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Sample records for auger electron emitters

  1. Nuclear Targeting with an Auger Electron Emitter Potentiates the Action of a Widely Used Antineoplastic Drug.

    PubMed

    Imstepf, Sebastian; Pierroz, Vanessa; Raposinho, Paula; Bauwens, Matthias; Felber, Michael; Fox, Thomas; Shapiro, Adam B; Freudenberg, Robert; Fernandes, Célia; Gama, Sofia; Gasser, Gilles; Motthagy, Felix; Santos, Isabel R; Alberto, Roger

    2015-12-16

    We present the combination of the clinically well-proven chemotherapeutic agent, Doxorubicin, and (99m)Tc, an Auger and internal conversion electron emitter, into a dual-action agent for therapy. Chemical conjugation of Doxorubicin to (99m)Tc afforded a construct which autonomously ferries a radioactive payload into the cell nucleus. At this site, damage is exerted by dose deposition from Auger radiation. The (99m)Tc-conjugate exhibited a dose-dependent inhibition of survival in a selected panel of cancer cells and an in vivo study in healthy mice evidenced a biodistribution which is comparable to that of the parent drug. The homologous Rhenium conjugate was found to effectively bind to DNA, inhibited human Topoisomerase II, and exhibited cytotoxicity in vitro. The collective in vitro and in vivo data demonstrate that the presented metallo-conjugates closely mimic native Doxorubicin. PMID:26473388

  2. Evaluation of new iodinated acridine derivatives for targeted radionuclide therapy of melanoma using 125I, an Auger electron emitter.

    PubMed

    Gardette, Maryline; Papon, Janine; Bonnet, Mathilde; Desbois, Nicolas; Labarre, Pierre; Wu, Ting-Dee; Miot-Noirault, Elisabeth; Madelmont, Jean-Claude; Guerquin-Kern, Jean-Luc; Chezal, Jean-Michel; Moins, Nicole

    2011-12-01

    The increasing incidence of melanoma and the lack of effective therapy on the disseminated form have led to an urgent need for new specific therapies. Several iodobenzamides or analogs are known to possess specific affinity for melanoma tissue. New heteroaromatic derivatives have been designed with a cytotoxic moiety and termed DNA intercalating agents. These compounds could be applied in targeted radionuclide therapy using (125)I, which emits Auger electrons and gives high-energy, localized irradiation. Two iodinated acridine derivatives have been reported to present an in vivo kinetic profile conducive to application in targeted radionuclide therapy. The aim of the present study was to perform a preclinical evaluation of these compounds. The DNA intercalating property was confirmed for both compounds. After radiolabeling with (125)I, the two compounds induced in vitro a significant radiotoxicity to B16F0 melanoma cells. Nevertheless, the acridine compound appeared more radiotoxic than the acridone compound. While cellular uptake was similar for both compounds, SIMS analysis and in vitro protocol showed a stronger affinity for melanin with acridone derivative, which was able to induce a predominant scavenging process in the melanosome and restrict access to the nucleus. In conclusion, the acridine derivative with a higher nuclear localization appeared a better candidate for application in targeted radionuclide therapy using (125)I. PMID:20567996

  3. Dosimetry at the sub-cellular scale of Auger-electron emitter 99mTc in a mouse single thyroid follicle.

    PubMed

    Taborda, A; Benabdallah, N; Desbrée, A

    2016-02-01

    The Auger-electrons emitted by (99m)Tc have been recently associated with the induction of thyroid stunning in in vivo experiments in mice, making the dosimetry at the sub-cellular level of (99m)Tc a pertinent and pressing subject. The S-values for (99m)Tc were calculated using MCNP6, which was first validated for studies at the sub-cellular scale and for low energies electrons. The calculation was then performed for (99m)Tc within different cellular compartments in a single mouse thyroid follicle model, considering the radiative and non-radiative transitions of the (99m)Tc radiation spectrum. It was shown that the contribution of the (99m)Tc Auger and low energy electrons to the absorbed dose to the follicular cells' nucleus is important, being at least of the same order of magnitude compared to the emitted photons' contribution and cannot be neglected. The results suggest that Auger-electrons emitted by (99m)Tc play a significant role in the occurrence of the thyroid stunning effect in mice. PMID:26704702

  4. 119Sb--a potent Auger emitter for targeted radionuclide therapy.

    PubMed

    Thisgaard, H; Jensen, M

    2008-09-01

    Auger electron emitting radionuclides in cancer therapy offer the opportunity to deliver a high radiation dose to the tumor cells with high radiotoxicity while minimizing toxicity to normal tissue. We have in this study identified the Auger emitter 119Sb as a potent nuclide for targeted radionuclide therapy based on theoretical dosimetry calculations at a subcellular scale. From these calculations we have determined the cellular S-values for this therapeutic isotope. Moreover, we have demonstrated the possibility of producing this isotope and also the SPECT-analogue 117Sb for patient-specific dosimetry, by measuring the proton irradiation yields for both isotopes using a low-energy cyclotron. The excellent SPECT imaging properties of the 117Sb radionuclide have been shown by scanning a Jaszczak SPECT Phantom. PMID:18841834

  5. {sup 119}Sb--A potent Auger emitter for targeted radionuclide therapy

    SciTech Connect

    Thisgaard, H.; Jensen, M.

    2008-09-15

    Auger electron emitting radionuclides in cancer therapy offer the opportunity to deliver a high radiation dose to the tumor cells with high radiotoxicity while minimizing toxicity to normal tissue. We have in this study identified the Auger emitter {sup 119}Sb as a potent nuclide for targeted radionuclide therapy based on theoretical dosimetry calculations at a subcellular scale. From these calculations we have determined the cellular S-values for this therapeutic isotope. Moreover, we have demonstrated the possibility of producing this isotope and also the SPECT-analogue {sup 117}Sb for patient-specific dosimetry, by measuring the proton irradiation yields for both isotopes using a low-energy cyclotron. The excellent SPECT imaging properties of the {sup 117}Sb radionuclide have been shown by scanning a Jaszczak SPECT Phantom.

  6. Positron annihilation induced Auger electron spectroscopy

    NASA Technical Reports Server (NTRS)

    Weiss, Alex; Koymen, A. R.; Mehl, David; Jensen, K. O.; Lei, Chun; Lee, K. H.

    1990-01-01

    Recently, Weiss et al. have demonstrated that it is possible to excite Auger transitions by annihilating core electrons using a low energy (less than 30eV) beam of positrons. This mechanism makes possible a new electron spectroscopy, Positron annihilation induced Auger Electron Spectroscopy (PAES). The probability of exciting an Auger transition is proportional to the overlap of the positron wavefunction with atomic core levels. Since the Auger electron energy provides a signature of the atomic species making the transition, PAES makes it possible to determine the overlap of the positron wavefunction with a particular element. PAES may therefore provide a means of detecting positron-atom complexes. Measurements of PAES intensities from clean and adsorbate covered Cu surfaces are presented which indicate that approx. 5 percent of positrons injected into CU at 25eV produce core annihilations that result in Auger transitions.

  7. Positron annihilation induced Auger electron emission

    SciTech Connect

    Weiss, A.; Jibaly, M.; Lei, Chun; Mehl, D.; Mayer, R.; Lynn, K.G.

    1988-01-01

    We report on measurements of Auger electron emission from Cu and Fe due to core hole excitations produced by the removal of core electrons by matter-antimatter annihilation. Estimates are developed of the probability of positrons annihilating with a 3p electron in these materials. Several important advantages of Positron annihilation induced Auger Electron Spectroscopy (PAES) for surface analysis are suggested. 10 refs., 2 figs.

  8. Evidence for Chirped Auger-Electron Emission

    NASA Astrophysics Data System (ADS)

    Schütte, B.; Bauch, S.; Frühling, U.; Wieland, M.; Gensch, M.; Plönjes, E.; Gaumnitz, T.; Azima, A.; Bonitz, M.; Drescher, M.

    2012-06-01

    Auger decay carries valuable information about the electronic structure and dynamics of atoms, molecules, and solids. Here we furnish evidence that under certain conditions Auger electrons are subject to an energetic chirp. The effect is disclosed in time-resolved streaking experiments on the Xe NOO and Kr MNN Auger decay using extreme-ultraviolet pulses from the free-electron laser in Hamburg as well as from a high-order harmonic laser source. The origin of this effect is found to be an exchange of energy between the Auger electron and an earlier emitted correlated photoelectron. The observed time-dependent spectral modulations are understood within an analytical model and confirmed by extensive computer simulations.

  9. Diamondoid monolayers as electron emitters

    DOEpatents

    Yang, Wanli; Fabbri, Jason D.; Melosh, Nicholas A.; Hussain, Zahid; Shen, Zhi-Xun

    2012-04-10

    Provided are electron emitters based upon diamondoid monolayers, preferably self-assembled higher diamondoid monolayers. High intensity electron emission has been demonstrated employing such diamondoid monolayers, particularly when the monolayers are comprised of higher diamondoids. The application of such diamondoid monolayers can alter the band structure of substrates, as well as emit monochromatic electrons, and the high intensity electron emissions can also greatly improve the efficiency of field-effect electron emitters as applied to industrial and commercial applications.

  10. Diamondoid monolayers as electron emitters

    DOEpatents

    Yang, Wanli; Fabbri, Jason D.; Melosh, Nicholas A.; Hussain, Zahid; Shen, Zhi-Xun

    2013-10-29

    Provided are electron emitters based upon diamondoid monolayers, preferably self-assembled higher diamondoid monolayers. High intensity electron emission has been demonstrated employing such diamondoid monolayers, particularly when the monolayers are comprised of higher diamondoids. The application of such diamondoid monolayers can alter the band structure of substrates, as well as emit monochromatic electrons, and the high intensity electron emissions can also greatly improve the efficiency of field-effect electron emitters as applied to industrial and commercial applications.

  11. Amorphous-diamond electron emitter

    DOEpatents

    Falabella, Steven

    2001-01-01

    An electron emitter comprising a textured silicon wafer overcoated with a thin (200 .ANG.) layer of nitrogen-doped, amorphous-diamond (a:D-N), which lowers the field below 20 volts/micrometer have been demonstrated using this emitter compared to uncoated or diamond coated emitters wherein the emission is at fields of nearly 60 volts/micrometer. The silicon/nitrogen-doped, amorphous-diamond (Si/a:D-N) emitter may be produced by overcoating a textured silicon wafer with amorphous-diamond (a:D) in a nitrogen atmosphere using a filtered cathodic-arc system. The enhanced performance of the Si/a:D-N emitter lowers the voltages required to the point where field-emission displays are practical. Thus, this emitter can be used, for example, in flat-panel emission displays (FEDs), and cold-cathode vacuum electronics.

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

    SciTech Connect

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

    2007-03-15

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

  13. Auger recombination in heavily doped shallow-emitter silicon p-n-junction solar cells, diodes, and transistors

    NASA Technical Reports Server (NTRS)

    Shibib, M. A.; Lindholm, F. A.; Fossum, J. G.

    1979-01-01

    A rigorous analytic evaluation of an emitter model that includes Auger recombination but excludes bandgap narrowing is presented. It is shown that such a model cannot explain the experimentally observed values of the open-circuit voltage in p-n-junction silicon solar cells. Thus physical mechanisms in addition to Auger recombination are responsible for the experimentally observed values of the open-circuit voltage in silicon solar cells and the common-emitter current gain in bipolar transistors.

  14. Effects of Auger electron elastic scattering in quantitative AES

    NASA Astrophysics Data System (ADS)

    Jablonski, Aleksander

    1987-09-01

    The Monte Carlo algorithm was developed for simulating the trajectories of electrons elastically scattered in the solid. The distribution of scattering angles was determined using the partial wave expansion method. This algorithm was used to establish the influence of Auger electron elastic collisions on the results of quantitative AES analysis. The calculations were performed for the most pronounced KLL, L 3 MM and M 5NN Auger transitions. It turned out that due to the elastic collisions the Auger electron signal is decreased by up to 10%. The corresponding decreased of the escape depth of Auger electrons reaches 30% as compared with the value derived from the inelastic mean free path. The values of the inelastic mean free path resulting from the overalyer method may be strongly affected by elastic scattering of Auger electrons.

  15. Microdosimetry of the Auger electron emitting 123I radionuclide using Geant4-DNA simulations

    NASA Astrophysics Data System (ADS)

    Fourie, H.; Newman, R. T.; Slabbert, J. P.

    2015-04-01

    Microdosimetric calculations of the Auger electron emitter 123I were done in liquid water spheres using the Geant4 toolkit. The electron emission spectrum of 123I produced by Geant4 is presented. Energy deposition and corresponding S-values were calculated to investigate the influence of the sub-cellular localization of the Auger emitter. It was found that S-values calculated by the Geant4 toolkit are generally lower than the values calculated by other Monte Carlo codes for the 123I radionuclide. The differences in the compared S-values are mainly due to the different particle emission spectra employed by the respective computational codes and emphasizes the influence of the spectra on dosimetry calculations.

  16. Microdosimetry of the Auger electron emitting 123I radionuclide using Geant4-DNA simulations.

    PubMed

    Fourie, H; Newman, R T; Slabbert, J P

    2015-04-21

    Microdosimetric calculations of the Auger electron emitter (123)I were done in liquid water spheres using the Geant4 toolkit. The electron emission spectrum of (123)I produced by Geant4 is presented. Energy deposition and corresponding S-values were calculated to investigate the influence of the sub-cellular localization of the Auger emitter. It was found that S-values calculated by the Geant4 toolkit are generally lower than the values calculated by other Monte Carlo codes for the (123)I radionuclide. The differences in the compared S-values are mainly due to the different particle emission spectra employed by the respective computational codes and emphasizes the influence of the spectra on dosimetry calculations. PMID:25825914

  17. Low Emittance Electron Beam Studies

    SciTech Connect

    Tikhoplav, Rodion

    2006-04-01

    We have studied the properties of a low emittance electron beam produced by laser pulses incident onto an rf gun photocathode. The experiments were carried out at the A0 photoinjector at Fermilab. Such beam studies are necessary for fixing the design of new Linear Colliders as well as for the development of Free Electron Lasers. An overview of the A0 photoinjector is given in Chapter 1. In Chapter 2 we describe the A0 photoinjector laser system. A stable laser system is imperative for reliable photoinjector operation. After the recent upgrade, we have been able to reach a new level of stability in the pulse-to-pulse fluctuations of the pulse amplitude, and of the temporal and transverse profiles. In Chapter 3 we present a study of transverse emittance versus the shape of the photo-cathode drive-laser pulse. For that purpose a special temporal profile laser shaping device called a pulse-stacker was developed. In Chapter 4 we discuss longitudinal beam dynamics studies using a two macro-particle bunch; this technique is helpful in analyzing pulse compression in the magnetic chicane, as well as velocity bunching effects in the rf-gun and the 9-cell accelerating cavity. In Chapter 5 we introduce a proposal for laser acceleration of electrons. We have developed a laser functioning on the TEM*{sub 01} mode, a mode with a longitudinal electric field component which is suitable for such a process. Using this technique at energies above 40 MeV, one would be able to observe laser-based acceleration.

  18. Auger, zero-energy photoelectron, coincidence spectroscopy (AZEPECO): Chemical-site-selective Auger electron spectroscopy

    SciTech Connect

    Lee, K.; Ji, D.; Hanson, D.M.; Hulbert, S.L.; Kuiper, P.

    1993-12-31

    The Auger electron spectrum associated with decay of a core-hole on the terminal nitrogen and that associated with the central nitrogen of nitrous oxide, N{sub 2}O, are obtained individually through the use of a coincidence technique. Specifically, each of the two Auger electron spectra is obtained by detection of Auger electrons in coincidence with near zero energy (threshold) photoelectrons at the respective ionization thresholds. These zero energy electrons serve to identify the core-ionization continuum associated with the different Auger electrons. The salient features of the experimental spectra are in good agreement with theoretical calculations. The low counting rate generally associated with coincidence experiments, especially in the gas phase, is not encountered because the low energy electrons are collected over a 4{pi} solid angle. Also, velocity discrimination is accomplished by a spatial filter rather than by time-of-flight to utilize the maximum duty cycle of the synchrotron source. These data are believed to be the first examples of chemical-site-selective molecular Auger spectra.

  19. Light modulated electron beam driven radiofrequency emitter

    DOEpatents

    Wilson, M.T.; Tallerico, P.J.

    1979-10-10

    The disclosure relates to a light modulated electron beam-driven radiofrequency emitter. Pulses of light impinge on a photoemissive device which generates an electron beam having the pulse characteristics of the light. The electron beam is accelerated through a radiofrequency resonator which produces radiofrequency emission in accordance with the electron, hence, the light pulses.

  20. An ultracold low emittance electron source

    NASA Astrophysics Data System (ADS)

    Xia, G.; Harvey, M.; Murray, A. J.; Bellan, L.; Bertsche, W.; Appleby, R. B.; Mete, O.; Chattopadhyay, S.

    2014-06-01

    Ultracold atom-based electron sources have recently been proposed as an alternative to the conventional photo-injectors or thermionic electron guns widely used in modern particle accelerators. The advantages of ultracold atom-based electron sources lie in the fact that the electrons extracted from the plasma (created from near threshold photo-ionization of ultracold atoms) have a very low temperature, i.e. down to tens of Kelvin. Extraction of these electrons has the potential for producing very low emittance electron bunches. These features are crucial for the next generation of particle accelerators, including free electron lasers, plasma-based accelerators and future linear colliders. The source also has many potential direct applications, including ultrafast electron diffraction (UED) and electron microscopy, due to its intrinsically high coherence. In this paper, the basic mechanism of ultracold electron beam production is discussed and our new research facility for an ultracold, low emittance electron source is introduced. This source is based on a novel alternating current Magneto-Optical Trap (the AC-MOT). Detailed simulations for a proposed extraction system have shown that for a 1 pC bunch charge, a beam emittance of 0.35 mm mrad is obtainable, with a bunch length of 3 mm and energy spread 1%.

  1. Looking for Auger signatures in III-nitride light emitters: A full-band Monte Carlo perspective

    SciTech Connect

    Bertazzi, Francesco Goano, Michele; Zhou, Xiangyu; Calciati, Marco; Ghione, Giovanni; Matsubara, Masahiko; Bellotti, Enrico

    2015-02-09

    Recent experiments of electron emission spectroscopy (EES) on III-nitride light-emitting diodes (LEDs) have shown a correlation between droop onset and hot electron emission at the cesiated surface of the LED p-cap. The observed hot electrons have been interpreted as a direct signature of Auger recombination in the LED active region, as highly energetic Auger-excited electrons would be collected in long-lived satellite valleys of the conduction band so that they would not decay on their journey to the surface across the highly doped p-contact layer. We discuss this interpretation by using a full-band Monte Carlo model based on first-principles electronic structure and lattice dynamics calculations. The results of our analysis suggest that Auger-excited electrons cannot be unambiguously detected in the LED structures used in the EES experiments. Additional experimental and simulative work are necessary to unravel the complex physics of GaN cesiated surfaces.

  2. Emittance growth from electron beam modulation

    SciTech Connect

    Blaskiewicz, M.

    2009-12-01

    In linac ring colliders like MeRHIC and eRHIC a modulation of the electron bunch can lead to a modulation of the beam beam tune shift and steering errors. These modulations can lead to emittance growth. This note presents simple formulas to estimate these effects which generalize some previous results.

  3. Auger effect in yellow light emitters based on InGaN–AlGaN–GaN quantum wells

    NASA Astrophysics Data System (ADS)

    Huong Ngo, Thi; Gil, Bernard; Valvin, Pierre; Damilano, Benjamin; Lekhal, Kaddour; De Mierry, Philippe

    2016-05-01

    The Auger effect and its impact on the internal quantum efficiency (IQE) of yellow light emitters based on silicon-doped InGaN–AlGaN–GaN quantum wells are investigated by power dependence measurement and using an ABC model. Photoluminescence intensity recorded as a function of excitation power density follows a linear dependence up to a threshold P T that depends on the design of the sample. Above this threshold, the variation of the intensity becomes sublinear, which is characteristic of the onset of Auger recombination processes. After extracting the evolution of IQE with pump power from the experimental data, we use a modified ABC modeling that includes the residual n-type doping to estimate the contribution of different recombination channels. We find that the Auger effect dominates in the high-excitation regime. In addition, we find that intercalating an AlGaN-strain-compensating layer reduces not only the coefficient of nonradiative recombination rates but also reduces the onset of Auger recombination.

  4. Properties of Auger electrons following excitation of polarized atoms by polarized electrons

    NASA Astrophysics Data System (ADS)

    Kupliauskienė, A.; Tutlys, V.

    2009-01-01

    In non-relativistic approximation, the most general expression for differential cross sections describing the properties of Auger-electron emission induced in the excitation of polarized atoms by polarized electrons is obtained for the first time. The ways of the application of the general expressions suitable for the specific experimental conditions are outlined by deriving the expressions for the asymmetry parameters and the magnetic dichroism of the angular distribution of the Auger electrons as well as of the angular correlations between the scattered and Auger electrons.

  5. Large-area lanthanum hexaboride electron emitter

    SciTech Connect

    Goebel, D.M.; Hirooka, Y.; Sketchley, T.A.

    1985-09-01

    A large-area cathode assembly which is capable of continuous, high-current electron emission is described. The cathode utilizes an indirectly heated lanthanum hexaboride (LaB/sub 6/) disk as the thermionic electron emitter. The LaB/sub 6/ cathode emits over 600 A of electrons at an average of 20 A/cm/sup 2/ continuously with no observable lifetime limits to date after about 400 h of operation in a plasma discharge. Proper clasping of the LaB/sub 6/ disk is required to avoid impurity production from chemical reactions with the holder and to provide adequate support if the disk fractures during rapid thermal cycling. Modification of the LaB/sub 6/ surface composition due to preferential sputtering of boron by hydrogen and argon ions in the plasma discharge has been observed. The surface appearance is consistent with the formation of LaB/sub 4/ as a result of boron depletion. The electron emission capability of the cathode is not significantly altered by the surface change. This surface modification by preferential sputtering is not observed in hollow cathodes where the ion energy from the cathode sheath voltage is typically less than 50 V. The electron emission by the cathode has not been affected by exposure to both air and water during operation. Utilizing thick disks of this intermediate temperature cathode material results in reliable, high-current, long-lifetime electron emitter assemblies.

  6. Site-specific Auger electron spectra of ethyl trifluoroacelate molecules studied by magnetic bottle electron spectrometer

    NASA Astrophysics Data System (ADS)

    Iwayama, Hiroshi; Shigemasa, Eiji; Hikosaka, Yasumasa; Nakano, Motoyoshi; Ito, Kenji; Lablanquie, Pascal; Penet, Francis; Andric, Lidija; Selles, Patricia

    2012-11-01

    We performed multielectron coincidence measurements for inner-shell photoionizations of ethyl trifluoroacelate molecules (C4H5F3O2) using a magnetic bottle electron spectrometer. From a two dimensional coincidence map between a photoelectron and Auger electron for C 1s ionizations, we extracted site-specific Auger electron spectra for each carbon site and corresponding binding energy of doubly charged states.

  7. Some strategies for quantitative scanning Auger electron microscopy

    NASA Technical Reports Server (NTRS)

    Browning, R.; Peacock, D. C.; Prutton, M.

    1985-01-01

    The general applicability of power law forms of the background in electron spectra is pointed out and exploited for background removal from under Auger peaks. This form of B(E) is found to be extremely sensitive to instrumental alignment and to fault-free construction - an observation which can be used to set up analyser configurations in an accurate way. Also, differences between N(E) and B(E) can be used to derive a spectrometer transmission function T(E). The questions of information density in an energy-analysing spatially-resolving instrument are addressed after reliable instrumental characterization has been established. Strategies involving ratio histograms, showing the population distribution of the ratio of a pair of Auger peak heights, composition scatter diagrams and windowed imaging are discussed and illustrated.

  8. LOW EMITTANCE ELECTRON BEAMS FOR THE RHIC ELECTRON COOLER

    SciTech Connect

    KEWISCH,J.; CHANG, X.

    2007-06-25

    An electron cooler, based on an Energy Recovery Linac (ERL) is under development for the Relativistic Heavy Ion Collider (RMIC) at Brookhaven National Laboratory. This will be the first electron cooler operating at high energy with bunched beams. In order to achieve sufficient cooling of the ion beams the electron have to have a charge of 5 nC and a normalized emittance less than 4 {mu}. This paper presents the progress in optimizing the injector and the emittance improvements from shaping the charge distribution in the bunch.

  9. Innovative Field Emitters for High-Voltage Electronic Devices

    NASA Astrophysics Data System (ADS)

    Sominski, G. G.; Sezonov, V. E.; Taradaev, E. P.; Tumareva, T. A.; Zadiranov, Yu. M.; Kornishin, S. Yu.; Stepanova, A. N.

    2015-12-01

    We describe multitip field emitters with protective coatings, which were developed in Peter the Great St. Petersburg Polytechnic University. The coatings ensure long-term operation of the emitters under high currents and technical vacuum. Innovative multi-layer emitters composed of contacting nanolayers of materials with different work functions are presented as well. The possibility by using the developed emitters in high-voltage electronic devices is demonstrated.

  10. Digital electronics for the Pierre Auger Observatory AMIGA muon counters

    NASA Astrophysics Data System (ADS)

    Wainberg, O.; Almela, A.; Platino, M.; Sanchez, F.; Suarez, F.; Lucero, A.; Videla, M.; Wundheiler, B.; Melo, D.; Hampel, M. R.; Etchegoyen, A.

    2014-04-01

    The ``Auger Muons and Infill for the Ground Array'' (AMIGA) project provides direct muon counting capacity to the Pierre Auger Observatory and extends its energy detection range down to 0.3 EeV. It currently consists of 61 detector pairs (a Cherenkov surface detector and a buried muon counter) distributed over a 23.5 km2 area on a 750 m triangular grid. Each counter relies on segmented scintillator modules storing a logical train of `0's and `1's on each scintillator segment at a given time slot. Muon counter data is sampled and stored at 320 MHz allowing both the detection of single photoelectrons and the implementation of an offline trigger designed to mitigate multi-pixel PMT crosstalk and dark rate undesired effects. Acquisition is carried out by the digital electronics built around a low power Cyclone III FPGA. This paper presents the digital electronics design, internal and external synchronization schemes, hardware tests, and first results from the Observatory.

  11. Plasma treatment for producing electron emitters

    DOEpatents

    Coates, Don Mayo; Walter, Kevin Carl

    2001-01-01

    Plasma treatment for producing carbonaceous field emission electron emitters is disclosed. A plasma of ions is generated in a closed chamber and used to surround the exposed surface of a carbonaceous material. A voltage is applied to an electrode that is in contact with the carbonaceous material. This voltage has a negative potential relative to a second electrode in the chamber and serves to accelerate the ions toward the carbonaceous material and provide an ion energy sufficient to etch the exposed surface of the carbonaceous material but not sufficient to result in the implantation of the ions within the carbonaceous material. Preferably, the ions used are those of an inert gas or an inert gas with a small amount of added nitrogen.

  12. A new technique for Auger analysis of surface species subject to electron-induced desorption

    NASA Technical Reports Server (NTRS)

    Pepper, S. V.

    1973-01-01

    A method is presented to observe surface species subject to electron-induced desorption by Auger electron spectroscopy. The surface to be examined is moved under the electron beam at constant velocity, establishing a time independent condition and eliminating the time response of the electron spectrometer as a limiting factor. The dependence of the Auger signal on the surface velocity, incident electron current, beam diameter, and desorption cross section are analyzed. The method is illustrated by the Auger analysis of PTFE, in which the fluorine is removed by electron induced desorption.

  13. An Auger electron spectroscopy study of surface-preparation contaminants

    NASA Technical Reports Server (NTRS)

    Wu, D.; Stephens, R. M.; Outlaw, R. A.; Hopson, P.

    1990-01-01

    There are many cleaning techniques that are presently being employed for surface preparation of materials that are subsequently exposed to ultrahigh vacuum (UHV). Unfortunately, there are virtually no comparative measurements which establish the residual contaminant level of each method. In this report, eleven different cleaning methods, ranging from only detergent cleaning to electrochemical polishing, were applied to identical samples of 347 stainless steel. Two surface conditions, a standard machined surface and a mechanically polished surface, were studied. Auger electron spectroscopy (AES) within a UHV environment was then used to detect the types of contaminants and the magnitudes found on the sample surfaces. It was found that the electrochemical polishing gave the least contaminated surface of all metals studied and that mechanically polished surfaces were significantly cleaner than the as-machined surfaces for any given cleaning method. Furthermore, it was also found that the residual contaminations left by methanol, ethanol, isopropyl alcohol, acetone, and freon finishing rinses are almost the same.

  14. An Auger electron spectroscopy study of surface-preparation contaminants

    NASA Astrophysics Data System (ADS)

    Wu, D.; Stephens, R. M.; Outlaw, R. A.; Hopson, P.

    1990-02-01

    There are many cleaning techniques that are presently being employed for surface preparation of materials that are subsequently exposed to ultrahigh vacuum (UHV). Unfortunately, there are virtually no comparative measurements which establish the residual contaminant level of each method. In this report, eleven different cleaning methods, ranging from only detergent cleaning to electrochemical polishing, were applied to identical samples of 347 stainless steel. Two surface conditions, a standard machined surface and a mechanically polished surface, were studied. Auger electron spectroscopy (AES) within a UHV environment was then used to detect the types of contaminants and the magnitudes found on the sample surfaces. It was found that the electrochemical polishing gave the least contaminated surface of all metals studied and that mechanically polished surfaces were significantly cleaner than the as-machined surfaces for any given cleaning method. Furthermore, it was also found that the residual contaminations left by methanol, ethanol, isopropyl alcohol, acetone, and freon finishing rinses are almost the same.

  15. Multiple-Auger electron ejection after inner-shell ionization and excitation

    SciTech Connect

    Viefhaus, Jens

    2003-01-24

    Results on the Auger decay of core-ionized and core-exited Ar atoms above the Ar 2p threshold and at the Ar 2p3/2 {yields}3d resonance leading to double and triple ionization states are presented. Using a multiple time-of-flight analyzer arrangement for electron-electron coincidences, we directly observe for the first time a double Auger continuum following core electron ionization. Our results show clear evidence for continuously distributed Auger electron intensity over a 160 eV range of kinetic energies. This double Auger decay represents roughly 10 % of the normal single Auger channels. In the case of the resonant Auger decay we also observe a two-electron continuum of the same order of magnitude as in the non-resonant case which can be explained due to the existence of excited states of the doubly charged ion in the vicinity or just above the triple ionization threshold. In the latter case these states can further decay via emission of a low kinetic energy electron, which makes it possible to study the electron emission characteristics of the triple electron process. Both double- and triple-electron emission Auger processes will make it possible to study electron correlations undisturbed by the symmetry properties of the photoabsorption process.

  16. Is CO Carbon KVV Auger Electron Emission Affected by the Photoelectron?

    SciTech Connect

    Pruemper, G.; Fukuzawa, H.; Sakai, K.; Ueda, K.; Rolles, D.; Prince, K. C.; Harries, J. R.; Tamenori, Y.; Berrah, N.

    2008-12-05

    Angular distributions (ADs) of O{sup +} fragments from C 1s photoexcited CO detected in coincidence with carbon KVV Auger electrons emitted in the horizontal direction were measured at photon energies of 298, 305, 320, and 450 eV. At 450 eV, the ADs are polarization-independent and coincide with the molecular-frame Auger electron angular distribution. All measured ADs can be rationalized as a product of the same molecular-frame Auger electron angular distribution and the axial selectivity in the photoionization process. Thus the interaction between the photoelectron and the Auger electron for the normal Auger decay of CO can be neglected, and the two-step model is a good approximation.

  17. Diffraction and holography with photoelectrons and Auger electrons: Some new directions

    SciTech Connect

    Fadley, C.S. Lawrence Berkeley Lab., CA )

    1992-06-01

    The current status of photoelectron and Auger-electron diffraction is reviewed, with emphasis on new directions of activity. The use of forward scattering in the study of adsorbed molecules, epitaxial overlayers, and clean surfaces is one of the most developed applications, and one that will become more powerful as higher energy resolution and perhaps spin analysis are used to resolve emitters on the basis of chemical state, position at a surface, or magnetic state. The use of larger data sets spanning a considerable fraction of the solid angle above a surface will also much enhance the structural information available, for example, in the growth of epitaxial layers or nanostructures on surfaces. Detailed fitting of experimental data to theoretical calculations based upon either single scattering or multiple scattering should also provide more rich structural information, including such parameters as substrate interlayer relaxation. Surface phase transitions in which near-surface layers become highly disordered can also be studied, with results that are complementary to those from such techniques as low energy electron diffraction and medium energy ion scattering. Short-range magnetic order also can be probed by somehow resolving the spin of the outgoing electrons, e.g. by using multiplet-split core levels.

  18. Angular correlation between photoelectrons and auger electrons from K-shell ionization of neon.

    PubMed

    Landers, A L; Robicheaux, F; Jahnke, T; Schöffler, M; Osipov, T; Titze, J; Lee, S Y; Adaniya, H; Hertlein, M; Ranitovic, P; Bocharova, I; Akoury, D; Bhandary, A; Weber, Th; Prior, M H; Cocke, C L; Dörner, R; Belkacem, A

    2009-06-01

    We have used cold target recoil ion momentum spectroscopy to study the continuum correlation between the photoelectron of core-photoionized neon and the subsequent Auger electron. We observe a strong angular correlation between the two electrons. Classical trajectory Monte Carlo calculations agree quite well with the photoelectron energy distribution that is shifted due to the potential change associated with Auger decay. However, a striking discrepancy results in the distribution of the relative angle between Auger and photoelectron. The classical model predicts a shift in photoelectron flux away from the Auger emission direction, and the data strikingly reveal that the flux is lost rather than diverted, indicating that the two-step interpretation of photoionization followed by Auger emission is insufficient to fully describe the core-photoionization process. PMID:19658860

  19. Angular Correlation between Photoelectrons and Auger Electrons from K-Shell Ionization of Neon

    SciTech Connect

    Landers, A. L.; Robicheaux, F.; Bhandary, A.; Jahnke, T.; Schoeffler, M.; Titze, J.; Akoury, D.; Doerner, R.; Osipov, T.; Lee, S. Y.; Adaniya, H.; Hertlein, M.; Weber, Th.; Prior, M. H.; Belkacem, A.; Ranitovic, P.; Bocharova, I.; Cocke, C. L.

    2009-06-05

    We have used cold target recoil ion momentum spectroscopy to study the continuum correlation between the photoelectron of core-photoionized neon and the subsequent Auger electron. We observe a strong angular correlation between the two electrons. Classical trajectory Monte Carlo calculations agree quite well with the photoelectron energy distribution that is shifted due to the potential change associated with Auger decay. However, a striking discrepancy results in the distribution of the relative angle between Auger and photoelectron. The classical model predicts a shift in photoelectron flux away from the Auger emission direction, and the data strikingly reveal that the flux is lost rather than diverted, indicating that the two-step interpretation of photoionization followed by Auger emission is insufficient to fully describe the core-photoionization process.

  20. Change of Auger-electron emission from Ni-Pd alloys under magnetic phase transition

    NASA Astrophysics Data System (ADS)

    Elovikov, S. S.; Zykova, E. Y.; Gvozdover, R. S.; Colligon, J. S.; Yurasova, V. E.

    2006-04-01

    The change of Auger-electron emission from polycrystals of disordered ferromagnetic NiPd 3 and Ni 3 Pd alloys, under ferro- to paramagnetic transition, has been studied experimentally. It has been shown that the intensity of the Auger-lines, which are formed because of transition of valent zone 3d 3/2 and 3d 5/2 electrons, has local maxima near the Curie point T C for the alloys. Thus, the sensitivity of Auger-electron emission to a magnetic state of the alloy has been established.

  1. Auger electron intensity variations in oxygen-exposed large grain polycrystalline silver

    NASA Technical Reports Server (NTRS)

    Lee, W. S.; Outlaw, R. A.; Hoflund, G. B.; Davidson, M. R.

    1989-01-01

    Auger electron spectroscopic studies of the grains in oxygen-charged polycrystal-line silver show significant intensity variations as a function of crystallographic orientation. These intensity variations were observed by studies of the Auger images and line scans of the different grains (randomly selected) for each silver transition energy. The results can be attributed to the diffraction of the ejected Auger electrons and interpreted by corresponding changes in the electron mean-free path for inelastic scattering and by oxygen atom accumulation in the subsurface. The subsurface (second layer) octahedral sites increased in size because of surface relaxation and serve as a stable reservoir for the dissolved oxygen.

  2. Limits to Electron Beam Emittance from Stochastic Coulomb Interactions

    SciTech Connect

    Coleman-Smith, Christopher; Padmore, Howard A.; Wan, Weishi

    2008-08-22

    Dense electron beams can now be generated on an ultrafast timescale using laser driven photo-cathodes and these are used for a range of applications from ultrafast electron defraction to free electron lasers. Here we determine a lower bound to the emittance of an electron beam limited by fundamental stochastic Coulomb interactions.

  3. May Auger electron spectroscopy provide surface structural information?

    NASA Astrophysics Data System (ADS)

    Alonso, M.; Soria, F.

    1986-12-01

    Quantitative analysis of Auger electron spectroscopy peak energies, lineshapes and heights allows to determine the chemical composition of the surface layer, and in binary (111) semiconductors even the composition of the outermost surface bilayer, if the composition of a standard surface is known. Surface structural information can also be obtained by the interaction of these surfaces with some gases used as markers, when the gas absorption proceeds by an over/underlayer mechanism, as it happens in the initial stages of the interaction of oxygen with differently prepared GaAs(111) surfaces. Thus, we have been able to confirm the structure of the (111) 2 × 2 Ga surface, and to determine the oxygen absorption sites and occupation sequence, by comparison of the experimental intensities with calculations which model the surface structure and absorption sites. This formalism has also been applied to ( overline1overline1overline1) 1 × 1 facetted surfaces, where very different absorption behaviour is seen for surfaces prepared at different ion energies, but annealed at the same temperature.

  4. Auger Emitting Radiopharmaceuticals for Cancer Therapy

    NASA Astrophysics Data System (ADS)

    Falzone, Nadia; Cornelissen, Bart; Vallis, Katherine A.

    Radionuclides that emit Auger electrons have been of particular interest as therapeutic agents. This is primarily due to the short range in tissue, controlled linear paths and high linear energy transfer of these particles. Taking into consideration that ionizations are clustered within several cubic nanometers around the point of decay the possibility of incorporating an Auger emitter in close proximity to the cancer cell DNA has immense therapeutic potential thus making nuclear targeted Auger-electron emitters ideal for precise targeting of cancer cells. Furthermore, many Auger-electron emitters also emit γ-radiation, this property makes Auger emitting radionuclides a very attractive option as therapeutic and diagnostic agents in the molecular imaging and management of tumors. The first requirement for the delivery of Auger emitting nuclides is the definition of suitable tumor-selective delivery vehicles to avoid normal tissue toxicity. One of the main challenges of targeted radionuclide therapy remains in matching the physical and chemical characteristics of the radionuclide and targeting moiety with the clinical character of the tumor. Molecules and molecular targets that have been used in the past can be classified according to the carrier molecule used to deliver the Auger-electron-emitting radionuclide. These include (1) antibodies, (2) peptides, (3) small molecules, (4) oligonucleotides and peptide nucleic acids (PNAs), (5) proteins, and (6) nanoparticles. The efficacy of targeted radionuclide therapy depends greatly on the ability to increase intranuclear incorporation of the radiopharmaceutical without compromising toxicity. Several strategies to achieve this goal have been proposed in literature. The possibility of transferring tumor therapy based on the emission of Auger electrons from experimental models to patients has vast therapeutic potential, and remains a field of intense research.

  5. Auger electron spectroscopy as a tool for measuring intramolecular charges of adsorbed molecules

    NASA Astrophysics Data System (ADS)

    Magkoev, T. T.

    A way for the determination of the values of intramolecular charges of adsorbed molecules of some binary dielectrics, based on Auger electron spectroscopy (AES), is proposed. These values can be obtained from the coverage dependences of the ratios of intensities of anion KL 23L 23 and KL 1L 1 Auger transitions, which are sensitive to the amount of charge at the 2p-orbitals. As an example, MgO adsorbed on Mo(110) is presented.

  6. Auger electron spectroscopy as a tool for measuring intramolecular charges of adsorbed molecules

    NASA Astrophysics Data System (ADS)

    Magkoev, T. T.

    1993-10-01

    A way for the determination of the values of intramolecular charges of adsorbed molecules of some binary dielectrics, based on Auger electron spectroscopy (AES), is proposed. These values can be obtained from the coverage dependences of the ratios of intensities of anion KL 23L 23 and KL 1L 1 Auger transitions, which are sensitive to the amount of charge at the 2p-orbitals. As an example, MgO adsorbed on Mo(110) is presented.

  7. Intrinsic Emittance Reduction of an Electron Beam from Metal Photocathodes

    SciTech Connect

    Hauri, C. P.; Ganter, R.; Le Pimpec, F.; Trisorio, A.; Ruchert, C.; Braun, H. H.

    2010-06-11

    Electron beams in modern linear accelerators are now becoming limited in brightness by the intrinsic emittance of the photocathode electron source. Therefore it becomes important for large scale facilities such as free electron lasers to reduce this fundamental limit. In this Letter we present measurements of the intrinsic emittance for different laser wavelength (from 261 to 282 nm) and for different photocathode materials such as Mo, Nb, Al, Cu. Values as low as 0.41{+-}0.03 mm{center_dot}mrad/mm laser spot size (rms) were measured for a copper photocathode illuminated with a 282 nm laser wavelength. The key element for emittance reduction is a uv laser system which allows adjustment of the laser photon energy to match the effective work function of the cathode material and to emit photoelectrons with a lower initial kinetic energy. The quantum efficiency over the explored wavelength range varies by less than a factor of 3.

  8. Field Emitter Magnetic Sensor with Steered Focused Electron Beam

    NASA Astrophysics Data System (ADS)

    Nicolaescu, Dan; Filip, Valeriu; Itoh, Junji

    2001-04-01

    A novel field emission magnetic sensor is proposed and its operation is theoretically analyzed. The sensor comprises a dual-gate wedge field emitter with a split gate having the double role of focusing and steering the electron beam. The electron beam deflection due to the Lorentz force is compensated by appropriate potentials applied to this electrode. The modeling results have been obtained using the Simion 3D 7.0 software package. The device has high sensitivity and its operation is not influenced by fluctuations in the emission current. Arrangements of mutually normal wedge emitters can be used for two-dimensional magnetic field sensing.

  9. Excellent oxidation endurance of boron nitride nanotube field electron emitters

    SciTech Connect

    Song, Yenan; Song, Yoon-Ho; Milne, William I.; Jin Lee, Cheol

    2014-04-21

    Boron nitride nanotubes (BNNTs) are considered as a promising cold electron emission material owing to their negative electron affinity. BNNT field emitters show excellent oxidation endurance after high temperature thermal annealing of 600 °C in air ambient. There is no damage to the BNNTs after thermal annealing at a temperature of 600 °C and also no degradation of field emission properties. The thermally annealed BNNTs exhibit a high maximum emission current density of 8.39 mA/cm{sup 2} and show very robust emission stability. The BNNTs can be a promising emitter material for field emission devices under harsh oxygen environments.

  10. Molecular-Frame Angular Distributions of Resonant CO:C(1s) Auger Electrons

    SciTech Connect

    Rolles, D.; Pesic, Z. D.; Dumitriu, I.; Pruemper, G.; Fukuzawa, H.; Liu, X.-J.; Ueda, K.; Fink, R. F.; Grum-Grzhimailo, A. N.; Berrah, N.

    2008-12-31

    The molecular-frame angular distributions of resonantly excited CO:C(1s){yields}{pi}* Auger electrons were determined using angle-resolved electron-ion coincidence spectroscopy in combination with a novel transformation procedure. Our new methodology yields full three-dimensional electron angular distributions with high energy resolution from the measurement of electrons at only two angles. The experimentally determined distributions are well reproduced by calculations performed in a simple one-center approximation, allowing an unambiguous identification of several overlapping Auger lines.

  11. Selective detection of angular-momentum-polarized Auger electrons by atomic stereography.

    PubMed

    Matsui, Fumihiko; Fujita, Masayoshi; Ohta, Takuya; Maejima, Naoyuki; Matsui, Hirosuke; Nishikawa, Hiroaki; Matsushita, Tomohiro; Daimon, Hiroshi

    2015-01-01

    When a core level is excited by circularly polarized light, the angular momentum of light is transferred to the emitted photoelectron, which can be confirmed by the parallax shift of the forward focusing peak (FFP) direction in a stereograph of atomic arrangement. No angular momentum has been believed to be transferred to normal Auger electrons resulting from the decay process filling core hole after photoelectron ejection. We succeeded in detecting a non-negligible circular dichroism contrast in a normal Auger electron diffraction from a nonmagnetic Cu(001) surface far off from the absorption threshold. Moreover, we detected angular-momentum-polarized Cu L(3)M(4,5)M(4,5) Auger electrons at the L(3) absorption threshold, where the excited core electron is trapped at the conduction band. From the kinetic energy dependence of the Auger electron FFP parallax shift, we found that the angular momentum is transferred to the Auger electron most effectively in the case of the (1)S(0) two-hole creation. PMID:25615477

  12. Angular Correlation of Electrons Emitted by Double Auger Decay of K-Shell Ionized Neon

    NASA Astrophysics Data System (ADS)

    Jones, Matthew Philip

    2011-12-01

    We have investigated in detail the 4-body continuum state produced when core-ionized neon undergoes Double-Auger (DA) decay, using COLd Target Recoil Ion Momentum Spectroscopy (COLTRIMS ). We conducted the experiment at the Lawrence Berkeley National Laboratory's Advanced Light Source (LBNL-ALS) beamline 11.0.2. The synchrotron operated in 2-bunch mode and outputted an elliptically polarized, pulsed photon beam (hn=872.9eV), sufficient to K-shell ionize neon just above threshold. Our analysis supports research showing that Auger electrons tend to share energy asymmetrically. We qualitatively compared this result to Photo-Double Ionization (PDI) of helium. Further, we confirm research that shows how Auger electrons that share energy symmetrically can be modeled by the elastic-like knock-out process plus Post-Collision Interaction ( PCI) effects. New observations include the angular correlation between the photo-electron and each respective Auger electron, for specific ranges of energy sharing. We identify a broad feature in the asymmetric case that shows a level of interaction between electrons that until recently, has disagreed with theory. Additionally, we consider the angular correlation between the photo-electron and the momentum sum of the Auger electrons. We observe that the angular correlation between this sum and the photo-electron in the highly asymmetric case is nearly identical to the correlation between just the fast-Auger and the photo-electron - as expected. In the case of symmetric energy sharing, the sum momentum vector appears to be isotropic, particularly for small angles of interaction. Finally, we acknowledge two novel methods of calibration. The first, uses well known line-energies to calibrate the spectrometer. These lines correspond to the decay channels of core-excited neon, Ne(1 s-13p). The second, describes a method to statistically weight list-mode data in order to calibrate it to well known physical features (e.g., isotropic distributions).

  13. Time of flight spectrometer for background-free positron annihilation induced Auger electron spectroscopy.

    PubMed

    Mukherjee, S; Shastry, K; Anto, C V; Joglekar, P V; Nadesalingam, M P; Xie, S; Jiang, N; Weiss, A H

    2016-03-01

    We describe a novel spectrometer designed for positron annihilation induced Auger electron spectroscopy employing a time-of-flight spectrometer. The spectrometer's new configuration enables us to implant monoenergetic positrons with kinetic energies as low as 1.5 eV on the sample while simultaneously allowing for the detection of electrons emitted from the sample surface at kinetic energies ranging from ∼500 eV to 0 eV. The spectrometer's unique characteristics made it possible to perform (a) first experiments demonstrating the direct transition of a positron from an unbound scattering state to a bound surface state and (b) the first experiments demonstrating that Auger electron spectra can be obtained down to 0 eV without the beam induced secondary electron background obscuring the low energy part of the spectra. Data are presented which show alternative means of estimating positron surface state binding energy and background-free Auger spectra. PMID:27036826

  14. Time of flight spectrometer for background-free positron annihilation induced Auger electron spectroscopy

    NASA Astrophysics Data System (ADS)

    Mukherjee, S.; Shastry, K.; Anto, C. V.; Joglekar, P. V.; Nadesalingam, M. P.; Xie, S.; Jiang, N.; Weiss, A. H.

    2016-03-01

    We describe a novel spectrometer designed for positron annihilation induced Auger electron spectroscopy employing a time-of-flight spectrometer. The spectrometer's new configuration enables us to implant monoenergetic positrons with kinetic energies as low as 1.5 eV on the sample while simultaneously allowing for the detection of electrons emitted from the sample surface at kinetic energies ranging from ˜500 eV to 0 eV. The spectrometer's unique characteristics made it possible to perform (a) first experiments demonstrating the direct transition of a positron from an unbound scattering state to a bound surface state and (b) the first experiments demonstrating that Auger electron spectra can be obtained down to 0 eV without the beam induced secondary electron background obscuring the low energy part of the spectra. Data are presented which show alternative means of estimating positron surface state binding energy and background-free Auger spectra.

  15. Angle-resolved Auger electron spectra induced by neon ion impact on aluminum

    NASA Technical Reports Server (NTRS)

    Pepper, S. V.; Aron, P. R.

    1986-01-01

    Auger electron emission from aluminum bombarded with 1 to 5 keV neon ions was studied by angle-resolved electron spectroscopy. The position and shape of the spectral features depended on the incident ion energy, angle of ion incidence, and electron take-off angle with respect to the aluminum surface. These spectral dependencies were interpreted in terms of the Doppler shift given to the Auger electron velocity by the excited atom ejected into the vacuum. For oblique ion incidence it is concluded that a flux of high energy atoms are ejected in a direction close to the projection of the ion beam on the target surface. In addition, a new spectral feature was found and identified as due to Auger emission from excited neon in the aluminum matrix.

  16. Evaluating {sup 99m}Tc Auger electrons for targeted tumor radiotherapy by computational methods

    SciTech Connect

    Tavares, Adriana Alexandre S.; Tavares, Joao Manuel R. S.

    2010-07-15

    Purpose: Technetium-99m ({sup 99m}Tc) has been widely used as an imaging agent but only recently has been considered for therapeutic applications. This study aims to analyze the potential use of {sup 99m}Tc Auger electrons for targeted tumor radiotherapy by evaluating the DNA damage and its probability of correct repair and by studying the cellular kinetics, following {sup 99m}Tc Auger electron irradiation in comparison to iodine-131 ({sup 131}I) beta minus particles and astatine-211 ({sup 211}At) alpha particle irradiation. Methods: Computational models were used to estimate the yield of DNA damage (fast Monte Carlo damage algorithm), the probability of correct repair (Monte Carlo excision repair algorithm), and cell kinetic effects (virtual cell radiobiology algorithm) after irradiation with the selected particles. Results: The results obtained with the algorithms used suggested that {sup 99m}Tc CKMMX (all M-shell Coster-Kroning--CK--and super-CK transitions) electrons and Auger MXY (all M-shell Auger transitions) have a therapeutic potential comparable to high linear energy transfer {sup 211}At alpha particles and higher than {sup 131}I beta minus particles. All the other {sup 99m}Tc electrons had a therapeutic potential similar to {sup 131}I beta minus particles. Conclusions: {sup 99m}Tc CKMMX electrons and Auger MXY presented a higher probability to induce apoptosis than {sup 131}I beta minus particles and a probability similar to {sup 211}At alpha particles. Based on the results here, {sup 99m}Tc CKMMX electrons and Auger MXY are useful electrons for targeted tumor radiotherapy.

  17. Differential auger spectrometry

    DOEpatents

    Strongin, Myron; Varma, Matesh Narayan; Anne, Joshi

    1976-06-22

    Differential Auger spectroscopy method for increasing the sensitivity of micro-Auger spectroanalysis of the surfaces of dilute alloys, by alternately periodically switching an electron beam back and forth between an impurity free reference sample and a test sample containing a trace impurity. The Auger electrons from the samples produce representative Auger spectrum signals which cancel to produce an Auger test sample signal corresponding to the amount of the impurity in the test samples.

  18. Validation of 64Cu-ATSM damaging DNA via high-LET Auger electron emission.

    PubMed

    McMillan, Dayton D; Maeda, Junko; Bell, Justin J; Genet, Matthew D; Phoonswadi, Garrett; Mann, Kelly A; Kraft, Susan L; Kitamura, Hisashi; Fujimori, Akira; Yoshii, Yukie; Furukawa, Takako; Fujibayashi, Yasuhisa; Kato, Takamitsu A

    2015-09-01

    Radioactive copper (II) (diacetyl-bis N4-methylthiosemicarbazone) (Cu-ATSM) isotopes were originally developed for the imaging of hypoxia in tumors. Because the decay of a (64)Cu atom is emitting not only positrons but also Auger electrons, this radionuclide has great potential as a theranostic agent. However, the success of (64)Cu-ATSM internal radiation therapy would depend on the contribution of Auger electrons to tumor cell killing. Therefore, we designed a cell culture system to define the contributions to cell death from Auger electrons to support or refute our hypothesis that the majority of cell death from (64)Cu-ATSM is a result of high-LET Auger electrons and not positrons or other low-LET radiation. Chinese hamster ovary (CHO) wild type and DNA repair-deficient xrs5 cells were exposed to (64)Cu-ATSM during hypoxic conditions. Surviving fractions were compared with those surviving gamma-radiation, low-LET hadron radiation, and high-LET heavy ion exposure. The ratio of the D(10) values (doses required to achieve 10% cell survival) between CHO wild type and xrs5 cells suggested that (64)Cu-ATSM toxicity is similar to that of high-LET Carbon ion radiation (70 keV/μm). γH2AX foci assays confirmed DNA double-strand breaks and cluster damage by high-LET Auger electrons from (64)Cu decay, and complex types of chromosomal aberrations typical of high-LET radiation were observed after (64)Cu-ATSM exposure. The majority of cell death was caused by high-LET radiation. This work provides strong evidence that (64)Cu-ATSM damages DNA via high-LET Auger electrons, supporting further study and consideration of (64)Cu-ATSM as a cancer treatment modality for hypoxic tumors. PMID:26251463

  19. Validation of 64Cu-ATSM damaging DNA via high-LET Auger electron emission

    PubMed Central

    McMillan, Dayton D.; Maeda, Junko; Bell, Justin J.; Genet, Matthew D.; Phoonswadi, Garrett; Mann, Kelly A.; Kraft, Susan L.; Kitamura, Hisashi; Fujimori, Akira; Yoshii, Yukie; Furukawa, Takako; Fujibayashi, Yasuhisa; Kato, Takamitsu A.

    2015-01-01

    Radioactive copper (II) (diacetyl-bis N4-methylthiosemicarbazone) (Cu-ATSM) isotopes were originally developed for the imaging of hypoxia in tumors. Because the decay of a 64Cu atom is emitting not only positrons but also Auger electrons, this radionuclide has great potential as a theranostic agent. However, the success of 64Cu-ATSM internal radiation therapy would depend on the contribution of Auger electrons to tumor cell killing. Therefore, we designed a cell culture system to define the contributions to cell death from Auger electrons to support or refute our hypothesis that the majority of cell death from 64Cu-ATSM is a result of high-LET Auger electrons and not positrons or other low-LET radiation. Chinese hamster ovary (CHO) wild type and DNA repair–deficient xrs5 cells were exposed to 64Cu-ATSM during hypoxic conditions. Surviving fractions were compared with those surviving gamma-radiation, low-LET hadron radiation, and high-LET heavy ion exposure. The ratio of the D10 values (doses required to achieve 10% cell survival) between CHO wild type and xrs5 cells suggested that 64Cu-ATSM toxicity is similar to that of high-LET Carbon ion radiation (70 keV/μm). γH2AX foci assays confirmed DNA double-strand breaks and cluster damage by high-LET Auger electrons from 64Cu decay, and complex types of chromosomal aberrations typical of high-LET radiation were observed after 64Cu-ATSM exposure. The majority of cell death was caused by high-LET radiation. This work provides strong evidence that 64Cu-ATSM damages DNA via high-LET Auger electrons, supporting further study and consideration of 64Cu-ATSM as a cancer treatment modality for hypoxic tumors. PMID:26251463

  20. Novel time-of-flight spectrometer for the analysis of positron annihilation induced Auger electrons

    SciTech Connect

    Hugenschmidt, Christoph; Legl, Stefan

    2006-10-15

    Positron annihilation induced Auger-electron spectroscopy (PAES) has several advantages over conventional Auger-electron spectroscopy such as extremely high surface sensitivity and outstanding signal-to-noise ratio at the Auger-transition energy. In order to benefit from these prominent features a low-energy positron beam of high intensity is required for surface sensitive PAES studies. In addition, an electron energy analyzer is required, which efficiently detects the Auger electrons with acceptable energy resolution. For this reason a novel time-of-flight (TOF) spectrometer has been developed at the intense positron source NEPOMUC that allows PAES studies within short measurement time. This TOF-PAES setup combines a trochoidal filter and a flight tube in a Faraday cage in order to achieve an improved energy resolution of about 1 eV at high electron energies up to E{approx_equal}1000 eV. The electron flight time is the time between the annihilation radiation at the sample and when the electron hits a microchannel plate detector at the end of the flight tube.

  1. Science and applications of low-emittance electron beams

    SciTech Connect

    van Bibber, K

    2000-08-20

    The capability of making very low-emittance electron beams of temporally short, high charge bunches has opened up exciting new possibilities in basic and applied science. Two notable applications are high energy electron-positron linear colliders for particle physics, and fourth-generation light sources consisting of linac-driven Free-Electron Lasers (FEL), both of which represent significant programmatic potential for the Laboratory in the future. The technologies contributing to low-emittance electron beams and their applications, namely precision fabrication, ultra-short pulse lasers, and RF photocathode injectors, are all areas of Lab expertise, and the work carried out under this LDRD project further expanded our core-competency in advanced concept accelerators. Furthermore, high energy accelerators have become a cornerstone of the SBSS program, as illustrated by the recent development of proton radiography as a prime technology candidate for the Advanced Hydrotest Facility (AHF), which enhanced the significance of this project all the more. This was a one-year project to both advance the technology of, and participate in the science enabled by very low-emittance electron beams. The work centered around the two themes above, namely electron-positron linear colliders, and the new fourth-generation light sources. This work built upon previous LDRD investments, and was intended to emphasize accelerator physics experiments.

  2. Electron Cloud at Low Emittance in CesrTA

    SciTech Connect

    Palmer, Mark; Alexander, James; Billing, Michael; Calvey, Joseph; Conolly, Christopher; Crittenden, James; Dobbins, John; Dugan, Gerald; Eggert, Nicholas; Fontes, Ernest; Forster, Michael; Gallagher, Richard; Gray, Steven; Greenwald, Shlomo; Hartill, Donald; Hopkins, Walter; Kreinick, David; Kreis, Benjamin; Leong, Zhidong; Li, Yulin; Liu, Xianghong; /more authors..

    2012-07-06

    The Cornell Electron Storage Ring (CESR) has been reconfigured as a test accelerator (CesrTA) for a program of electron cloud (EC) research at ultra low emittance. The instrumentation in the ring has been upgraded with local diagnostics for measurement of cloud density and with improved beam diagnostics for the characterization of both the low emittance performance and the beam dynamics of high intensity bunch trains interacting with the cloud. A range of EC mitigation methods have been deployed and tested and their effectiveness is discussed. Measurements of the electron cloud's effect on the beam under a range of conditions are discussed along with the simulations being used to quantitatively understand these results.

  3. PHOTOELECTRON AND AUGER ELECTRON ASYMMETRIES: ALIGNMENT OF Xe{sup +}({sup 2}D{sub 5/2}) BY PHOTOIONIZATION

    SciTech Connect

    Southworth, S. H.; Kobrin, P. H.; Truesdale, C. M.; Lindle, D.; Owaki, S.; Shirley, D. A.

    1980-12-01

    Angular distributions of photoelectrons from the Xe 4d subshell, and N{sub 4,5}oo Auger electrons, have been measured using synchrotron radiation. The 4d asymmetry parameter exhibits strong oscillations with energy, in agreement with several theoretical calculations. The Auger electrons show large asymmetries due to alignment of Xe{sup +} by photoionization.

  4. Observation of suppressed Auger mechanism in type-I quantum well structures with delocalized electron-hole wavefunctions

    SciTech Connect

    Hassani Nia, Iman; Fathipour, Vala; Mohseni, Hooman

    2015-08-15

    We report the first observation of non-threshold Auger mechanism for a quantum well structure with Type-I band alignment. Excitation-dependent photoluminescence measurements were used to extract the Auger recombination coefficients from 77 K up to room temperature. The results verify the role of interface mediated momentum exchange as well as suppression of Auger recombination for delocalized electron-hole wavefunctions.

  5. Low emittance injector design for free electron lasers

    NASA Astrophysics Data System (ADS)

    Bettoni, S.; Pedrozzi, M.; Reiche, S.

    2015-12-01

    Several parameters determine the performance of free electron lasers: the slice and the projected emittance, the slice energy spread, and the peak current are the most crucial ones. The peak current is essentially obtained by magnetic compression stages along the machine or occasionally assisted by velocity bunching at low energy. The minimum emittance and the alignment of the slices along the bunch are mainly determined in the low energy part of the accelerator (injector). Variations at the per-mille level of several parameters in this section of the machine strongly influence these quantities with highly nonlinear dynamic. We developed a numerical tool to perform the optimization of the injector. We applied this code to optimize the SwissFEL injector, assuming different gun designs, initial bunch lengths and intrinsic emittances. We obtained an emittance along the bunch of 0.14 mm mrad and around 0.08 mm mrad for the maximum and the minimum SwissFEL charges (200 and 10 pC, respectively). We applied the same tool to a running injector, where we automatized the optimization of the machine.

  6. Measuring the emittance of the DARHT-II electron beam

    NASA Astrophysics Data System (ADS)

    Ekdahl, Carl; Bartsch, Richard; Custer, Dan; Ridlon, Rae; Rose, Evan; Eylon, Shmuel; Broste, William; Johnson, Jefferey

    2001-10-01

    The DARHT-II linear induction accelerator (LIA) is being built for radiography of large-scale, explosively-driven hydrodynamics experiments. When fully operational, DARHT-II will have an electron beam current of 2-kA and a beam energy of 18 MeV. The two-microsecond beam pulse will be chopped into four short pulses for time resolution of hydrodynamic motion. A small radiographic spot size is a requirement for DARHT-II. The DARHT-II LIA design emphasizes low beam emittance to reduce the spot size. Measuring the emittance of a high-power, 2-micro-sec beam presents special challenges, and we will discuss two different approaches. In the first technique a fast solenoid is employed to focus the beam onto an imaging screen in 120 ns to prevent overheating of the screen and consequent beam disruption by evolved gas/plasma/ions. The fast-focus coil must produce a 1 kG field over an effective length of 50 cm. The design and testing of this coil and its pulsed-power driver will be presented. The second technique uses non-invasive diamagnetic loop measurements, from which the beam radius can be inferred, at several locations. A beam envelope code is then used to find the most likely emittance that fits the data. In this presentation these methods are compared with respect to expected uncertainties, and the resulting accuracy of emittance determination.

  7. Communication: Formation of slow electrons in the Auger decay of core-ionized water molecules

    NASA Astrophysics Data System (ADS)

    Hikosaka, Y.; Yamamoto, K.; Nakano, M.; Odagiri, T.; Soejima, K.; Suzuki, I. H.; Lablanquie, P.; Penent, F.; Ito, K.

    2012-11-01

    Double Auger decay of O1s-1 and its satellite states in H2O has been studied with a multi-electron coincidence method, and a process leading to autoionizing O* fragments has been revealed. The breaking of the two O-H bonds producing the autoionizing O* fragments occurs for highly excited H2O2+ populated by the initial Auger decay. The O* fragments are more favorably produced in the decay from the satellite states, resulting from the larger population of highly excited H2O2+ states inheriting the valence excitation in the initial state.

  8. Communication: Formation of slow electrons in the Auger decay of core-ionized water molecules.

    PubMed

    Hikosaka, Y; Yamamoto, K; Nakano, M; Odagiri, T; Soejima, K; Suzuki, I H; Lablanquie, P; Penent, F; Ito, K

    2012-11-21

    Double Auger decay of O1s(-1) and its satellite states in H(2)O has been studied with a multi-electron coincidence method, and a process leading to autoionizing O* fragments has been revealed. The breaking of the two O-H bonds producing the autoionizing O* fragments occurs for highly excited H(2)O(2+) populated by the initial Auger decay. The O* fragments are more favorably produced in the decay from the satellite states, resulting from the larger population of highly excited H(2)O(2+) states inheriting the valence excitation in the initial state. PMID:23181286

  9. Production of Ne Auger electrons by Ne/+/ bombardment of Mg and Al surfaces

    NASA Technical Reports Server (NTRS)

    Ferrante, J.; Pepper, S. V.

    1976-01-01

    A description is given of experiments which provide evidence for the production of an inner shell vacancy in the Ne by the asymmetric Ne-Mg and Ne-Al collision. In addition, autoionization states of neutral Ne have been observed. These states are to be distinguished from the more usual case in Auger electron spectroscopy of de-excitation of an ion with a core vacancy. The experiments involved the bombardment of Mg and Al surfaces with Ne(+) ions. A LEED-Auger system equipped with an ion gun and a four-grid retarding potential analyzer operated in the usual dN(E)/dE mode was used.

  10. A new technique for Auger analysis of surface species subject to electron-induced desorption.

    NASA Technical Reports Server (NTRS)

    Pepper, S. V.

    1973-01-01

    A method is presented to observe surface species subject to electron-induced desorption by Auger electron spectroscopy. The surface to be examined is moved under the electron beam at constant velocity, establishing a time-independent condition and eliminating the time response of the electron spectrometer as a limiting factor. The dependence of the Auger signal on the sample velocity, incident electron current, beam diameter, and desorption cross section is analyzed. It is shown that it is advantageous to analyze the moving sample with a high beam current, in contrast to the usual practice of using a low beam current to minimize desorption from a stationary sample. The method is illustrated by the analysis of a friction transfer film of PTFE, in which the fluorine is removed by electron-induced desorption. The method is relevant to surface studies in the field of lubrication and catalysis.

  11. Angular distribution of molecular K-shell Auger electrons: Spectroscopy of photoabsorption anisotropy

    SciTech Connect

    Dill, D.; Swanson, J.R.; Wallace, S.; Dehmer, J.L.

    1980-10-27

    The angular distribution of Auger electrons emitted in the decay of molecular K-shell vacancies created by photoabsorption is predicted to be a direct probe of the anisotropy of molecular photoabsorption. The sigma..--> pi.. discrete absorption of the sigma..-->..sigma f-wave shape resonance in N/sub 2/ and CO are given as examples.

  12. Fluorine Auger-electron production in collisions of H+ and Li2+ with fluorocarbon targets

    NASA Astrophysics Data System (ADS)

    Shinpaugh, J. L.; Toburen, L. H.; Justiniano, E. L. B.

    1999-12-01

    Relative and absolute cross sections are presented for fluorine KLL Auger-electron production in collisions of 2.0-MeV H+ and 0.5-MeV/amu Li2+ with various fluorocarbon targets. Auger yields were measured for molecular targets of CH3F, CH2F2, C2H2F2, CHF3, CF4, C2F6, and C4F8. The fluorine Auger cross sections for these collision systems were found to be independent of the chemical environment, i.e., the atomic cross sections were found to obey additivity for these molecules. This is in contrast to recently reported fluorine K-shell ionization cross sections found for He+ impact on fluorocarbon targets, where the atomic cross sections were found to differ by up to a factor of 3.

  13. Potential use of radiolabeled glucuronide prodrugs with auger and/or alpha emitters in combined chemo- and radio-therapy of cancer.

    PubMed

    Unak, T

    2000-07-01

    Nowadays, the scientists from different disciplines have focused their attentions to new anticancer drug design for cancer chemotherapy. An effective anticancer drug should ensure the selective drug incorporation into the targeted tumor cells without principally incorporation into the normal cells. So, the targeted tumor cells can selectively be damaged by the cytotoxic effectiveness of the drug. The basic principles of drug design have involved "prodrug" concept, which means a chemical agent which is not itself active as an anticancer drug, but it can be transformed to an active form after its administration. Prodrugs can finally be activated onto the tumor cells by some kind of enzymes. In this context, the activation of glucuronide prodrugs by b-glucuronidase have a large potential applications in cancer chemotherapy. On the other hand, combined chemo- and radio-therapy of cancer (CCRTC) concept aims to combine the cytotoxicity of an aglycone with the radiotoxicity of an appropriate radionuclide on the same prodrug. So, the cytotoxic and radiotoxic effectiveness' will be able to be concentrated into the same tumor cell to increase obviously its damage. For experimental realization of this concept an effective anticancer prodrug should be radiolabeled with a radionuclide having high level of radiotoxic effectiveness such as Auger and/or alpha-emitter radionuclides. Iodine-125 and astatine-211 are very interesting radionuclides as being effective Auger and/or alpha-emitters. Briefly, the glucuronide prodrugs radiolabeled with iodine-125 or astatine-211 promise to be designed very effective anticancer agents in the future applications of cancer chemotherapy. PMID:10903386

  14. Low Emittance Guns for the ILC Polarized Electron Beam

    SciTech Connect

    Clendenin, J.E.; Brachmann, A.; Ioakeimidi, K.; Kirby, R.E.; Maruyama, T.; Miller, R.H.; Wang, J.W.; Zhou, F.; /SLAC

    2006-12-01

    Polarized electron beams generated by DC guns are routinely available at several accelerators including JLAB, Mainz and SLAC. These guns operate with a cathode bias on the order of -100 kV. To minimize space charge effects, relatively long bunches are generated at the gun and then compressed longitudinally external to the gun just before and during initial acceleration. For linear colliders, this compression is accomplished using a combination of rf bunchers. For the basic design of the International Linear Collider (ILC), a 120 kV DC photocathode gun is used to produce a series of nanosecond bunches that are each compressed by two sub-harmonic bunchers (SHBs) followed by an L-band buncher and capture section. The longitudinal bunching process results in a significantly higher emittance than produced by the gun alone. While high-energy experiments using polarized beams are not generally sensitive to the source emittance, there are several benefits to a lower source emittance including a simpler more efficient injector system and a lower radiation load during transport especially at bends as at the damping ring. For the ILC, the SHBs could be eliminated if the voltage of the gun is raised sufficiently. Simulations using the General Particle Tracer (GPT) package indicate that a cathode bias voltage of {ge}200 kV should allow both SHBs to be operated at 433 or even 650 MHz, while {ge}500 kV would be required to eliminate the SHBs altogether. Simulations can be used to determine the minimum emittance possible if the injector is designed for a given increased voltage. A possible alternative to the DC gun is an rf gun. Emittance compensation, routinely used with rf guns, is discussed for higher-voltage DC guns.

  15. Low Emittance Guns for the ILC Polarized Electron Beam

    SciTech Connect

    Clendenin, J. E.; Brachmann, A.; Ioakeimidi, K.; Kirby, R. E.; Maruyama, T.; Miller, R. H.; Wang, J. W.; Zhou, F.

    2007-06-13

    Polarized electron beams generated by DC guns are routinely available at several accelerators including JLAB, Mainz and SLAC. These guns operate with a cathode bias on the order of -100 kV. To minimize space charge effects, relatively long bunches are generated at the gun and then compressed longitudinally external to the gun just before and during initial acceleration. For linear colliders, this compression is accomplished using a combination of rf bunchers. For the basic design of the International Linear Collider (ILC), a 120 kV DC photocathode gun is used to produce a series of nanosecond bunches that are each compressed by two sub-harmonic bunchers (SHBs) followed by an L-band buncher and capture section. The longitudinal bunching process results in a significantly higher emittance than produced by the gun alone. While high-energy experiments using polarized beams are not generally sensitive to the source emittance, there are several benefits to a lower source emittance including a simpler more efficient injector system and a lower radiation load during transport especially at bends as at the damping ring. For the ILC, the SHBs could be eliminated if the voltage of the gun is raised sufficiently. Simulations using the General Particle Tracer (GPT) package indicate that a cathode bias voltage of {>=}200 kV should allow both SHBs to be operated at 433 or even 650 MHz, while {>=}500 kV would be required to eliminate the SHBs altogether. Simulations can be used to determine the minimum emittance possible if the injector is designed for a given increased voltage. A possible alternative to the DC gun is an rf gun. Emittance compensation, routinely used with rf guns, is discussed for higher-voltage DC guns.

  16. Depth-selective X-ray absorption spectroscopy by detection of energy-loss Auger electrons

    NASA Astrophysics Data System (ADS)

    Isomura, Noritake; Soejima, Narumasa; Iwasaki, Shiro; Nomoto, Toyokazu; Murai, Takaaki; Kimoto, Yasuji

    2015-11-01

    A unique X-ray absorption spectroscopy (XAS) method is proposed for depth profiling of chemical states in material surfaces. Partial electron yield mode detecting energy-loss Auger electrons, called the inelastic electron yield (IEY) mode, enables a variation in the probe depth. As an example, Si K-edge XAS spectra for a well-defined multilayer sample (Si3N4/SiO2/Si) have been investigated using this method at various kinetic energies. We found that the peaks assigned to the layers from the top layer to the substrate appeared in the spectra in the order of increasing energy loss relative to the Auger electrons. Thus, the probe depth can be changed by the selection of the kinetic energy of the energy loss electrons in IEY-XAS.

  17. Auger electron spectroscopy of super-doped Si:Mn thin films

    NASA Astrophysics Data System (ADS)

    Abe, S.; Nakasima, Y.; Okubo, S.; Nakayama, H.; Nishino, T.; Yanagi, H.; Ohta, H.; Iida, S.

    1999-04-01

    Thin films of Si heavily doped with Mn impurities at nonequilibrium doping levels have been successfully prepared by Laser-Ablation MBE. The electronic structure of Mn-doped Si thin films have been investigated by Auger Valence Electron Spectroscopy (AVES). The peak positions of Mn[3p,V,V] (V=3d) Auger spectra of Si:Mn thin films were located at the higher energy region than those of pure Mn and Mn 5Si 3 compound. For the Si:Mn thin film grown on SiO 2/Si(001) substrate, the new Auger peak was observed around 50 eV. The changes of the line shape were observed in Mn[L,M,M] (L=2s,2p; M=3s,3p,3d) Auger spectra of Si:Mn thin films compared with those of pure Mn and Mn 5Si 3 compounds. In the Mn[2s,M,V] (M=3s,3p,V=3d) spectra for Si:Mn thin films, the new peaks were appeared around 700 eV. These new peaks were considered to arise from the new split of the 3d electron states due to the formation of the Mn-Si bonds in Si:Mn thin films.

  18. A retractable electron emitter for the creation of unperturbed pure electron plasmas

    NASA Astrophysics Data System (ADS)

    Berkery, John W.; Pedersen, Thomas Sunn; Sampedro, Luis

    2007-01-01

    A retractable electron emitter has been constructed for the creation of unperturbed pure electron plasmas on magnetic surfaces in the Columbia Non-neutral Torus stellarator. The previous method of electron emission using emitters mounted on stationary rods limited the confinement time to 20 ms. A pneumatically driven system that can retract from the magnetic axis to the last closed flux surface in less than 20 ms while filling the surfaces with electrons was designed. The motion of the retractable emitter was modeled with a system of dynamical equations. The measured position versus time of the emitter agrees well with the model and the fastest axis-to-edge retraction was measured to be 20 ms with 40 psig helium gas driving the pneumatic piston.

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

    NASA Technical Reports Server (NTRS)

    Omidvar, K.

    1977-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Omidvar, K.

    1977-01-01

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

  1. ROLE OF DIAMOND SECONDARY EMITTERS IN HIGH BRIGHTNESS ELECTRON SOURCES.

    SciTech Connect

    RAO, T.; BEN-ZVI, I.; BURRILL, A.; CHANG, X.; GRIMES, J.; RANK, J.; SEGALOV, Z.; SMEDLEY, J.

    2005-09-20

    In this paper we explore the possibility of using diamond secondary emitter in a high average current electron injector to amplify the current from the photocathode and to isolate the cathode and the injector from each other to increase the life time of the cathode and preserve the performance of the injector. Secondary electron yield of 225 and current density of 0.8 a/cm{sup 2} have been measured in the transmission mode from type 2 a natural diamond. Although the diamond will be heated during normal operation in the injector, calculations indicate that by cryogenically cooling the diamond, the temperature gradient along the diamond can be maintained within the acceptable range. The electron energy and temporal distributions are expected to be narrow from this device resulting in high brightness beams. Plans are underway to measure the SEY in emission mode, fabricate photocathode-diamond capsule and test diamond and capsule in superconducting RF injector.

  2. Electron gun using carbon-nanofiber field emitter

    NASA Astrophysics Data System (ADS)

    Sakai, Y.; Haga, A.; Sugita, S.; Kita, S.; Tanaka, S.-I.; Okuyama, F.; Kobayashi, N.

    2007-01-01

    An electron gun constructed using carbon-nanofiber (CNF) emitters and an electrostatic Einzel lens system has been characterized for the development of a high-resolution x-ray source. The CNFs used were grown on tungsten and palladium tips by plasma-enhanced chemical-vapor deposition. Electron beams with the energies of 10electron beam extracted from the CNFs was estimated to be D <50μm in diameter. Superior performance was realized by using CNFs with larger fiber radii (100-500nm) grown sparsely on the metal tips, which were installed in a holder at the short length L =0.5mm.

  3. Electron gun using carbon-nanofiber field emitter

    SciTech Connect

    Sakai, Y.; Haga, A.; Sugita, S.; Kita, S.; Tanaka, S.-I.; Okuyama, F.; Kobayashi, N.

    2007-01-15

    An electron gun constructed using carbon-nanofiber (CNF) emitters and an electrostatic Einzel lens system has been characterized for the development of a high-resolution x-ray source. The CNFs used were grown on tungsten and palladium tips by plasma-enhanced chemical-vapor deposition. Electron beams with the energies of 10electron beam extracted from the CNFs was estimated to be D<50 {mu}m in diameter. Superior performance was realized by using CNFs with larger fiber radii (100-500 nm) grown sparsely on the metal tips, which were installed in a holder at the short length L=0.5 mm.

  4. Receptor-DNA binding to target auger electrons for cancer therapy. Final report, August 1, 1993--January 31, 1997

    SciTech Connect

    DeSombre, E.R.

    1997-05-01

    The goal of this program was to investigate the principle of receptor-DNA binding as a means to target Auger electron radiation for cancer therapy, and thereby to evaluate the potential of non-covalent, high-affinity, Auger electron-emitting ligands binding to a DNA associated molecule, or DNA itself, for cancer therapy. These studies were intended to assess the ability of Auger-emitting estrogens to kill estrogen receptor-positive tumor cells, determine the mean lethal dose, and determine whether they could be effective in vitro and in vivo.

  5. A universal algorithm for calculating the backscattering factor in Auger-electron spectroscopy

    NASA Astrophysics Data System (ADS)

    Jablonski, A.; Powell, C. J.

    2007-02-01

    We describe a universal Monte Carlo algorithm that can be used for the efficient calculation of backscattering factors (BFs) for quantitative Auger-electron spectroscopy (AES). This algorithm makes use of the continuous slowing-down approximation and the electron stopping power instead of simulation of individual inelastic-scattering events. This approach is attractive because it can be applied to any material with an empirical formula for the stopping power, available data for differential elastic-scattering cross sections, and an empirical formula for inner-shell ionization cross sections. We report BFs for the Si KL 23L 23, Cu L 3M 45M 45, Ag M 5N 45N 45, and Au M 5N 67N 67 Auger transitions in the corresponding elemental solids. These BFs were calculated for normal incidence of the primary beam, primary energies from near threshold for ionization of the relevant core levels to 20 keV, and Auger-electron emission angles of 10°, 60°, and 80°. We found satisfactory agreement between these BFs and values obtained from a more accurate algorithm in which individual inelastic-scattering events were simulated. Percentage deviations between BFs from the two algorithms were <2% for Au, <5% for Ag, <7% for Cu, and <10% for Si for primary energies likely to be used in practical AES. These deviations arise mainly from our use of stopping powers from the empirical formula rather than more reliable values calculated from experimental optical data.

  6. Radiobiological Effects of Auger Electrons in the Decay of PLATINUM-195M.

    NASA Astrophysics Data System (ADS)

    Howell, Roger Wells

    The metastable radionuclide Pt-195m decays predominantly by internal conversion (IC) with a half-life of 4 days. The vacancies created in the inner atomic shells by the primary IC decay modes result in copious emission of low energy Auger electrons. The biological effects of these electrons, which have ranges of subcellular dimensions, are of interest to basic and applied radiation biophysics. Using radiolabeled platinum complexes which bind to DNA, one can examine the effect of Pt-195m Auger cascades close to the DNA. Trans -Pt-195m (trans-dichlorodiammineplatinum (II); specific activity 0.5 mCi/mg), a DNA-binding compound, has been synthesized and its effect on the survival of Chinese hamster V79 cells determined. The cellular uptake of Pt-195m reaches a plateau in 3-4 hours and varies nonlinearly with extracellular activity concentration. Following an 18 hour incubation, 75% of the cellular radioactivity is found in the cytoplasm, and 25% in the nucleus. About 42% of the activity in the nucleus is DNA-bound. The activity is eliminated from the cell, postincubation, with a 24 hour half-life. Cell survival data, when corrected for the chemical toxicity of the unlabeled trans-Pt, give a survival curve typical of densely ionizing radiation of high linear energy transfer such as alpha particles. The mean lethal cellular uptake of radioactivity is 0.032 +/- 0.003 pCi/cell at 37% survival. Theoretical calculations of the Pt-195m Auger electron spectrum using Monte Carlo methods indicate about 30 Auger electrons are expected per decay. Dosimetric considerations give a value of 4.8 for the relative biological effectiveness of Pt-195m compared to 250 kVp x-rays. Theoretical Monte Carlo calculations imply that the density of chemical species produced by Auger electrons in liquid water in the immediate vicinity of a Pt-195m decay site is comparable to the density along the track of a 4 MeV alpha particle. This explains qualitatively the efficacy of Pt-195m in causing

  7. A study of native oxides of beta-SiC using Auger electron spectroscopy

    NASA Technical Reports Server (NTRS)

    Chaudhry, M. Iqbal

    1989-01-01

    Thermal and anodic oxide films of beta-SiC are analyzed using Auger electron spectroscopy. Auger depth-composition profiles are obtained in order to determine the chemical composition of the oxide films. The position and shape of silicon spectral peaks are used to estimate the chemical bonding of the oxide constituents. It is found that the wet thermal oxide is almost stoichiometric but contains about 14 pct C. Dry oxide, on the other hand, has less than 3 pct C but is highly nonstoichiometric. The C content in the anodic oxide is 12 pct. Anodic oxide films, like dry-oxide films, are nonstoichiometric. A model of the SiC oxidation process is presented.

  8. Chemical state analysis of grain boundaries in ZnO varistors by Auger electron spectroscopy

    SciTech Connect

    Tanaka, Shigeru ); Akita, Chiyoshi ); Ohashi, Naoki ); Kawai, Jun ); Haneda, Hajime; Tanaka, Junzo )

    1993-07-01

    The chemical state of grain boundaries in Bi[sub 2]O[sub 3]-doped ZnO ceramics was investigated by Auger electron spectroscopy. The additive Bi was segregated into grain boundaries 2 to 3 nm thick, where oxygen deficiency occurred. Auger transitions KL[sub 2,3]L[sub 2,3] for oxygen at the grain boundaries were composed of three peaks whose relative intensities varied with the amount of the segregated Bi. Results calculated using a molecular orbital method suggested that the metal-oxygen bonding state in the grain boundary changed with increased amounts of Bi. The change of the bonding character was considered to be related to the formation of an interfacial state at the grain boundary causing nonlinear current-voltage characteristics. 16 refs., 9 figs.

  9. Techniques for the correction of topographical effects in scanning Auger electron microscopy

    NASA Technical Reports Server (NTRS)

    Prutton, M.; Larson, L. A.; Poppa, H.

    1983-01-01

    A number of ratioing methods for correcting Auger images and linescans for topographical contrast are tested using anisotropically etched silicon substrates covered with Au or Ag. Thirteen well-defined angles of incidence are present on each polyhedron produced on the Si by this etching. If N1 electrons are counted at the energy of an Auger peak and N2 are counted in the background above the peak, then N1, N1 - N2, (N1 - N2)/(N1 + N2) are measured and compared as methods of eliminating topographical contrast. The latter method gives the best compensation but can be further improved by using a measurement of the sample absorption current. Various other improvements are discussed.

  10. Reduced Auger recombination in single CdSe/CdS nanorods by one-dimensional electron delocalization.

    PubMed

    Rabouw, Freddy T; Lunnemann, Per; van Dijk-Moes, Relinde J A; Frimmer, Martin; Pietra, Francesca; Koenderink, A Femius; Vanmaekelbergh, Daniël

    2013-10-01

    Progress to reduce nonradiative Auger decay in colloidal nanocrystals has recently been made by growing thick shells. However, the physics of Auger suppression is not yet fully understood. Here, we examine the dynamics and spectral characteristics of single CdSe-dot-in-CdS-rod nanocrystals. These exhibit blinking due to charging/discharging, as well as trap-related blinking. We show that one-dimensional electron delocalization into the rod-shaped shell can be as effective as a thick spherical shell at reducing Auger recombination of the negative trion state. PMID:24010869

  11. Sliding of poly(vinyl chloride) on metals studied by Auger electron spectroscopy

    NASA Technical Reports Server (NTRS)

    Pepper, S. V.

    1974-01-01

    The sliding of polyvinyl chloride on nickel, iron and S-Monel has been studied by Auger electron spectroscopy. Polymer was not transferred to the metals, rather shear appeared to take place at the interface. The metal was progressively chlorinated as the polymer made multiple passes on the surface. The thickness of this chlorine film was the order of one atomic layer. Electron-induced desorption studies indicate that the chlorine is chemisorbed to the metal. These results are interpreted as evidence for mechanically induced and/or thermal degradation of the polymer during sliding. Degradation products of HCl and Cl2 which chemisorb to the metal are evolved near the interface.

  12. High-current lanthanum-hexaboride electron emitter for a quasi-stationary arc plasma generator

    SciTech Connect

    Davydenko, V. I. Ivanov, A. A. Shul’zhenko, G. I.

    2015-11-15

    A high-current electron emitter on the basis of lanthanum hexaboride is developed for quasi-stationary arc plasma generators of ion sources. The emitter consists of a set of LaB{sub 6} washers interleaved with washers made of thermally extended graphite. The emitter is heated by the current flowing through the graphite washers. The thermal regime of emitter operation during plasma generation is considered. The emitter has been successfully used in the ion sources of the diagnostic injectors of fast hydrogen atomic beams.

  13. Angular dependences in auger electron emission from the Ni(001) face. II. Angular distribution of auger electron emission from the Ni(001) face for different temperatures and different electron energies in M 2,3VV transition

    NASA Astrophysics Data System (ADS)

    Mróz, S.; Mróz, A.; Wieczorek, A.; Fritzsche, V.

    1989-12-01

    Angular-resolved Auger electron spectroscopy (ARAES) was applied for the investigation of the Ni(001) face of both a clean surface and a surface covered with a c(2 × 2) sulphur layer at different sample temperatures. Polar ARAES profiles measured for the NiM 2,3VV transition are presented for the [100] and [110] azimuths, for the full Auger current and for particular Auger energies as well. These latter profiles are theoretically calculated and compared with experiment. An increase of the temperature up to 980 K does not influence appreciably the polar ARAES profiles for the c(2 × 2) {S}/{Ni}(001) sample. It indicates that the atomic structure of the surface investigated is not changed in this temperature region.

  14. A new route to nanoscale tomographic chemical analysis: Focused ion beam-induced auger electron spectrosocpy

    NASA Astrophysics Data System (ADS)

    Parvaneh, Hamed

    This research project is aimed to study the application of ion-induced Auger electron spectroscopy (IAES) in combination with the characteristics of focused ion beam (FIB) microscopy for performing chemical spectroscopy and further evaluate its potential for 3-dimensional chemical tomography applications. The mechanism for generation of Auger electrons by bombarding ions is very different from its electron induced counterpart. In the conventional electron-induced Auger electron spectroscopy (EAES), an electron beam with energy typically in the range 1-10kV is used to excite inner-shell (core) electrons of the solid. An electron from a higher electron energy state then de-excites to fill the hole and the extra energy is then transferred to either another electron, i.e. the Auger electron, or generation of an X-ray (photon). In both cases the emitting particles have charac-teristic energies and could be used to identify the excited target atoms. In IAES, however, large excitation cross sections can occur by promotion of in-ner shell electrons through crossing of molecular orbitals. Originally such phenomenological excitation processes were first proposed [3] for bi-particle gas phase collision systems to explain the generation of inner shell vacancies in violent collisions. In addition to excitation of incident or target atoms, due to a much heavier mass of ions compared to electrons, there would also be a substantial momentum transfer from the incident to the target atoms. This may cause the excited target atom to recoil from the lattice site or alternatively sputter off the surface with the possibility of de-excitation while the atom is either in motion in the matrix or traveling in vacuum. As a result, one could expect differences between the spectra induced by incident electrons and ions and interpretation of the IAE spectra requires separate consideration of both excitation and decay processes. In the first stage of the project, a state-of-the-art mass

  15. Ultrafast dynamics of multiple exciton harvesting in the CdSe-ZnO system: electron injection versus Auger recombination.

    PubMed

    Zídek, Karel; Zheng, Kaibo; Abdellah, Mohamed; Lenngren, Nils; Chábera, Pavel; Pullerits, Tõnu

    2012-12-12

    We study multiple electron transfer from a CdSe quantum dot (QD) to ZnO, which is a prerequisite for successful utilization of multiple exciton generation for photovoltaics. By using ultrafast time-resolved spectroscopy we observe competition between electron injection into ZnO and quenching of multiexcitons via Auger recombination. We show that fast electron injection dominates over biexcitonic Auger recombination and multiple electrons can be transferred into ZnO. A kinetic component with time constant of a few tens of picoseconds was identified as the competition between injection of the second electron from a doubly excited QD and a trion Auger recombination. Moreover, we demonstrate that the multiexciton harvesting efficiency changes significantly with QD size. Within a narrow QD diameter range from 2 to 4 nm, the efficiency of electron injection from a doubly excited QD can vary from 30% to 70% in our system. PMID:23163524

  16. An experimental comparison of the K- and L-Auger electron spectra generated in the decays of 140Nd and 111In.

    PubMed

    Yakushev, E A; Kovalík, A; Filosofov, D V; Korolev, N A; Lebedev, N A; Lubashevski, A V; Rösch, F; Novgorodov, A F

    2005-03-01

    The low-energy electron spectra generated in the decay of 140Nd have been measured using a combined electrostatic spectrometer adjusted to the 4, 7, and 35 eV instrumental resolution. In order to estimate the therapeutic potential of low-energy electrons associated with the decay of 140Nd, similar experiments have been performed with 111In. Relative Auger electron intensity ratios per decay are: 111In(K-Auger)/140Nd(K-Auger)=1.47(12), 111In(L-Auger) /140Nd(L-Auger)=1.1(4), and 111In(L-Auger [2.8-7 keV])/140Nd(L-Auger [2.8-7 keV])=0.24(11). The obtained K-Auger group intensity ratios have been compared with results of calculations. The good agreement found for the experimental and estimated values indicates that such information can be also derived using available nuclear and atomic data. The relative intensity of L-Auger electrons emitted within the 2.8-7 keV interval is higher for 140Nd by a factor of about 4 compared to 111In. As the L-Auger emission is dominating relative to that of the K-Auger group, this implicates that any potential endotherapeutic strategy using 140Nd-labelled targeting vectors requires a maximum accumulation of the endoradiotherapeutical close to the cell nucleus or the DNA of the tumour cell. PMID:15607923

  17. Auger-electron angular distributions calculated without the two-step approximation: Calculation of angle-resolved resonant Auger spectra of C2 H2

    NASA Astrophysics Data System (ADS)

    Colle, Renato; Embriaco, Davide; Massini, Michol; Simonucci, Stefano; Taioli, Simone

    2004-10-01

    Analytic expressions for the direct, resonant, and interference contributions to the differential cross section of a resonant Auger process, produced by the inner-shell photoionization of a linear molecule either “fixed in space” or belonging to a gas of randomly oriented molecules, have been derived following Dill’s procedures [ Dill , Phys. Rev. Lett. 45, 1393 (1980) ], but going beyond the two-step approximation. Angle-resolved Auger spectra of the C2H2 molecule measured on top of the C1s→π* resonance [ Kivimäki , J. Phys. B 30, 4279 (1997) ] have been calculated together with asymmetry parameters, analyzing also the different contributions to the electron angular distributions.

  18. Channel-resolved photo- and Auger-electron spectroscopy of halogenated hydrocarbons

    NASA Astrophysics Data System (ADS)

    Ablikim, Utuq; Kaderiya, B.; Kumarapan, V.; Kushawaha, R.; Rudenko, A.; Rolles, D.; Xiong, H.; Berrah, N.; Bomme, C.; Savelyev, E.; Kilcoyne, D.

    2016-05-01

    Inner-shell photoelectron and Auger electron spectra of polyatomic molecules such as halogenated hydrocarbons are typically hard to interpret and assign due to many overlapping states that form broad bands even in high-resolution measurements. With the help of electron-ion-ion coincidence measurements performed using the velocity map imaging technique, we are able to detect high-energy (<= 150 eV) photo- and Auger electrons in coincidence with two- or many-body ionic fragmentation channels. Such channel-resolved measurements allow disentangling the overlapping electronic structures and help assigning individual components of the electron spectra to specific potential surfaces and final states. In this work, we present measurements on CH3 I, CH2 IBr, and CH2 ICl molecules in the gas-phase using soft x-ray light provided by the Advanced Light Source at LBNL. This project is supported by the DOE, Office of Science, BES, Division of Chemical, Geological and Biological Sciences under Award Number DE-FG02-86ER13491 (U.A., B.K., V.K., A.R., D.R.) and Award Number DE-SC0012376 (H.X., N.B.).

  19. Tunable graphene micro-emitters with fast temporal response and controllable electron emission

    PubMed Central

    Wu, Gongtao; Wei, Xianlong; Gao, Song; Chen, Qing; Peng, Lianmao

    2016-01-01

    Microfabricated electron emitters have been studied for half a century for their promising applications in vacuum electronics. However, tunable microfabricated electron emitters with fast temporal response and controllable electron emission still proves challenging. Here, we report the scaling down of thermionic emitters to the microscale using microfabrication technologies and a Joule-heated microscale graphene film as the filament. The emission current of the graphene micro-emitters exhibits a tunability of up to six orders by a modest gate voltage. A turn-on/off time of less than 1 μs is demonstrated for the graphene micro-emitters, indicating a switching speed about five orders of magnitude faster than their bulky counterparts. Importantly, emission performances of graphene micro-emitters are controllable and reproducible through engineering graphene dimensions by microfabrication technologies, which enables us to fabricate graphene micro-emitter arrays with uniform emission performances. Graphene micro-emitters offer an opportunity of realizing large-scale addressable micro-emitter arrays for vacuum electronics applications. PMID:27160693

  20. Tunable graphene micro-emitters with fast temporal response and controllable electron emission.

    PubMed

    Wu, Gongtao; Wei, Xianlong; Gao, Song; Chen, Qing; Peng, Lianmao

    2016-01-01

    Microfabricated electron emitters have been studied for half a century for their promising applications in vacuum electronics. However, tunable microfabricated electron emitters with fast temporal response and controllable electron emission still proves challenging. Here, we report the scaling down of thermionic emitters to the microscale using microfabrication technologies and a Joule-heated microscale graphene film as the filament. The emission current of the graphene micro-emitters exhibits a tunability of up to six orders by a modest gate voltage. A turn-on/off time of less than 1 μs is demonstrated for the graphene micro-emitters, indicating a switching speed about five orders of magnitude faster than their bulky counterparts. Importantly, emission performances of graphene micro-emitters are controllable and reproducible through engineering graphene dimensions by microfabrication technologies, which enables us to fabricate graphene micro-emitter arrays with uniform emission performances. Graphene micro-emitters offer an opportunity of realizing large-scale addressable micro-emitter arrays for vacuum electronics applications. PMID:27160693

  1. Tunable graphene micro-emitters with fast temporal response and controllable electron emission

    NASA Astrophysics Data System (ADS)

    Wu, Gongtao; Wei, Xianlong; Gao, Song; Chen, Qing; Peng, Lianmao

    2016-05-01

    Microfabricated electron emitters have been studied for half a century for their promising applications in vacuum electronics. However, tunable microfabricated electron emitters with fast temporal response and controllable electron emission still proves challenging. Here, we report the scaling down of thermionic emitters to the microscale using microfabrication technologies and a Joule-heated microscale graphene film as the filament. The emission current of the graphene micro-emitters exhibits a tunability of up to six orders by a modest gate voltage. A turn-on/off time of less than 1 μs is demonstrated for the graphene micro-emitters, indicating a switching speed about five orders of magnitude faster than their bulky counterparts. Importantly, emission performances of graphene micro-emitters are controllable and reproducible through engineering graphene dimensions by microfabrication technologies, which enables us to fabricate graphene micro-emitter arrays with uniform emission performances. Graphene micro-emitters offer an opportunity of realizing large-scale addressable micro-emitter arrays for vacuum electronics applications.

  2. On the interatomic electronic processes following Auger decay in neon dimer.

    PubMed

    Stoychev, Spas D; Kuleff, Alexander I; Tarantelli, Francesco; Cederbaum, Lorenz S

    2008-08-21

    The accessible relaxation channels of the electronic states of Ne(++)-Ne and Ne(3+)-Ne populated by KLL Auger decay are studied. In particular, we address the "direct" and "exchange" interatomic Coulombic decays (ICDs) and the electron-transfer-mediated decay following the population of one-site states Ne(++)(2s(-2))-Ne and Ne(++)(2s(-1)2p(-1) (1)P)-Ne. Radiative charge transfer of the low lying Ne(++)(2p(-2))-Ne states, three-electron ICD process from the Ne(++)(2s(-2))-Ne states, as well as charge transfer at the points of curve crossing of the lowest in energy Ne(3+)(2p(-3))-Ne states are also discussed. To carry out the present study, we have calculated the potential energy curves (from 1.75 to 5.00 A) of the ground state Ne(2), the core ionized state Ne(+)(1s(-1))-Ne, and the dicationic and tricationic states with energies in the range of 45-140 eV using accurate ab initio methods and basis sets. Apart from being of interest by themselves, the results obtained may be helpful in interpreting the recent measurements of interatomic electronic processes following Auger decay in neon dimer [K. Kreidi et al., J. Phys. B 41, 101002 (2008)]. PMID:19044767

  3. New electronics for the surface detectors of the Pierre Auger Observatory

    NASA Astrophysics Data System (ADS)

    Kleifges, M.

    2016-07-01

    The Pierre Auger Observatory is the largest installation worldwide for the investigation of ultra-high energy cosmic rays. Air showers are detected using a hybrid technique with 27 fluorescence telescopes and 1660 water-Cherenkov detectors (WCD) distributed over about 3000 km2. The Auger Collaboration has decided to upgrade the electronics of the WCD and complement the surface detector with scintillators (SSD). The objective is to improve the separation between the muonic and the electron/photon shower component for better mass composition determination during an extended operation period of 8-10 years. The surface detector electronics records data locally and generates time stamps based on the GPS timing. The performance of the detectors is significantly improved with a higher sampling rate, an increased dynamic range, new generation of GPS receivers, and FPGA integrated CPU power. The number of analog channels will be increased to integrate the new SSD, but the power consumption needs to stay below 10 W to be able to use the existing photovoltaic system. In this paper, the concept of the additional SSD is presented with a focus on the design and performance of the new surface detector electronics.

  4. Stability and dissociation dynamics of N2 (++) ions following core ionization studied by an Auger-electron-photoion coincidence method.

    PubMed

    Iwayama, H; Kaneyasu, T; Hikosaka, Y; Shigemasa, E

    2016-07-21

    An Auger-electron-photoion coincidence (AEPICO) method has been applied to study the stability and dissociation dynamics of dicationic states after the N K-shell photoionization of nitrogen molecules. From time-of-flight and kinetic energy analyses of the product ions, we have obtained coincident Auger spectra associated with metastable states of N2 (++) ions and dissociative states leading to N2 (++) → N(+) + N(+) and N(++) + N. To investigate the production of dissociative states, we present two-dimensional AEPICO maps which reveal the correlations between the binding energies of the Auger final states and the ion kinetic energy release. These correlations have been used to determine the dissociation limits of individual Auger final states. PMID:27448885

  5. Radiolabeling and in vitro evaluation of 67Ga-NOTA-modular nanotransporter – A potential Auger electron emitting EGFR-targeted radiotherapeutic

    PubMed Central

    Koumarianou, Eftychia; Slastnikova, Tatiana A.; Pruszynski, Marek; Rosenkranz, Andrey A.; Vaidyanathan, Ganesan; Sobolev, Alexander S.; Zalutsky, Michael R.

    2014-01-01

    Introduction Modular nanotransporters (MNTs) are vehicles designed to transport drugs from the cell surface via receptor-mediated endocytosis and endosomal escape to nucleus. Hence their conjugation to Auger electron emitters, can cause severe cell killing, by nuclear localization. Herein we evaluate the use of MNT as a platform for targeted radiotherapy with 67Ga. Methods EGF was the targeting ligand on the MNT, and NOTA was selected for its radiolabeling with 67Ga. In the radiolabeling study we dealt with the precipitation of MNT (pI 5.7) at the labeling pH (4.5–5.5) of 67Ga. Cellular and nuclei uptake of 67Ga-NOTA-MNT by the A431 cell line was determined. Its specific cytotoxicity was compared to that of 67Ga-EDTA, 67Ga-NOTA-BSA and 67Ga-NOTA-hEGF, in A431 and U87MGWTT, cell lines, by clonogenic assay. Dosimetry studies were also performed. Results 67Ga-NOTA-MNT was produced with 90% yield and specific activity of 25.6 mCi/mg. The in vitro kinetics revealed an increased uptake over 24 h. 55% of the internalized radioactivity was detected in the nuclei at 1 h. The cytotoxicity of 67Ga-NOTA-MNT on A431 cell line was 17 and 385-fold higher when compared to non-specific 67Ga-NOTA-BSA and 67Ga-EDTA. While its cytotoxic potency was 13 and 72 – fold higher when compared to 67Ga-NOTA-hEGF in the A431 and the U87MGWTT cell lines, respectively, validating its nuclear localization. The absorbed dose, for 63% cell killing, was 9 Gy, confirms the high specific index of 67Ga. Conclusion These results demonstrate the feasibility of using MNT as a platform for single cell kill targeted radiotherapy by Auger electron emitters. PMID:24776093

  6. Kinetic energies to analyze the experimental auger electron spectra by density functional theory calculations

    NASA Astrophysics Data System (ADS)

    Endo, Kazunaka

    2016-02-01

    In the Auger electron spectra (AES) simulations, we define theoretical modified kinetic energies of AES in the density functional theory (DFT) calculations. The modified kinetic energies correspond to two final-state holes at the ground state and at the transition-state in DFT calculations, respectively. This method is applied to simulate Auger electron spectra (AES) of 2nd periodic atom (Li, Be, B, C, N, O, F)-involving substances (LiF, beryllium, boron, graphite, GaN, SiO2, PTFE) by deMon DFT calculations using the model molecules of the unit cell. Experimental KVV (valence band electrons can fill K-shell core holes or be emitted during KVV-type transitions) AES of the (Li, O) atoms in the substances agree considerably well with simulation of AES obtained with the maximum kinetic energies of the atoms, while, for AES of LiF, and PTFE substance, the experimental F KVV AES is almost in accordance with the spectra from the transitionstate kinetic energy calculations.

  7. Analysis methodology of movable emittance-meter measurements for low energy electron beams.

    PubMed

    Mostacci, A; Bacci, A; Boscolo, M; Chiadroni, E; Cianchi, A; Filippetto, D; Migliorati, M; Musumeci, P; Ronsivalle, C; Rossi, A R

    2008-01-01

    The design of photoinjectors for modern free electron laser linac relies heavily on particular beam behavior in the few meters after the gun. To experimentally characterize it a movable emittance meter was proposed and built [L. Catani et al., Rev. Sci. Instrum. 77, 093301 (2006)] based on the beam slicing technique. This paper addresses all the aspects of analysis of the data acquired with the emittance meter and common to any slit based emittance measurement for low energy beams. PMID:18248027

  8. Experimental optimization of the 6-dimentional electron beam emittance at the NSLS SDL

    SciTech Connect

    Qian, H.J.; Murphy, J.; Shen,Y.; Tang,C.X.; Wang,X.J.

    2011-05-13

    Experimental optimization of the 6-dimensional electron beam emittance generated by a Magnesium (Mg) photocathode RF gun is presented in this report. A new electron beam optimization algorithm for a low charge (<100 pC) beam was experimentally demonstrated; where the electron beam velocity bunching inside the RF gun plays a critical role, and the transverse emittance as a function of the laser-RF timing jitter was experimentally characterized for the first time. A 20 pC electron beam was optimized to have a normalized slice emittance of 0.15 mm mrad and a longitudinal projected emittance of 3.9 ps keV. Furthermore, the upper limit of the measured thermal emittance - 0.5 mm mrad per mm of the rms laser size, is about 50% lower than the theoretical prediction for a Mg cathode (Qian et al., 2010) [1].

  9. X-ray fluorescence/Auger-electron coincidence spectroscopy of vacancy cascades in atomic argon

    SciTech Connect

    Arp, U.; LeBrun, T.; Southworth, S.H.; Jung, M.; MacDonald, M.A.

    1996-12-01

    Argon L{sub 2.3}-M{sub 2.3}M{sub 2.3} Auger-electron spectra were measured in coincidence with K{alpha} fluorescent x-rays in studies of Ar K-shell vacancy decays at several photon energies above the K-threshold and on the 1s-4p resonance in atomic argon. The complex spectra recorded by conventional electron spectroscopy are greatly simplified when recorded in coincidence with fluorescent x-rays, allowing a more detailed analysis of the vacancy cascade process. The resulting coincidence spectra are compared with Hartree-Fock calculations which include shake-up transitions in the resonant case. Small energy shifts of the coincidence electron spectra are attributed to post-collision interaction with 1s photoelectrons.

  10. Ultra low emittance electron beams from multi-alkali antimonide photocathode operated with infrared light

    NASA Astrophysics Data System (ADS)

    Cultrera, L.; Gulliford, C.; Bartnik, A.; Lee, H.; Bazarov, I.

    2016-03-01

    The intrinsic emittance of electron beams generated from a multi-alkali photocathode operated in a high voltage DC gun is reported. The photocathode showed sensitivity extending to the infrared part of the spectrum up to 830 nm. The measured intrinsic emittances of electron beams generated with light having wavelength longer than 800 nm are approaching the limit imposed by the thermal energy of electrons at room temperature with quantum efficiencies comparable to metallic photocathodes used in operation of modern photoinjectors.

  11. Approaches to analyzing insulators with Auger Electron Spectroscopy: Update and Overview

    SciTech Connect

    Baer, Donald R.; Lea, Alan S.; Geller, J.; Hammond, John S.; Kover, L.; Powell, Cedric J.; Seah, M. P.; Suzuki, M.; Watts, J. W.; Wolstenholme, J.

    2010-01-01

    This paper provides an updated overview, intended to be of practical value to analysts, of methods that can be applied to minimize or control the buildup of near surface electrical charge during electron induced Auger electron spectroscopy (AES). Although well developed methods can be highly effective, dealing with insulating or ungrounded samples for which high spatial resolution is needed remains a challenge. Examples of the application of methods involving low energy ion sources and sample thinning using a focused ion beam that can allow high resolution measurements on a variety of samples are highlighted. The physical bases of newer and traditional methods are simply described along with strengths and limitations of the methods. Summary tables indicate which methods apply to almost any spectrometer, which require special instrumental capabilities, and those that require special sample preparation or mounting.

  12. Auger electron and photoabsorption spectra of glycine in the vicinity of the oxygen K-edge measured with an X-FEL

    NASA Astrophysics Data System (ADS)

    Sanchez-Gonzalez, A.; Barillot, T. R.; Squibb, R. J.; Kolorenč, P.; Agaker, M.; Averbukh, V.; Bearpark, M. J.; Bostedt, C.; Bozek, J. D.; Bruce, S.; Carron Montero, S.; Coffee, R. N.; Cooper, B.; Cryan, J. P.; Dong, M.; Eland, J. H. D.; Fang, L.; Fukuzawa, H.; Guehr, M.; Ilchen, M.; Johnsson, A. S.; Liekhus-S, C.; Marinelli, A.; Maxwell, T.; Motomura, K.; Mucke, M.; Natan, A.; Osipov, T.; Östlin, C.; Pernpointner, M.; Petrovic, V. S.; Robb, M. A.; Sathe, C.; Simpson, E. R.; Underwood, J. G.; Vacher, M.; Walke, D. J.; Wolf, T. J. A.; Zhaunerchyk, V.; Rubensson, J.-E.; Berrah, N.; Bucksbaum, P. H.; Ueda, K.; Feifel, R.; Frasinski, L. J.; Marangos, J. P.

    2015-12-01

    We report the first measurement of the near oxygen K-edge auger spectrum of the glycine molecule. Our work employed an x-ray free electron laser as the photon source operated with input photon energies tunable between 527 and 547 eV. Complete electron spectra were recorded at each photon energy in the tuning range, revealing resonant and non-resonant auger structures. Finally ab initio theoretical predictions are compared with the measured above the edge auger spectrum and an assignment of auger decay channels is performed.

  13. Atomic and Molecular Photoelectron and Auger Electron SpectroscopyStudies Using Synchrotron Radiation

    SciTech Connect

    Southworth, Stephen H.

    1982-01-01

    Electron spectroscopy, combined with synchrotron radiation, was used to measure the angular distributions of photoelectrons and Auger electrons from atoms and molecules as functions of photon energy. The branching ratios and partial cross sections were a 130 measured in certain cases. By comparison with theoretical calculations, the experimental results are interpreted in terms of the characteristic electronic structure and ionization dynamics of the atomic or molecular sample. The time structure of the synchrotron radiation source was used to record time-of-flight (TOF) spectra o f the ejected electrons. The ''a double-angle-TOF'' method for the measurement of photoelectron angular distributions is discussed. This technique offers the advantages of increased electron collect ion efficiency and the elimination of certain systematic errors. Several results were obtained for Xe using photon energies in the range hv {approx_equal} 60-190 eV, where excitation and ionization of the inner-subshell 4d electrons dominates. The 4d asymmetry parameter {beta} exhibits strong oscillations with energy, in agreement with several theoretical calculations. As predicted, the 5p asymmetry parameter was observed to deviate strongly from that calculated using the independent-electron model, due to intershell correlation with the 4d electrons.

  14. Auger decay of 1{sigma}{sub g} and 1{sigma}{sub u} hole states of the N{sub 2} molecule. II. Young-type interference of Auger electrons and its dependence on internuclear distance

    SciTech Connect

    Cherepkov, N. A.; Semenov, S. K.; Schoeffler, M. S.; Titze, J.; Petridis, N.; Jahnke, T.; Cole, K.; Schmidt, L. Ph. H.; Czasch, A.; Jagutzki, O.; Schmidt-Boecking, H.; Doerner, R.; Akoury, D.; Williams, J. B.; Landers, A. L.; Osipov, T.; Lee, S.; Prior, M. H.; Belkacem, A.; Weber, Th.

    2010-08-15

    Theoretical two-center interference patterns produced (i) by the K-shell photoionization process of the N{sub 2} molecule and (ii) by the Auger decay process of the K-shell hole state of the N{sub 2} molecule are compared for the case of equal photo- and Auger-electron energies of about 360 eV. The comparison shows that both the angular distribution of the photoelectrons and the angular distribution of the Auger electrons of equal energy in the molecular frame are primarily defined by the Young interference. The experimental data for the angular resolved K-shell Auger electrons as a function of the kinetic-energy release (KER) obtained earlier [Phys. Rev. A 81, 043426 (2010)] have been renormalized in order to visualize the angular variation in the regions of low Auger-electron intensities. That renormalized data are compared with the corresponding theoretical results. From the known behavior of the potential energy curves, the connection between the KER and the internuclear distance can be established. Since the Young interference pattern is sensitive to the internuclear distance in the molecule, from the measured KER dependence of the Young interference pattern one can trace the behavior of the Auger-electron angular distribution for different molecular terms as a function of internuclear distance. The results of that analysis are in a good agreement with the corresponding theoretical predictions.

  15. Relationship Between Chromatin Structure and Sensitivity to Molecularly Targeted Auger Electron Radiation Therapy

    SciTech Connect

    Terry, Samantha Y.A.

    2012-07-15

    Purpose: The open structure of euchromatin renders it susceptible to DNA damage by ionizing radiation (IR) compared with compact heterochromatin. The effect of chromatin configuration on the efficacy of Auger electron radiotherapy was investigated. Methods and Materials: Chromatin structure was altered in MDA-MB-468 and 231-H2N human breast cancer cells by suberoylanilide hydroxamic acid (SAHA), 5-aza-2-deoxycytidine, or hypertonic treatment. The extent and duration of chromatin structural changes were evaluated using the micrococcal nuclease assay. DNA damage ({gamma}H2AX assay) and clonogenic survival were evaluated after exposure to {sup 111}In-DTPA-hEGF, an Auger electron-emitting radiopharmaceutical, or IR. The intracellular distribution of {sup 111}In-DTPA-hEGF after chromatin modification was investigated in cell fractionation experiments. Results: Chromatin remained condensed for up to 20 minutes after NaCl and in a relaxed state 24 hours after SAHA treatment. The number of {gamma}H2AX foci per cell was greater in MDA-MB-468 and 231-H2N cells after IR (0.5 Gy) plus SAHA (1 {mu}M) compared with IR alone (16 {+-} 0.6 and 14 {+-} 0.3 vs. 12 {+-} 0.4 and 11 {+-} 0.2, respectively). More {gamma}H2AX foci were observed in MDA-MB-468 and 231-H2N cells exposed to {sup 111}In-DTPA-hEGF (6 MBq/{mu}g) plus SAHA vs. {sup 111}In-DTPA-hEGF alone (11 {+-} 0.3 and 12 {+-} 0.7 vs. 9 {+-} 0.4 and 7 {+-} 0.3, respectively). 5-aza-2-deoxycytidine enhanced the DNA damage caused by IR and {sup 111}In-DTPA-hEGF. Clonogenic survival was reduced in MDA-MB-468 and 231-H2N cells after IR (6 Gy) plus SAHA (1 {mu}M) vs. IR alone (0.6% {+-} 0.01 and 0.3% {+-} 0.2 vs. 5.8% {+-} 0.2 and 2% {+-} 0.1, respectively) and after {sup 111}In-DTPA-hEGF plus SAHA compared to {sup 111}In-DTPA-hEGF alone (21% {+-} 0.4% and 19% {+-} 4.6 vs. 33% {+-} 2.3 and 32% {+-} 3.7). SAHA did not affect {sup 111}In-DTPA-hEGF nuclear localization. Hypertonic treatment resulted in fewer {gamma}H2AX foci per cell

  16. Undulator-Based Laser Wakefield Accelerator Electron Beam Energy Spread and Emittance Diagnostic

    SciTech Connect

    Bakeman, M.S.; Van Tilborg, J.; Nakamura, K.; Gonsalves, A.; Osterhoff, J.; Sokollik, T.; Lin, C.; Robinson, K.E.; Schroeder, C.B.; Toth, Cs.; Weingartner, R.; Gruner, F.; Esarey, E.; Leemans, W.P.

    2010-06-01

    The design and current status of experiments to couple the Tapered Hybrid Undulator (THUNDER) to the Lawrence Berkeley National Laboratory (LBNL) laser plasma accelerator (LPA) to measure electron beam energy spread and emittance are presented.

  17. Undulator-Based Laser Wakefield Accelerator Electron Beam Energy Spread and Emittance Diagnostic

    SciTech Connect

    Bakeman, M. S.; Van Tilborg, J.; Nakamura, K.; Gonsalves, A.; Osterhoff, J.; Robinson, K. E.; Schroeder, C. B.; Toth, Cs.; Esarey, E.; Leemans, W. P.; Sokollik, T.; Lin, C.; Weingartner, R.; Gruener, F.

    2010-11-04

    The design and current status of experiments to couple the Tapered Hybrid Undulator (THUNDER) to the Lawrence Berkeley National Laboratory (LBNL) laser plasma accelerator (LPA) to measure electron beam energy spread and emittance are presented.

  18. Thickness determination of few-layer hexagonal boron nitride films by scanning electron microscopy and Auger electron spectroscopy

    SciTech Connect

    Sutter, P. Sutter, E.

    2014-09-01

    We assess scanning electron microscopy (SEM) and Auger electron spectroscopy (AES) for thickness measurements on few-layer hexagonal boron nitride (h-BN), the layered dielectric of choice for integration with graphene and other two-dimensional materials. Observations on h-BN islands with large, atomically flat terraces show that the secondary electron intensity in SEM reflects monolayer height changes in films up to least 10 atomic layers thickness. From a quantitative analysis of AES data, the energy-dependent electron escape depth in h-BN films is deduced. The results show that AES is suitable for absolute thickness measurements of few-layer h-BN of 1 to 6 layers.

  19. Influence of emitter ring manufacturing tolerances on electron beam quality of high power gyrotrons

    NASA Astrophysics Data System (ADS)

    Pagonakis, Ioannis Gr.; Illy, Stefan; Thumm, Manfred

    2016-08-01

    A sensitivity analysis of manufacturing imperfections and possible misalignments of the emitter ring in the gyrotron cathode structure on the electron beam quality has been performed. It has been shown that a possible radial displacement of the emitter ring of the order of few tens of microns can cause dramatic effects on the beam quality and therefore the gyrotron operation. Two different design approaches are proposed in order to achieve an electron beam which is less sensitive to manufacturing imperfections.

  20. Oxygen diffusion of anodic surface oxide film on titanium studied by Auger electron spectroscopy. [Oxygen diffusivity

    SciTech Connect

    Wang, P.S.; Wittberg, T.N.; Keil, R.G.

    1982-01-01

    TiO/sub 2/ films of about 1000 A were grown onto titanium foils anodically under galvanostatic conditions at 20 mA/cm/sup 2/ in saturated aqueous solutions of ammonium tetraborate. The samples were then aged at 450, 500, and 550/sup 0/C, and oxygen diffusion was observed by Auger electron spectroscopy (AES) profilings. The oxygen diffusivities were calculated by Fick's Second Law, using the Boltzmann-Matano solution, to be 9.4 x 10/sup -17/, 2.6 x 10/sup -16/, and 1.2 x 10/sup -15/ cm/sup 2//sec at 450, 500, and 550/sup 0/C, respectively. The diffusivities obtained by this method were also compared with those obtained using an exact solution to Fick's Second Law. The activation energy was calculated to be 30 kcal/mole.

  1. Auger electron spectroscopy and depth profile study of oxidation of modified 440C steel

    NASA Technical Reports Server (NTRS)

    Ferrante, J.

    1974-01-01

    Auger electron spectroscopy (AES) and sputtering were used to study selective oxidation of modified 440C steel. The sample was polycrystalline. Oxidation was performed on initially clean surfaces for pressures ranging from 1 x 10 to the minus 7th power to 1 x 10 to the minus 5th power torr and temperatures ranging from room temperature to 800 C. AES traces were taken during oxidation. In situ sputtering depth profiles are also obtained. A transition temperature is observed in the range 600 to 700 C for which the composition of the outer surface oxide changed from iron oxide to chromium oxide. Heating in vacuum about 5 x 10 to the minus 10 power torr to 700 C causes conversion of the iron oxide surface to chromium oxide.

  2. Nonequilibrium dynamics of photoexcited electrons in graphene: Collinear scattering, Auger processes, and the impact of screening

    NASA Astrophysics Data System (ADS)

    Tomadin, Andrea; Brida, Daniele; Cerullo, Giulio; Ferrari, Andrea C.; Polini, Marco

    2013-07-01

    We present a combined analytical and numerical study of the early stages (sub-100-fs) of the nonequilibrium dynamics of photoexcited electrons in graphene. We employ the semiclassical Boltzmann equation with a collision integral that includes contributions from electron-electron (e-e) and electron-optical phonon interactions. Taking advantage of circular symmetry and employing the massless Dirac fermion (MDF) Hamiltonian, we are able to perform an essentially analytical study of the e-e contribution to the collision integral. This allows us to take particular care of subtle collinear scattering processes—processes in which incoming and outgoing momenta of the scattering particles lie on the same line—including carrier multiplication (CM) and Auger recombination (AR). These processes have a vanishing phase space for two-dimensional MDF bare bands. However, we argue that electron-lifetime effects, seen in experiments based on angle-resolved photoemission spectroscopy, provide a natural pathway to regularize this pathology, yielding a finite contribution due to CM and AR to the Coulomb collision integral. Finally, we discuss in detail the role of physics beyond the Fermi golden rule by including screening in the matrix element of the Coulomb interaction at the level of the random phase approximation (RPA), focusing in particular on the consequences of various approximations including static RPA screening, which maximizes the impact of CM and AR processes, and dynamical RPA screening, which completely suppresses them.

  3. Emittance growth of an nonequilibrium intense electron beam in a transport channel with discrete focusing

    SciTech Connect

    Carlsten, B.E.

    1997-02-01

    The author analyzes the emittance growth mechanisms for a continuous, intense electron beam in a focusing transport channel, over distances short enough that the beam does not reach equilibrium. The emittance grows from the effect of nonlinear forces arising from (1) current density nonuniformities, (2) energy variations leading to nonlinearities in the space-charge force even if the current density is uniform, (3) axial variations in the radial vector potential, (4) an axial velocity shear along the beam, and (5) an energy redistribution of the beam as the beam compresses or expands. The emittance growth is studied analytically and numerically for the cases of balanced flow, tight focusing, and slight beam scalloping, and is additionally studied numerically for an existing 6-MeV induction linear accelerator. Rules for minimizing the emittance along a beamline are established. Some emittance growth will always occur, both from current density nonuniformities that arise along the transport and from beam radius changes along the transport.

  4. Characterizing and Optimizing Photocathode Laser Distributions for Ultra-low Emittance Electron Beam Operations

    SciTech Connect

    Zhou, F.; Bohler, D.; Ding, Y.; Gilevich, S.; Huang, Z.; Loos, H.; Ratner, D.; Vetter, S.

    2015-12-07

    Photocathode RF gun has been widely used for generation of high-brightness electron beams for many different applications. We found that the drive laser distributions in such RF guns play important roles in minimizing the electron beam emittance. Characterizing the laser distributions with measurable parameters and optimizing beam emittance versus the laser distribution parameters in both spatial and temporal directions are highly desired for high-brightness electron beam operation. In this paper, we report systematic measurements and simulations of emittance dependence on the measurable parameters represented for spatial and temporal laser distributions at the photocathode RF gun systems of Linac Coherent Light Source. The tolerable parameter ranges for photocathode drive laser distributions in both directions are presented for ultra-low emittance beam operations.

  5. Transverse Emittance and Current of Multi-GeV Trapped Electrons in a Plasma Wakefield Accelerator

    SciTech Connect

    Kirby, N.; Blumenfeld, I.; Clayton, C.E.; Decker, F.J.; Hogan, M.J.; Huang, C.; Ischebeck, R.; Iverson, R.H.; Joshi, C.; Katsouleas, T.; Lu, W.; Marsh, K.A.; Martins, S.F.; Mori, W.B.; Muggli, P.; Oz, E.; Siemann, R.H.; Walz, D.R.; Zhou, M.; /UCLA

    2009-10-17

    Multi-GeV trapped electron bunches in a plasma wakefield accelerator (PWFA) 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 emittance scales inversely with the square root of the plasma density in the nonlinear '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.

  6. Correlation between energy deposition and molecular damage from Auger electrons: A case study of ultra-low energy (5–18 eV) electron interactions with DNA

    PubMed Central

    Rezaee, Mohammad; Hunting, Darel J.; Sanche, Léon

    2015-01-01

    Purpose The present study introduces a new method to establish a direct correlation between biologically related physical parameters (i.e., stopping and damaging cross sections, respectively) for an Auger-electron emitting radionuclide decaying within a target molecule (e.g., DNA), so as to evaluate the efficacy of the radionuclide at the molecular level. These parameters can be applied to the dosimetry of Auger electrons and the quantification of their biological effects, which are the main criteria to assess the therapeutic efficacy of Auger-electron emitting radionuclides. Methods Absorbed dose and stopping cross section for the Auger electrons of 5–18 eV emitted by 125I within DNA were determined by developing a nanodosimetric model. The molecular damages induced by these Auger electrons were investigated by measuring damaging cross section, including that for the formation of DNA single- and double-strand breaks. Nanoscale films of pure plasmid DNA were prepared via the freeze-drying technique and subsequently irradiated with low-energy electrons at various fluences. The damaging cross sections were determined by employing a molecular survival model to the measured exposure–response curves for induction of DNA strand breaks. Results For a single decay of 125I within DNA, the Auger electrons of 5–18 eV deposit the energies of 12.1 and 9.1 eV within a 4.2-nm3 volume of a hydrated or dry DNA, which results in the absorbed doses of 270 and 210 kGy, respectively. DNA bases have a major contribution to the deposited energies. Ten-electronvolt and high linear energy transfer 100-eV electrons have a similar cross section for the formation of DNA double-strand break, while 100-eV electrons are twice as efficient as 10 eV in the induction of single-strand break. Conclusions Ultra-low-energy electrons (<18 eV) substantially contribute to the absorbed dose and to the molecular damage from Auger-electron emitting radionuclides; hence, they should be considered in the

  7. Correlation between energy deposition and molecular damage from Auger electrons: A case study of ultra-low energy (5–18 eV) electron interactions with DNA

    SciTech Connect

    Rezaee, Mohammad Hunting, Darel J.; Sanche, Léon

    2014-07-15

    Purpose: The present study introduces a new method to establish a direct correlation between biologically related physical parameters (i.e., stopping and damaging cross sections, respectively) for an Auger-electron emitting radionuclide decaying within a target molecule (e.g., DNA), so as to evaluate the efficacy of the radionuclide at the molecular level. These parameters can be applied to the dosimetry of Auger electrons and the quantification of their biological effects, which are the main criteria to assess the therapeutic efficacy of Auger-electron emitting radionuclides. Methods: Absorbed dose and stopping cross section for the Auger electrons of 5–18 eV emitted by{sup 125}I within DNA were determined by developing a nanodosimetric model. The molecular damages induced by these Auger electrons were investigated by measuring damaging cross section, including that for the formation of DNA single- and double-strand breaks. Nanoscale films of pure plasmid DNA were prepared via the freeze-drying technique and subsequently irradiated with low-energy electrons at various fluences. The damaging cross sections were determined by employing a molecular survival model to the measured exposure–response curves for induction of DNA strand breaks. Results: For a single decay of{sup 125}I within DNA, the Auger electrons of 5–18 eV deposit the energies of 12.1 and 9.1 eV within a 4.2-nm{sup 3} volume of a hydrated or dry DNA, which results in the absorbed doses of 270 and 210 kGy, respectively. DNA bases have a major contribution to the deposited energies. Ten-electronvolt and high linear energy transfer 100-eV electrons have a similar cross section for the formation of DNA double-strand break, while 100-eV electrons are twice as efficient as 10 eV in the induction of single-strand break. Conclusions: Ultra-low-energy electrons (<18 eV) substantially contribute to the absorbed dose and to the molecular damage from Auger-electron emitting radionuclides; hence, they should

  8. Interference of electron pairs in photoinduced N4,5 - O1O2,3 Auger decay in xenon

    NASA Astrophysics Data System (ADS)

    Žitnik, M.; Bučar, K.; Lablanquie, P.; Penent, F.; Palaudoux, J.; Andric, L.; Hikosaka, Y.; Ito, K.

    2012-11-01

    We observed an interference originating from coincidence detection of two indistinguishable electron pairs emitted upon photoionization of 4d electron in Xe. At 89.9 eV photon impact the energy of photoelectron ejected from 4d5/2 orbital equals energy of Auger electron emitted in decay of 4d3/2 hole into the [5s5p1P] state, and for the same final state the energy of the 4d3/2 photoelectron equals the Auger electron energy in decay of 4d5/2 hole. An angle-integrated coincidence yield as a function of photon energy is measured with the magnetic bottle time-of-flight spectrometer and shows a peak at the expected energy position.

  9. Single shot 3 GeV electron transverse emittance with a pepper-pot

    NASA Astrophysics Data System (ADS)

    Thomas, Cyrille; Delerue, Nicolas; Bartolini, Riccardo

    2013-11-01

    We present the first measurement of the transverse emittance of an electron bunch at 3 GeV using the pepper-pot technique. The measurements presented in this paper demonstrate the possibility to use such a method for single shot emittance measurement of high energy particles. This measurement presents also the experimental verification of a previous theoretical study, which was predicting in which condition such a measurement can be done. The method may present some technical limitations which are discussed in view of the application to future very small emittance multi-GeV particle accelerators.

  10. Instantaneous electron beam emittance measurement system based on the optical transition radiation principle

    NASA Astrophysics Data System (ADS)

    Jiang, Xiao-Guo; Wang, Yuan; Zhang, Kai-Zhi; Yang, Guo-Jun; Shi, Jin-Shui; Deng, Jian-Jun; Li, Jin

    2014-01-01

    One kind of instantaneous electron beam emittance measurement system based on the optical transition radiation principle and double imaging optical method has been set up. It is mainly adopted in the test for the intense electron-beam produced by a linear induction accelerator. The system features two characteristics. The first one concerns the system synchronization signal triggered by the following edge of the main output waveform from a Blumlein switch. The synchronous precision of about 1 ns between the electron beam and the image capture time can be reached in this way so that the electron beam emittance at the desired time point can be obtained. The other advantage of the system is the ability to obtain the beam spot and beam divergence in one measurement so that the calculated result is the true beam emittance at that time, which can explain the electron beam condition. It provides to be a powerful beam diagnostic method for a 2.5 kA, 18.5 MeV, 90 ns (FWHM) electron beam pulse produced by Dragon I. The ability of the instantaneous measurement is about 3 ns and it can measure the beam emittance at any time point during one beam pulse. A series of beam emittances have been obtained for Dragon I. The typical beam spot is 9.0 mm (FWHM) in diameter and the corresponding beam divergence is about 10.5 mrad.

  11. Simulation of electron beam formation and transport in a gas-filled electron-optical system with a plasma emitter

    NASA Astrophysics Data System (ADS)

    Grishkov, A. A.; Kornilov, S. Yu.; Rempe, N. G.; Shidlovskiy, S. V.; Shklyaev, V. A.

    2016-07-01

    The results of computer simulations of the electron-optical system of an electron gun with a plasma emitter are presented. The simulations are performed using the KOBRA3-INP, XOOPIC, and ANSYS codes. The results describe the electron beam formation and transport. The electron trajectories are analyzed. The mechanisms of gas influence on the energy inhomogeneity of the beam and its current in the regions of beam primary formation, acceleration, and transport are described. Recommendations for optimizing the electron-optical system with a plasma emitter are presented.

  12. Characterization of ion beam modified ceramic wear surfaces using Auger electron spectroscopy

    NASA Technical Reports Server (NTRS)

    Wei, W.; Lankford, J.

    1987-01-01

    An investigation of the surface chemistry and morphology of the wear surfaces of ceramic material surfaces modified by ion beam mixing has been conducted using Auger electron spectroscopy and secondary electron microscopy. Studies have been conducted on ceramic/ceramic friction and wear couples made up of TiC and NiMo-bonded TiC cermet pins run against Si3N4 and partially stabilized zirconia disc surfaces modified by the ion beam mixing of titanium and nickel, as well as ummodified ceramic/ceramic couples in order to determine the types of surface changes leading to the improved friction and wear behavior of the surface modified ceramics in simulated diesel environments. The results of the surface analyses indicate that the formation of a lubricating oxide layer of titanium and nickel, is responsible for the improvement in ceramic friction and wear behavior. The beneficial effect of this oxide layer depends on several factors, including the adherence of the surface modified layer or subsequently formed oxide layer to the disc substrate, the substrate materials, the conditions of ion beam mixing, and the environmental conditions.

  13. Measurement of the Spectral Distribution of Low Energy Electrons emitted as a result of MVV Auger Transition in Cu(100)

    NASA Astrophysics Data System (ADS)

    Satyal, Suman; Joglekar, P. V.; Shastry, K.; Weiss, A. H.; Hulbert, S. L.

    2011-10-01

    Auger Photoelectron Coincidence Spectroscopy (APECS) was used to investigate the physics of the Low Energy tail (LET) region of the Auger spectrum of a Cu (100) sample. A beam of 200eV photons was incident on the sample and two Cylindrical Mirror Analyzers (CMA's) were used to select the energy of electrons emitted from the sample. An APECS spectra was obtained with one of the CMA's fixed at the energy 136.25eV, which corresponds to the core photoemission peak. The APECS spectra contains the contributions from electrons excited by the MVV Auger transition plus a background due to true coincidences between photo-emitted valence band electrons that undergo inelastic scattering and transfer part of their energy with other valence electrons. Coincidence measurements were made with the fixed analyzer set at various energies between the core and the valence band. These measurements were used to obtain an estimate of the background due to the inelastically scattered valence band electrons.

  14. Laser Assisted Emittance Exchange: Downsizing the X-ray Free Electron Laser

    SciTech Connect

    Xiang, Dao; /SLAC

    2009-12-11

    A technique is proposed to generate electron beam with ultralow transverse emittance through laser assisted transverse-to-longitudinal emittance exchange. In the scheme a laser operating in the TEM10 mode is used to interact with the electron beam in a dispersive region and to initiate the emittance exchange. It is shown that with the proposed technique one can significantly downsize an x-ray free electron laser (FEL), which may greatly extend the availability of these light sources. A hard x-ray FEL operating at 1.5 {angstrom} with a saturation length within 30 meters using a 3.8 GeV electron beam is shown to be practically feasible.

  15. Production of Mg and Al Auger electrons by noble gas ion bombardment of Mg and Al surfaces

    NASA Technical Reports Server (NTRS)

    Ferrante, J.; Pepper, S. V.

    1976-01-01

    Relative production efficiencies of Mg and Al Auger electrons by He, Ne, Ar, Kr, and Xe ion bombardment are reported as a function of ion energy for energies not exceeding 3 keV. The experimental apparatus employed consisted of a LEED-Auger system equipped with an ion gun and a four-grid retarding-potential analyzer. It is found that: (1) the shape of the ion-excited Auger signal was independent of the rare gas and quite symmetric; (2) the Al signal was about an order of magnitude smaller than the Mg signal for a given bombarding species and ion-gun voltage; (3) no signal was observed for He(+) bombardment under any of the experimental conditions; (4) signal strengths were independent of temperature and ion dose; (5) the Auger production efficiencies differed by no more than a factor of two among the different gases - except for He(+) - on a given metal; (6) all the signal strengths increased with increasing ion-gun voltage, with no maximum exhibited; and (7) the apparent threshold energy for the Al signal was higher than that for the Mg signal. The differences between the results for the two metals are attributed to the fact that the Al 2p orbital lies deeper in energy and closer to the nucleus than the corresponding Mg orbital.

  16. Microelectrode for energy and current control of nanotip field electron emitters

    SciTech Connect

    Lüneburg, S.; Müller, M. Paarmann, A. Ernstorfer, R.

    2013-11-18

    Emerging experiments and applications in electron microscopy, holography, and diffraction benefit from miniaturized electron guns for compact experimental setups. We present a highly compact microelectrode integrated field emitter that consists of a tungsten nanotip coated with a few micrometers thick polyimide film followed by a several nanometers thick gold film, both positioned behind the exposed emitter apex by approximately 10–30 μm. The control of the electric field strength at the nanometer scale tip apex allows suppression, extraction, and energy tuning of field-emitted electrons. The performance of the microelectrode is demonstrated experimentally and supported by numerical simulations.

  17. Low Emittance, High Brilliance Relativistic Electron Beams from a Laser-Plasma Accelerator

    SciTech Connect

    Brunetti, E.; Shanks, R. P.; Manahan, G. G.; Islam, M. R.; Ersfeld, B.; Anania, M. P.; Cipiccia, S.; Issac, R. C.; Raj, G.; Vieux, G.; Welsh, G. H.; Wiggins, S. M.; Jaroszynski, D. A.

    2010-11-19

    Progress in laser wakefield accelerators indicates their suitability as a driver of compact free-electron lasers (FELs). High brightness is defined by the normalized transverse emittance, which should be less than 1{pi} mm mrad for an x-ray FEL. We report high-resolution measurements of the emittance of 125 MeV, monoenergetic beams from a wakefield accelerator. An emittance as low as 1.1{+-}0.1{pi} mm mrad is measured using a pepper-pot mask. This sets an upper limit on the emittance, which is comparable with conventional linear accelerators. A peak transverse brightness of 5x10{sup 15} A m{sup -1} rad{sup -1} makes it suitable for compact XUV FELs.

  18. The beta-SiC(100) surface studied by low energy electron diffraction, Auger electron spectroscopy, and electron energy loss spectra

    NASA Technical Reports Server (NTRS)

    Dayan, M.

    1986-01-01

    The beta-SiC(100) surface has been studied by low energy electron diffraction, Auger electron spectroscopy, high resolution electron energy loss spectra (HREELS), and core level excitation EELS. Two new Si-terminated phases have been discovered, one with (3 x 2) symmetry, and the other with (2 x 1) symmetry. Models are presented to describe these phases. New results, for the C-rich surface, are presented and discussed. In addition, core level excitation EELS results are given and compared with theory.

  19. Medium Vacuum Electron Emitter as Soft Atmospheric Pressure Chemical Ionization Source for Organic Molecules.

    PubMed

    Liedtke, Sascha; Ahlmann, Norman; Marggraf, Ulrich; Schütz, Alexander; Vautz, Wolfgang; Franzke, Joachim

    2016-05-01

    An electron emitter as a soft atmospheric pressure chemical ionization source is presented, which operates at inner pressures of the device in the medium vacuum range (>10(-3) hPa). Conventional nonradioactive electron emitters require high vacuum (<10(-6) hPa) to prevent electrical sparkovers. The emitter presented here contains structural modifications of an existing setup, which inhibits electrical breakdowns up to 10(-2) hPa at 8 kV acceleration voltage. The increased inner pressure reduces the ionization efficiency until 10(-3) hPa-achievable without a turbomolecular pump-by 2% compared to high-vacuum conditions. This can be compensated with an increase of the electron source output. The functionality of this ion source is demonstrated with mass spectrometric and ion mobility measurements of acetone, eucalyptol, and diisopropyl methanephosphonate. Additional mass spectrometric measurements of 20 different organic compounds demonstrate the soft characteristics of this ionization source. PMID:27046293

  20. Reaction of sulfur dioxide with modified 440C, studied by Auger electron spectroscopy and depth profiling

    NASA Technical Reports Server (NTRS)

    Ferrante, J.

    1975-01-01

    Auger electron spectroscopy and sputtering were used to study the interaction of SO2 with modified 440C, which is a nominally 77-wt%-Fe, 14-wt%-Cr, and 4-wt%-Mo bearing steel with C, S, Si, Ni, V, P, and Mn making up the balance. The sample was polycrystalline. Three temperatures were used: room temperature, 500 C, and 600 C. The reaction time was varied from 30 minutes to 2 hours. A surface cleaned of oxides was the starting point for each reaction. For reactions at 500 C, the major constituents Cr, O, Fe, and S were present in the surface film. At 600 C, the principal constituents of the film were Cr, O, and S with no Fe present. Therefore, a transition in film composition occurred between 500 and 600 C. Oxides were the primary constituents of the films at both temperatures. Room-temperature reactions indicated that SO2 adsorbed dissociatively, with approximately equal quantities of S and O on the surface. For the same reaction time (1 hr) and pressure, a strong temperature dependence of film thickness was observed. The film formed at 600 C was approximately seven times thicker than that formed at 500 C.

  1. On the focused beam parameters of an electron gun with a plasma emitter

    NASA Astrophysics Data System (ADS)

    Kornilov, S.; Rempe, N.; Beniyash, A.; Murray, N.

    2014-11-01

    The report presents the measurement results of the focused beam brightness in the electron gun with plasma emitter. The beam brightness was approximately 1010 A·m-2·sr-1 under the beam power up to 4 kW and an electron energy of 60 keV at the focal distance of 0.5 m. Qualitative assessment of the beam parameters was performed by welding test pieces. The results describing the possibility in principle of using the guns with a plasma emitter in nonvacuum technological devices are presented.

  2. Plexciton quenching by resonant electron transfer from quantum emitter to metallic nanoantenna.

    PubMed

    Marinica, D C; Lourenço-Martins, H; Aizpurua, J; Borisov, A G

    2013-01-01

    Coupling molecular excitons and localized surface plasmons in hybrid nanostructures leads to appealing, tunable optical properties. In this respect, the knowledge about the excitation dynamics of a quantum emitter close to a plasmonic nanoantenna is of importance from fundamental and practical points of view. We address here the effect of the excited electron tunneling from the emitter into a metallic nanoparticle(s) in the optical response. When close to a plasmonic nanoparticle, the excited state localized on a quantum emitter becomes short-lived because of the electronic coupling with metal conduction band states. We show that as a consequence, the characteristic features associated with the quantum emitter disappear from the optical absorption spectrum. Thus, for the hybrid nanostructure studied here and comprising quantum emitter in the narrow gap of a plasmonic dimer nanoantenna, the quantum tunneling might quench the plexcitonic states. Under certain conditions the optical response of the system approaches that of the individual plasmonic dimer. Excitation decay via resonant electron transfer can play an important role in many situations of interest such as in surface-enhanced spectroscopies, photovoltaics, catalysis, or quantum information, among others. PMID:24206447

  3. Prominent conjugate processes in the PCI recapture of photoelectrons revealed by high resolution Auger electron measurements of Xe

    NASA Astrophysics Data System (ADS)

    Azuma, Yoshiro; Kosugi, Satoshi; Suzuki, Norihiro; Shigemasa, Eiji; Iwayama, Hiroshi; Koike, Fumihiro

    2016-05-01

    The Xe (N5O2 , 3O2 , 3) Auger electron spectrum originating from 4d5/ 2 - 1 photoionization was measured with the photon energy tuned very close above the ionization threshold. As the photon energy approached the 4d5/ 2 - 1 photoionization threshold, Rydberg series structures including several angular momentum components were formed within the Auger profile by the recapture of the photoelectrons into high-lying final ion orbitals. Our spectrum with resolution much narrower than the lifetime width of the corresponding core excited state allowed us to resolve detailed structures due to the orbital angular momenta very clearly. Unexpectedly, conjugate peaks originating from the exchange of angular momentum between the photoelectron and the Auger electron through Post-Collision-Interaction were found to dominate the spectrum. The new assignments were in accord with the quantum defect values obtained for the high Rydberg series for singly charged ionic Xe + 5 p(1S0) ml. This work was supported by Japan Society for the Promotion of Science through Grants-in-Aid for Scientific Research No. 23600009.

  4. Auger electron spectroscopy study of alloy 718 and 304L stainless steel irradiated with 800 MeV protons

    NASA Astrophysics Data System (ADS)

    García-Mazarío, M.; Hernández-Mayoral, M.; Lancha, A. M.

    2001-07-01

    It is well known that radiation produces changes in materials microstructure such as formation of defects, dissolution and redistribution of secondary phases, precipitation of new phases, etc. and changes in the grain boundary microchemistry by a process known as radiation-induced segregation (RIS). This paper describes the grain boundary microchemical characterization of alloy 718 and 304L stainless steel irradiated with high-energy protons at Los Alamos Neutron Science Center (LANSCE), performed by means of Auger electron spectroscopy (AES). In addition, non-irradiated alloy 718 was characterized as reference. The Auger results showed that as a consequence of exposure to proton radiation, the changes observed in alloy 718 were the disappearance of the nickel and niobium rich grain boundaries precipitates and RIS of the major alloying elements (nickel to grain boundaries, and chromium and iron away from grain boundaries). On the other hand, in irradiated AISI 304L no differences were observed between intergranular and transgranular areas.

  5. Growth of cobalt ultra-thin films deposited on Pt(100) surfaces: An Auger electron spectroscopy study

    NASA Astrophysics Data System (ADS)

    Boeglin, C.; Carrière, B.; Deville, J. P.; Heckmann, O.; Leroux, C.; Panissod, P.

    1989-04-01

    To investigate the possibility of building Co/Pt modulated multilayers, attention has been paid to the early stages of interface formation between cobalt and platinum. The growth of cobalt layers less than 10 monolayers thick on Pt(100) surfaces has been studied by Auger electron spectroscopy. Growth kinetics obtained by AES show that two different models of interface formation can be possible: the Volmer-Weber case (cobalt islands) or an interdiffusion process between the two metals (similar to suicide formation). Looking at the fine structure of the low-energy platinum Auger transitions suggests that there is a strong interaction between cobalt and platinum as soon as the equivalent of a cobalt 2 monolayer coverage is deposited. This would favor the interdiffusion process model.

  6. Ultra-bright pulsed electron beam with low longitudinal emittance

    DOEpatents

    Zolotorev, Max

    2010-07-13

    A high-brightness pulsed electron source, which has the potential for many useful applications in electron microscopy, inverse photo-emission, low energy electron scattering experiments, and electron holography has been described. The source makes use of Cs atoms in an atomic beam. The source is cycled beginning with a laser pulse that excites a single Cs atom on average to a band of high-lying Rydberg nP states. The resulting valence electron Rydberg wave packet evolves in a nearly classical Kepler orbit. When the electron reaches apogee, an electric field pulse is applied that ionizes the atom and accelerates the electron away from its parent ion. The collection of electron wave packets thus generated in a series of cycles can occupy a phase volume near the quantum limit and it can possess very high brightness. Each wave packet can exhibit a considerable degree of coherence.

  7. Directional Auger electron spectroscopy (DAES) and directional elastic peak electron spectroscopy (DEPES) in the investigation of the crystalline structure of surface layers: the Ag/Cu(111) interface

    NASA Astrophysics Data System (ADS)

    Mróz, S.; Nowicki, M.

    1993-11-01

    Dependence of the Auger signal (directional Auger electron spectroscopy — DAES) and the elastically scattered electron intensity (directional elastic peak electron spectroscopy — DEPES) on the direction of the primary electron beam ( E = 600-1500 eV) was measured using a retarding field analyser (LEED optics) for the Cu(111) face, both clean and covered with silver up to 12 ML. Well-developed maxima of DAES and DEPES signals appear when the primary beam is parallel to one of the close-packed rows of atoms in the sample surface layer, while the angular distribution of the emitted electrons is averaged over the large acceptance angle of the RFA and does not influence appreciably the DAES and DEPES profiles. From the positions of the maxima mentioned above the atomic structure of a few surface layers can be determined. The silver layer was found to be rotated for 60° with respect to the Cu(111) substrate.

  8. Test beam results of a low-pressure micro-strip gas chamber with a secondary-electron emitter

    SciTech Connect

    Kwan, S.; Anderson, D.F.; Zimmerman, J.; Sbarra, C.; Salomon, M.

    1994-10-01

    We present recent results, from a beam test, on the angular dependence of the efficiency and the distribution of the signals on the anode strips of a low-pressure microstrip gas chamber with a thick CsI layer as a secondary-electron emitter. New results of CVD diamond films as secondary-electron emitters are discussed.

  9. Oxygen diffusion from anodic surface oxide films on titanium subhydride studies by auger electron spectroscopy and electron energy loss spectroscopy

    NASA Astrophysics Data System (ADS)

    Wang, P. S.; Wittberg, T. N.; Wolf, J. D.; Keil, R. G.

    TiH sub x (0.5 less than x less than 1.7) samples were prepared from titanium foil in order to study the diffusion of oxygen in the titanium subhydride. An anodic oxide, 1000A thick, was grown on the titanium subhydride foils in an agueous saturated solution of ammonium tetraborate. These anodized samples were then heat treated at temperatures between 500 and 600(0)C and changes in the profile of oxygen concentration as a function of depth were monitored using auger electron spectroscopy. From this data then it was possible to calculate the diffusivity of oxygen in the titanium subhydride. It was also found that electron energy loss spectroscopy could be used to determine the titanium subhydride stoichiometry in the near-surface region. This was done by measuring the energy of the bulk plasmon loss peak, which for TiH sub x, varies linearly with hydrogen content. The amount of dehydriding which occurred following a given heat treatment could be determined from profiles of the plasmon loss energy as a function of depth. A sample of anodized TiH0 87 was studied in some detail. Significant dehydriding of this sample for heat treatment times of less than one hour only occured at temperatures above 550(0)C.

  10. PCI and interference effects in the energy and angular correlation between the photoelectron and the Auger electron for equal electron energies

    NASA Astrophysics Data System (ADS)

    Sheinerman, S. A.; Schmidt, V.

    1997-04-01

    Photoionization in the inner shell of an atom followed by Auger decay is considered for the case of equal energies of the emitted electrons. Due to the indistinguishability of both electrons it is imperative to describe this process as resonance embedded in the double ionization continuum, i.e. within the one-step formulation. As a consequence, two amplitudes appear where either one of the two electrons with momenta 0953-4075/30/7/008/img1 and 0953-4075/30/7/008/img2 is connected to the photoprocess, and correspondingly the other to the Auger decay. We have accounted for the modification of these amplitudes by post-collision interaction (PCI). To elucidate our theoretical treatment we have selected a simple example and demonstrate how both exchange and PCI strongly modify by interference the energy- and angle-dependent correlation patterns of coincident two-electron emission.

  11. Development of an Apparatus for High-Resolution Auger Photoelectron Coincidence Spectroscopy (APECS) and Electron Ion Coincidence (EICO) Spectroscopy

    NASA Astrophysics Data System (ADS)

    Kakiuchi, Takuhiro; Hashimoto, Shogo; Fujita, Narihiko; Mase, Kazuhiko; Tanaka, Masatoshi; Okusawa, Makoto

    We have developed an electron electron ion coincidence (EEICO) apparatus for high-resolution Auger photoelectron coincidence spectroscopy (APECS) and electron ion coincidence (EICO) spectroscopy. It consists of a coaxially symmetric mirror electron energy analyzer (ASMA), a miniature double-pass cylindrical mirror electron energy analyzer (DP-CMA), a miniature time-of-flight ion mass spectrometer (TOF-MS), a magnetic shield, an xyz stage, a tilt-adjustment mechanism, and a conflat flange with an outer diameter of 203 mm. A sample surface was irradiated by synchrotron radiation, and emitted electrons were energy-analyzed and detected by the ASMA and the DP-CMA, while desorbed ions were mass-analyzed and detected by the TOF-MS. The performance of the new EEICO analyzer was evaluated by measuring Si 2p photoelectron spectra of clean Si(001)-2×1 and Si(111)-7×7, and by measuring Si-L23VV-Si-2p Auger photoelectron coincidence spectra (Si-L23VV-Si-2p APECS) of clean Si(001)-2×1.

  12. Characterization of oxide layers on amorphous Zr-based alloys by Auger electron spectroscopy with sputter depth profiling

    NASA Astrophysics Data System (ADS)

    Baunack, S.; Mudali, U. Kamachi; Gebert, A.

    2005-09-01

    Amorphous Zr-Cu-Ni-Al-[Ti, Nb] ribbons prepared by melt spinning under argon atmosphere were subjected to electrochemical investigations. Passive films developed at potentiostatic anodic polarization in sulphuric acid solution were investigated by Auger electron spectroscopy (AES) and sputter depth profiling. Changes in the shape of the Auger peaks have been analyzed by factor analysis of the spectra obtained during depth profiling. Pronounced changes in shape and position occur for the Zr, Al, and Ti Auger transitions, but not for Cu and Ni. At least three different peak shapes for O(KVV) were found and attributed to different oxygen binding states. The alloy composition has no significant effect on the thickness and composition of the oxide layer. In multi-element alloys preferential sputtering is a common phenomenon. In the steady state of sputtering, a significant depletion in Cu is found. At the oxide/metal interface, a distinct enrichment of copper is found for all alloys and treatments. The degree of this Cu enrichment depends on the pretreatment. It is higher for the electrochemically-passivated samples than for samples with oxide layers grown during melt spinning.

  13. Effect of insulating layer on the Field Electron Emission Performance of Nano-Apex Metallic Emitters

    NASA Astrophysics Data System (ADS)

    AL-Qudah, Ala'a. A.; Mousa, Marwan S.; Fischer, A.

    2015-10-01

    This paper deals with the process of electron emission from the surface of metals (before and after coating with controlled layers of dielectric materials) into the vacuum due to an intense applied external electric field. This process is usually called cold field electron emission (CFE). The research work reported here includes the current-voltage (I-V) characteristics presented as Fowler-Nordheim (FN) plots and scanning electron micrographs in addition to the spatial emission current distributions (electron emission images). The process of coating the clean tungsten (W) emitters by layers of dielectric epoxylite resin was easy, and the measurements were performed under UHV ∼ 10-8 mbar. From comparing the results obtained in this work, significant improvement in properties of the emitters after coating are observed.

  14. Numerical and experimental studies of enhanced electron emission from functionalized carbon nanotube emitters

    NASA Astrophysics Data System (ADS)

    Jin, Feng; Little, Scott; Alzubi, Feras

    2007-03-01

    Vertically aligned carbon nanotubes (CNTs) were grown using plasma enhanced chemical vapor deposition (PECVD) method. The CNTs were further functionalized by coating their surface with a thin layer of low work function oxide emissive materials. The electron emission capability of the coated CNT emitters was greatly improved with the low work function emissive layer, particularly at high temperature. Thermionic emission current three orders magnitude higher was observed. The emission properties of the oxide coated CNTs were measured and characterized over a wide temperature and field ranges. It was found that neither the Fowler-Nordheim theory for field emission nor the Richardson theory for thermionic emission were adequate to describe the electron emission characteristics of these emitters in certain range of temperature and field. However, by adopting a general electron emission formulism developed by Murphy and Good, we were able to simulate the electron emission from the coated CNTs over the whole temperature and field range and fit the experimental data.

  15. Mechanical test in-situ fracture device for Auger electron spectroscopy

    NASA Technical Reports Server (NTRS)

    Moorhead, R. D.

    1975-01-01

    An in-situ fracture device for Auger spectroscopy was described. The device is designed to handle small tensile specimens or small double cantilever beam specimens and is fully instrumented with load and displacement transducers so that quantitative stress-strain measurements can be made directly. Some initial test results for specimens made from 4130 and 1020 steel were presented.

  16. Emittance and Current of Electrons Trapped in a Plasma Wakefield Accelerator

    SciTech Connect

    Kirby, N.; Blumenfeld, I.; Decker, F. J.; Hogan, M. J.; Ischebeck, R.; Iverson, R. H.; Siemann, R. H.; Walz, D. R.; Clayton, C. E.; Huang, C.; Joshi, C.; Lu, W.; Marsh, K. A.; Mori, W. B.; Zhou, M.; Katsouleas, T.; Muggli, P.; Oz, E.; Martins, S.

    2009-01-22

    In recent experiments plasma electrons became trapped in a plasma wakefield accelerator (PWFA). The transverse size of these trapped electrons on a downstream diagnostic yields an upper limit measurement of transverse normalized emittance divided by peak current, {epsilon}{sub N,{sub x}}/I. The lowest upper limit for {epsilon}{sub N,{sub x}}/I measured in the experiment is 1.3{center_dot}10{sup -10} m/A.

  17. Emittance and Current of Electrons Trapped in a Plasma Wakefield Accelerator

    SciTech Connect

    Kirby, N; Blumenfeld, I; Clayton, C.E.; Decker, F.J.; Hogan, M.J.; Huang, C.; Ischebeck, R.; Iverson, R.H.; Joshi, C.; Katsouleas, T.; Lu, W.; Marsh, K.A.; Mori, W.B.; Muggli, P; Oz, E.; Siemann, R.H.; Walz, D.R.; Zhou, M.; /SLAC /UCLA /USC

    2008-09-24

    In recent experiments plasma electrons became trapped in a plasma wakefield accelerator (PWFA). The transverse size of these trapped electrons on a downstream diagnostic yields an upper limit measurement of transverse normalized emittance divided by peak current, {var_epsilon}{sub N,x}/I. The lowest upper limit for {var_epsilon}{sub N,x}/I measured in the experiment is 1.3 {center_dot} 10{sup -10} m/A.

  18. Specific energy from Auger and conversion electrons of 131I, 188Re-anti-CD20 to a lymphocyte's nucleus

    NASA Astrophysics Data System (ADS)

    Torres-García, E.; Carrillo-Cazares, T. A.

    2011-01-01

    The typical radionuclides used to label anti-CD20 in the treatment of non-Hodgkin's lymphoma are 90Y, 131I, and 188Re, with the emission of beta particles, Auger electrons, and conversion electrons for the latter two. The aim of the present work was to calculate the contribution of high linear energy transfer radiation as Auger electrons (AE) and conversion electrons (CE) of 131I and 188Re-anti-CD20 to mean specific energy into the cell nucleus by Monte Carlo simulation (MCS), so as to infer therapeutic effectiveness on a dosimetric basis. MCS was used to quantify the frequency-mean specific energy into the cell nucleus, where the cell was modeled by two concentric spheres, considering two cell models. The results showed that 10% and 33% of the mean-specific energies (z¯) per disintegration imparted to the cell nucleus for both geometries are due to AE and CE; on the other hand, if the hit of AE and CE occurs, the contribution to (z¯) is about 64% and 86% for 131I and 188Re, respectively. According to the amount of specific energy from AE and CE into the cell nucleus by positive event, they can cause catastrophic effects in the nuclear DNA in the treatment of non-Hodgkin's lymphoma with 131I, 188Re-anti-CD20.

  19. Thermodynamic characterization of a diamond-based electron emitter

    NASA Astrophysics Data System (ADS)

    Fisher, T. S.; Strauss, A. M.; Davidson, J. L.; Kang, W. P.

    2000-01-01

    This paper contains a thermodynamic analysis of electron emission from a micro-fabricated diamond tip array. The analysis is based on experimental measurements of the current-voltage characteristics of an actual device. Field enhancement, applied field, and electrical current density are shown to influence thermodynamic performance. The idealized thermodynamic analysis predicts cooling rates above 10 W/cm2 for an existing device under room temperature operation and that 100 W/cm2 may be possible for future devices. .

  20. Inner-shell ionization of rotating linear molecules in the presence of spin-dependent interactions: Entanglement between a photoelectron and an auger electron

    NASA Astrophysics Data System (ADS)

    Ghosh, R.; Chandra, N.; Parida, S.

    2009-03-01

    This paper reports results of a theoretical study of angle- and spin-resolved photo-Auger electron coincident spectroscopy in the form of entanglement between these two particles emitted from a linear molecule. First, we develop an expression for a density matrix needed for studying spin-entanglement between a photoelectron and an Auger electron. In order to properly represent the molecular symmetries, nuclear rotation, and the spin-dependent interactions (SDIs), we have used symmetry adapted wavefunctions in Hund’s coupling scheme (a) for all the species participating in this two-step process. This expression shows that spin-entanglement in a photo-Auger electron pair in the presence of SDIs very strongly depends upon, among other things, polarization of the ionizing radia- tion, directions of motion and of spin polarization of two ejected electrons, and the dynamics of photoionization and of Auger decay. We have applied this expression, as an example, to a generic linear molecule in its J0, M0 = 0 state. This model calculation clearly brings out the salient features of the spin-entanglement of a photo-Auger electron pair in the presence of the SDIs.

  1. Luminescence quenching of conductive Si nanocrystals via “Linkage emission”: Hopping-like propagation of infrared-excited Auger electrons

    SciTech Connect

    Ishii, Masashi; Crowe, Iain F.; Halsall, Matthew P.; Hamilton, Bruce; Knights, Andrew P.; Gwilliam, Russell M.

    2014-08-14

    Phosphorus (P) is an n-type dopant for conductive silicon nanocrystals (Si-nc's), the electrical activation of which may be monitored through a non-radiative Auger recombination process that quenches the Si-nc luminescence. We investigated this quenching mechanism through electrical measurements of Si-nc's. Infrared-excited Auger electron emission as the non-radiative process was directly probed and the dynamics of the process are determined from a frequency response analysis. To explain the dynamics, we propose a model in which Auger electrons with a low kinetic energy establish a local inter-nanocrystal conductance and the repetition of this local conductance results in a constant photocurrent (“linkage emission”). This emission becomes significant by electron filling in the Si-nc's owing to the electrical activation of P, which is consistent with observed luminescence quenching behavior. We found that the IR photo-excited emission is distinct from the thermally induced hopping conduction and show that confined, rather than trapped, charges are the source of the Auger electrons. Thus, the process consumes both confined charges and the recombination energy for Auger emission, which explains the luminescence quenching mechanism of Si-nc:P.

  2. A Multislit Transverse-Emittance Diagnostic for Space-Charge-Dominated Electron Beams

    NASA Astrophysics Data System (ADS)

    Piot, P.; Song, J.; Li, R.; Krafft, G. A.; Jordan, K.; Feldl, E.; Kehne, D.; Denard, J.-C.

    1997-05-01

    Jefferson Lab is building a 10 MeV injector to provide electron beam for a high-power free-electron laser (FEL). To characterize the transverse phase space of the space-charged-dominated beam produced by this injector, we designed an interceptive multislit emittance diagnostic. It incorporates an algorithm for phase-space reconstruction and subsequent calculation of the Twiss parameters and emittance for both transverse directions at an update rate exceeding 1 Hz, a speed that will facilitate the transverse-phase-space matching between the injector and the FEL's accelerator that is critical for proper operation. This paper describes issues pertaining to the diagnostic's design. It also discusses the acquisition system, as well as the software algorithm and its implementation in the FEL control system. First results obtained from testing this diagnostic in Jefferson Lab's Injector Test Stand are also included.

  3. System for transporting an electron beam to the atmosphere for a gun with a plasma emitter

    NASA Astrophysics Data System (ADS)

    Kornilov, S. Yu.; Rempe, N. G.; Shidlovskiy, S. V.

    2016-06-01

    We report on the results of simulation of the gas flow in a gun with a plasma emitter and in the system for extracting the electron beam to the atmosphere, constructed on the basis of standard gasdynamic windows (GDWs). The design of the gun and GDWs is described. Calculations are performed for a pressure of about 10-3 Torr in the electron beam generation range. It is shown that the pressure drop to the atmospheric pressure in the system of electron beam extraction to the atmosphere can be ensured by two GDW stages evacuated by pumps with optimal performance.

  4. Auger electron spectroscopy analysis of the first stages of thermally stimulated oxidation of GaAs(100)

    NASA Astrophysics Data System (ADS)

    Passeggi, M. C. G.; Vaquila, I.; Ferrón, J.

    1998-05-01

    The first stages (exposures <10 4 L) of thermally stimulated oxidation of GaAs(100) have been studied using Auger electron spectroscopy and principal component analysis. We compare the GaAs oxidation processes taking place at high (700 K) and room temperatures, and during simultaneous electron bombardment and oxygen exposure. We found that while at room temperature, GaAs oxidizes via a one-phase process involving the simultaneous oxidation of Ga and As, the high temperature process is characterized by the presence of two different GaAs oxide phases. The first phase involves the simultaneous oxidation of Ga and As while in the second, only Ga oxides are formed. On the other hand, under simultaneous oxygen exposure and electron irradiation, two different oxide phases appear, both of them exhibiting the same features of the room temperature process, i.e., the simultaneous oxidation of Ga and As.

  5. Auger electron nanoscale mapping and x-ray photoelectron spectroscopy combined with gas cluster ion beam sputtering to study an organic bulk heterojunction

    SciTech Connect

    Heon Kim, Seong; Heo, Sung; Ihn, Soo-Ghang; Yun, Sungyoung; Hwan Park, Jong; Chung, Yeonji; Lee, Eunha; Park, Gyeongsu; Yun, Dong-Jin

    2014-06-16

    The lateral and vertical distributions of organic p/n bulk heterojunctions for an organic solar cell device are, respectively, investigated using nanometer-scale Auger electron mapping and using X-ray photoelectron spectroscopy (XPS) with Ar gas cluster ion beam (GCIB) sputtering. The concentration of sulfur, present only in the p-type material, is traced to verify the distribution of p-type (donor) and n-type (acceptor) materials in the blended structure. In the vertical direction, a considerable change in atomic sulfur concentration is observed using XPS depth profiling with Ar GCIB sputtering. In addition, Auger electron mapping of sulfur reveals the lateral 2-dimensional distribution of p- and n-type materials. The combination of Auger electron mapping with Ar GCIB sputtering should thereby allow the construction of 3-dimensional distributions of p- and n-type materials in organic photovoltaic cells.

  6. X-Ray Lines Close to Kll Auger Electron Energies from Iron, Cobalt, Nickel, and Copper Monocrystals

    NASA Astrophysics Data System (ADS)

    Koo, Yeon Deog

    1990-01-01

    By x-ray bombardment of metal monocrystals (Fe, Co, Ni, and Cu), x-rays of KLL radiative Auger electrons (KLL RAE) can be observed on the low energy side of the Kalpha lines. The energies of the x-rays of the KLL RAE of each monocrystal are the same for different lattice planes and when different kinds of x-ray tubes (Mo, W, and Cu) are used. Therefore, the peak energies detected within the KLL Auger electron energy limit are interpreted as KLL RAE x-rays. The measured intensity ratios of KLL/Kalpha are about 0.3%. Additionally, the ratio of I(Kbeta )/I(Kalpha) and I(Si escape peak)/I(Kalpha) are measured. All of these values agree well with theoretical values. The beam shapes of KLL RAE x-rays are studied by taking pictures of x-ray films. The intensity distribution for Ni and Cu are measured by changing the crystal angle with respect to the incident x-ray beam near the Bragg angles of KLL RAE x-rays. It is shown that the KLL RAE x-rays are very sharp and stimulated when the crystal is set at the Bragg angle of the KLL RAE with respect to the incident beam, which contains both the pumping radiation and Bremsstrahlung of the frequencies in the KLL RAE range in which the KLL x-rays stimulation is achieved.

  7. Intrinsic beam emittance of laser-accelerated electrons measured by x-ray spectroscopic imaging.

    PubMed

    Golovin, G; Banerjee, S; Liu, C; Chen, S; Zhang, J; Zhao, B; Zhang, P; Veale, M; Wilson, M; Seller, P; Umstadter, D

    2016-01-01

    The recent combination of ultra-intense lasers and laser-accelerated electron beams is enabling the development of a new generation of compact x-ray light sources, the coherence of which depends directly on electron beam emittance. Although the emittance of accelerated electron beams can be low, it can grow due to the effects of space charge during free-space propagation. Direct experimental measurement of this important property is complicated by micron-scale beam sizes, and the presence of intense fields at the location where space charge acts. Reported here is a novel, non-destructive, single-shot method that overcame this problem. It employed an intense laser probe pulse, and spectroscopic imaging of the inverse-Compton scattered x-rays, allowing measurement of an ultra-low value for the normalized transverse emittance, 0.15 (±0.06) π mm mrad, as well as study of its subsequent growth upon exiting the accelerator. The technique and results are critical for designing multi-stage laser-wakefield accelerators, and generating high-brightness, spatially coherent x-rays. PMID:27090440

  8. Intrinsic beam emittance of laser-accelerated electrons measured by x-ray spectroscopic imaging

    DOE PAGESBeta

    Golovin, G.; Banerjee, S.; Liu, C.; Chen, S.; Zhang, J.; Zhao, B.; Zhang, P.; Veale, M.; Wilson, M.; Seller, P.; et al

    2016-04-19

    Here, the recent combination of ultra-intense lasers and laser-accelerated electron beams is enabling the development of a new generation of compact x-ray light sources, the coherence of which depends directly on electron beam emittance. Although the emittance of accelerated electron beams can be low, it can grow due to the effects of space charge during free-space propagation. Direct experimental measurement of this important property is complicated by micron-scale beam sizes, and the presence of intense fields at the location where space charge acts. Reported here is a novel, non-destructive, single-shot method that overcame this problem. It employed an intense lasermore » probe pulse, and spectroscopic imaging of the inverse-Compton scattered x-rays, allowing measurement of an ultra-low value for the normalized transverse emittance, 0.15 (±0.06) π mm mrad, as well as study of its subsequent growth upon exiting the accelerator. The technique and results are critical for designing multi-stage laser-wakefield accelerators, and generating high-brightness, spatially coherent x-rays.« less

  9. Intrinsic beam emittance of laser-accelerated electrons measured by x-ray spectroscopic imaging

    PubMed Central

    Golovin, G.; Banerjee, S.; Liu, C.; Chen, S.; Zhang, J.; Zhao, B.; Zhang, P.; Veale, M.; Wilson, M.; Seller, P.; Umstadter, D.

    2016-01-01

    The recent combination of ultra-intense lasers and laser-accelerated electron beams is enabling the development of a new generation of compact x-ray light sources, the coherence of which depends directly on electron beam emittance. Although the emittance of accelerated electron beams can be low, it can grow due to the effects of space charge during free-space propagation. Direct experimental measurement of this important property is complicated by micron-scale beam sizes, and the presence of intense fields at the location where space charge acts. Reported here is a novel, non-destructive, single-shot method that overcame this problem. It employed an intense laser probe pulse, and spectroscopic imaging of the inverse-Compton scattered x-rays, allowing measurement of an ultra-low value for the normalized transverse emittance, 0.15 (±0.06) π mm mrad, as well as study of its subsequent growth upon exiting the accelerator. The technique and results are critical for designing multi-stage laser-wakefield accelerators, and generating high-brightness, spatially coherent x-rays. PMID:27090440

  10. Intrinsic beam emittance of laser-accelerated electrons measured by x-ray spectroscopic imaging

    NASA Astrophysics Data System (ADS)

    Golovin, G.; Banerjee, S.; Liu, C.; Chen, S.; Zhang, J.; Zhao, B.; Zhang, P.; Veale, M.; Wilson, M.; Seller, P.; Umstadter, D.

    2016-04-01

    The recent combination of ultra-intense lasers and laser-accelerated electron beams is enabling the development of a new generation of compact x-ray light sources, the coherence of which depends directly on electron beam emittance. Although the emittance of accelerated electron beams can be low, it can grow due to the effects of space charge during free-space propagation. Direct experimental measurement of this important property is complicated by micron-scale beam sizes, and the presence of intense fields at the location where space charge acts. Reported here is a novel, non-destructive, single-shot method that overcame this problem. It employed an intense laser probe pulse, and spectroscopic imaging of the inverse-Compton scattered x-rays, allowing measurement of an ultra-low value for the normalized transverse emittance, 0.15 (±0.06) π mm mrad, as well as study of its subsequent growth upon exiting the accelerator. The technique and results are critical for designing multi-stage laser-wakefield accelerators, and generating high-brightness, spatially coherent x-rays.

  11. Carbon nanotube as a Cherenkov-type light emitter and free electron laser

    SciTech Connect

    Batrakov, K. G.; Maksimenko, S. A.; Kuzhir, P. P.; Thomsen, C.

    2009-03-15

    A mechanism of stimulated emission of electromagnetic radiation by an electron beam in carbon nanotubes is theoretically considered. Three basic properties of carbon nanotubes: a strong slowing down of surface electromagnetic waves, ballisticity of the electron motion over typical nanotube length, and extremely high electron current density reachable in nanotubes, allow proposition of them as candidates for the development of nanoscale Cherenkov-type emitters, analogous to traveling-wave tube and free electron laser. Dispersion equations of the electron-beam instability and the threshold conditions of the stimulated emission have been derived and analyzed, demonstrating realizability of the nanotube-based nano-free electron lasers at realistic parameters of nanotubes and electronic beams.

  12. Experimental Determination of the Dominant Type of Auger Recombination in InGaN Quantum Wells

    NASA Astrophysics Data System (ADS)

    Galler, Bastian; Lugauer, Hans-Jürgen; Binder, Michael; Hollweck, Richard; Folwill, Yannick; Nirschl, Anna; Gomez-Iglesias, Alvaro; Hahn, Berthold; Wagner, Joachim; Sabathil, Matthias

    2013-11-01

    We investigate theoretically the influence of type and density of background carriers in the active region on the quantum efficiency of InGaN-based light emitters using an extension of the ABC rate model. A method to determine experimentally whether a certain type of Auger recombination is relevant in InGaN quantum wells is derived from these considerations. Using this approach, we show that the physical process which is the dominant cause for the efficiency droop is superlinear in the electron density and can thus be assigned to nnp-Auger recombination.

  13. Pointable Auger

    NASA Technical Reports Server (NTRS)

    Lewis, E. V.

    1985-01-01

    Machine drills, crushes, and feeds coal - and seeks out extra-hard inclusions. Auger mounted on gimbal, located at its center of gravity for ease of maneuvering. Opposing hydraulic cylinders cooperate to point auger under control of microprocessor. Its diamond teeth break up coal seam, it crushes coal fed to it by mining machine jaws, and its screw action pushes crushed coal into slurry-forming chamber.

  14. Determination of the solid angle and response function of a hemispherical spectrograph with injection lens for Auger electrons emitted from long lived projectile states

    SciTech Connect

    Doukas, S.; Madesis, I.; Dimitriou, A.; Zouros, T. J. M.; Laoutaris, A.; Benis, E. P.

    2015-04-15

    We present SIMION 8.1 Monte Carlo type simulations of the response function and detection solid angle for long lived Auger states (lifetime τ ∼ 10{sup −9} − 10{sup −5} s) recorded by a hemispherical spectrograph with injection lens and position sensitive detector used for high resolution Auger spectroscopy of ion beams. Also included in these simulations for the first time are kinematic effects particular to Auger emission from fast moving projectile ions such as line broadening and solid angle limitations allowing for a more accurate and realistic line shape modeling. Our results are found to be in excellent agreement with measured electron line shapes of both long lived 1s2s2p{sup 4}P and prompt Auger projectile states formed by electron capture in collisions of 25.3 MeV F{sup 7+} with H{sub 2} and 12.0 MeV C{sup 4+} with Ne recorded at 0{sup ∘} to the beam direction. These results are important for the accurate evaluation of the 1s2s2p {sup 4}P/{sup 2}P ratio of K-Auger cross sections whose observed non-statistical production by electron capture into He-like ions, recently a field of interesting interpretations, awaits further resolution.

  15. Monitoring Ultrafast Chemical Dynamics by Time-Domain X-ray Photo- and Auger-Electron Spectroscopy.

    PubMed

    Gessner, Oliver; Gühr, Markus

    2016-01-19

    The directed flow of charge and energy is at the heart of all chemical processes. Extraordinary efforts are underway to monitor and understand the concerted motion of electrons and nuclei with ever increasing spatial and temporal sensitivity. The element specificity, chemical sensitivity, and temporal resolution of ultrafast X-ray spectroscopy techniques hold great promise to provide new insight into the fundamental interactions underlying chemical dynamics in systems ranging from isolated molecules to application-like devices. Here, we focus on the potential of ultrafast X-ray spectroscopy techniques based on the detection of photo- and Auger electrons to provide new fundamental insight into photochemical processes of systems with various degrees of complexity. Isolated nucleobases provide an excellent testing ground for our most fundamental understanding of intramolecular coupling between electrons and nuclei beyond the traditionally applied Born-Oppenheimer approximation. Ultrafast electronic relaxation dynamics enabled by the breakdown of this approximation is the major component of the nucleobase photoprotection mechanisms. Transient X-ray induced Auger electron spectroscopy on photoexcited thymine molecules provides atomic-site specific details of the extremely efficient coupling that converts potentially bond changing ultraviolet photon energy into benign heat. In particular, the time-dependent spectral shift of a specific Auger band is sensitive to the length of a single bond within the molecule. The X-ray induced Auger transients show evidence for an electronic transition out of the initially excited state within only ∼200 fs in contrast to theoretically predicted picosecond population trapping behind a reaction barrier. Photoinduced charge transfer dynamics between transition metal complexes and semiconductor nanostructures are of central importance for many emerging energy and climate relevant technologies. Numerous demonstrations of photovoltaic and

  16. Highly reliable field electron emitters produced from reproducible damage-free carbon nanotube composite pastes with optimal inorganic fillers.

    PubMed

    Kim, Jae-Woo; Jeong, Jin-Woo; Kang, Jun-Tae; Choi, Sungyoul; Ahn, Seungjoon; Song, Yoon-Ho

    2014-02-14

    Highly reliable field electron emitters were developed using a formulation for reproducible damage-free carbon nanotube (CNT) composite pastes with optimal inorganic fillers and a ball-milling method. We carefully controlled the ball-milling sequence and time to avoid any damage to the CNTs, which incorporated fillers that were fully dispersed as paste constituents. The field electron emitters fabricated by printing the CNT pastes were found to exhibit almost perfect adhesion of the CNT emitters to the cathode, along with good uniformity and reproducibility. A high field enhancement factor of around 10,000 was achieved from the CNT field emitters developed. By selecting nano-sized metal alloys and oxides and using the same formulation sequence, we also developed reliable field emitters that could survive high-temperature post processing. These field emitters had high durability to post vacuum annealing at 950 °C, guaranteeing survival of the brazing process used in the sealing of field emission x-ray tubes. We evaluated the field emitters in a triode configuration in the harsh environment of a tiny vacuum-sealed vessel and observed very reliable operation for 30 h at a high current density of 350 mA cm(-2). The CNT pastes and related field emitters that were developed could be usefully applied in reliable field emission devices. PMID:24434798

  17. Desorption due to Recoil Induced by Neutrino Emission and Auger Relaxation of CHLORINE-37 Following the Electron Capture Decay of ARGON-37.

    NASA Astrophysics Data System (ADS)

    Zhu, Lin

    1995-01-01

    A novel experiment was developed in this work to study the desorption and the Auger relaxation processes of ^{37}Cl following the ^{37}Ar electron capture decay. For the first time, the desorption of ^{37}Cl ions due to recoil induced by neutrino emission in this decay process was observed. The kinetic energy distribution of the desorbing ^{37}Cl ions was accurately measured by using coincidence techniques. The resulting ^{37}Cl ion energy ranges from 5 eV to 13 eV with a maximum at around 9 eV and an FWHM about 3 eV. The charge state distribution of the desorbing ^{37}Cl ions was also measured. The resulting charge state distribution is: 53% of the total ions have charge +e, 21% have charge +2e and 26% have charge +ne, where n >= 3. The desorbing probability of ^ {37}Cl ions was measured by two independent experiments which gave the result of 9.4+/-1.2 %. The energy distribution, the charge state distribution and the desorbing probability of ^{37}Cl ions are all quite different as compared with the expected values for an isolated Cl atom. These differences are explained in the desorption model involving charge exchange and Coulomb repulsion between ^{37}Cl ions and their surrounding atoms. The electron capture decay also creates a highly unusual initial state in the ^{37 }Cl atom which allows direct observation of some novel relaxation processes which are amenable to many body theory, but essentially impossible to probe experimentally with conventional techniques. For the first time, direct evidence of the double Auger decay of a K-hole and the large shift in energy (22 eV) of an LMM Auger line was reported. The double Auger decay probability and energy distribution of the two double Auger electrons were measured by using coincidence techniques. The resulting double Auger decay probability ranges from 12+/-0.3 % to 15+/-0.4% of the total Auger decay. The preferred energy distribution of the double Auger emission is for one of the electrons to take most of the

  18. Low-emittance monoenergetic electron and ion beams from ultra-intense laser-solid interactions

    SciTech Connect

    Cowan, T E; Roth, M; Allen, M M; Johnson, J; Hatchett, S P; Le Sage, G P; Wilks, S C

    2000-03-03

    Recent experiments at the LLNL Petawatt Laser have demonstrated the generation of intense, high energy beams of electrons and ions from the interaction of ultra-intense laser light with solid targets. Focused laser intensities as high as 6 x 10{sup 20} W/cm{sup 2} are achieved, at which point the quiver energies of the target electrons extend to {approx}10 MeV. In this new, fully relativistic regime of laser-plasma interactions, nuclear processes become important and nuclear techniques are required to diagnose the high-energy particle production. In recent experiments we have observed electrons accelerated to 100 MeV, up to 60 MeV brehmsstrahlung generation, photo-nuclear fission and positron-electron pair creation. We also have observed monoenergetic jets of electrons having sufficiently small emittance to be interesting as a laser-accelerated beam, if the production mechanism could be understood and controlled. The huge flux of multi-MeV ponderomotively accelerated electrons produced in the laser-solid interaction is also observed to accelerate contaminant ions from the rear surface of the solid target up to 50 MeV. We describe spectroscopic measurements which reveal intense monoenergetic beam features in the proton energy spectrum. The total spectrum contains >10{sup 13} protons, while the monoenergetic beam pulses contain {approx}1 nC of protons, and exhibits a longitudinal and transverse emittance smaller than conventional RF proton accelerator beams.

  19. Local atomic configuration and Auger Valence Electron Spectra in BiSrCaCuO single crystals

    SciTech Connect

    Fujiwara, Y.; Hirata, S.; Nishikubo, M.; Kobayashi, T. ); Nakayama, H.; Fujita, H. . Faculty of Engineering)

    1991-03-01

    This paper reports on Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub y} (2212) and Ca-doped Bi{sub 2}Sr{sub 2}CuO{sub y} (2201) single crystals systematically investigated by Auger Valence Electron Spectroscopy (AVES). In AVES measurements on two kinds of crystals, a drastic difference was observed in the spectral shape of Ca(2p,3p,3p), reflecting a difference in spin-orbit splitting induced by local atomic configuration in the vicinity of Ca atoms. Furthermore, Ca(2p,3p,4s) spectrum appeared in both the crystals, which indicates that the real valency of Ca atoms is deviated from + 2 in the crystals. These results suggest that AVES is a promising probe for characterizing local atomic configuration and valence electron states of the constituent elements.

  20. Electronic Doppler effect in resonant Auger decay of CO molecules upon excitation near a shake-up {pi} resonance

    SciTech Connect

    Sorensen, S. L.; Kitajima, M.; Tanaka, T.; Hoshino, M.; Tanaka, H.; Tamenori, Y.; Sankari, R.; Piancastelli, M. N.; Ueda, K.; Velkov, Y.; Minkov, I.; Carravetta, V. |; Gel'mukhanov, F. |

    2007-12-15

    We present an experimental observation of the electronic Doppler effect in resonant Auger spectra upon core excitation slightly above the carbon K edge of the CO molecule. Thus the electronic Doppler effect has been identified in above-threshold excitation, and in a transition of {pi} symmetry. Ab initio calculations of the potential energy curves of the relevant states of CO and the wave packet technique have been employed to provide a theoretical background to the experimental studies. The weak feature around 299.4 eV in the photoabsorption spectrum, whose decay has been investigated by the present experiment, is assigned to double (core-valence) excitations to C 1s shake-up states |1s{sub C}{sup -1}1{pi}{sup -1}{pi}*{sup 2}> with a strong dissociative character, and the Doppler splitting of the atomic peak has been reproduced by the simulation.

  1. Flexible electron field emitters fabricated using conducting ultrananocrystalline diamond pyramidal microtips on polynorbornene films

    SciTech Connect

    Sankaran, K. J.; Tai, N. H.; Lin, I. N.

    2014-01-20

    High performance flexible field emitters made of aligned pyramidal shaped conducting ultrananocrystalline diamond (C-UNCD) microtips on polynorbornene substrates is demonstrated. Flexible C-UNCD pyramidal microtips show a low turn-on field of 1.80 V/μm with a field enhancement factor of 4580 and a high emission current density of 5.8 mA/cm{sup 2} (at an applied field of 4.20 V/μm) with life-time stability of 210 min. Such an enhancement in the field emission is due to the presence of sp{sup 2}-graphitic sheath with a nanowire-like diamond core. This high performance flexible C-UNCD field emitter is potentially useful for the fabrication of diverse, flexible electronic devices.

  2. Auger-electron angular distributions calculated without the two-step approximation: Calculation of angle-resolved resonant Auger spectra of C{sub 2}H{sub 2}

    SciTech Connect

    Colle, Renato; Embriaco, Davide; Massini, Michol; Simonucci, Stefano; Taioli, Simone

    2004-10-01

    Analytic expressions for the direct, resonant, and interference contributions to the differential cross section of a resonant Auger process, produced by the inner-shell photoionization of a linear molecule either 'fixed in space' or belonging to a gas of randomly oriented molecules, have been derived following Dill's procedures [Dill et al., Phys. Rev. Lett. 45, 1393 (1980)], but going beyond the two-step approximation. Angle-resolved Auger spectra of the C{sub 2}H{sub 2} molecule measured on top of the C 1s{yields}{pi}* resonance [Kivimaeki et al., J. Phys. B 30, 4279 (1997)] have been calculated together with asymmetry parameters, analyzing also the different contributions to the electron angular distributions.

  3. Low energy electron microscopy and Auger electron spectroscopy studies of Cs-O activation layer on p-type GaAs photocathode

    NASA Astrophysics Data System (ADS)

    Jin, Xiuguang; Cotta, Alexandre A. C.; Chen, Gong; N`Diaye, Alpha T.; Schmid, Andreas K.; Yamamoto, Naoto

    2014-11-01

    Work function, photoemission yield, and Auger electron spectra were measured on (001) p-type GaAs during negative electron affinity (NEA) surface preparation, surface degradation, and heating processes. The emission current sensitively depends on work function change and its dependence allows us to determine that the shape of the vacuum barrier was close to double triangular. Regarding the NEA surface degradation during photoemission, we discuss the importance of residual gas components the oxygen and hydrogen. We also found that gentle annealing (≤100 °C) of aged photocathodes results in a lower work function and may offer a patch to reverse the performance degradation.

  4. Asymmetrical field emitter

    DOEpatents

    Fleming, J.G.; Smith, B.K.

    1995-10-10

    A method is disclosed for providing a field emitter with an asymmetrical emitter structure having a very sharp tip in close proximity to its gate. One preferred embodiment of the present invention includes an asymmetrical emitter and a gate. The emitter having a tip and a side is coupled to a substrate. The gate is connected to a step in the substrate. The step has a top surface and a side wall that is substantially parallel to the side of the emitter. The tip of the emitter is in close proximity to the gate. The emitter is at an emitter potential, and the gate is at a gate potential such that with the two potentials at appropriate values, electrons are emitted from the emitter. In one embodiment, the gate is separated from the emitter by an oxide layer, and the emitter is etched anisotropically to form its tip and its asymmetrical structure. 17 figs.

  5. Single-Particle Dynamics in Electron Storage Rings with Extremely Low Emittance

    SciTech Connect

    Cai, Yunhai; /SLAC

    2011-05-31

    Electron storage rings are widely used for high luminosity colliders, damping rings in high-energy linear colliders, and synchrotron light sources. They have become essential facilities to study high-energy physics and material and medical sciences. To further increase the luminosity of colliders or the brightness of synchrotron light sources, the beam emittance is being continually pushed downward, recently to the nanometer region. In the next decade, another order of reduction is expected. This requirement of ultra-low emittance presents many design challenges in beam dynamics, including better analysis of maps and improvement of dynamic apertures. To meet these challenges, we have refined transfer maps of common elements in storage rings and developed a new method to compute the resonance driving terms as they are built up along a beamline. The method is successfully applied to a design of PEP-X as a future light source with 100-pm emittance. As a result, we discovered many unexpected cancelations of the fourth-order resonance terms driven by sextupoles within an achromat.

  6. Deviations from one-electron behavior in the Ag and Pd M4,5-VV Auger spectra of AgcPd1-c alloys

    NASA Astrophysics Data System (ADS)

    Mariot, J.-M.; Hague, C. F.; Dufour, G.

    1981-04-01

    A systematic investigation of the Ag and Pd M4,5-VV Auger spectra in the pure metals and in the AgcPd1-c(0.1<=c<=0.9) alloys is presented. The shape of the Auger spectra is discussed in relation to the values of the effective Coulomb interaction Ueff between the two holes present in the final state of the Auger transition and of the width W of the one-electron local densities of states as obtained from Lβ2,15 soft-x-ray emission bands. The Auger spectra of Ag in the metal and the alloys have a pronounced quasiatomic character, as can be expected from the Ueff2W ratio which is found to be close to unity. The Auger spectrum of pure Pd (Ueff2W~0.4) can be explained in terms of an atomic model in which strong band effects are present. For alloys with low-Pd content where Pd forms an impurity state, it is shown that final states other than the localized [4d2] two-hole state have to be invoked to explain the line shape.

  7. Electronic state-lifetime interference in resonant Auger spectra: a tool to disentangle overlapping core-excited states.

    PubMed

    Goldsztejn, Gildas; Marchenko, Tatiana; Céolin, Denis; Journel, Loïc; Guillemin, Renaud; Rueff, Jean-Pascal; Kushawaha, Rajesh K; Püttner, Ralph; Piancastelli, Maria Novella; Simon, Marc

    2016-06-01

    We have measured resonant-Auger decay following Cl 1s(-1) excitations in HCl and CH3Cl molecules, and extracted the pseudo-cross sections of different Cl 2p(-2) final states. These cross sections show clear evidence of shake processes as well as contributions of electronic state-lifetime interference (ELI). To describe the spectra we developed a fit approach that takes into account ELI contributions and ultrafast nuclear dynamics in dissociative core-excited states. Using this approach we utilized the ELI contributions to obtain the intensity ratios of the overlapping states Cl 1s(-1)4pπ/1s(-1)4pσ in HCl and Cl 1s(-1)4pe/1s(-1)4pa1 in CH3Cl. The experimental value for HCl is compared with theoretical results showing satisfactory agreement. PMID:27199185

  8. Auger electron spectroscopy for the determination of sex and age related Ca/P ratio at different bone sites

    SciTech Connect

    Balatsoukas, Ioannis; Kourkoumelis, Nikolaos; Tzaphlidou, Margaret

    2010-10-15

    The Ca/P ratio of normal cortical and trabecular rat bone was measured by Auger electron spectroscopy (AES). Semiquantitative analysis was carried out using ratio techniques to draw conclusions on how age, sex and bone site affect the relative composition of calcium and phosphorus. Results show that Ca/P ratio is not sex dependent; quite the opposite, bone sites exhibit variations in elemental stoichiometry where femoral sections demonstrate higher Ca/P ratio than rear and front tibias. Age-related changes are more distinct for cortical bone in comparison with the trabecular bone. The latter's Ca/P ratio remains unaffected from all the parameters under study. This study confirms that AES is able to successfully quantify bone mineral main elements when certain critical points, related to the experimental conditions, are addressed effectively.

  9. Thermal effects in equilibrium surface segregation in a copper/10-atomic-percent-aluminum alloy using Auger electron spectroscopy

    NASA Technical Reports Server (NTRS)

    Ferrante, J.

    1972-01-01

    Equilibrium surface segregation of aluminum in a copper-10-atomic-percent-aluminum single crystal alloy oriented in the /111/ direction was demonstrated by using Auger electron spectroscopy. This crystal was in the solid solution range of composition. Equilibrium surface segregation was verified by observing that the aluminum surface concentration varied reversibly with temperature in the range 550 to 850 K. These results were curve fitted to an expression for equilibrium grain boundary segregation and gave a retrieval energy of 5780 J/mole (1380 cal/mole) and a maximum frozen-in surface coverage three times the bulk layer concentration. Analyses concerning the relative merits of sputtering calibration and the effects of evaporation are also included.

  10. Auger electron spectroscopy study of oxidation of a PdCr alloy used for high-temperature sensors

    NASA Technical Reports Server (NTRS)

    Boyd, Darwin L.; Zeller, Mary V.; Vargas-Aburto, Carlos

    1993-01-01

    A Pd-13 wt. percent Cr solid solution is a promising high-temperature strain gage alloy. In bulk form it has a number of properties that are desirable in a resistance strain gage material, such as a linear electrical resistance versus temperature curve to 1000 C and stable electrical resistance in air at 1000 C. However, unprotected fine wire gages fabricated from this alloy perform well only to 600 C. At higher temperatures severe oxidation degrades their electrical performance. In this work Auger electron spectroscopy was used to study the oxidation chemistry of the alloy wires and ribbons. Results indicate that the oxidation is caused by a complex mechanism that is not yet fully understood. As expected, during oxidation, a layer of chromium oxide is formed. This layer, however, forms beneath a layer of metallic palladium. The results of this study have increased the understanding of the oxidation mechanism of Pd-13 wt. percent Cr.

  11. Auger electron spectroscopy, secondary ion mass spectroscopy and optical characterization of a-C-H and BN films

    NASA Technical Reports Server (NTRS)

    Pouch, J. J.; Alterovitz, S. A.; Warner, J. D.

    1986-01-01

    The amorphous dielectrics a-C:H and BN were deposited on III-V semiconductors. Optical band gaps as high as 3 eV were measured for a-C:H generated by C4H10 plasmas; a comparison was made with bad gaps obtained from films prepared by CH4 glow discharges. The ion beam deposited BN films exhibited amorphous behavior with band gaps on the order of 5 eV. Film compositions were studied by Auger electron spectroscopy (AES), x-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS). The optical properties were characterized by ellipsometry, UV/VIS absorption, and IR reflection and transmission. Etching rates of a-C:H subjected to O2 dicharges were determined.

  12. Auger electron spectroscopy for the determination of sex and age related Ca/P ratio at different bone sites

    NASA Astrophysics Data System (ADS)

    Balatsoukas, Ioannis; Kourkoumelis, Nikolaos; Tzaphlidou, Margaret

    2010-10-01

    The Ca/P ratio of normal cortical and trabecular rat bone was measured by Auger electron spectroscopy (AES). Semiquantitative analysis was carried out using ratio techniques to draw conclusions on how age, sex and bone site affect the relative composition of calcium and phosphorus. Results show that Ca/P ratio is not sex dependent; quite the opposite, bone sites exhibit variations in elemental stoichiometry where femoral sections demonstrate higher Ca/P ratio than rear and front tibias. Age-related changes are more distinct for cortical bone in comparison with the trabecular bone. The latter's Ca/P ratio remains unaffected from all the parameters under study. This study confirms that AES is able to successfully quantify bone mineral main elements when certain critical points, related to the experimental conditions, are addressed effectively.

  13. Auger electron spectroscopy study and depth profile analyses of the CaS:Eu2+ pulsed laser deposited thin luminescent films

    NASA Astrophysics Data System (ADS)

    Nyenge, R. L.; Swart, H. C.; Ntwaeaborwa, O. M.

    2016-06-01

    This paper presents the results of a study of the chemical composition, depth profile analyses of pulsed laser deposited CaS:Eu2+ thin films grown at different substrate temperatures. Using Auger electron spectroscopy, we have shown that the thin film grown in an argon atmosphere shows sulfur deficiency as the substrate temperature is increased from 200 to 650 °C.

  14. Growth and structure of rapid thermal silicon oxides and nitroxides studied by spectroellipsometry and Auger electron spectroscopy

    NASA Astrophysics Data System (ADS)

    Gonon, N.; Gagnaire, A.; Barbier, D.; Glachant, A.

    1994-11-01

    Rapid thermal oxidation of Czochralski-grown silicon in either O2 or N2O atmospheres have been studied using spectroellipsometry and Auger electron spectroscopy. Multiwavelength ellipsometric data were processed in order to separately derive the thickness and refractive indexes of rapid thermal dielectrics. Results revealed a significant increase of the mean refractive index as the film thickness falls below 20 nm for both O2 or N2O oxidant species. A multilayer structure including an about 0.3-nm-thick interfacial region of either SiO(x) or nitroxide in the case of O2 and N2O growth, respectively, followed by a densified SiO2 layer, was found to accurately fit the experimental data. The interfacial region together with the densified state of SiO2 close to the interface suggest a dielectric structure in agreement with the continuous random network model proposed for classical thermal oxides. Auger electron spectroscopy analysis confirmed the presence of noncrystalline Si-Si bonds in the interfacial region, mostly in the case of thin oxides grown in O2. It was speculated that the initial fast growth regime was due to a transient oxygen supersaturation in the interfacial region. Besides, the self-limiting growth in N2O was confirmed and explained in agreement with several recently published data, by the early formation of a very thin nitride or oxynitride membrane in the highly densified oxide beneath the interface. The beneficial effect of direct nitrogen incorporation by rapid thermal oxidation in N2O instead of O2 for the electrical behavior of metal-oxide-semiconductor capacitors is likely a better SiO2/Si lattice accommodation through the reduction of stresses and Si-Si bonds in the interfacial region of the dielectric.

  15. Positron versus electron-beam quality in low emittance storage rings (invited)

    NASA Astrophysics Data System (ADS)

    Marin, P. C.

    1992-01-01

    A brief summary of ion trapping dependence and its effects is first presented. Based on the experience of Super-ACO, the benefits at different stages of commissioning a synchrotron radiation facility with positrons are then reviewed for the running in period and later, for beam physics studies. Most important appears to be the trapping of nonconductive dust particles in electron beams and its consequences: microlosses, reduced lifetime, and beam emittance growth. A simple model based on photoionization and Möller scattering leads to several predictions which have been tested at Super-ACO. Experimental evidences are presented.

  16. The primary test of measuremental system for the actual emittance of relativistic electron beams

    SciTech Connect

    Liang Fu; Tai-bin Du; Xin Chen

    1995-12-31

    Recent, a new measuremental system has been established basically in Tsinghua University PRA. This system is able to measure the lower emittance of the electron beams from the RF accelerators for the FEL. It consists of a scanning magnetic field, a slit, a fluorescent screen, and a TV camera, an image processing system, a CAD 386 computer. Using it an actual phase diagram is obtained for 4-10 Mev electron beams, The principle and structure of the facility were reported in the Proceeding of the 15th FEL Conference. This paper describes the performance of the main components and the results of first measurement for the electron gun and 4Mev standing wave LINAC, Some new suggests are related too.

  17. Development of a MEMS electrostatic condenser lens array for nc-Si surface electron emitters of the Massive Parallel Electron Beam Direct-Write system

    NASA Astrophysics Data System (ADS)

    Kojima, A.; Ikegami, N.; Yoshida, T.; Miyaguchi, H.; Muroyama, M.; Yoshida, S.; Totsu, K.; Koshida, N.; Esashi, M.

    2016-03-01

    Developments of a Micro Electro-Mechanical System (MEMS) electrostatic Condenser Lens Array (CLA) for a Massively Parallel Electron Beam Direct Write (MPEBDW) lithography system are described. The CLA converges parallel electron beams for fine patterning. The structure of the CLA was designed on a basis of analysis by a finite element method (FEM) simulation. The lens was fabricated with precise machining and assembled with a nanocrystalline silicon (nc-Si) electron emitter array as an electron source of MPEBDW. The nc-Si electron emitter has the advantage that a vertical-emitted surface electron beam can be obtained without any extractor electrodes. FEM simulation of electron optics characteristics showed that the size of the electron beam emitted from the electron emitter was reduced to 15% by a radial direction, and the divergence angle is reduced to 1/18.

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

    PubMed

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

    2015-05-13

    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 chemical nature of the trapping mechanism remains largely unidentified. In this study, we determine the density of trap states in CdTe quantum-dot solids both experimentally, using a combination of electrochemical control of the Fermi level with ultrafast transient absorption and time-resolved photoluminescence spectroscopy, and theoretically, via density functional theory calculations. We find a high density of very efficient electron traps centered ∼0.42 eV above the valence band. Electrochemical filling of these traps increases the electron lifetime and the photoluminescence quantum yield by more than an order of magnitude. The trapping rate constant for holes is an order of magnitude lower that for electrons. These observations can be explained by Auger-mediated electron trapping. From density functional theory calculations we infer that the traps are formed by dicoordinated Te atoms at the quantum dot surface. The combination of our unique experimental determination of the density of trap states with the theoretical modeling of the quantum dot surface allows us to identify the trapping mechanism and chemical reaction at play during charge trapping in these quantum dots. PMID:25853555

  19. Ultrafast electron microscopy and diffraction with laser-driven field emitters

    NASA Astrophysics Data System (ADS)

    Ropers, Claus

    2015-03-01

    Ultrafast structural dynamics in solids and nanostructures can be investigated by an increasing number of sophisticated electron and x-ray diffraction techniques. Electrons are particularly suited for this purpose, exhibiting high scattering cross-sections and allowing for beam control by versatile electrostatic or magnetic lens systems. The capabilities of time-resolved electron imaging techniques critically depend on the employed source of laser-driven ultrashort electron pulses. Nanoscopic sources offer exceptional possibilities for the generation of electron probe pulses with very short durations and high spatial beam coherence. In this talk, I will discuss recent progress in the development of ultrafast electron microscopy and diffraction based on nanoscopic photocathodes. In particular, we implemented ultrafast low-energy electron diffraction (ULEED) and ultrafast transmission electron microscopy (UTEM) driven by nonlinear photoemission from field emission tips. ULEED enables the study of structural changes with high temporal resolution and ultimate surface sensitivity, at sub-keV electron energies. As a first application of this technique, we studied the structural phase transition in a stripe-like polymer superstructure on freestanding monolayer graphene. An advanced UTEM instrument was realized by custom modifications of a standard transmission electron microscope, leading to electron focal spot sizes in the microscope's sample plane of about 10 nm and electron pulse durations of less than 700 fs. Utilizing these features, we investigate the quantum-coherent interaction between the ultrashort electron pulse and the optical near-field of an illuminated nanostructure. Finally, further applications and prospects of ultrafast electron imaging, diffraction and spectroscopy using nanoscale field emitters will be discussed.

  20. Development of a miniature double-pass cylindrical mirror electron energy analyzer (DPCMA), and its application to Auger photoelectron coincidence spectroscopy (APECS)

    NASA Astrophysics Data System (ADS)

    Kobayashi, Eiichi; Seo, Junya; Nambu, Akira; Mase, Kazuhiko

    2007-09-01

    We have developed a miniature double-pass cylindrical mirror electron energy analyzer (DPCMA) with an outer diameter of 26 mm. The DPCMA consists of a shield for the electric field, inner and outer cylinders, two pinholes with a diameter of 2.0 mm, and an electron multiplier. By assembling the DPCMA in a coaxially symmetric mirror electron energy analyzer (ASMA) coaxially and confocally we developed an analyzer for Auger photoelectron coincidence spectroscopy (APECS). The performance was estimated by measuring the Si-LVV-Auger Si-1s-photoelectron coincidence spectra of clean Si(1 1 1). The electron-energy resolution of the DPCMA was estimated to be E/Δ E = 20. This value is better than that of the miniature single-pass CMA ( E/Δ E = 12) that was used in the previous APECS analyzer.

  1. Emittance growth due to static and radiative space charge forces in an electron bunch compressor

    NASA Astrophysics Data System (ADS)

    Talman, Richard; Malitsky, Nikolay; Stulle, Frank

    2009-01-01

    Evolution of short intense electron bunches passing through bunch-compressing beam lines is studied using the UAL (Unified Accelerator Libraries) string space charge formulation [R. Talman, Phys. Rev. ST Accel. Beams 7, 100701 (2004)PRABFM1098-440210.1103/PhysRevSTAB.7.100701; N. Malitsky and R. Talman, in Proceedings of the 9th European Particle Accelerator Conference, Lucerne, 2004 (EPS-AG, Lucerne, 2004); R. Talman, Accelerator X-Ray Sources (Wiley-VCH, Weinheim, 2006), Chap. 13]. Three major configurations are studied, with the first most important and studied in greatest detail (because actual experimental results are available and the same results have been simulated with other codes): (i) Experimental bunch compression results were obtained at CTF-II, the CERN test facility for the “Compact Linear Collider” using electrons of about 40 MeV. Previous simulations of these results have been performed (using TraFiC4* [A. Kabel , Nucl. Instrum. Methods Phys. Res., Sect. A 455, 185 (2000)NIMAER0168-900210.1016/S0168-9002(00)00729-4] and ELEGANT [M. Borland, Argonne National Laboratory Report No. LS-287, 2000]). All three simulations are in fair agreement with the data except that the UAL simulation predicts a substantial dependence of horizontal emittance γx on beam width (as controlled by the lattice βx function) at the compressor location. This is consistent with the experimental observations, but inconsistent with other simulations. Excellent agreement concerning dependence of bunch energy loss on bunch length and magnetic field strength [L. Groening , in Proceedings of the Particle Accelerator Conference, Chicago, IL, 2001 (IEEE, New York, 2001), http://groening.home.cern/groening/csr_00.htm] confirms our understanding of the role played by coherent synchrotron radiation (CSR). (ii) A controlled comparison is made between the predictions of the UAL code and those of CSRTrack [M. Dohlus and T. Limberg, in Proceedings of the 2004 FEL Conference, pp. 18

  2. Oxidation study by Auger electron spectroscopy and electron energy-loss spectroscopy of GaSb(001) surfaces grown by molecular-beam epitaxy

    SciTech Connect

    Raisin, C.; Da Silva, F.W.O.; Lassabatere, L. , Place Eugene Bataillon, 34095 Montpellier-Cedex 5, France )

    1990-01-01

    GaSb (001) surfaces were prepared by molecular-beam epitaxy. Auger electron spectroscopy (AES) and electron energy-loss spectroscopy (EELS) are reported for clean surfaces exposed to oxygen, and during the process the ionization gauge of the vacuum system is turned on. Successive stages of chemisorption can be distinguished. For oxygen coverage up to 0.5 monolayer, the surface states are saturated by bonding of the oxygen with Ga and Sb atoms. Sb atoms desorb causing significant Sb depletion in the first layer. Larger exposures further increase the coverage and induce, in the EELS spectra, losses related to O(2{ital p}) and O(2{ital s}) atomic states and new plasmon excitations. In the AES spectra the shift of Auger emission lines which are characteristic of Sb and Ga oxide forms appear; at coverages of about one monolayer back bonds break forming Sb{sub 2}O{sub 3} and Ga{sub 2}O{sub 3}. Further exposures to oxygen result in thicker oxide layers of Ga and Sb.

  3. In-plane carbon nanotube field emitters for high temperature integrated electronics

    NASA Astrophysics Data System (ADS)

    Monica, Andrew Hayes

    Lateral carbon nanotube (CNT)-based field emission devices have been developed for the purpose of fabricating diodes, triodes, and ultimately integrated circuits. The goal of this research is to create CNT-based field emission devices that offer high performance operation in harsh environments, particularly high temperature. Silicon based technologies suffer from an inherent inability to operate at temperatures above ˜300°C; however, a need still exists for such electronics. The devices developed by this research seek to address the need for robust microelectronics capable of wide temperature range operation without the need for elaborate cooling systems. The field emitter structures consist of carbon nanotubes that are created using one of two distinct techniques: dielectrophoretic assembly or thermal chemical vapor deposition synthesis. I will discuss how such techniques can be used to create lateral CNT structures suitable for planar field emission while also enabling complete compatibility with modern semiconductor processing techniques. The electrical and thermal performance results of planar CNT field emitters operating in diode and triode configurations are also reported. Carbon nanotube based field emission devices, such as those I have developed, have characteristics that could result in benefits to an exceedingly wide range of applications beyond operation in harsh environments. High-frequency analog applications are particularly of interest because of the very low capacitances and the high current/unit area capability of typical CNT field emitters, which is in the Amps/cm2 range. Also, since field emitted current is a very strong function of the applied electric field, these devices will undoubtedly find potential use in applications requiring large gain.

  4. On the correlation of the Auger generated hot electron emission and efficiency droop in III-N light-emitting diodes

    SciTech Connect

    Sadi, Toufik; Kivisaari, Pyry; Oksanen, Jani; Tulkki, Jukka

    2014-09-01

    Recent experiments presented in by Iveland et al. [Phys. Rev. Lett. 110, 177406 (2013)] demonstrated that hot electron emission from cesiated p-contacts of III-nitride quantum-well (QW) light-emitting diodes (LEDs) coincides with the onset of the efficiency droop. We have carried out Monte Carlo simulations of hot-electron transport in realistic III-N LEDs. The simulations account for the hole population and all relevant electron scattering and recombination processes. We show that Auger recombination generates a significant hot electron population, which is temporarily trapped in the conduction band side-valleys, without decaying completely before reaching the p-contact. The leakage current due to electron overflow and thermal escape from the QWs is shown to have a minimal impact on the droop. We conclude that the experimentally observed hot electrons are created by Auger recombination in QWs, and that the Auger effect as the origin of the droop is the only consistent explanation for the experimental findings of Iveland et al., [Phys. Rev. Lett. 110, 177406 (2013)].

  5. ANALYSIS OF PASSIVATED SURFACES FOR MASS SPECTROMETER INLET SYSTEMS BY AUGER ELECTRON AND X-RAY PHOTOELECTRON SPECTROSCOPY

    SciTech Connect

    Ajo, H.; Clark, E.

    2010-09-01

    Stainless steel coupons approximately 0.5' in diameter and 0.125' thick were passivated with five different surface treatments and an untreated coupon was left as a control. These surface treatments are being explored for use in tritium storage containers. These coupons were made to allow surface analysis of the surface treatments using well-know surface analysis techniques. Depth profiles using Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) were performed on these coupons to characterize the surface and near surface regions. Scanning electron microscope (SEM) images were collected as well. All of the surface treatments studied here appear to change the surface morphology dramatically, as evidenced by lack of tool marks on the treated samples. In terms of the passivation treatment, Vendors A-D appeared to have oxide layers that were very similar in thickness to each other (0.7-0.9 nm thick) as well as the untreated samples (the untreated sample oxide layers appeared to be somewhat larger). Vendor E's silicon coating appears to be on the order of 200 nm thick.

  6. AMIGA at the Pierre Auger Observatory: The interface and control electronics of the first prototype muon counters

    NASA Astrophysics Data System (ADS)

    Videla, M.; Platino, M.; García, B.; Almela, A.; de la Vega, G.; Lucero, A.; Suarez, F.; Wainberg, O.; Sanchez, F.; Yelos, D.

    2015-08-01

    AMIGA is an enhancement of the Pierre Auger Observatory. The main goals of AMIGA are to extend the full efficiency range to lower energies of the Observatory and to measure the muon content of extensive air showers. Currently, it consists of 61 detector pairs, each one composed of a surface water-Cherenkov detector and a buried muon counter. Prototypes of the muon counter - buried at a depth of 2.25 m - were installed at each vertex of a hexagon and at its center with 750 m spacing. Each prototype has a detection area of 10 m2 segmented in 64 scintillation strips and coupled to a multi-anode PMT through optical fibers. The electronic systems of these prototypes are accessible via a service tube. An electronics interface and control board were designed to extract the data from the counter and to provide a remote control of the system. This article presents the design of the interface and control board and the results and performance during the first AMIGA acquisition period in 2012.

  7. Oxidation of metals and alloys in controlled atmospheres using in situ transmission electron microscopy and Auger spectrography

    NASA Technical Reports Server (NTRS)

    Rao, D. B.; Heinemann, K.; Douglass, D. L.

    1976-01-01

    Single-crystalline thin films of copper were oxidized at an isothermal temperature of 425 C and at an oxygen partial pressure of .005 Torr in situ in a high-resolution electron microscope. The specimens were prepared by epitaxial vapor deposition onto polished 100 and 110 faces of rocksalt and mounted in a hot stage inside an ultra-high-vacuum specimen chamber of the microscope. Large amounts of sulfur, carbon, and oxygen were detected by Auger electron spectroscopy on the surface of the as-received films and were removed in situ by ion-sputter etching immediately prior to the oxidation. The nucleation and growth characteristics of Cu2O on Cu were studied. Results show that neither stacking faults nor dislocations are associated with the Cu2O nucleation sites. The growth of Cu2O nuclei is linear with time. The experimental findings, including results from oxygen dissolution experiments and from repetitive oxidation-reduction-oxidation sequences, fit well into the framework of an oxidation process involving (a) the formation of a surface-charge layer, (b) oxygen saturation in the metal and (c) nucleation, followed by surface diffusion of oxygen and bulk diffusion of copper for lateral and vertical oxide growth, respectively.

  8. The effect of Sr and Bi on the Si(100) surface oxidation - Auger electron spectroscopy, low energy electron diffraction, and X-ray photoelectron spectroscopy study

    NASA Technical Reports Server (NTRS)

    Fan, W. C.; Mesarwi, A.; Ignatiev, A.

    1990-01-01

    The effect of Sr and Bi on the oxidation of the Si(100) surface has been studied by Auger electron spectroscopy, low electron diffraction, and X-ray photoelectron spectroscopy. A dramatic enhancement, by a factor of 10, of the Si oxidation has been observed for Si(100) with a Sr overlayer. The SR-enhanced Si oxidation has been studied as a function of O2 exposure and Sr coverage. In contrast to the oxidation promotion of Sr on Si, it has been also observed that a Bi overlayer on Si(100) reduced Si oxidation significantly. Sr adsorption on the Si(100) with a Bi overlayer enhances Si oxidation only at Sr coverage of greater than 0.3 ML.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  10. Production, PET performance and dosimetric considerations of 134Ce/134La, an Auger electron and positron-emitting generator for radionuclide therapy

    NASA Astrophysics Data System (ADS)

    Lubberink, Mark; Lundqvist, Hans; Tolmachev, Vladimir

    2002-02-01

    We propose the use of the Auger electron and positron-emitting generator 134Ce/134La (half-lives 3.16 d and 6.45 min) for radionuclide therapy. It combines emission of high-energy beta particles with Auger electrons. The high-energy beta particles have similar energies as those emitted by 90Y. Many cancer patients receiving radionuclide therapy have both bulk tumours, which are best treated with high-energy beta particles, and single spread cells or micrometastasis, which are preferably treated with low-energy electrons such as Auger and conversion electrons. Furthermore, the positron-emitting 134La can be used to study kinetics and dosimetry using PET. Production and PET performance were investigated and theoretical dosimetry calculations were made. PET resolution, recovery and quantitative accuracy were slightly degraded for 134La compared to 18F. 134Ce/134La absorbed doses to single cells were higher than absorbed doses from 90Y and 111In. Absorbed doses to spheres representing bulk tumours were almost as high as for 90Y, and a factor 10 higher than for 111In. Whole-body absorbed doses, based on kinetics of the somatostatin analogue octreotide, were higher for 134Ce/134La than for 90Y because of the 134La annihilation photons. This initial study of the therapeutic possibilities of 134Ce/134La is encouraging and justifies further investigations.

  11. Flexible control of femtosecond pulse duration and separation using an emittance-spoiling foil in x-ray free-electron lasers

    SciTech Connect

    Ding, Y.; Behrens, C.; Coffee, R.; Decker, F. -J.; Emma, P.; Field, C.; Helml, W.; Huang, Z.; Krejcik, P.; Krzywinski, J.; Loos, H.; Lutman, A.; Marinelli, A.; Maxwell, T. J.; Turner, J.

    2015-06-22

    We report experimental studies of generating and controlling femtosecond x-ray pulses in free-electron lasers (FELs) using an emittance spoiling foil. By selectivity spoiling the transverse emittance of the electron beam, the output pulse duration or double-pulse separation is adjusted with a variable size single or double slotted foil. Measurements were performed with an X-band transverse deflector located downstream of the FEL undulator, from which both the FEL lasing and emittance spoiling effects are observed directly.

  12. The application of reflected light microscopy, scanning electron microscopy-energy dispersive spectroscopy, Auger electron spectroscopy and electron microprobe analysis to the study of dusts

    SciTech Connect

    Hagni, A.M.; Hagni, R.D. . Dept. of Geology and Geophysics)

    1993-03-01

    Over 500,000 tons of electric arc furnace (EAF) dust is generated each year in the US. The mineralogy and characterization of this dust is being studied to determine the phases and relationships of the valuable zinc, the hazardous lead, cadmium, and chromium, and the deleterious chlorine and fluorine. EAF dust averages 15--20% zinc and is therefore a potential source for 100,000 tons of zinc per year. The major mineralogical phases of EAF dust are franklinite (ZnFe[sub 2]O[sub 4]), magnetite (FeFe[sub 2]O[sub 4]), jacobsite (MnFe[sub 2]O[sub 4]), solid solutions between franklinite-magnetite-jacobsite, and zincite (ZnO). Franklinite, magnetite, and jacobsite solid solutions commonly are cruciform or dendritic crystals in a Ca-Fe-Si matrix and contain up to 5% chromium. Magnetite also occurs as spheres partially oxidized to hematite (Fe[sub 2]O[sub 3]) along its octahedral planes. The dust particles are predominantly in the form of spheres and broken spheres, ranging in size from 200 [mu]m to less than 1 [mu]m. Although many spheres are in the size ranges of 40--50 [mu]m and 10--20 [mu]m, most are less than 1 [mu]m in diameter. Automated scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) probed 118 particles in search of chlorine phases. Chlorine-bearing lime (CaO) was identified by that SEM study. In addition, chlorine is present as hydrophylite (CaCl[sub 2]) and sylvite (KCl). Auger electron spectroscopy (AES) was used to sputter the outer 180[angstrom] layer of the dust particles to search for the possible presence of cotunnite (PbCl[sub 2]) coatings, but none were detected. Minor phases detected include chalcopyrite (CuFeS[sub 2]), sphalerite (ZnS), pyrite (FeS[sub 2]), and coke.

  13. Auger resonant Raman spectroscopy

    SciTech Connect

    Azuma, Y.; LeBrun, T.; MacDonald, M.; Southworth, S.H.

    1995-08-01

    As noted above, traditional spectroscopy of the electronic structure of the inner shells of atoms, molecules, and solids is limited by the lifetime broadening of the core-excited states. This limitation can also be avoided with the non-radiative analog of X-ray Raman scattering - resonant Auger Raman spectroscopy. We have used this technique to study the K-shell excitation spectrum of argon as the photon energy is continuously scanned across threshold.

  14. Dependence of Cell Survival on Iododeoxyuridine Concentration in 35-keV Photon-Activated Auger Electron Radiotherapy

    SciTech Connect

    Dugas, Joseph P.; Varnes, Marie E.; Sajo, Erno; Welch, Christopher E.; Ham, Kyungmin; Hogstrom, Kenneth R.

    2011-01-01

    Purpose: To measure and compare Chinese hamster ovary cell survival curves using monochromatic 35-keV photons and 4-MV x-rays as a function of concentration of the radiosensitizer iododeoxyuridine (IUdR). Methods and Materials: IUdR was incorporated into Chinese hamster ovary cell DNA at 16.6 {+-} 1.9%, 12.0 {+-} 1.4%, and 9.2 {+-} 1.3% thymidine replacement. Cells were irradiated from 1 to 8 Gy with 35-keV synchrotron-generated photons and conventional radiotherapy 4-MV x-rays. The effects of the radiation were measured via clonogenic survival assays. Surviving fraction was plotted vs. dose and fit to a linear quadratic model. Sensitization enhancement ratios (SER{sub 10}) were calculated as the ratio of doses required to achieve 10% surviving fraction for cells without and with DNA-incorporated IUdR. Results: At 4 MV, SER{sub 10} values were 2.6 {+-} 0.1, 2.2 {+-} 0.1, and 1.5 {+-} 0.1 for 16.6%, 12.0%, and 9.2% thymidine replacement, respectively. At 35 keV, SER{sub 10} values were 4.1 {+-} 0.2, 3.0 {+-} 0.1, and 2.0 {+-} 0.1, respectively, which yielded SER{sub 10} ratios (35 keV:4 MV) of 1.6 {+-} 0.1, 1.4 {+-} 0.1, and 1.3 {+-} 0.1, respectively. Conclusions: SER{sub 10} increases monotonically with percent thymidine replacement by IUdR for both modalities. As compared to 4-MV x-rays, 35-keV photons produce enhanced SER{sub 10} values whose ratios are linear with percent thymidine replacement and assumed to be due to Auger electrons contributing to enhanced dose to DNA. Although this Auger effectiveness factor is less than the radiosensitization factor of IUdR, both could be important for the clinical efficacy of IUdR radiotherapy.

  15. A detailed Auger electron spectroscopy study of the first stages of the growth of C60 thin films

    NASA Astrophysics Data System (ADS)

    Vidal, R. A.; Ferrón, J.

    2015-11-01

    In this work we take advantage of the large sensitivity and in-depth resolution of Auger electron spectroscopy (AES) to study in a detailed way the growth of C60 over different substrates, namely Cu(1 1 1), Si(1 0 0) and graphene. The ability of AES, as compared to more local probes like STM or AFM, to follow the process in a dynamic way, allows us to study the growth of C60 below and over one ML, including the change of C60 over either Si or Cu to the growth of C60 over a C60 film. We found that the growth always proceeds layer by layer. This result shows that differences in diffusion barriers are not as important as one may think following the idea of diffusion by a jumping mechanism. We propose that the sticking coefficient, governed by the adsorption energy, is responsible for the differences observed between Cu and Si. Our results also point to a different charge transfer among fullerene molecules and these surfaces. The same result is suggested in the case of C60 over graphene, but in this case our conclusion comes from the variable temperature experiments.

  16. Limit of validity of the thermionic-field-emission treatment of electron injection across emitter-base junctions in abrupt heterojunction bipolar transistors

    NASA Astrophysics Data System (ADS)

    Kumar, T.; Cahay, M.; Shi, S.; Roenker, K.; Stanchina, W. E.

    1995-06-01

    A hybrid model is developed to simulate electron transport through the emitter-base heterojunction and the base region of abrupt heterojunction bipolar transistors. The energy distribution of the injected electron flux through the emitter-base junction is calculated using a rigorous quantum-mechanical treatment of electron tunneling and thermionic emission across the spike at the emitter-base junction. The results are compared with those predicted by the conventional thermionic-field-emission model. For both models, the electron fluxes injected across the emitter-base junction are used as initial energy distributions in a regional Monte Carlo calculation to model electron transport through the base. The average base transit times are calculated using the impulse response technique as a function of the emitter-base voltage. The differences between the thermionic-field-emission model and the rigorous quantum-mechanical approaches to model electron transport through abrupt heterojunction bipolar transistors are pointed out.

  17. Ion emittance growth due to focusing modulation from slipping electron bunch

    SciTech Connect

    Wang, G.

    2015-02-17

    Low energy RHIC operation has to be operated at an energy ranging from γ = 4.1 to γ = 10. The energy variation causes the change of revolution frequency. While the rf system for the circulating ion will operate at an exact harmonic of the revolution frequency (h=60 for 4.5 MHz rf and h=360 for 28 MHz rf.), the superconducting rf system for the cooling electron beam does not have a frequency tuning range that is wide enough to cover the required changes of revolution frequency. As a result, electron bunches will sit at different locations along the ion bunch from turn to turn, i.e. the slipping of the electron bunch with respect to the circulating ion bunch. At cooling section, ions see a coherent focusing force due to the electrons’ space charge, which differs from turn to turn due to the slipping. We will try to estimate how this irregular focusing affects the transverse emittance of the ion bunch.

  18. Effects of pulse-length and emitter area on virtual cathode formation in electron guns

    NASA Astrophysics Data System (ADS)

    Valfells, Ágúst; Feldman, D. W.; Virgo, M.; O'Shea, P. G.; Lau, Y. Y.

    2002-05-01

    Recent experiments at the University of Maryland using photoemission from a dispenser cathode have yielded some interesting results regarding the effects of the area of emission and of the ratio between the pulse length and the gap transit time on the amount of current that may be drawn from an electron gun before a virtual cathode forms. The experiments show that a much higher current density may be drawn from a short pulse or limited emitter area than is anticipated by the Child-Langmuir limiting current. There is also evidence that the current may be increased even after virtual cathode formation, which leads a distinction between a limiting current density and a current density critical for virtual cathode formation. The experiments have also yielded some interesting results on the longitudinal structure of the current pulse passed through the anode. Some empirical and theoretical scaling laws regarding the formation of virtual cathodes in an electron gun will be presented. This work was motivated by the needs of the University of Maryland Electron Ring (UMER) [P. G. O'Shea, M. Reiser, R. A. Kishek et al., Nucl. Instrum. Methods Phys. Res. A 464, 646 (2001)] where the goal is to generate pulses that are well-localized in time and space.

  19. Characterization of the heavily doped emitter and junction regions of silicon solar cells using an electron beam

    NASA Technical Reports Server (NTRS)

    Luke, K. L.; Cheng, L.-J.

    1986-01-01

    Heavily doped emitter and junction regions of silicon solar cells are investigated by means of the electron-beam-induced-current (EBIC) technique. Although the experimental EBIC data are collected under three-dimensional conditions, it is analytically demonstrated with two numerical examples that the solutions obtained with one-dimensional numerical modeling are adequate. EBIC data for bare and oxide-covered emitter surfaces are compared with theory. The improvement in collection efficiency when an emitter surface is covered with a 100-A SiO2 film varies with beam energy; for a cell with a junction depth of 0.35 microns, the improvement is about 54 percent at 2 keV.

  20. A metal-insulator-metal electron emitter based on a porous Al{sub 2}O{sub 3} film

    SciTech Connect

    Xue, Tao; Liang, Zhi-Hu Zhang, Xiao-Ning; Liu, Chun-Liang

    2015-04-20

    A metal-insulator-metal electron emitter containing a sandwiched insulator layer composed of porous aluminum oxide Al{sub 2}O{sub 3} was fabricated. The electron emission characteristics of the electron emitter were investigated under vacuum and xenon. Treatment with H{sub 3}PO{sub 4} and rapid thermal oxidation increased the electric field inside the insulator and improved the quality of porous Al{sub 2}O{sub 3}, resulting in higher efficiency and less fluctuation of electron emission. The maximum current and efficiency of electron emission reached 1.05 mA/cm{sup 2} and 51.2%, respectively, under a pressure of 1.0×10{sup −4} Pa. In addition, electrons were injected into xenon and 147 nm vacuum ultraviolet emission was detected in xenon at a pressure of 5.0 × 10{sup 2 }Pa. This electron emitter has a great potential for use as an ultraviolet radiation source.

  1. Theory and simulation of emittance, space charge and electron pressure effects on focusing of neutralized ion beams

    SciTech Connect

    Lemons, D.S.; Jones, M.E.

    1986-01-01

    We investigate the final focus mode characterized by warm comoving electrons and vacuum propagation. In particular, we extend a previous envelope equation analysis of ion focusing in this mode to include the effects of ion emittance as well as ion space charge and initial electron temperature. Our major result is a simple equation relating initial R/sub o/ and final R/sub f/ beam radii to ion emittance epsilon and perveance K and electron Debye length lambda/sub D/ which is supported by one dimensional, electrostatic, particle-in-cell simulations of radial ion focusing. Finally, we use this equation to find the allowed temperature of neutralizing electrons for typical Heavy Ion Fusion reactor and High Temperature Experiment scenarios.

  2. Diamond fiber field emitters

    DOEpatents

    Blanchet-Fincher, Graciela B.; Coates, Don M.; Devlin, David J.; Eaton, David F.; Silzars, Aris K.; Valone, Steven M.

    1996-01-01

    A field emission electron emitter comprising an electrode formed of at least one diamond, diamond-like carbon or glassy carbon composite fiber, said composite fiber having a non-diamond core and a diamond, diamond-like carbon or glassy carbon coating on said non-diamond core, and electronic devices employing such a field emission electron emitter.

  3. Planar ultrananocrystalline diamond field emitter in accelerator radio frequency electron injector: Performance metrics

    SciTech Connect

    Baryshev, Sergey V. Antipov, Sergey; Jing, Chunguang; Qiu, Jiaqi; Shao, Jiahang; Liu, Wanming; Gai, Wei; Pérez Quintero, Kenneth J.; Sumant, Anirudha V.; Kanareykin, Alexei D.

    2014-11-17

    A case performance study of a planar field emission cathode (FEC) based on nitrogen-incorporated ultrananocrystalline diamond, (N)UNCD, was carried out in an RF 1.3 GHz electron gun. The FEC was a 100 nm (N)UNCD film grown on a 20 mm diameter stainless steel disk with a Mo buffer layer. At surface gradients 45–65 MV/m, peak currents of 1–80 mA (equivalent to 0.3–25 mA/cm{sup 2}) were achieved. Imaging with two YAG screens confirmed emission from the (N)UNCD surface with (1) the beam emittance of 1.5 mm × mrad/mm-rms and (2) longitudinal FWHM and rms widths of non-Gaussian energy spread of 0.7% and 11% at an electron energy of 2 MeV. Current stability was tested over the course of 36 × 10{sup 3} RF pulses (equivalent to 288 × 10{sup 6 }GHz oscillations)

  4. Nanodosimetry of Auger electrons: A case study from the decay of 125I and 0–18-eV electron stopping cross sections of cytosine

    PubMed Central

    Michaud, M.; Bazin, M.; Sanche, L.

    2013-01-01

    Radiopharmaceuticals emitting Auger electrons are often injected into patients undergoing cancer treatment with targeted radionuclide therapy (TRT). In this type of radiotherapy, the radiation source is radial and most of the emitted primary particles are low-energy electrons (LEEs) having kinetic energies distributed mostly from zero to a few hundred electron volts with very short ranges in biological media. These LEEs generate a high density of energy deposits and clustered damage, thus offering a relative biological effectiveness comparable to that of alpha particles. In this paper, we present a simple model and corresponding measurements to assess the energy deposited near the site of the radiopharmaceuticals in TRT. As an example, a calculation is performed for the decay of a single 125I radionuclide surrounded by a 1-nm-radius spherical shell of cytosine molecules using the energy spectrum of LEEs emitted by 125I along with their stopping cross sections between 0 and 18 eV. The dose absorbed by the cytosine shell, which occupies a volume of 4 nm3, is extremely high. It amounts to 79 kGy per decay of which 3%, 39%, and 58% is attributed to vibrational excitations, electronic excitations, and ionization processes, respectively. PMID:24976798

  5. Nanodosimetry of Auger electrons: A case study from the decay of (125)I and 0-18-eV electron stopping cross sections of cytosine.

    PubMed

    Michaud, M; Bazin, M; Sanche, L

    2013-03-01

    Radiopharmaceuticals emitting Auger electrons are often injected into patients undergoing cancer treatment with targeted radionuclide therapy (TRT). In this type of radiotherapy, the radiation source is radial and most of the emitted primary particles are low-energy electrons (LEEs) having kinetic energies distributed mostly from zero to a few hundred electron volts with very short ranges in biological media. These LEEs generate a high density of energy deposits and clustered damage, thus offering a relative biological effectiveness comparable to that of alpha particles. In this paper, we present a simple model and corresponding measurements to assess the energy deposited near the site of the radiopharmaceuticals in TRT. As an example, a calculation is performed for the decay of a single (125)I radionuclide surrounded by a 1-nm-radius spherical shell of cytosine molecules using the energy spectrum of LEEs emitted by (125)I along with their stopping cross sections between 0 and 18 eV. The dose absorbed by the cytosine shell, which occupies a volume of 4 nm(3), is extremely high. It amounts to 79 kGy per decay of which 3%, 39%, and 58% is attributed to vibrational excitations, electronic excitations, and ionization processes, respectively. PMID:24976798

  6. Nanodosimetry of Auger electrons: A case study from the decay of 125I and 0-18-eV electron stopping cross sections of cytosine

    NASA Astrophysics Data System (ADS)

    Michaud, M.; Bazin, M.; Sanche, L.

    2013-03-01

    Radiopharmaceuticals emitting Auger electrons are often injected into patients undergoing cancer treatment with targeted radionuclide therapy (TRT). In this type of radiotherapy, the radiation source is radial and most of the emitted primary particles are low-energy electrons (LEEs) having kinetic energies distributed mostly from zero to a few hundred electron volts with very short ranges in biological media. These LEEs generate a high density of energy deposits and clustered damage, thus offering a relative biological effectiveness comparable to that of alpha particles. In this paper, we present a simple model and corresponding measurements to assess the energy deposited near the site of the radiopharmaceuticals in TRT. As an example, a calculation is performed for the decay of a single 125I radionuclide surrounded by a 1-nm-radius spherical shell of cytosine molecules using the energy spectrum of LEEs emitted by 125I along with their stopping cross sections between 0 and 18 eV. The dose absorbed by the cytosine shell, which occupies a volume of 4 nm3, is extremely high. It amounts to 79 kGy per decay of which 3%, 39%, and 58% is attributed to vibrational excitations, electronic excitations, and ionization processes, respectively.

  7. Auger Recombination in Self-Assembled Quantum Dots: Quenching and Broadening of the Charged Exciton Transition.

    PubMed

    Kurzmann, Annika; Ludwig, Arne; Wieck, Andreas D; Lorke, Axel; Geller, Martin

    2016-05-11

    In quantum dots (QDs), the Auger recombination is a nonradiative process in which the electron-hole recombination energy is transferred to an additional carrier. It has been studied mostly in colloidal QDs, where the Auger recombination time is in the picosecond range and efficiently quenches the light emission. In self-assembled QDs, on the other hand, the influence of Auger recombination on the optical properties is in general neglected, assuming that it is masked by other processes such as spin and charge fluctuations. Here, we use time-resolved resonance fluorescence to analyze the Auger recombination and its influence on the optical properties of a single self-assembled QD. From excitation-power-dependent measurements, we find a long Auger recombination time of about 500 ns and a quenching of the trion transition by about 80%. Furthermore, we observe a broadening of the trion transition line width by up to a factor of 2. With a model based on rate equations, we are able to identify the interplay between tunneling and Auger rate as the underlying mechanism for the reduced intensity and the broadening of the line width. This demonstrates that self-assembled QDs can serve as an ideal model system to study how the charge recapture process, given by the band-structure surrounding the confined carriers, influences the Auger process. Our findings are not only relevant for improving the emission properties of colloidal QD-based emitters and dyes, which have recently entered the consumer market, but also of interest for more visionary applications, such as quantum information technologies, based on self-assembled quantum dots. PMID:27087053

  8. Auger Recombination in Self-Assembled Quantum Dots: Quenching and Broadening of the Charged Exciton Transition

    NASA Astrophysics Data System (ADS)

    Kurzmann, Annika; Ludwig, Arne; Wieck, Andreas D.; Lorke, Axel; Geller, Martin

    2016-05-01

    In quantum dots (QDs) the Auger recombination is a non-radiative process, where the electron-hole recombination energy is transferred to an additional carrier. It has been studied mostly in colloidal QDs, where the Auger recombination time is in the ps range and efficiently quenches the light emission. In self-assembled QDs, on the other hand, the influence of Auger recombination on the optical properties is in general neglected, assuming that it is masked by other processes such as spin and charge fluctuations. Here, we use time-resolved resonance fluorescence to analyze the Auger recombination and its influence on the optical properties of a single self-assembled QD. From excitation-power dependent measurements, we find a long Auger recombination time of about 500 ns and a quenching of the trion transition by about 80 percent. Furthermore, we observe a broadening of the trion transition linewidth by up to a factor of two. With a model based on rate equations, we are able to identify the interplay between tunneling and Auger rate as the underlying mechanism for the reduced intensity and the broadening of the linewidth. This demonstrates that self-assembled QDs can serve as an ideal model system to study how the charge recapture process, given by the band-structure surrounding the confined carriers, influences the Auger process. Our findings are not only relevant for improving the emission properties of colloidal QD-based emitters and dyes, which have recently entered the consumer market. They are also of interest for more visionary applications, such as quantum information technologies, based on self-assembled quantum dots.

  9. Evaluation of two (125)I-radiolabeled acridine derivatives for Auger-electron radionuclide therapy of melanoma.

    PubMed

    Gardette, Maryline; Viallard, Claire; Paillas, Salomé; Guerquin-Kern, Jean-Luc; Papon, Janine; Moins, Nicole; Labarre, Pierre; Desbois, Nicolas; Wong-Wah-Chung, Pascal; Palle, Sabine; Wu, Ting-Di; Pouget, Jean-Pierre; Miot-Noirault, Elisabeth; Chezal, Jean-Michel; Degoul, Francoise

    2014-08-01

    We previously selected two melanin-targeting radioligands [(125)I]ICF01035 and [(125)I]ICF01040 for melanoma-targeted (125)I radionuclide therapy according to their pharmacological profile in mice bearing B16F0 tumors. Here we demonstrate in vitro that these compounds present different radiotoxicities in relation to melanin and acidic vesicle contents in B16F0, B16F0 PTU and A375 cell lines. ICF01035 is effectively observed in nuclei of achromic (A375) melanoma or in melanosomes of melanized melanoma (B16F0), while ICF01040 stays in cytoplasmic vesicles in both cells. [(125)I]ICF01035 induced a similar survival fraction (A50) in all cell lines and led to a significant decrease in S-phase cells in amelanotic cell lines. [(125)I]ICF01040 induced a higher A50 in B16 cell lines compared to [(125)I]ICF01035 ones. [(125)I]ICF01040 induced a G2/M blockade in both A375 and B16F0 PTU, associated with its presence in cytoplasmic acidic vesicles. These results suggest that the radiotoxicity of [(125)I]ICF01035 and [(125)I]ICF01040 are not exclusively reliant on DNA alterations compatible with γ rays but likely result from local dose deposition (Auger electrons) leading to toxic compound leaks from acidic vesicles. In vivo, [(125)I]ICF01035 significantly reduced the number of B16F0 lung colonies, enabling a significant increase in survival of the treated mice. Targeting melanosomes or acidic vesicles is thus an option for future melanoma therapy. PMID:24691673

  10. Impact of IUdR on Rat 9L glioma cell survival for 25-35 keV photon-activated auger electron therapy.

    PubMed

    Alvarez, Diane; Hogstrom, Kenneth R; Brown, Thomas A D; Ii, Kenneth L Matthews; Dugas, Joseph P; Ham, Kyungmin; Varnes, Marie E

    2014-12-01

    The goal of the current study was to measure the energy dependence of survival of rat 9L glioma cells labeled with iododeoxyuridine (IUdR) that underwent photon-activated Auger electron therapy using 25-35 keV monochromatic X rays, i.e., above and below the K-edge energy of iodine. Rat 9L glioma cells were selected because of their radioresistance, ability to be implanted for future in vivo studies and analogy to radioresistant human gliomas. Survival curves were measured for a 4 MV X-ray beam and synchrotron produced monochromatic 35, 30 and 25 keV X-ray beams. IUdR was incorporated into the DNA at levels of 0, 9 and 18% thymidine replacement for 4 MV and 35 keV and 0 and 18% thymidine replacement for 30 and 25 keV. For 10 combinations of beam energy and thymidine replacement, 62 data sets (3-13 per combination) provided 776 data points (47-148 per combination). Survival versus dose data taken for the same combination, but on different days, were merged by including the zero-dose points in the nonlinear, chi-squared data fitting using the linear-quadratic model and letting the best estimate to the zero-dose plating efficiency for each of the different days be a fitting parameter. When comparing two survival curves, the ratio of doses resulting in 10% survival gave sensitization enhancement ratios (SER10) from which contributions due to linear energy transfer (LET) (SER10,LET), IUdR radiosensitization (SER10,RS), the Auger effect (SER10,AE) and the total of all effects (SER10,T) were determined. At 4 MV and 35, 30 and 25 keV, SER10,LET values were 1.00, 1.08 ± 0.03, 1.22 ± 0.02 and 1.37 ± 0.02, respectively. At 4 MV SER10,RS values for 9 and 18% IUdR were 1.28 ± 0.02 and 1.40 ± 0.02, respectively. Assuming LET effects were independent of percentage IUdR and radiosensitization effects were independent of energy, SER10,AE values for 18% IUdR at 35, 30 and 25 keV were 1.35 ± 0.05, 1.06 ± 0.03 and 0.98 ± 0.03, respectively. The value for 9% IUdR at 35 keV was 1

  11. Resonant Auger studies of metallic systems

    SciTech Connect

    Coulthard, I.; Antel, W. J., Jr.; Frigo, S. P.; Freeland, J. W.; Moore, J.; Calaway, W. S.; Pellin, M. J.; Mendelsohn, M.; Sham, T. K.; Naftel, S. J.; Stampfl, A. P. J.

    1999-10-21

    Results of resonant Auger spectroscopy experiments are presented for Cu, Co, and oxidized Al. Sub-lifetime narrowing of Auger spectra and generation of sub-lifetime narrowed absorption spectra constructed from Auger yield measurements, were observed. Resonant Auger yields are used to identify three valence states of oxidized Al. Partial absorption yield spectra were derived giving detailed electronic information and thickness information for the various chemical states of the bulk metal, the passivating aluminum oxide layer, and the metal-oxide interface region. In addition, the total absorption yield spectrum for the oxidized Al sample was constructed from the partial yield data, supporting the consistency of the authors method.

  12. Space-charged-induced emittance growth in the transport of high-brightness electron beams

    SciTech Connect

    Jones, M.E.; Carlsten, B.E.

    1987-03-01

    The emittance induced by space charge in a drifting beam of finite length has been investigated, and a scaling law has been obtained from simple considerations of the different rates of expansion of different portions of the beam. The scaling law predicts the initial rate of emittance growth, before the beam shape has distorted significantly, and thus represents an upper bound on the rate of emittance increase. This scaling law has been substantiated by particle-in-cell simulation and the dependence on geometric factors evaluated for specific choices of the beam profile. For long, axially nonuniform beams, the geometric factors have been evaluated explicitly for Gaussian profiles, and other shapes.

  13. Experimental generation of longitudinally-modulated electron beams using an emittance exchange technique

    SciTech Connect

    Sun, Y.-E; Piot, P.; Johnson, A.; Lumpkin, A.; Maxwell, T.; Ruan, J.; Thurman-Keup, R.; /FERMILAB

    2010-08-01

    We report our experimental demonstration of longitudinal phase space modulation using a transverse-to-longitudinal emittance exchange technique. The experiment is carried out at the A0 photoinjector at Fermi National Accelerator Lab. A vertical multi-slit plate is inserted into the beamline prior to the emittance exchange, thus introducing beam horizontal profile modulation. After the emittance exchange, the longitudinal phase space coordinates (energy and time structures) of the beam are modulated accordingly. This is a clear demonstration of the transverse-to-longitudinal phase space exchange. In this paper, we present our experimental results on the measurement of energy profile as well as numerical simulations of the experiment.

  14. Structure of the initial stages of oxidation of A1{111} surfaces from low-energy-electron diffraction and Auger electron spectroscopy

    NASA Astrophysics Data System (ADS)

    Soria, F.; Martínez, V.; Muñoz, M. C.; Sacedón, J. L.

    1981-12-01

    The structure of the initial stages of oxidation of A1{111} surfaces has been determined by low-energy-electron diffraction (LEED) and Auger-electron-spectroscopy (AES) measurements. The oxidation process can be described by a four-stage mechanism depending on the oxygen exposure: 0-30 L; 30-100 L; 100-200 L; and 200 onwards. At the end of the first stage, the transition density of states (TDOS) obtained by self-deconvolution of the A1{111} -25-L RT O2-exposure L2,3VV AES spectra and comparison with theoretical calculations of the DOS for this coverage show that the oxygen atoms occupy the fcc threefold hollows in an underlayer configuration, with an interplanar distance d12=0.0-0.5 Å. At 100-L RT O2 exposure, AES and LEED indicate the formation of a complete A1{111} 1 × 1-O overlayer structure with the oxygen atoms occupying the fcc threefold hollows at d12=0.73+/-0.05 Å. At 150 L, d12=0.80+/-0.03 Å for the same A1{111} 1 × 1-O structure. These LEED values solve the discrepancy with the surface-extended x-ray-absorption fine-structure measurements, and suggest the need for a revision of interplanar distances previously determined by LEED for oxygen-metal structures.

  15. Analysis of passivated A-286 stainless steel surfaces for mass spectrometer inlet systems by Auger electron and X-ray photoelectron spectroscopy and scanning electron microscopy

    SciTech Connect

    Ajo, Henry; Blankenship, Donnie; Clark, Elliot

    2014-07-25

    In this study, various commercially available surface treatments are being explored for use on stainless steel components in mass spectrometer inlet systems. Type A-286 stainless steel coupons, approximately 12.5 mm in diameter and 3 mm thick, were passivated with one of five different surface treatments; an untreated coupon served as a control. The surface and near-surface microstructure and chemistry of the coupons were investigated using sputter depth profiling using Auger electron spectroscopy, x-ray photoelectron spectroscopy, and scanning electron microscopy (SEM). All the surface treatments studied appeared to change the surface morphology dramatically, as evidenced by lack of tool marks on the treated samples in SEM images. In terms of the passivation treatment, Vendors A-D appeared to have oxide layers that were very similar in thickness to each other (0.7–0.9 nm thick), as well as to the untreated samples (the untreated sample oxide layers appeared to be somewhat larger). Vendor E’s silicon coating appears to be on the order of 200 nm thick.

  16. Analysis of passivated A-286 stainless steel surfaces for mass spectrometer inlet systems by Auger electron and X-ray photoelectron spectroscopy and scanning electron microscopy

    DOE PAGESBeta

    Ajo, Henry; Blankenship, Donnie; Clark, Elliot

    2014-07-25

    In this study, various commercially available surface treatments are being explored for use on stainless steel components in mass spectrometer inlet systems. Type A-286 stainless steel coupons, approximately 12.5 mm in diameter and 3 mm thick, were passivated with one of five different surface treatments; an untreated coupon served as a control. The surface and near-surface microstructure and chemistry of the coupons were investigated using sputter depth profiling using Auger electron spectroscopy, x-ray photoelectron spectroscopy, and scanning electron microscopy (SEM). All the surface treatments studied appeared to change the surface morphology dramatically, as evidenced by lack of tool marks onmore » the treated samples in SEM images. In terms of the passivation treatment, Vendors A-D appeared to have oxide layers that were very similar in thickness to each other (0.7–0.9 nm thick), as well as to the untreated samples (the untreated sample oxide layers appeared to be somewhat larger). Vendor E’s silicon coating appears to be on the order of 200 nm thick.« less

  17. Current gain above 10 in sub-10 nm base III-Nitride tunneling hot electron transistors with GaN/AlN emitter

    NASA Astrophysics Data System (ADS)

    Yang, Zhichao; Zhang, Yuewei; Krishnamoorthy, Sriram; Nath, Digbijoy N.; Khurgin, Jacob B.; Rajan, Siddharth

    2016-05-01

    We report on a tunneling hot electron transistor amplifier with common-emitter current gain greater than 10 at a collector current density in excess of 40 kA/cm2. The use of a wide-bandgap GaN/AlN (111 nm/2.5 nm) emitter was found to greatly improve injection efficiency of the emitter and reduce cold electron leakage. With an ultra-thin (8 nm) base, 93% of the injected hot electrons were collected, enabling a common-emitter current gain up to 14.5. This work improves understanding of the quasi-ballistic hot electron transport and may impact the development of high speed devices based on unipolar hot electron transport.

  18. Investigations of the emittance and brightness of ion beams from an electron beam ion source of the Dresden EBIS type

    SciTech Connect

    Silze, Alexandra; Ritter, Erik; Zschornack, Guenter; Schwan, Andreas; Ullmann, Falk

    2010-02-15

    We have characterized ion beams extracted from the Dresden EBIS-A, a compact room-temperature electron beam ion source (EBIS) with a permanent magnet system for electron beam compression, using a pepper-pot emittance meter. The EBIS-A is the precursor to the Dresden EBIS-SC in which the permanent magnets have been replaced by superconducting solenoids for the use of the source in high-ion-current applications such as heavy-ion cancer therapy. Beam emittance and brightness values were calculated from data sets acquired for a variety of source parameters, in leaky as well as pulsed ion extraction mode. With box shaped pulses of C{sup 4+} ions at an energy of 39 keV root mean square emittances of 1-4 mm mrad and a brightness of 10 nA mm{sup -2} mrad{sup -2} were achieved. The results meet the expectations for high quality ion beams generated by an electron beam ion source.

  19. Site-dependent Si KL{sub 23}L{sub 23} resonant Auger electron spectra following inner-shell excitation of Cl{sub 3}SiSi(CH{sub 3}){sub 3}

    SciTech Connect

    Suzuki, Isao H.; Endo, Hikari; Nagai, Kanae; Nagaoka, Shin-ichi; Takahashi, Osamu; Tamenori, Yusuke

    2013-11-07

    Spectator resonant Auger electron spectra with the Si 1s photoexcitation of Cl{sub 3}SiSi(CH{sub 3}){sub 3} have been measured using an electron spectroscopic technique combined with undulator radiation. The transition with the highest intensity in the total ion yield (TIY) spectrum, coming from excitation of a Si 1s electron on the Cl-side into a vacant valence orbital, generates the resonant Auger decay in which the excited electron remains in this valence orbital. Photoexcitation of 1s electrons into some Rydberg orbitals induces Auger shake-down transitions, because higher-lying Rydberg orbitals in the two Si atoms closely positioned hold spatially overlapping considerably. A broad TIY peak slightly above the 1s ionization thresholds appreciably yields resonant Auger decays in which a slow photoelectron is re-captured into a higher-lying Rydberg orbital. The normal Auger peak shape at this photon energy is distorted due to a post-collision interaction effect. These findings provide a clear understanding on properties of the excited orbitals which are ambiguous in the measurement of the TIY only.

  20. Two-photon photoemission study of competing Auger and surface-mediated relaxation of hot electrons in CdSe quantum dot solids.

    PubMed

    Sippel, Philipp; Albrecht, Wiebke; Mitoraj, Dariusz; Eichberger, Rainer; Hannappel, Thomas; Vanmaekelbergh, Daniel

    2013-04-10

    Solids composed of colloidal quantum dots hold promise for third generation highly efficient thin-film photovoltaic cells. The presence of well-separated conduction electron states opens the possibility for an energy-selective collection of hot and equilibrated carriers, pushing the efficiency above the one-band gap limit. However, in order to reach this goal the decay of hot carriers within a band must be better understood and prevented, eventually. Here, we present a two-photon photoemission study of the 1Pe→1Se intraband relaxation dynamics in a CdSe quantum dot solid that mimics the active layer in a photovoltaic cell. We observe fast hot electron relaxation from the 1Pe to the 1Se state on a femtosecond-scale by Auger-type energy donation to the hole. However, if the oleic acid capping is exchanged for hexanedithiol capping, fast deep hole trapping competes efficiently with this relaxation pathway, blocking the Auger-type electron-hole energy exchange. A slower decay becomes then visible; we provide evidence that this is a multistep process involving the surface. PMID:23506122

  1. THE ELECTRONIC STRUCTURE OF AG/CU(100) SURFACE ALLOYS STUDIES BY AUGER-PHOTOELECTRON COINCIDENCE SPECTROSCOPY.

    SciTech Connect

    ARENA,D.A.; BARTYNSKI,R.A.; HULBERT,S.L.

    2001-10-08

    We have measured the Ag and Pd M{sub 5}VV Auger spectrum in coincidence with Ag and Pd 4d{sub 5/2} photoelectrons for the Ag/Cu(100) and Pd/Cu(100) systems, respectively, as a function of admetal coverage. These systems form surface alloys (i.e. random substitutional alloys in the first atomic layer) for impurity concentrations in the 0.1 monolayer range. For these systems, the centroid of the impurity 4d levels is expected to shift away from the Fermi level by {approx}1 eV [Ruban et al., Journal of Molecular Catalysis. A 115 (1997) 421], an effect that should be easily seen in coincidence core-valence-valence Auger spectra. We find that the impurity Auger spectra of both systems shift in a manner that is consistent with d-band moving away from EF. However, the shift for Pd is considerably smaller than expected, and a shift almost absent for Ag. The disagreement between theory and experiment is most likely caused by the neglect of lattice relaxations in the calculations.

  2. DIAMOND SECONDARY EMITTER

    SciTech Connect

    BEN-ZVI, I.; RAO, T.; BURRILL, A.; CHANG, X.; GRIMES, J.; RANK, J.; SEGALOV, Z.; SMEDLEY, J.

    2005-10-09

    We present the design and experimental progress on the diamond secondary emitter as an electron source for high average power injectors. The design criteria for average currents up to 1 A and charge up to 20 nC are established. Secondary Electron Yield (SEY) exceeding 200 in transmission mode and 50 in emission mode have been measured. Preliminary results on the design and fabrication of the self contained capsule with primary electron source and secondary electron emitter will also be presented.

  3. Coal-Sizing Auger

    NASA Technical Reports Server (NTRS)

    Lewis, E. V.

    1985-01-01

    Aft end of auger, like forward, face-piercing end, equipped with hard cutting bits such as diamonds. As auger breaks face, pulls broken coal lumps into jaws and forces them into hardened throat section. There, cutting bits chew up lumps: Clearance between throat and auger shaft sets maximum size for coal particles that pass through. Auger motion pushes coal particles into mixing chamber, where paddles combine them with water.

  4. Radioprotection by DMSO against the biological effects of incorporated radionuclides in vivo--Comparison with other radioprotectors and evidence for indirect action of Auger electrons.

    PubMed

    Goddu, S M; Narra, V R; Harapanhalli, R S; Howell, R W; Rao, D V

    1996-01-01

    Dimethyl sulfoxide (DMSO) was studied for its capacity to protect against the biological effects of chronic irradiation by incorporated radionuclides. Spermatogenesis in mice was used as experimental model and spermatogonial cell survival was the biological endpoint. DMSO was injected intratesticularly 4 h prior to a similar injection of the radiochemical and the spermhead survival determined. Iodine-125 was localized in either the cytoplasm (H125IPDM) or in the DNA (125IUdR) of the testicular cells. Protection was observed against the high-LET type effects of DNA-bound 125I as well as the low-LET effects of cytoplasmically localized 125I with dose modification factors (DMF) of 3.1+/-1.0 and 4.4+/-1.0 respectively. No protection (DMF = 1.1+/-0.1) was observed against the effects of high-LET 5.3 MeV alpha particles of 210Po. The present findings provide supporting evidence that the mechanism responsible for the extreme biological damage caused by DNA-bound Auger emitters is largely radical mediated and therefore indirect in nature. PMID:9004770

  5. Single-Bunch Electron Cloud Effects in the GLC/NLC, US-Cold and TESLA Low Emittance Transport Lines

    SciTech Connect

    Bates, D.

    2005-04-12

    This paper examines the severity of the electron cloud effects in the Low Emittance Transport (LET) of linear colliders including the Bunch-Compressor System (BCS) and Beam Delivery System (BDS). We examine the electron cloud effects in the normal-conducting GLC/NLC or X-Band, and the super-conducting US-Cold and TESLA linear collider designs through the use of specially developed computer simulation codes. An estimate of the critical cloud density is given for the BDS and BCS of the X-Band collider.

  6. Temperature dependence of photoluminescence spectra of bilayer two-dimensional electron gases in LaAlO{sub 3}/SrTiO{sub 3} superlattices: coexistence of Auger recombination and single-carrier trapping

    SciTech Connect

    Ma, H. J. Harsan Ariando; Venkatesan, T.; Wang, S. J.

    2015-06-15

    We report emerging photoluminescence (PL) of bilayer two-dimensional electron gases (2DEG) in LaAlO{sub 3}/SrTiO{sub 3} (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.

  7. Photoelectron linear accelerator for producing a low emittance polarized electron beam

    DOEpatents

    Yu, David U.; Clendenin, James E.; Kirby, Robert E.

    2004-06-01

    A photoelectron linear accelerator for producing a low emittance polarized electric beam. The accelerator includes a tube having an inner wall, the inner tube wall being coated by a getter material. A portable, or demountable, cathode plug is mounted within said tube, the surface of said cathode having a semiconductor material formed thereon.

  8. An asymmetric emittance electron source for the GALAXIE dielectric-laser accelerator injector

    SciTech Connect

    Valloni, A.; Cahill, A.; Fukusawa, A.; Musumeci, P.; Spataro, B.; Yakub, A.; Rosenzweig, J. B.

    2012-12-21

    The GALAXIE project is a program to develop an all-optical, very high field accelerator and undulator integrated SASE FEL system based on dielectric laser-excited structures that support >GV/m fields. These structures are very wide in one direction to allow adequate charge given beam loading considerations, but also having small (subwavelength) apertures in the narrow direction. Such small vertical dimensions yield strict restrictions on the emittance in this direction, while no such constraint exists in the wide transverse direction. However, the overall beam brightness is restricted by the performance requirements on the FEL. To meet these demands, we are studying a very high field gun with a magnetized cathode, yielding a beam with angular momentum content. This beam is then subject to a skew-quad triplet that splits the emittances; this process is reversed to give a round beam after acceleration. This symmetric emittance beam avoids gain-degrading multiple-transverse-mode operation of the FEL, which also demands that the effects of the angular momentum in the beam be mitigated. In this paper we discuss the RF design of an X-band gun to be operated at {approx}200 MV/m peak field giving a 1 pC magnetized beam with unprecedented brightness. We examine the design of the focusing and skew-quad systems, investigating the associated beam dynamics and efficacy of emittance splitting.

  9. Electron Beam Damage in Poly(Vinyl Chloride) and Poly(Acrylonitrile) as Observed by Auger Electron Spectroscopy

    SciTech Connect

    Lea, Alan S.; Engelhard, Mark H.; Baer, Donald R.

    2003-03-07

    AES spectra of spun-cast films of poly(vinyl chloride) (PVC) and poly(acrylonitrile) (PAN) were collected over a period of time to determine specimen damage during exposure to a 10kV electron beam. For the PVC, loss of chlorine was observed over a period of 203 minutes to the extent that the final chlorine concentration was only 20% of its original value. PAN exhibited a loss in nitrogen content over a period of 120 minutes, but the rate of damage to the polymer was significantly less than PVC. Figure 1 shows the atomic concentration in the PVC film as a function of dose (time). It takes a dose of approximately 7.0x10-5 Ccm-5 for the chlorine concentration to fall from its original value by 10% (one definition of critical dose). Figure 2 shows a similar drop in nitrogen concentration in the PAN film as a function of dose. For this polymer, it takes a dose of 1.3x10-3 Ccm-2 for the nitrogen concentration to fall by 10%.

  10. Design and characterization of a movable emittance meter for low-energy electron beams

    SciTech Connect

    Catani, Luciano; Chiadroni, Enrica; Cianchi, Alessandro; Tazzari, Sergio; Boscolo, Manuela; Castellano, Michele; Di Pirro, Giampiero; Ferrario, Massimo; Fusco, Valeria; Filippetto, Daniele; Palumbo, Luigi; Vaccarezza, Cristina; Vicario, Carlo; Ronsivalle, Concetta

    2006-09-15

    In order to characterize and optimize the beam emittance compensation scheme [L. Serafini and J. B. Rosenzweig, Phys. Rev. E 55, 7565 (1997)] of the Sorgente Pulsata Autoamplificata di Radiazione Coerente project [D. Alesini et al., Nucl. Instrum. Methods Phys. Res. A 507, 345 (2003)] high brightness preinjector a system to accurately measure the beam rms emittance evolution downstream of the rf gun has been developed. Since in a space charge dominated beam the quadrupole-scan method is not applicable, a movable emittance measurement device has been built based on the pepper-pot technique. The device consists of a double system of horizontal and vertical slit arrays and a downstream screen, all installed on a longitudinally movable support equipped with bellows and spanning the {approx_equal}1.2 m long drift space between gun and first accelerating section. The system allows the measuring of the beam rms emittance all along the spanned region so as to accurately reconstruct its evolution along the beam trajectory. More than a simple improvement over more conventional beam emittance measurement tools this device defines a new strategy for characterizing high performance photoinjectors as it allows a detailed analysis of the beam behavior over a section of the accelerator where crucial beam shaping takes place. Numerical simulations of the measurement, mainly based on PARMELA [J. Billen, PARMELA Report No. LA-UR 96-1835, 1996 (unpublished)], have been used to estimate the achievable accuracy and to optimize the experimental setup. Wake field effects induced by the beam propagation through the bellows have also been investigated with HOMDYN [M. Ferrario et al., LCLS Report No. SLAC-PUB 84000, 1999 (unpublished)]. A series of laboratory tests to evaluate its performance has been carried out at LNF in Frascati. The system was then moved to DESY Zeuthen and installed on the Photo Injector Test Facility PITZ, for further testing with beam. Design criteria and tests

  11. 111In-BnDTPA-F3: an Auger electron-emitting radiotherapeutic agent that targets nucleolin

    PubMed Central

    2012-01-01

    Introduction The F3 peptide (KDEPQRRSARLSAKPAPPKPEPKPKKAPAKK), a fragment of the human high mobility group protein 2, binds nucleolin. Nucleolin is expressed in the nuclei of normal cells but is also expressed on the membrane of some cancer cells. The goal was to investigate the use of 111In-labeled F3 peptide for Auger electron-targeted radiotherapy. Methods F3 was labeled with fluorescein isothiocyanate (FITC) for confocal microscopy and conjugated to p-SCN-benzyl-diethylenetriaminepentaacetic acid (BnDTPA) for labeling with 111In to form 111In-BnDTPA-F3. MDA-MB-231-H2N (231-H2N) human breast cancer cells were exposed to 111In-BnDTPA-F3 and used in cell fractionation, γH2AX immunostaining (a marker of DNA double-strand breaks), and clonogenic assays. In vivo, biodistribution studies of 111In-BnDTPA-F3 were performed in 231-H2N xenograft-bearing mice. In tumor growth delay studies, 111In-BnDTPA-F3 (3 μg, 6 MBq/μg) was administered intravenously to 231-H2N xenograft-bearing mice once weekly for 3 weeks. Results Membrane-binding of FITC-F3 was observed in 231-H2N cells, and there was co-localization of FITC-F3 with nucleolin in the nuclei. After exposure of 231-H2N cells to 111In-BnDTPA-F3 for 2 h, 1.7% of 111In added to the medium was membrane-bound. Of the bound 111In, 15% was internalized, and of this, 37% was localized in the nucleus. Exposure of 231-H2N cells to 111In-BnDTPA-F3 (1 μM, 6 MBq/μg) resulted in a dose-dependent increase in γH2AX foci and in a significant reduction of clonogenic survival compared to untreated cells or cells exposed to unlabeled BnDTPA-F3 (46 ± 4.1%, 100 ± 1.8%, and 132 ± 7.7%, respectively). In vivo, tumor uptake of 111In-BnDTPA-F3 (3 μg, 6 MBq/μg) at 3-h post-injection was 1% of the injected dose per gram (%ID/g), and muscle uptake was 0.5%ID/g. In tumor growth delay studies, tumor growth rate was reduced 19-fold compared to untreated or unlabeled BnDTPA-F3-treated mice (p = 0.023). Conclusion 111In-BnDTPA-F3 is

  12. Oxygen diffusion from anodic surface oxide films on titanium subhydride studied by auger electron spectroscopy and electron energy loss spectroscopy

    SciTech Connect

    Wang, P.S.; Wittberg, T.N.; Wolf, J.D.; Keil, R.G.

    1984-01-01

    In the present study, TiH/sub x/ (0.5 < x < 1.7) samples were prepared from titanium foil in order to study the diffusion of oxygen in the titanium subhydride. An anodic oxide, 1000A thick, was grown on the titanium subhydride foils in an aqueous saturated solution of ammonium tetraborate. These anodized samples were then heat treated at temperatures between 500 and 600/sup 0/C and changes in the profile of oxygen concentration as a function of depth were monitored using AES. From this data then it was possible to calculate the diffusivity of oxygen in the titanium subhydride. It was also found that electron energy loss spectroscopy (EELS) could be used to determine the titanium subhydride stoichiometry in the near-surface region. This was done by measuring the energy of the bulk plasmon loss peak, which for TiH/sub x/, varies linearly with hydrogen content. The amount of dehydriding which had occurred following a given heat treatment could be determined from profiles of the plasmon loss energy as a function of depth. A sample of anodized TiH/sub 0/ /sub 87/ was studied in some detail. Significant dehydriding of this sample for heat treatment times of less than one hour, only occurred at temperatures above 550/sup 0/C. Likewise, oxide dissolution was only significant at temperatures greater than 550/sup 0/C. In general, for the heat treatment parameters which were chosen, the diffusivity of oxygen in TiH/sub 0/ /sub 87/ was about an order of magnitude lower than that for oxygen in titanium.

  13. Simulation of Auger electron emission from nanometer-size gold targets using the Geant4 Monte Carlo simulation toolkit

    NASA Astrophysics Data System (ADS)

    Incerti, S.; Suerfu, B.; Xu, J.; Ivantchenko, V.; Mantero, A.; Brown, J. M. C.; Bernal, M. A.; Francis, Z.; Karamitros, M.; Tran, H. N.

    2016-04-01

    A revised atomic deexcitation framework for the Geant4 general purpose Monte Carlo toolkit capable of simulating full Auger deexcitation cascades was implemented in June 2015 release (version 10.2 Beta). An overview of this refined framework and testing of its capabilities is presented for the irradiation of gold nanoparticles (NP) with keV photon and MeV proton beams. The resultant energy spectra of secondary particles created within and that escape the NP are analyzed and discussed. It is anticipated that this new functionality will improve and increase the use of Geant4 in the medical physics, radiobiology, nanomedicine research and other low energy physics fields.

  14. Field electron emission enhancement of graphenated MWCNTs emitters following their decoration with Au nanoparticles by a pulsed laser ablation process.

    PubMed

    Gautier, L-A; Le Borgne, V; Delegan, N; Pandiyan, R; El Khakani, M A

    2015-01-30

    A plasma-enhanced chemical vapor deposition (PECVD) process was adapted to alter the growth of multiwall carbon nanotubes (MWCNTs) so that graphene sheets grow out of their tips. Gold nanoparticle (Au-NP) decoration of graphenated MWCNTs (g-MWCNTs) was obtained by subsequent decoration by a pulsed laser deposition (PLD) process. By varying the number of laser ablation pulses (N(Lp)) in the PLD process, we were able to control the size of the gold nanoparticles and the surface coverage of the decorated g-MWCNTs. The presence of Au-NPs, preferentially located at the tip of the g-MWCNTs emitters, is shown to significantly improve the field electron emission (FEE) properties of the global g-MWCNT/Au-NP nanohybrid films. Indeed, the electric field needed to extract a current density of 0.1 μA cm(-)(2) from the g-MWCNT/Au-NP films was decreased from 2.68 V μm(-1) to a value as low as 0.96 V μm(-1). On the other hand, UV photoelectron spectroscopy (UPS) characterization revealed a decrease in the global work function of the Au-decorated g-MWCNT nanohybrids compared to that of bare g-MWCNT emitters. Surprisingly, the work function of g-MWCNT was found to decrease from 4.9 to 4.7 eV with the addition of Au-NPs-a value lower than the work function of both materials worth 5.2 and 4.9 eV for gold and g-MWCNT, respectively. Our results show that the N(Lp) dependence of the FEE characteristics of the g-MWCNT/Au-NP emitters correlates well with their work function changes. Fowler-Nordheim-theory-based calculations suggest that the significant FEE enhancement of the emitters is also caused by the Au-NPs acting as nanoscale electric field enhancers. PMID:25567743

  15. Field electron emission enhancement of graphenated MWCNTs emitters following their decoration with Au nanoparticles by a pulsed laser ablation process

    NASA Astrophysics Data System (ADS)

    Gautier, L.-A.; Le Borgne, V.; Delegan, N.; Pandiyan, R.; El Khakani, M. A.

    2015-01-01

    A plasma-enhanced chemical vapor deposition (PECVD) process was adapted to alter the growth of multiwall carbon nanotubes (MWCNTs) so that graphene sheets grow out of their tips. Gold nanoparticle (Au-NP) decoration of graphenated MWCNTs (g-MWCNTs) was obtained by subsequent decoration by a pulsed laser deposition (PLD) process. By varying the number of laser ablation pulses (NLp) in the PLD process, we were able to control the size of the gold nanoparticles and the surface coverage of the decorated g-MWCNTs. The presence of Au-NPs, preferentially located at the tip of the g-MWCNTs emitters, is shown to significantly improve the field electron emission (FEE) properties of the global g-MWCNT/Au-NP nanohybrid films. Indeed, the electric field needed to extract a current density of 0.1 μA cm-2 from the g-MWCNT/Au-NP films was decreased from 2.68 V μm-1 to a value as low as 0.96 V μm-1. On the other hand, UV photoelectron spectroscopy (UPS) characterization revealed a decrease in the global work function of the Au-decorated g-MWCNT nanohybrids compared to that of bare g-MWCNT emitters. Surprisingly, the work function of g-MWCNT was found to decrease from 4.9 to 4.7 eV with the addition of Au-NPs—a value lower than the work function of both materials worth 5.2 and 4.9 eV for gold and g-MWCNT, respectively. Our results show that the NLp dependence of the FEE characteristics of the g-MWCNT/Au-NP emitters correlates well with their work function changes. Fowler-Nordheim-theory-based calculations suggest that the significant FEE enhancement of the emitters is also caused by the Au-NPs acting as nanoscale electric field enhancers.

  16. High resolution positron annihilation induced Auger electron spectroscopy of the CuM 2,3VV-transition and of Cu sub-monolayers on Pd and Fe

    NASA Astrophysics Data System (ADS)

    Mayer, J.; Hugenschmidt, C.; Schreckenbach, K.

    2010-09-01

    We present a high resolution positron annihilation induced Auger Electron Spectroscopy (PAES) of the CuM 2,3VV-transition with the unprecedented energy resolution of Δ/EE <1%. This energy resolution and the highly intense positron source NEPOMUC enabled us to resolve the double peak structure with PAES for the first time within a measurement time of only 5.5 h. In addition, sub-monolayers of Cu were deposited on Fe- and Pd-samples in order to investigate the surface selectivity of PAES in comparison with EAES. The extremely high surface selectivity of PAES due to the different positron affinity of Cu and Fe lead to the result that with only 0.96 monolayer of Cu on Fe more than 55% of the emitted Auger electrons stem from Cu, whereas with EAES the Cu Auger fraction amounted to less than 6%.

  17. Surface compositions of atomic layer deposited Zn{sub 1−x}Mg{sub x}O thin films studied using Auger electron spectroscopy

    SciTech Connect

    Xie, Ting; Romero, Danilo; Gomez, Romel D.

    2015-09-15

    In this paper, the authors present Auger electron spectroscopy (AES) studies of Zn{sub 1−x}Mg{sub x}O (ZMO) films grown via interrupted atomic-layer deposition (ALD) techniques. The ZMO films were fabricated by alternating ALD deposition of ZnO and MgO layers up to 1000 cycles. Zn{sub 1−x}Mg{sub x}O films with progressively decreasing Mg/Zn ratios (Mg/Zn = 1/1, 1/2, 1/3, 1/4, 1/5, 1/6, 1/9, and 2/8, 3/12, 4/16, and 5/20) were fabricated for this study. The AES results exhibit an abrupt drop of Mg composition on the ZMO surface when the Mg/Zn < 1/3. Additionally, the surface composition ratios of O to Mg, O to Zn, and Mg to Zn were estimated with known Auger sensitivity factors. The results indicate that Mg ions diffuse into the bulk, forming Zn{sub 1−x}Mg{sub x}O alloys.

  18. Stable electron field emission from carbon nanotubes emitter transferred on graphene films

    NASA Astrophysics Data System (ADS)

    Zhao, Ning; Chen, Jing; Qu, Ke; Khan, Qasim; Lei, Wei; Zhang, Xiaobing

    2015-08-01

    Carbon nanotubes (CNTs) arrays grown by microwave plasma enhanced chemical vapor deposition (MPCVD) method was transferred onto the substrate covered with graphene layer obtained by thermal chemical vapor deposition (CVD) technology. The graphene buffer layer provides good electrical and thermal contact to the CNTs. The field emission characteristics of this hybrid structure were investigated in this study. Compared with the CNTs arrays directly grown on the silicon substrate, the hybrid emitter shows better field emission performance, such as high emission current and long-term emission stability. The presence of this graphene layer was shown to improve the field emission behavior of CNTs. This work provides an effective way to realize stable field emission from CNTs emitter and similar hybrid structures.

  19. Development of a pepper-pot device to determine the emittance of an ion beam generated by electron cyclotron resonance ion sources

    SciTech Connect

    Strohmeier, M.; Benitez, J. Y.; Leitner, D.; Lyneis, C. M.; Todd, D. S.; Bantel, M.

    2010-02-15

    This paper describes the recent development and commissioning of a pepper-pot emittance meter at the Lawrence Berkeley National Laboratory (LBNL). It is based on a potassium bromide (KBr) scintillator screen in combination with a charged coupled device camera. Pepper-pot scanners record the full four-dimensional transverse phase space emittances which are particularly interesting for electron cyclotron resonance ion sources. The strengths and limitations of evaluating emittances using optical pepper-pot scanners are described and systematic errors induced by the optical data acquisition system will be presented. Light yield tests of KBr exposed to different ion species and first emittance measurement data using ion beams extracted from the 6.4 GHz LBNL electron cyclotron resonance ion source are presented and discussed.

  20. Development of a pepper-pot device to determine the emittance of an ion beam generated by electron cyclotron resonance ion sources.

    PubMed

    Strohmeier, M; Benitez, J Y; Leitner, D; Lyneis, C M; Todd, D S; Bantel, M

    2010-02-01

    This paper describes the recent development and commissioning of a pepper-pot emittance meter at the Lawrence Berkeley National Laboratory (LBNL). It is based on a potassium bromide (KBr) scintillator screen in combination with a charged coupled device camera. Pepper-pot scanners record the full four-dimensional transverse phase space emittances which are particularly interesting for electron cyclotron resonance ion sources. The strengths and limitations of evaluating emittances using optical pepper-pot scanners are described and systematic errors induced by the optical data acquisition system will be presented. Light yield tests of KBr exposed to different ion species and first emittance measurement data using ion beams extracted from the 6.4 GHz LBNL electron cyclotron resonance ion source are presented and discussed. PMID:20192450

  1. Multielectron Spectroscopy: The Xenon 4d Hole Double Auger Decay

    SciTech Connect

    Penent, F.; Palaudoux, J.; Lablanquie, P.; Andric, L.; Feifel, R.; Eland, J.H.D.

    2005-08-19

    A magnetic bottle spectrometer of the type recently developed by Eland et al. [Phys. Rev. Lett. 90, 053003 (2003).] has been implemented for use with synchrotron radiation, allowing multidimensional electron spectroscopy. Its application to the Xe 4d double Auger decay reveals all the energy pathways involved. The dominant path is a cascade process with a rapid (6 fs) ejection of a first Auger electron followed by the slower (>23 fs) emission of a second Auger electron. Weaker processes implying 3 electron processes are also revealed, namely, direct double Auger and associated Rydberg series.

  2. Emittance study of a 28 GHz electron cyclotron resonance ion source for the Rare Isotope Science Project superconducting linear accelerator.

    PubMed

    Park, Bum-Sik; Hong, In-Seok; Jang, Ji-Ho; Jin, Hyunchang; Choi, Sukjin; Kim, Yonghwan

    2016-02-01

    A 28 GHz electron cyclotron resonance (ECR) ion source is being developed for use as an injector for the superconducting linear accelerator of the Rare Isotope Science Project. Beam extraction from the ECR ion source has been simulated using the KOBRA3-INP software. The simulation software can calculate charged particle trajectories in three dimensional complex magnetic field structures, which in this case are formed by the arrangement of five superconducting magnets. In this study, the beam emittance is simulated to understand the effects of plasma potential, mass-to-charge ratio, and spatial distribution. The results of these simulations and their comparison to experimental results are presented in this paper. PMID:26931953

  3. Emittance study of a 28 GHz electron cyclotron resonance ion source for the Rare Isotope Science Project superconducting linear accelerator

    NASA Astrophysics Data System (ADS)

    Park, Bum-Sik; Hong, In-Seok; Jang, Ji-Ho; Jin, Hyunchang; Choi, Sukjin; Kim, Yonghwan

    2016-02-01

    A 28 GHz electron cyclotron resonance (ECR) ion source is being developed for use as an injector for the superconducting linear accelerator of the Rare Isotope Science Project. Beam extraction from the ECR ion source has been simulated using the KOBRA3-INP software. The simulation software can calculate charged particle trajectories in three dimensional complex magnetic field structures, which in this case are formed by the arrangement of five superconducting magnets. In this study, the beam emittance is simulated to understand the effects of plasma potential, mass-to-charge ratio, and spatial distribution. The results of these simulations and their comparison to experimental results are presented in this paper.

  4. Measurements and Simulations of Ultra-Low Emittance and Ultra-Short Electron Beams in the Linac Coherent Light Source

    SciTech Connect

    Ding, Y.; Brachmann, A.; Decker, F.-J.; Dowell, D.; Emma, P.; Frisch, J.; Gilevich, S.; Hays, G.; Hering, Ph.; Huang, Z.; Iverson, R.; Loos, H.; Miahnahri, A.; Nuhn, H.-D.; Ratner, D.; Turner, J.; Welch, J.; White, W.; Wu, J.; /SLAC

    2009-02-03

    The Linac Coherent Light Source (LCLS) is an x-ray Free-Electron Laser (FEL) project presently in a commissioning phase at SLAC. We report here on very low emittance measurements made at low bunch charge, and a few femtosecond bunch length produced by the LCLS bunch compressors. Start-to-end simulations associated with these beam parameters show the possibilities of generating hundreds of GW at 1.5 {angstrom} x-ray wavelength and nearly a single longitudinally spike at 1.5 nm with 2-fs duration.

  5. Auger Radiopharmaceutical Therapy Targeting Prostate-Specific Membrane Antigen

    PubMed Central

    Kiess, Ana P.; Hobbs, Robert; Sgouros, George; Mease, Ronnie C.; Pullambhatla, Mrudula; Shen, Colette J.; Foss, Catherine A.; Pomper, Martin G.

    2015-01-01

    Auger electron emitters such as 125I have a high linear energy transfer and short range of emission (<10 μm), making them suitable for treating micrometastases while sparing normal tissues. We used a highly specific small molecule targeting the prostate-specific membrane antigen (PSMA) to deliver 125I to prostate cancer cells. Methods The PSMA-targeting Auger emitter 2-[3-[1-carboxy-5-(4-125I-iodo-benzoylamino)-pentyl]-ureido]-pentanedioic acid (125I-DCIBzL) was synthesized. DNA damage (via phosphorylated H2A histone family member X staining) and clonogenic survival were tested in PSMA-positive (PSMA+) PC3 PIP and PSMA-negative (PSMA−) PC3 flu human prostate cancer cells after treatment with 125I-DCIBzL. Subcellular drug distribution was assessed with confocal microscopy using a related fluorescent PSMA-targeting compound YC-36. In vivo antitumor efficacy was tested in nude mice bearing PSMA+ PC3 PIP or PSMA− PC3 flu flank xenografts. Animals were administered (intravenously) 111 MBq (3 mCi) of 125I-DCIBzL, 111 MBq (3 mCi) of 125I-NaI, an equivalent amount of nonradiolabeled DCIBzL, or saline. Results After treatment with 125I-DCIBzL, PSMA+ PC3 PIP cells exhibited increased DNA damage and decreased clonogenic survival when compared with PSMA− PC3 flu cells. Confocal microscopy of YC-36 showed drug distribution in the perinuclear area and plasma membrane. Animals bearing PSMA+ PC3 PIP tumors had significant tumor growth delay after treatment with 125I-DCIBzL, with only 1 mouse reaching 5 times the initial tumor volume by 60 d after treatment, compared with a median time to 5 times volume of less than 15 d for PSMA− PC3 flu tumors and all other treatment groups (P = 0.002 by log-rank test). Conclusion PSMA-targeted radiopharmaceutical therapy with the Auger emitter 125I-DCIBzL yielded highly specific antitumor efficacy in vivo, suggesting promise for treatment of prostate cancer micrometastases. PMID:26182968

  6. Space Charge Correction on Emittance Measurement of Low Energy Electron Beams

    SciTech Connect

    Treado, Colleen J.; /Massachusetts U., Amherst

    2012-09-07

    The goal of any particle accelerator is to optimize the transport of a charged particle beam along a set path by confining the beam to a small region close to the design trajectory and directing it accurately along the beamline. To do so in the simplest fashion, accelerators use a system of magnets that exert approximately linear electromagnetic forces on the charged beam. These electromagnets bend the beam along the desired path, in the case of bending magnets, and constrain the beam to the desired area through alternating focusing and defocusing effects, in the case of quadrupole magnets. We can model the transport of such a beam through transfer matrices representing the actions of the various beamline elements. However, space charge effects, produced from self electric fields within the beam, defocus the beam and must be accounted for in the calculation of beam emittance. We present below the preliminary results of a MATLAB code built to model the transport of a charged particle beam through an accelerator and measure the emittance under the influence of space charge effects. We demonstrate the method of correctly calculating the emittance of a beam under space charge effects using a least square fit to determine the initial properties of the beam given the beam size measured at a specific point after transport.

  7. Modeling of the energy resolution of a 1 meter and a 3 meter time of flight positron annihilation induced Auger electron spectrometers

    NASA Astrophysics Data System (ADS)

    Fairchild, A.; Chirayath, V.; Gladen, R.; McDonald, A.; Lim, Z.; Chrysler, M.; Koymen, A.; Weiss, A.

    Simion 8.1®simulations were used to determine the energy resolution of a 1 meter long Time of Flight Positron annihilation induced Auger Electron Spectrometer (TOF-PAES). The spectrometer consists of: 1. a magnetic gradient section used to parallelize the electrons leaving the sample along the beam axis, 2. an electric field free time of flight tube and 3. a detection section with a set of ExB plates that deflect electrons exiting the TOF tube into a Micro-Channel Plate (MCP). Simulations of the time of flight distribution of electrons emitted according to a known secondary electron emission distribution, for various sample biases, were compared to experimental energy calibration peaks and found to be in excellent agreement. The TOF spectra at the highest sample bias was used to determine the timing resolution function describing the timing spread due to the electronics. Simulations were then performed to calculate the energy resolution at various electron energies in order to deconvolute the combined influence of the magnetic field parallelizer, the timing resolution, and the voltage gradient at the ExB plates. The energy resolution of the 1m TOF-PAES was compared to a newly constructed 3 meter long system. The results were used to optimize the geometry and the potentials of the ExB plates for obtaining the best energy resolution. This work was supported by NSF Grant NSF Grant No. DMR 1508719 and DMR 1338130.

  8. Direct Observation of the Surface Segregation of Cu in Pd by Time-Resolved Positron-Annihilation-Induced Auger Electron Spectroscopy

    SciTech Connect

    Mayer, J.; Hugenschmidt, C.; Schreckenbach, K.

    2010-11-12

    Density functional theory calculations predict the surface segregation of Cu in the second atomic layer of Pd which has not been unambiguously confirmed by experiment so far. We report measurements on Pd surfaces covered with three and six monolayers of Cu using element selective positron-annihilation-induced Auger electron spectroscopy (PAES) which is sensitive to the topmost atomic layer. Moreover, time-resolved PAES, which was applied for the first time, enables the investigation of the dynamics of surface atoms and hence the observation of the segregation process. The time constant for segregation was experimentally determined to {tau}=1.38(0.21) h, and the final segregated configuration was found to be consistent with calculations. Time-dependent PAES is demonstrated to be a novel element selective technique applicable for the investigation of, e.g., heterogeneous catalysis, corrosion, or surface alloying.

  9. Auger electron spectroscopy and x-ray photoelectron spectroscopy of the biocorrosion of copper by Gum Arabic, BCS and Pseudomonas atlantica exopolymer

    SciTech Connect

    Jolley, J.G.; Geesey, G.G.; Hankins, M.R.; Wright, R.B.; Wichlacz, P.L.

    1987-01-01

    Thin films (3.4 nm) of copper on germanium substrates were exposed to 10% Gum Arabic aqueous solution, 1% BCS (aqueous and simulated sea water solutions) and 0.5% Pseudomonas atlantica exopolymer (aqueous and simulated sea water solutions). Pre- and post-exposure characterization were done by Auger electron spectroscopy and x-ray photoelectron spectroscopy. Ancillary graphite furnace atomic absorption spectroscopy was used to monitor the removal process of the copper thin film from the germanium substrate. Results indicate that the copper was oxidized by the Gum Arabic and BCS, and some was removed from the Cu/Ge interface by all three polymers and incorporated into the polymer matrix. Thus biocorrosion of copper was exhibited by the Gum Arabic, BCS and Pseudomonas atlantica exopolymer. 14 refs., 4 figs., 3 tabs.

  10. Variations of surface roughness for deposition of Co-sputtered-ZnO(002) by Auger electron spectroscopy and surface magneto-optic Faraday effect

    NASA Astrophysics Data System (ADS)

    Chang, Y.-C.; Su, C.-W.; Chang, S.-C.; Lee, Y.-H.

    2011-02-01

    Auger electron spectroscopy and the surface magneto-optical Faraday effect were used to monitor the deposition of Co ultrathin films on an initially rough ZnO(002) crystal surface. The magnetic properties of the epitaxial films were compared with those associated with that the structure properties in a 3D island growth mode. The magneto-optic signals are very sensitive to the thickness of the Co film structure, even if it is rough. The ZnO(002) substrate surface formed by routine ion sputtering may exhibit short-range ordering in the initial sample preparation. The roughness of a sputtered substrate surface can be determined from the sensitive magneto-optical signals, especially when ultrathin films are deposited in the initial stage of growth.

  11. Angular distribution measurements of the xenon N{sub 4,5}O{sub 2,3}O{sub 2,3} Auger electrons: Determination of alignment and intrinsic parameters

    SciTech Connect

    Snell, G.; Kukk, E.; Berrah, N.

    2000-04-01

    In the framework of the two-step model of Auger decay the alignment of the xenon 4d{sup -1} primary hole states has been derived as a function of photon energy. This quantity was obtained from angular distribution measurements of the N{sub 4,5}O{sub 2,3}O{sub 2,3} Auger lines after ionization of free atoms by monochromatized synchrotron radiation of 80-250 eV photon energy. The data show a minimum of the alignment parameter in the Cooper minimum of the 4d photoionization cross section, which proves the vanishing of the outgoing {epsilon}f electron wave. Furthermore, the intrinsic parameters for all lines in this Auger group were determined and are compared with previous experiments and calculations. (c) 2000 The American Physical Society.

  12. Multiple direct and sequential Auger effect in the rare gases

    SciTech Connect

    Penent, F.; Lablanquie, P.; Palaudoux, J.; Andric, L.; Aoto, T.; Ito, K.; Hikosaka, Y.; Feifel, R.; Eland, J. H. D.

    2006-01-09

    The use of a magnetic bottle spectrometer with synchrotron radiation allows multi dimensional electron spectroscopy to be performed by detecting in coincidence all electrons (2, 3, 4) ejected in multiple ionization events. Multiple Auger effect following inner-shell ionization can be investigated in this way. Application of the technique to rare gases (Xe 4d and Kr 3d) double Auger decay reveals all the energy pathways involved. The dominant decay path proceeds by Auger cascade through autoionizing states of the doubly charged ion. Processes where 3 electrons are involved are also observed as direct double Auger and as involving precursor Rydberg series.

  13. High Stability Electron Field Emitters Synthesized via the Combination of Carbon Nanotubes and N₂-Plasma Grown Ultrananocrystalline Diamond Films.

    PubMed

    Chang, Ting-Hsun; Hsieh, Ping-Yen; Kunuku, Srinivasu; Lou, Shiu-Cheng; Manoharan, Divinah; Leou, Keh-Chyang; Lin, I-Nan; Tai, Nyan-Hwa

    2015-12-16

    An electron field emitter with superior electron field emission (EFE) properties and improved lifetime stability is being demonstrated via the combination of carbon nanotubes and the CH4/N2 plasma grown ultrananocrystalline diamond (N-UNCD) films. The resistance of the carbon nanotubes to plasma ion bombardment is improved by the formation of carbon nanocones on the side walls of the carbon nanotubes, thus forming strengthened carbon nanotubes (s-CNTs). The N-UNCD films can thus be grown on s-CNTs, forming N-UNCD/s-CNTs carbon nanocomposite materials. The N-UNCD/s-CNTs films possess good conductivity of σ = 237 S/cm and marvelous EFE properties, such as low turn-on field of (E0) = 3.58 V/μm with large EFE current density of (J(e)) = 1.86 mA/cm(2) at an applied field of 6.0 V/μm. Moreover, the EFE emitters can be operated under 0.19 mA/cm(2) for more than 350 min without showing any sign of degradation. Such a superior EFE property along with high robustness characteristic of these combination of materials are not attainable with neither N-UNCD films nor s-CNTs films alone. Transmission electron microscopic investigations indicated that the N-UNCD films contain needle-like diamond grains encased in a few layers of nanographitic phase, which enhanced markedly the transport of electrons in the N-UNCD films. Moreover, the needle-like diamond grains were nucleated from the s-CNTs without the necessity of forming the interlayer that facilitate the transport of electrons crossing the diamond-to-Si interface. Both these factors contributed to the enhanced EFE behavior of the N-UNCD/s-CNTs films. PMID:26600097

  14. Improved Electronic Properties of Laser-Doped Emitters by Reducing Surface Roughness

    NASA Astrophysics Data System (ADS)

    Nishimura, Hideki; Hirata, Kenji; Hasegawa, Mitsuhiro; Katagiri, Takuya; Fuyuki, Takashi

    2012-10-01

    Laser doping (LD) can help form emitters at low cost and in high throughput because it operates in air atmosphere and at room temperature. Moreover, LD makes high-efficiency structures in a very simple way by melting and diffusing impurities on selective areas. In this study, evaluation of the relationship between multicrystalline silicon (mc-Si) surface conditions and electric properties is carried out. The results show that the surface electric properties were improved and conversion efficiencies were increased. This was accomplished by changing the surface conditions from rough to smooth by surface etching and vacuum treatment before LD.

  15. Pulsed hybrid field emitter

    DOEpatents

    Sampayan, Stephen E.

    1998-01-01

    A hybrid emitter exploits the electric field created by a rapidly depoled ferroelectric material. Combining the emission properties of a planar thin film diamond emitter with a ferroelectric alleviates the present technological problems associated with both types of emitters and provides a robust, extremely long life, high current density cathode of the type required by emerging microwave power generation, accelerator technology and display applications. This new hybrid emitter is easy to fabricate and not susceptible to the same failures which plague microstructure field emitter technology. Local electrode geometries and electric field are determined independently from those for optimum transport and brightness preservation. Due to the large amount of surface charge created on the ferroelectric, the emitted electrons have significant energy, thus eliminating the requirement for specialized phosphors in emissive flat-panel displays.

  16. Pulsed hybrid field emitter

    DOEpatents

    Sampayan, S.E.

    1998-03-03

    A hybrid emitter exploits the electric field created by a rapidly depoled ferroelectric material. Combining the emission properties of a planar thin film diamond emitter with a ferroelectric alleviates the present technological problems associated with both types of emitters and provides a robust, extremely long life, high current density cathode of the type required by emerging microwave power generation, accelerator technology and display applications. This new hybrid emitter is easy to fabricate and not susceptible to the same failures which plague microstructure field emitter technology. Local electrode geometries and electric field are determined independently from those for optimum transport and brightness preservation. Due to the large amount of surface charge created on the ferroelectric, the emitted electrons have significant energy, thus eliminating the requirement for specialized phosphors in emissive flat-panel displays. 11 figs.

  17. Formation of compressed flat electron beams with high transverse-emittance ratios

    SciTech Connect

    Zhu, J.; Piot, P.; Mihalcea, D.; Prokop, C. R.

    2014-08-01

    Flat beams—beams with asymmetric transverse emittances—have important applications in novel light-source concepts and advanced-acceleration schemes and could possibly alleviate the need for damping rings in lepton colliders. Over the last decade, a flat beam generation technique based on the conversion of an angular-momentum-dominated beam was proposed and experimentally tested. In this paper we explore the production of compressed flat beams. We especially investigate and optimize the flat beam transformation for beams with substantial fractional energy spread. We use as a simulation example the photoinjector of Fermilab’s Advanced Superconducting Test Accelerator. The optimizations of the flat beam generation and compression at Advanced Superconducting Test Accelerator were done via start-to-end numerical simulations for bunch charges of 3.2 nC, 1.0 nC, and 20 pC at ~37 MeV. The optimized emittances of flat beams with different bunch charges were found to be 0.25 μm (emittance ratio is ~400), 0.13 μm, 15 nm before compression, and 0.41 μm, 0.20 μm, 16 nm after full compression, respectively, with peak currents as high as 5.5 kA for a 3.2-nC flat beam. These parameters are consistent with requirements needed to excite wakefields in asymmetric dielectric-lined waveguides or produce significant photon flux using small-gap micro-undulators.

  18. Generating femtosecond X-ray pulses using an emittance-spoiling foil in free-electron lasers

    NASA Astrophysics Data System (ADS)

    Ding, Y.; Behrens, C.; Coffee, R.; Decker, F.-J.; Emma, P.; Field, C.; Helml, W.; Huang, Z.; Krejcik, P.; Krzywinski, J.; Loos, H.; Lutman, A.; Marinelli, A.; Maxwell, T. J.; Turner, J.

    2015-11-01

    Generation of femtosecond to sub-femtosecond pulses is attracting much attention in X-ray free-electron laser user community. One method is to use a slotted, emittance-spoiling foil which was proposed before (P. Emma et al., Phys. Rev. Lett. 92, 074801 (2004)) and has been widely used at the Linac Coherent Light Source. Direct experimental characterization of the slotted-foil performance was previously unfeasible due to a lack of appropriate diagnostics. With a recently installed X-band radio-frequency transverse deflector, we are able to characterize the electron bunch spoiling effect and X-ray pulse when using the slotted foil. We show that few-femtosecond X-ray pulses are generated with flexible control of the single-pulse duration or double-pulse separation with comparison to the theoretical model.

  19. Generating femtosecond X-ray pulses using an emittance-spoiling foil in free-electron lasers

    SciTech Connect

    Ding, Y. Coffee, R.; Decker, F.-J.; Emma, P.; Field, C.; Huang, Z.; Krejcik, P.; Krzywinski, J.; Loos, H.; Lutman, A.; Marinelli, A.; Maxwell, T. J.; Turner, J.; Behrens, C.; Helml, W.

    2015-11-09

    Generation of femtosecond to sub-femtosecond pulses is attracting much attention in X-ray free-electron laser user community. One method is to use a slotted, emittance-spoiling foil which was proposed before (P. Emma et al., Phys. Rev. Lett. 92, 074801 (2004)) and has been widely used at the Linac Coherent Light Source. Direct experimental characterization of the slotted-foil performance was previously unfeasible due to a lack of appropriate diagnostics. With a recently installed X-band radio-frequency transverse deflector, we are able to characterize the electron bunch spoiling effect and X-ray pulse when using the slotted foil. We show that few-femtosecond X-ray pulses are generated with flexible control of the single-pulse duration or double-pulse separation with comparison to the theoretical model.

  20. Quadrupole lens-free multiple-profile diagnostics for emittance measurement of laser wakefield accelerated electron beams

    NASA Astrophysics Data System (ADS)

    Krůs, M.; Laštovička, T.; Levato, T.

    2016-02-01

    A quadrupole lens-free diagnostic is a simple single shot method which can be used to measure the electron beam transverse emittance. LANEX screens are used as profile monitors due to the high yield of visible photons which can be easily detected by standard camera sensors. This type of minimally destructive diagnostics is particularly suitable for electron beams accelerated by the laser wakefield mechanism where the basic parameters of such beams fluctuate shot-to-shot mainly during the beam optimizing process. It allows to simultaneously measure the beam divergence, position, profile, pointing, and charge. The numerical study of the diagnostics performance and applicability range is presented and its limits are discussed. The influence of the LANEX screen multiple Coulomb scattering is studied by means of GEANT4; the unfolding procedure for multiple scattering contribution is presented.

  1. Transverse emittance-preserving arc compressor for high-brightness electron beam-based light sources and colliders

    NASA Astrophysics Data System (ADS)

    Di Mitri, S.; Cornacchia, M.

    2015-03-01

    Bunch length magnetic compression is used in high-brightness linacs driving free-electron lasers (FELs) and particle colliders to increase the peak current of the injected beam. To date, it is performed in dedicated insertions made of few degrees bending magnets and the compression factor is limited by the degradation of the beam transverse emittance owing to emission of coherent synchrotron radiation (CSR). We reformulate the known concept of CSR-driven optics balance for the general case of varying bunch length and demonstrate, through analytical and numerical results, that a 500 pC charge beam can be time-compressed in a periodic 180 deg arc at 2.4 GeV beam energy and lower, by a factor of up to 45, reaching peak currents of up to 2 kA and with a normalized emittance growth at the 0.1 μ \\text{m} rad level. The proposed solution offers new schemes of beam longitudinal gymnastics; an application to an energy recovery linac driving FEL is discussed.

  2. Investigation of Field Emitter Array Vacuum Microtriodes for Space Electronics Applications

    NASA Technical Reports Server (NTRS)

    Smith, Mark A.; Kapoor, Vik J.

    1997-01-01

    Research into processing techniques for fabrication of vacuum microelectronic devices has been carried out, with special emphasis being given to the growth of silicon dioxide thin films. Oxide films ranging from 30 nm to approximately 2 micrometers have been grown on single crystal silicon wafers. Metal-oxide-semiconductor capacitor test structures have been made from some of these oxide films, and current-versus-voltage plots for these structures have been measured. It has been observed that the rate of applied voltage across the oxide films produces marked differences in measured leakage current. Breakdown fields across two of the thinnest oxide films have been measured and are comparable with highest values reported in literature. Several silicon wafers were processed to make field- emitter array diodes, and were delivered to collaborators at NASA-Lewis Research Center for final fabrication steps and testing.

  3. Outreach activities within Auger

    NASA Astrophysics Data System (ADS)

    López Ramírez, Rebeca; Snow, Gregory

    2009-04-01

    The scale and scope of the physics studied at the Auger Observatory offer significant opportunities for original outreach work. Education, outreach, and public relations of the Auger collaboration are coordinated in a task of its own whose goals are to encourage and support a wide range of efforts that link schools and the public with the Auger scientists and the science of cosmic rays, particle physics, and associated technologies. This report focuses on the impact of the collaboration in Mendoza Province, Argentina, as: the Auger Visitor Center in Malargüe that has hosted over 29,000 visitors since 2001, the Auger Celebration and a collaboration-sponsored science fair held on the Observatory campus in November 2005, the opening of the James Cronin School in Malargüe in November 2006, public lectures, school visits, and courses for science teachers.

  4. Apparatus and method for compensating for electron beam emittance in synchronizing light sources

    DOEpatents

    Neil, G.R.

    1996-07-30

    A focused optical beam is used to change the path length of the core electrons in electron light sources thereby boosting their efficiency of conversion of electron beam energy to light. Both coherent light in the free electron laser and incoherent light in the synchrotron is boosted by this technique. By changing the path length of the core electrons by the proper amount, the core electrons are caused to stay in phase with the electrons in the outer distribution of the electron beam. This increases the fraction of the electron beam energy that is converted to light thereby improving the efficiency of conversion of energy to light and therefore boosting the power output of the free electron laser and synchrotron. 4 figs.

  5. Apparatus and method for compensating for electron beam emittance in synchronizing light sources

    DOEpatents

    Neil, George R.

    1996-01-01

    A focused optical beam is used to change the path length of the core electrons in electron light sources thereby boosting their efficiency of conversion of electron beam energy to light. Both coherent light in the free electron laser and incoherent light in the synchrotron is boosted by this technique. By changing the path length of the core electrons by the proper amount, the core electrons are caused to stay in phase with the electrons in the outer distribution of the electron beam. This increases the fraction of the electron beam energy that is converted to light thereby improving the efficiency of conversion of energy to light and therefore boosting the power output of the free electron laser and synchrotron.

  6. Current gain in sub-10 nm base GaN tunneling hot electron transistors with AlN emitter barrier

    SciTech Connect

    Yang, Zhichao Zhang, Yuewei; Nath, Digbijoy N.; Rajan, Siddharth; Khurgin, Jacob B.

    2015-01-19

    We report on Gallium Nitride-based tunneling hot electron transistor amplifier with common-emitter current gain greater than 1. Small signal current gain up to 5 and dc current gain of 1.3 were attained in common-emitter configuration with collector current density in excess of 50 kA/cm{sup 2}. The use of a combination of 1 nm GaN/3 nm AlN layers as an emitter tunneling barrier was found to improve the energy collimation of the injected electrons. These results represent demonstration of unipolar vertical transistors in the III-nitride system that can potentially lead to higher frequency and power microwave devices.

  7. High current, low emittance, steady state electron guns with plasma cathodes

    SciTech Connect

    Hershcovitch, A.

    1995-12-31

    Major limitations of plasma cathodes have been overcome in an electron gun based on extraction of superthermal electrons from a discharge characterized by a large component of high energy electrons with a low thermal spread. A grid is employed to select these electrons for extraction while retaining the bulk electrons in the discharge. Steady state extraction of electron beams corresponding to over 60% of the total arc discharge current has been observed. A perveance of over 280 microperv was reached with the extraction of 9A at 1 keV from a 6 nun aperture. Some of the characteristics of the electron beam described in this paper are very attractive for electron beam melting.

  8. Carbon and metal nanotube hybrid structures on graphene as efficient electron field emitters

    NASA Astrophysics Data System (ADS)

    Heo, Kwang; Lee, Byung Yang; Lee, Hyungwoo; Cho, Dong-guk; Arif, Muhammad; Kim, Kyu Young; Choi, Young Jin; Hong, Seunghun

    2016-07-01

    We report a facile and efficient method for the fabrication of highly-flexible field emission devices by forming tubular hybrid structures based on carbon nanotubes (CNTs) and nickel nanotubes (Ni NTs) on graphene-based flexible substrates. By employing an infiltration process in anodic alumina oxide (AAO) templates followed by Ni electrodeposition, we could fabricate CNT-wrapped Ni NT/graphene hybrid structures. During the electrodeposition process, the CNTs served as Ni nucleation sites, resulting in a large-area array of high aspect-ratio field emitters composed of CNT-wrapped Ni NT hybrid structures. As a proof of concepts, we demonstrate that high-quality flexible field emission devices can be simply fabricated using our method. Remarkably, our proto-type field emission devices exhibited a current density higher by two orders of magnitude compared to other devices fabricated by previous methods, while maintaining its structural integrity in various bending deformations. This novel fabrication strategy can be utilized in various applications such as optoelectronic devices, sensors and energy storage devices.

  9. Carbon and metal nanotube hybrid structures on graphene as efficient electron field emitters.

    PubMed

    Heo, Kwang; Lee, Byung Yang; Lee, Hyungwoo; Cho, Dong-Guk; Arif, Muhammad; Kim, Kyu Young; Choi, Young Jin; Hong, Seunghun

    2016-07-01

    We report a facile and efficient method for the fabrication of highly-flexible field emission devices by forming tubular hybrid structures based on carbon nanotubes (CNTs) and nickel nanotubes (Ni NTs) on graphene-based flexible substrates. By employing an infiltration process in anodic alumina oxide (AAO) templates followed by Ni electrodeposition, we could fabricate CNT-wrapped Ni NT/graphene hybrid structures. During the electrodeposition process, the CNTs served as Ni nucleation sites, resulting in a large-area array of high aspect-ratio field emitters composed of CNT-wrapped Ni NT hybrid structures. As a proof of concepts, we demonstrate that high-quality flexible field emission devices can be simply fabricated using our method. Remarkably, our proto-type field emission devices exhibited a current density higher by two orders of magnitude compared to other devices fabricated by previous methods, while maintaining its structural integrity in various bending deformations. This novel fabrication strategy can be utilized in various applications such as optoelectronic devices, sensors and energy storage devices. PMID:27233004

  10. Verification of surface polarity of O-face ZnO(0 0 0 1\\OverBar) by quantitative modeling analysis of Auger electron spectroscopy

    NASA Astrophysics Data System (ADS)

    Su, C. W.; Huang, M. S.; Tsai, T. H.; Chang, S. C.

    2012-12-01

    Is crystalline ZnO(0 0 0 1¯) O-face surface believed to be enriched by Zn atoms? This study may get the answer. We proposed a simplified model to simulate surface concentration ratio on (0 0 0 1¯)-O or (0 0 0 1)-Zn surface based on the hard-sphere model. The simulation ratio was performed by integrating electron signals from the assumed Auger emission, in which the electron mean free path and relative atomic layer arrangements inside the different polarity ZnO crystal surface were considered as relevant parameters. After counting more than 100 experimental observations of Zn/O ratios, the high frequency peak ratio was found at around 0.428, which was near the value predicted by the proposed model using the IMFP database. The ratio larger than the peak value corresponds to that observed in the annealed samples. A downward trend of the ratio evaluated on the post-sputtering sample indicates the possibility of a Zn-enriched phase appearing on the annealed O-face surface. This phenomenon can further elucidate the O-deficiency debate on most ZnO materials.

  11. Auger recombination and free-carrier absorption in nitrides from first principles

    NASA Astrophysics Data System (ADS)

    Kioupakis, Emmanouil

    2010-03-01

    Solid-state optoelectronic devices in the blue/green part of the visible spectrum, based on group-III-nitride materials and their alloys, have a wide array of applications as well as the potential to replace incandescent and fluorescent light bulbs for general illumination. Progress in nitride light emitters research, however, is hampered by the efficiency droop effect, a severe drop in quantum efficiency at high drive currents that particularly affects devices emitting at longer wavelengths. The efficiency droop has been the subject of extensive research and several mechanisms have been proposed as its origin. One such mechanism is the Auger recombination process, a non-radiative recombination mechanism induced by free carrier scattering via the Coulomb interaction. An additional loss mechanism that affects laser devices in particular is the reabsorption of the generated light by free carriers in the device. We used first-principles calculations to study the direct as well as the indirect Auger recombination and free-carrier absorption processes, mediated by electron-phonon and alloy scattering, and identify their importance in nitride light emitters. Since the various loss processes are hard to decouple experimentally, first-principles calculations are an indispensable tool to investigate the various loss mechanisms in isolation and determine their significance.

  12. Determination of the surface composition of binary alloys by auger electron spectroscopy: The gold-silver and gold-tin systems. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Overbury, S. H.

    1976-01-01

    Polycrystalline Au-Ag alloy foils of a wide range of composition were cleaned and equilibrated in ultra high vacuum. Using two different types of energy analyzers for comparison, the intensities of the Auger emission from transitions at several energies were measured and normalized to those of pure Au and Ag. A model developed to describe the intensity of Auger emission was applied to the intensities and the surface monolayer compositions of the alloys were thus determined. The Auger data were consistent with enrichment of Ag in the surface monolayer.

  13. Emittance Reduction between EBIS LINAC and Booster by Electron Beam Cooling; Is Single Pass Cooling Possible?

    SciTech Connect

    Hershcovitch,A.

    2008-04-01

    Electron beam cooling is examined as an option to reduce momentum of gold ions exiting the EBIS LINAC before injection into the booster. Electron beam parameters are based on experimental data (obtained at BNL) of electron beams extracted from a plasma cathode. Preliminary calculations indicate that single pass cooling is feasible; momentum spread can be reduced by more than an order of magnitude in less than one meter.

  14. Uncertainties in electron-absorbed fractions and lung doses from inhaled beta-emitters.

    PubMed

    Farfán, Eduardo B; Bolch, Wesley E; Huston, Thomas E; Rajon, Didier A; Huh, Chulhaeng; Bolch, W Emmett

    2005-01-01

    The computer code LUDUC (Lung Dose Uncertainty Code), developed at the University of Florida, was originally used to investigate the range of potential doses from the inhalation of either plutonium or uranium oxides. The code employs the ICRP Publication 66 Human Respiratory Tract model; however, rather than using simple point estimates for each of the model parameters associated with particle deposition, clearance, and lung-tissue dosimetry, probability density functions are ascribed to these parameters based upon detailed literature review. These distributions are subsequently sampled within LUDUC using Latin hypercube sampling techniques to generate multiple (e.g., approximately 1,000) sets of input vectors (i.e., trials), each yielding a unique estimate of lung dose. In the present study, the dosimetry component of the ICRP-66 model within LUDUC has been extended to explicitly consider variations in the beta particle absorbed fraction due to corresponding uncertainties and biological variabilities in both source and target tissue depths and thicknesses within the bronchi and bronchioles of the thoracic airways. Example dose distributions are given for the inhalation of absorption Type S compounds of 90Sr (Tmax = 546 keV) and 90Y (Tmax = 2,284 keV) as a function of particle size. Over the particle size range of 0.001 to 1 microm, estimates of total lung dose vary by a factor of 10 for 90Sr particles and by a factor of 4 to 10 for 90Y particles. As the particle size increases to 10 microm, dose uncertainties reach a factor of 100 for both radionuclides. In comparisons to identical exposures scenarios run by the LUDEP 2.0 code, Reference Man doses for inhaled beta-emitters were shown to provide slightly conservative estimates of lung dose compared to those in this study where uncertainties in lung airway histology are considered. PMID:15596988

  15. The Auger Engineering Radio Array

    NASA Astrophysics Data System (ADS)

    Fuchs, Benjamin

    2012-11-01

    High and ultra-high energy cosmic rays hitting the Earth's atmosphere cause extensive air showers (EAS). In recent years, these cosmic rays have been extensively studied at the Pierre Auger Observatory in Argentina. The EAS mainly consist of charged particles, especially electrons and positrons, which cause electro-magnetic emission in the MHz range by interaction with the Earth's magnetic field. To measure this radio emission, AERA, the Auger Engineering Radio Array, was deployed in October 2010 and commenced regular data acquisition in April 2011. AERA was designed as an engineering array for technology and methodology development towards future large-scale radio arrays. It will allow studies on the radio emission mechanism and the physics capabilities of the detection technique. AERA's unique site within the surface detector array (SD) of the Pierre Auger Observatory provides the possibility of coincident hybrid and super-hybrid EAS detection especially in overlap with the fluorescence telescopes Coihueco and HEAT. Besides a description of the setup, we present an overview of analyses of commissioning data taken between November 2010 and April 2011. Also, we show the first hybrid and self-triggered events detected with AERA in April 2011.

  16. Auger injuries in children.

    PubMed Central

    Letts, R. M.; Gammon, W.

    1978-01-01

    A 6-year review of auger injuries in Manitoba children revealed that 23 children sustained major injuries resulting in amputation of 17 limbs. Auger injuries are the main cause of traumatic amputation in children in Manitoba. Improved safety education for the entire farm family as well as better design of safety shields would decrease this carnage. Images FIG. 1 FIG. 3 FIG. 4 FIG. 5 FIG. 6 FIG. 9 PMID:630513

  17. Developments in on-line, electron-beam emittance measurements using optical transition radiation techniques

    SciTech Connect

    Feldman, R.B.; Lumpkin, A.H. ); Rule, D.W.; Fiorito, R.B. )

    1989-01-01

    We have developed image analysis software to facilitate the analysis of optical transition radiation (OTR) patterns generated by the electron beam from the Los Alamos free-electron laser facility. The software can be used for beam alignment, beam profile and angular divergence measurements, and the programs run on an IBM AT microcomputer. The programs and their use are described and some results shown. 2 refs., 17 figs.

  18. Apparatus for measuring the stopping power of active materials evaporated in situ and characterized by Auger electron spectrometry and Rutherford backscattering

    NASA Astrophysics Data System (ADS)

    Semrad, D.; Bauer, P.; Eder, K.; Obermann, W.

    1986-07-01

    An ultrahigh-vacuum scattering chamber working in the low 10-9-mbar range is described. It is attached to a standard O-ring sealed beam transport system of an electrostatic accelerator. Twelve targets can be prepared in situ, one by one, by evaporating the material onto backings, which are mounted on tiltable target holders on a wheel. Backscattering spectra are obtained from these targets and the stopping cross section is deduced from their widths. A cooled high-resolution surface barrier detector is used for this purpose. The integral concentrations of light impurities in the target are obtained using Rutherford backscattering (RBS), whereas Auger electron spectrometry (AES) together with a sputtering device is used to determine the depth composition. As a test of the assembly we determined the stopping power of aluminum for protons and deuterons, respectively. The results are compared to published tables based upon fits to experiments. The influence of impurities on the result is discussed for an aluminum target prepared under standard evaporation conditions.

  19. Investigation of Sn surface segregation during GeSn epitaxial growth by Auger electron spectroscopy and energy dispersive x-ray spectroscopy

    NASA Astrophysics Data System (ADS)

    Tsukamoto, Takahiro; Hirose, Nobumitsu; Kasamatsu, Akifumi; Mimura, Takashi; Matsui, Toshiaki; Suda, Yoshiyuki

    2015-02-01

    The mechanism of Sn surface segregation during the epitaxial growth of GeSn on Si (001) substrates was investigated by Auger electron spectroscopy and energy dispersive X-ray spectroscopy. Sn surface segregation depends on the growth temperature and Sn content of GeSn layers. During Sn surface segregation, Sn-rich nanoparticles form and move on the surface during the deposition, which results in a rough surface owing to facet formation. The Sn-rich nanoparticles moving on the surface during the deposition absorb Sn from the periphery and yield a lower Sn content, not on the surface but within the layer, because the Sn surface segregation and the GeSn deposition occur simultaneously. Sn surface segregation can occur at a lower temperature during the deposition compared with that during postannealing. This suggests that the Sn surface segregation during the deposition is strongly promoted by the migration of deposited Ge and Sn adatoms on the surface originating from the thermal effect of substrate temperature, which also suggests that limiting the migration of deposited Ge and Sn adatoms can reduce the Sn surface segregation and improve the crystallinity of GeSn layers.

  20. Apparatus for measuring the stopping power of active materials evaporated in situ and characterized by Auger electron spectrometry and Rutherford backscattering

    SciTech Connect

    Semrad, D.; Bauer, P.; Eder, K.; Obermann, W.

    1986-07-01

    An ultrahigh-vacuum scattering chamber working in the low 10/sup -9/-mbar range is described. It is attached to a standard O-ring sealed beam transport system of an electrostatic accelerator. Twelve targets can be prepared in situ, one by one, by evaporating the material onto backings, which are mounted on tiltable target holders on a wheel. Backscattering spectra are obtained from these targets and the stopping cross section is deduced from their widths. A cooled high-resolution surface barrier detector is used for this purpose. The integral concentrations of light impurities in the target are obtained using Rutherford backscattering (RBS), whereas Auger electron spectrometry (AES) together with a sputtering device is used to determine the depth composition. As a test of the assembly we determined the stopping power of aluminum for protons and deuterons, respectively. The results are compared to published tables based upon fits to experiments. The influence of impurities on the result is discussed for an aluminum target prepared under standard evaporation conditions.

  1. Surface change in titanium subhydride between 25 and 700/sup 0/C studied by Auger electron spectroscopy and x-ray photoelectron spectroscopy

    SciTech Connect

    Wang, P.S.; Carlson, R.S.; Wittberg, T.N.

    1982-07-09

    The surface sensitive spectroscopic techniques of Auger electron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS) have been applied to the study of the oxide dissolution of titanium and titanium subhydride. In an earlier study using AES, it was shown that the rate of oxygen dissolution into titanium increased sharply at approx. 350/sup 0/C. These data correlated well with physical property measurements that indicated an exothermic reaction was occurring at these temperatures which corresponded to the reaction of free Ti with atmospheric oxygen. In the present study the work has been expanded to include studies of TiH/sub x/ (x = 1.15, 1.62). It has been found that dissolution of the native oxide on titanium subhydride occurs at a temperature substantially higher (approx. 500/sup 0/C) than that required for titanium. It appears that the outward diffusion of hydrogen is inhibiting the inward diffusion of oxygen on the sub-hydride samples at temperatures below 500/sup 0/C.

  2. Spin-polarized electron emitter: Mn-doped GaN nanotubes and their arrays

    NASA Astrophysics Data System (ADS)

    Hao, Shaogang; Zhou, Gang; Wu, Jian; Duan, Wenhui; Gu, Bing-Lin

    2004-03-01

    The influences from the doping magnetic atom, Mn, on the geometry, electronic properties, and spin-polarization characteristics are demonstrated for open armchair gallium nitrogen (GaN) nanotubes and arrays by use of the first-principles calculations. The interaction between dangling bonds of Ga (Mn) and N atoms at the open-end promotes the self-close of the tube mouth and formation of a more stable open semicone top. Primarily owing to hybridization of Mn 3d and N 2p orbitals, one Mn atom introduces several impurity energy levels into the original energy gap, and the calculated magnetic moment is 4μB. The electron spin polarizations in the field emission are theoretically evaluated. We suggest that armchair open GaN nanotube arrays doped with a finite number of magnetic atoms may have application potential as the electron source of spintronic devices in the future.

  3. The growth of graphite phase on an iridium field electron emitter

    NASA Astrophysics Data System (ADS)

    Bernatskii, D. P.; Pavlov, V. G.

    2016-06-01

    The growth of graphite on the surface of an iridium tip in pyrolysis of benzene to give a ribbed crystal has been found by the methods of field electron and desorption microscopy. The formation of a graphite crystal results in the electric field factor increasing. The adsorption of alkali metals on the surface of graphite is accompanied by the intercalation effect.

  4. DNA Double Strand Breaks as Predictor of Efficacy of the Alpha-Particle Emitter Ac-225 and the Electron Emitter Lu-177 for Somatostatin Receptor Targeted Radiotherapy

    PubMed Central

    Graf, Franziska; Fahrer, Jörg; Maus, Stephan; Morgenstern, Alfred; Bruchertseifer, Frank; Venkatachalam, Senthil; Fottner, Christian; Weber, Matthias M.; Huelsenbeck, Johannes; Schreckenberger, Mathias; Kaina, Bernd; Miederer, Matthias

    2014-01-01

    Rationale Key biologic effects of the alpha-particle emitter Actinium-225 in comparison to the beta-particle emitter Lutetium-177 labeled somatostatin-analogue DOTATOC in vitro and in vivo were studied to evaluate the significance of γH2AX-foci formation. Methods To determine the relative biological effectiveness (RBE) between the two isotopes (as - biological consequence of different ionisation-densities along a particle-track), somatostatin expressing AR42J cells were incubated with Ac-225-DOTATOC and Lu-177-DOTATOC up to 48 h and viability was analyzed using the MTT assay. DNA double strand breaks (DSB) were quantified by immunofluorescence staining of γH2AX-foci. Cell cycle was analyzed by flow cytometry. In vivo uptake of both radiolabeled somatostatin-analogues into subcutaneously growing AR42J tumors and the number of cells displaying γH2AX-foci were measured. Therapeutic efficacy was assayed by monitoring tumor growth after treatment with activities estimated from in vitro cytotoxicity. Results Ac-225-DOTATOC resulted in ED50 values of 14 kBq/ml after 48 h, whereas Lu-177-DOTATOC displayed ED50 values of 10 MBq/ml. The number of DSB grew with increasing concentration of Ac-225-DOTATOC and similarly with Lu-177-DOTATOC when applying a factor of 700-fold higher activity compared to Ac-225. Already 24 h after incubation with 2.5–10 kBq/ml, Ac-225-DOTATOC cell-cycle studies showed up to a 60% increase in the percentage of tumor cells in G2/M phase. After 72 h an apoptotic subG1 peak was also detectable. Tumor uptake for both radio peptides at 48 h was identical (7.5%ID/g), though the overall number of cells with γH2AX-foci was higher in tumors treated with 48 kBq Ac-225-DOTATOC compared to tumors treated with 30 MBq Lu-177-DOTATOC (35% vs. 21%). Tumors with a volume of 0.34 ml reached delayed exponential tumor growth after 25 days (44 kBq Ac-225-DOTATOC) and after 21 days (34 MBq Lu-177-DOTATOC). Conclusion γH2AX-foci formation, triggered by beta- and

  5. WE-E-BRE-08: Impact of IUdR in Rat 9L Glioma Cell Survival for 25–35 KeV Photo-Activated Auger Electron Therapy

    SciTech Connect

    Alvarez, D; Hogstrom, K; Brown, T; Dugas, J; Varnes, M; Matthews, K

    2014-06-15

    Purpose: To determine the biological effect from Auger electrons with 9% and 18% iododeoxyuridine (IUdR) incorporated into the DNA of rat 9L glioma cells at photon energies above and below the K-edge of iodine (33.2 keV). Methods: Rat 9L glioma cell survival versus dose curves with 0%, 9%, and 18% thymidine replacement with IUdR were measured using four irradiation energies (4 MV x-rays; monochromatic 35, 30, and 25 keV synchrotron photons). For each of 11 conditions (Energy, %IUdR) survival curves were fit to the data (826 cell cultures) using the linear-quadratic model. The ratio of doses resulting in 10% survival gave sensitization enhancement ratios (SER10) from which contributions due to linear-energy transfer (LET), radiosensitization (RS), and Auger effect (AE) were extracted. Results: At 35, 30, and 25 keV, SER10,LET values were 1.08±0.03, 1.22±0.02, and 1.37±0.02, respectively. At 4 MV SER10,RS values for 9% and 18% IUdR were 1.28±0.02 and 1.40±0.02, respectively. Assuming LET effects are independent of %IUdR and radiosensitization effects are independent of energy, SER10,AE values for 18% IUdR at 35, 30, and 25 keV were 1.35±0.05, 1.06±0.03, and 0.98±0.03, respectively; values for 9% IUdR at 35 and 25 keV were 1.01±0.04 and 0.82±0.02, respectively. Conclusion: For 18% IUdR the radiosensitization effect of 1.40 and the Auger effect of 1.35 at 35 keV are equally important to the combined effect of 1.90. No measureable Auger effect was observed for energies below the K-edge at 20 and 25 keV, as expected. The insignificant Auger effect at 9% IUdR was not expected. Additional data (40–70 keV) and radiobiological modeling are being acquired to better understand the energy dependence of Auger electron therapy with IUdR. Funding support in part by the National Science Foundation Graduate Research Fellowship Program and in part by Contract No. W81XWH-10-1-0005 awarded by the U.S. Army Research Acquisition Activity. This paper does not necessarily

  6. Three dimensional simulation of the operation of a hollow cathode electron emitter on the Shuttle orbiter

    NASA Technical Reports Server (NTRS)

    Davis, V. A.; Katz, I.; Mandell, M. J.; Parks, D. E.

    1986-01-01

    Several researchers have suggested using hollow cathodes as plasma contactors for electrodynamic tethers, particularly to prevent the shuttle orbiter from charging to large negative potentials. Previous studies have shown that fluid models with anomalous scattering can describe the electron transport in hollow cathode generated plasmas. An improved theory of the hollow cathode plasmas is developed and computational results using the theory are compared with laboratory experiment. Numerical predictions for a hollow cathode plasma source of the type considered for use on the shuttle are presented as are three-dimensional NASCAP/LEO calculations of the emitted ion trajectories and the resulting potentials in the vicinity of the orbiter. The computer calculations show that the hollow cathode plasma source makes vastly superior contact with the ionospheric plasma compared with either an electron gun or passive ion collection by the orbiter.

  7. Selective Emitters

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L. (Inventor)

    1992-01-01

    This invention relates to a small particle selective emitter for converting thermal energy into narrow band radiation with high efficiency. The small particle selective emitter is used in combination with a photovoltaic array to provide a thermal to electrical energy conversion device. An energy conversion apparatus of this type is called a thermo-photovoltaic device. In the first embodiment, small diameter particles of a rare earth oxide are suspended in an inert gas enclosed between concentric cylinders. The rare earth oxides are used because they have the desired property of large emittance in a narrow wavelength band and small emittance outside the band. However, it should be emphasized that it is the smallness of the particles that enhances the radiation property. The small particle selective emitter is surrounded by a photovoltaic array. In an alternate embodiment, the small particle gas mixture is circulated through a thermal energy source. This thermal energy source can be a nuclear reactor, solar receiver, or combustor of a fossil fuel.

  8. Development of ballistic hot electron emitter and its applications to parallel processing: active-matrix massive direct-write lithography in vacuum and thin films deposition in solutions

    NASA Astrophysics Data System (ADS)

    Koshida, N.; Kojima, A.; Ikegami, N.; Suda, R.; Yagi, M.; Shirakashi, J.; Yoshida, T.; Miyaguchi, H.; Muroyama, M.; Nishino, H.; Yoshida, S.; Sugata, M.; Totsu, K.; Esashi, M.

    2015-03-01

    Making the best use of the characteristic features in nanocrystalline Si (nc-Si) ballistic hot electron source, the alternative lithographic technology is presented based on the two approaches: physical excitation in vacuum and chemical reduction in solutions. The nc-Si cold cathode is a kind of metal-insulator-semiconductor (MIS) diode, composed of a thin metal film, an nc-Si layer, an n+-Si substrate, and an ohmic back contact. Under a biased condition, energetic electrons are uniformly and directionally emitted through the thin surface electrodes. In vacuum, this emitter is available for active-matrix drive massive parallel lithography. Arrayed 100×100 emitters (each size: 10×10 μm2, pitch: 100 μm) are fabricated on silicon substrate by conventional planar process, and then every emitter is bonded with integrated complementary metal-oxide-semiconductor (CMOS) driver using through-silicon-via (TSV) interconnect technology. Electron multi-beams emitted from selected devices are focused by a micro-electro-mechanical system (MEMS) condenser lens array and introduced into an accelerating system with a demagnification factor of 100. The electron accelerating voltage is 5 kV. The designed size of each beam landing on the target is 10×10 nm2 in square. Here we discuss the fabrication process of the emitter array with TSV holes, implementation of integrated ctive-matrix driver circuit, the bonding of these components, the construction of electron optics, and the overall operation in the exposure system including the correction of possible aberrations. The experimental results of this mask-less parallel pattern transfer are shown in terms of simple 1:1 projection and parallel lithography under an active-matrix drive scheme. Another application is the use of this emitter as an active electrode supplying highly reducing electrons into solutions. A very small amount of metal-salt solutions is dripped onto the nc-Si emitter surface, and the emitter is driven without

  9. Chemical Vapor Deposited Few-Layer Graphene as an Electron Field Emitter.

    PubMed

    Behural, Sanjay K; Nayak, Sasmita; Yang, Qiaoqin; Hirose, Akira; Janil, Omkar

    2016-01-01

    Chemical vapor deposition (CVD) growth of graphene on polycrystalline copper (Cu) foil in a low pressure conditions has been presented, aiming to achieve the highest quality with large-scale fabrications, which requires comprehensive understanding and effective controlling of the growth process. Herein, few-layer graphene (FLG) films with large-domain sizes were grown on Cu metal catalyst substrates using a vertical mass-flow hot-filament CVD reactor, with the intention of large scale production, by optimizing the CVD system and three of the process parameters: (i) gas flow compositions, (ii) substrate annealing time and (iii) graphene deposition time. The detailed scanning electron microscope and Raman spectroscopy analysis indicate that all the above mentioned process parameters affect growth of FLG film on Cu substrate. The presence of two intense peaks, G and 2D-band at 1583.6 and 2702.6 cm⁻¹ for synthesized sample at optimized conditions (H₂/CH₄ ratio of 50:1 at graphene deposition time of 10 minutes and substrate annealed time for 20 minutes) revealed the formation of FLG films with large domain size. These graphene films on Cu have shown the room temperature field electron emission characteristics, hence appears to be prospective candidate for vacuum nanoelectronics. PMID:27398456

  10. Direct bonding between spacer and field emitter array using an electron-beam-evaporated interlayer

    NASA Astrophysics Data System (ADS)

    Park, Heung-Woo; Ju, Byeong-Kwon; Lee, Yun-Hi; Kang, In-Byeong; Samaan, Noel D.; Haskard, Malcolm R.; Park, Jung-Ho; Oh, Myung-Hwan

    1997-06-01

    This work reports a direct bonding method between silicon wafers using an interlayer. Thermal oxide, sputtered silicon nitride, molybdenum film and electron-beam evaporated silicon oxide were used as an interlayer. Silicon wafers were hydrophilized by one of the host nitric acid, the sulfuric acid based solution and the ammonium hydroxide based solution, mated at class 100 hemisphere and heat treated. After hydrophilization of silicon wafers, the changes of the surface roughness' were studied by the atomic force microscopy and the voids and the non-bonded areas were inspected by the infra-red transmission microscope. The bonding interfaces of the bonded pairs were inspected by a high resolution scanning electron microscope. Surface energies and tensile strengths of the bonded pairs were also tested by the crack propagation method and the push-pull meter, respectively. Surface energy of the Si-Si wafer pair annealed at 150 degree(s)C for 48 hours was about 7200 [erg/cm2] and its tensile strength was more than 18 MPa. This tensile strength is comparable with the bulk strength of the used silicon wafer.

  11. Auger processes in the 21st century

    PubMed Central

    Howell, Roger W.

    2012-01-01

    Purpose The extreme radiotoxicity of Auger electrons and their exquisite capacity to irradiate specific molecular sites has prompted scientists to extensively investigate their radiobiological effects. Their efforts have been punctuated by quadrennial international symposia that have focused on biophysical aspects of Auger processes. The latest meeting, the 6th International Symposium on Physical, Molecular, Cellular, and Medical Aspects of Auger Processes, was held 5–6 July 2007 at Harvard Medical School in Boston, Massachusetts, USA. This article provides a review of the research in this field that was published during the years 2004–2007, the period that has elapsed since the previous meeting. Conclusion The field has advanced considerably. A glimpse of the potential of this unique form of ionizing radiation to contribute to future progress in a variety of fields of study is proffered. PMID:19061120

  12. Bromine-80m-labeled estrogens: Auger-electron emitting, estrogen receptor-directed ligands with potential for therapy of estrogen receptor positive cancers

    SciTech Connect

    DeSombre, E.R.; Mease, R.C.; Hughes, A.; Harper, P.V.; DeJesus, O.T.; Friedman, A.M.

    1988-01-01

    A triphenylbromoethylene, 1,1-bis(p-hydroxyphenyl)-2-bromo-2-phenylethylene, Br-BHPE, and a bromosteroidal estrogen, 17..cap alpha..- bromovinylestradiol, BrVE/sub 2/, were labeled with the Auger electron emitting nuclide bromine-80m, prepared by the (p,n) reaction with /sup 80/Se. To assess their potential as estrogen receptor (ER) directed therapeutic substrates the bromine-80m labeled estrogens were injected into immature female rats and the tissue distribution studied at 0.5 and 2 hours. Both radiobromoestrogens showed substantial diethylstilbesterol (DES)-inhibitable localization in the ER rich tissues, uterus, pituitary, ovary and vagina at both time points. While the percent dose per gram tissue was higher for the Br-BHPE, the BrVE/sub 2/ showed higher tissue to blood ratios, especially at 2 hr, reflecting the lower blood concentrations of radiobromine following administration of the steroidal bromoestrogen. Comparing intraperitoneal, intravenous and subcutaneous routes of administration for the radiobromine labeled Br-BHPE, the intraperitoneal route was particularly advantageous to provide maximum, DES-inhibitable concentrations in the peritoneal, ER-rich target organs, the uterus, ovary and vagina. While uterine concentrations after BrBHPE were from 10--48% dose/g and after BrVE/sub 2/ were 15--25% dose/g, similar treatment with /sup 80m/Br as sodium bromide showed uniform low concentrations in all tissues at about the levels seen in blood. The effective specific activity of (/sup 80m/Br)BrBHPE, assayed by specific binding to ER in rat uterine cytosol, was 8700 Ci/mmole. 23 refs., 9 figs., 2 tabs.

  13. Tool for Guiding An Auger

    NASA Technical Reports Server (NTRS)

    Wesselski, C. J.

    1983-01-01

    Auger and Ram have same pitch, which minimizes damage to workpiece and load carried by auger. Auger firmly fastened onto ram shaft by screw and kept from rotating on shaft by slot machined into end of stem and male driving lug that engages slot. Used to install threaded studs in plastic or rubber where impractical to mold them in.

  14. An Auger electron spectroscopy study of the activation of iron Fischer-Tropsch catalysts. II. Carbon monoxide activation

    SciTech Connect

    Sault, A.G. ); Datye, A.K. )

    1993-03-01

    Activation procedures can have a dramatic effect on the activity of iron-based catalysts for Fischer-Tropsch (F-T) synthesis. CO conversion over a 100 Fe/3 Cu/0.2 K catalyst (parts by weight) can vary by nearly a factor of 3, depending on activation treatment. In contrast, a 100 Fe/5 Cu/4.2 K/25 SiO[sub 2] catalyst displays little dependence of F-T activity on activation treatment. An ultra-high vacuum surface analysis chamber coupled to an atmospheric reactor has been used to measure the surface composition of these catalysts following activation in carbon monoxide at 280[degrees]C, while transmission electron microscopy (TEM) and BET surface area measurements have been used to investigate catalyst morphology. CO activation of the 100 Fe/5 Cu/4.2 K/25 SiO[sub 2] catalyst at 280[degrees]C results in partial reduction of iron to a mixture of Fe[sub x]O and Fe[sub 3]O[sub 4], and an overall surface composition very similar to that obtained following hydrogen activation at 220 or 280[degrees]C, consistent with the invariance of F-T activity with activation treatment for this catalyst. Activation of the 100 Fe/3 Cu/0.2 K catalyst in CO at 280[degrees]C results in the formation of iron carbide particles, growth of graphitic carbon (C[sub g]) filaments, and formation of a thick, porous, C[sub g] layer covering the carbide particles. Differences in F-T activity between the hydrogen- and CO-activated 100 Fe/3 Cu/0.2 K catalyst are discussed in terms of surface composition and catalyst morphology. The difference in sensitivity of the two catalysts to activation conditions is related to differences in the extent of reduction of the catalysts. 45 refs., 4 figs., 1 tab.

  15. An Auger electron spectroscopy study of the activation of iron Fischer-Tropsch catalysts. I. Hydrogen activation

    SciTech Connect

    Sault, A.G. )

    1993-03-01

    Activation procedures can have a dramatic effect on the activity of iron-based catalysts for Fischer-Tropsch (F-T) synthesis. CO conversion over a 100 Fe/3 Cu/0.2 K catalyst (parts by weight) can vary by nearly a factor of 3, depending on activation. In contrast, a 100 Fe/5 Cu/4.2 K/25 SiO[sub 2] catalyst displays only minor variations in activity with activation conditions. An ultra-high vacuum surface analysis chamber coupled to an atmospheric pressure reactor has been used to measure the surface compositions of these catalysts following various hydrogen activation procedures. Activation of the 100 Fe/3 Cu/0.2 K catalyst in H[sub 2] results in rapid reduction of iron to the metallic state, and segregation of sulfur to the catalyst surface. The sulfur arises from bulk sulfate impurities present in the metal nitrates used to prepare the catalyst. Sulfur coverage increases with both activation time and temperature, due to an increase in the rate of sulfur diffusion with temperature. F-T activity of this catalyst varies inversely with sulfur coverage, consistent with the well-known poisoning effect of sulfur on F-T synthesis. For the 100 Fe/5 Cu/4.2 K/25 SiO[sub 2] catalyst no significant variations in surface composition are observed as a function of hydrogen activation temperature, consistent with the absence of any variations in catalyst activity. Only partial reduction of iron to a mixture of Fe[sub x]O and Fe[sub 3]O[sub 4] is observed for this catalyst for all activation conditions investigated. Using electron beam effects to remove potassium and silica shows that one or both of these components inhibits reduction of iron to the metallic state in the 100 Fe/5 Cu/4.2 K/25 SiO[sub 2] catalyst. 48 refs., 3 tabs.

  16. Auger-architectomics: introducing a new nanotechnology to infectious disease.

    PubMed

    Swart, Chantel W; Pohl, Carolina H; Kock, Johan L F

    2014-01-01

    In 2010, we developed a new imaging nanotechnology called Auger-architectomics, to study drug biosensors in nano-detail. We succeeded in applying Auger atom electron physics coupled to scanning electron microscopy (SEM) and Argon-etching to cell structure exploration, thereby exposing a new dimension in structure and element composition architecture. Auger-architectomics was used to expose the fate and effect of drugs on cells. This technology should now be expanded to diseased cells. This paper will outline the development, proof of concept, and application of this imaging nanotechnology. A virtual tour is available at: http://vimeo.com/user6296337 . PMID:24619614

  17. Effect Of Auger Recombination In An Ion Track

    NASA Technical Reports Server (NTRS)

    Edmonds, Larry D.

    1993-01-01

    Report presents theoretical calculations of contribution of Auger recombination to depletion of charge carriers from ionization track left by passage of energetic heavy ion through silicon-based electronic device.

  18. Photolithographic fabrication of gated self-aligned parallel electron beam emitters with a single-stranded carbon nanotube

    NASA Astrophysics Data System (ADS)

    Ho, Justin; Ono, Takahito; Tsai, Ching-Hsiang; Esashi, Masayoshi

    2008-09-01

    In this paper we report on the development of a photolithographic process to fabricate a gated-emitter array with single-stranded carbon nanotubes (CNTs) self-aligned to the center of the emitter gate using plasma-enhanced chemical vapor deposition (PECVD). Si tips are formed on a silicon wafer by anisotropic etching of Si using SiO2 as a mask. Deposition of a SiO2 insulating layer and Cr-W electrode layers creates protrusions above the Si tips. This wafer is polished, and the Cr-W on the tips is removed. Etching of the SiO2 using hydrofluoric acid is performed to expose the gated Si tip. Incorporation of a novel diffusion process produces single-stranded CNTs by depositing a thin Ni layer on the Si tips and thermally diffusing the Ni layer to yield a catalyst particle for single-stranded CNT growth. The large surface to volume ratio at the apex of the Si tip allows a Ni particle to remain to act as a catalyst to grow a single-stranded CNT for fabricating the CNT based emitter structure. Diffusion of the Ni is carried out in situ during the heating phase of the PECVD CNT growth process at 600 °C. The diameters of the observed CNTs are on the order of 20 nm. The field emission characteristics of the gated field emitters are evaluated. The measured turn-on voltage of the gated emitter is 5 V.

  19. First-Principle Electronic Properties of Dilute-P GaN(1-x)P(x) Alloy for Visible Light Emitters.

    PubMed

    Tan, Chee-Keong; Borovac, Damir; Sun, Wei; Tansu, Nelson

    2016-01-01

    A study on the electronic properties of the dilute-P GaN(1-x)P(x)alloy using First-Principle Density Functional Theory (DFT) calculations is presented. Our results indicate a band gap energy coverage from 3.645 eV to 2.697 eV, with P-content varying from 0% to 12.5% respectively. In addition, through line fitting of calculated and experimental data, a bowing parameter of 9.5 ± 0.5 eV was obtained. The effective masses for electrons and holes are analyzed, as well as the split-off energy parameters where findings indicate minimal interband Auger recombination. The alloy also possesses the direct energy band gap property, indicating its strong potential as a candidate for future photonic device applications. PMID:27076266

  20. First-Principle Electronic Properties of Dilute-P GaN1−xPx Alloy for Visible Light Emitters

    PubMed Central

    Tan, Chee-Keong; Borovac, Damir; Sun, Wei; Tansu, Nelson

    2016-01-01

    A study on the electronic properties of the dilute-P GaN1−xPx alloy using First-Principle Density Functional Theory (DFT) calculations is presented. Our results indicate a band gap energy coverage from 3.645 eV to 2.697 eV, with P-content varying from 0% to 12.5% respectively. In addition, through line fitting of calculated and experimental data, a bowing parameter of 9.5 ± 0.5 eV was obtained. The effective masses for electrons and holes are analyzed, as well as the split-off energy parameters where findings indicate minimal interband Auger recombination. The alloy also possesses the direct energy band gap property, indicating its strong potential as a candidate for future photonic device applications. PMID:27076266

  1. First-Principle Electronic Properties of Dilute-P GaN1‑xPx Alloy for Visible Light Emitters

    NASA Astrophysics Data System (ADS)

    Tan, Chee-Keong; Borovac, Damir; Sun, Wei; Tansu, Nelson

    2016-04-01

    A study on the electronic properties of the dilute-P GaN1‑xPx alloy using First-Principle Density Functional Theory (DFT) calculations is presented. Our results indicate a band gap energy coverage from 3.645 eV to 2.697 eV, with P-content varying from 0% to 12.5% respectively. In addition, through line fitting of calculated and experimental data, a bowing parameter of 9.5 ± 0.5 eV was obtained. The effective masses for electrons and holes are analyzed, as well as the split-off energy parameters where findings indicate minimal interband Auger recombination. The alloy also possesses the direct energy band gap property, indicating its strong potential as a candidate for future photonic device applications.

  2. Interference and PCI in argon Auger (e, 2e) spectra

    NASA Astrophysics Data System (ADS)

    Waterhouse, D. K.; Williams, J. F.

    1997-06-01

    Angle-dependent interference is observed in electron-impact ionization (e, 2e) coincidence experiments on the argon 0953-4075/30/12/013/img1 and 0953-4075/30/12/013/img2 Auger transitions. Recapture of the slow ejected electron from the Auger process leads to interference with the satellite-state ionization processes. The post-collision interaction (PCI) and interference effects are quantified for a large range of excess energies.

  3. First experimental test of quadrupole lens-free multiple profile monitor technique for electron beam emittance measurement with a PW laser system

    NASA Astrophysics Data System (ADS)

    Krus, M.; Levato, T.; Kim, H. T.; Grittani, G.; Margarone, D.; Jeong, T. M.; Mocek, T.; Korn, G.

    2015-05-01

    The quadrupole lens free multiple profile emittance measurement method is an adaptation of the standard multiple profile monitor method for electron beam emittance measurement which was tested at PW laser system. This single shot technique allows to obtain the emittance from beam profile radii fit by means of Twiss (Courant-Snyder) parameters. Lanex scintillating screens were used as profile monitors due to their high yield of visible photons. However, on the other hand, the screen is a source of multiple Coulomb scattering which can influence the beam profile on the following screens at relatively low electron energies. Nevertheless, the contribution of the multiple scattering can be effectively subtracted from the signal by e.g. Bayes unfolding. For high energy beams (E > 0.5 GeV), the multiple scattering contribution is negligible. The presented diagnostics is easy to be implemented into standard experimental setups without any special requests for alignment procedure. Moreover, it can be useful in the optimization phase of the laser plasma accelerator where beam fundamental parameters (energy, energy spread, divergence, pointing) typically fluctuate shot-to- shot.

  4. Auger Spectroscopy of Hydrogenated Diamond Surfaces

    NASA Technical Reports Server (NTRS)

    Krainsky, I. L.; Asnin, V. M.; Petukhov, A. G.; Foygel, M.

    1997-01-01

    An energy shift and a change of the line shape of the carbon core-valence-valence Auger spectra are observed for diamond surfaces after their exposure to an electron beam, or annealing at temperatures higher then 950 C. The effect is studied for both natural diamond crystals and chemical-vapor-deposited diamond films. A theoretical model is proposed for Auger spectra of hydrogenated diamond surfaces. The observed changes of the carbon Auger line shape are shown to be related to the redistribution of the valence-band local density of states caused by the hydrogen desorption from the surface. One-electron calculation of Auger spectra of diamond surfaces with various hydrogen coverages are presented. They are based on self-consistent wave functions and matrix elements calculated in the framework of the local-density approximation and the self-consistent linear muffin-tin orbital method with static core-hole effects taken into account. The major features of experimental spectra are explained.

  5. Development of ballistic hot electron emitter and its applications to parallel processing: active-matrix massive direct-write lithography in vacuum and thin-film deposition in solutions

    NASA Astrophysics Data System (ADS)

    Koshida, Nobuyoshi; Kojima, Akira; Ikegami, Naokatsu; Suda, Ryutaro; Yagi, Mamiko; Shirakashi, Junichi; Miyaguchi, Hiroshi; Muroyama, Masanori; Yoshida, Shinya; Totsu, Kentaro; Esashi, Masayoshi

    2015-07-01

    Making the best use of the characteristic features in nanocrystalline Si (nc-Si) ballistic hot electron source, an alternative lithographic technology is presented based on two approaches: physical excitation in vacuum and chemical reduction in solutions. The nc-Si cold cathode is composed of a thin metal film, an nc-Si layer, an n+-Si substrate, and an ohmic back contact. Under a biased condition, energetic electrons are uniformly and directionally emitted through the thin surface electrodes. In vacuum, this emitter is available for active-matrix drive massive parallel lithography. Arrayed 100×100 emitters (each emitting area: 10×10 μm2) are fabricated on a silicon substrate by a conventional planar process, and then every emitter is bonded with the integrated driver using through-silicon-via interconnect technology. Another application is the use of this emitter as an active electrode supplying highly reducing electrons into solutions. A very small amount of metal-salt solutions is dripped onto the nc-Si emitter surface, and the emitter is driven without using any counter electrodes. After the emitter operation, thin metal and elemental semiconductors (Si and Ge) films are uniformly deposited on the emitting surface. Spectroscopic surface and compositional analyses indicate that there are no significant contaminations in deposited thin films.

  6. Neutralization of space charge on high-current low-energy ion beam by low-energy electrons supplied from silicon based field emitter arrays

    SciTech Connect

    Gotoh, Yasuhito; Tsuji, Hiroshi; Taguchi, Shuhei; Ikeda, Keita; Kitagawa, Takayuki; Ishikawa, Junzo; Sakai, Shigeki

    2012-11-06

    Neutralization of space charge on a high-current and low-energy ion beam was attempted to reduce the divergence with an aid of low-energy electrons supplied from silicon based field emitter arrays (Si-FEAs). An argon ion beam with the energy of 500 eV and the current of 0.25 mA was produced by a microwave ion source. The initial beam divergence and the emittance were measured at the entrance of the analysis chamber in order to estimate the intrinsic factors for beam divergence. The current density distribution of the beam after transport of 730 mm was measured by a movable Faraday cup, with and without electron supply from Si-FEAs. A similar experiment was performed with tungsten filaments as an electron source. The results indicated that the electron supply from FEA had almost the same effect as the thermionic filament, and it was confirmed that both electron sources can neutralize the ion beam.

  7. EMITTANCE COMPENSATION FOR MAGNETIZED BEAMS

    SciTech Connect

    KEWISCH,J.; CHANG, X.

    2007-06-25

    Emittance compensation is a well established technique for minimizing the emittance of an electron beam from a RF photo-cathode gun. Longitudinal slices of a bunch have a small emittance, but due to the longitudinal charge distribution of the bunch and time dependent RF fields they are not focused in the same way, so that the direction of their phase ellipses diverges in phase space and the projected emittance is much larger. Emittance compensation reverses the divergence. At the location where the slopes of the phase ellipses coincide the beam is accelerated, so that the space charge forces are reduced. A recipe for emittance compensation is given in. For magnetized beams (where the angular momentum is non-zero) such emittance compensation is not sufficient because variations in the slice radius lead to variations in the angular speed and therefore to an increase of emittance in the rotating game. We describe a method and tools for a compensation that includes the beam magnetization.

  8. The Auger Star Monitor

    NASA Astrophysics Data System (ADS)

    Diaz, Johana; Nitz, David; Fick, Brian

    2006-04-01

    The Auger Star Monitor (ASM) is designed to automatically measure the total vertical atmospheric extinction above the Auger Observatory. The system continually takes wide-field CCD images of the night sky through a Johnson U-Band filter. Photometry is performed on the star images. The change in recorded star brightness as a function of zenith angle is used to obtain values for the integrated density of atmospheric scattering components. The MTU group has installed two ASMs; one at the Southern Observatory atop the Los Leones Fluorescence Detector building and one at the future site of the Northern Observatory in Colorado. Both of these units have been routinely operating during the past year. Much of our effort has turned to developing better data-reduction algorithms and automated software. Significant work has done to perfect the algorithms for image processing, star identification and photometry. Partial results of extinction coefficients obtained by the ASM will be presented.

  9. Photolithographic fabrication of gated self-aligned parallel electron beam emitters with a single-stranded carbon nanotube.

    PubMed

    Ho, Justin; Ono, Takahito; Tsai, Ching-Hsiang; Esashi, Masayoshi

    2008-09-10

    In this paper we report on the development of a photolithographic process to fabricate a gated-emitter array with single-stranded carbon nanotubes (CNTs) self-aligned to the center of the emitter gate using plasma-enhanced chemical vapor deposition (PECVD). Si tips are formed on a silicon wafer by anisotropic etching of Si using SiO(2) as a mask. Deposition of a SiO(2) insulating layer and Cr-W electrode layers creates protrusions above the Si tips. This wafer is polished, and the Cr-W on the tips is removed. Etching of the SiO(2) using hydrofluoric acid is performed to expose the gated Si tip. Incorporation of a novel diffusion process produces single-stranded CNTs by depositing a thin Ni layer on the Si tips and thermally diffusing the Ni layer to yield a catalyst particle for single-stranded CNT growth. The large surface to volume ratio at the apex of the Si tip allows a Ni particle to remain to act as a catalyst to grow a single-stranded CNT for fabricating the CNT based emitter structure. Diffusion of the Ni is carried out in situ during the heating phase of the PECVD CNT growth process at 600 °C. The diameters of the observed CNTs are on the order of 20 nm. The field emission characteristics of the gated field emitters are evaluated. The measured turn-on voltage of the gated emitter is 5 V. PMID:21828872

  10. Shielding in ungated field emitter arrays

    NASA Astrophysics Data System (ADS)

    Harris, J. R.; Jensen, K. L.; Shiffler, D. A.; Petillo, J. J.

    2015-05-01

    Cathodes consisting of arrays of high aspect ratio field emitters are of great interest as sources of electron beams for vacuum electronic devices. The desire for high currents and current densities drives the cathode designer towards a denser array, but for ungated emitters, denser arrays also lead to increased shielding, in which the field enhancement factor β of each emitter is reduced due to the presence of the other emitters in the array. To facilitate the study of these arrays, we have developed a method for modeling high aspect ratio emitters using tapered dipole line charges. This method can be used to investigate proximity effects from similar emitters an arbitrary distance away and is much less computationally demanding than competing simulation approaches. Here, we introduce this method and use it to study shielding as a function of array geometry. Emitters with aspect ratios of 102-104 are modeled, and the shielding-induced reduction in β is considered as a function of tip-to-tip spacing for emitter pairs and for large arrays with triangular and square unit cells. Shielding is found to be negligible when the emitter spacing is greater than the emitter height for the two-emitter array, or about 2.5 times the emitter height in the large arrays, in agreement with previously published results. Because the onset of shielding occurs at virtually the same emitter spacing in the square and triangular arrays, the triangular array is preferred for its higher emitter density at a given emitter spacing. The primary contribution to shielding in large arrays is found to come from emitters within a distance of three times the unit cell spacing for both square and triangular arrays.

  11. Shielding in ungated field emitter arrays

    SciTech Connect

    Harris, J. R.; Jensen, K. L.; Shiffler, D. A.; Petillo, J. J.

    2015-05-18

    Cathodes consisting of arrays of high aspect ratio field emitters are of great interest as sources of electron beams for vacuum electronic devices. The desire for high currents and current densities drives the cathode designer towards a denser array, but for ungated emitters, denser arrays also lead to increased shielding, in which the field enhancement factor β of each emitter is reduced due to the presence of the other emitters in the array. To facilitate the study of these arrays, we have developed a method for modeling high aspect ratio emitters using tapered dipole line charges. This method can be used to investigate proximity effects from similar emitters an arbitrary distance away and is much less computationally demanding than competing simulation approaches. Here, we introduce this method and use it to study shielding as a function of array geometry. Emitters with aspect ratios of 10{sup 2}–10{sup 4} are modeled, and the shielding-induced reduction in β is considered as a function of tip-to-tip spacing for emitter pairs and for large arrays with triangular and square unit cells. Shielding is found to be negligible when the emitter spacing is greater than the emitter height for the two-emitter array, or about 2.5 times the emitter height in the large arrays, in agreement with previously published results. Because the onset of shielding occurs at virtually the same emitter spacing in the square and triangular arrays, the triangular array is preferred for its higher emitter density at a given emitter spacing. The primary contribution to shielding in large arrays is found to come from emitters within a distance of three times the unit cell spacing for both square and triangular arrays.

  12. Vertically reciprocating auger

    NASA Technical Reports Server (NTRS)

    Etheridge, Mark; Morgan, Scott; Fain, Robert; Pearson, Jonathan; Weldi, Kevin; Woodrough, Stephen B., Jr.

    1988-01-01

    The mathematical model and test results developed for the Vertically Reciprocating Auger (VRA) are summarized. The VRA is a device capable of transporting cuttings that result from below surface drilling. It was developed chiefly for the lunar surface, where conventional fluid flushing while drilling would not be practical. The VRA uses only reciprocating motion and transports material through reflections with the surface above. Particles are reflected forward and land ahead of radially placed fences, which prevent the particles from rolling back down the auger. Three input wave forms are considered to drive the auger. A modified sawtooth wave form was chosen for testing, over a modified square wave or sine wave, due to its simplicity and effectiveness. The three-dimensional mathematical model predicted a sand throughput rate of 0.2667 pounds/stroke, while the actual test setup transported 0.075 pounds/stroke. Based on this result, a correction factor of 0.281 is suggested for a modified sawtooth input.

  13. Midwave Infrared (2-6{micro}m) Emitter-Based Chemical Sensor Systems

    SciTech Connect

    Allerman, A.A.; Biefeld, R.M.; Kurtz, S.R.

    1999-02-01

    Long wavelength (2-6 {micro}m) diode emitters are desirable for many applications including monitoring of chemical species in the environment and manufacturing, long wavelength fiber-optic communications, lidar, and JR detector counter-measures. No practical diode lasers are available for any of these applications because the band structure of bulk III-V, II-VI, and IV-VI semiconductor alloys results in large Auger recombination rates at these wavelengths. Experimental and theoretical work at Sandia has resulted in new understanding of the electronic properties of narrow bandgap III-V heterostructures, and we have found methods of reducing the Auger rates in certain InAsSb superlattices and quantum wells. These devices enable us to begin chemical sensing demonstrations of important species such as CO-CO{sub 2} and numerous other compounds. This project will involve developing chemical sensing systems and determining the sensitivity and limitations of these systems. Concurrently, we will improve upon infrared emitters used in these systems.

  14. FACET Emittance Growth

    SciTech Connect

    Frederico, J; Hogan, M.J.; Nosochkov, Y.; Litos, M.D.; Raubenheimer, T.; /SLAC

    2011-04-05

    FACET, the Facility for Advanced Accelerator and Experimental Tests, is a new facility being constructed in sector 20 of the SLAC linac primarily to study beam driven plasma wakefield acceleration. The FACET beamline consists of a chicane and final focus system to compress the 23 GeV, 3.2 nC electron bunches to {approx}20 {micro}m long and {approx}10 {micro}m wide. Simulations of the FACET beamline indicate the short-duration and large, 1.5% rms energy spread beams may suffer a factor of four emittance growth from a combination of chromaticity, incoherent synchrotron radiation (ISR), and coherent synchrotron radiation (CSR). Emittance growth is directly correlated to head erosion in plasma wakefield acceleration and is a limiting factor in single stage performance. Studies of the geometric, CSR, and ISR components are presented. Numerical calculation of the rms emittance can be overwhelmed by long tails in the simulated phase space distributions; more useful definitions of emittance are given. A complete simulation of the beamline is presented as well, which agrees with design specifications.

  15. Valence Auger decay following 3 s photoionization in potassium

    NASA Astrophysics Data System (ADS)

    Palaudoux, J.; Sheinerman, S.; Soronen, J.; Huttula, S.-M.; Huttula, M.; Jänkälä, K.; Andric, L.; Ito, K.; Lablanquie, P.; Penent, F.; Bizau, J.-M.; Guilbaud, S.; Cubaynes, D.

    2015-07-01

    We have studied photoionization in the inner valence 3 s subshell of K and the spectroscopic properties of the two 3 s-1(1S) and (3S) resulting states. Similar to the Rb and Cs cases, the lifetime widths of the (1S) and (3S) states are found to be markedly different, due to the electron correlation effects. The main part of the study deals with the subsequent Auger decay of the 3 s-1 states, which have the particularity to involve low energy (˜5 eV ) Auger electrons. A magnetic bottle spectrometer with a multicoincidence technique has been used to observe and filter the Auger spectra with respect to the K2 + final state. The evolution of these Auger spectra has been investigated near the ionization threshold. They show strong post-collision interaction (PCI) effects, which are well reproduced by semiclassical and eikonal models. They reveal the importance of the photoelectron-Auger-electron interaction associated with these low energy Auger electrons.

  16. Surface photovoltage and Auger electron spectromicroscopy studies of HfO2/SiO2/4H-SiC and HfO2/Al2O3/4H-SiC structures

    NASA Astrophysics Data System (ADS)

    Domanowska, A.; Miczek, M.; Ucka, R.; Matys, M.; Adamowicz, B.; Żywicki, J.; Taube, A.; Korwin-Mikke, K.; Gierałtowska, S.; Sochacki, M.

    2012-08-01

    The electronic and chemical properties of the interface region in the structures obtained by the passivation of epitaxial n-type 4H-SiC layers with bilayers consisting of a 5 nm-thick SiO2 or Al2O3 buffer film and high-κ HfO2 layer were investigated. The main aim was to estimate the influence of the passivation approach on the interface effective charge density (Qeff) from the surface photovoltage (SPV) method and, in addition to determine the in-depth element distribution in the interface region from the Auger electron spectroscopy (AES) combined with Ar+ ion profiling. The structure HfO2/SiO2/4H-SiC exhibited slightly superior electronic properties in terms of Qeff (in the range of -1011 q cm-2).

  17. The silicon photomultiplier as a metasystem with designed electronics as metadevice for a new receiver-emitter in visible light communications

    NASA Astrophysics Data System (ADS)

    Gutierrez, R. M.; Hernandez, A. I.; Castañeda, L. F.; Castaño, J. F.

    2015-09-01

    A Silicon Photomultiplier, SiPM, is a metasystem of Avalanche Photodiodes, APDs, which embedded in a specific purpose electronic, becomes a metadevice with unique and useful advanced functionalities to capture, transmit and analyze information with increased efficiency and security. The SiPM is a very small state of the art photo-detector with very high efficiency and sensitivity, with good response to controlled light pulses in the presence of background light without saturation. New results profit of such metadevice to propose a new receiver-emitter system useful for Visible Light Communication, VLC.

  18. Binary collision model for neon Auger spectra from neon ion bombardment of the aluminum surface

    NASA Technical Reports Server (NTRS)

    Pepper, S. V.

    1986-01-01

    A model is developed to account for the angle-resolved Auger spectra from neon ion bombardment of the aluminum surface recently obtained by Pepper and Aron. The neon is assumed to be excited in a single asymmetric neon-aluminum-collision and scattered back into the vacuum where it emits an Auger electron. The velocity of the Auger electron acquires a Doppler shift by virtue of the emission from a moving source. The dependence of the Auger peak shape and energy on the incident ion energy, angle of incidence and on the angle of Auger electron emission with respect to the surface is presented. Satisfactory agreement with the angle resolved experimental observations is obtained. The dependence of the angle-integrated Auger yield on the incident ion energy and angle of incidence is also obtained and shown to be in satisfactory agreement with available experimental evidence.

  19. Specific absorbed fractions from the image-based VIP-Man body model and EGS4-VLSI Monte Carlo code: internal electron emitters

    NASA Astrophysics Data System (ADS)

    Chao, T. C.; Xu, X. G.

    2001-04-01

    VIP-Man is a whole-body anatomical model newly developed at Rensselaer from the high-resolution colour images of the National Library of Medicine's Visible Human Project. This paper summarizes the use of VIP-Man and the Monte Carlo method to calculate specific absorbed fractions from internal electron emitters. A specially designed EGS4 user code, named EGS4-VLSI, was developed to use the extremely large number of image data contained in the VIP-Man. Monoenergetic and isotropic electron emitters with energies from 100 keV to 4 MeV are considered to be uniformly distributed in 26 organs. This paper presents, for the first time, results of internal electron exposures based on a realistic whole-body tomographic model. Because VIP-Man has many organs and tissues that were previously not well defined (or not available) in other models, the efforts at Rensselaer and elsewhere bring an unprecedented opportunity to significantly improve the internal dosimetry.

  20. Effect of external static magnetic field on the emittance and total charge of electron beams generated by laser-Wakefield acceleration.

    PubMed

    Hosokai, Tomonao; Kinoshita, Kenichi; Zhidkov, Alexei; Maekawa, Akira; Yamazaki, Atsushi; Uesaka, Mitsuru

    2006-08-18

    Significant enhancement of emittance and an increase of the total charge of femtosecond electron beams produced by a 12 TW, 40 fs laser pulse, tightly focused in a He gas jet, are observed after applying a static magnetic field, B> or =0.2 T, directed along the axis of laser pulse propagation. The effect appears when plasma produced by a laser prepulse becomes magnetized in the vicinity of the focus point: the electron Larmor frequency exceeds the collisional frequency, while periphery of the plasma remains unmagnetized. The entailed change in the shape of the plasma suppresses the diffraction of the main laser pulse that results in a much higher charge of electrons self-injected during the longitudinal wave breaking of the laser wake as well as the excellent stability of the beams. PMID:17026240

  1. Electron beam collimation with a 40 000 tip metallic double-gate field emitter array and in-situ control of nanotip sharpness distribution

    NASA Astrophysics Data System (ADS)

    Helfenstein, P.; Guzenko, V. A.; Fink, H.-W.; Tsujino, S.

    2013-01-01

    The generation of highly collimated electron beams from a double-gate field emitter array with 40000 metallic tips and large collimation gate apertures is reported. Field emission beam measurements demonstrated the reduction of the beam envelope down to the array size by applying a negative potential to the on-chip gate electrode for the collimation of individual field emission beamlets. Owing to the optimized gate structure, the concomitant decrease of the emission current was minimal, leading to a net enhancement of the current density. Furthermore, a noble gas conditioning process was successfully applied to the double-gate device to improve the beam uniformity in-situ with orders of magnitude increase of the active emission area. The results show that the proposed double-gate field emission cathodes are promising for high current and high brightness electron beam applications such as free-electron lasers and THz power devices.

  2. Trapped-electron effects on time-independent negative-bias states of a collisionless single-emitter plasma device: Theory and simulation

    SciTech Connect

    Crystal, T.L.; Gray, P.C.; Lawson, W.S.; Birdsall, C.K.; Kuhn, S. )

    1991-01-01

    Time-average values from particle simulations of a collisionless, single-emitter plasma device modeling single-ended {ital Q} machines or thermionic converters with a negatively biased collector are presented. These results quantitatively confirm the predictions of collisionless, kinetic plane-diode theory for spatial potential profiles that decrease monotonically. However, simulations of negative-bias potential profiles with a single internal maximum differ significantly from previous theoretical predictions which assumed electron phase space to have either (i) no trapped electrons or (ii) trapped electrons isothermal with the passing electrons. A more general class of trapped-electron model distributions is introduced from which new equilibrium potential values can be recovered that closely match the simulations. These simulations clearly demonstrate the sensitive role that trapped electrons play in shaping the potential profiles of the equilibrium (or slowly evolving) states of the simulated systems. The trapped-electron distributions in these simulations are themselves shown to be controlled critically by fluctuations whose levels are varied by the choice of particle injection scheme. These effects, although found and discussed here in the context of a particular model, are believed to be important in many bounded plasma systems where electrons can be trapped in potential wells.

  3. Atomic Auger Doppler effects upon emission of fast photoelectrons.

    PubMed

    Simon, Marc; Püttner, Ralph; Marchenko, Tatiana; Guillemin, Renaud; Kushawaha, Rajesh K; Journel, Loïc; Goldsztejn, Gildas; Piancastelli, Maria Novella; Ablett, James M; Rueff, Jean-Pascal; Céolin, Denis

    2014-01-01

    Studies of photoemission processes induced by hard X-rays including production of energetic electrons have become feasible due to recent substantial improvement of instrumentation. Novel dynamical phenomena have become possible to investigate in this new regime. Here we show a significant change in Auger emission following 1s photoionization of neon, which we attribute to the recoil of the Ne ion induced by the emission of a fast photoelectron. Because of the preferential motion of the ionized Ne atoms along two opposite directions, an Auger Doppler shift is revealed, which manifests itself as a gradual broadening and doubling of the Auger spectral features. This Auger Doppler effect should be a general phenomenon in high-energy photoemission of both isolated atoms and molecules, which will have to be taken into account in studies of other recoil effects such as vibrational or rotational recoil in molecules, and may also have consequences in measurements in solids. PMID:24906107

  4. Generation of energy bands in the electron beam with an asymmetric chicane-type emittance exchange beamline

    NASA Astrophysics Data System (ADS)

    Jiang, Bo-Cheng; Zhao, Zhen-tang; Feng, Chao

    2014-11-01

    An asymmetric chicane-type transverse to longitudinal emittance exchange beam line is investigated and presented in this paper. This design is more feasible for existing machines due to its coaxial arrangement of the components and dispense of symmetric requirement of two doglegs compared to two-dogleg type one. By inserting quadrupoles between the dogleg and deflecting cavity, the dispersion can be amplified and hence the bending angle of the chicane is reduced with the same deflecting cavity parameters which will reduce the coherent synchrotron radiation effect.

  5. Molecular cascade Auger decays following Si KL23L23 Auger transitions in SiCl4

    NASA Astrophysics Data System (ADS)

    Suzuki, I. H.; Bandoh, Y.; Mochizuki, T.; Fukuzawa, H.; Tachibana, T.; Yamada, S.; Takanashi, T.; Ueda, K.; Tamenori, Y.; Nagaoka, S.

    2016-08-01

    Cascade Si LVV Auger electron spectra at the photoexcitation of the Si 1s electron in a SiCl4 molecule have been measured using an electron spectrometer combined with monochromatized undulator radiation. In the instance of the resonant excitation of the Si 1s electron into the vacant molecular orbital a peak with high yield is observed at about 106 eV, an energy considerably higher than the energies of the normal LVV Auger electron. This peak is presumed to originate from the participator decay from the state with two 2p holes and one excited electron into the state with one 2p hole and one valence hole. Following the normal KL23L23 Auger transition, the cascade spectrum shows several peak structures, e.g. 63 eV, 76 eV and 91 eV. The peak at 91 eV is probably assigned to the second step Auger decay into states having a 2p hole together with two valence holes. These findings are similar to experimental results of SiF4. The former two peaks (63 eV and 76 eV) are ascribed to Auger transitions of Si atomic ions produced through molecular ion dissociation after the first step cascade decays, although the peak heights of atomic ions are lower than those of SiF4.

  6. Multielectron spectroscopy: Auger decays of the krypton 3d hole

    SciTech Connect

    Palaudoux, J.; Lablanquie, P.; Penent, F.; Andric, L.; Ito, K.; Shigemasa, E.; Eland, J. H. D.; Jonauskas, V.; Kucas, S.; Karazija, R.

    2010-10-15

    The emission of one or two Auger electrons, following Kr 3d inner-shell ionization by synchrotron light, has been investigated both experimentally and theoretically. All electrons emitted in the process are detected in coincidence and analyzed in energy thanks to a magnetic-bottle electron time-of-flight spectrometer. In addition, noncoincident high-resolution electron spectra have been measured to characterize the cascade double-Auger paths more fully. Combination of the two experimental approaches and of our calculations allows a full determination of the decay pathways and branching ratios in the case of Kr 3d single- and double-Auger decays. The Kr{sup 3+} threshold is found at 74.197{+-}0.020 eV.

  7. Multielectron spectroscopy: Auger decays of the krypton 3d hole

    NASA Astrophysics Data System (ADS)

    Palaudoux, J.; Lablanquie, P.; Andric, L.; Ito, K.; Shigemasa, E.; Eland, J. H. D.; Jonauskas, V.; Kučas, S.; Karazija, R.; Penent, F.

    2010-10-01

    The emission of one or two Auger electrons, following Kr 3d inner-shell ionization by synchrotron light, has been investigated both experimentally and theoretically. All electrons emitted in the process are detected in coincidence and analyzed in energy thanks to a magnetic-bottle electron time-of-flight spectrometer. In addition, noncoincident high-resolution electron spectra have been measured to characterize the cascade double-Auger paths more fully. Combination of the two experimental approaches and of our calculations allows a full determination of the decay pathways and branching ratios in the case of Kr 3d single- and double-Auger decays. The Kr3+ threshold is found at 74.197±0.020 eV.

  8. Stability of an emittance-dominated sheet-electron beam in planar wiggler and periodic permanent magnet structures with natural focusing

    NASA Astrophysics Data System (ADS)

    Carlsten, B. E.; Earley, L. M.; Krawczyk, F. L.; Russell, S. J.; Potter, J. M.; Ferguson, P.; Humphries, S.

    2005-06-01

    A sheet-beam traveling-wave amplifier has been proposed as a high-power generator of rf from 95 to 300 GHz, using a microfabricated rf slow-wave structure [Carlsten et al., IEEE Trans. Plasma Sci. 33, 85 (2005), ITPSBD, 0093-3813, 10.1109/TPS.2004.841172], for emerging radar and communications applications. The planar geometry of microfabrication technologies matches well with the nearly planar geometry of a sheet beam, and the greater allowable beam current leads to high-peak power, high-average power, and wide bandwidths. Simulations of nominal designs using a vane-loaded waveguide as the slow-wave structure have indicated gains in excess of 1 dB/mm, with extraction efficiencies greater than 20% at 95 GHz with a 120-kV, 20-A electron beam. We have identified stable sheet-beam formation and transport as the key enabling technology for this type of device. In this paper, we describe sheet-beam transport, for both wiggler and periodic permanent magnet (PPM) magnetic field configurations, with natural (or single-plane) focusing. For emittance-dominated transport, the transverse equation of motion reduces to a Mathieu equation, and to a modified Mathieu equation for a space-charge dominated beam. The space-charge dominated beam has less beam envelope ripple than an emittance-dominated beam, but they have similar stability thresholds (defined by where the beam ripple continues to grow without bound along the transport line), consistent with the threshold predicted by the Mathieu equation. Design limits are derived for an emittance-dominated beam based on the Mathieu stability threshold. The increased beam envelope ripple for emittance-dominated transport may impact these design limits, for some transport requirements. The stability of transport in a wiggler field is additionally compromised by the beam’s increased transverse motion. Stable sheet-beam transport with natural focusing is shown to be achievable for a 120-kV, 20-A, elliptical beam with a cross section of

  9. Pierre Auger Results

    SciTech Connect

    Chou, Aaron

    2008-01-14

    Using data collected at the Pierre Auger Observatory during the past 3.7 years, we demonstrate that there is a correlation between the arrival directions of cosmic rays with energy above 6 [1] 1019 eV and the positions of active galactic nuclei (AGN) lying within 75 Mpc. We reject the hypothesis of an isotropic distribution of these cosmic rays at over 99% confidence level from a prescribed a priori test. The correlation we observe is compatible with the hypothesis that the highest energy particles originate from relatively nearby extragalactic sources whose fluxes have therefore not been significantly reduced by interaction with the cosmic background radiation. AGN or objects having a similar spatial distribution are possible sources.

  10. Auger recombination in InN from first principles

    NASA Astrophysics Data System (ADS)

    McAllister, Andrew; Kioupakis, Emmanouil

    Group-III Nitride materials are used in numerous electronic and optoelectronic devices including solid-state lighting, energy conversion, sensor technologies, and high-power electronics. Indium nitride in particular is interesting for fast electronics and optoelectronics in the infrared. Auger recombination is a non-radiative carrier recombination process that would limit the efficiency of these devices. The small band gap (0.7 eV) and the high intrinsic free-electron concentrations in InN possibly make Auger recombination particularly important in this material. We used first-principles computational methods to determine the Auger recombination rates in InN. Our results suggest that direct Auger recombination is dominant in this material and that phonon-assisted Auger processes are not as important as in wider-gap nitrides such as GaN. This research was supported by the National Science Foundation CAREER award through Grant No. DMR-1254314. Computational resources were provided by the DOE NERSC facility.

  11. Auger spectroscopy of fracture surfaces of ceramics

    NASA Technical Reports Server (NTRS)

    Marcus, H. L.; Harris, J. M.; Szalkowski, F. J.

    1974-01-01

    Results of Auger electron spectroscopy (AES) studies of fracture surfaces in a series of ceramic materials, including Al2O3, MgO, and Si3N4, which were formed using different processing techniques. AES on the fractured surface of a lunar sample is also discussed. Scanning electron micrograph fractography is used to relate the surface chemistry to the failure mode. Combined argon ion sputtering and AES studies demonstrate the local variations in chemistry near the fracture surface. The problems associated with doing AES in insulators are also discussed, and the experimental techniques directed toward solving them are described.

  12. Selective generation and extraction of low emittance electrons from plasmas: A new concept for E-beam cathodes

    SciTech Connect

    Hershcovitch, A.

    1991-09-19

    It is shown that hollow cathode discharges can operate in a mode characterized by a two-component electron energy distribution: bulk electrons with a thermal distribution with a temperature of a few electron volts, and a component of fast electrons with an energy of about 30 eV and a thermal spread of about 0.1 eV. Measurements of both parallel and perpendicular energy spreads confirm the existence of fast, low energy spread electrons. Selective extraction of these electrons can form the basis of a high current, high brightness electron gun which could be well suited for EBIS applications. 8 refs., 4 figs., 1 tab.

  13. Emittance Theory for Thin Film Selective Emitter

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.; Lowe, Roland A.; Good, Brian S.

    1994-01-01

    Thin films of high temperature garnet materials such as yttrium aluminum garnet (YAG) doped with rare earths are currently being investigated as selective emitters. This paper presents a radiative transfer analysis of the thin film emitter. From this analysis the emitter efficiency and power density are calculated. Results based on measured extinction coefficients for erbium-YAG and holmium-YAG are presented. These results indicated that emitter efficiencies of 50 percent and power densities of several watts/sq cm are attainable at moderate temperatures (less than 1750 K).

  14. Direct first-principles simulation of a high-performance electron emitter: Lithium-oxide-coated diamond surface

    SciTech Connect

    Miyamoto, Yoshiyuki Miyazaki, Takehide; Takeuchi, Daisuke; Yamasaki, Satoshi

    2014-09-28

    We examined the field emission properties of lithium(Li)/oxygen(O)-co-terminated diamond (001) surface [C(001)-LiO] through real-time electron dynamics simulation under an applied field. The current emitted from this surface was found to be more than four-fold that emitted by an H-terminated (001) surface, the latter being a typical negative electron affinity system. This high performance is attributed to the Li layer, which bends the potential wall of O-induced electron pockets down in the direction of vacuum, thus facilitating electron emission. Detailed analysis of the emitted electrons and the profile of the self-consistent potential elucidated that the role of O atoms changes from an electron barrier on OH-terminated diamond surfaces to an outlet for electron emission on C(001)-LiO.

  15. Intrinsic emittance reduction in transmission mode photocathodes

    NASA Astrophysics Data System (ADS)

    Lee, Hyeri; Cultrera, Luca; Bazarov, Ivan

    2016-03-01

    High quantum efficiency (QE) and low emittance electron beams provided by multi-alkali photocathodes make them of great interest for next generation high brightness photoinjectors. Spicer's three-step model well describes the photoemission process; however, some photocathode characteristics such as their thickness have not yet been completely exploited to further improve the brightness of the generated electron beams. In this work, we report on the emittance and QE of a multi-alkali photocathode grown onto a glass substrate operated in transmission and reflection modes at different photon energies. We observed a 20% reduction in the intrinsic emittance from the reflection to the transmission mode operation. This observation can be explained by inelastic electron-phonon scattering during electrons' transit towards the cathode surface. Due to this effect, we predict that thicker photocathode layers will further reduce the intrinsic emittance of electron beams generated by photocathodes operated in transmission mode.

  16. Emittance Theory for Cylindrical Fiber Selective Emitter

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.

    1998-01-01

    A fibrous rare earth selective emitter is approximated as an infinitely long, cylinder. The spectral emittance, e(sub x), is obtained L- by solving the radiative transfer equations with appropriate boundary conditions and uniform temperature. For optical depth, K(sub R), where alpha(sub lambda), is the extinction coefficient and R is the cylinder radius, greater than 1 the spectral emittance depths, K(sub R) alpha(sub lambda)R, is nearly at its maximum value. There is an optimum cylinder radius, R(sub opt) for maximum emitter efficiency, n(sub E). Values for R(sub opt) are strongly dependent on the number of emission bands of the material. The optimum radius decreases slowly with increasing emitter temperature, while the maximum efficiency and useful radiated power increase rapidly with increasing, temperature.

  17. Emittance Theory for Cylindrical Fiber Selective Emitter

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.

    1998-01-01

    A fibrous rare earth selective emitter is approximated as an infinitely long cylinder. The spectral emittance, epsilon(lambda), is obtained by solving the radiative transfer equations with appropriate boundary conditions and uniform temperature. For optical depths, Kappa(R) = alpha(lambda)R, where alpha(lambda) is the extinction coefficient and R is the cylinder radius, greater than 1 the spectral emittance is nearly at its maximum value. There is an optimum cylinder radius, R(opt), for maximum emitter efficiency, eta(E). Values for R(opt) are strongly dependent on the number of emission bands of the material. The optimum radius decreases slowly with increasing emitter temperature, while the maximum efficiency and useful radiated power increase rapidly with increasing temperature.

  18. El proyecto AUGER

    NASA Astrophysics Data System (ADS)

    Etchegoyen, A.

    Hace ya más de 30 años en Volcano Ranch, EE.UU., un extenso chubasco cósmico (ECC) fue detectado con energía en exceso de 1020 eV. Desde entonces, observatorios ubicados en Haverah Park del Reino Unido, Yakutsk de Rusia, AGASA de Japón y Dugway de EE.UU. también han observado ECC con energías mayores que 1020 eV. Poco se sabe de dichos rayos, y en particular cuál es la naturaleza del primario, de dónde provienen, y cómo son acelerados, pero su naturaleza ultrarelativista excluye la mayoría de las respuestas dejando sólo algunas plausibles de ser investigadas experimentalmente. Grupos de científicos de 20 países están trabajando con el fin de construir dos arreglos de detectores gigantes, uno en cada hemisferio a lo largo de 3000 km2 c/u. Dichas dimensiones son necesarias debido al flujo estimado de 1 rayo cósmico/centuria/km2/sr. La sede del Observatorio del Sur es la Argentina. El proyecto fue nombrado Pierre Auger en conmemoración del célebre físico francés que detectó por primera vez chubascos cósmicos en 1938. El proyecto focaliza su interés en rayos cósmicos con energías mayores que 1020 eV.

  19. Performance comparisons of low emittance lattices

    SciTech Connect

    Delahaye, J.P.; Zisman, M.S.

    1987-05-01

    In this paper, the results of a performance analysis of several low emittance electron storage ring lattices provided by various members of the Lattice Working Group are presented. Altogether, four lattices were investigated. There are two different functions being considered for the low beam emittance rings discussed here. The first is to serve as a Damping Ring (DR), i.e., to provide the emittance damping required for a high energy linear collider. The second is to provide beams for a short wavelength Free Electron Laser (FEL), which is envisioned to operate in the wavelength region near 40 A.

  20. Auger width of metastable states in antiprotonic helium

    SciTech Connect

    Revai, J.; Kruppa, A.T.

    1998-01-01

    Auger decay probabilities of metastable states in antiprotonic helium are derived using a minimal extension of the existing bound-state wave functions to account for the electron continuum. Calculations were performed for the Born-Oppenheimer wave functions of Shimamura [Phys. Rev. A {bold 46}, 3776 (1992)] and the variational wave functions of Korobov [Phys. Rev. A {bold 54}, 1749 (1996)]. Our results suggest that the overall accuracy of the Auger widths calculated from the presently available bound-state wave functions is not sufficient. {copyright} {ital 1998} {ital The American Physical Society}

  1. Floating emitter solar cell

    NASA Technical Reports Server (NTRS)

    Chih, Sah (Inventor); Cheng, Li-Jen (Inventor)

    1987-01-01

    A front surface contact floating emitter solar cell transistor is provided in a semiconductor body (n-type), in which floating emitter sections (p-type) are diffused or implanted in the front surface. Between the emitter sections, a further section is diffused or implanted in the front surface, but isolated from the floating emitter sections, for use either as a base contact to the n-type semiconductor body, in which case the section is doped n+, or as a collector for the adjacent emitter sections.

  2. Some applications of Photon/Electron-Rejecting Alpha Liquid Scintillation (PERALS) spectrometry to the assay of alpha emitters

    SciTech Connect

    McDowell, W.J.; Case, G.N.

    1988-01-01

    The combination of certain solvent extraction separations and a special kind of liquid scintillation detector and electronics designed for alpha spectrometry allows some highly accurate, yet simple determinations of alpha-emitting nuclides. Counting efficiency is 99.68% with backgrounds of <0.02 cpm. Energy resolution and peak position are sufficient for the identification of many nuclides. Rejection of interference from ..beta.. and ..gamma.. radiation is >99.95%. The Photon/Electron Rejecting Alpha Liquid Scintillation (PERALS) equipment is described and procedures for the separation and determination of uranium, thorium, plutonium, polonium, radium, and trivalent actinides are outlined. 25 refs., 10 figs., 1 tab.

  3. Auger parameter and Wagner plot studies of small copper clusters

    NASA Astrophysics Data System (ADS)

    Moretti, Giuliano; Palma, Amedeo; Paparazzo, Ernesto; Satta, Mauro

    2016-04-01

    We discuss application of the Auger parameter and Wagner plot concepts to the study of small copper clusters deposited on various supports such as C(graphite), SiO2 and Al2O3. We demonstrate that the cluster size and the electronic properties of the support influence the shifts of both the binding energy of the Cu 2p3/2 transition and the kinetic energy of the Cu L3M45M45; 1G Auger transition. We find that the Cu L3M45M45; 1G-2p3/2 Auger parameter and Wagner plot allow one to single out and measure both initial- and final-state effects with a detail which is superior to that achieved in photoemission studies.

  4. Direct and Auger Electron-Induced, Single- and Double-Strand Breaks on Plasmid DNA Caused by 99mTc-Labeled Pyrene Derivatives and the Effect of Bonding Distance.

    PubMed

    Reissig, Falco; Mamat, Constantin; Steinbach, Joerg; Pietzsch, Hans-Juergen; Freudenberg, Robert; Navarro-Retamal, Carlos; Caballero, Julio; Kotzerke, Joerg; Wunderlich, Gerd

    2016-01-01

    It is evident that 99mTc causes radical-mediated DNA damage due to Auger electrons, which were emitted simultaneously with the known γ-emission of 99mTc. We have synthesized a series of new 99mTc-labeled pyrene derivatives with varied distances between the pyrene moiety and the radionuclide. The pyrene motif is a common DNA intercalator and allowed us to test the influence of the radionuclide distance on damages of the DNA helix. In general, pUC 19 plasmid DNA enables the investigation of the unprotected interactions between the radiotracers and DNA that results in single-strand breaks (SSB) or double-strand breaks (DSB). The resulting DNA fragments were separated by gel electrophoresis and quantified by fluorescent staining. Direct DNA damage and radical-induced indirect DNA damage by radiolysis products of water were evaluated in the presence or absence of the radical scavenger DMSO. We demonstrated that Auger electrons directly induced both SSB and DSB in high efficiency when 99mTc was tightly bound to the plasmid DNA and this damage could not be completely prevented by DMSO, a free radical scavenger. For the first time, we were able to minimize this effect by increasing the carbon chain lengths between the pyrene moiety and the 99mTc nuclide. However, a critical distance between the 99mTc atom and the DNA helix could not be determined due to the significantly lowered DSB generation resulting from the interaction which is dependent on the type of the 99mTc binding motif. The effect of variable DNA damage caused by the different chain length between the pyrene residue and the Tc-core as well as the possible conformations of the applied Tc-complexes was supplemented with molecular dynamics (MD) calculations. The effectiveness of the DNA-binding 99mTc-labeled pyrene derivatives was demonstrated by comparison to non-DNA-binding 99mTcO4-, since nearly all DNA damage caused by 99mTcO4- was prevented by incubating with DMSO. PMID:27583677

  5. Light modulated switches and radio frequency emitters

    DOEpatents

    Wilson, Mahlon T.; Tallerico, Paul J.

    1982-01-01

    The disclosure relates to a light modulated electron beam driven radiofrequency emitter. Pulses of light impinge on a photoemissive device which generates an electron beam having the pulse characteristics of the light. The electron beam is accelerated through a radiofrequency resonator which produces radiofrequency emission in accordance with the electron, hence, the light pulses.

  6. Negative Ion Beam Extraction and Emittance

    SciTech Connect

    Holmes, Andrew J. T.

    2007-08-10

    The use of magnetic fields to both aid the production of negative ions and suppress the co-extracted electrons causes the emittance and hence the divergence of the negative ion beam to increase significantly due to the plasma non-uniformity from jxB drift. This drift distorts the beam-plasma meniscus and experimental results of the beam emittance are presented, which show that non-uniformity causes the square of the emittance to be proportional to the 2/3 power of the extracted current density. This can cause the divergence of the negative ion beam to be significantly larger than its positive ion counterpart. By comparing results from positive and negative ion beam emittances from the same source, it is also possible to draw conclusions about their vulnerability to magnetic effects. Finally emittances of caesiated and un-caesiated negative ion beams are compared to show how the surface and volume modes of production interact.

  7. Manipulation of resonant Auger processes with strong optical fields

    NASA Astrophysics Data System (ADS)

    Picón, Antonio; Buth, Christian; Doumy, Gilles; Krässig, Bertold; Young, Linda; Southworth, Stephen

    2013-05-01

    We recently reported on the optical control of core-excited states of a resonant Auger process in neon. We have focused on the resonant excitation 1 s --> 1s-1 3 p , while a strong optical field may resonantly couple two core-excited states (1s-1 3 p and 1s-1 3 s) in the Rydberg manifold as well as dressing the continuum. There is a clear signature in the Auger electron spectrum of the inner-shell dynamics induced by the strong optical field: i) the Auger electron spectrum is modified by the rapid optical-induced population transfer from the 1s-1 3 p state to the 1s-1 3 s state during their decay. ii) The angular anisotropy parameter, defining the angular distribution of the Auger electron, is manifested in the envelope of the (angle-integrated) sidebands. This work is funded by the Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy, under Contract No. DE-AC02-06CH11357.

  8. Auger analysis of films formed on metals in sliding contact with halogenated polymers

    NASA Technical Reports Server (NTRS)

    Pepper, S. V.

    1974-01-01

    The use of Auger electron spectroscopy (AES) to search for transferred polymer must contend with the fact that there has been no published work on Auger analysis of polymers. Since this is a new area for AES, the Auger spectra of polymers and of halogenated polymers in particular is discussed. It is shown that the Auger spectra of halogenated polymers have certain characteristics that permit an assessment of whether a polymeric transfer film has been established by sliding contact. The discussion is general and the concepts should be useful in considering the Auger analysis of any polymer. The polymers chosen for this study are the halogenated polymers polytetrafluoroethylene (PTFE), polyvinyl chloride (PVC), and polychlorotrifluorethylene (PCTFE).

  9. Bright Single Photon Emitter in Silicon Carbide

    NASA Astrophysics Data System (ADS)

    Lienhard, Benjamin; Schroeder, Tim; Mouradian, Sara; Dolde, Florian; Trong Tran, Toan; Aharonovich, Igor; Englund, Dirk

    Efficient, on-demand, and robust single photon emitters are of central importance to many areas of quantum information processing. Over the past 10 years, color centers in solids have emerged as excellent single photon emitters. Color centers in diamond are among the most intensively studied single photon emitters, but recently silicon carbide (SiC) has also been demonstrated to be an excellent host material. In contrast to diamond, SiC is a technologically important material that is widely used in optoelectronics, high power electronics, and microelectromechanical systems. It is commercially available in sizes up to 6 inches and processes for device engineering are well developed. We report on a visible-spectrum single photon emitter in 4H-SiC. The emitter is photostable at both room and low temperatures, and it enables 2 million photons/second from unpatterned bulk SiC. We observe two classes of orthogonally polarized emitters, each of which has parallel absorption and emission dipole orientations. Low temperature measurements reveal a narrow zero phonon line with linewidth < 0.1 nm that accounts for more than 30% of the total photoluminescence spectrum. To our knowledge, this SiC color emitter is the brightest stable room-temperature single photon emitter ever observed.

  10. Auger electron spectroscopy study of surface segregation in the binary alloys copper-1 atomic percent indium, copper-2 atomic percent tin, and iron-6.55 atomic percent silicon

    NASA Technical Reports Server (NTRS)

    Ferrante, J.

    1973-01-01

    Auger electron spectroscopy was used to examine surface segregation in the binary alloys copper-1 at. % indium, copper-2 at. % tin and iron-6.55 at. % silicon. The copper-tin and copper-indium alloys were single crystals oriented with the /111/ direction normal to the surface. An iron-6.5 at. % silicon alloy was studied (a single crystal oriented in the /100/ direction for study of a (100) surface). It was found that surface segregation occurred following sputtering in all cases. Only the iron-silicon single crystal alloy exhibited equilibrium segregation (i.e., reversibility of surface concentration with temperature) for which at present we have no explanation. McLean's analysis for equilibrium segregation at grain boundaries did not apply to the present results, despite the successful application to dilute copper-aluminum alloys. The relation of solute atomic size and solubility to surface segregation is discussed. Estimates of the depth of segregation in the copper-tin alloy indicate that it is of the order of a monolayer surface film.

  11. Dynamics of Intraband and Interband Auger Processes in Colloidal Core-Shell Quantum Dots.

    PubMed

    Rabouw, Freddy T; Vaxenburg, Roman; Bakulin, Artem A; van Dijk-Moes, Relinde J A; Bakker, Huib J; Rodina, Anna; Lifshitz, Efrat; L Efros, Alexander; Koenderink, A Femius; Vanmaekelbergh, Daniël

    2015-10-27

    Conventional colloidal quantum dots (QDs) suffer from rapid energy losses by nonradiative (Auger) processes, leading to sub-ns lifetimes in all excited states but the lowest-energy single exciton. Suppression of interband Auger decay, such as biexciton Auger recombination, has been achieved with the design of heterostructured core-shell QDs. Auger-like processes are also believed to be responsible for rapid intraband hot-electron cooling in QDs. However, the simultaneous effect of shell growth on interband Auger recombination and intraband hot-electron cooling has not been addressed. Here we investigate how the growth of a CdS shell affects these two relaxation processes in CdSe/CdS core-shell QDs. Using a combination of ultrafast pump-push-probe spectroscopy on the QD ensemble and analysis of the photon statistics from single QDs, we find that Auger losses in the biexciton state are suppressed with increasing shell thickness, while hot-electron cooling remains unaffected. Calculations conducted within an eight-band k·p model confirm the experimental dependence of the biexciton Auger decay on the shell thickness, and provide insights into the factors determining the cooling rate of hot carriers. PMID:26389562

  12. Photonically Engineered Incandescent Emitter

    DOEpatents

    Gee, James M.; Lin, Shawn-Yu; Fleming, James G.; Moreno, James B.

    2005-03-22

    A photonically engineered incandescence is disclosed. The emitter materials and photonic crystal structure can be chosen to modify or suppress thermal radiation above a cutoff wavelength, causing the emitter to selectively emit in the visible and near-infrared portions of the spectrum. An efficient incandescent lamp is enabled thereby. A method for fabricating a three-dimensional photonic crystal of a structural material, suitable for the incandescent emitter, is also disclosed.

  13. Photonically engineered incandescent emitter

    DOEpatents

    Gee, James M.; Lin, Shawn-Yu; Fleming, James G.; Moreno, James B.

    2003-08-26

    A photonically engineered incandescence is disclosed. The emitter materials and photonic crystal structure can be chosen to modify or suppress thermal radiation above a cutoff wavelength, causing the emitter to selectively emit in the visible and near-infrared portions of the spectrum. An efficient incandescent lamp is enabled thereby. A method for fabricating a three-dimensional photonic crystal of a structural material, suitable for the incandescent emitter, is also disclosed.

  14. The Quantum Efficiency and Thermal Emittance of Metal Photocathodes

    SciTech Connect

    Dowell, David H.; Schmerge, John F.; /SLAC

    2009-03-04

    Modern electron beams have demonstrated the brilliance needed to drive free electron lasers at x-ray wavelengths, with the principle improvements occurring since the invention of the photocathode gun. The state-of-the-art normalized emittance electron beams are now becoming limited by the thermal emittance of the cathode. In both DC and RF photocathode guns, details of the cathode emission physics strongly influence the quantum efficiency and the thermal emittance. Therefore improving cathode performance is essential to increasing the brightness of beams. It is especially important to understand the fundamentals of cathode quantum efficiency and thermal emittance. This paper investigates the relationship between the quantum efficiency and the thermal emittance of metal cathodes using the Fermi-Dirac model for the electron distribution. We derive the thermal emittance and its relationship to the quantum efficiency, and compare our results to those of others.

  15. Thermal emittance from ionization-induced trapping in plasma accelerators

    NASA Astrophysics Data System (ADS)

    Schroeder, C. B.; Vay, J.-L.; Esarey, E.; Bulanov, S. S.; Benedetti, C.; Yu, L.-L.; Chen, M.; Geddes, C. G. R.; Leemans, W. P.

    2014-10-01

    The minimum obtainable transverse emittance (thermal emittance) of electron beams generated and trapped in plasma-based accelerators using laser ionization injection is examined. The initial transverse phase space distribution following ionization and passage through the laser is derived, and expressions for the normalized transverse beam emittance, both along and orthogonal to the laser polarization, are presented. Results are compared to particle-in-cell simulations. Ultralow emittance beams can be generated using laser ionization injection into plasma accelerators, and examples are presented showing normalized emittances on the order of tens of nm.

  16. Study of the Auger line shape of polyethylene and diamond

    NASA Technical Reports Server (NTRS)

    Dayan, M.; Pepper, S. V.

    1984-01-01

    The KVV Auger electron line shapes of carbon in polyethylene and diamond have been studied. The spectra were obtained in derivative form by electron beam excitation. They were treated by background subtraction, integration and deconvolution to produce the intrinsic Auger line shape. Electron energy loss spectra provided the response function in the deconvolution procedure. The line shape from polyethylene is compared with spectra from linear alkanes and with a previous spectrum of Kelber et al. Both spectra are compared with the self-convolution of their full valence band densities of states and of their p-projected densities. The experimental spectra could not be understood in terms of existing theories. This is so even when correlation effects are qualitatively taken into account account to the theories of Cini and Sawatzky and Lenselink.

  17. Suppression of auger recombination in ""giant"" core/shell nanocrystals

    SciTech Connect

    Garcia Santamaria, Florencio; Vela, Javier; Schaller, Richard D; Hollingsworth, Jennifer A; Klimov, Victor I; Chen, Yongfen

    2009-01-01

    Many potential applications of semiconductor nanocrystals are hindered by nonradiative Auger recombination wherein the electron-hole (exciton) recombination energy is transferred to a third charge carrier. This process severely limits the lifetime and bandwidth of optical gain, leads to large nonradiative losses in light emitting diodes and photovoltaic cells, and is believed to be responsible for intermittency ('blinking') of emission from single nanocrystals. The development of nanostructures in which Auger recombination is suppressed has been a longstanding goal in colloidal nanocrystal research. Here, we demonstrate that such suppression is possible using so-called 'giant' nanocrystals that consist of a small CdSe core and a thick CdS shell. These nanostructures exhibit a very long biexciton lifetime ({approx}10 ns) that is likely dominated by radiative decay instead of non-radiative Auger recombination. As a result of suppressed Auger recombination, even high-order multiexcitons exhibit high emission efficiencies, which allows us to demonstrate optical amplification with an extraordinarily large bandwidth (>500 me V) and record low excitation thresholds.

  18. X-ray excited Auger transitions of Pu compounds

    SciTech Connect

    Nelson, Art J. Grant, William K.; Stanford, Jeff A.; Siekhaus, Wigbert J.; Allen, Patrick G.; McLean, William

    2015-05-15

    X-ray excited Pu core–valence–valence and core–core–valence Auger line-shapes were used in combination with the Pu 4f photoelectron peaks to characterize differences in the oxidation state and local electronic structure for Pu compounds. The evolution of the Pu 4f core-level chemical shift as a function of sputtering depth profiling and hydrogen exposure at ambient temperature was quantified. The combination of the core–valence–valence Auger peak energies with the associated chemical shift of the Pu 4f photoelectron line defines the Auger parameter and results in a reliable method for definitively determining oxidation states independent of binding energy calibration. Results show that PuO{sub 2}, Pu{sub 2}O{sub 3}, PuH{sub 2.7}, and Pu have definitive Auger line-shapes. These data were used to produce a chemical state (Wagner) plot for select plutonium oxides. This Wagner plot allowed us to distinguish between the trivalent hydride and the trivalent oxide, which cannot be differentiated by the Pu 4f binding energy alone.

  19. Emittance growth from radiation fluctuations

    SciTech Connect

    Sands, M.

    1985-12-01

    As an electron bunch travels through a transport system, fluctuations in the energy loss of individual electrons cause the size of the bunch to grow. A calculation is given of the quantum-induced growth of the emittance of a beam in one transverse coordinate, making the following approximations: (1) that the transport system is linear; (2) that there is no coupling between the two transverse motions; and (3) that the radiation effects can be described by their values on the central design trajectory. This last assumption means that systems are considered in which the quantum effects from bending magnets are much larger than from the focusing lenses.

  20. Hydrogen slush production with a large auger

    NASA Technical Reports Server (NTRS)

    Daney, D. E.; Arp, V. D.; Voth, R. O.

    1990-01-01

    The design and construction of a 178-mm-diameter auger-type hydrogen slush generator are described. A supercritical helium flow loop, which simulates the performance of a helium refrigerator, cools the generator. The coolant temperature varies down to 5 K and the flow varies about the 1.4 L/s (3 cfm) design point. The computer model of the auger-type generator shows that coolant temperature and auger speed have the greatest influence on slush production rate, although coolant flow rate and auger radial clearance are also important.

  1. Vertical-Screw-Auger Conveyer Feeder

    NASA Technical Reports Server (NTRS)

    Walton, Otis (Inventor); Vollmer, Hubert J. (Inventor)

    2016-01-01

    A conical feeder is attached to a vertically conveying screw auger. The feeder is equipped with scoops and rotated from the surface to force-feed regolith the auger. Additional scoops are possible by adding a cylindrical section above the conical funnel section. Such then allows the unit to collect material from swaths larger in diameter than the enclosing casing pipe of the screw auger. A third element includes a flexible screw auger. All three can be used in combination in microgravity and zero atmosphere environments to drill and recover a wide area of subsurface regolith and entrained volatiles through a single access point on the surface.

  2. Sequential double Auger decay in atoms: A quantum informatic analysis

    NASA Astrophysics Data System (ADS)

    Parida, S.; Chandra, N.

    2009-05-01

    We theoretically show that the process of inner-shell photoionization in an atom A, followed by the spontaneous sequential emission of two Auger electrons, produces various kinds of spin-entangled states of three flying electronic qubits. All properties of these states are completely pre-determined by the total spin quantum numbers of the electronic states of four atomic species (i.e., A, A, A, A) participating in this process in the Russell-Saunders coupling. These tripartite states are readily characterized experimentally by measuring only energies of the three emitted electrons, without requiring any entanglement witness or other such protocols.

  3. Portable emittance measurement device

    SciTech Connect

    Liakin, D.; Seleznev, D.; Orlov, A.; Kuibeda, R.; Kropachev, G.; Kulevoy, T.; Yakushin, P.

    2010-02-15

    In Institute for Theoretical and Experimental Physics (ITEP) the portable emittance measurements device is developed. It provides emittance measurements both with ''pepper-pot'' and ''two slits'' methods. Depending on the method of measurements, either slits or pepper-pot mask with scintillator are mounted on the two activators and are installed in two standard Balzer's cross chamber with CF-100 flanges. To match the angle resolution for measured beam, the length of the stainless steel pipe between two crosses changes is adjusted. The description of the device and results of emittance measurements at the ITEP ion source test bench are presented.

  4. The emittance concept

    NASA Astrophysics Data System (ADS)

    Lawson, J. D.

    1992-04-01

    An informal descriptive account is first given of the emittance concept and its underlying physical basis. This is followed by a discussion of the connection between emittance and entropy, and a number of questions relating to problems of current interest concerning such topics as emittance growth and equipartition between different degrees of freedom are raised. Although no new results are obtained, it is hoped that the discussion may be helpful in the search for new insights. The paper differs from that presented at the conference, and contains ideas which arose in discussion with T. P. Wangler at Los Alamos after the conference.

  5. Resonant Auger Effect at High X-Ray Intensity

    SciTech Connect

    Rohringer, N; Santra, R

    2008-03-27

    The resonant Auger effect of atomic neon exposed to high-intensity x-ray radiation in resonance with the 1s {yields} 3p transition is discussed. High intensity here means that the x-ray peak intensity is sufficient ({approx} 10{sup 18} W/cm{sup 2}) to induce Rabi oscillations between the neon ground state and the 1s{sup -1}3p ({sup 1}P) state within the relaxation lifetime of the inner-shell vacancy. For the numerical analysis presented, an effective two-level model, including a description of the resonant Auger decay process, is employed. Both coherent and chaotic x-ray pulses are treated. The latter are used to simulate radiation from x-ray free-electron lasers based on the principle of self-amplified spontaneous emission. Observing x-ray-driven atomic population dynamics in the time domain is challenging for chaotic pulse ensembles. A more practical option for experiments using x-ray free-electron lasers is to measure the line profiles in the kinetic energy distribution of the resonant Auger electron. This provides information on both atomic population dynamics and x-ray pulse properties.

  6. Localization effects in the Auger spectra of ring nitrogen systems: Pyridine, poly(2-vinyl)pyridine, borazine, and boron nitride

    SciTech Connect

    Rye, R.R.; Kelber, J.A.; Kellogg, G.E.; Nebesny, K.W.; Lichtenberger, D.L.

    1987-04-15

    The N(KVV) Auger spectra of gas phase pyridine (C/sub 5/H/sub 5/N) and borazine (B/sub 3/N/sub 3/H/sub 6/), and of solid phase poly(2-vinyl)pyridine (PVP) and hexagonal boron nitride ((BN)/sub x/) are reported and analyzed. The data indicate two Auger ''fingerprint'' types of nitrogen. Ammonia (NH/sub 3/) is the prototype for the first, where three of the five valence electrons are sigma bonding and the other two are the lone pair. This localized electronic structure gives rise to relatively sharp features in the N(KVV) spectrum. Typical of the second fingerprint type is pyridine, where there are two sigma bonding electrons, a lone pair of electrons, and one electron contributing to the delocalized ..pi.. system. Theoretical nitrogen Auger transition energies and intensities are calculated for pyridine to demonstrate the general origin of the overlapping features in the relatively broad N(KVV) spectrum of this molecule. PVP fits into the second fingerprint type while borazine and boron nitride give nitrogen Auger spectra more like ammonia. Approximate calculations using the equivalent core concept are used to clarify the relationship between the ammonia, borazine, and boron nitride spectra. It is shown that in these systems the initial Auger state (core--hole) largely localizes the bonds and lone pair on the nitrogen. The Auger spectra show that it is the sigma, ..pi.. and nonbonding orbital characters that provide the Auger fingerprint.

  7. Auger decay and subsequent fragmentation pathways of ethylene following K -shell ionization

    NASA Astrophysics Data System (ADS)

    Gaire, B.; Haxton, D. J.; Sturm, F. P.; Williams, J.; Gatton, A.; Bocharova, I.; Gehrken, N.; Schöffler, M.; Gassert, H.; Zeller, S.; Voigtsberger, J.; Jahnke, T.; Zohrabi, M.; Reedy, D.; Nook, C.; Landers, A. L.; Belkacem, A.; Cocke, C. L.; Ben-Itzhak, I.; Dörner, R.; Weber, Th.

    2015-07-01

    The fragmentation pathways and dynamics of ethylene molecules after core ionization are explored using coincident measurements of the Auger electron and fragment ions by employing the cold target recoil-ion momentum spectroscopy method. The influence of several factors on the dynamics and kinematics of the dissociation is studied. These include propensity rules, ionization mechanisms, symmetry of the orbitals from which the Auger electrons originate, multiple scattering, conical intersections, interference, and possible core-hole localization for the double ionization of this polyatomic molecule. Energy correlation maps allow probing the multidimensional potential energy surfaces and, in combination with our multiconfiguration self-consistent field calculations, identifying the populated electronic states of the dissociating dication. The measured angular distributions of the Auger electrons in the molecular frame further support and augment these assignments. The deprotonation and molecular hydrogen ion elimination channels show a nearly isotropic Auger electron angular distribution with a small elongation along the direction perpendicular to the molecular axis. For the symmetric breakup the angular distributions show a clear influence of multiple scattering on the outgoing electrons. The lowest kinetic energy release feature of the symmetric breakup channel displays a fingerprint of entangled Auger and photoelectron motion in the angular emission pattern identifying this transition as an excellent candidate to probe core-hole localization at a conical intersection of a polyatomic molecule.

  8. A low-emittance lattice for SPEAR

    NASA Astrophysics Data System (ADS)

    Safranek, J.; Wiedemann, H.

    1992-08-01

    The design and implementation of a low emittance lattice for the SPEAR storage ring including measurements of the performance of the lattice are presented [J. Safranek, Ph.D. thesis, Stanford University, 1991]. The low emittance lattice is designed to optimize the performance of SPEAR as a synchrotron radiation source while keeping SPEAR hardware changes at a minimum. The horizontal emittance of the electron beam in the low emittance lattice is reduced by a factor of 4 from the previous lattice. This reduces the typical horizontal source size and divergence of the photon beams by a factor of 2 each and increases the photon beam brightness. At 3 GeV the horizontal emittance is 129π nm rad, which makes the low emittance lattice the lowest emittance, running synchrotron radiation source in the world in the 1.5 to 4.0 GeV energy range for the emittance scaled to 3 GeV. The measured vertical emittance was reduced to half that typically seen at SPEAR in the past. The brightness of the photon beams was further increased by reducing βy at the insertion devices to 1.1 m and reducing the energy dispersion at the insertion devices by more than a factor of 2 on average. The horizontal dispersion at the rf cavities was reduced by a factor of nearly 4 which gives much less problems with synchrobetatron resonances. The dynamic and physical apertures of the lattice are large, giving long beam lifetimes and easy injection of electrons. The measurements of the linear optics and intensity dependent phenomena gave reasonable agreement with the design. The overall performance of the machine was very good. Injection rates of 10 to 20 mA/min and larger were achieved routinely, and 100 mA total current was stored. Repeated ramping of stored beam from the injection energy of 2.3 GeV to the running energy of 3.0 GeV was achieved with very little beam loss. This low emittance configuration is expected to be the operating configuration for SPEAR starting in January 1992.

  9. Azimuth-dependent Auger neutralization of He{sup +} on Ag(111) and (110) surfaces

    SciTech Connect

    Valdes, Diego; Monreal, R. C.; Blanco, J. M.; Esaulov, V. A.

    2007-04-15

    We present a detailed theoretical analysis of the role played by s and d electrons in Auger neutralization processes of He{sup +} at Ag(111) and Ag(110) surfaces. We calculate crystal-lattice-site Auger neutralization rates as a function of the perpendicular distance between ions and surfaces. We find that the rate is very insensitive to the lateral position for large values of the perpendicular distance because the contribution of the delocalized s electrons dominates in this case. In contrast, the contribution of d electrons dominates at short perpendicular distances and the strong spatial localization of these electrons causes a similar strong dependence of the Auger rate with lateral position. We perform molecular dynamic simulations of scattered ion trajectories, which, used together with the Auger neutralization rates, allow us to obtain the theoretical ion fraction that we compare with our measurements. This parameter-free theory is able to reproduce the magnitude of the ion survival probability and its dependence with the azimuthal angle of incidence for both surfaces of Ag, thus showing the important role played by localized electrons in Auger neutralization of He.

  10. Analysis of Slice Transverse Emittance Evolution ina Photocathode RF Gun

    SciTech Connect

    Huang, Z.; Ding, Y.; Qiang, J.; /LBL, Berkeley

    2007-10-17

    The slice transverse emittance of an electron beam is of critical significance for an x-ray FEL. In a photocathode RF gun, the slice transverse emittance is not only determined by the emission process, but also influenced strongly by the non-linear space charge effect. In this paper, we study the slice transverse emittance evolution in a photocathode RF gun using a simple model that includes effects of RF acceleration, focusing, and space charge force. The results are compared with IMPACT-T space charge simulations and may be used to understand the development of the slice emittance in an RF gun.

  11. Auger recombination in long-wave infrared InAs/InAsSb type-II superlattices

    SciTech Connect

    Olson, B. V.; Grein, C. H.; Kim, J. K.; Kadlec, E. A.; Klem, J. F.; Hawkins, S. D.; Shaner, E. A.

    2015-12-29

    The Auger lifetime is a critical intrinsic parameter for infrared photodetectors as it determines the longest potential minority carrier lifetime and consequently the fundamental limitations to their performance. Here, Auger recombination is characterized in a long-wave infrared InAs/InAsSb type-II superlattice. Auger coefficients as small as 7.1×10–26 cm6/s are experimentally measured using carrier lifetime data at temperatures in the range of 20 K–80 K. The data are compared to Auger-1 coefficients predicted using a 14-band K•p electronic structure model and to coefficients calculated for HgCdTe of the same bandgap. In conclusion, the experimental superlattice Auger coefficients are found to be an order-of-magnitude smaller than HgCdTe.

  12. Auger recombination in long-wave infrared InAs/InAsSb type-II superlattices

    DOE PAGESBeta

    Olson, B. V.; Grein, C. H.; Kim, J. K.; Kadlec, E. A.; Klem, J. F.; Hawkins, S. D.; Shaner, E. A.

    2015-12-29

    The Auger lifetime is a critical intrinsic parameter for infrared photodetectors as it determines the longest potential minority carrier lifetime and consequently the fundamental limitations to their performance. Here, Auger recombination is characterized in a long-wave infrared InAs/InAsSb type-II superlattice. Auger coefficients as small as 7.1×10–26 cm6/s are experimentally measured using carrier lifetime data at temperatures in the range of 20 K–80 K. The data are compared to Auger-1 coefficients predicted using a 14-band K•p electronic structure model and to coefficients calculated for HgCdTe of the same bandgap. In conclusion, the experimental superlattice Auger coefficients are found to be anmore » order-of-magnitude smaller than HgCdTe.« less

  13. Rare Earth Doped Yttrium Aluminum Garnet (YAG) Selective Emitters

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.; Pal, AnnaMarie T.; Patton, Martin O.; Jenkins, Phillip P.

    1999-01-01

    As a result of their electron structure, rare earth ions in crystals at high temperature emit radiation in several narrow bands rather than in a continuous blackbody manner. This study presents a spectral emittance model for films and cylinders of rare earth doped yttrium aluminum garnets. Good agreement between experimental and theoretical film spectral emittances was found for erbium and holmium aluminum garnets. Spectral emittances of films are sensitive to temperature differences across the film. For operating conditions of interest, the film emitter experiences a linear temperature variation whereas the cylinder emitter has a more advantageous uniform temperature. Emitter efficiency is also a sensitive function of temperature. For holminum aluminum garnet film the efficiency is 0.35 at 1446K but only 0.27 at 1270 K.

  14. Thermionic scanner pinpoints work function of emitter surfaces

    NASA Technical Reports Server (NTRS)

    Rasor, N. S.

    1966-01-01

    In the electron tube testing, a thermionic scanner makes accurate spatial resolution measurements of the metallic surface work functions of emitters. The scanner determines the emitter function and its local departures from the mean value on a point-by-point basis for display on an oscilloscope.

  15. A theoretical study on tuning the electronic structures and photophysical properties of newly designed platinum(II) complexes by adding substituents on functionalized ligands as highly efficient OLED emitters.

    PubMed

    Zhang, Luqiong; Tian, Li; Li, Ming; He, Rongxing; Shen, Wei

    2014-05-01

    By imitating FIrpic, seven new platinum(II) complexes with pic (pic = picolinate) ligand have been designed to be guest materials by means of adding different substituents to functionalized ligands (ppy and fpy, ppy = phenylpyridyl-N,C and fpy = 2-(9',9'-diethyl-9H-fluorenyl)pyridyl-N,C). In order to reveal their molecular structures, photophysical properties and structure-property relationships with typical host materials, an in-depth theoretical investigation was performed via quantum chemical calculations. The electronic structures and photophysical properties of these complexes were investigated by density functional theory (DFT) and time-dependent density functional theory (TDDFT) using the B3LYP functional with LANL2DZ and 6-31G* basis sets. It turns out that electronic structures and photophysical properties can be tuned by substituent modifications on functionalized ligands. This work highlights that the match between guest materials and host materials in typical OLED structures can be weighed by the energy levels of the HOMO and LUMO and the adiabatic triplet energy of each complex. Also, a combined analysis of electronic structures, host-guest match, reorganization energies (λ) and triplet exciton generation fraction (χ(T)) is helpful in exploring triplet emitters with high phosphorescence efficiency in OLEDs, which is an interesting and creative aspect of this work. Thereinto, λ reveals the capability of carrier transport and the balance between holes and electrons, whilst structural parameters and d-orbital splittings show that those complexes that have strong electron-withdrawing and electron-donating groups are nonemissive. Consequently, complexes 3-7 can be better triplet emitters than FIrpic. Moreover, the emission colors could be predicted by the 0-0 transition energy (E(0-0)) instead of the triplet vertical transition energy (E(vert)). Accordingly, complexes 3, 4 and 6 would be efficient phosphorescent materials with different predicted

  16. Cancer from internal emitters

    SciTech Connect

    Boecker, B.B.; Griffith, W.C. Jr.

    1995-10-01

    Irradiation from internal emitters, or internally deposited radionuclides, is an important component of radiation exposures encountered in the workplace, home, or general environment. Long-term studies of human populations exposed to various internal emitters by different routes of exposure are producing critical information for the protection of workers and members of the general public. The purpose of this report is to examine recent developments and discuss their potential importance for understanding lifetime cancer risks from internal emitters. The major populations of persons being studied for lifetime health effects from internally deposited radionuclides are well known: Lung cancer in underground miners who inhaled Rn progeny, liver cancer from persons injected with the Th-containing radiographic contrast medium Thorotrast, bone cancer from occupational or medical intakes of {sup 226}Ra or medical injections of {sup 224}Ra, and thyroid cancer from exposures to iodine radionuclides in the environment or for medical purposes.

  17. 30 CFR 77.1500 - Auger mining; planning.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Auger mining; planning. 77.1500 Section 77.1500... MANDATORY SAFETY STANDARDS, SURFACE COAL MINES AND SURFACE WORK AREAS OF UNDERGROUND COAL MINES Auger Mining § 77.1500 Auger mining; planning. Auger mining shall be planned and conducted by the operator to...

  18. 30 CFR 77.1500 - Auger mining; planning.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Auger mining; planning. 77.1500 Section 77.1500... MANDATORY SAFETY STANDARDS, SURFACE COAL MINES AND SURFACE WORK AREAS OF UNDERGROUND COAL MINES Auger Mining § 77.1500 Auger mining; planning. Auger mining shall be planned and conducted by the operator to...

  19. 30 CFR 77.1500 - Auger mining; planning.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Auger mining; planning. 77.1500 Section 77.1500... MANDATORY SAFETY STANDARDS, SURFACE COAL MINES AND SURFACE WORK AREAS OF UNDERGROUND COAL MINES Auger Mining § 77.1500 Auger mining; planning. Auger mining shall be planned and conducted by the operator to...

  20. 30 CFR 56.7005 - Augers and drill stems.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Augers and drill stems. 56.7005 Section 56.7005... Piercing Drilling § 56.7005 Augers and drill stems. Drill crews and others shall stay clear of augers or drill stems that are in motion. Persons shall not pass under or step over a moving stem or auger....

  1. 30 CFR 56.7005 - Augers and drill stems.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Augers and drill stems. 56.7005 Section 56.7005... Piercing Drilling § 56.7005 Augers and drill stems. Drill crews and others shall stay clear of augers or drill stems that are in motion. Persons shall not pass under or step over a moving stem or auger....

  2. 30 CFR 56.7005 - Augers and drill stems.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Augers and drill stems. 56.7005 Section 56.7005... Piercing Drilling § 56.7005 Augers and drill stems. Drill crews and others shall stay clear of augers or drill stems that are in motion. Persons shall not pass under or step over a moving stem or auger....

  3. 30 CFR 56.7005 - Augers and drill stems.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Augers and drill stems. 56.7005 Section 56.7005... Piercing Drilling § 56.7005 Augers and drill stems. Drill crews and others shall stay clear of augers or drill stems that are in motion. Persons shall not pass under or step over a moving stem or auger....

  4. 30 CFR 56.7005 - Augers and drill stems.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Augers and drill stems. 56.7005 Section 56.7005... Piercing Drilling § 56.7005 Augers and drill stems. Drill crews and others shall stay clear of augers or drill stems that are in motion. Persons shall not pass under or step over a moving stem or auger....

  5. Universal size dependence of auger constants in direct- and indirect-gap semiconductor nanocrystals

    SciTech Connect

    Robel, Istvan; Schaller, Richard D; Klimov, Victor I; Gresback, Ryan; Kortshagen, Uwe

    2008-01-01

    Three-dimensional (3D) spatial confinement of electronic wave functions in semiconductor nanocrystals (NCs) results in a significant enhancement of multi-electron phenomena including non radiative Auger recombination. In this process, a conduction-band electron recombines with a valence-band hole by transferring the recombination energy to a third carrier. Significant interest in Auger recombination in NCs has been stimulated by recent studies ofNC lasing, and generation-III photovoltaics enabled by carrier multiplication because in both of these prospective applications Auger recombination represents a dominant carrier-loss mechanism. Here, we perform a side-by-side comparison of Auger recombination rates in NCs of several different compositions including Ge, PbSe, InAs, and CdSe. We observe that the only factor, which has a significant effect on the measured recombination rates, is the size of the NCs but not the details of the material's electronic structure. Most surprisingly, comparable rates are measured for nanocrystals of directand indirect-gap semiconductor NCs despite a dramatic four-to-five orders of magnitude difference in respective bulk-semiconductor Auger constants. This unusual observation can be explained by confinement-induced relaxation of momentum conservation, which smears out the difference between direct- and indirect-gap materials.

  6. Thermal limit to the intrinsic emittance from metal photocathodes

    SciTech Connect

    Feng, Jun Nasiatka, J.; Wan, Weishi; Karkare, Siddharth; Padmore, Howard A.; Smedley, John

    2015-09-28

    Measurements of the intrinsic emittance and transverse momentum distributions obtained from a metal (antimony thin film) photocathode near and below the photoemission threshold are presented. Measurements show that the intrinsic emittance is limited by the lattice temperature of the cathode as the incident photon energy approaches the photoemission threshold. A theoretical model to calculate the transverse momentum distributions near this photoemission threshold is presented. An excellent match between the experimental measurements and the theoretical calculations is demonstrated. These measurements are relevant to low emittance electron sources for Free Electron Lasers and Ultrafast Electron Diffraction experiments.

  7. Observation of Picometer Vertical Emittance with a Vertical Undulator

    NASA Astrophysics Data System (ADS)

    Wootton, K. P.; Boland, M. J.; Dowd, R.; Tan, Y.-R. E.; Cowie, B. C. C.; Papaphilippou, Y.; Taylor, G. N.; Rassool, R. P.

    2012-11-01

    Using a vertical undulator, picometer vertical electron beam emittances have been observed at the Australian Synchrotron storage ring. An APPLE-II type undulator was phased to produce a horizontal magnetic field, which creates a synchrotron radiation field that is very sensitive to the vertical electron beam emittance. The measured ratios of undulator spectral peak heights are evaluated by fitting to simulations of the apparatus. With this apparatus immediately available at most existing electron and positron storage rings, we find this to be an appropriate and novel vertical emittance diagnostic.

  8. RFI emitter location techniques

    NASA Technical Reports Server (NTRS)

    Rao, B. L. J.

    1973-01-01

    The possibility is discussed of using Doppler techniques for determining the location of ground based emitters causing radio frequency interference with low orbiting satellites. An error analysis indicates that it is possible to find the emitter location within an error range of 2 n.mi. The parameters which determine the required satellite receiver characteristic are discussed briefly along with the non-real time signal processing which may by used in obtaining the Doppler curve. Finally, the required characteristics of the satellite antenna are analyzed.

  9. Heterostructures and infrared emitters with compressed InAsSb layers

    SciTech Connect

    Kurtz, S.R.; Biefeld, R.M.

    1995-03-01

    An overview is presented of strained InAsSb heterostructures and infrared emitters. InAsSb/InGaAs strained-layer superlattices (SLS) and InAsSb quantum wells were characterized using magneto-photoluminescence and compared with unstrained InAsSb and InAs alloys. In heterostructures with biaxially compressed InAsSb, large quantum confinement energies were observed, and the holes exhibited a decrease in effective mass, approaching that of the electrons. This study demonstrates that the electrons and holes in the InAsSb heterostructures are confined in the InAsSb layers, and the band offsets are type I. A large increase in the Auger-1 threshold energy should accompany the strain-induced change in valence-band symmetry of the InAsSb layers. Correspondingly, the InAsSb heterostructures display high radiative efficiencies and increased activation energies for nonradiative recombination compared with the unstrained alloys. LEDs and L-mrs with InAsSb heterostructure active regions are described. InAsSb/InGaAs SLS LEDs operating at 300K at wavelengths {le} 5 pm have been demonstrated. Optically pumped InAsSb/InGaAs SLS lasers, with InPSb cladding, had a maximum operating temperature of 100K.

  10. Automated emittance measurements in the SLC

    SciTech Connect

    Ross, M.C.; Phinney, N.; Quickfall, G.; Shoaee, H.; Sheppard, J.C.

    1987-03-01

    The emittance of the SLC beam is determined from measurements of the beam width on a profile monitor as a quadrupole field is varied. An automated system has been developed to allow this to be done rapidly and accurately. The image on a fluorescent screen profile monitor (resolution about 20 ..mu..m) is read out through an electronic interface and digitized by a transient recorder. A high level software package has been developed to set up the hardware for the measurements, acquire data, fit the beam width, and calculate the emittance.

  11. Head erosion with emittance growth in PWFA

    SciTech Connect

    Li, S. Z.; Adli, E.; England, R. J.; Frederico, J.; Gessner, S. J.; Hogan, M. J.; Litos, M. D.; Walz, D. R.; Muggli, P.; An, W.; Clayton, C. E.; Joshi, C.; Lu, W.; Marsh, K. A.; Mori, W.; Vafaei, N.

    2012-12-21

    Head erosion is one of the limiting factors in plasma wakefield acceleration (PWFA). We present a study of head erosion with emittance growth in field-ionized plasma from the PWFA experiments performed at the FACET user facility at SLAC. At FACET, a 20.3 GeV bunch with 1.8 Multiplication-Sign 10{sup 10} electrons is optimized in beam transverse size and combined with a high density lithium plasma for beam-driven plasma wakefield acceleration experiments. A target foil is inserted upstream of the plasma source to increase the bunch emittance through multiple scattering. Its effect on beamplasma interaction is observed with an energy spectrometer after a vertical bend magnet. Results from the first experiments show that increasing the emittance has suppressed vapor field-ionization and plasma wakefields excitation. Plans for the future are presented.

  12. ETAII 6 MEV PEPPERPOT EMITTANCE MEASUREMENT

    SciTech Connect

    Paul, A C; Richardson, R; Weir, J

    2004-10-18

    We measured the beam emittance at the ETAII accelerator using a pepper-pot diagnostic at nominal parameters of 6 MeV and 2000 Amperes. During the coarse of these experiments, a ''new tune'' was introduced which significantly improved the beam quality. The source of a background pedestal was investigated and eliminated. The measured ''new tune'' emittance is {var_epsilon}= 8.05 {plus_minus} 0. 53 cm - mr or a normalized emittance of {var_epsilon}{sub n} = 943 {plus_minus} 63 mm - mr In 1990 the ETAII programmatic emphasis was on free electron lasers and the paramount parameter was whole beam brightness. The published brightness for ETAII after its first major rebuild was J = 1 - 3 x 10{sup 8} A/(m - rad){sup 2} at a current and energy of 1000-1400 Amperes and 2.5 MeV. The average normalized emittance derived from table 2 of that report is 864 mm-mr corresponding to a real emittance of 14.8 cm-mr.

  13. Nonradiative Auger recombination in semiconductor nanocrystals.

    PubMed

    Vaxenburg, Roman; Rodina, Anna; Shabaev, Andrew; Lifshitz, Efrat; Efros, Alexander L

    2015-03-11

    We calculate the rate of nonradiative Auger recombination in negatively charged CdSe nanocrystals (NCs). The rate is nonmonotonic, strongly oscillating with NC size, and sensitive to the NC surface. The oscillations result in nonexponential decay of carriers in NC ensembles. Using a standard single-exponential approximation of the decay dynamics, we determine the apparent size dependence of the Auger rate in an ensemble and derive CdSe surface parameters consistent with the experimental dependence on size. PMID:25693512

  14. Effect of Temperature Gradient on Thick Film Selective Emitter Emittance

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.; Good, Brian S.; Clark, Eric B.; Chen, Zheng

    1997-01-01

    A temperature gradient across a thick (greater than or equal to .1 mm) film selective emitter will produce a significant reduction in the spectral emittance from the no temperature gradient case. Thick film selective emitters of rare earth doped host materials such as yttrium-aluminum-garnet (YAG) are examples where temperature gradient effects are important. In this paper a model is developed for the spectral emittance assuming a linear temperature gradient across the film. Results of the model indicate that temperature gradients will result in reductions the order of 20% or more in the spectral emittance.

  15. Photoelectron recapture and reemission process associated with double Auger decay in Ar

    NASA Astrophysics Data System (ADS)

    Hikosaka, Y.; Mashiko, R.; Odagiri, T.; Adachi, J.; Tanaka, H.; Kosuge, T.; Ito, K.

    2016-06-01

    Multielectron coincidence spectroscopy has been performed for Ar at a photon energy of only 0.2 eV above the 2 p1 /2 threshold. It is revealed that a postcollision interaction induced by double Auger decay leads to photoelectron recapture, followed by reemission of the captured electron, where the recapture of the slow photoelectron forms the A r2 + Rydberg-excited states which subsequently undergo autoionization. The energy correlation of the emitted electrons discloses that both direct and cascade paths in the double Auger decay contribute to the photoelectron recapture.

  16. Nonlocal effects: relevance for the spontaneous emission rates of quantum emitters coupled to plasmonic structures.

    PubMed

    Filter, Robert; Bösel, Christoph; Toscano, Giuseppe; Lederer, Falk; Rockstuhl, Carsten

    2014-11-01

    The spontaneous emission rate of dipole emitters close to plasmonic dimers are theoretically studied within a nonlocal hydrodynamic model. A nonlocal model has to be used since quantum emitters in the immediate environment of a metallic nanoparticle probe its electronic structure. Compared to local calculations, the emission rate is significantly reduced. The influence is mostly pronounced if the emitter is located close to sharp edges. We suggest to use quantum emitters to test nonlocal effects in experimentally feasible configurations. PMID:25361293

  17. CSR-induced emittance growth in achromats: Linear formalism revisited

    NASA Astrophysics Data System (ADS)

    Venturini, M.

    2015-09-01

    We review the R-matrix formalism used to describe Coherent Synchrotron Radiation (CSR)-induced projected emittance growth in electron beam transport lines and establish the connection with a description in terms of the dispersion-invariant function.

  18. Measurement of ultralow vertical emittance using a calibrated vertical undulator

    NASA Astrophysics Data System (ADS)

    Wootton, K. P.; Boland, M. J.; Rassool, R. P.

    2014-11-01

    Very few experimental techniques are useful for the direct observation of ultralow vertical emittance in electron storage rings. In this work, quantitative measurements of ultralow (pm rad) electron beam vertical emittance using a vertical undulator are presented. An undulator radiation model was developed using the measured magnetic field of the APPLE-II type undulator. Using calibrated experimental apparatus, a geometric vertical emittance of ɛy=0.9 ±0.3 pm rad has been observed. These measurements could also inform modeling of the angular distribution of undulator radiation at high harmonics, for proposed diffraction-limited storage ring light sources.

  19. Operations of and Future Plans for the Pierre Auger Observatory

    SciTech Connect

    Abraham, : J.; Abreu, P.; Aglietta, M.; Aguirre, C.; Ahn, E.J.; Allard, D.; Allekotte, I.; Allen, J.; Alvarez-Muniz, J.; Ambrosio, M.; Anchordoqui, L.

    2009-06-01

    These are presentations to be presented at the 31st International Cosmic Ray Conference, in Lodz, Poland during July 2009. It consists of the following presentations: (1) Performance and operation of the Surface Detectors of the Pierre Auger Observatory; (2) Extension of the Pierre Auger Observatory using high-elevation fluorescence telescopes (HEAT); (3) AMIGA - Auger Muons and Infill for the Ground Array of the Pierre Auger Observatory; (4) Radio detection of Cosmic Rays at the southern Auger Observatory; (5) Hardware Developments for the AMIGA enhancement at the Pierre Auger Observatory; (6) A simulation of the fluorescence detectors of the Pierre Auger Observatory using GEANT 4; (7) Education and Public Outreach at the Pierre Auger Observatory; (8) BATATA: A device to characterize the punch-through observed in underground muon detectors and to operate as a prototype for AMIGA; and (9) Progress with the Northern Part of the Pierre Auger Observatory.

  20. The Auger Engineering Radio Array and multi-hybrid cosmic ray detection

    NASA Astrophysics Data System (ADS)

    Holt, E. M.; Pierre Auger Collaboration

    2016-05-01

    The Auger Engineering Radio Array (AERA) aims at the detection of air showers induced by high-energy cosmic rays. As an extension of the Pierre Auger Observatory, it measures complementary information to the particle detectors, fluorescence telescopes and to the muon scintillators of the Auger Muons and Infill for the Ground Array (AMIGA). AERA is sensitive to all fundamental parameters of an extensive air shower such as the arrival direction, energy and depth of shower maximum. Since the radio emission is induced purely by the electromagnetic component of the shower, in combination with the AMIGA muon counters, AERA is perfect for separate measurements of the electrons and muons in the shower, if combined with a muon counting detector like AMIGA. In addition to the depth of the shower maximum, the ratio of the electron and muon number serves as a measure of the primary particle mass.

  1. Nanostructure TEM analysis of diamond cold cathode field emitters

    SciTech Connect

    Wade, Travis S.; Ghosh, Nikkon; Wittig, James Edward; Kang, Weng; Allard Jr, Lawrence Frederick; Unocic, Kinga A; Davidson, James; Tolk, Norman H.

    2012-01-01

    Diamond cold cathode devices have demonstrated significant potential as electron field emitters. Ultra-sharp diamond pyramidal tips (~5nm tip radius) have been fabricated and show improvement in emission when compared to conventional field emitters. However, the emission mechanisms in these complex diamond nanostructures are not well understood. Transmission electron microscopy performed in this study provides new insight into tip structure and composition with implications for field emission and diamond growth.

  2. Auger Recombination in Indium Gallium Nitride: Experimental Evidence

    NASA Astrophysics Data System (ADS)

    Krames, Michael

    2010-03-01

    Progress in InGaN-based light-emitting diode (LED) technology has resulted in white-light emitters with efficiencies far exceeding those of conventional light sources such as tungsten-filament-based incandescence and mercury-vapor based fluorescence. Indeed, by now efficacies exceeding 150 lumens per Watt for InGaN-based phosphor-converted white LEDs are claimed, which represent a 90% energy savings compared to the conventional incandescent (i.e., ``light bulb'') solution. However, these high performance levels are obtained under conditions of very low forward current-density for the InGaN LED and do not represent true operating conditions (nor cost-effective utilization) for the device. In order to reduce the cost (and thus increase market penetration of) solid-state lighting, more lumens per unit of semiconductor area are required which in practice necessitates higher drive current densities. Unfortunately, at these higher driver current densities, the internal quantum efficiency of InGaN-based LEDs is observed to decrease significantly. In the fall of 2007, researchers at the Advanced Laboratories of Philips Lumileds were the first to propose Auger recombination as the root-cause mechanism in InGaN which was behind this ``efficiency droop'' [1]. They further proposed to circumvent the problem by employing InGaN-based active region designs that maintain low carrier density, and demonstrated an LED device design that reaches a maximum quantum efficiency above 200 A/cm2, compared to ˜1-10 A/cm^2 for typical multiple-quantum-well heterostructures [2]. In this talk we will review the experimental evidence for Auger recombination in InGaN, beginning with the early work from 2007 and then considering additional work from more recent efforts to better understand the details behind this loss mechanism. [4pt] [1] Y. C. Shen, G. O. M"uller, S. Watanabe, N. F. Gardner, A. Munkholm, and M. R. Krames, ``Auger recombination in InGaN measured by photoluminescence'', Appl. Phys

  3. Rare Earth Garnet Selective Emitter

    NASA Technical Reports Server (NTRS)

    Lowe, Roland A.; Chubb, Donald L.; Farmer, Serene C.; Good, Brian S.

    1994-01-01

    Thin film Ho-YAG and Er-YAG emitters with a platinum substrate exhibit high spectral emittance in the emission band (epsilon(sub lambda) approx. = 0.75, sup 4)|(sub 15/2) - (sup 4)|(sub 13/2),for Er-YAG and epsilon(sub lambda) approx. = 0.65, (sup 5)|(sub 7) - (sup 5)|(sub 8) for Ho-YAG) at 1500 K. In addition, low out-of-band spectral emittance, epsilon(sub lambda) less than 0.2, suggest these materials would be excellent candidates for high efficiency selective emitters in thermophotovoltaic (TPV) systems operating at moderate temperatures (1200-1500 K). Spectral emittance measurements of the thin films were made (1.2 less than lambda less than 3.0 microns) and compared to the theoretical emittances calculated using measured values of the spectral extinction coefficient. In this paper we present the results for a new class of rare earth ion selective emitters. These emitters are thin sections (less than 1 mm) of yttrium aluminum garnet (YAG) single crystal with a rare earth substitutional impurity. Selective emitters in the near IR are of special interest for thermophotovoltaic (TPV) energy conversion. The most promising solid selective emitters for use in a TPV system are rare earth oxides. Early spectral emittance work on rare earth oxides showed strong emission bands in the infrared (0.9 - 3 microns). However, the emittance outside the emission band was also significant and the efficiency of these emitters was low. Recent improvements in efficiency have been made with emitters fabricated from fine (5 - 10 microns) rare earth oxide fibers similar to the Welsbach mantle used in gas lanterns. However, the rare earth garnet emitters are more rugged than the mantle type emitters. A thin film selective emitter on a low emissivity substrate such as gold, platinum etc., is rugged and easily adapted to a wide variety of thermal sources. The garnet structure and its many subgroups have been successfully used as hosts for rare earth ions, introduced as substitutional

  4. Understanding the Impact of Field-Emitter Characteristics on Electron Beam Focusing in the VAPoR Time-of-Fight Mass Spectrometer

    NASA Technical Reports Server (NTRS)

    Southard, Adrian E.; Getty, Stephanie A.; Costen, Nicholas P.; Hidrobo, Gregory B.; Glavin, Daniel P.

    2013-01-01

    Simulations of field emission of electrons from an electron gun are used to determine the angular distribution of the emitted electron beam and the percentage of charge transmitted through the grid. The simulations are a first step towards understanding the spherical aberration present after focusing the electron beam. The effect of offset of the cathode with respect to the grid and the separation between cathode and grid on the angular distributions of emitted electrons and transmission of the grid are explored.

  5. Enhanced radiative auger emission from lithiumlike20Ca17+

    NASA Astrophysics Data System (ADS)

    Bernstein, E. M.; Clark, M. W.; Tanis, J. A.; Graham, W. G.; Morgan, T. J.; Stöckli, M. P.; Berkner, K. H.; Schlachter, A. S.; Stearns, J. W.

    1991-03-01

    Radiative Auger emission (RAE) from lithiumlike20Ca17+ projectiles excited in collisions with He has been measured. The intensity of RAE photons relative to Kα x-ray emission is enhanced by a factor of 10 17 compared with theoretical calculations for ions with few electron vacancies. The enhancement of RAE for Ca17+ is consistent with the results reported previously for lithiumlike16S13+ and23V20+ and indicates a systematic dependence on Z. Both the enhancement and the relative RAE transition rate increase with Z.

  6. Rutherford backscattering and Auger spectroscopy of mercuric iodide detectors

    NASA Astrophysics Data System (ADS)

    Felter, T. E.; Stulen, R. H.; Schnepple, W. F.; Ortale, C.; van den Berg, L.

    1989-11-01

    Palladium contacts on mercuric iodide have been studied using Rutherford backscattering spectroscopy and Auger electron spectroscopy. Results on actual detector contacts show some intermixing of both mercury and iodine with the palladium. To investigate the role of processing variables as a possible cause of this effect we have fabricated model contacts at low temperatures (T ≈ 100 K) and analyzed in situ. The results demonstrated that significant interdiffusion occurs at temperatures as low as 225 K. We conclude that excessive heating during contact deposition could prove to be detrimental to device performance and that the use of cooled substrates during processing should be explored.

  7. Enhanced radiative Auger emission from lithiumlike 16S13+

    NASA Astrophysics Data System (ADS)

    Bernstein, E. M.; Clark, M. W.; Oglesby, C. S.; Tanis, J. A.; Graham, W. G.; McFarland, R. H.; Morgan, T. J.; Johnson, B. M.; Jones, K. W.

    1990-03-01

    The radiative Auger emission (RAE) from 0.94-6.25-MeV/u 16S13+ (lithiumlike) projectiles excited in collisions with He target atoms has been measured. For these highly stripped ions the intensity of RAE photons relative to Kα x-ray emission is enhanced by about a factor of five compared with theoretical calculations and an earlier experimental measurement for S ions with few electron vacancies. The enhancement of RAE for S13+ is qualitatively similar to results reported previously for lithiumlike 23V20+; however, some differences between S and V are evident.

  8. Nonintercepting emittance monitor

    SciTech Connect

    Miller, R.H.; Clendenin, J.E.; James, M.B.; Sheppard, J.C.

    1983-08-01

    A nonintercepting emittance monitor is a helpful device for measuring and improving particle beams in accelerators and storage rings as it allows continuous monitoring of the beam's distribution in phase space, and perhaps closed loop computer control of the distributions. Stripline position monitors are being investigated for use as nonintercepting emittance monitors for a beam focused by a FODO array in the first 100 meters of our linear accelerator. The technique described here uses the signal from the four stripline probes of a single position monitor to measure the quadrupole mode of the wall current in the beam pipe. This current is a function of the quadrupole moment of the beam, sigma/sup 2//sub x/ - sigma/sup 2//sub y/. In general, six independent measurements of the quadrupole moment are necessary to determine the beam emittance. This technique is dependent on the characteristically large variations of sigma/sup 2//sub x/ - sigma/sup 2//sub y/ in a FODO array. It will not work in a focusing system where the beam is round at each focusing element.

  9. GTF Transverse and Longitudinal Emittance Data Analysis Technique

    SciTech Connect

    Not Available

    2010-12-07

    The SSRL Gun Test Facility (GTF) was built to develop a high brightness electron injector for the LCLS and has been operational since 1996. Measurements at the GTF include quadrupole scan transverse emittance measurements and linac phase scan longitudinal emittance measurements. Typically the beam size is measured on a screen as a function of a quadrupole current or linac phase and the beam matrix is then fit to the measured data. Often the emittance which is the final result of the measurement is the only number reported. However, the method used to reduce the data to the final emittance value can have a significant effect on the result. This paper describes in painful detail the methods used to analyze the transverse and longitudinal emittance data collected at the GTF.

  10. Low-emittance tuning at CesrTA

    NASA Astrophysics Data System (ADS)

    Shanks, James

    The International Linear Collider (ILC) is a proposed 500GeV center-of-mass electron/positron collider. In order to meet luminosity requirements, low-emittance beams must be provided at the start of the two 15-km main linacs. These low-emittance beams will be provided by damping rings, whose optics must be well-corrected in order to minimize dilution of the vertical emittance. In 2008 the Cornell Electron/Positron Storage Ring (CESR)was reconfigured from an electron/positron collider to the CESR Test Accelerator (CesrTA), to serve as a testbed for the ILC damping rings. One of the primary research objectives of the CesrTA project is to explore beam-based optics correction techniques for application at the ILC damping rings. The geometric vertical emittance target for CesrTA is < 10 pm at 2.085 GeV. This dissertation discusses the tuning methods used at CesrTA to achieve low-emittance conditions. Simulationsmodeling the effects ofmagnetmisalignments, systematic and random multipoles, BPM errors, and emittance correction algorithm have been developed, and suggest the residual vertical emittance measured at the conclusion of the tuning procedure is dominated by sources unaffected by optics correction. The same characterization methods leading to this diagnosis have been applied to the proposed International Linear Collider (ILC) damping rings to evaluate misalignment and multipole tolerances. Dynamic aperture studies for the ILC damping rings are discussed.

  11. Si infrared pixelless photonic emitter

    NASA Astrophysics Data System (ADS)

    Malyutenko, V. K.; Bogatyrenko, V. V.; Malyutenko, O. Y.; Chyrchyk, S. V.

    2005-09-01

    We report on basic principle and technology of Si high-temperature (T>300K) IR emitter based on all optical down conversion concept. The approach is based on the possibility to modulate semiconductor thermal emission power in the spectral range of intra-band electron transitions through shorter wavelength (inter-band transitions) optical pumping (light down conversion process). Device emission bands are matched to transparency windows in atmosphere (3-5 μm and 8-12 μm) by adjusting thin film coat parameters. The carrier lifetime is responsible for the device time response whereas its maximum power emitted (mW-range) activates with temperature increase. One of the major advantages of devices employing optical "read in" technology is that they are free of contacts and junctions, thus making them ideal for operation at high temperatures.

  12. Spin-dependent screening and Auger neutralization of He{sup +} ions in metals

    SciTech Connect

    Alducin, M.; Diez Muino, R.; Juaristi, J.I.

    2004-07-01

    The screening of a He{sup +} ion embedded in a paramagnetic electron gas is studied using density functional theory within the local spin density approximation. We calculate the induced electron density and the induced density of states for each spin orientation, parallel and antiparallel to that of the electron bound to the He{sup +} ion. Our results show that the screening is preferably due to parallel spin electrons, especially for low electron densities of the medium. In a second step, the rates for Auger neutralization of a He{sup +} ion in an electron gas are calculated, paying special attention to their dependence on the spin of the electron excited in the Auger process. The results obtained are used to interpret experiments in which the spin polarization of the emitted yield is measured when a He{sup +} projectile is neutralized in front of a metal surface.

  13. Role of cascade and Auger effects in the enhanced population of the C{sup 3+}(1s2s2p {sup 4}P) states following single-electron capture in C{sup 4+}(1s2s {sup 3}S)-He collisions

    SciTech Connect

    Roehrbein, D.; Kirchner, T.; Fritzsche, S.

    2010-04-15

    The population of excited three-electron states in carbon ions after single-electron capture in 0.5-1.1 MeV/amu C{sup 4+}(1s2s {sup 3}S)-He collisions is analyzed theoretically by combining different methods. While the two-center basis generator method is used to calculate capture amplitudes on the single-particle level, all-electron structure calculations for the relevant C{sup 3+} states and their radiative and Auger transition rates are performed on the multiconfiguration Dirac-Fock level. These data are then combined and fed into a set of classical rate equations for the decay dynamics. Total cross sections for the production of the 1s2s2p {sup 4}P, 1s2s2p {sup 2}P{sub -}, and 1s2s2p {sup 2}P{sub +} states are calculated and their ratios compared with recent experimental data and previous calculations [D. Strohschein et al., Phys. Rev. A 77, 022706 (2008)]. It is found that the relative intensities of the 1s2s2p {sup 4}P states are considerably larger than expected on the basis of pure spin statistics. The Auger transitions, which were not included in the previous calculations, have a significant effect on the final results in that they reduce the 1s2s2p {sup 2}P intensities. Although our extended computations explain a significant part of the production of the 1s2s2p {sup 4}P states, the experimentally observed enhancement of these states is still considerably larger than the theoretical one.

  14. Sharpening of field emitter tips using high-energy ions

    DOEpatents

    Musket, Ronald G.

    1999-11-30

    A process for sharpening arrays of field emitter tips of field emission cathodes, such as found in field-emission, flat-panel video displays. The process uses sputtering by high-energy (more than 30 keV) ions incident along or near the longitudinal axis of the field emitter to sharpen the emitter with a taper from the tip or top of the emitter down to the shank of the emitter. The process is particularly applicable to sharpening tips of emitters having cylindrical or similar (e.g., pyramidal) symmetry. The process will sharpen tips down to radii of less than 12 nm with an included angle of about 20 degrees. Because the ions are incident along or near the longitudinal axis of each emitter, the tips of gated arrays can be sharpened by high-energy ion beams rastered over the arrays using standard ion implantation equipment. While the process is particularly applicable for sharpening of arrays of field emitters in field-emission flat-panel displays, it can be effectively utilized in the fabrication of other vacuum microelectronic devices that rely on field emission of electrons.

  15. Rare earth garnet selective emitter

    SciTech Connect

    Lowe, R.A.; Chubb, D.L.; Farmer, S.C.; Good, B.S.

    1994-09-01

    Thin film Ho-YAG and Er-YAG emitters with a platinum substrate exhibit high spectral emittance in the emission band (epsilon{sub {lambda}}) approximately equal to 0.74, ((4)l{sub 15/2}) - ((4)l{sub 13/2}), for Er-YAG and epsilon{sub {lambda}} approximately equal to 0.65, ((5)l{sub 7})-((5)l{sub 8}) for (Ho-YAG) at excellent candidates for high efficiency selective emitters in the thermophotovoltaics (TPV) systems operating at moderate temperatures (1200-1500K). Spectral emittance measurements of the thin films were made (1.2 less than lambda less than 3.0 microns) and compared to the theoretical emittances calculated using measured values of the spectral extinction coefficient. In this paper the authors present the results for a new class of rare earth ion selective emitters. These emitters are thin sections (less than 1 mm) of yttrium aluminum garnet (YAG) single crystal with a rare earth substitutional impurity. This paper presents normal spectral emittance, epsilon{sub {lambda}} measurements of holmium (Ho), and erbium (Er) doped YAG thin film selective emitters at 1500 K, and compares those results with the theoretical spectral emittance.

  16. Rare earth garnet selective emitter

    NASA Technical Reports Server (NTRS)

    Lowe, Roland A.; Chubb, Donald L.; Farmer, Serene C.; Good, Brian S.

    1994-01-01

    Thin film Ho-YAG and Er-YAG emitters with a platinum substrate exhibit high spectral emittance in the emission band (epsilon(sub lambda) approximately equal to 0.74, ((4)l(sub 15/2)) - ( (4)l(sub13/2)), for Er-YAG and epsilon(sub lambda) approximately equal to 0.65, ((5)l(sub 7))-((5)l(sub 8)) for Ho-YAG) at excellent candidates for high efficiency selective emitters in the thermophotovoltaics (TPV) systems operating at moderate temperatures (1200-1500K). Spectral emittance measurements of the thin films were made (1.2 less than lambda less than 3.0 microns) and compared to the theoretical emittances calculated using measured values of the spectral extinction coefficient. In this paper we present the results for a new class of rare earth ion selective emitters. These emitters are thin sections (less than 1 mm) of yttrium aluminum garnet (YAG) single crystal with a rare earth substitutional impurity. This paper presents normal spectral emittance, epsilon(sub lambda), measurements of holmium (Ho), and erbium (Er) doped YAG thin film selective emitters at 1500 K, and compares those results with the theoretical spectral emittance.

  17. Monolithic multinozzle emitters for nanoelectrospray mass spectrometry

    DOEpatents

    Wang, Daojing; Yang, Peidong; Kim, Woong; Fan, Rong

    2011-09-20

    Novel and significantly simplified procedures for fabrication of fully integrated nanoelectrospray emitters have been described. For nanofabricated monolithic multinozzle emitters (NM.sup.2 emitters), a bottom up approach using silicon nanowires on a silicon sliver is used. For microfabricated monolithic multinozzle emitters (M.sup.3 emitters), a top down approach using MEMS techniques on silicon wafers is used. The emitters have performance comparable to that of commercially-available silica capillary emitters for nanoelectrospray mass spectrometry.

  18. Auger analysis of a fiber/matrix interface in a ceramic matrix composite

    NASA Technical Reports Server (NTRS)

    Honecy, Frank S.; Pepper, Stephen V.

    1988-01-01

    Auger electron spectroscopy (AES) depth profiling was used to characterize the fiber/matrix interface of an SiC fiber, reaction bonded Si3N4 matrix composite. Depth profiles of the as received double coated fiber revealed concentration oscillations which disappeared after annealing the fiber in the environment used to fabricate the composite. After the composite was fractured, the Auger depth profiles showed that failure occurred in neither the Beta-SiC fiber body nor in the Si3N4 matrix but, concurrently, at the fiber coating/matrix interface and within the fiber coating itself.

  19. Auger decay of Ar 2p satellite states studied with a multielectron coincidence method

    NASA Astrophysics Data System (ADS)

    Nakano, M.; Hikosaka, Y.; Lablanquie, P.; Penent, F.; Huttula, S.-M.; Suzuki, I. H.; Soejima, K.; Kouchi, N.; Ito, K.

    2012-04-01

    The Auger decay channels of the Ar 2p satellite states have been investigated using a multielectron coincidence technique, using a magnetic bottle time-of-flight electron spectrometer. For the Ar+(2p-13p-1np) satellite states the 2p hole is filled first, while for the Ar+(2p-13s-14s) satellite states the 3s hole is filled first with leading to Ar2+(2p-13p-1) states, which subsequently undergo an Auger decay leading to the filling of the 2p hole.

  20. Effects of the atomic level shift in the Auger neutralization rates of noble metal surfaces

    PubMed Central

    Monreal, R.C.; Goebl, D.; Primetzhofer, D.; Bauer, P.

    2013-01-01

    In this work we compare characteristics of Auger neutralization of He+ ions at noble metal and free-electron metal surfaces. For noble metals, we find that the position of the energy level of He with respect to the Fermi level has a non-negligible influence on the values of the calculated Auger rates through the evaluation of the surface dielectric susceptibility. We conclude that even though our calculated rates are accurate, further theoretical effort is needed to obtain realistic values of the energy level of He in front of these surfaces. PMID:25843996

  1. Experimental results of a single emittance compensation solenoidal magnet

    SciTech Connect

    Palmer, D.T.; Miller, R.H.; Wang, X.J.; Ben-Zvi, I.; Skaritka, J.

    1997-07-01

    A new iron dominated single emittance compensation solenoidal magnet was designed to be integrated with the BNL/SLAC/UCLA 1.6 cell S-Band Photocathode rf Gun. This emittance compensated photoinjector is now in operation at the Brookhaven Accelerator Test Facility. It has produced a 0.329 {+-} 0.012 pC, {tau}{sub 95%} = 10.9 psec electron bunches with a normalized rms transverse emittance of {epsilon}{sub n,rms} = 1.17 {+-} 0.16 {pi} mm mrad. POISSON field maps were used with PARMELA to optimize the emittance compensation solenoidal magnet design. Magnetic field measurements show that at the cathode plane B{sub z} {le} 10 G for a peak magnetic field of B{sub z,max} = 3 kG. Which is in agreement with POISSON simulation. A single emittance compensation solenoidal magnet will produces an initial angular momentum of the electron bunch that manifests itself in a initial magnetic emittance term that cannot be eliminated. This magnetic emittance {epsilon}{sub n,rms}{sup mag} scales as 0.010 {pi} mm mrad/G as the cathode, which is in agreement with PARMELA simulations. Experimental beam dynamics results are presented that shows relative angular rotation and spot size as a function of cathode magnetic field. These results are compared to theory.

  2. Beam emittance from ARPES for photoinjectors

    NASA Astrophysics Data System (ADS)

    Harkay, Katherine; Spentzouris, Linda; Nemeth, Karoly; Droubay, Timothy; Chambers, Scott; Joly, Alan; Hess, Wayne

    2014-03-01

    A commonly-used beam emittance measurement for photoinjector sources involves accelerating a low-charge beam to a few megavolts in an electron gun, then using a pepper-pot emittance diagnostic to image the transverse charge distribution. The emission distribution at the cathode surface could in principle be deduced through simulations, but cannot be measured directly with this method. In the quest to develop ultra-bright photoinjectors, it would be advantageous to be able to measure the emission distribution directly, and use this as a screening process to characterize different photocathode candidates. Angle-resolved photoemission sepctroscopy (ARPES), used widely in surface science, has been proposed [H. Padmore (private communication)] as a method to measure the photocathode intrinsic emittance. A promising novel photocathode, a thin layer of MgO on Ag was recently fabricated and ARPES measurements were carried out [T.C. Droubay et al., PRL (in press)]. The analysis of these data and resulting emittance will be presented. Implications for its use in simulations and design of future photoinjectors will also be presented. This work was supported by the U.S. DOE Office of Science (DE-AC02-06CH11357) and the National Science Foundation (No. PHY-0969989). The measurements were carried out at the EMSL user facility at PNNL.

  3. Emittance growth from space-charge forces

    SciTech Connect

    Wangler, T.P.

    1991-01-01

    Space-charge-induced emittance growth has become a topic of much recent interest for designing the low-velocity sections of high- intensity, high-brightness accelerators and beam-transport channels. In this paper we review the properties of the space-charge force, and discuss the concepts of matching, space-charge and emittance-dominated beams, and equilibrium beams and their characteristics. This is followed by a survey of some of the work over the past 25 years to identify the mechanisms of this emittance growth in both ion and electron accelerators. We summarize the overall results in terms of four distinct mechanisms whose characteristics we describe. Finally, we show numerical simulation results for the evolution of initial rms-mismatched laminar beams. The examples show that for space-charge dominated beams, the nonlinear space-charge forces produce a highly choatic filamentation pattern, which in projection to the 2-D phase spaces results in a 2-component beam consisting of an inner core and a diffuse outer halo. In the examples we have studied the halo contains only a few percent of the particles, but contributes about half of the emittance growth. 39 refs., 2 figs., 1 tab.

  4. Latest results from the Pierre Auger Observatory

    NASA Astrophysics Data System (ADS)

    Lhenry-Yvon, Isabelle

    2016-07-01

    The Pierre Auger Observatory has been designed to investigate the origin and nature of Ultra High Energy Cosmic Rays (UHECR) with energies from 1017 to 1020 eV. In this paper we will review some of the most recent results obtained from data of the Pierre Auger Observatory, namely the spectrum of cosmic rays, the anisotropies in arrival directions and the studies related to mass composition and to the number of muons measured at the ground. We will also discuss the implication of these results for assembling a consistent description of the composition, origin and propagation of cosmic rays.

  5. Auger anchors produce major cost savings

    SciTech Connect

    Webb, B.C.

    1981-10-01

    To meet specific-gravity standards, a 42-in.-diam, 0.598-in.-wall-thickness pipeline being installed in a glacial area full of potholes, peat swamps, and low-lying sections required 425 lb/ft of anchor hold-down. In spots where the underlying soil had an acceptable shear strength, the crew installed auger anchors (costing only $8/ft of pipeline) instead of the concrete set-on weights (at $80/ft) required in areas where the auger anchors would not hold; the savings amounted to about $380,000/mile of line laid.

  6. Direct Observation of Ultralow Vertical Emittance using a Vertical Undulator

    SciTech Connect

    Wootton, Kent

    2015-09-17

    In recent work, the first quantitative measurements of electron beam vertical emittance using a vertical undulator were presented, with particular emphasis given to ultralow vertical emittances [K. P. Wootton, et al., Phys. Rev. ST Accel. Beams, 17, 112802 (2014)]. Using this apparatus, a geometric vertical emittance of 0.9 #6;± 0.3 pm rad has been observed. A critical analysis is given of measurement approaches that were attempted, with particular emphasis on systematic and statistical uncertainties. The method used is explained, compared to other techniques and the applicability of these results to other scenarios discussed.

  7. 30 CFR 77.1501 - Auger mining; inspections.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Auger mining; inspections. 77.1501 Section 77.1501 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND... Auger Mining § 77.1501 Auger mining; inspections. (a) The face of all highwalls, to a distance of...

  8. 30 CFR 77.1501 - Auger mining; inspections.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Auger mining; inspections. 77.1501 Section 77.1501 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND... Auger Mining § 77.1501 Auger mining; inspections. (a) The face of all highwalls, to a distance of...

  9. 30 CFR 819.17 - Auger mining: Subsidence protection.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 3 2014-07-01 2014-07-01 false Auger mining: Subsidence protection. 819.17 Section 819.17 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE... MINING § 819.17 Auger mining: Subsidence protection. Auger mining shall be conducted in accordance...

  10. 30 CFR 819.17 - Auger mining: Subsidence protection.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 3 2011-07-01 2011-07-01 false Auger mining: Subsidence protection. 819.17 Section 819.17 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE... MINING § 819.17 Auger mining: Subsidence protection. Auger mining shall be conducted in accordance...

  11. 30 CFR 819.17 - Auger mining: Subsidence protection.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 3 2012-07-01 2012-07-01 false Auger mining: Subsidence protection. 819.17 Section 819.17 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE... MINING § 819.17 Auger mining: Subsidence protection. Auger mining shall be conducted in accordance...

  12. 30 CFR 77.1501 - Auger mining; inspections.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Auger mining; inspections. 77.1501 Section 77.1501 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND... Auger Mining § 77.1501 Auger mining; inspections. (a) The face of all highwalls, to a distance of...

  13. 30 CFR 77.1501 - Auger mining; inspections.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Auger mining; inspections. 77.1501 Section 77.1501 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND... Auger Mining § 77.1501 Auger mining; inspections. (a) The face of all highwalls, to a distance of...

  14. 30 CFR 819.19 - Auger mining: Backfilling and grading.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 3 2013-07-01 2013-07-01 false Auger mining: Backfilling and grading. 819.19 Section 819.19 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE... MINING § 819.19 Auger mining: Backfilling and grading. (a) General. Auger mining shall be conducted...

  15. 30 CFR 819.17 - Auger mining: Subsidence protection.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Auger mining: Subsidence protection. 819.17 Section 819.17 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE... MINING § 819.17 Auger mining: Subsidence protection. Auger mining shall be conducted in accordance...

  16. 30 CFR 77.1501 - Auger mining; inspections.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Auger mining; inspections. 77.1501 Section 77.1501 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND... Auger Mining § 77.1501 Auger mining; inspections. (a) The face of all highwalls, to a distance of...

  17. 30 CFR 819.17 - Auger mining: Subsidence protection.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 3 2013-07-01 2013-07-01 false Auger mining: Subsidence protection. 819.17 Section 819.17 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE... MINING § 819.17 Auger mining: Subsidence protection. Auger mining shall be conducted in accordance...

  18. 30 CFR 77.1505 - Auger holes; blocking.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Auger holes; blocking. 77.1505 Section 77.1505 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH... § 77.1505 Auger holes; blocking. Auger holes shall be blocked with highwall spoil or other...

  19. 30 CFR 57.7005 - Augers and drill stems.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Augers and drill stems. 57.7005 Section 57.7005... Jet Piercing Drilling-Surface Only § 57.7005 Augers and drill stems. Drill crews and others shall stay clear of augers or drill stems that are in motion. Persons shall not pass under or step over a...

  20. 30 CFR 819.15 - Auger mining: Hydrologic balance.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Auger mining: Hydrologic balance. 819.15 Section 819.15 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE... MINING § 819.15 Auger mining: Hydrologic balance. (a) Auger mining shall be planned and conducted...

  1. 30 CFR 819.15 - Auger mining: Hydrologic balance.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 3 2011-07-01 2011-07-01 false Auger mining: Hydrologic balance. 819.15... MINING § 819.15 Auger mining: Hydrologic balance. (a) Auger mining shall be planned and conducted to minimize disturbances of the prevailing hydrologic balance in accordance with the requirements of §§...

  2. 30 CFR 819.15 - Auger mining: Hydrologic balance.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 3 2012-07-01 2012-07-01 false Auger mining: Hydrologic balance. 819.15... MINING § 819.15 Auger mining: Hydrologic balance. (a) Auger mining shall be planned and conducted to minimize disturbances of the prevailing hydrologic balance in accordance with the requirements of §§...

  3. 30 CFR 819.15 - Auger mining: Hydrologic balance.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 3 2014-07-01 2014-07-01 false Auger mining: Hydrologic balance. 819.15... MINING § 819.15 Auger mining: Hydrologic balance. (a) Auger mining shall be planned and conducted to minimize disturbances of the prevailing hydrologic balance in accordance with the requirements of §§...

  4. 30 CFR 819.15 - Auger mining: Hydrologic balance.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 3 2013-07-01 2013-07-01 false Auger mining: Hydrologic balance. 819.15... MINING § 819.15 Auger mining: Hydrologic balance. (a) Auger mining shall be planned and conducted to minimize disturbances of the prevailing hydrologic balance in accordance with the requirements of §§...

  5. 30 CFR 57.7005 - Augers and drill stems.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Augers and drill stems. 57.7005 Section 57.7005... Jet Piercing Drilling-Surface Only § 57.7005 Augers and drill stems. Drill crews and others shall stay clear of augers or drill stems that are in motion. Persons shall not pass under or step over a...

  6. 30 CFR 57.7005 - Augers and drill stems.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Augers and drill stems. 57.7005 Section 57.7005... Jet Piercing Drilling-Surface Only § 57.7005 Augers and drill stems. Drill crews and others shall stay clear of augers or drill stems that are in motion. Persons shall not pass under or step over a...

  7. 30 CFR 57.7005 - Augers and drill stems.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Augers and drill stems. 57.7005 Section 57.7005... Jet Piercing Drilling-Surface Only § 57.7005 Augers and drill stems. Drill crews and others shall stay clear of augers or drill stems that are in motion. Persons shall not pass under or step over a...

  8. 30 CFR 57.7005 - Augers and drill stems.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Augers and drill stems. 57.7005 Section 57.7005... Jet Piercing Drilling-Surface Only § 57.7005 Augers and drill stems. Drill crews and others shall stay clear of augers or drill stems that are in motion. Persons shall not pass under or step over a...

  9. 30 CFR 77.1500 - Auger mining; planning.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... MANDATORY SAFETY STANDARDS, SURFACE COAL MINES AND SURFACE WORK AREAS OF UNDERGROUND COAL MINES Auger Mining... against any hazard to underground workings located at or near such auger operations and all auger holes... underground mine; (b) Inundation hazards from surface water entering any active underground mine; (c)...

  10. 30 CFR 77.1500 - Auger mining; planning.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... MANDATORY SAFETY STANDARDS, SURFACE COAL MINES AND SURFACE WORK AREAS OF UNDERGROUND COAL MINES Auger Mining... against any hazard to underground workings located at or near such auger operations and all auger holes... underground mine; (b) Inundation hazards from surface water entering any active underground mine; (c)...

  11. Single-knob beam line for transverse emittance partitioning

    NASA Astrophysics Data System (ADS)

    Xiao, C.; Kester, O. K.; Groening, L.; Leibrock, H.; Maier, M.; Rottländer, P.

    2013-04-01

    Flat beams feature unequal emittances in the horizontal and vertical phase space. Such beams were created successfully in electron machines by applying effective stand-alone solenoid fringe fields in the electron gun. Extension of this method to ion beams was proposed conceptually. The present paper is on the decoupling capabilities of an ion beam emittance transfer line. The proposed beam line provides a single-knob tool to partition the horizontal and vertical rms emittances, while keeping the product of the two emittances constant as well as the transverse rms Twiss parameters (αx,y and βx,y) in both planes. It is shown that this single knob is the solenoid field strength.

  12. Field emission electron source

    SciTech Connect

    Zettl, A.K.; Cohen, M.L.

    2000-05-02

    A novel field emitter material, field emission electron source, and commercially feasible fabrication method is described. The inventive field emission electron source produces reliable electron currents of up to 400 mA/cm{sup 2} at 200 volts. The emitter is robust and the current it produces is not sensitive to variability of vacuum or the distance between the emitter tip and the cathode. The novel emitter has a sharp turn-on near 100 volts.

  13. Field emission electron source

    DOEpatents

    Zettl, Alexander Karlwalter; Cohen, Marvin Lou

    2000-01-01

    A novel field emitter material, field emission electron source, and commercially feasible fabrication method is described. The inventive field emission electron source produces reliable electron currents of up to 400 mA/cm.sup.2 at 200 volts. The emitter is robust and the current it produces is not sensitive to variability of vacuum or the distance between the emitter tip and the cathode. The novel emitter has a sharp turn-on near 100 volts.

  14. Near-ideal emittance exchange at the Fermilab Photoinjector

    SciTech Connect

    Johnson, A.S.; Ruan, J.; Edwards, H.; Lumpkin, A.H.; Santucci, J.; Thurman-Keup, R.; /Fermilab

    2011-03-01

    The A0 Photoinjector at Fermilab is presently home to an emittance exchange (EEX) experiment. The emittance exchange beamline consists of a 3.9 GHz normal conducting deflecting mode cavity flanked by two doglegs. Electron bunches with charges of 250 pC and energy of 14.3 MeV are routinely sent through the exchanger. Here we present results of a 1:1 transverse and longitudinal emittance exchange. The advent of synchrotron radiation light sources and free electron lasers (FEL) has been a boon to a wide range of disciplines, resulting in a constantly increasing demand for brighter sources and better resolution. This demand translates to requirements on the properties of the underlying electron beams which produce the light. In particular, one is driven to find ways to precisely manipulate the phase space volume of the beam to optimize it for the desired application. Motivated by the FEL requirement for a small transverse emittance, Cornacchia and Emma developed a transverse/longitudinal emittance exchange concept using a deflecting mode rf cavity located in the dispersive section of a magnetic chicane. This method however, contained residual couplings between the two dimensions, leading Kim to propose a modified version which removed that coupling and resulted in a complete exchange. In this configuration, the deflecting mode cavity is placed between two magnetic doglegs thereby removing the afore-mentioned coupling term. We have used this beamline with upgraded diagnostics to measure a near-ideal 1:1 emittance exchange.

  15. Proof of principal for staircase auger chip removal theory

    NASA Technical Reports Server (NTRS)

    Barron, Jeffrey B.; Brewer, Steve; Kerns, Kenneth; Moody, Kyle; Rossi, Richard A.

    1987-01-01

    A proof of principal design of the staircase auger theory is provided for lunar drilling. The drill is designed to drill holes 30 meters deep and 0.1 meters in diameter. The action of the auger is 0.01 meter strokes at a varying number of strokes per second. A detailed analysis of the interaction of the auger and particle was done to optimize the parameters of the auger. This optimum design will allow for proper heat removal and reasonable drilling time. The drill bit is designed to scoop the particles into the auger while efficiently cutting through the moon's surface.

  16. Emittance growth in intense beams

    SciTech Connect

    Wangler, T.P.; Mills, R.S.; Crandall, K.R.

    1987-03-01

    Recent progress in the study of high-current, low-emittance, charged-particle beams may have a significant influence in the design of future linear accelerators and beam-transport systems for higher brightness applications. Three space-charge-induced rms-emittance-growth mechanisms are now well established: (1) charge-density redistribution, (2) kinetic-energy exchange toward equipartitioning, and (3) coherent instabilities driven by periodic focusing systems. We report the results from a numerical simulation study of emittance in a high-current radio-frequency quadrupole (RFQ) linear accelerator, and present a new semiempirical equation for the observed emittance growth, which agrees well with the emittance growth predicted from numerical simulation codes.

  17. Highly directional thermal emitter

    DOEpatents

    Ribaudo, Troy; Shaner, Eric A; Davids, Paul; Peters, David W

    2015-03-24

    A highly directional thermal emitter device comprises a two-dimensional periodic array of heavily doped semiconductor structures on a surface of a substrate. The array provides a highly directional thermal emission at a peak wavelength between 3 and 15 microns when the array is heated. For example, highly doped silicon (HDSi) with a plasma frequency in the mid-wave infrared was used to fabricate nearly perfect absorbing two-dimensional gratings structures that function as highly directional thermal radiators. The absorption and emission characteristics of the HDSi devices possessed a high degree of angular dependence for infrared absorption in the 10-12 micron range, while maintaining high reflectivity of solar radiation (.about.64%) at large incidence angles.

  18. Measurement of sub-10 fs Auger processes in monolayer graphene.

    PubMed

    Giovanni, David; Yu, Guannan; Xing, Guichuan; Leek, Meng Lee; Sum, Tze Chien

    2015-08-10

    Despite the concerted efforts to directly probe the electron-electron (e-e) scattering mediated relaxation process in graphene using transient absorption spectroscopy, the initial sub-10 fs photoexcited carrier relaxation dynamics has remained elusive. Herein, we utilize a simple z-scan approach to elucidate this process and discern its mechanisms in CVD grown single layer graphene using femtosecond laser pulses with temporal pulse widths far longer than the relaxation time. We report the first experimental observation of e-e scattering lifetime shortening with increasing fluence, which had been theoretically predicted. Analysis from two-body Coulombic scattering suggests that Auger processes are essential relaxation channels in single layer graphene. Importantly, our straightforward approach on the graphene model system is applicable to the family of emergent layered materials. PMID:26367961

  19. Using television cameras to measure emittance

    SciTech Connect

    Ross, M.

    1984-09-25

    Since the luminosity in a linear collider depends on the horizontal and vertical emittance (epsilon/sub x/, epsilon/sub y/) as 1/..sqrt..(epsilon/sub x/epsilon/sub y/) a possible method for improving the performance would be to decrease one or both of these numbers. Once this has been done in a damping ring for example, great care must be taken to avoid effective emittance growth in the remainder of the collider. Therefore an effort should be made to measure epsilon, (x and y), as accurately as possible, both during machine development and operationally. One technique used for measuring epsilon is to insert a luminescent screen in the path of the beam and measure the size of the spot of light made as the beam passes with a television camera and some associated electronics. This has advantages over sampling type techniques (such as wire scanners) because it provides full pulse to pulse two-dimensional information.

  20. Analysis of submicron defects using an SEM-Auger defect review tool

    SciTech Connect

    Childs, Kenton D.; Watson, David G.; Paul, Dennis F.; Clough, Stephen P.

    1998-11-24

    The challenges associated with analyzing semiconductor defects become greater as the device design rule decreases. According to the SIA National Technology Roadmap for Semiconductors, the current metrology requirement for particle analysis is 90 nm with the need to analyze 75 nm particles by the year 2001. These dimensional requirements are beyond the typical capabilities of current SEM/EDX defect review tools. Auger Electron Spectroscopy is a powerful method for measuring the surface composition of localized regions, and has been identified in the SIA roadmap as a primary technique for particle analysis. The ability of a state-of-the-art Auger defect review tool (DRT) to provide secondary electron and high spatial resolution elemental images is particularly effective in characterizing the often complex structure of semiconductor defects. Examples of Auger analysis from defects found at various process steps, on both unpatterned and patterned whole wafers, are shown. These examples highlight the ability of Auger to analyze both thin and laterally small or complex defects.

  1. Studies of signal waveforms from the water-cherenkov detectors of the Pierre Auger Observatory

    SciTech Connect

    Allison, P.S.; Bui-Duc, H.; Chye, J.; Dagoret-Campagne, S.; Dorofeev, A.; Matthews, J.; Nitz, D.F.; Ranchon, S.; Urban, M.; Veberic, D.; Watson, A.A.; Wileman, C.

    2005-08-01

    The ground array of the Pierre Auger Observatory will consist of 1600 water-Cherenkov detectors. Such detectors give signals which can help differentiate between muons and electrons in extensive air showers. The relative numbers of muons and electrons is sensitive to the type of primary particle which initiated the shower. Results are presented using methods which describe the muon content and related information, such as the time structure of the shower front.

  2. FXR LIA Optimization - Time-resolved OTR Emittance Measurement

    SciTech Connect

    Jacob, J; Ong, M; Wargo, P; LeSage, G

    2005-07-21

    The Flash X-Ray Radiography (FXR) facility at Lawrence Livermore National Laboratory utilizes a high current, long pulse linear induction accelerator to produce high doses of x-ray radiation. Accurate characterization of the transverse beam emittance is required in order to facilitate accelerator modeling and tuning efforts and, ultimately, to optimize the final focus spot size, yielding higher resolution radiographs. In addition to conventional magnet scan, pepper-pot, and multiple screen techniques, optical transition radiation (OTR) has been proven as a useful emittance measurement diagnostic and is particularly well suited to the FXR accelerator. We shall discuss the time-resolved emittance characterization of an induction linac electron beam using OTR, and we will present our experimental apparatus and analysis software. We shall also develop the theoretical background of beam emittance and transition radiation.

  3. Rare Earth Doped High Temperature Ceramic Selective Emitters

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.; Pal, AnnaMarie; Patton, Martin O.; Jenkins, Phillip P.

    1999-01-01

    As a result of their electron structure, rare earth ions in crystals at high temperature emit radiation in several narrow bands rather than in a continuous blackbody manner. This study develops a spectral emittance model for films of rare earth containing materials. Although there are several possible rare earth doped high temperature materials, this study was confined to rare earth aluminum garnets. Good agreement between experimental and theoretical spectral emittances was found for erbium, thulium and erbium-holmium aluminum garnets. Spectral emittances of these films are sensitive to temperature differences across the film. Emitter efficiency is also a sensitive function of temperature. For thulium aluminum garnet the efficiency is 0.38 at 1700 K but only 0.19 at 1262 K.

  4. Field emitter based extractor gauges and residual gas analyzers

    SciTech Connect

    Changkun Dong; G. Rao Myneni

    1999-04-01

    Attempts at using the Spindt-type molybdenum field emitter arrays in the extractor gauges and a residual gas analyzer are presented in this article. The sensitivity of the fuel emitter gauge is as high as 11 Torr{sup -1}. The departure from linearity of the pressure versus ion current measurements did not exceed 10% over the pressure range of 10{sup -10} - 10{sup -6} Torr. Stable sensitivities for nitrogen, helium, and hydrogen were achieved below 10{sup -7} Torr with the field emitter residual gas analyzer. The slightly reduced emission current and sensitivity, after long-term operation, are of concern and need to be addressed. Residual gas spectra indicate that when using field emitters, the electron stimulated desorption ions (O{sup +}, F{sup +}, and Cl{sup +}) are reduced as compared to those made using a hot filament source.

  5. Localization of Narrowband Single Photon Emitters in Nanodiamonds.

    PubMed

    Bray, Kerem; Sandstrom, Russell; Elbadawi, Christopher; Fischer, Martin; Schreck, Matthias; Shimoni, Olga; Lobo, Charlene; Toth, Milos; Aharonovich, Igor

    2016-03-23

    Diamond nanocrystals that host room temperature narrowband single photon emitters are highly sought after for applications in nanophotonics and bioimaging. However, current understanding of the origin of these emitters is extremely limited. In this work, we demonstrate that the narrowband emitters are point defects localized at extended morphological defects in individual nanodiamonds. In particular, we show that nanocrystals with defects such as twin boundaries and secondary nucleation sites exhibit narrowband emission that is absent from pristine individual nanocrystals grown under the same conditions. Critically, we prove that the narrowband emission lines vanish when extended defects are removed deterministically using highly localized electron beam induced etching. Our results enhance the current understanding of single photon emitters in diamond and are directly relevant to fabrication of novel quantum optics devices and sensors. PMID:26937848

  6. Halo Formation And Emittance Growth of Positron Beams in Plasmas

    SciTech Connect

    Muggli, P.; Blue, B.E.; Clayton, C.E.; Decker, F.J.; Hogan, M.J.; Huang, C.; Joshi, C.; Katsouleas, Thomas C.; Lu, W.; Mori, W.B.; O'Connell, C.L.; Siemann, R.H.; Walz, D.; Zhou, M.; /UCLA

    2011-10-25

    An ultrarelativistic 28.5 GeV, 700-{micro}m-long positron bunch is focused near the entrance of a 1.4-m-long plasma with a density n{sub e} between {approx}10{sup 13} and {approx}5 x 10{sup 14} cm{sup -3}. Partial neutralization of the bunch space charge by the mobile plasma electrons results in a reduction in transverse size by a factor of {approx}3 in the high emittance plane of the beam {approx}1 m downstream from the plasma exit. As n{sub e} increases, the formation of a beam halo containing {approx}40% of the total charge is observed, indicating that the plasma focusing force is nonlinear. Numerical simulations confirm these observations. The bunch with an incoming transverse size ratio of {approx}3 and emittance ratio of {approx}5 suffers emittance growth and exits the plasma with approximately equal sizes and emittances.

  7. Ladder-type pentaphenylenes and their polymers: efficient blue-light emitters and electron-accepting materials via a common intermediate.

    PubMed

    Jacob, Josemon; Sax, Stefan; Piok, Thomas; List, Emil J W; Grimsdale, Andrew C; Müllen, Klaus

    2004-06-01

    A new route to ladder-type pentaphenylenes has been developed in which both good hole-accepting p-type and electron-accepting n-type materials can be prepared from a common intermediate. This key intermediate is a pentaphenylene diester 5 obtained in high yield by Suzuki coupling of 2 equiv of fluorene boronates with 2,5-dibromoterephthalate. Addition of aryllithium followed by ring closure with boron trifluoride produced a blue-emitting ladder-type pentaphenylene. Bromination followed by reductive polymerization with nickel(0) gave new high molecular mass polymers, which show efficient blue emission with a very small Stokes shift. These polymers bridge the gap in emission between polyfluorenes and fully ladder-type polyphenylenes. An alternative ring closure of the dibromopentaphenylene diester 14 with acid made a diketone that is a good electron-accepting material, as it displays a reversible two-electron reduction. The reduction onset potential of -0.875 V against Ag/Ag(+) corresponds to a lowest unoccupied molecular orbital (LUMO) energy level of 3.53 eV, comparable to the work function of magnesium, suggesting that this unit could be used to greatly increase the injection of electrons into polymers containing it in a light-emitting diode (LED) or solar cell. A red-emitting material was prepared by Suzuki coupling of the dibromopentaphenylene 10b with a perylene dye, thus offering the prospect of tuning the emission from pentaphenylene materials over the whole visible range by attachment of suitable dyes. Unoptimized single-layer organic LEDs that used 11b showed stable pure-blue emission with brightnesses of over 200 cd/m(2) at 7 V, with moderate efficiencies. PMID:15174868

  8. Emittance and Phase Space Exchange

    SciTech Connect

    Xiang, Dao; Chao, Alex; /SLAC

    2011-08-19

    Alternative chicane-type beam lines are proposed for exact emittance exchange between horizontal phase space (x; x{prime}) and longitudinal phase space (z; {delta}). Methods to achieve exact phase space exchanges, i.e. mapping x to z, x{prime} to {delta}, z to x and {delta} to x{prime} are suggested. Methods to mitigate the thick-lens effect of the transverse cavity on emittance exchange are discussed. Some applications of the phase space exchanger and the feasibility of an emittance exchange experiment with the proposed chicane-type beam line at SLAC are discussed.

  9. Elementary framework for cold field emission from quantum-confined, non-planar emitters

    NASA Astrophysics Data System (ADS)

    Patterson, A. A.; Akinwande, A. I.

    2015-05-01

    For suitably small field emitters, the effects of quantum confinement at the emitter tip may have a significant impact on the emitter performance and total emitted current density (ECD). Since the geometry of a quantum system uniquely determines the magnitude and distribution of its energy levels, a framework for deriving ECD equations from cold field electron emitters of arbitrary geometry and dimensionality is developed. In the interest of obtaining semi-analytical ECD equations, the framework is recast in terms of plane wave solutions to the Schrödinger equation via the use of the Jeffreys-Wentzel-Kramers-Brillouin approximation. To demonstrate the framework's consistency with our previous work and its capabilities in treating emitters with non-planar geometries, ECD equations were derived for the normally unconfined cylindrical nanowire (CNW) and normally confined (NC) CNW emitter geometries. As a function of the emitter radius, the NC CNW emitter ECD profile displayed a strong dependence on the Fermi energy and had an average ECD that exceeded the Fowler-Nordheim equation for typical values of the Fermi energy due to closely spaced, singly degenerate energy levels (excluding electron spin), comparatively large electron supply values, and the lack of a transverse, zero-point energy. Such characteristics suggest that emitters with non-planar geometries may be ideal for emission from both an electron supply and electrostatics perspective.

  10. Elementary framework for cold field emission from quantum-confined, non-planar emitters

    SciTech Connect

    Patterson, A. A. Akinwande, A. I.

    2015-05-07

    For suitably small field emitters, the effects of quantum confinement at the emitter tip may have a significant impact on the emitter performance and total emitted current density (ECD). Since the geometry of a quantum system uniquely determines the magnitude and distribution of its energy levels, a framework for deriving ECD equations from cold field electron emitters of arbitrary geometry and dimensionality is developed. In the interest of obtaining semi-analytical ECD equations, the framework is recast in terms of plane wave solutions to the Schrödinger equation via the use of the Jeffreys-Wentzel-Kramers-Brillouin approximation. To demonstrate the framework's consistency with our previous work and its capabilities in treating emitters with non-planar geometries, ECD equations were derived for the normally unconfined cylindrical nanowire (CNW) and normally confined (NC) CNW emitter geometries. As a function of the emitter radius, the NC CNW emitter ECD profile displayed a strong dependence on the Fermi energy and had an average ECD that exceeded the Fowler-Nordheim equation for typical values of the Fermi energy due to closely spaced, singly degenerate energy levels (excluding electron spin), comparatively large electron supply values, and the lack of a transverse, zero-point energy. Such characteristics suggest that emitters with non-planar geometries may be ideal for emission from both an electron supply and electrostatics perspective.

  11. Recent results from the Pierre Auger Observatory

    SciTech Connect

    Gascón, Alberto; Collaboration: Pierre Auger Collaboration

    2014-07-23

    The Pierre Auger Observatory has been designed to investigate the origin and nature of Ultra High Energy Cosmic Rays (UHECR) using a hybrid detection technique. In this contribution we present some of the most recent results of the observatory, namely the upper-end of the spectrum of cosmic rays, state-of-the-art analyses on mass composition, the measurements of the proton-air cross-section, and the number of muons at ground.

  12. Intersubband Auger recombination and population inversion in quantum-well subbands

    NASA Technical Reports Server (NTRS)

    Borenstain, S.; Katz, J.

    1989-01-01

    The intersubband-Auger-recombination time of electrons under population-inversion conditions in a single quantum well is calculated by taking into account momentum- and energy-conservation rules, and by employing Fermi-Dirac statistics. The screened matrix element of the electron-electron interaction and the overlap integral are calculated for an infinitely deep quantum well. The results are in a good agreement with published experimental data. As a major nonradiative process, the Auger recombination is related to threshold current of infrared lasers based on intersubband transitions in quantum-well structures. The realization of these devices and other limitations to achieving population inversion are discussed. In view of the results, development of these lasers for emission wavelengths corresponding to energies below the LO-phonon energy seems feasible.

  13. Distributed Computing for the Pierre Auger Observatory

    NASA Astrophysics Data System (ADS)

    Chudoba, J.

    2015-12-01

    Pierre Auger Observatory operates the largest system of detectors for ultra-high energy cosmic ray measurements. Comparison of theoretical models of interactions with recorded data requires thousands of computing cores for Monte Carlo simulations. Since 2007 distributed resources connected via EGI grid are successfully used. The first and the second versions of production system based on bash scripts and MySQL database were able to submit jobs to all reliable sites supporting Virtual Organization auger. For many years VO auger belongs to top ten of EGI users based on the total used computing time. Migration of the production system to DIRAC interware started in 2014. Pilot jobs improve efficiency of computing jobs and eliminate problems with small and less reliable sites used for the bulk production. The new system has also possibility to use available resources in clouds. Dirac File Catalog replaced LFC for new files, which are organized in datasets defined via metadata. CVMFS is used for software distribution since 2014. In the presentation we give a comparison of the old and the new production system and report the experience on migrating to the new system.

  14. On the uncertainty of the Auger recombination coefficient extracted from InGaN/GaN light-emitting diode efficiency droop measurements

    SciTech Connect

    Piprek, Joachim; Römer, Friedhard; Witzigmann, Bernd

    2015-03-09

    III-nitride light-emitting diodes (LEDs) suffer from a severe efficiency reduction with increasing injection current (droop). Auger recombination is often seen as primary cause of this droop phenomenon. The corresponding Auger recombination coefficient C is typically obtained from efficiency measurements using mathematical models. However, C coefficients reported for InGaN active layers vary over two orders of magnitude. We here investigate this uncertainty and apply successively more accurate models to the same efficiency measurement, thereby revealing the strong sensitivity of the Auger coefficient to quantum well properties such as electron-hole ratio, electric field, and hot carrier escape.

  15. On the uncertainty of the Auger recombination coefficient extracted from InGaN/GaN light-emitting diode efficiency droop measurements

    NASA Astrophysics Data System (ADS)

    Piprek, Joachim; Römer, Friedhard; Witzigmann, Bernd

    2015-03-01

    III-nitride light-emitting diodes (LEDs) suffer from a severe efficiency reduction with increasing injection current (droop). Auger recombination is often seen as primary cause of this droop phenomenon. The corresponding Auger recombination coefficient C is typically obtained from efficiency measurements using mathematical models. However, C coefficients reported for InGaN active layers vary over two orders of magnitude. We here investigate this uncertainty and apply successively more accurate models to the same efficiency measurement, thereby revealing the strong sensitivity of the Auger coefficient to quantum well properties such as electron-hole ratio, electric field, and hot carrier escape.

  16. Beam emittance measurements in RHIC

    SciTech Connect

    Zelenski,A.; Bazilevsky, A.; Bunce, G.; Gill, R.; Huang, H.; Makdisi, Y.; Morozov, B.; Nemesure, S.; Russo, t.; Steski, D.; Sivertz, M.

    2009-05-04

    The RHIC proton polarimeters can operate in scanning mode, giving polarization profiles and transverse beam intensity profile (beam emittance) measurements. The polarimeters function as wire scanners, providing a very good signal/noise ratio and high counting rate. This allows accurate bunch-by-bunch emittance measurements during fast target sweeps (<1 s) through the beam. Very thin carbon strip targets make these measurements practically non-destructive. Bunch by bunch emittance measurements are a powerful tool for machine set-up; in RHIC, individual proton beam transverse emittances can only be measured by CNI polarimeter scans. We discuss the consistency of these measurements with Ionization Profile Monitors (IPMs) and vernier scan luminosity measurements. Absolute accuracy limitations and cross-calibration of different techniques are also discussed.

  17. High Mg-content wurtzite MgZnO alloys and their application in deep-ultraviolet light-emitters pumped by accelerated electrons

    SciTech Connect

    Ni, Pei-Nan; Shan, Chong-Xin E-mail: shendz@ciomp.ac.cn; Li, Bing-Hui; Shen, De-Zhen E-mail: shendz@ciomp.ac.cn

    2014-01-20

    High Mg-content single-phase wurtzite MgZnO alloys with a bandgap of 4.35 eV have been obtained on sapphire substrate by introducing a composition-gradient Mg{sub x}Zn{sub 1−x}O buffer layer. By employing the accelerated electrons obtained in a solid-state structure as an excitation source, an emission at around 285 nm, which is originated from the near-band-edge emission of the Mg{sub 0.51}Zn{sub 0.49}O active layer, has been observed. The results reported in this paper may provide a promising route to high performance deep-ultraviolet light-emitting devices by bypassing the challenging doping issues of wide bandgap semiconductors.

  18. Thermal activation of non-radiative Auger recombination in charged colloidal nanocrystals.

    PubMed

    Javaux, C; Mahler, B; Dubertret, B; Shabaev, A; Rodina, A V; Efros, Al L; Yakovlev, D R; Liu, F; Bayer, M; Camps, G; Biadala, L; Buil, S; Quelin, X; Hermier, J-P

    2013-03-01

    Applications of semiconductor nanocrystals such as biomarkers and light-emitting optoelectronic devices require that their fluorescence quantum yield be close to 100%. However, such quantum yields have not been obtained yet, in part, because non-radiative Auger recombination in charged nanocrystals could not be suppressed completely. Here, we synthesize colloidal core/thick-shell CdSe/CdS nanocrystals with 100% quantum yield and completely quenched Auger processes at low temperatures, although the nanocrystals are negatively photocharged. Single particle and ensemble spectroscopy in the temperature range 30-300 K shows that the non-radiative Auger recombination is thermally activated around 200 K. Experimental results are well described by a model suggesting a temperature-dependent delocalization of one of the trion electrons from the CdSe core and enhanced Auger recombination at the abrupt CdS outer surface. These results point to a route for the design of core/shell structures with 100% quantum yield at room temperature. PMID:23396313

  19. Postcollision interactions in the Auger decay of the Ar L-shell

    SciTech Connect

    Samson, J.A.R.; Stolte, W.C.; He, Z.X.

    1997-04-01

    The photoionization cross sections for Ar{sup +} through Ar{sup 4+}, produced by the Auger decay of an inner shell 2p hole, have been measured between 242 eV and 253 eV on beamline 9.0.1 and 6.3.2. In this study the authors are interested in near threshold phenomenon involving postcollision interactions (PCI), which are related to the Auger decay of a vacancy in the Ar L-shell. During an Auger decay a postcollision interaction can occur causing the out-going photoelectron to be retarded thus losing a certain amount of energy. If the retardation is sufficiently large the photoelectron will not escape. This result produces a singly charged ion, which normally would not be present. Such evidence of electron capture by the PCI effect was first shown clearly by Eberhardt et al. and, with higher resolution, in the present work. However, capture of the photoelectron is expected to be 100% exactly at the L{sub 2,3} thresholds. Thus, from the authors results they would have expected the Ar{sup 2+} signal to be zero at threshold, but it was not? The authors can explain this anomoly on the basis that during the Auger decay the photoelectrons are captured into high lying excited states of Ar{sup +}, which subsequently decay through autoionization yielding Ar{sup 2+}. Future work in this area will seek experimental evidence to verify this prediction.

  20. Electronic and chemical structure of an organic light emitter embedded in an inorganic wide-bandgap semiconductor: Photoelectron spectroscopy of layered and composite structures of Ir(BPA) and ZnSe

    NASA Astrophysics Data System (ADS)

    Dimamay, Mariel; Mayer, Thomas; Hadziioannou, Georges; Jaegermann, Wolfram

    2015-05-01

    Luminescent organic phases embedded in conductive inorganic matrices are proposed for hybrid organic-inorganic light-emitting diodes. In this configuration, the organic dye acts as the radiative recombination site for charge carriers injected into the inorganic matrix. Our investigation is aimed at finding a material combination where the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of the organic dye are situated in between the valence and conduction bands of the inorganic matrix in order to promote electron and hole transfer from the matrix to the dye. Bilayer and composite thin films of zinc selenide (ZnSe) and a red iridium complex (Ir(BPA)) organic light emitter were prepared in situ via UHV thermal evaporation technique. The electronic and atomic structures were studied applying X-ray and ultraviolet photoelectron spectroscopies. The measured energy band alignments for the ZnSe/Ir(BPA) bilayer and ZnSe+Ir(BPA) composite reveal that the HOMO and LUMO of the organic dye are positioned in the ZnSe bandgap. For the initial steps of ZnSe deposition on a dye film to form Ir(BPA)/ZnSe bilayers, zinc atoms intercalate into the dye film leaving behind an excess of selenium at the interface that partly reacts with dye molecules. Photoelectron spectroscopy of the composites shows the same species suggesting a similar mechanism. This mechanism leads to composite films with increased content of amorphous phases in the inorganic matrix, thereby affecting its conductivity, as well as to the presence of nonradiative recombination sites provided by the intercalated Zn atoms.