an MHD mode can be detected from the electron temperature fluctuations measured by ECE. The amplitude and phase profiles of the fluctuations contain detailed information about the mode structure. The ECE fluctuation phase profile indicates the magnetic island deformation due to the combination of sheared flow and viscosity. A model is presented to relate qualitatively the observed phase gradient to the local magnetic field, flow velocity shear and viscosity in a 2D slab geometry, using an ideal Ohm's law and the plasma momentum equation including flow and viscosity. Numerical solution of the resultant Grad-Shafranov-like equation describing the deformed island shows that the experimentally observed value of the phase gradient can be obtained under realistic parameters for the shear in the flow velocity and viscosity. A new approach to the tearing mode stability boundary and saturation level is also presented

  3. A study of tearing modes via electron cyclotron emission from tokamak plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Chuang [Univ. of Wisconsin, Madison, WI (United States)

    1998-07-01

    This thesis studies several tearing mode problems from both theoretical and experimental points of view. A major part of this thesis is to demonstrate that Electron Cyclotron Emission (ECE) is an excellent diagnostic for studying an MHD mode structure and its properties in a tokamak plasma. It is shown that an MHD mode can be detected from the electron temperature fluctuations measured by ECE. The amplitude and phase profiles of the fluctuations contain detailed information about the mode structure. The ECE fluctuation phase profile indicates the magnetic island deformation due to the combination of sheared flow and viscosity. A model is presented to relate qualitatively the observed phase gradient to the local magnetic field, flow velocity shear and viscosity in a 2D slab geometry, using an ideal Ohm`s law and the plasma momentum equation including flow and viscosity. Numerical solution of the resultant Grad-Shafranov-like equation describing the deformed island shows that the experimentally observed value of the phase gradient can be obtained under realistic parameters for the shear in the flow velocity and viscosity. A new approach to the tearing mode stability boundary and saturation level is also presented.

  4. Distorted wave models applied to electron emission study in ion-atom collisions at intermediate and high energies

    International Nuclear Information System (INIS)

    Fainstein, P.D.

    1989-01-01

    The electron emission from different atoms induced by impact of multicharged bare ions at intermediate and high energies is studied. To perform these studies, the continuum distorted wave-eikonal initial state model is used. With this distorted wave model, analytical expressions are obtained for the transition amplitudes as a function of the transverse momentum transfer for hydrogen targets in an arbitrary initial state and for every any orbital of a multielectronic target represented as a linear combination of Slater type orbitals. With these expressions, the different cross sections which are compared with the experimental data available are numerically calculated. The results obtained for different targets and projectiles and the comparison with other theoretical models and experimental data allows to explain the electron emission spectra and to predict new effects which have not been measured so far. The results of the present work permit to view the ionization process as the evolution of the active electron in the combined field of the target and projectile nuclei. (Author) [es

  5. Experimental-theoretical comparisons of 1/sup 1/S. -->. 3/sup 1/P differential magnetic sublevel cross sections for electron-helium scattering at 80 and 100 eV

    Energy Technology Data Exchange (ETDEWEB)

    Chutjian, A [Jet Propulsion Lab., Pasadena, Calif. (USA)

    1976-07-11

    Experimental normalized absolute differential cross sections (DCS) for the excitation 1/sup 1/S ..-->.. 3/sup 1/P in helium are reported at incident electron energies of 80 and 100 eV, and at scattering angles between 7/sup 0/ and 135/sup 0/. The measurements are combined with results of recent electron-photon coincidence studies, and absolute DCS for the excitation of the magnetic sublevels 3/sup 1/P/sub 0/ and 3/sup 1/Psub(+-1) are obtained. These experimental sublevel cross sections, and their sum, are compared with results of recent calculations in the multichannel eikonal and distorted-wave polarized-orbital theories.

  6. Experimental Study of WBFC method for testing electromagnetic immunity of integrated circuits

    OpenAIRE

    香川, 直己; カガワ, ナオキ; Naoki, KAGAWA

    2004-01-01

    The author made a workbench faraday cage, WBFC, in order to estimate performance of the WBFC method for the measurement of common mode noise immunity of integrated circuits. In this report, characteristics of the constructed workbench faraday cage and results of experimental study of effects of the common mode noise on a circuit board including an electronic device are shown. Selected DUT, LM324 is popular operational amplifier for electrical circuits in vehicles.

  7. Study of electronic and structural properties of CaS

    International Nuclear Information System (INIS)

    Mirfenderski, M.; Akbarzdeh, H.; Mokhtari, A.

    2003-01-01

    The electronic and structural properties of CaS are calculated using full potential linearized augmented plane wave method within the local density approximation and generalized gradient approximation for the exchange -correlation energy. For both structures, NaCl structure (B1) and CsCl structure (B2), the obtained values for lattice parameters, bulk modulus and its pressure derivative and transition pressure are in reasonable agreement with the experimental values. For electronic properties, the obtained value for band gap is smaller than the experimental value as well as other calculated results based on density functional theory. Engel and Vosko calculated an exchange potential for some atoms within the so-called optimize-potential model and then used the virial relation and constructed a new exchange-correlation functional. We used that functional and obtained reasonable results for band gap. Finally we investigated the possibility for a third phase ( Zinc Blend structure) for this crystal

  8. Observation of electron plasma waves in plasma of two-temperature electrons

    International Nuclear Information System (INIS)

    Ikezawa, Shunjiro; Nakamura, Yoshiharu.

    1981-01-01

    Propagation of electron plasma waves in a large and unmagnetized plasma containing two Maxwellian distributions of electrons is studied experimentally. Two kinds of plasma sources which supply electrons of different temperature are used. The temperature ratio is about 3 and the density ratio of hot to cool electrons is varied from 0 to 0.5. A small contamination of hot electrons enhances the Landau damping of the principal mode known as the Bohm-Gross mode. When the density of hot electrons is larger than about 0.2, two modes are observed. The results agree with theoretical dispersion relations when excitation efficiencies of the modes are considered. (author)

  9. Time-dependent first-principles study of angle-resolved secondary electron emission from atomic sheets

    Science.gov (United States)

    Ueda, Yoshihiro; Suzuki, Yasumitsu; Watanabe, Kazuyuki

    2018-02-01

    Angle-resolved secondary electron emission (ARSEE) spectra were analyzed for two-dimensional atomic sheets using a time-dependent first-principles simulation of electron scattering. We demonstrate that the calculated ARSEE spectra capture the unoccupied band structure of the atomic sheets. The excitation dynamics that lead to SEE have also been revealed by the time-dependent Kohn-Sham decomposition scheme. In the present study, the mechanism for the experimentally observed ARSEE from atomic sheets is elucidated with respect to both energetics and the dynamical aspects of SEE.

  10. Radiative electron capture studied in relativistic heavy-ion atom collisions

    International Nuclear Information System (INIS)

    Stoehlker, T.; Kozhuharov, C.; Mokler, P.H.; Warczak, A.; Bosch, F.; Geissel, H.; Moshammer, R.; Scheidenberger, C.; Eichler, J.; Shirai, T.; Stachura, Z.; Rymuza, P.

    1994-08-01

    The process of Radiative Electron Capture (REC) in relativistic collisions of high-Z ions with low-Z gaseous and solid targets is studied experimentally and theoretically. The observed X-ray spectra are analysed with respect to photon angular distributions as well as to total K-REC cross sections. The experimental results for angle-differential cross sections are well-reproduced by exact relativistic calculations which yield significant deviations from standard sin 2 θ distributions. Total cross sections for K-REC are shown to follow a simple scaling rule obtained from exact relativistic calculations as well as from a non-relativistic dipole approximation. The agreement between these different theoretical approaches must be regarded as fortuitous, but it lends support to the use of the non-relativistic approach for practical purposes. (orig.)

  11. Using numerical simulations to extract parameters of toroidal electron plasmas from experimental data

    DEFF Research Database (Denmark)

    Ha, B. N.; Stoneking,, M. R.; Marler, Joan

    2009-01-01

    Measurements of the image charge induced on electrodes provide the primary means of diagnosing plasmas in the Lawrence Non-neutral Torus II (LNT II) [Phys. Rev. Lett. 100, 155001 (2008)]. Therefore, it is necessary to develop techniques that determine characteristics of the electron plasma from......, as in the cylindrical case. In the toroidal case, additional information about the m=1 motion of the plasma can be obtained by analysis of the image charge signal amplitude and shape. Finally, results from the numerical simulations are compared to experimental data from the LNT II and plasma characteristics...

  12. Evaporative cooling of highly charged ions in EBIT [Electron Beam Ion Trap]: An experimental realization

    International Nuclear Information System (INIS)

    Schneider, M.B.; Levine, M.A.; Bennett, C.L.; Henderson, J.R.; Knapp, D.A.; Marrs, R.E.

    1988-01-01

    Both the total number and trapping lifetime of near-neon-like gold ions held in an electron beam ion trap have been greatly increased by a process of 'evaporative cooling'. A continuous flow of low-charge-state ions into the trap cools the high-charge-state ions in the trap. Preliminary experimental results using titanium ions as a coolant are presented. 8 refs., 6 figs., 2 tabs

  13. Study of electron groupings in the Saclay linear accelerator; Etude du groupement des electrons dans l'accelerateur lineaire de Saclay

    Energy Technology Data Exchange (ETDEWEB)

    Bergere, R; Veyssiere, A; Beil, H [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-07-01

    The classical theory of the linear accelerator buncher does not fit the experimental measurements of the shape of the bunch of electrons performed at Saclay by the method of the energy spectrum. If the spurious effect of the mode converter at the input of the linac is taken into account the theory can fit the experimental results and also explain the variations of the phase of the bunch on the accelerating sine wave. (authors) [French] Une etude classique du groupeur en tete de l'Accelerateur Lineaire de Saclav conduit a des resultats incompatibles avec les resultats experimentaux obtenus sur le groupement des electrons par l'etude du spectre des frequences rayonnees par le faisceau d'electrons ou par l'etude des spectres en energie. Par contre si l'effet parasite du convertisseur de mode a l'entree de l'accelerateur est pris en consideration les resultats theoriques coincident bien avec les resultats experimentaux et permettent en outre d'expliquer les variations du calage en phase des paquets elementaires d'electrons. (auteurs)

  14. Contribution to the study of standing wave bi-periodical accelerating structures for electrons

    International Nuclear Information System (INIS)

    Fuhrmann, Celso

    1985-01-01

    Experimental results on bi-periodic standing wave accelerating structures are presented. These structures which are characterized by a high effective shunt impedance, are designed for standing wave, high duty cycle electron accelerators. Two types of structures are studied: the on-axis coupled structure and the coaxial coupled structure. The expressions for the dispersion relation, coupling coefficients, phase and group velocity are derived from a coupled resonator model. An experimental method to eliminate the stop-band is put forward. The influence of the coupling slots on the dispersion curves is studied experimentally. The effective shunt impedance and the transit time factor are measured by the field perturbation techniques. Measured parameters are compared with SUPERFISH theoretical calculations. The field perturbation technique is also applied to measure the transverse shunt impedance of the dipole modes which are responsible for the beam breakup phenomenon. (author) [fr

  15. Structural, electronic, and optical properties of GaInO{sub 3}: A hybrid density functional study

    Energy Technology Data Exchange (ETDEWEB)

    Wang, V., E-mail: wangvei@icloud.com; Ma, D.-M.; Liu, R.-J.; Yang, C.-M. [Department of Applied Physics, Xi' an University of Technology, Xi' an 710054 (China); Xiao, W. [State Key Lab of Nonferrous Metals and Processes, General Research Institute for Nonferrous Metals, Beijing 100088 (China)

    2014-01-28

    The structural, electronic, and optical properties of GaInO{sub 3} have been studied by first-principles calculations based on Heyd-Scuseria-Ernzerhof hybrid functional theory. The optical properties, including the optical reflectivity, refractive index, extinction coefficient, absorption coefficient, and electron energy loss are discussed for radiation up to 60 eV together with the calculated electronic structure. Our results predicted that GaInO{sub 3} displays good transparency over the whole vision region, which is in good agreement with the experimental data available in the literature.

  16. Status of the experimental studies of the electron cloud at the Los Alamos proton storage ring

    International Nuclear Information System (INIS)

    Macek, R.J.; Browman, A.A.; Borden, M.J.; Fitzgerald, D.H.; McCrady, R.C.; Spickermann, T.J.; Zaugg, T.J.

    2003-01-01

    The electron cloud (EC) at the Los Alamos Proton Storage Ring (PSR) has been studied extensively for the past several years with an overall aim to identify and measure its important characteristics, the factors that influence these characteristics, and to relate these to the two-stream (e-p) transverse instability long observed at PSR. Some new results since PAC2001 are presented.

  17. The order-disorder transition in Cu2ZnSnS4: A theoretical and experimental study

    International Nuclear Information System (INIS)

    Quennet, Marcel; Ritscher, Anna; Lerch, Martin; Paulus, Beate

    2017-01-01

    In this work the Cu/Zn order-disorder transition in Cu 2 ZnSnS 4 kesterites on Wyckoff positions 2c and 2d was investigated by a structural and electronic analysis in theory and experiment. For experimental investigations stoichiometric samples with different Cu/Zn order, annealed in the temperature range of 473–623 K and afterwards quenched, were used. The optical gaps were determined using the Derivation of Absorption Spectrum Fitting (DASF) method. Furthermore, the order-disorder transition was examined by DFT calculations for a closer analysis of the origins of the reduced band gap, showing a good agreement with experimental data with respect to structural and electronic properties. Our studies show a slight increase of lattice parameter c in the kesterite lattice with increasing disorder. Additionally, a reduced band gap was observed with increasing disorder, which is an effect of newly occurring binding motifs in the disordered kesterite structure. - Highlights: • Experimental and theoretical investigation on the order-disorder transition in kesterites. • Slight enlargements of lattice constants due to disorder in experiment and theory. • Strong band gap fluctuations with decreasing order. • Electronic structure deviations due to changing binding motifs. • Disorder as possible main source of low open-circuit voltages.

  18. Experimental study of radiative energy transport in dense plasmas by emission and absorption spectroscopy

    International Nuclear Information System (INIS)

    Dozieres, Maylis

    2016-01-01

    This PhD work is an experimental study, based on emission and absorption spectroscopy of hot and dense nanosecond laser-produced plasmas. Atomic physics in such plasmas is a complex subject and of great interest especially in the fields of astrophysics or inertial confinement fusion. On the atomic physics point of view, this means determining parameters such as the average ionization or opacity in plasmas at given electronic temperature and density. Atomic physics codes then need of experimental data to improve themselves and be validated so that they can be predictive for a wide range of plasmas. With this work we focus on plasmas whose electronic temperature varies from 10 eV to more than a hundred and whose density range goes from 10 -5 ato10 -2 g/cm 3 . In this thesis, there are two types of spectroscopic data presented which are both useful and necessary to the development of atomic physics codes because they are both characteristic of the state of the studied plasma: 1) some absorption spectra from Cu, Ni and Al plasmas close to local thermodynamic equilibrium; 2) some emission spectra from non local thermodynamic equilibrium plasmas of C, Al and Cu. This work highlights the different experimental techniques and various comparisons with atomic physics codes and hydrodynamics codes. (author) [fr

  19. Magnetism in RRhGe (R = Tb, Dy, Er, Tm): An experimental and theoretical study

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Sachin [Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076 (India); Suresh, K.G., E-mail: suresh@phy.iitb.ac.in [Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076 (India); Nigam, A.K. [Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India); Lukoyanov, A.V. [Institute of Metal Physics, Russian Academy of Sciences, Ural Branch, Yekaterinburg 620137 (Russian Federation); Ural Federal University, Yekaterinburg 620002 (Russian Federation)

    2015-08-15

    Highlights: • RRhGe (R = Tb, Dy, Er, Tm) compounds show low temperature antiferromagnetic ordering. • All compounds show field induced metamagnetic transitions. • Some of these compounds show large magnetocaloric effect and magnetoresistance. • Change of sign in MR take place on temperature variation. - Abstract: RRhGe (R = Tb, Dy, Er, Tm) compounds have been studied by different experimental probes and theoretical ab initio calculations. These compounds show very interesting magnetic and transport properties. All the compounds are antiferromagnetic with some of them showing spin-reorientation transition at low temperatures. The magnetocaloric effect estimated from magnetization data shows high values in all these compounds. Magnetoresistance is negative near the ordering temperatures and positive at low temperatures. The electronic structure calculations accounting for electronic correlations in the 4f rare-earth shell reveal the closeness of the antiferromagnetic ground state and other types of magnetic orderings in the rare-earth sublattice. These calculations are also in agreement with the experimental results.

  20. Experimental study of hot electrons propagation and energy deposition in solid or laser-shock compressed targets: applications to fast igniter

    International Nuclear Information System (INIS)

    Pisani, F.

    2000-02-01

    In the fast igniter scheme, a recent approach proposed for the inertial confinement fusion, the idea is to dissociate the fuel ignition phase from its compression. The ignition phase would be then achieved by means of an external energy source: a fast electron beam generated by the interaction with an ultra-intense laser. The main goal of this work is to study the mechanisms of the hot electron energy transfer to the compressed fuel. We intent in particular to study the role of the electric and collisional effects involved in the hot electron propagation in a medium with properties similar to the compressed fuel. We carried out two experiments, one at the Vulcan laser facility (England) and the second one at the new LULI 100 TW laser (France). During the first experiment, we obtained the first results on the hot electron propagation in a dense and hot plasma. The innovating aspect of this work was in particular the use of the laser-shock technique to generate high pressures, allowing the strongly correlated and degenerated plasma to be created. The role of the electric and magnetic effects due to the space charge associated with the fast electron beam has been investigated in the second experiment. Here we studied the propagation in materials with different electrical characteristics: an insulator and a conductor. The analysis of the results showed that only by taking into account simultaneously the two propagation mechanisms (collisions and electric effects) a correct treatment of the energy deposition is possible. We also showed the importance of taking into account the induced modifications due to the electrons beam crossing the target, especially the induced heating. (author)

  1. Effect of Secondary Electron Emission on Electron Cross-Field Current in E×B Discharges

    Energy Technology Data Exchange (ETDEWEB)

    Yevgeny Raitses, Igor D. Kaganovich, Alexander Khrabrov, Dmytro Sydorenko, Nathaniel J. Fisch and Andrei Smolyakov

    2011-02-10

    This paper reviews and discusses recent experimental, theoretical, and numerical studies of plasma-wall interaction in a weakly collisional magnetized plasma bounded with channel walls made from different materials. A lowpressure ExB plasma discharge of the Hall thruster was used to characterize the electron current across the magnetic field and its dependence on the applied voltage and electron-induced secondary electron emission (SEE) from the channel wall. The presence of a depleted, anisotropic electron energy distribution function with beams of secondary electrons was predicted to explain the enhancement of the electron cross-field current observed in experiments. Without the SEE, the electron crossfield transport can be reduced from anomalously high to nearly classical collisional level. The suppression of SEE was achieved using an engineered carbon velvet material for the channel walls. Both theoretically and experimentally, it is shown that the electron emission from the walls can limit the maximum achievable electric field in the magnetized plasma. With nonemitting walls, the maximum electric field in the thruster can approach a fundamental limit for a quasineutral plasma.

  2. Correlating electronic structure with corrosion inhibition potentiality of some bis-benzimidazole derivatives for mild steel in hydrochloric acid: Combined experimental and theoretical studies

    International Nuclear Information System (INIS)

    Dutta, Alokdut; Saha, Sourav Kr.; Banerjee, Priyabrata; Sukul, Dipankar

    2015-01-01

    Highlights: • Bis-benzimidazole derivatives as good corrosion inhibitors for mild steel in acid. • Simultaneous both way electron-transfer is expected to occur during adsorption. • Role of molecular conformation on inhibition efficiency is demonstrated. • Good correlation between inhibition efficiency and molecular parameters established. • MD simulation results support experimental observations. - Abstract: Four different bis-benzimidazole (BBI) derivatives, tested as potential corrosion inhibitors for mild steel in 1 M HCl, have revealed good inhibition efficiency for long period of exposure. Inhibitors impart high resistance towards charge transfer across metal–electrolyte interface and behave broadly as mixed type. DFT calculations are used to correlate inhibition potentiality with intrinsic molecular parameters. From the optimized geometry of BBI derivatives, electron distribution in HOMO and LUMO and Fukui indices of each atom, possible modes of interaction of BBI derivatives with mild steel surface have been predicted. Energy corresponding to inhibitor-metal surface interaction is evaluated following molecular dynamics simulation

  3. Theoretical and experimental studies of the current–voltage and capacitance–voltage of HEMT structures and field-effect transistors

    Energy Technology Data Exchange (ETDEWEB)

    Tarasova, E. A.; Obolenskaya, E. S., E-mail: obolensk@rf.unn.ru; Hananova, A. V.; Obolensky, S. V. [Lobachevsky State University of Nizhny Novgorod (NNSU) (Russian Federation); Zemliakov, V. E.; Egorkin, V. I. [National Research University of Electronic Technology (MIET) (Russian Federation); Nezhenzev, A. V. [Lobachevsky State University of Nizhny Novgorod (NNSU) (Russian Federation); Saharov, A. V.; Zazul’nokov, A. F.; Lundin, V. V.; Zavarin, E. E. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation); Medvedev, G. V. [JSC RPE Salut (Russian Federation)

    2016-12-15

    The sensitivity of classical n{sup +}/n{sup –} GaAs and AlGaN/GaN structures with a 2D electron gas (HEMT) and field-effect transistors based on these structures to γ-neutron exposure is studied. The levels of their radiation hardness were determined. A method for experimental study of the structures on the basis of a differential analysis of their current–voltage characteristics is developed. This method makes it possible to determine the structure of the layers in which radiation-induced defects accumulate. A procedure taking into account changes in the plate area of the experimentally measured barrier-contact capacitance associated with the emergence of clusters of radiation-induced defects that form dielectric inclusions in the 2D-electron-gas layer is presented for the first time.

  4. Study of cerenkov radiation. Production of {gamma} rays by electron accelerators; Etude du rayonnement de freinage. Production de rayons {gamma} par des accelerateurs d'electrons

    Energy Technology Data Exchange (ETDEWEB)

    Bernard, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1961-07-01

    This study is a critical comparison of the theories of Bremsstrahlung. Experimental results obtained by the production of {gamma} radiation with electron accelerators are compared to the theoretical results in order to estimate the extent to which the various theories are valid. (author) [French] Cette etude est une synthese des theories du rayonnement de freinage. Des resultats experimentaux, obtenus par la production de rayonnements {gamma} avec des accelerateurs d'electrons, sont compares aux resultats theoriques afin d'evaluer les domaines de validite des diverses theories. (auteur)

  5. Social Studies by Electronic Mail.

    Science.gov (United States)

    Barr, Hugh

    1994-01-01

    Asserts that electronic mail provides opportunities to engage students actively in cross-cultural contact with students in other nations. Discusses advantages and problems with using electronic mail in the social studies classroom. Describes electronic mail projects that link students in New Zealand, England, and the United States. (CFR)

  6. Experimental study of unipolar arcs in a low pressure mercury discharge

    International Nuclear Information System (INIS)

    Johnson, C.T.

    1979-01-01

    An experimental study of unipolar arcs was conducted in a low pressure mercury discharge inductively heated with RF. The results were found to be consistent with the concept of a sheath mechanism for driving the unipolar arcs. Floating double-probe measurements of the unipolar arc plasma parameters yielded electron temperatures of approx. 2 eV and electron number densities of approx. 1 x 10 11 cm -3 assuming quasi-neutral plasma conditions. The variation of the unipolar arc current with: (1) the RF power input; and (2) the metal surface area exposed to the plasma verified the predicted dependence of the arc current on the plasma parameters and the metal surface area. Finally, alternative mechanisms for sustaining the observed arcs by high frequency rectification were ruled out on the basis of the recorded current waveforms of the unipolar arcs

  7. Electron microscope studies

    International Nuclear Information System (INIS)

    Crewe, A.V.; Kapp, O.H.

    1990-01-01

    Our laboratory has made significant progress this year in devising improved electron-optical systems, in studying invertebrate hemoglobins with the STEM, and in achieving a workable sub-angstrom STEM. Our goal in electron optics is to improve resolution by producing spherical and chromatic aberration coefficients with signs opposite those of magnetic lenses. We have progressed toward this goal through calculations that explore the addition of electrodes to electron mirrors to reduce these two geometric aberrations and by devising a beam separation system that won't introduce asymmetrical aberrations. Some promising new designs of magnetic lenses for SEM applications have also been investigated. We have continued our exploration of the quaternary structure of the invertebrate hemoglobins and are now among the top laboratories in this area of expertise. In addition, we have overcome many of our electronic difficulties on the sub-angstrom STEM and have made significant progress toward achieving an operational system. The addition of an IBM RISC-6000 workstation to our lab has significantly increased our image processing capabilities

  8. Electron-excited molecule interactions

    International Nuclear Information System (INIS)

    Christophorou, L.G.; Tennessee Univ., Knoxville, TN

    1991-01-01

    In this paper the limited but significant knowledge to date on electron scattering from vibrationally/rotationally excited molecules and electron scattering from and electron impact ionization of electronically excited molecules is briefly summarized and discussed. The profound effects of the internal energy content of a molecule on its electron attachment properties are highlighted focusing in particular on electron attachment to vibrationally/rotationally and to electronically excited molecules. The limited knowledge to date on electron-excited molecule interactions clearly shows that the cross sections for certain electron-molecule collision processes can be very different from those involving ground state molecules. For example, optically enhanced electron attachment studies have shown that electron attachment to electronically excited molecules can occur with cross sections 10 6 to 10 7 times larger compared to ground state molecules. The study of electron-excited molecule interactions offers many experimental and theoretical challenges and opportunities and is both of fundamental and technological significance. 54 refs., 15 figs

  9. Intense electron and ion beams

    CERN Document Server

    Molokovsky, Sergey Ivanovich

    2005-01-01

    Intense Ion and Electron Beams treats intense charged-particle beams used in vacuum tubes, particle beam technology and experimental installations such as free electron lasers and accelerators. It addresses, among other things, the physics and basic theory of intense charged-particle beams; computation and design of charged-particle guns and focusing systems; multiple-beam charged-particle systems; and experimental methods for investigating intense particle beams. The coverage is carefully balanced between the physics of intense charged-particle beams and the design of optical systems for their formation and focusing. It can be recommended to all scientists studying or applying vacuum electronics and charged-particle beam technology, including students, engineers and researchers.

  10. Chemical treatment effect on physi-sorption properties of nano-fibres: an experimental and theoretical study

    Energy Technology Data Exchange (ETDEWEB)

    Kayiran, S.B.; Darkrim, F.L.; Gicquel, A. [Paris-Nord Univ., Laboratoire d' Ingenierie des Materiaux et des Hautes Pressions UPR 1311, 93 - Villetaneuse (France); Bernier, P. [Groupe de Dynamique des Phases Condensees, UMR5581 UMII, 34 - Montpellier (France); Gadelle, P. [Universite Joseph Fourier ENSEEG, 38 - St Martin d' Heres (France); Levesque, D. [Paris-11 Univ., Laboratoire de Physique theorique UMR 8627, 91 - Orsay (France)

    2003-09-01

    In this work, we have realized experimental studies of gas adsorption in purified and raw graphitic nano-fibres (GNFs) obtained by CVD method, at a pressure of 20 MPa and a temperature of 293 K. The structural characterizations of these adsorbents have been evaluated by X-ray diffraction, transmission electronic microscopy, specific surface area measurements at 77 K, chemical analysis and Raman spectroscopy. We have also realized Monte Carlo simulations of hydrogen adsorption in GNF model. The results of the simulations, realized in the Grand Canonical ensemble, are compared to experimental data. (authors)

  11. Instrumentation, computer software and experimental techniques used in low-frequency internal friction studies at WNRE

    International Nuclear Information System (INIS)

    Sprugmann, K.W.; Ritchie, I.G.

    1980-04-01

    A detailed and comprehensive account of the equipment, computer programs and experimental methods developed at the Whiteshell Nuclear Research Estalbishment for the study of low-frequency internal friction is presented. Part 1 describes the mechanical apparatus, electronic instrumentation and computer software, while Part II describes in detail the laboratory techniques and various types of experiments performed together with data reduction and analysis. Experimental procedures for the study of internal friction as a function of temperature, strain amplitude or time are described. Computer control of these experiments using the free-decay technique is outlined. In addition, a pendulum constant-amplitude drive system is described. (auth)

  12. Electronic study books and learning style

    NARCIS (Netherlands)

    de Diana, I.P.F.; van der Heiden, G.

    1994-01-01

    Attention has been drawn to the concepts of Electronic Books and Electronic Study Books. Several publications have discussed some main ideas (paradigms) for both concepts. For the Electronic Study Book as a learning environment, it is essential to consider individual modes of learning, usually

  13. A ferroelectric electron gun in a free-electron maser experiment

    International Nuclear Information System (INIS)

    Einat, M.; Jerby, E.; Rosenman, G.

    2002-01-01

    An electron-gun based on a ferroelectric cathode is studied in a free-electron maser (FEM) experiment. In this gun, the electrons are separated from the cathode surface plasma, and are accelerated in two stages. The electron energy-spread is reduced sufficiently for an FEM operation in the microwave regime. A 14 keV, 1-2 A e-beam is obtained in a 0.1-2.1 μs pulse width. The pulse repetition frequency attains 3.1 MHz in ∼50% duty-cycle. This gun is implemented in an FEM oscillator experiment operating around 3 GHz. The paper presents experimental results and discusses the applicability of ferroelectric guns in free-electron laser devices

  14. A ferroelectric electron gun in a free-electron maser experiment

    CERN Document Server

    Einat, M; Rosenman, G

    2002-01-01

    An electron-gun based on a ferroelectric cathode is studied in a free-electron maser (FEM) experiment. In this gun, the electrons are separated from the cathode surface plasma, and are accelerated in two stages. The electron energy-spread is reduced sufficiently for an FEM operation in the microwave regime. A 14 keV, 1-2 A e-beam is obtained in a 0.1-2.1 mu s pulse width. The pulse repetition frequency attains 3.1 MHz in approx 50% duty-cycle. This gun is implemented in an FEM oscillator experiment operating around 3 GHz. The paper presents experimental results and discusses the applicability of ferroelectric guns in free-electron laser devices.

  15. Spin Relaxation in GaAs: Importance of Electron-Electron Interactions

    Directory of Open Access Journals (Sweden)

    Gionni Marchetti

    2014-04-01

    Full Text Available We study spin relaxation in n-type bulk GaAs, due to the Dyakonov–Perel mechanism, using ensemble Monte Carlo methods. Our results confirm that spin relaxation time increases with the electronic density in the regime of moderate electronic concentrations and high temperature. We show that the electron-electron scattering in the non-degenerate regime significantly slows down spin relaxation. This result supports predictions by Glazov and Ivchenko. Most importantly, our findings highlight the importance of many-body interactions for spin dynamics: we show that only by properly taking into account electron-electron interactions within the simulations, results for the spin relaxation time—with respect to both electron density and temperature—will reach good quantitative agreement with corresponding experimental data. Our calculations contain no fitting parameters.

  16. Study on the behaviour of high energy electrons in REPUTE-1 ULQ plasmas

    International Nuclear Information System (INIS)

    Ogawa, Y.; Morikawa, J.; Nihei, H.; Nakajima, T.; Ozawa, D.; Ohno, M.; Suzuki, T.; Himura, H.; Yoshida, Z.; Morita, S.; Shirai, Y.

    2001-01-01

    In REPUTE-1 Ultra-Low-q (ULQ) plasmas, behaviors of high energy electrons have been studied through a low-Z pellet injection experiment, in addition to the measurements of soft-X ray PHA and Electron Energy Analyzer (EEA). The high energy tail has been measured in the soft-X ray spectrum, and EEA signal has shown a strong anisotropy of the electron distribution function (i.e., the electron flux to the electron drift side is dominant). To study temporal and spatial information on these high energy electrons, a low-Z pellet injection experiment has been conducted. A small piece of plastic pellet is injected from the top of the REPUTE-1 device, and the trajectory of the pellet inside the plasma is measured by CCD camera. We have observed a large deflection of the pellet trajectory to the toroidal direction opposite to the plasma current (i.e., the electron drift side). This suggests that a pellet is ablated selectively only from one side due to the high energy electrons with a large heat flux. We have calculated the heat flux carried by high energy electrons. Since the repulsion force to the pellet can be calculated with the 2 nd derivative of the pellet trajectory, we have estimated the heat flux of high energy electrons to be a few tens MW/m 2 around the plasma center. Experimental data by EEA measurement and low-Z pellet ablation show the large population of the high energy electrons at the core region in comparison with the edge region, suggesting a MHD dynamo mechanism for the production of the high energy electrons. (author)

  17. Study of diffused particles by an electron cyclotron-resonance ions source plasma

    International Nuclear Information System (INIS)

    Klein, J.P.

    1995-01-01

    A double electrostatic analyser has been built mainly to study the loss cone electron population. The analysis of the ions can help to determine the plasma potential. The possibility of applying two analysing potentials along the extraction decaying magnetic filed allowed us to determine the anisotropy of the electron distribution function, of parallel temperature Tpar and perpendicular temperature Tper outside the plasma. The Tpar temperature remains constant at around 10 eV when Tper increases from 30 eV to 150 eV with improved confinement. The electron cyclotron heating provides mainly perpendicular energy to the electrons. The perpendicular electron energy is then converted to parallel energy predominantly by electron ion collisions and leave the plasma with a frequency depending on v per -3 . Taking a Maxwellian function of temperature T per cent to describe the electron function distribution f cent (v per ) in the center of the plasma is in line with the experimental electron characteristics obtained with a single electrostatic potential. Temperatures of 2 keV have been reached at 10 Ghz and 6 keV at 18 Ggz. Measurements of density and diamagnetism can complete the description of this warm population: the warm electrons dominate in number but leave the plasma quicker than the very hot electron population (analysed with the X ray diagnostic). For this reason the energy density of warm electrons is less than that of the very hot population by warm electrons consume most of the injected rf power. (author). 52 refs., 100 figs

  18. Radiation reaction studies in an all-optical set-up: experimental limitations

    Science.gov (United States)

    Samarin, G. M.; Zepf, M.; Sarri, G.

    2018-06-01

    The recent development of ultra-high intensity laser facilities is finally opening up the possibility of studying high-field quantum electrodynamics in the laboratory. Arguably, one of the central phenomena in this area is that of quantum radiation reaction experienced by an ultra-relativistic electron beam as it propagates through the tight focus of a laser beam. In this paper, we discuss the major experimental challenges that are to be faced in order to extract meaningful and quantitative information from this class of experiments using existing and near-term laser facilities.

  19. Electronic structure of B-doped diamond: A first-principles study

    Directory of Open Access Journals (Sweden)

    T. Oguchi

    2006-01-01

    Full Text Available Electronic structure of B-doped diamond is studied based on first-principles calculations with supercell models for substitutional and interstitial doping at 1.5–3.1 at.% B concentrations. Substitutional doping induces holes around the valence-band maximum in a rigid-band fashion. The nearest neighbor C site to B shows a large energy shift of 1s core state, which may explain reasonably experimental features in recent photoemission and X-ray absorption spectra. Doping at interstitial Td site is found to be unstable compared with that at the substitutional site

  20. Nuclear clustering and the electron screening puzzle

    Science.gov (United States)

    Bertulani, C. A.; Spitaleri, C.

    2018-01-01

    Electron screening changes appreciably the magnitude of astrophysical nuclear reactions within stars. This effect is also observed in laboratory experiments on Earth, where atomic electrons are present in the nuclear targets. Theoretical models were developed over the past 30 years and experimental measurements have been carried out to study electron screening in thermonuclear reactions. None of the theoretical models were able to explain the high values of the experimentally determined screening potentials. We explore the possibility that the "electron screening puzzle" is due to nuclear clusterization and polarization e_ects in the fusion reactions. We will discuss the supporting arguments for this scenario.

  1. Electronic properties of iron impurity in hcp metals from Moessbauer studies

    International Nuclear Information System (INIS)

    Janot, C.; Delcroix, P.

    1975-01-01

    Moessbauer spectroscopy was used in quantitative investigating the electronic properties of iron impurities in hexagonal close-packed metals. Beryllium of the highest commercially obtainable purity containing about 300 ppm residual impurities was used as a host element. Experimental evidence is given for the existence of localized electronic states which have non-spherical distribution and obviously contribute especially to the electric field gradient. Iron impurity seems to retain the same electronic behaviour as long as the host hcp metal is a normal one (Mg, Cd, Zn), but the localized electronic states seem to disappear when the host is a transition hcp metal (Co, Ti, Sc, Zr, etc.). (Z.S.)

  2. Experimental study on the spin-orbit coupling property in low-dimensional semiconductor structures

    International Nuclear Information System (INIS)

    Zhao, Hongming

    2010-01-01

    The spin-orbit coupling and optical properties have been studied in several low-dimensional semiconductor structures. First, the spin dynamics in (001) GaAs/AlGaAs two-dimensional electron gas was investigated by time resolved Kerr rotation technique under a transverse magnetic field. The in-plane spin lifetime is found to be anisotropic. The results show that the electron density in two-dimensional electron gas channel strongly affects the Rashba spin-orbit coupling. Then, a large anisotropy of the magnitude of in-plane conduction electron g factor in asymmetric (001) GaAs/AlGaAs QWs was observed and its tendency of temperature dependence was studied. Second, the experimental study of the in-plane-orientation dependent spin splitting in the C(0001) GaN/AlGaN two-dimensional electron gas at room temperature was reported. The measurement of circular photo-galvanic effect current clearly shows the isotropic in-plane spin splitting in this system for the first time. Third, the first measurement of conduction electron g factor in GaAsN at room temperature was done by using time resolved Kerr rotation technique. It demonstrates that the g factor can be modified drastically by introducing a small amount of nitrogen in GaAs bulk. Finally, the optical characteristic of indirect type II transition in a series of size and shape-controlled linear CdTe/CdSe/CdTe heterostructure nano-rods was studied by steady-state and time resolved photoluminescence. Results show the steady transfer from the direct optical transition (type I) within CdSe to the indirect transition (type II) between CdSe/CdTe as the length of the nano-rods increases. (author)

  3. Absolute experimental cross sections for the electron impact ionization of rubidium. Technical summary report

    International Nuclear Information System (INIS)

    Hughes, D.W.; Feeney, R.K.

    1980-01-01

    The absolute cross sections for the double, triple, and quadruple ionization of Rb + ions by electron impact have been measured from below their respective thresholds to approximately 3000 eV. This determination has been accomplished using a crossed beam facility in which monoenergetic beams of ions and electrons are caused to intersect at right angles in a well-defined collision volume. Multiply charged, product ions born as a result of the electron impact are deflected into their respective detectors by cascaded electrostatic analyzers. The multiply charged beam current component is measured by means of a vibrating reed electrometer operating in the rate-of-charge mode. The required singly charged rubidium ions are produced in a thermionic ion source and pass through a series of focusing, collimating and deflecting structures before entering the interaction region. A thermionically generated, rectangular electron beam intercepts the target ions in a spatially designated collision volume. Just prior to entering this interaction region the two beams can be made to pass through a movable slit scanner which determines their spatial profiles. The various charged particle currents, energies and beam current density distributions represent the experimental data from which the desired absolute cross sections have been determined. The results obtained with this technique are compared with available theoretical predictions of the appropriate cross sections

  4. Experimental and numerical studies of choked flow through adiabatic and diabatic capillary tubes

    International Nuclear Information System (INIS)

    Deodhar, Subodh D.; Kothadia, Hardik B.; Iyer, K.N.; Prabhu, S.V.

    2015-01-01

    Capillary tubes are extensively used in several cooling applications like refrigeration, electronic cooling etc. Local pressure variation in adiabatic straight capillary tube (mini channel) is studied experimentally and numerically with R134a as the working fluid. Experiments are performed on two straight capillary tubes. It is found that the diameter is the most sensitive design parameter of the capillary tube. Experiments are performed on five helically coiled capillary tubes to quantify the effect of pitch and curvature of helically coiled capillary tube on the pressure drop. Non dimensionalized factor to account coiling of capillary tube is derived to calculate mass flow rate in helically coiled capillary tubes. Flow visualization in adiabatic capillary tube confirms the bubbly nature of two phase flow. Numerical and experimental investigations in diabatic capillary tube suggest that the use of positive displacement pump and choking at the exit of the channel ensures flow stability. - Highlights: • Model is developed to design capillary tube in adiabatic and diabatic condition. • Effect of coil curvature on pressure drop is studied experimentally. • Correlation is developed to predict mass flow rate in helical capillary tubes. • Flow visualization is carried out to check the type of two phase flow. • Effect of choked flow on diabatic capillary tubes is studied experimentally.

  5. Summary of experimental core turbulence characteristics in ohmic and electron cyclotron resonance heated discharges in T-10 tokamak plasmas

    International Nuclear Information System (INIS)

    Vershkov, V.A.; Shelukhin, D.A.; Soldatov, S.V.; Urazbaev, A.O.; Grashin, S.A.; Eliseev, L.G.; Melnikov, A.V.

    2005-01-01

    This report summarizes the results of experimental turbulence investigations carried out at T-10 for more than 10 years. The turbulence characteristics were investigated using correlation reflectometry, multipin Langmuir probe (MLP) and heavy ion beam probe diagnostics. The reflectometry capabilities were analysed using 2D full-wave simulations and verified by direct comparison using a MLP. The ohmic and electron cyclotron resonance heated discharges show the distinct transition from the core turbulence, having complex spectral structure, to the unstructured one in the scrape-off layer. The core turbulence includes 'broad band, quasi-coherent' features, arising due to the excitation of rational surfaces with high poloidal m-numbers, with a low frequency near zero and specific oscillations at 15-30 kHz. All experimentally measured properties of low frequency and high frequency quasi-coherent oscillations are in good agreement with predictions of linear theory for the ion temperature gradient/dissipative trapped electron mode instabilities. Significant local changes in the turbulence characteristics were observed at the edge velocity shear layer and in the core near q = 1 radius after switching off the electron cyclotron resonance heating (ECRH). The local decrease in the electron heat conductivity and decrease in the turbulence level could be evidence of the formation of an electron internal transport barrier. The dynamic behaviour of the core turbulence was also investigated for the case of fast edge cooling and the beginning phase of ECRH

  6. Experimentation and correlates of electronic nicotine delivery system (electronic cigarettes) among university students - A cross sectional study.

    Science.gov (United States)

    Awan, K H

    2016-04-01

    E-cigarettes are becoming popular among youth as safe nicotine delivery systems. Many have expressed concern, however, that e-cigarettes may serve as a gateway to future smoking, given their low perceived risk, or that their use may prevent regular smokers from quitting by maintaining their nicotine addiction. The aim of this study was to assess experimentation with and correlates of e-cigarette use among university students. A cross-sectional study was carried out among 480 university students from four faculties at a university in Riyadh in August-October 2014. A modified version of the World Health Organization's Global Adult Tobacco Survey was used, and multinomial logistic regression was carried out to assess correlations with e-cigarette variables in the whole study sample and among smokers. Almost all students, including the majority of ex-smokers (96.3%) and smokers (94.4%), reported having heard about e-cigarettes. In addition, about one-quarter of the sample (54.2% of smokers, 24.7% of ex-smokers, 6% of never smokers) had experimented with e-cigarettes at least once during their lifetime. Curiosity and peer influence were reported as the main reasons for the use of e-cigarettes. Factors found to be correlated significantly with e-cigarette use were male gender, being a traditional cigarette smoker, having friends who have tried e-cigarettes, and having a strong belief that e-cigarettes could aid smoking cessation. E-cigarettes are popular among Saudi youth, especially among smokers and ex-smokers. Well-designed health education programs and regulatory interventions are required to address this issue.

  7. Experimental approaches and applications

    CERN Document Server

    Crasemann, Bernd

    1975-01-01

    Atomic Inner-Shell Processes, Volume II: Experimental Approaches and Applications focuses on the physics of atomic inner shells, with emphasis on experimental aspects including the use of radioactive atoms for studies of atomic transition probabilities. Surveys of modern techniques of electron and photon spectrometry are also presented, and selected practical applications of inner-shell processes are outlined. Comprised of six chapters, this volume begins with an overview of the general principles underlying the experimental techniques that make use of radioactive isotopes for inner-sh

  8. Electron microscopy of surfaces

    International Nuclear Information System (INIS)

    Venables, J.A.

    1981-01-01

    Electron beam techniques used to study clean surfaces and surface processes on a microscopic scale are reviewed. Recent experimental examples and possible future developments are discussed. Special emphasis is given to (i) transmission diffraction and microscopy techniques, including atomic imaging; (ii) Auger microscopy on bulk and thin film samples; (iii) secondary electron microscopy, especially low energy secondaries for work-function imaging and photoelectron imaging; and (iv) reflection electron microscopy and diffraction. (orig.)

  9. Nuclear structure studies by the scattering of medium-energy electrons: Progress report, September 1, 1986-June 30, 1987

    International Nuclear Information System (INIS)

    Teterson, G.A.; Hicks, R.S.; Dubach, J.F.; Miskimen, R.A.

    1987-06-01

    This paper discusses the experimental electron scattering studies at SLAC and Bates Accelerator Center. Some theoretical work on nucleon-nucleon interactions, electromagnetic interactions, weak interactions and nuclear structure are also discussed

  10. Electron spectroscopy of He and NO using electron impact and multiphoton ionisation

    International Nuclear Information System (INIS)

    Kimman, J.T.N.

    1984-01-01

    This thesis describes two experimental studies which are intended to contribute to our knowledge of the structure of molecules and the decay dynamics of excited molecular states. The two studies have in common that they are both concerned with ionisation processes, in which an accurately known amount of energy is transferred to the target, and energy analysis of the ejected electrons is made. Ionisation is caused either by scattering electrons off the molecules (chapter 2: electron impact ionisation) or by a simultaneous absorption of several photons (chapter 3: multiphoton ionisation). In chapter 2 an electron impact ionisation experiment on Helium is described in which the kinematics of both the scattered and the ejected electrons is fully determined ((e,2e) experiment). (Auth.)

  11. Effect of Secondary Electron Emission on Electron Cross-Field Current in E x B Discharges

    International Nuclear Information System (INIS)

    Raitses, Yevgeny; Kaganovich, Igor D.; Khrabrov, Alexander; Sydorenko, Dmytro; Fisch, Nathaniel J.; Smolyakov, Andrei

    2011-01-01

    This paper reviews and discusses recent experimental, theoretical, and numerical studies of plasma-wall interaction in a weakly collisional magnetized plasma bounded with channel walls made from different materials. A lowpressure ExB plasma discharge of the Hall thruster was used to characterize the electron current across the magnetic field and its dependence on the applied voltage and electron-induced secondary electron emission (SEE) from the channel wall. The presence of a depleted, anisotropic electron energy distribution function with beams of secondary electrons was predicted to explain the enhancement of the electron cross-field current observed in experiments. Without the SEE, the electron crossfield transport can be reduced from anomalously high to nearly classical collisional level. The suppression of SEE was achieved using an engineered carbon velvet material for the channel walls. Both theoretically and experimentally, it is shown that the electron emission from the walls can limit the maximum achievable electric field in the magnetized plasma. With nonemitting walls, the maximum electric field in the thruster can approach a fundamental limit for a quasineutral plasma.

  12. Ion and electron swarm studies of relevance to plasma processing: positive ion-molecule and electron-molecule studies of SF6 and derivatives

    International Nuclear Information System (INIS)

    Atterbury, C.; Kennedy, R.A.; Critchley, A.D.J.; Mayhew, C.A.

    2002-01-01

    Many sequential and parallel chemical reactions involving charged species occur in a plasma. Data needed to model plasma's chemical and physical environment includes cross-section, rate coefficients, and product ion distribution of electron-molecule and ion-molecule processes. Such reactions are studied by our group away from the complexity of the plasma environment, with experimental techniques that allow us to concentrate on a single process, where usually only one or two species are involved. A molecule commonly used in plasma etching applications is SF 6 1,2 . We have performed a series of positive ion-molecule and electron attachment studies on SF 6 and related molecules, including SeF 6 , TeF 6 (i.e. XF 6 molecules), SF 5 CF 3 and SF 5 Cl (i.e. SF 5 X molecules) 3- (. The studies of ion reactions with and electron attachment to SF 6 and physically similar molecules are of value when seeking to understand the ion and electron chemistry occurring in SF 6 containing plasma. The result of these studies are presented in this poster. Ion-molecule reactions. Rate coefficients and ion product branching ratios have been determined with the Selected Ion Flow Tube (SIFT) at room temperature (300 K) for reactions of SF 5 X with the following twenty-two cations; Ne + , F + , Ar + , N 2 + , N + , CO + , CO 2 + , O + , N 2 O + , O 2 + , SF 4 + , CF 2 + , SF + , SF 2 + , NO 2 + , SF 5 + , NO + , CF + , CF 3 + , SF 3 + , and H 3 O + (listed in order of decreasing recombination energy). SF 2 + , NO 2 + , NO + , SF 3 + , and H 3 O + are found to be unreacted with both SF 5 CF 3 and SF 5 Cl. The majority of the other reactions proceed with rate coefficients that are close to the capture value. Those found to occur at rates significantly less than the capture mechanism value re the reactions of O 2 + , SF + , SF 5 + , and CF 3 + with SF 5 CF 3 , and SF 4 + and SF 5 + with SF 5 Cl. Several distinction processes are observed among the large number of reactions studied, including

  13. A study on radiation treatment of wastewater using an electron accelerator

    International Nuclear Information System (INIS)

    Hashimoto, Shoji

    1982-02-01

    A study on radiation oxidation treatment of refractory or toxic wastewater using an electron accelerator was carried out from the viewpoint of reaction engineering. For the process using electron beams, oxygen supply to the penetration range of electron (reaction zone) where the dose rate is extremely high, is significantly important. A concentric dual-tube-type bubbling column reactor was shown to be most suitable to maintain the dissolved oxygen at a high concentration. Rate expressions of pollutant reduction and oxygen consumption in the reactor were derived. The efficiency of active species utilization for oxidation, phi, was defined and shown to be an important design parameter. A new wastewater treatment system (Electron Accelerator-Dual tube Bubbling Reactor system) was proposed, and successfully demonstrated for the treatment of wastewater involving dyes and phenol. The dissolved oxygen was maintained at a high concentration by using this type of reactor for the high dose rate irradiation. phi was obtained as a function of dissolved oxygen concentration for the dye solution and was also obtained as functions of the oxygen concentration and dose rate for the phenol solution. By these experimental results, the effectiveness of EA-DBR system was proved. (author)

  14. Study of electrons photoemitted from field emission tips. Progress report, July 1, 1979-March 1, 1980

    International Nuclear Information System (INIS)

    Reifenberger, R.

    1980-02-01

    Photo-induced field emission is a technique which studies electrons that have been photoemitted from a field emission tip. This new experimental method promises to combine the proven utility of both field emission and photoemission for investigating the electronic states near a metal surface. The primary objective of the research being performed is to investigate photo-induced field emitted electrons using a tuneable cw dye laser. To fully exploit this continuously tuneable photon source, a differential energy analyzer is being constructed to allow energy resolved measurements of the photo-field emitted electrons. This report describes the progress made in implementing experiments on photo-induced field emission from July 1979 to March 1980

  15. Theoretical Studies of the Electronic Structure of the Compounds of the Actinide Elements

    International Nuclear Information System (INIS)

    Kaltsoyannis, Nikolas; Hay, P.J.; Li, Jun; Blaudeau, Jean-Philippe; Bursten, Bruce E.

    2006-01-01

    In this chapter, we will present an overview of the theoretical and computational developments that have increased our understanding of the electronic structure of actinide-containing molecules and ions. The application of modern electronic structure methodologies to actinide systems remains one of the great challenges in quantum chemistry; indeed, as will be discussed below, there is no other portion of the periodic table that leads to the confluence of complexity with respect to the calculation of ground- and excited-state energies, bonding descriptions, and molecular properties. But there is also no place in the periodic table in which effective computational modeling of electronic structure can be more useful. The difficulties in creating, isolating, and handling many of the actinide elements provide an opportunity for computational chemistry to be an unusually important partner in developing the chemistry of these elements. The importance of actinide electronic structure begins with the earliest studies of uranium chemistry and predates the discovery of quantum mechanics. The fluorescence of uranyl compounds was observed as early as 1833, a presage of the development of actinometry as a tool for measuring photochemical quantum yields. Interest in nuclear fuels has stimulated tremendous interest in understanding the properties, including electronic properties, of small actinide-containing molecules and ions, especially the oxides and halides of uranium and plutonium. The synthesis of uranocene in 1968 led to the flurry of activity in the organometallic chemistry of the actinides that continues today. Actinide organometallics (or organoactinides) are nearly always molecular systems and are often volatile, which makes them amenable to an arsenal of experimental probes of molecular and electronic structure (Marks and Fischer, 1979). Theoretical and computational studies of the electronic structure of actinide systems have developed in concert with the experimental

  16. Compact high-current, subnanosecond electron accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Shpak, V G; Shunajlov, S A; Ulmaskulov, M R; Yalandin, M I [Russian Academy of Sciences, Ekaterinburg (Russian Federation). Inst. of Electrophysics; Pegel, I V [Russian Academy of Sciences, Tomsk (Russian Federation). High-Current Electronics Inst.; Tarakanov, V P [Russian Academy of Sciences, Moscow (Russian Federation). High-Temperature Inst.

    1997-12-31

    A compact subnanosecond, high-current electron accelerator producing an annular electron beam of duration up to 300 - 400 ps, energy about 250 keV, and current up to 1 kA has been developed to study transient processes in pulsed power microwave devices. The measuring and recording techniques used to experimentally investigate the dynamics of the beam current pulse and the transformation of the electron energy during the transportation of the beam in a longitudinal magnetic field are described. The experimental data obtained are compared with the predictions of a numerical simulation. (author). 6 figs., 5 refs.

  17. Phenomenological studies of electron-beam transport in wire-plasma channels

    International Nuclear Information System (INIS)

    Lockwood, G.J.; Beezhold, W.

    1980-01-01

    Multiple electron-beam transport in air through plasma channels is an important method for delivering many intense beams to a bremsstrahlung converter system. This paper reports work intended to optimize this transport technique with emphasis on transport through curved channels and on transport efficiencies. Curved-channel transport allows accelerators such as Sandia's PROTO II and PBFA I facilities to be used as flash x-ray sources for weapon effects simulation without reconfiguring the diodes or developing advanced converters. The formation mechanisms of wire-initiated plasma channels in air were examined and the subsequent transport efficiencies of relativistic electron beams through various-length straight and curved plasma channels were determined. Electron transport efficiency through a channel was measured to be 80 to 100% of a zero length channel for 40 cm long straight channels and for curved channels which re-directed the electron beam through an angle of 90 0 . Studies of simultaneous e-beam transport along two curved channels closely spaced at the converter showed that transport efficiency remained at 80 to 100%. However, it was observed that the two e-beams were displaced towards each other. Transport efficiency was observed to depend only weakly on parameters such as wire material, wire length and shape, diode anode aperture, e-beam injection time, and wire-channel applied voltage. For off-center injection conditions the electron beam strongly perturbed the plasma channel in periodic or regularly spaced patterns even though the total energy lost by the electron beam remained small. Plasma-channel transport, when all experimental parameters have been optimized for maximum transport efficiency, is a workable method for directing electron beams to a converter target

  18. Secondary mineralization in carious lesions of human dentin. Electron-probe, electron microscope, and electron diffraction studies

    Energy Technology Data Exchange (ETDEWEB)

    Ogiwara, H [Tokyo Dental Coll. (Japan)

    1975-02-01

    Dentinal carious lesions having a remineralized surface layer were studied by means electron-probe microanalysis, electron microscopy, electron diffraction. As the results of electron-probe study, F, Mg, and Na were found to be distributed mainly in the remineralized surface layer and S in the decalcified region where decreases in Ca, P, and Mg concentration were usually observed. The decrease in Mg concentration always started earlier than that of Ca and P concentration. Electron microscope and electron diffraction studies revealed that apatic crystals in the remineralized surface layer were much larger than those in the intact dentin. Although they were less conspicuous, crystals in the decalcified region also were larger than those in the intact region. Dentinal tubules, occluded by many crystals, were frequently seen during the observations. Crystals in the tubules varied in morphology, showing granular, needle, rhomboid, and tabular shapes. By means of electron diffraction, the granular- or needle-shaped crystals were identified as apatite and the rhomboid-shaped crystals as whitlockite. Some of the tabular-shaped crystals appeared to be cotacalcium phosphate.

  19. Compton scattering studies of the electron momentum distribution in indium phosphide

    CERN Document Server

    Deb, A; Guin, R; Chatterjee, A K

    1999-01-01

    The electron momentum anisotropy of indium phosphide has been studied by measuring the directional Compton profiles of indium phosphide single crystals with the use of radiation from an sup 2 sup 4 sup 1 Am gamma source. Three different samples, cut along the [100], [110] and [111] planes, were used. The experimental anisotropy has been compared with the results based on the linear combination of Gaussian orbitals (LCGO) method. The agreement is very good with our theoretical results. It is found that the extrema appearing in the dependences on q of the anisotropies have an intimate connection with the bonding properties of the semiconductor. A self-consistent, all-electron, local density calculation for the partial density of states, total density of states and the charge analysis is also presented here.

  20. [Experiment studies of electron-positron interactions at the Stanford Linear Accelerator Center

    International Nuclear Information System (INIS)

    Hertzbach, S.S.; Kofler, R.R.

    1993-01-01

    The High Energy Physics group at the University of Massachusetts has continued its' program of experimental studies of electron-positron interactions at the Stanford Linear Accelerator Center (SLAC). The group activities have included: analysis of data taken between 1982 and 1990 with the TPC detector at the PEP facility, continuing data collection and data analysis using the SLC/SLD facility, planning for the newly approved B-factory at SLAC, and participation in design studies for future high energy linear colliders. This report will briefly summarize these activities

  1. Study of luminous emissions associated to electron emissions in radiofrequency cavities

    International Nuclear Information System (INIS)

    Maissa, S.

    1996-01-01

    This study investigates luminous emissions simultaneously to electron emissions and examines their features in order to better understand the field electron emission phenomenon. A RF cavity, operating at room temperature and in pulsed mode, joined to a sophisticated experimental apparatus has been especially developed. The electron and luminous emissions are investigated on cleaned or with metallic, graphitic and dielectric particles contaminated RF surfaces in order to study their influence on these phenomena. During the surface processing, unstable luminous spots glowing during one RF pulse are detected. Their apparition is promoted in the vicinity of the metallic particles or scratches. Two hypotheses could explain their origin: the presence of micro-plasmas associated to electronic explosive emission during processing or the thermal radiation of the melted metal during this emission. Stable luminous spots glowing during several RF pulses are also detected and appear to increase on RF surfaces contaminated with dielectric particles, leading to strong and explosive luminous emissions. Two interpretations are considered: the initiation of surface breakdowns on the dielectric particles or the heating by the RF field at temperatures sufficiently intense to provoke their thermal radiation then their explosion. Finally a superconducting cavity has been adapted to observe luminous spots, which differ from the former ones bu their star shape and could be associated to micro-plasmas, revealed by the starbursts observed on superconducting cavity walls. (author)

  2. Microscopy of electronic wave function

    International Nuclear Information System (INIS)

    Harb, M.

    2010-01-01

    This work of thesis aims to visualize, on a position sensitive detector, the spatial oscillations of slow electrons (∼ meV) emitted by a threshold photoionization in the presence of an external electric field. The interference figure obtained represents the square magnitude of electronic wavefunction. This fundamental work allows us to have access to the electronic dynamics and thus to highlight several quantum mechanisms that occur at the atomic scale (field Coulomb, electron/electron interaction..). Despite the presence an electronic core in Li atom, we have succeeded, experimentally and for the first time, in visualizing the wave function associated with the quasi-discrete Stark states coupled to the ionization continuum. Besides, using simulations of wave packet propagation, based on the 'Split-operator' method, we have conducted a comprehensive study of the H, Li and Cs atoms while revealing the significant effects of the Stark resonances. A very good agreement, on and off resonances, was obtained between simulated and experimental results. In addition, we have developed a generalized analytical model to understand deeply the function of VMI (Velocity-Map Imaging) spectrometer. This model is based on the paraxial approximation; it is based on matrix optics calculation by making an analogy between the electronic trajectory and the light beam. An excellent agreement was obtained between the model predictions and the experimental results. (author)

  3. Experimental investigations on the influence of the photocathode laser pulse parameters on the electron bunch quality in an RF-photoelectron source

    Energy Technology Data Exchange (ETDEWEB)

    Haenel, Marc

    2010-07-15

    Free Electron Lasers based on the SASE principle like the European XFEL require electron bunches having peak currents of several kiloamperes as well as very low transverse emittance. While high peak currents can be generated using longitudinal bunch compression techniques, the transverse emittance must have values as low as 1mmmrad already at the source. The development of electron sources fulfilling these demanding specifications is the goal of the Photo Injector Test Facility (PITZ) in DESY, Zeuthen site. The key component of a photoinjector is the electron gun cavity where the electrons bunches are generated and immediately accelerated. The extraction of the electrons is based on the photoelectric effect of the cathode which requires a laser system having special capabilities. In the first part of the thesis, measurements are presented which were performed to investigate whether the laser and the laser transport system fulfill these requirements. The second part of the thesis is dedicated to simulations as well as experimental studies on the impact of the temporal and spatial parameters of the laser pulses on the electron bunch quality. This influence is possible because the response time of the Cs{sub 2}Te photocathode is short compared to the laser pulse duration. Based on these investigations, suggestions for improvements are given and tolerances for the laser pulse properties are defined. (orig.)

  4. Experimental investigations on the influence of the photocathode laser pulse parameters on the electron bunch quality in an RF-photoelectron source

    International Nuclear Information System (INIS)

    Haenel, Marc

    2010-06-01

    Free Electron Lasers based on the SASE principle like the European XFEL require electron bunches having peak currents of several kiloamperes as well as very low transverse emittance. While high peak currents can be generated using longitudinal bunch compression techniques, the transverse emittance must have values as low as 1mmmrad already at the source. The development of electron sources fulfilling these demanding specifications is the goal of the Photo Injector Test Facility (PITZ) in DESY, Zeuthen site. The key component of a photoinjector is the electron gun cavity where the electrons bunches are generated and immediately accelerated. The extraction of the electrons is based on the photoelectric effect of the cathode which requires a laser system having special capabilities. In the first part of the thesis, measurements are presented which were performed to investigate whether the laser and the laser transport system fulfill these requirements. The second part of the thesis is dedicated to simulations as well as experimental studies on the impact of the temporal and spatial parameters of the laser pulses on the electron bunch quality. This influence is possible because the response time of the Cs 2 Te photocathode is short compared to the laser pulse duration. Based on these investigations, suggestions for improvements are given and tolerances for the laser pulse properties are defined. (orig.)

  5. Experimental and theoretical study of the energy loss of C and O in Zn

    Energy Technology Data Exchange (ETDEWEB)

    Cantero, E. D.; Lantschner, G. H.; Arista, N. R. [Centro Atomico Bariloche and Instituto Balseiro, Comision Nacional de Energia Atomica, 8400 San Carlos de Bariloche (Argentina); Montanari, C. C.; Miraglia, J. E. [Instituto de Astronomia y Fisica del Espacio (CONICET-UBA), Buenos Aires (Argentina); Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires (Argentina); Behar, M.; Fadanelli, R. C. [Instituto de Fisica, Universidade Federal do Rio Grande do Sul, Avenida Bento Goncalves 9500, Porto Alegre-RS (Brazil)

    2011-07-15

    We present a combined experimental-theoretical study of the energy loss of C and O ions in Zn in the energy range 50-1000 keV/amu. This contribution has a double purpose, experimental and theoretical. On the experimental side, we present stopping power measurements that fill a gap in the literature for these projectile-target combinations and cover an extended energy range, including the stopping maximum. On the theoretical side, we make a quantitative test on the applicability of various theoretical approaches to calculate the energy loss of heavy swift ions in solids. The description is performed using different models for valence and inner-shell electrons: a nonperturbative scattering calculation based on the transport cross section formalism to describe the Zn valence electron contribution, and two different models for the inner-shell contribution: the shellwise local plasma approximation (SLPA) and the convolution approximation for swift particles (CasP). The experimental results indicate that C is the limit for the applicability of the SLPA approach, which previously was successfully applied to projectiles from H to B. We find that this model clearly overestimates the stopping data for O ions. The origin of these discrepancies is related to the perturbative approximation involved in the SLPA. This shortcoming has been solved by using the nonperturbative CasP results to describe the inner-shell contribution, which yields a very good agreement with the experiments for both C and O ions.

  6. Experimental Studies of Ar{sup n+} ionization using an EBIS

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seunghyun; Kim, Han-Sung; Kwon, Hyeok-Jung; Cho, Yong-Sub [Korea Atomic Energy Research Institute, Gyeongju (Korea, Republic of)

    2016-10-15

    Electron beam ion source (EBIS) has been one of widely used table-top devices for the production of highly charged ions by electron impact ionization. EBIS employs a magnetically compressed, high energy and density electron beam to sequentially ionize atoms or ions in a low charge state. Combination of an EBIS and a Radio frequency quadrupole (RFQ) is a suitable means of heavy ion beam production at low energies. With EBIS, beams of any element can be prepared including uranium and spin-polarized {sup 3}He with a narrow charge distribution. It has demonstrated its reliability and flexibility as a pre-injector used at several accelerators and collider facilities such as Brookhaven National Laboratory, Relative Heavy Ion Collider, NASA Space Radiation Laboratory, Argonne National Laboratory and Large Hadron Collider. At Korea Multi-purpose Accelerator Complex (KOMAC), we have a compact EBIS, operated at room temperature. It is additionally constructed with a dipole bending magnet and a Faraday Cup to separate the charge distribution and measure charge spectra of an ion beam from the EBIS. Using this setup, helium (He) and argon (Ar) gases have been tested to produce charge spectra. An EBIS is employed to produce ions in multiply charged states. We measure an Ar ion spectrum and identify it till 16{sup th} charge state. A detailed experimental study of Ar{sup 1+} and Ar{sup 2+} ions is performed to characterize the effects of electron beam for ionization.

  7. Investigation of particle transport through the measurement of the electron source in the Texas Experimental Tokamak

    International Nuclear Information System (INIS)

    Klepper, C.C.

    1985-01-01

    The spatial distribution of the electron source was measured spectroscopically in the Texas Experimental Tokamak. The method used involves the measurement of the emissivity of the Balmer α and β lines of neutral hydrogen. Modeling of the corresponding atomic transitions provides a relation between the emissivities and the electron source from the ionization of neutrals. Toroidal distributions were obtained by means of a set of relatively calibrated photodiode amplifier-filter packages referred to as plasma light monitors. Such monitors were distributed toroidally, and attached primarily to radial ports. Specially constructed, absolutely calibrated monitors provided absolute calibration. A scanning, rotating mirror system provided in-out brightness profiles. A TV camera system, viewing the limiter through a tangential port, provided a qualitative description of the poloidal asymmetry. Such description was necessary for the inversion of the rotating mirror data. Using electron density profiles obtained by means of far-infrared interferometry, and integrating the electron sources, the global particle confinement time (tau/sub p/) was computed. Parameter scans were performed in ohmically heated plasmas, varying the toroidal field, the plasma current, the electron density, and the plasma position with respect to the center of the poloidal ring limiter. It was found that tau/sub p/ peaks for a critical density that is independent of the other parameters

  8. Electron paramagnetic resonance

    CERN Document Server

    Al'tshuler, S A

    2013-01-01

    Electron Paramagnetic Resonance is a comprehensive text on the field of electron paramagnetic resonance, covering both the theoretical background and the results of experiment. This book is composed of eight chapters that cover theoretical materials and experimental data on ionic crystals, since these are the materials that have been most extensively studied by the methods of paramagnetic resonance. The opening chapters provide an introduction to the basic principles of electron paramagnetic resonance and the methods of its measurement. The next chapters are devoted to the theory of spectra an

  9. Experimental study of finite Larmor radius effects

    International Nuclear Information System (INIS)

    Struve, K.W.

    1980-08-01

    Linear Z-pinches in Ar, Kr, Xe, N 2 , and He are experimentally studied in regimes where strong finite Larmor radius effects could provide a significant stabilizing effect. Scaling arguments show that for deuterium such a pinch has an electron line density of order 2 x 10 15 /cm. For higher Z plasmas a higher line density is allowed, the exact value of which depends on the average ion charge. The pinch is formed by puffing gas axially through the cathode towards the anode of an evacuated pinch chamber. When the gas reaches the anode, the pinch bank is fired. The pinch current rises in 2 to 3 μsec to a maximum of 100 to 200 kA. The pinch bank capacitance is 900 μF, and the external inductance is 100 nH. Additionally, the bank is fused to increase dI/dt. The primary diagnostics are a framing camera, a spatially resolved Mach-Zehnder interferometer, and X-ray absorption

  10. Experimental demonstration and visual observation of dust trapping in an electron storage ring

    Directory of Open Access Journals (Sweden)

    Yasunori Tanimoto

    2009-11-01

    Full Text Available Sudden decreases in the beam lifetime, which are attributed to the dust trappings, sometimes occur at the electron storage ring Photon Factory Advanced Ring (PF-AR. Since these dust events cause difficulties in user operations, we have been carefully observing this phenomenon for many years. Our observations indicated that the dust trappings could be caused by electric discharges in vacuum ducts. In order to demonstrate this hypothesis experimentally, we designed a new vacuum device that intentionally generates electric discharges and installed it in PF-AR. Using this device, we could repeatedly induce sudden decreases in the beam lifetime because of the generated electric discharge. We also detected decreases in the beam lifetime caused by mechanical movement of the electrodes in the device. Moreover, we could visually observe the dust trapping phenomenon; the trapped dust particle was observed by two video cameras and appeared as a luminous body that resembled a shooting star. This was the first direct observation of a luminous dust particle trapped by the electron beam.

  11. Suprathermal electron studies in Tokamak plasmas by means of diagnostic measurements and modeling

    International Nuclear Information System (INIS)

    Kamleitner, J.

    2015-01-01

    To achieve reactor-relevant conditions in a tokamak plasma, auxiliary heating systems are required and can be realized by waves injected in the plasma that heat ions or electrons. Electron cyclotron resonant heating (ECRH) is a very flexible and robust technique featuring localized power deposition and current drive (CD) capabilities. Its fundamental principles are well understood and the application of ECRH is a proven and established tool; electron cyclotron current drive (ECCD) is regularly used to develop advanced scenarios and control magneto-hydrodynamics (MHD) instabilities in the plasma by tailoring the current profile. There remain important open questions, such as the phase space dynamics, the observed radial broadening of the supra-thermal electron distribution function and discrepancies in predicted and experimental CD efficiency. A main goal is to improve the understanding of wave-particle interaction in plasmas and current drive mechanisms. This was accomplished by combined experimental and numerical studies, strongly based on the conjunction of hard X-ray (HXR) Bremsstrahlung measurements and Fokker-Planck modelling, characterizing the supra-thermal electron population. The hard X-ray tomographic spectrometer (HXRS) diagnostic was developed to perform these studies by investigating spatial HXR emission asymmetries in the co- and counter-current directions and within the poloidal plane. The system uses cadmium-telluride detectors and digital acquisition to store the complete time history of incoming photon pulses. An extensive study of digital pulse processing algorithms was performed and its application allows the HXRS to handle high count rates in a noisy tokamak environment. Numerical tools were developed to improve the time resolution by conditional averaging and to obtain local information with the general tomographic inversion package. The interfaces of the LUKE code and the well-established CQL3D Fokker-Planck code to the Tokamak a

  12. Experimental study of rf pulsed heating

    Directory of Open Access Journals (Sweden)

    Lisa Laurent

    2011-04-01

    Full Text Available Cyclic thermal stresses produced by rf pulsed heating can be the limiting factor on the attainable reliable gradients for room temperature linear accelerators. This is especially true for structures that have complicated features for wakefield damping. These limits could be pushed higher by using special types of copper, copper alloys, or other conducting metals in constructing partial or complete accelerator structures. Here we present an experimental study aimed at determining the potential of these materials for tolerating cyclic thermal fatigue due to rf magnetic fields. A special cavity that has no electric field on the surface was employed in these studies. The cavity shape concentrates the magnetic field on one flat surface where the test material is placed. The materials tested in this study have included oxygen free electronic grade copper, copper zirconium, copper chromium, hot isostatically pressed copper, single crystal copper, electroplated copper, Glidcop®, copper silver, and silver plated copper. The samples were exposed to different machining and heat treatment processes prior to rf processing. Each sample was tested to a peak pulsed heating temperature of approximately 110°C and remained at this temperature for approximately 10×10^{6} rf pulses. In general, the results showed the possibility of pushing the gradient limits due to pulsed heating fatigue by the use of copper zirconium and copper chromium alloys.

  13. Electron-stimulated purification of platinum nanostructures grown via focused electron beam induced deposition

    Directory of Open Access Journals (Sweden)

    Brett B. Lewis

    2015-04-01

    Full Text Available Platinum–carbon nanostructures deposited via electron beam induced deposition from MeCpPt(IVMe3 are purified during a post-deposition electron exposure treatment in a localized oxygen ambient at room temperature. Time-dependent studies demonstrate that the process occurs from the top–down. Electron beam energy and current studies demonstrate that the process is controlled by a confluence of the electron energy loss and oxygen concentration. Furthermore, the experimental results are modeled as a 2nd order reaction which is dependent on both the electron energy loss density and the oxygen concentration. In addition to purification, the post-deposition electron stimulated oxygen purification process enhances the resolution of the EBID process due to the isotropic carbon removal from the as-deposited materials which produces high-fidelity shape retention.

  14. Experimental study of interactions of highly charged ions with atoms at keV energies. Progress report, February 16, 1993--April 15, 1994

    International Nuclear Information System (INIS)

    Kostroun, V.O.

    1994-01-01

    Experimental study of low energy, highly charged ions with other atomic species requires an advanced ion source such as an electron beam ion source, EBIS or an electron cyclotron ion source, ECRIS. Five years ago we finished the design and construction of the Cornell superconducting solenoid, cryogenic EBIS (CEBIS). Since then, this source has been in continuous operation in a program whose main purpose is the experimental study of interactions of highly charged ions with atoms at keV energies. This progress report for the period February 16, 1993 to April 15, 1994 describes the work accomplished during this time in the form of short abstracts

  15. Development and preliminary experimental study on micro-stacked insulator

    International Nuclear Information System (INIS)

    Ren Chengyan; Yuan Weiqun; Zhang Dongdong; Yan Ping; Wang Jue

    2009-01-01

    High gradient insulating technology is one of the key technologies in new type dielectric wall accelerator(DWA). High gradient insulator, namely micro-stacked insulator, was developed and preliminary experimental study was done. Based on the finite element and particle simulating method, surface electric field distribution and electron movement track of micro-stacked insulator were numerated, and then the optimized design proposal was put forward. Using high temperature laminated method, we developed micro-stacked insulator samples which uses exhaustive fluorinated ethylene propylene(FEP) as dielectric layer and stainless steel as metal layer. Preliminary experiment of vacuum surface flashover in nanosecond pulse voltage was done and micro-stacked insulator exhibited favorable vacuum surface flashover performance with flashover field strength of near 180 kV/cm. (authors)

  16. Theoretical study of the electron stopping power in ion planar channeling

    International Nuclear Information System (INIS)

    Haymann, P.

    1974-01-01

    A theory recently developed by the authors for slow and fast electrons is shown to be also applicable to channeled ions and to explain the experimental results about electron loss phenomena as a whole. The theory is based on the fundamental hypothesis of the nonadiabaticity of the ion-target interactions. How essential an exponential form of the interaction pseudo-potential is in explaining the energy exchange mechanism at the walls may be deduced from a quasi-classical development of the quantum model. The theory also allows a number of new experiments to be envisaged in the field of surface electron states [fr

  17. Monte Carlo study of electron relaxation in graphene with spin polarized, degenerate electron gas in presence of electron-electron scattering

    Science.gov (United States)

    Borowik, Piotr; Thobel, Jean-Luc; Adamowicz, Leszek

    2017-12-01

    The Monte Carlo simulation method is applied to study the relaxation of excited electrons in monolayer graphene. The presence of spin polarized background electrons population, with density corresponding to highly degenerate conditions is assumed. Formulas of electron-electron scattering rates, which properly account for electrons presence in two energetically degenerate, inequivalent valleys in this material are presented. The electron relaxation process can be divided into two phases: thermalization and cooling, which can be clearly distinguished when examining the standard deviation of electron energy distribution. The influence of the exchange effect in interactions between electrons with parallel spins is shown to be important only in transient conditions, especially during the thermalization phase.

  18. Substituent influence on the structural, vibrational and electronic properties of 2,5-dihydrothiophene-1,1-dioxide by experimental and DFT methods.

    Science.gov (United States)

    Arjunan, V; Thirunarayanan, S; Durga Devi, G; Mohan, S

    2015-11-05

    Spectroscopic and theoretical quantum chemical studies of 2,5-dihydrothiophene-1,1-dioxide and 3-methyl-2,5-dihydrothiophene-1,1-dioxide have been carried out by FTIR and FT-Raman spectral techniques along with B3LYP methods. The geometry of the compounds have been optimised by B3LYP method with 6-311++G(∗∗) and cc-pVTZ basis sets. The geometrical parameters obtained at B3LYP levels have been compared with the experimental values. Molecular electrostatic potential surface, total electron density distribution and frontier molecular orbital are constructed at B3LYP/cc-pVTZ level to understand the electronic properties. The charge density distribution and sites of chemical reactivity of the molecules have been obtained by mapping electron density isosurface with electrostatic potential surfaces. Natural bond orbital analysis of the molecules are carried out and the occupancies and the atomic hybrid contributions are calculated. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Experimental study on energy distribution of the hot electrons generated by femtosecond laser interacting with solid targets

    International Nuclear Information System (INIS)

    Gu Yuqiu; Zheng Zhijian; Zhou Weimin; Wen Tianshu; Chunyu Shutai; Cai Dafeng; Sichuan Univ., Chengdu; Neijiang Teachers College, Neijiang; Jiao Chunye; Chen Hao; Sichuan Univ., Chengdu; Yang Xiangdong

    2005-01-01

    This paper reports the results of the experiment of hot electron energy distribution during the femtosecond laser-solid target interaction. The hot electrons formed an anisotropic energy distribution. In the direction of the target normal, the energy spectrum of the hot electron was a Maxwellian-like distribution with an effective temperature of 206 keV, which was due to the resonance absorption. In the direction of the specular reflection of laser, there appeared a local plateau of hot electron energy spectrum at the beginning and then it was decreased gradually, which maybe produced by several acceleration mechanisms. The effective temperature and the yield of hot electrons in the direction of the target normal is larger than those in the direction of the specular reflection of laser, which proves that the resonance absorption mechanism is more effective than others. (authors)

  20. Benchmarking Experimental and Computational Thermochemical Data: A Case Study of the Butane Conformers.

    Science.gov (United States)

    Barna, Dóra; Nagy, Balázs; Csontos, József; Császár, Attila G; Tasi, Gyula

    2012-02-14

    Due to its crucial importance, numerous studies have been conducted to determine the enthalpy difference between the conformers of butane. However, it is shown here that the most reliable experimental values are biased due to the statistical model utilized during the evaluation of the raw experimental data. In this study, using the appropriate statistical model, both the experimental expectation values and the associated uncertainties are revised. For the 133-196 and 223-297 K temperature ranges, 668 ± 20 and 653 ± 125 cal mol(-1), respectively, are recommended as reference values. Furthermore, to show that present-day quantum chemistry is a favorable alternative to experimental techniques in the determination of enthalpy differences of conformers, a focal-point analysis, based on coupled-cluster electronic structure computations, has been performed that included contributions of up to perturbative quadruple excitations as well as small correction terms beyond the Born-Oppenheimer and nonrelativistic approximations. For the 133-196 and 223-297 K temperature ranges, in exceptional agreement with the corresponding revised experimental data, our computations yielded 668 ± 3 and 650 ± 6 cal mol(-1), respectively. The most reliable enthalpy difference values for 0 and 298.15 K are also provided by the computational approach, 680.9 ± 2.5 and 647.4 ± 7.0 cal mol(-1), respectively.

  1. Experimental project - Cloud chamber

    International Nuclear Information System (INIS)

    Nour, Elena; Quinchard, Gregory; Soudon, Paul

    2015-01-01

    This document reports an academic experimental project dealing with the general concepts of radioactivity and their application to the cloud room experiment. The author first recalls the history of the design and development of a cloud room, and some definitions and characteristics of cosmic radiation, and proposes a description of the principle and physics of a cloud room. The second part is a theoretical one, and addresses the involved particles, the origins of electrons, and issues related to the transfer of energy (Bremsstrahlung effect, Bragg peak). The third part reports the experimental work with the assessment of a cloud droplet radius, the identification of a trace for each particle (alphas and electrons), and the study of the magnetic field deviation

  2. Analytic model of electron pulse propagation in ultrafast electron diffraction experiments

    International Nuclear Information System (INIS)

    Michalik, A.M.; Sipe, J.E.

    2006-01-01

    We present a mean-field analytic model to study the propagation of electron pulses used in ultrafast electron diffraction experiments (UED). We assume a Gaussian form to characterize the electron pulse, and derive a system of ordinary differential equations that are solved quickly and easily to give the pulse dynamics. We compare our model to an N-body numerical simulation and are able to show excellent agreement between the two result sets. This model is a convenient alternative to time consuming and computationally intense N-body simulations in exploring the dynamics of UED electron pulses, and as a tool for refining UED experimental designs

  3. Electron optical study of the Venus Express ASPERA-4 Electron Spectrometer (ELS) top-hat electrostatic analyser

    International Nuclear Information System (INIS)

    Collinson, Glyn A; Kataria, D O; Coates, Andrew J; Tsang, Sharon M E; Arridge, Christopher S; Lewis, Gethyn R; Frahm, Rudy A; Winningham, J David; Barabash, Stas

    2009-01-01

    The performance of the Venus Express (VEX) ASPERA-4 Electron Spectrometer (ELS) is different from the nominal response shown by the ASPERA-3 ELS aboard Mars Express due to machining tolerance. Up to now, the precise mechanism for this was unknown and, therefore, the results of the experimental calibration could not be supported with a theoretical understanding of the fundamental instrument science behind the device. In this study, we show that the difference is due to a misalignment of the inner hemisphere and a widening of the entrance aperture of the instrument. The response of the VEX ELS can be approximated by a combination of a vertical offset of the inner hemisphere of ≈0.6 mm and a lateral offset of less than 0.125 mm, combined with an aperture that is ≈0.54 mm wider than nominal. The resulting K-factor, geometric factor, energy resolution and peak elevation are in good agreement with those observed experimentally. Therefore, we now have a good agreement between both laboratory calibration data and computer simulation, giving a firm foundation for future scientific data analysis

  4. Experimental Electron Density Distribution in Two Cocrystals of Betaines with p-Hydroxybenzoic Acid

    Directory of Open Access Journals (Sweden)

    Agata Owczarzak

    2018-03-01

    Full Text Available Experimental determination of electron density distribution in crystals by means of high-resolution X-ray diffraction allows, among others, for studying the details of intra- and inter-molecular interactions. In case of co-crystals, this method may help in finding the conditions of creating such species. The results of such analysis for two co-crystals containing betaines, namely trigonelline (TRG: nicotinic acid N-methylbetaine, IUPAC name: 1-methylpyridinium-3-carboxylate and N-methylpiperidine betaine (MPB: 1-methylpiperidinium-1-yl-carboxylate with p-hydroxybenzoic acid (HBA are reported. TRG-HBA crystallizes as a hydrate. For both of the co-crystals, high-quality diffraction data were collected up to sinθ/λ = 1.13 Å−1. Hansen-Coppens multipolar model was then applied for modelling the electron density distribution and Atoms-In-Molecules approach was used for detailed analysis of interactions in crystals. A number of intermolecular interactions was identified, ranging from strong O-H···O hydrogen bonds through C-H···O to C-H···π and π···π interactions. Correlations between the geometrical characteristics of the contacts and the features of their critical points were analyzed in detail. Atomic charges show that in zwitterionic species there are regions of opposite charges, rather than charges that are localized on certain atoms. In case of MPB-HBA, a significant charge transfer between the components of co-crystal (0.5 e was found, as opposed to TRG-HBA, where all of the components are almost neutral.

  5. Study and realization of an electron linear accelerator. Dynamics of accelerated electrons; Etude et realisation d'un accelerateur lineaire d'electrons. Dynamique des electrons acceleres

    Energy Technology Data Exchange (ETDEWEB)

    Bernard, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-04-01

    The theoretical characteristics of the electron linear accelerator are: 30 MeV for the energy W{sub S} and 250 mA for the peak current I{sub c}. The main utilization is the intense production of fast neutrons by the reactions ({gamma},n) and ({gamma},f) induced in a target of natural uranium by the accelerated electrons. In the first part of the thesis, relative to the study and the realization of the accelerator, a new equation of dispersion is established analytically when the guide is loaded with round-edged irises. The relation is compared with the equation established by CHU and Hansen, WALKINSHAW, KVASIL in the case of a guide loaded with flat-edged irises. The experimental and theoretical curves of dispersion are compared. The accuracy of every relation of dispersion is estimated. The second part of the thesis is relative to the theoretical study of the electrons dynamics in the guide; it allows the derivation of the parameters of the beam: dispersion of phase, energy, dispersion of energy and the relation W{sub S} = f (I{sub c}). The results relative to the first experiments are given and compared with the theoretical expectations. (author) [French] Les caracteristiques nominales theoriques de l'accelerateur lineaire d'electrons sont: 30 MeV pour l'energie W{sub S} et 250 mA pour le courant de crete I{sub c}. L'utilisation principale envisagee est la production de neutrons rapides par les reactions ({gamma},n) et ({gamma},f) induites dans une cible d'uranium naturel par les electrons acceleres. Dans la premiere partie de la these relative a l'elude et a la realisation de l'accelerateur, une nouvelle equation de dispersion (ou equation aux frequences) est etablie analytiquement pour un guide charge par des iris a bord rond. Cette relation est comparee a celles etablies par CHU et HANSEN, WALKINSHAW, KVASIL dans le cas du guide charge par des iris a bord plat. On compare les courbes de dispersion theoriques et experimentales et on evalue la precision de

  6. All-electron study of ultra-incompressible superhard material ReB2: structural and electronic properties

    International Nuclear Information System (INIS)

    Yan-Ling, Li; Guo-Hua, Zhong; Zhi, Zeng

    2009-01-01

    This paper investigates the structural and electronic properties of rhenium diboride by first-principles calculation based on density functional theory. The obtained results show that the calculated equilibrium structural parameters of ReB 2 are in excellent agreement with experimental values. The calculated bulk modulus is 361 GPa in comparison with that of the experiment. The compressibility of ReB 2 is lower than that of well-known OsB 2 . The anisotropy of the bulk modulus is confirmed by c/a ratio as a function of pressure curve and the bulk modulus along different axes along with the electron density distribution. The high bulk modulus is attributed to the strong covalent bond between Re-d and B-p orbitals and the wider pseudogap near the Fermi level, which could be deduced from both electron charge density distribution and density of states. The band structure and density of states of ReB 2 exhibit that this material presents metallic behavior. The good metallicity and ultra-incompressibility of ReB 2 might suggest its potential application as pressure-proof conductors. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  7. Beam dynamics study of a 30 MeV electron linear accelerator to drive a neutron source

    Science.gov (United States)

    Kumar, Sandeep; Yang, Haeryong; Kang, Heung-Sik

    2014-02-01

    An experimental neutron facility based on 32 MeV/18.47 kW electron linac has been studied by means of PARMELA simulation code. Beam dynamics study for a traveling wave constant gradient electron accelerator is carried out to reach the preferential operation parameters (E = 30 MeV, P = 18 kW, dE/E E-gun, pre-buncher, buncher, and 2 accelerating columns. A disk-loaded, on-axis-coupled, 2π/3-mode type accelerating rf cavity is considered for this linac. After numerous optimizations of linac parameters, 32 MeV beam energy is obtained at the end of the linac. As high electron energy is required to produce acceptable neutron flux. The final neutron flux is estimated to be 5 × 1011 n/cm2/s/mA. Future development will be the real design of a 30 MeV electron linac based on S band traveling wave.

  8. Studies of Electron Transport and Isochoric Heating and Their Applicability to Fast Ignition

    International Nuclear Information System (INIS)

    Key, M H; Amiranoff, F; Andersen, C; Batani, D; Baton, S D; Cowan, T; Fisch, N; Freeman, R; Gremillet, L; Hall, T; Hatchett, S; Hill, J; King, J; Kodama, R; Koch, J; Koenig, M; Lasinski, B; Langdon, B; MacKinnon, A; Martinolli, E; Norreys, P; Parks, P; Perrelli-Cippo, E; Rabec Le Gloahec, M; Rosenbluth, M; Rousseaux, C; Santon, J J; Scianitti, F; Snavely, R; Tabak, M; Tanaka, K; Town, R; Tsutumi, T; Stephens, R

    2003-01-01

    Experimental measurements of electron transport and isochoric heating in 100 J, 1 ps laser irradiation of solid A1 targets are presented. Modeling with a hybrid PIC code is compared with the data and good agreement is obtained using a heuristic model for the electron injection. The relevance for fast ignition is discussed

  9. a Study on SODIUM(110) and Other Nearly Free Electron Metals Using Angle Resolved Photoemission Spectroscopy.

    Science.gov (United States)

    Lyo, In-Whan

    Electronic properties of the epitaxially grown Na(110) film have been studied using angle resolved ultraviolet photoemission spectroscopy with synchrotron radiation as the light source. Na provides an ideal ground to study the fundamental aspects of the electron-electron interactions in metals, because of its simple Fermi surface and small pseudopotential. The absolute band structure of Na(110) using angle resolved photoemission spectroscopy has been mapped out using the extrema searching method. The advantage of this approach is that the usual assumption of the unoccupied state dispersion is not required. We have found that the dispersion of Na(1l0) is very close to the parabolic band with the effective mass 1.21 M_{rm e} at 90 K. Self-consistent calculations of the self-energy for the homogeneous electron gas have been performed using the Green's function technique within the framework of the GW approximation, in the hope of understanding the narrowing mechanism of the bandwidth observed for all the nearly-free-electron (NFE) metals. Good agreements between the experimental data and our calculated self-energy were obtained not only for our data on k-dependency from Na(l10), but also for the total bandwidth corrections for other NFE metals, only if dielectric functions beyond the random phase approximation were used. Our findings emphasize the importance of the screening by long wavelength plasmons. Off-normal spectra of angle resolved photoemission from Na(110) show strong asymmetry of the bulk peak intensity for the wide range of photon energies. Using a simple analysis, we show this asymmetry has an origin in the interference of the surface Umklapp electrons with the normal electrons. We have also performed the detailed experimental studies of the anomalous Fermi level structure observed in the forbidden gap region of Na. This was claimed by A. W. Overhauser as the evidence of the charge density wave in the alkali metal. The possibility of this hypothesis is

  10. Plasma channels for electron beam transport

    International Nuclear Information System (INIS)

    Schneider, R.F.; Smith, J.R.; Moffatt, M.E.; Nguyen, K.T.; Uhm, H.S.

    1988-01-01

    In recent years, there has been much interest in transport of intense relativistic electron beams using plasma channels. These channels are formed by either: ionization of an organic gas by UV photoionization or electron impact ionization of a low pressure gas utilizing a low energy (typically several hundred volts) electron gun. The second method is discussed here. As their electron gun, the authors used a 12 volt lightbulb filament which is biased to -400 volts with respect to the grounded 15 cm diameter drift tube. The electrons emitted from the filament are confined by an axial magnetic field of --100 Gauss to create a plasma channel which is less than 1 cm in radius. The channel density has been determined with Langmuir probes and the resulting line densities were found to be 10 11 to 10 12 per cm. When a multi-kiloamp electron beam is injected onto this channel, the beam space charge will eject the plasma electrons leaving the ions behind to charge neutralize the electron beam, hence allowing the beam to propagate. In this work, the authors performed experimental studies on the dynamics of the plasma channel. These include Langmuir probe measurements of a steady state (DC) channel, as well as time-resolved Langmuir probe studies of pulsed channels. In addition they performed experimental studies of beam propagation in these plasma channels. Specifically, they observed the behavior of current transport in these channels. Detailed results of beam transport and channel studies are presented

  11. Simultaneous electrochemical-electron spin resonance studies of carotenoid cation radicals and dications

    International Nuclear Information System (INIS)

    Khaled, M.; Hadjipetrou, A.; Xinhai Chen; Kispert, L.

    1989-01-01

    Carotenoids are present in the chloroplasts of photosynthetic green plants and serve as photoprotect devices and antenna pigments, and active role in the photosynthetic electron-transport chain with the carotenoid cation radical as an integral part of the electron-transfer process. The research reported herein has confirmed that carotenoid cation radicals have a lifetime that is sensitive to solvent, being longest in CH 2 Cl 2 and are best prepared electrochemically. Semiempirical AM1 and INDO calculations of the trans and cis isomers of β-carotene, canthaxanthin and β-apo-8'-carotenal cation radicals predicted the unresolved EPR line whose linewidth varies to a measurable degree with carotenoid, which subsequent experimental observations affirmed. Simultaneous electrochemical - electron spin resonance studies of carotenoid cation radicals and dications have shown the radicals detected by EPR are formed by the one electron oxidation of the carotenoid, that dimers are not formed upon decay of the radical cations and an estimate of the rate of comproportionation as a function of carotenoid can be given. The formal rate constant K' for heterogenous electron transfer rate at the electrode surface has been deduced from rotating disc experiments. Upon deuteration, and in the presence of excess β-carotene, the half-life for decay of the carotenoid radical cation increased an order of magnitude due to the reaction between diffusion carotenoid dications and carotenoids to form additional radical cations. The carotenoid diffusion coefficients deduced by chronocoulometry substantiates this measurement. The produces formed upon electrochemical studies are being studied by HPLC and the isomers formed thermally are being separated. Additional radical reactions are currently being studied by EPR and electrochemical methods

  12. Redox Chemistry of Bis(pyrrolyl)pyridine Chromium and Molybdenum Complexes: An Experimental and Density Functional Theoretical Study.

    Science.gov (United States)

    Gowda, Anitha S; Petersen, Jeffrey L; Milsmann, Carsten

    2018-02-19

    The three- and four-membered redox series [Cr( Me PDP) 2 ] z (z = 1-, 2-, 3-) and [Mo( Me PDP) 2 ] z (z = 0, 1-, 2-, 3-) were synthesized to study the redox properties of the pincer ligand Me PDP 2- (H 2 Me PDP = 2,6-bis(5-methyl-3-phenyl-1H-pyrrol-2-yl)pyridine). The monoanionic complexes were characterized by X-ray crystallography, UV/vis/NIR spectroscopy, and magnetic susceptibility measurements. Experimental and density functional theory (DFT) studies are consistent with closed-shell Me PDP 2- ligands and +III oxidation states (d 3 , S = 3/2) for the central metal ions. Cyclic voltammetry established multiple reversible redox processes for [M( Me PDP) 2 ] 1- (M = Cr, Mo), which were further investigated via chemical oxidation and reduction. For molybdenum, one-electron oxidation yielded Mo( Me PDP) 2 which was characterized by X-ray crystallography, UV/vis/NIR, and magnetic susceptibility measurements. The experimental and computational data indicate metal-centered oxidation to a Mo IV complex (d 2 , S = 1) with two Me PDP 2- ligands. In contrast, one- and two-electron reductions were found to be ligand centered resulting in the formation of Me PDP •3- radicals, in which the unpaired electron is predominantly located on the central pyridine ring of the ligand. The presence of ligand radicals was established experimentally by observation of ligand-to-ligand intervalence charge transfer (LLIVCT) bands in the UV/vis/NIR spectra of the dianionic and trianionic complexes and further supported by broken-symmetry DFT calculations. X-ray crystallographic analyses of the one-electron-reduced species [M( Me PDP) 2 ] 2- (S = 1, M = Cr, Mo) established structural indicators for pincer reduction and showed localization of the radical on one of the two pincer ligands. The two-electron-reduced, trianionic complexes (S = 1/2) were characterized by UV/vis/NIR spectroscopy, magnetic susceptibility measurements, and EPR spectroscopy. The electronic structures of the reduced

  13. An experimental attenuation plate to improve the dose distribution in intraoperative electron beam radiotherapy for breast cancer.

    Science.gov (United States)

    Oshima, T; Aoyama, Y; Shimozato, T; Sawaki, M; Imai, T; Ito, Y; Obata, Y; Tabushi, K

    2009-06-07

    Intraoperative electron beam radiotherapy (IOERT) is a technique in which a single-fraction high dose is intraoperatively delivered to subclinical tumour cells using an electron beam after breast-conserving surgery. In IOERT, an attenuation plate consisting of a pair of metal disks is commonly used to protect the normal tissues posterior to the breast. However, the dose in front of the plate is affected by backscatter, resulting in an unpredictable delivered dose to the tumour cells. In this study, an experimental attenuation plate, termed a shielding plate, was designed using Monte Carlo simulation, which significantly diminished the electron beam without introducing any backscatter radiation. The plate's performance was verified by measurements. It was made of two layers, a first layer (source side) of polymethyl methacrylate (PMMA) and a second layer of copper, which was selected from among other metals (aluminium, copper and lead) after testing for shielding capability and the range and magnitude of backscatter. The optimal thicknesses of the PMMA (0.71 cm) and copper (0.3 cm) layers were determined by changing their thicknesses during simulations. On the basis of these results, a shielding plate was prototyped and depth doses with and without the plate were measured by radiophotoluminescence glass dosimeters using a conventional stationary linear accelerator and a mobile linear accelerator dedicated for IOERT. The trial shielding plate functioned as intended, indicating its applicability in clinical practice.

  14. Experimental and theoretical studies of manganite and magnetite compounds

    International Nuclear Information System (INIS)

    Srinitiwarawong, Chatchai

    2002-01-01

    In the recent years interest in the transition oxide compounds has renewed among researchers in the field of condensed matter physics. This thesis presents the studies of the two families of the transition oxides, the manganite and magnetite compounds. Manganite has regained the interest since the discovery of the large magnetoresistance around its Curie temperature in 1990s. Magnetite on the other hand is the oldest magnetic material known to man however some of its physical properties are still controversial. The experimental works address some basic properties of these compounds when fabricated in the form of thin films. These include the resistivity measurements and magnetic measurements as well as the Hall effect. The various models of transport mechanism have been compared. The magnetic field and the temperature dependence of magnetoresistance have also been studied. Simple devices such as an artificial grain boundary and bilayers thin film have been investigated. The second part of this thesis concentrates on the theoretical aspects of the fundamental physics behind these two compounds. The problem of electrons tunnelling between the magnetite electrodes has been addressed taking into account the surface effect with distortion. The last chapter presents a theoretical study of the spinless-Hubbard model which is the simplest approximation of the conduction electrons in magnetite and manganite. The results are obtained from the Hartree-Fock and the Hubbard-I approximations as well as the exact diagonalisation method. (author)

  15. Primary experimental studies on mid-infrared FEL irradiation on dental substances at BFEL

    CERN Document Server

    Biao, Z J; Gao Xue Ju; He Wei; Huang Yu Ying; Li Yong Gui; LiuNianQing; Wang Min Kai; Wu Gan; Yan Xue Pin; Zhang Guo Qing

    2001-01-01

    A free electron laser (FEL) with its characteristics of wide wavelength tunability, ultrashort pulse time structure, and high peak power density is predominantly superior to all other conventional lasers in applications. Several experimental studies on mid-infrared FEL irradiation on dental enamel and dentine were performed at the Beijing FEL. Experimental aims were to investigate changes in the hardness, ratios of P to Ca and Cs before and after irradiation on samples with a characteristic absorption wavelength of 9.66 mu m, in the colors of these sample surfaces after irradiation with different wavelengths around the peak wavelength. The time dependence of temperature of the dentine sample was measured with its ps pulse effects compared to that with a continuous CO sub 2 laser. FTIR absorption spectra in the range of 2.5-15.4 mu m for samples of these hard dental substances and pure hydroxyapatite were first examined to decide their chemical components and absorption maximums. Primary experimental results w...

  16. The order-disorder transition in Cu{sub 2}ZnSnS{sub 4}: A theoretical and experimental study

    Energy Technology Data Exchange (ETDEWEB)

    Quennet, Marcel, E-mail: marcel.quennet@fu-berlin.de [Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Institut für Chemie und Biochemie, Freie Universität Berlin, Takustraße 3, 14195 Berlin (Germany); Ritscher, Anna [Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin (Germany); Lerch, Martin [Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin (Germany); Paulus, Beate [Institut für Chemie und Biochemie, Freie Universität Berlin, Takustraße 3, 14195 Berlin (Germany)

    2017-06-15

    In this work the Cu/Zn order-disorder transition in Cu{sub 2}ZnSnS{sub 4} kesterites on Wyckoff positions 2c and 2d was investigated by a structural and electronic analysis in theory and experiment. For experimental investigations stoichiometric samples with different Cu/Zn order, annealed in the temperature range of 473–623 K and afterwards quenched, were used. The optical gaps were determined using the Derivation of Absorption Spectrum Fitting (DASF) method. Furthermore, the order-disorder transition was examined by DFT calculations for a closer analysis of the origins of the reduced band gap, showing a good agreement with experimental data with respect to structural and electronic properties. Our studies show a slight increase of lattice parameter c in the kesterite lattice with increasing disorder. Additionally, a reduced band gap was observed with increasing disorder, which is an effect of newly occurring binding motifs in the disordered kesterite structure. - Highlights: • Experimental and theoretical investigation on the order-disorder transition in kesterites. • Slight enlargements of lattice constants due to disorder in experiment and theory. • Strong band gap fluctuations with decreasing order. • Electronic structure deviations due to changing binding motifs. • Disorder as possible main source of low open-circuit voltages.

  17. Experimental transition probabilities for several spectral lines arising from the 5d10 6s{8s, 7p, 5f, 5g} electronic configurations of Pb III

    International Nuclear Information System (INIS)

    Alonso-Medina, A.

    2010-01-01

    Transition probabilities for 30 spectral lines, arising from the 5d 10 6s{8s, 7p, 5f, 5g} electronic configurations of Pb III (20 measured for the first time), have been experimentally determined from measurements of emission line intensities in a plasma lead induced by ablation with a Nd:YAG laser. The line intensities were obtained with the target placed in molecular argon at 6 Torr, recorded at a 400 ns delay from the laser pulse, which provides appropriate measurement conditions, and analysed between 200 and 700 nm. They are measured when the plasma reaches local thermodynamic equilibrium (LTE). The plasma under study had an electron temperature (T) of 21,400 K and an electron number density (N e ) of 7x10 16 cm -3 . The influence of self-absorption has been estimated for every line, and plasma homogeneity has been checked. The values obtained were compared with previous experimental values and theoretical estimates where possible.

  18. ELECTRONIC SYSTEM FOR EXPERIMENTATION IN AC ELECTROGRAVIMETRY II: IMPLEMENTED DESIGN

    Directory of Open Access Journals (Sweden)

    Robinson Torres

    2007-06-01

    Full Text Available A detailed description of the electronic system designed to improve the measurements in an experimental AC electrogravimetry setup is presented. This system is committed to acquire appropriated data for determining the Electrogravimetric Transfer Function (EGTF and provide information regarding the mass transfer in an electrochemical cell in the AC Electrogravimetry Technique, but maintaining a good trade-off between the locking frequency bandwidth and the resolution in the frequency tracking, that is, enlarging the bandwidth of the system to follow signals with frequency as higher as 1 kHz, but maintaining an accurate and continuous tracking of this signal. The enlarged bandwidth allows the study of fast kinetic process in electrochemical applications and the continuous tracking let to achieve a precise measurement with good resolution rather than average frequency records obtained by conventional frequency meters. The system is based on an Analogue-Digital Phase Locked Loop (A-D PLL.En este artículo se presenta una descripción detallada del sistema electrónico diseñado para mejorar las medidas en un sistema experimental de electrogravimetría AC. El sistema diseñado se encarga de adquirir los datos adecuados para determinar la función de transferencia electrogravimétrica (EGTF y proveer información relacionada con la transferencia de masa en una celda electroquímica en la técnica de electrogravimetría AC, pero manteniendo un buen compromiso entre el ancho de banda de enganche y la resolución en el seguimiento de la frecuencia, es decir, el sistema incrementa el ancho de banda para permitir el seguimiento de señales con frecuencias hasta de 1 kHz, pero conservando un exacto y continuo seguimiento de esta señal. El aumento del ancho de banda permite el estudio de procesos con una cinética rápida en aplicaciones electroquímicas y el seguimiento continuo de la señal permite la obtención de medidas precisas con buena resoluci

  19. Beam studies and experimental facility for the AWAKE experiment at CERN

    CERN Document Server

    Bracco, Chiara; Petrenko, Alexey; Timko, Helga; Argyropoulos, Theodoros; Bartosik, Hannes; Bohl, Thomas; Esteban Müller, Juan; Goddard, Brennan; Meddahi, Malika; Pardons, Ans; Shaposhnikova, Elena; Velotti, Francesco M; Vincke, Helmut

    2014-01-01

    A Proton Driven Plasma Wakefield Acceleration Experiment has been proposed as an approach to eventually accelerate an electron beam to the TeV energy range in a single plasma section. To verify this novel technique, a proof of principle R&D experiment, AWAKE, is planned at CERN using 400 GeV proton bunches from the SPS. An electron beam will be injected into the plasma cell to probe the accelerating wakefield. The AWAKE experiment will be installed in the CNGS facility profiting from existing infrastructure where only minor modifications need to be foreseen. The design of the experimental area and the proton and electron beam lines are shown. The achievable SPS proton bunch properties and their reproducibility have been measured and are presented.

  20. Beijing Experimental Electronic Musicians on the Phenomenon of Commercialization and Tourism in the Contemporary Chinese Art

    Directory of Open Access Journals (Sweden)

    Matic Urbanija

    2014-12-01

    Full Text Available The article provides opinions of some Beijing experimental electronic musicians about the situation of contemporary art in China and in the world, primarily about the background of the so called Christmas performance in Art District 798's gallery UCCA in Beijing. This was a sort of protest against destroying art with commercialization as the only measure of art gallery's success. The article first describes the situation of contemporary art in the world at the beginning of 21st century as it is described in Julian Stallabrass' book Art Incorporated. It can be deduced from the words of experimental electronic musicians in Beijing that the situation is similar in China. During the debate about the Christmas performance in UCCA gallery, a problem with galleries was emphasize. These became more similar to tourist venues than places for enriching one's thoughts and awareness about the world surrounding us, through artwork. Therefore, the Christmas performance tried to express this sentiment. It offered visitors a tourist show brought to the point of absurd. The employees and the leader of UCCA couldn't comprehend the symbolic meaning of this happening, which, symbolically, took place on Christmas, the most commercialized holiday in the West as well as in China.

  1. Spatial distribution of charged particles along the ion-optical axis in electron cyclotron resonance ion sources. Experimental results

    International Nuclear Information System (INIS)

    Panitzsch, Lauri

    2013-01-01

    The experimental determination of the spatial distribution of charged particles along the ion-optical axis in electron cyclotron resonance ion sources (ECRIS) defines the focus of this thesis. The spatial distributions of different ion species were obtained in the object plane of the bending magnet (∼45 cm downstream from the plasma electrode) and in the plane of the plasma electrode itself, both in high spatial resolution. The results show that each of the different ion species forms a bloated, triangular structure in the aperture of the plasma electrode. The geometry and the orientation of these structures are defined by the superposition of the radial and axial magnetic fields. The radial extent of each structure is defined by the charge of the ion. Higher charge states occupy smaller, more concentrated structures. The total current density increases towards the center of the plasma electrode. The circular and star-like structures that can be observed in the beam profiles of strongly focused, extracted ion beams are each dominated by ions of a single charge state. In addition, the spatially resolved current density distribution of charged particles in the plasma chamber that impinge on the plasma electrode was determined, differentiating between ions and electrons. The experimental results of this work show that the electrons of the plasma are strongly connected to the magnetic field lines in the source and thus spatially well confined in a triangular-like structure. The intensity of the electrons increases towards the center of the plasma electrode and the plasma chamber, as well. These electrons are surrounded by a spatially far less confined and less intense ion population. All the findings mentioned above were already predicted in parts by simulations of different groups. However, the results presented within this thesis represent the first (and by now only) direct experimental verification of those predictions and are qualitatively transferable to other

  2. Spatial distribution of charged particles along the ion-optical axis in electron cyclotron resonance ion sources. Experimental results

    Energy Technology Data Exchange (ETDEWEB)

    Panitzsch, Lauri

    2013-02-08

    The experimental determination of the spatial distribution of charged particles along the ion-optical axis in electron cyclotron resonance ion sources (ECRIS) defines the focus of this thesis. The spatial distributions of different ion species were obtained in the object plane of the bending magnet ({approx}45 cm downstream from the plasma electrode) and in the plane of the plasma electrode itself, both in high spatial resolution. The results show that each of the different ion species forms a bloated, triangular structure in the aperture of the plasma electrode. The geometry and the orientation of these structures are defined by the superposition of the radial and axial magnetic fields. The radial extent of each structure is defined by the charge of the ion. Higher charge states occupy smaller, more concentrated structures. The total current density increases towards the center of the plasma electrode. The circular and star-like structures that can be observed in the beam profiles of strongly focused, extracted ion beams are each dominated by ions of a single charge state. In addition, the spatially resolved current density distribution of charged particles in the plasma chamber that impinge on the plasma electrode was determined, differentiating between ions and electrons. The experimental results of this work show that the electrons of the plasma are strongly connected to the magnetic field lines in the source and thus spatially well confined in a triangular-like structure. The intensity of the electrons increases towards the center of the plasma electrode and the plasma chamber, as well. These electrons are surrounded by a spatially far less confined and less intense ion population. All the findings mentioned above were already predicted in parts by simulations of different groups. However, the results presented within this thesis represent the first (and by now only) direct experimental verification of those predictions and are qualitatively transferable to

  3. Electron-electron interactions in disordered systems

    CERN Document Server

    Efros, AL

    1985-01-01

    ``Electron-Electron Interactions in Disordered Systems'' deals with the interplay of disorder and the Coulomb interaction. Prominent experts give state-of-the-art reviews of the theoretical and experimental work in this field and make it clear that the interplay of the two effects is essential, especially in low-dimensional systems.

  4. Electronic band structures of binary skutterudites

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Banaras [Center for Computational Materials Science, University of Malakand, Chakdara (Pakistan); Department of Physics, University of Malakand, Chakdara (Pakistan); Aliabad, H.A. Rahnamaye [Department of Physics, Hakim Sabzevari University, Sabzevar (Iran, Islamic Republic of); Saifullah [Center for Computational Materials Science, University of Malakand, Chakdara (Pakistan); Department of Physics, University of Malakand, Chakdara (Pakistan); Jalali-Asadabadi, S. [Department of Physics, Faculty of Science, University of Isfahan (UI), 81744 Isfahan (Iran, Islamic Republic of); Khan, Imad [Center for Computational Materials Science, University of Malakand, Chakdara (Pakistan); Department of Physics, University of Malakand, Chakdara (Pakistan); Ahmad, Iftikhar, E-mail: ahma5532@gmail.com [Center for Computational Materials Science, University of Malakand, Chakdara (Pakistan); Department of Physics, University of Malakand, Chakdara (Pakistan)

    2015-10-25

    The electronic properties of complex binary skutterudites, MX{sub 3} (M = Co, Rh, Ir; X = P, As, Sb) are explored, using various density functional theory (DFT) based theoretical approaches including Green's Function (GW) as well as regular and non-regular Tran Blaha modified Becke Jhonson (TB-mBJ) methods. The wide range of calculated bandgap values for each compound of this skutterudites family confirm that they are theoretically as challenging as their experimental studies. The computationally expensive GW method, which is generally assume to be efficient in the reproduction of the experimental bandgaps, is also not very successful in the calculation of bandgaps. In this article, the issue of the theoretical bandgaps of these compounds is resolved by reproducing the accurate experimental bandgaps, using the recently developed non-regular TB-mBJ approach, based on DFT. The effectiveness of this technique is due to the fact that a large volume of the binary skutterudite crystal is empty and hence quite large proportion of electrons lie outside of the atomic spheres, where unlike LDA and GGA which are poor in the treatment of these electrons, this technique properly treats these electrons and hence reproduces the clear electronic picture of these compounds. - Highlights: • Theoretical and experimental electronic band structures of binary skutterudites are reviewed. • The literature reveals that none of the existing theoretical results are consistent with the experiments. • GW, regular and non-regular TB-mBJ methods are used to reproduce the correct results. • The GW and regular TB-mBJ results are better than the available results in literature. • However, non-regular TB-mBJ reproduces the correct experimental band structures.

  5. Electronic band structures of binary skutterudites

    International Nuclear Information System (INIS)

    Khan, Banaras; Aliabad, H.A. Rahnamaye; Saifullah; Jalali-Asadabadi, S.; Khan, Imad; Ahmad, Iftikhar

    2015-01-01

    The electronic properties of complex binary skutterudites, MX 3 (M = Co, Rh, Ir; X = P, As, Sb) are explored, using various density functional theory (DFT) based theoretical approaches including Green's Function (GW) as well as regular and non-regular Tran Blaha modified Becke Jhonson (TB-mBJ) methods. The wide range of calculated bandgap values for each compound of this skutterudites family confirm that they are theoretically as challenging as their experimental studies. The computationally expensive GW method, which is generally assume to be efficient in the reproduction of the experimental bandgaps, is also not very successful in the calculation of bandgaps. In this article, the issue of the theoretical bandgaps of these compounds is resolved by reproducing the accurate experimental bandgaps, using the recently developed non-regular TB-mBJ approach, based on DFT. The effectiveness of this technique is due to the fact that a large volume of the binary skutterudite crystal is empty and hence quite large proportion of electrons lie outside of the atomic spheres, where unlike LDA and GGA which are poor in the treatment of these electrons, this technique properly treats these electrons and hence reproduces the clear electronic picture of these compounds. - Highlights: • Theoretical and experimental electronic band structures of binary skutterudites are reviewed. • The literature reveals that none of the existing theoretical results are consistent with the experiments. • GW, regular and non-regular TB-mBJ methods are used to reproduce the correct results. • The GW and regular TB-mBJ results are better than the available results in literature. • However, non-regular TB-mBJ reproduces the correct experimental band structures

  6. Plasma Electronics. Theoretical and Experimental Investigations of Plasma Nonlinearity in the Powerful Microwave Oscillators

    International Nuclear Information System (INIS)

    Bliokh, Yu.P.

    2001-01-01

    During more than 50 years of Plasma Electronics development a great number of experimental and theoretical results have been achieved. These results allow understanding of physical processes which originate under charged particles beams interaction with a plasma. However, one essential aspect of such interaction remains insufficiently studied. The question is about a correlation between conditions of microwave excitation by a beam in plasma and plasma parameters. Each of these effects, namely the influence of plasma parameters on conditions of microwave excitation by a beam and plasma parameters variations under the influence of propagating microwave radiation are well known and investigated enough. However their common action under beam-plasma instability (BPI) development were not studied systematically, although the role of such reciprocal influence on character of these processes may be very large. The aim of this report is a review of recent theoretical and experimental investigations of such plasma nonlinearity in plasma-filled trawling-wave tubes. N.M.Zemlyansky and E.A.Kornilov have done experiments in Kharkov Institute of Physics and Technology (KhPhTI). Development of the theoretical model was started in KhPhTI (Yu.P.Bliokh, Ya.B.Fainberg, M.G.Lyubarsky, and V.O.Podobinsky) and continues by author in Technion. The developed theory takes into account two main reasons of the plasma density redistribution: high frequency pressure (HFP) force which ''push out'' plasma from the regions with increased microwave amplitude, or microwave discharge, which appears in the region where amplitude is large enough. Displaced (under HFP action) or additionally originating (under (BPD) development) plasma propagates from the disturbance source in the form of slow plasma waves (for example, ion-sound or magneto-sound waves), and the BPI develops in the nonhomogeneous plasma. It changes both magnitude and longitudinal distribution of excited microwave amplitude. As a result

  7. TH-CD-201-06: Experimental Characterization of Acoustic Signals Generated in Water Following Clinical Photon and Electron Beam Irradiation

    International Nuclear Information System (INIS)

    Hickling, S; El Naqa, I

    2016-01-01

    Purpose: Previous work has demonstrated the detectability of acoustic waves induced following the irradiation of high density metals with radiotherapy linac photon beams. This work demonstrates the ability to experimentally detect such acoustic signals following both photon and electron irradiation in a more radiotherapy relevant material. The relationship between induced acoustic signal properties in water and the deposited dose distribution is explored, and the feasibility of exploiting such signals for radiotherapy dosimetry is demonstrated. Methods: Acoustic waves were experimentally induced in a water tank via the thermoacoustic effect following a single pulse of photon or electron irradiation produced by a clinical linac. An immersion ultrasound transducer was used to detect these acoustic waves in water and signals were read out on an oscilloscope. Results: Peaks and troughs in the detected acoustic signals were found to correspond to the location of gradients in the deposited dose distribution following both photon and electron irradiation. Signal amplitude was linearly related to the dose per pulse deposited by photon or electron beams at the depth of detection. Flattening filter free beams induced large acoustic signals, and signal amplitude decreased with depth after the depth of maximum dose. Varying the field size resulted in a temporal shift of the acoustic signal peaks and a change in the detected signal frequency. Conclusion: Acoustic waves can be detected in a water tank following irradiation by linac photon and electron beams with basic electronics, and have characteristics related to the deposited dose distribution. The physical location of dose gradients and the amount of dose deposited can be inferred from the location and magnitude of acoustic signal peaks. Thus, the detection of induced acoustic waves could be applied to photon and electron water tank and in vivo dosimetry. This work was supported in part by CIHR grants MOP-114910 and MOP

  8. Experimental study on iodine chemistry (EXSI) - Containment experiments with methyl iodide

    Energy Technology Data Exchange (ETDEWEB)

    Holm, J.; Glaenneskog, H.; Ekberg, C. (Chalmers Univ. of Technology (Sweden)); Kaerkelae, T.; Auvinen, A. (VTT Technical Research Centre of Finland (Finland))

    2010-05-15

    An experimental study on radiolytic decomposition of methyl iodide was conducted in co-operation between VTT and Chalmers University of Technology as a part of the NKS-R programs. The behaviour of iodine during a severe accident has been studied in several experimental programs, ranging from the large-scale PHEBUS FP tests and intermediate-scale ThAI tests to numerous separate effect studies. In year 2008 the NROI project, a Nordic collaboration studying iodine chemistry in the containment was started. During 2009, oxidation of iodine, especially organic iodine, was studied within the NROI project. The chemistry of organic iodine in the gas phase is still one of the greatest remaining uncertainties concerning iodine behaviour during a severe accident. During the first year of the NROI project the oxidation of elemental iodine, I2, with ozone and UV-light was investigated. In this study organic iodide, in this case methyl iodide, was investigated in similar conditions as in the NROI-1 project. The experimental facility applied in this study is based on the sampling system built at VTT for the ISTP project CHIP conducted by IRSN. The experimental facility and the measuring technology are sophisticated and unique in the area of nuclear research as well as in the field of aerosol science. Experimental results showed that the methyl iodide concentration in the facility was reduced with increasing temperature and increasing UVC intensity. Similar behaviour occurred when ozone was present in the system. Formed organic gas species during the decomposition of methyl iodide was mainly formaldehyde and methanol. Instant and extensive particle formation occurred when methyl iodide was transported through a UVC radiation field and/or when ozone was present. The size of the formed primary particles was about 10 nm and the size of secondary particles was between 50-150 nm. From the SEM-EDX analyses of the particles, the conclusion was drawn that these were some kind of iodine

  9. Experimental study on iodine chemistry (EXSI) - Containment experiments with methyl iodide

    International Nuclear Information System (INIS)

    Holm, J.; Glaenneskog, H.; Ekberg, C.; Kaerkelae, T.; Auvinen, A.

    2010-05-01

    An experimental study on radiolytic decomposition of methyl iodide was conducted in co-operation between VTT and Chalmers University of Technology as a part of the NKS-R programs. The behaviour of iodine during a severe accident has been studied in several experimental programs, ranging from the large-scale PHEBUS FP tests and intermediate-scale ThAI tests to numerous separate effect studies. In year 2008 the NROI project, a Nordic collaboration studying iodine chemistry in the containment was started. During 2009, oxidation of iodine, especially organic iodine, was studied within the NROI project. The chemistry of organic iodine in the gas phase is still one of the greatest remaining uncertainties concerning iodine behaviour during a severe accident. During the first year of the NROI project the oxidation of elemental iodine, I2, with ozone and UV-light was investigated. In this study organic iodide, in this case methyl iodide, was investigated in similar conditions as in the NROI-1 project. The experimental facility applied in this study is based on the sampling system built at VTT for the ISTP project CHIP conducted by IRSN. The experimental facility and the measuring technology are sophisticated and unique in the area of nuclear research as well as in the field of aerosol science. Experimental results showed that the methyl iodide concentration in the facility was reduced with increasing temperature and increasing UVC intensity. Similar behaviour occurred when ozone was present in the system. Formed organic gas species during the decomposition of methyl iodide was mainly formaldehyde and methanol. Instant and extensive particle formation occurred when methyl iodide was transported through a UVC radiation field and/or when ozone was present. The size of the formed primary particles was about 10 nm and the size of secondary particles was between 50-150 nm. From the SEM-EDX analyses of the particles, the conclusion was drawn that these were some kind of iodine

  10. Study of Coulomb effects using the comparison of positrons and electrons elastic scattering on nuclei

    International Nuclear Information System (INIS)

    Breton, Vincent

    1990-01-01

    We have studied Coulomb effects in the electron-nucleus interaction by measuring electron and positron elastic scattering. The Coulomb field of the nucleus acts differently on theses particles because of their opposite charges. The experiment took place at the Accelerateur Lineaire de Saclay, with 450 MeV electrons and positrons. We measured the emittance of the positron and electron beams. We compared electron and positron beams having the same energy, the same emittance and the same intensity. This way, we measured positron scattering cross sections with 2 % systematic error. By comparing positron and electron elastic scattering cross sections for momentum transfers between 1 and 2 fm -1 , on a Lead 208 target, we showed that the calculations of Coulomb effects in elastic scattering are in perfect agreement with experimental results. The comparison of positron and electron elastic scattering cross sections on Carbon showed that dispersive effects are smaller than 2 % outside the diffraction minima. These two results demonstrate in a definitive way that electron scattering allows to measure charge densities in the center of nuclei with an accuracy of the order of 1 %. (author) [fr

  11. Study of the Polarization Strategy for Electron Cyclotron Heating Systems on HL-2M

    Science.gov (United States)

    Zhang, F.; Huang, M.; Xia, D. H.; Song, S. D.; Wang, J. Q.; Huang, B.; Wang, H.

    2016-06-01

    As important components integrated in transmission lines of electron cyclotron heating systems, polarizers are mainly used to obtain the desired polarization for highly efficient coupling between electron cyclotron waves and plasma. The polarization strategy for 105-GHz electron cyclotron heating systems of HL-2M tokamak is studied in this paper. Considering the polarizers need high efficiency, stability, and low loss to realize any polarization states, two sinusoidal-grooved polarizers, which include a linear polarizer and an elliptical polarizer, are designed with the coordinate transformation method. The parameters, the period p and the depth d, of two sinusoidal-grooved polarizers are optimized by a phase difference analysis method to achieve an almost arbitrary polarization. Finally, the optimized polarizers are manufactured and their polarization characteristics are tested with a low-power test platform. The experimental results agree well with the numerical calculations, indicating that the designed polarizers can meet the polarization requirements of the electron cyclotron heating systems of HL-2M tokamak.

  12. An experimental investigation on reverse-cycle defrosting performance for an air source heat pump using an electronic expansion valve

    International Nuclear Information System (INIS)

    Qu, Minglu; Xia, Liang; Deng, Shiming; Jiang, Yiqiang

    2012-01-01

    Highlights: ► We experimentally studied the defrost performance under two EEV control strategies. ► The two EEV control strategies were fully open and controlled by a DS controller. ► When the EEV was under the DS controller, higher defrosting efficiency was obtained. -- Abstract: When an air source heat pump (ASHP) operates in heating mode, frost can be accumulated on the surface of its finned outdoor coil. Frosting deteriorates the operation and energy efficiency of the ASHP and periodic defrosting becomes necessary. Currently the most widely used standard defrosting method for ASHPs is reverse cycle defrost. On the other hand, electronic expansion valves (EEVs) are commonly used in heat pump/refrigeration systems, including ASHP units, as throttle regulators of refrigerant flow. This paper reports on an experimental investigation of the performance of a reverse cycle defrost operation for a 6.5 kW experimental heating capacity residential ASHP whose outdoor coil had four-parallel refrigerant circuits, and with an EEV as the refrigerant flow throttle regulator. The detailed descriptions of the experimental ASHP unit and the experimental procedures of ASHP are firstly presented. This is followed by reporting the comparative experiments of two control strategies for the EEV to investigate their effects on defrosting performance: the EEV being fully open and the EEV being regulated by a degree of refrigerant superheat (DS) controller. Experimental results revealed that when the EEV was regulated by the DS controller during defrosting, a higher defrosting efficiency and less heat wastage would be resulted in.

  13. Electron scattering and nuclear structure

    International Nuclear Information System (INIS)

    Wolynec, E.

    1985-01-01

    A review of the historical development and the theory necessary to the interpretation of the experimental results is made. Some measurement techniques, experimental results and the technique of analysis of these data are presented. Future perspectives, due to the appearence of continous electron current accelerators, in this field of study are discussed. (L.C.) [pt

  14. Electron diffraction study of {alpha}-AlMnSi crystals including non-crystallographic axes

    Energy Technology Data Exchange (ETDEWEB)

    Song, G.L.; Bursill, L.A.

    1997-06-01

    The structure of crystalline {alpha}-AlMnSi is examined by electron diffraction. Six distinct zone axes are examined, including both normal crystallographic and non-crystallographic zones axes, allowing the space group symmetry to be studied. Electron diffraction patterns characteristic of Pm3-bar were obtained for thicker specimens. However, for very thin specimens, as used for HRTEM imaging, the electron diffraction patterns were characteristic of Im3-bar space group symmetry. The structural basis of the Pm3-bar to Im3-bar transformation may be understood in terms of an analysis of the icosahedral structural elements located at the corners and body-centers of the cubic unit cell. A method for indexing the non-crystallographic zone axis diffraction patterns is described. An electron diffraction pattern of the 5-fold axis of the quasicrystalline phase i-AlMnSi is also included; this is compared with the experimental results and calculations for the [0{tau}1] axis of Pm3-bar and Im3-bar crystalline phases. 26 refs., 4 tabs., 7 figs.

  15. Photoemission study of electronic structure of the half-metallic ferromagnet Co₃Sn₂S₂

    OpenAIRE

    Holder, M.; Dedkov, Y.; Kade, A.; Rosner, H.; Schnelle, W.; Leithe-Jasper, A.; Weihrich, R.; Molodtsov, S.

    2009-01-01

    Surface electronic structure of polycrystalline and single-crystalline samples of the half-metallic ferromagnet Co₃Sn₂S₂ was studied by means of angle-resolved and core-level photoemissions. The experiments were performed in temperature regimes both above and below a Curie temperature of 176.9 K. The spectroscopic results are compared to local-spin density approximation band-structure calculations for the bulk samples. It is found that the surface sensitive experimental data are generally rep...

  16. Experimental Investigation of Electron Cloud Containment in a Nonuniform Magnetic Field

    Science.gov (United States)

    Eninger, J. E.

    1974-01-01

    Dense clouds of electrons were generated and studied in an axisymmetric, nonuniform magnetic field created by a short solenoid. The operation of the experiment was similar to that of a low-pressure (approximately 0.000001 Torr) magnetron discharge. Discharge current characteristics are presented as a function of pressure, magnetic field strength, voltage, and cathode end-plate location. The rotation of the electron cloud is determined from the frequency of diocotron waves. In the space charge saturated regime of operation, the cloud is found to rotate as a solid body with frequency close to V sub a/phi sub a where V sub a is the anode voltage and phi suba is the total magnetic flux. This result indicates that, in regions where electrons are present, the magnetic field lines are electrostatic equipotentials (E bar, B bar = 0). Equilibrium electron density distributions suggested by this conditions are integrated with respect to total ionizing power and are found consistent with measured discharge currents.

  17. Experimental investigation of electron cloud containment in a nonuniform magnetic field

    International Nuclear Information System (INIS)

    Eninger, J.E.

    1974-05-01

    Dense clouds of electrons were generated and studied in an axisymmetric, nonuniform magnetic field created by a short solenoid. The operation of the experiment was similar to that of a low-pressure (approximately 0.000001 torr) magnetron discharge. Discharge current characteristics are presented as a function of pressure, magnetic field strength, voltage, and cathode end-plate location. The rotation of the electron cloud is determined from the frequency of diocotron waves. In the space charge saturated regime of operation, the cloud is found to rotate as a solid body with frequency close to V/sub a/phi/sub a/ where V/sub a/ is the anode voltage and phi/sub a/ is the total magnetic flux. This result indicates that, in regions where electrons are present, the magnetic field lines are electrostatic equipotentials (E bar, B bar = 0). Equilibrium electron density distributions suggested by this condition are integrated with respect to total ionizing power and are found consistent with measured discharge currents. (U.S.)

  18. theoretical and experimental study of plasma acceleration by means of R.F. and static magnetic field gradient

    International Nuclear Information System (INIS)

    Bardet, Rene; Consoli, Terenzio; Geller, Richard

    1964-09-01

    In the first part of the paper, the theory of the physical mechanism of ion dragging by accelerated electrons due to the superimposition of the gradient of a electromagnetic field and the gradient of a static magnetic field, is described. The resulting trajectory of the electrons is a helicoid and one shows the variations of the diameter and the path of the spirals along the axis as a function of the difference between the gyrofrequency and the applied R.F. frequency. The ion acceleration is due to an electron space charge effect. The grouping of the equations of the electronic and ionic fluid motions leads to the introduction of a tensor mass: along the x and y direction the transverse motion of the fluid is controlled by the relativistic mass of electrons whereas along the z direction the axial motion is determined by the ionic mass. Then we deduce physical consequences of the theoretical study and give three experimental evidences. The second part of the paper is devoted to the experimental device called Pleiade which allowed us to verify some of the theoretical predictions. Pleiade produces a D.C. operating plasma beam in which the electrons exhibit radially oriented energies whereas the ionic energy is mainly axial. The experimental results indicate that the energy of the particles is in the keV range. In the third part we deal with the reflecting properties of the device. We show that the R.F. static magnetic field gradients are not only capable of accelerating a Plasma beam along the axially decreasing magnetic field, but are also capable of stopping and reflecting such a beam when the latter is moving along an axially increasing magnetic field. We describe finally a plasma accumulation experiment in which two symmetric structures form simultaneously an accelerator and a 'dynamic mirror' for the particles. Evidence of accumulation is given. (authors) [fr

  19. Hearing shapes of few electrons quantum drums: A configuration–interaction study

    International Nuclear Information System (INIS)

    Ţolea, F.; Ţolea, M.

    2015-01-01

    The – highly remarkable – existence of non-congruent yet vibrationally isospectral shapes has been first proved theoretically and then also tested experimentally – by using electromagnetic waves in cavities, vibrating smectic films or electrons in nanostructures. In this context, we address the question whether isospectrality holds if two or more electrons interact electrostatically, using the accurate configuration–interaction method, in a discrete representation of the Bilby and Hawk shapes. Isospectral pairs offer an unique possibility to test how identical sets of single-particle energies may combine differently in the few-electrons eigenmodes, due to different wave functions spatial distributions. Our results point towards the break down of isospectrality in the presence of interactions. Thus one should be able to ”hear” the shapes of few electrons quantum drums. Interestingly however, for the analyzed two and three electrons cases, there exists an interaction strength (which can be tuned by changing the size of the shapes), for which the ground states energies of Bilby and Hawk coincide, but not the excited states as well. Wigner localization is studied and shown to occur at about the same size for both Bilby and Hawk shapes. Next, an exercise is proposed to use the two-electrons charge density of the Bilby and Hawk ground states in the phase extraction scheme as proposed by Moon et al. (2008). Results show that out-of-phase regions appear if the linear size of the shapes exceeds the Bohr radius as occupation of higher Slater determinants becomes significant

  20. Hearing shapes of few electrons quantum drums: A configuration–interaction study

    Energy Technology Data Exchange (ETDEWEB)

    Ţolea, F.; Ţolea, M., E-mail: tzolea@infim.ro

    2015-02-01

    The – highly remarkable – existence of non-congruent yet vibrationally isospectral shapes has been first proved theoretically and then also tested experimentally – by using electromagnetic waves in cavities, vibrating smectic films or electrons in nanostructures. In this context, we address the question whether isospectrality holds if two or more electrons interact electrostatically, using the accurate configuration–interaction method, in a discrete representation of the Bilby and Hawk shapes. Isospectral pairs offer an unique possibility to test how identical sets of single-particle energies may combine differently in the few-electrons eigenmodes, due to different wave functions spatial distributions. Our results point towards the break down of isospectrality in the presence of interactions. Thus one should be able to ”hear” the shapes of few electrons quantum drums. Interestingly however, for the analyzed two and three electrons cases, there exists an interaction strength (which can be tuned by changing the size of the shapes), for which the ground states energies of Bilby and Hawk coincide, but not the excited states as well. Wigner localization is studied and shown to occur at about the same size for both Bilby and Hawk shapes. Next, an exercise is proposed to use the two-electrons charge density of the Bilby and Hawk ground states in the phase extraction scheme as proposed by Moon et al. (2008). Results show that out-of-phase regions appear if the linear size of the shapes exceeds the Bohr radius as occupation of higher Slater determinants becomes significant.

  1. Experimental evidence for interactions between anions and electron-deficient aromatic rings.

    Science.gov (United States)

    Berryman, Orion B; Johnson, Darren W

    2009-06-14

    This feature article summarizes our research aimed at using electron-deficient aromatic rings to bind anions in the context of complementary research in this active field. Particular attention is paid to the different types of interactions exhibited between anions and electron-deficient arenes in solution. The 120+ references cited in this article underscore the flurry of recent activity by numerous researchers in this field, which was relatively nascent when our efforts began in 2005. While the interaction of anions with electron-deficient aromatic rings has recently garnered much attention by supramolecular chemists, the observation of these interactions is not a recent discovery. Therefore, we begin with a historical perspective on early examples of anions interacting with electron-deficient arenes. An introduction to recent (and not so recent) computational investigations concerning anions and electron-deficient aromatic rings as well as a brief structural survey of crystalline examples of this interaction are provided. Finally, the limited solution-based observations of anions interacting with electron-deficient aromatic rings are summarized to introduce our current investigations in this area. We highlight three different systems from our lab where anion-arene interactions have been investigated. First, we show that tandem hydrogen bonds and anion-arene interactions augment halide binding in solution. Second, a crystallographic and computational study highlights the multiple types of interactions possible between anions and electron-deficient arenes. Third, we summarize the first example of a class of designed receptors that emphasize the different types of anion-arene interactions possible in solution.

  2. Study of electron and neutrino interactions

    International Nuclear Information System (INIS)

    Abashian, A.

    1997-01-01

    This is the final report for the DOE-sponsored experimental particle physics program at Virginia Tech to study the properties of the Standard Model of strong and electroweak interactions. This contract (DE-AS05-80ER10713) covers the period from August 1, 1980 to January 31, 1993. Task B of this contract, headed by Professor Alexander Abashian, is described in this final report. This program has been pursued on many fronts by the researchers-in a search for axions at SLAC, in electron-positron collisions in the AMY experiment at the TRISTAN collider in Japan, in measurements of muon decay properties in the MEGA and RHO experiments at the LAMPF accelerator, in a detailed analysis of scattering effects in the purported observation of a 17 keV neutrino at Oxford, in a search for a disoriented chiral condensate with the MiniMax experiment at Fermilab, and in an R ampersand D program on resistive plate counters that could find use in low-cost high-quality charged particle detection at low rates

  3. Study of the electron heat transport in Tore-Supra tokamak; Etude du transport de la chaleur electronique dans le Tokamak Tore Supra

    Energy Technology Data Exchange (ETDEWEB)

    Harauchamps, E

    2004-07-01

    This work presents analytical solutions to the electron heat transport equation involving a damping term and a convection term in a cylindrical geometry. These solutions, processed by Matlab, allow the determination of the evolution of the radial profile of electron temperature in tokamaks during heating. The modulated injection of waves around the electron cyclotron frequency is an efficient tool to study heat transport experimentally in tokamaks. The comparison of these analytical solutions with experimental results from Tore-Supra during 2 discharges (30550 and 31165) shows the presence of a sudden change for the diffusion and damping coefficients. The hypothesis of the presence of a pinch spread all along the plasma might explain the shape of the experimental temperature profiles. These analytical solutions could be used to determine the time evolution of plasma density as well or of any parameter whose evolution is governed by a diffusion-convection equation. (A.C.)

  4. Single-electron tunneling in double-barrier nanostructures

    International Nuclear Information System (INIS)

    Goldman, V.J.; Su, B.; Cunningham, J.E.

    1992-01-01

    In this paper, the authors review experimental study of charge transport in nanometer double-barrier resonant tunneling devices. Heterostructure material is asymmetric: one barrier is substantially less transparent than the other. Resonant tunneling through size-quantized well states and single-electron charging of the well are thus largely separated in the two bias polarities. When the emitter barrier is more transparent than the collector barrier, electrons accumulate in the well; incremental electron occupation of the well is accompanied by Coulomb blockade leading to sharp steps of the tunneling current. When the emitter barrier is less transparent, the current reflects resonant tunneling of just one electron at a time through size-quantized well states; the current peaks and/or steps (depending on experimental parameters) appear in current-voltage characteristics. Magnetic field and temperature effects are also reviewed. Good agreement is achieved in comparison of many features of experimental data with simple theoretical models

  5. Experimental study of heat transfer in a heat exchanger with rectangular channels

    International Nuclear Information System (INIS)

    Hammami, Mahmoud; Ben Said, Akrem; Ben Maad, Rejeb; Rebay, Mourad

    2009-01-01

    This paper presents the results of an experimental study related to characterisation of a mini channel heat exchanger. Such heat exchanger may be used in water cooling of electronic components. The results obtained show the efficiency of this exchanger even with very low water flow rates. Indeed, in spite of the importance of the extracted heat fluxes which can reach about 50Kw/m 2 , the temperature of the cooled Aluminium bloc remained always lower than the tolerated threshold of 80 degree in electronic cooling. Moreover, several thermal characteristics such as equivalent thermal resistance of the exchanger, the average internal convective heat transfer coefficient and the increase in the temperature of the cooling water have been measured. The results presented have been obtained with in q uinconce r ectangular mini-channel heat exchanger, with a hydraulic diameter D h = 2mm. NOMENCLATURE h D Hydraulic diameter (mm). int

  6. Study of the electron energy distribution function in plasma produced by a rf discharge in a mixture of inert gases

    International Nuclear Information System (INIS)

    Vagner, S.D.; Ignat'ev, B.K.

    1983-01-01

    Electron energy distribution functions (EEDF) are recorded in an rf discharge in a mixture of neon and argon. The rates of different ionization processes and the energy losses of the electrons in the bulk of the discharge are calculated. The experimentally recorded electron energy distribution functions are compared with distributions calculated using a nonlocal theory. The effect of an rf voltage in the probe circuit on the recorded electron energy distribution functions is investigated experimentally

  7. Study of photo-activated electron transfer reactions in the first excited singlet state by picosecond and nanosecond laser spectroscopy

    International Nuclear Information System (INIS)

    Doizi, Denis

    1983-01-01

    Picosecond laser spectroscopy has been used to study two photo-activated electron transfer reactions: - a bimolecular electron transfer reaction between a sensitizer, DODCI, and an electron acceptor, methylviologen. The two radical ions created with an electron transfer efficiency γ ≅ 0.07 have been identified in picosecond and nanosecond laser absorption spectroscopy by adding selective solutes such as para-benzoquinone (an electron acceptor) or L(+) ascorbic acid (an electron donor). - an intramolecular electron transfer reaction in a triad molecule consisting of a tetra-aryl-porphyrin covalently linked to both a carotenoid and a quinone. The photoinduced charge separation occurs within 30 ps and leads, with a yield of 25 pc, to the formation of a zwitterion whose half-life is 2.5 μs. The experimental results obtained in these two studies show an effective decrease in the recombination rate of the two radical ions created in the encounter pair. (author) [fr

  8. Beam dynamics studies at DAΦNE: from ideas to experimental results

    Science.gov (United States)

    Zobov, M.; DAΦNE Team

    2017-12-01

    DAΦNE is the electron-positron collider operating at the energy of Φ-resonance, 1 GeV in the center of mass. The presently achieved luminosity is by about two orders of magnitude higher than that obtained at other colliders ever operated at this energy. Careful beam dynamic studies such as the vacuum chamber design with low beam coupling impedance, suppression of different kinds of beam instabilities, investigation of beam-beam interaction, optimization of the beam nonlinear motion have been the key ingredients that have helped to reach this impressive result. Many novel ideas in accelerator physics have been proposed and/or tested experimentally at DAΦNE for the first time. In this paper we discuss the advanced accelerator physics studies performed at DAΦNE.

  9. Experimental study of pulmonary thromboembolism ischemia-reperfusion injury in canine model

    International Nuclear Information System (INIS)

    Li Jianjun; Zhai Renyou; Zhang Dongpo; Huang Qiang; Yu Ping; Dai Dingke; Bao Na

    2009-01-01

    Objective: To establish a canine model of pulmonary thromboembolism ischemia- reperfusion injury (PTE IRI) that may be used for imaging study. Methods: Ten male and 10 female healthy mongrel canines with (18.6±0.8) kg/body weight, were used. A Swan-Ganz catheter was introduced into the right internal jugular vein via a preset percutaneous sheath using the Seldinger technique, and then was with further insertion the pulmonary artery. Balloon occlusion of the right inferior lobe pulmonary artery for 4 hours was followed by removing the catheter and ending with 4 hours of reperfusion. CT was performed before ischemia, 4 h after ischemia and 4 h after reperfusion. At last, dogs were killed and the bilateral inferior lung tissues were prepared for the examination by light and electronic microscopy. Results: All canine models were successfully developed pulmonary thromboembolism ischemia-reperfusion injury. The examination of CT, light and electron microscopy consistently indicated the presence of permeability pulmonary edema after reperfusion. Conclusions: A closed-chest canine model in vivo of pulmonary thromboembolism ischemia-reperfusion injury can be established with virtual pathophysiological process in human and be as well as for imaging experimental study. (authors)

  10. Experimental study of the electric resistivity in Heusler alloys

    International Nuclear Information System (INIS)

    Kunzler, J.V.

    1980-01-01

    Electrical resistivity measurements have been performed in the Cu 2 Mn (A1sub(1-x) Snsub(x)) Heusler alloys, where x = 0, 0.05, 0.10 and 0.15, in the temperature range from 4.2 to 800 0 K. Measurements have also been made on the Ni 2 MnX Heusler asloys, with X = In, Sn or Sb, in the range from 4.2 to 300 0 K. The experimental curves clearly show the importance of the ferromagnetic character for the alloys resistivity. The results obtained for the copper alloys, as well as for the Ni 2 MnSn alloy, are in agreement with an interpretation in terms of Bloch-Gruneisen and spin-disorder models, and fail to provide evidences of s-d scattering for the conduction electrons. This is not the case for the Ni 2 MnIn and Ni 2 MnSb alloys, in which the presence of (s-d) interband electronic scattering process, via phonon, was detected. Specially for the two last alloys specific heat and electronic photo-emissivity experiments are suggested. (Author) [pt

  11. Design studies for the electron storage ring EUTERPE

    Energy Technology Data Exchange (ETDEWEB)

    Boling, Xi

    1995-05-18

    The 400 MeV electron storage ring EUTERPE is under construction at Eindhoven University of Technology. The ring is to be used as an experimental tool for accelerator physics studies and synchroton radiation applications. The main task of the current research work is the electron optical design of the ring. Lattice design is a basis for machine design as a whole. Design aspects regarding the basic lattice, based on single particle dynamics, include determination of the equilibrium beam size and bunch length, design of achromatic bending sections, selection of tune values, correction of chromaticity, and minimization of the natural emittance in the ring. The basic lattice designed for the EUTERPE ring has a high flexibility so that different electron optical modes can be realized easily. In low energy storage rings with a high beam current, collective effects can cause a significant change in the bunch length, the transverse emittance and the beam lifetime. In order to ensure a good optical performance for the ring, the choice of suitable parameters concerning the vacuum and RF system are essential as far as collective effects are concerned. An estimation of the collective effects in the ring is given. The injector for EUTERPE is a 75 MeV racetrack microtron which is injected from a 10 MeV linac. In order to get sufficient beam current in the ring, a special procedure of continuous injection with an adjustable locally shifted closed orbit has been presented. Details of the injection procedure and numerical simulations are given. (orig./HSI).

  12. Design studies for the electron storage ring EUTERPE

    International Nuclear Information System (INIS)

    Xi Boling.

    1995-01-01

    The 400 MeV electron storage ring EUTERPE is under construction at Eindhoven University of Technology. The ring is to be used as an experimental tool for accelerator physics studies and synchroton radiation applications. The main task of the current research work is the electron optical design of the ring. Lattice design is a basis for machine design as a whole. Design aspects regarding the basic lattice, based on single particle dynamics, include determination of the equilibrium beam size and bunch length, design of achromatic bending sections, selection of tune values, correction of chromaticity, and minimization of the natural emittance in the ring. The basic lattice designed for the EUTERPE ring has a high flexibility so that different electron optical modes can be realized easily. In low energy storage rings with a high beam current, collective effects can cause a significant change in the bunch length, the transverse emittance and the beam lifetime. In order to ensure a good optical performance for the ring, the choice of suitable parameters concerning the vacuum and RF system are essential as far as collective effects are concerned. An estimation of the collective effects in the ring is given. The injector for EUTERPE is a 75 MeV racetrack microtron which is injected from a 10 MeV linac. In order to get sufficient beam current in the ring, a special procedure of continuous injection with an adjustable locally shifted closed orbit has been presented. Details of the injection procedure and numerical simulations are given. (orig./HSI)

  13. Experimental electron density studies as key for understanding the chemical and physical properties in selected model systems; Experimentelle Elektronendichtestudien als Schluessel zum Verstaendnis chemischer und physikalischer Eigenschaften in ausgewaehlten Modellsystemen

    Energy Technology Data Exchange (ETDEWEB)

    Hauf, Christoph

    2014-12-17

    The topological analysis of experimentally determined electron density distributions, employing the quantum theory of atoms in molecules developed by Richard FW Bader, was used in this thesis to study chemically or physically motivated questions in appropriate model systems. First, transition metal complexes with activated C-H bonds or Si-H bonds were examined which led to a better understanding of agostic interactions. An important tool during these investigations is the so called atomic graph, which describes the characteristic spatial arrangement of the critical points of the Laplacefield of the electron density distribution in the valence shell of the relevant atoms. It reveals zones with a locally concentrated or depleted electron density distribution. This leads to the empirical rule, that a strong activation of C-H bonds or Si-H bonds is only observed when the hydrogen atom faces a pronounced charge depletion zone at the transition metal atom. In addition, the quasi one-dimensional rare-earth transition metal carbides Sc{sub 3}FeC{sub 4}, Sc{sub 3}CoC{sub 4} and Sc{sub 3}NiC{sub 4} were examined. Although all three compounds are isotypic at room temperature, it was revealed during this thesis, that only Sc{sub 3}CoC{sub 4} undergoes a structural phase transition at a temperature of ∝ 70 K and becomes superconducting below a critical temperature of 4.5 K. The main reason for this behaviour is the variation of the valence electrons through the exchange of Fe by Co or Ni. This results in the occupation of progressively higher energy electronic states and a raising of the Fermi level. The change in the nature of the electronic states at the Fermi level is in turn reflected by the different atomic graphs of the transition metal atoms and the distinct physical properties of these three compounds.

  14. Attempt to assess the infiltration of enamel made with experimental preparation using a scanning electron microscope.

    Science.gov (United States)

    Skucha-Nowak, Małgorzata

    2015-01-01

    The resin infiltration technique, a minimally invasive method, involves the saturation, strengthening, and stabilization of demineralized enamel by a mixture of polymer resins without the need to use rotary tools or the risk of losing healthy tooth structures. To design and synthesize an experimental infiltrant with potential bacteriostatic properties.To compare the depth of infiltration of the designed experimental preparation with the infiltrant available in the market using a scanning electron microscope. Composition of the experimental infiltrant was established after analysis of 1H NMR spectra of the commercially available compounds that can penetrate pores of demineralized enamel. As the infiltrant should have bacteriostatic features by definition, an addition of 1% of monomer containing metronidazole was made. Thirty extracted human teeth were soaked in an acidic solution, which was to provide appropriate conditions for demineralization of enamel. Afterward, each tooth was divided along the coronal-root axis into two zones. One zone had experimental preparation applied to it (the test group), while the other had commercially available Icon (the control group). The teeth were dissected along the long axis and described above underwent initial observation with use of a Hitachi S-4200 scanning electron microscope. It was found that all samples contained only oxygen and carbon, regardless of the concentration of additions introduced into them. The occurrence of carbon is partially because it is a component of the preparation in question and partially because of sputtering of the sample with it. Hydrogen is also a component of the preparation, as a result of its phase composition; however, it cannot be detected by the EDS method. SEM, in combination with X-ray microanalysis, does not allow one to explicitly assess the depth of penetration of infiltration preparations into enamel.In order to assess the depth of penetration of infiltration preparations with use of

  15. Electron transfer driven decomposition of adenine and selected analogs as probed by experimental and theoretical methods

    Science.gov (United States)

    Cunha, T.; Mendes, M.; Ferreira da Silva, F.; Eden, S.; García, G.; Bacchus-Montabonel, M.-C.; Limão-Vieira, P.

    2018-04-01

    We report on a combined experimental and theoretical study of electron-transfer-induced decomposition of adenine (Ad) and a selection of analog molecules in collisions with potassium (K) atoms. Time-of-flight negative ion mass spectra have been obtained in a wide collision energy range (6-68 eV in the centre-of-mass frame), providing a comprehensive investigation of the fragmentation patterns of purine (Pu), adenine (Ad), 9-methyl adenine (9-mAd), 6-dimethyl adenine (6-dimAd), and 2-D adenine (2-DAd). Following our recent communication about selective hydrogen loss from the transient negative ions (TNIs) produced in these collisions [T. Cunha et al., J. Chem. Phys. 148, 021101 (2018)], this work focuses on the production of smaller fragment anions. In the low-energy part of the present range, several dissociation channels that are accessible in free electron attachment experiments are absent from the present mass spectra, notably NH2 loss from adenine and 9-methyl adenine. This can be understood in terms of a relatively long transit time of the K+ cation in the vicinity of the TNI tending to enhance the likelihood of intramolecular electron transfer. In this case, the excess energy can be redistributed through the available degrees of freedom inhibiting fragmentation pathways. Ab initio theoretical calculations were performed for 9-methyl adenine (9-mAd) and adenine (Ad) in the presence of a potassium atom and provided a strong basis for the assignment of the lowest unoccupied molecular orbitals accessed in the collision process.

  16. Study of nuclei by electron scattering

    International Nuclear Information System (INIS)

    Torizuka, Yoshiharu; Saito, Teijiro; Ito, Kohei; Terasawa, Tatsuo; Hosoyama, Kenji.

    1974-01-01

    It is urgently required to clarify the physical meaning of the quasi-elastic scattering associated with the background, in order to develop rapidly the study of giant resonance. The experimental works performed in the present term aimed at the synthetic understanding of both giant resonance and quasi-elastic scattering, and presented the possibility of the separability of giant resonance from quasi-elastic scattering. The object of this experiment was to measure higher order multi-pole moment of 51 V by using relatively high energy electron beam. Targets of chemically pure 51 V had thickness of 68.2 or 100.5 mg/cm 2 . The measurement was made at the position where scattering angle was 155 0 . The state of M7 can be well explained by the model with (fsub(7/2)) 3 coordination. This may be because the nuclei with stretched configuration such as 51 V do not have any contribution of orbital motion, but have the contribution of eigen magnetic moment to the highest multiplicity. States of M3 and M5 are a little complicated. Since in the experimental equipment used, the contribution of charge distribution was so large, that it was difficult to make the precision measurement of M3 and M5. In 51 V, however, it can be considered that M3 and M5 decreased by the contribution of 2Psub(3/2) and 1fsub(5/2). On the other hand, there is no contribution from these energy states to M7. (Tai, I.)

  17. Experimental demonstration of synergy between electron cyclotron and lower hybrid current drive on Tore Supra

    International Nuclear Information System (INIS)

    Artaud, J.F.; Giruzzi, G.; Dumont, R.J.; Imbeaux, F.; Bibet, P.; Bouquey, F.; Clary, J.; Ekedahl, A.; Hoang, G.T.; Lennholm, M.; Magne, R.; Segui, J.L.

    2004-01-01

    Non-inductive current drive (CD) has two main applications in tokamaks: sustainment of a substantial fraction of the toroidal plasma current necessary for the plasma confinement and control of the plasma stability and transport properties by appropriate shaping of the current density profile. For the first kind of applications, lower hybrid (LH) waves are known to provide the highest efficiency (defined as the ratio of the driven current to the injected wave power), although with limited control capability. Conversely, electron cyclotron (EC) waves drive highly localized currents, and are therefore particularly suited for control purposes, but their CD efficiency is much lower than that of LH waves (typically, an order of magnitude in present day experiments). Various calculations have demonstrated an interesting property: the current driven by the simultaneous use of the two waves, I(LH+EC), can be significantly larger than the sum I(LH)+I(EC) of the currents separately driven by the two waves in the same plasma conditions. This property, called synergy effect. The peculiar experimental conditions attainable on the Tore Supra tokamak have allowed the first experimental demonstration of the synergy between EC and LH current drive. The significant improvement of the electron cyclotron current drive (ECCD) efficiency in the presence of low hybrid current drive (LHCD), predicted by kinetic theory and confirmed by stationary experiments on Tore Supra, opens up the possibility of using ECCD as an efficient current profile control tool in LHCD plasmas

  18. Study on the intense relativistic electron beam propagation in a collisionless plasma of small density

    International Nuclear Information System (INIS)

    Korenev, S.A.; Rubin, N.B.; Khodataev, K.V.

    1982-01-01

    The results of the experimental studies of the intense relativistic electron beam (IREB) propagation with ν/γ approximately 0.1, and γ approximately 1.6 (γ is an electron beam relativistic factor) in a collisionless plasma of small density over the 180 cm length are presented. Plasma is generated with the incomplete discharge over dielectric surface at the residual gas pressure of P approximately 10 -5 Torr. It is shown that the transportation efficiency may be essentially high, if the electron concentration in plasma satisfies the equilibrium conditions and if it is less or equal to the electron concentration in a beam. At concentration less than optimum one, the transportation efficiency decreases due to violations of equilibrium conditions. At high concentration the transportation efficiency also decreased due to the scattering and breaking on excited small-scale and plasma oscillations. The IREB propagation occurs without essential time delay under optimum conditions

  19. Experimental studies on the production and suppression mechanism of the hot electrons produced by short wavelength laser

    International Nuclear Information System (INIS)

    Qi Lanying; Jiang Xiaohua; Zhao Xuewei; Li Sanwei; Zhang Wenhai; Li Chaoguang; Zheng Zhijian; Ding Yongkun

    1999-12-01

    The experiments on gold-disk and hohlraum and plastic hydrocarbon (CH) film targets irradiated by laser beams with wavelength 0.35 μm (Xingguang-II) and 0.53 μm (Shenguang-I) are performed. The characteristics of hot electrons are commonly deduced from spectrum of hard X-ray. Associated with the measurement of backward SRS and 3/2ω 0 , the production mechanism of hot electrons for different target type is analyzed in laser plasma with shorter wavelength. A effective way to suppress hot electrons has been found

  20. In situ transmission electron microscopy and scanning transmission electron microscopy studies of sintering of Ag and Pt nanoparticles

    International Nuclear Information System (INIS)

    Asoro, M.A.; Ferreira, P.J.; Kovar, D.

    2014-01-01

    Transmission electron microscopy and scanning transmission electron microscopy studies were conducted in situ on 2–5 nm Pt and 10–40 nm Ag nanoparticles to study mechanisms for sintering and to measure relevant sintering kinetics in nanoscale particles. Sintering between two separated particles was observed to initiate by either (1) diffusion of the particles on the sample support or (2) diffusion of atoms or small clusters of atoms to the neck region between the two particles. After particle contact, the rate of sintering was controlled by atomic surface diffusivity. The surface diffusivity was determined as a function of particle size and temperature from experimental measurements of the rate of neck growth of the particles. The surface diffusivities did not show a strong size effect for the range of particle sizes that were studied. The surface diffusivity for Pt nanoparticles exhibited the expected Arrhenius temperature dependence and did not appear to be sensitive to the presence of surface contaminants. In contrast, the surface diffusivity for Ag nanoparticles was affected by the presence of impurities such as carbon. The diffusivities for Ag nanoparticles were consistent with previous measurements of bulk surface diffusivities for Ag in the presence of C, but were significantly slower than those obtained from pristine Ag

  1. A method for the direct measurement of electronic site populations in a molecular aggregate using two-dimensional electronic-vibrational spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, Nicholas H. C.; Dong, Hui; Oliver, Thomas A. A.; Fleming, Graham R., E-mail: grfleming@lbl.gov [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Kavli Energy Nanosciences Institute at Berkeley, Berkeley, California 94720 (United States)

    2015-09-28

    Two dimensional electronic spectroscopy has proved to be a valuable experimental technique to reveal electronic excitation dynamics in photosynthetic pigment-protein complexes, nanoscale semiconductors, organic photovoltaic materials, and many other types of systems. It does not, however, provide direct information concerning the spatial structure and dynamics of excitons. 2D infrared spectroscopy has become a widely used tool for studying structural dynamics but is incapable of directly providing information concerning electronic excited states. 2D electronic-vibrational (2DEV) spectroscopy provides a link between these domains, directly connecting the electronic excitation with the vibrational structure of the system under study. In this work, we derive response functions for the 2DEV spectrum of a molecular dimer and propose a method by which 2DEV spectra could be used to directly measure the electronic site populations as a function of time following the initial electronic excitation. We present results from the response function simulations which show that our proposed approach is substantially valid. This method provides, to our knowledge, the first direct experimental method for measuring the electronic excited state dynamics in the spatial domain, on the molecular scale.

  2. Low energy electron scattering from fuels

    International Nuclear Information System (INIS)

    Lopes, M. Cristina A.; Silva, Daniel G.M.; Coelho, Rafael F.; Duque, Humberto V.; Santos, Rodrigo R. dos; Ribeiro, Thiago M.

    2011-01-01

    Full text. Accurate and precise values of absolute total cross section (TCS) represent important information in many scientific and technological applications. In our case, for example, we are motivated to provide such information for electron-fuel collision processes which are specifically relevant to modeling spark ignition in alcohol-fuelled internal combustion engines. Many electron scattering TCS measurements are presently available for a diverse range of atomic and molecular targets. However, lack of data for important bio-molecular targets still remains. Disagreements between the available TCS data for the alcohols have prompted several studies of electron scattering collision of slow electrons with these molecules which are currently important in applications as bio- fuels. This relevance, which has attracted much attention, has been one of the subjects of a recent collaboration between experimental and theoretical groups in the USA and Brazil. Recently this collaboration reported first measurements and calculations of differential cross sections for elastic low-energy (rotationally unresolved) electron scattering by several primary alcohols. In this work we address methanol and ethanol TCSs at low energy range and report additional studies of resonant structure in ethanol using the detection of metastable states produced by electron impact excitation with high energy resolution. We have recently constructed a TCS apparatus in our laboratory at Universidade Federal de Juiz de Fora, Brazil, based on the well-known linear transmission technique. The experimental setup is based on the measurement of the attenuation of a collimated electron beam through a gas cell containing the atoms or molecules to be studied at a given pressure. It consists essentially of an electron gun, a gas cell and an electron energy analyzer composed of an array of decelerating electrostatic lenses, a cylindrical dispersive 127o analyzer and a Faraday cup. To our knowledge, there exist

  3. Low energy electron scattering from fuels

    Energy Technology Data Exchange (ETDEWEB)

    Lopes, M. Cristina A.; Silva, Daniel G.M.; Coelho, Rafael F.; Duque, Humberto V.; Santos, Rodrigo R. dos; Ribeiro, Thiago M. [Universidade Federal de Juiz de Fora (UFJF), MG (Brazil). Dept. de Fisica; Yates, Brent; Hong, Ling; Khakoo, Murtadha A. [California State University at Fullerton, CA (US). Physics Department; Bettega, Marcio H.F. [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil). Dept. de Fisica; Costa, Romarly F. da [Universidade Federal do ABC (UFABC), Santo Andre, SP (Brazil). Centro de Ciencias Naturais e Humanas; Lima, Marco A.P. [Laboratorio Nacional de Ciencia e Tecnologia do Bioetanol (CTBE/CNPEM), Campinas, SP (Brazil)

    2011-07-01

    Full text. Accurate and precise values of absolute total cross section (TCS) represent important information in many scientific and technological applications. In our case, for example, we are motivated to provide such information for electron-fuel collision processes which are specifically relevant to modeling spark ignition in alcohol-fuelled internal combustion engines. Many electron scattering TCS measurements are presently available for a diverse range of atomic and molecular targets. However, lack of data for important bio-molecular targets still remains. Disagreements between the available TCS data for the alcohols have prompted several studies of electron scattering collision of slow electrons with these molecules which are currently important in applications as bio- fuels. This relevance, which has attracted much attention, has been one of the subjects of a recent collaboration between experimental and theoretical groups in the USA and Brazil. Recently this collaboration reported first measurements and calculations of differential cross sections for elastic low-energy (rotationally unresolved) electron scattering by several primary alcohols. In this work we address methanol and ethanol TCSs at low energy range and report additional studies of resonant structure in ethanol using the detection of metastable states produced by electron impact excitation with high energy resolution. We have recently constructed a TCS apparatus in our laboratory at Universidade Federal de Juiz de Fora, Brazil, based on the well-known linear transmission technique. The experimental setup is based on the measurement of the attenuation of a collimated electron beam through a gas cell containing the atoms or molecules to be studied at a given pressure. It consists essentially of an electron gun, a gas cell and an electron energy analyzer composed of an array of decelerating electrostatic lenses, a cylindrical dispersive 127o analyzer and a Faraday cup. To our knowledge, there exist

  4. Study of electron current extraction from a radio frequency plasma cathode designed as a neutralizer for ion source applications

    Energy Technology Data Exchange (ETDEWEB)

    Jahanbakhsh, Sina, E-mail: sinajahanbakhsh@gmail.com; Satir, Mert; Celik, Murat [Department of Mechanical Engineering, Bogazici University, Istanbul 34342 (Turkey)

    2016-02-15

    Plasma cathodes are insert free devices that are developed to be employed as electron sources in electric propulsion and ion source applications as practical alternatives to more commonly used hollow cathodes. Inductively coupled plasma cathodes, or Radio Frequency (RF) plasma cathodes, are introduced in recent years. Because of its compact geometry, and simple and efficient plasma generation, RF plasma source is considered to be suitable for plasma cathode applications. In this study, numerous RF plasma cathodes have been designed and manufactured. Experimental measurements have been conducted to study the effects of geometric and operational parameters. Experimental results of this study show that the plasma generation and electron extraction characteristics of the RF plasma cathode device strongly depend on the geometric parameters such as chamber diameter, chamber length, orifice diameter, orifice length, as well as the operational parameters such as RF power and gas mass flow rate.

  5. Monte Carlo study of the effective Sherman function for electron polarimetry

    International Nuclear Information System (INIS)

    Drągowski, M.; Włodarczyk, M.; Weber, G.; Ciborowski, J.; Enders, J.; Fritzsche, Y.; Poliszczuk, A.

    2016-01-01

    The PEBSI Monte Carlo simulation was upgraded towards usefulness for electron Mott polarimetry. The description of Mott scattering was improved and polarisation transfer in Møller scattering was included in the code. An improved agreement was achieved between the simulation and available experimental data for a 100 keV polarised electron beam scattering off gold foils of various thicknesses. The dependence of the effective Sherman function on scattering angle and target thickness, as well as the method of finding optimal conditions for Mott polarimetry measurements were analysed.

  6. Experimental study on lyophilized irradiation sterilized nerve allografts in rabbits

    International Nuclear Information System (INIS)

    Yang Zhiyuan; Sun Shiquan; Liu Hechen

    1991-01-01

    Lyophilized irradiation sterilized nerve grafts in rabbits were used in allogeneic nerve transplantation. The result show that about 76% of experimental rabbits had fairly well morphologic (microscopic and electron microscopic) and electrophysiological recovery 3 month after operation. Preservation of neurilemmal tubes in nerve grafts, repopulation of Schwann cells in this tube and suppression of immune rejection are the key points in allogeneic nerve transplantation

  7. Experimental and theoretical study of breakdown mechanisms in a gas in an uniform electric field

    Energy Technology Data Exchange (ETDEWEB)

    Bayle, P

    1975-01-01

    The theoretical study of breakdown mechanisms in a gas with an applied electric field has been made on the basis of a deterministic model built on continuity equations governing the evolution of electronic and ionic densities. With this purpose, the breakdown formation has been simulated in electronegative gases (air, oxygen) taking into account the space charge effects on initial applied electric field, the electronic emission on the cathode by photonic or ionic impact, the delayed electrons processes (attachment, detachment) and charge exchange processes. Without space charge, the influence of photoionization in the gas on the electronic and ionic population has been pointed out in a discharge in nitrogen. Then the problem of external electrode discharges has been approached for the study of plasma visualization pannel cells, and the fundamental role of the charges deposed on dielectrics has been manifested. In the experimental study, the discharge formation has been analysed in rare gases and nitrogen for high over voltages (more than 100%) and for pressures of about hundred torrs. Using high-speed cinematographic techniques, the discharge propagation has been studied with a one nanosecond time resolution. The ultra-fast propagation zone of anode-directed streamer has been linked with the intervention of distance ionization process. The arrival of the streamers on the anode induces the beginning of an ionization front propagating towards the cathode.

  8. Experimental and theoretical study of breakdown mechanisms in a gas in an uniform electric field

    International Nuclear Information System (INIS)

    Bayle, Pierre.

    1975-01-01

    The theoretical study of breakdown mechanisms in a gas with an applied electric field has been made on the basis of a deterministic model built on continuity equations governing the evolution of electronic and ionic densities. With this purpose, the breakdown formation has been simulated in electronegative gases (air, oxygen) taking into account the space charge effects on initial applied electric field, the electronic emission on the cathode by photonic or ionic impact, the delayed electrons processes (attachment, detachment) and charge exchange processes. Without space charge, the influence of photoionization in the gas on the electronic and ionic population has been pointed out in a discharge in nitrogen. Then the problem of external electrode discharges has been approached for the study of plasma visualization pannel cells, and the fundamental role of the charges deposed on dielectrics has been manifested. In the experimental study, the discharge formation has been analysed in rare gases and nitrogen for high over voltages (more than 100%) and for pressures of about hundred torrs. Using high-speed cinematographic techniques, the discharge propagation has been studied with a one nanosecond time resolution. The ultra-fast propagation zone of anode-directed streamer has been linked with the intervention of distance ionization process. The arrival of the streamers on the anode induces the beginning of an ionization front propagating towards the cathode [fr

  9. Experimental investigation of electronic and magnetic properties of LaAlO{sub 3}-SrTiO{sub 3} interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Richter, Christoph

    2013-02-08

    This thesis is an experimental study of the interface between LaAlO{sub 3} (LAO) and SrTiO{sub 3} (STO). Both materials are non-magnetic insulators. LAO-STO interfaces, however, can be conducting, and even superconducting at millikelvin temperatures. Moreover, using cantilever-based torque magnetometry we have found a ferromagnetic-like ordering at such interfaces that coexists with the superconductivity. To gain insight into the underlying electronic structure I have developed and built solid-state planar tunnel devices with LAO-STO interfaces as one tunneling electrode. Using these devices the electronic density of states (DOS) of normal- and superconducting LAO-STO interfaces was mapped with tunneling spectroscopy. Since the charge carrier density at LAO-STO interfaces is highly tunable with electrostatic gating, the spectral DOS of the 2D-superconductor could be explored across a wide T,n-phase diagram. The main result bears a striking resemblance to the pseudogap-phase of high-temperature cuprate superconductors. The appendix reports on possible technical applications of LAO-STO interfaces in field-effect transistors and integrated circuits. Furthermore, it contains extensive experimental results concerning alternative growth procedures and related material systems. The LAO-STO interface is established as a representative of a broader class of conducting oxide interfaces. In particular, a conducting oxide interface without SrTiO{sub 3}, the LaAlO{sub 3}-CaTiO{sub 3} interface, is investigated.

  10. An R-matrix study of electron induced processes in BF3 plasma

    Science.gov (United States)

    Gupta, Dhanoj; Chakrabarti, Kalyan; Yoon, Jung-Sik; Song, Mi-Young

    2017-12-01

    An R-matrix formalism is used to study electron collision with the BF3 molecule using Quantemol-N, a computational system for electron molecule collisions which uses the molecular R-matrix method. Several target models are tested for BF3 in its equilibrium geometry, and the results are presented for the best model. Scattering calculations are then performed to yield resonance parameters, elastic, differential, excitation, and momentum transfer cross sections. The results for all the cross sections are compared with the experimental and theoretical data, and a good agreement is obtained. The resonances have been detected at 3.79 and 13.58 eV, with the ionization threshold being 15.7 eV. We have also estimated the absolute dissociative electron attachment (DEA) cross section for the F- ion production from BF3, which is a maiden attempt. The peak of the DEA is at around 13.5 eV, which is well supported by the resonance detected at 13.58 eV. The cross sections reported here find a variety of applications in the plasma technology.

  11. The Impact of Diagnostic Code Misclassification on Optimizing the Experimental Design of Genetic Association Studies

    Directory of Open Access Journals (Sweden)

    Steven J. Schrodi

    2017-01-01

    Full Text Available Diagnostic codes within electronic health record systems can vary widely in accuracy. It has been noted that the number of instances of a particular diagnostic code monotonically increases with the accuracy of disease phenotype classification. As a growing number of health system databases become linked with genomic data, it is critically important to understand the effect of this misclassification on the power of genetic association studies. Here, I investigate the impact of this diagnostic code misclassification on the power of genetic association studies with the aim to better inform experimental designs using health informatics data. The trade-off between (i reduced misclassification rates from utilizing additional instances of a diagnostic code per individual and (ii the resulting smaller sample size is explored, and general rules are presented to improve experimental designs.

  12. Experimental study of surface quality and damage when drilling unidirectional CFRP composites

    Directory of Open Access Journals (Sweden)

    Eshetu D. Eneyew

    2014-10-01

    Full Text Available In this study, an experimental investigation on the drilling of unidirectional carbon fiber reinforced plastic (UD-CFRP composite was conducted using polycrystalline diamond (PCD tipped eight facet drill. The quality of the drilled hole surface was examined through surface roughness measurements and surface damage by scanning electron microscopy (SEM. It was found that fiber pullout occurred in two specific sectors relative to the angle between the cutting direction and the fiber orientation. The thrust force was highly influenced by the feed rate than the cutting speed and it shows a significant variation throughout the rotation of the drill.

  13. Calculated fraction of an incident current pulse that will be accelerated by an electron linear accelerator and comparisons with experimental data

    International Nuclear Information System (INIS)

    Alsmiller, R.G. Jr.; Alsmiller, F.S.; Lewis, T.A.

    1986-05-01

    In a series of previous papers, calculated results obtained using a one-dimensional ballistic model were presented to aid in the design of a prebuncher for the Oak Ridge Electron Linear Accelerator. As part of this work, a model was developed to provide limits on the fraction of an incident current pulse that would be accelerated by the existing accelerator. In this paper experimental data on this fraction are presented and the validity of the model developed previously is tested by comparing calculated and experimental data. Part of the experimental data is used to fix the physical parameters in the model and then good agreement between the calculated results and the rest of the experimental data is obtained

  14. Experimental study of linear magnetic dichroism in photoionization satellite transitions of atomic rubidium

    International Nuclear Information System (INIS)

    Jaenkaelae, K.; Alagia, M.; Feyer, V.; Richter, R.; Prince, K. C.

    2011-01-01

    Laser orientation in the initial state has been used to study the properties of satellite transitions in inner-shell photoionization of rubidium atoms. The linear magnetic dichroism in the angular distribution (LMDAD) has been utilized to probe the continuum waves of orbital angular momentum conserving monopole, and angular momentum changing conjugate satellites, accompanying the 4p ionization of atomic Rb. We show experimentally that LMDAD of both types of satellite transitions is nonzero and that LMDAD of monopole satellites, measured as a function of photon energy, mimics the LMDAD of direct photoionization, whereas the LMDAD of conjugate transitions deviates drastically from that trend. The results indicate that conjugate transitions cannot be described theoretically without explicit inclusion of electron-electron interaction. The present data can thus be used as a very precise test of current models for photoionization.

  15. High pressure structural behavior of YGa2: A combined experimental and theoretical study

    International Nuclear Information System (INIS)

    Sekar, M.; Shekar, N.V. Chandra; Babu, R.; Sahu, P. Ch.; Sinha, A.K.; Upadhyay, Anuj; Singh, M.N.; Babu, K. Ramesh; Appalakondaiah, S.; Vaitheeswaran, G.; Kanchana, V.

    2015-01-01

    High pressure structural stability studies were carried out on YGa 2 (AlB 2 type structure at NTP, space group P6/mmm) up to a pressure of ~35 GPa using both laboratory based rotating anode and synchrotron X-ray sources. An isostructural transition with reduced c/a ratio, was observed at ~6 GPa and above ~17.5 GPa, the compound transformed to orthorhombic structure. Bulk modulus B 0 for the parent and high pressure phases were estimated using Birch–Murnaghan and modified Birch–Murnaghan equation of state. Electronic structure calculations based on projector augmented wave method confirms the experimentally observed two high pressure structural transitions. The calculations also reveal that the ‘Ga’ networks remains as two dimensional in the high pressure isostructural phase, whereas the orthorhombic phase involves three dimensional networks of ‘Ga’ atoms interconnected by strong covalent bonds. - Graphical abstract: High pressure X-ray diffraction patterns of YGa 2 up to ~35 GPa shows an isostructural phase transition at ~5 GPa and transition to an orthorhombic structure ~14 GPa. - Highlights: • High pressure structural stability studies were carried out on YGa 2 up to 35 GPa. • An isostructural transition with reduced c/a ratio was observed above 6 GPa. • Above 17.5 GPa, the compound transformed to orthorhombic structure. • PAW based electronic structure calculations have been carried out. • Calculations confirm the experimentally observed structural transitions

  16. Theoretical modeling of the spectroscopic absorption properties of luciferin and oxyluciferin: A critical comparison with recent experimental studies

    Energy Technology Data Exchange (ETDEWEB)

    Anselmi, Massimiliano, E-mail: m.anselmi@caspur.it [Department of Chemistry, University of Rome ' La Sapienza' , P.le Aldo Moro 5, 00185 Rome (Italy); Marocchi, Simone [Department of Chemistry, University of Rome ' La Sapienza' , P.le Aldo Moro 5, 00185 Rome (Italy); Aschi, Massimiliano [Department of Chemistry, Chemical Engineering and Materials, University of L' Aquila, Via Vetoio (Coppito 1), 67100 Coppito, L' Aquila (Italy); Amadei, Andrea [Department of Chemistry, University of Rome ' Tor Vergata' , Via della Ricerca Scientifica 1, 00133 Rome (Italy)

    2012-01-02

    Highlights: Black-Right-Pointing-Pointer The calculated absorption spectra were compared with experimental data. Black-Right-Pointing-Pointer Shapes and absorption maxima were reproduced for luciferin and oxyluciferin spectra. Black-Right-Pointing-Pointer The effect of the solvent largely changes the electronic transition probabilities. Black-Right-Pointing-Pointer Higher excitations provide an important contribution to the main absorption peak. - Abstract: Firefly luciferin and its oxidated form, oxyluciferin, are two heterocyclic compounds involved in the enzymatic reaction, catalyzed by redox proteins called luciferases, which provides the bioluminescence in a wide group of arthropods. Whereas the electronic absorption spectra of D-luciferin in water at different pHs are known since 1960s, only recently reliable experimental electronic spectra of oxyluciferin have become available. In addition oxyluciferin is involved in a triple chemical equilibria (deprotonation of the two hydroxyl groups and keto-enol tautomerism of the 4-hydroxythiazole ring), that obligates to select during an experiment a predominant species, tuning pH or solvent polarity besides introducing chemical modifications. In this study we report the absorption spectra of luciferin and oxyluciferin in each principal chemical form, calculated by means of perturbed matrix method (PMM), which allowed us to successfully introduce the effect of the solvent on the spectroscopic absorption properties, and compare the result with available experimental data.

  17. Theoretical and experimental studies of elementary physics. Annual technical progress report, November 1, 1992--October 31, 1993

    Energy Technology Data Exchange (ETDEWEB)

    Bodek, A.; Ferbel, T.; Melissinos, A.C.; Slattery, P.; Tipton, P.; Das, A.; Hagen, C.R.; Rajeev, S.G.; Okubo, S.; Orr, L.

    1993-05-01

    The various components of the high-energy physics research program at the University of Rochester are presented. (I)Fixed-target experimentation at FNAL includes studies of direct photon production by p and {pi} on H, Be, and Cu, and hybrid mesons and other physics issues in Coulomb excitation at high energies. (II)The status of the GEM (Gammas, Electrons, and Muons) Experiment at the SSC is given. (III)The D-Zero experiment at FNAL is reviewed. (IV)Deep inelastic lepton--nucleon scattering experiments are summarized: electron scattering experiments at SLAC, FNAL neutrino quad triplet runs, FNAL neutrino sign selected experiments, and SDC cosmic ray test and test beam calibration. (V)Studies of nonlinear QED at SLAC concentrated on a study of QED at critical field strength in intense laser--high-energy electron collisions. (VI)Development work on the Collider Detector at Fermilab (CDF) emphasized the CDF silicon vertex detector, the end plug calorimeter, and the SDC tile/fiber calorimetry. (VII)The theoretical physics effort is sketched.

  18. Ab initio study of low-energy electrons interacting with HCN molecules

    International Nuclear Information System (INIS)

    Jain, A.; Norcross, D.W.

    1984-01-01

    Our earlier study of low-energy electron scattering with HCN molecules is further improved by treating exchange exactly (in a separable exchange approximation 2 ) in Σ, π and Δ symmetries: the 3.8 eV π resonance is shifted towards lower energy (2.56 eV, the experimental position is around 2.26 eV 3 ), while in Σ and the Δ symmetries the difference is within 15%. We also study possible negative ion states of HCN by calculating potential energy curves with respect to C-H and C-N stretches. For example, there is evidence of an avoiding crossing between a 1Σ + and a 2Σ + state (C-H stretch) of HCN -

  19. Study of the Effects of the Electric Field on Charging Measurements on Individual Micron-size Dust Grains by Secondary Electron Emissions

    Science.gov (United States)

    Tankosic, D.; Abbas, M. M.

    2013-01-01

    The dust charging by electron impact is an important dust charging process in Astrophysical, Planetary, and the Lunar environments. Low energy electrons are reflected or stick to the grains charging the dust grains negatively. At sufficiently high energies electrons penetrate the grain leading to excitation and emission of electrons referred to as secondary electron emission (SEE). Available theoretical models for the calculation of SEE yield applicable for neutral, planar or bulk surfaces are generally based on Sternglass Equation. However, viable models for charging of individual dust grains do not exist at the present time. Therefore, the SEE yields have to be obtained by some experimental methods at the present time. We have conducted experimental studies on charging of individual micron size dust grains in simulated space environments using an electrodynamic balance (EDB) facility at NASA-MSFC. The results of our extensive laboratory study of charging of individual micron-size dust grains by low energy electron impact indicate that the SEE by electron impact is a very complex process expected to be substantially different from the bulk materials. It was found that the incident electrons may lead to positive or negative charging of dust grains depending upon the grain size, surface potential, electron energy, electron flux, grain composition, and configuration. In this paper we give a more elaborate discussion about the possible effects of the AC field in the EDB on dust charging measurements by comparing the secondary electron emission time-period (tau (sub em) (s/e)) with the time-period (tau (sub ac) (ms)) of the AC field cycle in the EDB that we have briefly addressed in our previous publication.

  20. Polarized Electrons at Jefferson Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Sinclair, C.K.

    1997-12-31

    The CEBAF accelerator at Jefferson laboratory can deliver CW electron beams to three experimental halls simultaneously. A large fraction of the approved scientific program at the lab requires polarized electron beams. Many of these experiments, both polarized and unpolarized, require high average beam current as well. Since all electrons delivered to the experimental halls originate from the same cathode, delivery of polarized beam to a single hall requires using the polarized source to deliver beam to all experiments in simultaneous operation. The polarized source effort at Jefferson Lab is directed at obtaining very long polarized source operational lifetimes at high average current and beam polarization; at developing the capability to deliver all electrons leaving the polarized source to the experimental halls; and at delivering polarized beam to multiple experimental halls simultaneously.initial operational experience with the polarized source will be presented.

  1. An experimental analysis of the waveguide modes in a high-gain free-electron laser amplifier

    International Nuclear Information System (INIS)

    Anderson, B.R.

    1989-01-01

    The presence, growth, and interaction of transverse waveguide modes in high-gain free-electron laser (FEL) amplifiers has been observed and studied. Using the Electron Laser Facility at Lawrence Livermore National Laboratory, a 3 MeV, 800 A electron beam generated by the Experimental Test Accelerator was injected into a planar wiggler. Power was then extracted and measured in the fundamental (TE 01 ) an higher-order modes (Te 21 and TM 21 ) under various sets of operating conditions. Horizontal focusing through the wiggler was provided by external quadrupole magnets. There was no axial guide field. The input microwave signal for amplification was generated by a 100 kW magnetron operating at 34.6 Ghz. Power measurements were taken for both flat and tapered wigglers, for two sizes of waveguide, and for both flat and tapered wigglers, for two sizes of waveguide, and for both fundamental and higher mode injection. Mode content was determined by sampling the radiated signal at specific points in the radiation patter. For the flat wiggler and with the large waveguide (2.9 cm x 9.8 cm) the power in the higher modes was comparable to power in the fundamental. both exhibited gains greater than 30 dB/m prior to saturation and both reached powers in excess of 80 MW. Choice of injection mode had little effect on the operation of the system. Operation with the smaller guide (WR-229) provided much better mode selectivity. The fundamental mode continued to show optimum gain in excess of 30 dB/m while the higher-mode gain was of order 20 dB/m. As expected, power output increased significantly with the tapered wigglers. The relative mode content depended on the specific taper used

  2. Electron emission from solids induced by swift heavy ions

    International Nuclear Information System (INIS)

    Xiao Guoqing

    2000-01-01

    The recent progresses in experimental and theoretical studies of the collision between swift heavy ion and solids as well as electron emission induced by swift heavy ion in solids were briefly reviewed. Three models, Coulomb explosion, thermal spike and repulsive long-lived states, for interpreting the atomic displacements stimulated by the electronic energy loss were discussed. The experimental setup and methods for measuring the electron emission from solids were described. The signification deviation from a proportionality between total electron emission yields and electronic stopping power was found. Auger-electron and convoy-electron spectra are thought to be a probe for investigating the microscopic production mechanisms of the electronic irradiation-damage. Electron temperature and track potential at the center of nuclear tracks in C and polypropylene foils induced by 5 MeV/u heavy ions, which are related to the electronic excitation density in metals and insulators respectively, were extracted by measuring the high resolution electron spectra

  3. Relativistic electron transport in a solid target: study of heating in the framework of inertial fusion

    International Nuclear Information System (INIS)

    Martinolli, E.

    2003-04-01

    This work is dedicated to the study of the energy deposition of fast electrons in matter. This topic is of prime importance for inertial fusion driven by laser since relativistic electrons are produced in laser-matter interaction for a laser operating in ultra-intense regime. This thesis is made up of: a theoretical chapter dealing with the generation and transport of fast electrons, of 2 chapters reporting experimental data obtained with optical and X-rays diagnostics at the laser facilities of LULI in France and RAL in U.K., and of a chapter dedicated to the simulation of electron transport by using a Monte-Carlo code combined to a hybrid collisional-electromagnetic PIC code. A new spectrometer has been designed: the detection of Kα rays coming from a fluorescent layer embedded in the target has allowed us to assess the size of the electron beam and the level of ionisation. (A.C.)

  4. First-principles studies of electronic, transport and bulk properties of pyrite FeS2

    Directory of Open Access Journals (Sweden)

    Dipendra Banjara

    2018-02-01

    Full Text Available We present results from first principle, local density approximation (LDA calculations of electronic, transport, and bulk properties of iron pyrite (FeS2. Our non-relativistic computations employed the Ceperley and Alder LDA potential and the linear combination of atomic orbitals (LCAO formalism. The implementation of the LCAO formalism followed the Bagayoko, Zhao, and Williams (BZW method, as enhanced by Ekuma and Franklin (BZW-EF. We discuss the electronic energy bands, total and partial densities of states, electron effective masses, and the bulk modulus. Our calculated indirect band gap of 0.959 eV (0.96, using an experimental lattice constant of 5.4166 Å, at room temperature, is in agreement with the measured indirect values, for bulk samples, ranging from 0.84 eV to 1.03 ± 0.05 eV. Our calculated bulk modulus of 147 GPa is practically in agreement with the experimental value of 145 GPa. The calculated, partial densities of states reproduced the splitting of the Fe d bands to constitute the dominant upper most valence and lower most conduction bands, separated by the generally accepted, indirect, experimental band gap of 0.95 eV.

  5. Resonant tunneling of electrons in quantum wires

    International Nuclear Information System (INIS)

    Krive, I.V.; Shekhter, R.I.; Jonson, M.; Krive, I.V.

    2010-01-01

    We considered resonant electron tunneling in various nanostructures including single wall carbon nanotubes, molecular transistors and quantum wires formed in two-dimensional electron gas. The review starts with a textbook description of resonant tunneling of noninteracting electrons through a double-barrier structure. The effects of electron-electron interaction in sequential and resonant electron tunneling are studied by using Luttinger liquid model of electron transport in quantum wires. The experimental aspects of the problem (fabrication of quantum wires and transport measurements) are also considered. The influence of vibrational and electromechanical effects on resonant electron tunneling in molecular transistors is discussed.

  6. Atomic imaging using secondary electrons in a scanning transmission electron microscope: experimental observations and possible mechanisms.

    Science.gov (United States)

    Inada, H; Su, D; Egerton, R F; Konno, M; Wu, L; Ciston, J; Wall, J; Zhu, Y

    2011-06-01

    We report detailed investigation of high-resolution imaging using secondary electrons (SE) with a sub-nanometer probe in an aberration-corrected transmission electron microscope, Hitachi HD2700C. This instrument also allows us to acquire the corresponding annular dark-field (ADF) images both simultaneously and separately. We demonstrate that atomic SE imaging is achievable for a wide range of elements, from uranium to carbon. Using the ADF images as a reference, we studied the SE image intensity and contrast as functions of applied bias, atomic number, crystal tilt, and thickness to shed light on the origin of the unexpected ultrahigh resolution in SE imaging. We have also demonstrated that the SE signal is sensitive to the terminating species at a crystal surface. A possible mechanism for atomic-scale SE imaging is proposed. The ability to image both the surface and bulk of a sample at atomic-scale is unprecedented, and can have important applications in the field of electron microscopy and materials characterization. Copyright © 2010 Elsevier B.V. All rights reserved.

  7. Attosecond electron pulse trains and quantum state reconstruction in ultrafast transmission electron microscopy

    Science.gov (United States)

    Priebe, Katharina E.; Rathje, Christopher; Yalunin, Sergey V.; Hohage, Thorsten; Feist, Armin; Schäfer, Sascha; Ropers, Claus

    2017-12-01

    Ultrafast electron and X-ray imaging and spectroscopy are the basis for an ongoing revolution in the understanding of dynamical atomic-scale processes in matter. The underlying technology relies heavily on laser science for the generation and characterization of ever shorter pulses. Recent findings suggest that ultrafast electron microscopy with attosecond-structured wavefunctions may be feasible. However, such future technologies call for means to both prepare and fully analyse the corresponding free-electron quantum states. Here, we introduce a framework for the preparation, coherent manipulation and characterization of free-electron quantum states, experimentally demonstrating attosecond electron pulse trains. Phase-locked optical fields coherently control the electron wavefunction along the beam direction. We establish a new variant of quantum state tomography—`SQUIRRELS'—for free-electron ensembles. The ability to tailor and quantitatively map electron quantum states will promote the nanoscale study of electron-matter entanglement and new forms of ultrafast electron microscopy down to the attosecond regime.

  8. Enhancement of the solubility, thermal stability, and electronic properties of carbon nanotubes functionalized with MEH-PPV: A combined experimental and computational study

    International Nuclear Information System (INIS)

    Prajongtat, P.; Suramitr, S.; Hannongbua, S.; Gleeson, M.P.; Mitsuke, K.

    2013-01-01

    Multi-walled carbon nanotubes (MWCNTs) functionalized with poly[2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylenevinylene] (MWCNT-f-MEH-PPV) nanocomposites were successfully prepared by employing a “grafting from” approach. The content of the functionalizing MEH-PPV in the composites was observed as 76 wt.%. Compared with pristine MWCNTs (p-MWCNT), the aqueous solubility and thermal stability of the former are significantly enhanced. The effect of covalently and non-covalently functionalized nanotubes on dye-sensitized solar cell performance was also studied. Solar cells were successfully fabricated from isolated MEH-PPV, p-MWCNT/MEH-PPV, and MWCNT-f-MEH-PPV/MEH-PPV counter electrodes. The devices based on a MWCNT-f-MEH-PPV/MEH-PPV counter electrode demonstrated the best photovoltaic performance as observed by higher J SC, V OC, and fill factor (FF) values. The experimental phenomena can be explained by quantum-chemical calculations: Charge transfer from MEH-PPV oligomers to nanotubes is greater when covalently functionalized compared with non-covalently functionalized. This suggests that the improvement in the photovoltaic parameters of the cells containing covalently functionalized nanotubes results not only from the higher concentration present in the nanotube films of the counter electrode, but also from the greater electron delocalization between the oligomers and nanotubes. (author)

  9. Contribution to the study of point defects formed in nickel by electron bombardment

    International Nuclear Information System (INIS)

    Oddou, J.L.

    1968-12-01

    After a short account of the experimental techniques employed in our studies, the experimental results obtained on pure nickel samples are exposed. The apparition of the successive annihilation stages of point defects created by electron bombardment is established by isochronal heat treatments: the annihilation kinetics and the corresponding activation energies are determined. The effect of the incident particle doses is also studied. The experimental results are then compared with R.A. Johnson's theoretical calculations of the stability and the migration of point defects in nickel, and taking into account the results obtained by Peretto in magnetic after effect measurements. This leads us to a model in good agreement with calculations and experiment for the first stages. In a second chapter the behaviour of nickel doped by certain impurities is studied. First, the results concerning the rate of increase of resistivity (function of sample purity) is investigated. Two possible explanations of the observed phenomenon are proposed: either a deviation with respect to Mathiessen's law, or an increase of the number of defects formed in the presence of impurity atoms. Finally, a study of the resistivity recovery of the doped samples permits us to suggest an order of magnitude for the binding energy interstitial/impurity atom in the nickel matrix. (author) [fr

  10. Study of profile control and suprathermal electron production with lower hybrid waves

    International Nuclear Information System (INIS)

    Soeldner, F.X.; Brambilla, M.; Leuterer, F.; Muenich, M.

    1986-05-01

    In this study the coupling of LH waves to suprathermal electrons, the LH current drive efficiency and the mechanism for sawtooth stabilisation will be discussed. A wide data base has been obtained by the LH experiments on Alcator C, ASDEX, FT; JFT-2M, JIPPT-IIU, Petula, PLT, Versator, WT II during the last years and important aspects as the scaling of global current drive efficiency are satisfactorily described by theory. We mainly rely here on experimental results from ASDEX and comparison with theoretical calculations by Fisch and Karney. (orig.)

  11. Experimental validation of a radio frequency photogun as external electron

    NARCIS (Netherlands)

    Stragier, X.F.D.; Luiten, O.J.; Geer, van der S.B.; Wiel, van der M.J.

    2011-01-01

    A purpose-built RF-photogun as external electron injector for a laser wakefield accelerator has been thoroughly tested. Different properties of the RF-photogun have been measured such as energy, energy spread and transverse emittance. The focus of this study is the investigation of the smallest

  12. Atomic and electronic structure of exfoliated black phosphorus

    International Nuclear Information System (INIS)

    Wu, Ryan J.; Topsakal, Mehmet; Jeong, Jong Seok; Wentzcovitch, Renata M.; Mkhoyan, K. Andre; Low, Tony; Robbins, Matthew C.; Haratipour, Nazila; Koester, Steven J.

    2015-01-01

    Black phosphorus, a layered two-dimensional crystal with tunable electronic properties and high hole mobility, is quickly emerging as a promising candidate for future electronic and photonic devices. Although theoretical studies using ab initio calculations have tried to predict its atomic and electronic structure, uncertainty in its fundamental properties due to a lack of clear experimental evidence continues to stymie our full understanding and application of this novel material. In this work, aberration-corrected scanning transmission electron microscopy and ab initio calculations are used to study the crystal structure of few-layer black phosphorus. Directly interpretable annular dark-field images provide a three-dimensional atomic-resolution view of this layered material in which its stacking order and all three lattice parameters can be unambiguously identified. In addition, electron energy-loss spectroscopy (EELS) is used to measure the conduction band density of states of black phosphorus, which agrees well with the results of density functional theory calculations performed for the experimentally determined crystal. Furthermore, experimental EELS measurements of interband transitions and surface plasmon excitations are also consistent with simulated results. Finally, the effects of oxidation on both the atomic and electronic structure of black phosphorus are analyzed to explain observed device degradation. The transformation of black phosphorus into amorphous PO 3 or H 3 PO 3 during oxidation may ultimately be responsible for the degradation of devices exposed to atmosphere over time

  13. Relativistic runaway electrons in tokamak plasmas

    International Nuclear Information System (INIS)

    Jaspers, R.E.

    1995-01-01

    Runaway electrons are inherently present in a tokamak, in which an electric field is applied to drive a toroidal current. The experimental work is performed in the tokamak TEXTOR. Here runaway electrons can acquire energies of up to 30 MeV. The runaway electrons are studied by measuring their synchrotron radiation, which is emitted in the infrared wavelength range. The studies presented are unique in the sense that they are the first ones in tokamak research to employ this radiation. Hitherto, studies of runaway electrons revealed information about their loss in the edge of the discharge. The behaviour of confined runaways was still a terra incognita. The measurement of the synchrotron radiation allows a direct observation of the behaviour of runaway electrons in the hot core of the plasma. Information on the energy, the number and the momentum distribution of the runaway electrons is obtained. The production rate of the runaway electrons, their transport and the runaway interaction with plasma waves are studied. (orig./HP)

  14. Collaborative Research: Fundamental Studies of Plasma Control Using Surface Embedded Electronic Devices

    International Nuclear Information System (INIS)

    Overzet, Lawrence J.; Raja, L.

    2015-01-01

    The research program was collaborative between the researchers at the University of Texas at Dallas and the University of Texas at Austin. The primary subject of this program was to investigate the possibility of active control of secondary electron emission (SEE) from surfaces in contact with plasmas and thereby actively control plasmas. Very few studies of ion-induced electron emission (IIEE) from semiconductors exist, and those that do exist primarily used high-energy ion beams in the experiments. Furthermore, those few studies took extreme measures to ensure that the measurements were performed on atomically clean surfaces because of the surface sensitivity of the IIEE process. Even a small exposure to air can change the IIEE yield significantly. In addition, much of the existing data for IIEE from semiconductors was obtained in the 1950s and '60s, when semiconductor materials were first being refined. As a result, nearly all of that data is for p-type Ge and Si. Before this investigation, experimental data on n-type materials was virtually non-existent. While the basic theory assumed that IIEE yields ought to be substantially independent of doping type and concentration, recent measurements of near atmospheric pressure plasmas and of breakdown suggested otherwise. These indirect measurements were made on surfaces that were not atomically clean and seemed to indicate that deep sub-surface changes to the bulk conduction band electron density could lead to substantial variations in the IIEE yield. Exactly in contradiction to the generally accepted theory. Insufficient direct data existed to settle the matter. We performed both experimental measurements and theoretical calculations of IIEE yields from both Si and Ge in order to help clarify whether or not conduction band electrons substantially change the IIEE yield. We used three wafers of each material to carry out the investigation: a heavily doped p-type, an intrinsic and a heavily doped n-type wafer. There