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Sample records for electron traps ii

  1. Characteristics of trapped electrons and electron traps in single crystals

    International Nuclear Information System (INIS)

    Budzinski, E.E.; Potter, W.R.; Potienko, G.; Box, H.C.

    1979-01-01

    Two additional carbohydrates are reported whose crystal structures trap electrons intermolecularly in single crystals x irradiated at low temperature, namely sucrose and rhamnose. Five carbohydrate and polyhydroxy compounds are now known which exhibit this phenomenon. The following characteristics of the phenomenon were investigated: (1) the hyperfine couplings of the electron with protons of the polarized hydroxy groups forming the trap; (2) the distances between these protons and the trapped electron; (3) the spin density of the electron at the protons and (4) the relative stabilities of the electron trapped in various crystal structures

  2. Effects of the radial electric field on confinement and trapping for non collisional electrons in TJ-II

    International Nuclear Information System (INIS)

    Guasp, J.; Liniers, M.

    1998-01-01

    The effects of radial electric fields on the non collisional losses, asymmetries at plasma border and on the Vacuum Vessel and trapping fractions for 0.1 1 KeV electrons in TJ-II are analysed. This study complements a series, already published, for ions, therefore only the main differences are stressed. Many of these effect are similar for electrons and ions, mainly the drastic decrease of losses with the electric field, the increasing peripherical loss concentration, the strong accumulation on the Hard Core (HC), the modification in the direction of the induced poloidal rotation, similar angular distributions for trapped particles, etc. Nevertheless, there appear also important differences, that in many cases are originated by the higher electron mobility, in particular a higher sensitivity to the electric field, as well to the intensity as to the sign, producing a faster drop in electron losses for positive potential and a higher asymmetry in the sign dependence. Most of these electron losses exit through the upper side of the plasma, the opposite happens for ions. The strong concentration on the HC appears, many, on the PL-1 plate (the one that is placed upside for toroidal angle φ=0 degree centigree), instead of the opposite PL-2 plate for ions.Finally, for the analysed energy range, there is no variation of electron trapping with the potential nor resonant effect. (Author) 8 refs

  3. MOS Capacitance—Voltage Characteristics II. Sensitivity of Electronic Trapping at Dopant Impurity from Parameter Variations

    International Nuclear Information System (INIS)

    Jie Binbin; Sah Chihtang

    2011-01-01

    Low-frequency and high-frequency Capacitance—Voltage (C—V) curves of Metal—Oxide—Semiconductor Capacitors (MOSC), including electron and hole trapping at the dopant donor and acceptor impurities, are presented to illustrate giant trapping capacitances, from > 0.01C OX to > 10C OX . Five device and materials parameters are varied for fundamental trapping parameter characterization, and electrical and optical signal processing applications. Parameters include spatially constant concentration of the dopant-donor-impurity electron trap, N DD , the ground state electron trapping energy level depth measured from the conduction band edge, E C –E D , the degeneracy of the trapped electron at the ground state, g D , the device temperature, T, and the gate oxide thickness, x OX . (invited papers)

  4. Injection into electron plasma traps

    International Nuclear Information System (INIS)

    Gorgadze, Vladimir; Pasquini, Thomas A.; Fajans, Joel; Wurtele, Jonathan S.

    2003-01-01

    Computational studies and experimental measurements of plasma injection into a Malmberg-Penning trap reveal that the number of trapped particles can be an order of magnitude higher than predicted by a simple estimates based on a ballistic trapping model. Enhanced trapping is associated with a rich nonlinear dynamics generated by the space-charge forces of the evolving trapped electron density. A particle-in-cell simulation is used to identify the physical mechanisms that lead to the increase in trapped electrons. The simulations initially show strong two-stream interactions between the electrons emitted from the cathode and those reflected off the end plug of the trap. This is followed by virtual cathode oscillations near the injection region. As electrons are trapped, the initially hollow longitudinal phase-space is filled, and the transverse radial density profile evolves so that the plasma potential matches that of the cathode. Simple theoretical arguments are given that describe the different dynamical regimes. Good agreement is found between simulation and theory

  5. Electron trapping during irradiation in reoxidized nitrided oxide

    International Nuclear Information System (INIS)

    Mallik, A.; Vasi, J.; Chandorkar, A.N.

    1993-01-01

    Isochronal detrapping experiments have been performed following irradiation under different gate biases in reoxidized nitrided oxide (RNO) MOS capacitors. These show electron trapping by the nitridation-induced electron traps at low oxide fields during irradiation. A difference in the detrapping behavior of trapped holes and electrons is observed, with trapped holes being detrapped at relatively lower temperatures compared to trapped electrons. Electron trapping shows a strong dependence on tile magnitude of the applied gate bias during irradiation but is independent of its polarity. Conventional oxide devices, as expected, do not show any electron trapping during irradiation by the native electron traps. Finally, a comparison of the isochronal detrapping behavior following irradiation and following avalanche injection of electrons has been made to estimate the extent of electron trapping. The results show that electron trapping by the nitridation-induced electron traps does not play the dominant role in improving radiation performance of RNO, though its contribution cannot be completely neglected for low oxide field irradiations

  6. Electron traps in semiconducting polymers : Exponential versus Gaussian trap distribution

    NARCIS (Netherlands)

    Nicolai, H. T.; Mandoc, M. M.; Blom, P. W. M.

    2011-01-01

    The low electron currents in poly(dialkoxy-p-phenylene vinylene) (PPV) derivatives and their steep voltage dependence are generally explained by trap-limited conduction in the presence of an exponential trap distribution. Here we demonstrate that the electron transport of several PPV derivatives can

  7. Electron traps in semiconducting polymers: exponential versus Gaussian trap distribution

    NARCIS (Netherlands)

    Nicolai, H.T.; Mandoc, M.M.; Blom, P.W.M.

    2011-01-01

    The low electron currents in poly(dialkoxy-p-phenylene vinylene) (PPV) derivatives and their steep voltage dependence are generally explained by trap-limited conduction in the presence of an exponential trap distribution. Here we demonstrate that the electron transport of several PPV derivatives can

  8. Stability of trapped electrons in SiO2

    International Nuclear Information System (INIS)

    Fleetwood, D.M.; Winokur, P.S.; Flament, O.; Leray, J.L.

    1998-01-01

    Electron trapping near the Si/SiO 2 interface plays a crucial role in mitigating the response of MOS devices to ionizing radiation or high-field stress. These electrons offset positive charge due to trapped holes, and can be present at densities exceeding 10 12 cm -2 in the presence of a similar density of trapped positive charge. The nature of the defects that serve as hosts for trapped electrons in the near-interfacial SiO 2 is presently unknown, although there is compelling evidence that these defects are often intimately associated with trapped holes. This association is depicted most directly in the model of Lelis et al., which suggests that trapped electrons and holes occupy opposite sides of a compensated E center in SiO 2 . Charge exchange between electron traps and the Si can occur over a wide range of time scales, depending on the trap depth and location relative to the Si/SiO 2 interface. Here the authors report a detailed study of the stability of electron traps associated with trapped holes near the Si/SiO 2 interface

  9. Stability of Trapped Electrons in SiO(2)

    International Nuclear Information System (INIS)

    Fleetwood, D.M.; Winokur, P.S.

    1999-01-01

    Thermally stimulated current and capacitance voltage methods are used to investigate the thermal stability of trapped electrons associated with radiation-induced trapped positive charge in metal-oxide-semiconductor capacitors. The density of deeply trapped electrons in radiation-hardened 45 nm oxides exceeds that of shallow electrons by a factor of ∼3 after radiation exposure, and by up to a factor of 10 or more during biased annealing. Shallow electron traps anneal faster than deep traps, and seem to be at least qualitatively consistent with the model of Lelis et al. Deeper traps maybe part of a fundamentally distinct dipole complex, and/or have shifted energy levels that inhibit charge exchange with the Si

  10. Electron scattering by trapped fermionic atoms

    International Nuclear Information System (INIS)

    Wang Haijun; Jhe, Wonho

    2002-01-01

    Considering the Fermi gases of alkali-metal atoms that are trapped in a harmonic potential, we study theoretically the elastic and inelastic scattering of the electrons by the trapped Fermi atoms and present the corresponding differential cross sections. We also obtain the stopping power for the cases that the electronic state as well as the center-of-mass state are excited both separately and simultaneously. It is shown that the elastic scattering process is no longer coherent in contrast to the electron scattering by the atomic Bose-Einstein condensate (BEC). For the inelastic scattering process, on the other hand, the differential cross section is found to be proportional to the 2/3 power of the number of the trapped atoms. In particular, the trapped fermionic atoms display the effect of ''Fermi surface,'' that is, only the energy levels near the Fermi energy have dominant contributions to the scattering process. Moreover, it is found that the stopping power scales as the 7/6 power of the atomic number. These results are fundamentally different from those of the electron scattering by the atomic BEC, mainly due to the different statistics obeyed by the trapped atomic systems

  11. A nonlinear bounce kinetic equation for trapped electrons

    International Nuclear Information System (INIS)

    Gang, F.Y.

    1990-03-01

    A nonlinear bounce averaged drift kinetic equation for trapped electrons is derived. This equation enables one to compute the nonlinear response of the trapped electron distribution function in terms of the field-line projection of a potential fluctuation left-angle e -inqθ φ n right-angle b . It is useful for both analytical and computational studies of the nonlinear evolution of short wavelength (n much-gt 1) trapped electron mode-driven turbulence. 7 refs

  12. Trapping in GaN-based metal-insulator-semiconductor transistors: Role of high drain bias and hot electrons

    Energy Technology Data Exchange (ETDEWEB)

    Meneghini, M., E-mail: matteo.meneghini@dei.unipd.it; Bisi, D.; Meneghesso, G.; Zanoni, E. [Department of Information Engineering, University of Padova, via Gradenigo 6/B, 35131 Padova (Italy); Marcon, D.; Stoffels, S.; Van Hove, M.; Wu, T.-L.; Decoutere, S. [IMEC, Kapeldreef 75, 3001 Heverlee (Belgium)

    2014-04-07

    This paper describes an extensive analysis of the role of off-state and semi-on state bias in inducing the trapping in GaN-based power High Electron Mobility Transistors. The study is based on combined pulsed characterization and on-resistance transient measurements. We demonstrate that—by changing the quiescent bias point from the off-state to the semi-on state—it is possible to separately analyze two relevant trapping mechanisms: (i) the trapping of electrons in the gate-drain access region, activated by the exposure to high drain bias in the off-state; (ii) the trapping of hot-electrons within the AlGaN barrier or the gate insulator, which occurs when the devices are operated in the semi-on state. The dependence of these two mechanisms on the bias conditions and on temperature, and the properties (activation energy and cross section) of the related traps are described in the text.

  13. Novel extension of the trap model for electrons in liquid hydrocarbons

    International Nuclear Information System (INIS)

    Jamal, M.A.; Watt, D.E.

    1981-01-01

    A novel extension for the trap model of electron mobilities in liquid hydrocarbons is described. The new model assumes: (a) two main types of electron trap exist in liquid hydrocarbons, one is deep and the second is shallow; (b) these traps are the same in all liquid alkanes. The difference in electron mobilities in different alkanes is accounted for by the difference in the frequency of electron trapping in each state. The probability of trapping in each state has been evaluated from the known structures of the normal alkanes. Electron mobilities in normal alkanes (C 3 -C 10 ) show a very good correlation with the probability of trapping in deep traps, suggesting that the C-C bonds are the main energy sinks of the electron. A mathematical formula which expresses the electron mobility in terms of the probability of trapping in deep traps has been found from the Arrhenius relationship between electron mobilities and probability of trapping. The model has been extended for branched alkanes and the relatively high electron mobilities in globular alkanes has been explained by the fact that each branch provides some degree of screening to the skeleton structure of the molecule resulting in reduction of the probability of electron interaction with the molecular skeleton. (author)

  14. Electron Cooling of Protons in a Nested Penning Trap

    International Nuclear Information System (INIS)

    Hall, D.S.; Gabrielse, G.

    1996-01-01

    Trapped protons cool via collisions with trapped electrons at 4 K.This first demonstration of sympathetic cooling by trapped species of opposite sign of charge utilizes a nested Penning trap. The demonstrated interaction of electrons and protons at very low relative velocities, where recombination is predicted to be most rapid, indicates that this may be a route towards the study of low temperature recombination. The production of cold antihydrogen is of particular interest, and electron cooling of highly stripped ions may also be possible. copyright 1996 The American Physical Society

  15. Properties of Trapped Electron Bunches in a Plasma Wakefield Accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Kirby, Neil; /SLAC

    2009-10-30

    Plasma-based accelerators use the propagation of a drive bunch through plasma to create large electric fields. Recent plasma wakefield accelerator (PWFA) experiments, carried out at the Stanford Linear Accelerator Center (SLAC), successfully doubled the energy for some of the 42 GeV drive bunch electrons in less than a meter; this feat would have required 3 km in the SLAC linac. This dissertation covers one phenomenon associated with the PWFA, electron trapping. Recently it was shown that PWFAs, operated in the nonlinear bubble regime, can trap electrons that are released by ionization inside the plasma wake and accelerate them to high energies. These trapped electrons occupy and can degrade the accelerating portion of the plasma wake, so it is important to understand their origins and how to remove them. Here, the onset of electron trapping is connected to the drive bunch properties. Additionally, the trapped electron bunches are observed with normalized transverse emittance divided by peak current, {epsilon}{sub N,x}/I{sub t}, below the level of 0.2 {micro}m/kA. A theoretical model of the trapped electron emittance, developed here, indicates that the emittance scales inversely with the square root of the plasma density in the non-linear 'bubble' regime of the PWFA. This model and simulations indicate that the observed values of {epsilon}{sub N,x}/I{sub t} result from multi-GeV trapped electron bunches with emittances of a few {micro}m and multi-kA peak currents. These properties make the trapped electrons a possible particle source for next generation light sources. This dissertation is organized as follows. The first chapter is an overview of the PWFA, which includes a review of the accelerating and focusing fields and a survey of the remaining issues for a plasma-based particle collider. Then, the second chapter examines the physics of electron trapping in the PWFA. The third chapter uses theory and simulations to analyze the properties of the trapped

  16. Trapped electron losses by interactions with coherent VLF waves

    International Nuclear Information System (INIS)

    Walt, M.; Inan, U.S.; Voss, H.D.

    1996-01-01

    VLF whistler waves from lightning enter the magnetosphere and cause the precipitation of energetic trapped electrons by pitch angle scattering. These events, known as Lightning-induced Electron Precipitation (LEP) have been detected by satellite and rocket instruments and by perturbations of VLF waves traveling in the earth-ionosphere waveguide. Detailed comparison of precipitating electron energy spectra and time dependence are in general agreement with calculations of trapped electron interactions with ducted whistler waves. In particular the temporal structure of the precipitation and the dynamic energy spectra of the electrons confirm this interpretation of the phenomena. There are discrepancies between observed and measured electron flux intensities and pitch angle distributions, but these quantities are sensitive to unknown wave intensities and trapped particle fluxes near the loss cone angle. The overall effect of lightning generated VLF waves on the lifetime of trapped electrons is still uncertain. The flux of electrons deflected into the bounce loss cone by a discrete whistler wave has been measured in a few cases. However, the area of the precipitation region is not known, and thus the total number of electrons lost in an LEP event can only be estimated. While the LEP events are dramatic, more important effects on trapped electrons may arise from the small but numerous deflections which increase the pitch angle diffusion rate of the electron population. copyright 1996 American Institute of Physics

  17. Trapped electron losses by interactions with coherent VLF waves

    Science.gov (United States)

    Walt, M.; Inan, U. S.; Voss, H. D.

    1996-07-01

    VLF whistler waves from lightning enter the magnetosphere and cause the precipitation of energetic trapped electrons by pitch angle scattering. These events, known as Lightning-induced Electron Precipitation (LEP) have been detected by satellite and rocket instruments and by perturbations of VLF waves traveling in the earth-ionosphere waveguide. Detailed comparison of precipitating electron energy spectra and time dependence are in general agreement with calculations of trapped electron interactions with ducted whistler waves. In particular the temporal structure of the precipitation and the dynamic energy spectra of the electrons confirm this interpretation of the phenomena. There are discrepancies between observed and measured electron flux intensities and pitch angle distributions, but these quantities are sensitive to unknown wave intensities and trapped particle fluxes near the loss cone angle. The overall effect of lightning generated VLF waves on the lifetime of trapped electrons is still uncertain. The flux of electrons deflected into the bounce loss cone by a discrete whistler wave has been measured in a few cases. However, the area of the precipitation region is not known, and thus the total number of electrons lost in an LEP event can only be estimated. While the LEP events are dramatic, more important effects on trapped electrons may arise from the small but numerous deflections which increase the pitch angle diffusion rate of the electron population.

  18. Trapped electrons in irradiated single crystals of polyhydroxy compounds

    International Nuclear Information System (INIS)

    Box, H.C.; Budzinski, E.E.; Freund, H.G.; Potter, W.R.

    1979-01-01

    The intermolecular trapping of electrons has been observed in single crystals of dulcitol and L(+) arabinose x-irradiated at 4.2 0 K. Attribution of a major component of the ESR absorption to trapped electrons is based upon the character of the hyperfine pattern, which arises from multiple anisotropic hyperfine interactions with exchangeable protons, and on the g value of the absorption, which is always less than the free spin value. The removal of the trapped electron absorption upon irradiation with visible light has also been demonstrated. In these experiments all of the electrons are trapped in identical sites. This circumstance provides some important advantages in the study of the factors affecting the stabilization of charge in an environment of polarizable molecules

  19. Trapping of self-interstitials at manganese atoms in electron-irradiated dilute AlMn alloys

    International Nuclear Information System (INIS)

    Bartels, A.; Dworschak, F.

    1985-01-01

    Dilute AlMn alloys were irradiated isothermally at different temperatures in stage II with 1.8 MeV electrons and the resistivity damage rates were measured as a function of the residual resistivity increase. The results demonstrate that Mn atoms provide deep traps at least up to 150 K for mobile interstitials. A quantitative evaluation of the data with respect to trapping radii is somewhat handicapped by the fact that the resistivity contribution of a Mn-Al interstitial complex was found to be considerably less than the sum of the resistivity contributions of an isolated solute Mn atom and an Al self-interstitial. The results can be explained by a model which assumes that both the trapping radius and the resistivity contribution of solute-self-interstitial complexes increase with the number of trapped interstitials. (author)

  20. Spectroscopic analysis of electron trapping levels in pentacene field-effect transistors

    International Nuclear Information System (INIS)

    Bum Park, Chang

    2014-01-01

    Electron trapping phenomena have been investigated with respect to the energy levels of localized trap states and bias-induced device instability effects in pentacene field-effect transistors. The mechanism of the photoinduced threshold voltage shift (ΔV T ) is presented by providing a ΔV T model governed by the electron trapping. The trap-and-release behaviour functionalized by photo-irradiation also shows that the trap state for electrons is associated with the energy levels in different positions in the forbidden gap of pentacene. Spectroscopic analysis identifies two kinds of electron trap states distributed above and below the energy of 2.5 eV in the band gap of the pentacene crystal. The study of photocurrent spectra shows the specific trap levels of electrons in energy space that play a substantial role in causing device instability. The shallow and deep trapping states are distributed at two centroidal energy levels of ∼1.8 and ∼2.67 eV in the pentacene band gap. Moreover, we present a systematic energy profile of electron trap states in the pentacene crystal for the first time. (paper)

  1. Trapping of Electron Cloud LLC/Cesrta Quadrupole and Sextupole Magnets

    International Nuclear Information System (INIS)

    Wang, L.

    2011-01-01

    The Cornell Electron Storage Ring (CESR) has been reconfigured as an ultra low emittance damping ring for use as a test accelerator (CesrTA) for International Linear Collider (ILC) damping ring R and D (1). One of the primary goals of the CesrTA program is to investigate the interaction of the electron cloud with low emittance positron beam to explore methods to suppress the electron cloud, develop suitable advanced instrumentation required for these experimental studies and benchmark predictions by simulation codes. This paper reports the simulation of the electron-cloud formation in CESRTA and ILC quadrupole and sextupole magnets using the 3D code CLOUDLAND. We found that electrons can be trapped with a long lifetime in a quadrupole and sextupole magnet due to the mirror field trapping mechanism. We study the effects of magnet strength, bunch current, ante-chamber effect, bunch spacing effect and secondary emission yield (SEY) in great detail. The development of an electron cloud in magnets is the main concern where a weak solenoid field is not effective. Quadrupole and sextupole magnets have mirror field configurations which may trap electrons by the mirror field trapping mechanism (2). Fig.1 shows the orbit of a trapped electron in a quadrupole magnet. The electron makes gyration motion (called transverse motion) and also moves along the field line (called longitudinal motion). At the mirror point (middle of the field line), there is a maximum longitudinal energy and minimum transverse energy. When the electron moves away from the mirror point, its longitudinal energy reduces and the transverse energy increases as the magnetic field increases. If the magnetic field is strong enough, the longitudinal energy becomes zero at one point and then the electron is turned back by the strong field. Note that the electrons are trapped in the region near the middle of the field lines. Although all quadrupole and sextupole magnets can trap electrons in principle, the

  2. Hydration of excess electrons trapped in charge pockets on molecular surfaces

    Science.gov (United States)

    Jalbout, Abraham F.; Del Castillo, R.; Adamowicz, Ludwik

    2007-01-01

    In this work we strive to design a novel electron trap located on a molecular surface. The process of electron trapping involves hydration of the trapped electron. Previous calculations on surface electron trapping revealed that clusters of OH groups can form stable hydrogen-bonded networks on one side of a hydrocarbon surface (i.e. cyclohexane sheets), while the hydrogen atoms on the opposite side of the surface form pockets of positive charge that can attract extra negative charge. The excess electron density on such surfaces can be further stabilized by interactions with water molecules. Our calculations show that these anionic systems are stable with respect to vertical electron detachment (VDE).

  3. Slow electron acoustic double layer (SEADL) structures in bi-ion plasma with trapped electrons

    Science.gov (United States)

    Shan, Shaukat Ali; Imtiaz, Nadia

    2018-05-01

    The properties of ion acoustic double layer (IADL) structures in bi-ion plasma with electron trapping are investigated by using the quasi-potential analysis. The κ-distributed trapped electrons number density expression is truncated to some finite order of the electrostatic potential. By utilizing the reductive perturbation method, a modified Schamel equation which describes the evolution of the slow electron acoustic double layer (SEADL) with the modified speed due to the presence of bi-ion species is investigated. The Sagdeev-like potential has been derived which accounts for the effect of the electron trapping and superthermality in a bi-ion plasma. It is found that the superthermality index, the trapping efficiency of electrons, and ion to electron temperature ratio are the inhibiting parameters for the amplitude of the slow electron acoustic double layers (SEADLs). However, the enhanced population of the cold ions is found to play a supportive role for the low frequency DLs in bi-ion plasmas. The illustrations have been presented with the help of the bi-ion plasma parameters in the Earth's ionosphere F-region.

  4. Reactivity of Trapped and Accumulated Electrons in Titanium Dioxide Photocatalysis

    Directory of Open Access Journals (Sweden)

    Shigeru Kohtani

    2017-10-01

    Full Text Available Electrons, photogenerated in conduction bands (CB and trapped in electron trap defects (Tids in titanium dioxide (TiO2, play crucial roles in characteristic reductive reactions. This review summarizes the recent progress in the research on electron transfer in photo-excited TiO2. Particularly, the reactivity of electrons accumulated in CB and trapped at Tids on TiO2 is highlighted in the reduction of molecular oxygen and molecular nitrogen, and the hydrogenation and dehalogenation of organic substrates. Finally, the prospects for developing highly active TiO2 photocatalysts are discussed.

  5. Nonlinear ion-mixing-mode particle transport in the dissipative trapped electron regime

    International Nuclear Information System (INIS)

    Ware, A.S.; Terry, P.W.

    1993-09-01

    The nonlinear particle transport arising from the convection of nonadiabatic electron density by ion temperature gradient driven turbulence is examined for trapped electron collisionality regimes. The renormalized dissipative nonadiabatic trapped electron phase space density response is derived and used to calculate the nonlinear particle flux along with an ansatz for the turbulently broadened frequency spectrum. In the lower temperature end of this regime, trapped electrons are collisional and all components of the quasilinear particle flux are outward (i.e., in the direction of the gradients). Nonlinear effects can alter the phase between the nonadiabatic trapped electron phase space density and the electrostatic potential, producing inward components in the particle flux. Specifically, both turbulent shifting of the peak of the frequency spectrum and nonlinear source terms in the trapped electron response can give rise to inward components. However, in the dissipative regime these terms are small and the trapped electron response remains dominantly laminar. When the trapped electrons are collisionless, there is a temperature threshold above which the electron temperature gradient driven component of the quasilinear particle flux changes sign and becomes inward. For finite amplitude turbulence, however, turbulent broadening of both the electron collisional resonance and the frequency spectrum removes tills threshold., and the temperature gradient driven component remains outward

  6. Atomic physics measurements in an electron Beam Ion Trap

    International Nuclear Information System (INIS)

    Marrs, R.E.; Beiersdorfer, P.; Bennett, C.

    1989-01-01

    An electron Beam Ion Trap at Lawrence Livermore National Laboratory is being used to produce and trap very-highly-charged ions (q ≤ 70/+/) for x-ray spectroscopy measurements. Recent measurements of transition energies and electron excitation cross sections for x-ray line emission are summarized. 13 refs., 10 figs

  7. The Role of Electron Transport and Trapping in MOS Total-Dose Modeling

    International Nuclear Information System (INIS)

    Fleetwood, D.M.; Winokur, P.S.; Riewe, L.C.; Flament, O.; Paillet, P.; Leray, J.L.

    1999-01-01

    Radiation-induced hole and electron transport and trapping are fundamental to MOS total-dose models. Here we separate the effects of electron-hole annihilation and electron trapping on the neutralization of radiation-induced charge during switched-bias irradiation for hard and soft oxides, via combined thermally stimulated current (TSC) and capacitance-voltage measurements. We also show that present total-dose models cannot account for the thermal stability of deeply trapped electrons near the Si/SiO 2 interface, or the inability of electrons in deep or shallow traps to contribute to TSC at positive bias following (1) room-temperature, (2) high-temperature, or (3) switched-bias irradiation. These results require revisions of modeling parameters and boundary conditions for hole and electron transport in SiO 2 . The nature of deep and shallow electron traps in the near-interfacial SiO 2 is discussed

  8. Electrons in feldspar I: On the wavefunction of electrons trapped at simple lattice defects

    DEFF Research Database (Denmark)

    Poolton, H.R.J.; Wallinga, J.; Murray, A.S.

    2002-01-01

    The purpose of this article is to make an initial consideration of the physical properties of electrons trapped at classic hydrogenic lattice defects in feldspar. We are particularly interested to determine the radial extent of the electron wavefunctions in the ground and excited states. It is sh......The purpose of this article is to make an initial consideration of the physical properties of electrons trapped at classic hydrogenic lattice defects in feldspar. We are particularly interested to determine the radial extent of the electron wavefunctions in the ground and excited states...

  9. Spectroscopy of a Synthetic Trapped Ion Qubit

    Science.gov (United States)

    Hucul, David; Christensen, Justin E.; Hudson, Eric R.; Campbell, Wesley C.

    2017-09-01

    133Ba+ has been identified as an attractive ion for quantum information processing due to the unique combination of its spin-1 /2 nucleus and visible wavelength electronic transitions. Using a microgram source of radioactive material, we trap and laser cool the synthetic A =133 radioisotope of barium II in a radio-frequency ion trap. Using the same, single trapped atom, we measure the isotope shifts and hyperfine structure of the 62P1 /2↔62S1 /2 and 62P1 /2↔52D3 /2 electronic transitions that are needed for laser cooling, state preparation, and state detection of the clock-state hyperfine and optical qubits. We also report the 62P1 /2↔52D3 /2 electronic transition isotope shift for the rare A =130 and 132 barium nuclides, completing the spectroscopic characterization necessary for laser cooling all long-lived barium II isotopes.

  10. Spectral measurements of few-electron uranium ions produced and trapped in a high-energy electron beam ion trap

    International Nuclear Information System (INIS)

    Beiersdorfer, P.

    1994-01-01

    Measurements of 2s l/2 -2p 3/2 electric dipole and 2p 1/2 -2p 3/2 magnetic dipole and electric quadrupole transitions in U 82+ through U 89+ have been made with a high-resolution crystal spectrometer that recorded the line radiation from stationary ions produced and trapped in a high-energy electron beam ion trap. From the measurements we infer -39.21 ± 0.23 eV for the QED contribution to the 2s 1/2 -2p 3/2 transition energy of lithiumlike U 89+ . A comparison between our measurements and various computations illustrates the need for continued improvements in theoretical approaches for calculating the atomic structure of ions with two or more electrons in the L shell

  11. Sawtooth activity of the ion cloud in an electron-beam ion trap

    International Nuclear Information System (INIS)

    Radtke, R.; Biedermann, C.

    2003-01-01

    The dynamics of an ensemble of highly charged Ar and Ba ions in an electron-beam ion trap (EBIT) was studied by recording time-resolved x-ray spectra emitted from trapped ions. Sawtoothlike signatures manifest in the spectra for a variety of EBIT operating conditions indicating a sudden collapse of the ion inventory in the trap. The collapse occurs on a time scale of approximately 100 ms and the evolution of the sawteeth is very sensitive to parameters such as electron-beam current and axial trap depth. Analysis of the measurements is based on a time-dependent calculation of the trapping process showing that sawtooth activity is caused by the feedback between the low-Z argon and high-Z barium ions. This unexpected behavior demonstrates the importance of nonlinear effects in electron-beam traps containing more than a single ion species

  12. Electron trap annealing in neutron transmutation doped silicon

    DEFF Research Database (Denmark)

    Guldberg, J.

    1977-01-01

    Silicon doped by neutron transmutation to 1.2×1014 phosphorus atoms/cm3 was investigated with deep level transient spectroscopy using evaporated Au/n-Si diodes. Seven bulk electron traps were identified which appear after 30 min N2 anneal at temperatures between 425 and 725 °C. Five of these anne......Silicon doped by neutron transmutation to 1.2×1014 phosphorus atoms/cm3 was investigated with deep level transient spectroscopy using evaporated Au/n-Si diodes. Seven bulk electron traps were identified which appear after 30 min N2 anneal at temperatures between 425 and 725 °C. Five...

  13. Electron-trapping probability in natural dosemeters as a function of irradiation temperature

    DEFF Research Database (Denmark)

    Wallinga, J.; Murray, A.S.; Wintle, A.G.

    2002-01-01

    The electron-trapping probability in OSL traps as a function of irradiation temperature is investigated for sedimentary quartz and feldspar. A dependency was found for both minerals; this phenomenon could give rise to errors in dose estimation when the irradiation temperature used in laboratory...... procedures is different from that in the natural environment. No evidence was found for the existence of shallow trap saturation effects that Could give rise to a dose-rate dependency of electron trapping....

  14. Electron transfer from electronic excited states to sub-vacuum electron traps in amorphous ice

    International Nuclear Information System (INIS)

    Vichnevetski, E.; Bass, A.D.; Sanche, L.

    2000-01-01

    We investigate the electron stimulated yield of electronically excited argon atoms (Ar * ) from monolayer quantities of Ar deposited onto thin films of amorphous ice. Two peaks of narrow width ( - electron-exciton complex into exciton states, by the transfer of an electron into a sub-vacuum electron state within the ice film. However, the 10.7 eV feature is shifted to lower energy since electron attachment to Ar occurs within small pores of amorphous ice. In this case, the excess electron is transferred into an electron trap below the conduction band of the ice layer

  15. Origin and behavior of main electron traps in Si-implanted GaAs

    International Nuclear Information System (INIS)

    Fang, Z.Q.; Yamamoto, H.; Look, D.C.

    1990-01-01

    The electron traps in Si-implanted active layers (n ∼ 10 17 cm -3 ) have been studied by capacitance and conductance DLTS techniques in conjunction with different anneal conditions, which include rapid thermal anneals at different temperatures and furnace anneals with Si 3 N 4 cap or capless in an AsH 3 atmosphere. As compared to the electron traps in as-grown bulk n-GaAs (n ∼ 4 x 10 16 cm -3 ), nearly the same electron traps, i.e. EL2, EL3, EL4, EL5, EL6, and EL9 can be observed in the Si-implanted layers. Through a comparison with the annealing behavior of the main electron traps in bulk n-GaAs, the processing associated origins of some of the traps (EL2, EL3, EL4, EL5 and EL9) observed in Si-implanted GaAs layers have been determined. For some Si-implanted capped with Si 3 N 4 and furnace annealed, traps EL3 and EL4 dominate the trap EL2. In such layers it is found that emission due to EL3 is reduced while emission from EL12 is augmented by increasing the filling pulse width from 10 μs to 5 x 10 3 μs. In this paper phenomenon is explained in terms of a defect reaction enhanced by electron capture, showing a metastability or bistability

  16. Electron Fermi acceleration in collapsing magnetic traps: Computational and analytical models

    International Nuclear Information System (INIS)

    Gisler, G.; Lemons, D.

    1990-01-01

    The authors consider the heating and acceleration of electrons trapped on magnetic field lines between approaching magnetic mirrors. Such a collapsing magnetic trap and consequent electron energization can occur whenever a curved (or straight) flux tube drifts into a relatively straight (or curved) perpendicular shock. The relativistic, three-dimensional, collisionless test particle simulations show that an initial thermal electron distribution is bulk heated while a few individual electrons are accelerated to many times their original energy before they escape the trap. Upstream field-aligned beams and downstream pancake distributions perpendicular to the field are predicted. In the appropriate limit the simulation results agree well with a nonrelativistic analytic model of the distribution of escaping electrons which is based on the first adiabatic invariant and energy conservation between collisions with the mirrors. Space science and astrophysical applications are discussed

  17. Neutralizing trapped electrons on the hydrogenated surface of a diamond amplifier

    Directory of Open Access Journals (Sweden)

    Xiangyun Chang

    2012-01-01

    Full Text Available We discuss our investigation of electron trapping in a diamond amplifier (DA. Our previous work demonstrated that some electrons reaching the DA’s hydrogenated surface are not emitted. The state and the removal of these electrons is important for DA applications. We found that these stopped electrons are trapped, and cannot be removed by a strong reversed-polarity electric field; to neutralize this surface charge, holes must be sent to the hydrogenated surface to recombine with the trapped electrons through the Shockley-Read-Hall surface-recombination mechanism. We measured the time taken for such recombination on the hydrogenated surface, viz. the recombination time, as less than 5 ns, limited by the resolution of our test system. With this measurement, we demonstrated that DA could be operated in an rf cavity with frequency of a few hundred megahertz.

  18. ELECTRON TRAPPING IN WIGGLER AND QUADRUPOLE MAGNETS OF CESRTA

    International Nuclear Information System (INIS)

    Wang, Lanfa

    2010-01-01

    The Cornell Electron Storage Ring (CESR) has been reconfigured as an ultra low emittance damping ring for use as a test accelerator (CesrTA) for International Linear Collider (ILC) damping ring R and D (1). One of the primary goals of the CesrTA program is to investigate the interaction of the electron cloud with low emittance positron beam to explore methods to suppress the electron cloud, develop suitable advanced instrumentation required for these experimental studies and benchmark predictions by simulation codes. This paper reports the simulation of the electron-cloud formation in the wiggler and quadrupole magnets using the 3D code CLOUDLAND. We found that electrons can be trapped with long lifetime in a quadrupole magnet due to the mirror field trapping mechanism and photoelectrons produced in the wiggler zero field zone have long lifetime due to their complicated trajectory.

  19. Intrinsic electron traps in atomic-layer deposited HfO{sub 2} insulators

    Energy Technology Data Exchange (ETDEWEB)

    Cerbu, F.; Madia, O.; Afanas' ev, V. V.; Houssa, M.; Stesmans, A. [Laboratory of Semiconductor Physics, Department of Physics and Astronomy, University of Leuven, 3001 Leuven (Belgium); Andreev, D. V. [Laboratory of Semiconductor Physics, Department of Physics and Astronomy, University of Leuven, 3001 Leuven (Belgium); Bauman Moscow State Technical University—Kaluga Branch, 248000 Kaluga, Moscow obl. (Russian Federation); Fadida, S.; Eizenberg, M. [Department of Materials Science and Engineering, Technion-Israel Institute of Technology, 32000 Haifa (Israel); Breuil, L. [imec, 3001 Leuven (Belgium); Lisoni, J. G. [imec, 3001 Leuven (Belgium); Institute of Physics and Mathematics, Faculty of Science, Universidad Austral de Chile, Valdivia (Chile); Kittl, J. A. [Laboratory of Semiconductor Physics, Department of Physics and Astronomy, University of Leuven, 3001 Leuven (Belgium); Advanced Logic Lab, Samsung Semiconductor, Inc., Austin, 78754 Texas (United States); Strand, J.; Shluger, A. L. [Department of Physics and Astronomy, University College London, London WC1E 6BT (United Kingdom)

    2016-05-30

    Analysis of photodepopulation of electron traps in HfO{sub 2} films grown by atomic layer deposition is shown to provide the trap energy distribution across the entire oxide bandgap. The presence is revealed of two kinds of deep electron traps energetically distributed at around E{sub t} ≈ 2.0 eV and E{sub t} ≈ 3.0 eV below the oxide conduction band. Comparison of the trapped electron energy distributions in HfO{sub 2} layers prepared using different precursors or subjected to thermal treatment suggests that these centers are intrinsic in origin. However, the common assumption that these would implicate O vacancies cannot explain the charging behavior of HfO{sub 2}, suggesting that alternative defect models should be considered.

  20. Radiation of electrons in an electromagnetic axial trap

    International Nuclear Information System (INIS)

    Toropova, A.I.

    1998-01-01

    The version of a trap. wherein particles move in a homogeneous constant magnetic field and electrostatic field, formed by two equipotential planes and rotation axial surface, is proposed. The solution of canonic equations is found. It is shown that interaction of electrons with the radiation field leads to damping parametric resonance. The trap model, accounting for the finite conductivity of the resonator walls and losses by collisions with gas, is studied

  1. Role of trapped and solvated electrons in Ps formation

    International Nuclear Information System (INIS)

    Stepanov, S.V.; Byakov, V.M.; Mikhin, K.V.; He, C.; Hirade, T.

    2005-01-01

    Role of trapped and solvated electrons in Ps formation is discussed. Combination of thermalized positron with such electrons is possible from the view point of the energy balance and may results in Ps formation. This process proceeds during all e = lifetime matter. Fitting of raw experimental e + -e - annihilation spectra has to be based on an adequate physical input, which often leads to necessity of nonexponential deconvolution of the spectra. We have interpreted the Ps formation data in polyethylene, ethylene-methylmethacrylate and polymethylmethacrylate in dark and in light vs. tome of the measurement and temperature. parameters characterized accumulation of trapped electrons and their recombination with counter ions and positrons are obtained. (author)

  2. Self-generated zonal flows in the plasma turbulence driven by trapped-ion and trapped-electron instabilities

    Energy Technology Data Exchange (ETDEWEB)

    Drouot, T.; Gravier, E.; Reveille, T.; Collard, M. [Institut Jean Lamour, UMR 7198 CNRS - Université de Lorraine, 54 506 Vandoeuvre-lès-Nancy Cedex (France)

    2015-10-15

    This paper presents a study of zonal flows generated by trapped-electron mode and trapped-ion mode micro turbulence as a function of two plasma parameters—banana width and electron temperature. For this purpose, a gyrokinetic code considering only trapped particles is used. First, an analytical equation giving the predicted level of zonal flows is derived from the quasi-neutrality equation of our model, as a function of the density fluctuation levels and the banana widths. Then, the influence of the banana width on the number of zonal flows occurring in the system is studied using the gyrokinetic code. Finally, the impact of the temperature ratio T{sub e}/T{sub i} on the reduction of zonal flows is shown and a close link is highlighted between reduction and different gyro-and-bounce-average ion and electron density fluctuation levels. This reduction is found to be due to the amplitudes of gyro-and-bounce-average density perturbations n{sub e} and n{sub i} gradually becoming closer, which is in agreement with the analytical results given by the quasi-neutrality equation.

  3. Effect of Single-Electron Interface Trapping in Decanano MOSFETs: A 3D Atomistic Simulation Study

    Science.gov (United States)

    Asenov, Asen; Balasubramaniam, R.; Brown, A. R.; Davies, J. H.

    2000-01-01

    We study the effect of trapping/detrapping of a single-electron in interface states in the channel of n-type MOSFETs with decanano dimensions using 3D atomistic simulation techniques. In order to highlight the basic dependencies, the simulations are carried out initially assuming continuous doping charge, and discrete localized charge only for the trapped electron. The dependence of the random telegraph signal (RTS) amplitudes on the device dimensions and on the position of the trapped charge in the channel are studied in detail. Later, in full-scale, atomistic simulations assuming discrete charge for both randomly placed dopants and the trapped electron, we highlight the importance of current percolation and of traps with strategic position where the trapped electron blocks a dominant current path.

  4. Ultralow-Power Electronic Trapping of Nanoparticles with Sub-10 nm Gold Nanogap Electrodes.

    Science.gov (United States)

    Barik, Avijit; Chen, Xiaoshu; Oh, Sang-Hyun

    2016-10-12

    We demonstrate nanogap electrodes for rapid, parallel, and ultralow-power trapping of nanoparticles. Our device pushes the limit of dielectrophoresis by shrinking the separation between gold electrodes to sub-10 nm, thereby creating strong trapping forces at biases as low as the 100 mV ranges. Using high-throughput atomic layer lithography, we manufacture sub-10 nm gaps between 0.8 mm long gold electrodes and pattern them into individually addressable parallel electronic traps. Unlike pointlike junctions made by electron-beam lithography or larger micron-gap electrodes that are used for conventional dielectrophoresis, our sub-10 nm gold nanogap electrodes provide strong trapping forces over a mm-scale trapping zone. Importantly, our technology solves the key challenges associated with traditional dielectrophoresis experiments, such as high voltages that cause heat generation, bubble formation, and unwanted electrochemical reactions. The strongly enhanced fields around the nanogap induce particle-transport speed exceeding 10 μm/s and enable the trapping of 30 nm polystyrene nanoparticles using an ultralow bias of 200 mV. We also demonstrate rapid electronic trapping of quantum dots and nanodiamond particles on arrays of parallel traps. Our sub-10 nm gold nanogap electrodes can be combined with plasmonic sensors or nanophotonic circuitry, and their low-power electronic operation can potentially enable high-density integration on a chip as well as portable biosensing.

  5. Regulation of electron temperature gradient turbulence by zonal flows driven by trapped electron modes

    Science.gov (United States)

    Asahi, Y.; Ishizawa, A.; Watanabe, T.-H.; Tsutsui, H.; Tsuji-Iio, S.

    2014-05-01

    Turbulent transport caused by electron temperature gradient (ETG) modes was investigated by means of gyrokinetic simulations. It was found that the ETG turbulence can be regulated by meso-scale zonal flows driven by trapped electron modes (TEMs), which are excited with much smaller growth rates than those of ETG modes. The zonal flows of which radial wavelengths are in between the ion and the electron banana widths are not shielded by trapped ions nor electrons, and hence they are effectively driven by the TEMs. It was also shown that an E × B shearing rate of the TEM-driven zonal flows is larger than or comparable to the growth rates of long-wavelength ETG modes and TEMs, which make a main contribution to the turbulent transport before excitation of the zonal flows.

  6. Electron spin resonance from NV centers in diamonds levitating in an ion trap

    International Nuclear Information System (INIS)

    Delord, T; Nicolas, L; Schwab, L; Hétet, G

    2017-01-01

    We report observations of the electron spin resonance (ESR) of nitrogen vacancy centers in diamonds that are levitating in an ion trap. Using a needle Paul trap operating under ambient conditions, we demonstrate efficient microwave driving of the electronic spin and show that the spin properties of deposited diamond particles measured by the ESR are retained in the Paul trap. We also exploit the ESR signal to show angle stability of single trapped mono-crystals, a necessary step towards spin-controlled levitating macroscopic objects. (paper)

  7. Accurate measurements of visible M1 transitions of titanium-like ions using an electron beam ion trap

    International Nuclear Information System (INIS)

    Crosby, D.N.; Gaarde-Widdowson, K.; Silver, J.D.; Tarbutt, M.R.

    2001-01-01

    Magnetic dipole transitions between the fine structure levels (3d 4 ) 5 D 3 - 5 D 2 of titanium-like silver and tin have been observed as emission lines from the Oxford electron beam ion trap (EBIT). The precision of the measurement system is validated by observation and comparison of well known lines in Kr II and He I with the database values, justifying uncertainties of 4-12 ppm. (orig.)

  8. The energy distribution function of excess electrons trapped in the pulse irradiated low density polyethylene (LDPE)

    International Nuclear Information System (INIS)

    Wysocki, S.; Mazurek, L.; Karolczak, S.; Kroh, J.

    1995-01-01

    Distribution function D (E) of electrons trapped in irradiated LDPE was calculated on the basis of time resolved absorption spectra recorded at temperatures of 20-250 K. Variation of absorption spectra with time and temperature were observed and discussed in terms of simultaneous decay and relocation of electrons from shallow to deeper traps. Results obtained imply domination of trap limited transport for shallowly trapped electrons. For deeper traps, hopping mechanism is prevailing. (author)

  9. Time-dependence hole and electron trapping effects in SIMOX buried oxides

    International Nuclear Information System (INIS)

    Boesch, H.E. Jr.; Taylor, T.L.; Hite, L.R.; Bailey, W.E.

    1990-01-01

    Back-channel threshold shift associated with the buried oxide layers of separation by implanted oxygen (SIMOX) and zone-melted recrystallization (ZMR) field-effect transistors (FETs) was measured following pulsed irradiation as a function of temperature and back-gate bias using a fast time-resolved I-V measurement technique. The SIMOX FETs showed large initial negative voltage shifts at 0.2 ms after irradiation followed by temperature- and bias-dependent additional negative shifts to 800s. Analysis and modeling of the results indicate efficient deep trapping of radiation-generated holes in the bulk of the oxide, substantial initial trapping of radiation-generated electrons in the oxide, and rapid removal of the trapped electrons by a thermal detrapping process. The ZMR FETs showed evidence of substantial trapping of holes alone in the oxide bulk

  10. The role of electron-phonon interaction and non-Gaussian transport in spectral changes of trapped electrons in glasses

    International Nuclear Information System (INIS)

    Funabishi, K.; Hamill, W.H.

    The continuous-time-random-walk (CTRW) model which was developed for electron scavenging reactions in polar glasses is extended to the phenomenon of spectral relaxation of electrons in shallow traps esub(t) - in a wider range of systems. The central role of electron-phonon coupling in understanding the initial electron localization, the ''pre-existing trap'', and electron transfer processes are emphasized. The reactivity of esub(t) - with scavengers, including protons, is discussed in terms of the theory of multi-phonon non-radiative transitions. (author)

  11. First Test of a Radionuclide Trap at KNK II

    International Nuclear Information System (INIS)

    Stamm, H.-H.; Hanke, H.-D.; Clauss, H.

    1984-03-01

    The first test of an experimental radionuclide trap was performed at KNK II. The aim was to remove some Zn-65 and Mn-54 from the primary sodium. The 2.3 l trap was filled with stainless steel and nickel pallrings of different sizes and was operated for 100 hours at 312 ''0C and a flow rate of 1.6 m''3 Na/h. On the Ni samples 110 times the amount of Mn-54 and 440 times the amount of Zn-65 have been sorbed compared to stainless steel pallrings of the same size. The activity sorbed was proportional to the surface area

  12. The electron trap parameter extraction-based investigation of the relationship between charge trapping and activation energy in IGZO TFTs under positive bias temperature stress

    Science.gov (United States)

    Rhee, Jihyun; Choi, Sungju; Kang, Hara; Kim, Jae-Young; Ko, Daehyun; Ahn, Geumho; Jung, Haesun; Choi, Sung-Jin; Myong Kim, Dong; Kim, Dae Hwan

    2018-02-01

    Experimental extraction of the electron trap parameters which are associated with charge trapping into gate insulators under the positive bias temperature stress (PBTS) is proposed and demonstrated for the first time in amorphous indium-gallium-zinc-oxide thin-film transistors. This was done by combining the PBTS/recovery time-evolution of the experimentally decomposed threshold voltage shift (ΔVT) and the technology computer-aided design (TCAD)-based charge trapping simulation. The extracted parameters were the trap density (NOT) = 2.6 × 1018 cm-3, the trap energy level (ΔET) = 0.6 eV, and the capture cross section (σ0) = 3 × 10-19 cm2. Furthermore, based on the established TCAD framework, the relationship between the electron trap parameters and the activation energy (Ea) is comprehensively investigated. It is found that Ea increases with an increase in σ0, whereas Ea is independent of NOT. In addition, as ΔET increases, Ea decreases in the electron trapping-dominant regime (low ΔET) and increases again in the Poole-Frenkel (PF) emission/hopping-dominant regime (high ΔET). Moreover, our results suggest that the cross-over ΔET point originates from the complicated temperature-dependent competition between the capture rate and the emission rate. The PBTS bias dependence of the relationship between Ea and ΔET suggests that the electric field dependence of the PF emission-based electron hopping is stronger than that of the thermionic field emission-based electron trapping.

  13. Accurate measurements of visible M1 transitions of titanium-like ions using an electron beam ion trap

    Energy Technology Data Exchange (ETDEWEB)

    Crosby, D.N.; Gaarde-Widdowson, K.; Silver, J.D.; Tarbutt, M.R. [Oxford Univ. (United Kingdom). Dept. of Physics

    2001-07-01

    Magnetic dipole transitions between the fine structure levels (3d{sup 4}) {sup 5}D{sub 3}-{sup 5}D{sub 2} of titanium-like silver and tin have been observed as emission lines from the Oxford electron beam ion trap (EBIT). The precision of the measurement system is validated by observation and comparison of well known lines in Kr II and He I with the database values, justifying uncertainties of 4-12 ppm. (orig.)

  14. A small electron beam ion trap/source facility for electron/neutral–ion collisional spectroscopy in astrophysical plasmas

    Science.gov (United States)

    Liang, Gui-Yun; Wei, Hui-Gang; Yuan, Da-Wei; Wang, Fei-Lu; Peng, Ji-Min; Zhong, Jia-Yong; Zhu, Xiao-Long; Schmidt, Mike; Zschornack, Günter; Ma, Xin-Wen; Zhao, Gang

    2018-01-01

    Spectra are fundamental observation data used for astronomical research, but understanding them strongly depends on theoretical models with many fundamental parameters from theoretical calculations. Different models give different insights for understanding a specific object. Hence, laboratory benchmarks for these theoretical models become necessary. An electron beam ion trap is an ideal facility for spectroscopic benchmarks due to its similar conditions of electron density and temperature compared to astrophysical plasmas in stellar coronae, supernova remnants and so on. In this paper, we will describe the performance of a small electron beam ion trap/source facility installed at National Astronomical Observatories, Chinese Academy of Sciences.We present some preliminary experimental results on X-ray emission, ion production, the ionization process of trapped ions as well as the effects of charge exchange on the ionization.

  15. Electron cooling of highly charged ions in penning traps; Elektronenkuehlung hochgeladener Ionen in Penningfallen

    Energy Technology Data Exchange (ETDEWEB)

    Moellers, B.

    2007-02-08

    For many high precision experiments with highly charged ions in ion traps it is necessary to work with low energy ions. One possibility to slow ions down to a very low energy in a trap is electron cooling, a method, which is already successfully used in storage rings to produce ion beams with high phase space density. Fast ions and a cold electron plasma are inserted into a Penning trap. The ions lose their energy due to Coulomb interaction with the electrons while they cross the plasma, the electrons are heated. The cooling time is the time, which is needed to cool an ion from a given initial energy to a low final energy. To calculate cooling times it is necessary to solve coupled differential equations for the ion energy and electron temperature. In a Penning trap the strong external magnetic field constitutes a theoretical challenge, as it influences the energy loss of the ions in an electron plasma, which can no longer be calculated analytically. In former estimates of cooling times this influence is neglected. But simulations show a dramatic decrease of the energy loss in the presence of a strong magnetic field, so it is necessary to investigate the effect of the magnetic field on the cooling times. This work presents a model to calculate cooling times, which includes both the magnetic field and the trap geometry. In a first step a simplified model without the external trap potential is developed. The energy loss of the ions in the magnetized electron plasma is calculated by an analytic approximation, which requires a numerical solution of integrals. With this model the dependence of the cooling time on different parameters like electron and ion density, magnetic field and the angle between ion velocity and magnetic field is studied for fully ionized uranium. In addition the influence of the electron heating is discussed. Another important topic in this context is the recombination between ions and electrons. The simplified model for cooling times allows to

  16. Ultrafast carrier dynamics in tetrahedral amorphous carbon: carrier trapping versus electron-hole recombination

    International Nuclear Information System (INIS)

    Carpene, E; Mancini, E; Dallera, C; Schwen, D; Ronning, C; Silvestri, S De

    2007-01-01

    We report the investigation of the ultrafast carrier dynamics in thin tetrahedral amorphous carbon films by means of femtosecond time-resolved reflectivity. We estimated the electron-phonon relaxation time of a few hundred femtoseconds and we observed that under low optical excitation photo-generated carriers decay according to two distinct mechanisms attributed to trapping by defect states and direct electron-hole recombination. With high excitation, when photo-carrier and trap densities are comparable, a unique temporal evolution develops, as the time dependence of the trapping process becomes degenerate with the electron-hole recombination. This experimental evidence highlights the role of defects in the ultrafast electronic dynamics and is not specific to this particular form of carbon, but has general validity for amorphous and disordered semiconductors

  17. Electronic circuit provides automatic level control for liquid nitrogen traps

    Science.gov (United States)

    Turvy, R. R.

    1968-01-01

    Electronic circuit, based on the principle of increased thermistor resistance corresponding to decreases in temperature provides an automatic level control for liquid nitrogen cold traps. The electronically controlled apparatus is practically service-free, requiring only occasional reliability checks.

  18. Phase-Space Density Analyses of the AE-8 Trapped Electron and the AP-8 Trapped Proton Model Environments

    Energy Technology Data Exchange (ETDEWEB)

    T.E. Cayton

    2005-08-12

    The AE-8 trapped electron and the AP-8 trapped proton models are used to examine the L-shell variation of phase-space densities for sets of transverse (or 1st) invariants, {mu}, and geometrical invariants, K (related to the first two adiabatic invariants). The motivation for this study is twofold: first, to discover the functional dependence of the phase-space density upon the invariants; and, second, to explore the global structure of the radiation belts within this context. Variation due to particle rest mass is considered as well. The overall goal of this work is to provide a framework for analyzing energetic particle data collected by instruments on Global Positioning System (GPS) spacecraft that fly through the most intense region of the radiation belt. For all considered values of {mu} and K, and for 3.5 R{sub E} < L < 6.5 R{sub E}, the AE-8 electron phase-space density increases with increasing L; this trend--the expected one for a population diffusing inward from an external source--continues to L = 7.5 R{sub E} for both small and large values of K but reverses slightly for intermediate values of K. The AP-8 proton phase-space density exhibits {mu}-dependent local minima around L = 5 R{sub E}. Both AE-8 and AP-8 exhibit critical or cutoff values for the invariants beyond which the flux and therefore the phase-space density vanish. For both electrons and protons, these cutoff values vary systematically with magnetic moment and L-shell and are smaller than those estimated for the atmospheric loss cone. For large magnetic moments, for both electrons and protons, the K-dependence of the phase-space density is exponential, with maxima at the magnetic equator (K = 0) and vanishing beyond a cutoff value, K{sub c}. Such features suggest that momentum-dependent trapping boundaries, perhaps drift-type loss cones, serve as boundary conditions for trapped electrons as well as trapped protons.

  19. Phase-Space Density Analyses of the AE-8 Trapped Electron and the AP-8 Trapped Proton Model Environments

    International Nuclear Information System (INIS)

    Cayton, Thomas E.

    2005-01-01

    The AE-8 trapped electron and the AP-8 trapped proton models are used to examine the L-shell variation of phase-space densities for sets of transverse (or 1st) invariants, μ, and geometrical invariants, K (related to the first two adiabatic invariants). The motivation for this study is twofold: first, to discover the functional dependence of the phase-space density upon the invariants; and, second, to explore the global structure of the radiation belts within this context. Variation due to particle rest mass is considered as well. The overall goal of this work is to provide a framework for analyzing energetic particle data collected by instruments on Global Positioning System (GPS) spacecraft that fly through the most intense region of the radiation belt. For all considered values of μ and K, and for 3.5 R E E , the AE-8 electron phase-space density increases with increasing L; this trend--the expected one for a population diffusing inward from an external source--continues to L = 7.5 R E for both small and large values of K but reverses slightly for intermediate values of K. The AP-8 proton phase-space density exhibits μ-dependent local minima around L = 5 R E . Both AE-8 and AP-8 exhibit critical or cutoff values for the invariants beyond which the flux and therefore the phase-space density vanish. For both electrons and protons, these cutoff values vary systematically with magnetic moment and L-shell and are smaller than those estimated for the atmospheric loss cone. For large magnetic moments, for both electrons and protons, the K-dependence of the phase-space density is exponential, with maxima at the magnetic equator (K = 0) and vanishing beyond a cutoff value, K c . Such features suggest that momentum-dependent trapping boundaries, perhaps drift-type loss cones, serve as boundary conditions for trapped electrons as well as trapped protons

  20. Reduction of charge trapping and electron tunneling in SIMOX by supplemental implantation of oxygen

    International Nuclear Information System (INIS)

    Stahlbush, R.E.; Hughes, H.L.; Krull, W.A.

    1993-01-01

    Silicon-on-insulator, SOI, technologies are being aggressively pursued to produce high density, high speed, radiation tolerant electronics. The dielectric isolation of the buried oxide makes it possible to design integrated circuits that greatly minimize single event upset and eliminate dose-rate induced latchup and upset. The reduction of excess-silicon related defects in SIMOX by the supplemental implantation of oxygen has been examined. The supplemental implant is 6% of the oxygen dose used to form the buried oxide, and is followed by a 1,000 C anneal, in contrast to the >1,300 C anneal used to form the buried oxide layer of SIMOX. The defects examined include shallow electron traps, deep hole traps, and silicon clusters. The radiation-induced shallow electron and deep hole trapping are measured by cryogenic detrapping and isothermal annealing techniques. The low-field (3 to 6 MV/cm) electron tunneling is interpreted as due to a two phase mixture of stoichiometric SiO 2 and Si clusters a few nm in size. Single and triple SIMOS samples have been examined. All of the defects are reduced by the supplemental oxygen processing. Shallow electron trapping is reduced by an order of magnitude. Because of the larger capture cross section for hole trapping, hole trapping is not reduced as much. The low-field electron tunneling due to Si clusters is also significantly reduced. Both uniform and nonuniform electron tunneling have been observed in SIMOX samples without supplement processing. In samples exhibiting only uniform tunneling, electron capture at holes has been observed. The nonuniform tunneling is superimposed upon the uniform tunneling and is characterized by current spiking

  1. Photoconductivity and bleaching of trapped electrons at 770C in irradiated methylcyclohexane

    International Nuclear Information System (INIS)

    Dolivo, G.; Gaeumann, T.

    1977-01-01

    The influence of the wavelength and intensity of the bleaching radiation on the thermoluminescence, thermoconductivity, optical absorption and photoconductivity of the methylcyclohexane, protonated and deuterated, was studied. The energy level scheme of the trapped electron in this alkane is very similar to that found in MTHF and 3-MP. The rate of bleaching of the trapped electrons is less in the deuterated product. (U.K.)

  2. Asymptotic theory of dissipative trapped electron mode overlapping many rational surfaces

    International Nuclear Information System (INIS)

    Rogister, A.; Hasselberg, G.

    1978-01-01

    The two dimensional eigenvalue equation describing the dissipative trapped electron mode is solved exactly in the limit of the mode overlapping many rational surfaces using the Pogutse model for the magnetic field and the pitch angle collision operator. The trapped electron contribution to the growth rate decreases, with respect to the standard theory, by a factor of order Δ/chi sub(T) << 1 where chi sub(T) is the position of the turning point and Δ the distance between rational surfaces

  3. Dependence of the confinement time of an electron plasma on the magnetic field in a quadrupole Penning trap

    Energy Technology Data Exchange (ETDEWEB)

    Dyavappa, B.M.; Datar, Durgesh; Prakash; Ananthamurthy, Sharath [Bangalore University, Department of Physics, Bangalore (India)

    2017-12-15

    A quadrupole Penning trap is used to confine electrons in weak magnetic fields. Perturbations due to space charge and imperfections in the trap geometry, as well as collisions with the background gas molecules, lead to loss of the electrons from the trap. We present in this work the results on measurements of the electron confinement time and its dependence on the magnetic field in a quadrupolar Penning trap. We describe a method to measure the confinement time of an electron cloud under weak magnetic fields (0.01 T - 0.1 T). This time is found to scale as τ ∝ B{sup 1.41} in variance with the theoretically expected confinement time that scales as τ ∝ B{sup 2} for trapped electrons that are lost through collisions with the neutrals present in the trap. A measurement of the expansion rate of the electron plasma in the trap through controlled variation of the trap voltage, yields expansion times that depend on the energy of escaping electrons. This is found to vary in our case in the scaling range B{sup 0.32} to B{sup 0.43}. Distorting the geometry of the trap, results in a marked change in the confinement time's dependence on the magnetic field. The results indicate that the confinement time of the electron cloud in the trap is limited by both, effects of collisions and perturbations that result in the plasma loss through expansion in the trap. (orig.)

  4. Tuning the Electronic and Dynamical Properties of a Molecule by Atom Trapping Chemistry.

    Science.gov (United States)

    Pham, Van Dong; Repain, Vincent; Chacon, Cyril; Bellec, Amandine; Girard, Yann; Rousset, Sylvie; Abad, Enrique; Dappe, Yannick J; Smogunov, Alexander; Lagoute, Jérôme

    2017-11-28

    The ability to trap adatoms with an organic molecule on a surface has been used to obtain a range of molecular functionalities controlled by the choice of the molecular trapping site and local deprotonation. The tetraphenylporphyrin molecule used in this study contains three types of trapping sites: two carbon rings (phenyl and pyrrole) and the center of a macrocycle. Catching a gold adatom on the carbon rings leads to an electronic doping of the molecule, whereas trapping the adatom at the macrocycle center with single deprotonation leads to a molecular rotor and a second deprotonation leads to a molecular jumper. We call "atom trapping chemistry" the control of the structure, electronic, and dynamical properties of a molecule achieved by trapping metallic atoms with a molecule on a surface. In addition to the examples previously described, we show that more complex structures can be envisaged.

  5. First results on dense plasma confinement at the multimirror open trap GOL-3-II

    International Nuclear Information System (INIS)

    Koidan, V.S.; Arzhannikov, A.V.; Astrelin, V.T.

    2001-01-01

    First results of experiments on plasma confinement in multimirror open trap GOL-3-II are presented. This facility is an open trap with total length of 17 m intended for confinement of a relatively dense (10 15 -10 17 cm -3 ) plasma in axially-symmetrical magnetic system. The plasma heating is provided by a high-power electron beam (1 MeV, 30 kA, 8 ms, 200 kJ). New phase of the experiments is aimed to confinement of high-β thermalized plasma. Two essential modifications of the facility have been done. First, plasma column was separated by vacuum sections from the beam accelerator and exit beam receiver. Second, the magnetic field on part of the solenoid was reconfigured into multimirror system with H max /H min ∼1.5 and 22 cm cell length. Results of the experiments at modified configuration of the device indicate that the confinement time of the plasma with n e ∼(0, 5/5)·10 15 cm -3 and T e ∼1 keV increases more than order of magnitude. (author)

  6. Dielectronic recombination measurements using the Electron Beam Ion Trap

    International Nuclear Information System (INIS)

    Knapp, D.A.

    1991-01-01

    We have used the Electron Beam Ion Trap at LLNL to study dielectronic recombination in highly charged ions. Our technique is unique because we observe the x-rays from dielectronic recombination at the same time we see x-rays from all other electron-ion interactions. We have recently taken high-resolution, state-selective data that resolves individual resonances

  7. Proposed LLNL electron beam ion trap

    International Nuclear Information System (INIS)

    Marrs, R.E.; Egan, P.O.; Proctor, I.; Levine, M.A.; Hansen, L.; Kajiyama, Y.; Wolgast, R.

    1985-01-01

    The interaction of energetic electrons with highly charged ions is of great importance to several research fields such as astrophysics, laser fusion and magnetic fusion. In spite of this importance there are almost no measurements of electron interaction cross sections for ions more than a few times ionized. To address this problem an electron beam ion trap (EBIT) is being developed at LLNL. The device is essentially an EBIS except that it is not intended as a source of extracted ions. Instead the (variable energy) electron beam interacting with the confined ions will be used to obtain measurements of ionization cross sections, dielectronic recombination cross sections, radiative recombination cross sections, energy levels and oscillator strengths. Charge-exchange recombinaion cross sections with neutral gasses could also be measured. The goal is to produce and study elements in many different charge states up to He-like xenon and Ne-like uranium. 5 refs., 2 figs

  8. Identification of electron and hole traps in KH2PO4 crystals

    International Nuclear Information System (INIS)

    Garces, N. Y.; Stevens, K. T.; Halliburton, L. E.; Demos, S. G.; Radousky, H. B.; Zaitseva, N. P.

    2001-01-01

    Electron paramagnetic resonance (EPR) has been used to characterize a hole trap and several electron traps in single crystals of potassium dihydrogen phosphate (KH 2 PO 4 or KDP). The paramagnetic charge states of these centers are produced by ionizing radiation (e.g., x rays or a 266 nm beam from a pulsed Nd:YAG laser) and are stable for days and even weeks at room temperature. One center consists of a hole trapped on an oxygen ion adjacent to a silicon impurity located on a phosphorus site. This defect has a small, but easily observed, hyperfine interaction with the adjacent substitutional proton. The other centers are formed when an electron is trapped at an oxygen vacancy. These latter defects are best described as (PO 3 ) 2- molecular ions, where the primary phosphorus nucleus is responsible for a large hyperfine splitting (500--800 G in magnitude). Five EPR spectra representing variations of these oxygen vacancy centers are observed, with the differences being attributed to the relative position of a nearby cation vacancy, either a missing proton or potassium. An angular study of the EPR spectra, conducted at room temperature, provided principal values and principal directions for the g matrices and hyperfine matrices for the hole center and two of the electron centers

  9. The Role of Electron Transport and Trapping in MOS Total-Dose Modeling

    International Nuclear Information System (INIS)

    Flament, O.; Fleetwood, D.M.; Leray, J.L.; Paillet, P.; Riewe, L.C.; Winokur, P.S.

    1999-01-01

    Deep and shallow electron traps form in irradiated thermal SiO 2 as a natural response to hole transport and trapping. The density and stability of these defects are discussed, as are their implications for total-dose modeling

  10. A way for evaluating parameters of electron transport in non-polar molecular liquids derived from analysis of the trapped electron recombination kinetics

    International Nuclear Information System (INIS)

    Lukin, L.V.

    2012-01-01

    The geminate recombination kinetics of electron-ion pairs produced by high energy radiation in liquid hydrocarbons is considered in the two state model of electron transport. The purpose of the study is to relate the trapped electron transient optical absorption, observed in the pulse radiolysis experiments, to fundamental parameters of electron transport in liquid. It is shown that measurements of the half-life time and amplitude of the trapped electron decay curve allow one to find the electron life time in a localized state. - Highlights: ► A two state electron model is applied to geminate charge recombination. ► Time dependence of trapped electrons is computed for liquid isooctane and squalane. ► Electron decay kinetics depends on electron life time in a localized state. ► Key parameters of electron transport are found from the pulse radiolysis studies.

  11. Atomic physics of highly charged ions in an electron beam ion trap

    International Nuclear Information System (INIS)

    Marrs, R.E.

    1990-07-01

    Two electron beam ion traps are in use at LLNL for the purpose of studying the properties of very highly charged ions and their interactions with electrons. This paper reviews the operation of the traps and discusses recent experiments in three areas: precision transition energy measurements in the limit of very high ion charge, dielectronic recombination measurements for the He-like isoelectronic sequence, and measurements of x-ray polarization. 22 refs., 11 figs., 1 tab

  12. A multidimensional theory for electron trapping by a plasma wake generated in the bubble regime

    International Nuclear Information System (INIS)

    Kostyukov, I; Nerush, E; Pukhov, A; Seredov, V

    2010-01-01

    We present a theory for electron self-injection in nonlinear, multidimensional plasma waves excited by a short laser pulse in the bubble regime or by a short electron beam in the blowout regime. In these regimes, which are typical for electron acceleration in the last impressive experiments, the laser radiation pressure or the electron beam charge pushes out plasma electrons from some region, forming a plasma cavity or a bubble with a huge ion charge. The plasma electrons can be trapped in the bubble and accelerated by the plasma wakefields up to a very high energy. We derive the condition of the electron trapping in the bubble. The developed theory predicts the trapping cross section in terms of the bubble radius and the bubble velocity. It is found that the dynamic bubble deformations observed in the three-dimensional (3D) particle-in-cell (PIC) simulations influence the trapping process significantly. The bubble elongation reduces the gamma-factor of the bubble, thereby strongly enhancing self-injection. The obtained analytical results are in good agreement with the 3D PIC simulations.

  13. X-ray spectroscopy of highly-ionized atoms in an electron beam ion trap (EBIT)

    International Nuclear Information System (INIS)

    Marrs, R.E.; Bennett, C.; Chen, M.H.

    1988-01-01

    An Electron Beam Ion Trap at Lawrence Livermore National Laboratory is being used to produce and trap very-highly-charged-ions (q /le/ 70+) for x-ray spectroscopy measurements. Recent measurements of dielectronic recombination, electron impact excitation and transition energies are presented. 15 refs., 12 figs., 1 tab

  14. Direct probing of electron and hole trapping into nano-floating-gate in organic field-effect transistor nonvolatile memories

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Ze-Qun; Wang, Shun; Chen, Jian-Mei; Gao, Xu; Dong, Bin, E-mail: wangsd@suda.edu.cn, E-mail: chilf@suda.edu.cn, E-mail: bdong@suda.edu.cn; Chi, Li-Feng, E-mail: wangsd@suda.edu.cn, E-mail: chilf@suda.edu.cn, E-mail: bdong@suda.edu.cn; Wang, Sui-Dong, E-mail: wangsd@suda.edu.cn, E-mail: chilf@suda.edu.cn, E-mail: bdong@suda.edu.cn [Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Institute of Functional Nano and Soft Materials (FUNSOM), Soochow University, Suzhou, Jiangsu 215123 (China)

    2015-03-23

    Electron and hole trapping into the nano-floating-gate of a pentacene-based organic field-effect transistor nonvolatile memory is directly probed by Kelvin probe force microscopy. The probing is straightforward and non-destructive. The measured surface potential change can quantitatively profile the charge trapping, and the surface characterization results are in good accord with the corresponding device behavior. Both electrons and holes can be trapped into the nano-floating-gate, with a preference of electron trapping than hole trapping. The trapped charge quantity has an approximately linear relation with the programming/erasing gate bias, indicating that the charge trapping in the device is a field-controlled process.

  15. Direct probing of electron and hole trapping into nano-floating-gate in organic field-effect transistor nonvolatile memories

    International Nuclear Information System (INIS)

    Cui, Ze-Qun; Wang, Shun; Chen, Jian-Mei; Gao, Xu; Dong, Bin; Chi, Li-Feng; Wang, Sui-Dong

    2015-01-01

    Electron and hole trapping into the nano-floating-gate of a pentacene-based organic field-effect transistor nonvolatile memory is directly probed by Kelvin probe force microscopy. The probing is straightforward and non-destructive. The measured surface potential change can quantitatively profile the charge trapping, and the surface characterization results are in good accord with the corresponding device behavior. Both electrons and holes can be trapped into the nano-floating-gate, with a preference of electron trapping than hole trapping. The trapped charge quantity has an approximately linear relation with the programming/erasing gate bias, indicating that the charge trapping in the device is a field-controlled process

  16. Deep electron traps in HfO_2-based metal-oxide-semiconductor capacitors

    International Nuclear Information System (INIS)

    Salomone, L. Sambuco; Lipovetzky, J.; Carbonetto, S.H.; García Inza, M.A.; Redin, E.G.; Campabadal, F.

    2016-01-01

    Hafnium oxide (HfO_2) is currently considered to be a good candidate to take part as a component in charge-trapping nonvolatile memories. In this work, the electric field and time dependences of the electron trapping/detrapping processes are studied through a constant capacitance voltage transient technique on metal-oxide-semiconductor capacitors with atomic layer deposited HfO_2 as insulating layer. A tunneling-based model is proposed to reproduce the experimental results, obtaining fair agreement between experiments and simulations. From the fitting procedure, a band of defects is identified, located in the first 1.7 nm from the Si/HfO_2 interface at an energy level E_t = 1.59 eV below the HfO_2 conduction band edge with density N_t = 1.36 × 10"1"9 cm"−"3. A simplified analytical version of the model is proposed in order to ease the fitting procedure for the low applied voltage case considered in this work. - Highlights: • We characterized deep electron trapping/detrapping in HfO_2 structures. • We modeled the experimental results through a tunneling-based model. • We obtained an electron trap energy level of 1.59 eV below conduction band edge. • We obtained a spatial trap distribution extending 1.7 nm within the insulator. • A simplified tunneling front model is able to reproduce the experimental results.

  17. A study of the profile of the E3 electron trap in GaAs

    Energy Technology Data Exchange (ETDEWEB)

    Kourkoutas, C.D. (TEI Athens (Greece). Dept. of Physics Chemistry and Material Technology); Kovacs, B.; Szentpali, B.; Somogyi, K. (Research Inst. for Technical Physics, Budapest (Hungary)); Euthymiou, P.C. (Athens Univ. (Greece)); Giakoumakis, G.E. (Ioannina Univ. (Greece). Dept. of Physics)

    1994-01-01

    Electron irradiation at room temperature introduces in GaAs a donor type electronic state Tx at 0.18 eV, which is associated with the E3 electron trap. The presence of Tx is observed at depths d > 1.5 [mu]m, which correspond to the limits of the depletion region under the highest applied reverse bias voltage, while the E3 trap concentration drops off into the same region. (author).

  18. A study of the profile of the E3 electron trap in GaAs

    International Nuclear Information System (INIS)

    Kourkoutas, C.D.; Euthymiou, P.C.; Giakoumakis, G.E.

    1994-01-01

    Electron irradiation at room temperature introduces in GaAs a donor type electronic state Tx at 0.18 eV, which is associated with the E3 electron trap. The presence of Tx is observed at depths d > 1.5 μm, which correspond to the limits of the depletion region under the highest applied reverse bias voltage, while the E3 trap concentration drops off into the same region. (author)

  19. Ion production and trapping in electron rings

    International Nuclear Information System (INIS)

    Gluckstern, R.C.; Ruggiero, A.G.

    1979-08-01

    The electron beam in the VUV and X-ray rings of NSLS will ionize residual gas by collisions. Positive ions will be produced with low velocity, and will be attracted by the electron beam to the beam axis. If they are trapped in stable (transverse) orbits, they may accumulate, thereby increasing the ν/sub x,z/ of the individual electrons. Since the accumulated ions are unlikely to be of uniform density, a spread in ν/sub x,z/ will also occur. Should these effects be serious, it may be necessary to introduce clearing electrodes, although this may increase Z/n in the rings, thereby adding to longitudinal instability problems. The seriousness of the above effect for the VUV and X-ray rings is estimated

  20. Electronic properties of hafnium oxide: A contribution from defects and traps

    Energy Technology Data Exchange (ETDEWEB)

    Gritsenko, Vladimir A., E-mail: grits@isp.nsc.ru; Perevalov, Timofey V.; Islamov, Damir R., E-mail: damir@isp.nsc.ru

    2016-02-15

    In the present article, we give a review of modern data and latest achievements pertaining to the study of electronic properties of oxygen vacancies in hafnium oxide. Hafnium oxide is a key dielectric for use in many advanced silicon devices. Oxygen vacancies in hafnium oxide largely determine the electronic properties of the material. We show that the electronic transitions between the states due to oxygen vacancies largely determine the optical absorption and luminescent properties of hafnium oxide. We discuss the role of oxygen vacancies as traps that facilitate charge transport in hafnium oxide films. Also, we demonstrate the fact that the electrical conductivity in hafnium oxide is controlled by the phonon-assisted tunnelling of charge carriers between traps that were identified as oxygen vacancies.

  1. Hydride vapor phase GaN films with reduced density of residual electrons and deep traps

    International Nuclear Information System (INIS)

    Polyakov, A. Y.; Smirnov, N. B.; Govorkov, A. V.; Yugova, T. G.; Cox, H.; Helava, H.; Makarov, Yu.; Usikov, A. S.

    2014-01-01

    Electrical properties and deep electron and hole traps spectra are compared for undoped n-GaN films grown by hydride vapor phase epitaxy (HVPE) in the regular process (standard HVPE samples) and in HVPE process optimized for decreasing the concentration of residual donor impurities (improved HVPE samples). It is shown that the residual donor density can be reduced by optimization from ∼10 17  cm −3 to (2–5) × 10 14  cm −3 . The density of deep hole traps and deep electron traps decreases with decreased donor density, so that the concentration of deep hole traps in the improved samples is reduced to ∼5 × 10 13  cm −3 versus 2.9 × 10 16  cm −3 in the standard samples, with a similar decrease in the electron traps concentration

  2. Electron, hole and exciton self-trapping in germanium doped silica glass from DFT calculations with self-interaction correction

    International Nuclear Information System (INIS)

    Du Jincheng; Rene Corrales, L.; Tsemekhman, Kiril; Bylaska, Eric J.

    2007-01-01

    Density functional theory (DFT) calculations were employed to understand the refractive index change in germanium doped silica glasses for the trapped states of electronic excitations induced by UV irradiation. Local structure relaxation and excess electron density distribution were calculated upon self-trapping of an excess electron, hole, and exciton in germanium doped silica glass. The results show that both the trapped exciton and excess electron are highly localized on germanium ion and, to some extent, on its oxygen neighbors. Exciton self-trapping is found to lead to the formation of a Ge E' center and a non-bridging hole center. Electron trapping changes the GeO 4 tetrahedron structure into trigonal bi-pyramid with the majority of the excess electron density located along the equatorial line. The self-trapped hole is localized on bridging oxygen ions that are not coordinated to germanium atoms that lead to elongation of the Si-O bonds and change of the Si-O-Si bond angles. We carried out a comparative study of standard DFT versus DFT with a hybrid PBE0 exchange and correlation functional. The results show that the two methods give qualitatively similar relaxed structure and charge distribution for electron and exciton trapping in germanium doped silica glass; however, only the PBE0 functional produces the self-trapped hole

  3. Trapped electrons as a free energy source for the auroral kilometric radiation

    International Nuclear Information System (INIS)

    Louarn, P.; Roux, A.; de Feraudy, H.; Le Queau, D.; Andre, M.; Matson, L.

    1990-01-01

    Simultaneous measurements of electromagnetic fields and particle distributions, measured during the crossing by the Swedish spacecraft Viking of an auroral kilometric radiation (AKR) source, are presented. It is shown that AKR is generated within an acceleration region characterized by an upward directed parallel electric field, as evidenced by its signature on the proton and electron distributions. From particle observations inside the AKR source it is clear that the potential drop below the spacecraft produces upward moving field-aligned ion beams and a depletion in the density of low energy electrons. The potential drop above the spacecraft produces downward accelerated electrons. A large fraction of these electrons have small parallel velocities; they mirror above the ionosphere. These trapped electrons lie in a region of velocity space which should be empty in a simple adiabatic theory. The authors suggest that these electrons get trapped when they experience a time-varying (or space-varying) parallel electric field. This conclusion is supported by the comparison between the observed electron distribution function and a model distribution function built by applying Liouville theorem. Since trapped electrons can cause positive gradients (∂f e /∂V perpendicular > 0) over a broad range of parallel velocities, around v parallel ∼ 0, it is suggested that they are the free energy source for the AKR. This conclusion is substantiated by an evaluation of the convective growth rate, where the various input parameters have been determined by fitting particle data

  4. Fast Transverse Beam Instability Caused by Electron Cloud Trapped in Combined Function Magnets

    Energy Technology Data Exchange (ETDEWEB)

    Antipov, Sergey [Univ. of Chicago, IL (United States)

    2017-03-01

    Electron cloud instabilities affect the performance of many circular high-intensity particle accelerators. They usually have a fast growth rate and might lead to an increase of the transverse emittance and beam loss. A peculiar example of such an instability is observed in the Fermilab Recycler proton storage ring. Although this instability might pose a challenge for future intensity upgrades, its nature had not been completely understood. The phenomena has been studied experimentally by comparing the dynamics of stable and unstable beam, numerically by simulating the build-up of the electron cloud and its interaction with the beam, and analytically by constructing a model of an electron cloud driven instability with the electrons trapped in combined function dipoles. Stabilization of the beam by a clearing bunch reveals that the instability is caused by the electron cloud, trapped in beam optics magnets. Measurements of microwave propagation confirm the presence of the cloud in the combined function dipoles. Numerical simulations show that up to 10$^{-2}$ of the particles can be trapped by their magnetic field. Since the process of electron cloud build-up is exponential, once trapped this amount of electrons significantly increases the density of the cloud on the next revolution. In a combined function dipole this multi-turn accumulation allows the electron cloud reaching final intensities orders of magnitude greater than in a pure dipole. The estimated fast instability growth rate of about 30 revolutions and low mode frequency of 0.4 MHz are consistent with experimental observations and agree with the simulations. The created instability model allows investigating the beam stability for the future intensity upgrades.

  5. High-resolution compact Johann crystal spectrometer with the Livermore electron beam ion trap

    International Nuclear Information System (INIS)

    Robbins, D.L.; Chen, H.; Beiersdorfer, P.; Faenov, A.Ya.; Pikuz, T.A.; May, M.J.; Dunn, J.; Smith, A.J.

    2004-01-01

    A compact high-resolution (λ/Δλ≅10 000) spherically bent crystal spectrometer in the Johann geometry was recently installed and tested on the Lawrence Livermore National Laboratory SuperEBIT electron beam ion trap. The curvature of the mica (002) crystal grating allows for higher collection efficiency compared to the flat and cylindrically bent crystal spectrometers commonly used on the Livermore electron beam ion traps. The spectrometer's Johann configuration enables orientation of its dispersion plane to be parallel to the electron beam propagation. Used in concert with a crystal spectrometer, whose dispersion plane is perpendicular to the electron beam propagation, the polarization of x-ray emission lines can be measured

  6. 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

  7. Evaluating Origin of Electron Traps in Tris(8-hydroxyquinoline) Aluminum Thin Films using Thermally Stimulated Current Technique

    OpenAIRE

    Matsushima, Toshinori; Adachi, Chihaya

    2008-01-01

    We measured the energy distributions and concentrations of electron traps in O_2-unexposed and O_2-exposed tris(8-hydroxyquinoline) aluminum (Alq_3) films using a thermally stimulated current (TSC) technique to investigate how doping O_2 molecules in Alq_3 films affect the films' electron trap and electron transport characteristics. The results of our TSC studies revealed that Alq_3 films have an electron trap distribution with peak depths ranging from 0.075 to 0.1 eV and peak widths ranging ...

  8. 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

  9. Trapped Electron Instability of Electron Plasma Waves: Vlasov simulations and theory

    Science.gov (United States)

    Berger, Richard; Chapman, Thomas; Brunner, Stephan

    2013-10-01

    The growth of sidebands of a large-amplitude electron plasma wave is studied with Vlasov simulations for a range of amplitudes (. 001 vph = +/-ωbe , where vph =ω0 /k0 and ωbe is the bounce frequency of a deeply trapped electron. In 2D simulations, we find that the instability persists and co-exists with the filamentation instability. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and funded by the Laboratory Research and Development Program at LLNL under project tracking code 12-ERD.

  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. Natural variations in the geomagnetically trapped electron population

    Science.gov (United States)

    Vampola, A. L.

    1972-01-01

    Temporal variations in the trapped natural electron flux intensities and energy spectra are discussed and demonstrated using recent satellite data. These data are intended to acquaint the space systems engineer with the types of natural variations that may be encountered during a mission and to augment the models of the electron environment currently being used in space system design and orbit selection. An understanding of the temporal variations which may be encountered should prove helpful. Some of the variations demonstrated here which are not widely known include: (1) addition of very energetic electrons to the outer zone during moderate magnetic storms: (2) addition of energetic electrons to the inner zone during major magnetic storms; (3) inversions in the outer zone electron energy spectrum during the decay phase of a storm injection event and (4) occasional formation of multiple maxima in the flux vs altitude profile of moderately energetic electrons.

  12. Spectroscopy of highly charged tungsten ions with Electron Beam Ion Traps

    International Nuclear Information System (INIS)

    Sakaue, Hiroyuki A.; Kato, Daiji; Morita, Shigeru; Murakami, Izumi; Yamamoto, Norimasa; Ohashi, Hayato; Yatsurugi, Junji; Nakamura, Nobuyuki

    2013-01-01

    We present spectra of highly charged tungsten ions in the extreme ultra-violet (EUV) by using electron beam ion traps. The electron energy dependence of spectra is investigated of electron energies from 490 to 1440 eV. Previously unreported lines are presented in the EUV range, and some of them are identified by comparing the wavelengths with theoretical calculations. (author)

  13. Nonlinear trapped electron mode and anomalous heat transport in tokamaks

    International Nuclear Information System (INIS)

    Kaw, P.K.

    1982-01-01

    We take the phenomenological point of view that the anomalous electron thermal conductivity produced by the non-linear trapped electron mode should also influence the stability properties of the mode itself. Using a model equation, we show that this effect makes the mode self-stabilizing. A simple expression for the anomalous thermal conductivity is derived, and its scaling properties are discussed. (orig.)

  14. Charged particle traps II applications

    CERN Document Server

    Werth, Günther; Major, Fouad G

    2009-01-01

    This, the second volume of Charged Particle Traps, is devoted to applications, complementing the first volume’s comprehensive treatment of the theory and practice of charged particle traps, their many variants and refinements. In recent years, applications of far reaching importance have emerged ranging from the ultra-precise mass determinations of elementary particles and their antiparticles and short-lived isotopes, to high-resolution Zeeman spectroscopy on multiply-charged ions, to microwave and optical spectroscopy, some involving "forbidden" transitions from metastable states of such high resolution that optical frequency standards are realized by locking lasers to them. Further the potential application of trapped ions to quantum computing is explored, based on the extraordinary quantum state coherence made possible by the particle isolation. Consideration is given to the Paul and Penning traps as potential quantum information processors.

  15. Effect of fast electrons on the stability of resistive interchange modes in the TJ-II stellarator

    Energy Technology Data Exchange (ETDEWEB)

    García, L. [Universidad Carlos III de Madrid, Avda. de la Universidad 30, 28911 Leganés, Madrid (Spain); Ochando, M. A.; Hidalgo, C.; Milligen, B. Ph. van [CIEMAT - Laboratorio Nacional de Fusión, Avda. Complutense 40, 28040 Madrid (Spain); Carreras, B. A. [BACV Solutions, 110 Mohawk Road, Oak Ridge, Tennessee 37830 (United States); Carralero, D. [Max-Planck-Institute for Plasma Physics, Boltzmannstr. 2, Garching (Germany)

    2016-06-15

    In this paper, we report on electromagnetic phenomena in low-β plasmas at the TJ-II stellarator, controlled by external heating. To understand the observations qualitatively, we introduce a simple modification of the standard resistive MHD equations, to include the potential impact of fast electrons on instabilities. The dominant instabilities of the modeling regime are resistive interchange modes, and calculations are performed in a configuration with similar characteristics as the TJ-II stellarator. The main effect of the trapping of fast electrons by magnetic islands induced by MHD instabilities is to increase the magnetic component of the fluctuations, changing the character of the instability to tearing-like and modifying the frequency of the modes. These effects seem to be consistent with some of the experimental observations.

  16. Electron self-injection and trapping into an evolving plasma bubble.

    Science.gov (United States)

    Kalmykov, S; Yi, S A; Khudik, V; Shvets, G

    2009-09-25

    The blowout (or bubble) regime of laser wakefield acceleration is promising for generating monochromatic high-energy electron beams out of low-density plasmas. It is shown analytically and by particle-in-cell simulations that self-injection of the background plasma electrons into the quasistatic plasma bubble can be caused by slow temporal expansion of the bubble. Sufficient criteria for the electron trapping and bubble's expansion rate are derived using a semianalytic nonstationary Hamiltonian theory. It is further shown that the combination of bubble's expansion and contraction results in monoenergetic electron beams.

  17. A high-energy electron beam ion trap for production of high-charge high-Z ions

    International Nuclear Information System (INIS)

    Knapp, D.A.; Marrs, R.E.; Elliott, S.R.; Magee, E.W.; Zasadzinski, R.

    1993-01-01

    We have developed a new high-energy electron beam ion trap, the first laboratory source of low-energy, few-electron, high-Z ions. We describe the device and report measurements of its performance, including the electron beam diameter, current density and energy, and measurements of the ionization balance for several high-Z elements in the trap. This device opens up a wide range of possible experiments in atomic physics, plasma physics, and nuclear physics. (orig.)

  18. Origin of the main deep electron trap in electron irradiated InP

    International Nuclear Information System (INIS)

    Sibille, A.

    1986-01-01

    The electrical activity and annealing behavior of the main electron trap in electron irradiated InP p + n junctions has been investigated. A very marked depth dependence of the annealing rate has been found. Moreover, this center apparently acts as if it were a deep donor, leading to an increase of carrier concentration on the n side. All these results are coherently interpreted with a model in terms of radiation defect D(P) (phosphorus interstitial or vacancy), residual shallow acceptor complexing, the final annealing resulting from a dissociation of the complex followed by a diffusion and either recapture or annihilation of D(P)

  19. Effects of the radial electrical field on the drifts, trapping and particle orbits in TJ-II

    International Nuclear Information System (INIS)

    Guasp, J.; Liniers, M.

    1997-01-01

    In this study a detailed analysis of the effect of radial electric fields on drifts, trapping and trajectories for ions of low and intermediate energy (0.1-1 keV) in the helical axis stellarator TJ-II has been performed. In TJ-II the drift velocities have the same rotation direction than the Hard Core (HC, the same than the plasma) with predominance of the vertical downwards component. The intensity is higher near the HC and in the outwards direction. These trends create strong asymmetries in losses even in the absence of electric field. When an electric field is present the poloidal components of the drift velocity predominates modifying deeply the orbit behaviour. Positive electric fields produce internal radial trapping barriers and have a tendency to eliminate the external ones. The opposite happens for negative fields. These facts alterate deeply the tapping and confinement properties of the particles. All these analysis will be used as a basis for the understanding of the modifications on the loss distribution, trapping regions and loss cones for TJ-II that will be addressed in forthcoming studies. (Author)

  20. 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

  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. Formation of hydrogen-related traps in electron-irradiated n-type silicon by wet chemical etching

    International Nuclear Information System (INIS)

    Tokuda, Yutaka; Shimada, Hitoshi

    1998-01-01

    Interaction of hydrogen atoms and vacancy-related defects in 10 MeV electron-irradiated n-type silicon has been studied by deep-level transient spectroscopy. Hydrogen has been incorporated into electron-irradiated n-type silicon by wet chemical etching. The reduction of the concentration of the vacancy-oxygen pair and divacancy occurs by the incorporation of hydrogen, while the formation of the NH1 electron trap (E c - 0.31 eV) is observed. Further decrease of the concentration of the vacancy-oxygen pair and further increase of the concentration of the NH1 trap are observed upon subsequent below-band-gap light illumination. It is suggested that the trap NH1 is tentatively ascribed to the vacancy-oxygen pair which is partly saturated with hydrogen

  3. Measurement of few-electron uranium ions on a high-energy electron beam ion trap

    International Nuclear Information System (INIS)

    Beiersdorfer, P.

    1994-01-01

    The high-energy electron beam ion trap, dubbed Super-EBIT, was used to produce, trap, and excite uranium ions as highly charged as fully stripped U 92+ . The production of such highly charged ions was indicated by the x-ray emission observed with high-purity Ge detectors. Moreover, high-resolution Bragg crystal spectromters were used to analyze the x-ray emission, including a detailed measurement of both the 2s 1/2 -2p 3/2 electric dipole and 2p 1/2 -2p 3/2 magnetic dipole transitions. Unlike in ion accelerators, where the uranium ions move at relativistic speeds, the ions in this trap are stationary. Thus very precise measurements of the transition energies could be made, and the QED contribution to the transition energies could be measured within less than 1 %. Details of the production of these highly charged ions and their measurement is given

  4. Atomic origin of high-temperature electron trapping in metal-oxide-semiconductor devices

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Xiao, E-mail: xiao.shen@vanderbilt.edu [Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235 (United States); Dhar, Sarit [Department of Physics, Auburn University, Auburn, Alabama 36849 (United States); Pantelides, Sokrates T. [Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235 (United States); Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, Tennessee 37235 (United States); Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

    2015-04-06

    MOSFETs based on wide-band-gap semiconductors are suitable for operation at high temperature, at which additional atomic-scale processes that are benign at lower temperatures can get activated, resulting in device degradation. Recently, significant enhancement of electron trapping was observed under positive bias in SiC MOSFETs at temperatures higher than 150 °C. Here, we report first-principles calculations showing that the enhanced electron trapping is associated with thermally activated capturing of a second electron by an oxygen vacancy in SiO{sub 2} by which the vacancy transforms into a structure that comprises one Si dangling bond and a bond between a five-fold and a four-fold Si atoms. The results suggest a key role of oxygen vacancies and their structural reconfigurations in the reliability of high-temperature MOS devices.

  5. EUV spectrum of highly charged tungsten ions in electron beam ion trap

    International Nuclear Information System (INIS)

    Sakaue, H.A.; Kato, D.; Murakami, I.; Nakamura, N.

    2016-01-01

    We present spectra of highly charged tungsten ions in the extreme ultra-violet (EUV) by using electron beam ion traps. The electron energy dependence of spectra was investigated for electron energy from 540 to 1370 eV. Previously unreported lines were presented in the EUV range, and comparing the wavelengths with theoretical calculations identified them. (author)

  6. Experimental evaluation of quantum computing elements (qubits) made of electrons trapped over a liquid helium film

    International Nuclear Information System (INIS)

    Rousseau, E.

    2006-12-01

    An electron on helium presents a quantized energy spectrum. The interaction with the environment is considered sufficiently weak in order to allow the realization of a quantum bit (qubit) by using the first two energy levels. The first stage in the realization of this qubit was to trap and control a single electron. This is carried out thanks to a set of micro-fabricated electrodes defining a well of potential in which the electron is trapped. We are able with such a sample to trap and detect a variables number of electrons varying between one and around twenty. This then allowed us to study the static behaviour of a small number of electrons in a trap. They are supposed to crystallize and form structures called Wigner molecules. Such molecules have not yet been observed yet with electrons above helium. Our results bring circumstantial evidence for of Wigner crystallization. We then sought to characterize the qubit more precisely. We sought to carry out a projective reading (depending on the state of the qubit) and a measurement of the relaxation time. The results were obtained by exciting the electron with an incoherent electric field. A clean measurement of the relaxation time would require a coherent electric field. The conclusion cannot thus be final but it would seem that the relaxation time is shorter than calculated theoretically. That is perhaps due to a measurement of the relaxation between the oscillating states in the trap and not between the states of the qubit. (author)

  7. Thermal and optical excitation of trapped electrons in high-density polyethylene (HDPE) studied through positron annihilation

    International Nuclear Information System (INIS)

    Nahid, F.; Zhang, J.D.; Yu, T.F.; Ling, C.C.; Fung, S.; Beling, C.D.

    2011-01-01

    Positronium (Ps) formation in high-density polyethylene (HDPE) has been studied below the glass transition temperature. The formation probability increases with positron irradiation time due to an increasing number of inter-track trapped electrons becoming available for positron capture. The temperature variation of the saturated Ps level is discussed in different models. The quenching of trapped electrons by light has been studied and the optical de-trapping cross-section for different photon energies has been estimated over the visible region.

  8. Dependence of the trapping regions with the radial electric field in TJ-II

    International Nuclear Information System (INIS)

    Guasp, J.; Liniers, M.

    1997-01-01

    The influence of the electric field upon the radial and angular distributions of trapped ions of energies between 0.1 and 1 keV in TJ-II is analysed. Near the magnetic axis, with moderate electric fields, the trapped fraction increases for negative potentials and decreases for positive ones. Nevertheless for high potentials this decreasing for positive sign can be reversed. Near the plasma periphery trapping is affected only for high potentials and always increases, independently of the potential sign. The sensibility to negative potentials is always higher than for the positive ones. These trapping changes are almost uniform in poloidal and toroidal angular profiles and affect mainly to marginally trapped or passing particles. Nevertheless for high potentials or energie the resonances modify this behaviour and inhibit the increasing of trapping in the outer side or the torus. For the locally trapped population fraction a steady decrease with the potential appears independently of the sign, except very near the magnetic axis or the plasma periphery. The global result of all these partial effects is the presence of a wide trapping minimum for moderate positive electric potential, potential that increases with the ion energy as well as a strong increase for high electric fields of either sign, more visible for negative potentials and high energies. For the locally trapped population a steady decrease with potential appears independently of the sign. All these effects can be explained by the combined action of the appearance and elimination of radial magnetic barriers and of the electric field resonances. (Author)

  9. Effect of trapped electrons on the transient current density and luminance of organic light-emitting diode

    Science.gov (United States)

    Lee, Jiun-Haw; Chen, Chia-Hsun; Lin, Bo-Yen; Shih, Yen-Chen; Lin, King-Fu; Wang, Leeyih; Chiu, Tien-Lung; Lin, Chi-Feng

    2018-04-01

    Transient current density and luminance from an organic light-emitting diode (OLED) driven by voltage pulses were investigated. Waveforms with different repetition rate, duty cycle, off-period, and on-period were used to study the injection and transport characteristics of electron and holes in an OLED under pulse operation. It was found that trapped electrons inside the emitting layer (EML) and the electron transporting layer (ETL) material, tris(8-hydroxyquinolate)aluminum (Alq3) helped for attracting the holes into the EML/ETL and reducing the driving voltage, which was further confirmed from the analysis of capacitance-voltage and displacement current measurement. The relaxation time and trapped filling time of the trapped electrons in Alq3 layer were ~200 µs and ~600 µs with 6 V pulse operation, respectively.

  10. Electronic relaxation of deep bulk trap and interface state in ZnO ceramics

    International Nuclear Information System (INIS)

    Yang Yan; Li Sheng-Tao; Ding Can; Cheng Peng-Fei

    2011-01-01

    This paper investigates the electronic relaxation of deep bulk trap and interface state in ZnO ceramics based on dielectric spectra measured in a wide range of temperature, frequency and bias, in addition to the steady state response. It discusses the nature of net current flowing over the barrier affected by interface state, and then obtains temperature-dependent barrier height by approximate calculation from steady I—V (current—voltage) characteristics. Additional conductance and capacitance arising from deep bulk trap relaxation are calculated based on the displacement of the cross point between deep bulk trap and Fermi level under small AC signal. From the resonances due to deep bulk trap relaxation on dielectric spectra, the activation energies are obtained as 0.22 eV and 0.35 eV, which are consistent with the electronic levels of the main defect interstitial Zn and vacancy oxygen in the depletion layer. Under moderate bias, another resonance due to interface relaxation is shown on the dielectric spectra. The DC-like conductance is also observed in high temperature region on dielectric spectra, and the activation energy is much smaller than the barrier height in steady state condition, which is attributed to the displacement current coming from the shallow bulk trap relaxation or other factors. (fluids, plasmas and electric discharges)

  11. The Electronic McPhail Trap

    Science.gov (United States)

    Potamitis, Ilyas; Rigakis, Iraklis; Fysarakis, Konstantinos

    2014-01-01

    Certain insects affect cultivations in a detrimental way. A notable case is the olive fruit fly (Bactrocera oleae (Rossi)), that in Europe alone causes billions of euros in crop-loss/per year. Pests can be controlled with aerial and ground bait pesticide sprays, the efficiency of which depends on knowing the time and location of insect infestations as early as possible. The inspection of traps is currently carried out manually. Automatic monitoring traps can enhance efficient monitoring of flying pests by identifying and counting targeted pests as they enter the trap. This work deals with the hardware setup of an insect trap with an embedded optoelectronic sensor that automatically records insects as they fly in the trap. The sensor responsible for detecting the insect is an array of phototransistors receiving light from an infrared LED. The wing-beat recording is based on the interruption of the emitted light due to the partial occlusion from insect's wings as they fly in the trap. We show that the recordings are of high quality paving the way for automatic recognition and transmission of insect detections from the field to a smartphone. This work emphasizes the hardware implementation of the sensor and the detection/counting module giving all necessary implementation details needed to construct it. PMID:25429412

  12. Effects of irradiation and isochronal anneal temperature on hole and electron trapping in MOS devices

    International Nuclear Information System (INIS)

    Fleetwood, D.M.; Winokur, P.S.; Shaneyfelt, M.R.; Riewe, L.C.; Flament, O.; Paillet, P.; Leray, J.L.

    1998-02-01

    Capacitance-voltage and thermally-stimulated-current techniques are used to estimate trapped hole and electron densities in MOS oxides as functions of irradiation and isochronal anneal temperature. Trapped-charge annealing and compensation effects are discussed

  13. Bifurcation analysis for ion acoustic waves in a strongly coupled plasma including trapped electrons

    Science.gov (United States)

    El-Labany, S. K.; El-Taibany, W. F.; Atteya, A.

    2018-02-01

    The nonlinear ion acoustic wave propagation in a strongly coupled plasma composed of ions and trapped electrons has been investigated. The reductive perturbation method is employed to derive a modified Korteweg-de Vries-Burgers (mKdV-Burgers) equation. To solve this equation in case of dissipative system, the tangent hyperbolic method is used, and a shock wave solution is obtained. Numerical investigations show that, the ion acoustic waves are significantly modified by the effect of polarization force, the trapped electrons and the viscosity coefficients. Applying the bifurcation theory to the dynamical system of the derived mKdV-Burgers equation, the phase portraits of the traveling wave solutions of both of dissipative and non-dissipative systems are analyzed. The present results could be helpful for a better understanding of the waves nonlinear propagation in a strongly coupled plasma, which can be produced by photoionizing laser-cooled and trapped electrons [1], and also in neutron stars or white dwarfs interior.

  14. Molecular dynamics simulation of electron trapping in the sapphire lattice

    International Nuclear Information System (INIS)

    Rambaut, C.; Oh, K.H.; Fayeulle, S.; Kohanoff, J.

    1995-10-01

    Energy storage and release in dielectric materials can be described on the basis of the charge trapping mechanism. Most phenomenological aspects have been recently rationalized in terms of the space charge mode. Dynamical aspects are studied here by performing Molecular Dynamics simulations. We show that an excess electron introduced into the sapphire lattice (α -Al 2 O 3 ) can be trapped only at a limited number of sites. The energy gained by allowing the electron to localize in these sites is of the order of 4-5 eV, in good agreement with the results of the space charge model. Displacements of the neighboring ions due to the implanted charge are shown to be localized in a small region of about 5 A. Detrapping is observed at 250 K. The ionic displacements turn out to play an important role in modifying the potential landscape by lowering, in a dynamical way, the barriers that cause localization at low temperature. (author). 18 refs, 7 figs, 2 tabs

  15. Coupled ion temperature gradient and trapped electron mode to electron temperature gradient mode gyrokinetic simulations

    International Nuclear Information System (INIS)

    Waltz, R. E.; Candy, J.; Fahey, M.

    2007-01-01

    Electron temperature gradient (ETG) transport is conventionally defined as the electron energy transport at high wave number (high-k) where ions are adiabatic and there can be no ion energy or plasma transport. Previous gyrokinetic simulations have assumed adiabatic ions (ETG-ai) and work on the small electron gyroradius scale. However such ETG-ai simulations with trapped electrons often do not have well behaved nonlinear saturation unless fully kinetic ions (ki) and proper ion scale zonal flow modes are included. Electron energy transport is separated into ETG-ki at high-k and ion temperature gradient-trapped electron mode (ITG/TEM) at low-k. Expensive (more computer-intensive), high-resolution, large-ion-scale flux-tube simulations coupling ITG/TEM and ETG-ki turbulence are presented. These require a high effective Reynolds number R≡[k(max)/k(min)] 2 =μ 2 , where μ=[ρ si /ρ si ] is the ratio of ion to electron gyroradii. Compute times scale faster than μ 3 . By comparing the coupled expensive simulations with (1) much cheaper (less compute-intensive), uncoupled, high-resolution, small, flux-tube ETG-ki and with (2) uncoupled low-resolution, large, flux-tube ITG/TEM simulations, and also by artificially turning ''off'' the low-k or high-k drives, it appears that ITG/TEM and ETG-ki transport are not strongly coupled so long as ETG-ki can access some nonadiabatic ion scale zonal flows and both high-k and low-k are linearly unstable. However expensive coupled simulations are required for physically accurate k-spectra of the transport and turbulence. Simulations with μ≥30 appear to represent the physical range μ>40. ETG-ki transport measured in ion gyro-Bohm units is weakly dependent on μ. For the mid-radius core tokamak plasma parameters studied, ETG-ki is about 10% of the electron energy transport, which in turn is about 30% of the total energy transport (with negligible ExB shear). However at large ExB shear sufficient to quench the low-k ITG

  16. The Electronic McPhail Trap

    Directory of Open Access Journals (Sweden)

    Ilyas Potamitis

    2014-11-01

    Full Text Available Certain insects affect cultivations in a detrimental way. A notable case is the olive fruit fly (Bactrocera oleae (Rossi, that in Europe alone causes billions of euros in crop-loss/per year. Pests can be controlled with aerial and ground bait pesticide sprays, the efficiency of which depends on knowing the time and location of insect infestations as early as possible. The inspection of traps is currently carried out manually. Automatic monitoring traps can enhance efficient monitoring of flying pests by identifying and counting targeted pests as they enter the trap. This work deals with the hardware setup of an insect trap with an embedded optoelectronic sensor that automatically records insects as they fly in the trap. The sensor responsible for detecting the insect is an array of phototransistors receiving light from an infrared LED. The wing-beat recording is based on the interruption of the emitted light due to the partial occlusion from insect’s wings as they fly in the trap. We show that the recordings are of high quality paving the way for automatic recognition and transmission of insect detections from the field to a smartphone. This work emphasizes the hardware implementation of the sensor and the detection/counting module giving all necessary implementation details needed to construct it.

  17. A tunable electron beam source using trapping of electrons in a density down-ramp in laser wakefield acceleration.

    Science.gov (United States)

    Ekerfelt, Henrik; Hansson, Martin; Gallardo González, Isabel; Davoine, Xavier; Lundh, Olle

    2017-09-25

    One challenge in the development of laser wakefield accelerators is to demonstrate sufficient control and reproducibility of the parameters of the generated bunches of accelerated electrons. Here we report on a numerical study, where we demonstrate that trapping using density down-ramps allows for tuning of several electron bunch parameters by varying the properties of the density down-ramp. We show that the electron bunch length is determined by the difference in density before and after the ramp. Furthermore, the transverse emittance of the bunch is controlled by the steepness of the ramp. Finally, the amount of trapped charge depends both on the density difference and on the steepness of the ramp. We emphasize that both parameters of the density ramp are feasible to vary experimentally. We therefore conclude that this tunable electron accelerator makes it suitable for a wide range of applications, from those requiring short pulse length and low emittance, such as the free-electron lasers, to those requiring high-charge, large-emittance bunches to maximize betatron X-ray generation.

  18. Electron trapping and acceleration by the plasma wakefield of a self-modulating proton beam

    CERN Document Server

    Lotov, K.V.; Petrenko, A.V.; Amorim, L.D.; Vieira, J.; Fonseca, R.A.; Silva, L.O.; Gschwendtner, E.; Muggli, P.

    2014-01-01

    It is shown that co-linear injection of electrons or positrons into the wakefield of the self-modulating particle beam is possible and ensures high energy gain. The witness beam must co-propagate with the tail part of the driver, since the plasma wave phase velocity there can exceed the light velocity, which is necessary for efficient acceleration. If the witness beam is many wakefield periods long, then the trapped charge is limited by beam loading effects. The initial trapping is better for positrons, but at the acceleration stage a considerable fraction of positrons is lost from the wave. For efficient trapping of electrons, the plasma boundary must be sharp, with the density transition region shorter than several centimeters. Positrons are not susceptible to the initial plasma density gradient.

  19. Hydrogen treatment as a detergent of electronic trap states in lead chalcogenide nanoparticles

    Science.gov (United States)

    Voros, Marton; Brawand, Nicholas; Galli, Giulia

    Lead chalcogenide (PbX) nanoparticles are promising materials for solar energy conversion. However, the presence of trap states in their electronic gap limits their usability, and developing a universal strategy to remove trap states is a persistent challenge. Using calculations based on density functional theory, we show that hydrogen acts as an amphoteric impurity on PbX nanoparticle surfaces; hydrogen atoms may passivate defects arising from ligand imbalance or off-stoichiometric surface terminations, irrespective of whether they originate from cation or anion excess. In addition, we show, using constrained density functional theory calculations, that hydrogen treatment of defective nanoparticles is also beneficial for charge transport in films. We also find that hydrogen adsorption on stoichiometric nanoparticles leads to electronic doping, preferentially n-type. Our findings suggest that post-synthesis hydrogen treatment of lead chalcogenide nanoparticle films is a viable approach to reduce electronic trap states or to dope well-passivated films. Work supported by the Center for Advanced Solar Photophysics, an Energy Frontier Research Center funded by the US Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences (NB) and U.S. DOE under Contract No. DE-AC02-06CH11357 (MV).

  20. Direct exchange between silicon nanocrystals and tunnel oxide traps under illumination on single electron photodetector

    Energy Technology Data Exchange (ETDEWEB)

    Chatbouri, S., E-mail: Samir.chatbouri@yahoo.com; Troudi, M.; Sghaier, N.; Kalboussi, A. [Avenue de I’environnement, Université de Monastir, Laboratoire de Micro électronique et Instrumentation (LR13ES12), Faculté des Sciences de Monastir (Tunisia); Aimez, V. [Université de Sherbrooke, Laboratoire Nanotechnologies et Nanosystémes (UMI-LN2 3463), Université de Sherbrooke—CNRS—INSA de Lyon-ECL-UJF-CPE Lyon, Institut Interdisciplinaire d’Innovation Technologique (Canada); Drouin, D. [Avenue de I’environnement, Université de Monastir, Laboratoire de Micro électronique et Instrumentation (LR13ES12), Faculté des Sciences de Monastir (Tunisia); Souifi, A. [Institut des Nanotechnologies de Lyon—site INSA de Lyon, UMR CNRS 5270 (France)

    2016-09-15

    In this paper we present the trapping of photogenerated charge carriers for 300 s resulted by their direct exchange under illumination between a few silicon nanocrystals (ncs-Si) embedded in an oxide tunnel layer (SiO{sub x} = 1.5) and the tunnel oxide traps levels for a single electron photodetector (photo-SET or nanopixel). At first place, the presence of a photocurrent limited in the inversion zone under illumination in the I–V curves confirms the creation of a pair electron/hole (e–h) at high energy. This photogenerated charge carriers can be trapped in the oxide. Using the capacitance-voltage under illumination (the photo-CV measurements) we show a hysteresis chargement limited in the inversion area, indicating that the photo-generated charge carriers are stored at traps levels at the interface and within ncs-Si. The direct exchange of the photogenerated charge carriers between the interface traps levels and the ncs-Si contributed on the photomemory effect for 300 s for our nanopixel at room temperature.

  1. Charge transport in micas: The kinetics of FeII/III electron transfer in the octahedral sheet

    International Nuclear Information System (INIS)

    Rosso, Kevin M.; Ilton, Eugene S.

    2003-01-01

    The two principal FeII/III electron exchange reactions underlying charge transport in the octahedral sheet of ideal end-member annite were modeled using a combination of ab initio calculations and Marcus electron transfer theory. A small polaron model was applied which yielded electron hopping activation energies that agree well with the limited available experimental data. A small ab initio cluster model successfully reproduced several important structural, energetic, and magnetic characteristics of the M1 and M2 Fe sites in the annite octahedral sheet. The cluster enabled calculation of the internal reorganization energy and electronic coupling matrix elements for the M2-M2 and M1-M2 electron transfer reactions. The M2-M2 electron transfer is symmetric with a predicted forward/reverse electron hopping rate of 106 s-1. The M1-M2 electron transfers are asymmetric due to the higher ionization potential by 0.46 eV of FeII in the M1 site. The electronic coupling matrix elements for these reactions are predicted to be small and of similar magnitude, suggesting the possibility that the coupling is essentially direction independent amongst hopping directions in the octahedral sheet. M1 Fe sites are predicted to be efficient electron traps and charge transport should occur by nearest-neighbor electron hops along the M2 Fe sublattice

  2. Properties and parameters of the electron beam injected into the mirror magnetic trap of a plasma accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Andreev, V. V., E-mail: temple18@mail.ru; Novitsky, A. A.; Vinnichenko, L. A.; Umnov, A. M.; Ndong, D. O. [Peoples’ Friendship University of Russia (Russian Federation)

    2016-03-15

    The parameters of the injector of an axial plasma beam injected into a plasma accelerator operating on the basis of gyroresonance acceleration of electrons in the reverse magnetic field are determined. The trapping of the beam electrons into the regime of gyroresonance acceleration is numerically simulated by the particle- in-cell method. The optimal time of axial injection of the beam into a magnetic mirror trap is determined. The beam parameters satisfying the condition of efficient particle trapping into the gyromagnetic autoresonance regime are found.

  3. 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

  4. Dynamic tunneling force microscopy for characterizing electronic trap states in non-conductive surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Wang, R.; Williams, C. C., E-mail: clayton@physics.utah.edu [Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112 (United States)

    2015-09-15

    Dynamic tunneling force microscopy (DTFM) is a scanning probe technique for real space mapping and characterization of individual electronic trap states in non-conductive films with atomic scale spatial resolution. The method is based upon the quantum mechanical tunneling of a single electron back and forth between a metallic atomic force microscopy tip and individual trap states in completely non-conducting surface. This single electron shuttling is measured by detecting the electrostatic force induced on the probe tip at the shuttling frequency. In this paper, the physical basis for the DTFM method is unfolded through a physical model and a derivation of the dynamic tunneling signal as a function of several experimental parameters is shown. Experimental data are compared with the theoretical simulations, showing quantitative consistency and verifying the physical model used. The experimental system is described and representative imaging results are shown.

  5. Zonal flow generation in collisionless trapped electron mode turbulence

    International Nuclear Information System (INIS)

    Anderson, J; Nordman, H; Singh, R; Weiland, J

    2006-01-01

    In the present work the generation of zonal flows in collisionless trapped electron mode (TEM) turbulence is studied analytically. A reduced model for TEM turbulence is utilized based on an advanced fluid model for reactive drift waves. An analytical expression for the zonal flow growth rate is derived and compared with the linear TEM growth, and its scaling with plasma parameters is examined for typical tokamak parameter values

  6. In situ electromagnetic field diagnostics with an electron plasma in a Penning-Malmberg trap

    CERN Document Server

    Amole, C; Baquero-Ruiz, M.; Bertsche, W.; Butler, E.; Capra, A.; Cesar, C.L.; Charlton, M.; Deller, A.; Evetts, N.; Eriksson, S.; Fajans, J.; Friesen, T.; Fujiwara, M.C.; Gill, D.R.; Gutierrez, A.; Hangst, J.S.; Hardy, W.N.; Hayden, M.E.; Isaac, C.A.; Jonsell, S.; Kurchaninov, L.; Little, A.; Madsen, N.; McKenna, J.T.K.; Menary, S.; Napoli, S.C.; Olchanski, K.; Olin, A.; Pusa, P.; Rasmussen, C.; Robicheaux, F.; Sarid, E.; Silveira, D.M.; So, C.; Stracka, S.; Tharp, T.; Thompson, R.I.; van der Werf, D.P.; Wurtele, J.S.

    2014-01-01

    We demonstrate a novel detection method for the cyclotron resonance frequency of an electron plasma in a Penning-Malmberg trap. With this technique, the electron plasma is used as an in situ diagnostic tool for measurement of the static magnetic field and the microwave electric field in the trap. The cyclotron motion of the electron plasma is excited by microwave radiation and the temperature change of the plasma is measured non-destructively by monitoring the plasma's quadrupole mode frequency. The spatially-resolved microwave electric field strength can be inferred from the plasma temperature change and the magnetic field is found through the cyclotron resonance frequency. These measurements were used extensively in the recently reported demonstration of resonant quantum interactions with antihydrogen.

  7. Trap-mediated electronic transport properties of gate-tunable pentacene/MoS2 p-n heterojunction diodes.

    Science.gov (United States)

    Kim, Jae-Keun; Cho, Kyungjune; Kim, Tae-Young; Pak, Jinsu; Jang, Jingon; Song, Younggul; Kim, Youngrok; Choi, Barbara Yuri; Chung, Seungjun; Hong, Woong-Ki; Lee, Takhee

    2016-11-10

    We investigated the trap-mediated electronic transport properties of pentacene/molybdenum disulphide (MoS 2 ) p-n heterojunction devices. We observed that the hybrid p-n heterojunctions were gate-tunable and were strongly affected by trap-assisted tunnelling through the van der Waals gap at the heterojunction interfaces between MoS 2 and pentacene. The pentacene/MoS 2 p-n heterojunction diodes had gate-tunable high ideality factor, which resulted from trap-mediated conduction nature of devices. From the temperature-variable current-voltage measurement, a space-charge-limited conduction and a variable range hopping conduction at a low temperature were suggested as the gate-tunable charge transport characteristics of these hybrid p-n heterojunctions. Our study provides a better understanding of the trap-mediated electronic transport properties in organic/2-dimensional material hybrid heterojunction devices.

  8. Dependence of secondary electron emission on surface charging in sapphire and polycrystalline alumina: Evaluation of the effective cross sections for recombination and trapping

    International Nuclear Information System (INIS)

    Said, K.; Damamme, G.; Si Ahmed, A.; Moya, G.; Kallel, A.

    2014-01-01

    Highlights: • A novel approach for the analysis of the secondary electron emission in connection with the surface density of trapped charges. • Experimental estimation of the effective cross section for electron–hole recombination and electron trapping in defects. • A simplified charge transport and trapping model which corroborates qualitatively the interpretation of the results. - Abstract: The evolution of the secondary electron emission from sapphire and polycrystalline alumina during electron irradiation, achieved in a scanning electron microscope at room temperature, is derived from the measurement of the induced and the secondary electron currents. The semi-logarithmic plot of the secondary electron emission yield versus the surface density of trapped charges displays a plateau followed by a linear variation. For positive charging, the slope of the linear part, whose value is of about 10 −9 cm 2 , is independent of the primary electron energy, the microstructure and the impurities. It is interpreted as an effective microscopic cross section for electron–hole recombination. For negative charging of sapphire, the slope is associated with an effective electron trapping cross section close to 10 −11 cm 2 , which can be assigned to the dominant impurity trap. These effective values reflect the multiple interactions leading to the accumulation of charges. The yield corresponding to the plateau is controlled by the initial density of impurity traps. A charge transport and trapping >model, based on simplifying assumptions, confirms qualitatively these inferences

  9. Increased electric sail thrust through removal of trapped shielding electrons by orbit chaotisation due to spacecraft body

    Directory of Open Access Journals (Sweden)

    P. Janhunen

    2009-08-01

    Full Text Available An electric solar wind sail is a recently introduced propellantless space propulsion method whose technical development has also started. The electric sail consists of a set of long, thin, centrifugally stretched and conducting tethers which are charged positively and kept in a high positive potential of order 20 kV by an onboard electron gun. The positively charged tethers deflect solar wind protons, thus tapping momentum from the solar wind stream and producing thrust. The amount of obtained propulsive thrust depends on how many electrons are trapped by the potential structures of the tethers, because the trapped electrons tend to shield the charged tether and reduce its effect on the solar wind. Here we present physical arguments and test particle calculations indicating that in a realistic three-dimensional electric sail spacecraft there exist a natural mechanism which tends to remove the trapped electrons by chaotising their orbits and causing them to eventually collide with the conducting tethers. We present calculations which indicate that if these mechanisms were able to remove trapped electrons nearly completely, the electric sail performance could be about five times higher than previously estimated, about 500 nN/m, corresponding to 1 N thrust for a baseline construction with 2000 km total tether length.

  10. Real-space Mapping of Surface Trap States in CIGSe Nanocrystals using 4D Electron Microscopy

    KAUST Repository

    Bose, Riya

    2016-05-26

    Surface trap states in semiconductor copper indium gallium selenide nanocrystals (NCs) which serve as undesirable channels for non-radiative carrier recombination, remain a great challenge impeding the development of solar and optoelectronics devices based on these NCs. In order to design efficient passivation techniques to minimize these trap states, a precise knowledge about the charge carrier dynamics on the NCs surface is essential. However, selective mapping of surface traps requires capabilities beyond the reach of conventional laser spectroscopy and static electron microscopy; it can only be accessed by using a one-of-a-kind, second-generation four-dimensional scanning ultrafast electron microscope (4D S-UEM) with sub-picosecond temporal and nanometer spatial resolutions. Here, we precisely map the surface charge carrier dynamics of copper indium gallium selenide NCs before and after surface passivation in real space and time using S-UEM. The time-resolved snapshots clearly demonstrate that the density of the trap states is significantly reduced after zinc sulfide (ZnS) shelling. Furthermore, removal of trap states and elongation of carrier lifetime are confirmed by the increased photocurrent of the self-biased photodetector fabricated using the shelled NCs.

  11. Real-space Mapping of Surface Trap States in CIGSe Nanocrystals using 4D Electron Microscopy

    KAUST Repository

    Bose, Riya; Bera, Ashok; Parida, Manas R.; Adhikari, Aniruddha; Shaheen, Basamat; Alarousu, Erkki; Sun, Jingya; Wu, Tao; Bakr, Osman; Mohammed, Omar F.

    2016-01-01

    Surface trap states in semiconductor copper indium gallium selenide nanocrystals (NCs) which serve as undesirable channels for non-radiative carrier recombination, remain a great challenge impeding the development of solar and optoelectronics devices based on these NCs. In order to design efficient passivation techniques to minimize these trap states, a precise knowledge about the charge carrier dynamics on the NCs surface is essential. However, selective mapping of surface traps requires capabilities beyond the reach of conventional laser spectroscopy and static electron microscopy; it can only be accessed by using a one-of-a-kind, second-generation four-dimensional scanning ultrafast electron microscope (4D S-UEM) with sub-picosecond temporal and nanometer spatial resolutions. Here, we precisely map the surface charge carrier dynamics of copper indium gallium selenide NCs before and after surface passivation in real space and time using S-UEM. The time-resolved snapshots clearly demonstrate that the density of the trap states is significantly reduced after zinc sulfide (ZnS) shelling. Furthermore, removal of trap states and elongation of carrier lifetime are confirmed by the increased photocurrent of the self-biased photodetector fabricated using the shelled NCs.

  12. Forces of vortice trapping and critical current in type II superconductors

    International Nuclear Information System (INIS)

    Bormio, C.

    1985-12-01

    The vortice-centers interactions of trapping in type II superconductor materials were studied by two theories: thermodynamic (Hampshire-Taylor) and microscopic (Larkin - Ovchinnikov). The study was applied to NbTi with composition of 50% weight of Ti. They are commercial cables containing 361 filaments with final diameter of 0.35 mm for the wire and 9.2 μm foi filaments. The material presents high deformation rate in area and high density of dislocations. These defects actuate as centers of trapping. Variations in themomechanical treatments of superconductor cables modify the interaction mechanisms. The specific mechanism for each treatment type was identified. Measurements of critical current density in function of magnetic field in the range from 1 to 7 Tesla were done, which the usual superconductor parameters as upper critical field and Ginzburg - Landau (Kappa-k) parameter are estimated from literature data. (M.C.K.) [pt

  13. Formation of Deep Electron Trap by Yb3+ Codoping Leads into Super-Long Persistent Luminescence in Ce3+-doped Yttrium Aluminum Gallium Garnet Phosphors.

    Science.gov (United States)

    Ueda, Jumpei; Miyano, Shun; Tanabe, Setsuhisa

    2018-05-23

    The Y 3 Al 2 Ga 3 O 12 :Ce 3+ -Cr 3+ compound is one of the brightest persistent phosphors, but its persistent luminescence (PersL) duration is not so long due to the relatively shallow Cr 3+ electron trap. Comparing the vacuum referred binding energy of the electron trapping state by Cr 3+ and those by lanthanide ions, we selected Yb 3+ as a deeper electron trapping center. The Y 3 Al 2 Ga 3 O 12 :Ce 3+ -Yb 3+ phosphors show Ce 3+ :5d→4f green persistent luminescence after ceasing blue light excitation. The formation of Yb 2+ was confirmed by the increased intensity of absorption at 585 nm during the charging process. This result indicates that the Yb 3+ ions act as electron traps by capturing an electron. From the thermoluminescence glow curves, it was found the Yb 3+ trap makes much deeper electron trap with 1.01 eV depth than the Cr 3+ electron trap with 0.81 eV depth. This deeper Yb 3+ trap provides much slower detrapping rate of filled electron traps than the Cr 3+ -codoped persistent phosphor. In addition, by preparing transparent ceramics and optimizing Ce 3+ and Yb 3+ concentrations, the Y 3 Al 2 Ga 3 O 12 :Ce 3+ (0.2%)-Yb 3+ (0.1%) as-made transparent ceramic phosphor showed super long persistent luminescence for over 138.8 hours after ceasing blue light charging.

  14. Impact of electron trapping on RF current drive in tokamaks

    International Nuclear Information System (INIS)

    Giruzzi, G.; Engelmann, F.

    1987-01-01

    The impact of the presence of trapped electrons on noninductive current drive by RF waves in tokamak plasmas is investigated. The appropriate response function, allowing to express the current drive efficiency J/P by a simple analytical formula, has been derived. The approach displays the reasons for the degradation of the current drive efficiency away from the plasma axis in the case of methods relying on the diffusion of electrons in the velocity component perpendicular to the confining magnetic field. It is shown that this degradation is appreciable even for large resonant parallel velocities. (author) [pt

  15. Overview of the Livermore electron beam ion trap project

    International Nuclear Information System (INIS)

    Beiersdorfer, P.; Behar, E.; Boyce, K.R.; Brown, G.V.; Chen, H.; Gendreau, K.C.; Graf, A.; Gu, M.-F.; Harris, C.L.; Kahn, S.M.; Kelley, R.L.; Lepson, J.K.; May, M.J.; Neill, P.A.; Pinnington, E.H.; Porter, F.S.; Smith, A.J.; Stahle, C.K.; Szymkowiak, A.E.; Tillotson, A.; Thorn, D.B.; Traebert, E.; Wargelin, B.J.

    2003-01-01

    The Livermore electron beam ion trap facility has recently been moved to a new location within LLNL, and new instrumentation was added, including a 32-pixel microcalorimeter. The move was accompanied by a shift of focus toward in situ measurements of highly charged ions, which continue with increased vigor. Overviews of the facility, which includes EBIT-I and SuperEBIT, and the research projects are given, including results from optical spectroscopy, QED, and X-ray line excitation measurements

  16. Kinetic features and non-stationary electron trapping in paraxial magnetic nozzles

    Science.gov (United States)

    Sánchez-Arriaga, G.; Zhou, J.; Ahedo, E.; Martínez-Sánchez, M.; Ramos, J. J.

    2018-03-01

    The paraxial expansion of a collisionless plasma jet into vacuum, guided by a magnetic nozzle, is studied with an Eulerian and non-stationary Vlasov-Poisson solver. Parametric analyzes varying the magnetic field expansion rate, the size of the simulation box, and the electrostatic potential fall are presented. After choosing the potential fall leading to a zero net current beam, the steady states of the simulations exhibit a quasi-neutral region followed by a downstream sheath. The latter, an unavoidable consequence of the finite size of the computational domain, does not affect the quasi-neutral region if the box size is chosen appropriately. The steady state presents a strong decay of the perpendicular temperature of the electrons, whose profile versus the inverse of the magnetic field does not depend on the expansion rate within the quasi-neutral region. As a consequence, the electron distribution function is highly anisotropic downstream. The simulations revealed that the ions reach a higher velocity during the transient than in the steady state and their distribution functions are not far from mono-energetic. The density percentage of the population of electrons trapped during the transient, which is computed self-consistently by the code, is up to 25% of the total electron density in the quasi-neutral region. It is demonstrated that the exact amount depends on the history of the system and the steady state is not unique. Nevertheless, the amount of trapped electrons is smaller than the one assumed heuristically by kinetic stationary theories.

  17. METHOD AND APPARATUS FOR INJECTING AND TRAPPING ELECTRONS IN A MAGNETIC FIELD

    Science.gov (United States)

    Christofilos, N.C.

    1962-05-29

    An apparatus is designed for the manipulation of electrons in an exially symmetric magnetic field region and may be employed to trap electrons in such a field by directing an electron beam into a gradientially intensified field region therein to form an annular electron moving axially in the field and along a decreasing field gradient. Dissipative loop circuits such as resistive loops are disposed along at least the decreasing field gradient so as to be inductively coupled to the electron bunch so as to extract energy of the electron bunch and provide a braking force effective to reduce the velocity of the bunch. Accordingly, the electron bunch upon entering a lower intensity magnetic field region is retained therein since the electrons no longer possess sufficient energy to escape. (AEC)

  18. Trapped electron decay by the thermally-assisted tunnelling to electron acceptors in glassy matrices. A computer simulation study

    International Nuclear Information System (INIS)

    Feret, B.; Bartczak, W.M.; Kroh, J.

    1991-01-01

    The Redi-Hopefield quantum mechanical model of the thermally-assisted electron transfer has been applied to simulate the decay of trapped electrons by tunnelling to electron acceptor molecules added to the glassy matrix. It was assumed that the electron energy levels in donors and acceptors are statistically distributed and the electron excess energy after transfer is dissipated in the medium by the electron-phonon coupling. The electron decay curves were obtained by the method of computer simulation. It was found that for a given medium there exists a certain preferred value of the electronic excess energy which can be effectively converted into the matrix vibrations. If the mismatch of the electron states on the donor and acceptor coincides with the ''resonance'' energy the overall kinetics of electron transfer is accelerated. (author)

  19. Dynamic trapping of electrons in space plasmas

    International Nuclear Information System (INIS)

    Brenning, N.; Bohm, M.; Faelthammar, C.G.

    1989-12-01

    The neutralization of positive space charge is studied in a case where heavy positive ions are added to a limited region of length L in a collisionfree magnetized plasma. It is found that electrons which become accelerated towards the positive space charge can only achieve a partial neutralization: they overshoot, and the positive region becomes surrounded by negative space charges which screen the electric field from the surroundings. The process is studied both analytically and by computer simulations with consistent results: large positive potentials (U>>kT e /e) can be built up with respect to the surrounding plasma. In the process of growth, the potential maximum traps electrons in transit so that quasineutrality is maintained. The potential U is proportional to the ambient electron temperature and the square of the plasma density increase, but independent of both the ion injection rate and the length L. The process explains several features of the Porcupinge xenon beam injection experiment. It could also have importance for the electrodynamic coupling between plasmas of different densities, e.g. the injection of neutral clouds in the ionosphere of species that becomes rapidly photoionized, or penetration of dense plasma clouds from the solar wind into the magnetosphere. (31 refs.) (authors)

  20. Electron beam ion trap bi-annual report 1996/1997

    International Nuclear Information System (INIS)

    Schneider, D.

    1999-01-01

    The research of the EBIT (Electron Beam Ion Trap) program in N Division of the Physics and Space Technology Directorate at LLNL continues to contribute significantly to the understanding of physical processes with low energy highly charged ions in atomic physics, plasma physics, and material science. Low-energy highly charged ions (up to U 92+ ), provided by the EBIT facilities, provide a unique laboratory opportunity to study high field effects in atomic structures and dynamic interaction processes. The formation, existence, and structure of highly charged ions in astrophysical environments and laboratory plasmas make highly charged ions desirable for diagnosing various plasma conditions. The strong interaction of highly charged ions with matter and the response of solid surfaces make them a sensitive analysis tool and possibly a future capability for materials modifications at the atomic scale (nano technology). These physical applications require a good understanding and careful study of the dynamics of the interactions of the ions with complex systems. The EBIT group hosted an international conference and a workshop on trapped charged particles. The various talks and discussions showed that physics research with trapped charged particles is a very active and attractive area of innovative research, and provides a basis for research efforts in new areas. It also became obvious that the EBIT/RETRAP project has unique capabilities to perform important new experiments with trapped very highly charged ions at rest, which are complementary to and competitive with research at heavy ion storage rings and other trapping facilities planned or in operation in Europe, Japan, and the United States. Atomic structure research at EBIT provides ever better and more experimental complete benchmark data, supplying data needed to improve atomic theories. Research highlights through 1996 and 1997 include hyperfine structure measurements in H-like ions, QED studies, lifetime and

  1. A dominant electron trap in molecular beam epitaxial InAlN lattice-matched to GaN

    Science.gov (United States)

    Pandey, Ayush; Bhattacharya, Aniruddha; Cheng, Shaobo; Botton, Gianluigi A.; Mi, Zetian; Bhattacharya, Pallab

    2018-04-01

    Deep levels in lattice-matched undoped and Si-doped InAlN/GaN grown by plasma-assisted molecular beam epitaxy have been identified and characterized by capacitance and photocapacitance measurements. From x-ray diffraction, reflectance measurements, electron energy loss spectroscopy and high-resolution transmission electron microscopy it is evident that the material has two distinct phases with different compositions. These correspond to In compositions of 18.1% and 25.8%, with corresponding bandgaps of 4.6 eV and 4.1 eV, respectively. The lower bandgap material is present as columnar microstructures in the form of quantum wires. A dominant electron trap with an activation energy of 0.293  ±  0.01 eV, a small capture cross-section of (1.54  ±  0.25)  ×  10-18 cm2, and density increasing linearly with Si doping density is identified in all the samples. The characteristics of the electron trap and variation of diode capacitance are discussed in the context of carrier dynamics involving the dominant trap level and the quantum wires.

  2. Excitation transfer and trapping kinetics in plant photosystem I probed by two-dimensional electronic spectroscopy.

    Science.gov (United States)

    Akhtar, Parveen; Zhang, Cheng; Liu, Zhengtang; Tan, Howe-Siang; Lambrev, Petar H

    2018-03-01

    Photosystem I is a robust and highly efficient biological solar engine. Its capacity to utilize virtually every absorbed photon's energy in a photochemical reaction generates great interest in the kinetics and mechanisms of excitation energy transfer and charge separation. In this work, we have employed room-temperature coherent two-dimensional electronic spectroscopy and time-resolved fluorescence spectroscopy to follow exciton equilibration and excitation trapping in intact Photosystem I complexes as well as core complexes isolated from Pisum sativum. We performed two-dimensional electronic spectroscopy measurements with low excitation pulse energies to record excited-state kinetics free from singlet-singlet annihilation. Global lifetime analysis resolved energy transfer and trapping lifetimes closely matches the time-correlated single-photon counting data. Exciton energy equilibration in the core antenna occurred on a timescale of 0.5 ps. We further observed spectral equilibration component in the core complex with a 3-4 ps lifetime between the bulk Chl states and a state absorbing at 700 nm. Trapping in the core complex occurred with a 20 ps lifetime, which in the supercomplex split into two lifetimes, 16 ps and 67-75 ps. The experimental data could be modelled with two alternative models resulting in equally good fits-a transfer-to-trap-limited model and a trap-limited model. However, the former model is only possible if the 3-4 ps component is ascribed to equilibration with a "red" core antenna pool absorbing at 700 nm. Conversely, if these low-energy states are identified with the P 700 reaction centre, the transfer-to-trap-model is ruled out in favour of a trap-limited model.

  3. Electron spin-lattice relaxation mechanisms of radiation produced trapped electrons and hydrogen atoms in aqueous and organic glassy matrices. Modulation of electron nuclear dipolar interaction by tunnelling modes in a glassy matrix. [. gamma. rays

    Energy Technology Data Exchange (ETDEWEB)

    Bowman, M K; Kevan, L [Wayne State Univ., Detroit, Mich. (USA). Dept. of Chemistry

    1977-01-01

    The spin lattice relaxation of trapped electrons in aqueous and organic glasses and trapped hydrogen atoms in phosphoric acid glass has been directly studied as a function of temperature by the saturation recovery method. Below 50 to 100 K, the major spin lattice relaxation mechanism involves modulation of the electron nuclear dipolar (END) interaction with nuclei in the radical's environment by tunnelling of those nuclei between two or more positions. This relaxation mechanism occurs with high efficiency and has a characteristic linear temperature dependence. The tunnelling nuclei around trapped electrons do not seem to involve the nearest neighbor nuclei which are oriented by the electron in the process of solvation. Instead the tunnelling nuclei typically appear to be next nearest neighbors to the trapped electron. The identities of the tunnelling nuclei have been deduced by isotopic substitution and are attributed to: Na in 10 mol dm/sup -3/ NaOH aqueous glass, ethyl protons in ethanol glass, methyl protons in methanol glass and methyl protons in MTHF glass. For trapped hydrogen atoms in phosphoric acid, the phosphorus nuclei appear to be the effective tunnelling nuclei. Below approximately 10 K the spin lattice relaxation is dominated by a temperature independent cross relaxation term for H atoms in phosphoric acid glass and for electrons in 10 mol dm/sup -3/ NaOH aqueous glass, but not for electrons in organic glasses. This is compared with recent electron-electron double resonance studies of cross relaxation in these glasses. The spin lattice relaxation of O/sup -/ formed in 10 mol dm/sup -3/ NaOH aqueous glass was also studied and found to be mainly dominated by a Raman process with an effective Debye temperature of about 100 K.

  4. Deeply trapped electrons in imaging plates and their utilization for extending the dynamic range

    International Nuclear Information System (INIS)

    Ohuchi, Hiroko; Kondo, Yasuhiro

    2010-01-01

    The absorption spectra of deep centers in an imaging plate (IP) made of BaFBr 0:85 I 0:15 :Eu 2+ have been studied in the ultraviolet region. Electrons trapped in deep centers are considered to be the cause of unerasable and reappearing latent images in IPs over-irradiated with X-rays. Deep centers showed a dominant peak at around 320 nm, followed by two small peaks at around 345 and 380 nm. By utilizing deeply trapped electrons, we have attempted to extend the dynamic range of an IP. The IP was irradiated by 150-kV X-rays with doses from 8.07 mGy to 80.7 Gy. Reading out the latent image by the stimulation of Eu 2+ luminescence with a 633-nm He-Ne laser light from a conventional Fuji reader showed a linear relationship with irradiated dose up to 0.8 Gy, but then becoming non-linear. After fully erasing with visible light, unerasable latent images were read out using 635-nm semi-conductor laser light combined with a photon-counting detection system. The dose-response curve so obtained gave a further two orders of magnitude extending the dynamic range up to 80.7 Gy. Comprehensive results indicate that electrons supplied from deep centers to the F centers provided the extended dynamic range after the F centers became saturated. Based on these facts, a model of the excitation of deeply trapped electrons and PSL processes is proposed.

  5. Wavelength-selective bleaching of the optical spectra of trapped electrons in organic glasses. II

    International Nuclear Information System (INIS)

    Paraszczak, J.; Willard, J.E.

    1979-01-01

    Further resolution of the inhomogeneous optical spectra of trapped electrons (e - /sub t/) in organic glasses has been obtained from wavelength selective bleaching and thermal decay studies on 3-methylpentane-d 14 (3MP-d 14 ) and 2-methyltetrahydrofuran (MTHF) following γ irradiation in the temperature region of 20 K, and limits on the degree of resolution achievable have been indicated. Exposure of 3MP-d 14 to light of wavelengths >2100 nm (from a tunable laser) reduces the optical densities at the bleaching wavelength and longer to zero, while ''peeling off'' a portion of the O.D. at all shorter wavelengths but leaving the remainder of the spectrum unaffected. The fraction of the integrated optical spectrum, ∫OD d (eV), removed by bleaching at each wavelength tested, and also by thermal decay, is equivalent to the fraction of the total e - /sub t/ spins removed and measured by ESR. 1064 nm light bleaches the spectrum nearly uniformly, confirming that the spectra of all of the e - /sub t/ have blue tails with similar ease of bleaching. Heretofore unobserved low temperature thermal decay of e - /sub t/ occurs at 20 and 40 K (20% of the spin concentration in 30 min, 35% in 3h). The rate of decay of the optical spectrum decreases with decreasing wavelength of observation (2.5, 2.2, 1.8, and 1.5 μ), but at each wavelength is the same at 40 K as at 20 K, consistent

  6. Deuterium trapping at vacancy clusters in electron/neutron-irradiated tungsten studied by positron annihilation spectroscopy

    Science.gov (United States)

    Toyama, T.; Ami, K.; Inoue, K.; Nagai, Y.; Sato, K.; Xu, Q.; Hatano, Y.

    2018-02-01

    Deuterium trapping at irradiation-induced defects in tungsten, a candidate material for plasma facing components in fusion reactors, was revealed by positron annihilation spectroscopy. Pure tungsten was electron-irradiated (8.5 MeV at ∼373 K and to a dose of ∼1 × 10-3 dpa) or neutron-irradiated (at 573 K to a dose of ∼0.3 dpa), followed by post-irradiation annealing at 573 K for 100 h in deuterium gas of ∼0.1 MPa. In both cases of electron- or neutron-irradiation, vacancy clusters were found by positron lifetime measurements. In addition, positron annihilation with deuterium electrons was demonstrated by coincidence Doppler broadening measurements, directly indicating deuterium trapping at vacancy-type defects. This is expected to cause significant increase in deuterium retention in irradiated-tungsten.

  7. THE POSSIBLE ROLE OF CORONAL STREAMERS AS MAGNETICALLY CLOSED STRUCTURES IN SHOCK-INDUCED ENERGETIC ELECTRONS AND METRIC TYPE II RADIO BURSTS

    Energy Technology Data Exchange (ETDEWEB)

    Kong, Xiangliang; Chen, Yao; Feng, Shiwei; Wang, Bing; Du, Guohui [Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, and Institute of Space Sciences, Shandong University, Weihai, Shandong 264209 (China); Guo, Fan [Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Li, Gang, E-mail: yaochen@sdu.edu.cn [Department of Space Science and CSPAR, University of Alabama in Huntsville, Huntsville, AL 35899 (United States)

    2015-01-10

    Two solar type II radio bursts, separated by ∼24 hr in time, are examined together. Both events are associated with coronal mass ejections (CMEs) erupting from the same active region (NOAA 11176) beneath a well-observed helmet streamer. We find that the type II emissions in both events ended once the CME/shock fronts passed the white-light streamer tip, which is presumably the magnetic cusp of the streamer. This leads us to conjecture that the closed magnetic arcades of the streamer may play a role in electron acceleration and type II excitation at coronal shocks. To examine such a conjecture, we conduct a test-particle simulation for electron dynamics within a large-scale partially closed streamer magnetic configuration swept by a coronal shock. We find that the closed field lines play the role of an electron trap via which the electrons are sent back to the shock front multiple times and therefore accelerated to high energies by the shock. Electrons with an initial energy of 300 eV can be accelerated to tens of keV concentrating at the loop apex close to the shock front with a counter-streaming distribution at most locations. These electrons are energetic enough to excite Langmuir waves and radio bursts. Considering the fact that most solar eruptions originate from closed field regions, we suggest that the scenario may be important for the generation of more metric type IIs. This study also provides an explanation of the general ending frequencies of metric type IIs at or above 20-30 MHz and the disconnection issue between metric and interplanetary type IIs.

  8. Second generation measurement of the electric dipole moment of the electron using trapped ThF+ ions

    Science.gov (United States)

    Ng, Kia Boon; Zhou, Yan; Gresh, Daniel; Cairncross, William; Grau, Matthew; Ni, Yiqi; Ye, Jun; Cornell, Eric

    2016-05-01

    ThF+ has been chosen as the candidate for a second generation measurement of the electric dipole moment of the electron (eEDM). Compared to the current HfF+ eEDM experiment, ThF+ has several advantages: (i) the eEDM-sensitive state (3Δ1) is the ground state, which facilitates a long coherence time; (ii) its effective electric field (38 GV/cm) is 50% larger than that of HfF+, which promises a direct increase of the eEDM sensitivity; and (iii) the ionization energy of neutral ThF is lower than its dissociation energy, which introduces greater flexibility in rotational state-selective photoionization via core-nonpenetrating Rydberg states. Here, we present progress of our experimental setup, preliminary spectroscopic data of multi-photon ionization, and discussions of new features in ion trapping, state preparation and population readout.

  9. Relaxation oscillations induced by amplitude-dependent frequency in dissipative trapped electron mode turbulence

    International Nuclear Information System (INIS)

    Terry, P.W.; Ware, A.S.; Newman, D.E.

    1994-01-01

    A nonlinear frequency shift in dissipative trapped electron mode turbulence is shown to give rise to a relaxation oscillation in the saturated power density spectrum. A simple non-Markovian closure for the coupled evolution of ion momentum and electron density response is developed to describe the oscillations. From solutions of a nonlinear oscillator model based on the closure, it is found that the oscillation is driven by the growth rate, as modified by the amplitude-dependent frequency shift, with inertia provided by the memory of the growth rate of prior amplitudes. This memory arises from time-history integrals common to statistical closures. The memory associated with a finite time of energy transfer between coupled spectrum components does not sustain the oscillation in the simple model. Solutions of the model agree qualitatively with the time-dependent numerical solutions of the original dissipative trapped electron model, yielding oscillations with the proper phase relationship between the fluctuation energy and the frequency shift, the proper evolution of the wave number spectrum shape and particle flux, and a realistic period

  10. Detection of electron and hole traps in CdZnTe radiation detectors by thermoelectric emission spectroscopy and thermally stimulated conductivity

    International Nuclear Information System (INIS)

    Lee, E.Y.; Brunett, B.A.; Olsen, R.W.; Van Scyoc, J.M. III; Hermon, H.; James, R.B.

    1998-01-01

    The electrical properties of CdZnTe radiation detectors are largely determined by electron and hole traps in this material. The traps, in addition to degrading the detector performance, can function as dopants and determine the resistivity of the material. Thermoelectric emission spectroscopy and thermally stimulated conductivity are used to detect these traps in a commercially available spectrometer-grade CdZnTe detector, and the electrical resistivity is measured as a function of temperature. A deep electron trap having an energy of 695 meV and cross section of 8 x 10 -16 cm 2 is detected and three hole traps having energies of 70 ± 20 meV, 105 ± 30 meV and 694 ± 162 meV are detected. A simple model based on these traps explains quantitatively all the data, including the electrical properties at room temperature and also their temperature dependence

  11. First experiments with the Greifswald electron-beam ion trap

    Science.gov (United States)

    Schabinger, B.; Biedermann, C.; Gierke, S.; Marx, G.; Radtke, R.; Schweikhard, L.

    2013-09-01

    The former Berlin electron-beam ion trap (EBIT) was moved to Greifswald. In addition to x-ray studies the setup will be used for the investigation of interaction processes between highly charged ions and atomic clusters such as charge exchange and fragmentation. The EBIT setup has now been reassembled and highly charged ions have been produced from Xe-Ar gas mixtures to study the ‘sawtooth effect’. In addition, the layout of the extraction beamline, the interaction region and product analysis for interaction studies with highly charged ions are presented.

  12. Electron trapping in the electrosound solitary wave for propagation of high intensity laser in a relativistic plasma

    International Nuclear Information System (INIS)

    Heidari, E; Aslaninejad, M; Eshraghi, H

    2010-01-01

    Using a set of relativistic equations for plasmas with warm electrons and cold ions, we have investigated the effects of trapped electrons in the propagation of an electrosound wave and discussed the possibility of the formation of electromagnetic solitons in a plasma. The effective potential energy and deviations of the electron and ion number densities in this relativistic model have been found. We have obtained the governing equations for the amplitude of the HF field with relativistic corrections. In order to show the destructive impact of the trapped electrons on the solitary wave, a relativistic effective potential and the governing equation have been found. It is shown that for certain values of the parameters the condition of localization of the HF amplitude is violated. In addition, it is shown that as the flow velocity of the plasma changes, the shape of the solitary wave shows two opposing behaviours, depending on whether the solitary wave velocity is larger than the flow velocity or smaller. Also, the existence of stationary solitary waves which are prohibited for nonrelativistic plasma has been predicted. Finally, we have obtained the Korteweg-de Vries equation showing the relativistic, trapping and nonlinearity effects.

  13. Design and Fabrication of Cryostat Interface and Electronics for High Performance Antimatter Trap (HI-PAT)

    Science.gov (United States)

    Smith, Gerald A.

    1999-01-01

    Included in Appendix I to this report is a complete set of design and assembly schematics for the high vacuum inner trap assembly, cryostat interfaces and electronic components for the MSFC HI-PAT. Also included in the final report are summaries of vacuum tests, and electronic tests performed upon completion of the assembly.

  14. Crystal step edges can trap electrons on the surfaces of n-type organic semiconductors.

    Science.gov (United States)

    He, Tao; Wu, Yanfei; D'Avino, Gabriele; Schmidt, Elliot; Stolte, Matthias; Cornil, Jérôme; Beljonne, David; Ruden, P Paul; Würthner, Frank; Frisbie, C Daniel

    2018-05-30

    Understanding relationships between microstructure and electrical transport is an important goal for the materials science of organic semiconductors. Combining high-resolution surface potential mapping by scanning Kelvin probe microscopy (SKPM) with systematic field effect transport measurements, we show that step edges can trap electrons on the surfaces of single crystal organic semiconductors. n-type organic semiconductor crystals exhibiting positive step edge surface potentials display threshold voltages that increase and carrier mobilities that decrease with increasing step density, characteristic of trapping, whereas crystals that do not have positive step edge surface potentials do not have strongly step density dependent transport. A device model and microelectrostatics calculations suggest that trapping can be intrinsic to step edges for crystals of molecules with polar substituents. The results provide a unique example of a specific microstructure-charge trapping relationship and highlight the utility of surface potential imaging in combination with transport measurements as a productive strategy for uncovering microscopic structure-property relationships in organic semiconductors.

  15. Extreme ultra-violet emission spectroscopy of highly charged gadolinium ions with an electron beam ion trap

    International Nuclear Information System (INIS)

    Ohashi, Hayato; Nakamura, Nobuyuki; Sakaue, Hiroyuki A

    2013-01-01

    We present extreme ultra-violet emission spectra of highly charged gadolinium ions obtained with an electron beam ion trap at electron energies of 0.53–1.51 keV. The electron energy dependence of the spectra in the 5.7–11.3 nm range is compared with calculation with the flexible atomic code. (paper)

  16. Nonextensive statistical mechanics approach to electron trapping in degenerate plasmas

    Science.gov (United States)

    Mebrouk, Khireddine; Gougam, Leila Ait; Tribeche, Mouloud

    2016-06-01

    The electron trapping in a weakly nondegenerate plasma is reformulated and re-examined by incorporating the nonextensive entropy prescription. Using the q-deformed Fermi-Dirac distribution function including the quantum as well as the nonextensive statistical effects, we derive a new generalized electron density with a new contribution proportional to the electron temperature T, which may dominate the usual thermal correction (∼T2) at very low temperatures. To make the physics behind the effect of this new contribution more transparent, we analyze the modifications arising in the propagation of ion-acoustic solitary waves. Interestingly, we find that due to the nonextensive correction, our plasma model allows the possibility of existence of quantum ion-acoustic solitons with velocity higher than the Fermi ion-sound velocity. Moreover, as the nonextensive parameter q increases, the critical temperature Tc beyond which coexistence of compressive and rarefactive solitons sets in, is shifted towards higher values.

  17. Two-dimensional spatial structure of the dissipative trapped-electron mode

    International Nuclear Information System (INIS)

    Rewoldt, G.; Tang, W.M.; Frieman, E.A.

    1976-09-01

    This paper deals with the complete two-dimensional structure of the dissipative trapped-electron mode over its full width, which may extend over several mode-rational surfaces. The complete integro-differential equation is studied in the limit k/sub r/rho/sub i/ less than 1, where rho/sub i/ is the ion gyroradius, and k/sub r/, the radial wavenumber, is regarded as a differential operator. This is converted into a matrix equation which is then solved by standard numerical methods

  18. Kβ spectra of heliumlike chromium from an electron-beam ion trap

    International Nuclear Information System (INIS)

    Decaux, V.; Beiersdorfer, P.; Elliott, S.; Osterheld, A.

    1993-01-01

    Kβ spectra of heliumlike chromium have been recorded using the Livermore electron-beam ion trap (EBIT) with a high-resolution Bragg crystal spectrometer in the von Hamos configuration, in the wavelong range from 1.870 Angstrom. Measurements have been made both for direct excitation at an electron beam energy of 8 k and dielectronic recombination around the KLM resonance energy of 5 keV. In order to evaluate the resonance strength the lithiumlike dielectronic satellites, we used a data routine technique to accumulate spectra at 15 different beam energies between 4.96 and 5.28 keV. Results are compared to theoretical calculations using the multiconfiguration parametric potential method

  19. Computation of transverse muon-spin relaxation functions including trapping-detrapping reactions, with application to electron-irradiated tantalum

    International Nuclear Information System (INIS)

    Doering, K.P.; Aurenz, T.; Herlach, D.; Schaefer, H.E.; Arnold, K.P.; Jacobs, W.; Orth, H.; Haas, N.; Seeger, A.; Max-Planck-Institut fuer Metallforschung, Stuttgart

    1986-01-01

    A new technique for the economical evaluation of transverse muon spin relaxation functions in situations involving μ + trapping at and detrapping from crystal defects is applied to electron-irradiated Ta exhibiting relaxation maxima at about 35 K, 100 K, and 250 K. The long-range μ + diffusion is shown to be limted by traps over the entire temperature range investigated. The (static) relaxation rates for several possible configurations of trapped muons are discussed, including the effect of the simultaneous presence of a proton in a vacancy. (orig.)

  20. ELECTRON ACCELERATION BY CASCADING RECONNECTION IN THE SOLAR CORONA. II. RESISTIVE ELECTRIC FIELD EFFECTS

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, X.; Gan, W.; Liu, S. [Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China); Büchner, J.; Bárta, M., E-mail: zhou@mps.mpg.de, E-mail: liusm@pmo.ac.cn, E-mail: buechner@mps.mpg.de [Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, D-37077 Göttingen (Germany)

    2016-08-20

    We investigate electron acceleration by electric fields induced by cascading reconnections in current sheets trailing coronal mass ejections via a test particle approach in the framework of the guiding-center approximation. Although the resistive electric field is much weaker than the inductive electric field, the electron acceleration is still dominated by the former. Anomalous resistivity η is switched on only in regions where the current carrier’s drift velocity is large enough. As a consequence, electron acceleration is very sensitive to the spatial distribution of the resistive electric fields, and electrons accelerated in different segments of the current sheet have different characteristics. Due to the geometry of the 2.5-dimensional electromagnetic fields and strong resistive electric field accelerations, accelerated high-energy electrons can be trapped in the corona, precipitating into the chromosphere or escaping into interplanetary space. The trapped and precipitating electrons can reach a few MeV within 1 s and have a very hard energy distribution. Spatial structure of the acceleration sites may also introduce breaks in the electron energy distribution. Most of the interplanetary electrons reach hundreds of keV with a softer distribution. To compare with observations of solar flares and electrons in solar energetic particle events, we derive hard X-ray spectra produced by the trapped and precipitating electrons, fluxes of the precipitating and interplanetary electrons, and electron spatial distributions.

  1. Dissipative dust-acoustic shock waves in a varying charge electronegative magnetized dusty plasma with trapped electrons

    Energy Technology Data Exchange (ETDEWEB)

    Bacha, Mustapha [Faculty of Physics, Theoretical Physics Laboratory, Plasma Physics Group, University of Bab-Ezzouar, USTHB, B.P. 32, El Alia, Algiers 16111 (Algeria); Tribeche, Mouloud, E-mail: mouloudtribeche@yahoo.fr, E-mail: mtribeche@usthb.dz [Faculty of Physics, Theoretical Physics Laboratory, Plasma Physics Group, University of Bab-Ezzouar, USTHB, B.P. 32, El Alia, Algiers 16111 (Algeria); Algerian Academy of Sciences and Technologies, Algiers (Algeria)

    2016-08-15

    The combined effects of an oblique magnetic field and electron trapping on dissipative dust-acoustic waves are examined in varying charge electronegative dusty plasmas with application to the Halley Comet plasma (∼10{sup 4} km from the nucleus). A weakly nonlinear analysis is carried out to derive a modified Korteweg-de Vries-Burger-like equation. Making use of the equilibrium current balance equation, the physically admissible values of the electron trapping parameter are first constrained. We then show that the Burger dissipative term is solely due to the dust charge variation process. It is found that an increase of the magnetic field obliqueness or a decrease of its magnitude renders the shock structure more dispersive.

  2. Spectroscopy with trapped highly charged ions

    International Nuclear Information System (INIS)

    Beiersdorfer, Peter

    2009-01-01

    We give an overview of atomic spectroscopy performed on electron beam ion traps at various locations throughout the world. Spectroscopy at these facilities contributes to various areas of science and engineering, including but not limited to basic atomic physics, astrophysics, extreme ultraviolet lithography, and the development of density and temperature diagnostics of fusion plasmas. These contributions are accomplished by generating, for example, spectral surveys, making precise radiative lifetime measurements, accounting for radiative power emitted in a given wavelength band, illucidating isotopic effects, and testing collisional-radiative models. While spectroscopy with electron beam ion traps had originally focused on the x-ray emission from highly charged ions interacting with the electron beam, the operating modes of such devices have expanded to study radiation in almost all wavelength bands from the visible to the hard x-ray region; and at several facilities the ions can be studied even in the absence of an electron beam. Photon emission after charge exchange or laser excitation has been observed; and the work is no longer restricted to highly charged ions. Much of the experimental capabilities are unique to electron beam ion traps, and the work performed with these devices cannot be undertaken elsewhere. However, in other areas the work on electron beam ion traps rivals the spectroscopy performed with conventional ion traps or heavy-ion storage rings. The examples we present highlight many of the capabilities of the existing electron beam ion traps and their contributions to physics.

  3. Phase-Space Density Analysis of the AE-8 Traped Electron and the AP-8 Trapped Proton Model Environments

    Energy Technology Data Exchange (ETDEWEB)

    Thomas E. Cayton

    2005-08-01

    The AE-8 trapped electron and the AP-8 trapped proton models are used to examine the L-shell variation of phase-space densities for sets of transverse (or 1st) invariants, {mu}, and geometrical invariants, K (related to the first two adiabatic invariants). The motivation for this study is twofold: first, to discover the functional dependence of the phase-space density upon the invariants; and, second, to explore the global structure of the radiation belts within this context. Variation due to particle rest mass is considered as well. The overall goal of this work is to provide a framework for analyzing energetic particle data collected by instruments on Global Positioning System (GPS) spacecraft that fly through the most intense region of the radiation belt. For all considered values of {mu} and K, and for 3.5 R{sub E} < L < 6.5 R{sub E}, the AE-8 electron phase-space density increases with increasing L; this trend--the expected one for a population diffusing inward from an external source--continues to L = 7.5 R{sub E} for both small and large values of K but reverses slightly for intermediate values of K. The AP-8 proton phase-space density exhibits {mu}-dependent local minima around L = 5 R{sub E}. Both AE-8 and AP-8 exhibit critical or cutoff values for the invariants beyond which the flux and therefore the phase-space density vanish. For both electrons and protons, these cutoff values vary systematically with magnetic moment and L-shell and are smaller than those estimated for the atmospheric loss cone. For large magnetic moments, for both electrons and protons, the K-dependence of the phase-space density is exponential, with maxima at the magnetic equator (K = 0) and vanishing beyond a cutoff value, K{sub c}. Such features suggest that momentum-dependent trapping boundaries, perhaps drift-type loss cones, serve as boundary conditions for trapped electrons as well as trapped protons.

  4. EPR study of electron traps in x-ray-irradiated yttria-stabilized zirconia

    International Nuclear Information System (INIS)

    Azzoni, C.B.; Paleari, A.

    1989-01-01

    Single crystals of yttria-stabilized zirconia (12 mol % of Y 2 O 3 ) have been x-ray irradiated at room temperature. The electron paramagnetic resonance spectrum of the filled electron traps is analyzed in terms of a single oxygen vacancy type of defect with its symmetry axis along the left-angle 111 right-angle direction. The angular dependence of the linewidth and the asymmetry of the line shape are attributed to the disordered rearrangements of the anion sublattice surrounding the oxygen vacancy. This affects the local crystal fields and the directions of the symmetry axis of the defects

  5. EPR study of electron traps in x-ray-irradiated yttria-stabilized zirconia

    Energy Technology Data Exchange (ETDEWEB)

    Azzoni, C.B.; Paleari, A. (Dipartimento di Fisica, Alessandro Volta dell' Universita di Pavia, via Bassi 6, 27100 Pavia, Italy (IT))

    1989-10-01

    Single crystals of yttria-stabilized zirconia (12 mol % of Y{sub 2}O{sub 3}) have been x-ray irradiated at room temperature. The electron paramagnetic resonance spectrum of the filled electron traps is analyzed in terms of a single oxygen vacancy type of defect with its symmetry axis along the {l angle}111{r angle} direction. The angular dependence of the linewidth and the asymmetry of the line shape are attributed to the disordered rearrangements of the anion sublattice surrounding the oxygen vacancy. This affects the local crystal fields and the directions of the symmetry axis of the defects.

  6. Trapping and Evolution Dynamics of Ultracold Two-Component Plasmas

    International Nuclear Information System (INIS)

    Choi, J.-H.; Knuffman, B.; Zhang, X. H.; Povilus, A. P.; Raithel, G.

    2008-01-01

    We demonstrate the trapping of a strongly magnetized, quasineutral ultracold plasma in a nested Penning trap with a background field of 2.9 T. Electrons remain trapped in this system for several milliseconds. Early in the evolution, the dynamics are driven by a breathing-mode oscillation in the ionic charge distribution, which modulates the electron trap depth. Over longer times scales, the electronic component undergoes cooling. Trap loss resulting from ExB drift is characterized

  7. Study of the motion of electrons in non polar classical liquids. Measurement of Hall effect and f.i.r. search for low energy traps. Progress report

    International Nuclear Information System (INIS)

    1981-01-01

    Progress is reported on experiments aimed at the measurement of the Hall mobility of injected electrons in classical non polar insulating liquids and the optical absorption associated with electrons captured by shallow traps in the liquefied rare gases. Theoretical work aimed at a better understanding of the trapping kinetics of electrons by SF 6 and O 2 dissolved in rare gas liquids was also carried out. Its conclusion is that the electric field dependence of the trapping probability can be explained, basically without adjustable parameters, by considering the Poole-Frenkel-Schotky ionization of the excited state of the traps. From the analysis of published data on the motion of electrons in liquid ethane it is tentatively concluded that at low temperatures the trapping of electrons in the liquid involves a Jahn-Teller like distortion of a single ethane molecule while at higher temperatures it is necessary to consider a small molecular cluster, possibly made up of 2 molecules

  8. Experimental evaluation of quantum computing elements (qubits) made of electrons trapped over a liquid helium film; Evaluation experimentale d'elements de calcul quantique (qubit) formes d'electrons pieges sur l'helium liquide

    Energy Technology Data Exchange (ETDEWEB)

    Rousseau, E

    2006-12-15

    An electron on helium presents a quantized energy spectrum. The interaction with the environment is considered sufficiently weak in order to allow the realization of a quantum bit (qubit) by using the first two energy levels. The first stage in the realization of this qubit was to trap and control a single electron. This is carried out thanks to a set of micro-fabricated electrodes defining a well of potential in which the electron is trapped. We are able with such a sample to trap and detect a variables number of electrons varying between one and around twenty. This then allowed us to study the static behaviour of a small number of electrons in a trap. They are supposed to crystallize and form structures called Wigner molecules. Such molecules have not yet been observed yet with electrons above helium. Our results bring circumstantial evidence for of Wigner crystallization. We then sought to characterize the qubit more precisely. We sought to carry out a projective reading (depending on the state of the qubit) and a measurement of the relaxation time. The results were obtained by exciting the electron with an incoherent electric field. A clean measurement of the relaxation time would require a coherent electric field. The conclusion cannot thus be final but it would seem that the relaxation time is shorter than calculated theoretically. That is perhaps due to a measurement of the relaxation between the oscillating states in the trap and not between the states of the qubit. (author)

  9. The effects of electron spiraling on the anisotropy and polarization of photon emission from an electron beam ion trap

    International Nuclear Information System (INIS)

    Savin, D.W.; Gu, M.F.; Beiersdorfer, P.

    1998-01-01

    We present a theoretical formalism for calculating the anisotropy and polarization of photon emission due to a spiraling beam of electrons in an electron beam ion trap (EBIT). We present measurements of the polarization for the Fe XXIV 4p 2 P 3/2 → 2s 2 S 1/2 X-ray transition due to electron impact excitation. We discuss these results, together with previously reported EBIT polarization measurements, in the light of electron spiraling. We find that spiraling effects cannot yet be discerned in these measurements. This is important for many EBIT measurements concerned with X-ray line intensity measurements. While the amount of spiraling is not accurately known, neglecting its effects introduces an error typically no larger than that given by counting statistics. (author)

  10. Luminescence and photothermally stimulated defects creation processes in PbWO4:La3+, Y3+ (PWO II) crystals

    International Nuclear Information System (INIS)

    Auffray, E.; Korjik, M.; Zazubovich, S.

    2015-01-01

    Photoluminescence and thermally stimulated luminescence (TSL) are studied for a PbWO 4 crystal grown by the Czochralski method at Bogoroditsk Technical Chemical Plant, Russia from the melt with a precise tuning of the stoichiometry and co-doped with La 3+ and Y 3+ ions (the PWO II crystal). Photothermally stimulated processes of electron and hole centers creation under selective UV irradiation of this crystal in the 3.5–5.0 eV energy range and the 85–205 K temperature range are clarified and the optically created electron and hole centers are identified. The electrons in PWO II are mainly trapped at the (WO 4 ) 2− groups located close to single La 3+ and Y 3+ ions, producing the electron {(WO 4 ) 3− –La 3+ } and {(WO 4 ) 3− –Y 3+ } centers. The holes are mainly trapped at the regular oxygen ions O 2− located close to La 3+ and Y 3+ ions associated with lead vacancies, producing the hole O − (I)-type centers. No evidence of single-vacancy-related centers has been observed in PWO II. The data obtained indicate that excellent scintillation characteristics of the PWO II crystal can be explained by a negligible concentration of single (non-compensated) oxygen and lead vacancies as the traps for electrons and holes, respectively. - Highlights: • Photoluminescence of the PbWO 4 :La 3+ , Y 3+ (PWO II) crystal is investigated. • Creation of defects under UV irradiation of PWO II is studied by TSL. • Origin of dominating electron and hole centers is ascertained. • Concentration of single-vacancy-related centers is found to be negligible. • Excellent scintillation characteristics of the PWO II crystal are explained.

  11. Towards a Measurement of the n=2 Lamb Shift in Hydrogen-like Nitrogen Using an Electron Beam Ion Trap

    International Nuclear Information System (INIS)

    Hosaka, K.; Crosby, D. N.; Gaarde-Widdowson, K.; Smith, C. J.; Silver, J. D.; Myers, E. G.; Kinugawa, T.; Ohtani, S.

    2003-01-01

    Using a 14 C 16 O 2 laser the 2s 1/2 -2p 3/2 (fine structure - Lamb shift) transition has been induced in 14 N 6+ ions trapped in an electron beam ion trap. Prospects for a measurement of the Lamb shift in hydrogen-like nitrogen are discussed.

  12. On the correct implementation of Fermi-Dirac statistics and electron trapping in nonlinear electrostatic plane wave propagation in collisionless plasmas

    Science.gov (United States)

    Schamel, Hans; Eliasson, Bengt

    2016-05-01

    Quantum statistics and electron trapping have a decisive influence on the propagation characteristics of coherent stationary electrostatic waves. The description of these strictly nonlinear structures, which are of electron hole type and violate linear Vlasov theory due to the particle trapping at any excitation amplitude, is obtained by a correct reduction of the three-dimensional Fermi-Dirac distribution function to one dimension and by a proper incorporation of trapping. For small but finite amplitudes, the holes become of cnoidal wave type and the electron density is shown to be described by a ϕ ( x ) 1 / 2 rather than a ϕ ( x ) expansion, where ϕ ( x ) is the electrostatic potential. The general coefficients are presented for a degenerate plasma as well as the quantum statistical analogue to these steady state coherent structures, including the shape of ϕ ( x ) and the nonlinear dispersion relation, which describes their phase velocity.

  13. Midgap traps related to compensation processes in CdTe alloys

    International Nuclear Information System (INIS)

    Castaldini, A.; Cavallini, A.; Fraboni, B.; Fernandez, P.; Piqueras, J.

    1997-01-01

    We study, by cathodoluminescence and junction spectroscopy methods, the deep traps located near midgap in semiconducting and semi-insulating II-VI compounds, namely, undoped CdTe, CdTe:Cl, and Cd 0.8 Zn 0.2 Te. In order to understand the role such deep levels play in the control of the electrical properties of the material, it appears necessary to determine their character, donor, or acceptor, in addition to their activation energy and capture cross section. Photoinduced-current transient spectroscopy and photo deep-level transient spectroscopy are used to investigate the semi-insulating (SI) samples, and a comparison of the complementary results obtained allows us to identify an acceptor trap, labeled H, and an electron trap, labeled E. Level H is common to all investigated compounds, while E is present only in CdTe:Cl samples. This provides clear experimental evidence of the presence of a deep trap in CdTe:Cl, which could be a good candidate for the deep donor level needed to explain the compensation process of SI CdTe:Cl. copyright 1997 The American Physical Society

  14. Influence of the shear flow on electron cyclotron resonance plasma confinement in an axisymmetric magnetic mirror trap of the electron cyclotron resonance ion source.

    Science.gov (United States)

    Izotov, I V; Razin, S V; Sidorov, A V; Skalyga, V A; Zorin, V G; Bagryansky, P A; Beklemishev, A D; Prikhodko, V V

    2012-02-01

    Influence of shear flows of the dense plasma created under conditions of the electron cyclotron resonance (ECR) gas breakdown on the plasma confinement in the axisymmetric mirror trap ("vortex" confinement) was studied experimentally and theoretically. A limiter with bias potential was set inside the mirror trap for plasma rotation. The limiter construction and the optimal value of the potential were chosen according to the results of the preliminary theoretical analysis. This method of "vortex" confinement realization in an axisymmetric mirror trap for non-equilibrium heavy-ion plasmas seems to be promising for creation of ECR multicharged ion sources with high magnetic fields, more than 1 T.

  15. Influence of the shear flow on electron cyclotron resonance plasma confinement in an axisymmetric magnetic mirror trap of the electron cyclotron resonance ion source

    International Nuclear Information System (INIS)

    Izotov, I. V.; Razin, S. V.; Sidorov, A. V.; Skalyga, V. A.; Zorin, V. G.; Bagryansky, P. A.; Beklemishev, A. D.; Prikhodko, V. V.

    2012-01-01

    Influence of shear flows of the dense plasma created under conditions of the electron cyclotron resonance (ECR) gas breakdown on the plasma confinement in the axisymmetric mirror trap (''vortex'' confinement) was studied experimentally and theoretically. A limiter with bias potential was set inside the mirror trap for plasma rotation. The limiter construction and the optimal value of the potential were chosen according to the results of the preliminary theoretical analysis. This method of ''vortex'' confinement realization in an axisymmetric mirror trap for non-equilibrium heavy-ion plasmas seems to be promising for creation of ECR multicharged ion sources with high magnetic fields, more than 1 T.

  16. A Collapsin Response Mediator Protein 2 Isoform Controls Myosin II-Mediated Cell Migration and Matrix Assembly by Trapping ROCK II

    Science.gov (United States)

    Morgan-Fisher, Marie; Wait, Robin; Couchman, John R.; Wewer, Ulla M.

    2012-01-01

    Collapsin response mediator protein 2 (CRMP-2) is known as a regulator of neuronal polarity and differentiation through microtubule assembly and trafficking. Here, we show that CRMP-2 is ubiquitously expressed and a splice variant (CRMP-2L), which is expressed mainly in epithelial cells among nonneuronal cells, regulates myosin II-mediated cellular functions, including cell migration. While the CRMP-2 short form (CRMP-2S) is recognized as a substrate of the Rho-GTP downstream kinase ROCK in neuronal cells, a CRMP-2 complex containing 2L not only bound the catalytic domain of ROCK II through two binding domains but also trapped and inhibited the kinase. CRMP-2L protein levels profoundly affected haptotactic migration and the actin-myosin cytoskeleton of carcinoma cells as well as nontransformed epithelial cell migration in a ROCK activity-dependent manner. Moreover, the ectopic expression of CRMP-2L but not -2S inhibited fibronectin matrix assembly in fibroblasts. Underlying these responses, CRMP-2L regulated the kinase activity of ROCK II but not ROCK I, independent of GTP-RhoA levels. This study provides a new insight into CRMP-2 as a controller of myosin II-mediated cellular functions through the inhibition of ROCK II in nonneuronal cells. PMID:22431514

  17. Bias dependent charge trapping in MOSFETs during 1 and 6 MeV electron irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Shinde, N.S. [Department of Chemical Engineering, Mie University, 5148507 (Japan); Kulkarni, V.R.; Mathakari, N.L.; Bhoraskar, V.N. [Department of Physics, Univeristy of Pune, Pune 411007 (India); Dhole, S.D. [Department of Physics, Univeristy of Pune, Pune 411007 (India)], E-mail: sanjay@physics.unipune.ernet.in

    2008-06-15

    To study irradiation-induced charge trapping in SiO{sub 2} and around the SiO{sub 2}-Si interface, depletion n-MOSFETs (metal-oxide-semiconductor field effect transistor) were used. The devices were gate biased during 1 and 6 MeV pulsed electron irradiation. The I{sub D}-V{sub DS} (drain current versus drain voltage) and I{sub D}-V{sub GS} (drain current versus gate voltage) characteristics were measured before and after irradiation. The shift in threshold voltage {delta}V{sub T} (difference in threshold voltage V{sub T} before and after irradiation) exhibited trends depending on the applied gate bias during 1 MeV electron irradiation. This behavior can be associated to the contribution of irradiation-induced negative charge {delta}N{sub IT} buildup around the SiO{sub 2}-Si interface to {delta}V{sub T}, which is sensitive to the electron tunneling from the substrates. However, only weak gate bias dependence was observed in 6 MeV electron irradiated devices. Independent of the energy loss and applied bias, the positive oxide trapped charge {delta}N{sub OT} is marginal and can be associated to thin and good quality of SiO{sub 2}. These results are explained using screening of free and acceptor states by the applied bias during irradiation, thereby reducing the total irradiation-induced charges.

  18. A Statistical Analysis of Langmuir Wave-Electron Correlations Observed by the CHARM II Auroral Sounding Rocket

    Science.gov (United States)

    Dombrowski, M. P.; Labelle, J. W.; Kletzing, C.; Bounds, S. R.; Kaeppler, S. R.

    2014-12-01

    Langmuir-mode electron plasma waves are frequently observed by spacecraft in active plasma environments such as the ionosphere. Ionospheric Langmuir waves may be excited by the bump-on-tail instability generated by impinging beams of electrons traveling parallel to the background magnetic field (B). The Correlation of High-frequencies and Auroral Roar Measurement (CHARM II) sounding rocket was launched into a substorm at 9:49 UT on 17 February 2010, from the Poker Flat Research Range in Alaska. The primary instruments included the University of Iowa Wave-Particle Correlator (WPC), the Dartmouth High-Frequency Experiment (HFE), several charged particle detectors, low-frequency wave instruments, and a magnetometer. The HFE is a receiver system which effectively yields continuous (100% duty cycle) electric-field waveform measurements from 100 kHz to 5 MHz, and which had its detection axis aligned nominally parallel to B. The HFE output was fed on-payload to the WPC, which uses a phase-locked loop to track the incoming wave frequency with the most power, then sorting incoming electrons at eight energy levels into sixteen wave-phase bins. CHARM II encountered several regions of strong Langmuir wave activity throughout its 15-minute flight, and the WPC showed wave-lock and statistically significant particle correlation distributions during several time periods. We show results of an in-depth analysis of the CHARM II WPC data for the entire flight, including statistical analysis of correlations which show evidence of direct interaction with the Langmuir waves, indicating (at various times) trapping of particles and both driving and damping of Langmuir waves by particles. In particular, the sign of the gradient in particle flux appears to correlate with the phase relation between the electrons and the wave field, with possible implications for the wave physics.

  19. Detection and characterisation of radicals using electron paramagnetic resonance (EPR) spin trapping and related methods

    DEFF Research Database (Denmark)

    Davies, Michael Jonathan

    2016-01-01

    Electron paramagnetic resonance (EPR) spectroscopy (also known as electron spin resonance, ESR, or electron magnetic resonance, EMR, spectroscopy) is often described as the “gold standard” for the detection and characterisation of radicals in chemical, biological and medical systems. The article...... reviews aspects of EPR spectroscopy and discusses how this methodology and related techniques can be used to obtain useful information from biological systems. Consideration is given to the direct detection of radicals, the use of spin traps and the detection of nitric oxide, and the advantages...

  20. Electron collisions in the trapped gyro-Landau fluid transport model

    International Nuclear Information System (INIS)

    Staebler, G. M.; Kinsey, J. E.

    2010-01-01

    Accurately modeling electron collisions in the trapped gyro-Landau fluid (TGLF) equations has been a major challenge. Insights gained from numerically solving the gyrokinetic equation have lead to a significant improvement of the low order TGLF model. The theoretical motivation and verification of this model with the velocity-space gyrokinetic code GYRO[J. Candy and R. E. Waltz, J. Comput. Phys. 186, 545 (2003)] will be presented. The improvement in the fidelity of TGLF to GYRO is shown to also lead to better prediction of experimental temperature profiles by TGLF for a dedicated collision frequency scan.

  1. Trapping and dark current in plasma-based accelerators

    International Nuclear Information System (INIS)

    Schroder, C.B.; Esarey, E.; Shadwick, B.A.; Leemans, W.P.

    2004-01-01

    The trapping of thermal electrons in a nonlinear plasma wave of arbitrary phase velocity is investigated. The threshold plasma wave amplitude for trapping plasma electrons is calculated, thereby determining the fraction trapped and the expected dark current in a plasma-based accelerator. It is shown that the presence of a laser field (e.g., trapping in the self-modulated regime of the laser wakefield accelerator) increases the trapping threshold. Implications for experimental and numerical laser-plasma studies are discussed

  2. Dynamic Trap Formation and Elimination in Colloidal Quantum Dots

    KAUST Repository

    Voznyy, O.; Thon, S. M.; Ip, A. H.; Sargent, E. H.

    2013-01-01

    Using first-principles simulations on PbS and CdSe colloidal quantum dots, we find that surface defects form in response to electronic doping and charging of the nanoparticles. We show that electronic trap states in nanocrystals are dynamic entities, in contrast with the conventional picture wherein traps are viewed as stable electronic states that can be filled or emptied, but not created or destroyed. These traps arise from the formation or breaking of atomic dimers at the nanoparticle surface. The dimers' energy levels can reside within the bandgap, in which case a trap is formed. Fortunately, we are also able to identify a number of shallow-electron-affinity cations that stabilize the surface, working to counter dynamic trap formation and allowing for trap-free doping. © 2013 American Chemical Society.

  3. Dynamic Trap Formation and Elimination in Colloidal Quantum Dots

    KAUST Repository

    Voznyy, O.

    2013-03-21

    Using first-principles simulations on PbS and CdSe colloidal quantum dots, we find that surface defects form in response to electronic doping and charging of the nanoparticles. We show that electronic trap states in nanocrystals are dynamic entities, in contrast with the conventional picture wherein traps are viewed as stable electronic states that can be filled or emptied, but not created or destroyed. These traps arise from the formation or breaking of atomic dimers at the nanoparticle surface. The dimers\\' energy levels can reside within the bandgap, in which case a trap is formed. Fortunately, we are also able to identify a number of shallow-electron-affinity cations that stabilize the surface, working to counter dynamic trap formation and allowing for trap-free doping. © 2013 American Chemical Society.

  4. Observation of trapped-electron-mode microturbulence in reversed field pinch plasmas

    Science.gov (United States)

    Duff, J. R.; Williams, Z. R.; Brower, D. L.; Chapman, B. E.; Ding, W. X.; Pueschel, M. J.; Sarff, J. S.; Terry, P. W.

    2018-01-01

    Density fluctuations in the large-density-gradient region of improved confinement Madison Symmetric Torus reversed field pinch (RFP) plasmas exhibit multiple features that are characteristic of the trapped-electron mode (TEM). Core transport in conventional RFP plasmas is governed by magnetic stochasticity stemming from multiple long-wavelength tearing modes. Using inductive current profile control, these tearing modes are reduced, and global confinement is increased to that expected for comparable tokamak plasmas. Under these conditions, new short-wavelength fluctuations distinct from global tearing modes appear in the spectrum at a frequency of f ˜ 50 kHz, which have normalized perpendicular wavenumbers k⊥ρs≲ 0.2 and propagate in the electron diamagnetic drift direction. They exhibit a critical-gradient threshold, and the fluctuation amplitude increases with the local electron density gradient. These characteristics are consistent with predictions from gyrokinetic analysis using the Gene code, including increased TEM turbulence and transport from the interaction of remnant tearing magnetic fluctuations and zonal flow.

  5. An application of random field theory to analysis of electron trapping sites in disordered media

    International Nuclear Information System (INIS)

    Hilczer, M.; Bartczak, W.M.

    1993-01-01

    The potential energy surface in a disordered medium is considered a random field and described using the concepts of the mathematical theory of random fields. The preexisting traps for excess electrons are identified with certain regions of excursion (extreme regions) of the potential field. The theory provides an analytical method of statistical analysis of these regions. Parameters of the cavity-averaged potential field, which are provided by computer simulation of a given medium, serve as input data for the analysis. The statistics of preexisting traps are obtained for liquid methanol as a numerical example of the random field method. 26 refs., 6 figs

  6. Towards a Measurement of the n=2 Lamb Shift in Hydrogen-like Nitrogen Using an Electron Beam Ion Trap

    Energy Technology Data Exchange (ETDEWEB)

    Hosaka, K.; Crosby, D. N.; Gaarde-Widdowson, K.; Smith, C. J.; Silver, J. D. [University of Oxford, Department of Physics (United Kingdom); Myers, E. G. [Florida State University (United States); Kinugawa, T.; Ohtani, S. [University of Electro-Communications, Cold Trapped Ions Project, JST (Japan)

    2003-03-15

    Using a {sup 14}C{sup 16}O{sub 2} laser the 2s{sub 1/2}-2p{sub 3/2} (fine structure - Lamb shift) transition has been induced in {sup 14}N{sup 6+} ions trapped in an electron beam ion trap. Prospects for a measurement of the Lamb shift in hydrogen-like nitrogen are discussed.

  7. Deuterium trapping in carbon fiber composites under high fluence

    International Nuclear Information System (INIS)

    Airapetov, A.A.; Begrambekov, L.B.; Kuzmin, A.A.; Shigin, P.A.; Zakharov, A.M.

    2010-01-01

    The paper is devoted to investigation of deuterium trapping in CFC, dance graphite MPG-8 and pyrolytic graphite (PG) under plasma ion- and electron irradiation. Number of specific features of deuterium trapping and retention under plasma ion and electron irradiation is presented and discussed. In particular it is shown that 1) deuterium trapping takes place even when energy of impinging ions approaches zero; 2) deuterium is trapped under irradiation by plasma electrons; 3) under irradiation at equal fluences deuterium trapping is higher, when ion flux is smaller. High energy ion penetrating the surfaces are trapped in the traps created at the expense of their kinetic energy. The process may be named 'kinetic trapping'. Under low energy (smaller than 200 eV) electron and/or ion irradiation the energy of inelastic interaction on the surface provides creation of active centers, which initiate dissociation of deuterium sorbed on the surface, penetration of deuterium atoms into graphite and their trapping in specific low energy traps. The term 'potential trapping' is proposed for this type of trapping. Under high energy irradiation such atoms can fill the traps formed through kinetic mechanism. Origination of moveable deuterium atoms from the layer of surface sorption seems to be time dependent process and it is a reason of increase of trapping along with irradiation time. New features of deuterium trapping and retention in graphite evaluated in this study offer new opportunities for analysis and correct estimation of hydrogen isotope trapping and retention in tokamaks having graphite tiles. (authors)

  8. Confinement time exceeding one second for a toroidal electron plasma.

    Science.gov (United States)

    Marler, J P; Stoneking, M R

    2008-04-18

    Nearly steady-state electron plasmas are trapped in a toroidal magnetic field for the first time. We report the first results from a new toroidal electron plasma experiment, the Lawrence Non-neutral Torus II, in which electron densities on the order of 10(7) cm(-3) are trapped in a 270-degree toroidal arc (670 G toroidal magnetic field) by application of trapping potentials to segments of a conducting shell. The total charge inferred from measurements of the frequency of the m=1 diocotron mode is observed to decay on a 3 s time scale, a time scale that approaches the predicted limit due to magnetic pumping transport. Three seconds represents approximately equal to 10(5) periods of the lowest frequency plasma mode, indicating that nearly steady-state conditions are achieved.

  9. Precision Measurement of the Electron's Electric Dipole Moment Using Trapped Molecular Ions

    Science.gov (United States)

    Cairncross, William B.; Gresh, Daniel N.; Grau, Matt; Cossel, Kevin C.; Roussy, Tanya S.; Ni, Yiqi; Zhou, Yan; Ye, Jun; Cornell, Eric A.

    2017-10-01

    We describe the first precision measurement of the electron's electric dipole moment (de) using trapped molecular ions, demonstrating the application of spin interrogation times over 700 ms to achieve high sensitivity and stringent rejection of systematic errors. Through electron spin resonance spectroscopy on 180Hf 19F+ in its metastable 3Δ1 electronic state, we obtain de=(0.9 ±7. 7stat±1. 7syst)×10-29 e cm , resulting in an upper bound of |de|<1.3 ×10-28 e cm (90% confidence). Our result provides independent confirmation of the current upper bound of |de|<9.4 ×10-29 e cm [J. Baron et al., New J. Phys. 19, 073029 (2017), 10.1088/1367-2630/aa708e], and offers the potential to improve on this limit in the near future.

  10. Electronics II essentials

    CERN Document Server

    REA, The Editors of

    2012-01-01

    REA's Essentials provide quick and easy access to critical information in a variety of different fields, ranging from the most basic to the most advanced. As its name implies, these concise, comprehensive study guides summarize the essentials of the field covered. Essentials are helpful when preparing for exams, doing homework and will remain a lasting reference source for students, teachers, and professionals. Electronics II covers operational amplifiers, feedback and frequency compensation of OP amps, multivibrators, logic gates and families, Boolean algebra, registers, counters, arithmet

  11. Distinguishing between deep trapping transients of electrons and holes in TiO2 nanotube arrays using planar microwave resonator sensor.

    Science.gov (United States)

    Zarifi, Mohammad H; Wiltshire, Benjamin Daniel; Mahdi, Najia; Shankar, Karthik; Daneshmand, Mojgan

    2018-05-16

    A large signal DC bias and a small signal microwave bias were simultaneously applied to TiO2 nanotube membranes mounted on a planar microwave resonator. The DC bias modulated the electron concentration in the TiO2 nanotubes, and was varied between 0 and 120 V in this study. Transients immediately following the application and removal of DC bias were measured by monitoring the S-parameters of the resonator as a function of time. The DC bias stimulated Poole-Frenkel type trap-mediated electrical injection of excess carriers into TiO2 nanotubes which resulted in a near constant resonant frequency but a pronounced decrease in the microwave amplitude due to free electron absorption. When ultraviolet illumination and DC bias were both present and then step-wise removed, the resonant frequency shifted due to trapping -mediated change in the dielectric constant of the nanotube membranes. Characteristic lifetimes of 60-80 s, 300-800 s and ~3000 s were present regardless of whether light or bias was applied and are also observed in the presence of a hole scavenger, which we attribute to oxygen adsorption and deep electron traps while another characteristic lifetime > 9000 s was only present when illumination was applied, and is attributed to the presence of hole traps.

  12. Proposed demonstration of the Einstein-Poldosky-Rosen paradox using trapped electrons

    International Nuclear Information System (INIS)

    Martins, Ana M.

    2002-01-01

    Correlations of the type discussed by Einstein, Poldosky, and Rosen in their original 1935 paradox may be generated between the positions and the momenta of two electrons confined in two spatially separated Penning traps when they are allowed to be coupled for a certain time interval. An experimental demonstration of the paradox could be done using the accurate techniques of manipulation and measurement of confined charged particles. The basic ideas presented in this paper might be extended in order to enable quantum information transfer of continuous variables between massive particles

  13. Variations of electron fluxes in the outer radiation belt near the boundary of a trapping region during substorms

    International Nuclear Information System (INIS)

    Ginzburg, E.A.; Malyshev, A.B.

    1979-01-01

    Variations of electron fluxes with the energy Esub(e) > 0.7 MeV have been investigated near the high-latitude boundary of electron trapping region in the night and day sections of the magnetosphere. It is found that during substorms the natural changes of the structure of electron fluxes take place. On the night side of the magnetosphere after the flux boundary drift to the equator at the preliminary phase, its sharp drift to the pole at the explosion phase takes place with further slow ( during 1-2 hours) shift to the initial position. The boundary position reconstruction period coincide by duration with the life time of negative bays at magnetograms of the night section stations. On the day side the boundary of electron fluxes recorded drifts to the pole in 30-60 min after the beginning of the substorm exposion phase. The results obtained are interpreted within the framework of the theory of adiabatic drift of trapped electrons and their pitch-angular diffusion under the effect of very low frequency waves

  14. Electronic properties of electron and hole in type-II semiconductor nano-heterostructures

    Science.gov (United States)

    Rahul, K. Suseel; Souparnika, C.; Salini, K.; Mathew, Vincent

    2016-05-01

    In this project, we record the orbitals of electron and hole in type-II (CdTe/CdSe/CdTe/CdSe) semiconductor nanocrystal using effective mass approximation. In type-II the band edges of both valance and conduction band are higher than that of shell. So the electron and hole get confined in different layers of the hetero-structure. The energy eigen values and eigen functions are calculated by solving Schrodinger equation using finite difference matrix method. Based on this we investigate the effect of shell thickness and well width on energy and probability distribution of ground state (1s) and few excited states (1p,1d,etc). Our results predict that, type-II quantum dots have significant importance in photovoltaic applications.

  15. Electronic properties of electron and hole in type-II semiconductor nano-heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Rahul, K. Suseel [Department of Physics, Central University of Kerala, Riverside Transit Campus, Kasaragod, Kerala. India (India); Department of Physics, Sri Vyasa NSS College, Wadakkancheri, Thrissur, Kerala, PIN:680623. India (India); Souparnika, C. [Department of Physics, Sri Vyasa NSS College, Wadakkancheri, Thrissur, Kerala, PIN:680623. India (India); Salini, K.; Mathew, Vincent, E-mail: vincent@cukerala.ac.in [Department of Physics, Central University of Kerala, Riverside Transit Campus, Kasaragod, Kerala. India (India)

    2016-05-06

    In this project, we record the orbitals of electron and hole in type-II (CdTe/CdSe/CdTe/CdSe) semiconductor nanocrystal using effective mass approximation. In type-II the band edges of both valance and conduction band are higher than that of shell. So the electron and hole get confined in different layers of the hetero-structure. The energy eigen values and eigen functions are calculated by solving Schrodinger equation using finite difference matrix method. Based on this we investigate the effect of shell thickness and well width on energy and probability distribution of ground state (1s) and few excited states (1p,1d,etc). Our results predict that, type-II quantum dots have significant importance in photovoltaic applications.

  16. Luminescence and photothermally stimulated defects creation processes in PbWO{sub 4}:La{sup 3+}, Y{sup 3+} (PWO II) crystals

    Energy Technology Data Exchange (ETDEWEB)

    Auffray, E. [CERN, Geneva 23, Geneva (Switzerland); Korjik, M. [Institute for Nuclear Problems, 11 Bobruiskaya, 220020 Minsk (Belarus); Zazubovich, S., E-mail: svetlana.zazubovits@ut.ee [Institute of Physics, University of Tartu, Ravila 14 c, 50411 Tartu (Estonia)

    2015-12-15

    Photoluminescence and thermally stimulated luminescence (TSL) are studied for a PbWO{sub 4} crystal grown by the Czochralski method at Bogoroditsk Technical Chemical Plant, Russia from the melt with a precise tuning of the stoichiometry and co-doped with La{sup 3+} and Y{sup 3+} ions (the PWO II crystal). Photothermally stimulated processes of electron and hole centers creation under selective UV irradiation of this crystal in the 3.5–5.0 eV energy range and the 85–205 K temperature range are clarified and the optically created electron and hole centers are identified. The electrons in PWO II are mainly trapped at the (WO{sub 4}){sup 2−} groups located close to single La{sup 3+} and Y{sup 3+} ions, producing the electron {(WO_4)"3"−–La"3"+} and {(WO_4)"3"−–Y"3"+} centers. The holes are mainly trapped at the regular oxygen ions O{sup 2−} located close to La{sup 3+} and Y{sup 3+} ions associated with lead vacancies, producing the hole O{sup −}(I)-type centers. No evidence of single-vacancy-related centers has been observed in PWO II. The data obtained indicate that excellent scintillation characteristics of the PWO II crystal can be explained by a negligible concentration of single (non-compensated) oxygen and lead vacancies as the traps for electrons and holes, respectively. - Highlights: • Photoluminescence of the PbWO{sub 4}:La{sup 3+}, Y{sup 3+} (PWO II) crystal is investigated. • Creation of defects under UV irradiation of PWO II is studied by TSL. • Origin of dominating electron and hole centers is ascertained. • Concentration of single-vacancy-related centers is found to be negligible. • Excellent scintillation characteristics of the PWO II crystal are explained.

  17. Simulation of the electron cloud density in BEPC II

    International Nuclear Information System (INIS)

    Liu Yudong; Guo Zhiyuan; Wang Jiuqing

    2004-01-01

    Electron Cloud Instability (ECI) may take place in positron storage ring when the machine is operated with multi-bunch positron beam. According to the actual shape of the vacuum chamber in the BEPC II, a program has been developed. With the code, authors can calculate the electron density in the chamber with different length of antechamber and the different secondary electron yield respectively. By the simulation, the possibility to put clearing electrodes in the chamber to reduce the electron density in the central region of the chamber is investigated. The simulation provides meaningful and important results for the BEPC II project and electron cloud instability research

  18. Screening conditions in a magnetized plasma with electron beam, with application to ripple trapped electron losses

    Energy Technology Data Exchange (ETDEWEB)

    Faudot, E.; Heuraux, S. [Nancy-1 Univ. Henri Poincare, LPMIA, UMR CNRS 7040, 54 (France); Colas, L.; Saint-Laurent, F.; Martin, G.; Basiuk, V. [Association Euratom-CEA Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee

    2004-07-01

    In Tore Supra, electrons are accelerated by lower hybrid waves in the direction parallel to the confinement magnetic field, in order to drive non-inductive current. But electrons have also on increase of their perpendicular velocity, then 10% of the most energetic electrons get trapped in the magnetic ripple between 2 adjacent toroidal coils, thus forming a beam. The electron beam follows a banana trajectory, the 20 mm wide protection represented by a cooled copper tube is assumed to protect the VP entrance from this energetic flux. Nevertheless, this beam is able to go beyond the copper tube and creates a hot spot on the steel panel edge able to melt the metal. Heat fluxes deposition on the vertical port (VP) can be understood with a beam+sheath theory including the fact that the sheaths can be obstructed when their length becomes greater than flux tube length. By this way, we identify 4 deposition regimes: 2 free sheath regimes and 2 obstructed sheath regimes. Beam flux deposits either at the entrance of the VP along first 2 cm behind the copper tube or until the end of the VP when beam flux is high and for free sheath. Obstructed sheaths make the repulsive, potential for electrons decrease and so accelerate the flux deposition. (authors)

  19. 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)

  20. Experimental evaluation of quantum computing elements (qubits) made of electrons trapped over a liquid helium film; Evaluation experimentale d'elements de calcul quantique (qubit) formes d'electrons pieges sur l'helium liquide

    Energy Technology Data Exchange (ETDEWEB)

    Rousseau, E

    2006-12-15

    An electron on helium presents a quantized energy spectrum. The interaction with the environment is considered sufficiently weak in order to allow the realization of a quantum bit (qubit) by using the first two energy levels. The first stage in the realization of this qubit was to trap and control a single electron. This is carried out thanks to a set of micro-fabricated electrodes defining a well of potential in which the electron is trapped. We are able with such a sample to trap and detect a variables number of electrons varying between one and around twenty. This then allowed us to study the static behaviour of a small number of electrons in a trap. They are supposed to crystallize and form structures called Wigner molecules. Such molecules have not yet been observed yet with electrons above helium. Our results bring circumstantial evidence for of Wigner crystallization. We then sought to characterize the qubit more precisely. We sought to carry out a projective reading (depending on the state of the qubit) and a measurement of the relaxation time. The results were obtained by exciting the electron with an incoherent electric field. A clean measurement of the relaxation time would require a coherent electric field. The conclusion cannot thus be final but it would seem that the relaxation time is shorter than calculated theoretically. That is perhaps due to a measurement of the relaxation between the oscillating states in the trap and not between the states of the qubit. (author)

  1. PIC simulations of the trapped electron filamentation instability in finite-width electron plasma waves

    Science.gov (United States)

    Winjum, B. J.; Banks, J. W.; Berger, R. L.; Cohen, B. I.; Chapman, T.; Hittinger, J. A. F.; Rozmus, W.; Strozzi, D. J.; Brunner, S.

    2012-10-01

    We present results on the kinetic filamentation of finite-width nonlinear electron plasma waves (EPW). Using 2D simulations with the PIC code BEPS, we excite a traveling EPW with a Gaussian transverse profile and a wavenumber k0λDe= 1/3. The transverse wavenumber spectrum broadens during transverse EPW localization for small width (but sufficiently large amplitude) waves, while the spectrum narrows to a dominant k as the initial EPW width increases to the plane-wave limit. For large EPW widths, filaments can grow and destroy the wave coherence before transverse localization destroys the wave; the filaments in turn evolve individually as self-focusing EPWs. Additionally, a transverse electric field develops that affects trapped electrons, and a beam-like distribution of untrapped electrons develops between filaments and on the sides of a localizing EPW. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and funded by the Laboratory Research and Development Program at LLNL under project tracking code 12-ERD-061. Supported also under Grants DE-FG52-09NA29552 and NSF-Phy-0904039. Simulations were performed on UCLA's Hoffman2 and NERSC's Hopper.

  2. (Anti)hydrogen recombination studies in a nested Penning trap

    International Nuclear Information System (INIS)

    Quint, W.; Kaiser, R.; Hall, D.; Gabrielse, G.

    1993-01-01

    Extremely cold antiprotons, stored in Penning trap at 4 K, open the way toward the production and study of cold antihydrogen. We have begun experimentally investigating the possibility to recombine cold positrons and antiprotons within nested Penning traps. Trap potentials are adjusted to allow cold trapped protons (and positive helium ions) to pass through cold trapped electrons. Electrons, protons and ions are counted by ejecting them to a cold channel plate and by nondestructive radiofrequency techniques. The effect of the space charge of one trapped species upon another trapped species passing through is clearly observed. (orig.)

  3. Capture, Electron-Cooling and Compression of Antiprotons in a Large Penning-Trap for Physics Experiments with an Ultra-Low Energy Extracted Antiproton Beam

    CERN Multimedia

    2002-01-01

    % PS200 \\\\ \\\\The availability of ultra-low energy antiprotons is a crucial ingredient for the execution of the gravity measurements PS200. We have developed a method to provide such low energy antiprotons based on a large Penning trap (the PS200 catching trap). This system can accept a fast-extracted pulse from LEAR, reduce the energy of the antiprotons in the pulse from 5.9~MeV to several tens of kilovolts using a degrading foil, and then capture the antiprotons in a large Penning trap. These antiprotons are cooled by electrons previously admitted to the trap and are collected in a small region at the center of the trap. We have demonstrated our capability to capture up to 1~million antiprotons from LEAR in a single shot, electron cool these antiprotons, and transfer up to 95\\% of them into the inner, harmonic region. A storage time in excess of 1 hour was observed. These results have been obtained with the cryogenic trap vacuum coupled to a room temperature vacuum at about l0$ ^- ^{1} ^0 $ Torr, which is an...

  4. Stable confinement of toroidal electron plasma in an internal conductor device Prototype-Ring Trap

    International Nuclear Information System (INIS)

    Saitoh, H.; Yoshida, Z.; Watanabe, S.

    2005-01-01

    A pure electron plasma has been produced in an internal conductor device Prototype-Ring Trap (Proto-RT). The temporal evolution of the electron plasma was investigated by the measurement of electrostatic fluctuations. Stable confinement was realized when the potential profile adjusted to match the magnetic surfaces. The confinement time varies as a function of the magnetic field strength and the neutral gas pressure, and is comparable to the diffusion time of electrons determined by the classical collisions with neutral gas. Although the addition of a toroidal magnetic field stabilized the electrostatic fluctuation of the plasma, the effects of the magnetic shear shortened the stable confinement time, possibly because of the obstacles of coil support structures

  5. Electron shakeoff following the β+ decay of +19Ne and +35Ar trapped ions

    Science.gov (United States)

    Fabian, X.; Fléchard, X.; Pons, B.; Liénard, E.; Ban, G.; Breitenfeldt, M.; Couratin, C.; Delahaye, P.; Durand, D.; Finlay, P.; Guillon, B.; Lemière, Y.; Mauger, F.; Méry, A.; Naviliat-Cuncic, O.; Porobic, T.; Quéméner, G.; Severijns, N.; Thomas, J.-C.

    2018-02-01

    The electron shakeoff of 19F and 35Cl atoms resulting from the β+ decay of +19Ne and +35Ar ions has been investigated using a Paul trap coupled to a time of flight recoil-ion spectrometer. The charge-state distributions of the recoiling daughter nuclei were compared to theoretical calculations based on the sudden approximation and accounting for subsequent Auger processes. The excellent agreement obtained for 35Cl is not reproduced in 19F. The shortcoming is attributed to the inaccuracy of the independent particle model employed to calculate the primary shakeoff probabilities in systems with rather low atomic numbers. This calls for more elaborate calculations, including explicitly the electron-electron correlations.

  6. Micro Penning Trap for Continuous Magnetic Field Monitoring in High Radiation Environments

    Science.gov (United States)

    Latorre, Javiera; Bollen, Georg; Gulyuz, Kerim; Ringle, Ryan; Bado, Philippe; Dugan, Mark; Lebit Team; Translume Collaboration

    2016-09-01

    As new facilities for rare isotope beams, like FRIB at MSU, are constructed, there is a need for new instrumentation to monitor magnetic fields in beam magnets that can withstand the higher radiation level. Currently NMR probes, the instruments used extensively to monitor magnetic fields, do not have a long lifespans in radiation-high environments. Therefore, a radiation-hard replacement is needed. We propose to use Penning trap mass spectrometry techniques to make high precision magnetic field measurements. Our Penning microtrap will be radiation resistant as all of the vital electronics will be at a safe distance from the radiation. The trap itself is made from materials not subject to radiation damage. Penning trap mass spectrometers can determine the magnetic field by measuring the cyclotron frequency of an ion with a known mass and charge. This principle is used on the Low Energy Beam Ion Trap (LEBIT) minitrap at NSCL which is the foundation for the microtrap. We have partnered with Translume, who specialize in glass micro-fabrication, to develop a microtrap in fused-silica glass. A microtrap is finished and ready for testing at NSCL with all of the electronic and hardware components setup. DOE Phase II SBIR Award No. DE-SC0011313, NSF Award Number 1062410 REU in Physics, NSF under Grant No. PHY-1102511.

  7. Effects of radial envelope modulations on the collisionless trapped-electron mode in tokamak plasmas

    Science.gov (United States)

    Chen, Hao-Tian; Chen, Liu

    2018-05-01

    Adopting the ballooning-mode representation and including the effects of radial envelope modulations, we have derived the corresponding linear eigenmode equation for the collisionless trapped-electron mode in tokamak plasmas. Numerical solutions of the eigenmode equation indicate that finite radial envelope modulations can affect the linear stability properties both quantitatively and qualitatively via the significant modifications in the corresponding eigenmode structures.

  8. Particle trapping in stimulated scattering processes

    International Nuclear Information System (INIS)

    Karttunen, S.J.; Heikkinen, J.A.

    1981-01-01

    Particle trapping effects on stimulated Brillouin and Raman scattering are investigated. A time and space dependent model assumes a Maxwellian plasma which is taken to be homogeneous in the interaction region. Ion trapping has a rather weak effect on stimulated Brillouin scattering and large reflectivities are obtained even in strong trapping regime. Stimulated Raman scattering is considerably reduced by electron trapping. Typically 15-20 times larger laser intensities are required to obtain same reflectivity levels than without trapping. (author)

  9. Density of Trap States and Auger-mediated Electron Trapping in CdTe Quantum-Dot Solids

    NARCIS (Netherlands)

    Boehme, Simon C.; Mikel Azpiroz, Jon; Aulin, Yaroslav V.; Grozema, Ferdinand C.; Vanmaekelbergh, Daniel; Siebbeles, Laurens D. A.; Infante, Ivan; Houtepen, Arjan J.

    Charge trapping is an ubiquitous process in colloidal quantum-dot solids and a major limitation to the efficiency of quantum dot based devices such as solar cells, LEDs, and thermoelectrics. Although empirical approaches led to a reduction of trapping and thereby efficiency enhancements, the exact

  10. Density of trap states and Auger-mediated electron trapping in CdTe quantum-dot solids

    NARCIS (Netherlands)

    Boehme, Simon C.; Azpiroz, Jon Mikel; Aulin, Yaroslav V.; Grozema, Ferdinand C.; Vanmaekelbergh, Daniël; Siebbeles, Laurens D A; Infante, Ivan; Houtepen, Arjan J.

    2015-01-01

    Charge trapping is an ubiquitous process in colloidal quantum-dot solids and a major limitation to the efficiency of quantum dot based devices such as solar cells, LEDs, and thermoelectrics. Although empirical approaches led to a reduction of trapping and thereby efficiency enhancements, the exact

  11. 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...

  12. Structure and dynamics of highly charged heavy ions studied with the electron beam ion trap in Tokyo

    International Nuclear Information System (INIS)

    Nakamura, Nobuyuki; Hu, Zhimin; Watanabe, Hirofumi; Li, Yueming; Kato, Daiji; Currell, Fred J.; Tong Xiaomin; Watanabe, Tsutomu; Ohtani, Shunsuke

    2011-01-01

    In this paper, we present the structure and the dynamics of highly charged heavy ions studied through dielectronic recombination (DR) observations performed with the Tokyo electron beam ion trap. By measuring the energy dependence of the ion abundance ratio in the trap at equilibrium, we have observed DR processes for open shell systems very clearly. Remarkable relativistic effects due to the generalized Breit interaction have been clearly shown in DR for highly charged heavy ions. We also present the first result for the coincidence measurement of two photons emitted from a single DR event.

  13. Solar cyclic behavior of trapped energetic electrons in Earth's inner radiation belt

    Science.gov (United States)

    Abel, Bob; Thorne, Richard M.

    1994-10-01

    Magnetic electron spectrometer data from six satellites (OV3-3, OV1-14, OGO 5, S3-2, S3-3, and CRRES) have been used to study long-term (1966-1991) behavior of trapped energetic electrons in the inner radiation belt. Comparison of the observed energy spectra at L equal to or greater than 1.35 for different phases of the solar cycle reveals a clear trend toward enhanced fluxes during periods of solar maximum for energies below a few hundred keV; we suggest that this is caused by an increase in the rate of inward radial diffusion from a source at higher L. In contrast, for L less than 1.30, where atmospheric collisions become increasingly important, the electron flux is reduced during solar maximum; we attribute this to the expected increase in upper atmospheric densities. The electron flux above 1 MeV exhibits a systematic decay beyond 1979 to values well below the current NASA AE-8 model. This indicates that the natural background of high-energy electrons has previously been overestimated due to the long lasting presence of electrons produced by nuclear detonations in the upper atmosphere in the late 1950s and early 1960s.

  14. Effect of trapped electron on the dust ion acoustic waves in dusty plasma using time fractional modified Korteweg-de Vries equation

    International Nuclear Information System (INIS)

    Nazari-Golshan, A.; Nourazar, S. S.

    2013-01-01

    The time fractional modified Korteweg-de Vries (TFMKdV) equation is solved to study the nonlinear propagation of small but finite amplitude dust ion-acoustic (DIA) solitary waves in un-magnetized dusty plasma with trapped electrons. The plasma is composed of a cold ion fluid, stationary dust grains, and hot electrons obeying a trapped electron distribution. The TFMKdV equation is derived by using the semi-inverse and Agrawal's methods and then solved by the Laplace Adomian decomposition method. Our results show that the amplitude of the DIA solitary waves increases with the increase of time fractional order β, the wave velocity v 0 , and the population of the background free electrons λ. However, it is vice-versa for the deviation from isothermality parameter b, which is in agreement with the result obtained previously

  15. First experiments with the 200 keV electron beam ion trap at LLNL

    International Nuclear Information System (INIS)

    Marrs, R.E.; Knapp, D.A.; Elliott, S.

    1993-01-01

    A high-energy electron beam ion trap (Super EBIT) is operating at electron energies up to 200 keV and currents up to 200 mA. Highly charged ions up to Li-like U 89+ and H-like Pb 81+ have been produced and studied. Ionization cross sections for H-like Dy 66+ at E e = 170 keV have been measured with respect to radiative recombination from the observed Dy 66+ /Dy 67+ equilibrium ionization balance. A Bragg crystal spectrometer has been used to measure 2s 1/2 -2p 3/2 transition energies in Li-like U 82+ with respect to the Lymann-series transitions in lower-Z hydrogenic ions

  16. Trapped Electron Mode Turbulence Driven Intrinsic Rotation in Tokamak Plasmas

    International Nuclear Information System (INIS)

    Wang, W.X.; Hahm, T.S.; Ethier, S.; Zakharov, L.E.

    2011-01-01

    Recent progress from global gyrokinetic simulations in understanding the origin of intrinsic rotation in toroidal plasmas is reported with emphasis on electron thermal transport dominated regimes. The turbulence driven intrinsic torque associated with nonlinear residual stress generation by the fluctuation intensity and the intensity gradient in the presence of zonal flow shear induced asymmetry in the parallel wavenumber spectrum is shown to scale close to linearly with plasma gradients and the inverse of the plasma current. These results qualitatively reproduce empirical scalings of intrinsic rotation observed in various experiments. The origin of current scaling is found to be due to enhanced kll symmetry breaking induced by the increased radial variation of the safety factor as the current decreases. The physics origin for the linear dependence of intrinsic torque on pressure gradient is that both turbulence intensity and the zonal flow shear, which are two key ingredients for driving residual stress, increase with the strength of turbulence drive, which is R0/LTe and R0/Lne for the trapped electron mode.

  17. Charge generation and trapping in bisphenol-A-polycarbonate/N-isopropylcarbazole mixture: A study by electron bombardment-induced conductivity

    International Nuclear Information System (INIS)

    Santos, S.; Caraballo, D.

    2007-01-01

    Electron bombardment-induced conductivity measurements were carried out on cast films of N-isopropylcarbazole (NIPC) dispersed into an amorphous matrix of bisphenol-A-polycarbonate. The charge generation was studied by estimating the hole yield (g), the fraction of charge escaping recombination, as a function of electric field and concentration of NIPC at room temperature. The hole yield, besides increasing by increasing the content of NIPC, was observed to increase with the electric field in the manner predicted by the Onsager theory of geminate recombination. Deep trapping levels were studied by filling under electron bombardment and observing transients. The deep traps were neutral in nature with a concentration on the order of 8.0x10 14 cm -3 , which was low enough not to degrade transport under normal conditions

  18. Theoretical characterization on the size-dependent electron and hole trapping activity of chloride-passivated CdSe nanoclusters

    Science.gov (United States)

    Cui, Yingqi; Cui, Xianhui; Zhang, Li; Xie, Yujuan; Yang, Mingli

    2018-04-01

    Ligand passivation is often used to suppress the surface trap states of semiconductor quantum dots (QDs) for their continuous photoluminescence output. The suppression process is related to the electrophilic/nucleophilic activity of surface atoms that varies with the structure and size of QD and the electron donating/accepting nature of ligand. Based on first-principles-based descriptors and cluster models, the electrophilic/nucleophilic activities of bare and chloride-coated CdSe clusters were studied to reveal the suppression mechanism of Cl-passivated QDs and compared to experimental observations. The surface atoms of bare clusters have higher activity than inner atoms and their activity decreases with cluster size. In the ligand-coated clusters, the Cd atom remains as the electrophilic site, while the nucleophilic site of Se atoms is replaced by Cl atoms. The activities of Cd and Cl atoms in the coated clusters are, however, remarkably weaker than those in bare clusters. Cluster size, dangling atoms, ligand coverage, electronegativity of ligand atoms, and solvent (water) were found to have considerable influence on the activity of surface atoms. The suppression of surface trap states in Cl-passivated QDs was attributed to the reduction of electrophilic/nucleophilic activity of Cd/Se/Cl atoms. Both saturation to under-coordinated surface atoms and proper selection for the electron donating/accepting strength of ligands are crucial for eliminating the charge carrier traps. Our calculations predicted a similar suppressing effect of chloride ligands with experiments and provided a simple but effective approach to assess the charge carrier trapping behaviors of semiconductor QDs.

  19. Investigation of diocotron modes in toroidally trapped electron plasmas using non-destructive method

    Science.gov (United States)

    Lachhvani, Lavkesh; Pahari, Sambaran; Sengupta, Sudip; Yeole, Yogesh G.; Bajpai, Manu; Chattopadhyay, P. K.

    2017-10-01

    Experiments with trapped electron plasmas in a SMall Aspect Ratio Toroidal device (SMARTEX-C) have demonstrated a flute-like mode represented by oscillations on capacitive (wall) probes. Although analogous to diocotron mode observed in linear electron traps, the mode evolution in toroids can have interesting consequences due to the presence of in-homogeneous magnetic field. In SMARTEX-C, the probe signals are observed to undergo transition from small, near-sinusoidal oscillations to large amplitude, non-linear "double-peaked" oscillations. To interpret the wall probe signal and bring forth the dynamics, an expression for the induced current on the probe for an oscillating charge is derived, utilizing Green's Reciprocation Theorem. Equilibrium position, poloidal velocity of the charge cloud, and charge content of the cloud, required to compute the induced current, are estimated from the experiments. Signal through capacitive probes is thereby computed numerically for possible charge cloud trajectories. In order to correlate with experiments, starting with an intuitive guess of the trajectory, the model is evolved and tweaked to arrive at a signal consistent with experimentally observed probe signals. A possible vortex like dynamics is predicted, hitherto unexplored in toroidal geometries, for a limited set of experimental observations from SMARTEX-C. Though heuristic, a useful interpretation of capacitive probe data in terms of charge cloud dynamics is obtained.

  20. A metastable helium trap for atomic collision physics

    International Nuclear Information System (INIS)

    Colla, M.; Gulley, R.; Uhlmann, L.; Hoogerland, M.D.; Baldwin, K.G.H.; Buckman, S.J.

    1999-01-01

    Full text: Metastable helium in the 2 3 S state is an important species for atom optics and atomic collision physics. Because of its large internal energy (20eV), long lifetime (∼8000s) and large collision cross section for a range of processes, metastable helium plays an important role in atmospheric physics, plasma discharges and gas laser physics. We have embarked on a program of studies on atom-atom and electron-atom collision processes involving cold metastable helium. We confine metastable helium atoms in a magneto-optic trap (MOT), which is loaded by a transversely collimated, slowed and 2-D focussed atomic beam. We employ diode laser tuned to the 1083 nm (2 3 S 1 - 2 3 P2 1 ) transition to generate laser cooling forces in both the loading beam and the trap. Approximately 10 million helium atoms are trapped at temperatures of ∼ 1mK. We use phase modulation spectroscopy to measure the trapped atomic density. The cold, trapped atoms can collide to produce either atomic He + or molecular He 2 + ions by Penning Ionisation (PI) or Associative Ionisation (AI). The rate of formation of these ions is dependant upon the detuning of the trapping laser from resonance. A further laser can be used to connect the 2 3 S 1 state to another higher lying excited state, and variation of the probe laser detuning used to measure interatomic collision potential. Electron-atom collision processes are studied using a monochromatic electron beam with a well defined spatial current distribution. The total trap loss due to electron collisions is measured as a function of electron energy. Results will be presented for these atomic collision physics measurements involving cold, trapped metastable helium atoms. Copyright (1999) Australian Optical Society

  1. APC-II: an electron beam propagation code

    International Nuclear Information System (INIS)

    Iwan, D.C.; Freeman, J.R.

    1984-05-01

    The computer code APC-II simulates the propagation of a relativistic electron beam through air. APC-II is an updated version of the APC envelope model code. It incorporates an improved conductivity model which significantly extends the range of stable calculations. A number of test cases show that these new models are capable of reproducing the simulations of the original APC code. As the result of a major restructuring and reprogramming of the code, APC-II is now friendly to both the occasional user and the experienced user who wishes to make modifications. Most of the code is in standard ANS-II Fortran 77 so that it can be easily transported between machines

  2. Mini ion trap mass spectrometer

    Science.gov (United States)

    Dietrich, D.D.; Keville, R.F.

    1995-09-19

    An ion trap is described which operates in the regime between research ion traps which can detect ions with a mass resolution of better than 1:10{sup 9} and commercial mass spectrometers requiring 10{sup 4} ions with resolutions of a few hundred. The power consumption is kept to a minimum by the use of permanent magnets and a novel electron gun design. By Fourier analyzing the ion cyclotron resonance signals induced in the trap electrodes, a complete mass spectra in a single combined structure can be detected. An attribute of the ion trap mass spectrometer is that overall system size is drastically reduced due to combining a unique electron source and mass analyzer/detector in a single device. This enables portable low power mass spectrometers for the detection of environmental pollutants or illicit substances, as well as sensors for on board diagnostics to monitor engine performance or for active feedback in any process involving exhausting waste products. 10 figs.

  3. X-ray spectroscopy of hydrogen-like ions in an electron beam ion trap

    Energy Technology Data Exchange (ETDEWEB)

    Tarbutt, M.R.; Crosby, D.; Silver, J.D. [Univ. of Oxford, Clarendon Lab. (United Kingdom); Myers, E.G. [Dept. of Physics, Florida State Univ., Tallahassee, FL (United States); Nakamura, N.; Ohtani, S. [ICORP, JST, Chofu, Tokyo (Japan)

    2001-07-01

    The X-ray emission from highly charged hydrogen-like ions in an electron beam ion trap is free from the problems of satellite contamination and Doppler shifts inherent in fast-beam sources. This is a favourable situation for the measurement of ground-state Lamb shifts in these ions. We present recent progress toward this goal, and discuss a method whereby wavelength comparison between transitions in hydrogenlike ions of different nuclear charge Z, enable the measurement of QED effects without requiring an absolute calibration.

  4. Dependence of direct losses and trapping properties with the magnetic configuration in TJ-II

    International Nuclear Information System (INIS)

    Guasp, J.; Liniers, M.

    1998-05-01

    The former studies concerning direct losses, disymmetries, trapping and radial electric field effects for intermediate energy ions have been extended to several magnetic configurations in TJ-II. In the absence of electric field there are strong similarities in the behaviour of all configurations: disymmetries, loss distributions at plasma border, radial and angular profiles, etc. Generally the differences are only quantitative and dominated by the magnetic ripple at border, that is clearly related with the configuration radius. This qualitative similarity disappears in the presence of a radial electric field. The field resonance are at the origin of these differences. A simple model reproduces correctly the ordering and degree of influence of these resonances. Except when the 0 resonance predominates the los distributions at plasma border move always in the direction of the induced poloidal rotation. The los radial profiles are strongly affected by the -2 Resonance, that can provoke the appearance of lost passing ions well inside the plasma. Instead the radial and angular profiles for trapping are only slightly affected by the -2 Resonance, while the 0 Resonance has a very strong influence there

  5. Mitigating unaccounted fishing mortality from gillnet and traps

    NARCIS (Netherlands)

    Uhlmann, S.S.; Broadhurst, M.K.

    2015-01-01

    Gillnets and traps often are considered to have fewer holistic environmental impacts than active fishing gears. However, in addition to the targeted catches, gillnets and traps still cause unwanted mortalities due to (i) discarding, (ii) ghost fishing of derelict gear, (iii) depredation, (iv)

  6. Intrinsic charge trapping in amorphous oxide films: status and challenges

    Science.gov (United States)

    Strand, Jack; Kaviani, Moloud; Gao, David; El-Sayed, Al-Moatasem; Afanas’ev, Valeri V.; Shluger, Alexander L.

    2018-06-01

    We review the current understanding of intrinsic electron and hole trapping in insulating amorphous oxide films on semiconductor and metal substrates. The experimental and theoretical evidences are provided for the existence of intrinsic deep electron and hole trap states stemming from the disorder of amorphous metal oxide networks. We start from presenting the results for amorphous (a) HfO2, chosen due to the availability of highest purity amorphous films, which is vital for studying their intrinsic electronic properties. Exhaustive photo-depopulation spectroscopy measurements and theoretical calculations using density functional theory shed light on the atomic nature of electronic gap states responsible for deep electron trapping observed in a-HfO2. We review theoretical methods used for creating models of amorphous structures and electronic structure calculations of amorphous oxides and outline some of the challenges in modeling defects in amorphous materials. We then discuss theoretical models of electron polarons and bi-polarons in a-HfO2 and demonstrate that these intrinsic states originate from low-coordinated ions and elongated metal-oxygen bonds in the amorphous oxide network. Similarly, holes can be captured at under-coordinated O sites. We then discuss electron and hole trapping in other amorphous oxides, such as a-SiO2, a-Al2O3, a-TiO2. We propose that the presence of low-coordinated ions in amorphous oxides with electron states of significant p and d character near the conduction band minimum can lead to electron trapping and that deep hole trapping should be common to all amorphous oxides. Finally, we demonstrate that bi-electron trapping in a-HfO2 and a-SiO2 weakens Hf(Si)–O bonds and significantly reduces barriers for forming Frenkel defects, neutral O vacancies and O2‑ ions in these materials. These results should be useful for better understanding of electronic properties and structural evolution of thin amorphous films under carrier injection

  7. Quasi-Linear Evolution of Trapped Electron Fluxes Under the Influence of Realistic Whistler-Mode Waves

    Science.gov (United States)

    Agapitov, O. V.; Mourenas, D.; Artemyev, A.; Krasnoselskikh, V.

    2014-12-01

    The evolution of fluxes of energetic trapped electrons as a function of geomagnetic activity is investigated using brand new statistical models of chorus waves derived from Cluster observations in the radiation belts. The new wave models provide the distributions of wave power and wave-normal angle with latitude as a function of either Dst or Kp indices. Lifetimes and energization of energetic electrons are examined, as well as the relevant uncertainties related to some of the wave models implicit assumptions.From the presented results, different implications concerning the characterization of relativistic flux enhancements and losses are provided.

  8. The range of attraction for light traps catching Culicoides biting midges (Diptera: Ceratopogonidae).

    Science.gov (United States)

    Kirkeby, Carsten; Græsbøll, Kaare; Stockmarr, Anders; Christiansen, Lasse E; Bødker, René

    2013-03-15

    Culicoides are vectors of e.g. bluetongue virus and Schmallenberg virus in northern Europe. Light trapping is an important tool for detecting the presence and quantifying the abundance of vectors in the field. Until now, few studies have investigated the range of attraction of light traps. Here we test a previously described mathematical model (Model I) and two novel models for the attraction of vectors to light traps (Model II and III). In Model I, Culicoides fly to the nearest trap from within a fixed range of attraction. In Model II Culicoides fly towards areas with greater light intensity, and in Model III Culicoides evaluate light sources in the field of view and fly towards the strongest. Model II and III incorporated the directionally dependent light field created around light traps with fluorescent light tubes. All three models were fitted to light trap collections obtained from two novel experimental setups in the field where traps were placed in different configurations. Results showed that overlapping ranges of attraction of neighboring traps extended the shared range of attraction. Model I did not fit data from any of the experimental setups. Model II could only fit data from one of the setups, while Model III fitted data from both experimental setups. The model with the best fit, Model III, indicates that Culicoides continuously evaluate the light source direction and intensity. The maximum range of attraction of a single 4W CDC light trap was estimated to be approximately 15.25 meters. The attraction towards light traps is different from the attraction to host animals and thus light trap catches may not represent the vector species and numbers attracted to hosts.

  9. Compression of Antiproton Clouds for Antihydrogen Trapping

    CERN Document Server

    Andresen, G B; Bowe, P D; Bray, C C; Butler, E; Cesar, C L; Chapman, S; Charlton, M; Fajans, J; Fujiwara, M C; Funakoshi, R; Gill, D R; Hangst, J S; Hardy, W N; Hayano, R S; Hayden, M E; Hydomako, R; Jenkins, M J; Jørgensen, L V; Kurchaninov, L; Lambo, R; Madsen, N; Nolan, P; Olchanski, K; Olin, A; Povilus, A; Pusa, P; Robicheaux, F; Sarid, E; Seif El Nasr, S; Silveira, D M; Storey, J W; Thompson, R I; Van der Werf, D P; Wurtele, J S; Yamazaki, Y

    2008-01-01

    Control of the radial profile of trapped antiproton clouds is critical to trapping antihydrogen. We report the first detailed measurements of the radial manipulation of antiproton clouds, including areal density compressions by factors as large as ten, by manipulating spatially overlapped electron plasmas. We show detailed measurements of the near-axis antiproton radial profile and its relation to that of the electron plasma.

  10. Direct observation of 0.57 eV trap-related RF output power reduction in AlGaN/GaN high electron mobility transistors

    Science.gov (United States)

    Arehart, A. R.; Sasikumar, A.; Rajan, S.; Via, G. D.; Poling, B.; Winningham, B.; Heller, E. R.; Brown, D.; Pei, Y.; Recht, F.; Mishra, U. K.; Ringel, S. A.

    2013-02-01

    This paper reports direct evidence for trap-related RF output power loss in GaN high electron mobility transistors (HEMTs) grown by metal organic chemical vapor deposition (MOCVD) through increased concentration of a specific electron trap at EC-0.57 eV that is located in the drain access region, as a function of accelerated life testing (ALT). The trap is detected by constant drain current deep level transient spectroscopy (CID-DLTS) and the CID-DLTS thermal emission time constant precisely matches the measured drain lag. Both drain lag and CID-DLTS measurements show this state to already exist in pre-stressed devices, which coupled with its strong increase in concentration as a function of stress in the absence of significant increases in concentrations of other detected traps, imply its role in causing degradation, in particular knee walkout. This study reveals EC-0.57 eV trap concentration tracks degradation induced by ALT for MOCVD-grown HEMTs supplied by several commercial and university sources. The results suggest this defect has a common source and may be a key degradation pathway in AlGaN/GaN HEMTs and/or an indicator to predict device lifetime.

  11. Correlation of interface states/border traps and threshold voltage shift on AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Tian-Li, E-mail: Tian-Li.Wu@imec.be; Groeseneken, Guido [imec, Kapeldreef 75, 3001 Leuven (Belgium); Department of Electrical Engineering, KU Leuven, Leuven (Belgium); Marcon, Denis; De Jaeger, Brice; Lin, H. C.; Franco, Jacopo; Stoffels, Steve; Van Hove, Marleen; Decoutere, Stefaan [imec, Kapeldreef 75, 3001 Leuven (Belgium); Bakeroot, Benoit [imec, Kapeldreef 75, 3001 Leuven (Belgium); Centre for Microsystems Technology, Ghent University, 9052 Gent (Belgium); Roelofs, Robin [ASM, Kapeldreef 75, 3001 Leuven (Belgium)

    2015-08-31

    In this paper, three electrical techniques (frequency dependent conductance analysis, AC transconductance (AC-g{sub m}), and positive gate bias stress) were used to evaluate three different gate dielectrics (Plasma-Enhanced Atomic Layer Deposition Si{sub 3}N{sub 4}, Rapid Thermal Chemical Vapor Deposition Si{sub 3}N{sub 4}, and Atomic Layer Deposition (ALD) Al{sub 2}O{sub 3}) for AlGaN/GaN Metal-Insulator-Semiconductor High-Electron-Mobility Transistors. From these measurements, the interface state density (D{sub it}), the amount of border traps, and the threshold voltage (V{sub TH}) shift during a positive gate bias stress can be obtained. The results show that the V{sub TH} shift during a positive gate bias stress is highly correlated to not only interface states but also border traps in the dielectric. A physical model is proposed describing that electrons can be trapped by both interface states and border traps. Therefore, in order to minimize the V{sub TH} shift during a positive gate bias stress, the gate dielectric needs to have a lower interface state density and less border traps. However, the results also show that the commonly used frequency dependent conductance analysis technique to extract D{sub it} needs to be cautiously used since the resulting value might be influenced by the border traps and, vice versa, i.e., the g{sub m} dispersion commonly attributed to border traps might be influenced by interface states.

  12. Electron scavenging in ethylene glycol-water glass at 4 and 77 K: scavenging of trapped vs mobile electrons. [. gamma. -rays, x radiation

    Energy Technology Data Exchange (ETDEWEB)

    Lin, D P; Kevan, L [Wayne State Univ., Detroit, Mich. (USA). Dept. of Chemistry; Steen, H B

    1976-01-01

    Electron scavenging efficiencies have been measured at 77 and 4 K in ethylene glycol-water glass for the following scavengers which span a 250-fold range of scavenger efficiencies at 77 K: HCl, NaNO/sub 3/ and K/sub 2/Cr0/sub 4/. The range of scavenging efficiencies decreases to 62 at 4 K with the largest relative change occurring for the less efficient scavengers. These results are suggested to be most consistent with a model in which scavenging occurs by tunneling from shallowly and deeply trapped electrons at 4 and 77 K, respectively.

  13. Dopant controlled trap-filling and conductivity enhancement in an electron-transport polymer

    Energy Technology Data Exchange (ETDEWEB)

    Higgins, Andrew, E-mail: aehiggin@princeton.edu, E-mail: kahn@princeton.edu; Kahn, Antoine, E-mail: aehiggin@princeton.edu, E-mail: kahn@princeton.edu [Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544-5263 (United States); Mohapatra, Swagat K.; Barlow, Stephen; Marder, Seth R. [Center for Organic Photonics and Electronics and School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400 (United States)

    2015-04-20

    Charge transport in organic semiconductors is often inhibited by the presence of tail states that extend into the band gap of a material and act as traps for charge carriers. This work demonstrates the passivation of acceptor tail states by solution processing of ultra-low concentrations of a strongly reducing air-stable organometallic dimer, the pentamethylrhodocene dimer, [RhCp*Cp]{sub 2}, into the electron transport polymer poly([N,N′-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide) -2,6-diyl]-alt-5,5′-(2,2′-bithiophene)), P(NDI{sub 2}OD-T{sub 2}). Variable-temperature current-voltage measurements of n-doped P(NDI{sub 2}OD-T{sub 2}) are presented with doping concentration varied through two orders of magnitude. Systematic variation of the doping parameter is shown to lower the activation energy for hopping transport and enhance film conductivity and electron mobility.

  14. Trapping, self-trapping and the polaron family

    International Nuclear Information System (INIS)

    Stoneham, A M; Gavartin, J; Shluger, A L; Kimmel, A V; Ramo, D Munoz; Roennow, H M; Aeppli, G; Renner, C

    2007-01-01

    The earliest ideas of the polaron recognized that the coupling of an electron to ionic vibrations would affect its apparent mass and could effectively immobilize the carrier (self-trapping). We discuss how these basic ideas have been generalized to recognize new materials and new phenomena. First, there is an interplay between self-trapping and trapping associated with defects or with fluctuations in an amorphous solid. In high dielectric constant oxides, like HfO 2 , this leads to oxygen vacancies having as many as five charge states. In colossal magnetoresistance manganites, this interplay makes possible the scanning tunnelling microscopy (STM) observation of polarons. Second, excitons can self-trap and, by doing so, localize energy in ways that can modify the material properties. Third, new materials introduce new features, with polaron-related ideas emerging for uranium dioxide, gate dielectric oxides, Jahn-Teller systems, semiconducting polymers and biological systems. The phonon modes that initiate self-trapping can be quite different from the longitudinal optic modes usually assumed to dominate. Fourth, there are new phenomena, like possible magnetism in simple oxides, or with the evolution of short-lived polarons, like muons or excitons. The central idea remains that of a particle whose properties are modified by polarizing or deforming its host solid, sometimes profoundly. However, some of the simpler standard assumptions can give a limited, indeed misleading, description of real systems, with qualitative inconsistencies. We discuss representative cases for which theory and experiment can be compared in detail

  15. EBIT trapping program

    International Nuclear Information System (INIS)

    Elliott, S.R.; Beck, B.; Beiersdorfer, P.; Church, D.; DeWitt, D.; Knapp, D.K.; Marrs, R.E.; Schneider, D.; Schweikhard, L.

    1993-01-01

    The LLNL electron beam ion trap provides the world's only source of stationary highly charged ions up to bare U. This unique capability makes many new atomic and nuclear physics experiments possible. (orig.)

  16. Electron self-trapped at molybdenum complex in lead molybdate: An EPRand TSL comparative study

    Czech Academy of Sciences Publication Activity Database

    Buryi, Maksym; Laguta, Valentyn; Fasoli, M.; Moretti, F.; Trubitsyn, M.; Volnianskii, M.; Vedda, A.; Nikl, Martin

    2017-01-01

    Roč. 192, Dec (2017), s. 767-774 ISSN 0022-2313 R&D Projects: GA MŠk LO1409; GA MŠk LM2015088; GA ČR GA17-09933S EU Projects: European Commission(XE) 690599 - ASCIMAT Institutional support: RVO:68378271 Keywords : EPR * wavelength resolved TSL * self-trapped electron * lead molybdate * molecular orbitals Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 2.686, year: 2016

  17. Effects of antimony (Sb) on electron trapping near SiO{sub 2}/4H-SiC interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Mooney, P. M.; Jiang, Zenan; Basile, A. F. [Physics Department, Simon Fraser University, Burnaby, British Columbia V5A 1S6 (Canada); Zheng, Yongju; Dhar, Sarit [Physics Department, Auburn University, Auburn, Alabama 36849 (United States)

    2016-07-21

    To investigate the mechanism by which Sb at the SiO{sub 2}/SiC interface improves the channel mobility of 4H-SiC MOSFETs, 1 MHz capacitance measurements and constant capacitance deep level transient spectroscopy (CCDLTS) measurements were performed on Sb-implanted 4H-SiC MOS capacitors. The measurements reveal a significant concentration of Sb donors near the SiO{sub 2}/SiC interface. Two Sb donor related CCDLTS peaks corresponding to shallow energy levels in SiC were observed close to the SiO{sub 2}/SiC interface. Furthermore, CCDLTS measurements show that the same type of near-interface traps found in conventional dry oxide or NO-annealed capacitors are present in the Sb implanted samples. These are O1 traps, suggested to be carbon dimers substituted for O dimers in SiO{sub 2}, and O2 traps, suggested to be interstitial Si in SiO{sub 2}. However, electron trapping is reduced by a factor of ∼2 in Sb-implanted samples compared with samples with no Sb, primarily at energy levels within 0.2 eV of the SiC conduction band edge. This trap passivation effect is relatively small compared with the Sb-induced counter-doping effect on the MOSFET channel surface, which results in improved channel transport.

  18. Foam flow in a model porous medium: II. The effect of trapped gas.

    Science.gov (United States)

    Jones, S A; Getrouw, N; Vincent-Bonnieu, S

    2018-05-09

    Gas trapping is an important mechanism in both Water or Surfactant Alternating Gas (WAG/SAG) and foam injection processes in porous media. Foams for enhanced oil recovery (EOR) can increase sweep efficiency as they decrease the gas relative permeability, and this is mainly due to gas trapping. However, gas trapping mechanisms are poorly understood. Some studies have been performed during corefloods, but little work has been carried out to describe the bubble trapping behaviour at the pore scale. We have carried out foam flow tests in a micromodel etched with an irregular hexagonal pattern. Image analysis of the foam flow allowed the bubble centres to be tracked and local velocities to be obtained. It was found that the flow in the micromodel is dominated by intermittency and localized zones of trapped gas. The quantity of trapped gas was measured both by considering the fraction of bubbles that were trapped (via velocity thresholding) and by measuring the area fraction containing immobile gas (via image analysis). A decrease in the quantity of trapped gas was observed for both increasing total velocity and increasing foam quality. Calculations of the gas relative permeability were made with the Brooks Corey equation, using the measured trapped gas saturations. The results showed a decrease in gas relative permeabilities, and gas mobility, for increasing fractions of trapped gas. It is suggested that the shear thinning behaviour of foam could be coupled to the saturation of trapped gas.

  19. Resilience of quasi-isodynamic stellarators against trapped-particle instabilities.

    Science.gov (United States)

    Proll, J H E; Helander, P; Connor, J W; Plunk, G G

    2012-06-15

    It is shown that in perfectly quasi-isodynamic stellarators, trapped particles with a bounce frequency much higher than the frequency of the instability are stabilizing in the electrostatic and collisionless limit. The collisionless trapped-particle instability is therefore stable as well as the ordinary electron-density-gradient-driven trapped-electron mode. This result follows from the energy balance of electrostatic instabilities and is thus independent of all other details of the magnetic geometry.

  20. Derivation of electron density and temperature from (S II) and (O II) line intensity ratios

    Energy Technology Data Exchange (ETDEWEB)

    Canto, J; Meaburn, J; Theokas, A C [Manchester Univ. (UK). Dept of Astronomy; Elliott, K H [Anglo-Australian Observatory, Epping (Australia)

    1980-12-01

    Line intensity ratios for (S II) and (O II) due to collisional de-excitation are briefly discussed. Comparison is made between various reaction rate parameters presented by separate investigators. Included are observations of ratios obtained from the Orion nebula which experimentally confirm the reaction rates of Pradhan as best representing the observed distribution of these ratios. (O II) and (S II) contour plots are also presented, which allow effective electron temperatures and densities to be estimated from pairs of line ratios.

  1. A pheromone-baited trap for monitoring the Indian meal moth, Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae).

    Science.gov (United States)

    Mullen, M A.; Dowdy, A K.

    2001-07-01

    A pheromone-baited trap was developed to monitor the Indian meal moth in grocery stores and similar areas where visible traps are not desirable. The trap can be used under shelves and against walls. As a shelf mount, the trap is in close proximity to the food packages and may capture emerging insects before they mate. The trap can also be used as a hanging trap similar to the Pherocon II. When used as a shelf or wall mount, it was as effective as the Pherocon II, but when used as a hanging trap significantly fewer insects were captured.

  2. Electron tunnelling in glassy media

    International Nuclear Information System (INIS)

    Marshall, E.J.; Pilling, M.J.; Rice, S.A.

    1975-01-01

    The efficiency of electron scavenging by a range of solute molecules in methanol, 2-methyltetrahydrofuran (MTHF) and 10mol dm -3 hydroxide glasses has been investigated by γ-radiolysis at 77K using spectrophotometric detection. The data have been analyzed using the recent theory of Dainton, Pilling and Rice (J.C.S. Faraday II; 71:1311 (1975)), and a satisfactory fit found. The trap depths for the thre systems are estimated to be 1.7eV (methanol), 1.0eV (MTHF) and 0.95eV (aq.hydroxide). A wide variation in the scavenging efficiency is tentatively ascribed to the differing geometries of the scavenger molecules. For MTHF and 10mol dm -3 hydroxide glasses, the efficiency of scavenging is independent of wave-length, suggesting that the width of the electron spectrum is not due to a range of trap depths. (author)

  3. Effect of OFF-state stress induced electric field on trapping in AlGaN/GaN high electron mobility transistors on Si (111)

    Science.gov (United States)

    Anand, M. J.; Ng, G. I.; Arulkumaran, S.; Manoj Kumar, C. M.; Ranjan, K.; Vicknesh, S.; Foo, S. C.; Syamal, B.; Zhou, X.

    2015-02-01

    The influence of electric field (EF) on the dynamic ON-resistance (dyn-RDS[ON]) and threshold-voltage shift (ΔVth) of AlGaN/GaN high electron mobility transistors on Si has been investigated using pulsed current-voltage (IDS-VDS) and drain current (ID) transients. Different EF was realized with devices of different gate-drain spacing (Lgd) under the same OFF-state stress. Under high-EF (Lgd = 2 μm), the devices exhibited higher dyn-RDS[ON] degradation but a small ΔVth (˜120 mV). However, at low-EF (Lgd = 5 μm), smaller dyn-RDS[ON] degradation but a larger ΔVth (˜380 mV) was observed. Our analysis shows that under OFF-state stress, the gate electrons are injected and trapped in the AlGaN barrier by tunnelling-assisted Poole-Frenkel conduction mechanism. Under high-EF, trapping spreads towards the gate-drain access region of the AlGaN barrier causing dyn-RDS[ON] degradation, whereas under low-EF, trapping is mostly confined under the gate causing ΔVth. A trap with activation energy 0.33 eV was identified in the AlGaN barrier by ID-transient measurements. The influence of EF on trapping was also verified by Silvaco TCAD simulations.

  4. MRI diagnosis of trapped periosteum following incomplete closed reduction of distal tibial Salter-Harris II fracture

    International Nuclear Information System (INIS)

    Raman, Subha; Wallace, E.C.

    2011-01-01

    Irreducible fracture of the distal tibial physis due to interposed soft tissue including periosteum is well documented in the orthopedic literature but is uncommon. This condition has been associated with subsequent growth disturbance and requires open reduction. There are very few prior reports of MRI depiction of soft tissue interposition and none of periosteal interposition in the distal tibial physis. This is a relatively common location of physeal injury and related growth disturbance. We present a case of periosteum trapped in the distal tibial physis, diagnosed on MRI, in a Salter-Harris II fracture and its management implications. (orig.)

  5. Copper(II) Thiosemicarbazone Complexes and Their Proligands upon UVA Irradiation: An EPR and Spectrophotometric Steady-State Study.

    Science.gov (United States)

    Hricovíni, Michal; Mazúr, Milan; Sîrbu, Angela; Palamarciuc, Oleg; Arion, Vladimir B; Brezová, Vlasta

    2018-03-21

    X- and Q-band electron paramagnetic resonance (EPR) spectroscopy was used to characterize polycrystalline Cu(II) complexes that contained sodium 5-sulfonate salicylaldehyde thiosemicarbazones possessing a hydrogen, methyl, ethyl, or phenyl substituent at the terminal nitrogen. The ability of thiosemicarbazone proligands to generate superoxide radical anions and hydroxyl radicals upon their exposure to UVA irradiation in aerated aqueous solutions was evidenced by the EPR spin trapping technique. The UVA irradiation of proligands in neutral or alkaline solutions and dimethylsulfoxide (DMSO) caused a significant decrease in the absorption bands of aldimine and phenolic chromophores. Mixing of proligand solutions with the equimolar amount of copper(II) ions resulted in the formation of 1:1 Cu(II)-to-ligand complex, with the EPR and UV-Vis spectra fully compatible with those obtained for the dissolved Cu(II) thiosemicarbazone complexes. The formation of the complexes fully inhibited the photoinduced generation of reactive oxygen species, and only subtle changes were found in the electronic absorption spectra of the complexes in aqueous and DMSO solutions upon UVA steady-state irradiation. The dark redox activity of copper(II) complexes and proligand/Cu(II) aqueous solutions towards hydrogen peroxide which resulted in the generation of hydroxyl radicals, was confirmed by spin trapping experiments.

  6. Variation of carrier concentration and interface trap density in 8MeV electron irradiated c-Si solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Bhat, Sathyanarayana, E-mail: asharao76@gmail.com; Rao, Asha, E-mail: asharao76@gmail.com [Department of Physics, Mangalore Institute of Technology and Engineering, Moodabidri, Mangalore-574225 (India); Krishnan, Sheeja [Department of Physics, Sri Devi Institute of Technology, Kenjar, Mangalore-574142 (India); Sanjeev, Ganesh [Microtron Centre, Department of Physics, Mangalore University, Mangalagangothri-574199 (India); Suresh, E. P. [Solar Panel Division, ISRO Satellite Centre, Bangalore-560017 (India)

    2014-04-24

    The capacitance and conductance measurements were carried out for c-Si solar cells, irradiated with 8 MeV electrons with doses ranging from 5kGy – 100kGy in order to investigate the anomalous degradation of the cells in the radiation harsh environments. Capacitance – Voltage measurements indicate that there is a slight reduction in the carrier concentration upon electron irradiation due to the creation of radiation induced defects. The conductance measurement results reveal that the interface state densities and the trap time constant increases with electron dose due to displacement damages in c-Si solar cells.

  7. Progress toward magnetic confinement of a positron-electron plasma: nearly 100% positron injection efficiency into a dipole trap

    Science.gov (United States)

    Stoneking, Matthew

    2017-10-01

    The hydrogen atom provides the simplest system and in some cases the most precise one for comparing theory and experiment in atomics physics. The field of plasma physics lacks an experimental counterpart, but there are efforts underway to produce a magnetically confined positron-electron plasma that promises to represent the simplest plasma system. The mass symmetry of positron-electron plasma makes it particularly tractable from a theoretical standpoint and many theory papers have been published predicting modified wave and stability properties in these systems. Our approach is to utilize techniques from the non-neutral plasma community to trap and accumulate electrons and positrons prior to mixing in a magnetic trap with good confinement properties. Ultimately we aim to use a levitated superconducting dipole configuration fueled by positrons from a reactor-based positron source and buffer-gas trap. To date we have conducted experiments to characterize and optimize the positron beam and test strategies for injecting positrons into the field of a supported permanent magnet by use of ExB drifts and tailored static and dynamic potentials applied to boundary electrodes and to the magnet itself. Nearly 100% injection efficiency has been achieved under certain conditions and some fraction of the injected positrons are confined for as long as 400 ms. These results are promising for the next step in the project which is to use an inductively energized high Tc superconducting coil to produce the dipole field, initially in a supported configuration, but ultimately levitated using feedback stabilization. Work performed with the support of the German Research Foundation (DFG), JSPS KAKENHI, NIFS Collaboration Research Program, and the UCSD Foundation.

  8. Deuterium trapping in tungsten

    Science.gov (United States)

    Poon, Michael

    irradiation. Deuterium trapping could be characterized by three regimes: (i) enhanced D retention in a graphitic film formed by the C+ irradiation; (ii) decreased D retention in a modified tungsten-carbon layer; and (iii) D retention in pure tungsten.

  9. Deuterium trapping in tungsten

    International Nuclear Information System (INIS)

    Poon, M.

    2004-01-01

    irradiation Deuterium trapping could be characterized by three regimes: (i) enhanced D retention in a graphitic film formed by the C + irradiation ; (ii) decreased D retention in a modified tungsten-carbon layer; and (iii) D retention in pure tungsten. (author)

  10. Deuterium trapping in tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Poon, M

    2004-07-01

    irradiation Deuterium trapping could be characterized by three regimes: (i) enhanced D retention in a graphitic film formed by the C{sup +} irradiation ; (ii) decreased D retention in a modified tungsten-carbon layer; and (iii) D retention in pure tungsten. (author)

  11. Nonlinear theory of trapped electron temperature gradient driven turbulence in flat density H-mode plasmas

    International Nuclear Information System (INIS)

    Hahm, T.S.

    1990-12-01

    Ion temperature gradient turbulence based transport models have difficulties reconciling the recent DIII-D H-mode results where the density profile is flat, but χ e > χ i in the core region. In this work, a nonlinear theory is developed for recently discovered ion temperature gradient trapped electron modes propagating in the electron diamagnetic direction. This instability is predicted to be linearly unstable for L Ti /R approx-lt κ θ ρ s approx-lt (L Ti /R) 1/4 . They are also found to be strongly dispersive even at these long wavelengths, thereby suggesting the importance of the wave-particle-wave interactions in the nonlinear saturation phase. The fluctuation spectrum and anomalous fluxes are calculated. In accordance with the trends observed in DIII-D, the predicted electron thermal diffusivity can be larger than the ion thermal diffusivity. 17 refs., 3 figs

  12. Status of THe-Trap

    Energy Technology Data Exchange (ETDEWEB)

    Streubel, Sebastian; Eronen, Tommi; Hoecker, Martin; Ketter, Jochen; Blaum, Klaus [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Van Dyck, Robert S. Jr. [Department of Physics, University of Washington, Seattle, WA (United States)

    2013-07-01

    THe-Trap (short for Tritium-{sup 3}He Trap) is a Penning-trap setup dedicated to measure the {sup 3}H to {sup 3}He mass-ratio with a relative uncertainty of better than 10{sup -11}. The ratio is of relevance for the KArlsruhe TRItium Neutrino experiment (KATRIN), which aims to measure the electron anti-neutrino mass, by measuring the shape of the β-decay energy spectrum close to its endpoint. An independent measurement of the {sup 3}H to {sup 3}He mass-ratio pins down this endpoint, and thus will help to determine the systematics of KATRIN. The trap setup consists of two Penning-traps: One trap for precision measurements, the other trap for ion storage. Ideally, the trap content will be periodically switched, which reduces the time between the measurements of the two ions' motional frequencies. In 2012, a mass ratio measurement of {sup 12}C{sup 4+} to {sup 14}N{sup 5+} was performed to characterize systematic effects of the traps. This measurement yielded a accuracy of 10{sup -9}. Further investigations revealed that a major reason for the modest accuracy is the large axial amplitude of ∼100 μm, compared to a ideal case of 3 μm at 4 K. In addition, relative magnetic fluctuations at a 3 x 10{sup -10} level on a 10 h timescale need to be significantly improved. In this contribution, the aforementioned findings and further systematic studies will be presented.

  13. Status of THe-trap

    Energy Technology Data Exchange (ETDEWEB)

    Ketter, Jochen; Eronen, Tommi; Hoecker, Martin; Streubel, Sebastian; Blaum, Klaus [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Van Dyck, Robert S. Jr. [Department of Physics, University of Washington, Seattle, WA (United States)

    2012-07-01

    Originally developed at the University of Washington and relocated to the Max-Planck-Institut fuer Kernphysik in 2008, the Penning-trap spectrometer THe-Trap is specially tailored for a {sup 3}H/{sup 3}He mass-ratio measurement, from which the Q-value of the beta-decay of {sup 3}H to {sup 3}He can be derived. Improving the current best value by at least an order of magnitude will provide an important independent test parameter for the determination of the electron-antineutrino's mass by the Karlsruhe Tritium Neutrino Experiment (KATRIN). However, Penning-trap mass spectrometry has to be pushed to its limits in a dedicated experiment for a sufficiently accurate mass-ratio measurement with a relative uncertainty of 10{sup -11}. Unlike the closed-envelope, single-trap predecessor, the new spectrometer features an external ion source, owing to the radioactive nature of tritium, and two traps in order to speed up the measurement cycle. While the double-trap technique holds great promise, it also calls for more intricate procedures, such as ion transfer. Details about the recent progress of the experiment are given.

  14. Localization of ionization-induced trapping in a laser wakefield accelerator using a density down-ramp

    CERN Document Server

    Hansson, M.; Ekerfelt, H.; Aurand, B.; Gallardo Ganzalez, I.; Desforges, F. G.; Davoine, X.; Maitrallain, A.; Reymond, S.; Monot, P.; Persson, A.; Dobosz Dufrénoy S.; Wahlström C-G.; Cros, B.; Lundh, O.

    2016-01-01

    We report on a study on controlled trapping of electrons, by field ionization of nitrogen ions, in laser wakefield accelerators in variable length gas cells. In addition to ionization-induced trapping in the density plateau inside the cells, which results in wide, but stable, electron energy spectra, a regime of ionization-induced trapping localized in the density down-ramp at the exit of the gas cells, is found. The resulting electron energy spectra are peaked, with 10% shot-to-shot fluctuations in peak energy. Ionization-induced trapping of electrons in the density down-ramp is a way to trap and accelerate a large number of electrons, thus improving the efficiency of the laser-driven wakefield acceleration.

  15. Electron spin resonance of nitrogen-vacancy centers in optically trapped nanodiamonds

    Science.gov (United States)

    Horowitz, Viva R.; Alemán, Benjamín J.; Christle, David J.; Cleland, Andrew N.; Awschalom, David D.

    2012-01-01

    Using an optical tweezers apparatus, we demonstrate three-dimensional control of nanodiamonds in solution with simultaneous readout of ground-state electron-spin resonance (ESR) transitions in an ensemble of diamond nitrogen-vacancy color centers. Despite the motion and random orientation of nitrogen-vacancy centers suspended in the optical trap, we observe distinct peaks in the measured ESR spectra qualitatively similar to the same measurement in bulk. Accounting for the random dynamics, we model the ESR spectra observed in an externally applied magnetic field to enable dc magnetometry in solution. We estimate the dc magnetic field sensitivity based on variations in ESR line shapes to be approximately . This technique may provide a pathway for spin-based magnetic, electric, and thermal sensing in fluidic environments and biophysical systems inaccessible to existing scanning probe techniques. PMID:22869706

  16. Performance improvement of charge trap flash memory by using a composition-modulated high-k trapping layer

    International Nuclear Information System (INIS)

    Tang Zhen-Jie; Li Rong; Yin Jiang

    2013-01-01

    A composition-modulated (HfO 2 ) x (Al 2 O3) 1−x charge trapping layer is proposed for charge trap flash memory by controlling the Al atom content to form a peak and valley shaped band gap. It is found that the memory device using the composition-modulated (HfO 2 ) x (Al 2 O 3 ) 1−x as the charge trapping layer exhibits a larger memory window of 11.5 V, improves data retention even at high temperature, and enhances the program/erase speed. Improvements of the memory characteristics are attributed to the special band-gap structure resulting from the composition-modulated trapping layer. Therefore, the composition-modulated charge trapping layer may be useful in future nonvolatile flash memory device application. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  17. Intensity dependent waiting time for strong electron trapping events in speckle stimulated raman scatter

    Energy Technology Data Exchange (ETDEWEB)

    Rose, Harvey [Los Alamos National Laboratory; Daughton, W [Los Alamos National Laboratory; Yin, L [Los Alamos National Laboratory

    2009-01-01

    The onset of Stimulated Raman scatter from an intense laser speckle is the simplest experimentally realizable laser-plasma-interaction environment. Despite this data and recent 3D particle simulations, the controlling mechanism at the onset of backscatter in the kinetic regime when strong electron trapping in the daughter Langmuir wave is a dominant nonlinearity is not understood. This paper explores the consequences of assuming that onset is controlled by large thermal fluctuations. A super exponential dependence of mean reflectivity on speckle intensity in the onset regime is predicted.

  18. Laser induced fluorescence of trapped molecular ions

    Energy Technology Data Exchange (ETDEWEB)

    Grieman, F.J.

    1979-10-01

    An experimental apparatus for obtaining the optical spectra of molecular ions is described. The experimental technique includes the use of three dimensional ion trapping, laser induced fluorescence, and gated photon counting methods. The ions, which are produced by electron impact, are confined in a radio-frequency quadrupole ion trap of cylindrical design. Because the quadrupole ion trap allows mass selection of the molecular ion desired for study, the analysis of the spectra obtained is greatly simplified. The ion trap also confines the ions to a region easily probed by a laser beam. 18 references.

  19. Laser induced fluorescence of trapped molecular ions

    International Nuclear Information System (INIS)

    Grieman, F.J.

    1979-10-01

    An experimental apparatus for obtaining the optical spectra of molecular ions is described. The experimental technique includes the use of three dimensional ion trapping, laser induced fluorescence, and gated photon counting methods. The ions, which are produced by electron impact, are confined in a radio-frequency quadrupole ion trap of cylindrical design. Because the quadrupole ion trap allows mass selection of the molecular ion desired for study, the analysis of the spectra obtained is greatly simplified. The ion trap also confines the ions to a region easily probed by a laser beam. 18 references

  20. In-trap decay spectroscopy for {beta}{beta} decays

    Energy Technology Data Exchange (ETDEWEB)

    Brunner, Thomas

    2011-01-18

    The presented work describes the implementation of a new technique to measure electron-capture (EC) branching ratios (BRs) of intermediate nuclei in {beta}{beta} decays. This technique has been developed at TRIUMF in Vancouver, Canada. It facilitates one of TRIUMF's Ion Traps for Atomic and Nuclear science (TITAN), the Electron Beam Ion Trap (EBIT) that is used as a spectroscopy Penning trap. Radioactive ions, produced at the radioactive isotope facility ISAC, are injected and stored in the spectroscopy Penning trap while their decays are observed. A key feature of this technique is the use of a strong magnetic field, required for trapping. It radially confines electrons from {beta} decays along the trap axis while X-rays, following an EC, are emitted isotropically. This provides spatial separation of X-ray and {beta} detection with almost no {beta}-induced background at the X-ray detector, allowing weak EC branches to be measured. Furthermore, the combination of several traps allows one to isobarically clean the sample prior to the in-trap decay spectroscopy measurement. This technique has been developed to measure ECBRs of transition nuclei in {beta}{beta} decays. Detailed knowledge of these electron capture branches is crucial for a better understanding of the underlying nuclear physics in {beta}{beta} decays. These branches are typically of the order of 10{sup -5} and therefore difficult to measure. Conventional measurements suffer from isobaric contamination and a dominating {beta} background at theX-ray detector. Additionally, X-rays are attenuated by the material where the radioactive sample is implanted. To overcome these limitations, the technique of in-trap decay spectroscopy has been developed. In this work, the EBIT was connected to the TITAN beam line and has been commissioned. Using the developed beam diagnostics, ions were injected into the Penning trap and systematic studies on injection and storage optimization were performed. Furthermore, Ge

  1. In-trap decay spectroscopy for ββ decays

    International Nuclear Information System (INIS)

    Brunner, Thomas

    2011-01-01

    The presented work describes the implementation of a new technique to measure electron-capture (EC) branching ratios (BRs) of intermediate nuclei in ββ decays. This technique has been developed at TRIUMF in Vancouver, Canada. It facilitates one of TRIUMF's Ion Traps for Atomic and Nuclear science (TITAN), the Electron Beam Ion Trap (EBIT) that is used as a spectroscopy Penning trap. Radioactive ions, produced at the radioactive isotope facility ISAC, are injected and stored in the spectroscopy Penning trap while their decays are observed. A key feature of this technique is the use of a strong magnetic field, required for trapping. It radially confines electrons from β decays along the trap axis while X-rays, following an EC, are emitted isotropically. This provides spatial separation of X-ray and β detection with almost no β-induced background at the X-ray detector, allowing weak EC branches to be measured. Furthermore, the combination of several traps allows one to isobarically clean the sample prior to the in-trap decay spectroscopy measurement. This technique has been developed to measure ECBRs of transition nuclei in ββ decays. Detailed knowledge of these electron capture branches is crucial for a better understanding of the underlying nuclear physics in ββ decays. These branches are typically of the order of 10 -5 and therefore difficult to measure. Conventional measurements suffer from isobaric contamination and a dominating β background at theX-ray detector. Additionally, X-rays are attenuated by the material where the radioactive sample is implanted. To overcome these limitations, the technique of in-trap decay spectroscopy has been developed. In this work, the EBIT was connected to the TITAN beam line and has been commissioned. Using the developed beam diagnostics, ions were injected into the Penning trap and systematic studies on injection and storage optimization were performed. Furthermore, Ge detectors, for the detection of X-rays, were

  2. Temperature dependence of photoluminescence spectra of bilayer two-dimensional electron gases in LaAlO3/SrTiO3 superlattices: coexistence of Auger recombination and single-carrier trapping

    Directory of Open Access Journals (Sweden)

    H. J. Harsan Ma

    2015-06-01

    Full Text Available We report emerging photoluminescence (PL of bilayer two-dimensional electron gases (2DEG in LaAlO3/SrTiO3 (LAO/STO systems. A strong blue PL emerges in bilayer-2DEGs in LAO/STO/LAO/STO which doesn’t show in LAO/STO. PL band in bilayer-2DEGs includes both nearly temperature independent Auger recombination and temperature dependent free electron trapping while it crossovers from Auger recombination to single carrier trapping in LAO/STO. The PL signal of free electron trapping appears at high temperatures and it is much stronger than Auger recombination in the conducting channel in bilayer 2DEGs. This observation shows that high mobility carriers dominate the carrier dynamics in bilayer-2DEGs in LAO/STO superlattices.

  3. Electron transfer reactions of ruthenium(II) complexes with polyphenolic acids in micelles

    Energy Technology Data Exchange (ETDEWEB)

    Rajeswari, Angusamy [School of Chemistry, Madurai Kamaraj University, Madurai 625 021 (India); Department of Chemistry, Fatima College, Madurai 625 018 (India); Ramdass, Arumugam [School of Chemistry, Madurai Kamaraj University, Madurai 625 021 (India); Research Department of Chemistry, Aditanar College of Arts and Science, Tiruchendur 628 216 (India); Muthu Mareeswaran, Paulpandian [School of Chemistry, Madurai Kamaraj University, Madurai 625 021 (India); Department of Industrial Chemistry, Alagappa University, Karaikudi 630 003 (India); Rajagopal, Seenivasan, E-mail: rajagopalseenivasan@yahoo.com [School of Chemistry, Madurai Kamaraj University, Madurai 625 021 (India)

    2016-02-15

    The electron transfer in a microhetrogeneous system is a perfect mimic of biological electron transfer. The electron transfer between biologically important phenolic acids and ruthenium (II) complexes is systematically studied in the presence of anionic and cationic micelles. The photophysical properties of these ruthenium (II) complexes with anionic and cationic micelles and their binding abilities with these two type of micelles are also studies using absorption, emission and excited state lifetime spectral techniques. Pseudophase Ion Exchange (PIE) Model is applied to derive mechanism of electron transfer in two types of micelles. - Highlights: • Effect of microhetrogeneous system is studied using ruthenium (II) complexes and gallic acid is studied. • Pseudophase Ion exchange model is applied to derive the mechanism. • Binding constants are in the range of 10{sup 2}–10{sup 4} M{sup −1}.

  4. The range of attraction for light traps catching Culicoides biting midges (Diptera: Ceratopogonidae)

    DEFF Research Database (Denmark)

    Kirkeby, Carsten; Græsbøll, Kaare; Stockmarr, Anders

    2013-01-01

    Background Culicoides are vectors of e.g. bluetongue virus and Schmallenberg virus in northern Europe. Light trapping is an important tool for detecting the presence and quantifying the abundance of vectors in the field. Until now, few studies have investigated the range of attraction of light tr...... light trap was estimated to be approximately 15.25 meters. The attraction towards light traps is different from the attraction to host animals and thus light trap catches may not represent the vector species and numbers attracted to hosts.......Background Culicoides are vectors of e.g. bluetongue virus and Schmallenberg virus in northern Europe. Light trapping is an important tool for detecting the presence and quantifying the abundance of vectors in the field. Until now, few studies have investigated the range of attraction of light...... traps. Methods Here we test a previously described mathematical model (Model I) and two novel models for the attraction of vectors to light traps (Model II and III). In Model I, Culicoides fly to the nearest trap from within a fixed range of attraction. In Model II Culicoides fly towards areas...

  5. Toward Rechargeable Persistent Luminescence for the First and Third Biological Windows via Persistent Energy Transfer and Electron Trap Redistribution.

    Science.gov (United States)

    Xu, Jian; Murata, Daisuke; Ueda, Jumpei; Viana, Bruno; Tanabe, Setsuhisa

    2018-05-07

    Persistent luminescence (PersL) imaging without real-time external excitation has been regarded as the next generation of autofluorescence-free optical imaging technology. However, to achieve improved imaging resolution and deep tissue penetration, developing new near-infrared (NIR) persistent phosphors with intense and long duration PersL over 1000 nm is still a challenging but urgent task in this field. Herein, making use of the persistent energy transfer process from Cr 3+ to Er 3+ , we report a novel garnet persistent phosphor of Y 3 Al 2 Ga 3 O 12 codoped with Er 3+ and Cr 3+ (YAG G:Er-Cr), which shows intense Cr 3+ PersL (∼690 nm) in the deep red region matching well with the first biological window (NIR-I, 650-950 nm) and Er 3+ PersL (∼1532 nm) in the NIR region matching well with the third biological window (NIR-III, 1500-1800 nm). The optical imaging through raw-pork tissues (thickness of 1 cm) suggests that the emission band of Er 3+ can achieve higher spatial resolution and more accurate signal location than that of Cr 3+ due to the reduced light scattering at longer wavelengths. Furthermore, by utilizing two independent electron traps with two different trap depths in YAG G:Er-Cr, the Cr 3+ /Er 3+ PersL can even be recharged in situ by photostimulation with 660 nm LED thanks to the redistribution of trapped electrons from the deep trap to the shallow one. Our results serve as a guide in developing promising NIR (>1000 nm) persistent phosphors for long-term optical imaging.

  6. The NSSDC trapped radiation model facility

    International Nuclear Information System (INIS)

    Gaffey, J.D. Jr.; Bilitza, D.

    1990-01-01

    The National Space Science Data Center (NSSDC) trapped radiation models calculate the integral and differential electron and proton flux for given values of the particle energy E, drift shell parameter L, and magnetic field strength B for either solar maximum or solar minimum. The most recent versions of the series of models, which have been developed and continuously improved over several decades by Dr. James Vette and coworkers at NSSDC, are AE-8 for electrons and AP-8 for protons. The present status of the NSSDC trapped particle models is discussed. The limits of validity of the models are described. 17 refs

  7. Ion traps fabricated in a CMOS foundry

    Energy Technology Data Exchange (ETDEWEB)

    Mehta, K. K.; Ram, R. J. [Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Eltony, A. M.; Chuang, I. L. [Center for Ultracold Atoms, Research Laboratory of Electronics and Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Bruzewicz, C. D.; Sage, J. M., E-mail: jsage@ll.mit.edu; Chiaverini, J., E-mail: john.chiaverini@ll.mit.edu [Lincoln Laboratory, Massachusetts Institute of Technology, Lexington, Massachusetts 02420 (United States)

    2014-07-28

    We demonstrate trapping in a surface-electrode ion trap fabricated in a 90-nm CMOS (complementary metal-oxide-semiconductor) foundry process utilizing the top metal layer of the process for the trap electrodes. The process includes doped active regions and metal interconnect layers, allowing for co-fabrication of standard CMOS circuitry as well as devices for optical control and measurement. With one of the interconnect layers defining a ground plane between the trap electrode layer and the p-type doped silicon substrate, ion loading is robust and trapping is stable. We measure a motional heating rate comparable to those seen in surface-electrode traps of similar size. This demonstration of scalable quantum computing hardware utilizing a commercial CMOS process opens the door to integration and co-fabrication of electronics and photonics for large-scale quantum processing in trapped-ion arrays.

  8. Investigation of trap states in high Al content AlGaN/GaN high electron mobility transistors by frequency dependent capacitance and conductance analysis

    International Nuclear Information System (INIS)

    Zhu, Jie-Jie; Ma, Xiao-Hua; Hou, Bin; Chen, Wei-Wei; Hao, Yue

    2014-01-01

    Trap states in Al 0.55 Ga 0.45 N/GaN Schottky-gate high-electron-mobility transistors (S-HEMTs) and Al 2 O 3 /Al 0.55 Ga 0.45 N/GaN metal-oxide-semiconductor HEMTs (MOS-HEMTs) were investigated with conductance method in this paper. Surface states with time constant of (0.09–0.12) μs were found in S-HEMTs, and electron tunneling rather than emission was deemed to be the dominant de-trapping mechanism due to the high electric field in high Al content barrier. The density of surface states evaluated in S-HEMTs was (1.02–4.67)×10 13 eV −1 ·cm −2 . Al 2 O 3 gate insulator slightly reduced the surface states, but introduced low density of new traps with time constant of (0.65–1.29) μs into MOS-HEMTs

  9. MOS Capacitance—Voltage Characteristics III. Trapping Capacitance from 2-Charge-State Impurities

    International Nuclear Information System (INIS)

    Jie Binbin; Sah Chihtang

    2011-01-01

    Low-frequency and high-frequency capacitance—voltage curves of Metal—Oxide—Semiconductor Capacitors are presented to illustrate giant electron and hole trapping capacitances at many simultaneously present two-charge-state and one-trapped-carrier, or one-energy-level impurity species. Models described include a donor electron trap and an acceptor hole trap, both donors, both acceptors, both shallow energy levels, both deep, one shallow and one deep, and the identical donor and acceptor. Device and material parameters are selected to simulate chemically and physically realizable capacitors for fundamental trapping parameter characterizations and for electrical and optical signal processing applications. (invited papers)

  10. Hybrid (Vlasov-Fluid) simulation of ion-acoustic solitons chain formation including trapped electrons

    Energy Technology Data Exchange (ETDEWEB)

    Behjat, E.; Aminmansoor, F.; Abbasi, H. [Faculty of Energy Engineering and Physics, Amirkabir University of Technology, P. O. Box 15875-4413, Tehran (Iran, Islamic Republic of)

    2015-08-15

    Disintegration of a Gaussian profile into ion-acoustic solitons in the presence of trapped electrons [H. Hakimi Pajouh and H. Abbasi, Phys. Plasmas 15, 082105 (2008)] is revisited. Through a hybrid (Vlasov-Fluid) model, the restrictions associated with the simple modified Korteweg de-Vries (mKdV) model are studied. For instance, the lack of vital information in the phase space associated with the evolution of electron velocity distribution, the perturbative nature of mKdV model which limits it to the weak nonlinear cases, and the special spatio-temporal scaling based on which the mKdV is derived. Remarkable differences between the results of the two models lead us to conclude that the mKdV model can only monitor the general aspects of the dynamics, and the precise picture including the correct spatio-temporal scales and the properties of solitons should be studied within the framework of hybrid model.

  11. Overview of the current spectroscopy effort on the Livermore electron beam ion traps

    International Nuclear Information System (INIS)

    Beiersdorfer, P.; Lopez-Urrutia, J.C.; Brown, G.

    1995-01-01

    An overview is given of the current spectroscopic effort on the Livermore electron beam ion trap facilities. The effort focuses on four aspects: spectral line position, line intensity, temporal evolution, and line shape. Examples of line position measurements include studies of the K-shell transitions in heliumlike Kr 34+ and the 2s-2p intrashell transitions in lithiumlike Th 87+ and U 89+ , which provide benchmark values for testing the theory of relativistic and quantum electrodynamical contributions in high-Z ions. Examples of line intensity measurements are provided by measurements of the electron-impact excitation and dielectronic recombination cross sections of heliumlike transition-metal ions Ti 20+ through CO 25+ . A discussion of radiative lifetime measurements of metastable levels in heliumlike ions is given to illustrate the time-resolved spectroscopy techniques in the microsecond range. The authors also present a measurement of the spectral lineshape that illustrates the very low ion temperatures that can be achieved in an EBIT

  12. Cooling and trapping neutral atoms with radiative forces

    International Nuclear Information System (INIS)

    Bagnato, V.S.; Castro, J.C.; Li, M.S.; Zilio, S.C.

    1988-01-01

    Techniques to slow and trap neutral atoms at high densities with radiative forces are discussed in this review articles. Among several methods of laser cooling, it is emphasized Zeeman Tuning of the electronic levels and frequency-sweeping techniques. Trapping of neutral atoms and recent results obtained in light and magnetic traps are discussed. Techniques to further cool atoms inside traps are presented and the future of laser cooling of neutral atoms by means of radiation pressure is discussed. (A.C.A.S.) [pt

  13. A Solid Trap and Thermal Desorption System with Application to a Medical Electronic Nose

    Directory of Open Access Journals (Sweden)

    Xuntao Xu

    2008-11-01

    Full Text Available In this paper, a solid trap/thermal desorption-based odorant gas condensation system has been designed and implemented for measuring low concentration odorant gas. The technique was successfully applied to a medical electronic nose system. The developed system consists of a flow control unit, a temperature control unit and a sorbent tube. The theoretical analysis and experimental results indicate that gas condensation, together with the medical electronic nose system can significantly reduce the detection limit of the nose system and increase the system’s ability to distinguish low concentration gas samples. In addition, the integrated system can remove the influence of background components and fluctuation of operational environment. Even with strong disturbances such as water vapour and ethanol gas, the developed system can classify the test samples accurately.

  14. Pumped helium system for cooling positron and electron traps to 1.2 K

    CERN Document Server

    Wrubel, J; Kolthammer, W S; Larochelle, P; McConnell, R; Richerme, P; Grzonka, D; Oelert, W; Sefzick, T; Zielinski, M; Borbely, J S; George, M C; Hessels, E A; Storry, C H; Weel, M; Mullers, A; Walz, J; Speck, A

    2011-01-01

    Extremely precise tests of fundamental particle symmetries should be possible via laser spectroscopy of trapped antihydrogen ((H) over bar) atoms. (H) over bar atoms that can be trapped must have an energy in temperature units that is below 0.5 K-the energy depth of the deepest magnetic traps that can currently be constructed with high currents and superconducting technology. The number of atoms in a Boltzmann distribution with energies lower than this trap depth depends sharply upon the temperature of the thermal distribution. For example, ten times more atoms with energies low enough to be trapped are in a thermal distribution at a temperature of 1.2 K than for a temperature of 4.2 K. To date, (H) over bar atoms have only been produced within traps whose electrode temperature is 4.2 K or higher. A lower temperature apparatus is desirable if usable numbers of atoms that can be trapped are to eventually be produced. This report is about the pumped helium apparatus that cooled the trap electrodes of an (H) ove...

  15. Trapped Mode Study in the LHC Rotatable Collimator

    CERN Document Server

    Xiao, L; Smith, J C; Caspers, F

    2010-01-01

    A rotatable collimator is proposed for the LHC phase II collimation upgrade. When the beam crosses the collimator, trapped modes will be excited that result in beam energy loss and collimator power dissipation. Some of the trapped modes can also generate transverse kick on the beam and affect the beam operation. In this paper the parallel eigensolver code Omega3P is used to search for all the trapped modes below 2GHz in the collimator, including longitudinal modes and transverse modes. The loss factors and kick factors of the trapped modes are calculated as function of the jaw positions. The amplitude ratio between transverse and longitudinal trapped mode intensity can be used as a direct measure of the position of the beam. We present simulation results and discuss the results.

  16. Influence of the variation potential on photosynthetic flows of light energy and electrons in pea.

    Science.gov (United States)

    Sukhova, Ekaterina; Mudrilov, Maxim; Vodeneev, Vladimir; Sukhov, Vladimir

    2018-05-01

    Local damage (mainly burning, heating, and mechanical wounding) induces propagation of electrical signals, namely, variation potentials, which are important signals during the life of plants that regulate different physiological processes, including photosynthesis. It is known that the variation potential decreases the rate of CO 2 assimilation by the Calvin-Benson cycle; however, its influence on light reactions has been poorly investigated. The aim of our work was to investigate the influence of the variation potential on the light energy flow that is absorbed, trapped and dissipated per active reaction centre in photosystem II and on the flow of electrons through the chloroplast electron transport chain. We analysed chlorophyll fluorescence in pea leaves using JIP-test and PAM-fluorometry; we also investigated delayed fluorescence. The electrical signals were registered using extracellular electrodes. We showed that the burning-induced variation potential stimulated a nonphotochemical loss of energy in photosystem II under dark conditions. It was also shown that the variation potential gradually increased the flow of light energy absorbed, trapped and dissipated by photosystem II. These changes were likely caused by an increase in the fraction of absorbed light distributed to photosystem II. In addition, the variation potential induced a transient increase in electron flow through the photosynthetic electron transport chain. Some probable mechanisms for the influence of the variation potential on the light reactions of photosynthesis (including the potential role of intracellular pH decrease) are discussed in the work.

  17. Effect of OFF-state stress induced electric field on trapping in AlGaN/GaN high electron mobility transistors on Si (111)

    International Nuclear Information System (INIS)

    Anand, M. J.; Ng, G. I.; Syamal, B.; Zhou, X.; Arulkumaran, S.; Manoj Kumar, C. M.; Ranjan, K.; Vicknesh, S.; Foo, S. C.

    2015-01-01

    The influence of electric field (EF) on the dynamic ON-resistance (dyn-R DS[ON] ) and threshold-voltage shift (ΔV th ) of AlGaN/GaN high electron mobility transistors on Si has been investigated using pulsed current-voltage (I DS -V DS ) and drain current (I D ) transients. Different EF was realized with devices of different gate-drain spacing (L gd ) under the same OFF-state stress. Under high-EF (L gd  = 2 μm), the devices exhibited higher dyn-R DS[ON] degradation but a small ΔV th (∼120 mV). However, at low-EF (L gd  = 5 μm), smaller dyn-R DS[ON] degradation but a larger ΔV th (∼380 mV) was observed. Our analysis shows that under OFF-state stress, the gate electrons are injected and trapped in the AlGaN barrier by tunnelling-assisted Poole-Frenkel conduction mechanism. Under high-EF, trapping spreads towards the gate-drain access region of the AlGaN barrier causing dyn-R DS[ON] degradation, whereas under low-EF, trapping is mostly confined under the gate causing ΔV th . A trap with activation energy 0.33 eV was identified in the AlGaN barrier by I D -transient measurements. The influence of EF on trapping was also verified by Silvaco TCAD simulations

  18. Electron Spin Resonance study of charge trapping in α-ZnMoO.sub.4./sub. single crystal scintillator

    Czech Academy of Sciences Publication Activity Database

    Buryi, Maksym; Spassky, D.A.; Hybler, Jiří; Laguta, Valentyn; Nikl, Martin

    2015-01-01

    Roč. 47, Sep (2015), 244-250 ISSN 0925-3467 R&D Projects: GA MŠk LO1409; GA MŠk(CZ) LM2011029; GA ČR GAP204/12/0805 Institutional support: RVO:68378271 Keywords : Electron Spin Resonance * scintillator * charge traps * zinc molybdate Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.183, year: 2015

  19. Trapping processes in CaS:Eu2+,Tm3+

    International Nuclear Information System (INIS)

    Jia, Dongdong; Jia, Weiyi; Evans, D. R.; Dennis, W. M.; Liu, Huimin; Zhu, Jing; Yen, W. M.

    2000-01-01

    CaS:Eu 2+ ,Tm 3+ is a persistent red phosphor. Thermoluminescence was measured under different excitation and thermal treatment conditions. The results reveal that the charge defects, created by substituting Tm 3+ for Ca 2+ , serve as hole traps for the afterglow at room temperature. Tm 3+ plays the role of deep electron trapping centers, capturing electrons either through the conduction band or directly from the excited Eu 2+ ions. These two processes, in which two different sites of Tm 3+ are involved, correspond to two traps with different depths. (c) 2000 American Institute of Physics

  20. Electron Cloud Generation and Trapping in a Quadrupole Magnet at the Los Alamos Proton Storage Ring

    International Nuclear Information System (INIS)

    Macek, Robert J.; Browman, Andrew A.; Ledford, John E.; TechSource, Santa Fe; Los Alamos; Borden, Michael J.; O'Hara, James F.; McCrady, Rodney C.; Rybarcyk, Lawrence J.; Spickermann, Thomas; Zaugg, Thomas J.; Pivi, Mauro T.F.

    2008-01-01

    Recent beam physics studies on the two-stream e-p instability at the LANL proton storage ring (PSR) have focused on the role of the electron cloud generated in quadrupole magnets where primary electrons, which seed beam-induced multipacting, are expected to be largest due to grazing angle losses from the beam halo. A new diagnostic to measure electron cloud formation and trapping in a quadrupole magnet has been developed, installed, and successfully tested at PSR. Beam studies using this diagnostic show that the 'prompt' electron flux striking the wall in a quadrupole is comparable to the prompt signal in the adjacent drift space. In addition, the 'swept' electron signal, obtained using the sweeping feature of the diagnostic after the beam was extracted from the ring, was larger than expected and decayed slowly with an exponential time constant of 50 to 100 (micro)s. Other measurements include the cumulative energy spectra of prompt electrons and the variation of both prompt and swept electron signals with beam intensity. Experimental results were also obtained which suggest that a good fraction of the electrons observed in the adjacent drift space for the typical beam conditions in the 2006 run cycle were seeded by electrons ejected from the quadrupole

  1. Electron cloud generation and trapping in a quadrupole magnet at the Los Alamos proton storage ring

    Directory of Open Access Journals (Sweden)

    Robert J. Macek

    2008-01-01

    Full Text Available Recent beam physics studies on the two-stream e-p instability at the LANL proton storage ring (PSR have focused on the role of the electron cloud generated in quadrupole magnets where primary electrons, which seed beam-induced multipacting, are expected to be largest due to grazing angle losses from the beam halo. A new diagnostic to measure electron cloud formation and trapping in a quadrupole magnet has been developed, installed, and successfully tested at PSR. Beam studies using this diagnostic show that the “prompt” electron flux striking the wall in a quadrupole is comparable to the prompt signal in the adjacent drift space. In addition, the “swept” electron signal, obtained using the sweeping feature of the diagnostic after the beam was extracted from the ring, was larger than expected and decayed slowly with an exponential time constant of 50 to 100  μs. Other measurements include the cumulative energy spectra of prompt electrons and the variation of both prompt and swept electron signals with beam intensity. Experimental results were also obtained which suggest that a good fraction of the electrons observed in the adjacent drift space for the typical beam conditions in the 2006 run cycle were seeded by electrons ejected from the quadrupole.

  2. Co-existence of free and self-trapped excitons in J-aggregates

    International Nuclear Information System (INIS)

    Malyukin, Yu.V.; Lebedenko, A.N.; Sorokin, A.V.; Yefimova, S.L.

    2005-01-01

    Nature of excited electronic states of amphi-PIC J-aggregates, which are the source of the self-trapping states, have been investigated using low-temperature site-selective, time-resolved spectroscopy techniques. The self-trapping states are shown to evolve from the delocalized exciton states within the J-band. The strongly localized electronic states located on the low-frequency edge of the J-band, are not able to form polaronic states and, hence, the polaronic relaxation process is particularly collective one. The exciton self-trapping is more effective in J-aggregates with strong disorder, requires overcoming a self-trapping barrier

  3. TRAP230/ARC240 and TRAP240/ARC250 Mediator subunits are functionally conserved through evolution

    DEFF Research Database (Denmark)

    Samuelsen, Camilla O; Baraznenok, Vera; Khorosjutina, Olga

    2003-01-01

    In Saccharomyces cerevisiae Mediator, a subgroup of proteins (Srb8, Srb9, Srb10, and Srb11) form a module, which is involved in negative regulation of transcription. Homologues of Srb10 and Srb11 are found in some mammalian Mediator preparations, whereas no clear homologues have been reported...... for Srb8 and Srb9. Here, we identify a TRAP240/ARC250 homologue in Schizosaccharomyces pombe and demonstrate that this protein, spTrap240, is stably associated with a larger form of Mediator, which also contains conserved homologues of Srb8, Srb10, and Srb11. We find that spTrap240 and Sch. pombe Srb8 (sp......Srb8) regulate the same distinct subset of genes and have indistinguishable phenotypic characteristics. Importantly, Mediator containing the spSrb8/spTrap240/spSrb10/spSrb11 subunits is isolated only in free form, devoid of RNA polymerase II. In contrast, Mediator lacking this module associates...

  4. Nested Penning Trap as a Source of Singly Charged Ions

    International Nuclear Information System (INIS)

    Ordonez, C.A.

    2003-01-01

    In the work reported, the possibility of using a nested Penning trap as a high purity source of low-charge-state ions is studied. For the configuration considered, a relatively dense ion plasma is confined by a three-dimensional electric potential well. The three-dimensional well is produced by the electric field generated by both the trap electrodes and a trapped electron plasma. The ion and electron plasmas are each considered to have Maxwellian velocity distributions. However, it is shown that the electron plasma must have a temperature that is higher than that of the ion plasma when the ions have low charge states. The work reported includes a self-consistent prediction of a possible plasma equilibrium

  5. An active trap filter for high-power voltage source converters

    DEFF Research Database (Denmark)

    Bai, Haofeng; Wang, Xiongfei; Loh, Poh Chiang

    2015-01-01

    This paper proposes a power electronic based device to actively trap the switching current ripples for highpower converters. Control principle and system design of the active trap filter are discussed first. Comparisons of the active trap filter with LCL and LLCL filters are then carried out...

  6. Trapping of deuterium in krypton-implanted nickel

    International Nuclear Information System (INIS)

    Frank, R.C.; McManus, S.P.; Rehn, L.E.; Baldo, P.

    1986-01-01

    Krypton ions with energy 600 keV were implanted in nickel to fluences of 2 x 10 16 cm -2 under three different conditions. Deuterium was subsequently introduced into the implanted regions by electrolysis at room temperature. After the diffusible deuterium was permitted to escape, the 2 H( 3 He, 1 H) 4 He nuclear reaction was used to analyze for the trapped deuterium during an isochronal annealing program. The region implanted at 100 0 C with no higher temperature anneal had the largest number of traps; the region implanted at 100 0 C and annealed for 100 min at 500 0 C had considerably less; the region implanted at 500 0 C had the least. Electron diffraction patterns confirmed the existence of solid crystalline krypton in all three regions. Transmission electron microscope studies revealed precipitates with an average diameter of 8 nm in the region implanted at 500 0 C. The two regions implanted at 100 0 C contained smaller precipitates. Trap binding enthalpies were obtained by math modeling. In addition to the traps with binding enthalpy of 0.55 eV reported earlier by other investigators for helium implanted in nickel, a smaller number of traps with binding enthalpies up to 0.83 eV were also found. The trapping of deuterium by various types of imperfections, including the solid krypton precipitates, is discussed

  7. Geometry and electronic structure of an impurity-trapped exciton in the Cs2GeF6 crystal doped with U4+. The 5f17s1 manifold

    International Nuclear Information System (INIS)

    Ordejon, B.; Seijo, L.; Barandiaran, Z.

    2007-01-01

    Complete text of publication follows: Excitons trapped at impurity centres in highly ionic crystals were first described by McClure and Pedrini [Phys. Rev. B 32, 8465 (1985)] as excited states consisting of a bound electron-hole pair with the hole localized on the impurity and the electron on nearby lattice sites, and a very short impurity-ligand bond length. In this work we present a detailed microscopic characterization of an impurity - trapped exciton in Cs 2 GeF 6 doped with U 4+ . Its electronic structure has been studied by means of CASSCF/CASPT2/SOCI relativistic ab initio model potential (AIMP) embedded-cluster calculations on (UF 6 ) 2- and (UF 6 Cs 8 ) 6+ clusters embedded in Cs 2 GeF 6 . The local geometry of the impurity-trapped exciton, the potential energy curves, and the multi electronic wavefunctions, have been obtained as direct, non-empirical results of the methods. The calculated excited states appear to be significantly delocalized outside the UF 6 volume and their U-F bond length turns out to be very short, closer to that of a pentavalent uranium defect than to that of a tetravalent uranium defect. The wavefunctions of these excited states show a dominant U 5f 1 7s 1 configuration character. This result has never been anticipated by simpler models and reveals the unprecedented ability of diffuse orbitals of f-element impurities to act as electron traps in ionic crystals

  8. Extraction of highly charged ions from the Berlin Electron Beam Ion Trap for interactions with a gas target

    International Nuclear Information System (INIS)

    Allen, F.I.; Biedermann, C.; Radtke, R.; Fussmann, G.

    2006-01-01

    Highly charged ions are extracted from the Berlin Electron Beam Ion Trap for investigations of charge exchange with a gas target. The classical over-the-barrier model for slow highly charged ions describes this process, whereby one or more electrons are captured from the target into Rydberg states of the ion. The excited state relaxes via a radiative cascade of the electron to ground energy. The cascade spectra are characteristic of the capture state. We investigate x-ray photons emitted as a result of interactions between Ar 17+ ions at energies ≤5q keV with Ar atoms. Of particular interest is the velocity dependence of the angular momentum capture state l c

  9. A Landau fluid model for dissipative trapped electron modes

    International Nuclear Information System (INIS)

    Hedrick, C.L.; Leboeuf, J.N.; Sidikman, K.L.

    1995-09-01

    A Landau fluid model for dissipative trapped electron modes is developed which focuses on an improved description of the ion dynamics. The model is simple enough to allow nonlinear calculations with many harmonics for the times necessary to reach saturation. The model is motivated by a discussion that starts with the gyro-kinetic equation and emphasizes the importance of simultaneously including particular features of magnetic drift resonance, shear, and Landau effects. To ensure that these features are simultaneously incorporated in a Landau fluid model with only two evolution equations, a new approach to determining the closure coefficients is employed. The effect of this technique is to reduce the matching of fluid and kinetic responses to a single variable, rather than two, and to allow focusing on essential features of the fluctuations in question, rather than features that are only important for other types of fluctuations. Radially resolved nonlinear calculations of this model, advanced in time to reach saturation, are presented to partially illustrate its intended use. These calculations have a large number of poloidal and toroidal harmonics to represent the nonlinear dynamics in a converged steady state which includes cascading of energy to both short and long wavelengths

  10. Model of electron capture in low-temperature glasses

    International Nuclear Information System (INIS)

    Bartczak, W.M.; Swiatla, D.; Kroh, J.

    1983-01-01

    The new model of electron capture by a statistical variety of traps in glassy matrices is proposed. The electron capture is interpreted as the radiationless transition (assisted by multiphonon emission) of the mobile electron to the localized state in the trap. The conception of 'unfair' and 'fair' traps is introduced. The 'unfair' trap captures the mobile electron by the shallow excited state. In contrast, the 'fair' trap captures the electron by the ground state. The model calculations of the statistical distributions of the occupied electron traps are presented and discussed with respect to experimental results. (author)

  11. Charge Trapping in Photovoltaically Active Perovskites and Related Halogenoplumbate Compounds.

    Science.gov (United States)

    Shkrob, Ilya A; Marin, Timothy W

    2014-04-03

    Halogenoplumbate perovskites (MeNH3PbX3, where X is I and/or Br) have emerged as promising solar panel materials. Their limiting photovoltaic efficiency depends on charge localization and trapping processes that are presently insufficiently understood. We demonstrate that in halogenoplumbate materials the holes are trapped by organic cations (that deprotonate from their oxidized state) and Pb(2+) cations (as Pb(3+) centers), whereas the electrons are trapped by several Pb(2+) cations, forming diamagnetic lead clusters that also serve as color centers. In some cases, paramagnetic variants of these clusters can be observed. We suggest that charge separation in the halogenoplumbates resembles latent image formation in silver halide photography. Electron and hole trapping by lead clusters in extended dislocations in the bulk may be responsible for accumulation of trapped charge observed in this photovoltaic material.

  12. Toward sub-Kelvin resistive cooling and non destructive detection of trapped non-neutral electron plasma

    Science.gov (United States)

    Di Domizio, S.; Krasnický, D.; Lagomarsino, V.; Testera, G.; Vaccarone, R.; Zavatarelli, S.

    2015-01-01

    A resonant circuit tuned to a particular frequency of the motion of charged particles stored in a Penning trap and connected to a low noise amplifier allows, at the same time, cooling and non destructive detection of the particles. Its use is widely diffused when single or few particles are stored near the centre of a hyperbolic Penning trap. We present a consistent model that predicts the shape of the induced signal when the tuned circuit is used to detect and cool the axial motion of a cold non neutral plasma stored in an open-ended cylindrical Penning trap. The model correctly accounts for the not negligible axial plasma size. We show that the power spectrum of the signal measured across the tuned circuit provides information about the particle number and insights about the plasma temperature. We report on the design of a HEMT-based cryogenic amplifier working at 14.4 MHz and 4.2 K and the results of the noise measurements. We have measured a drain current noise in the range from 6 to 17 pA/√Hz, which corresponds to an increase of the tuned circuit equivalent temperature of at maximum 0.35 K. The cryogenic amplifier has a very low power consumption from few tens to few hundreds of μW corresponding to a drain current in the range 100-800 μ A. An additional contribution due to the gate noise has been identified when the drain current is below 300 μA above that value an upper limit of the increase of the equivalent tuned circuit temperature due to this contribution of 0.02 K has been obtained. These features make the tuned circuit connected to this amplifier a promising device for detecting and cooling the axial motion of an electron plasma when the Penning trap is mounted inside a dilution refrigerator.

  13. Deuterium ion irradiation damage and deuterium trapping mechanism in candidate stainless steel material (JPCA2) for fusion reactor

    International Nuclear Information System (INIS)

    Ashizuka, Norihiro; Kurita, Takaaki; Yoshida, Naoaki; Fujiwara, Tadashi; Muroga, Takeo

    1987-01-01

    An improved austenitic stainless steel (JPCA), a candidate material for fusion reactor, is irradiated at room temperature with deuterium ion beams. Desorption spectra of deuterium gas is measured at various increased temperatures and defects formed under irradiation are observed by transmission electron microscopy to determine the mechanism of the thermal release of deuteriums and the characteristics of irradiation-induced defects involved in the process. In the deuterium deportion spectra observed, five release stages are found to exist at 90 deg C, 160 deg C, 220 deg C, 300 deg C and 400 deg C, referred to as Stage I, II, III, IV and V, respectively. Stage I is interpreted as representing the release of deuteriums trapped in point defects (presumably vacancies) formed under irradiation. The energy of desorption from the trapping sites is estimated at 0.8 eV. Stage II is concluded to be associated with the release of deuteriums trapped in a certain kind of existing defects. Stage III involves the release of deuteriums that are trapped in dislocations, dislocation loops or dislocated portions of stacking fault tetrahedra. This release occurs significantly in processed materials and other materials irradiated with high energy ion beams that may cause cascade damage. Stage IV is interpreted in terms of thermal decomposition of small deuterium clusters. Stage V is associated with the decomposition of rather large deuterium clusters grown on the {111} plane. (Nogami, K.)

  14. A study of back-trap mottle in coated papers using electron probe microanalysis

    International Nuclear Information System (INIS)

    Eby, T.; Whalen-Shaw, M.

    1991-01-01

    In this paper methodology is been developed for analyzing both the surface and cross-sectional distributions for coating components using electron probe microanalysis and image analysis technology. Actual light and dark areas of print mottle are physically separated and analyzed to provide an unequivocal relationship between the distribution of coating components and the physical structure of the coating in areas of print mottle. Areas of low ink density were found to have higher surface latex concentration, greater mean coating thickness, and greater mean rawstock roughness. Furthermore, the difference in surface concentration of CaCO 3 within areas of, low and high ink density was established as a new and additional probable cause of back-trap mottle

  15. HITRAP: A Facility for Experiments with Trapped Highly Charged Ions

    International Nuclear Information System (INIS)

    Quint, W.; Dilling, J.; Djekic, S.; Haeffner, H.; Hermanspahn, N.; Kluge, H.-J.; Marx, G.; Moore, R.; Rodriguez, D.; Schoenfelder, J.; Sikler, G.; Valenzuela, T.; Verdu, J.; Weber, C.; Werth, G.

    2001-01-01

    HITRAP is a planned ion trap facility for capturing and cooling of highly charged ions produced at GSI in the heavy-ion complex of the UNILAC-SIS accelerators and the ESR storage ring. In this facility heavy highly charged ions up to uranium will be available as bare nuclei, hydrogen-like ions or few-electron systems at low temperatures. The trap for receiving and studying these ions is designed for operation at extremely high vacuum by cooling to cryogenic temperatures. The stored highly charged ions can be investigated in the trap itself or can be extracted from the trap at energies up to about 10 keV/q. The proposed physics experiments are collision studies with highly charged ions at well-defined low energies (eV/u), high-accuracy measurements to determine the g-factor of the electron bound in a hydrogen-like heavy ion and the atomic binding energies of few-electron systems, laser spectroscopy of HFS transitions and X-ray spectroscopy

  16. High-k shallow traps observed by charge pumping with varying discharging times

    International Nuclear Information System (INIS)

    Ho, Szu-Han; Chen, Ching-En; Tseng, Tseung-Yuen; Chang, Ting-Chang; Lu, Ying-Hsin; Lo, Wen-Hung; Tsai, Jyun-Yu; Liu, Kuan-Ju; Wang, Bin-Wei; Cao, Xi-Xin; Chen, Hua-Mao; Cheng, Osbert; Huang, Cheng-Tung; Chen, Tsai-Fu

    2013-01-01

    In this paper, we investigate the influence of falling time and base level time on high-k bulk shallow traps measured by charge pumping technique in n-channel metal-oxide-semiconductor field-effect transistors with HfO 2 /metal gate stacks. N T -V high level characteristic curves with different duty ratios indicate that the electron detrapping time dominates the value of N T for extra contribution of I cp traps. N T is the number of traps, and I cp is charge pumping current. By fitting discharge formula at different temperatures, the results show that extra contribution of I cp traps at high voltage are in fact high-k bulk shallow traps. This is also verified through a comparison of different interlayer thicknesses and different Ti x N 1−x metal gate concentrations. Next, N T -V high level characteristic curves with different falling times (t falling time ) and base level times (t base level ) show that extra contribution of I cp traps decrease with an increase in t falling time . By fitting discharge formula for different t falling time , the results show that electrons trapped in high-k bulk shallow traps first discharge to the channel and then to source and drain during t falling time . This current cannot be measured by the charge pumping technique. Subsequent measurements of N T by charge pumping technique at t base level reveal a remainder of electrons trapped in high-k bulk shallow traps

  17. Effect of OFF-state stress induced electric field on trapping in AlGaN/GaN high electron mobility transistors on Si (111)

    Energy Technology Data Exchange (ETDEWEB)

    Anand, M. J., E-mail: anand2@e.ntu.edu.sg, E-mail: eging@ntu.edu.sg; Ng, G. I., E-mail: anand2@e.ntu.edu.sg, E-mail: eging@ntu.edu.sg; Syamal, B.; Zhou, X. [School of Electrical and Electronics Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Arulkumaran, S.; Manoj Kumar, C. M.; Ranjan, K.; Vicknesh, S.; Foo, S. C. [Temasek Laboratories@NTU, Nanyang Technological University, 50 Nanyang Drive, Research Techno Plaza, Singapore 637553 (Singapore)

    2015-02-23

    The influence of electric field (EF) on the dynamic ON-resistance (dyn-R{sub DS[ON]}) and threshold-voltage shift (ΔV{sub th}) of AlGaN/GaN high electron mobility transistors on Si has been investigated using pulsed current-voltage (I{sub DS}-V{sub DS}) and drain current (I{sub D}) transients. Different EF was realized with devices of different gate-drain spacing (L{sub gd}) under the same OFF-state stress. Under high-EF (L{sub gd} = 2 μm), the devices exhibited higher dyn-R{sub DS[ON]} degradation but a small ΔV{sub th} (∼120 mV). However, at low-EF (L{sub gd} = 5 μm), smaller dyn-R{sub DS[ON]} degradation but a larger ΔV{sub th} (∼380 mV) was observed. Our analysis shows that under OFF-state stress, the gate electrons are injected and trapped in the AlGaN barrier by tunnelling-assisted Poole-Frenkel conduction mechanism. Under high-EF, trapping spreads towards the gate-drain access region of the AlGaN barrier causing dyn-R{sub DS[ON]} degradation, whereas under low-EF, trapping is mostly confined under the gate causing ΔV{sub th}. A trap with activation energy 0.33 eV was identified in the AlGaN barrier by I{sub D}-transient measurements. The influence of EF on trapping was also verified by Silvaco TCAD simulations.

  18. A shortcut to high-affinity Ga-68 and Cu-64 radiopharmaceuticals: one-pot click chemistry trimerisation on the TRAP platform.

    Science.gov (United States)

    Baranyai, Zsolt; Reich, Dominik; Vágner, Adrienn; Weineisen, Martina; Tóth, Imre; Wester, Hans-Jürgen; Notni, Johannes

    2015-06-28

    Due to its 3 carbonic acid groups being available for bioconjugation, the TRAP chelator (1,4,7-triazacyclononane-1,4,7-tris(methylene(2-carboxyethylphosphinic acid))) is chosen for the synthesis of trimeric bioconjugates for radiolabelling. We optimized a protocol for bio-orthogonal TRAP conjugation via Cu(I)-catalyzed Huisgen-cycloaddition of terminal azides and alkynes (CuAAC), including a detailed investigation of kinetic properties of Cu(II)-TRAP complexes. TRAP building blocks for CuAAC, TRAP(alkyne)3 and TRAP(azide)3 were obtained by amide coupling of propargylamine/3-azidopropyl-1-amine, respectively. For Cu(II) complexes of neat and triply amide-functionalized TRAP, the equilibrium properties as well as pseudo-first-order Cu(II)-transchelation, using 10 to 30 eq. of NOTA and EDTA, were studied by UV-spectrophotometry. Dissociation of any Cu(II)-TRAP species was found to be independent on the nature or excess of a competing chelator, confirming a proton-driven two-step mechanism. The respective thermodynamic stability constants (log K(ML): 19.1 and 17.6) and dissociation rates (k: 38 × 10(-6) and 7 × 10(-6) s(-1), 298 K, pH 4) show that the Cu(II) complex of the TRAP-conjugate possesses lower thermodynamic stability but higher kinetic inertness. At pH 2-3, its demetallation with NOTA was complete within several hours/days at room temperature, respectively, enabling facile Cu(II) removal after click coupling by direct addition of NOTA trihydrochloride to the CuAAC reaction mixture. Notwithstanding this, an extrapolated dissociation half life of >100 h at 37 °C and pH 7 confirms the suitability of TRAP-bioconjugates for application in Cu-64 PET (cf. t(1/2)(Cu-64) = 12.7 h). To showcase advantages of the method, TRAP(DUPA-Pep)3, a trimer of the PSMA inhibitor DUPA-Pep, was synthesized using 1 eq. TRAP(alkyne)3, 3.3 eq. DUPA-Pep-azide, 10 eq. Na ascorbate, and 1.2 eq. Cu(II)-acetate. Its PSMA affinity (IC50), determined by the competition assay on LNCa

  19. The effect of dopant-induced electron traps on spectrum evolution of doped organic light-emitting devices

    Energy Technology Data Exchange (ETDEWEB)

    Zhan, Y.Q. [Surface Physics Laboratory (National Key Laboratory), Lab of Advanced Materials, Fudan University, Shanghai 200433 (China)]. E-mail: yqzhan@fudan.edu.cn; Zhou, J. [Surface Physics Laboratory (National Key Laboratory), Lab of Advanced Materials, Fudan University, Shanghai 200433 (China); Zhou, Y.C. [Surface Physics Laboratory (National Key Laboratory), Lab of Advanced Materials, Fudan University, Shanghai 200433 (China); Wu, Y. [Surface Physics Laboratory (National Key Laboratory), Lab of Advanced Materials, Fudan University, Shanghai 200433 (China); Yang, H. [Surface Physics Laboratory (National Key Laboratory), Lab of Advanced Materials, Fudan University, Shanghai 200433 (China); Li, F.Y. [Surface Physics Laboratory (National Key Laboratory), Lab of Advanced Materials, Fudan University, Shanghai 200433 (China); Ding, X.M. [Surface Physics Laboratory (National Key Laboratory), Lab of Advanced Materials, Fudan University, Shanghai 200433 (China); Hou, X.Y. [Surface Physics Laboratory (National Key Laboratory), Lab of Advanced Materials, Fudan University, Shanghai 200433 (China)]. E-mail: xyhou@fudan.edu.cn

    2007-05-07

    A prototype of light emitting device with two symmetrically located Al/LiF electrodes is fabricated to study the voltage dependence of emission spectra. 4-(dicyanomethylene)-2-methyl-6- (pdimethylaminostyryl)-4H-pyran doped tris-(8-hydroxy-quinolinato) aluminum thin film is the emitting layer of the device. Experiments show that with increasing applied voltage the emission intensity of the device decreases, of which the dopant emission intensity decreases more steeply than that of the host. Based on the theory of space-charge-limited current in insulator with a single shallow trap level it is deduced that the photoluminescence intensity of the dopant emission decreases linearly with applied voltage, in good agreement with experimental measurements. The evolution of the emission spectra can be well explained by the suggested mechanism that the electrons are trapped in the dopant molecules, which blocks the energy transfer from the host, and leads to more excitons in the host to emit light.

  20. The effect of dopant-induced electron traps on spectrum evolution of doped organic light-emitting devices

    International Nuclear Information System (INIS)

    Zhan, Y.Q.; Zhou, J.; Zhou, Y.C.; Wu, Y.; Yang, H.; Li, F.Y.; Ding, X.M.; Hou, X.Y.

    2007-01-01

    A prototype of light emitting device with two symmetrically located Al/LiF electrodes is fabricated to study the voltage dependence of emission spectra. 4-(dicyanomethylene)-2-methyl-6- (pdimethylaminostyryl)-4H-pyran doped tris-(8-hydroxy-quinolinato) aluminum thin film is the emitting layer of the device. Experiments show that with increasing applied voltage the emission intensity of the device decreases, of which the dopant emission intensity decreases more steeply than that of the host. Based on the theory of space-charge-limited current in insulator with a single shallow trap level it is deduced that the photoluminescence intensity of the dopant emission decreases linearly with applied voltage, in good agreement with experimental measurements. The evolution of the emission spectra can be well explained by the suggested mechanism that the electrons are trapped in the dopant molecules, which blocks the energy transfer from the host, and leads to more excitons in the host to emit light

  1. Electron-beam induced conduction in some polymers

    International Nuclear Information System (INIS)

    Suzuoki, Yasuo; Mizutani, Teruyoshi; Ieda, Masayuki

    1976-01-01

    The charge signal induced by pulsed electron beam consists of two components, i.e. the fast and the slow components. The slow component which corresponds to carrier transport via shallow traps exhibited an asymmetry with respect to the bias field polarity. The asymmetry revealed that the main carriers which drifted via shallow traps were electrons in PET, both electrons and holes in PEN, and holes in PS. TSC spectra of electron-beam induced electrets proved directly the existence of electron shallow traps in PET and both electron and hole traps in PEN. Their trap energies were 0.1 to 0.2 eV. (auth.)

  2. Theoretical modeling of the electronic structure and exchange interactions in Cu(II)Pc

    Science.gov (United States)

    Wu, Wei; Fisher, A. J.; Harrison, N. M.; Wang, Hai; Wu, Zhenlin; Gardener, Jules; Heutz, Sandrine; Jones, Tim; Aeppli, Gabriel

    2012-12-01

    We calculate the electronic structure and exchange interactions in a copper(II)phthalocyanine (Cu(II)Pc) crystal as a one-dimensional molecular chain using hybrid exchange density functional theory (DFT). In addition, the intermolecular exchange interactions are also calculated in a molecular dimer using Green's function perturbation theory (GFPT) to illustrate the underlying physics. We find that the exchange interactions depend strongly on the stacking angle, but weakly on the sliding angle (defined in the text). The hybrid DFT calculations also provide an insight into the electronic structure of the Cu(II)Pc molecular chain and demonstrate that on-site electron correlations have a significant effect on the nature of the ground state, the band gap and magnetic excitations. The exchange interactions predicted by our DFT calculations and GFPT calculations agree qualitatively with the recent experimental results on newly found η-Cu(II)Pc and the previous results for the α- and β-phases. This work provides a reliable theoretical basis for the further application of Cu(II)Pc to molecular spintronics and organic-based quantum information processing.

  3. 1D numerical simulation of charge trapping in an insulator submitted to an electron beam irradiation. Part I: Computation of the initial secondary electron emission yield

    International Nuclear Information System (INIS)

    Aoufi, A.; Damamme, G.

    2011-01-01

    The aim of this work is to study by numerical simulation a mathematical modelling technique describing charge trapping during initial charge injection in an insulator submitted to electron beam irradiation. A two-fluxes method described by a set of two stationary transport equations is used to split the electron current j e (z) into coupled forward j e+ (z) and backward j e (z) currents and such that j e (z) = j e+ (z) - j e- (z). The sparse algebraic linear system, resulting from the vertex-centered finite-volume discretization scheme is solved by an iterative decoupled fixed point method which involves the direct inversion of a bi-diagonal matrix. The sensitivity of the initial secondary electron emission yield with respect to the energy of incident primary electrons beam, that is penetration depth of the incident beam, or electron cross sections (absorption and diffusion) is investigated by numerical simulations. (authors)

  4. Impact of Shock Front Rippling and Self-reformation on the Electron Dynamics at Low-Mach-number Shocks

    Science.gov (United States)

    Yang, Zhongwei; Lu, Quanming; Liu, Ying D.; Wang, Rui

    2018-04-01

    Electron dynamics at low-Mach-number collisionless shocks are investigated by using two-dimensional electromagnetic particle-in-cell simulations with various shock normal angles. We found: (1) The reflected ions and incident electrons at the shock front provide an effective mechanism for the quasi-electrostatic wave generation due to the charge-separation. A fraction of incident electrons can be effectively trapped and accelerated at the leading edge of the shock foot. (2) At quasi-perpendicular shocks, the electron trapping and reflection is nonuniform due to the shock rippling along the shock surface and is more likely to take place at some locations accompanied by intense reflected ion-beams. The electron trapping process has a periodical evolution over time due to the shock front self-reformation, which is controlled by ion dynamics. Thus, this is a cross-scale coupling phenomenon. (3) At quasi-parallel shocks, reflected ions can travel far back upstream. Consequently, quasi-electrostatic waves can be excited in the shock transition and the foreshock region. The electron trajectory analysis shows these waves can trap electrons at the foot region and reflect a fraction of them far back upstream. Simulation runs in this paper indicate that the micro-turbulence at the shock foot can provide a possible scenario for producing the reflected electron beam, which is a basic condition for the type II radio burst emission at low-Mach-number interplanetary shocks driven by Coronal Mass Ejections (CMEs).

  5. Electron transfer and atom exchange between aqueous Fe(II) and structural Fe(III) in clays. Role in U and Hg(II) transformations

    Energy Technology Data Exchange (ETDEWEB)

    Scherer, Michelle [Univ. of Iowa, Iowa City, IA (United States)

    2016-08-31

    During this project, we investigated Fe electron transfer and atom exchange between aqueous Fe(II) and structural Fe(III) in clay minerals. We used selective chemical extractions, enriched Fe isotope tracer experiments, computational molecular modeling, and Mössbauer spectroscopy. Our findings indicate that structural Fe(III) in clay minerals is reduced by aqueous Fe(II) and that electron transfer occurs when Fe(II) is sorbed to either basal planes and edge OH-groups of clay mineral. Findings from highly enriched isotope experiments suggest that up to 30 % of the Fe atoms in the structure of some clay minerals exhanges with aqueous Fe(II). First principles calculations using a small polaron hopping approach suggest surprisingly fast electron mobility at room temperature in a nontronite clay mineral and are consistent with temperature dependent Mössbauer data Fast electron mobility suggests that electrons may be able to conduct through the mineral fast enough to enable exchange of Fe between the aqueous phase and clay mineral structure. over the time periods we observed. Our findings suggest that Fe in clay minerals is not as stable as previously thought.

  6. Electron trapping in neutron-irradiated very thin films of Al2O3

    International Nuclear Information System (INIS)

    Srivastava, P.C.; Bardhan, A.R.

    1979-01-01

    Oxide layers of thicknesses less than 100 A have been prepared by thermal-oxidation of a base metal electrode film of aluminium. These films were then neutron-irradiated from a laboratory Ra-Be source to a fluence of approximately 10 11 neutrons cm -2 and the sandwich structure, Al-Al 2 O 3 -Au, was completed by depositing a thin metal film of gold over the irradiated oxide layer. D.C. steady and transient flow through the sandwich structures have been studied. Results obtained in the experiments with irradiated sandwiches have been compared with unirradiated ones to show that traps are introduced because of the damage caused by the incident neutrons. Transient voltage measurement across the junction gives a trap density of approximately 10 18 cm -3 . A capture cross-section of the order 10 -28 cm 2 is estimated for the traps. It is found that the (identified) traps are uniformly distributed within an energy of 0.099 eV below the conduction band edge of aluminium oxide. The physical nature of the traps is discussed by comparing the capture cross-sections of the physically known trapping centres. The possibility of vacancies or F-centres acting as traps (for the identified ones) has been suggested. (author)

  7. PEP-II Transverse Feedback Electronics Upgrade

    International Nuclear Information System (INIS)

    Weber, J.; Chin, M.; Doolittle, L.; Akre, R.

    2005-01-01

    The PEP-II B Factory at the Stanford Linear Accelerator Center (SLAC) requires an upgrade of the transverse feedback system electronics. The new electronics require 12-bit resolution and a minimum sampling rate of 238 Msps. A Field Programmable Gate Array (FPGA) is used to implement the feedback algorithm. The FPGA also contains an embedded PowerPC 405 (PPC-405) processor to run control system interface software for data retrieval, diagnostics, and system monitoring. The design of this system is based on the Xilinx(R) ML300 Development Platform, a circuit board set containing an FPGA with an embedded processor, a large memory bank, and other peripherals. This paper discusses the design of a digital feedback system based on an FPGA with an embedded processor. Discussion will include specifications, component selection, and integration with the ML300 design

  8. PEP-II Transverse Feedback Electronics Upgrade

    International Nuclear Information System (INIS)

    Weber, J.M.; Chin, M.J.; Doolittle, L.R.; Akre, R.

    2006-01-01

    The PEP-II B Factory at the Stanford Linear Accelerator Center (SLAC) requires an upgrade of the transverse feedback system electronics. The new electronics require 12-bit resolution and a minimum sampling rate of 238 Msps. A Field Programmable Gate Array (FPGA) is used to implement the feedback algorithm. The FPGA also contains an embedded PowerPC 405 (PPC-405) processor to run control system interface software for data retrieval, diagnostics, and system monitoring. The design of this system is based on the Xilinx(reg s ign) ML300 Development Platform, a circuit board set containing an FPGA with an embedded processor, a large memory bank, and other peripherals. This paper discusses the design of a digital feedback system based on an FPGA with an embedded processor. Discussion will include specifications, component selection, and integration with the ML300 design

  9. PEP-II Transverse Feedback Electronics Upgrade

    CERN Document Server

    Weber, Jonah; Chin, Michael; Doolittle, Lawrence

    2005-01-01

    The PEP-II B Factory at the Stanford Linear Accelerator Center (SLAC) requires an upgrade of the transverse feedback system electronics. The new electronics require 12-bit resolution and a minimum sampling rate of 238 Msps. A Field Programmable Gate Array (FPGA) is used to implement the feedback algorithm. The FPGA also contains an embedded PowerPC 405 (PPC-405) processor to run control system interface software for data retrieval, diagnostics, and system monitoring. The design of this system is based on the Xilinx® ML300 Development Platform, a circuit board set containing an FPGA with an embedded processor, a large memory bank, and other peripherals. This paper discusses the design of a digital feedback system based on an FPGA with an embedded processor. Discussion will include specifications, component selection, and integration with the ML300 design.

  10. Fast and slow border traps in MOS devices

    International Nuclear Information System (INIS)

    Fleetwood, D.M.

    1996-01-01

    Convergent lines of evidence are reviewed which show that near-interfacial oxide traps (border traps) that exchange charge with the Si can strongly affect the performance, radiation response, and long-term reliability of MOS devices. Observable effects of border traps include capacitance-voltage (C-V) hysteresis, enhanced l/f noise, compensation of trapped holes, and increased thermally stimulated current in MOS capacitors. Effects of faster (switching times between ∼10 -6 s and ∼1 s) and slower (switching times greater than ∼1 s) border traps have been resolved via a dual-transistor technique. In conjunction with studies of MOS electrical response, electron paramagnetic resonance and spin dependent recombination studies suggest that E' defects (trivalent Si centers in SiO 2 associated with O vacancies) can function as border traps in MOS devices exposed to ionizing radiation or high-field stress. Hydrogen-related centers may also be border traps

  11. Electron beam cooling at a magnetic storage ring, TARN II, and an electrostatic storage ring

    International Nuclear Information System (INIS)

    Tanabe, Tetsumi

    2006-01-01

    At the High Energy Accelerator Research Organization (KEK), a magnetic storage ring, TARN II, with an electron cooler was operated from 1989 to 1999, while an electrostatic storage ring with a small electron cooler has been operational since 2000. In this paper, the electron cooling at TARN II and the electrostatic storage ring is described. (author)

  12. Magnetic field extraction of trap-based electron beams using a high-permeability grid

    International Nuclear Information System (INIS)

    Hurst, N. C.; Danielson, J. R.; Surko, C. M.

    2015-01-01

    A method to form high quality electrostatically guided lepton beams is explored. Test electron beams are extracted from tailored plasmas confined in a Penning-Malmberg trap. The particles are then extracted from the confining axial magnetic field by passing them through a high magnetic permeability grid with radial tines (a so-called “magnetic spider”). An Einzel lens is used to focus and analyze the beam properties. Numerical simulations are used to model non-adiabatic effects due to the spider, and the predictions are compared with the experimental results. Improvements in beam quality are discussed relative to the use of a hole in a high permeability shield (i.e., in lieu of the spider), and areas for further improvement are described

  13. Simulation of electron transmittance and tunnel current in n{sup +} Poly-Si/HfSiO{sub x}N/Trap/SiO{sub 2}/Si(100) capacitors using analytical and numerical approaches

    Energy Technology Data Exchange (ETDEWEB)

    Noor, Fatimah A., E-mail: fatimah@fi.itb.ac.id; Iskandar, Ferry; Abdullah, Mikrajuddin; Khairurrijal [Physics of Electronic Materials Research Division Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung Jalan Ganesa 10, Bandung 40132 (Indonesia)

    2015-04-16

    In this paper, we discuss the electron transmittance and tunneling current in high-k-based-MOS capacitors with trapping charge by including the off-diagonal effective-mass tensor elements and the effect of coupling between transverse and longitudinal energies represented by an electron velocity in the gate. The HfSiO{sub x}N/SiO{sub 2} dual ultrathin layer is used as the gate oxide in an n{sup +} poly- Si/oxide/Si capacitor to replace SiO{sub 2}. The main problem of using HfSiO{sub x}N is the charge trapping formed at the HfSiO{sub x}N/SiO{sub 2} interface that can influence the performance of the device. Therefore, it is important to develop a model taking into account the presence of electron traps at the HfSiO{sub x}N/SiO{sub 2} interface in the electron transmittance and tunneling current. The transmittance and tunneling current in n{sup +} poly- Si/HfSiO{sub x}N/trap/SiO2/Si(100) capacitors are calculated by using Airy wavefunctions and a transfer matrix method (TMM) as analytical and numerical approaches, respectively. The transmittance and tunneling current obtained from the Airy wavefunction are compared to those computed by the TMM. The effects of the electron velocity on the transmittance and tunneling current are also discussed.

  14. Deuterium transport and trapping in polycrystalline tungsten

    International Nuclear Information System (INIS)

    Anderl, R.A.; Holland, D.F.; Longhurst, G.R.; Pawelko, R.J.; Trybus, C.L.; Sellers, C.H.

    1992-01-01

    This paper reports that deuterium permeation studies for polycrystalline tungsten foil have been conducted to provide data for estimating tritium transport and trapping in tungsten-clad divertors proposed for advanced fusion-reactor concepts. Based on a detailed transmission electron microscopy (TEM) microstructural characterization of the specimen material and on analyses of permeation data measured at temperatures ranging form 610 to 823 K for unannealed and annealed tungsten foil (25 μm thick), the authors note the following key results: deuterium transport in tungsten foil is dominated by extensive trapping that varies inversely with prior anneal temperatures of the foil material, the reduction in the trapped fraction correlates with a corresponding elimination of a high density of dislocations in cell-wall structures introduced during the foil fabrication process, trapping behavior in these foils can be modelled using trap energies between 1.3 eV and 1.5 eV and trap densities ranging from 1 x 10 -5 atom fraction

  15. Calculation of stationary plasma parameters in an electromagnetic trap

    International Nuclear Information System (INIS)

    Karpukhin, V.I.; Lavrent'ev, O.A.; Sappa, N.N.

    1978-01-01

    The model of energy and particle balance is considered and the numerical calculations for stationary plasma parameters, supported by the electron injection, are obtained for a hypothetical electromagnetic trap with linear dimensions, magnetic field strength and energy contribution to plasma of the order of these parameters for the modern tokamak-type traps. The process of limitation of an effective injection current and energy contribution to plasma caused by returning of electrons to the injector due to diffusion in the velocity space is simulated. In approximation of a classical diffusion dependences are obtained of the effective energy contribution to plasma and of the parameters ntausub(E) and Tsub(i) (n is a plasma density; tausub(E)- energetic lifetime; Tsub(i) ion temperature) on electron injection current and power and on the confining magnetic field strength. It had been established that at classical character of diffusion in electromagnetic trap with above parameters one could obtain stationary plasma with ntausub(E)=10 12 cm -3 s and Tsub(i)=1keV, maintaining only by electron injection

  16. High-precision measurement of the electron spin g factor of trapped atomic nitrogen in the endohedral fullerene N@C60

    Science.gov (United States)

    Wittmann, J. J.; Can, T. V.; Eckardt, M.; Harneit, W.; Griffin, R. G.; Corzilius, B.

    2018-05-01

    The electronic g factor carries highly useful information about the electronic structure of a paramagnetic species, such as spin-orbit coupling and dia- or paramagnetic (de-)shielding due to local fields of surrounding electron pairs. However, in many cases, a near "spin-only" case is observed, in particular for light elements, necessitating accurate and precise measurement of the g factors. Such measurement is typically impeded by a "chicken and egg situation": internal or external reference standards are used for relative comparison of electron paramagnetic resonance (EPR) Larmor frequencies. However, the g factor of the standard itself usually is subject to a significant uncertainty which directly limits the precision and/or accuracy of the sought after sample g factor. Here, we apply an EPR reference-free approach for determining the g factor of atomic nitrogen trapped within the endohedral fullerene C60:N@C60 in its polycrystalline state by measuring the 1H NMR resonance frequency of dispersing toluene at room temperature. We found a value of g = 2.00204 (4) with a finally reached relative precision of ∼20 ppm. This accurate measurement allows us to directly compare the electronic properties of N@C60 to those found in atomic nitrogen in the gas phase or trapped in other solid matrices at liquid helium temperature. We conclude that spin-orbit coupling in N@C60 at room temperature is very similar in magnitude and of same sign as found in other inert solid matrices and that interactions between the quartet spin system and the C60 molecular orbitals are thus negligible.

  17. Moessbauer spectroscopic study on valence-detrapping and trapping of mixed-valence trinuclear iron (III, III, II) fluorine-substitute benzoate complexes

    International Nuclear Information System (INIS)

    Sakai, Y.; Onaka, S.; Ogiso, R.; Takayama, T.; Takahashi, M.; Nakamoto, T.

    2012-01-01

    Four mixed-valence trinuclear iron(III, III, II) fluorine-substituted benzoate complexes were synthesized; Fe 3 O(C 6 F 5 COO) 6 (C 5 H 5 N) 3 ·CH 2 Cl 2 (1), Fe 3 O(C 6 F 5 COO) 6 (C 5 H 5 N) 3 (2), Fe 3 O(2H-C 6 F 4 COO) 6 (C 5 H 5 N) 3 (3), and Fe 3 O(4H-C 6 F 4 COO) 6 (C 5 H 5 N) 3 (4). By means of 57 Fe-Moessbauer spectroscopy, valence-detrapping and trapping phenomena have been investigated for the four mixed-valence complexes. The valence state of three iron ions is trapped at lower temperatures while it is fully detrapped at higher temperatures for 1. Valence detrapping is not observed for 2, 3, and 4 even at room temperature, although Moessbauer spectra for 3 and 4 show a complicated temperature dependence. (author)

  18. Conformational cycle of the vitamin B12 ABC importer in liposomes detected by double electron-electron resonance (DEER).

    Science.gov (United States)

    Joseph, Benesh; Korkhov, Vladimir M; Yulikov, Maxim; Jeschke, Gunnar; Bordignon, Enrica

    2014-02-07

    Double electron-electron resonance is used here to investigate intermediates of the transport cycle of the Escherichia coli vitamin B12 ATP-binding cassette importer BtuCD-F. Previously, we showed the ATP-induced opening of the cytoplasmic gate I in TM5 helices, later confirmed by the AMP-PNP-bound BtuCD-F crystal structure. Here, other key residues are analyzed in TM10 helices (positions 307 and 322) and in the cytoplasmic gate II, i.e. the loop between TM2 and TM3 (positions 82 and 85). Without BtuF, binding of ATP induces detectable changes at positions 307 and 85 in BtuCD in liposomes. Together with BtuF, ATP triggers the closure of the cytoplasmic gate II in liposomes (reported by both positions 82 and 85). This forms a sealed cavity in the translocation channel in agreement with the AMP-PNP·BtuCD-F x-ray structure. When vitamin B12 and AMP-PNP are simultaneously present, the extent of complex formation is reduced, but the short 82-82 interspin distance detected indicates that the substrate does not affect the closed conformation of this gate. The existence of the BtuCD-F complex under these conditions is verified with spectroscopically orthogonal nitroxide and Gd(III)-based labels. The cytoplasmic gate II remains closed also in the vanadate-trapped state, but it reopens in the ADP-bound state of the complex. Therefore, we suggest that the substrate likely trapped in ATP·BtuCD-F can be released after ATP hydrolysis but before the occluded ADP-bound conformation is reached.

  19. Laboratory X-ray Studies with Trapped Highly Charged Ions Using Synchrotrons and Free-electron Lasers

    Science.gov (United States)

    Crespo López-Urrutia, José R.

    2018-06-01

    Laboratory studies on highly charged ions (HCI) using electron beam ion traps (EBITs) can cover all charge states and chemical elements found in astrophysical sources. Since their introduction in 1986, a wealth of emission measurements from the optical to the x-ray range has been carried out by different groups. In most of the work, electron-impact excitation was the driving mechanism, and high resolution spectrometers were used for the diagnostic of the emitted radiation. Other recent studies included x-ray emission following charge exchange, a mechanism which is present in many astrophysical environments and can help explain some of the unknown spectral features at 3.55 keV.In the last decade, excitation and photoionization have also been investigated by exposing HCI trapped in an EBIT to intense, monochromatic radiation from free-electron lasers and synchrotron sources. Here, advanced monochromators in powerful undulator beamlines allowed us to work at photon energies from 50 eV to 15 keV while resolving the natural linewidths of x-ray transitions like the Kα complex of Fe up to the highest charge states, and to measure the oscillator strengths of, e. g., the neonlike Fe16+ spectrum. Photoionization studies have been performed for those species as well. Very recently, our novel compact EBIT with an off-axis electron gun allows for simultaneously using the photon beam downstream, enabling exact wavelength determinations referenced to HCI with accurately calculable transitions. We have performed a recalibration of the molecular and atomic oxygen soft x-ray absorption lines in the 500 eV range with an uncertainty estimate of 30 meV. This revealed a 600 meV calibration error that propagated through the literature for decades with the consequence of a 200 km/s misfit of the velocity in interstellar oxygen absorbers. Other possibilities for the compact EBIT are investigations of resonant photorecombination processes with excellent energy resolution. With the

  20. Ion trapping within the dust grain plasma sheath

    International Nuclear Information System (INIS)

    Jovanovic, D.; Shukla, P.K.

    2002-01-01

    One of the most important and still unresolved problems in the physics of dusty plasmas is the determination of the dust charge. The grains are not directly accessible to measurements and it is necessary to have a reliable theoretical model of the electron and ion dynamics inside the Debye sphere for the interpretation of the relevant experimental data, which include also the effects of the surrounding electron and ion clouds. Recent computer simulations [6] and laboratory experiments [9] indicate that the plasma sheath is dominated by trapped ions, orbiting the grain on closed trajectories at distances smaller than the Debye radius, that cannot be accounted for by the classical theories. We present the first analytical, fully self-consistent, calculations of the electrostatic shielding of a charged dust grain in a collisional plasma. In the regime when the mean free path for the ion-dust collisions is larger than that for the ion-neutral collisions, we solve the kinetic equation for the ions, coupled with Boltzmann distributed electrons and Poisson's equation. The ion velocity distribution function, in the form of a spherically symmetric ion hole, is found to be anisotropic in the presence of charge-exchange collisions. The number of trapped ions and their spatial distribution are determined from the interplay between the collective plasma interaction and the collisional trapping/de-trapping. The stationary state results from the self-tuning of the trapped ion density by the feedback based on the nonlocality of the collisional integral, and on the ion mixing in the radial direction along elongated orbits. Our results confirm the existence of a strong Debye shielding of the dust charge, allowing also the over-population of the trapped ion distribution (ion hump)

  1. Polarized electron cyclotron emission in the Tokapole II Tokamak

    International Nuclear Information System (INIS)

    Sengstacke, M.A.; Dexter, R.N.; Prager, S.C.

    1984-06-01

    To examine the effect of wall reflections we have measured the polarization of second harmonic cyclotron emission (at omega = 2 omega/sub ce/) in the Tokapole II tokamak both with and without a microwave absorber installed within the field of view of the receiving antenna. Indeed, the local elimination of wall reflections markedly enhances the polarization, as described in section II. Section III describes observations consistent with right-hand cutoff effects and an attempt to infer the electron temperature from cyclotron emission in an optically thin plasma

  2. Two-dimensional analysis of trapped-ion eigenmodes

    International Nuclear Information System (INIS)

    Marchand, R.; Tang, W.M.; Rewoldt, G.

    1979-11-01

    A fully two-dimensional eigenmode analysis of the trapped-ion instability in axisymmetric toroidal geometry is presented. The calculations also takes into account the basic dynamics associated with other low frequency modes such as the trapped-electron instability and the ion-temperature-gradient instability. The poloidal structure of the mode is taken into account by Fourier expanding the perturbed electrostatic potential, PHI, in theta

  3. Structural information on the coordination compounds formed by manganese(II), cobalt(II), nickel(II), zinc(II), cadmium(II) and mercury(II) thiocyanates with 4-cyanopyridine N-oxide from their magnetic moments, electronic and infrared spectra

    Science.gov (United States)

    Ahuja, I. S.; Yadava, C. L.; Singh, Raghuvir

    1982-05-01

    Coordination compounds formed by the interaction of 4-cyanopyridine. N-oxide (4-CPO), a potentially bidentate ligand, with manganese(II), cobalt(II), nickel(II), zinc(II), cadmium(II) and rnercury(II) thiocyanates have been prepared and characterized from their elemental analyses, magnetic susceptibilities, electronic and infrared spectral studies down to 200 cm -1 in the solid state. The compounds isolated are: Mn(4-CPO) 2(NCS) 2, Co(4-CPO) 2(NCS) 2,Ni(4-CPO) 2(NCS) 2,Zn(4-CPO) 2(NCS) 2, Cd(4-CPO)(NCS) 2 and Hg(4-CPO) 2(SCN) 2. It is shown that 4-CPO acts as a terminal N-oxide oxygen bonded monodentate ligand in all the metal(II) thiocyanate complexes studied. Tentative stereochemistries of the complexes in the solid state are discussed. The ligand field parameters 10 Dq, B, β and λ calculated for the manganese(II), cobalt(II) and nickel(II) complexes are consistent with their proposed stereochemistries.

  4. Optical Trapping of Ion Coulomb Crystals

    Science.gov (United States)

    Schmidt, Julian; Lambrecht, Alexander; Weckesser, Pascal; Debatin, Markus; Karpa, Leon; Schaetz, Tobias

    2018-04-01

    The electronic and motional degrees of freedom of trapped ions can be controlled and coherently coupled on the level of individual quanta. Assembling complex quantum systems ion by ion while keeping this unique level of control remains a challenging task. For many applications, linear chains of ions in conventional traps are ideally suited to address this problem. However, driven motion due to the magnetic or radio-frequency electric trapping fields sometimes limits the performance in one dimension and severely affects the extension to higher-dimensional systems. Here, we report on the trapping of multiple barium ions in a single-beam optical dipole trap without radio-frequency or additional magnetic fields. We study the persistence of order in ensembles of up to six ions within the optical trap, measure their temperature, and conclude that the ions form a linear chain, commonly called a one-dimensional Coulomb crystal. As a proof-of-concept demonstration, we access the collective motion and perform spectrometry of the normal modes in the optical trap. Our system provides a platform that is free of driven motion and combines advantages of optical trapping, such as state-dependent confinement and nanoscale potentials, with the desirable properties of crystals of trapped ions, such as long-range interactions featuring collective motion. Starting with small numbers of ions, it has been proposed that these properties would allow the experimental study of many-body physics and the onset of structural quantum phase transitions between one- and two-dimensional crystals.

  5. High-k shallow traps observed by charge pumping with varying discharging times

    Energy Technology Data Exchange (ETDEWEB)

    Ho, Szu-Han; Chen, Ching-En; Tseng, Tseung-Yuen [Department of Electronics Engineering, National Chiao Tung University, Hsinchu 300, Taiwan (China); Chang, Ting-Chang, E-mail: tcchang@mail.phys.nsysu.edu.tw [Department of Physics, National Sun Yat-Sen University, Kaohsiung 804, Taiwan (China); Advanced Optoelectronics Technology Center, National Cheng Kung University, Tainan, Taiwan (China); Lu, Ying-Hsin; Lo, Wen-Hung; Tsai, Jyun-Yu; Liu, Kuan-Ju [Department of Physics, National Sun Yat-Sen University, Kaohsiung 804, Taiwan (China); Wang, Bin-Wei; Cao, Xi-Xin [Department of Embedded System Engineering, Peking University, Beijing, P.R.China (China); Chen, Hua-Mao [Department of Photonics and Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu, Taiwan (China); Cheng, Osbert; Huang, Cheng-Tung; Chen, Tsai-Fu [Device Department, United Microelectronics Corporation, Tainan Science Park, Taiwan (China)

    2013-11-07

    In this paper, we investigate the influence of falling time and base level time on high-k bulk shallow traps measured by charge pumping technique in n-channel metal-oxide-semiconductor field-effect transistors with HfO{sub 2}/metal gate stacks. N{sub T}-V{sub high} {sub level} characteristic curves with different duty ratios indicate that the electron detrapping time dominates the value of N{sub T} for extra contribution of I{sub cp} traps. N{sub T} is the number of traps, and I{sub cp} is charge pumping current. By fitting discharge formula at different temperatures, the results show that extra contribution of I{sub cp} traps at high voltage are in fact high-k bulk shallow traps. This is also verified through a comparison of different interlayer thicknesses and different Ti{sub x}N{sub 1−x} metal gate concentrations. Next, N{sub T}-V{sub high} {sub level} characteristic curves with different falling times (t{sub falling} {sub time}) and base level times (t{sub base} {sub level}) show that extra contribution of I{sub cp} traps decrease with an increase in t{sub falling} {sub time}. By fitting discharge formula for different t{sub falling} {sub time}, the results show that electrons trapped in high-k bulk shallow traps first discharge to the channel and then to source and drain during t{sub falling} {sub time}. This current cannot be measured by the charge pumping technique. Subsequent measurements of N{sub T} by charge pumping technique at t{sub base} {sub level} reveal a remainder of electrons trapped in high-k bulk shallow traps.

  6. Secondary Electron Emission Yields from PEP-II Accelerator Materials

    International Nuclear Information System (INIS)

    Kirby, Robert E.

    2000-01-01

    The PEP-II B-Factory at SLAC operates with aluminum alloy and copper vacuum chambers, having design positron and electron beam currents of 2 and 1 A, respectively. Titanium nitride coating of the aluminum vacuum chamber in the arcs of the positron ring is needed in order to reduce undesirable electron-cloud effects. The total secondary electron emission yield of TiN-coated aluminum alloy has been measured after samples of beam chamber material were exposed to air and again after electron-beam bombardment, as a function of incident electron beam angle and energy. The results may be used to simulate and better understand electron-cloud effects under actual operating conditions. We also present yield measurements for other accelerator materials because new surface effects are expected to arise as beam currents increase. Copper, in particular, is growing in popularity for its good thermal conductivity and self-radiation-shielding properties. The effect of electron bombardment, ''conditioning'', on the yield of TiN and copper is shown

  7. N-tert-butylmethanimine N-oxide is an efficient spin-trapping probe for EPR analysis of glutathione thiyl radical

    Science.gov (United States)

    Scott, Melanie J.; Billiar, Timothy R.; Stoyanovsky, Detcho A.

    2016-01-01

    The electron spin resonance (EPR) spin-trapping technique allows detection of radical species with nanosecond half-lives. This technique is based on the high rates of addition of radicals to nitrones or nitroso compounds (spin traps; STs). The paramagnetic nitroxides (spin-adducts) formed as a result of reactions between STs and radical species are relatively stable compounds whose EPR spectra represent “structural fingerprints” of the parent radical species. Herein we report a novel protocol for the synthesis of N-tert-butylmethanimine N-oxide (EBN), which is the simplest nitrone containing an α-H and a tertiary α′-C atom. We present EPR spin-trapping proof that: (i) EBN is an efficient probe for the analysis of glutathione thiyl radical (GS•); (ii) β-cyclodextrins increase the kinetic stability of the spin-adduct EBN/•SG; and (iii) in aqueous solutions, EBN does not react with superoxide anion radical (O2−•) to form EBN/•OOH to any significant extent. The data presented complement previous studies within the context of synthetic accessibility to EBN and efficient spin-trapping analysis of GS•. PMID:27941944

  8. Trapped particle stability for the kinetic stabilizer

    Science.gov (United States)

    Berk, H. L.; Pratt, J.

    2011-08-01

    A kinetically stabilized axially symmetric tandem mirror (KSTM) uses the momentum flux of low-energy, unconfined particles that sample only the outer end-regions of the mirror plugs, where large favourable field-line curvature exists. The window of operation is determined for achieving magnetohydrodynamic (MHD) stability with tolerable energy drain from the kinetic stabilizer. Then MHD stable systems are analysed for stability of the trapped particle mode. This mode is characterized by the detachment of the central-cell plasma from the kinetic-stabilizer region without inducing field-line bending. Stability of the trapped particle mode is sensitive to the electron connection between the stabilizer and the end plug. It is found that the stability condition for the trapped particle mode is more constraining than the stability condition for the MHD mode, and it is challenging to satisfy the required power constraint. Furthermore, a severe power drain may arise from the necessary connection of low-energy electrons in the kinetic stabilizer to the central region.

  9. Electrostatic modes as a diagnostic in Penning-trap experiments

    International Nuclear Information System (INIS)

    Weimer, C.S.; Bollinger, J.J.; Moore, F.L.; Wineland, D.J.

    1994-01-01

    A subset of the electrostatic modes of a cold cloud of electrons, a non-neutral electron plasma, trapped in a Penning trap has been observed and identified using a recent theoretical model. The detection of these modes is accomplished using electronic techniques which could apply to any ion species. The modes are observed in the low-density, low-rotation limit of the cloud where the cloud approaches a two-dimensional charged disk. We observe both axially symmetric and asymmetric drumhead modes. The shape, rotation frequency, and density of the cloud are found in a real-time nondestructive manner by measuring the frequency of these modes. In addition, it is found that radio-frequency sideband cooling compresses the cloud, increasing its density. The ability to measure and control the density of a trapped ion cloud might be useful for experiments on low-temperature ion--neutral-atom collisions, recombination rates, and studies of the confinement properties of non-neutral plasmas

  10. RADLAC II high current electron beam propagation experiment

    International Nuclear Information System (INIS)

    Frost, C.A.; Shope, S.L.; Mazarakis, M.G.; Poukey, J.W.; Wagner, J.S.; Turman, B.N.; Crist, C.E.; Welch, D.R.; Struve, K.W.

    1993-01-01

    The resistive hose instability of an electron beam was observed to be convective in recent RADLAC II experiments for higher current shots. The effects of air scattering for these shots were minimal. These experiments and theory suggest low-frequency hose motion which does not appear convective may be due to rapid expansion and subsequent drifting of the beam nose

  11. Hydrogen passivation of electron trap in amorphous In-Ga-Zn-O thin-film transistors

    International Nuclear Information System (INIS)

    Hanyu, Yuichiro; Domen, Kay; Nomura, Kenji; Hiramatsu, Hidenori; Kamiya, Toshio; Kumomi, Hideya; Hosono, Hideo

    2013-01-01

    We report an experimental evidence that some hydrogens passivate electron traps in an amorphous oxide semiconductor, a-In-Ga-Zn-O (a-IGZO). The a-IGZO thin-film transistors (TFTs) annealed at 300 °C exhibit good operation characteristics; while those annealed at ≥400 °C show deteriorated ones. Thermal desorption spectra (TDS) of H 2 O indicate that this threshold annealing temperature corresponds to depletion of H 2 O desorption from the a-IGZO layer. Hydrogen re-doping by wet oxygen annealing recovers the good TFT characteristic. The hydrogens responsible for this passivation have specific binding energies corresponding to the desorption temperatures of 300–430 °C. A plausible structural model is suggested

  12. Trapped-particle instabilities in quasi-isodynamic stellarators

    Energy Technology Data Exchange (ETDEWEB)

    Proll, Josefine Henriette Elise

    2014-01-28

    approximately in quasi-isodynamic stellarators, for example Wendelstein 7-X. In such configurations the precessional drift of the trapped particles is in the opposite direction from the direction of propagation of drift waves. Instabilities that are driven by the trapped particles usually rely on a resonance between these two frequencies. Here it is shown analytically by analysing the electrostatic energy transfer between the particles and the instability that, thanks to the absence of the resonance, a particle species draws energy from the mode if the frequency of the mode is well below the characteristic bounce frequency. Due to the low electron mass and the fast bounce motion, electrons are almost always found to be stabilising. Most of the trapped-particle instabilities are therefore predicted to be absent in maximum- J configurations in large parts of parameter space. Analytical theory thus predicts enhanced linear stability of trapped-particle modes in quasi-isodynamic stellarators compared with tokamaks. Moreover, since the electrons are expected to be stabilising, or at least less destabilising, for all instabilities whose frequency lies below the trapped-electron bounce frequency, other modes might benefit from the enhanced stability as well. In reality, however, stellarators are never perfectly quasi-isodynamic, and the question thus arises whether they still benefit from enhanced stability. Here the stability properties of Wendelstein 7-X and a more quasi-isodynamic configuration, QIPC, are investigated numerically and compared with another, non-quasiisodynamic stellarator, the National Compact Stellarator Experiment (NCSX) and a typical tokamak. In gyrokinetic simulations, performed with the gyrokinetic code GENE in the electrostatic and collisionless approximation, several microinstabilities, driven by the density as well as both ion and electron temperature gradients, are studied. Wendelstein 7-X and QIPC exhibit significantly reduced growth rates for all

  13. Trapped-particle instabilities in quasi-isodynamic stellarators

    International Nuclear Information System (INIS)

    Proll, Josefine Henriette Elise

    2014-01-01

    approximately in quasi-isodynamic stellarators, for example Wendelstein 7-X. In such configurations the precessional drift of the trapped particles is in the opposite direction from the direction of propagation of drift waves. Instabilities that are driven by the trapped particles usually rely on a resonance between these two frequencies. Here it is shown analytically by analysing the electrostatic energy transfer between the particles and the instability that, thanks to the absence of the resonance, a particle species draws energy from the mode if the frequency of the mode is well below the characteristic bounce frequency. Due to the low electron mass and the fast bounce motion, electrons are almost always found to be stabilising. Most of the trapped-particle instabilities are therefore predicted to be absent in maximum- J configurations in large parts of parameter space. Analytical theory thus predicts enhanced linear stability of trapped-particle modes in quasi-isodynamic stellarators compared with tokamaks. Moreover, since the electrons are expected to be stabilising, or at least less destabilising, for all instabilities whose frequency lies below the trapped-electron bounce frequency, other modes might benefit from the enhanced stability as well. In reality, however, stellarators are never perfectly quasi-isodynamic, and the question thus arises whether they still benefit from enhanced stability. Here the stability properties of Wendelstein 7-X and a more quasi-isodynamic configuration, QIPC, are investigated numerically and compared with another, non-quasiisodynamic stellarator, the National Compact Stellarator Experiment (NCSX) and a typical tokamak. In gyrokinetic simulations, performed with the gyrokinetic code GENE in the electrostatic and collisionless approximation, several microinstabilities, driven by the density as well as both ion and electron temperature gradients, are studied. Wendelstein 7-X and QIPC exhibit significantly reduced growth rates for all

  14. Retrospective accident dosimetry using trapped charges

    Energy Technology Data Exchange (ETDEWEB)

    Lee, J. I.; Kim, J. L.; Chang, I.; Kim, B. H. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    Dicentric chromosome aberrations technique scoring of aberrations in metaphases prepared from human lymphocytes is most commonly used. This is considered as a reliable technique because the sample is extracted from the individual human body itself. There are other techniques in biological dosimetry such as Fluorescence In Situ Hybridization (FISH) using translocations, premature chromosome condensation (PCC) and micronucleus assay. However the minimum detectable doses (MDD) are relatively high and sample preparation time is also relatively longer. Therefore, there is limitation in use of these techniques for the purpose of triage in a short time in case of emergency situation relating large number of persons. Electronic paramagnetic resonance (EPR) technique is based on the signal from unpaired electrons such as free radicals in irradiated materials especially tooth enamel, however it has also limitation for the purpose of triage because of difficulty of sample taking and its high MDD. Recently as physical methods, thermoluminescence (TL) and optically stimulated luminescence (OSL) technique have been attracted due to its lower MDD and simplicity of sample preparation. Density of the trapped charges is generally proportional to the radiation dose absorbed and the intensity of emitting light is also proportional to the density of trapped charges, thus it can be applied to measure radiation dose retrospectively. In this presentation, TL and OSL techniques are going to introduced and discussed as physical methods for retrospective accident dosimetry using trapped charges especially in electronic component materials. As a tool for dose reconstruction for emergency situation, thermoluminescece and optically stimulated luminescence techniques which are based on trapped charges during exposure of material are introduced. These techniques have several advantages such as high sensitivity, fast evaluation and ease to sample collection over common biological dosimetry and EPR

  15. All-optical atom trap as a target for MOTRIMS-like collision experiments

    Science.gov (United States)

    Sharma, S.; Acharya, B. P.; De Silva, A. H. N. C.; Parris, N. W.; Ramsey, B. J.; Romans, K. L.; Dorn, A.; de Jesus, V. L. B.; Fischer, D.

    2018-04-01

    Momentum-resolved scattering experiments with laser-cooled atomic targets have been performed since almost two decades with magneto-optical trap recoil ion momentum spectroscopy (MOTRIMS) setups. Compared to experiments with gas-jet targets, MOTRIMS features significantly lower target temperatures allowing for an excellent recoil ion momentum resolution. However, the coincident and momentum-resolved detection of electrons was long rendered impossible due to incompatible magnetic field requirements. Here we report on an experimental approach which is based on an all-optical 6Li atom trap that—in contrast to magneto-optical traps—does not require magnetic field gradients in the trapping region. Atom temperatures of about 2 mK and number densities up to 109 cm-3 make this trap ideally suited for momentum-resolved electron-ion coincidence experiments. The overall configuration of the trap is very similar to conventional magneto-optical traps. It mainly requires small modifications of laser beam geometries and polarization which makes it easily implementable in other existing MOTRIMS experiments.

  16. Progress towards magnetic trapping of ultra-cold neutrons

    CERN Document Server

    Huffman, P R; Butterworth, J S; Coakley, K J; Dewey, M S; Dzhosyuk, S N; Gilliam, D M; Golub, R; Greene, G L; Habicht, K; Lamoreaux, S K; Mattoni, C E H; McKinsey, D N; Wietfeldt, F E; Doyle, J M

    2000-01-01

    We report progress towards magnetic trapping of ultra-cold neutrons (UCN) in preparation for a neutron lifetime measurement. UCN will be produced by inelastic scattering of cold (0.89 nm) neutrons in a reservoir of superfluid sup 4 He and confined in a three-dimensional magnetic trap. As the trapped neutrons decay, recoil electrons will generate scintillations in the liquid He, which should be detectable with nearly 100% efficiency. This direct measure of the number of UCN decays vs. time can be used to determine the neutron beta-decay lifetime.

  17. Radiation effects on II-VI compound-based detectors

    CERN Document Server

    Cavallini, A; Dusi, W; Auricchio, N; Chirco, P; Zanarini, M; Siffert, P; Fougeres, P

    2002-01-01

    The performance of room temperature CdTe and CdZnTe detectors exposed to a radiation source can be strongly altered by the interaction of the ionizing particles and the material. Up to now, few experimental data are available on the response of II-VI compound detectors to different types of radiation sources. We have carried out a thorough investigation on the effects of gamma-rays, neutrons and electron irradiation both on CdTe : Cl and Cd sub 0 sub . sub 9 Zn sub 0 sub . sub 1 Te detectors. We have studied the detector response after radiation exposure by means of dark current measurements and of quantitative spectroscopic analyses at low and medium energies. The deep traps present in the material have been characterized by means of PICTS (photo-induced current transient spectroscopy) analyses, which allow to determine the trap apparent activation energy and capture cross-section. The evolution of the trap parameters with increasing irradiation doses has been monitored for all the different types of radiati...

  18. Optical Trapping of Ion Coulomb Crystals

    Directory of Open Access Journals (Sweden)

    Julian Schmidt

    2018-05-01

    Full Text Available The electronic and motional degrees of freedom of trapped ions can be controlled and coherently coupled on the level of individual quanta. Assembling complex quantum systems ion by ion while keeping this unique level of control remains a challenging task. For many applications, linear chains of ions in conventional traps are ideally suited to address this problem. However, driven motion due to the magnetic or radio-frequency electric trapping fields sometimes limits the performance in one dimension and severely affects the extension to higher-dimensional systems. Here, we report on the trapping of multiple barium ions in a single-beam optical dipole trap without radio-frequency or additional magnetic fields. We study the persistence of order in ensembles of up to six ions within the optical trap, measure their temperature, and conclude that the ions form a linear chain, commonly called a one-dimensional Coulomb crystal. As a proof-of-concept demonstration, we access the collective motion and perform spectrometry of the normal modes in the optical trap. Our system provides a platform that is free of driven motion and combines advantages of optical trapping, such as state-dependent confinement and nanoscale potentials, with the desirable properties of crystals of trapped ions, such as long-range interactions featuring collective motion. Starting with small numbers of ions, it has been proposed that these properties would allow the experimental study of many-body physics and the onset of structural quantum phase transitions between one- and two-dimensional crystals.

  19. The Multipole Plasma Trap-PIC Modeling Results

    Science.gov (United States)

    Hicks, Nathaniel; Bowman, Amanda; Godden, Katarina

    2017-10-01

    A radio-frequency (RF) multipole structure is studied via particle-in-cell computer modeling, to assess the response of quasi-neutral plasma to the imposed RF fields. Several regimes, such as pair plasma, antimatter plasma, and conventional (ion-electron) plasma are considered. In the case of equal charge-to-mass ratio of plasma species, the effects of the multipole field are symmetric between positive and negative particles. In the case of a charge-to-mass disparity, the multipole RF parameters (frequency, voltage, structure size) may be chosen such that the light species (e.g. electrons) is strongly confined, while the heavy species (e.g. positive ions) does not respond to the RF field. In this case, the trapped negative space charge creates a potential well that then traps the positive species. 2D and 3D particle-in-cell simulations of this concept are presented, to assess plasma response and trapping dependences on multipole order, consequences of the formation of an RF plasma sheath, and the effects of an axial magnetic field. The scalings of trapped plasma parameters are explored in each of the mentioned regimes, to guide the design of prospective experiments investigating each. Supported by U.S. NSF/DOE Partnership in Basic Plasma Science and Engineering Grant PHY-1619615.

  20. Identification of mitochondrial electron transport chain-mediated NADH radical formation by EPR spin-trapping techniques.

    Science.gov (United States)

    Matsuzaki, Satoshi; Kotake, Yashige; Humphries, Kenneth M

    2011-12-20

    The mitochondrial electron transport chain (ETC) is a major source of free radical production. However, due to the highly reactive nature of radical species and their short lifetimes, accurate detection and identification of these molecules in biological systems is challenging. The aim of this investigation was to determine the free radical species produced from the mitochondrial ETC by utilizing EPR spin-trapping techniques and the recently commercialized spin-trap, 5-(2,2-dimethyl-1,3-propoxycyclophosphoryl)-5-methyl-1-pyrroline N-oxide (CYPMPO). We demonstrate that this spin-trap has the preferential quality of having minimal mitochondrial toxicity at concentrations required for radical detection. In rat heart mitochondria and submitochondrial particles supplied with NADH, the major species detected under physiological pH was a carbon-centered radical adduct, indicated by markedly large hyperfine coupling constant with hydrogen (a(H) > 2.0 mT). In the presence of the ETC inhibitors, the carbon-centered radical formation was increased and exhibited NADH concentration dependency. The same carbon-centered radical could also be produced with the NAD biosynthesis precursor, nicotinamide mononucleotide, in the presence of a catalytic amount of NADH. The results support the conclusion that the observed species is a complex I derived NADH radical. The formation of the NADH radical could be blocked by hydroxyl radical scavengers but not SOD. In vitro experiments confirmed that an NADH-radical is readily formed by hydroxyl radical but not superoxide anion, further implicating hydroxyl radical as an upstream mediator of NADH radical production. These findings demonstrate the identification of a novel mitochondrial radical species with potential physiological significance and highlight the diverse mechanisms and sites of production within the ETC.

  1. MARK II end cap calorimeter electronics

    International Nuclear Information System (INIS)

    Jared, R.C.; Haggerty, J.S.; Herrup, D.A.; Kirsten, F.A.; Lee, K.L.; Olson, S.R.; Wood, D.R.

    1985-10-01

    An end cap calorimeter system has been added to the MARK II detector in preparation for its use at the SLAC Linear Collider. The calorimeter uses 8744 rectangular proportional counter tubes. This paper describes the design features of the data acquisition electronics that has been installed on the calorimeter. The design and use of computer-based test stands for the amplification and signal-shaping components is also covered. A portion of the complete system has been tested in a beam at SLAC. In these initial tests, using only the calibration provided by the test stands, a resolution of 18%/√E was achieved

  2. Radiation Dose from Reentrant Electrons

    Science.gov (United States)

    Badhwar, G.D.; Cleghorn, T. E.; Watts, J.

    2003-01-01

    In estimating the crew exposures during an EVA, the contribution of reentrant electrons has always been neglected. Although the flux of these electrons is small compared to the flux of trapped electrons, their energy spectrum extends to several GeV compared to about 7 MeV for trapped electrons. This is also true of splash electrons. Using the measured reentrant electron energy spectra, it is shown that the dose contribution of these electrons to the blood forming organs (BFO) is more than 10 times greater than that from the trapped electrons. The calculations also show that the dose-depth response is a very slowly changing function of depth, and thus adding reasonable amounts of additional shielding would not significantly lower the dose to BFO.

  3. Synthesis, EPR, Electronic and Magnetic Studies on Cobalt (II) Complexes of Semicarbazone and Thiosemicarbazone

    International Nuclear Information System (INIS)

    Chandra, S.; Gupta, L.K.; Sharma, K.K.

    2005-01-01

    Cobalt (II) complexes having the general composition Co(L2) X2 [where Lisopropyl methyl ketone semicarbazone (LLA), isopropyl methyl ketone thiosemicarbazone (LLB), 4-aminoacetophenone semicarbazone (LLC) and4-aminoacetophenone thiosemicarbazone (LLD) and X=Cl] have been synthesized. All the Co(II) complexes reported here have been characterized by elemental analyses, magnetic moments, IR, electronic and EPR spectral studies. All the complexes were found to have magnetic moments corresponding to three unpaired electrons. The possible geometries of the complexes were assigned on the basis of electronic infrared and EPR spectral studies. (author) = = = = = = = = = = = = = = =

  4. Highly charged ion trapping and cooling

    International Nuclear Information System (INIS)

    Beck, B. R.; Church, D. A.; Gruber, L.; Holder, J. P.; Schneider, D.; Steiger, J.

    1998-01-01

    In the past few years a cryogenic Penning trap (RETRAP) has been operational at the Electron Beam Ion Trap (EBIT) facility at Lawrence Livermore National Laboratory. The combination of RETRAP and EBIT provides a unique possibility of producing and re-trapping highly charged ions and cooling them to very low temperatures. Due to the high Coulomb potentials in such an ensemble of cold highly charged ions the Coulomb coupling parameter (the ratio of Coulomb potential to the thermal energy) can easily reach values of 172 and more. To study such systems is not only of interest in astrophysics to simulate White Dwarf star interiors but opens up new possibilities in a variety of areas (e.g. laser spectroscopy), cold highly charged ion beams

  5. Hydrogen passivation of electron trap in amorphous In-Ga-Zn-O thin-film transistors

    Energy Technology Data Exchange (ETDEWEB)

    Hanyu, Yuichiro, E-mail: y-hanyu@lucid.msl.titech.ac.jp; Domen, Kay [Materials and Structures Laboratory, Tokyo Institute of Technology, Yokohama (Japan); Nomura, Kenji [Frontier Research Center, Tokyo Institute of Technology, Yokohama (Japan); Hiramatsu, Hidenori; Kamiya, Toshio [Materials and Structures Laboratory, Tokyo Institute of Technology, Yokohama (Japan); Materials Research Center for Element Strategy, Tokyo Institute of Technology, Yokohama (Japan); Kumomi, Hideya [Materials Research Center for Element Strategy, Tokyo Institute of Technology, Yokohama (Japan); Hosono, Hideo [Materials and Structures Laboratory, Tokyo Institute of Technology, Yokohama (Japan); Frontier Research Center, Tokyo Institute of Technology, Yokohama (Japan); Materials Research Center for Element Strategy, Tokyo Institute of Technology, Yokohama (Japan)

    2013-11-11

    We report an experimental evidence that some hydrogens passivate electron traps in an amorphous oxide semiconductor, a-In-Ga-Zn-O (a-IGZO). The a-IGZO thin-film transistors (TFTs) annealed at 300 °C exhibit good operation characteristics; while those annealed at ≥400 °C show deteriorated ones. Thermal desorption spectra (TDS) of H{sub 2}O indicate that this threshold annealing temperature corresponds to depletion of H{sub 2}O desorption from the a-IGZO layer. Hydrogen re-doping by wet oxygen annealing recovers the good TFT characteristic. The hydrogens responsible for this passivation have specific binding energies corresponding to the desorption temperatures of 300–430 °C. A plausible structural model is suggested.

  6. An optical trap for relativistic plasma

    International Nuclear Information System (INIS)

    Zhang Ping; Saleh, Ned; Chen Shouyuan; Sheng Zhengming; Umstadter, Donald

    2003-01-01

    The first optical trap capable of confining relativistic electrons, with kinetic energy ≤350 keV was created by the interference of spatially and temporally overlapping terawatt power, 400 fs duration laser pulses (≤2.4x10 18 W/cm 2 ) in plasma. Analysis and computer simulation predicted that the plasma density was greatly modulated, reaching a peak density up to 10 times the background density (n e /n 0 ∼10) at the interference minima. Associated with this charge displacement, a direct-current electrostatic field of strength of ∼2x10 11 eV/m was excited. These predictions were confirmed experimentally by Thomson and Raman scattering diagnostics. Also confirmed were predictions that the electron density grating acted as a multi-layer mirror to transfer energy between the crossed laser beams, resulting in the power of the weaker laser beam being nearly 50% increased. Furthermore, it was predicted that the optical trap acted to heat electrons, increasing their temperature by two orders of magnitude. The experimental results showed that the number of high energy electrons accelerated along the direction of one of the laser beams was enhanced by a factor of 3 and electron temperature was increased ∼100 keV as compared with single-beam illumination

  7. The InP - SiO2 interface: Electron tunneling into oxide traps

    International Nuclear Information System (INIS)

    Prasad, S.J.; Owen, S.J.T.

    1985-01-01

    Indium Phosphide is an attractive material for high-speed devices. Though many successful devices have been built and demonstrated, InP MISFET's still suffer from drain current drift. From the data current drift measurements, the shift in the threshold voltage ΔV was computed for different times. It was found that a linear relationship exists between √ΔV and log(t). When a positive bias-stress was applied to the gate of an MIS capacitor for a time t, the C-V cure shifted by an amount ΔV and again, a linear relationship was observed between √ΔV and log(t). This was verified on four different gate insulators: pyrolytic SiO 2 at 320 0 C and 360 0 C, plasma oxide at 300 0 C and photo CVD oxide at 225 0 C. These results can only be explained by a model in which electrons tunnel from the substrate into oxide traps

  8. ESR study on free radicals trapped in crosslinked polytetrafluoroethylene (PTFE)

    International Nuclear Information System (INIS)

    Oshima, Akihiro; Tabata, Yoneho; Seguchi, Tadao

    1997-01-01

    Free radicals in crosslinked PTFE which formed by 60 Co γ-rays irradiation at 77 K and at room temperature were studied by electron spin resonance (ESR) spectroscopy. The crosslinked PTFE specimens with different crosslinking density were prepared by electron beam irradiation in the molten state. The ESR spectra observed in the irradiated crosslinked PTFE are much different from those in non-crosslinked PTFE (virgin); a broad singlet component increases with increasing the crosslinking density, G-value of radicals is much higher in crosslinked PTFE than in non-crosslinked one. Free radicals related to the broad component are trapped in the non-crystalline region of crosslinked PTFE and rather stable at room temperature, whereas radicals trapped in amorphous non-crosslinked PTFE are unstable at room temperature. It is thought that most of free radicals trapped in the crosslinked PTFE are formed in the crosslinked amorphous region. The trapped radicals decays around 383 K (110 o C) due to the molecular motion of α-relaxation. (Author)

  9. Colloquium: Quantum Networks with Trapped Ions

    Science.gov (United States)

    2010-04-28

    observed be- tween two ions held in the same trap Eichmann et al., 1993; DeVoe and Brewer, 1996. Type-II links have the advantage of being less sensitive...Childress, E. Jiang, J. Togan, J. Maze, F. Jelezko, A. S. Zibrov, P. R. Hemmer, and M. D. Lukin, 2007, Science 316, 1312. Eichmann , U., J. C. Bergquist

  10. Resilience offers escape from trapped thinking on poverty alleviation.

    Science.gov (United States)

    Lade, Steven J; Haider, L Jamila; Engström, Gustav; Schlüter, Maja

    2017-05-01

    The poverty trap concept strongly influences current research and policy on poverty alleviation. Financial or technological inputs intended to "push" the rural poor out of a poverty trap have had many successes but have also failed unexpectedly with serious ecological and social consequences that can reinforce poverty. Resilience thinking can help to (i) understand how these failures emerge from the complex relationships between humans and the ecosystems on which they depend and (ii) navigate diverse poverty alleviation strategies, such as transformative change, that may instead be required. First, we review commonly observed or assumed social-ecological relationships in rural development contexts, focusing on economic, biophysical, and cultural aspects of poverty. Second, we develop a classification of poverty alleviation strategies using insights from resilience research on social-ecological change. Last, we use these advances to develop stylized, multidimensional poverty trap models. The models show that (i) interventions that ignore nature and culture can reinforce poverty (particularly in agrobiodiverse landscapes), (ii) transformative change can instead open new pathways for poverty alleviation, and (iii) asset inputs may be effective in other contexts (for example, where resource degradation and poverty are tightly interlinked). Our model-based approach and insights offer a systematic way to review the consequences of the causal mechanisms that characterize poverty traps in different agricultural contexts and identify appropriate strategies for rural development challenges.

  11. Resilience offers escape from trapped thinking on poverty alleviation

    Science.gov (United States)

    Lade, Steven J.; Haider, L. Jamila; Engström, Gustav; Schlüter, Maja

    2017-01-01

    The poverty trap concept strongly influences current research and policy on poverty alleviation. Financial or technological inputs intended to “push” the rural poor out of a poverty trap have had many successes but have also failed unexpectedly with serious ecological and social consequences that can reinforce poverty. Resilience thinking can help to (i) understand how these failures emerge from the complex relationships between humans and the ecosystems on which they depend and (ii) navigate diverse poverty alleviation strategies, such as transformative change, that may instead be required. First, we review commonly observed or assumed social-ecological relationships in rural development contexts, focusing on economic, biophysical, and cultural aspects of poverty. Second, we develop a classification of poverty alleviation strategies using insights from resilience research on social-ecological change. Last, we use these advances to develop stylized, multidimensional poverty trap models. The models show that (i) interventions that ignore nature and culture can reinforce poverty (particularly in agrobiodiverse landscapes), (ii) transformative change can instead open new pathways for poverty alleviation, and (iii) asset inputs may be effective in other contexts (for example, where resource degradation and poverty are tightly interlinked). Our model-based approach and insights offer a systematic way to review the consequences of the causal mechanisms that characterize poverty traps in different agricultural contexts and identify appropriate strategies for rural development challenges. PMID:28508077

  12. Possibilities for achieving antihydrogen recombination and trapping using a nested Penning trap and a magnetic well

    International Nuclear Information System (INIS)

    Ordonez, C.A.; Dolliver, D.D.; Chang Yongbin; Correa, J. R.

    2002-01-01

    A theoretical study is presented regarding some possibilities for achieving antihydrogen recombination and trapping using a nested Penning trap and a magnetic well. The work reported consists of a review, an extension, and applications of the relevant knowledge base. A nested Penning trap produces a magnetic field, which provides plasma confinement perpendicular to the magnetic field, and an electric field associated with a nested-well potential profile. The nested-well potential profile provides plasma confinement parallel to the magnetic field for oppositely signed plasma species that can have overlapping confinement regions. A configuration is considered in which the electric field is applied in two regions of uniform magnetic field that reside on opposite sides of a magnetic well region. The electric field confines overlapping positron and antiproton plasmas, which thread the magnetic well region. The magnetic well region would serve to trap a fraction of any antihydrogen atoms that are formed. Two different methods are considered for achieving overlap of positron and antiproton plasmas. For each, a set of conditions is predicted for achieving antihydrogen recombination and trapping. Although the study reported specifically considers simultaneous confinement of positron and antiproton plasmas in nested Penning traps, much of the information presented is also relevant to the prospect of merging other pairs of oppositely signed plasmas (e.g., electron and positron plasmas)

  13. Neutral atom traps of radioactives

    International Nuclear Information System (INIS)

    Behr, J.A.

    2003-01-01

    Neutral atoms trapped with modern laser cooling techniques offer the promise of improving several broad classes of experiments with radioactive isotopes. In nuclear β decay, neutrino spectroscopy from beta-recoil coincidences, along with highly polarized samples, enable experiments to search for non-Standard Model interactions, test whether parity symmetry is maximally violated, and search for new sources of time reversal violation. Ongoing efforts at TRIUMF, Los Alamos and Berkeley will be highlighted. The traps also offer bright sources for Doppler-free spectroscopy, particularly in high-Z atoms where precision measurements could measure the strength of weak neutral nucleon-nucleon and electron-nucleon interactions. Physics with francium atoms has been vigorously pursued at Stony Brook. Several facilities plan work with radioactive atom traps; concrete plans and efforts at KVI Groningen and Legnaro will be among those summarized. Contributions to the multidisciplinary field of trace analysis will be left up to other presenters

  14. Neutral atom traps of radioactives

    CERN Document Server

    Behr, J A

    2003-01-01

    Neutral atoms trapped with modern laser cooling techniques offer the promise of improving several broad classes of experiments with radioactive isotopes. In nuclear beta decay, neutrino spectroscopy from beta-recoil coincidences, along with highly polarized samples, enable experiments to search for non-Standard Model interactions, test whether parity symmetry is maximally violated, and search for new sources of time reversal violation. Ongoing efforts at TRIUMF, Los Alamos and Berkeley will be highlighted. The traps also offer bright sources for Doppler-free spectroscopy, particularly in high-Z atoms where precision measurements could measure the strength of weak neutral nucleon-nucleon and electron-nucleon interactions. Physics with francium atoms has been vigorously pursued at Stony Brook. Several facilities plan work with radioactive atom traps; concrete plans and efforts at KVI Groningen and Legnaro will be among those summarized. Contributions to the multidisciplinary field of trace analysis will be left...

  15. Trapping molecules in two and three dimensions

    International Nuclear Information System (INIS)

    Pinkse, PW.H.; Junglen, T.; Rieger, T.; Rangwala, S.A.; Windpassinger, P.; Rempe, G.

    2005-01-01

    Full text: Cold molecules offer a new testing ground for quantum-physical effects in nature. For example, producing slow beams of large molecules could push experiments studying the boundary between quantum interference and classical particles up towards ever heavier particles. Moreover, cold molecules, in particular YbF, seem an attractive way to narrow down the constraints on the value of the electron dipole moment and finally, quantum information processing using chains of cold polar molecules or vibrational states in molecules have been proposed. All these proposals rely on advanced production and trapping techniques, most of which are still under development. Therefore, novel production and trapping techniques for cold molecules could offer new possibilities not found in previous methods. Electric traps hold promise for deep trap potentials for neutral molecules. Recently we have demonstrated two-dimensional trapping of polar molecules in a four-wire guide using electrostatic and electrodynamic trapping techniques. Filled from a thermal effusive source, such a guide will deliver a beam of slow molecules, which is an ideal source for interferometry experiments with large molecules, for instance. Here we report about the extension of this work to three-dimensional trapping. Polar molecules with a positive Stark shift can be trapped in the minimum of an electrostatic field. We have successfully tested a large volume electrostatic trap for ND3 molecules. A special feature of this trap is that it can be loaded continuously from an electrostatic guide, at a temperature of a few hundred mK. (author)

  16. Deep traps at GaAs/GaAs interface grown by MBE-interruption growth technique

    International Nuclear Information System (INIS)

    Kaniewska, M.; Engstroem, O.

    2007-01-01

    Electron trapping centers at the GaAs/GaAs interface grown by molecular beam epitaxy (MBE)-interruption growth technique have been studied by capacitance versus voltage (C-V) measurements and deep level transient spectroscopy (DLTS). Two main electron traps have been revealed with activation energies at 0.16 eV and 0.52 eV from the conduction band. Inhomogeneous spatial distributions of the traps, obtained by DLTS profiling, indicate that they are agglomerated at the interrupted interface on a concentration level of (2-3) x 10 15 cm -3 at their maximum. Their behaviour is typical of acceptor-like traps when investigating by C-V profiling as a function of temperature. Based on a comparison made with electron traps in MBE-GaAs as well as with the traps in InAs/GaAs quantum dot/quantum well (QD/QW) structures, we conclude they are the well-known EL10 and EL4 defects, respectively, and their concentrations are growth condition dependent. They may be point defect-impurity complexes. Their presence may cause interpretation and application problems of the low-dimensional InAs/GaAs structures

  17. Deep traps at GaAs/GaAs interface grown by MBE-interruption growth technique

    Energy Technology Data Exchange (ETDEWEB)

    Kaniewska, M. [Department of Analysis of Semicoductor Nanostructures, Institute of Electron Technology, Al. Lotnikow 32/46, 02-668 Warsaw (Poland)], E-mail: kaniew@ite.waw.pl; Engstroem, O. [Department of Microtechnology and Nanoscience, Chalmers University of Technology, SE-412 96 Goeteborg (Sweden)

    2007-09-15

    Electron trapping centers at the GaAs/GaAs interface grown by molecular beam epitaxy (MBE)-interruption growth technique have been studied by capacitance versus voltage (C-V) measurements and deep level transient spectroscopy (DLTS). Two main electron traps have been revealed with activation energies at 0.16 eV and 0.52 eV from the conduction band. Inhomogeneous spatial distributions of the traps, obtained by DLTS profiling, indicate that they are agglomerated at the interrupted interface on a concentration level of (2-3) x 10{sup 15} cm{sup -3} at their maximum. Their behaviour is typical of acceptor-like traps when investigating by C-V profiling as a function of temperature. Based on a comparison made with electron traps in MBE-GaAs as well as with the traps in InAs/GaAs quantum dot/quantum well (QD/QW) structures, we conclude they are the well-known EL10 and EL4 defects, respectively, and their concentrations are growth condition dependent. They may be point defect-impurity complexes. Their presence may cause interpretation and application problems of the low-dimensional InAs/GaAs structures.

  18. Dislocation-related trap levels in nitride-based light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Venturi, Giulia; Castaldini, Antonio; Cavallini, Anna [Department of Physics and Astronomy, University of Bologna, Viale Berti Pichat 6/2, Bologna 40127 (Italy); Meneghini, Matteo; Zanoni, Enrico [Department of Information Engineering, University of Padova, via Gradenigo 6/B, Padova 35131 (Italy); Zhu, Dandan; Humphreys, Colin [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom)

    2014-05-26

    Deep level transient spectroscopy was performed on InGaN/GaN multiple quantum well light emitting diodes (LEDs) in order to determine the effect of the dislocation density on the deep intragap electronic levels. The LEDs were grown by metalorganic vapor phase epitaxy on GaN templates with a high dislocation density of 8 × 10{sup 9} cm{sup −2} and a low dislocation density of 3 × 10{sup 8} cm{sup −2}. Three trapping levels for electrons were revealed, named A, A1, and B, with energies E{sub A} ≈ 0.04 eV, E{sub A1} ≈ 0.13 eV, and E{sub B} ≈ 0.54 eV, respectively. The trapping level A has a much higher concentration in the LEDs grown on the template with a high density of dislocations. The logarithmic dependence of the peak amplitude on the bias pulse width for traps A and A1 identifies the defects responsible for these traps as associated with linearly arranged defects. We conclude that traps A and A1 are dislocation-related intragap energy levels.

  19. Dislocation-related trap levels in nitride-based light emitting diodes

    International Nuclear Information System (INIS)

    Venturi, Giulia; Castaldini, Antonio; Cavallini, Anna; Meneghini, Matteo; Zanoni, Enrico; Zhu, Dandan; Humphreys, Colin

    2014-01-01

    Deep level transient spectroscopy was performed on InGaN/GaN multiple quantum well light emitting diodes (LEDs) in order to determine the effect of the dislocation density on the deep intragap electronic levels. The LEDs were grown by metalorganic vapor phase epitaxy on GaN templates with a high dislocation density of 8 × 10 9 cm −2 and a low dislocation density of 3 × 10 8 cm −2 . Three trapping levels for electrons were revealed, named A, A1, and B, with energies E A  ≈ 0.04 eV, E A1  ≈ 0.13 eV, and E B  ≈ 0.54 eV, respectively. The trapping level A has a much higher concentration in the LEDs grown on the template with a high density of dislocations. The logarithmic dependence of the peak amplitude on the bias pulse width for traps A and A1 identifies the defects responsible for these traps as associated with linearly arranged defects. We conclude that traps A and A1 are dislocation-related intragap energy levels.

  20. Iron-chelating agents never suppress Fenton reaction but participate in quenching spin-trapped radicals

    International Nuclear Information System (INIS)

    Li Linxiang; Abe, Yoshihiro; Kanagawa, Kiyotada; Shoji, Tomoko; Mashino, Tadahiko; Mochizuki, Masataka; Tanaka, Miho; Miyata, Naoki

    2007-01-01

    Hydroxyl radical formation by Fenton reaction in the presence of an iron-chelating agent such as EDTA was traced by two different assay methods; an electron spin resonance (ESR) spin-trapping method with 5,5-dimethyl-1-pyrroline N-oxide (DMPO), and high Performance liquid chromatography (HPLC)-fluorescence detection with terephthalic acid (TPA), a fluorescent probe for hydroxyl radicals. From the ESR spin-trapping measurement, it was observed that EDTA seemed to suppress hydroxyl radical formation with the increase of its concentration. On the other hand, hydroxyl radical formation by Fenton reaction was not affected by EDTA monitored by HPLC assay. Similar inconsistent effects of other iron-chelating agents such as nitrylotriacetic acid (NTA), diethylenetriamine penta acetic acid (DTPA), oxalate and citrate were also observed. On the addition of EDTA solution to the reaction mixture 10 min after the Fenton reaction started, when hydroxyl radical formation should have almost ceased but the ESR signal of DMPO-OH radicals could be detected, it was observed that the DMPO-OH· signal disappeared rapidly. With the simultaneous addition of Fe(II) solution and EDTA after the Fenton reaction ceased, the DMPO-OH· signal disappeared more rapidly. The results indicated that these chelating agents should enhance the quenching of [DMPO-OH]· radicals by Fe(II), but they did not suppress Fenton reaction by forming chelates with iron ions

  1. Trapping of superoxido cobalt and peroxido dicobalt species formed reversibly from CoII and O2.

    Science.gov (United States)

    Corona, Teresa; Padamati, Sandeep K; Acuña-Parés, Ferran; Duboc, Carole; Browne, Wesley R; Company, Anna

    2017-08-22

    The formation and spectroscopic characterization of a superoxido cobalt(iii) and a peroxido dicobalt(iii) species formed in the temperature dependent reversible reaction of a cobalt(ii) precursor with O 2 is described. The electronic nature of each species is explored in their reactivity with organic substrates.

  2. Light effect in photoionization of traps in GaN MESFETs

    Directory of Open Access Journals (Sweden)

    H. Arabshahi

    2009-09-01

    Full Text Available Trapping of hot electron behavior by trap centers located in buffer layer of a wurtzite phase GaN MESFET has been simulated using an ensemble Monte Carlo simulation. The results of the simulation show that the trap centers are responsible for current collapse in GaN MESFET at low temperatures. These electrical traps degrade the performance of the device at low temperature. On the opposite, a light-induced increase in the trap-limited drain current, results from the photoionization of trapped carriers and their return to the channel under the influence of the built in electric field associated with the trapped charge distribution. The simulated device geometries and doping are matched to the nominal parameters described for the experimental structures as closely as possible, and the predicted drain current and other electrical characteristics for the simulated device including trapping center effects show close agreement with the available experimental data.

  3. Fueling profile sensitivities of trapped particle mode transport to TNS

    International Nuclear Information System (INIS)

    Mense, A.T.; Attenberger, S.E.; Houlberg, W.A.

    1977-01-01

    A key factor in the plasma thermal behavior is the anticipated existence of dissipative trapped particle modes. A possible scheme for controlling the strength of these modes was found. The scheme involves varying the cold fueling profile. A one dimensional multifluid transport code was used to simulate plasma behavior. A multiregime model for particle and energy transport was incorporated based on pseudoclassical, trapped electron, and trapped ion regimes used elsewhere in simulation of large tokamaks. Fueling profiles peaked toward the plasma edge may provide a means for reducing density-gradient-driven trapped particle modes, thus reducing diffusion and conduction losses

  4. Pioneer 10/11 data analysis of the trapped radiation experiment

    Science.gov (United States)

    Fillius, W.

    1982-01-01

    The data handling operations and the database produced by the Trapped Radiation Experiment on the NASA Pioneer 10 and 11 spacecraft are outlined. In situ measurements of trapped radiation at both Jupiter and Saturn, the extension of cosmic ray observations to the outer heliosphere, the presence of Jovian electrons in interplanetary space, analyses of the interaction between planetary satellites and the trapped radiation that engulfs them, and further investigations of the radiation enviroments of both planets are reported.

  5. First results on the GOL-3-II facility

    International Nuclear Information System (INIS)

    Agafonov, M.A.; Arzhannikov, A.V.; Astrelin, V.T.

    1996-01-01

    The first experiments on injection of 8-s, 200-kJ GOL-3-II relativistic electron beam into a plasma are reported. The possibility of a macroscopically stable beam transport through a plasma column 12 m long under the conditions of the developed plasma microturbulence is demonstrated. As a result of collective beam-plasma interaction the effective heating of a dense plasma (∼ 1015 cm -3 ) is observed. According to the data from Thomson scattering the plasma electrons are heated up to the temperature of ∼ 1 keV, the beam energy loss reaching 25-30 %. Putting the facility into operation opens up prospects to carry out the experiments with a dense and hot plasma in a multimirror trap. (J.U.). 4 figs., 10 refs

  6. Temperature dependence of positron trapping by vacancies, loops and voids in molybdenum

    International Nuclear Information System (INIS)

    Bentzon, M.D.; Linderoth, S.; Petersen, K.

    1985-01-01

    The temperature dependence of positron trapping by defects in molybdenum has been studied. By resolving positron lifetime spectra into three components, it has been possible to distinguish the temperature dependence of positron trapping into loops and voids. The results show that the positron trapping rate into voids depends linearly on temperature. The temperature dependence of positron trapping by loops can be interpreted as positrons being trapped by jogs, directly or via the dislocation line. The temperature dependence of positrons trapped by loops is argued mainly to be due to the trapping at the dislocation line, and not to detrapping. The observed temperature dependence of positron annihilation parameters in an electron irradiated sample (below stage III), is explained by competitive positron trapping in interstitial loops at low temperatures

  7. Electron spin resonance and electron spin echo modulation studies of Cu(II) ions in the aluminosilicate chabazite: A comparison of Cu(II) cation location and adsorbate interaction with isostructural silicoaluminophosphate-34

    International Nuclear Information System (INIS)

    Zamadics, M.; Kevan, L.

    1992-01-01

    This study focuses on Cu(II) ions exchanged in the aluminosilicate zeolite chabazite. The various Cu(II) species formed after dehydration, rehydration, and exposure to adsorbates are characterized by electron spin resonance and electron spin echo modulation spectroscopies. These results are interpreted in terms of Cu(II) ion location and adsorbate interaction. The results of this study are compared to the results found earlier for SAPO-34, chabazite's structural analog from the silicoaluminophosphate group. In a hydrated sample of chabazite the Cu(II) ions are found to be in a near octahedral environment coordinated to three nonequivalent water molecules and three framework oxygens. The most probable location of the Cu(II) ion in a hydrated sample is above the plane of the six-membered ring slightly displaced into the ellipsoidal cavity. A somewhat similar location and coordination is found for Cu(II) ions in H-SAPO-34. A feature common to both CuH-chabazite and CuH-SAPO-34 is the generation of two distinct Cu(II) species upon dehydration. It is found that Cu(II) cations in chabazite interact with the various adsorbate molecules in a similar manner as Cu(II) cation in H-chabazite and three molecules of ethanol and three propanol molecules. Only the Cu(II) ions located in the hexagonal rings after dehydration were found to complex with ethylene. The differences observed in the interaction of the Cu(II) in with water, propanol, and ehtylene between SAPO-34 and chabazite can be related to the differing cation densities of these two materials. 32 refs., 7 figs., 21 tabs

  8. Characterization of trapped charges distribution in terms of mirror plot curve.

    Science.gov (United States)

    Al-Obaidi, Hassan N; Mahdi, Ali S; Khaleel, Imad H

    2018-01-01

    Accumulation of charges (electrons) at the specimen surface in scanning electron microscope (SEM) lead to generate an electrostatic potential. By using the method of image charges, this potential is defined in the chamber's space of such apparatus. The deduced formula is expressed in terms a general volumetric distribution which proposed to be an infinitesimal spherical extension. With aid of a binomial theorem the defined potential is expanded to a multipolar form. Then resultant formula is adopted to modify a novel mirror plot equation so as to detect the real distribution of trapped charges. Simulation results reveal that trapped charges may take a various sort of arrangement such as monopole, quadruple and octuple. But existence of any of these arrangements alone may never be take place, rather are some a formations of a mix of them. Influence of each type of these profiles depends on the distance between the incident electron and surface of a sample. Result also shows that trapped charge's amount of trapped charges can refer to a threshold for failing of point charge approximation. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Barrier controlled carrier trapping of extended defects in CdZnTe detector

    International Nuclear Information System (INIS)

    Guo, Rongrong; Jie, Wanqi; Xu, Yadong; Yu, Hui; Zha, Gangqiang; Wang, Tao; Ren, Jie

    2015-01-01

    Transient current techniques using alpha particle source were utilized to study the influence of extended defects on the electron drift time and the detector performance of CdZnTe crystals. Different from the case of trapping through isolated point defect, a barrier controlled trapping model was used to explain the mechanism of carrier trapping at the extended defects. The effect of extended defects on the photoconductance was studied by laser beam induced transient current (LBIC) measurement. The results demonstrate that the Schottky-type depletion space charge region is induced at the vicinity of the extended defects, which further distorts the internal electric field distribution and affects the carrier trajectory in CdZnTe crystals. The relationship between the electron drift time and detector performance has been established. - Highlights: • The barrier controlled trapping model was developed around extended defects. • Electron mobility and E-field distribution were distorted by space charge depletion region. • Extended defects act as a recombination-activated region. • The relationships between extended defects and detector performance were established

  10. Thermal and hydraulic analyses of the System 81 cold traps

    Energy Technology Data Exchange (ETDEWEB)

    Kim, K.

    1977-06-15

    Thermal and hydraulic analyses of the System 81 Type I and II cold traps were completed except for thermal transients analysis. Results are evaluated, discussed, and reported. Analytical models were developed to determine the physical dimensions of the cold traps and to predict the performance. The FFTF cold trap crystallizer performances were simulated using the thermal model. This simulation shows that the analytical model developed predicts reasonably conservative temperatures. Pressure drop and sodium residence time calculations indicate that the present design will meet the requirements specified in the E-Specification. Steady state temperature data for the critical regions were generated to assess the magnitude of the thermal stress.

  11. Reductive trapping of [(OC){sub 5}W-W(CO){sub 5}]{sup 2-} in a mixed-valent Sm{sup II/III} calix[4]pyrrolide sandwich

    Energy Technology Data Exchange (ETDEWEB)

    Deacon, Glen B.; Guo, Zhifang [School of Chemistry, Monash University, VIC (Australia); Junk, Peter C.; Wang, Jun [College of Science and Engineering, James Cook University, Townsville, QLD (Australia)

    2017-07-10

    Reduction of tungsten hexacarbonyl by the divalent samarium(II) complex [Sm{sub 2}(N{sub 4}Et{sub 8})(thf){sub 4}] ((N{sub 4}Et{sub 8}){sup 4-}=meso-octaethylcalix[4]pyrrolide) in toluene at ambient temperature gave the remarkable heteronuclear mixed-valent samarium(II/III)/tungsten complex [{(thf)_2Sm"I"I(N_4Et_8)Sm"I"I"I(thf)}{sub 2}{(μ-OC)_2W_2(CO)_8}], which features the trapping of a rare [W{sub 2}(CO){sub 10}]{sup 2-} anion with an unsupported W-W bond. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Measurements and characterization of a hole trap in neutron-irradiated silicon

    International Nuclear Information System (INIS)

    Avset, B.S.

    1996-04-01

    The report describes measurements on a hole trap in neutron irradiated silicon diodes made one high resistivity phosphorus doped floatzone silicon. The hole trap was detected by Deep Level Transient Spectroscopy. This measurement gave a trap activation energy of 0.475 MeV. Other measurements showed that the trap has very small capture cross sections for both holes and electrons (10 -18 to 10 -20 cm 2 ) and that the hole capture cross section is temperature dependent. The energy level position of the trap has been estimated to be between 0.25 and 0.29 eV from the valence band. 25 refs., 21 figs., 4 tabs

  13. High temperature annealing of minority carrier traps in irradiated MOCVD n(+)p InP solar cell junctions

    Science.gov (United States)

    Messenger, S. R.; Walters, R. J.; Summers, G. P.

    1993-01-01

    Deep level transient spectroscopy was used to monitor thermal annealing of trapping centers in electron irradiated n(+)p InP junctions grown by metalorganic chemical vapor deposition, at temperatures ranging from 500 up to 650K. Special emphasis is given to the behavior of the minority carrier (electron) traps EA (0.24 eV), EC (0.12 eV), and ED (0.31 eV) which have received considerably less attention than the majority carrier (hole) traps H3, H4, and H5, although this work does extend the annealing behavior of the hole traps to higher temperatures than previously reported. It is found that H5 begins to anneal above 500K and is completely removed by 630K. The electron traps begin to anneal above 540K and are reduced to about half intensity by 630K. Although they each have slightly different annealing temperatures, EA, EC, and ED are all removed by 650K. A new hole trap called H3'(0.33 eV) grows as the other traps anneal and is the only trap remaining at 650K. This annealing behavior is much different than that reported for diffused junctions.

  14. Properties of ion temperature gradient and trapped electron modes in tokamak plasmas with inverted density profiles

    Science.gov (United States)

    Du, Huarong; Jhang, Hogun; Hahm, T. S.; Dong, J. Q.; Wang, Z. X.

    2017-12-01

    We perform a numerical study of linear stability of the ion temperature gradient (ITG) mode and the trapped electron mode (TEM) in tokamak plasmas with inverted density profiles. A local gyrokinetic integral equation is applied for this study. From comprehensive parametric scans, we obtain stability diagrams for ITG modes and TEMs in terms of density and temperature gradient scale lengths. The results show that, for the inverted density profile, there exists a normalized threshold temperature gradient above which the ITG mode and the TEM are either separately or simultaneously unstable. The instability threshold of the TEM for the inverted density profile is substantially different from that for normal and flat density profiles. In addition, deviations are found on the ITG threshold from an early analytic theory in sheared slab geometry with the adiabatic electron response [T. S. Hahm and W. M. Tang, Phys. Fluids B 1, 1185 (1989)]. A possible implication of this work on particle transport in pellet fueled tokamak plasmas is discussed.

  15. One electron oxidation of Ni(II)-iminodiacetate by carbonate radical

    International Nuclear Information System (INIS)

    Mandal, P.C.; Bardhan, D.K.; Bhattacharyya, S.N.

    1995-01-01

    Reactions of carbonate radical (CO 3 - ), generated by photolysis or by radiolysis of a carbonate solution with nickel(II)-iminodiacetate (Ni(II)IDA) were studied at pH 10.5 and ionic strength (I)=0.2 mol x dm -3 . The stable product arising from the ligand degradation in the complex is mainly glyoxalic acid. Time-resolved spectroscopy and transient kinetics were studied using flash photolysis. From the kinetic data it was suggested that the carbonate radical initially reacts with Ni(III)IDA with a rate constant (2.4.±0.4) x 10 6 dm 3 x mol -1 x s -1 to form a Ni(II)IDA species which, however, undergoes a first-order transformation (k=2.7 x 10 2 x s -1 ) to give a radical intermediate of the type Ni(II)RNHCHCO - 2 ) which rapidly forms an adduct containing a Ni-C bond. This adduct decays very slowly to give rise to glyoxalic acid. From a consideration of equilibrium between Ni(II)IDA and Ni(III)IDA, the one electron reduction potential for the Ni(III)IDA/Ni(II)IDA couple was determined to be 1.467 V. (author) 30 refs.; 5 figs

  16. Mechanisms of electron transfer from structrual Fe(II) in reduced nontronite to oxygen for production of hydroxyl radicals

    Science.gov (United States)

    Yuan, Songhu; Liu, Xixiang; Liao, Wenjuan; Zhang, Peng; Wang, Xiaoming; Tong, Man

    2018-02-01

    Production of hydroxyl radicals (radOH) has been recently revealed upon oxygenation of sediments in redox-dynamic subsurface environments. In particular, Fe(II)-bearing clay minerals are the major sediment components contributing to radOH production upon oxygenation, and the produced radOH can oxidize contaminants and inactivate bacteria. Whereas, the mechanisms of radOH production from oxygenation of Fe(II)-bearing clay minerals remain elusive. The objectives of this study were to identify the structural variation of Fe(II) entities during the oxidation of Fe(II)-bearing clay minerals by O2, and to unravel the mechanisms of electron transfer within the mineral structure and from mineral to O2 for radOH production. Nontronite (NAu-2, 23% Fe) which was chemically reduced to 54.5% Fe(II) in total Fe was used as a model Fe(II)-bearing clay mineral. Production of radOH and oxidation of Fe(II) were measured during the oxidation of reduced NAu-2 by O2. A wide spectrum of spectroscopic techniques, including Fourier transform infrared spectroscopy (FTIR), Fe K-edge X-ray absorption spectroscopy (XAS), Mössbauer spectra, and X-ray photoelectron spectroscopy (XPS), were employed to explore the structural variation of Fe(II) entities in NAu-2 and the electron transfer within NAu-2 and from NAu-2 to O2. For 180 min oxidation of 1 g/L reduced NAu-2, a biphasic radOH production was observed, being quick within the initial 15 min and slow afterwards. Production of radOH correlates well with oxidation of Fe(II) in the reduced NAu-2. Within the initial 15 min, trioctahedral Fe(II)-Fe(II)-Fe(II) entities and edge Fe(II) in the reduced NAu-2 were preferentially and quickly oxidized, and electrons from the interior Fe(II)-Fe(II)-Fe(II) entities were most likely ejected from the basal siloxane plane to O2. Meanwhile, trioctahedral Fe(II)-Fe(II)-Fe(II) entities were mainly transformed to dioctahedral Fe(II)-Fe(II) entities. When the time of oxygenation was longer than 15 min

  17. Life spans of planktonic foraminifers: New sight through sediment traps

    Digital Repository Service at National Institute of Oceanography (India)

    Nigam, R.; Saraswat, R.; Mazumder, A.

    ), indicated by black arrows are remarkably present for all three trap locations. (Modified after Curry et l.t 1992). 2002; Eguchi, Ujiie, Kawahata and Taira 2003), (ii) all the traps can not stop functioning simultaneously and that for the same time... estimates of the life spans of planktonic foraminifera based on extrapolation of lab culture observations. According to Be et al (1981), an inverse relationship exists between feeding frequency and survival time, and that planktonic foraminifers under...

  18. Effects of keV electron irradiation on the avalanche-electron generation rates of three donors on oxidized silicon

    International Nuclear Information System (INIS)

    Sah, C.; Sun, J.Y.; Tzou, J.J.

    1983-01-01

    After keV electron beam irradiation of oxidized silicon, the avalanche-electron-injection generation rates and densities of the bulk compensating donor, the interface states, and the turnaround trap all increase. Heating at 200 0 C can anneal out these three donor-like traps, however, it cannot restore the generation rates back to their original and lower pre-keV electron irradiation values. The experimental results also indicate that all three traps may be related to the same mobile impurity species whose bonds are loosened by the keV electrons and then broken or released by the avalanche injected electrons

  19. Transitions to improved core electron heat confinement in JT-II plasmas

    International Nuclear Information System (INIS)

    Estrada, T.; Medina, F.; Ascasibar, E.; Balbin, R.; Castejon, F.; Hidalgo, C.; Lopez-Bruna, D.; Petrov, S.

    2008-01-01

    Transitions to improved core electron heat confinement are triggered by low order rational magnetic surfaces in TJ-II ECH plasmas. Transitions triggered by the rational surface n=4/m=2 show an increase in the ion temperature synchronized with the increase in the electron temperature. SXR measurements demonstrate that, under certain circumstances, the rational surface positioned inside the plasma core region precedes and provides a trigger for the transition. (author)

  20. Oxide, interface, and border traps in thermal, N2O, and N2O-nitrided oxides

    International Nuclear Information System (INIS)

    Fleetwood, D.M.; Saks, N.S.

    1996-01-01

    We have combined thermally stimulated-current (TSC) and capacitance endash voltage (C endash V) measurements to estimate oxide, interface, and effective border trap densities in 6 endash 23 nm thermal, N 2 O, and N 2 O-nitrided oxides exposed to ionizing radiation or high-field electron injection. Defect densities depend strongly on oxide processing, but radiation exposure and moderate high-field stress lead to similar trapped hole peak thermal energy distributions (between ∼1.7 and ∼2.0 eV) for all processes. This suggests that similar defects dominate the oxide charge trapping properties in these devices. Radiation-induced hole and interface trap generation efficiencies (0.1%endash 1%) in the best N 2 O and N 2 O-nitrided oxides are comparable to the best radiation hardened oxides in the literature. After ∼10 Mrad(SiO 2 ) x-ray irradiation or ∼10 mC/cm 2 constant current Fowler endash Nordheim injection, effective border trap densities as high as ∼5x10 11 cm -2 are inferred from C endash V hysteresis. These measurements suggest irradiation and high-field stress cause similar border trap energy distributions. In each case, even higher densities of compensating trapped electrons in the oxides (up to 2x10 12 cm -2 ) are inferred from combined TSC and C endash V measurements. These trapped electrons prevent conventional C endash V methods from providing accurate estimates of the total oxide trap charge density in many irradiation or high-field stress studies. Fewer compensating electrons per trapped hole (∼26%±5%) are found for irradiation of N 2 O and N 2 O-nitrided oxides than for thermal oxides (∼46%±7%). (Abstract Truncated)

  1. Physisorption of an electron in deep surface potentials off a dielectric surface

    International Nuclear Information System (INIS)

    Heinisch, R. L.; Bronold, F. X.; Fehske, H.

    2011-01-01

    We study phonon-mediated adsorption and desorption of an electron at dielectric surfaces with deep polarization-induced surface potentials where multiphonon transitions are responsible for electron energy relaxation. Focusing on multiphonon processes due to the nonlinearity of the coupling between the external electron and the acoustic bulk phonon triggering the transitions between surface states, we calculate electron desorption times for graphite, MgO, CaO, Al 2 O 3 , and SiO 2 and electron sticking coefficients for Al 2 O 3 , CaO, and SiO 2 . To reveal the kinetic stages of electron physisorption, we moreover study the time evolution of the image-state occupancy and the energy-resolved desorption flux. Depending on the potential depth and the surface temperature, we identify two generic scenarios: (i) adsorption via trapping in shallow image states followed by relaxation to the lowest image state and desorption from that state via a cascade through the second strongly bound image state in not too deep potentials, and (ii) adsorption via trapping in shallow image states but followed by a relaxation bottleneck retarding the transition to the lowest image state and desorption from that state via a one-step process to the continuum in deep potentials.

  2. Characterization of Ni(II) complexes of Schiff bases of amino acids and (S)-N-(2-benzoylphenyl)-1-benzylpyrrolidine-2-carboxamide using ion trap and QqTOF electrospray ionization tandem mass spectrometry

    NARCIS (Netherlands)

    Jirasko, Robert; Holcapek, Michal; Kolarova, Lenka; Nadvornik, Milan; Popkov, Alexander

    This work demonstrates the application of electrospray ionization mass spectrometry (ESI-MS) using two different mass analyzers, ion trap and hybrid quadrupole time-of-flight (QqTOF) mass analyzer, for the structural characterization of Ni(II) complexes of Schiff bases of

  3. Some neutronic studies on flux-trap type moderator

    International Nuclear Information System (INIS)

    Kiyanagi, Y.; Watanabe, N.

    1991-01-01

    The neutronic performance of a flux-trap type moderator was studied by computer simulation in connection with the KENS-II target-moderator system. It was confirmed that this system can provide 1.3-1.4 times higher neutron intensity than a traditional wing-geometry moderator system. (author)

  4. Technology for On-Chip Qubit Control with Microfabricated Surface Ion Traps

    Energy Technology Data Exchange (ETDEWEB)

    Highstrete, Clark [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Quantum Information Sciences Dept.; Scott, Sean Michael [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). RF/Optoelectronics Dept.; Nordquist, Christopher D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). RF/Optoelectronics Dept.; Sterk, Jonathan David [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Photonic Microsystem Technologies Dept.; Maunz, Peter Lukas Wilhelm [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Photonic Microsystem Technologies Dept.; Tigges, Christopher P. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Photonic Microsystem Technologies Dept.; Blain, Matthew Glenn [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Photonic Microsystem Technologies Dept.; Heller, Edwin J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Microsystems Integration Dept.; Stevens, James E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). MESAFab Operations 2 Dept.

    2013-11-01

    Trapped atomic ions are a leading physical system for quantum information processing. However, scalability and operational fidelity remain limiting technical issues often associated with optical qubit control. One promising approach is to develop on-chip microwave electronic control of ion qubits based on the atomic hyperfine interaction. This project developed expertise and capabilities at Sandia toward on-chip electronic qubit control in a scalable architecture. The project developed a foundation of laboratory capabilities, including trapping the 171Yb+ hyperfine ion qubit and developing an experimental microwave coherent control capability. Additionally, the project investigated the integration of microwave device elements with surface ion traps utilizing Sandia’s state-of-the-art MEMS microfabrication processing. This effort culminated in a device design for a multi-purpose ion trap experimental platform for investigating on-chip microwave qubit control, laying the groundwork for further funded R&D to develop on-chip microwave qubit control in an architecture that is suitable to engineering development.

  5. Trapped Mode Study For A Rotatable Collimator Design For The LHC Upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Liling; Ng, Cho-Kuen; Smith, Jeffery Claiborne; Caspers, Fritz; /SLAC /CERN

    2009-06-23

    A rotatable collimator is proposed for the LHC phase II collimation upgrade. When the beam crosses the collimator, it will excite trapped modes that can contribute to the beam energy loss and power dissipation on the vacuum chamber wall. Transverse trapped modes can also generate transverse kicks on the beam and may thus affect the beam quality. In this paper, the parallel eigensolver code Omega3P is used to search for all the trapped modes below 2 GHz in two collimator designs, one with rectangular and the other with circular vacuum chamber. It is found that the longitudinal trapped modes in the circular vacuum chamber design may cause excessive heating. Adding ferrite tiles on the circular vacuum chamber wall can strongly damp these trapped modes. We will present and discuss the simulation results.

  6. Location of trapped charge in aluminum-implanted SiO2

    International Nuclear Information System (INIS)

    DiMaria, D.J.; Young, D.R.; Hunter, W.R.; Serrano, C.M.

    1978-01-01

    The position of the centroid of electrons trapped on sites resulting from aluminum implantation into SiO 2 is measured by using the photo I-V technique for energies from 15 to 40 keV, oxide thicknesses from 49 to 140 nm, and post-implant annealing temperature from 600 to 1050 0 C in N 2 for 30 min. The centroid of the trapped electrons is found to be identical to that of the implanted aluminum from SIMS measurements, regardless of annealing temperature from 600 to 1050 0 C, and located closer (by less than 9 nm) to the Al--SiO 2 interface than predicted from the Lindhard-Scharff-Schott (LSS) calculations of Gibbons, Johnson, and Mylroie. Comparison of centroids determined from photo I-V and SIMS measurements as a function of SiO 2 thickness also implies that the distributions of the ions and negative trapped charge are the same. The trapping behavior of these sites is discussed in the accompanying paper by Young et al

  7. Electron beam irradiation effect on GaN HEMT

    International Nuclear Information System (INIS)

    Lou Yinhong; Guo Hongxia; Zhang Keying; Wang Yuanming; Zhang Fengqi

    2011-01-01

    In this work, GaN HEMTs (High Electron Mobility Transistor) were irradiated by 0.8 and 1.2 MeV electron beams, and the irradiation effects were investigated. The results show that the device damage caused by 0.8 MeV electrons is more serious than that by 1.2 MeV electrons. Saturation drain current increase and threshold voltage negative shift are due to trapped positive charge from ionization in the AlGaN layer and N, Ga vacancy from non-ionizing energy loss in the GaN layer. Electron traps and trapped positive charges from non-ionizing in the AlGaN layer act as trap-assisted-tunneling centers that increase the gate leakage current.(authors)

  8. The effects of deep trap population on the thermoluminescence of Al{sub 2}O{sub 3}:C

    Energy Technology Data Exchange (ETDEWEB)

    Yukihara, E.G. E-mail: yukihara@thor.phy.okstate.edu; Whitley, V.H.; Polf, J.C.; Klein, D.M.; McKeever, S.W.S.; Akselrod, A.E.; Akselrod, M.S

    2003-12-01

    The influence of deep traps on the 450 K thermoluminescence (TL) peak of Al{sub 2}O{sub 3}:C is studied. Depending upon the sample and on the degree of deep trap filling, features such as the TL width, area and height can vary considerably. These effects are interpreted to be due to: (a) sensitivity changes introduced by competition mechanisms involving deep electron and hole traps, and (b) the multiple component nature of the 450 K TL peak. The influence of the deep traps on the TL was studied using different excitation sources (beta irradiation or UV illumination), and step annealing procedures. Optical absorption measurements were used to monitor the concentration of F- and F{sup +}-centers. The data lead to the suggestion that the competing deep traps which become unstable at {approx}800-875 K are hole traps, and that the competing deep traps which become unstable at {approx}1100-1200 K are electron traps. Both the dose response of the TL signal and the TL sensitivity are shown to be influenced by sensitization and desensitization processes caused by the filling of deep electron and hole traps, respectively. Changes in the TL peak at low doses were also shown to be connected to the degree of filling of deep traps, emphasizing the influence of deep trap concentration and dose history of each sample in determining the TL properties of the material. Implications of these results for the optically stimulated luminescence properties are also discussed.

  9. Photoreductive dissolution of iron oxides trapped in ice and its environmental implications.

    Science.gov (United States)

    Kim, Kitae; Choi, Wonyong; Hoffmann, Michael R; Yoon, Ho-Il; Park, Byong-Kwon

    2010-06-01

    The availability of iron has been thought to be a main limiting factor for the productivity of phytoplankton and related with the uptake of atmospheric CO(2) and algal blooms in fresh and sea waters. In this work, the formation of bioavailable iron (Fe(II)(aq)) from the dissolution of iron oxide particles was investigated in the ice phase under both UV and visible light irradiation. The photoreductive dissolution of iron oxides proceeded slowly in aqueous solution (pH 3.5) but was significantly accelerated in polycrystalline ice, subsequently releasing more bioavailable ferrous iron upon thawing. The enhanced photogeneration of Fe(II)(aq) in ice was confirmed regardless of the type of iron oxides [hematite, maghemite (gamma-Fe(2)O(3)), goethite (alpha-FeOOH)] and the kind of electron donors. The ice-enhanced dissolution of iron oxides was also observed under visible light irradiation, although the dissolution rate was much slower compared with the case of UV radiation. The iron oxide particles and organic electron donors (if any) in ice are concentrated and aggregated in the liquid-like grain boundary region (freeze concentration effect) where protons are also highly concentrated (lower pH). The enhanced photodissolution of iron oxides should occur in this confined boundary region. We hypothesized that electron hopping through the interconnected grain boundaries of iron oxide particles facilitates the separation of photoinduced charge pairs. The outdoor experiments carried out under ambient solar radiation of Ny-Alesund (Svalbard, 78 degrees 55'N) also showed that the generation of dissolved Fe(II)(aq) via photoreductive dissolution is enhanced when iron oxides are trapped in ice. Our results imply that the ice(snow)-covered surfaces and ice-cloud particles containing iron-rich mineral dusts in the polar and cold environments provide a source of bioavailable iron when they thaw.

  10. Kinetics of light sum collection in solid dosemeters with several trapping levels

    International Nuclear Information System (INIS)

    Vlasov, V.K.; Tarasov, M.Yu.

    1983-01-01

    On the basis of a stochastic model of filling up the electron-hole capture centres following irradiation, the kinetics of light sum accumulation in crystallophosphors with any number of capture levels has been considered. Using as an example a crystallophosphor with two hole- and two electron capture centres, solution of equations for the kinetics of light sum accumulation in solid dosemeters is presented. It is shown that in the presence of two competing capture centres the filling-up of one of the traps is always described by the function with a bent and superlinear section, whereas the filling-up of the competing trap is described by the function without a bent. The dose-effect functional relationship for competing traps does not depend either on the energetic depth of the trap or absolute values of capture micro cross-sections, but depends solely on relative values of macro- and micro cross-sections for competing traps. The theoretical model has been checked when studying radiothermoluminescence of synthetic quartz. The experimental results are shown to agree well with the model suggested

  11. Transport through dissipative trapped electron mode and toroidal ion temperature gradient mode in TEXTOR

    International Nuclear Information System (INIS)

    Rogister, A.; Hasselberg, G.; Waelbroeck, F.; Weiland, J.

    1987-12-01

    A self-consistent transport code is used to evaluate how plasma confinement in tokamaks is influenced by the microturbulent fields which are excited by the dissipative trapped electron (DTE) instability. As shown previously, the saturation theory on which the code is based has been developed from first principles. The toroidal coupling resulting from the ion magnetic drifts is neglected; arguments are presented to justify this approximation. The numerical results reproduce well the neo-Alcator scaling law observed experimentally - e.g. in TEXTOR - in non detached ohmic discharges, the confinement degradation which results when auxiliary heating is applied, as well as a large number of other experimental observations. We also assess the possible impact of the toroidal ion temperature gradient mode on energy confinement by estimating the ion thermal flux with the help of the mixing length approximation. (orig./GG)

  12. A comprehensive spectral theory of zonal-mode dynamics in trapped electron mode turbulence

    International Nuclear Information System (INIS)

    Terry, P.W.; Gatto, R.; Baver, D.A.; Fernandez, E.

    2005-01-01

    A comprehensive, self-consistent theory for spectral dynamics in trapped electron mode (TEM) turbulence offers critical new understanding and insights into zonal-mode physics. This theory shows that 1) zonal mode structure, anisotropy, excitation, and temporal behavior arise at and from the interface of nonlinear advection and linear wave properties; 2) waves induce a marked spectral energy-transfer anisotropy that preferentially drives zonal modes relative to non zonal modes; 3) triplet correlations involving density (as opposed to those involving only flow) mediate the dominant energy transfer at long wavelengths; 4) energy transfer becomes inverse in the presence of wave anisotropy, where otherwise it is forward; 5) zonal-mode excitation is accompanied by excitation of a spectrum of damped eigenmodes, making zonal modes nonlinearly damped; and 6) the combination of anisotropic transfer to zonal modes and their nonlinear damping make this the dominant saturation mechanism for TEM turbulence. This accounts for the reduction of turbulence level by zonal modes, not zonal-flow ExB shearing. (author)

  13. High-field penning-malmberg trap: confinement properties and use in positron accumulation

    Energy Technology Data Exchange (ETDEWEB)

    Hartley, J.H.

    1997-09-01

    This dissertation reports on the development of the 60 kG cryogenic positron trap at Lawrence Livermore National Laboratory, and compares the trap`s confinement properties with other nonneutral plasma devices. The device is designed for the accumulation of up to 2{times}10{sup 9} positrons from a linear-accelerator source. This positron plasma could then be used in Bhabha scattering experiments. Initial efforts at time-of-flight accumulation of positrons from the accelerator show rapid ({approximately}100 ms) deconfinement, inconsistent with the long electron lifetimes. Several possible deconfinement mechanisms have been explored, including annihilation on residual gas, injection heating, rf noise from the accelerator, magnet field curvature, and stray fields. Detailed studies of electron confinement demonstrate that the empirical scaling law used to design the trap cannot be extrapolated into the parameter regime of this device. Several possible methods for overcoming these limitations are presented.

  14. A quasi-electrostatic trap for neutral atoms

    International Nuclear Information System (INIS)

    Engler, H.

    2000-01-01

    This thesis reports on the realization of a ''quasi-electrostatic trap'' (QUEST) for neutral atoms. Cesium ( 133 Cs) and Lithium ( 7 Li) atoms are stored, which represents for the first time a mixture of different species in an optical dipole trap. The trap is formed by the focused Gaussian beam of a 30 W cw CO 2 -laser. For a beam waist of 108 μm the resulting trap depth is κ B x 118 μK for Cesium and κ B x 48 μK for Lithium. We transfer up to 2 x 10 6 Cesium and 10 5 Lithium atoms from a magneto-optical trap into the QUEST. When simultaneously transferred, the atom number currently is reduced by roughly a factor of 10. Since photon scattering from the trapping light can be neglected, the QUEST represents an almost perfect conservative trapping potential. Atoms in the QUEST populate the electronic ground state sublevels. Arbitrary sublevels can be addressed via optical pumping. Due to the very low background gas pressure of 2 x 10 -11 mbar storage times of several minutes are realized. Evaporative cooling of Cesium is observed. In addition, laser cooling is applied to the trapped Cesium sample, which reduces the temperature from 25 μK to a value below 7 μK. If prepared in the upper hyper-fine ground state sublevel, spin changing collisions are observed not only within one single species, but also between the two different species. The corresponding relaxation rates are quantitatively analyzed. (orig.)

  15. Interfacial dynamic surface traps of lead sulfide (PbS) nanocrystals: test-platform for interfacial charge carrier traps at the organic/inorganic functional interface

    Science.gov (United States)

    Kim, Youngjun; Ko, Hyungduk; Park, Byoungnam

    2018-04-01

    Nanocrystal (NC) size and ligand dependent dynamic trap formation of lead sulfide (PbS) NCs in contact with an organic semiconductor were investigated using a pentacene/PbS field effect transistor (FET). We used a bilayer pentacene/PbS FET to extract information of the surface traps of PbS NCs at the pentacene/PbS interface through the field effect-induced charge carrier density measurement in the threshold and subthreshold regions. PbS size and ligand dependent trap properties were elucidated by the time domain and threshold voltage measurements in which threshold voltage shift occurs by carrier charging and discharging in the trap states of PbS NCs. The observed threshold voltage shift is interpreted in context of electron trapping through dynamic trap formation associated with PbS NCs. To the best of our knowledge, this is the first demonstration of the presence of interfacial dynamic trap density of PbS NC in contact with an organic semiconductor (pentacene). We found that the dynamic trap density of the PbS NC is size dependent and the carrier residence time in the specific trap sites is more sensitive to NC size variation than to NC ligand exchange. The probing method presented in the study offers a means to investigate the interfacial surface traps at the organic-inorganic hetero-junction, otherwise understanding of the buried surface traps at the functional interface would be elusive.

  16. Emission Spectroscopy as a Probe into Photoinduced Intramolecular Electron Transfer in Polyazine Bridged Ru(II,Rh(III Supramolecular Complexes

    Directory of Open Access Journals (Sweden)

    Karen J. Brewer

    2010-08-01

    Full Text Available Steady-state and time-resolved emission spectroscopy are valuable tools to probe photochemical processes of metal-ligand, coordination complexes. Ru(II polyazine light absorbers are efficient light harvesters absorbing in the UV and visible with emissive 3MLCT excited states known to undergo excited state energy and electron transfer. Changes in emission intensity, energy or band-shape, as well as excited state lifetime, provide insight into excited state dynamics. Photophysical processes such as intramolecular electron transfer between electron donor and electron acceptor sub-units may be investigated using these methods. This review investigates the use of steady-state and time-resolved emission spectroscopy to measure excited state intramolecular electron transfer in polyazine bridged Ru(II,Rh(III supramolecular complexes. Intramolecular electron transfer in these systems provides for conversion of the emissive 3MLCT (metal-to-ligand charge transfer excited state to a non-emissive, but potentially photoreactive, 3MMCT (metal-to-metal charge transfer excited state. The details of the photophysics of Ru(II,Rh(III and Ru(II,Rh(III,Ru(II systems as probed by steady-state and time-resolved emission spectroscopy will be highlighted.

  17. CIGS Solar Cells for Space Applications: Numerical Simulation of the Effect of Traps Created by High-Energy Electron and Proton Irradiation on the Performance of Solar Cells

    Science.gov (United States)

    Dabbabi, Samar; Ben Nasr, Tarek; Turki Kamoun, Najoua

    2018-02-01

    Numerical simulation is carried out using the Silvaco ATLAS software to predict the effect of 1-MeV electron and 4-MeV proton irradiation on the performance of a Cu(In, Ga)Se2 (CIGS) solar cell that operates under the air mass zero spectrum (AM0). As a consequence of irradiation, two types of traps are induced including the donor- and acceptor-type traps. Only one of them (the donor-type trap) is found responsible for the degradation of the open-circuit voltage (V OC), fill factor (FF) and efficiency (η), while the short circuit current (J SC) remains essentially unaffected. The modelling simulation validity is verified by comparison with the experimental data. This article shows that CIGS solar cells are suited for space applications.

  18. Electron-impact excitation of Zn II

    International Nuclear Information System (INIS)

    Msezane, A.Z.; Henry, R.J.W.

    1982-01-01

    Collision strengths are calculated for excitation of Zn II from the 4s ground state to excited states 4p, 3d 9 4s 2 , 5s, and 4d in a five-state close-coupling approximation for the electron-impact energy range 15 5 3d 10 4s 2 in a two-state close-coupling approximation for the same energy range. Accurate target functions are used in the expansion. Very good agreement with measurements of absolute emission cross sections of Rogers et al. is obtained for energy region 15< E<100 eV, when cascade contributions are included. Poorer agreement is obtained with experiment for excitation of the 5s state, owing to sensitivities in the close-coupling approximation

  19. dE/dx electronics for MARK II experiment at SLAC

    International Nuclear Information System (INIS)

    Bernstein, D.; Boyarski, A.; Coupal, D.; Feldman, G.; Paffrath, L.

    1985-10-01

    This paper describes a 100 MHz pulse digitizer for dE/dx measurements on the MARK II drift chamber at SLAC. The electronics provides the read-out of the detector's 5832 sense based on a 16-channel FASTBUS module. The basic element of the module is the TRW 6-bit Flash-ADC

  20. Survey of trapped low energy electrons near the inner boundary of the inner radiation zone from the OSO-7

    International Nuclear Information System (INIS)

    Neighbors, J.E.; Clark, G.W.

    1974-01-01

    Data from the MIT x-ray experiment on the OSO-7 satellite were used to delineate the regions in B-L and geographic spaces where trapped radiation was encountered. The results pertain specifically to electrons with energies in a range of 10 keV centered on 55 keV which were encountered in an orbit between altitudes of 330 and 570 km and latitudes of +-33.3 0 . A typical pitch angle distribution is fitted by a Gaussian with a FWHM of 28 degrees. (U.S.)

  1. Preliminary Tests of a Paul ion Trap as an Ion Source

    Science.gov (United States)

    Sadat Kiai, S. M.; Zirak, A. R.; Elahi, M.; Adlparvar, S.; Mortazavi, B. N.; Safarien, A.; Farhangi, S.; Sheibani, S.; Alhooie, S.; Khalaj, M. M. A.; Dabirzadeh, A. A.; Ruzbehani, M.; Zahedi, F.

    2010-10-01

    The paper reports on the design and construction of a Paul ion trap as an ion source by using an impact electron ionization technique. Ions are produced in the trap and confined for the specific time which is then extracted and detected by a Faraday cup. Especial electronic configurations are employed between the end caps, ring electrodes, electron gun and a negative voltage for the detector. This configuration allows a constant low level of pure ion source between the pulsed confined ion sources. The present experimental results are based on the production and confinement of Argon ions with good stability and repeatability, but in principle, the technique can be used for various Argon like ions.

  2. Second harmonic electron cyclotron emission studies of Tokapole-II plasmas

    International Nuclear Information System (INIS)

    Sengstacke, M.A.

    1984-03-01

    The electron temperature is an important parameter in plasma physics. The intensity of electron cyclotron emission (ECE) is a function of the electron temperature. This function reduces to a direct proportionality for optically thick plasmas. Thus a study of ECE can help us understand various plasma properties. The principal diagnostic used is a radiometer consisting of a microwave superheterodyne receiver operating in the K band, (26.5,40) GHz, and fed by a three inch parabolic mirror with a spot size of about 4.4 cm. The entire microwave assembly can be rotated through 90 0 about the mirror axis to facilitate polarization measurements. A ray tracing analysis of Tokapole-II shows that refraction is significant for plasmas observed in this work

  3. Enhanced vaccine-induced CD8+ T cell responses to malaria antigen ME-TRAP by fusion to MHC class ii invariant chain.

    Directory of Open Access Journals (Sweden)

    Alexandra J Spencer

    Full Text Available The orthodox role of the invariant chain (CD74; Ii is in antigen presentation to CD4+ T cells, but enhanced CD8+ T cells responses have been reported after vaccination with vectored viral vaccines encoding a fusion of Ii to the antigen of interest. In this study we assessed whether fusion of the malarial antigen, ME-TRAP, to Ii could increase the vaccine-induced CD8+ T cell response. Following single or heterologous prime-boost vaccination of mice with a recombinant chimpanzee adenovirus vector, ChAd63, or recombinant modified vaccinia virus Ankara (MVA, higher frequencies of antigen-specific CD4+ and CD8+ T cells were observed, with the largest increases observed following a ChAd63-MVA heterologous prime-boost regimen. Studies in non-human primates confirmed the ability of Ii-fusion to augment the T cell response, where a 4-fold increase was maintained up to 11 weeks after the MVA boost. Of the numerous different approaches explored to increase vectored vaccine induced immunogenicity over the years, fusion to the invariant chain showed a consistent enhancement in CD8+ T cell responses across different animal species and may therefore find application in the development of vaccines against human malaria and other diseases where high levels of cell-mediated immunity are required.

  4. Tornado type closed magnetic trap for an ECR source

    CERN Document Server

    Abramova, K B; Voronin, A V; Zorin, V G

    1999-01-01

    We propose to use a Tornado type closed magnetic trap for creation of a source of mul-ticharged ions with plasma heating by microwave radiation. Plasma loss in closed traps is deter-mined by diffusion across the magnetic field, which increases substantially plasma confinement time as compared to the classical mirror trap [1]. We propose to extract ions with the aid of additional coils which partially destroy the closed structure of the magnetic lines in the trap, but don not influence the total confinement time. This allows for producing a controlled plasma flux that depends on the magnetic field of the additional coil. The Tornado trap also possesses merits such as an opportunity to produce high magnetic fields up to 3 T, which makes possible heating and confinement of plasma with a high density of electrons; plasma stability to magneto-hydrodynamic perturbations because the magnetic field structure corresponds to the "min B" configuration; and relatively low costs. All estimates and calculations were carrie...

  5. Measurement of the radiative cooling rates for high-ionization species of krypton using an electron beam ion trap

    International Nuclear Information System (INIS)

    Radtke, R.; Biedermann, C.; Fuchs, T.; Fussmann, G.; Beiersdorfer, P.

    2000-01-01

    We describe a measurement of the radiative cooling rate for krypton made at the Berlin electron beam ion trap (EBIT). The EBIT was tuned to a charge-state distribution approaching the ionization balance of a plasma at a temperature of about 5 keV. To determine the cooling rate, we made use of EBIT's capabilities to sample a wide range of electron-beam energies and distinguish between different radiation channels. We have measured the x-ray emission from bremsstrahlung, radiative recombination, dielectronic recombination, and line radiation following electron-impact excitation. The dominant contribution to the cooling rate is made by the n=3-2, n=4-2,... x rays of the L-shell spectra of krypton, which produce more than 75% of the total radiation loss. A difference with theoretical calculations is noted for the measured total cooling rate. The predicted values are lower by a factor of 1.5-2, depending on the theoretical model. For our measurement of the cooling rate, we estimate an uncertainty interval of 22-30 %. (c) 2000 The American Physical Society

  6. A Portable Source of Lattice-Trapped and Ultracold Strontium (PLUS), Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to demonstrate the portable source of lattice-trapped, ultracold strontium (PLUS) designed during Phase I. The device uses simplified and robust...

  7. The XRS microcalorimeter spectrometer at the Livermore Electron Beam Ion Trap

    Energy Technology Data Exchange (ETDEWEB)

    Porter, F S; Beiersdorfer, P; Boyce, K; Brown, G V; Chen, H; Gygax, J; Kahn, S M; Kelley, R; Kilbourne, C A; Magee, E; Thorn, D B

    2007-08-22

    NASA's X-ray Spectrometer (XRS) microcalorimeter instrument has been operating at the Electron Beam Ion Trap (EBIT) facility at Lawrence Livermore National Laboratory since July of 2000. The spectrometer is currently undergoing its third major upgrade to become an easy to use, extremely high performance instrument for a broad range of EBIT experiments. The spectrometer itself is broadband, capable of simultaneously operating from 0.1 to 12 keV and has been operated at up to 100 keV by manipulating its operating conditions. The spectral resolution closely follows the spaceflight version of the XRS, beginning at 10 eV FWHM at 6 keV in 2000, upgraded to 5.5 eV in 2003, and will hopefully be {approx}3.8 eV in the Fall of 2007. Here we review the operating principles of this unique instrument, the extraordinary science that has been performed at EBIT over the last 6 years, and prospects for future upgrades. Specifically we discuss upgrades to cover the high-energy band (to at least 100 keV) with a high quantum efficiency detector, and prospects for using a new superconducting detector to reach 0.8 eV resolution at 1 keV, and 2 eV at 6 keV with high counting rates.

  8. The drift-diffusion interpretation of the electron current within the organic semiconductor characterized by the bulk single energy trap level

    Science.gov (United States)

    Cvikl, B.

    2010-01-01

    The closed solution for the internal electric field and the total charge density derived in the drift-diffusion approximation for the model of a single layer organic semiconductor structure characterized by the bulk shallow single trap-charge energy level is presented. The solutions for two examples of electric field boundary conditions are tested on room temperature current density-voltage data of the electron conducting aluminum/tris(8-hydroxyquinoline aluminum/calcium structure [W. Brütting et al., Synth. Met. 122, 99 (2001)] for which jexp∝Va3.4, within the interval of bias 0.4 V≤Va≤7. In each case investigated the apparent electron mobility determined at given bias is distributed within a given, finite interval of values. The bias dependence of the logarithm of their lower limit, i.e., their minimum values, is found to be in each case, to a good approximation, proportional to the square root of the applied electric field. On account of the bias dependence as incorporated in the minimum value of the apparent electron mobility the spatial distribution of the organic bulk electric field as well as the total charge density turn out to be bias independent. The first case investigated is based on the boundary condition of zero electric field at the electron injection interface. It is shown that for minimum valued apparent mobilities, the strong but finite accumulation of electrons close to the anode is obtained, which characterize the inverted space charge limited current (SCLC) effect. The second example refers to the internal electric field allowing for self-adjustment of its boundary values. The total electron charge density is than found typically to be of U shape, which may, depending on the parameters, peak at both or at either Alq3 boundary. It is this example in which the proper SCLC effect is consequently predicted. In each of the above two cases, the calculations predict the minimum values of the electron apparent mobility, which substantially

  9. Spectra of W19 +-W32 + observed in the EUV region between 15 and 55 Å with an electron-beam ion trap

    Science.gov (United States)

    Sakaue, H. A.; Kato, D.; Yamamoto, N.; Nakamura, N.; Murakami, I.

    2015-07-01

    We present extreme ultraviolet spectra of highly charged tungsten ions (W19 +-W32 + ) in the wavelength range of 15 -55 Å obtained with a compact electron-beam ion trap (CoBIT) and a grazing-incidence spectrometer at the National Institute for Fusion Science. The electron energy dependence of the spectra was investigated for electron energies from 490 to 1320 eV . Identification of the observed lines was aided by collisional-radiative (CR) modeling of CoBIT plasma. Good quantitative agreement was obtained between the CR-modeling results and the experimental observations. The ion charge dependence of the 6 g -4 f ,5 g -4 f ,5 f -4 d ,5 p -4 d , and 4 f -4 d transition wavelengths were measured.

  10. On the thermoluminescent interactive multiple-trap system (IMTS) model: is it a simple model?

    International Nuclear Information System (INIS)

    Gil T, M. I.; Perez C, L.; Cruz Z, E.; Furetta, C.; Roman L, J.

    2016-10-01

    In the thermally stimulated luminescence phenomenon, named thermoluminescence (Tl), the electrons and holes generated by the radiation-matter interaction can be trapped by the metastable levels in the band gap of the solid. Following, the electron can be thermally releases into the conduction band and a radiatively recombination with hole close to the recombination center occurred and the glow curve is emitted. However, the complex mechanism of trapping and thermally releases occurred in the band gap of solid. Some models, such as; first, second and general-order kinetics, have been well established to explain the behaviour of the glow curves and their defects recombination mechanism. In this work, expressions for and Interactive Multiple-Trap System model (IMTS) was obtained assuming: a set of discrete electron traps (active traps At), another set of thermally disconnected trap (TDT) and a recombination center (Rc) too. A numerical analysis based on the Levenberg-Marquardt method in conjunction with an implicit Rosenbrock method was taken into account to simulate the glow curve. The numerical method was tested through synthetic Tl glow curves for a wide range of trap parameters. The activation energy and kinetics order were determined using values from the General Order Kinetics (GOK) model as entry data to IMTS model. This model was tested using the experimental glow curves obtained from Ce or Eu-doped MgF 2 (LiF) polycrystals samples. Results shown that the IMTS model can predict more accurately the behavior of the Tl glow curves that those obtained by the GOK modified by Rasheedy and by the Mixed Order Kinetics model. (Author)

  11. Insect Biometrics: Optoacoustic Signal Processing and Its Applications to Remote Monitoring of McPhail Type Traps.

    Science.gov (United States)

    Potamitis, Ilyas; Rigakis, Iraklis; Fysarakis, Konstantinos

    2015-01-01

    Monitoring traps are important components of integrated pest management applied against important fruit fly pests, including Bactrocera oleae (Gmelin) and Ceratitis capitata (Widemann), Diptera of the Tephritidae family, which effect a crop-loss/per year calculated in billions of euros worldwide. Pests can be controlled with ground pesticide sprays, the efficiency of which depends on knowing the time, location and extent of infestations as early as possible. Trap inspection is currently carried out manually, using the McPhail trap, and the mass spraying is decided based on a decision protocol. We introduce the term 'insect biometrics' in the context of entomology as a measure of a characteristic of the insect (in our case, the spectrum of its wingbeat) that allows us to identify its species and make devices to help face old enemies with modern means. We modify a McPhail type trap into becoming electronic by installing an array of photoreceptors coupled to an infrared emitter, guarding the entrance of the trap. The beating wings of insects flying in the trap intercept the light and the light fluctuation is turned to a recording. Custom-made electronics are developed that are placed as an external add-on kit, without altering the internal space of the trap. Counts from the trap are transmitted using a mobile communication network. This trap introduces a new automated remote-monitoring method different to audio and vision-based systems. We evaluate our trap in large number of insects in the laboratory by enclosing the electronic trap in insectary cages. Our experiments assess the potential of delivering reliable data that can be used to initialize reliably the spraying process at large scales but to also monitor the impact of the spraying process as it eliminates the time-lag between acquiring and delivering insect counts to a central agency.

  12. Modeling of radiation-induced charge trapping in MOS devices under ionizing irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Petukhov, M. A., E-mail: m.a.petukhov@gmail.com; Ryazanov, A. I. [National Research Center Kurchatov Institute (Russian Federation)

    2016-12-15

    The numerical model of the radiation-induced charge trapping process in the oxide layer of a MOS device under ionizing irradiation is developed; the model includes carrier transport, hole capture by traps in different states, recombination of free electrons and trapped holes, kinetics of hydrogen ions which can be accumulated in the material during transistor manufacture, and accumulation and charging of interface states. Modeling of n-channel MOSFET behavior under 1 MeV photon irradiation is performed. The obtained dose dependences of the threshold voltage shift and its contributions from trapped holes and interface states are in good agreement with experimental data.

  13. Theoretical modeling of the electronic structure and exchange interactions in a Cu(II)Pc one-dimensional chain

    Science.gov (United States)

    Wu, Wei; Fisher, A. J.; Harrison, N. M.

    2011-07-01

    We calculate the electronic structure and exchange interactions in a copper(II)phthalocyanine [Cu(II)Pc] crystal as a one-dimensional molecular chain using hybrid exchange density functional theory (DFT). In addition, the intermolecular exchange interactions are also calculated in a molecular dimer using Green’s function perturbation theory (GFPT) to illustrate the underlying physics. We find that the exchange interactions depend strongly on the stacking angle, but weakly on the sliding angle (defined in the text). The hybrid DFT calculations also provide an insight into the electronic structure of the Cu(II)Pc molecular chain and demonstrate that on-site electron correlations have a significant effect on the nature of the ground state, the band gap, and magnetic excitations. The exchange interactions predicted by our DFT calculations and GFPT calculations agree qualitatively with the recent experimental results on newly found η-Cu(II)Pc and the previous results for the α and β phases. This work provides a reliable theoretical basis for the further application of Cu(II)Pc to molecular spintronics and organic-based quantum information processing.

  14. Synthesis and formation process of SrSO{sub 4}:Sm{sup 3+} phosphors with hierarchical structures and its electron trapping luminescence properties

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Jiayue, E-mail: jiayue_sun@126.com; Sun, Guangchao; Xue, Bing; Cui, Dianpeng

    2013-10-15

    Highlights: •SrSO{sub 4} flower-like structures were synthesized by a aqueous solution route. •The as-prepared SrSO{sub 4} crystals have high crystalline. •The flower-like structures are composed of well aligned microtablets. •SrSO{sub 4} nuclei spontaneous attach by an “oriented attachment” process. •The SrSO{sub 4} crystals have excellent electron trapping luminescence properties. -- Abstract: Novel three-dimensional (3D) flower-like Strontium sulfate (SrSO{sub 4}) microstructures with hierarchical architecture were successfully fabricated by using Sr(NO{sub 3}){sub 2} react with Na{sub 2}SO{sub 4} aqueous solution under ambient conditions at room temperature. The SrSO{sub 4} flower-like microcrystals have a uniform diameter of about 10 μm, which are composed of numerous well-aligned single tablet-like SrSO{sub 4} crystals oriented radially to their center. The growth mechanism of the flower-like hierarchical celestine particles is discussed to obtain a better understanding on their formation process. XRD patterns confirm the single crystal phase of SrSO{sub 4}. In the photoluminescence property investigations of SrSO{sub 4}:Sm{sup 3+}, narrow bands observed are well identified with the electronic transition configurations of Sm{sup 3+}. The temperature-dependent photoluminescence spectra show that the temperature of maximum emission intensity is 25 °C. The thermal stability and electron trapping luminescence properties were also characterized.

  15. Experiments with highly charged ions up to bare U92+ on the electron beam ion trap

    International Nuclear Information System (INIS)

    Beiersdorfer, P.

    1994-07-01

    An overview is given of the current experimental effort to investigate the level structure of highly charged ions with the Livermore electron beam ion trap (EBIT) facility. The facility allows the production and study of virtually any ionization state of any element up to bare U 92+ . Precision spectroscopic measurements have been performed for a range of Δn = 0 and Δn = 1 transitions. Examples involving 3-4 and 2-3 as well as 3-3 and 2-2 transitions in uranium ions are discussed that illustrated some of the measurement and analysis techniques employed. The measurements have allowed tests of calculations of the the quantum electrodynamical contributions to the transitions energies at the 0.4% level in a regime where (Zα) ∼ 1

  16. Direct Experimental Evidence of Hole Trapping in Negative Bias Temperature Instability

    International Nuclear Information System (INIS)

    Ji Xiao-Li; Liao Yi-Ming; Yan Feng; Shi Yi; Zhang Guan; Guo Qiang

    2011-01-01

    Negative bias temperature instability (NBTI) in ultrathin-plasma-nitrided-oxide (PNO) based p-type metal-oxide-semiconductor field effect transistors (pMOSFETs) is investigated at temperatures ranging from 220K to 470K. It is found that the threshold voltage V T degradation below 290 K is dominated by the hole trapping process. Further studies unambiguously show that this process is unnecessarily related to nitrogen but the incorporation of nitrogen in the gate dielectric increases the probability of hole trapping in the NBTI process as it introduces extra trap states located in the upper half of the Si band gap. The possible hole trapping mechanism in NBTI stressed PNO pMOSFETs is suggested by taking account of oxygen and nitrogen related trap centers. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  17. Development of an in-trap spectroscopy setup at MLLTRAP for the future project MATS at FAIR

    Energy Technology Data Exchange (ETDEWEB)

    Thirolf, Peter; Gartzke, Eva; Habs, Dietrich; Krug, Kevin; Szerypo, Jerzy; Weber, Christine [Fak. fuer Physik, LMU - Muenchen (Germany); Kolhinen, Veli [Dept. of Physics, University of Jyvaeskylae (Sweden); Rodriguez, Daniel [FAMN, Universidad de Granada (Spain)

    2010-07-01

    One of the most important achievements of Penning trap technology is the possibility to manipulate ions of a defined q/m in order to provide purified ion species to dedicated experiments, such as high-precision mass measurements. This feature of ion manipulation and purification is used as well in nuclear decay-spectroscopy experiments with isobarically or even isomerically pure samples, typically installed after the trap. In a further approach, the Penning trap itself is equipped with detectors, since the stored ion clouds represent ideal sources, free from any background or scattering effects in the required backing materials. An in-trap spectroscopy setup is developed at MLLTRAP to be implemented in the future MATS facility at the low-energy branch of FAIR/GSI. Here, the main trapping electrodes will be replaced by position-sensitive Si-strip detectors and emitted electrons are efficiently guided towards detectors by the strong field of the trap magnet. Possible physics experiments are conversion-electron spectroscopy and in-trap {alpha}-decay experiments of heavy actinides. In this presentation, the design of the setup and possible physics applications are presented.

  18. Nonlinear Simulations of Trapped Electron Mode Turbulence in Low Magnetic Shear Stellarators

    Science.gov (United States)

    Faber, B. J.; Pueschel, M. J.; Terry, P. W.; Hegna, C. C.

    2017-10-01

    Optimized stellarators, like the Helically Symmetric eXperiment (HSX), often operate with small global magnetic shear to avoid low-order rational surfaces and magnetic islands. Nonlinear, flux-tube gyrokinetic simulations of density-gradient-driven Trapped Electron Mode (TEM) turbulence in HSX shows two distinct spectral fluctuation regions: long-wavelength slab-like TEMs localized by global magnetic shear that extend along field lines and short-wavelength TEMs localized by local magnetic shear to a single helical bad curvature region. The slab-like TEMs require computational domains significantly larger than one poloidal turn and are computationally expensive, making turbulent optimization studies challenging. A computationally more efficient, zero-average-magnetic-shear approximation is shown to sufficiently describe the relevant nonlinear physics and replicate finite-shear computations, and can be exploited in quasilinear models based on linear gyrokinetics as a feasible optimization tool. TEM quasilinear heat fluxes are computed with the zero-shear approximation and compared to experimentally-relevant nonlinear gyrokinetic TEM heat fluxes for HSX. Research supported by U.S. DoE Grants DE-FG02-99ER54546, DE-FG02-93ER54222 and DE-FG02-89ER53291.

  19. THz Electron Paramagnetic Resonance / THz Spectroscopy at BESSY II

    Directory of Open Access Journals (Sweden)

    Karsten Holldack

    2016-02-01

    Full Text Available The THz beamline at BESSY II employs high power broadband femto- to picosecond long THz pulses for magneto-optical THz and FIR studies. A newly designed set-up exploits the unique properties of ultrashort THz pulses generated by laser-energy modulation of electron bunches in the storage ring or alternatively from compressed electron bunches. Experiments from 0.15 to 5 THz (~ 5 – 150 cm-1 may be conducted at a user station equipped with a fully evacuated high resolution FTIR spectrometer (0.0063 cm-1, lHe cooled bolometer detectors, a THz TDS set-up and different sample environments, including a superconducting high field magnet (+11 T - 11T with variable temperature insert (1.5 K – 300 K, a sample cryostat and a THz attenuated total reflection chamber.  Main applications are Frequency Domain Fourier transform THz-Electron Paramagnetic Resonance (FD-FT THz-EPR, THz-FTIR spectroscopy and optical pump - THz probe time domain spectroscopy (TDS, with sub-ps time resolution.

  20. Generation of Nonlinear Electric Field Bursts in the Outer Radiation Belt through Electrons Trapping by Oblique Whistler Waves

    Science.gov (United States)

    Agapitov, Oleksiy; Drake, James; Mozer, Forrest

    2016-04-01

    Huge numbers of different nonlinear structures (double layers, electron holes, non-linear whistlers, etc. referred to as Time Domain Structures - TDS) have been observed by the electric field experiment on board the Van Allen Probes. A large part of the observed non-linear structures are associated with whistler waves and some of them can be directly driven by whistlers. The parameters favorable for the generation of TDS were studied experimentally as well as making use of 2-D particle-in-cell (PIC) simulations for the system with inhomogeneous magnetic field. It is shown that an outward propagating front of whistlers and hot electrons amplifies oblique whistlers which collapse into regions of intense parallel electric field with properties consistent with recent observations of TDS from the Van Allen Probe satellites. Oblique whistlers seed the parallel electric fields that are driven by the beams. The resulting parallel electric fields trap and heat the precipitating electrons. These electrons drive spikes of intense parallel electric field with characteristics similar to the TDSs seen in the VAP data. The decoupling of the whistler wave and the nonlinear electrostatic component is shown in PIC simulation in the inhomogeneous magnetic field system. These effects are observed by the Van Allen Probes in the radiation belts. The precipitating hot electrons propagate away from the source region in intense bunches rather than as a smooth flux.

  1. Feasibility Studies of the Two Filters Method in TJ-II for Electron Temperature Measurements in High Density Plasmas

    International Nuclear Information System (INIS)

    Baiao, D.; Medina, F.; Ochando, M.; Varandas, C.

    2009-01-01

    The TJ-II plasma soft X-ray emission was studied in order to establish an adequate setup for an electron temperature diagnostic suitable for high density, with spatial and temporal resolutions, based on the two-filters method. The preliminary experimental results reported were obtained with two diagnostics (an X-ray PHA based on a Ge detector and a tomography system) already installed in TJ-II stellarator. These results lead to the conclusion that the two-filters method was a suitable option for an electron temperature diagnostic for high-density plasmas in TJ-II. We present the design and fi rst results obtained with a prototype for the measurement of electron temperature in TJ-II plasmas heated with energetic neutral beams. This system consists in two AXUV20A detectors which measure the soft X-ray plasma emissivity trough beryllium filters of different thickness. From the two-filters technique it is possible to estimate the electron temperature. The analyses carried out allowed concluding which filter thicknesses are most suited for TJ-II plasmas, and enhanced the need of a computer code to simulate signals and plasma compositions. (Author) 7 refs.

  2. Feasibility Studies of the Two Filters Method in TJ-II for Electron Temperature Measurements in High Density Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Baiao, D.; Medina, F.; Ochando, M.; Varandas, C.

    2009-07-01

    The TJ-II plasma soft X-ray emission was studied in order to establish an adequate setup for an electron temperature diagnostic suitable for high density, with spatial and temporal resolutions, based on the two-filters method. The preliminary experimental results reported were obtained with two diagnostics (an X-ray PHA based on a Ge detector and a tomography system) already installed in TJ-II stellarator. These results lead to the conclusion that the two-filters method was a suitable option for an electron temperature diagnostic for high-density plasmas in TJ-II. We present the design and fi rst results obtained with a prototype for the measurement of electron temperature in TJ-II plasmas heated with energetic neutral beams. This system consists in two AXUV20A detectors which measure the soft X-ray plasma emissivity trough beryllium filters of different thickness. From the two-filters technique it is possible to estimate the electron temperature. The analyses carried out allowed concluding which filter thicknesses are most suited for TJ-II plasmas, and enhanced the need of a computer code to simulate signals and plasma compositions. (Author) 7 refs.

  3. Tarantula huwentoxin-IV inhibits neuronal sodium channels by binding to receptor site 4 and trapping the domain ii voltage sensor in the closed configuration.

    Science.gov (United States)

    Xiao, Yucheng; Bingham, Jon-Paul; Zhu, Weiguo; Moczydlowski, Edward; Liang, Songping; Cummins, Theodore R

    2008-10-03

    Peptide toxins with high affinity, divergent pharmacological functions, and isoform-specific selectivity are powerful tools for investigating the structure-function relationships of voltage-gated sodium channels (VGSCs). Although a number of interesting inhibitors have been reported from tarantula venoms, little is known about the mechanism for their interaction with VGSCs. We show that huwentoxin-IV (HWTX-IV), a 35-residue peptide from tarantula Ornithoctonus huwena venom, preferentially inhibits neuronal VGSC subtypes rNav1.2, rNav1.3, and hNav1.7 compared with muscle subtypes rNav1.4 and hNav1.5. Of the five VGSCs examined, hNav1.7 was most sensitive to HWTX-IV (IC(50) approximately 26 nM). Following application of 1 microm HWTX-IV, hNav1.7 currents could only be elicited with extreme depolarizations (>+100 mV). Recovery of hNav1.7 channels from HWTX-IV inhibition could be induced by extreme depolarizations or moderate depolarizations lasting several minutes. Site-directed mutagenesis analysis indicated that the toxin docked at neurotoxin receptor site 4 located at the extracellular S3-S4 linker of domain II. Mutations E818Q and D816N in hNav1.7 decreased toxin affinity for hNav1.7 by approximately 300-fold, whereas the reverse mutations in rNav1.4 (N655D/Q657E) and the corresponding mutations in hNav1.5 (R812D/S814E) greatly increased the sensitivity of the muscle VGSCs to HWTX-IV. Our data identify a novel mechanism for sodium channel inhibition by tarantula toxins involving binding to neurotoxin receptor site 4. In contrast to scorpion beta-toxins that trap the IIS4 voltage sensor in an outward configuration, we propose that HWTX-IV traps the voltage sensor of domain II in the inward, closed configuration.

  4. Modern power electronics in the Transrapid 06 II maglev train

    Energy Technology Data Exchange (ETDEWEB)

    Ruoss, W

    1987-04-01

    The Transrapid 06 II magler train comprises a number of power electronics components, e.g. modern, fast-switching power transistors of 100 kHz and with breaking capacities up to 100 kVA. The modular component design on the basis of established transistorized mountings and switching circuit components is described, as are the measures taken to assure high reliability and availability.

  5. Development of Diamond Vacuum Differential Amplifier for Harsh Environment Power Electronics, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — In this proposed Phase II, Scientic and Vanderbilt University will develop a novel vacuum field emission differential amplifier (VFEDA) using low electron affinity...

  6. One-Dimensional Rydberg Gas in a Magnetoelectric Trap

    International Nuclear Information System (INIS)

    Mayle, Michael; Hezel, Bernd; Lesanovsky, Igor; Schmelcher, Peter

    2007-01-01

    We study the quantum properties of Rydberg atoms in a magnetic Ioffe-Pritchard trap which is superimposed by a homogeneous electric field. Trapped Rydberg atoms can be created in long-lived electronic states exhibiting a permanent electric dipole moment of several hundred Debye. The resulting dipole-dipole interaction in conjunction with the radial confinement is demonstrated to give rise to an effectively one-dimensional ultracold Rydberg gas with a macroscopic interparticle distance. We derive analytical expressions for the electric dipole moment and the required linear density of Rydberg atoms

  7. ECRH scenarios with selective heating of trapped/passing electrons in the W7-X Stellarator

    Directory of Open Access Journals (Sweden)

    Marushchenko N.B.

    2015-01-01

    Full Text Available Using specific features of the magnetic equilibrium in the W7-X stellarator, the ECRH scenarios with combined X2 and X3 modes are discussed. The RF beams for operation with X2 and X3 modes need to be launched from low- and, via the remote steering launcher, high-field-side, respectivaly, in the different crosssections of the device where the maximum and minimum of the magnetic field located. The aim is to explore the possibility of selective heating of the different classes of electrons, passing and trapped, by changing direction of the beam for X3 or switching between the beams for X2 and X3 launched from the different ports. The numerical predictions for this kind of experiments in W7-X are performed by coupled transport and ray tracing codes

  8. Emerging science and technology of antimatter plasmas and trap-based beams

    International Nuclear Information System (INIS)

    Surko, C.M.; Greaves, R.G.

    2004-01-01

    Progress in the ability to accumulate and cool positrons and antiprotons is enabling new scientific and technological opportunities. The driver for this work is plasma physics research - developing new ways to create and manipulate antimatter plasmas. An overview is presented of recent results and near-term goals and challenges. In atomic physics, new experiments on the resonant capture of positrons by molecules provide the first direct evidence that positrons bind to 'ordinary' matter (i.e., atoms and molecules). The formation of low-energy antihydrogen was observed recently by injecting low-energy antiprotons into a cold positron plasma. This opens up a range of new scientific opportunities, including precision tests of fundamental symmetries such as invariance under charge conjugation, parity, and time reversal, and study of the chemistry of matter and antimatter. The first laboratory study of electron-positron plasmas has been conducted by passing an electron beam through a positron plasma. The next major step in these studies will be the simultaneous confinement of electron and positron plasmas. Although very challenging, such experiments would permit studies of the nonlinear behavior predicted for this unique and interesting plasma system. The use of trap-based positron beams to study transport in fusion plasmas and to characterize materials is reviewed. More challenging experiments are described, such as the creation of a Bose-condensed gas of positronium atoms. Finally, the future of positron trapping and beam formation is discussed, including the development of a novel multicell trap to increase by orders of magnitude the number of positrons trapped, portable antimatter traps, and cold antimatter beams (e.g., with energy spreads ≤1 meV) for precision studies of positron-matter interactions

  9. On the thermoluminescent interactive multiple-trap system (IMTS) model: is it a simple model?

    Energy Technology Data Exchange (ETDEWEB)

    Gil T, M. I.; Perez C, L. [UNAM, Facultad de Quimica, Ciudad Universitaria, 04510 Ciudad de Mexico (Mexico); Cruz Z, E.; Furetta, C.; Roman L, J., E-mail: ecruz@nucleares.unam.mx [UNAM, Instituto de Ciencias Nucleares, Ciudad Universitaria, 04510 Ciudad de Mexico (Mexico)

    2016-10-15

    In the thermally stimulated luminescence phenomenon, named thermoluminescence (Tl), the electrons and holes generated by the radiation-matter interaction can be trapped by the metastable levels in the band gap of the solid. Following, the electron can be thermally releases into the conduction band and a radiatively recombination with hole close to the recombination center occurred and the glow curve is emitted. However, the complex mechanism of trapping and thermally releases occurred in the band gap of solid. Some models, such as; first, second and general-order kinetics, have been well established to explain the behaviour of the glow curves and their defects recombination mechanism. In this work, expressions for and Interactive Multiple-Trap System model (IMTS) was obtained assuming: a set of discrete electron traps (active traps At), another set of thermally disconnected trap (TDT) and a recombination center (Rc) too. A numerical analysis based on the Levenberg-Marquardt method in conjunction with an implicit Rosenbrock method was taken into account to simulate the glow curve. The numerical method was tested through synthetic Tl glow curves for a wide range of trap parameters. The activation energy and kinetics order were determined using values from the General Order Kinetics (GOK) model as entry data to IMTS model. This model was tested using the experimental glow curves obtained from Ce or Eu-doped MgF{sub 2}(LiF) polycrystals samples. Results shown that the IMTS model can predict more accurately the behavior of the Tl glow curves that those obtained by the GOK modified by Rasheedy and by the Mixed Order Kinetics model. (Author)

  10. Charge-trapping effect of doped fluorescent dye on the electroluminescent processes and its performance in polymer light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Ye Tengling; Chen Zhenyu; Chen Jiangshan [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Graduate School of Chinese Academy of Sciences, Changchun 130022 (China); Ma Dongge, E-mail: mdg1014@ciac.jl.cn [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Graduate School of Chinese Academy of Sciences, Changchun 130022 (China)

    2010-11-15

    We have measured the temperature dependence of the steady-state current-voltage (I-V) characteristics and the transient electroluminescent (EL) characteristics in 4-(dicyanomethylene)-2-t-propyl-6-(1,1,7, 7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) doped polyfluorene devices to study the charge-trapping effect of DCJTB fluorescent dye on luminescence processes and on device performance. Physical and chemical analyses prove that DCJTB molecules serve both as electron and hole traps, and the charge-trapping effect is more sensitive against the electrons than the holes at the low dopant concentration. This intrinsic characteristic causes the electron to be injected into the emitting layer first and then trapped in the bulk, producing a strong effect on device performance.

  11. Population trapping: The mechanism for the lost resonance lines in Pm-like ions

    Science.gov (United States)

    Kato, Daiji; Sakaue, Hiroyuki A.; Murakami, Izumi; Nakamura, Nobuyuki

    2017-10-01

    We report a population kinetics study on line emissions of the Pm-like Bi22+ performed by using a collisional-radiative (CR) model. Population rates of excited levels are analyzed to explain the population trapping in the 4f135s2 state which causes the loss of the 5s - 5p resonance lines in emission spectra. Based on the present analysis, we elucidate why the population trapping is not facilitated for a meta-stable excited level of the Sm-like Bi21+. The emission line spectra are calculated for the Pm-like isoelectronic sequence from Au18+ through W13+ and compared with experimental measurements by electron-beam-ion-traps (EBITs). Structures of the spectra are similar for all of the cases except for calculated W13+ spectra. The calculated spectra are hardly reconciled with the measured W13+ spectrum using the compact electron-beam-ion-trap (CoBIT) [Phys. Rev. A 92 (2015) 022510].

  12. The trap states in lightly Mg-doped GaN grown by MOVPE on a freestanding GaN substrate

    Science.gov (United States)

    Narita, Tetsuo; Tokuda, Yutaka; Kogiso, Tatsuya; Tomita, Kazuyoshi; Kachi, Tetsu

    2018-04-01

    We investigated traps in lightly Mg-doped (2 × 1017 cm-3) p-GaN fabricated by metalorganic vapor phase epitaxy (MOVPE) on a freestanding GaN substrate and the subsequent post-growth annealing, using deep level transient spectroscopy. We identified four hole traps with energy levels of EV + 0.46, 0.88, 1.0, and 1.3 eV and one electron trap at EC - 0.57 eV in a p-type GaN layer uniformly doped with magnesium (Mg). The Arrhenius plot of hole traps with the highest concentration (˜3 × 1016 cm-3) located at EV + 0.88 eV corresponded to those of hole traps ascribed to carbon on nitrogen sites in n-type GaN samples grown by MOVPE. In fact, the range of the hole trap concentrations at EV + 0.88 eV was close to the carbon concentration detected by secondary ion mass spectroscopy. Moreover, the electron trap at EC - 0.57 eV was also identical to the dominant electron traps commonly observed in n-type GaN. Together, these results suggest that the trap states in the lightly Mg-doped GaN grown by MOVPE show a strong similarity to those in n-type GaN, which can be explained by the Fermi level close to the conduction band minimum in pristine MOVPE grown samples due to existing residual donors and Mg-hydrogen complexes.

  13. Developments in the theory of trapped particle pressure gradient driven turbulence in tokamaks and stellarators

    International Nuclear Information System (INIS)

    Diamond, P.H.; Biglari, H.; Gang, F.Y.

    1991-01-01

    Recent advances in the theory of trapped particle pressure gradient driven turbulence are summarized. A novel theory of trapped ion convective cell turbulence is presented. It is shown that non-linear transfer to small scales occurs, and that saturation levels are not unphysically large, as previously thought. As the virulent saturation mechanism of ion Compton scattering is shown to result in weak turbulence at higher frequencies, it is thus likely that trapped ion convective cells are the major agent of tokamak transport. Fluid like trapped electron modes at short wavelengths (k θ ρ i > 1) are shown to drive an inward particle pinch. The characteristics of convective cell turbulence in flat density discharges are described, as is the stability of dissipative trapped electron modes in stellarators, with flexible magnetic field structure. The role of cross-correlations in the dynamics of multifield models of drift wave turbulence is discussed. (author). 32 refs, 8 figs, 1 tab

  14. Mats and LaSpec: High-precision experiments using ion traps and lasers at Fair

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, D.; Lallena, A.M.; Blaum, K.; Bohm, C.; Cakirli, R.B.; Crespo Lopez-Urrutia, J.R.; Eliseev, S.; Ketelaer, J.; Kreim, M.S.; Kowalska, M.; Litvinov, Y.A.; Nagy, S.; Neidherr, D.; Repp, J.; Roux, C.; Schabinger, B.; Ullrich, J.; Nortershauser, W.; Eberhardt, K.; Geppert, C.; Kramer, J.; Krieger, A.; Sanchez, R.; Ahammed, M.; Das, P.; Ray, A.; Algora, A.; Rubio, B.; Tain, J.L.; Audi, G.; Lunney, D.; Naimi, S.; Aysto, J.; Jokinen, A.; Kolhinen, V.; Moore, I.; Beck, D.; Block, M.; Geissel, H.; Heinz, S.; Herfurth, F.; Litvinov, Y.A.; Minaya-Ramirez, E.; Plab, W.R.; Quint, W.; Scheidenberger, C.; Winkler, M.; Bender, M.; Billowes, J.; Campbell, P.; Flanagan, K.T.; Schwarz, S.; Bollen, G.; Ferrer, R.; George, S.; Kester, O.; Brodeur, M.; Brunner, T.; Delheij, P.; Dilling, J.; Ettenauer, S.; Lapierre, A.; Bushaw, B.A.; Cano-Ott, D.; Martinez, T.; Cortes, G.; Gomez-Hornillos, M.B.; Dax, A.; Herlert, A.; Yordanov, D.; De, A.; Dickel, T.; Geissel, H.; Jesch, C.; Kuhl, T.; Petrick, M.; PlaB, W.R.; Scheidenberger, C.; Garcia-Ramos, J.E.; Gartzke, E.; Habs, D.; Szerypo, J.; Thirolf, P.G.; Weber, C.; Gusev, Y.; Nesterenko, D.; Novikov, Y.N.; Popov, A.; Seliverstov, M.; Vasiliev, A.; Vorobjev, G.; Heenen, P.H.; Marx, G.; Schweikhard, L.; Ziegler, F.; Hobein, M.; Schuch, R.; Solders, A.; Suhonen, M.; Huber, G.; Wendt, K.; Huyse, M.; Koudriavtsev, I.; Neyens, G.; Van Duppen, P.; Le Blanc, F.; Matos, M.; Reinhard, P.G.; Schneider, D.

    2010-05-15

    Nuclear ground state properties including mass, charge radii, spins and moments can be determined by applying atomic physics techniques such as Penning-trap based mass spectrometry and laser spectroscopy. The MATS and LaSpec setups at the low-energy beamline at FAIR will allow us to extend the knowledge of these properties further into the region far from stability. With MATS (Precision Measurements of very short-lived nuclei using an Advanced Trapping System for highly-charged ions) at FAIR we aim to apply several techniques to very short-lived radionuclides: High-accuracy mass measurements, in-trap conversion electron and alpha spectroscopy, and trap-assisted spectroscopy. The experimental setup of MATS is a unique combination of an electron beam ion trap for charge breeding, ion traps for beam preparation, and a high-precision Penning trap system for mass measurements and decay studies. For the mass measurements, MATS offers both a high accuracy and a high sensitivity. A relative mass uncertainty of 10{sup -9} can be reached by employing highly-charged ions and a non-destructive Fourier-Transform Ion-Cyclotron-Resonance (FT-ICR) detection technique on single stored ions. Decay studies in ion traps will become possible with MATS. Laser spectroscopy of radioactive isotopes and isomers is an efficient and model-independent approach for the determination of nuclear ground and isomeric state properties. Hyperfine structures and isotope shifts in electronic transitions exhibit readily accessible information on the nuclear spin, magnetic dipole and electric quadrupole moments as well as root-mean-square charge radii. The accuracy of laser-spectroscopic-determined nuclear properties is very high while requirements concerning production rates are moderate. This Technical Design Report describes a new Penning trap mass spectrometry setup as well as a number of complementary experimental devices for laser spectroscopy. Since MATS and LaSpec require high-quality low

  15. Mats and LaSpec: High-precision experiments using ion traps and lasers at Fair

    International Nuclear Information System (INIS)

    Rodriguez, D.; Lallena, A.M.; Blaum, K.; Bohm, C.; Cakirli, R.B.; Crespo Lopez-Urrutia, J.R.; Eliseev, S.; Ketelaer, J.; Kreim, M.S.; Kowalska, M.; Litvinov, Y.A.; Nagy, S.; Neidherr, D.; Repp, J.; Roux, C.; Schabinger, B.; Ullrich, J.; Nortershauser, W.; Eberhardt, K.; Geppert, C.; Kramer, J.; Krieger, A.; Sanchez, R.; Ahammed, M.; Das, P.; Ray, A.; Algora, A.; Rubio, B.; Tain, J.L.; Audi, G.; Lunney, D.; Naimi, S.; Aysto, J.; Jokinen, A.; Kolhinen, V.; Moore, I.; Beck, D.; Block, M.; Geissel, H.; Heinz, S.; Herfurth, F.; Litvinov, Y.A.; Minaya-Ramirez, E.; Plab, W.R.; Quint, W.; Scheidenberger, C.; Winkler, M.; Bender, M.; Billowes, J.; Campbell, P.; Flanagan, K.T.; Schwarz, S.; Bollen, G.; Ferrer, R.; George, S.; Kester, O.; Brodeur, M.; Brunner, T.; Delheij, P.; Dilling, J.; Ettenauer, S.; Lapierre, A.; Bushaw, B.A.; Cano-Ott, D.; Martinez, T.; Cortes, G.; Gomez-Hornillos, M.B.; Dax, A.; Herlert, A.; Yordanov, D.; De, A.; Dickel, T.; Geissel, H.; Jesch, C.; Kuhl, T.; Petrick, M.; PlaB, W.R.; Scheidenberger, C.; Garcia-Ramos, J.E.; Gartzke, E.; Habs, D.; Szerypo, J.; Thirolf, P.G.; Weber, C.; Gusev, Y.; Nesterenko, D.; Novikov, Y.N.; Popov, A.; Seliverstov, M.; Vasiliev, A.; Vorobjev, G.; Heenen, P.H.; Marx, G.; Schweikhard, L.; Ziegler, F.; Hobein, M.; Schuch, R.; Solders, A.; Suhonen, M.; Huber, G.; Wendt, K.; Huyse, M.; Koudriavtsev, I.; Neyens, G.; Van Duppen, P.; Le Blanc, F.; Matos, M.; Reinhard, P.G.; Schneider, D.

    2010-01-01

    Nuclear ground state properties including mass, charge radii, spins and moments can be determined by applying atomic physics techniques such as Penning-trap based mass spectrometry and laser spectroscopy. The MATS and LaSpec setups at the low-energy beamline at FAIR will allow us to extend the knowledge of these properties further into the region far from stability. With MATS (Precision Measurements of very short-lived nuclei using an Advanced Trapping System for highly-charged ions) at FAIR we aim to apply several techniques to very short-lived radionuclides: High-accuracy mass measurements, in-trap conversion electron and alpha spectroscopy, and trap-assisted spectroscopy. The experimental setup of MATS is a unique combination of an electron beam ion trap for charge breeding, ion traps for beam preparation, and a high-precision Penning trap system for mass measurements and decay studies. For the mass measurements, MATS offers both a high accuracy and a high sensitivity. A relative mass uncertainty of 10 -9 can be reached by employing highly-charged ions and a non-destructive Fourier-Transform Ion-Cyclotron-Resonance (FT-ICR) detection technique on single stored ions. Decay studies in ion traps will become possible with MATS. Laser spectroscopy of radioactive isotopes and isomers is an efficient and model-independent approach for the determination of nuclear ground and isomeric state properties. Hyperfine structures and isotope shifts in electronic transitions exhibit readily accessible information on the nuclear spin, magnetic dipole and electric quadrupole moments as well as root-mean-square charge radii. The accuracy of laser-spectroscopic-determined nuclear properties is very high while requirements concerning production rates are moderate. This Technical Design Report describes a new Penning trap mass spectrometry setup as well as a number of complementary experimental devices for laser spectroscopy. Since MATS and LaSpec require high-quality low-energy beams

  16. Cold highly charged ions in a cryogenic Paul trap

    Energy Technology Data Exchange (ETDEWEB)

    Versolato, O. O., E-mail: oscar.versolato@mpi-hd.mpg.de; Schwarz, M.; Windberger, A.; Ullrich, J. [Max-Planck-Institut fuer Kernphysik (Germany); Schmidt, P. O. [Physikalisch-Technische Bundesanstalt (Germany); Drewsen, M. [University of Aarhus, Department of Physics and Astronomy (Denmark); Crespo Lopez-Urrutia, J. R. [Max-Planck-Institut fuer Kernphysik (Germany)

    2013-03-15

    Narrow optical transitions in highly charged ions (HCIs) are of particular interest for metrology and fundamental physics, exploiting the high sensitivity of HCIs to new physics. The highest sensitivity for a changing fine structure constant ever predicted for a stable atomic system is found in Ir{sup 17 + }. However, laser spectroscopy of HCIs is hindered by the large ({approx} 10{sup 6} K) temperatures at which they are produced and trapped. An unprecedented improvement in such laser spectroscopy can be obtained when HCIs are cooled down to the mK range in a linear Paul trap. We have developed a cryogenic linear Paul trap in which HCIs will be sympathetically cooled by {sup 9}Be{sup + } ions. Optimized optical access for laser light is provided while maintaining excellent UHV conditions. The Paul trap will be connected to an electron beam ion trap (EBIT) which is able to produce a wide range of HCIs. This EBIT will also provide the first experimental input needed for the determination of the transition energies in Ir{sup 17 + }, enabling further laser-spectroscopic investigations of this promising HCI.

  17. Hole traps in n-GaN detected by minority carrier transient spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Tokuda, Yutaka; Yamada, Yujiro; Shibata, Tatsunari; Yamaguchi, Shintaro [Department of Electrical and Electronics Engineering, Aichi Institute of Technology, Yakusa, 470-0392 Toyota (Japan); Ueda, Hiroyuki; Uesugi, Tsutomu; Kachi, Tetsu [Toyota Central R and D Laboratories, Inc., Nagakute, 480-1192 Aichi (Japan)

    2011-07-15

    Minority carrier transient spectroscopy (MCTS) has been applied for the detection of hole traps in n-GaN using Schottky diodes. MCTS using 355 nm light emitting diodes is performed under isothermal conditions in the temperature range 280 to 330 K for n-GaN grown by metalorganic chemical vapor deposition on sapphire. Isothermal MCTS spectra reveal the E{sub v} + 0.86 eV hole trap with the trap concentration of 1.1x10{sup 16} cm{sup -3}. The E{sub v} + 0.86 eV hole trap has the higher concentration as compared to electron traps observed by deep level transient spectroscopy. Thus, the isothermal MCTS around room temperature provides a convenient way to evaluate the dominant trap in n-GaN. It is suggested that the E{sub v} + 0.86 eV hole trap is associated with the V{sub Ga}-related defect or carbon-related defect. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  18. Deceleration and Trapping of Heavy Diatomic Molecules for Precision Measurements

    Science.gov (United States)

    Berg, J. E. Van Den; Turkesteen, S. N. Hoekman; Prinsen, E. B.; Hoekstra, S.

    2011-06-01

    We are setting up a novel type of Stark-decelerator optimized for the deceleration and trapping of heavy diatomic molecules. Aim of these experiments is to prepare a trapped sample of ultracold molecules for precision studies of fundamental symmetries. The decelerator uses ring-shaped electrodes to create a moving trapping potential, a prototype of which has been shown to work for CO molecules. Molecules can be decelerated and trapped in the weak-field seeking part of excited rotational states. The alkaline-earth monohalide molecules (currently we focus on the SrF molecule) are prime candidates for next generation parity violation and electron-EDM studies. We plan to combine the Stark deceleration with molecular laser cooling to create a trapped sample of molecules at a final temperature of ˜ 200 μK. A. Osterwalder, S. A. Meek, G. Hammer, H. Haak and G. Meijer Phys. Rev. A 81 (51401), 2010. T. A. Isaev, S. Hoekstra, R. Berger Phys. Rev. A 82 (52521), 2010

  19. Secondary Electron Yield Measurements and Groove Chambers Tests in the PEP-II Beam Line Straights Sections

    International Nuclear Information System (INIS)

    Pivi, M

    2008-01-01

    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 such as ILC and CLIC [1, 2]. In the Positron Low Energy Ring (LER) of the PEP-II accelerator, we have installed vacuum chambers with rectangular grooves in a straight magnetic-free section to test this promising possible electron cloud mitigation technique. We have also installed a special chamber to monitor the secondary electron yield of TiN and TiZrV (NEG) coating, Copper, Stainless Steel and Aluminum under the effect of electron and photon conditioning in situ in the beam line. In this paper, we describe the ongoing R and D effort to mitigate the electron cloud effect for the ILC damping ring, the latest results on in situ secondary electron yield conditioning and recent update on the groove tests in PEP-II

  20. Saturation of backward stimulated scattering of laser in kinetic regime: Wavefront bowing, trapped particle modulational instability, and trapped particle self-focusing of plasma waves

    International Nuclear Information System (INIS)

    Yin, L.; Albright, B. J.; Bowers, K. J.; Daughton, W.; Rose, H. A.

    2008-01-01

    Backward stimulated Raman and Brillouin scattering (SRS and SBS) of laser are examined in the kinetic regime using particle-in-cell simulations. The SRS reflectivity measured as a function of the laser intensity in a single hot spot from two-dimensional (2D) simulations shows a sharp onset at a threshold laser intensity and a saturated level at higher intensities, as obtained previously in Trident experiments [D. S. Montgomery et al., Phys. Plasmas 9, 2311 (2002)]. In these simulations, wavefront bowing of electron plasma waves (ion acoustic waves) due to the trapped particle nonlinear frequency shift, which increases with laser intensity, is observed in the SRS (SBS) regime for the first time. Self-focusing from trapped particle modulational instability (TPMI) [H. A. Rose, Phys. Plasmas 12, 12318 (2005)] is shown to occur in both two- and three-dimensional SRS simulations. The key physics underlying nonlinear saturation of SRS is identified as a combination of wavefront bowing, TPMI, and self-focusing of electron plasma waves. The wavefront bowing marks the beginning of SRS saturation and self-focusing alone is sufficient to terminate the SRS reflectivity, both effects resulting from cancellation of the source term for SRS and from greatly increased dissipation rate of the electron plasm waves. Ion acoustic wave bowing also contributes to the SBS saturation. Velocity diffusion by transverse modes and rapid loss of hot electrons in regions of small transverse extent formed from self-focusing lead to dissipation of the wave energy and an increase in the Landau damping rate in spite of strong electron trapping that reduces Landau damping initially. The ranges of wavelength and growth rate associated with transverse breakup of the electron-plasma wave are also examined in 2D speckle simulations as well as in 2D periodic systems from Bernstein-Greene-Kruskal equilibrium and are compared with theory predictions

  1. Dissociative electron attachment to methylhalides in 3-methylhexane glassy matrix

    International Nuclear Information System (INIS)

    Harada, K.; Irie, M.; Yoshida, H.

    1976-01-01

    Dissociative electron attachment reaction to CH 3 I, CH 3 Cl and CH 3 F in a 3-methylhexane glassy matrix was studied by determining the yield of trapped electrons and that of methyl radicals immediately after γ irradiation at 77 K as a function of the scavenger concentration. The efficiency of conversion from the trapped electrons to the methyl radicals was also studied by photobleaching the trapped electrons. The results obtained are (1) the dissociative electron attachment occurs to CH 3 F, for which the gas phase data indicate that the reaction is endothermic by 1.2 eV, during either the γ irradiation or the photobleaching, and (2) CH 3 F is relatively less efficient in scavenging photo-liberated electrons than in scavenging the electrons during the γ irradiation, whereas CH 3 I and CH 3 Cl are efficient scavengers for both the electrons. The dependence of the yields of the trapped electrons and the methyl radicals is discussed in terms of the electron-tunnelling mechanism and the epithermal electron-scavenging mechanism. (author)

  2. Full radius linear and nonlinear gyrokinetic simulations for tokamaks and stellarators: Zonal flows, applied E x B flows, trapped electrons and finite beta

    International Nuclear Information System (INIS)

    Villard, L.; Allfrey, S.J.; Bottino, A.

    2003-01-01

    The aim of this paper is to report on recent advances made on global gyrokinetic simulations of Ion Temperature Gradient modes (ITG) and other microinstabilities. The nonlinear development and saturation of ITG modes and the role of E x B zonal flows are studied with a global nonlinear δ f formulation that retains parallel nonlinearity and thus allows for a check of the energy conservation property as a means to verify the quality of the numerical simulation. Due to an optimised loading technique the conservation property is satisfied with an unprecedented quality well into the nonlinear stage. The zonal component of the perturbation establishes a quasi-steady state with regions of ITG suppression, strongly reduced radial energy flux and steepened effective temperature profile alternating with regions of higher ITG mode amplitudes, larger radial energy flux and flattened effective temperature profile. A semi-Lagrangian approach free of statistical noise is proposed as an alternative to the nonlinear δf formulation. An ASDEX-Upgrade experiment with an Internal Transport Barrier (ITB) is analysed with a global gyrokinetic code that includes trapped electron dynamics. The weakly destabilizing effect of trapped electron dynamics on ITG modes in an axisymmetric bumpy configuration modelling W7-X is shown in global linear simulations that retain the full electron dynamics. Finite β effects on microinstabilities are investigated with a linear global spectral electromagnetic gyrokinetic formulation. The radial global structure of electromagnetic modes shows a resonant behaviour with rational q values. (author)

  3. An electron-beam-heating model for the Gamble II rod pinch

    International Nuclear Information System (INIS)

    Mosher, David; Schumer, Joseph; Hinshelwood, David; Weber, Bruce; Stephanakis, Stavros; Swanekamp, Stephen; Young, Frank

    2002-01-01

    The rod-pinch diode concentrates electron deposition onto the tip of a high-atomic-number, mm-dia. anode rod to create an ultra-bright x-ray source for multi-MV radiography. Here, a technique is presented whereby line-spread functions acquired on-axis and at 90 deg. to the rod are used to determine the electron-deposition distribution. Results show that the smaller measured on-axis spot size for heated rods on Gamble II is due to pinching closer to the tapered tip. For a diode power of 6x1010 W, peak electron heating of 1x1014 W/cm 3 is calculated. MHD calculations of the e-beam-heated rod response agree with Schlieren measurements of plasma expansion

  4. States of the electron in hydrocarbon liquids

    International Nuclear Information System (INIS)

    Mozumder, A.

    2005-01-01

    Some features of the stationary and dynamic states of the electron are critically examined. Outline of a quantum mechanical description of electron thermalization is attempted qualitatively. The effects of both the mean free path and the reaction inefficiency on electron-ion geminate escape probability are investigated by a recently developed Metropolis method. The trapped state is interpreted in terms of Anderson localization, yielding an approximate number of molecules interacting with the trapped electron

  5. Trapping effects and acoustoelectric current saturation in ZnO single crystals

    DEFF Research Database (Denmark)

    Mosekilde, Erik

    1970-01-01

    Measurements of current-voltage characteristics for ZnO single crystals at temperatures between 77 and 640 °K are reported. Because of the buildup of an intense acoustic flux, a strong current saturation sets in when the trap-controlled electron drift velocity is equal to the velocity of sound....... The temperature dependence of the saturated current is discussed in terms of a trapping model which includes nonlinear trapping effects. Our results indicate the presence of a shallow-donor level with an ionization energy of 50 meV and a deep-donor level approximately 230 meV below the conduction-band edge...

  6. Electron internal transport barrier in the core of TJ-II ECH plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Estrada, T.; Hidalgo, C. [Laboratorio Nacional de Fusion por Confinamiento Magnetico. Asociacion EURATOM CIEMAT, Madrid (Spain); Dreval, N. [and others

    2003-07-01

    The influence of the magnetic topology on the formation of electron internal transport barriers (e-ITB) has been experimentally studied in the stellarator TJ-II. The formation of e-ITBs in electron cyclotron heated plasmas can be triggered by positioning a low order rational surface close to the plasma core region, while in configurations without any low order rational there are no indications of barrier formation within the available heating power. The e-ITB formation is characterized by an increase in the core electron temperature and plasma potential. Positive radial electric field increases in a factor of three in the plasma central region when the e-ITB forms. The results demonstrate that low order rational surfaces modify radial electric fields and electron heat transport. (orig.)

  7. Impact of nitrogen doping of niobium superconducting cavities on the sensitivity of surface resistance to trapped magnetic flux

    Science.gov (United States)

    Gonnella, Dan; Kaufman, John; Liepe, Matthias

    2016-02-01

    Future particle accelerators such as the SLAC "Linac Coherent Light Source-II" (LCLS-II) and the proposed Cornell Energy Recovery Linac require hundreds of superconducting radio-frequency (SRF) niobium cavities operating in continuous wave mode. In order to achieve economic feasibility of projects such as these, the cavities must achieve a very high intrinsic quality factor (Q0) to keep cryogenic losses within feasible limits. To reach these high Q0's in the case of LCLS-II, nitrogen-doping of niobium cavities has been selected as the cavity preparation technique. When dealing with Q0's greater than 1 × 1010, the effects of ambient magnetic field on Q0 become significant. Here, we show that the sensitivity to RF losses from trapped magnetic field in a cavity's walls is strongly dependent on the cavity preparation. Specifically, standard electropolished and 120 °C baked cavities show a sensitivity of residual resistance from trapped magnetic flux of ˜0.6 and ˜0.8 nΩ/mG trapped, respectively, while nitrogen-doped cavities show a higher sensitivity of residual resistance from trapped magnetic flux of ˜1 to 5 nΩ/mG trapped. We show that this difference in sensitivities is directly related to the mean free path of the RF surface layer of the niobium: shorter mean free paths lead to less sensitivity of residual resistance to trapped magnetic flux in the dirty limit (ℓ ≪ ξ0), while longer mean free paths lead to lower sensitivity of residual resistance to trapped magnetic flux in the clean limit (ℓ ≫ ξ0). These experimental results are also shown to have good agreement with recent theoretical predictions for pinned vortex lines oscillating in RF fields.

  8. Open trap with ambipolar mirrors

    International Nuclear Information System (INIS)

    Dimov, G.I.; Zakajdakov, V.V.; Kishinevskij, M.E.

    1977-01-01

    Results of numerical calculations on the behaviour of a thermonuclear plasma, allowing for α-particles in a trap with longitudinal confinement of the main ions by ambipolar electric fields are presented. This trap is formed by connecting two small-volume ''mirrortrons'' to an ordinary open trap. Into the extreme mirrortrons, approximately 1-MeV ions are introduced continuously by ionization of atomic beams on the plasma, and approximately 10-keV ions are similarly introduced into the main central region of the trap. By a suitable choice of injection currents, the plasma density established in the extreme mirrortrons is higher than in the central region. As a result of the quasi-neutrality condition, a longitudinal ambipolar field forming a potential well not only for electrons but also for the central ions is formed in the plasma. When the depth of the well for the central ions is much greater than their temperature, their life-time considerably exceeds the time of confinement by the magnetic mirrors. As a result, the plasma density is constant over the entire length of the central mirrortron, including the regions near the mirrors, and an ambipolar field is formed only in the extreme mirrortrons. The distribution of central ions and ambipolar potential in the extreme mirrortrons is uniquely determined by the density distribution of fast extreme ions. It is shown in the present study that an amplification coefficient Q as high as desired can, in principle, be reached in the trap under consideration, allowing for α-particles. However, this requires high magnetic fields in the mirrors and a sufficient length of the central mirrotron. It is shown that for moderate values of Q=3-8, it is desirable not to confine the central fast α-particles. To achieve a coefficient of Q=5, it is necessary to create fields of 250 kG in the mirrors, and the length of the trap must not be greater than 100 m. (author)

  9. Ultrafast electron dynamics at alkali/ice structures adsorbed on a metal surface

    International Nuclear Information System (INIS)

    Meyer, Michael

    2011-01-01

    mediated by tunneling through a potential barrier which is determined by the thickness of the ice layer. In the second system electron solvation at small alkali/water clusters directly prepared at the metal substrate is investigated. In these experiments the average number of water molecules in such a cluster can be controlled so that the population and stabilization dynamics of excess electrons can be investigated as a function of D 2 O coverage. Two main effects are observed: (i) the alkalis are solvated by a reorientation of the surrounding solvent molecules in the cluster; and (ii) above a critical number of water molecules per alkali excess electrons can localize at the clusters where they are energetically stabilized. This critical ratio depends on the type of alkali and is inversely proportional to the alkali-induced dipole moment. Finally, it is demonstrated that trapped electrons in crystalline ice adsorbed on Ru(001) can very efficiently mediate chemical reactions via dissociative electron attachment. When electronegative molecules like CFCl 3 are coadsorbed with crystalline ice a DEA process between trapped electrons and CFCl 3 molecules occurs, resulting in the formation of .CFCl 2 radicals and Cl - anions. These results suggest that photoexcited trapped electrons can play an important role in heterogeneous chemical processes on ice surfaces and could thus be relevant in the polar stratosphere chemistry.

  10. Effects of oxide traps, interface traps, and ''border traps'' on metal-oxide-semiconductor devices

    International Nuclear Information System (INIS)

    Fleetwood, D.M.; Winokur, P.S.; Reber, R.A. Jr.; Meisenheimer, T.L.; Schwank, J.R.; Shaneyfelt, M.R.; Riewe, L.C.

    1993-01-01

    We have identified several features of the 1/f noise and radiation response of metal-oxide-semiconductor (MOS) devices that are difficult to explain with standard defect models. To address this issue, and in response to ambiguities in the literature, we have developed a revised nomenclature for defects in MOS devices that clearly distinguishes the language used to describe the physical location of defects from that used to describe their electrical response. In this nomenclature, ''oxide traps'' are simply defects in the SiO 2 layer of the MOS structure, and ''interface traps'' are defects at the Si/SiO 2 interface. Nothing is presumed about how either type of defect communicates with the underlying Si. Electrically, ''fixed states'' are defined as trap levels that do not communicate with the Si on the time scale of the measurements, but ''switching states'' can exchange charge with the Si. Fixed states presumably are oxide traps in most types of measurements, but switching states can either be interface traps or near-interfacial oxide traps that can communicate with the Si, i.e., ''border traps'' [D. M. Fleetwood, IEEE Trans. Nucl. Sci. NS-39, 269 (1992)]. The effective density of border traps depends on the time scale and bias conditions of the measurements. We show the revised nomenclature can provide focus to discussions of the buildup and annealing of radiation-induced charge in non-radiation-hardened MOS transistors, and to changes in the 1/f noise of MOS devices through irradiation and elevated-temperature annealing

  11. Penning traps with unitary architecture for storage of highly charged ions.

    Science.gov (United States)

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

    2012-02-01

    Penning traps are made extremely compact by embedding rare-earth permanent magnets in the electrode structure. Axially-oriented NdFeB magnets are used in unitary architectures that couple the electric and magnetic components into an integrated structure. We have constructed a two-magnet Penning trap with radial access to enable the use of laser or atomic beams, as well as the collection of light. An experimental apparatus equipped with ion optics is installed at the NIST electron beam ion trap (EBIT) facility, constrained to fit within 1 meter at the end of a horizontal beamline for transporting highly charged ions. Highly charged ions of neon and argon, extracted with initial energies up to 4000 eV per unit charge, are captured and stored to study the confinement properties of a one-magnet trap and a two-magnet trap. Design considerations and some test results are discussed.

  12. Penning traps with unitary architecture for storage of highly charged ions

    International Nuclear Information System (INIS)

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

    2012-01-01

    Penning traps are made extremely compact by embedding rare-earth permanent magnets in the electrode structure. Axially-oriented NdFeB magnets are used in unitary architectures that couple the electric and magnetic components into an integrated structure. We have constructed a two-magnet Penning trap with radial access to enable the use of laser or atomic beams, as well as the collection of light. An experimental apparatus equipped with ion optics is installed at the NIST electron beam ion trap (EBIT) facility, constrained to fit within 1 meter at the end of a horizontal beamline for transporting highly charged ions. Highly charged ions of neon and argon, extracted with initial energies up to 4000 eV per unit charge, are captured and stored to study the confinement properties of a one-magnet trap and a two-magnet trap. Design considerations and some test results are discussed.

  13. From transistor to trapped-ion computers for quantum chemistry.

    Science.gov (United States)

    Yung, M-H; Casanova, J; Mezzacapo, A; McClean, J; Lamata, L; Aspuru-Guzik, A; Solano, E

    2014-01-07

    Over the last few decades, quantum chemistry has progressed through the development of computational methods based on modern digital computers. However, these methods can hardly fulfill the exponentially-growing resource requirements when applied to large quantum systems. As pointed out by Feynman, this restriction is intrinsic to all computational models based on classical physics. Recently, the rapid advancement of trapped-ion technologies has opened new possibilities for quantum control and quantum simulations. Here, we present an efficient toolkit that exploits both the internal and motional degrees of freedom of trapped ions for solving problems in quantum chemistry, including molecular electronic structure, molecular dynamics, and vibronic coupling. We focus on applications that go beyond the capacity of classical computers, but may be realizable on state-of-the-art trapped-ion systems. These results allow us to envision a new paradigm of quantum chemistry that shifts from the current transistor to a near-future trapped-ion-based technology.

  14. Plasmas in compact traps: From ion sources to multidisciplinary research

    Science.gov (United States)

    Mascali, D.; Musumarra, A.; Leone, F.; Galatà, A.; Romano, F. P.; Gammino, S.

    2017-09-01

    In linear (minimum-B) magneto-static traps dense and hot plasmas are heated by electromagnetic radiation in the GHz domain via the Electron Cyclotron Resonance (ECR). The values of plasma density, temperature and confinement times ( n_eτ_i>10^{13} cm ^{-3} s; T_e>10 keV) are similar to the ones of thermonuclear plasmas. The research in this field -devoted to heating and confinement optimization- has been supported by numerical modeling and advanced diagnostics, for probing the plasma especially in a non-invasive way. ECR-based systems are nowadays able to produce extremely intense (tens or hundreds of mA) beams of light ions (p, d, He), and relevant currents of heavier elements (C, O, N) up to heavy ions like Xe, Pb, U. Such beams can be extracted from the trap by a proper electrostatic system. The above-mentioned properties make these plasmas very attractive for interdisciplinary researches also, such as i) nuclear decays rates measurements in stellar-like conditions, ii) energy conversion studies, being exceptional sources of short-wavelength electromagnetic radiation (EUV, X-rays, hard X-rays and gammas, useful in material science and archaeometry), iii) environments allowing precise spectroscopical measurements as benchmarks for magnetized astrophysical plasmas. The talk will give an overview about the state-of-the-art in the field of intense ion sources, and some new perspectives for interdisciplinary research, with a special attention to the developments based at INFN-LNS.

  15. Triplet Transport to and Trapping by Acceptor End Groups on Conjugated Polyfluorene Chains

    Energy Technology Data Exchange (ETDEWEB)

    Sreearunothai, P.; Miller, J.; Estrada, A.; Asaoka, S.; Kowalczyk, M.; Jang, S.; Cook, A.R.; Preses, J.M.

    2011-08-31

    Triplet excited states created in polyfluorene (pF) molecules having average lengths up to 170 repeat units were transported to and captured by trap groups at the ends in less {approx}40 ns. Almost all of the triplets attached to the chains reached the trap groups, ruling out the presence of substantial numbers of defects that prevent transport. The transport yields a diffusion coefficient D of at least 3 x 10{sup -4} cm{sup 2} s{sup -1}, which is 30 times typical molecular diffusion and close to a value for triplet transport reported by Keller (J. Am. Chem. Soc.2011, 133, 11289-11298). The triplet states were created in solution by pulse radiolysis; time resolution was limited by the rate of attachment of triplets to the pF chains. Naphthylimide (NI) or anthraquinone (AQ) groups attached to the ends of the chains acted as traps for the triplets, although AQ would not have been expected to serve as a trap on the basis of triplet energies of the separate molecules. The depths of the NI and AQ triplet traps were determined by intermolecular triplet transfer equilibria and temperature dependence. The trap depths are shallow, just a few times thermal energy for both, so a small fraction of the triplets reside in the pF chains in equilibrium with the end-trapped triplets. Trapping by AQ appears to arise from charge transfer interactions between the pF chains and the electron-accepting AQ groups. Absorption bands of the end-trapped triplet states are similar in peak wavelength (760 nm) and shape to the 760 nm bands of triplets in the pF chains but have reduced intensities. When an electron donor, N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD), is added to the solution, it reacts with the end-trapped triplets to remove the 760 nm bands and to make the trapping irreversible. New bands created upon reaction with TMPD may be due to charge transfer states.

  16. Quantum dots use both LUMO and surface trap electrons in photoreduction process

    Energy Technology Data Exchange (ETDEWEB)

    Darżynkiewicz, Zbigniew M. [Centre of New Technologies, University of Warsaw, Banacha 2c, 02-097 Warsaw (Poland); Division of Biophysics, Faculty of Physics, University of Warsaw, Żwirki i Wigury 93, 02-089 Warsaw (Poland); Pędziwiatr, Marta [Institute of Physics PAS, al. Lotników 32/46, 02-668 Warsaw (Poland); Grzyb, Joanna, E-mail: jgrzyb@ifpan.edu.pl [Institute of Physics PAS, al. Lotników 32/46, 02-668 Warsaw (Poland)

    2017-03-15

    Here, we explore a mechanism of quantum dots related photoreduction of two redox-active proteins, cytochrome c and ferredoxin, by detailed analysis of fluorescence decay and reconstruction of time-resolved emission spectra (TRES). We used two types of cadmium telluride quantum dots, with diameters of 2.6 nm and 3.9 nm and maximum emissions at 550 nm and at 650 nm, respectively, which are known to be able to reduce proteins with different efficiencies. First, we observed that for a pure quantum dots solution, the fluorescence decay can be well fitted by three components. The average fluorescence lifetimes, as well as separate time constants, depend on the nanocrystal diameter. In the presence of proteins, fluorescence decay is faster and cytochrome c has a greater impact than ferredoxin. The TRES experiment showed that a fraction of the medium τ decay component is dominant in a pure quantum dot solution, with the maximum corresponding to the steady-state spectrum. The addition of ferredoxin does not change this pattern, while the presence of cytochrome c strongly promotes the shortest τ. Additionally, potassium iodide titration experiments were used to verify the origin of individual decay components. We propose that reduction occurs by electron transfer from both conductive band and surface trap states.

  17. Synthesis and spectroscopic studies of biologically active tetraazamacrocyclic complexes of Mn(II, Co(II, Ni(II, Pd(II and Pt(II

    Directory of Open Access Journals (Sweden)

    Monika Tyagi

    2014-01-01

    Full Text Available Complexes of Mn(II, Co(II, Ni(II, Pd(II and Pt(II were synthesized with the macrocyclic ligand, i.e., 2,3,9,10-tetraketo-1,4,8,11-tetraazacycoletradecane. The ligand was prepared by the [2 + 2] condensation of diethyloxalate and 1,3-diamino propane and characterized by elemental analysis, mass, IR and 1H NMR spectral studies. All the complexes were characterized by elemental analysis, molar conductance, magnetic susceptibility measurements, IR, electronic and electron paramagnetic resonance spectral studies. The molar conductance measurements of Mn(II, Co(II and Ni(II complexes in DMF correspond to non electrolyte nature, whereas Pd(II and Pt(II complexes are 1:2 electrolyte. On the basis of spectral studies an octahedral geometry has been assigned for Mn(II, Co(II and Ni(II complexes, whereas square planar geometry assigned for Pd(II and Pt(II. In vitro the ligand and its metal complexes were evaluated against plant pathogenic fungi (Fusarium odum, Aspergillus niger and Rhizoctonia bataticola and some compounds found to be more active as commercially available fungicide like Chlorothalonil.

  18. Charging effects of PET under electron beam irradiation in a SEM

    International Nuclear Information System (INIS)

    Jbara, O; Rondot, S; Hadjadj, A; Patat, J M; Fakhfakh, S; Belhaj, M

    2008-01-01

    This paper deals with charge trapping and charge transport of polyethylene terephthalate (PET) polymer subjected to electron irradiation in a scanning electron microscope (SEM). Measurement of displacement current and leakage current using an arrangement adapted to the SEM allows the amount of trapped charge during and after electron irradiation to be determined and the charge mechanisms regulation to be studied. These mechanisms involve several parameters related to the electronic injection, the characteristics of insulator and the effects of the trapped charge itself. The dynamic trapping properties of PET samples are investigated and the time constants of charging are evaluated for various conditions of irradiation. The determination of the trapping cross section for electrons is possible by using the trapping rate at the onset of irradiation. Many physical processes are involved in the charging and discharging mechanisms; among them surface conduction is outlined. Through the control of irradiation conditions, various types of surface discharging (flashover phenomenon) behaviour are also observed. The strength of the electric field initiating surface discharge is estimated.

  19. Observation of Deep Traps Responsible for Current Collapse in GaN Metal-Semiconductor Field-Effect Transistors

    National Research Council Canada - National Science Library

    Klein, P. B; Freitas, Jr., J. A; Binari, S. C; Wickenden, A. E

    1999-01-01

    ... of current collapse to determine the photoionization spectra of the traps involved. In the n-channel device investigated, the two electron traps observed were found to be very deep and strongly coupled to the lattice...

  20. The use of radiation trapping in the measurement of the electron excitation cross section for the production of the 1s4 (3P1) level of Ne

    International Nuclear Information System (INIS)

    Miers, R.E.; Gastineau, J.E.; Phillps, M.H.; Anderson, L.W.; Lin, C.C.

    1981-01-01

    The authors report the use of laser induced fluorescence for the first measurement of the electron excitation cross section for the production of the 1s 4 ( 3 P 1 ) level of Ne. Radiation trapping is used to lengthen the effective lifetime of the 1s 4 level allowing for the electron excitation cross section of the 1s 4 level to be measured in a manner similar to the measurement of electron excitation cross sections of the metastable 1s 3 and 1s 5 levels. (Auth.)

  1. Plasma accumulation in the HF supplemented mirror trap

    International Nuclear Information System (INIS)

    Dougar-Jabon, V.D.; Golovaniksky, K.S.; Karyaka, V.I.

    1975-01-01

    The confinement of plasma bunches in the mirror trap with the combined barrier at ECR is experimentally studied. Under fulfilment of the phase autofocusing condition the reflection of electrons by the combined barrier is quasiadiabatic and plasma losses are determined by perpendicular diffusion. (Auth.)

  2. Fortran programs for the time-dependent Gross-Pitaevskii equation in a fully anisotropic trap

    Science.gov (United States)

    Muruganandam, P.; Adhikari, S. K.

    2009-10-01

    , etc.: 122 907 No. of bytes in distributed program, including test data, etc.: 609 662 Distribution format: tar.gz Programming language: FORTRAN 77 and Fortran 90/95 Computer: PC Operating system: Linux, Unix RAM: 1 GByte (i, iv, v), 2 GByte (ii, vi, vii, x, xi), 4 GByte (iii, viii, xii), 8 GByte (ix) Classification: 2.9, 4.3, 4.12 Nature of problem: These programs are designed to solve the time-dependent Gross-Pitaevskii nonlinear partial differential equation in one-, two- or three-space dimensions with a harmonic, circularly-symmetric, spherically-symmetric, axially-symmetric or anisotropic trap. The Gross-Pitaevskii equation describes the properties of a dilute trapped Bose-Einstein condensate. Solution method: The time-dependent Gross-Pitaevskii equation is solved by the split-step Crank-Nicolson method by discretizing in space and time. The discretized equation is then solved by propagation, in either imaginary or real time, over small time steps. The method yields the solution of stationary and/or non-stationary problems. Additional comments: This package consists of 12 programs, see "Program title", above. FORTRAN77 versions are provided for each of the 12 and, in addition, Fortran 90/95 versions are included for ii, iii, vi, viii, ix, xii. For the particular purpose of each program please see the below. Running time: Minutes on a medium PC (i, iv, v, vii, x, xi), a few hours on a medium PC (ii, vi, viii, xii), days on a medium PC (iii, ix). Program summary (1)Title of program: imagtime1d.F Title of electronic file: imagtime1d.tar.gz Catalogue identifier: Program summary URL: Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Distribution format: tar.gz Computers: PC/Linux, workstation/UNIX Maximum RAM memory: 1 GByte Programming language used: Fortran 77 Typical running time: Minutes on a medium PC Unusual features: None Nature of physical problem: This program is designed to solve the time-dependent Gross

  3. Photo-excited charge collection spectroscopy probing the traps in field-effect transistors

    CERN Document Server

    Im, Seongil; Kim, Jae Hoon

    2013-01-01

    Solid state field-effect devices such as organic and inorganic-channel thin-film transistors (TFTs) have been expected to promote advances in display and sensor electronics. The operational stabilities of such TFTs are thus important, strongly depending on the nature and density of charge traps present at the channel/dielectric interface or in the thin-film channel itself. This book contains how to characterize these traps, starting from the device physics of field-effect transistor (FET). Unlike conventional analysis techniques which are away from well-resolving spectral results, newly-introduced photo-excited charge-collection spectroscopy (PECCS) utilizes the photo-induced threshold voltage response from any type of working transistor devices with organic-, inorganic-, and even nano-channels, directly probing on the traps. So, our technique PECCS has been discussed through more than ten refereed-journal papers in the fields of device electronics, applied physics, applied chemistry, nano-devices and materia...

  4. Trapping of slow recoil ions: past results and speculations on the future

    International Nuclear Information System (INIS)

    Prior, M.H.

    1983-01-01

    A simple electrostatic ion trap has been utilized to capture low energy recoil ions made by fast heavy ion impact upon a neon gas target. The heavy ion beams have been provided by the LBL SuperHILAC and the work has so far concentrated upon studies of the decay of the trapped ion population in time following creation by the pulsed HILAC beam (3.3 msec pulse length, 36Hz repetition rate). The various charge states decay predominantly via electron capture collisions with the ambient gas in the ion trap. By varying the gas composition and density, one can determine the electron capture rate constants from which an effective (velocity averaged) capture cross-section can be obtained. The uniqueness of this work lies in the high charge states, up to Ne 10 + (fully stripped), and the low mean collision energies available (in the range 1.0 to 70.0 eV)

  5. Evaluation of pseudostem trapping as a control measure against banana weevil, Cosmopolites sordidus (Coleoptera: Curculionidae) in Uganda.

    Science.gov (United States)

    Gold, C S; Gold, C S; Okech, S H; Nokoe, S

    2002-02-01

    Controlled studies to determine the efficacy of pseudostem trapping in reducing adult populations of the banana weevil, Cosmopolites sordidus (Germar), were conducted under farmer conditions in Ntungamo district, Uganda. Twenty-seven farms were stratified on the basis of C. sordidus population density (estimated by mark and recapture methods) and divided among three treatments: (i) researcher-managed trapping (one trap per mat per month): (ii) farmer-managed trapping (trap intensity at discretion of farmer); and (iii) controls (no trapping). Intensive trapping (managed by researchers) resulted in significantly lower C. sordidus damage after one year. Over the same period, C. sordidus numbers declined by 61% on farms where trapping was managed by researchers, 53% where farmers managed trapping and 38% on farms without trapping; however, results varied greatly among farms and, overall, there was no significant effect of trapping on C. sordidus numbers. Moreover, there was only a weak relationship between the number of C. sordidus removed and the change in population density. Trapping success appeared to be affected by management levels and immigration from neighbouring farms. Although farmers were convinced that trapping was beneficial, adoption has been low due to resource requirements.

  6. High-harmonic generation in a quantum electron gas trapped in a nonparabolic and anisotropic well

    Science.gov (United States)

    Hurst, Jérôme; Lévêque-Simon, Kévin; Hervieux, Paul-Antoine; Manfredi, Giovanni; Haas, Fernando

    2016-05-01

    An effective self-consistent model is derived and used to study the dynamics of an electron gas confined in a nonparabolic and anisotropic quantum well. This approach is based on the equations of quantum hydrodynamics, which incorporate quantum and nonlinear effects in an approximate fashion. The effective model consists of a set of six coupled differential equations (dynamical system) for the electric dipole and the size of the electron gas. Using this model we show that: (i) high harmonic generation is related to the appearance of chaos in the phase space, as attested to by related Poincaré sections; (ii) higher order harmonics can be excited efficiently and with relatively weak driving fields by making use of chirped electromagnetic waves.

  7. Trapping of positrons in a Penning Malmberg trap in the view of accumulating them with the use of a pulsed beam

    International Nuclear Information System (INIS)

    Dupre, P.

    2011-09-01

    The weak equivalence principle, a fundament of Einstein general relativity, states that gravitational mass and inertial mass are equal whatever the body. This equivalence principle has never been directly tested with antimatter. The GBAR (Gravitational Behaviour of Antimatter at Rest) experiment intends to test it by measuring the acceleration of ultra cold anti-hydrogens in free fall. The production of such anti-atoms requires a pulse of about 10 10 positrons in a few tens of nanoseconds. This thesis focuses on the development of a new accumulation technique of positrons in a Penning-Malmberg trap in order to create this pulse. This new method is an improvement of the accumulation technique of Oshima et al.. This technique requires a non-neutral electron plasma to cool down positrons in the trap in order to confine them. A continuous beam delivers positrons and the trapping efficiency is about 0.4%. The new method needs a positron pulsed beam and the method efficiency is estimated at 80%. A part of this thesis was performed at Riken (Tokyo) on the trap of Oshima et al. to study the behavior of non-neutral plasmas in this type of trap and the first accumulation method. A theoretical model was developed to simulate the positron trapping efficiency. The description and the systematic study of the new accumulation technique with a pulsed positron beam are presented. They includes notably the optimization through simulation of the electromagnetic configuration of the trap and of the parameters of the used non-neutral plasmas. (author)

  8. From chemolithoautotrophs to electrolithoautotrophs: CO2 fixation by Fe(II)-oxidizing bacteria coupled with direct uptake of electrons from solid electron sources.

    Science.gov (United States)

    Ishii, Takumi; Kawaichi, Satoshi; Nakagawa, Hirotaka; Hashimoto, Kazuhito; Nakamura, Ryuhei

    2015-01-01

    At deep-sea vent systems, hydrothermal emissions rich in reductive chemicals replace solar energy as fuels to support microbial carbon assimilation. Until recently, all the microbial components at vent systems have been assumed to be fostered by the primary production of chemolithoautotrophs; however, both the laboratory and on-site studies demonstrated electrical current generation at vent systems and have suggested that a portion of microbial carbon assimilation is stimulated by the direct uptake of electrons from electrically conductive minerals. Here we show that chemolithoautotrophic Fe(II)-oxidizing bacterium, Acidithiobacillus ferrooxidans, switches the electron source for carbon assimilation from diffusible Fe(2+) ions to an electrode under the condition that electrical current is the only source of energy and electrons. Site-specific marking of a cytochrome aa3 complex (aa3 complex) and a cytochrome bc1 complex (bc1 complex) in viable cells demonstrated that the electrons taken directly from an electrode are used for O2 reduction via a down-hill pathway, which generates proton motive force that is used for pushing the electrons to NAD(+) through a bc1 complex. Activation of carbon dioxide fixation by a direct electron uptake was also confirmed by the clear potential dependency of cell growth. These results reveal a previously unknown bioenergetic versatility of Fe(II)-oxidizing bacteria to use solid electron sources and will help with understanding carbon assimilation of microbial components living in electronically conductive chimney habitats.

  9. Shrew trap efficiency

    DEFF Research Database (Denmark)

    Gambalemoke, Mbalitini; Mukinzi, Itoka; Amundala, Drazo

    2008-01-01

    We investigated the efficiency of four trap types (pitfall, Sherman LFA, Victor snap and Museum Special snap traps) to capture shrews. This experiment was conducted in five inter-riverine forest blocks in the region of Kisangani. The total trapping effort was 6,300, 9,240, 5,280 and 5,460 trap......, our results indicate that pitfall traps are the most efficient for capturing shrews: not only do they have a higher efficiency (yield), but the taxonomic diversity of shrews is also higher when pitfall traps are used....

  10. Electron traps and scintillation mechanism in YAlO3:Ce and LuAlO3:Ce scintillators

    International Nuclear Information System (INIS)

    Wojtowicz, A.J.; Glodo, J.; Drozdowski, W.; Przegietka, K.R.

    1998-01-01

    In this paper we present the results of thermoluminescence, isothermal decay and scintillation light yield measurements on two isostructural scintillator materials, YAlO 3 :Ce and LuAlO 3 :Ce. In addition to the variety of deep traps identified by thermoluminescence and isothermal decays, scintillation light yield experiments demonstrate the presence in both materials of a number of relatively shallow traps. While the deep traps may reduce the scintillation light yield, they do not influence the kinetics of the process. The shallow traps, on the other hand, by interfering with the process of radiative recombination of charge carriers via Ce 3+ ions, can strongly affect not only the yield of the scintillation process but its kinetics as well. The presence of shallow traps provides a consistent explanation for a number of poorly understood relationships between the two scintillator materials, including a higher room temperature scintillation light yield and longer scintillation decay time in YAlO 3 :Ce, and a longer scintillation rise time in LuAlO 3 :Ce. Theoretical analysis indicates that elimination of these traps would make the two materials nearly identical in scintillator performance. Although the specific identity of all traps remains elusive, the performance of both scintillator materials is now, in practical terms, fully understood. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  11. Trapping saturation of the bump-on-tail instability and electrostatic harmonic excitation in Earth's foreshock

    International Nuclear Information System (INIS)

    Klimas, A.J.

    1990-01-01

    Trapping saturation of the bump-on-tail instability is discussed using electron plasma Vlasov simulation results. The role of electrostatic harmonic excitation is considered in detail and shown to play a decisive role in the saturation of the instability. An extensive discussion of the simulation results is given to show that the results are not significantly limited by the finite number of Fourier modes used nor by the discrete distribution of those modes in wave number. It is argued that in the leading edge of Earth's electron foreshock a narrow wave number band of unstable field modes leads to trapping saturation of the bump-on-tail instability while simultaneously exciting electrostatic plasma waves at harmonics of the plasma frequency in simialr narrow bands of shorter wavelengths. The argument is based (1) on the observations of Lacombe et al. (1985), who found intense plasma waves at the leading edge of the foreshock with a spectral distribution sufficiently narrow to trap particles in resonance with the waves, and (2) on numerical simulations of the foreshock electron plasma which indicate that trapping saturation of the bump-on-tail instability leads to phase space vortex formation with consequent excitation of electrostatic harmonics. Thus it is suggested that observations of electrostatic harmonics in the leading edge of the foreshock would strongly implicate trapping as the saturation mechanism for the bump-on-tail instability in that region

  12. PENTATRAP. A novel Penning-trap system for high-precision mass measurements

    Energy Technology Data Exchange (ETDEWEB)

    Doerr, Andreas

    2015-01-21

    The novel Penning-trap mass spectrometer PENTATRAP aims at mass-ratio determinations of medium-heavy to heavy ions with relative uncertainties below 10{sup -11}. From the mass ratios of certain ion species, the corresponding mass differences will be determined with sub-eV/c{sup 2} uncertainties. These mass differences are relevant for neutrino-mass experiments, a test of special relativity and tests of bound-state QED. Means to obtain the required precision are very stable trapping fields, the use of highly-charged ions produced by EBITs, a non-destructive cyclotron-frequency determination scheme employing detectors with single-ion sensitivity and a five-trap tower, that allows for measurement schemes being insensitive to magnetic field drifts. Within this thesis, part of the detection electronics was set up and tested under experimental conditions. A single-trap setup was realized. A Faraday cup in the trap tower enabled the proper adjustment of the settings of the beamline connecting the EBIT and the Penning-trap system, resulting in the first trapping of ions at PENTATRAP. A stabilization of switched voltages in the beamline and detailed studies of ion bunch characteristics allowed for reproducible loading of only a few ions. Detection of the axial oscillation of the trapped ions gave hints that in some cases, even single ions had been trapped. Furthermore, valuable conclusions about necessary modifications of the setup could be drawn.

  13. Current leakage relaxation and charge trapping in ultra-porous low-k materials

    International Nuclear Information System (INIS)

    Borja, Juan; Plawsky, Joel L.; Gill, William N.; Lu, T.-M.; Bakhru, Hassaram

    2014-01-01

    Time dependent dielectric failure has become a pivotal aspect of interconnect design as industry pursues integration of sub-22 nm process-technology nodes. Literature has provided key information about the role played by individual species such as electrons, holes, ions, and neutral impurity atoms. However, no mechanism has been shown to describe how such species interact and influence failure. Current leakage relaxation in low-k dielectrics was studied using bipolar field experiments to gain insight into how charge carrier flow becomes impeded by defects within the dielectric matrix. Leakage current decay was correlated to injection and trapping of electrons. We show that current relaxation upon inversion of the applied field can be described by the stretched exponential function. The kinetics of charge trapping events are consistent with a time-dependent reaction rate constant, k=k 0 ⋅(t+1) β−1 , where 0 < β < 1. Such dynamics have previously been observed in studies of charge trapping reactions in amorphous solids by W. H. Hamill and K. Funabashi, Phys. Rev. B 16, 5523–5527 (1977). We explain the relaxation process in charge trapping events by introducing a nonlinear charge trapping model. This model provides a description on the manner in which the transport of mobile defects affects the long-tail current relaxation processes in low-k films

  14. SU-F-T-318: Sensitivity and Stability of OSLDs with Filled Deep Electron/hole Traps Under Pre-Irradiation and Bleaching Conditions

    International Nuclear Information System (INIS)

    Kim, J; Park, S; Lee, H; Kim, H; Choi, C; Park, J

    2016-01-01

    Purpose: This work evaluated the characteristics of optically stimulated luminescence dosimeters (OSLDs) with fully filled deep electron/hole traps (OSLDfull) with the bleaching conditions according to the accumulated dose. Methods: The OSLDs were first pre-irradiated with a Co-60 gamma ray at more than 5 kGy, so as to fill the deep electron and hole traps. Using a 6-MV beam, the OSLDfull characteristics were investigated in terms of the full bleaching, fading, dose linearity, and dose sensitivity obtained in response to the accumulated dose values. To facilitate a comparison of the dose sensitivity, OSLDs with un-filled deep electron/hole traps (OSLDempty) were investigated in the same manner. A long-pass filter was used to exclude bleaching-source wavelengths of less than 520 nm. Various bleaching time and wavelength combinations were used in order to determine the optimal bleaching conditions for the OSLD full. Results: The fading for the OSLDfull exhibited stable signals after 8 min, for both 1- and 10-Gy. For 4-h bleaching time and an unfiltered bleaching device, the supralinear index values for the OSLDfull were 1.003, 1.002, 0.999, and 1.001 for doses of 2, 4, 7, and 10 Gy, respectively. For a 65-Gy accumulated dose with a 5-Gy fraction, no variation in dose sensitivity was obtained for the OSLDfull, within a standard deviation of 0.85%, whereas the OSLDempty dose sensitivity decreased by approximately 2.3% per 10 Gy. The filtered bleaching device yielded a highly stable sensitivity for OSLDfull, independent of bleaching time and within a standard deviation of 0.71%, whereas the OSLDempty dose sensitivity decreased by approximately 4.2% per 10 Gy for an accumulated dose of 25 Gy with a 5-Gy fraction. Conclusion: Under the bleaching conditions determined in this study, clinical dosimetry with OSLDfull is highly stable, having an accuracy of 1% with no change in dose sensitivity or linearity at clinical doses. This work was supported by a National Research

  15. Spin-trapping and ESR studies of the direct photolysis of aromatic amino acids, dipeptides, tripeptides and polypeptides in aqueous solutions-II. Tyrosine and related compounds

    Energy Technology Data Exchange (ETDEWEB)

    Lion, Y; Kuwabara, M; Riesz, P [National Cancer Inst., Bethesda, MD (USA)

    1982-01-01

    The UV-photolysis of peptides containing tyrosine (Tyr) was investigated in aqueous solutions at room temperature at 220 and 265 nm. The short-lived free radicals formed during photolysis were spin-trapped by t-nitrosobutane and identified by electron spin resonance. For N-acetyl-and N-formyl-L-Tyr and for peptides containing L-Tyr as the middle residue, photolysis at 265 nm under neutral conditions produced mainly spin-adducts due to the scission between the alpha carbon and the methylene group attached to the aromatic ring, while at 220 nm decarboxylation radicals were spin-trapped. Photolysis of di- and tripeptides at 275 nm in alkaline solutions predominantly generated deamination radicals. The radicals produced in the photolysis of the oxidized A chain of insulin were tentatively characterized by comparison with the results for di- and tripeptides.

  16. Fundamental physics in particle traps

    International Nuclear Information System (INIS)

    Quint, Wolfgang; Vogel, Manuel

    2014-01-01

    The individual topics are covered by leading experts in the respective fields of research. Provides readers with present theory and experiments in this field. A useful reference for researchers. This volume provides detailed insight into the field of precision spectroscopy and fundamental physics with particles confined in traps. It comprises experiments with electrons and positrons, protons and antiprotons, antimatter and highly charged ions, together with corresponding theoretical background. Such investigations represent stringent tests of quantum electrodynamics and the Standard model, antiparticle and antimatter research, test of fundamental symmetries, constants, and their possible variations with time and space. They are key to various aspects within metrology such as mass measurements and time standards, as well as promising to further developments in quantum information processing. The reader obtains a valuable source of information suited for beginners and experts with an interest in fundamental studies using particle traps.

  17. A search for supersymmetric electrons with the Mark II detector at PEP (Positron Electron Project)

    Energy Technology Data Exchange (ETDEWEB)

    LeClaire, B.W.

    1987-10-01

    An experimental search for selectrons, the supersymmetric partner of the electron, has been performed at the PEP storage ring at SLAC using the Mark II detector. The experimental search done was based upon hypothetical reaction in e/sup +/e/sup -/ interactions at PEP center of mass energies of 29 GeV. In this reaction the selectrons, e-tilde, are assumed produced by the interaction of one of initial state electrons with a photon radiated from the other initial state electron. This latter electron is assumed to continue down the beam pipe undetected. The photon and electron then produce a selectron and a photino, ..gamma..-tilde, in the supersymmetric analog of Compton scattering. The photino is assumed to be the lightest supersymmetric particle, and as such, does not interact in the detector, thereby escaping detection very much like a neutrino. The selectron is assumed to immediately decay into an electron and photino. This electron is produced with large p perpendicular with respect to the beam pipe, since it must balance the transverse momentum carried off by the photinos. Thus, the experimental signature of the process is a single electron in the detector with a large unbalanced tranverse momentum. No events of this type were observed in the original search of 123 pb/sup -1/ of data, resulting in a cross section limit of less than 2.4 x 10/sup -2/ pb (at the 95% CL) within the detector acceptance. This cross section upper limit applies to any process which produces anomalous single electron events with missing transverse momentum. When interpreted as a supersymmetry search it results in a lower selectron mass limit of 22.2 GeV/c/sup 2/ for the case of massless photinos. Limits for non-zero mass photinos have been calculated. 87 refs., 67 figs., 17 tabs.

  18. A search for supersymmetric electrons with the Mark II detector at PEP [Positron Electron Project

    International Nuclear Information System (INIS)

    LeClaire, B.W.

    1987-10-01

    An experimental search for selectrons, the supersymmetric partner of the electron, has been performed at the PEP storage ring at SLAC using the Mark II detector. The experimental search done was based upon hypothetical reaction in e + e - interactions at PEP center of mass energies of 29 GeV. In this reaction the selectrons, e, are assumed produced by the interaction of one of initial state electrons with a photon radiated from the other initial state electron. This latter electron is assumed to continue down the beam pipe undetected. The photon and electron then produce a selectron and a photino, γ, in the supersymmetric analog of Compton scattering. The photino is assumed to be the lightest supersymmetric particle, and as such, does not interact in the detector, thereby escaping detection very much like a neutrino. The selectron is assumed to immediately decay into an electron and photino. This electron is produced with large p perpendicular with respect to the beam pipe, since it must balance the transverse momentum carried off by the photinos. Thus, the experimental signature of the process is a single electron in the detector with a large unbalanced tranverse momentum. No events of this type were observed in the original search of 123 pb -1 of data, resulting in a cross section limit of less than 2.4 x 10 -2 pb (at the 95% CL) within the detector acceptance. This cross section upper limit applies to any process which produces anomalous single electron events with missing transverse momentum. When interpreted as a supersymmetry search it results in a lower selectron mass limit of 22.2 GeV/c 2 for the case of massless photinos. Limits for non-zero mass photinos have been calculated. 87 refs., 67 figs., 17 tabs

  19. Synthesis, Characterization, and Biological Activity of Mn(II, Fe(II, Co(II, Ni(II, Cu(II, Zn(II, and Cd(II Complexes of N-Thiophenoyl-N′-Phenylthiocarbohydrazide

    Directory of Open Access Journals (Sweden)

    M. Yadav

    2013-01-01

    Full Text Available Mn(II, Fe(II, Co(II, Ni(II, Cu(II, Zn(II, and Cd(II complex of N-thiophenoyl -N′-phenylthiocarbohydrazide (H2 TPTH have been synthesized and characterized by elemental analysis, magnetic susceptibility measurements, infrared, NMR, electronic, and ESR spectral studies. The complexes were found to have compositions [Mn(H TPTH2], [Co(TPTH (H2O2], [Ni(TPTH (H2O2], [Cu(TPTH], [Zn(H TPTH], [Cd(H TPTH2], and [Fe(H TPTH2(EtOH]. The magnetic and electronic spectral studies suggest square planar geometry for [Cu(TPTH], tetrahedral geometry for [Zn(TPTH] and [Cd(H TPTH2], and octahedral geometry for rest of the complexes. The infrared spectral studies of the 1 : 1 deprotonated complexes suggest bonding through enolic oxygen, thiolato sulfur, and both the hydrazinic nitrogens. Thus, H2TPTH acts as a binegative tetradentate ligand. H2 TPTH and its metal complexes have been screened against several bacteria and fungi.

  20. Effects of electrostatic trapping on neoclassical transport in an impure plasma

    International Nuclear Information System (INIS)

    Hazeltine, R.D.; Ware, A.A.

    1976-01-01

    Contamination of a toroidally confined plasma by highly charged impurity ions can produce substantial variation of the electrostatic potential within a magnetic surface. The resulting electrostatic trapping and electrostatic drifts, of hydrogen ions and electrons, yields significant alterations in neoclassical transport theory. A transport theory which includes these effects is derived from the drift-kinetic equation, with an ordering scheme modeled on the parameters of recent tokamak experiments. The theory self-consistently predicts that electrostatic trapping should be fully comparable to magnetic trapping, and provides transport coefficients which, depending quadratically upon the temperature and pressure gradients, differ markedly from the standard neoclassical coefficients for a pure plasma

  1. Magnetic traps with a sperical separatrix: Tornado traps

    International Nuclear Information System (INIS)

    Peregood, B.P.; Lehnert, B.

    1979-11-01

    A review is given on the features of magnetic traps with a spherical separatrix, with special emphesis on Tornado spiral coil configurations. The confinement and heating of static plasmas in Tornado traps is treated, including the topology of the magnetic field structure, the magneto-mechanical properties of the magnetic coil system, as well as the particle orbits and plasma behaviour in these traps. In additio, the mode of rotating plasma operation by crossed electric and magnetic fields is being described. The results of experiments on static and rotating plasmas are summarized, and conclusions are drawn about future possibilities of Tornado traps for the creation and containment of hot plasmas. (author)

  2. Magnetic traps with a spherical separatrix: Tornado traps

    International Nuclear Information System (INIS)

    Peregood, B.P.; Lehnert, B.

    1981-01-01

    A review is given on the features of magnetic traps with a spherical separatrix, with special emphasis on Tornado spiral coil configurations. The confinement and heating of static plasms in Tornado traps is treated, including the topology of the magnetic field structure, the magneto-mechanical properties of the magnetic coil system, as well as the particle orbits and plasma behaviour in these traps. In addition, the mode of rotating plasma operation by crossed electric and magnetic fields is described. The results of experiments on static and rotating plasmas are summarized, and conclusions are drawn about future possibilities of Tornado traps in the creation and containment of hot plasmas. (orig.)

  3. Red trap colour of the carnivorous plant Drosera rotundifolia does not serve a prey attraction or camouflage function.

    Science.gov (United States)

    Foot, G; Rice, S P; Millett, J

    2014-01-01

    The traps of many carnivorous plants are red in colour. This has been widely hypothesized to serve a prey attraction function; colour has also been hypothesized to function as camouflage, preventing prey avoidance. We tested these two hypotheses in situ for the carnivorous plant Drosera rotundifolia. We conducted three separate studies: (i) prey attraction to artificial traps to isolate the influence of colour; (ii) prey attraction to artificial traps on artificial backgrounds to control the degree of contrast and (iii) observation of prey capture by D. rotundifolia to determine the effects of colour on prey capture. Prey were not attracted to green traps and were deterred from red traps. There was no evidence that camouflaged traps caught more prey. For D. rotundifolia, there was a relationship between trap colour and prey capture. However, trap colour may be confounded with other leaf traits. Thus, we conclude that for D. rotundifolia, red trap colour does not serve a prey attraction or camouflage function.

  4. Radio frequency acceleration and manipulation of ultra-cold electron bunches

    NARCIS (Netherlands)

    Franssen, J.G.H.; Vredenbregt, E.J.D.; Luiten, O.J.

    2016-01-01

    We are developing an ultra-fast and ultra-cold electron source based on a grating magneto optical trap, RF acceleration and RF (de-) compression techniques. The electrons will be created by near-threshold, femtosecond photoionization of a laser-cooled and trapped gas. The electron cloud is extracted

  5. Photoexcited carrier trapping and recombination at Fe centers in GaN

    International Nuclear Information System (INIS)

    Uždavinys, T. K.; Marcinkevičius, S.; Leach, J. H.; Evans, K. R.; Look, D. C.

    2016-01-01

    Fe doped GaN was studied by time-resolved photoluminescence (PL) spectroscopy. The shape of PL transients at different temperatures and excitation powers allowed discrimination between electron and hole capture to Fe"3"+ and Fe"2"+ centers, respectively. Analysis of the internal structure of Fe ions and intra-ion relaxation rates suggests that for high repetition rates of photoexciting laser pulses the electron and hole trapping takes place in the excited state rather than the ground state of Fe ions. Hence, the estimated electron and hole capture coefficients of 5.5 × 10"−"8 cm"3/s and 1.8 × 10"−"8 cm"3/s should be attributed to excited Fe"3"+ and Fe"2"+ states. The difference in electron capture rates determined for high (MHz) and low (Hz) (Fang et al., Appl. Phys. Lett. 107, 051901 (2015)) pulse repetition rates may be assigned to the different Fe states participating in the carrier capture. A weak temperature dependence of the electron trapping rate shows that the potential barrier for the multiphonon electron capture is small. A spectral feature observed at ∼420 nm is assigned to the radiative recombination of an electron in the ground Fe"2"+ state and a bound hole.

  6. Runaway electrons beams in ITER disruptions

    International Nuclear Information System (INIS)

    Fleischmann, H.H.

    1993-01-01

    In agreement with the initial projections, the potential generation of runaway beams in disruptions of ITER discharges was performed. This analysis was based on the best-available present projections of plasma parameters existing in large-tokamak disruptions. Using these parameters, the potential contributions from various basic mechanisms for the generation of runway electrons were estimated. The envisioned mechanisms included (i) the well-known Dreicer process (assuming an evaporation of the runways from the thermal distribution), (ii) the seeding of runaway beams resulting from the potential presence of trapped high-temperature electrons from the original discharge still remaining in the disruption plasma at time of reclosure of the magnetic surfaces, and (iii) the generation of runaway beams through avalanche exponentiation of low-level seed runaways resulting via close collisions of existing runaways with cold plasma electrons. Finally, the prospective behavior of the any generated runaway beams -- in particular during their decay -- as well as their potential avoidance and/or damage controlled extraction through the use of magnetic perturbation fields also was considered in some detail

  7. 50 CFR 697.19 - Trap limits and trap tag requirements for vessels fishing with lobster traps.

    Science.gov (United States)

    2010-10-01

    ... vessels fishing with lobster traps. 697.19 Section 697.19 Wildlife and Fisheries FISHERY CONSERVATION AND... requirements for vessels fishing with lobster traps. (a) Trap limits for vessels fishing or authorized to fish... management area designation certificate or valid limited access American lobster permit specifying one or...

  8. Calibration of the OHREX high-resolution imaging crystal spectrometer at the Livermore electron beam ion traps

    Energy Technology Data Exchange (ETDEWEB)

    Hell, N. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Dr. Remeis-Sternwarte and ECAP, Universität Erlangen-Nürnberg, Bamberg 96049 (Germany); Beiersdorfer, P.; Magee, E. W.; Brown, G. V. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

    2016-11-15

    We report the calibration of the Orion High-Resolution X-ray (OHREX) imaging crystal spectrometer at the EBIT-I electron beam ion trap at Livermore. Two such instruments, dubbed OHREX-1 and OHREX-2, are fielded for plasma diagnostics at the Orion laser facility in the United Kingdom. The OHREX spectrometer can simultaneously house two spherically bent crystals with a radius of curvature of r = 67.2 cm. The focusing properties of the spectrometer allow both for larger distance to the source due to the increase in collected light and for observation of extended sources. OHREX is designed to cover a 2.5°–3° spectral range at Bragg angles around 51.3°. The typically high resolving powers at these large Bragg angles are ideally suited for line shape diagnostics. For instance, the nominal resolving power of the instrument (>10 000) is much higher than the effective resolving power associated with the Doppler broadening due to the temperature of the trapped ions in EBIT-I. The effective resolving power is only around 3000 at typical EBIT-I conditions, which nevertheless is sufficient to set up and test the instrument’s spectral characteristics. We have calibrated the spectral range for a number of crystals using well known reference lines in the first and second order and derived the ion temperatures from these lines. We have also made use of the 50 μm size of the EBIT-I source width to characterize the spatial focusing of the spectrometer.

  9. Use of spin traps to detect superoxide production in living cells by electron paramagnetic resonance (EPR) spectroscopy.

    Science.gov (United States)

    Abbas, Kahina; Babić, Nikola; Peyrot, Fabienne

    2016-10-15

    Detection of superoxide produced by living cells has been an on-going challenge in biology for over forty years. Various methods have been proposed to address this issue, among which spin trapping with cyclic nitrones coupled to EPR spectroscopy, the gold standard for detection of radicals. This technique is based on the nucleophilic addition of superoxide to a diamagnetic cyclic nitrone, referred to as the spin trap, and the formation of a spin adduct, i.e. a persistent radical with a characteristic EPR spectrum. The first application of spin trapping to living cells dates back 1979. Since then, considerable improvements of the method have been achieved both in the structures of the spin traps, the EPR methodology, and the design of the experiments including appropriate controls. Here, we will concentrate on technical aspects of the spin trapping/EPR technique, delineating recent breakthroughs, inherent limitations, and potential artifacts. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. The PS 200 catching trap: A new tool for ultra-low energy antiproton physics

    International Nuclear Information System (INIS)

    Holzscheiter, M.H.; Dyer, P.L.; King, N.S.P.; Lizon, D.C.; Morgan, G.L.; Schauer, M.M.; Schecker, J.A.; Hoibraten, S.; Lewis, R.A.; Otto, T.

    1994-01-01

    Approximately one million antiprotons have been trapped and electron cooled in the PS200 catching trap from a single fast extracted pulse from LEAR. The system is described in detail, different extraction schemes are discussed, and possible applications of this instrument to ultra-low energy atomic and nuclear physics with antiprotons are mentioned

  11. Trapped electron spectra in hydrates of sodium, potassium and tetraalkylammonium hydroxides of varying H2O content

    International Nuclear Information System (INIS)

    Zagorski, Z.P.; Grodkowski, J.; Bobrowski, K.

    1980-01-01

    Transient spectra of e - sub(t) in hydrates at room temperature obtained by pulse radiolysis with Cerenkov L.S.M. are presented. The decrease in number of H 2 O molecules n, in KOH.nH 2 O and NaOH.nH 2 O is accompanied by a blue shift of the absorption maximum. The same tendency is observed in concentrated solutions. The shifts in tetraalkylammonium hydroxides are not as extended as in KOH and NaOH systems, because TAAH's coordinate more H 2 O molecules and the preparation of solution of higher concentration is not possible. Freezing of hydrates does not change the e - sub(t) spectrum considerably. The concept of the trap containing one molecule of water and one electron is discussed in the general context of the phenomena. (author)

  12. Electron Transfer Pathways Facilitating U(VI) Reduction by Fe(II) on Al- vs Fe-Oxides

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, S. D. [Pacific Northwest National Laboratory, Physical Sciences Division, P.O. Box; Becker, U. [The University of Michigan, Department of Earth; Rosso, K. M. [Pacific Northwest National Laboratory, Physical Sciences Division, P.O. Box

    2017-09-06

    This study continues mechanistic development of heterogeneous electron transfer (ET) pathways at mineral surfaces in aquatic environments that enable the reduction U(VI) by surface-associated Fe(II). Using computational molecular simulation within the framework of Marcus Theory, our findings highlight the importance of the configurations and interaction of the electron donor and acceptor species with the substrate, with respect to influencing its electronic structure and thereby the ability of semiconducting minerals to facilitate ET. U(VI) reduction by surface-associated Fe(II) (adsorbed or structurally incorporated into the lattice) on an insulating, corundum (001) surface (α-Al2O3) occurs when proximal inner-sphere (IS) surface complexes are formed, such that ET occurs through a combination of direct exchange (i.e., Fe d- and U f-orbitals overlap through space) and superexchange via intervening surface oxygen atoms. U(VI) reduction by coadsorbed Fe(II) on the isostructural semiconducting hematite (α-Fe2O3) basal surface requires either their direct electronic interaction (e.g., IS complexation) or mediation of this interaction indirectly through the surface via an intrasurface pathway. Conceptually possible longer-range ET by charge-hopping through surface Fe atoms was investigated to determine whether this indirect pathway is competitive with direct ET. The calculations show that energy barriers are large for this conduction-based pathway; interfacial ET into the hematite surface is endothermic (+80.1 kJ/mol) and comprises the rate-limiting step (10–6 s–1). The presence of the IS adsorbates appears to weaken the electronic coupling between underlying Fe ions within the surface, resulting in slower intra-surface ET (10–5 s–1) than expected in the bulk basal plane. Our findings lay out first insights into donor-acceptor communication via a charge-hopping pathway through the surface for heterogeneous reduction of U(VI) by Fe(II) and help provide a basis

  13. Effect of the Electron Cloud and CSR on the Upgrade of the PEP-II

    International Nuclear Information System (INIS)

    Heifets, Samuel A

    2001-01-01

    Effects of the electron cloud and of the coherent synchrotron radiation (CSR) on the possible upgrade of the PEP-II B-factory are studied. PEP-II B factory operates with parameters shown in Table 1 and already exceeds the design luminosity. Nevertheless, a possibility of upgrading the machine to even higher luminosities is under consideration [1]. Several scenarios are summarized in Table 2. This paper describes effects of the electron cloud and of the coherent synchrotron radiation (CSR) on the proposed upgrades of the PEP-II B-factory. The first effect was observed [3] and caused [4] the degradation of the emittance at KEK B-factory. The analytic expression for the e-wake [2] is used in calculations of the head-tail instability. Other obvious effects of higher beam currents such as additional heat load are not considered. The short wave length CSR has been recently observed at Brookhaven [6]. Consideration of the effect of such CSR on the beam dynamics is based on our previous paper [7

  14. Evaluation of trapping parameters of annealed natural quartz

    International Nuclear Information System (INIS)

    Zhou, Rui; Wei, Ming-Jian; Song, Bo; Zhang, Yan; Zhao, Qiu-Yue; Pan, Bao-Lin; Li, Teng-Fei

    2016-01-01

    The thermoluminescence (TL) trapping parameters of annealed quartz have been investigated. The apparent TL peaks observed at temperatures of 133 °C, 211 °C, 266 °C and 405 °C, respectively, were named Peak I, Peak II, Peak III and Peak IV. The T_m − T_s_t_o_p method is applied to investigate the number of peaks and their positions, and to obtain the trap distributions in the quartz. Peak shape (PS), Hoogenstraaten method (Various Heating Rates Method, VHR), and Computerized Glow Curve Deconvolution (CGCD) are used to evaluate the trapping parameters of the annealed quartz. The glow curve can be considered as a superposition of at least nine overlapping peaks. These peaks show up at 133 °C, 211 °C, 266 °C, 308 °C, 333 °C, 384 °C, 441 °C, 466 °C and 484 °C. The PS method can be only used in evaluating the parameters for Peaks I. The VHR method can be used in evaluating the trapping parameters for the first three peaks. CGCD method is complementary to obtaining parameters for the sub-peaks, and the thermal quenching correction with the Urbach’s method is necessary. The Urbach’s coefficient for the quartz is 30.03 kT_m.

  15. Evaluation of trapping parameters of annealed natural quartz

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Rui [College of Resources, Environment & Tourism, Capital Normal University, 100048 Beijing (China); Shisanling Seismic Station, Institute of Earthquake Science, CEA, 102200 Beijing (China); Wei, Ming-Jian, E-mail: weimj@cnu.edu.cn [College of Resources, Environment & Tourism, Capital Normal University, 100048 Beijing (China); Song, Bo [College of Resources, Environment & Tourism, Capital Normal University, 100048 Beijing (China); Beijing Jing Yuan School, 100040 Beijing (China); Zhang, Yan [College of Resources, Environment & Tourism, Capital Normal University, 100048 Beijing (China); School of TaiPingqiao, Nan Lu of West Railway Station, 100073 Beijing (China); Zhao, Qiu-Yue [Key Laboratory of Tourism and Resources Environment in Universities of Shandong, Taishan University, 271000 Tai’an (China); Pan, Bao-Lin; Li, Teng-Fei [College of Resources, Environment & Tourism, Capital Normal University, 100048 Beijing (China)

    2016-05-15

    The thermoluminescence (TL) trapping parameters of annealed quartz have been investigated. The apparent TL peaks observed at temperatures of 133 °C, 211 °C, 266 °C and 405 °C, respectively, were named Peak I, Peak II, Peak III and Peak IV. The T{sub m} − T{sub stop} method is applied to investigate the number of peaks and their positions, and to obtain the trap distributions in the quartz. Peak shape (PS), Hoogenstraaten method (Various Heating Rates Method, VHR), and Computerized Glow Curve Deconvolution (CGCD) are used to evaluate the trapping parameters of the annealed quartz. The glow curve can be considered as a superposition of at least nine overlapping peaks. These peaks show up at 133 °C, 211 °C, 266 °C, 308 °C, 333 °C, 384 °C, 441 °C, 466 °C and 484 °C. The PS method can be only used in evaluating the parameters for Peaks I. The VHR method can be used in evaluating the trapping parameters for the first three peaks. CGCD method is complementary to obtaining parameters for the sub-peaks, and the thermal quenching correction with the Urbach’s method is necessary. The Urbach’s coefficient for the quartz is 30.03 kT{sub m}.

  16. Capture of melon flies, Zeugodacus cucurbitae (Diptera: Tephritidae), in a food-baited Multilure trap: influence of distance, diet, and sex

    Science.gov (United States)

    Many countries operate trapping programs to detect invasions of pestiferous fruit fly species (Diptera: Tephritidae). Surveillance relies heavily on traps baited with male lures, which, while powerful, have limited effectiveness, because (i) they are sex-specific and (ii) males of some species do no...

  17. Mobile quantum sensing with spins in optically trapped nanodiamonds

    Science.gov (United States)

    Awschalom, David D.

    2013-03-01

    The nitrogen-vacancy (NV) color center in diamond has emerged as a powerful, optically addressable, spin-based probe of electromagnetic fields and temperature. For nanoscale sensing applications, the NV center's atom-like nature enables the close-range interactions necessary for both high spatial resolution and the detection of fields generated by proximal nuclei, electrons, or molecules. Using a custom-designed optical tweezers apparatus, we demonstrate three-dimensional position control of nanodiamonds in solution with simultaneous optical measurement of electron spin resonance (ESR)[3]. Despite the motion and random orientation of NV centers suspended in the optical trap, we observe distinct peaks in the ESR spectra from the ground-state spin transitions. Accounting for the random dynamics of the trapped nanodiamonds, we model the ESR spectra observed in an applied magnetic field and estimate the dc magnetic sensitivity based on the ESR line shapes to be 50 μT/√{ Hz }. We utilize the optically trapped nanodiamonds to characterize the magnetic field generated by current-carrying wires and ferromagnetic structures in microfluidic circuits. These measurements provide a pathway to spin-based sensing in fluidic environments and biophysical systems that are inaccessible to existing scanning probe techniques, such as the interiors of living cells. This work is supported by AFOSR and DARPA.

  18. The electron as a chemical entity 201 Farday lecture

    International Nuclear Information System (INIS)

    Dainton, F.S.

    1975-01-01

    After an introductory section, the subject is covered in sections, as follows: on 'dropping' an electron into a liquid or an amorphous solid; the preparation of solvated and trapped electrons in condensed media; the physical properties of solvated or trapped electrons (the E.S.R. spectrum and cavity structure; the equivalent conductance, mobility, diffusion constant, and Stokes radius of esub(s)sup(-); the ionic atmosphere relaxation time; the thermodynamic properties of esub(s)sup(-)); spectroscopic and other evidence concerning the cavities (the effects of pressure and temperature on the spectrum; direct evidence for a range of trap sizes for esub(t)sup(-)); the trapping and solvation mechanism; the chemical reactions of esub(s)sup(-); some applications of our knowledge of esub(s)sup(-). (U.K.)

  19. Role for DNA topoisomerase II in prostatic growth

    International Nuclear Information System (INIS)

    Nelson, W.G. V.

    1987-01-01

    In the studies presented the role of the mammalian type II topoisomerase in the proliferation of normal and neoplastic rat prostate cells in vitro and in vivo was evaluated. First, the utility of mammalian type II topoisomerase inhibitors for the study of the biologic functions of the enzyme was assessed. Novobiocin inhibited rat topoisomerase II, but also interacted directly with chromatin in rat ventral prostate nuclei as well. Teniposide and amsacrine both trapped topoisomerase II in a covalent enzyme-DNA reaction intermediate that could be recovered using a K-SDS precipitation assay. The specific trapping of covalent topoisomerase II-DNA complexes by teniposide was exploited to implicate topoisomerase II in DNA replication in cultured Dunning R3327-G rat prostatic adenocarcinoma cells. In 3 H-thymidine pulse and pulse-chase labelling experiments, newly replicated DNA was found to be enriched among DNA linked topoisomerase II following teniposide treatment. Additional experiments demonstrated that topoisomerase II formed covalent complexes in the presence of teniposide directly with nascent DNA chains. On the basis of this data, a model for topoisomerase II function in untangling intertwined daughter DNA strands during replication by acting in the wake of the DNA replication fork near the site of DNA synthesis was proposed

  20. Cryogenic surface ion traps

    International Nuclear Information System (INIS)

    Niedermayr, M.

    2015-01-01

    Microfabricated surface traps are a promising architecture to realize a scalable quantum computer based on trapped ions. In principle, hundreds or thousands of surface traps can be located on a single substrate in order to provide large arrays of interacting ions. To this end, trap designs and fabrication methods are required that provide scalable, stable and reproducible ion traps. This work presents a novel surface-trap design developed for cryogenic applications. Intrinsic silicon is used as the substrate material of the traps. The well-developed microfabrication and structuring methods of silicon are utilized to create simple and reproducible traps. The traps were tested and characterized in a cryogenic setup. Ions could be trapped and their life time and motional heating were investigated. Long ion lifetimes of several hours were observed and the measured heating rates were reproducibly low at around 1 phonon per second at a trap frequency of 1 MHz. (author) [de