Science.gov

Sample records for auger electron emitters

  1. On the equivalent dose for Auger electron emitters.

    PubMed

    Howell, R W; Narra, V R; Sastry, K S; Rao, D V

    1993-04-01

    Radionuclides that emit Auger electrons are widely used in nuclear medicine (e.g., 99mTc, 123I, 201Tl) and biomedical research (e.g., 51Cr, 125I), and they are present in the environment (e.g., 40K, 55Fe). Depending on the subcellular distribution of the radionuclide, the biological effects caused by tissue-incorporated Auger emitters can be as severe as those from high-LET alpha particles. However, the recently adopted recommendations of the International Commission on Radiological Protection (ICRP) provide no guidance with regard to calculating the equivalent dose for these radionuclides. The present work, using spermatogenesis in mouse testis as the experimental model, shows that the lethality of the prolific Auger emitter 125I is linearly dependent on the fraction of the radioactivity in the organ that is bound to DNA. This suggests that the equivalent dose for Auger emitters may have a similar linear dependence. Accordingly, a formalism for calculating the equivalent dose for Auger emitters is advanced within the ICRP framework.

  2. On the Equivalent Dose for Auger Electron Emitters

    PubMed Central

    Howell, Roger W.; Narra, Venkat R.; Sastry, Kandula S. R.; Rao, Dandamudi V.

    2012-01-01

    Radionuclides that emit Auger electrons are widely used in nuclear medicine (e.g., 99mTc, 123I, 201T1) and biomedical research (e.g., 51Cr, 125I), and they are present in the environment (e.g., 40K, 55Fe). Depending on the subcellular distribution of the radionuclide, the biological effects caused by tissue-incorporated Auger emitters can be as severe as those from high-LET α particles. However, the recently adopted recommendations of the International Commission on Radiological Protection (ICRP) provide no guidance with regard to calculating the equivalent dose for these radionuclides. The present work, using spermatogenesis in mouse testis as the experimental model, shows that the lethality of the prolific Auger emitter 125I is linearly dependent on the fraction of the radioactivity in the organ that is bound to DNA. This suggests that the equivalent dose for Auger emitters may have a similar linear dependence. Accordingly, a formalism for calculating the equivalent dose for Auger emitters is advanced within the ICRP framework. PMID:8475256

  3. 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.

  4. Trifunctional somatostatin-based derivatives designed for targeted radiotherapy using auger electron emitters.

    PubMed

    Ginj, Mihaela; Hinni, Karin; Tschumi, Sibylle; Schulz, Stefan; Maecke, Helmut R

    2005-12-01

    Auger electron-emitting radionuclides have potential for the therapy of small-size cancers because of their high level of cytotoxicity, low-energy, high linear energy transfer, and short-range biologic effectiveness. Biologic effects are critically dependent on the subcellular (and even subnuclear) localization of these radionuclides. Our goals were the design, synthesis, and in vitro preclinical assessment of new trifunctional conjugates of somatostatin that should aim at the nucleus and, therefore, ensure a longer retention time in the cell, a close approximation to the DNA, and the success of Auger electron emitters in targeted radionuclide therapy as well as also improve other targeted therapy strategies. Three trifunctional derivatives of [(1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid)0,Tyr3]octreotide (DOTA-TOC) bearing the nuclear localization signal (NLS) (of simian virus 40 large-T antigen) PKKKRKV in 3 different positions relative to the somatostatin analog sequence were synthesized using solid and solution phase peptide synthesis. These compounds together with DOTA-TOC and DOTA-NLS derivatives were labeled with 111In and tested for binding affinity, internalization, externalization, and nuclei localization on AR4-2J cells and on human embryonic cells stably transfected with sst2A. The two N-terminal derivatives preserved the sstr2A binding affinity. Their rate of internalization in all tested sstr-expressing cell lines was always superior for the trifunctional derivatives in comparison with the parent compound. A 6-fold increase in cellular retention from the total internalized activity and a 45-fold higher accumulation in the cell nuclei were found for one of the N-terminally modified compounds compared with [111In]-DOTA-TOC. The C-terminal conjugate was inferior in all tests compared with the parent compound. These encouraging results support our hypothesis that an additional NLS sequence to the DOTA-TOC could not only provide a better

  5. A compilation of microdosimetry for uniformly distributed Auger emitters used in medicine.

    PubMed

    Chen, Jing

    2008-12-01

    To provide a compilation of microdosimetric characteristics for 12 Auger emitters commonly used in medicine. Monte Carlo electron track structure simulations are performed for 12 Auger emitters. They are (55)Fe, (67)Ga, (99m)Tc, (111)In, (113m)In, (115m)In, (123)I, (125)I, (193m)Pt, (195m)Pt, (201)Tl, and (203)Pb. Proximity functions of 12 Auger emitters are calculated from the simulated track structures and compared with that of gamma rays from (60)Co. Some of those Auger emitters are highly radiotoxic compared to hard gamma rays from (60)Co. The more electrons per decay and the lower electron energies, the more effective an Auger emitter could be. The high radiotoxicity of Auger emitters is due to correlations of low-energy electrons released from decay processes. If these correlations were disregarded, Auger emitters would not differ significantly from other low linear energy transfer (LET) radiation sources. Even in the case of uniform distribution, some of those Auger emitters are highly radiotoxic compared to hard gamma rays. For Auger emitters to bond to radiosensitive sites in cell nucleus, much higher radiation effectiveness could be expected.

  6. Dosimetry of Auger emitters: Physical and phenomenological approaches

    SciTech Connect

    Sastry, K.S.R.; Howell, R.W.; Rao, D.V.; Mylavarapu, V.B.; Kassis, A.I.; Adelstein, S.J.; Wright, H.A.; Hamm, R.N.; Turner, J.E.

    1987-01-01

    Recent radiobiological studies have demonstrated that Auger cascades can cause severe biological damage contrary to expectations based on conventional dosimetry. Several determinants govern these effects, including the nature of the Auger electron spectrum; localized energy deposition; cellular geometry; chemical form of the carrier; cellular localization, concentration, and subcellular distribution of the radionuclide. Conventional dosimetry is inadequate in that these considerations are ignored. Our results provide the basis for biophysical approaches toward subcellular dosimetry of Auger emitters in vitro and in vivo. 12 refs., 7 figs., 2 tabs.

  7. Incorporation of iododeoxyuridine in multicellular glioma spheroids: implications for DNA-targeted radiotherapy using Auger electron emitters.

    PubMed Central

    Neshasteh-Riz, A.; Angerson, W. J.; Reeves, J. R.; Smith, G.; Rampling, R.; Mairs, R. J.

    1997-01-01

    A promising new treatment for glioma involves Auger electron emitters such as 125I or 123I conjugated to deoxyuridine (IUdR). However, the presence in tumour deposits of non-proliferating cells with clonogenic potential poses a major limitation to this cycle-specific therapy. We have used multicellular tumour spheroids derived from the human glioma cell line UVW to study [125I]IUdR-targeted radiotherapy in aggregates containing cells in different proliferative states. Autoradiographic identification of labelled cells indicated that nuclear incorporation of [125I]IUdR decreased markedly with increasing size of spheroid. IUdR incorporation was maximal in the surface layer of cells and decreased with depth within spheroids. Radiopharmaceutical uptake corresponded closely to the regions of cell cycling as indicated by staining for the nuclear antigen Ki67. The uptake of drug was enhanced by increasing the duration of incubation from 52 h to 104 h. These observations suggest that significant sparing of non-cycling malignant cells would result from treatment delivered as a single injection of radiolabelled IUdR. To achieve maximal therapeutic effect. IUdR should be administered by multiple injections, by slow release from biodegradable implants or by slow-pump delivery. Images Figure 2 PMID:9052399

  8. Spin-polarized Auger electrons

    NASA Astrophysics Data System (ADS)

    Merz, H.; Semke, J.

    1990-12-01

    The spin polarization of Auger electrons will be discussed within the standard two-step model of the Auger emission process for different situations: target polarized, projectile polarized, targe and projectile unpolarized. In these three cases different interaction mechanisms are responsible for the polarization of the emitted Auger electrons. The present theoretical and experimental situation will be reviewed.

  9. Nanodosimetry of (125)I Auger electrons.

    PubMed

    Bantsar, Aliaksandr; Pszona, Stanislaw

    2012-12-01

    The nanodosimetric description of the radiation action of Auger electrons on nitrogen targets of nanometric size is presented. Experimental microdosimetry at nanometer scale for Auger electrons has been accomplished with the set-up called Jet Counter. This consists of a pulse-operated valve which injects an expanding nitrogen jet into an interaction chamber where a gaseous sensitive volume of cylindrical shape is created. The ionization cluster size distributions (ICSD) created by Auger electrons emitted by (125)I while crossing a nanometer-sized volume have been measured. The ICSD for the sensitive volumes corresponding to 3 and 12 nm in diameter (in unit density 1 g/cm(3)) irradiated by electrons emitted by a (125)I source were collected and compared with the corresponding Monte Carlo (MC) simulation. The preliminary results of the experiments with Auger electrons of (125)I interacting with a nitrogen jet having nanometric size comparable to a deoxyribonucleic acid (DNA) and nucleosome, showing the discrete spectrum of ICSD with extended cluster size, are described. The presented paper describes for the first time the nanodosimetric experiments with Auger electrons emitted by (125)I. A set of the new descriptors of the radiation quality describing the radiation effect at nanometer level is proposed. The ICSD were determined for the first time for an Auger emitter of (125)I.

  10. ET-22CONVECTION-ENHANCED DELIVERY OF THE AUGER-ELECTRON-EMITTER 125I-UdR: A HIGHLY EFFICIENT THERAPY IN AN ORTHOTOPIC GLIOBLASTOMA XENOGRAFT MODEL

    PubMed Central

    Halle, Bo; Thisgaard, Helge; Aaberg-Jessen, Charlotte; Olsen, Birgitte; Dam, Johan; Langkjær, Niels; Munthe, Sune; Någren, Kjell; Høilund-Carlsen, Poul Flemming; Kristensen, Bjarne

    2014-01-01

    BACKGROUND: Glioblastomas (GBMs), the most common and malignant primary brain tumors, always recur after standard treatment. In order to develop more efficient therapies, we tested a novel therapeutic approach using the radioactive Auger-electron-emitter (AEE) [125I]5-Iodo-2'-deoxyuridine (125I-UdR). This drug incorporates into DNA of dividing cells and upon decay emission of Auger-electrons causes clusters of double strand breaks leading to cell death. METHODS: In vitro, cells from two GBM spheroid cultures (T78 & T87) were exposed to either 125I-UdR or 127I-UdR (non-radioactive analogue) and tumor cell viability and migration were measured. In vivo, nude rats were implanted orthotopically with T87 cells and after tumor formation micro infusion pumps were implanted enabling direct intratumoral convection-enhanced delivery (CED). Animals were divided into three groups (I-III). Group I (n = 8) was treated with 127I-UdR by CED, group II (n = 7) with neoadjuvant methotrexate (MTX) + 125I-UdR by CED and group III with neoadjuvant MTX + 125I-UdR by CED and concomitant systemic temozolomide (TMZ). Rats were followed for 180 days post-treatment with repeated [11C]methylaminoisobutyric acid ([11C]MeAIB) positron emission tomography scans and blood sampling. Single photon emission computed tomography/computed tomography (SPECT/CT) scans were performed to evaluate 125I-UdR distribution. Additionally, post-mortem histological examination of brain, liver, kidneys and thyroid gland was performed. RESULTS: In vitro, 125I-UdR significantly decreased GBM cell viability and migration. In group I, no animals (8/8) survived longer than 23 days after treatment start. In group II, 4/7 animals survived the entire observation period of 180 days. In group III, all animals (8/8) survived the entire observation period. SPECT/CT showed a widespread intracerebral distribution of 125I-UdR, while blood samples and post-mortem histology revealed no signs of dose-limiting adverse effects

  11. WE-AB-204-12: Dosimetry at the Sub-Cellular Scale of Auger-Electron Emitter 99m-Tc in a Mouse Single Thyroid Follicle Model

    SciTech Connect

    Taborda, A; Benabdallah, N; Desbree, A

    2015-06-15

    Purpose: To perform a dosimetry study at the sub-cellular scale of Auger-electron emitter 99m-Tc using a mouse single thyroid cellular model to investigate the contribution of the 99m-Tc Auger-electrons to the absorbed dose and possible link to the thyroid stunning in in vivo experiments in mice, recently reported in literature. Methods: The simulation of S-values for Auger-electron emitting radionuclides was performed using both the recent MCNP6 software and the Geant4-DNA extension of the Geant4 toolkit. The dosimetric calculations were validated through comparison with results from literature, using a simple model of a single cell consisting of two concentric spheres of unit density water and for six Auger-electron emitting radionuclides. Furthermore, the S-values were calculated using a single thyroid follicle model for uniformly distributed 123-I and 125-I radionuclides and compared with published S-values. After validation, the simulation of the S-values was performed for the 99m-Tc radionuclide within the several mouse thyroid follicle cellular compartments, considering the radiative and non-radiative transitions of the 99m-Tc radiation spectrum. Results: The calculated S-values using MCNP6 are in good agreement with the results from literature, validating its use for the 99m-Tc S-values calculations. The most significant absorbed dose corresponds to the case where the radionuclide is uniformly distributed in the follicular cell’s nucleus, with a S-value of 7.8 mGy/disintegration, due mainly to the absorbed Auger-electrons. The results show that, at a sub-cellular scale, the emitted X-rays and gamma particles do not contribute significantly to the absorbed dose. Conclusion: In this work, MCNP6 was validated for dosimetric studies at the sub-cellular scale. It was shown that the contribution of the Auger-electrons to the absorbed dose is important at this scale compared to the emitted photons’ contribution and can’t be neglected. The obtained S

  12. 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.

  13. Study on cell survival, induction of apoptosis and micronucleus formation in SCL-II cells after exposure to the auger electron emitter (99m)Tc.

    PubMed

    Kriehuber, R; Kadenbach, K; Schultz, F; Weiss, D G

    2004-01-01

    To study the biological effectiveness of Auger electrons emitted by (99m)Tc on cell survival, induction of apoptosis and micronucleus (MN) formation in the human squamous cell carcinoma cell line SCL-II and compare the effects observed to those observed after exposure to external 60Co gamma radiation. Cells were either gamma(60Co)-irradiated (0.67 Gy/min) or exposed to (99m)Tc-pertechnetate (0.95-14.3 MBq/ml) for 24 h under cell culture conditions and assayed for cell survival (colony-forming assay), micronucleus formation (cytochalasin B assay) and the frequency of apoptotic cells (fluorescence microscopy). Monte Carlo based dosimetry has been applied to derive the absorbed dose corresponding to the accumulated decays of (99m)Tc under the given geometry. Absorbed doses up to 0.5 Gy could be achieved after 99mTc-exposure leading to no substantial cell killing in this dose range except at one dose point (0.1 Gy) resulting in an relative biological effectiveness (RBE)SF 0.9 of 0.64 when compared to the 60Co reference radiation. MN formation was described best by a linear dose response and was consistently lower after 99mTc exposure when compared to 60Co irradiated cells resulting in an RBE of 0.37. Apoptosis induction was significantly increased after 99mTc exposure at much lower doses (0.1 Gy) when compared to the reference radiation. The (99m)Tc uptake experiments revealed an activity concentration ratio cells vs. medium of 0.07 after 24 h of exposure. No overall increased biological effectiveness due to the emitted Auger electrons of (99m)Tc, applied as sodium-pertechnetate, could be observed in the investigated cell line when compared to acute external gamma radiation. The RBEs in the range of 0.37-0.64 might be well explained by dose rate effects. The significantly increased apoptotic response after (99m)Tc-exposure at very low doses has to be further investigated.

  14. {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.

  15. Calculation of equivalent dose for Auger electron emitting radionuclides distributed in human organs.

    PubMed

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

    1996-01-01

    Radionuclides that emit Auger electrons can be extremely radiotoxic depending on the subcellular distribution of the radiochemical. Despite this, ICRP 60 provides no guidance in the calculation of equivalent dose H(T) for Auger electrons. The recent report by the American Association of Physicists in Medicine recommends a radiation weighting factor wR of 20 for stochastic effects caused by Auger electrons, along with a method of calculating the equivalent dose that takes into account the subcellular distribution of the radionuclide. In view of these recommendations, it is important to reevaluate equivalent doses from Auger electron emitters. The mean absorbed dose per unit cumulated activity (S-value) from Auger electrons and other radiations is calculated for ninety Auger-electron-emitting radionuclides distributed in human ovaries, testes and liver. Using these S-values, and the formalism given in the recent AAPM report, the dependence of the organ equivalent doses on subcellular distribution of the Auger electron emitters is examined. The results show an increase in the mean equivalent dose for Auger electron emitters when a significant fraction of the organ activity localizes in the DNA.

  16. 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.

  17. 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.

  18. 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.

  19. Diamondoid monolayers as electron emitters

    DOEpatents

    Yang, Wanli [El Cerrito, CA; Fabbri, Jason D [San Francisco, CA; Melosh, Nicholas A [Menlo Park, CA; Hussain, Zahid [Orinda, CA; Shen, Zhi-Xun [Stanford, CA

    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.

  20. 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.

  1. Site-selected Auger electron spectroscopy of N2O.

    PubMed

    Bolognesi, Paola; Coreno, Marcello; Avaldi, Lorenzo; Storchi, Loriano; Tarantelli, Francesco

    2006-08-07

    The N 1s Auger spectra for the two nonequivalent N atoms in N2O have been measured via Auger electron-photoelectron coincidence spectroscopy. The site-selected Auger spectra are compared with the normal Auger spectrum and with accurate theoretical calculations accounting for the effects of the dynamics of the nuclei on the energy and linewidth of the Auger bands. Such effects are found to be crucial factors in determining the different band shapes in the site-selected spectra.

  2. Observation of four-electron Auger processes

    NASA Astrophysics Data System (ADS)

    Müller, A.; Borovik, A., Jr.; Buhr, T.; Hellhund, J.; Holste, K.; Kilcoyne, A. L. D.; Klumpp, S.; Martins, M.; Ricz, S.; Viefhaus, J.; Schippers, S.

    2015-09-01

    Multiple ionization of ions subsequent to absorption of a single photon has been studied employing a photon-ion merged-beam setup at the PETRA III synchrotron radiation facility of DESY in Hamburg. Absolute cross sections for single, double and triple ionization of C+ ions were measured with emphasis on specific well defined terms of K-shell excited C+. In particular, the terms C+ (1s2s22p2 2D,2P) were excited from the ground level of C+. Subsequent autoionization processes resulted in the production of C2+, C3+ and C4+ ions. The associated decay mechanisms are single-Auger, double-Auger and triple-Auger decay. The observation of C4+ products arising from C+(1s2s22p2 2D,2P) unambiguously confirmed the existence of triple-Auger decay, i.e., a process in which 4 electrons interact with one another such that one fills the K-shell vacancy and the others are simultaneously ejected. The experiment yields branching ratios for the Auger decay channels as well as individual decay rates for autoionization and radiative stabilization of the C+(1s2s22p2 2D,2P) terms.

  3. 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.

  4. Role of Emission Character in Auger Electron Diffraction

    NASA Astrophysics Data System (ADS)

    Idzerda, Y. U.

    A review of the interpretation of the angle-dependent Auger intensity pattern by both Auger electron diffraction (AED), which is concerned with identifying the nearby atomic structure, and angle-resolved Auger electron spectroscopy (ARAES), which is concerned with identifying the character of the emitted electron source function, is presented. The importance of the emission character of the Auger electron (in terms of its angular momentum, l, and its magnetic quantum number, m) in understanding the generation of the AED and ARAES patterns is described. Understanding of how the various direct and secondary mechanisms for the Auger electron generation can affect the populations of these states can also be used to help identify the multiplet structure within the Auger lineshape as well as elucidate the core hole generation process.

  5. Emitter location errors in electronic recognition system

    NASA Astrophysics Data System (ADS)

    Matuszewski, Jan; Dikta, Anna

    2017-04-01

    The paper describes some of the problems associated with emitter location calculations. This aspect is the most important part of the series of tasks in the electronic recognition systems. The basic tasks include: detection of emission of electromagnetic signals, tracking (determining the direction of emitter sources), signal analysis in order to classify different emitter types and the identification of the sources of emission of the same type. The paper presents a brief description of the main methods of emitter localization and the basic mathematical formulae for calculating their location. The errors' estimation has been made to determine the emitter location for three different methods and different scenarios of emitters and direction finding (DF) sensors deployment in the electromagnetic environment. The emitter has been established using a special computer program. On the basis of extensive numerical calculations, the evaluation of precise emitter location in the recognition systems for different configuration alignment of bearing devices and emitter was conducted. The calculations which have been made based on the simulated data for different methods of location are presented in the figures and respective tables. The obtained results demonstrate that calculation of the precise emitter location depends on: the number of DF sensors, the distances between emitter and DF sensors, their mutual location in the reconnaissance area and bearing errors. The precise emitter location varies depending on the number of obtained bearings. The higher the number of bearings, the better the accuracy of calculated emitter location in spite of relatively high bearing errors for each DF sensor.

  6. Low Emittance Electron Beam Studies

    SciTech Connect

    Tikhoplav, Rodion

    2006-01-01

    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*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.

  7. 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.

  8. Molecular frame Auger electron energy spectrum from N2

    NASA Astrophysics Data System (ADS)

    Cryan, J. P.; Glownia, J. M.; Andreasson, J.; Belkacem, A.; Berrah, N.; Blaga, C. I.; Bostedt, C.; Bozek, J.; Cherepkov, N. A.; DiMauro, L. F.; Fang, L.; Gessner, O.; Gühr, M.; Hajdu, J.; Hertlein, M. P.; Hoener, M.; Kornilov, O.; Marangos, J. P.; March, A. M.; McFarland, B. K.; Merdji, H.; Messerschmidt, M.; Petrović, V. S.; Raman, C.; Ray, D.; Reis, D. A.; Semenov, S. K.; Trigo, M.; White, J. L.; White, W.; Young, L.; Bucksbaum, P. H.; Coffee, R. N.

    2012-03-01

    Here we present the first angle-resolved, non-resonant (normal) Auger spectra for impulsively aligned nitrogen molecules. We have measured the angular pattern of Auger electron emission following K-shell photoionization by 1.1 keV photons from the Linac Coherent Light Source (LCLS). Using strong-field-induced molecular alignment to make molecular frame measurements is equally effective for both repulsive and quasi-bound final states. The capability to resolve Auger emission angular distributions in the molecular frame of reference provides a new tool for spectral assignments in congested Auger electron spectra that takes advantage of the symmetries of the final diction states. Based on our experimental results and theoretical predictions, we propose the assignment of the spectral features in the Auger electron spectrum.

  9. Energy efficiency of electron plasma emitters

    SciTech Connect

    Zalesski, V. G.

    2011-12-15

    Electron emission influence from gas-discharge plasma on plasma emitter energy parameters is considered. It is shown, that electron emission from plasma is accompanied by energy contribution redistribution in the gas-discharge from plasma emitter supplies sources-the gas-discharge power supply and the accelerating voltage power supply. Some modes of electron emission as a result can be realized: 'a probe measurements mode,' 'a transitive mode,' and 'a full switching mode.'.

  10. Exploring Protonation and Deprotonation Effects with Auger Electron Spectroscopy.

    PubMed

    Kryzhevoi, Nikolai V; Cederbaum, Lorenz S

    2012-09-20

    Auger electron spectroscopy is demonstrated to be a very efficient tool to probe alterations in local chemical environment due to changes in protonation states. We show that electronic and geometric structure changes induced by protonation or deprotonation are well reflected in Auger spectra through characteristic chemical shifts and spectral shape variations. We also present evidence that Auger spectra are sensitive to relative concentrations of compounds in different protonation states. Special attention is paid to the high kinetic energy spectral regions that exhibit remarkable features resulting from core ICD-like transitions in normal species and Auger transitions in deprotonated fragments. The latter contribution was so far ignored when explaining Auger spectra of species embedded in the environment. This contribution should be reconsidered, taking into account the recently discovered possibility of ultrafast dissociation of core-ionized hydrogen-bonded systems in media.

  11. Some performance tests of a microarea AES. [Auger Electron Spectroscopy

    NASA Technical Reports Server (NTRS)

    Todd, G.; Poppa, H.

    1978-01-01

    An Auger electron spectroscopy (AES) system which has a submicron analysis capability is described. The system provides secondary electron imaging, as well as micro- and macro-area AES. The resolution of the secondary electron image of an oxidized Al contact pad on a charge-coupled device chip indicates a primary beam size of about 1000 A. For Auger mapping, a useful resolution of about 4000 A is reported

  12. 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.

  13. Bone calcium, phosphorus detection by Auger electron spectroscopy.

    PubMed

    Tzaphlidou, Margaret; Berillis, Panagiotis; Matthopoulos, Demetrios

    2005-01-01

    Auger electron spectroscopy was used to detect calcium and phosphorus of cortical bone from rat femoral neck and rear tibia. Spectra were taken from bone pieces as well as from disks prepared from grinded bone material. Experimental conditions were found whereby the samples could be analyzed without conductive coatings. The results of this preliminary investigation demonstrate that Auger electron spectroscopy can be used to study bone mineral elements.

  14. Directional Auger Electron Spectroscopy — Physical Foundations and Applications

    NASA Astrophysics Data System (ADS)

    Mróz, S.

    Experimental data about the dependence of the Auger signal from crystalline samples on the primary beam direction are presented and discussed. It is shown that, for Auger electrons and elastically and inelastically backscattered electrons, maxima of the signal in its dependence on the polar and azimuth angles of the primary beam (in polar and azimuth profiles, respectively) appear when the primary beam is parallel either to one of the close-packed rows of atoms or to one of the densely packed atomic planes in the sample. This indicates that the diffraction of the primary electron beam is responsible for the dependence mentioned above. Mechanisms proposed for simple explanation of this dependence (channeling and forward focusing of primary electrons) are presented and results of their application are discussed. It is shown that both those mechanisms play an important role in the creation of the Auger signal contrast. The possibilities and limitations of the application of polar and azimuth Auger emission profiles in the determination of the surface layer crystalline structure (directional Auger electron spectroscopy — DAES) are presented and discussed. It is shown that the thickness of the investigated surface layer can be decreased up to a few monolayers. Results obtained with DAES are similar to those provided by X-ray photoelectron diffraction (XPD) and Auger electron diffraction (AED), but the DAES experimental equipment is simple and inexpensive and measurements are fast. Finally, experimental systems for DAES are described and examples of DAES applications are presented.

  15. Auger electron intensity variations in oxygen-charged silver

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

    Auger intensity variations over an oxygen-charged polycrystalline silver surface have been observed by studies of Auger images and line scans of selected adjacent grains which were determined to be the (421) and (221) orientations. The observed contrast (M4.5VV transition) between the grains is produced by the variation in the detected Auger electrons caused by the different directions (interatomic direction) of forward focusing in each grain. The contrast produced by the Ag Auger electrons was found to be strongly dependent on the surface order of the grains, but that of the O Auger electrons was not, presumably because the atoms were randomly distributed throughout the Ag surface or subsurface. The contrast observed between the grains at the lower Auger energies (N1VV and N1N2.3V transitions) appeared to be produced by constructive interference from multiple scattering. The N1N2.3V electrons at 29 eV, for example, gave higher contrast than that of the N1VV transition at 78 eV.

  16. Auger electron intensity variations in oxygen-charged silver

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

    Auger intensity variations over an oxygen-charged polycrystalline silver surface have been observed by studies of Auger images and line scans of selected adjacent grains which were determined to be the (421) and (221) orientations. The observed contrast (M4.5VV transition) between the grains is produced by the variation in the detected Auger electrons caused by the different directions (interatomic direction) of forward focusing in each grain. The contrast produced by the Ag Auger electrons was found to be strongly dependent on the surface order of the grains, but that of the O Auger electrons was not, presumably because the atoms were randomly distributed throughout the Ag surface or subsurface. The contrast observed between the grains at the lower Auger energies (N1VV and N1N2.3V transitions) appeared to be produced by constructive interference from multiple scattering. The N1N2.3V electrons at 29 eV, for example, gave higher contrast than that of the N1VV transition at 78 eV.

  17. Mapping the composition of planetary surfaces by Auger electron spectroscopy

    NASA Technical Reports Server (NTRS)

    Lin, R. P.; Gopalan, R.

    1991-01-01

    The feasibility of AES as a remote-sensing technique to map the composition of the sunlit surfaces of planetary bodies without atmospheres is studied. Solar X-rays eject photoelectrons from the planetary surface. The resulting ions relax by emission of fluorescence X-rays or Auger electrons, with energies characteristic of the element which is ionized. The spectrum of Auger electrons and photoelectrons is computed for a variety of elements and for representative lunar rock types illuminated by soft-X-ray line and continuum emission typical of solar long-lived coronal active regions. The Auger electron lines for O, Si, Mg, Al, Fe, and Ca in lunar rocks stand well above the continuum background from photoelectrons and backscattered interplanetary electrons, with typical line-to-continuum ratios from about 20 to over 1000.

  18. In situ observation on electron beam induced chemical vapor deposition by Auger electron spectroscopy

    SciTech Connect

    Matsui, S.; Mori, K.

    1987-08-31

    W deposition, using WF/sub 6/ gas source by electron beam induced surface reaction, has been studied by Auger electron spectroscopy. W Auger electron signals have been observed for WF/sub 6/ adlayer by Auger electron spectroscopy. Moreover, initial growth for W deposition has been observed in situ by Auger electron spectroscopy. As a result, it became clear that a growth rate for W deposition is proportional to WF/sub 6/ gas pressure and can be --1 A/min at 2 x 10/sup -7/ Torr.

  19. Auger electron spectroscopy of lunar samples

    NASA Technical Reports Server (NTRS)

    Grant, R. W.; Housley, R. M.; Szalkowski, F. J.; Marcus, H. L.

    1974-01-01

    Auger spectroscopy has been employed to study the surface composition of a number of grains from the submillimeter lunar fines. Some of the problems associated with using this technique for lunar sample analyses are discussed in terms of relevant physical principles. The use of inert gas sputtering to obtain thickness profiles of surface films is shown to be important in this type of investigation. Four anorthite grains from the Apollo 17 fines have been examined for evidence of vapor-deposited surface coatings of micrometeorite impact origin. The results indicate that the thickness of surface deposits, if they exist at all, are orders of magnitude less than expected. Auger analysis of orange glass balls form the 74220,107 fines have established sulfur-rich surface coatings on the order of 30 A in thickness.

  20. Auger electron spectroscopy of contrast-forming layers on metals

    NASA Technical Reports Server (NTRS)

    Hoffmann, Siegfried; Exner, Hans Eckart

    1988-01-01

    As shown by Auger electron spectroscopy, the layers formed during contrasting metallographic polished Cu and Ni with an apparatus using intense electron bombardment consist of metal sputtered from the Au, Fe, or Pb cathode. This layer takes up oxygen from the residual atmosphere. The mechanism of contrast enhancement is the same as that of vapor-deposited interference layers.

  1. 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.

  2. 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.

  3. The effect of dimethyl sulfoxide on the induction of DNA strand breaks in plasmid DNA and colony formation of PC Cl3 mammalian cells by alpha-, beta-, and Auger electron emitters (223)Ra, (188)Re, and (99m)Tc.

    PubMed

    Runge, Roswitha; Oehme, Liane; Kotzerke, Jörg; Freudenberg, Robert

    2016-12-01

    DNA damage occurs as a consequence of both direct and indirect effects of ionizing radiation. The severity of DNA damage depends on the physical characteristics of the radiation quality, e.g., the linear energy transfer (LET). There are still contrary findings regarding direct or indirect interactions of high-LET emitters with DNA. Our aim is to determine DNA damage and the effect on cellular survival induced by (223)Ra compared to (188)Re and (99m)Tc modulated by the radical scavenger dimethyl sulfoxide (DMSO). Radioactive solutions of (223)Ra, (188)Re, or (99m)Tc were added to either plasmid DNA or to PC Cl3 cells in the absence or presence of DMSO. Following irradiation, single strand breaks (SSB) and double strand breaks (DSB) in plasmid DNA were analyzed by gel electrophoresis. To determine the radiosensitivity of the rat thyroid cell line (PC Cl3), survival curves were performed using the colony formation assay. Exposure to 120 Gy of (223)Ra, (188)Re, or (99m)Tc leads to maximal yields of SSB (80 %) in plasmid DNA. Irradiation with 540 Gy (223)Ra and 500 Gy (188)Re or (99m)Tc induced 40, 28, and 64 % linear plasmid conformations, respectively. DMSO prevented the SSB and DSB in a similar way for all radionuclides. However, with the α-emitter (223)Ra, a low level of DSB could not be prevented by DMSO. Irradiation of PC Cl3 cells with (223)Ra, (188)Re, and (99m)Tc pre-incubated with DMSO revealed enhanced survival fractions (SF) in comparison to treatment without DMSO. Protection factors (PF) were calculated using the fitted survival curves. These factors are 1.23 ± 0.04, 1.20 ± 0.19, and 1.34 ± 0.05 for (223)Ra, (188)Re, and (99m)Tc, respectively. For (223)Ra, as well as for (188)Re and (99m)Tc, dose-dependent radiation effects were found applicable for plasmid DNA and PC Cl3 cells. The radioprotection by DMSO was in the same range for high- and low-LET emitter. Overall, the results indicate the contribution of mainly indirect radiation

  4. Triple targeting of Auger emitters using octreotate conjugated to a DNA-binding ligand and a nuclear localizing signal.

    PubMed

    Violet, John A; Farrugia, Gabriella; Skene, Colin; White, Jonathan; Lobachevsky, Pavel; Martin, Roger

    2016-11-01

    We investigated the effect of incorporation of a nuclear localization signal (NLS) into a conjugate comprising the DNA binding ligand para-iodoHoechst (PIH) and octreotate on its DNA binding and affinity to the somatostatin receptor (SSTR). Confirmation of these properties would support development of similar conjugates labelled with Auger emitters for their potential in Auger endoradiotherapy. We synthesized conjugates of PIH and octreotate (PO) or PIH and NLS (PN) and a conjugate comprising PIH, NLS and octreotate (PNO). DNA-binding characteristics of PIH and conjugates were assessed using synthetic DNA oligonucleotides employing spectrophotometric titration of ligand solutions with DNA. We used membranes from the type 2 SSTR (SSTR2) overexpressing human non-small cell lung cancer cell line A427-7 to investigate the binding affinity of PNO. We demonstrated PN and PNO retain specific high affinity DNA-binding properties observed for PIH, and acquire an additional non-specific binding capacity. No DNA binding was observed for PO. PNO retains its binding affinity for SSTR. The DNA-binding properties of PNO and its affinity for SSTR suggests that it could potentially be used for tumour-specific delivery of PIH labelled with an Auger emitter in SSTR expressing tumours.

  5. 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.

  6. Energy and angular distributions of electrons emitted by direct double auger decay.

    PubMed

    Viefhaus, Jens; Cvejanović, Slobodan; Langer, Burkhard; Lischke, Toralf; Prümper, Georg; Rolles, Daniel; Golovin, Alexander V; Grum-Grzhimailo, Alexei N; Kabachnik, Nikolai M; Becker, Uwe

    2004-02-27

    We have observed the direct L(2,3)MMM double Auger transition after photoionization of the 2p shell of argon by angle-resolved electron-electron coincidence spectroscopy. The process is responsible for about 20% of the observed Auger electron intensity. In contrast to the normal Auger lines, the spectra in double Auger decay show a continuous intensity distribution. The energy and angular distributions of the emitted electrons allow one to obtain information on the electron correlations giving rise to the double Auger process as well as the symmetry of the associated two-electron continuum state.

  7. Path-reversed Auger electron and photoelectron diffraction

    SciTech Connect

    Pauli, M. D.; Saldin, D. K.

    2001-08-15

    We propose a method for the computer simulation of Auger electron and photoelectron diffraction patterns by evaluating the amplitude of propagation paths from the detector to the electron-emitting source, justified by Helmholtz's reciprocity principle. The method offers significant computational advantages over previous schemes, and suggests an easy extension to enable the calculation of a structure-perturbation tensor for rapid crystallographic parameter variation.

  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. 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.

  10. 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.

  11. Incident-beam effects in electron-stimulated Auger-electron diffraction

    NASA Astrophysics Data System (ADS)

    Gao, Y.; Cao, Jianming

    1991-04-01

    We have examined incident-beam effects in electron-stimulated Auger-electron diffraction (AED) on a cleaved GaAs(110) surface. The results indicate that incident-beam diffraction is significant in an AED experiment, and that the dissipative nature of the incident beam in contributing to the Auger process must be accounted for. We have developed a qualitative model that describes the trend of the polar-angle dependence of the Auger intensity for both the incident and exit beams. In calculating the diffraction features, we used a zeroth-order approximation to simulate the dissipation of the incident beam, which is found to adequately describe the experimental data.

  12. 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.

  13. Surface segregation in titanium as monitored by Auger electron spectroscopy

    NASA Technical Reports Server (NTRS)

    Khan, I. H.

    1973-01-01

    Investigation of the surface diffusion and segregation of bulk impurities in titanium single crystals under well-defined and controlled experimental conditions. It is shown that an atomically clean titanium single-crystal surface can be obtained by argon ion bombardment within the temperature range from 700 to 800 C. It is demonstrated by Auger electron spectroscopy that, if such clean surfaces are subjected to thermal treatment, bulk impurities, especially sulfur, diffuse out to the crystal surface, and that the rate of surface segregation increases with increasing temperature.

  14. Surface segregation in titanium as monitored by Auger electron spectroscopy

    NASA Technical Reports Server (NTRS)

    Khan, I. H.

    1973-01-01

    Investigation of the surface diffusion and segregation of bulk impurities in titanium single crystals under well-defined and controlled experimental conditions. It is shown that an atomically clean titanium single-crystal surface can be obtained by argon ion bombardment within the temperature range from 700 to 800 C. It is demonstrated by Auger electron spectroscopy that, if such clean surfaces are subjected to thermal treatment, bulk impurities, especially sulfur, diffuse out to the crystal surface, and that the rate of surface segregation increases with increasing temperature.

  15. Evaluations of carbon nanotube field emitters for electron microscopy

    NASA Astrophysics Data System (ADS)

    Nakahara, Hitoshi; Kusano, Yoshikazu; Kono, Takumi; Saito, Yahachi

    2009-11-01

    Brightness of carbon nanotube (CNT) emitters was already reported elsewhere. However, brightness of electron emitter is affected by a virtual source size of the emitter, which strongly depends on electron optical configuration around the emitter. In this work, I- V characteristics and brightness of a CNT emitter are measured under a practical field emission electron gun (e-gun) configuration to investigate availability of CNT for electron microscopy. As a result, it is obtained that an emission area of MWNT is smaller than its tip surface area, and the emission area corresponds to a five-membered-ring with 2nd nearest six-membered-rings on the MWNT cap surface. Reduced brightness of MWNT is measured as at least 2.6×109 A/m 2 sr V. It is concluded that even a thick MWNT has enough brightness under a practical e-gun electrode configuration and suitable for electron microscopy.

  16. Ultrafast Molecular Three-Electron Collective Auger Decay

    NASA Astrophysics Data System (ADS)

    Feifel, Raimund

    2016-06-01

    A new class of many-electron Auger transitions in atoms was initially proposed over 40 years ago, but the first tentative evidence for its real existence was only adduced by Lee et al. in 1993, on the basis of the resonant Auger spectrum of Kr. Using a multi-electron coincidence technique with synchrotron radiation, we unambiguously showed very recently that the transition suggested by Lee et al. in Kr really does take place, but with a rather small branching ratio. Related inter-atomic three-electron transitions in rare gas clusters were recently predicted by Averbukh and Kolorenc and demonstrated by Ouchi et al.. From consideration of the energy levels involved it seems that the basic three-electron process could occur in molecules too, wherever a double inner-valence shell vacancy lies at a higher energy than the molecular triple ionisation onset. Experiments on CH_3F reveal for the first time the existence of this new decay pathway there, and calculations show that despite its three-electron nature, its effective oscillator strength is orders of magnitudes higher than in atoms, allowing an efficient competition with both molecular dissociation and two-electron decay channels on the ultrafast time scale. The dramatic enhancement of the molecular three-electron Auger transition can be explained in terms of a partial breakdown of the molecular orbital picture of ionisation. We predict that the collective decay pathway will be significant in a wide variety of heteroatomic molecules ionised by extreme UV and soft X-rays, particularly at Free-Electron-Lasers where double inner-shell vacancies can be created efficiently by two-photon transitions. G.N. Ogurtsov et al., Sov. Phys. Tech. Phys. 15, 1656 (1971) and V.V. Afrosimov et al., JETP Lett. 21, 249 (1975). I. Lee, R. Wehlitz, U. Becker and M. Ya. Amusia, J. Phys. B: At. Mol. Opt. Phys. 26, L41 (1993). J.H.D. Eland, R.J. Squibb, M. Mucke, S. Zagorodskikh, P. Linusson, and R. Feifel, New J. Phys. 17, 122001 (2015). V

  17. Internal quantum efficiency and Auger recombination in green, yellow and red InGaN-based light emitters grown along the polar direction

    NASA Astrophysics Data System (ADS)

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

    2017-03-01

    We comparatively study the onset of photo-induced non-radiative intrinsic Auger recombination processes for red, yellow and green light emitting InGaNsbnd GaN hetero-structures grown along the polar orientation. We find a dramatic reduction of the photo excitation densities triggering the domination of Auger effect with increasing emission wavelength; that is to say in concert with the enhancement of the internal electric field in the structure. In long wavelength emitters, the internal electric field is stronger, and hence reducing the impact of the internal electric field is more critical.

  18. Emittance measurements of the CLIO electron beam

    NASA Astrophysics Data System (ADS)

    Chaput, R.; Devanz, G.; Joly, P.; Kergosien, B.; Lesrel, J.

    1997-02-01

    We have designed a setup to measure the transverse emittance at the CLIO accelerator exit, based on the "3 gradients" method. The beam transverse size is measured simply by scanning it with a steering coil across a fixed jaw and recording the transmitted current, at various quadrupole strengths. A code then performs a complete calculation of the emittance using the transfer matrix of the quadrupole instead of the usual classical lens approximation. We have studied the influence of various parameters on the emittance: Magnetic field on the e-gun and the peak current. We have also improved a little the emittance by replacing a mismatched pipe between the buncher and accelerating section to avoid wake-field effects; The resulting improvements of the emittance have led to an increase in the FEL emitted power.

  19. Highly Effective Auger-Electron Therapy in an Orthotopic Glioblastoma Xenograft Model using Convection-Enhanced Delivery

    PubMed Central

    Thisgaard, Helge; Halle, Bo; Aaberg-Jessen, Charlotte; Olsen, Birgitte Brinkmann; Therkelsen, Anne Sofie Nautrup; Dam, Johan Hygum; Langkjær, Niels; Munthe, Sune; Någren, Kjell; Høilund-Carlsen, Poul Flemming; Kristensen, Bjarne Winther

    2016-01-01

    Glioblastoma, the most common and malignant primary brain tumor, always recurs after standard treatment. Therefore, promising new therapeutic approaches are needed. Short-range Auger-electron-emitters carry the ability of causing highly damaging radiation effects in cells. The aim of this study was to test the effect of [125I]5-Iodo-2'-deoxyuridine (125I-UdR, a radioactive Auger-electron-emitting thymidine analogue) Auger-therapy on immature glioblastoma spheroid cultures and orthotopic xenografted glioblastoma-bearing rats, the latter by means of convection-enhanced delivery (CED). Moreover, we aimed to determine if the therapeutic effect could be enhanced when combining 125I-UdR therapy with the currently used first-line chemotherapeutic agent temozolomide. 125I-UdR significantly decreased glioblastoma cell viability and migration in vitro and the cell viability was further decreased by co-treatment with methotrexate and/or temozolomide. Intratumoral CED of methotrexate and 125I-UdR with and without concomitant systemic temozolomide chemotherapy significantly reduced the tumor burden in orthotopically xenografted glioblastoma-bearing nude rats. Thus, 100% (8/8) of the animals survived the entire observation period of 180 days when subjected to the combined Auger-chemotherapy while 57% (4/7) survived after the Auger-therapy alone. No animals (0/8) treated with temozolomide alone survived longer than 50 days. Blood samples and post-mortem histology showed no signs of dose-limiting adverse effects. In conclusion, the multidrug approach consisting of CED of methotrexate and 125I-UdR with concomitant systemic temozolomide was safe and very effective leading to 100% survival in an orthotopic xenograft glioblastoma model. Therefore, this therapeutic strategy may be a promising option for future glioblastoma therapy. PMID:27924163

  20. 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.

  1. An electron transporting blue emitter for OLED

    NASA Astrophysics Data System (ADS)

    Qi, Boyuan; Luo, Jiaxiu; Li, Suyue; Xiao, Lixin; Sun, Wenfang; Chen, Zhijian; Qu, Bo; Gong, Qihuang

    2010-11-01

    After the premier commercialization of OLED in 1997, OLED has been considered as the candidate for the next generation of flat panel display. In comparison to liquid crystal display (LCD) and plasma display panel (PDP), OLED exhibits promising merits for display, e.g., flexible, printable, micro-buildable and multiple designable. Although many efforts have been made on electroluminescent (EL) materials and devices, obtaining highly efficient and pure blue light is still a great challenge. In order to improve the emission efficiency and purity of the blue emission, a new bipolar blue light emitter, 2,7-di(2,2':6',2"-terpyridine)- 2,7-diethynyl-9,9-dioctyl-9H-fluorene (TPEF), was designed and synthesized. A blue OLED was obtained with the configuration of ITO/PEDOT/PVK:CBP:TPEF/LiF/Al. The device exhibits a turn-on voltage of 9 V and a maximum brightness of 12 cd/m2 at 15 V. The device gives a deep blue emission located at 420 nm with the Commission Internationale de l'Eclairage (CIE) coordinates of (0.17, 0.10). We also use TPEF as electron transporting material in the device of ITO/PPV/TPEF/LiF/Al, the turn-on voltage is 3 V. It is proved the current in the device was enhanced indeed by using the new material.

  2. Innovative energy efficient low-voltage electron beam emitters

    NASA Astrophysics Data System (ADS)

    Felis, Kenneth P.; Avnery, Tovi; Berejka, Anthony J.

    2002-03-01

    Advanced electron beams (AEB) has developed a modular, low voltage (80-125 keV), high beam current (up to 40 ma), electron emitter with typically 25 cm of beam width, that is housed in an evacuated, returnable chamber that is easy to plug in and connect. The latest in nanofabrication enables AEB to use an ultra-thin beam window. The power supply for AEB's emitter is based on solid-state electronics. This combination of features results in a remarkable electrical efficiency. AEB's electron emitter relies on a touch screen, computer control system. With 80 μm of unit density beam penetration, AEB's electron emitter has gained market acceptance in the curing of opaque, pigmented inks and coatings used on flexible substrates, metals and fiber composites and in the curing of adhesives in foil based laminates.

  3. 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.

  4. Recent Developments of Low-emittance Electron Gun for Accelerator

    NASA Astrophysics Data System (ADS)

    Kuriki, Masao

    Recent developments of low-emittance electron guns for accelerator are reviewed. In the accelerator field, DC biased triode thermionic gun (Pierce type gun) has been widely used and is still conventional. On the other hand, because of strong demands on the high brightness electron beam by FEL and other advanced accelerator concepts based on linear accelerator, the low emittance beam generation becomes one of the most important issue in the accelerator science. The R&D effort is “accelerated” by two technological innovations, photo-cathode and RF gun. They made a large improvement on the beam emittance. After the explanations on the technical and physical aspects of the low emittance electron beam generation, advanced electron sources for accelerators are reviewed.

  5. Identification of Auger electron heating and inverse Auger effect in experiments irradiating solids with XUV free electron laser radiation at intensities larger than 1016 W/cm2

    NASA Astrophysics Data System (ADS)

    Rosmej, Frank B.; Petitdemange, Frédérick; Galtier, E.

    2011-09-01

    We present simulations that allow studying Auger heating and the subsequent evolution of the radiation emission of near solid density matter. Particular emphasize is paid to the multi-charge state inverse Auger-effect in dense plasmas which is proposed to explain the target emission when the conduction band at solid density becomes more atomic like as energy is transferred from the electrons to the ions. Simulations are discussed along with the first available experimental data.

  6. 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.

  7. 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.

  8. Biophysical aspects of Auger processes. American Association of Physicists in Medicine symposium proceedings No. 8

    SciTech Connect

    Howell, R.W.; Narra, V.R.; Rao, D.V. . Dept. of Radiology); Sastry, K.S.R. . Dept. of Physics and Astronomy)

    1992-01-01

    The 2nd International Symposium on Biophysical Aspects of Auger Processes was held in July 1991, at the University of Massachusetts. This conference provided a forum for state-of-the-art information regarding the basic mechanisms of action by which Auger processes effect biological damage, as well as the nature of the radiosensitive targets in the cell nucleus. In addition, new insight into the radiotoxicity of Auger processes arising from photon activation of atoms situated in the DNA were presented. Novel approaches to implement agents radiolabeled with Auger electron emitters for cancer therapy were discussed. The information is organized into three sections: Biological effects of photon induced Auger processes; biological effects of Auger-electron emitting radionuclides; and therapeutic applications of Auger electron emitters. Individual papers have been processed separately for inclusion in the appropriate data bases.

  9. 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

    2009-06-05

    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.

  10. 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.

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

    NASA Astrophysics Data System (ADS)

    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.

  12. 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.

  13. Auger electron spectroscopy at high spatial resolution and nA primary beam currents

    NASA Technical Reports Server (NTRS)

    Todd, G.; Poppa, H.; Moorhead, D.; Bales, M.

    1975-01-01

    An experimental Auger microprobe system is described which incorporates a field-emission electron gun and total beam currents in the nanoampere range. The distinguishing characteristics of this system include a large multistation UHV specimen chamber, pulse counting and fully digital Auger signal-processing techniques, and digital referencing methods to eliminate the effects of beam instabilities. Some preliminary results obtained with this system are described, and it is concluded that field-emission electron sources can be used for high-resolution Auger electron spectroscopy with primary-beam spots of less than 100 nm and beam currents of the order of 1 nA.

  14. Auger electron angular distribution of double core-hole states in the molecular reference frame.

    PubMed

    Cryan, James P; Glownia, J M; Andreasson, J; Belkacem, A; Berrah, N; Blaga, C I; Bostedt, C; Bozek, J; Buth, C; DiMauro, L F; Fang, L; Gessner, O; Guehr, M; Hajdu, J; Hertlein, M P; Hoener, M; Kornilov, O; Marangos, J P; March, A M; McFarland, B K; Merdji, H; Petrović, V S; Raman, C; Ray, D; Reis, D; Tarantelli, F; Trigo, M; White, J L; White, W; Young, L; Bucksbaum, P H; Coffee, R N

    2010-08-20

    The Linac Coherent Light Source free electron laser is a source of high brightness x rays, 2×10(11) photons in a ∼5 fs pulse, that can be focused to produce double core vacancies through rapid sequential ionization. This enables double core vacancy Auger electron spectroscopy, an entirely new way to study femtosecond chemical dynamics with Auger electrons that probe the local valence structure of molecules near a specific atomic core. Using 1.1 keV photons for sequential x-ray ionization of impulsively aligned molecular nitrogen, we observed a rich single-site double core vacancy Auger electron spectrum near 413 eV, in good agreement with ab initio calculations, and we measured the corresponding Auger electron angle dependence in the molecular frame.

  15. Auger Electron Angular Distribution of Double Core-Hole States in the Molecular Reference Frame

    NASA Astrophysics Data System (ADS)

    Cryan, James P.; Glownia, J. M.; Andreasson, J.; Belkacem, A.; Berrah, N.; Blaga, C. I.; Bostedt, C.; Bozek, J.; Buth, C.; Dimauro, L. F.; Fang, L.; Gessner, O.; Guehr, M.; Hajdu, J.; Hertlein, M. P.; Hoener, M.; Kornilov, O.; Marangos, J. P.; March, A. M.; McFarland, B. K.; Merdji, H.; Petrović, V. S.; Raman, C.; Ray, D.; Reis, D.; Tarantelli, F.; Trigo, M.; White, J. L.; White, W.; Young, L.; Bucksbaum, P. H.; Coffee, R. N.

    2010-08-01

    The Linac Coherent Light Source free electron laser is a source of high brightness x rays, 2×1011 photons in a ˜5fs pulse, that can be focused to produce double core vacancies through rapid sequential ionization. This enables double core vacancy Auger electron spectroscopy, an entirely new way to study femtosecond chemical dynamics with Auger electrons that probe the local valence structure of molecules near a specific atomic core. Using 1.1 keV photons for sequential x-ray ionization of impulsively aligned molecular nitrogen, we observed a rich single-site double core vacancy Auger electron spectrum near 413 eV, in good agreement with ab initio calculations, and we measured the corresponding Auger electron angle dependence in the molecular frame.

  16. Low-energy Auger electron diffraction: influence of multiple scattering and angular momentum

    NASA Astrophysics Data System (ADS)

    Chassé, A.; Niebergall, L.; Kucherenko, Yu.

    2002-04-01

    The angular dependence of Auger electrons excited from single-crystal surfaces is treated theoretically within a multiple-scattering cluster model taking into account the full Auger transition matrix elements. In particular the model has been used to discuss the influence of multiple scattering and angular momentum of the Auger electron wave on Auger electron diffraction (AED) patterns in the region of low kinetic energies. Theoretical results of AED patterns are shown and discussed in detail for Cu(0 0 1) and Ni(0 0 1) surfaces, respectively. Even though Cu and Ni are very similar in their electronic and scattering properties recently strong differences have been found in AED patterns measured in the low-energy region. It is shown that the differences may be caused to superposition of different electron diffraction effects in an energy-integrated experiment. A good agreement between available experimental and theoretical results has been achieved.

  17. Emittance of a Field Emission Electron Source

    DTIC Science & Technology

    2010-01-05

    mode within the wiggler in order for the laser threshold to be reached. The mode is characterized by a waist radius w and a divergence , the product...the field line red or curved compared to a massive particle trajectory blue or straight. The field lines originate on the surface at s ,zs and...emitter surface s ,zs and along the evalu- ation plane h ,zh. The equivalent sphere characterized by a , is also shown. The red curved line

  18. Auger electron diffraction in thin CoO films on Au(1 1 1)

    NASA Astrophysics Data System (ADS)

    Chassé, A.; Niebergall, L.; Heiler, M.; Neddermeyer, H.; Schindler, K.-M.

    The local structure of thin CoO films grown on a single crystal Au(1 1 1) surface has been studied by Auger electron diffraction (AED). Therefore, the angular dependence of the Auger electron intensity of Co-LMM and O-KLL Auger electrons was recorded in the total half-space above the film. Such 2 π-scans immediately reflect the symmetry of the surface and the local structure of the film. The experimental data are compared to multiple-scattering cluster calculations, where both the influence of multiple-scattering effects and effects of Auger transition matrix elements have been investigated. We have found that the AED patterns of a CoO film in forward-scattering conditions do not always provide straightforward information on the local structure of the film, whereas the multiple-scattering approximation applied gives very good agreement between experimental and theoretical results.

  19. 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.

  20. 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.

  1. Localized Irradiation of Cell Membrane by Auger Electrons Is Cytotoxic Through Oxidative Stress-Mediated Nontargeted Effects.

    PubMed

    Paillas, Salomé; Ladjohounlou, Riad; Lozza, Catherine; Pichard, Alexandre; Boudousq, Vincent; Jarlier, Marta; Sevestre, Samuel; Le Blay, Marion; Deshayes, Emmanuel; Sosabowski, Jane; Chardès, Thierry; Navarro-Teulon, Isabelle; Mairs, Robert J; Pouget, Jean-Pierre

    2016-09-10

    We investigated whether radiation-induced nontargeted effects are involved in the cytotoxic effects of anticell surface monoclonal antibodies labeled with Auger electron emitters, such as iodine 125 (monoclonal antibodies labeled with (125)I [(125)I-mAbs]). We showed that the cytotoxicity of (125)I-mAbs targeting the cell membrane of p53(+/+) HCT116 colon cancer cells is mainly due to nontargeted effects. Targeted and nontargeted cytotoxicities were inhibited in vitro following lipid raft disruption with Methyl-β-cyclodextrin (MBCD) or filipin or use of radical oxygen species scavengers. (125)I-mAb efficacy was associated with acid sphingomyelinase activation and modulated through activation of the AKT, extracellular signal-related kinase ½ (ERK1/2), p38 kinase, c-Jun N-terminal kinase (JNK) signaling pathways, and also of phospholipase C-γ (PLC-γ), proline-rich tyrosine kinase 2 (PYK-2), and paxillin, involved in Ca(2+) fluxes. Moreover, the nontargeted response induced by directing 5-[(125)I]iodo-2'-deoxyuridine to the nucleus was comparable to that of (125)I-mAb against cell surface receptors. In vivo, we found that the statistical significance of tumor growth delay induced by (125)I-mAb was removed after MBCD treatment and observed oxidative DNA damage beyond the expected Auger electron range. These results suggest the involvement of nontargeted effects in vivo also. Low-energy Auger electrons, such as those emitted by (125)I, have a short tissue range and are usually targeted to the nucleus to maximize their cytotoxicity. In this study, we show that targeting the cancer cell surface with (125)I-mAbs produces a lipid raft-mediated nontargeted response that compensates for the inferior efficacy of non-nuclear targeting. Our findings describe the mechanisms involved in the efficacy of (125)I-mAbs targeting the cancer cell surface. Antioxid. Redox Signal. 25, 467-484.

  2. X-ray absorption spectroscopy to determine originating depth of electrons that form an inelastic background of Auger electron spectrum

    NASA Astrophysics Data System (ADS)

    Isomura, Noritake; Cui, Yi-Tao; Murai, Takaaki; Oji, Hiroshi; Kimoto, Yasuji

    2017-07-01

    In Auger electron spectroscopy (AES), the spectral background is mainly due to inelastic scattering of Auger electrons that lose their kinetic energy in a sample bulk. To investigate the spectral components within this background for SiO2(19.3 nm)/Si(100) with known layer thickness, X-ray absorption spectroscopy (XAS) was used in the partial-electron-yield (PEY) mode at several electron kinetic energies to probe the background of the Si KLL Auger peak. The Si K-edge PEY-XAS spectra constituted of both Si and SiO2 components at each kinetic energy, and their component fractions were approximately the same as those derived from the simulated AES background for the same sample structure. The contributions of Auger electrons originating from layers at different depths to the inelastic background could thus be identified experimentally.

  3. Auger contributions to electron impact ionization of Li-like ions

    NASA Astrophysics Data System (ADS)

    Hahn, Yukap

    1980-07-01

    Electron impact ionization by a two-step process of inner-shell excitation followed by an Auger emission is estimated for the Li-like Oxygen and Fe ions. Result for the O 5+ is in good agreement with a recent experiment by Crandall et al. for incident energies above the twice of threshold energy. The Auger cross section is very much reduced in the case of Fe 23+ because of a large fluorescence yield.

  4. Search for multiple-electron emission in Auger transition processes in solids

    NASA Astrophysics Data System (ADS)

    Kalaskar, S.; Hulbert, S. L.; Dong, Q.; Bartynski, B. A.; Weiss, A. H.

    2010-03-01

    We present electron-electron coincidence measurements from Ag(100) taken using a synchrotron radiation photon beam of 465eV energy (which is just above the Ag 3d threshold), with one electron energy analyzer fixed at 175 eV kinetic energy and the other scanned from 150 to 200 eV. The data show a pronounced step at 175 eV consistent with processes in which the energy associated with the filling of the M core hole is shared with two or more correlated electrons that are emitted in an Auger transition accompanied by multiple-electron emission. These results provide direct evidence for the existence of these multiple-electron Auger processes, first posited to explain the origin of the large low energy tail characteristic of Auger spectra from solids.footnotetextE. Jensen, R. A. Bartynski, R. F. Garrett, S. L. Hulbert, E. D. Johnson, and C.-C., Phys. Rev. B 45, 13636 (1992)

  5. A calculation of backscattering factor database for quantitative analysis by Auger electron spectroscopy

    SciTech Connect

    Zeng, R. G.; Ding, Z. J.; Li, Y. G.; Mao, S. F.

    2008-12-01

    A systematic calculation of the backscattering factor in quantitative analysis by Auger electron spectroscopy has been performed for the primary electron beam of energy from the threshold energy of inner-shell ionization to 30 keV at the incident angle of 0 deg. - 89 deg. and for principal Auger transition and Auger electrons emitted from over 28 pure elements at an emission angle of 0 deg. - 89 deg. by using a Monte Carlo simulation method. The calculation employs a general definition of backscattering factor, Casnati's ionization cross section, up-to-date Monte Carlo model of electron scattering, and a large number of electron trajectories to ensure less statistical error. Both the configuration geometry of concentric hemispherical analyzer and the cylindrical mirror analyzer for Auger electron detection are considered in the calculation. The calculated backscattering factors are found to describe very well an experimental dependence of Auger electron intensity on primary energy and on incident angle for Si, Cu, Ag, and W in literature. The calculated numerical values of backscattering factor are stored in an open and online database at http://micro.ustc.edu.cn/BSFDataBase/BFAES.htm.

  6. Nanodiamond composite as a material for cold electron emitters

    NASA Astrophysics Data System (ADS)

    Arkhipov, A. V.; Gordeev, S. K.; Korchagina, S. B.; Sominski, G. G.; Uvarov, A. A.

    2008-03-01

    Characteristics of field-induced electron emission were investigated for one of newly designed all-carbon materials - nanodiamond composite (NDC). The composite is comprised by 4‥6 nm diamond grains covered with 0.2‥1 nm-thick graphite-like shells that merge at grain junctions and determine such properties as mechanical strength and high electric conductivity. Large number of uniformly distributed sp3-sp2 interfaces allowed to expect enhanced electron emission in electric field. Combination of these features makes NDC a promising material for cold electron emitters in various applications. Experimental testing confirmed high efficiency of electron emission from NDC. In comparison with previousely tested forms of nanocarbon, NDC emitters demonstrated better stabily and tolerance to performance conditions. Unusual activation scenarios and thermal dependencies of emission characteristics observed in experiments with NDC can add new background for explanation of facilitated electron emission from nanocarbons with relatively 'smooth' surface morphology.

  7. 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

    2015-01-09

    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.

  8. Calculations of absorbed fractions in small water spheres for low-energy monoenergetic electrons and the Auger-emitting radionuclides (123)Ι and (125)Ι.

    PubMed

    Bousis, Christos; Emfietzoglou, Dimitris; Nikjoo, Hooshang

    2012-12-01

    To calculate the absorbed fraction (AF) of low energy electrons in small tissue-equivalent spherical volumes by Monte Carlo (MC) track structure simulation and assess the influence of phase (liquid water versus density-scaled water vapor) and of the continuous-slowing-down approximation (CSDA) used in semi-analytic calculations. An event-by-event MC code simulating the transport of electrons in both the vapor and liquid phase of water using appropriate electron-water interaction cross sections was used to quantify the energy deposition of low-energy electrons in spherical volumes. Semi-analytic calculations within the CSDA using a convolution integral of the Howell range-energy expressions are also presented for comparison. The AF for spherical volumes of radii from 10-1000 nm are presented for monoenergetic electrons over the energy range 100-10,000 eV and the two Auger-emitting radionuclides (125)I and (123)I. The MC calculated AF for the liquid phase are found to be smaller than those of the (density scaled) gas phase by up to 10-20% for the monoenergetic electrons and 10% for the two Auger-emitters. Differences between the liquid-phase MC results and the semi-analytic CSDA calculations are up to ∼ 55% for the monoenergetic electrons and up to ∼ 35% for the two Auger-emitters. Condensed-phase effects in the inelastic interaction of low-energy electrons with water have a noticeable but relatively small impact on the AF for the energy range and target sizes examined. Depending on the electron energies, the semi-analytic approach may lead to sizeable errors for target sizes with linear dimensions below 1 micron.

  9. Gaseous Ultraviolet-Radiation Source with Electron Emitter

    NASA Astrophysics Data System (ADS)

    Hashiguchi, Seishiro; Tachibana, Kunihide

    2001-03-01

    An ultraviolet (UV) source is proposed. It resembles a dc-type plasma display panel (PDP) but the applied voltage is well below the breakdown voltage and an electron emitter is used. The advantage of the new UV source is that it can reduce energy dissipation due to creation of ions. Numerical calculations with pure xenon show an efficiency of 11% for the applied voltage of 210 V@. The emitter current of 1.3 mA/cm2 was needed to realize an UV-radiation energy equal to that of a conventional PDP@. The efficiency increased with decreasing applied voltage while the emitter current increased to obtain the same amount of UV-radiation energy.

  10. Electron-Electron Interaction in Ion-Atom Collisions Studied by Projectile State-Resolved Auger Electron Spectroscopy.

    NASA Astrophysics Data System (ADS)

    Lee, Do-Hyung

    1990-01-01

    This dissertation addresses the problem of dynamic electron-electron interactions in fast ion-atom collisions using projectile Auger electron spectroscopy. The study was carried out by measuring high-resolution projectile KLL Auger electron spectra as a function of projectile energy for the various collision systems of 0.25-2 MeV/u O^{q+} and F^ {q+} incident on H_2 and He targets. The electrons were detected in the beam direction, where the kinematic broadening is minimized. A zero-degree tandem electron spectrometer system was developed and showed the versatility of zero-degree measurements of collisionally-produced atomic states. The zero-degree binary encounter electrons (BEe), quasifree target electrons ionized by the projectiles in head-on collisions, were observed as a strong background in the KLL Auger electron spectrum. They were studied by treating the target ionization as 180^circ Rutherford elastic scattering in the projectile frame, and resulted in a validity test of the impulse approximation (IA) and a way to determine the spectrometer efficiency. An anomalous q-dependence, in which the zero-degree BEe yields increase with decreasing projectile charge state (q), was observed. State-resolved KLL Auger cross sections were determined by using the BEe normalization and thus the cross sections of the electron -electron interactions such as resonant transfer-excitation (RTE), electron-electron excitation (eeE), and electron -electron ionization (eeI) were determined. Projectile 2l capture with 1s to 2p excitation by the captured target electron was observed as an RTE process with Li-like and He-like projectiles and the measured RTEA (RTE followed by Auger decay) cross sections showed good agreement with an RTE-IA treatment and RTE alignment theory. Projectile 1s to 2p excitation by a target electron was observed an an eeE process with Li-like projectiles. Projectile 1s ionization by a target electron was observed as an eeI process with Be-like projectiles

  11. Monitoring electron-beam irradiation effects on graphenes by temporal Auger electron spectroscopy.

    PubMed

    Xu, Mingsheng; Fujita, Daisuke; Hanagata, Nobutaka

    2010-07-02

    Because of its unique electronic transport properties, graphene has attracted an enormous amount of interest recently. By using standard Auger electron spectroscopy and Raman spectroscopy, we have studied electron-beam irradiation effects on graphene damage. We have shown that irradiation with an electron-beam can selectively remove graphene layers and induce chemical reactions, as well as possible structural transformations. We have also demonstrated the dependence of damage in graphene on electron-beam dose. Our work provides ideas on how to optimize the experimental conditions for graphene characterization and device fabrication. The results throw light on how energy transfer from the electron beam to graphene layers leads to the removal of carbon atoms from graphene layers and on the possibility of using electron-beam irradiation to locally induce chemical reactions in a controlled manner.

  12. Tracking electron-induced carbon contamination and cleaning of Ru surfaces by Auger electron spectroscopy

    SciTech Connect

    Kanjilal, Aloke; Catalfano, Mark; Harilal, Sivanandan S.; Hassanein, Ahmed; Rice, Bryan

    2012-07-15

    Extreme ultraviolet (EUV) radiation induced growth of carbon and oxygen desorption were investigated on a Ru surface by Auger electron spectroscopy (AES) in the presence and absence of additional photoelectrons (PEs) from a focusing Ru mirror. A decrease in EUV reflectivity with carbon growth in the presence of additional PEs has been observed. Conversely, a carbonaceous Ru surface was cleaned in sequential AES, and discussed in terms of secondary electron assisted dissociation of residual hydrocarbons and water molecules, followed by a chemical reaction between adsorbed carbon and oxygen atoms.

  13. 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.

  14. 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.

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

    SciTech Connect

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

    2016-03-15

    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.

  16. 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.

  17. Emittance Measurements from a Laser Driven Electron Injector

    SciTech Connect

    Reis, David A

    2003-07-28

    The Gun Test Facility (GTF) at the Stanford Linear Accelerator Center was constructed to develop an appropriate electron beam suitable for driving a short wavelength free electron laser (FEL) such as the proposed Linac Coherent Light Source (LCLS). For operation at a wavelength of 1.5 {angstrom}, the LCLS requires an electron injector that can produce an electron beam with approximately 1 {pi} mm-mrad normalized rms emittance with at least 1 nC of charge in a 10 ps or shorter bunch. The GTF consists of a photocathode rf gun, emittance-compensation solenoid, 3 m linear accelerator (linac), drive laser, and diagnostics to measure the beam. The rf gun is a symmetrized 1.6 cell, s-band high gradient, room temperature, photocathode structure. Simulations show that this gun when driven by a temporally and spatially shaped drive laser, appropriately focused with the solenoid, and further accelerated in linac can produce a beam that meets the LCLS requirements. This thesis describes the initial characterization of the laser and electron beam at the GTF. A convolved measurement of the relative timing between the laser and the rf phase in the gun shows that the jitter is less than 2.5 ps rms. Emittance measurements of the electron beam at 35 MeV are reported as a function of the (Gaussian) pulse length and transverse profile of the laser as well as the charge of the electron beam at constant phase and gradient in both the gun and linac. At 1 nC the emittance was found to be {approx} 13 {pi} mm-mrad for 5 ps and 8 ps long laser pulses. At 0.5 nC the measured emittance decreased approximately 20% in the 5 ps case and 40% in the 8 ps case. These measurements are between 40-80% higher than simulations for similar experimental conditions. In addition, the thermal emittance of the electron beam was measured to be 0.5 {pi} mm-mrad.

  18. Emittance measurements from a laser-driven electron injector

    NASA Astrophysics Data System (ADS)

    Reis, David A.

    1999-11-01

    The Gun Test Facility (GTF) at the Stanford Linear Accelerator Center was constructed to develop an appropriate electron beam suitable for driving a short wavelength free electron laser (FEL) such as the proposed Linac Coherent Light Source (LCLS). For operation at a wavelength of 1.5 Å, the LCLS requires an electron injector that can produce an electron beam with approximately I π mm-mrad normalized rms emittance with at least 1 nC of charge in a 10 ps or shorter bunch. The GTF consists of a photocathode rf gun, emittance- compensation solenoid, 3 m linear accelerator (linac), drive laser, and diagnostics to measure the beam. The rf gun is a symmetrized 1.6 cell, S-band, high gradient, room temperature, photocathode structure. Simulations show that this gun when driven by a temporally and spatially shaped drive laser, appropriately focused with the solenoid, and further accelerated in linac can produce a beam that meets the LCLS requirements. This thesis describes the initial characterization of the laser and electron beam at the GTF. A convolved measurement of the relative timing between the laser and the rf phase in the gun shows that the jitter is less than 2.5 ps rms. Emittance measurements of the electron beam at 35 MeV are reported as a function of the (Gaussian) pulse length and transverse profile of the laser as well as the charge of the electron beam at constant phase and gradient in both the gun and linac. At 1 nC the emittance was found to be ~13 π mm-mrad for 5 ps, and 8 ps long laser pulses. At 0.5 nC the measured emittance decreased approximately 20% in the 5 ps case and 40% in the 8 ps case. These measurements are between 40-80% higher than simulations for similar experimental conditions. In addition, the thermal emittance of the electron beam was measured to be 0.15 π mm-mrad.

  19. Disentangling atomic-layer-specific x-ray absorption spectra by Auger electron diffraction spectroscopy

    NASA Astrophysics Data System (ADS)

    Matsui, Fumihiko; Matsushita, Tomohiro; Kato, Yukako; Hashimoto, Mie; Daimon, Hiroshi

    2009-11-01

    In order to investigate the electronic and magnetic structures of each atomic layer at subsurface, we have proposed a new method, Auger electron diffraction spectroscopy, which is the combination of x-ray absorption spectroscopy (XAS) and Auger electron diffraction (AED) techniques. We have measured a series of Ni LMM AED patterns of the Ni film grown on Cu(001) surface for various thicknesses. Then we deduced a set of atomic-layer-specific AED patterns in a numerical way. Furthermore, we developed an algorithm to disentangle XANES spectra from different atomic layers using these atomic-layer-specific AED patterns. Surface and subsurface core level shift were determined for each atomic layer.

  20. 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.

  1. Mechanical testing - In situ fracture device for Auger electron spectroscopy

    NASA Technical Reports Server (NTRS)

    Moorhead, R. D.

    1976-01-01

    An in situ fracture device for Auger spectroscopy is 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 are presented. Results indicate that impurity segregation at interfaces other than grain boundary may play a significant role in the mechanism of ductile fracture.

  2. Intrinsic normalized emittance growth in laser-driven electron accelerators

    NASA Astrophysics Data System (ADS)

    Migliorati, M.; Bacci, A.; Benedetti, C.; Chiadroni, E.; Ferrario, M.; Mostacci, A.; Palumbo, L.; Rossi, A. R.; Serafini, L.; Antici, P.

    2013-01-01

    Laser-based electron sources are attracting strong interest from the conventional accelerator community due to their unique characteristics in terms of high initial energy, low emittance, and significant beam current. Extremely strong electric fields (up to hundreds of GV/m) generated in the plasma allow accelerating gradients much higher than in conventional accelerators and set the basis for achieving very high final energies in a compact space. Generating laser-driven high-energy electron beam lines therefore represents an attractive challenge for novel particle accelerators. In this paper we show that laser-driven electrons generated by the nowadays consolidated TW laser systems, when leaving the interaction region, are subject to a very strong, normalized emittance worsening which makes them quickly unusable for any beam transport. Furthermore, due to their intrinsic beam characteristics, controlling and capturing the full beam current can only be achieved improving the source parameters.

  3. 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.

  4. Electron Cloud at Low Emittance in CesrTA

    SciTech Connect

    Alexander, J. P.; Billing, M. G.; Calvey, J.; Crittenden, J. A.; Dugan, G.; Eggert, N.; Forster, M.; Greenwald, S.; Hartill, D. L.; Hopkins, W. H.; Kreinick, D. L.; Li, Y.; Liu, X.; Livezey, J. A.; Meller, R.; Peck, S.; Peterson, D. P.; Rice, D.; Rider, N.; Rubin, D.; Sagan, D.; Schwartz, R.; Shanks, J. P.; Sikora, J.; Harkay, K. C.; Antoniou, F.; Calatroni, S.; Gasior, M.; Papaphilippou, Y.; Pfingstner, J.; Rumolo, G.; Schmickler, H.; Taborelli, M.; Holtzapple, R.; Jones, J.; Wolski, A.; Tan, C.Y.; Zwaska, R. M; Flanagan, J. W.; Kanazawa, K.I.; Sakai, H.; Shibata, K.; Suetsugu, Y.; Byrd, J.; Corlett, J.; De Santis, S.; Furman, M.; Kraft, R.; Munson, D. V.; Penn, G.; Plate, D.; Venturini, M.; Pivi, M. T. F.; Wang, L.; Schachter, L.

    2010-05-23

    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.

  5. 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.

  6. Hydrogen bonding in liquid water probed by resonant Auger-electron spectroscopy.

    PubMed

    Winter, Bernd; Hergenhahn, Uwe; Faubel, Manfred; Björneholm, Olle; Hertel, Ingolf V

    2007-09-07

    We have measured resonant and off-resonant Auger-electron spectra of liquid water. Continuumlike transitions near and above the O1s vertical ionization energy are identified by the characteristic normal Auger-electron spectra. On the contrary, well-resolved spectator shifts of the main Auger-electron peak are observed at the liquid-water O1s absorption main edge and near the absorption pre-edge. The shifts of 1.4 and 1.9 eV arise from the localized nature of the excitation. Excited-state localization/delocalization is also discussed for the analogous vacuum ultraviolet (VUV) transitions, and we point out the similarities between x-ray and VUV absorption spectra of liquid water.

  7. Electron beam emittance monitor for the SSC

    SciTech Connect

    Tsyganov, E.; Meinke, R.; Nexsen, W.; Kauffmann, S.; Zinchenko, A.; Taratin, A.

    1993-05-01

    A nondestructive beam profile monitor for the Superconducting Super Collider (SSC) is presented using as a probe a low-energy electron beam interacting with the proton bunch charge. Results using a full Monte Carlo simulation code look promising for the transverse and longitudinal beam profile measurements.

  8. 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.

  9. Theory of Carbon Nanotube (CNT)-Based Electron Field Emitters

    PubMed Central

    Bocharov, Grigory S.; Eletskii, Alexander V.

    2013-01-01

    Theoretical problems arising in connection with development and operation of electron field emitters on the basis of carbon nanotubes are reviewed. The physical aspects of electron field emission that underlie the unique emission properties of carbon nanotubes (CNTs) are considered. Physical effects and phenomena affecting the emission characteristics of CNT cathodes are analyzed. Effects given particular attention include: the electric field amplification near a CNT tip with taking into account the shape of the tip, the deviation from the vertical orientation of nanotubes and electrical field-induced alignment of those; electric field screening by neighboring nanotubes; statistical spread of the parameters of the individual CNTs comprising the cathode; the thermal effects resulting in degradation of nanotubes during emission. Simultaneous consideration of the above-listed effects permitted the development of the optimization procedure for CNT array in terms of the maximum reachable emission current density. In accordance with this procedure, the optimum inter-tube distance in the array depends on the region of the external voltage applied. The phenomenon of self-misalignment of nanotubes in an array has been predicted and analyzed in terms of the recent experiments performed. A mechanism of degradation of CNT-based electron field emitters has been analyzed consisting of the bombardment of the emitters by ions formed as a result of electron impact ionization of the residual gas molecules.

  10. Theory of Carbon Nanotube (CNT)-Based Electron Field Emitters.

    PubMed

    Bocharov, Grigory S; Eletskii, Alexander V

    2013-07-17

    Theoretical problems arising in connection with development and operation of electron field emitters on the basis of carbon nanotubes are reviewed. The physical aspects of electron field emission that underlie the unique emission properties of carbon nanotubes (CNTs) are considered. Physical effects and phenomena affecting the emission characteristics of CNT cathodes are analyzed. Effects given particular attention include: the electric field amplification near a CNT tip with taking into account the shape of the tip, the deviation from the vertical orientation of nanotubes and electrical field-induced alignment of those; electric field screening by neighboring nanotubes; statistical spread of the parameters of the individual CNTs comprising the cathode; the thermal effects resulting in degradation of nanotubes during emission. Simultaneous consideration of the above-listed effects permitted the development of the optimization procedure for CNT array in terms of the maximum reachable emission current density. In accordance with this procedure, the optimum inter-tube distance in the array depends on the region of the external voltage applied. The phenomenon of self-misalignment of nanotubes in an array has been predicted and analyzed in terms of the recent experiments performed. A mechanism of degradation of CNT-based electron field emitters has been analyzed consisting of the bombardment of the emitters by ions formed as a result of electron impact ionization of the residual gas molecules.

  11. Multi-electron spectroscopy: Auger decays of the argon 2s hole.

    PubMed

    Lablanquie, Pascal; Huttula, Saana-Maija; Huttula, Marko; Andric, Lidija; Palaudoux, Jérôme; Eland, John H D; Hikosaka, Yasumasa; Shigemasa, Eiji; Ito, Kenji; Penent, Francis

    2011-11-07

    Auger decay of an inner shell hole is an efficient way to create multiply charged ions in the gas phase. We illustrate this with the example of the argon 2s decay, and show that multi-electron coincidence spectroscopy between the 2s photoelectron and all released Auger electrons leads to a complete reconstruction of the Ar 2s decay cascade. Spectra of the intermediate and final Ar(n+) states are obtained and are compared with a theoretical model. This journal is © the Owner Societies 2011

  12. Detailed calculation of K- and L-Auger electron emission intensities following radioactive disintegration.

    PubMed

    Bé, Marie-Martine; Chisté, Vanessa; Dulieu, Christophe

    2006-01-01

    A program has been set up to calculate the K- and L-Auger electron emissions resulting from the radioactive disintegration process, and to study all the possible emissions in detail. Due to the fact that only a small number of experimental results are available in the measurements of K- and L-Auger electrons, the calculated values obtained in this work were compared with the other calculated values available. Good agreement was found between the values. Some of the results are given as examples.

  13. 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.

  14. 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.

  15. 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.

  16. Low Emittance Guns for the ILC Polarized Electron Beam

    NASA Astrophysics Data System (ADS)

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

    2007-06-01

    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 ⩾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.

  17. Induction of DNA-double-strand breaks by auger electrons from 99mTc complexes with DNA-binding ligands.

    PubMed

    Häfliger, Pascal; Agorastos, Nikos; Spingler, Bernhard; Georgiev, Oleg; Viola, Giampietro; Alberto, Roger

    2005-02-01

    The potential of certain Auger electron emitting nuclides for systemic radiotherapeutic applications has recently gained much attention. In particular, the ability of several nuclides, including 111In, 125I, and 123I, to induce DNA double-strand breaks (dsb), a good indicator of cytotoxicity, has been extensively studied. However, this ability has never previously been shown experimentally for 99mTc, which, besides the well-known gamma radiation that is used for diagnostic applications, also emits an average of 1.1 conversion electrons and 4 Auger or Coster-Kronig electrons per decay. Owing to the short range of Auger electrons, the radionuclide needs to be located very close to the DNA for dsb to occur. We synthesized two cationic 99mTcI-tricarbonyl complexes with pendant DNA binders, pyrene and anthraquinone. The X-ray crystal structures of the two complexes could be elucidated. Linear dichroism and UV/Vis spectroscopy revealed that the complex with pyrene intercalates DNA with a stability constant, K, of 1.1 x 10(6) M(-1), while the analogous complex with anthraquinone interacts with DNA in a groove-binding mode and has an affinity value of K=8.9 x 10(4) M(-1). We showed with phiX174 double-stranded DNA that the corresponding 99mTc complexes induce a significant amount of dsb, whereas non-DNA-binding [TcO4]- and nonradioactive Re compounds did not. These results indicate that the Auger electron emitter 99mTc can induce dsb in DNA when decaying in its direct vicinity and this implies potential for systemic radiotherapy with 99mTc complexes.

  18. 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.

  19. 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.

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

    PubMed

    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.

  1. Auger electron spectroscopy as a probe of the solution of aqueous ions.

    PubMed

    Pokapanich, Wandared; Bergersen, Henrik; Bradeanu, Ioana L; Marinho, Ricardo R T; Lindblad, Andreas; Legendre, Sebastien; Rosso, Aldana; Svensson, Svante; Björneholm, Olle; Tchaplyguine, Maxim; Ohrwall, Gunnar; Kryzhevoi, Nikolai V; Cederbaum, Lorenz S

    2009-06-03

    Aqueous potassium chloride has been studied by synchrotron-radiation excited core-level photoelectron and Auger electron spectroscopy. In the Auger spectrum of the potassium ion, the main feature comprises the final states where two outer valence holes are localized on potassium. This spectrum exhibits also another feature at a higher kinetic energy which is related to final states where outer valence holes reside on different subunits. Through ab initio calculations for microsolvated clusters, these subunits have been assigned as potassium ions and the surrounding water molecules. The situation is more complicated in the Auger spectrum of the chloride anion. One-center and multicenter final states are present here as well but overlap energetically.

  2. 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.

  3. Positron Annihilation Induced Auger Electron Spectroscopy of Inner Shell Transitions Using Time-Of Technique

    NASA Astrophysics Data System (ADS)

    Xie, Shuping; Jiang, Neng; Weiss, A. H.

    2003-03-01

    Positron annihilation induced Auger electron spectroscopy (PAES) has been shown to have unique advantages over conventional electron collision induced Auger techniques, including the ability to eliminate the secondary electron background and selectively probe the top-most atomic layer on the sample surface. Here we report on the development of a new time-of-flight (TOF) spectrometer which combines features high efficiency magnetic transport and parrallel energy measurment with high resolution by using an innovative timing method. The new TOF-PAES system, was used to make the first quantitative comparative measurements of the Auger intensities associated with the annihilation of positrons with the deep core levels (1s) of S KLL (180eV), C KLL (270eV), N KLL (360eV), and O KLL (510eV). Experimental results of Auger probabilities at outer core level (3s, 3P) of Cu M2,3VV (60eV), M1VV (105eV) are compared with the theoretical value of Jensen and Weiss. Quantitatively study the surface adsorbate process on Cu is performed and concentration changes of surface components are obtained. These results demonstrate that TOF-PAES can be used to obtain quantitative,top-layer specific, information from chemically important elements including those with relatively deep core levels (e.g. C and O).

  4. Dielectronic Satellites and Auger Electron Heating: Irradiation of Solids by Intense XUV-Free Electron Laser Radiation

    NASA Astrophysics Data System (ADS)

    Petitdemange, F.; Rosmej, F. B.

    Auger electron heating of dense matter that is driven by irradiation of solids with intense XUV/X-ray Free Electron Laser radiation permits studying the dielectronic capture channels that are usually closed in standard atomic physics investigations (like, e.g., in accelerators, EBITS, tokamaks, astrophysics). After disintegration of crystalline order dense strongly coupled plasma is formed where dielectronic capture coupled to excited states is identified as the primary population source of autoionizing hole states. We demonstrate that excited states coupling of the inverse Auger effect changes entirely the known picture of dielectronic satellite emission.

  5. Localized Irradiation of Cell Membrane by Auger Electrons Is Cytotoxic Through Oxidative Stress-Mediated Nontargeted Effects

    PubMed Central

    Paillas, Salomé; Ladjohounlou, Riad; Lozza, Catherine; Pichard, Alexandre; Boudousq, Vincent; Jarlier, Marta; Sevestre, Samuel; Le Blay, Marion; Deshayes, Emmanuel; Sosabowski, Jane; Chardès, Thierry; Navarro-Teulon, Isabelle; Mairs, Robert J.

    2016-01-01

    Abstract Aims: We investigated whether radiation-induced nontargeted effects are involved in the cytotoxic effects of anticell surface monoclonal antibodies labeled with Auger electron emitters, such as iodine 125 (monoclonal antibodies labeled with 125I [125I-mAbs]). Results: We showed that the cytotoxicity of 125I-mAbs targeting the cell membrane of p53+/+ HCT116 colon cancer cells is mainly due to nontargeted effects. Targeted and nontargeted cytotoxicities were inhibited in vitro following lipid raft disruption with Methyl-β-cyclodextrin (MBCD) or filipin or use of radical oxygen species scavengers. 125I-mAb efficacy was associated with acid sphingomyelinase activation and modulated through activation of the AKT, extracellular signal-related kinase ½ (ERK1/2), p38 kinase, c-Jun N-terminal kinase (JNK) signaling pathways, and also of phospholipase C-γ (PLC-γ), proline-rich tyrosine kinase 2 (PYK-2), and paxillin, involved in Ca2+ fluxes. Moreover, the nontargeted response induced by directing 5-[(125)I]iodo-2′-deoxyuridine to the nucleus was comparable to that of 125I-mAb against cell surface receptors. In vivo, we found that the statistical significance of tumor growth delay induced by 125I-mAb was removed after MBCD treatment and observed oxidative DNA damage beyond the expected Auger electron range. These results suggest the involvement of nontargeted effects in vivo also. Innovation: Low-energy Auger electrons, such as those emitted by 125I, have a short tissue range and are usually targeted to the nucleus to maximize their cytotoxicity. In this study, we show that targeting the cancer cell surface with 125I-mAbs produces a lipid raft-mediated nontargeted response that compensates for the inferior efficacy of non-nuclear targeting. Conclusion: Our findings describe the mechanisms involved in the efficacy of 125I-mAbs targeting the cancer cell surface. Antioxid. Redox Signal. 25, 467–484. PMID:27224059

  6. Measurements of Auger Electron Diffraction Using a 180° Deflection Toroidal Analyzer

    NASA Astrophysics Data System (ADS)

    Shiraki, Susumu; Ishii, Hideshi; Nihei, Yoshimasa; Owari, Masanori

    A 180° deflection toroidal analyzer is a novel electron spectrometer, which allows the simultaneous registration of the wide range of polar angles in a given azimuth of the sample. Therefore, measurements of photo- and Auger electron intensities over π steradians can be performed rapidly by azimuthal rotation of the sample. Using this analyzer, two-dimensional patterns of electron-beam-excited O KVV and Mg KVV Auger electron diffraction (AED) from a MgO(001) surface were measured in short acquisition times. The AED patterns obtained were compared with theoretical ones calculated by the multiple-scattering scheme. The agreement between experimental and theoretical data was good for both O KVV and Mg KVV transitions.

  7. Development of maskless electron-beam lithography using nc-Si electron-emitter array

    NASA Astrophysics Data System (ADS)

    Kojima, A.; Ikegami, N.; Yoshida, T.; Miyaguchi, H.; Muroyama, M.; Nishino, H.; Yoshida, S.; Sugata, M.; Cakir, S.; Ohyi, H.; Koshida, N.; Esashi, M.

    2013-03-01

    This study demonstrated our prototyped Micro Electro Mechanical System (MEMS) electron emitter which is a nc-Si (nanocrystalline silicon) ballistic electron emitter array integrated with an active-matrix driving LSI for high-speed Massively Parallel Electron Beam Direct Writing (MPEBDW) system. The MPEBDW system consists of the multi-column, and each column provides multi-beam. Each column consists of emitter array, a MEMS condenser lens array, an MEMS anode array, a stigmator, three-stage deflectors to align and to scan the multi beams, and a reduction lens as an objective lens. The emitter array generates 100x100 electron beams with binary patterns. The pattern exposed on a target is stored in one of the duplicate memories in the active matrix LSI. After the emission, each electron beam is condensed into narrow beam in parallel to the axis of electron optics of the system with the condenser lens array. The electrons of the beams are accelerated and pass through the anode array. The stigmator and deflectors make fine adjustments to the position of the beams. The reduction lens in the final stage focuses all parallel beams on the surface of the target wafer. The lens reduces the electron image to 1%-10% in size. Electron source in this system is nc-Si ballistic surface electron emitter. The characteristics of the emitter of 1:1 projection of e-beam have been demonstrated in our previous work. We developed a Crestec Surface Electron emission Lithography (CSEL) for mass production of semiconductor devices. CSEL system is 1:1 electron projection lithography using surface electron emitter. In first report, we confirmed that a test bench of CSEL resolved below 30 nm pattern over 0.2 um square area. Practical resolution of the system is limited by the chromatic aberration. We also demonstrated the CSEL system exposed deep sub-micron pattern over full-field for practical use. As an interim report of our development of MPEBDW system, we evaluated characteristics of the

  8. Evidence for the suppression of incident beam effects in Auger electron diffraction

    NASA Astrophysics Data System (ADS)

    Davoli, I.; Gunnella, R.; Bernardini, R.; De Crescenzi, M.

    1998-01-01

    Auger electron diffraction (AED) of the Cu(100) surface has been studied through the anisotropy of the elastic backdiffused beam electrons, the L 2,3M 4,5M 4,5 (LVV) and the M 2,3M 4,5M 4,5 (MVV) transitions in polar scan along the two main directions [001], [011] and in azimuth scan at normal emission. The intensity anisotropies of the low and high kinetic energy Auger lines are in antiphase to each other as in experiments in which these transitions are excited by X-ray photons. This behaviour has been exploited to single out the origin of the physical mechanisms accompanying the diffraction of the emitted electrons. Incident beam effects appear to be sizeable only when the collection of the AED spectra are made with an angle integrating electron analyser (cylindrical mirror analyser or low electron energy diffraction apparatus), but they appear negligible when electron collection is performed through a small solid-angle detector. The conclusions reached by our measurements are supported by good agreement with experimental and theoretical X-ray photoelectron diffraction data and demonstrate that, when the incident beam energy is sufficiently higher than the kinetic energy of the Auger electron detected, the influence of the incident beam on AED is negligible.

  9. Electron gun using carbon-nanofiber field emitter.

    PubMed

    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<50 microm 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.

  10. Procedure of measuring the longitudinal emittance of electron beam

    NASA Astrophysics Data System (ADS)

    Vladimirov, I. Yu

    2016-09-01

    The procedure of measuring the longitudinal emittance of electron beam generated by RF gun and reconstruction of its longitudinal phase portrait is proposed. Measuring system consists of vertical deflecting RF cavity, horizontal bending dipole and screen. The beam spot on the screen is used to reconstruct the longitudinal phase portrait. In the proposed procedure an electromagnetic field of the vertical deflecting RF cavity can be approximated by the TM110 mode of pillbox cavity. This approximation allows analytically solve the motion equations of the electron motion in the vertical deflecting RF cavity. The report contains description of the vertical deflecting RF cavity and the dipole, the formulae underlying the procedure and the results of numerical simulation.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Deceleration processes of secondary electrons produced by a high-energy Auger electron in a biological context.

    PubMed

    Kai, Takeshi; Yokoya, Akinari; Ukai, Masatoshi; Fujii, Kentaro; Watanabe, Ritsuko

    2016-11-01

    To simulate the deceleration processes of secondary electrons produced by a high-energy Auger electron in water, and particularly to focus on the spatial and temporal distributions of the secondary electron and the collision events (e.g. ionization, electronic excitation, and dissociative electron attachment) that are involved in the multiplication of lesions at sites of DNA damage. We developed a dynamic Monte Carlo code that considers the Coulombic force between an ejected electron and its parent cation produced by the Auger electron in water. Thus our code can simulate some return electrons to the parent cations. Using the code, we calculated to within the order of femtoseconds the temporal evolution of collision events, the mean energy, and the mean traveling distance (including its spatial probability distribution) of the electron at an ejected energy of 20 eV. Some of the decelerating electrons in water in the Coulombic field were attracted to the ionized atoms (cations) by the Coulombic force within hundreds of femtoseconds, although the force did not significantly enhance the number of ionization, electronic excitation, and dissociative electron attachment collision events leading to water radiolysis. The secondary electrons are decelerated in water by the Coulombic force and recombined to the ionized atoms (cations). Furthermore, the some return electrons might be prehydrated in water layer near the parent cation in DNA if the electrons might be emitted from the DNA. The prehydrated electron originated from the return electron might play a significant role in inducing DNA damage.

  16. 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

  17. Auger electron diffraction study of V/Fe(100) interface formation

    NASA Astrophysics Data System (ADS)

    Huttel, Y.; Avila, J.; Asensio, M. C.; Bencok, P.; Richter, C.; Ilakovac, V.; Heckmann, O.; Hricovini, K.

    1998-05-01

    Vanadium atoms present a magnetic moment different to zero when they are part of a thin film deposited on Fe or as a bimetallic Fe-V alloy. The understanding of this phenomenon can only be achieved with a correct structural description of these types of systems. We report an Auger electron diffraction investigation of V films grown on body cubic centred (b.c.c.) Fe(100) substrates. Angular-scanned Auger electron diffraction (AED) patterns of V L 23M 23M 4 (473 eV) and Fe L 3VV (703 eV) show the formation of a well-ordered V/Fe interface even at room temperature. The AED patterns of V films in the range of vanadium submonolayer provide evidence of an isotropic Auger emission, indicating the absence of interdiffusion of V atoms into the Fe substrate and absence of cluster growth of the V film. The annealing of these films up to 400°C does not activate the substitution of the topmost Fe surface layers by V atoms.

  18. Monte Carlo simulation of Auger-electron spectra.

    PubMed

    Grau Carles, A; Kossert, K

    2009-01-01

    A procedure to calculate the complex spectra of electron-capture nuclides which simultaneously eject several electrons and X-rays with different energies is presented. The model is applied to compute spectra of the radionuclides (125)I, (123)I and (111)In. The spectra are then compared with experimental spectra obtained by means of liquid scintillation counting. To this end, the computed spectra were transformed to allow for the nonlinear response function for a liquid scintillator, chemical quenching, as well as the Wallac-type amplifier used for the measurements. The calculated spectra are important for applications of free parameter models in liquid scintillation counting and also for studying the impact of electron-capture nuclides on DNA.

  19. 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.

  20. 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.

  1. 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.

  2. Etching on polar (111) surfaces of CdTe crystals studied with Auger electron spectroscopy

    NASA Astrophysics Data System (ADS)

    Lu, Y.-C.; Stahle, C. M.; Feigelson, R. S.; Morimoto, J.

    1987-12-01

    Several reducing and oxidizing etches were applied to the polar (111) Cd and (111) Te surfaces in CdTe crystals, and Auger electron spectroscopy was used to study the effect of these etches on the surface composition. Auger sputter profiles revealed the effect of the etch below the surface of the samples. Dithionite etch left both surfaces Cd-rich. The surface composition of sulfur increased with increasing etch time and temperature, with a corresponding decrease of Te. Hydrazine etch left the surface composition Cd-to-Te ratio about one-to-one. However, the large oxygen peak was found to increase as the etch time and temperature increased. Hydrogen heat treatment left the surface stoichiometric, free of contamination, and crystalline. The surface offers a good reference for the study of crystallographic polarity and is ideal for device applications.

  3. 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.

  4. 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

  5. Electrical Detection of Quantum Dot Hot Electrons Generated via a Mn(2+)-Enhanced Auger Process.

    PubMed

    Barrows, Charles J; Rinehart, Jeffrey D; Nagaoka, Hirokazu; deQuilettes, Dane W; Salvador, Michael; Chen, Jennifer I L; Ginger, David S; Gamelin, Daniel R

    2017-01-05

    An all-solid-state quantum-dot-based photon-to-current conversion device is demonstrated that selectively detects the generation of hot electrons. Photoexcitation of Mn(2+)-doped CdS quantum dots embedded in the device is followed by efficient picosecond energy transfer to Mn(2+) with a long-lived (millisecond) excited-state lifetime. Electrons injected into the QDs under applied bias then capture this energy via Auger de-excitation, generating hot electrons that possess sufficient energy to escape over a ZnS blocking layer, thereby producing current. This electrically detected hot-electron generation is correlated with a quench in the steady-state Mn(2+) luminescence and the introduction of a new nonradiative excited-state decay process, consistent with electron-dopant Auger cross-relaxation. The device's efficiency at detecting hot-electron generation provides a model platform for the study of hot-electron ionization relevant to the development of novel photodetectors and alternative energy-conversion devices.

  6. 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.

  7. Single-photon laser-enabled auger spectroscopy for measuring attosecond electron-hole dynamics.

    PubMed

    Cooper, Bridgette; Averbukh, Vitali

    2013-08-23

    We propose and simulate a new type of attosecond time-resolved spectroscopy of electron-hole dynamics, applicable particularly to ultrafast hole migration. Attosecond ionization in the inner-valence region is followed by a vacuum ultraviolet probe inducing single-photon laser-enabled Auger decay, a one-photon-two-electron transition filling the inner-valence vacancy. The double ionization probability as a function of the attosecond pump-vacuum ultraviolet probe delay captures efficiently the ultrafast inner-valence hole dynamics. Detailed ab initio calculations are presented for inner-valence hole migration in glycine.

  8. Ion Motion Induced Emittance Growth of Matched Electron Beams in Plasma Wakefields

    DOE PAGES

    An, Weiming; Lu, Wei; Huang, Chengkun; ...

    2017-06-14

    Plasma-based acceleration is being considered as the basis for building a future linear collider. Nonlinear plasma wakefields have ideal properties for accelerating and focusing electron beams. Preservation of the emittance of nano-Coulomb beams with nanometer scale matched spot sizes in these wakefields remains a critical issue due to ion motion caused by their large space charge forces. We use fully resolved quasistatic particle-in-cell simulations of electron beams in hydrogen and lithium plasmas, including when the accelerated beam has different emittances in the two transverse planes. The projected emittance initially grows and rapidly saturates with a maximum emittance growth of lessmore » than 80% in hydrogen and 20% in lithium. The use of overfocused beams is found to dramatically reduce the emittance growth. In conclusion, the underlying physics that leads to the lower than expected emittance growth is elucidated.« less

  9. Ion Motion Induced Emittance Growth of Matched Electron Beams in Plasma Wakefields

    NASA Astrophysics Data System (ADS)

    An, Weiming; Lu, Wei; Huang, Chengkun; Xu, Xinlu; Hogan, Mark J.; Joshi, Chan; Mori, Warren B.

    2017-06-01

    Plasma-based acceleration is being considered as the basis for building a future linear collider. Nonlinear plasma wakefields have ideal properties for accelerating and focusing electron beams. Preservation of the emittance of nano-Coulomb beams with nanometer scale matched spot sizes in these wakefields remains a critical issue due to ion motion caused by their large space charge forces. We use fully resolved quasistatic particle-in-cell simulations of electron beams in hydrogen and lithium plasmas, including when the accelerated beam has different emittances in the two transverse planes. The projected emittance initially grows and rapidly saturates with a maximum emittance growth of less than 80% in hydrogen and 20% in lithium. The use of overfocused beams is found to dramatically reduce the emittance growth. The underlying physics that leads to the lower than expected emittance growth is elucidated.

  10. 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.

  11. The KLM + KLN Auger electron spectrum of rubidium in different matrices

    NASA Astrophysics Data System (ADS)

    Inoyatov, A. Kh; Kovalík, A.; Perevoshchikov, L. L.; Filosofov, D. V.; Vénos, D.; Lee, B. Q.; Ekman, J.; Baimukhanova, A.

    2017-08-01

    The KLM + KLN Auger electron spectrum of rubidium (Z = 37) emitted in the electron capture decay of radioactive 83Sr in a polycrystalline platinum matrix and also 85Sr in polycrystalline platinum and carbon matrices as well as in an evaporated layer onto a carbon backing were experimentally studied in detail for the first time using a combined electrostatic electron spectrometer. Energies, relative intensities, and natural widths of fifteen basic spectrum components were determined and compared with both theoretical predictions and experimental data for krypton (Z = 36). Relative spectrum line energies obtained from the semi-empirical calculations in intermediate coupling scheme were found to agree within 3σ with the measured values while disagreement with experiment exceeding 3σ was often observed for values obtained from our multiconfiguration Dirac-Hartree-Fock calculations. The absolute energy of the dominant spectrum component given by the semi-empirical approach agrees within 1σ with the measured value. Shifts of +(0.2 ± 0.2) and -(1.9 ± 0.2) eV were measured for the dominant KLM spectrum components between the 85Sr sources prepared by vacuum evaporation on and implanted into the carbon foil, respectively, relative to 85Sr implanted into the platinum foil. A value of (713 ± 2) eV was determined for the energy difference of the dominant components of the KLM + KLN Auger electron spectra of rubidium and krypton generated in the polycrystalline platinum matrix. From the detailed analysis of the measured data and available theoretical results, the general conclusion can be drawn that the proper description of the KLM + KLN Auger electron spectrum for Z around 37 should still be based on the intermediate coupling of angular momenta taking into account relativistic effects.

  12. 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.

  13. Theory of Auger-electron and appearance-potential spectroscopy for interacting valence-band electrons

    NASA Astrophysics Data System (ADS)

    Nolting, W.; Geipel, G.; Ertl, K.

    1991-12-01

    A theory of Auger-electron spectroscopy (AES) and appearance-potential spectroscopy (APS) is presented for interacting electrons in a nondegenerate energy band, described within the framework of the Hubbard model. Both types of spectroscopy are based on the same two-particle spectral density. A diagrammatic vertex-correction method (Matsubara formalism) is used to express this function in terms of the one-particle spectral density. The latter is approximately determined for arbitrary temperature T, arbitrary coupling strength U/W (U, the intra-atomic Coulomb matrix element; W, the width of the ``free'' Bloch band), and arbitrary band occupations n (0<=n<=2 average number of band electrons per site) by a self-consistent moment method. In weakly coupled systems the electron correlations give rise to certain deformations of the quasiparticle density of states (QDOS) in relation to the Bloch density of states (BDOS), where, however, spontaneous magnetic order is excluded, irrespective of the band filling n. The AE (AP) spectra consist of only one structure a few eV wide (``bandlike'') which is strongly n dependent, but only slightly T dependent, being rather well approximated by a simple self-convolution of the occupied (unoccupied) QDOS. For strongly correlated electrons the Bloch band splits into two quasiparticle subbands. This leads for n<1 to one line in the AE spectrum and three lines in the AP spectrum, and vice versa for n>1. For sufficiently strong correlations U/W additional satellites appear that refer to situations where the two excited quasiparticles (quasiholes) propagate as tightly bound pairs through the lattice without being scattered by other charge carriers. As soon as the satellite splits off from the bandlike part of the spectrum, it takes almost the full spectral weight, conveying the impression of an ``atomiclike'' AE (AP) line shape. The satellite has almost exactly the structure of the free BDOS. If the particle density n as well as the hole

  14. Localization of electrons in the sugar/phosphate backbone in DNA investigated via resonant Auger decay spectra

    SciTech Connect

    Baba, Yuji; Sekiguchi, Tetsuhiro; Shimoyama, Iwao; Hirao, Norie; Nath, Krishna G.

    2006-11-15

    In order to elucidate the localized nature of electrons in sugar/phosphate backbone in DNA molecules, resonant Auger decay spectra excited by soft x-rays around the inner-shell ionization thresholds have been measured for single-strand DNA. The systems investigated are thin films of DNA as well as related phosphorus compounds such as nucleotide (adenosine triphosphate, ATP), sodium phosphate, and indium phosphide. For ATP and DNA, it was observed that the resonant excitations from P 1s to valence unoccupied {pi}* orbitals are followed by spectator-type Auger decays where the excited electrons remain in valence orbitals during the core-hole decays. It was also found that the energy of the P KL{sub 2,3}L{sub 2,3} (2p{sup -1}{center_dot}{pi}*) spectator Auger peak shifts linearly with the photon energy due to the resonant Auger Raman scattering. Most of the decay channel at the core-to-valence resonant excitation is spectator-type Auger decay in DNA, which is quite different from the Auger decay processes in metallic and semiconducting materials. We conclude that the excited electrons in valence unoccupied states around the phosphates in DNA molecules are strongly localized, resulting in the insulating properties in a one-dimensional direction along sugar/phosphate backbone.

  15. 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.

  16. 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.).

  17. Electron correlation during the Auger cascade of potassium and argon after K-shell photoexcitation

    NASA Astrophysics Data System (ADS)

    Hertlein, Marcus; Adaniya, Hidehito; Cole, Kyra; Feinberg, Benedict; Maddi, Jason; Prior, Michael; Schriel, Ralf; Belkacem, Ali

    2004-05-01

    We have measured and analyzed the charge state distributions of argon and potassium after ionization by photons with energies near the K-shell ionization threshold. Despite the similarity in core electron configurations, after Auger decay of the core hole the two atoms show remarkable differences in the resulting distribution of ion charge states, since the presence of the additional 4s valence electron in potassium and its correlation with the photoelectron generated by the K-shell excitation can lead to excitation and ionization pathways not available in argon. Our data indicate that the presence of the 4s electron almost completely suppresses the postcollision interaction (PCI) effect in potassium, and enables multiple electron excitations close to the ionization threshold. Compared to argon, potassium has a significantly larger probability of losing an additional valence electron during through correlation effects during the decay of a K-shell hole. In potassium, the differences in the ionization dynamics manifest themselves in a higher average charge state below the ionization edge, while several tens of eV above edge the average charge states of the two atoms remains almost identical. Additionally, the remarkable differences in the singly charged ion yield give clear indications of additional ionization channels through shakeup and correlation ionization, shedding some light on the time dynamics during Auger decay.

  18. Radiolabeling and in vitro evaluation of (67)Ga-NOTA-modular nanotransporter--a potential Auger electron emitting EGFR-targeted radiotherapeutic.

    PubMed

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

    2014-07-01

    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 (67)Ga. EGF was the targeting ligand on the MNT, and NOTA was selected for its radiolabeling with (67)Ga. In the radiolabeling study we dealt with the precipitation of MNT (pI 5.7) at the labeling pH (4.5-5.5) of (67)Ga. Cellular and nuclei uptake of (67)Ga-NOTA-MNT by the A431 cell line was determined. Its specific cytotoxicity was compared to that of (67)Ga-EDTA, (67)Ga-NOTA-BSA and (67)Ga-NOTA-hEGF, in A431 and U87MGWTT, cell lines, by clonogenic assay. Dosimetry studies were also performed. (67)Ga-NOTA-MNT was produced with 90% yield and specific activity of 25.6mCi/mg. The in vitro kinetics revealed an increased uptake over 24h. 55% of the internalized radioactivity was detected in the nuclei at 1h. The cytotoxicity of (67)Ga-NOTA-MNT on A431 cell line was 17 and 385-fold higher when compared to non-specific (67)Ga-NOTA-BSA and (67)Ga-EDTA. While its cytotoxic potency was 13 and 72-fold higher when compared to (67)Ga-NOTA-hEGF in the A431 and the U87MGWTT cell lines, respectively, validating its nuclear localization. The absorbed dose, for 63% cell killing, was 8Gy, confirming the high specific index of (67)Ga. These results demonstrate the feasibility of using MNT as a platform for single cell kill targeted radiotherapy by Auger electron emitters. Copyright © 2014 Elsevier Inc. All rights reserved.

  19. 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

  20. Electronic Properties of Gallium Arsenide Surfaces as Characterized by Inverse Photoemission and Auger Photoelectron Coincidence Spectroscopy.

    NASA Astrophysics Data System (ADS)

    Garrison, Karl Claudius

    The unoccupied electronic band structure of GaAs(100) has been probed using k-resolved inverse photoemission spectroscopy (KRIPES). The use of As-capped MBE-grown GaAs(100) surface has enabled us to obtain well-ordered surfaces that exhibit reconstructions characteristic of both the As-terminated (2 x 4) and the Ga-terminated (4 x 2) GaAs(100) surfaces. By studying the electronic structure of two different surface reconstructions on the same bulk semiconductor, we have been able to correlate the electronic structure of GaAs(100) with its geometric structure. In particular, we have detected a surface state at ~1.6 eV above the Fermi level that disperses with the incident electron angle. This state has been associated with the empty Ga-dangling bond and is only seen on the Ga-terminated (4 x 2) surface of GaAs(100). The energy of this state, however, is significantly higher than predicted by total energy DOS calculations. This discrepancy has been associated with quasiparticle excitations not included in the calculations. Using Auger photoelectron coincidence spectroscopy (APECS), we have also studied the core-valence-valance (CVV) Auger decay process for the GaAs(110) surface. APECS enables us to independently separate the Ga-derived and As-derived Auger spectra and to clearly resolve the s-s and s-p Auger contributions. This has led to the discovery of surface-specific electron correlation effects, which have been directly observed for the first time in this study. In addition, we have also investigated the growth of a new class of metallic overlayers on III-V semiconductors: thermally stable, epitaxial, single crystal metallic compound growth on MBE-grown GaAs(100). In particular, we have grown CoGa and ErAs metallic thin films on GaAs(100) and have investigated their properties using a variety of techniques to study the quality of the thin films both during and after growth. Our studies have shown both compounds form good quality single crystals when grown on an

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

    NASA Astrophysics Data System (ADS)

    Kleifges, M.; Pierre Auger Collaboration

    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.

  2. Production and dosimetric aspects of the potent Auger emitter {sup 58m}Co for targeted radionuclide therapy of small tumors

    SciTech Connect

    Thisgaard, H.; Elema, D.R.; Jensen, M.

    2011-08-15

    Purpose: Based on theoretical calculations, the Auger emitter {sup 58m}Co has been identified as a potent nuclide for targeted radionuclide therapy of small tumors. During the production of this isotope, the coproduction of the long-lived ground state {sup 58g}Co is unfortunately unavoidable, as is ingrowth of the ground state following the isomeric decay of {sup 58m}Co. The impact of {sup 58g}Co as a {beta}{sup +}- and {gamma}-emitting impurity should be included in the dosimetric analysis. The purpose of this study was to investigate this critical part of dosimetry based on experimentally determined production yields of {sup 58m}Co and {sup 58g}Co using a low-energy cyclotron. Also, the cellular S-values for {sup 58m}Co have been calculated and are presented here for the first time. Methods: {sup 58m}Co was produced via the {sup 58}Fe(p,n){sup 58m}Co nuclear reaction on highly enriched {sup 58}Fe metal. In addition, radiochemical separations of produced radio-cobalt from {sup nat}Fe target material were performed. The theoretical subcellular dosimetry calculations for {sup 58m}Co and {sup 58g}Co were performed using the MIRD formalism, and the impact of the increasing ground state impurity on the tumor-to-normal-tissue dose ratios (TND) per disintegration as a function of time after end of bombardment (EOB) was calculated. Results: 192 {+-} 8 MBq of {sup 58m}Co was produced in the irradiation corresponding to a production yield of 10.7 MBq/{mu}Ah. The activity of {sup 58g}Co was measured to be 0.85% {+-} 0.04% of the produced {sup 58m}Co activity at EOB. The radio-cobalt yields in the rapid separations were measured to be >97% with no detectable iron contaminations in the cobalt fractions. Due to the unavoidable coproduction and ingrowth of the long-lived ground state {sup 58g}Co, the TND and the potency of the {sup 58m}Co decrease with time after EOB. If a future treatment with a {sup 58m}Co labeled compound is not initiated before, e.g., 21 h after EOB, the

  3. Generation of low-emittance electron beams in electrostatic accelerators for FEL applications

    NASA Astrophysics Data System (ADS)

    Teng, Chen; Elias, Luis R.

    1995-02-01

    This paper reports results of transverse emittance studies and beam propagation in electrostatic accelerators for free electron laser applications. In particular, we discuss emittance growth analysis of a low current electron beam system consisting of a miniature thermoionic electron gun and a National Electrostatics Accelerator (NEC) tube. The emittance growth phenomenon is discussed in terms of thermal effects in the electron gun cathode and aberrations produced by field gradient changes occurring inside the electron gun and throughout the accelerator tube. A method of reducing aberrations using a magnetic solenoidal field is described. Analysis of electron beam emittance was done with the EGUN code. Beam propagation along the accelerator tube was studied using a cylindrically symmetric beam envelope equation that included beam self-fields and the external accelerator fields which were derived from POISSON simulations.

  4. X-ray photoelectron and X-ray Auger electron spectroscopy studies of heavy ion irradiated C 60 films

    NASA Astrophysics Data System (ADS)

    Kumar, Amit; Singh, F.; Govind; Shivaprasad, S. M.; Avasthi, D. K.; Pivin, J. C.

    2008-09-01

    The influence of 200 MeV Au ion irradiation on the surface properties of polycrystalline fullerene films has been investigated. The X-ray photoelectron and X-ray Auger electron spectroscopies are employed to study the ion-induced modification of the fullerene, near the surface region. The shift of C 1s core level and decrease in intensity of shake-up satellite were used to investigate the structural changes (like sp 2 to sp 3 conversion) and reduction of π electrons, respectively, under heavy ion irradiation. Further, X-ray Auger electron spectroscopy was employed to investigate hybridization conversion qualitatively as a function of ion fluence.

  5. 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.

  6. 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.

  7. A Smart Microwave Vacuum Electron Device (MVED) Using Field Emitters

    DTIC Science & Technology

    2012-01-31

    Stellar Lateral Emitters The original program was based on receiving lateral, nano -layer carbon emitters from Stellar Micro Devices (SMD). Stellar...Leakage current in the cathodes have been a very large problem. With an increased leakage both the heat of the cathode and voltage drop across...perfom1ance. The tleld emission arrays intended for the experiment did not meet specifications, so alternative field emission cathodes were used. While these

  8. Quantifying the effect of fracture surface topography on the scattering of grain boundary segregation measurement by Auger electron spectroscopy

    SciTech Connect

    Christien, F.; Borjon-Piron, Y.; Le Gall, R.; Saillet, S.

    2010-01-15

    The aim of this paper is to estimate the effect of the geometrical orientation of grain boundary facets on the quantification of grain boundary segregation by Auger electron spectroscopy (AES) on an in-situ fractured surface. Phosphorus grain boundary segregation (PGBS) was studied on 17 different samples (including 3 different steels and 12 different thermal treatments) using a MAC2 analyzer from Riber company. For each sample, 14 to 41 grain boundary facets were analyzed. It is demonstrated that there is proportionality between the PGBS mean value and the PGBS standard deviation obtained on one particular sample: for each sample, the PGBS standard deviation represents approximately 40% of the PGBS mean value. The topography of a typical purely intergranular fracture surface was determined by 3D stereographic observation in a SEM. The influence of surface topography on Auger quantification was then evaluated using the Auger quantification equations. The orientation of grain boundary facets with respect to the primary beam and the Auger analyzer was taken into account. The result is that, considering a homogeneous PGBS on all the grain boundary facets, a large scattering ({approx} 45%) of the PGBS quantification by AES can be accounted for by a purely geometrical effect (orientation of each facet with respect to the primary beam and to the Auger analyzer). This geometrical effect is nevertheless strongly dependant on the spectrometer geometry (respective position of primary beam, sample and Auger analyzer with respect to each other) and could be reduced by optimizing the relative positions of primary beam, sample and Auger analyzer. The topographical analysis was extended to the case of the well-known CMA (Cylindrical Mirror Analyzer). The scattering of the PGBS measurements with Auger spectrometers fitted with a CMA perpendicular to the fracture surface is expected to be much smaller.

  9. Transverse emittance preservation during bunch compression in the Fermi free electron laser

    NASA Astrophysics Data System (ADS)

    di Mitri, S.; Allaria, E. M.; Craievich, P.; Fawley, W.; Giannessi, L.; Lutman, A.; Penco, G.; Spampinati, S.; Trovo, M.

    2012-02-01

    A characterization of the transverse emittance of a 200 pC, 6 ps long electron bunch has been performed in the Fermi@Elettra Free Electron Laser (FEL) first bunch compressor area. This region includes a magnetic bunch length compressor, diagnostics, and quadrupole magnets. The beam is time compressed in one stage, without linearization of the longitudinal phase space. Some growth of the normalized emittance has been measured in the compressor area. To understand this effect, we have investigated mechanisms of emittance growth such as coherent synchrotron radiation emission, chromatic aberration, and spurious dispersion. We show that careful optics control inside the compressor is essential for emittance growth reduction. The final configuration of one-stage magnetic compression limits the emittance to values below the design goal of 2 mm mrad, up to a compression factor of about 5. This machine configuration has been adopted to optimize FEL radiation output at wavelengths in the range 30-60 nm.

  10. Reduction of Intrinsic Electron Emittance from Photocathodes Using Ordered Crystalline Surfaces.

    PubMed

    Karkare, Siddharth; Feng, Jun; Chen, Xumin; Wan, Weishi; Palomares, F Javier; Chiang, T-C; Padmore, Howard A

    2017-04-21

    The generation of intense electron beams with low emittance is key to both the production of coherent x rays from free electron lasers, and electron pulses with large transverse coherence length used in ultrafast electron diffraction. These beams are generated today by photoemission from disordered polycrystalline surfaces. We show that the use of single crystal surfaces with appropriate electronic structures allows us to effectively utilize the physics of photoemission to generate highly directed electron emission, thus reducing the emittance of the electron beam being generated.

  11. 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.

  12. Auger Electrons via Kα X-Ray Lines of Platinum Compounds for Nanotechnological Applications

    NASA Astrophysics Data System (ADS)

    Nahar, Sultana N.; Lim, Sara; Pradhan, A. K.; Pitzer, R. M.

    2011-06-01

    We will report study on the Kα X-ray lines of platinum. Pt compounds, such as cisplatin, are common in biomedical applications. The active element Pt can emit or absorb hard X-rays. We have obtained the photoionization cross sections from the oscillator strengths of 1s-2p (Kα) transitions in Pt ions. We find that these transitions appear as resonances in photoionization in the hard X-ray energy range of 64 - 71 keV (0.18 - 0.17 Å) below the K-shell ionization and with a strength orders of magnitude higher compared to that at the K-shell ionization. This is the focus of our study for possible initiation of an emission cascade of Auger electrons at the resonant energy. We will present the oscillator strengths and attenuation coefficients per unit mass for all the Kα transitions in the event platinum cascades through various, namely from fluorine-like to hydrogen like, ionic states. The study is motivated by uur proposed method, Resonant Theranosticsb,C (RT) for biomedical appliations, which aims to find narrow band X-ray energy that corresponds to resonant photo-absorption and leads to emission of Auger electrons. As the next step of the RT method we will also report on experimental results on producing monochromatic X-rays, targeted to the resonant energy, from the wide band Bremstruhlung radiation of a conventional X-ray source. Partially support: DOE, Computational Facility: Ohio Supercomputer Center, Columbus, Ohio. "Resonant X-Ray Enhancement of the Auger Effect in High-Z atoms, molecules, and Nanoparticles: Biomedical Applications", A.K. Pradhan, S.N. Nahar, M. Montenegro, Yan Yu, H.L. Zhang, C. Sur, M. Mrozik, R.M. Pitzer, J. of Phys. Chem. A, 113 (2009), 12356. "Monte Carlo Simulations and Atomic Calculations for Auger Processes in Biomedical Nanotheranostics", M. Montenegro, S. N. Nahar, A. K. Pradhan, Ke Huang, Yan Yu, J. of Phys. Chem. A, 113 (2009), 12364.

  13. Production of no carrier added 80mBr for investigation of Auger electron toxicity.

    PubMed

    Mease, R C; DeJesus, O T; Gatley, S J; Harper, P V; Desombre, E R; Friedman, A M

    1991-01-01

    80mBr (half-life = 4.43 h) is an Auger electron emitting nuclide with convenient properties for investigating Auger electron cytotoxicity and with potential for labeling in vivo radiotherapeutic agents. We have investigated three cyclotron target systems capable of generating 80mBr of sufficiently high specific radioactivity (no carrier added) for biomedical experiments. A 83Kr gas target irradiated with 21.5 MeV deuterons made 80mBr at a production yield of 1.6 +/- 0.2 mCi/muAh at saturation. A five-fold increase in 80mBr yield was obtained from 15 MeV proton irradiation of thin elemental Se enriched in 80Se targets although technical improvements are expected to further raise this production yield. This route is therefore superior for current medical cyclotrons. Irradiation of a reusable 80Se copper selenide target also yielded multi-millicurie amounts of 80mBr, and recovery of radiobromine by dry distillation is faster and more convenient than in the elemental Se target, but an optimum copper selenide target for 80mBr production has not yet been built.

  14. 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.

  15. Shake-off of loosely bound electrons in Auger decays of Kr 2p core hole states

    SciTech Connect

    Morishita, Y.; Suzuki, I.H.; Ibuki, T.

    2005-10-15

    Multicharged Kr ions have been measured using monochromatized undulator radiation combined with a coincidence technique. It has been found that a charge-state distribution of Kr ions being coincident with satellite peaks of Kr 2p{sub 3/2} photoelectron is slightly different from that for the main line. Resonant Auger peaks for 2p{sup -1}nl{yields}{sup 1}G{sub 4} nl transitions generated essentially Kr{sup 4+} only, which differs from the charge-state distribution for the normal Auger peak. These findings suggest that loosely bound electrons in high Rydberg orbitals are easily shaken-off in electron emission processes.

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

    SciTech Connect

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

    2016-08-15

    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.

  17. 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.

  18. Proposal for using optical transition radiation for electron beam alignment and emittance measurement for the free emittance measurement for the free electron laser experiments at ATF

    SciTech Connect

    Qiu, Xu Z.; Wang, Xijie; Ben-Zvi, I.

    1994-10-01

    Optical transiton radiation (OTR) produced from thin intercepting foils have been employed to image the spatial profile of the electron beam in several free electron laser experiments. It was found that the images from OTR were significantly sharper than the images produced from phosphor screens. Furthermore, OTR`s sensitivity of its angular distribution and polarization to energy and divergence of the electron beam was exploited to diagnose energy and emittance of the electron beam. OTR has been proven to be vital in electron beam alignment in FEL experiments. This report gives a summary of the basic theory of transition radiation and techniques using transition radiation for electron beam imaging and emittance measurement. The possibility was explored for employing these techniques in the HGHG FEL and the visible FEL experiments in ATF (Accelerator Test Facility).

  19. Direct mapping of Li distribution in electrochemically lithiated graphite anodes using scanning Auger electron microscopy

    NASA Astrophysics Data System (ADS)

    Ishida, Nobuyuki; Fukumitsu, Hitoshi; Kimura, Hiroshi; Fujita, Daisuke

    2014-02-01

    The spatial distribution of Li ions in electrochemically lithiated graphite anodes for Li-ion battery is characterized by scanning Auger electron microscopy. We show that direct mapping of Li KVV peak intensity reveal the spatial distribution of intercalated Li and its chemical state in a quantitative manner. Furthermore, we demonstrate that mapping using a C KVV peak also reflects the spatial distribution of Li due to the change in the electronic properties of C atoms induced by the electrode reaction (Li intercalation). Mapping measurements on three samples with different charging states (20%, 50%, and 100%) show that at the early stage of charging Li ions do not intercalate homogenously into all the graphite particles but selectively into some specific ones with higher rates. Our method provides the criteria to evaluate structure-correlated Li intercalation from nanometer- to micrometer-scale, such as conductivity network in the electrodes due to a non-uniform morphology of binder and conductive additives.

  20. Auger electron spectroscopy: a rational method for determining thickness of graphene films.

    PubMed

    Xu, Mingsheng; Fujita, Daisuke; Gao, Jianhua; Hanagata, Nobutaka

    2010-05-25

    We report the determination of the thickness of graphene layers by Auger electron spectroscopy (AES). We measure AES spectra of graphenes with different numbers of layers. The AES spectroscopy shows distinct spectrum shape, intensity, and energy characteristics with an increasing number of graphene layers. We also calculate electron inelastic mean free paths for graphene layers directly from these measurements. The method allows unambiguous and high-throughput determination of thickness up to six graphene layers and detection of defect and dopant in graphene films on almost any substrate. The availability of this reliable method will permit direct probing of graphene growth mechanisms and exploration of novel properties of graphenes with different thicknesses on diverse substrates.

  1. Auger electron diffraction study of the growth of Fe(001) films on ZnSe(001)

    NASA Astrophysics Data System (ADS)

    Jonker, B. T.; Prinz, G. A.

    1991-03-01

    The growth of Fe films on ZnSe(001) epilayers and bulk GaAs(001) substrates has been studied to determine the mode of film growth, the formation of the interface, and the structure of the overlayer at the 1-10 monolayer level. Auger electron diffraction (AED), x-ray photoelectron spectroscopy (XPS), and reflection high-energy electron diffraction data are obtained for incremental deposition of the Fe(001) overlayer. The coverage dependence of the AED forward scattering peaks reveals a predominantly layer-by-layer mode of film growth at 175 °C on ZnSe, while a more three-dimensional growth mode occurs on the oxide-desorbed GaAs(001) substrate. XPS studies of the semiconductor 3d levels indicate that the Fe/ZnSe interface is less reactive than the Fe/GaAs interface.

  2. 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.

  3. 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 ≃ 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.

  4. Resonant Transfer Excitation Followed by Auger-Electron Emission for Ne-like Ions

    SciTech Connect

    Omar, G.; Moussa, Ali H.; Ramadan, H.

    2005-03-17

    In ion-atom (I/A) collision, resonant transfer excitation followed by Auger emission (RTEA) is a complementary process to resonant transfer excitation followed by X-rays (RTEX). In both processes positive ions are assumed to collide with molecular H2-target or atomic He-targets. RTEA and RTEX are related to the resonance excitation (RE) and dielectronic recombination (DR) in electron-ion collisions. The cross sections of RTEA and RE are related under the validity of the conditions of impulse approximation, in which the ionic projectiles must move with very high velocity. RTEA are calculated for Ne-like ions with L-shell excitation. The database generated for Auger and radiative decay rates in LS coupling scheme. RTEA processes proceed through formation of resonance R states. These R-states have a general form 2p5n1 l 1n2 l 2 ; n1 = 3, 4 and n2 {>=} 4. It is found that RTEA cross sections exhibit a one-peak behavior with a peak value 1.6 x 10-18 cm2 when it collides with H2 as a target. This peak value decreases to 0.488x10-18 cm2 in case of Se24+.

  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. 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.

  7. Evaluation of DNA damage induced by Auger electrons from (137)Cs.

    PubMed

    Watanabe, Ritsuko; Hattori, Yuya; Kai, Takeshi

    2016-11-01

    To understand the biological effect of external and internal exposure from (137)Cs, DNA damage spectrum induced by directly emitted electrons (γ-rays, internal conversion electrons, Auger electrons) from (137)Cs was compared with that induced by (137)Cs γ-rays. Monte Carlo track simulation method was used to calculate the microscopic energy deposition pattern in liquid water. Simulation was performed for the two simple target systems in microscale. Radiation sources were placed inside for one system and outside for another system. To simulate the energy deposition by directly emitted electrons from (137)Cs placed inside the system, the multiple ejections of electrons after internal conversion were considered. In the target systems, induction process of DNA damage was modeled and simulated for both direct energy deposition and the water radical reaction on the DNA. The yield and spatial distribution of simple and complex DNA damage including strand breaks and base lesions were calculated for irradiation by electrons and γ-rays from (137)Cs. The simulation showed that the significant difference in DNA damage spectrum was not caused by directly ejected electrons and γ-rays from (137)Cs. The result supports the existing perception that the biological effects by internal and external exposure by (137)Cs are equivalent.

  8. 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

  9. 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.

  10. Emittance studies at the Los Alamos National Laboratory Free-Electron Laser (FEL)

    NASA Astrophysics Data System (ADS)

    Carlsten, B. E.; Feldman, D. W.; Lumpkin, A. H.; Stein, W. E.; Warren, R. W.

    Recent emittance studies at the Los Alamos Free-Electron Laser (FEL) have indicated several areas of concern in the linac and beamline feeding the wiggler. Four emittance growth mechanisms of special importance have been studied. First, a rapid growth of the electron beam's emittance immediately after the spherical gridded Pierce gun resulted, in part, from the long time required for our pulsing electronics to ramp the grid voltage up at the start and down at the end of the pulse, which created a pulse with a cosine-like current distribution as a function of time. The growth was compounded by the extremely small radial beam size (almost a waist) leaving the gun. In addition, we saw evidence of electrostatic charging of the insulators in the gun, reducing the quality of the electron beam further. Second, the action of the solenoidal focusing fields in the low-voltage bunching region was studied, and criteria for a minimum emittance growth were established. Third, maximum misalignment angles and displacements for various elements of the beamline were calculated for the desired low emittance growth. Finally, emittance growth in the horizontal dimension through the nonisochronous bend caused by varying energy depression on the particles due to longitudinal wake fields was both calculated and observed. In addition, we measured energy depressions caused by the wake fields generated by various other elements in the beamline. Strategies were developed to relieve the magnitude of these wake-field effects.

  11. 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.

  12. Application of a Novel Multiple-Scattering Approach to Photoelectron Diffraction and Auger Electron Diffraction.

    NASA Astrophysics Data System (ADS)

    Kaduwela, Ajith P.

    We apply a new separable-Green's-function matrix method due to Rehr and Albers (Phys. Rev. B4l (1990) 8139) to a multiple scattering treatment of photoelectron diffraction and Auger electron diffraction. This cluster -based method permits building up successive orders of scattering and judging the approach to convergence in a convenient and time-saving way. We include multiple scattering up to tenth order and can treat photoelectron emission form any initial state (s, p, d, or f) with full final-state interference. This new approach is used to simulate emission from linear and bent chains of atoms, from epitaxial overlayers and multilayer substrates and from atomic and molecular adsorbates, and various conclusions are drawn concerning the range of utility of the method and the geometric structures for which multiple scattering effects must be considered.

  13. Surface enrichment in hot-dipped metallic coatings investigated by Auger electron spectroscopy

    NASA Astrophysics Data System (ADS)

    Payling, R.; Mercer, P. D.

    1985-05-01

    The treatment, appearance, and corrosion resistance of metallic coatings are largely governed by the chemical composition of the surface. Auger electron spectroscopy shows that the surfaces of hot-dipped metallic coatings differ markedly from the bulk compositions of the coatings. For example, the surfaces of terne coatings, lead-tin alloys, contain little lead. The conventional galvanized coating, which is more than 99% zinc, has a predominantly aluminium oxide surface. Typical surface compositions of a range of hot-dipped metallic coatings are provided. A qualitative prediction of the dominant metallic species present on the surface of each of these coatings is presented in terms of the relative oxygen affinities of the metals. Theoretical equations for various mechanisms, such as atomic size mismatch, solubility, and oxidation, which could lead to surface segregation are considered, in order to place the experimental observations on a more quantitative basis.

  14. 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.

  15. Epitaxy of Fe/Cu/Si(1 1 1) ultrathin films: an Auger electron diffraction study

    NASA Astrophysics Data System (ADS)

    Castrucci, P.; Gunnella, R.; Bernardini, R.; Montecchiari, A.; Carboni, R.; De Crescenzi, M.

    2001-06-01

    Epitaxial Fe films, with thickness in the range between 1 and 50 ML (monolayer, ML), were grown in ultrahigh vacuum conditions on the 7×7 reconstructed (1 1 1)-Si surface. The films were evaporated on a Cu thick buffer layer to avoid iron silicides formation. Auger electron diffraction (AED) technique has been used to investigate the growth of the pseudomorphic film of fcc γ-Fe(1 1 1) and the successive growth of bcc Fe(1 1 0) domains in the Kurdjumov-Sachs orientation. The early stages of growth have been carefully investigated through AED to assess the pseudomorphism of iron γ-phase. AED patterns clearly show the presence of diffraction features that are fingerprints of the existence of a few bcc arranged atomic structures even for 1 ML iron coverage.

  16. Transverse-to-Longitudinal Emittance Exchange to Improve Performance of High-Gain Free-Electron Lasers

    SciTech Connect

    Emma, P.; Huang, Z.; Kim, K.-J.; Piot, P.; /Northern Illinois U. /Fermilab

    2006-09-21

    The ability to generate small transverse emittance is perhaps the main limiting factor for the performance of high-gain x-rays free-electron lasers (FELs). Noting that beams from an rf photocathode gun can have energy spread much smaller than required for efficient FEL interaction, we present a method to produce normalized transverse emittance at or below about 0.1 {micro}m, which will lead to a significantly shorter length undulator as well as a lower electron beam energy for an x-ray FEL project. The beam manipulation consists of producing an unequal partition of the initially equal emittances into two dissimilar emittances by a flat beam technique and exchanging the larger transverse emittance with a small longitudinal emittance. We study various issues involved in the manipulation. In particular, a new emittance exchange optics we found enables an exact emittance exchange necessary for this scheme.

  17. 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.

  18. Low-energy ion induced Auger electron spectra and energy thresholds for some pure elements, compounds, and alloys

    SciTech Connect

    Fan, C.; Yu, Z.; Chen, X.

    1987-07-01

    By improvements of experimental method, ion induced Auger electron spectra (IAES) of pure elements, compounds, and alloys for 23 samples have been obtained successfully using a combined scanning Auger microscopy/secondary ion mass spectrometry instrument. Ar/sup +/ with energy up to 5 keV was the incident ion. The spectra measured are different from that obtained by electron-stimulated Auger, and correspondent Auger electron energies are not more than 500 eV. With increasing atomic number, the intensity of IAES peaks decreases. Some spectra of those samples and energy thresholds of all samples are given here. Many of them are not found yet in publications. The results showed that energy threshold values of elements go up with increasing atomic number and level off in the region of the fourth- and fifth-period elements. Among others, the thresholds of Mg, Al, and Si are 200, 350, and 600 eV, respectively, and much lower than the values reported before.

  19. Emittance studies at the Los Alamos National Laboratory Free-Electron Laser

    SciTech Connect

    Carlsten, B.E.; Feldman, D.W.; Lumpkin, A.H.; Stein, W.E.; Warren, R.W.

    1987-01-01

    Recent emittance studies at the Los Alamos FEL have indicated several areas of concern in the linac and beamline feeding the wiggler. Four emittance growth mechanisms of special importance have been studied. First, a rapid growth of the electron beam's emittance immediately after the spherical gridded Pierce gun resulted, in part, from the long time required for our pulsing electronics to ramp the grid voltage up at the start and down at the end of the pulse, which created a pulse with a cosine-like current distribution as a function of time. The growth was compounded by the extremely small radial beam size (almost a waist) leaving the gun. In addition, we saw evidence of electrostatic charging of the insulators in the gun, reducing the quality of the electron beam further. Second, the action of the solenoidal focusing fields in the low-voltage bunching region was studied, and criteria for a minimum emittance growth were established. Third, maximum misalignment angles and displacements for various elements of the beamline were calculated for the desired low emittance growth. Finally, emittance growth in the horizontal dimension through the nonisochronous bend caused by varying energy depression on the particles due to longitudinal wake fields was both calculated and observed. In addition, we measured energy depressions caused by the wake fields generated by various other elements in the beamline. Strategies were developed to relieve the magnitude of these wake-field effects. 10 refs., 12 figs.

  20. 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.

  1. 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

  2. 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

  3. 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

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

    2014-07-01

    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. Absorbed dose and stopping cross section for the Auger electrons of 5-18 eV emitted by(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. For a single decay of(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(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. 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 dosimetry calculation of such

  4. 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.

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

    SciTech Connect

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

    2016-07-15

    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.

  6. 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.

  7. 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.

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

    SciTech Connect

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

    2016-03-28

    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.

  9. Auger electron emission initiated by the creation of valence-band holes in graphene by positron annihilation

    PubMed Central

    Chirayath, V. A.; Callewaert, V.; Fairchild, A. J.; Chrysler, M. D.; Gladen, R. W.; Mcdonald, A. D.; Imam, S. K.; Shastry, K.; Koymen, A. R.; Saniz, R.; Barbiellini, B.; Rajeshwar, K.; Partoens, B.; Weiss, A. H.

    2017-01-01

    Auger processes involving the filling of holes in the valence band are thought to make important contributions to the low-energy photoelectron and secondary electron spectrum from many solids. However, measurements of the energy spectrum and the efficiency with which electrons are emitted in this process remain elusive due to a large unrelated background resulting from primary beam-induced secondary electrons. Here, we report the direct measurement of the energy spectra of electrons emitted from single layer graphene as a result of the decay of deep holes in the valence band. These measurements were made possible by eliminating competing backgrounds by employing low-energy positrons (<1.25 eV) to create valence-band holes by annihilation. Our experimental results, supported by theoretical calculations, indicate that between 80 and 100% of the deep valence-band holes in graphene are filled via an Auger transition. PMID:28703225

  10. 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.

  11. Accurate model of electron beam profiles with emittance effects for pierce guns

    NASA Astrophysics Data System (ADS)

    Zeng, Peng; Wang, Guangqiang; Wang, Jianguo; Wang, Dongyang; Li, Shuang

    2016-09-01

    Accurate prediction of electron beam profile is one of the key objectives of electron optics, and the basis for design of the practical electron gun. In this paper, an improved model describing electron beam in Pierce gun with both space charge effects and emittance effects is proposed. The theory developed by Cutler and Hines is still applied for the accelerating region of the Pierce gun, while the motion equations of the electron beams in the anode aperture and drift tunnel are improved by modifying electron optics theory with emittance. As a result, a more universal and accurate formula of the focal length of the lens for the electron beam with both effects is derived for the anode aperture with finite dimension, and a modified universal spread curve considering beam emittance is introduced in drift tunnel region. Based on these improved motion equations of the electron beam, beam profiles with space charge effects and emittance effects can be theoretically predicted, which are subsequently approved to agree well with the experimentally measured ones. The developed model here is helpful to design more applicable Pierce guns at high frequencies.

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

    SciTech Connect

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

    1994-08-01

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

  13. EMILIA, the LS counting efficiency for electron-capture and capture-gamma emitters

    NASA Astrophysics Data System (ADS)

    Grau Carles, A.

    2006-01-01

    This version includes new aspects that improve the computation of the counting efficiency for each one of the three available atomic rearrangement detection models (i.e., KLM, KL 1L 2L 3M and KLMN). The first modification involves a correction algorithm that simulates the non-linear response of the detector to photoionization for low-energy X-ray photons. Although this correction has the inconvenience of substantially increasing the number of atomic rearrangement detection pathways, the computed counting efficiency for low- Z nuclides is reduced by 2% for moderate quenching in agreement with experiment. The program also simulates how the addition of extra components, such as a quencher or aqueous solutions, affects the counting efficiency. Since the CIEMAT/NIST method requires identical ionization quench functions for the electron-capture nuclide and the tracer, the computation of the counting efficiency for 3H, the low-energy beta-ray emitter commonly used as tracer, is included in the program as an option. Program summaryTitle of program:EMILIA Catalogue identifier:ADWK Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADWK Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Licensing previsions: none Computers: revisions: any IBM PC compatible with 80386 or higher Intel processors Operating systems under which the program has been tested:MS-DOS and higher systems Programming language used:FORTRAN 77 Memory required to execute with typical data: 253 kword No. of bits in a word: 32 No. of lines in distributed program, including test data, etc.:7147 No. of bytes in distributed program, including test data, etc.:74 776 Distribution format:tar.gz Nature of the physical problem: The determination of radioactivity in liquid samples of electron-capture nuclides is demanded in radiation physics, radiation protection, dosimetry, radiobiology and nuclear medicine. The CIEMAT/NIST method has proved to be suitable for radionuclide

  14. 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.

  15. Plasmons in doped finite carbon nanotubes and their interactions with fast electrons and quantum emitters

    NASA Astrophysics Data System (ADS)

    de Vega, Sandra; Cox, Joel D.; de Abajo, F. Javier García

    2016-08-01

    We study the potential of highly doped finite carbon nanotubes to serve as plasmonic elements that mediate the interaction between quantum emitters. Similar to graphene, nanotubes support intense plasmons that can be modulated by varying their level of electrical doping. These excitations exhibit large interaction with light and electron beams, as revealed upon examination of the corresponding light extinction cross-section and electron energy-loss spectra. We show that quantum emitters experience record-high Purcell factors, while they undergo strong mutual interaction mediated by their coupling to the tube plasmons. Our results show the potential of doped finite nanotubes as tunable plasmonic materials for quantum optics applications.

  16. Emittance measurements of space-charge-dominated electron beam. Final report

    SciTech Connect

    Namkung, W.; Chojnacki, E.P.

    1985-06-01

    A diagnostic technique of the beam emittance is developed for electron beams with diverging envelopes under strong space-charge forces. Radial profiles of current density, local temperature, and divergence angle are measured by the slit-pinhole method for axisymmetric beams. The partical distribution function in transverse phase space is then constructed and the rms emittance is obtained by numerical integrations. A 5-kV, 200-mA, and 3-microsec electron beam is used in the comparison between theory and experiment on this diagnostic method.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Auger-electron cascades, charge potential and microdosimetry of iodine-125.

    PubMed

    Booz, J; Paretzke, H G; Pomplun, E; Olko, P

    1987-01-01

    This paper is a contribution to the microdosimetry of I-125. It shows microdosimetric spectra of individual and average disintegrations of I-125 for various target sizes and gives evidence for the relative contributions of energy-deposition events of low and high LET. It further presents information on the relative efficiencies of Auger-electrons and multiple charges in terms of local energy deposition, e.g. to model targets of DNA, and discusses their radiobiological implications, e.g. the microdosimetric understanding of the different efficiencies of specific and random incorporations of I-125. When I-125 is specifically incorporated into DNA, most of the energy deposition events are very large, e.g. above 40 keV/micron for a simulated target volume of 20 nm diameter, regardless of the number and energy of Auger electrons emitted. Therefore it is not necessary, for the discussion of the radiobiological implications, to distinguish between different classes of disintegrations. For unspecific, homogeneous incorporation of I-125 somewhere into tissue, about 20% of the dose to critical targets of 25 nm diameter is made up by disintegrations that happen to occur within these targets. When assuming that other critical targets and target structures can be neglected, this part of the dose will be equally effective as in the case of specific incorporation of I-125 into such target models. In addition, there are the normal, low-LET radiation effects from the other, 80% large fraction of the dose. With this information, for the biological systems and end points for which a short section of the elemental chromatine fiber can be taken as the relevant critical target, it is shown that the expected D37 value for homogeneous unspecific incorporation of I-125 can be estimated when the D37 for specific incorporation in DNA is known. For an example calculation, the estimated D37-value for nonspecific, homogeneous incorporation of I-125 would be about half as effective as

  2. 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.

  3. 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.

  4. Emittance Measurements of the Jefferson Lab Free Electron Laser using optical transition radiation

    SciTech Connect

    Holloway, Michael Andrew

    2007-05-01

    Charged particle accelerators, such as the ones that power Free Electron Lasers (FEL), require high quality (low emittance) beams for efficient operation. Accurate and reliable beam diagnostics are essential to monitoring beam parameters in order to maintain a high quality beam. Optical Transition Radiation Interferometry (OTRI) has shown potential to be a quality diagnostic that is especially useful for high brightness electron beams such as Jefferson Labs FEL energy recovery linac. The purpose of this project is to further develop OTRI beam diagnostic techniques. An optical system was designed to make beam size and divergence measurements as well as to prepare for experiments in optical phase space mapping. Beam size and beam divergence measurements were taken to calculate the emittance of the Jefferson Lab FEL. OTRI is also used to separate core and halo beam divergences in order to estimate core and halo emittance separately.

  5. Auger electron spectroscopy and mass spectroscopy studies on hydrogenation of graphite in the presence of nickel and tungsten

    SciTech Connect

    Bliznakov, G.M.; Kiskinova, M.P.; Surnev, L.N.

    1983-05-01

    Hydrogenation of polycrystalline graphite in the presence of nickel and tungsten was studied by means of Auger electron spectroscopy and mass spectroscopy at temperatures up to 850K and a hydrogen pressure ranging from 1.10/sup -8/ to 5.10/sup -6/ Torr. The changes in the carbon Auger lineshape with increasing metal surface concentration revealed a tendency to formation of a carbide phase, the latter being much stabler in the case of tungsten. The mass spectrometric studies of the interaction of hydrogen with the metal graphite systems showed the formation of CH/sub 4/ methane at temperatures higher than 750K. The electronic and adsorption properties of the metal-graphite systems and the formation of active surface carbide carbon were considered in explaining the different catalytic activites of nickel and tungsten. 6 figures.

  6. Towards a Small Emittance Design of the JLEIC Electron Collider Ring

    SciTech Connect

    Lin, Fanglei; Derbenev, Yaroslav; Hutton, Andrew M.; Morozov, Vasiliy; Pilat, Fulvia C.; Zhang, Yuhong

    2016-05-01

    The electron collider ring of the Jefferson Lab Electron-Ion Collider (JLEIC) is designed to provide an electron beam with a small beam size at the IP for collisions with an ion beam in order to reach a desired high luminosity. For a chosen beta-star at the IP, electron beam size is determined by the equilibrium emittance that can be obtained through a linear optics design. This paper briefly describes the baseline design of the electron collider ring reusing PEP-II components and considering their parameters (such as dipole sagitta, magnet field strengths and acceptable synchrotron radiation power) and reports a few approaches to reducing the equilibrium emittance in the electron collider ring.

  7. Emittance studies at the Los Alamos national laboratory free electron laser

    NASA Astrophysics Data System (ADS)

    Carlsten, B. E.; Feldman, D. W.; Lumpkin, A. H.; Sollid, J. E.; Stein, W. E.; Warren, R. W.

    1988-10-01

    Recent emittance studies at the Los Alamos FEL have indicated several areas of concern in the linac and beamline feeding the wiggler. These studies included both experimental measurements and computer simulations. The beamline starts with a 5 A micropulse from the thermionic cathode in the gun. After bunching by velocity modulation and acceleration to 20 MeV in a 1300 MHz standing wave accelerator, the beam current is roughly 250 A. Final bunching to 800 A is performed in the nonisochronous bend that rotates the electrons onto the axis of the wiggler and the optical cavity. Four emittance growth mechanisms of special importance have been studied. First, a rapid growth of the electron beam's emittance immediately after the spherical gridded Pierce gun resulted, in part, from the long time required for our pulsing electronics to ramp the grid voltage up at the start and down at the end of the pulse, which created a pulse with a cosine-like current distribution as a function of time. The growth was compounded by the extremely small radial beam size (almost a waist) leaving the gun. In addition, we saw evidence of electrostatic charging of the insulators in the gun, reducing the quality of the electron beam further. Second the action of the solenoidal focusing fields in the low-voltage bunching region was studied, and criteria for a minimum emittance growth were established. Third, maximum misalignment angles and displacements for various elements of the beamline were calculated for the desired low emittance growth. Finally, emittance growth in the horizontal dimensions through the nonisochronous bend caused by varying energy depression on the particles due to longitudinal wake fields was both calculated and observed. In addition, we measured energy depressions caused by the wake fields generated by various other elements in the beamline. Strategies were developed to relieve the magnitude of these wake-field effects.

  8. 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.

  9. Auger electron diffraction study of the initial stage of Ge heteroepitaxy on Si(001)

    NASA Astrophysics Data System (ADS)

    Sasaki, M.; Abukawa, T.; Yeom, H. W.; Yamada, M.; Suzuki, S.; Sato, S.; Kono, S.

    1994-12-01

    The initial stage of pure and surfactant (Sb)-assisted Ge growth on a Si(001) surface has been studied by Auger electron diffraction (AED) and X-ray photoelectron diffraction (XPD). A single-domain Si(001)2 × 1 substrate was used to avoid the ambiguity arising from the usual double-domain substrate. For the pure Ge growth, 1 monolayer of Ge was deposited onto the room temperature substrate followed by annealing at 350°C-600°C, which appeared to have (1 × 2) periodicity by LEED. Ge LMM AED patterns were measured to find that a substantial amount of Ge atoms diffuse to the bulk Si positions up to the fourth layer at least. For the Sb-assisted Ge growth, a Sb(1 × 2)/Si(001) surface was first prepared and Sb 3d XPD patterns were measured to find that Sb forms dimers on the substrate. 1 ML of Ge was deposited onto the Sb(1 × 2)/Si(001) surface and then the surface was annealed at 600°C. Ge LMM AED and Sb 3d XPD patterns measured for this surface showed that surfactant Sb atoms are indeed present on the first layer forming dimers and that Ge atoms are present mainly on the second layer with a substantial amount of Ge diffused into the third and fourth layers.

  10. 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.

  11. An Ultra-Bright Pulsed Electron Beam With Low Longitudinal Emittance

    SciTech Connect

    Zolotorev, M.; Commins, E.D.; Denes, P.; Hussain, Z.; Lebedev, G.V.; Lidia, S.M.; Robin, D.; Sannibale, F.; Schoenlein, R.W.; Vogel, R.A.; Wan, W.; Heifets, S.A.; /SLAC

    2006-02-10

    Most existing electron sources extract electrons from conductors. Since the actual temperature inside the conductor is much less than the Fermi temperature of the conduction electrons, the electron degeneracy {delta}{sub f} is close to 1, the maximum allowed by the Pauli exclusion principle. However, during extraction several factors conspire together to reduce {delta}{sub f} many orders of magnitude, limiting the achieved values to {approx} 10{sup -5}. A new concept is described for building a novel electron source designed to produce a pulsed beam with {delta}{sub f} {approx} 2 10{sup -3} and longitudinal emittance four orders of magnitude smaller than currently achieved values. This high brightness, low longitudinal emittance regime enables a wide range of novel applications that utilize angstrom-scale spatial resolution and eV-scale energy resolution. The current state of a proof-of-principle experiment conducted at LBNL is also described.

  12. An Ultra-Bright Pulsed Electron Beam with Low LongitudinalEmittance

    SciTech Connect

    Zolotorev, Max; Commins, Eugene D.; Denes, P.; Heifets, Samuel; Hussain, Zahid; Lebedev, Gennnadi V.; Lidia, Steven M.; Robin, David S.; Sannibale, Fernando; Schoenlein, Robert W.; Vogel, Robert; Wan, Weishi

    2005-05-01

    Most existing electron sources extract electrons from conductors. Since the actual temperature inside the conductor is much less than the Fermi temperature of the conduction electrons, the electron degeneracy ({delta}{sub f}) is close to 1, the maximum allowed by the Pauli exclusion principle. However, during extraction several factors conspire together to reduce {delta}{sub f} many orders of magnitude, limiting the achieved values to approx 10{sup -5}. A new concept is described for building a novel electron source designed to produce a pulsed beam with {delta}{sub f} approx 2 10{sup -3} and longitudinal emittance four orders of magnitude smaller than currently achieved values. This high brightness, low longitudinal emittance regime enables a wide range of novel applications that utilize angstrom-scale spatial resolution and eV-scale energy resolution. The current state of a proof-of-principle experiment conducted at LBNL is also described.

  13. 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.

  14. A comprehensive study of the vibrationally resolved S 2p(-1) Auger electron spectrum of carbonyl sulfide.

    PubMed

    Sekushin, V; Püttner, R; Fink, R F; Martins, M; Jiang, Y H; Aksela, H; Aksela, S; Kaindl, G

    2012-07-28

    High-resolution normal Auger-electron spectra of carbonyl sulfide subsequent to S 2p(-1) photoionization at photon energies of 200, 220, and 240 eV are reported along with corresponding photoelectron spectra. In addition, theoretical results are presented that take the core-hole orientation of the various spin-orbit-split and molecular-field-split S 2p(-1) states into account. Auger transitions to eight metastable dicationic final states are observed and assigned on the basis of the theoretical results. From Franck-Condon analysis, assuming Morse potentials along the normal coordinates for seven of the observed quasi-stable dicationic final states, information on the potential-energy surfaces is derived and compared with theoretical results from the literature.

  15. Electron beam emittance techniques for the average power laser experiment (APLE) injector

    NASA Astrophysics Data System (ADS)

    Dowell, D. H.; Davis, K. J.; Tyson, E. L.; Adamski, J. L.; Friddell, K. D.; Shoffstall, D. R.; Lumpkin, A. H.; Takeda, H.

    1992-07-01

    Tests of the average power laser experiment (APLE) injector performance are planned. The injector consists of a frequency-doubled, Nd: YLF driver laser illuminating a cesium-potassium-antimonide photocathode, inserted into one side of the first of two independently powered, single-cell, rf cavities operating at 433 MHz. These are followed by two more cavities, which accelerate the electron beam to approximately 5 MeV. The rest of the beamline to the Faraday cup beam dump contains a three-dipole chicane, along with view screens, ferrite current monitors, and striplines for electron beam characterization. These diagnostics permit measurement of the emittance, pulse length, micropulse charge and peak current. The emittance is determined using the three-screen technique, which has advantages over the two-screen method. The longitudinal emittance can be measured using a streak camera that views quartz screens before, inside, and after the chicane. This chicane can also be used to bunch the electron beam using its non-isochronous transport. The formalism for the measurement of transverse and longitudinal emittances is described.

  16. 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.

  17. Surface-conduction electron-emitter characteristics and fabrication based on vertically aligned carbon nanotube arrays

    NASA Astrophysics Data System (ADS)

    Shih, Yi-Ting; Li, Kuan-Wei; Honda, Shin-ichi; Lin, Pao-Hung; Huang, Ying-Sheng; Lee, Kuei-Yi

    2017-06-01

    The carbon nanotube (CNT) has replaced palladium oxide (PdO) as the electrode material for surface-conduction electron-emitter (SCE) applications. Vertically aligned CNT arrays with a delta-star arrangement were patterned and synthesized onto a quartz substrate using photolithography and thermal chemical vapor deposition. Delta-star shaped VACNT arrays with 20° tips are used as cathodes that easily emit electrons because of their high electrical field gradient. In order to improve the field emission and secondary electrons (SEs) in SCE applications, magnesium oxide (MgO) nanostructures were coated onto the VACNT arrays to promote the surface-conduction electron-emitter display (SED) efficiency (η). According to the definition of η in SCE applications, in this study, the η was stably maintained in the 75-85% range. The proposed design provides a facile new method for developing SED applications.

  18. Electron quantum optics: current and noise of a single electron emitter

    NASA Astrophysics Data System (ADS)

    Fève, Gwendal

    2010-03-01

    Ballistic electronic transport along the Quantum Hall edge states of two dimensional electron gases presents strong analogies with the propagation of photons which have been best illustrated by the realization of electronic Mach-Zehnder interferometers [1]. The analogy can be pushed to quantum optics where single electron emitters are realized to manipulate one or few charges. Celebrated experiments such as the one electron Hanbury-Brown and Twiss or the two electrons Hong-Ou-Mandel experiments can then be implemented [2]. This brings us closer to the on demand generation of entangled electron pairs. The feasibility of these new quantum optics experiments relies also on the ability to measure the output correlations of the current generated by the source. We will present the first realization of such a single electron source characterized both by the measurement of the average ac current [3] and its fluctuations. The source is made of a periodically driven mesoscopic capacitor [4,5] coupled to the electron reservoir by a tunnel barrier of adjustable transmission. At the first half period of the excitation drive, an occupied energy level of the dot is suddenly promoted above the Fermi energy and a single charge is emitted on the tunnelling escape time. In the second half period, the level is brought back to its initial value and an electron is absorbed, leaving a hole in the Fermi sea. Single electron emission appears as a quantization of the ac current in units of the electric charge times the drive frequency. The occurrence of spurious multiple charge events can be ruled out by the measurement of the noise presented here. Our measurements confirm single electron emission where the noise reduces to the quantum jitter associated with the Heisenberg uncertainty on the emission time.[4pt] [1] Y. Ji et al., Nature 422, 415 (2003) [0pt] [2] S. Ol'khovskaya et al., Phys. Rev. Lett. 101, 166802 (2008)[0pt] [3] G. Fève et al., Science 316, 1169 (2007) [0pt] [4] M. B

  19. 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.

  20. 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.

  1. Projection of excited orbitals into kinetic energies of emitted electrons in resonant Si KLL Auger decays of SiF{sub 4}

    SciTech Connect

    Suzuki, I. H.; Kono, Y.; Ikeda, A.; Nagaoka, S.; Ouchi, T.; Ueda, K.; Takahashi, O.; Higuchi, I.; Tamenori, Y.

    2010-10-15

    Spectator resonant Auger-electron spectra have been measured in the Si 1s photoexcitation region of SiF{sub 4} using an electron spectroscopic technique combined with undulator radiation. A transition with the highest intensity in the total ion yield spectrum, which comes from excitation of a 1s electron into the 6t{sub 2} valence orbital, generates resonant Auger decays in which the excited electron remains predominantly in the valence orbital or is partly shaken up into a high-lying Rydberg orbital. The higher-lying peak generated through excitation into Rydberg orbitals induces resonant Auger decays in which the excited Rydberg electron is partly shaken up to a higher-lying Rydberg orbital or shaken down to a lower-lying valence molecular orbital. These findings exhibit a clear disentanglement effect among excited orbitals which are smeared out in the 1s electron excitation spectrum.

  2. Multi-field electron emission pattern of 2D emitter: Illustrated with graphene

    NASA Astrophysics Data System (ADS)

    Luo, Ma; Li, Zhibing

    2016-11-01

    The mechanism of laser-assisted multi-field electron emission of two-dimensional emitters is investigated theoretically. The process is basically a cold field electron emission but having more controllable components: a uniform electric field controls the emission potential barrier, a magnetic field controls the quantum states of the emitter, while an optical field controls electron populations of specified quantum states. It provides a highly orientational vacuum electron line source whose divergence angle over the beam plane is inversely proportional to square root of the emitter height. Calculations are carried out for graphene with the armchair emission edge, as a concrete example. The rate equation incorporating the optical excitation, phonon scattering, and thermal relaxation is solved in the quasi-equilibrium approximation for electron population in the bands. The far-field emission patterns, that inherit the features of the Landau bands, are obtained. It is found that the optical field generates a characteristic structure at one wing of the emission pattern.

  3. The low-energy β(-) and electron emitter (161)Tb as an alternative to (177)Lu for targeted radionuclide therapy.

    PubMed

    Lehenberger, Silvia; Barkhausen, Christoph; Cohrs, Susan; Fischer, Eliane; Grünberg, Jürgen; Hohn, Alexander; Köster, Ulli; Schibli, Roger; Türler, Andreas; Zhernosekov, Konstantin

    2011-08-01

    The low-energy β(-) emitter (161)Tb is very similar to (177)Lu with respect to half-life, beta energy and chemical properties. However, (161)Tb also emits a significant amount of conversion and Auger electrons. Greater therapeutic effect can therefore be expected in comparison to (177)Lu. It also emits low-energy photons that are useful for gamma camera imaging. The (160)Gd(n,γ)(161)Gd→(161)Tb production route was used to produce (161)Tb by neutron irradiation of massive (160)Gd targets (up to 40 mg) in nuclear reactors. A semiautomated procedure based on cation exchange chromatography was developed and applied to isolate no carrier added (n.c.a.) (161)Tb from the bulk of the (160)Gd target and from its stable decay product (161)Dy. (161)Tb was used for radiolabeling DOTA-Tyr3-octreotate; the radiolabeling profile was compared to the commercially available n.c.a. (177)Lu. A (161)Tb Derenzo phantom was imaged using a small-animal single-photon emission computed tomography camera. Up to 15 GBq of (161)Tb was produced by long-term irradiation of Gd targets. Using a cation exchange resin, we obtained 80%-90% of the available (161)Tb with high specific activity, radionuclide and chemical purity and in quantities sufficient for therapeutic applications. The (161)Tb obtained was of the quality required to prepare (161)Tb-DOTA-Tyr3-octreotate. We were able to produce (161)Tb in n.c.a. form by irradiating highly enriched (160)Gd targets; it can be obtained in the quantity and quality required for the preparation of (161)Tb-labeled therapeutic agents. Copyright © 2011 Elsevier Inc. All rights reserved.

  4. Comparative study of supertips for electron field emitters

    NASA Astrophysics Data System (ADS)

    Koops, Hans W. P.; Weber, Mark A.; Urban, J.; Schoessler, C.

    1995-09-01

    A numerical study of tips and supertips prone for fieldemission sources is performed using a 3D numerical electron optics package. Special supertips are fabricated with additive lithography under computer control. Different materials are used to generate amorphous or nanocrystalline tips. Its performance is simulated. Additive lithography using electron beam induced deposition allows to design base radii from 50 to 1000 nm. Tip radii and tip length of similar dimensions can be generated. Supertips on top of a deposited tip can have a radius as small as 5 nm. This is achieved using a high resolution scanning electron microscope with a cold field emission source. Gold-tips are constructed on top of Pt/Ir-wire tips. The positioning accuracy is 20 nm. Tips are routinely produced with aspect ratios of 5 to 10 and give an additional field enhancement factor. The influence of the nanocrystallinity of the deposited material to the field enhancement is investigated. Nanocrystals at the tip enhance the field up to a factor of 4. This effect explains the high emission current obtained in experiments from nanocrystalline tips.

  5. Studies Of Oxidation And Thermal Reduction Of The Cu(100) Surface Using Positron Annihilation Induced Auger Electron Spectroscopy

    SciTech Connect

    Fazleev, N. G.; Nadesalingam, M. P.; Maddox, W.; Weiss, A. H.

    2011-06-01

    Positron annihilation induced Auger electron spectroscopy (PAES) measurements from the surface of an oxidized Cu(100) single crystal show a large increase in the intensity of the annihilation induced Cu M2,3VV Auger peak as the sample is subjected to a series of isochronal anneals in vacuum up to annealing temperature 300 deg. C. The PAES intensity then decreases monotonically as the annealing temperature is increased to {approx}550 deg. C. Experimental positron annihilation probabilities with Cu 3p and O 1s core electrons are estimated from the measured intensities of the positron annihilation induced Cu M{sub 2,3}VV and O KLL Auger transitions. PAES results are analyzed by performing calculations of positron surface states and annihilation probabilities of the surface-trapped positrons with relevant core electrons taking into account the charge redistribution at the surface and various surface structures associated with low and high oxygen coverages. The variations in atomic structure and chemical composition of the topmost layers of the oxidized Cu(100) surface are found to affect localization and spatial extent of the positron surface state wave function. The computed positron binding energy and annihilation characteristics reveal their sensitivity to charge transfer effects, atomic structure and chemical composition of the topmost layers of the oxidized Cu(100) surface. Theoretical positron annihilation probabilities with Cu 3p and O 1s core electrons computed for the oxidized Cu(100) surface are compared with experimental ones. The obtained results provide a demonstration of thermal reduction of the copper oxide surface after annealing at 300 deg. C followed by re-oxidation of the Cu(100) surface at higher annealing temperatures presumably due to diffusion of subsurface oxygen to the surface.

  6. 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.

  7. Direct measurement of Auger electrons emitted from a semiconductor light-emitting diode under electrical injection: identification of the dominant mechanism for efficiency droop.

    PubMed

    Iveland, Justin; Martinelli, Lucio; Peretti, Jacques; Speck, James S; Weisbuch, Claude

    2013-04-26

    We report on the unambiguous detection of Auger electrons by electron emission spectroscopy from a cesiated InGaN/GaN light-emitting diode under electrical injection. Electron emission spectra were measured as a function of the current injected in the device. The appearance of high energy electron peaks simultaneously with an observed drop in electroluminescence efficiency shows that hot carriers are being generated in the active region (InGaN quantum wells) by an Auger process. A linear correlation was measured between the high energy emitted electron current and the "droop current"--the missing component of the injected current for light emission. We conclude that the droop phenomenon in GaN light-emitting diodes originates from the excitation of Auger processes.

  8. Hardened planar nitride based cold cathode electron emitter

    NASA Astrophysics Data System (ADS)

    Pillai, R.; Starikov, D.; Boney, C.; Bensaoula, A.

    2012-03-01

    Low threshold electron emission from planar AlN/Silicon heterostructures is reported. The surface emitting ballistic electron structure consisted of an undoped AlN layer grown on Silicon by Molecular Beam Epitaxy, a Ti/Au Ohmic contact, and a thin Pt Schottky contact fabricated by e-beam deposition. Tunnel-transparent Pt Schottky contact was deposited on a 1 μm thick Silicon Dioxide (SiO2) layer and covered a 4 x 4 matrix of 50 μm diameter via produced in the SiO2 layer using photolithography The measurements were performed in vacuum (~10-8 Torr) using a metal grid separated from the structure by a 60 micron thick Kapton® polyimide film having an opening aligned with the via. Bias voltages in the range of 0-130 V were applied across the Schottky diode, while currents were recorded across the structure for grid voltages ranging from 0 to 50 V. The field emission nature of the measured currents was confirmed by plotting the Fowler-Nordheim dependence. Current density of at least 2.5x10-4A/cm2 was achieved for a grid voltage of 50 V and a bias of 130 V. Degradation of the structure performance was observed at bias voltages exceeding 90 V as a result of Schottky barrier modification under the elevated temperature and high electric field operation. The solid-state electron emitting structure indicated a threshold field as low as 0.2 V/μm under applied grid voltage of 12 V.

  9. Suppression of Emittance Growth Using a Shaped Cold Atom Electron and Ion Source

    NASA Astrophysics Data System (ADS)

    Thompson, D. J.; Murphy, D.; Speirs, R. W.; van Bijnen, R. M. W.; McCulloch, A. J.; Scholten, R. E.; Sparkes, B. M.

    2016-11-01

    We demonstrate precise control of charged particle bunch shape with a cold atom electron and ion source to create bunches with linear and, therefore, reversible Coulomb expansion. Using ultracold charged particles enables detailed observation of space-charge effects without loss of information from thermal diffusion, unambiguously demonstrating that shaping in three dimensions can result in a marked reduction of Coulomb-driven emittance growth. We show that the emittance growth suppression is accompanied by an increase in bunch focusability and brightness, improvements necessary for the development of sources capable of coherent single-shot ultrafast electron diffraction of noncrystalline objects, with applications ranging from femtosecond chemistry to materials science and rational drug design.

  10. Emission Properties of Porous Silicon Electron Emitters Formed by Pulsed Anodic Etching

    NASA Astrophysics Data System (ADS)

    Hu, W. B.; Zhao, W.; Fan, J. L.; Wu, S. L.; Zhang, J. T.

    2017-02-01

    Porous silicon (PS) layers were formed by pulsed anodic etching and subsequently processed by electrochemical oxidization (ECO) and high-pressure water vapor annealing (HWA), and their morphologies and oxidation degrees were analyzed. The electron emitters based on these PS layers were fabricated, and their emission properties were investigated. The experimental results show that a PS layer formed by pulsed anodic etching has a better pore-diameter homogeneity in the longitudinal direction, and it can obtain good oxidation quality more easily by the combined treatment of ECO and HWA. The as-formed PS electron emitters have better emission properties in comparison with those based on PS layers prepared by constant-current anodic etching.

  11. Suppression of Emittance Growth Using a Shaped Cold Atom Electron and Ion Source.

    PubMed

    Thompson, D J; Murphy, D; Speirs, R W; van Bijnen, R M W; McCulloch, A J; Scholten, R E; Sparkes, B M

    2016-11-04

    We demonstrate precise control of charged particle bunch shape with a cold atom electron and ion source to create bunches with linear and, therefore, reversible Coulomb expansion. Using ultracold charged particles enables detailed observation of space-charge effects without loss of information from thermal diffusion, unambiguously demonstrating that shaping in three dimensions can result in a marked reduction of Coulomb-driven emittance growth. We show that the emittance growth suppression is accompanied by an increase in bunch focusability and brightness, improvements necessary for the development of sources capable of coherent single-shot ultrafast electron diffraction of noncrystalline objects, with applications ranging from femtosecond chemistry to materials science and rational drug design.

  12. Emittance and Energy Measurements of Low-Energy Electron Beam Using Optical Transition Radiation Techniques

    NASA Astrophysics Data System (ADS)

    Sakamoto, Fumito; Iijima, Hokuto; Dobashi, Katsuhiro; Imai, Takayuki; Ueda, Toru; Watanabe, Takahiro; Uesaka, Mitsuru

    2005-03-01

    Emittance and energy of an electron beam in the range of 8 to 22 MeV were measured via optical transition radiation (OTR) techniques. The beam divergence effect on observations of the far-field OTR image at low energies was studied by means of numerical analysis. The numerical analysis indicates that if the beam divergence is under 1.5 mrad, a simultaneous single-shot measurement of emittance and energy is possible. The results of the single-shot experiment agree with independent measurements conducted using the quadrupole scan method and an electron spectrometer. The experiments were performed with an S-band linac at the Nuclear Engineering Research Laboratory, The University of Tokyo (UTNL).

  13. Growth of carbon nanotube field emitters on single strand carbon fiber: a linear electron source

    NASA Astrophysics Data System (ADS)

    Kim, Ha Jin; Jong Bae, Min; Kim, Yong C.; Cho, Eun S.; Sohn, Y. C.; Kim, D. Y.; Lee, S. E.; Kang, H. S.; Han, In T.; Kim, Young H.; Patole, Shashikant P.; Yoo, Ji Beom

    2011-03-01

    The multi-stage effect has been revisited through growing carbon nanotube field emitters on single strand carbon fiber with a thickness of 11 µm. A prepared linear electron source exhibits a turn-on field as low as 0.4 V µm - 1 and an extremely high field enhancement factor of 19 300, when compared with those results from reference nanotube emitters grown on flat silicone wafer; 3.0 V µm - 1 and 2500, respectively. In addition, we introduce a novel method to grow nanotubes uniformly around the circumference of carbon fibers by using direct resistive heating on the continuously feeding carbon threads. These results open up not only a new path for synthesizing nanocomposites, but also offer an excellent linear electron source for special applications such as backlight units for liquid crystal displays and multi-array x-ray sources.

  14. A multislit transverse-emittance diagnostic for space-charge-dominated electron beams

    SciTech Connect

    Piot, P.; Song, J.; Li, R.

    1997-06-01

    Jefferson Lab is developing a 10 MeV injector to provide an 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, the authors 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.

  15. 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.

  16. Electron transfer mediated decay in NeXe triggered by K-LL Auger decay of Ne

    NASA Astrophysics Data System (ADS)

    Stumpf, Vasili; Scheit, Simona; Kolorenč, Přemysl; Gokhberg, Kirill

    2017-01-01

    In this article we present the results of an ab initio study of electron transfer mediated decay (ETMD) in NeXe dimer triggered by the K-LL Auger decay of Ne. We found that the Ne2+ (2p-21D)Xe and Ne2+ (2p-21S)Xe states which are strongly populated in the Auger process may decay by ETMD emitting a slow electron and leading to the Coulomb explosion of the dimer which results in Ne+ and Xe2+ ions. We also computed the corresponding decay widths, the ETMD electron spectra, and the kinetic energy release of the nuclei (KER) spectra. We showed that the spectra corresponding to the decaying states which derive from the two multiplets have completely different shape which reflects differing accessibility of the ETMD final states. Thus, in the Ne2+ (2p-21S)Xe state ETMD is allowed for all interatomic distances accessible in nuclear dynamics, while in the Ne2+ (2p-21D)Xe state the ETMD channels become closed one by one. This in turn leads to the different behavior of the ETMD decay widths and ultimately the spectra. We show how these differences make it possible to study ETMD of the two states separately in a coincident measurement. We also discuss how the dynamics which follow ETMD in the final state manifold may lead to the appearance of the unusual products: Ne, Xe3+ and a slow electron.

  17. Auger electron diffraction study of Fe 1- xNi x alloys epitaxially grown on Cu(100)

    NASA Astrophysics Data System (ADS)

    Martin, M. G.; Foy, E.; Chevrier, F.; Krill, G.; Asensio, M. C.

    1999-08-01

    We have combined Auger electron diffraction (AED), low-energy electron diffraction (LEED) and high-energy electron diffraction (RHEED) to examine the structure of Fe xNi 1- x alloys when the Fe content approaches 65%. At this concentration, the 'invar effect' takes place, so the magnetization falls to zero, and the thermal expansion coefficient is very small. The Fe xNi 1- x alloys, grown as metastable thin films by molecular-beam epitaxy on Cu(100) substrates, were studied as a function of the x stoichiometry. In contrast to the related bulk alloy compounds, we observe the collapse of the fcc-to-bcc structural transition in the Fe-rich films. Furthermore, the local atomic structure around Fe and Ni in the alloy has been simultaneously determined by the angular intensity distributions of Fe L 3VV (703 eV) and Ni L 3VV (848 eV) Auger electrons measured as a function of polar and azimuthal angles. For the films deposited at room temperature, we have confirmed the pseudomorphic growth morphology and the uniformity of the alloys.

  18. Electron quasi-Fermi level splitting at the base emitter junction of HBTs and DHBTs

    NASA Astrophysics Data System (ADS)

    García-Loureiro, Antonio J.; López-González, Juan M.

    2004-03-01

    In this paper we study the amount of electron quasi-Fermi level splitting in the emitter-base junction of single and double heterojunction bipolar transistors using a new numerical model that includes Fermi-Dirac statistics and base recombination current. The degree of splitting is different using our model than with previous models when high voltage or high doping levels are used. In order to illustrate its features, the model is applied to the study of collector current HBTs and DHBTs.

  19. 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.

  20. Auger electron and X-ray photoelectron spectroscopic study of the biocorrosion of copper by alginic acid polysaccharide

    NASA Astrophysics Data System (ADS)

    Jolley, John G.; Geesey, Gill G.; Hankins, Michael R.; Wright, Randy B.; Wichlacz, Paul L.

    1989-08-01

    Thin films (3.4 nm) of copper on germanium substrates were exposed to 2% alginic acid polysaccharide aqueous solution. 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 some of the copper was oxidized by the alginic acid solution. Some of the copper was removed from the Cu/Ge interface and incorporated into the polymer matrix. Thus, biocorrosion of copper was exhibited by the alginic acid polysaccharide.

  1. 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.

  2. 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

    2016-04-19

    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.

  3. 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

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

    DOE PAGES

    Golovin, G.; Banerjee, S.; Liu, C.; ...

    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

  5. Improved electron emission properties of the porous silicon emitter by chemical surface modification

    NASA Astrophysics Data System (ADS)

    Wang, Wenjiang; He, Li; Zhang, Xiaoning; Zhang, He

    2017-08-01

    A new chemical dipping method using nickel chloride (NiCl2) solution is proposed to improve the characteristics of an electron emitter based on porous silicon (PS). Two groups of PS samples were prepared, one group was then left untreated, while the other group was treated by the chemical dipping method. Energy dispersive x-ray (EDX) and x-ray photoemission spectroscopy (XPS) studies confirm the uniform filling of the reduced Ni and the formation of the SiO2 in the chemically dipped sample. The gold electrode was sputtered on the modified PS surface and the study of J-V characteristics show that the modified samples have more favorable rectifying behavior and longer-term durability than the unmodified one. The measured results showed that the voltage threshold ˜8 V, PVCR value ˜1.08, emission current density ˜48 μA cm-2, emission efficiency ˜0.72%, and stable emission were achieved for the modified sample; most of these electron emission characteristics were better than those from the unmodified emitter. Such improvements are mainly due to the decrease of the contact barrier height between the PS and the gold electrode, as is evident from analyzing the logarithmic J-V characteristics. The chemical dipping method is therefore expected to be a valuable technique to enhance the electron emission characteristics of the PS emitter.

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

    SciTech Connect

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

    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 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.

  7. Improvement of electron emission characteristics of porous silicon emitter by using cathode reduction and electrochemical oxidation

    NASA Astrophysics Data System (ADS)

    Li, He; Wenjiang, Wang; Xiaoning, Zhang

    2017-03-01

    A new simple and convenient post-treat technique combined the cathode reduction (CR) and electrochemical oxidation (ECO) was proposed to improve the electron emission properties of the surface-emitting cold cathodes based on the porous silicon (PS). It is demonstrated here that by introducing this new technique combined CR and ECO, the emission properties of the diode have been significantly improved than those as-prepared samples. The experimental results showed that the emission current densities and efficiencies of sample treated by CR were 62 μA/cm2 and 12.10‰, respectively, nearly 2 orders of magnitude higher than those of as-prepared sample. Furthermore, the CR-treated PS emitter shows higher repeatability and stability compared with the as-prepared PS emitter. The scanning electron microscope (SEM), atomic force microscope (AFM), energy dispersive spectrometer (EDS), furier transformed infrared (FTIR) spectroscopy results indicated that the improved mechanism is mainly due to the passivation of the PS, which not only improve the PS morphology by the passivation of the H+ but also improve the uniformity of the oxygen content distribution in the whole PS layer. Therefore, the method combined the CR treatment and ECO is expected to be a valuable technique to enhance the electron emission characteristics of the PS emitter.

  8. Angle Resolved Photoelectron and Auger Electron Diffraction as a Structural Probe for Surfaces, Interfaces, and Epitaxial Films.

    NASA Astrophysics Data System (ADS)

    Li, Hong

    The recently developed techniques of angle-resolved photoelectron and Auger electron diffraction (ARXPD/AED) have shown promise in identifying the structures of epitaxial films. This is due to the realization that electrons scattered by other atoms are enhanced along the forward direction. In this dissertation research, we have further investigated the capabilities of the ARXPD/AED technique. First, the complete polar angle distribution of the Auger electron intensity from Cu(001) was measured from the (100) to the (110) azimuth. The presentation of the ARAED in the form of a contour map clearly shows the relationship of the constructive and destructive interference of electron scattering to the crystallographic index of the crystal. Secondly, the angular distributions of electron emissions with initial states of 3p, 3d, 4d, and the Auger emission with electron kinetic energies ranging from 348 eV to 1477 eV were measured for single crystal Ag(001). The results show that all of these electron emissions have similar electron forward scattering enhancements along the directions of nearest and next nearest neighbour atoms in the crystal. The forward scattering enhancements do not shift as the electron kinectic energy changes. The ARXPD/AED combined with low energy electron diffraction (LEED) has been demonstrated to be a very powerful technique in probing both the long range order and the short range order of the epitaxial films. The epitaxial films studied include Co on Cu(001), Fe on Ag(001), Co on Ag(001), and Co on an ultra-thin film of Fe(001), which was epitaxially grown on Ag(001). We find that up to 20 ML thickness of high quality metastable fcc Co can be stabilized on Cu(001) at room temperature. We have directly verified that the Fe on Ag(001) is bcc. The Co on Ag(001) is neither bcc nor fcc for coverages of less than 3 ML. Thick films of Co on Ag(001) are disordered, of which a very small portion has a local structure of bcc. The bcc Co phases has been

  9. Cellular dosimetry and microdosimetry for internal electron emitters.

    PubMed

    Chao, T C; Huang, Y S; Hsu, F Y; Hsiao, Y; Lee, C C; Tung, C J

    2011-02-01

    Radiobiological descriptions of cellular dosimetry and microdosimetry require both radiation dose and radiation quality. The lineal energy, defined as a ratio of the energy deposition by a particle in the biological target and the mean chord length of this target, is generally adopted to characterise the radiation quality. Most microdosimetry applications assume that the cell nucleus is the target region. Therefore, the lineal energy is obtained for the source (S) to target (T) geometry, T ← S, where S = cell surface, cytoplasm, cell nucleus and T = cell nucleus. The definition of lineal energy is based on the approximation that the particle mean pathlength is equal to target mean chord length. This approximation is valid for crossers of external irradiations. In the case of starters, insiders and stoppers of internal sources, particle pathlengths are always shorter than target chord lengths. Thus, the lineal energy does not reflect the specific energy deposition along particle path. In the present work, the specific energy deposition in a target is calculated using three distance parameters, i.e. target mean chord length, particle mean pathlength in the target and particle individual pathlength in the target. Monte Carlo calculations are performed for electrons of various energies and cells of different sizes. Results are analysed and discussed.

  10. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

    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.

  12. Summary of ISO/TC 201 Standard: ISO 29081: 2010, Surface Chemical Analysis - Auger Electron Spectroscopy - Reporting of Methods Used for Charge Control and Charge Correction

    SciTech Connect

    Baer, Donald R.

    2011-11-01

    This international standard specifies the minimum amount of information required for describing the methods of charge control in measurements of Auger electron transitions from insulating specimens by electron-stimulated Auger electron spectroscopy to be reported with the analytical results. Information is provided in an Annex on methods that have been found useful for charge control prior to or during AES analysis. The Annex also includes a summary table of methods or approaches, ordered by simplicity of approach. A similar international standard has been published for x-ray photoelectron spectroscopy (ISO 19318: 2003(E), Surface chemical analysis - X-ray photoelectron spectroscopy - Reporting of methods used for charge control and charge correction).

  13. 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.

  14. Asymmetrical field emitter

    DOEpatents

    Fleming, James G.; Smith, Bradley K.

    1995-01-01

    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.

  15. 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.

  16. 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.

  17. A quantitative study of valence electron transfer in the skutterudite compound CoP(3) by combining x-ray induced Auger and photoelectron spectroscopy.

    PubMed

    Diplas, S; Prytz, O; Karlsen, O B; Watts, J F; Taftø, J

    2007-06-20

    We use the sum of the ionization and Auger energy, the so-called Auger parameter, measured from the x-ray photoelectron spectrum, to study the valence electron distribution in the skutterudite CoP(3). The electron transfer between Co and P was estimated using models relating changes in Auger parameter values to charge transfer. It was found that each P atom gains 0.24 e(-), and considering the unit formula CoP(3) this is equivalent to a donation of 0.72 e(-) per Co atom. This is in agreement with a recent electron energy-loss spectroscopy study, which indicates a charge transfer of 0.77 e(-)/atom from Co to P.

  18. 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.

  19. A quantitative study of valence electron transfer in the skutterudite compound CoP3 by combining x-ray induced Auger and photoelectron spectroscopy

    NASA Astrophysics Data System (ADS)

    Diplas, S.; Prytz, Ø.; Karlsen, O. B.; Watts, J. F.; Taftø, J.

    2007-06-01

    We use the sum of the ionization and Auger energy, the so-called Auger parameter, measured from the x-ray photoelectron spectrum, to study the valence electron distribution in the skutterudite CoP3. The electron transfer between Co and P was estimated using models relating changes in Auger parameter values to charge transfer. It was found that each P atom gains 0.24 e-, and considering the unit formula CoP3 this is equivalent to a donation of 0.72 e- per Co atom. This is in agreement with a recent electron energy-loss spectroscopy study, which indicates a charge transfer of 0.77 e-/atom from Co to P.

  20. Chemical-state-selective X-ray absorption spectroscopy by detecting bond-specific Auger electrons for SiO2/SiC interface

    NASA Astrophysics Data System (ADS)

    Isomura, Noritake; Murai, Takaaki; Oji, Hiroshi; Nomoto, Toyokazu; Watanabe, Yukihiko; Kimoto, Yasuji

    2017-08-01

    Chemical-state-selective Si K-edge extended X-ray absorption fine structure (EXAFS) measurements of SiO2 and SiC are demonstrated by detecting bond-specific Auger electrons in SiC coated with a very thin SiO2 film. Differential-electron-yield (DEY) mode is used for the measurements. Each EXAFS spectrum may be subject to the following two spectrally overlapping influences: (i) the background spectrum formed by energy-losing SiC Auger electrons overlaps the SiO2 Auger peak, and (ii) the resonant SiO2 Auger peak overlaps the SiC Auger peak. The SiO2- and SiC-selective DEY-EXAFS spectra differ from each other and are similar to the spectra of bulk SiO2 and SiC, respectively, in the EXAFS regions, indicating that the two influences are negligible, and that this method can be considered valid for selection of chemical states.

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

    PubMed

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

    2015-04-01

    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(-9) - 10(-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(4)P and prompt Auger projectile states formed by electron capture in collisions of 25.3 MeV F(7+) with H2 and 12.0 MeV C(4+) with Ne recorded at 0° to the beam direction. These results are important for the accurate evaluation of the 1s2s2p (4)P/(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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    We present SIMION 8.1 Monte Carlo type simulations of the response function and detection solid angle for long lived Auger states (lifetime τ ˜ 10-9 - 10-5 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 1s2s2p4P and prompt Auger projectile states formed by electron capture in collisions of 25.3 MeV F7+ with H2 and 12.0 MeV C4+ with Ne recorded at 0∘ to the beam direction. These results are important for the accurate evaluation of the 1s2s2p 4P/2P 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.

  3. 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.

  4. Determination of ratios of Auger electrons emission probabilities and K-L shell vacancy transfer probability of Cr, Mn, Fe, Co, Ni, Cu and Zn compounds

    NASA Astrophysics Data System (ADS)

    Küçükönder, Adnan; Kavşut, Onur

    2017-02-01

    Ratios of emission probabilities of Auger electrons [u = p(KLX)/p(KLL), ν = p(KXY)/p(KLL)] and the vacancy transfer probabilities from K to L shell, ηKL for Cr, Mn, Fe, Co,Ni, Cu and Zn compounds were obtained using the experimental Kx-ray emission ratios and K-shell fluorescence yields. We were used the experimental Kβ/Kα intensity ratios and K shell fluorescence yields WK. Ratios of emission probabilities of Auger electrons and the vacancy transfer probabilities are changed by chemical effect for different for Cr, Mn, Fe, Co,Ni, Cu and Zn compounds.

  5. 4d{sup -1} photoelectron spectra and subsequent N{sub 4,5}OO Auger electron spectra of atomic Sb

    SciTech Connect

    Patanen, M.; Heinaesmaeki, S.; Urpelainen, S.; Aksela, S.; Aksela, H.

    2010-05-15

    4d{sup -1} photoelectron and subsequent N{sub 4,5}OO Auger electron spectra of Sb have been measured using synchrotron radiation. Features created by an open shell electronic structure of atomic Sb in the spectra have been interpreted using multiconfigurational Dirac-Fock calculations. The results are compared with the molecular Sb{sub 4} and the comparison shows that the relaxation pathways of the hole states in atomic and molecular Sb are very different, so that different groups of states are populated in the corresponding Auger spectra.

  6. 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

  7. 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.

  8. Study of O/Ni(100) with LEED (low-energy electron diffraction) and AES (auger electron spectroscopy) from chemisorption to oxidation

    SciTech Connect

    Wang, Wen-Di.

    1990-11-16

    The structures formed on the Ni(100) surface during oxygen adsorption, leading to oxidation, are studied with Video-LEED (low-energy electron diffraction) and AES (Auger electron spectroscopy). The temperature- and exposure-dependence in the development of LEED patterns observed during oxidation of Ni(100), at oxidation temperatures of 80 to 400 K, are investigated extensively. Integrated diffraction spot intensities and fractional spot profiles are measured quantitatively and continuously, allowing unambiguous correlation of various surface processes. AES is used to measure the oxidation onset during adsorption and the final relative thickness of the oxide. 48 figs., 79 refs.

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

    SciTech Connect

    Jin, Xiuguang; Cotta, Alexandre A. C.; Chen, Gong; N'Diaye, Alpha T.; Schmid, Andreas K.; Yamamoto, Naoto

    2014-11-07

    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.

  10. Multipathway dissociation dynamics of core-excited methyl chloride probed by high resolution electron spectroscopy and Auger-electron-ion coincidences.

    PubMed

    Miron, Catalin; Morin, Paul; Céolin, Denis; Journel, Loïc; Simon, Marc

    2008-04-21

    Core excitation triggers nuclear dynamics on the femtosecond time scale. A multiparametric electron/ion coincidence approach has been used to disentangle complex decay processes occurring at short (molecular) or long (atomic) time scales. Methyl chloride has been excited by scanning along the dissociative Cl2p-->sigma* resonance. The detailed chronology of the competing decay processes, leading to either the rearrangement product HCl(+), or an ultrafast dissociation leading to Cl(+), has been investigated. The observed Auger-Doppler shift has been analyzed for various orientations of the electron and fragment ion.

  11. 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.

  12. Electron emission properties of gated silicon field emitter arrays driven by laser pulses

    NASA Astrophysics Data System (ADS)

    Shimawaki, Hidetaka; Nagao, Masayoshi; Neo, Yoichiro; Mimura, Hidenori; Wakaya, Fujio; Takai, Mikio

    2016-10-01

    We report optically modulated electron emission from gated p-type silicon field emitter arrays (Si-FEAs). The device's "volcano" structure is designed to control the photoexcitation of electrons by transmitting light through the small gate aperture, thereby minimizing the photogeneration of slow diffusion carriers outside the depletion region in the tip. Compared to that in the dark, the emission current was enhanced by more than three orders of magnitude in the high field region when irradiated with blue laser pulses. Results from the time-resolved measurements of photoassisted electron emission showed that these possess the same response as the laser pulse with no discernible delay. These results indicate that the volcano device structure is effective at eliminating the generation of diffusion carriers and that a fully optimized FEA is promising as a photocathode for producing high-speed modulated electron beams.

  13. X-ray photoelectron and scanning Auger electron spectroscopy study of electrodeposited ZnCr coatings on steel.

    PubMed

    Itani, H; Duchoslav, J; Arndt, M; Steck, T; Gerdenitsch, J; Faderl, J; Preis, K; Winkler, W; Stifter, D

    2012-05-01

    Zn-Cr alloyed coatings electrochemically deposited are of high interest for leading steel manufacturing companies because of their novel properties and high corrosion resistance compared with conventional Zn coatings on steel. For tuning and optimizing the properties of the electrodeposited Zn-Cr coatings, a broad range of the deposition conditions must be studied. For this reason, two different types of material were investigated in this study, one with a low electrolyte temperature and one with an elevated electrolyte pH, compared with the standard values. Because different corrosion performance and delamination behaviour of the layers were observed for the two types, advanced surface analysis was conducted to understand the origin of this behaviour and to discover differences in the formation of the coatings. The topmost surface, the shallow subsurface region, and the whole bulk down to the coating-steel interface surface were analysed in detail by X-ray photoelectron spectroscopy (XPS) and high-resolution scanning Auger electron spectroscopy to determine the elemental and the chemical composition. For better understanding of the resulting layer structure, multiple reference samples and materials were measured and their Auger and XPS spectra were fitted to the experimental data. The results showed that one coating type is composed of metallic Zn and Cr, with oxide residing only on the surface and interface, whereas the other type contains significant amounts of Zn and Cr oxides throughout the whole coating thickness.

  14. Low-emittance electron-beam generation with laser pulse shaping in photocathode radio-frequency gun

    NASA Astrophysics Data System (ADS)

    Yang, J.; Sakai, F.; Yanagida, T.; Yorozu, M.; Okada, Y.; Takasago, K.; Endo, A.; Yada, A.; Washio, M.

    2002-08-01

    A technique of laser-pulse shaping was developed for low-emittance electron-beam generation in a photocathode radio-frequency (rf) gun. The emittance growth due to space charge and rf effects in the rf gun was experimentally investigated with square and gaussian temporal pulse shapes. It was found that the square pulse shaping was a useful tool for both the reduction of nonlinear space-charge force and the correction of linear space charge. The normalized transverse rms emittance at 1 nC was obtained to be 1.20 pimm-mrad for the square pulse shape with pulse length of 9 ps full width at half maximum. The emittance was measured as a function of the electron bunch charge and the laser-pulse length.

  15. Effects of electron back-scattering in observations of cross-sectioned GaAs/AlAs superlattice with auger electron spectroscopy.

    PubMed

    Suzuki, Mineharu; Urushihara, Nobuaki; Sanada, Noriaki; Paul, Dennis F; Bryan, Scott; Hammond, John S

    2010-01-01

    Cross-sections of GaAs/AlAs thin films prepared by cleavage of MBE-grown superlattices have been analyzed with Auger electron spectroscopy with a spatial resolution of 6 nm. Elemental distributions of Ga, Al, and As were clearly distinguished in line analysis as well as in two dimensional mapping for 50, 20, and 10 nm thin film structures. We have found an oscillation of Al KLL peak position between the two values while the peak positions of Ga LMM and As LMM remain constant. The origin of the Al KLL peak shift is a primary electron beam induced reduction of oxidized Al atoms formed during specimen preparation. The Auger spectra of Al oxide are generated by scattered electrons at regions with small amounts of electron dose, corresponding to AlAs areas further than 10 to 25 nm from the primary beam. The intensity of the Al KLL peaks excited by scattered electrons from the 25 kV primary electron beam is about 10% of the Ga LMM peak intensity originating from the GaAs stripe.

  16. Monte Carlo single-cell dosimetry of Auger-electron emitting radionuclides

    NASA Astrophysics Data System (ADS)

    Bousis, C.; Emfietzoglou, D.; Hadjidoukas, P.; Nikjoo, H.

    2010-05-01

    A hybrid Monte Carlo transport scheme combining event-by-event and condensed-history simulation with a full account of energy-loss straggling was used to study the dosimetric characteristics of the Auger-emitting radionuclides 67Ga, 99mTc, 111In, 123I, 125I and 201Tl at the single-cell level. The influence of the intracellular localization of the Auger radionuclide upon cellular S-values, radial dose rate profiles and dose-volume-histograms (DVHs) was investigated. For the case where the radiopharmaceutical was either internalized into the cytoplasm or remained bound onto the cell surface (non-internalized), the dose to the cell nucleus was found to differ significantly from the MIRD values and other published data. In this case, the assumption of a homogeneous distribution throughout the cell is shown to significantly overestimate the nuclear dose. A dosimetric case study relevant to the radioimmunotherapy of single lymphoma B-cells with 125I and 123I is presented.

  17. Modelling of a high-current magnetron discharge in a plasma electron emitter

    NASA Astrophysics Data System (ADS)

    Udovichenko, S. Yu; Kostrin, D. K.; Lisenkov, A. A.

    2017-07-01

    An analytical model of a high-current form of a low-pressure glow discharge in an inverted cylindrical magnetron, which performs the function of plasma electron emitter, is shown. Were found conditions of the discharge self-sustaining, allowing to estimate the voltage of the discharge and determine the critical value of the magnetic field and residual gas pressure below which the existence of this type of discharge is impossible. A comparison of the calculated discharge characteristics with experimental data obtained on the setup for studying the emission properties of the magnetron discharge was carried out.

  18. Low-emittance thermionic-gun-based injector for a compact free-electron laser

    NASA Astrophysics Data System (ADS)

    Asaka, Takao; Ego, Hiroyasu; Hanaki, Hirohumi; Hara, Toru; Hasegawa, Taichi; Hasegawa, Teruaki; Inagaki, Takahiro; Kobayashi, Toshiaki; Kondo, Chikara; Maesaka, Hirokazu; Matsubara, Shinichi; Matsui, Sakuo; Ohshima, Takashi; Otake, Yuji; Sakurai, Tatsuyuki; Suzuki, Shinsuke; Tajiri, Yasuyuki; Tanaka, Shinichiro; Togawa, Kazuaki; Tanaka, Hitoshi

    2017-08-01

    A low-emittance thermionic-gun-based injector was developed for the x-ray free-electron laser (XFEL) facility known as the SPring-8 angstrom compact free-electron laser (SACLA). The thermionic-gun-based system has the advantages of maintainability, reliability, and stability over a photocathode radio-frequency (rf) gun because of its robust thermionic cathode. The basic performance of the injector prototype was confirmed at the SPring-8 compact self-amplified spontaneous emission source (SCSS) test accelerator, where stable FEL generation in an extreme ultraviolet wavelength range was demonstrated. The essential XFEL innovation is the achievement of a constant beam peak current of 3-4 kA, which is 10 times higher than that generated by the SCSS test accelerator, while maintaining a normalized-slice emittance below 1 mm mrad. Thus, the following five modifications were applied to the SACLA injector: (i) a nonlinear energy chirp correction; (ii) the optimization of the rf acceleration frequency; (iii) rf system stabilization; (iv) nondestructive beam monitoring; and (v) a geomagnetic field correction. The SACLA injector successfully achieved the target beam performance, which shows that a thermionic-gun-based injector is applicable to an XFEL accelerator system. This paper gives an overview of the SACLA injector and describes the physical and technical details, together with the electron beam performance obtained in the beam commissioning.

  19. 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.

  20. Precision Control of the Electron Longitudinal Bunch Shape Using an Emittance-Exchange Beam Line

    DOE PAGES

    Ha, Gwanghui; Cho, Moo -Hyun; Namkung, W.; ...

    2017-03-09

    Here, we report on the experimental generation of relativistic electron bunches with a tunable longitudinal bunch shape. A longitudinal bunch-shaping (LBS) beam line, consisting of a transverse mask followed by a transverse-to-longitudinal emittance exchange (EEX) beam line, is used to tailor the longitudinal bunch shape (or current profile) of the electron bunch. The mask shapes the bunch’s horizontal profile, and the EEX beam line converts it to a corresponding longitudinal profile. The Argonne wakefield accelerator rf photoinjector delivers electron bunches into a LBS beam line to generate a variety of longitudinal bunch shapes. The quality of the longitudinal bunch shapemore » is limited by various perturbations in the exchange process. We develop a simple method, based on the incident slope of the bunch, to significantly suppress the perturbations.« less

  1. Precision control of the electron longitudinal bunch shape using an emittance exchange beamline

    DOE PAGES

    Ha, Gwanghui; Cho, Moo-Hyun; Namkung, W.; ...

    2017-03-09

    We report on the experimental generation of relativistic electron bunches with a tunable longitudinal bunch shape. A longitudinal bunch-shaping (LBS) beam line, consisting of a transverse mask followed by a transverse-to-longitudinal emittance exchange (EEX) beam line, is used to tailor the longitudinal bunch shape (or current profile) of the electron bunch. The mask shapes the bunch’s horizontal profile, and the EEX beam line converts it to a corresponding longitudinal profile. The Argonne wakefield accelerator rf photoinjector delivers electron bunches into a LBS beam line to generate a variety of longitudinal bunch shapes. The quality of the longitudinal bunch shape ismore » limited by various perturbations in the exchange process. We develop a simple method, based on the incident slope of the bunch, to significantly suppress the perturbations.« less

  2. Precision Control of the Electron Longitudinal Bunch Shape Using an Emittance-Exchange Beam Line

    NASA Astrophysics Data System (ADS)

    Ha, G.; Cho, M. H.; Namkung, W.; Power, J. G.; Doran, D. S.; Wisniewski, E. E.; Conde, M.; Gai, W.; Liu, W.; Whiteford, C.; Gao, Q.; Kim, K.-J.; Zholents, A.; Sun, Y.-E.; Jing, C.; Piot, P.

    2017-03-01

    We report on the experimental generation of relativistic electron bunches with a tunable longitudinal bunch shape. A longitudinal bunch-shaping (LBS) beam line, consisting of a transverse mask followed by a transverse-to-longitudinal emittance exchange (EEX) beam line, is used to tailor the longitudinal bunch shape (or current profile) of the electron bunch. The mask shapes the bunch's horizontal profile, and the EEX beam line converts it to a corresponding longitudinal profile. The Argonne wakefield accelerator rf photoinjector delivers electron bunches into a LBS beam line to generate a variety of longitudinal bunch shapes. The quality of the longitudinal bunch shape is limited by various perturbations in the exchange process. We develop a simple method, based on the incident slope of the bunch, to significantly suppress the perturbations.

  3. 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.

  4. Auger eectron spectroscopy study of the {ZrO }/{W(100) } system at high temperature

    NASA Astrophysics Data System (ADS)

    Lee, S. C.; Irokawa, Y.; Inoue, M.; Shimizu, R.

    1996-09-01

    To study the role of oxygen in the mechanism of lowering the work function in the oxygen-processed {Zr}/{W(100) } system, Auger spectrum shape analysis was performed at high temperature after oxygen processing, according to the conventional treatment for activation processing of a {Zr-O }/{W(100) } thermal field emitter (TFE). For this we prepared O/Zr(≈1/2 ML)/M(100) and O/Zr(≈1 ML/W(100) to examine whether or not the oxygen adsorption on the {Zr}/{W(100) } results in any variation in the Auger spectrum of Zr as a result of the chemical effect caused by ZrO bonding. Auger electron spectroscopy (AES) of these samples reveals a tiny peak near 130 eV, which is thought to represent ZrO bonding. Careful re-examination of the Zr Auger spectra from {ZrO }/{W(100) } at ≈1700 K has led to the conclusion that this tiny peak at 130 eV did appear in the Auger spectrum reported in the previous paper. It has also been found from the analysis of the oxygen Auger spectrum that WO x is partially formed in a W(100) substrate.

  5. 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.

  6. Auger electron spectroscopy determination of surface self-diffusion coefficients from growth of voids in thin deposited films

    NASA Astrophysics Data System (ADS)

    Beszeda, I.; Szabó, I. A.; Gontier-Moya, E. G.

    2003-05-01

    Morphological evolution of thin metallic films, i.e. beading, Ostwald-ripening and/or evaporation of a beaded film, on a substrate under annealing is a complex process which depends on several parameters. However, under accurate experimental conditions, it is possible to study the growth of voids in thin continuous films (beading) separately. We compared different models describing this process and found that the Brandon and Bradshaw's description can be applied for these measurements. They suggest that the voids grow by surface self-diffusion of the metal atoms, independently of the substrate. Hence, from the time dependence of the uncovered surface, which is proportional to the area of voids, the surface self-diffusion coefficient of the metal can be derived. We present here a new method, based on Auger electron spectroscopy and atomic force microscopy techniques, to perform these measurements and we discuss its advantages and limits on an experimental example.

  7. Auger electron spectroscopy study of initial stages of oxidation in a copper - 19.6-atomic-percent-aluminum alloy

    NASA Technical Reports Server (NTRS)

    Ferrante, J.

    1973-01-01

    Auger electron spectroscopy was used to examine the initial stages of oxidation of a polycrystalline copper - 19.6 a/o-aluminum alloy. The growth of the 55-eV aluminum oxide peak and the decay of the 59-, 62-, and 937-eV copper peaks were examined as functions of temperature, exposure, and pressure. Pressures ranged from 1x10 to the minus 7th power to 0.0005 torr of O2. Temperatures ranged from room temperature to 700 C. A completely aluminum oxide surface layer was obtained in all cases. Complete disappearance of the underlying 937-eV copper peak was obtained by heating at 700 C in O2 at 0.0005 torr for 1 hr. Temperature studies indicated that thermally activated diffusion was important to the oxidation studies. The initial stages of oxidation followed a logarithmic growth curve.

  8. Theoretical Auger electron and X-ray emission spectra of CO and H 2O by density functional theory calculations

    NASA Astrophysics Data System (ADS)

    Otsuka, Takao; Chong, Delano P.; Maki, Jun; Kawabe, Hiroyuki; Endo, Kazunaka

    2002-02-01

    We propose a new method for analysis of X-ray emission and Auger electron spectra (XES and AES) of molecules involving the valence spectra using density functional theory (DFT) calculations. To obtain the more accurate transition energies and the relative intensities, we use the total-energy difference procedure ( ΔE-KS) for all transition energies, and transform the coefficients in the LCGTO-MO scheme in the DFT to those for the linear combination of the LCGTO-AO scheme. The method is applied to the analysis of valence spectra, XES and AES for CO and H 2O molecules. The simulated spectra are in a good agreement with the experimental results.

  9. 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.

  10. In situ X-ray photoelectron and Auger electron spectroscopic characterization of reaction mechanisms during Li-ion cycling.

    PubMed

    Tang, Ching-Yen; Haasch, Richard T; Dillon, Shen J

    2016-11-03

    The complex nature of Li-ion battery reactions along with their sensitivity to environmental exposure necessitates in situ characterization, particularly for surface sensitive methods. In this work, we demonstrate in situ X-ray photoelectron spectroscopy and in situ Auger electron spectroscopy applied to characterize the evolution of bonding and chemistry during cycling of nanoparticle electrodes. We apply the method to study the conversion reaction associated with Li insertion and extraction from CuO nanoparticle electrodes. This approach circumvents the need for ion sputtering and mechanical erosion, previously required to remove solid electrolyte interphase during ex situ measurements. This allows the elucidation of the changes in Cu oxidation state, during initial Li insertion, without the introduction of artifacts that have caused prior disagreement in the published literature.

  11. 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.

  12. 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.

  13. Stranski-Krastanov Growth of Tungsten during Chemical Vapor Deposition Revealed by Micro-Auger Electron Spectroscopy

    NASA Astrophysics Data System (ADS)

    Noda, Suguru; Tsumura, Takeshi; Fukuhara, Jota; Yoda, Takashi; Komiyama, Hiroshi; Shimogaki, Yukihiro

    2004-10-01

    Chemical vapor deposition (CVD) of tungsten is an important process to make interconnections in advanced integrated-circuit devices. As device dimensions continue to decrease, incomplete nucleation inside the trenches and via holes is becoming a crucial issue. In this work, micro-Auger electron spectroscopy with in-plane spatial resolution was applied for the first time to study the nucleation and growth process of W islands. Results showed that W grew slowly and uniformly on TiN surfaces up to about one-monolayer coverage, and then W islands nucleated and started to grow rapidly. This transition from layer to island shows that W grew by Stranski-Krastanov mode during CVD on TiN from WF6 and SiH4. Drastic difference might exist in chemical reactivity between the initial W layer on TiN surfaces and the W islands, causing the change in W growth rate.

  14. Study on mechanism of selective chemical vapor deposition of tungsten using in situ infrared spectroscopy and Auger electron spectroscopy

    NASA Astrophysics Data System (ADS)

    Kobayashi, Nobuyoshi; Goto, Hidekazu; Suzuki, Masayuki

    1991-01-01

    Selective chemical vapor deposition (CVD) of tungsten (W) using tungsten hexafluoride (WF6) and monosilane (SiH4) is investigated by in situ infrared spectroscopy and Auger electron spectroscopy. The infrared spectra show that trifluorosilane (SiHF3) is the main by-product species, and that silicon-tetrafluoride (SiF4) is less than 20%-25% of SiHF3 in partial pressure. The main chemical reaction involved in selective W CVD can be expressed as WF6+2SiH4→W+2SiHF3+3H2. Based on our experimental results, a new mechanism of selective W CVD, which notes hydrogen dissociation having a central role in this process, is proposed. It disproves the widely accepted model, which is based on the assumption that SiF4 is the major reaction product.

  15. Surface compositions of solid and liquid indium-tin alloys by auger electron spectroscopy using ion bombardment

    SciTech Connect

    Komiyama, M.; Tsukamoto, H.; Ogino, Y.

    1986-09-01

    Equilibrium surface compositions of solid and liquid In-Sn alloys of various bulk compositions were examined by Auger electron spectroscopy. The composition relaxation at the solid surfaces of this alloy system was very fast, and utilizing this the bulk compositions of the solid alloys and the corresponding surface compositions were determined using Xe-ion bombardment in conjunction. Above the temperature 1.2 times the melting point, the surface compositions were constant regardless of temperature, and coincided with the nominal bulk composition. As the temperature was lowered toward the melting point, surface segregation became apparent, and at around the melting point the surface composition nearly coincided with those of the solid alloys. When surface segregation occurred, In segregated to the surfaces of Sn-rich alloys and Sn to the surfaces of In-rich alloys. Under the influence of surface oxygen In segregates to the solid surface at any alloy composition.

  16. Electron dynamics in charge-transfer-to-solvent states of aqueous chloride revealed by Cl- 2p resonant Auger-electron spectroscopy.

    PubMed

    Winter, Bernd; Aziz, Emad F; Ottosson, Niklas; Faubel, Manfred; Kosugi, Nobuhiro; Hertel, Ingolf V

    2008-06-04

    Charge-transfer-to-solvent (CTTS) excited states of aqueous chloride are studied by a novel experimental approach based on resonant inner-shell photoexcitation, Cl(-)aq 2p --> e(i), i = 1-4, which denotes a series of excitations to lowest and higher CTTS states. These states are clearly identified through the occurrence of characteristic spectator Auger decays to double Cl 3p valence-hole states, where the CTTS states can be more stabilized as compared to single Cl(-)aq 2p core excitations and optical valence excitations. Furthermore, we have found for the first time that the CTTS electron e(i) bound by a single Cl 2p hole not only behaves as a spectator e(i) --> e'(i), bound by a double valence-hole state before relaxation of the excited electron (i) itself, but also shows electron dynamics to the relaxed lowest state, e(i) --> e'(1*). This interpretation is supported by ab initio calculations. The key to performing photoelectron and Auger-electron spectroscopy studies from aqueous solutions is the use of a liquid microjet in ultrahigh vacuum in conjunction with synchrotron radiation.

  17. Studies of emittance of multiply charged ions extracted from high temperature superconducting electron cyclotron resonance ion source, PKDELIS

    SciTech Connect

    Rodrigues, G.; Lakshmy, P. S.; Kumar, Sarvesh; Mandal, A.; Kanjilal, D.; Roy, A.; Baskaran, R.

    2010-02-15

    For the high current injector project at Inter University Accelerator Centre, a high temperature superconducting electron cyclotron resonance (ECR) ion source, PKDELIS, would provide the high charge state ions. The emittance of the ECR ion source is an important parameter to design further beam transport system and to match the acceptances of the downstream radio frequency quadrupole and drift tube linac accelerators of the high current injector. The emittance of the analyzed beam of PKDELIS ECR source has been measured utilizing the three beam size technique. A slit and two beam profile monitors positioned at fixed distances from each other were used to measure the beam size. The digitized beam profiles have been analyzed to determine the emittance of various multiply charged ions. The variation of emittance with gas mixing, ultrahigh frequency power, and extraction energy are discussed in this presentation.

  18. 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

  19. Localized versus delocalized excitations just above the 3d threshold in krypton clusters studied by Auger electron spectroscopy.

    PubMed

    Tchaplyguine, M; Kivimäki, A; Peredkov, S; Sorensen, S L; Ohrwall, G; Schulz, J; Lundwall, M; Rander, T; Lindblad, A; Rosso, A; Svensson, S; Mårtensson, N; Björneholm, O

    2007-09-28

    We present Auger spectroscopy studies of large krypton clusters excited by soft x-ray photons with energies on and just above the 3d(52) ionization threshold. The deexcitation spectra contain new features as compared to the spectra measured both below and far above threshold. Possible origins of these extra features, which stay at constant kinetic energies, are discussed: (1) normal Auger process with a postcollision interaction induced energy shift, (2) recapture of photoelectrons into high Rydberg orbitals after Auger decay, and (3) excitation into the conduction band (or "internal" ionization) followed by Auger decay. The first two schemes are ruled out, hence internal ionization remains the most probable explanation.

  20. Monolayer graphene-insulator-semiconductor emitter for large-area electron lithography

    NASA Astrophysics Data System (ADS)

    Kirley, Matthew P.; Aloui, Tanouir; Glass, Jeffrey T.

    2017-06-01

    The rapid adoption of nanotechnology in fields as varied as semiconductors, energy, and medicine requires the continual improvement of nanopatterning tools. Lithography is central to this evolving nanotechnology landscape, but current production systems are subject to high costs, low throughput, or low resolution. Herein, we present a solution to these problems with the use of monolayer graphene in a graphene-insulator-semiconductor (GIS) electron emitter device for large-area electron lithography. Our GIS device displayed high emission efficiency (up to 13%) and transferred large patterns (500 × 500 μm) with high fidelity (<50% spread). The performance of our device demonstrates a feasible path to dramatic improvements in lithographic patterning systems, enabling continued progress in existing industries and opening opportunities in nanomanufacturing.

  1. 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.

  2. ¹¹¹In-Bn-DTPA-nimotuzumab with/without modification with nuclear translocation sequence (NLS) peptides: an Auger electron-emitting radioimmunotherapeutic agent for EGFR-positive and trastuzumab (Herceptin)-resistant breast cancer.

    PubMed

    Fasih, Aisha; Fonge, Humphrey; Cai, Zhongli; Leyton, Jeffrey V; Tikhomirov, Ilia; Done, Susan J; Reilly, Raymond M

    2012-08-01

    Increased expression of epidermal growth factor receptors (EGFR) in breast cancer (BC) is often associated with trastuzumab (Herceptin)-resistant forms of the disease and represents an attractive target for novel therapies. Nimotuzumab is a humanized IgG(1) monoclonal antibody that is in clinical trials for treatment of EGFR-overexpressing malignancies. We show here that nimotuzumab derivatized with benzylisothiocyanate diethylenetriaminepentaacetic acid for labelling with the subcellular range Auger electron-emitter, (111)In and modified with nuclear translocation sequence (NLS) peptides ((111)In-NLS-Bn-DTPA-nimotuzumab) was bound, internalized and transported to the nucleus of EGFR-positive BC cells. Emission of Auger electrons in close proximity to the nucleus caused multiple DNA double-strand breaks which diminished the clonogenic survival (CS) of MDA-MB-468 cells that have high EGFR density (2.4 × 10(6) receptors/cell) to less than 3 %. (111)In-Bn-DTPA-nimotuzumab without NLS peptide modification was sevenfold less effective for killing MDA-MB-468 cells. (111)In-Bn-DTPA-nimotuzumab with/without NLS peptide modification were equivalently cytotoxic to MDA-MB-231 and TrR1 BC cells that have moderate EGFR density (5.4 × 10(5) or 4.2 × 10(5) receptors/cell, respectively) reducing their CS by twofold. MDA-MB-231 cells have intrinsic trastuzumab resistance due to low HER2 density, whereas TrR1 cells have acquired resistance despite HER2 overexpression. Biodistribution and microSPECT/CT imaging revealed that (111)In-NLS-Bn-DTPA-nimotuzumab exhibited more rapid elimination from the blood and lower tumour uptake than (111)In-Bn-DTPA-nimotuzumab. Tumour uptake of the radioimmunoconjugates in mice with MDA-MB-468 xenografts was high (8-16 % injected dose/g) and was blocked by administration of an excess of unlabelled nimotuzumab, demonstrating EGFR specificity. We conclude that (111)In-Bn-DTPA-nimotuzumab with/without NLS peptide modification are promising Auger

  3. 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.

  4. 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.

  5. X-ray-photoelectron-spectroscopy and Auger-electron-spectroscopy study of ultrathin palladium films on a Pt(111) substrate

    NASA Astrophysics Data System (ADS)

    Han, Moonsup; Mrozek, P.; Wieckowski, A.

    1993-09-01

    We have studied ultrathin palladium films vacuum deposited onto a Pt(111) substrate utilizing Auger-electron spectroscopy (AES), low-energy electron diffraction, and x-ray photoelectron spectroscopy. The AES results fit well to a layer-by-layer growth deposition. Below a coverage of 4 monolayers, the electron-diffraction data only show a (1×1) structure of palladium adatoms on the Pt(111) substrate, supporting the Frank-van der Merve growth mechanism. In contrast to two-dimensional palladium clusters and palladium bimetallic systems, the Pd 3d core-level binding energy of palladium on Pt(111) shifts toward lower binding energy relative to the value of bulk palladium with decreasing palladium overlayer coverage. This negative binding-energy shift of a surface adatom core level results mainly from the initial-state band-narrowing effect predicted by Citrin, Wertheim, and Baer. Also, the absence of the final-state effect after creating a core hole in the Pd/Pt(111) system indicates that efficient screening or very fast relaxation occurs, and that hybridization of the valence bands of the palladium adlayer and the platinum substrate plays an implortant role in the negative surface-atom binding-energy shift of the Pd 3d core level.

  6. 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.

  7. Observation of electron cloud instabilities and emittance dilution at the Cornell electron-positron Storage ring Test Accelerator

    DOE PAGES

    Holtzapple, R. L.; Billing, M. G.; Campbell, R. C.; ...

    2016-04-11

    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 diagnostics 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 withmore » 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 study 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.« less

  8. Observation of electron cloud instabilities and emittance dilution at the Cornell electron-positron Storage ring Test Accelerator

    SciTech Connect

    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.

    2016-04-11

    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 diagnostics 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 study 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.

  9. Considerations for a high-performance thermionic energy conversion device based on a negative electron affinity emitter

    NASA Astrophysics Data System (ADS)

    Smith, Joshua Ryan; Bilbro, Griff L.; Nemanich, Robert J.

    2007-12-01

    A theory is developed to model the effect a negative electron affinity (NEA) emitter electrode has on the negative space charge effect of a vacuum thermionic energy conversion device (TEC). The theory is derived by treating the electrons in the interelectrode space as a collisionless gas and self-consistently solving the Boltzmann transport equation and Poisson equation. The theory determines the point on the voltage-current characteristic such that the maximum motive due to space charge is at the same level as the conduction band minimum. It is shown that emitter electrodes with an NEA significantly mitigate the negative space charge effect; therefore a TEC employing such an electrode will outperfrom a similar TEC with conventional electrodes in terms of output power. Additionally, it is shown that a TEC with an NEA emitter electrode can have a greater interelectrode spacing than a TEC with conventional electrodes operating under similar conditions where the outputs of both TEC’s are comparable.

  10. Experimental study on the electric-sweep scanner and ion beam emittance of electron cyclotron resonance ion source

    SciTech Connect

    Cao, Y.; Sun, L.T.; Ma, L.; Ma, B.H.; Wang, H.; Feng, Y.C.; Li, J.Y.; Zhao, H.W.; Zhang, Z.M.; Zhang, X.Z.; He, W.; Zhao, H.Y.; Guo, X.; Li, X.X.

    2006-03-15

    With a latest developed electric-sweep scanner system, we have done a lot of experiments for studying this scanner system and ion beam emittance of electron cyclotron resonance (ECR) ion source. The electric-sweep scanner system was installed on the beam line of Lanzhou electron resonance ion source No. 3 experimental platform of Institute of Modern Physics. The repetition experiments have proven that the system is a relatively dependable and reliable emittance scanner, and its experiment error is about 10%. We have studied the influences of the major parameters of ECR ion source on the extracted ion beam emittance. The typical results of the experiments and the conclusions are presented in this article.

  11. Angle-resolved electron spectroscopy of laser-assisted Auger decay induced by a few-femtosecond x-ray pulse.

    PubMed

    Meyer, M; Radcliffe, P; Tschentscher, T; Costello, J T; Cavalieri, A L; Grguras, I; Maier, A R; Kienberger, R; Bozek, J; Bostedt, C; Schorb, S; Coffee, R; Messerschmidt, M; Roedig, C; Sistrunk, E; Di Mauro, L F; Doumy, G; Ueda, K; Wada, S; Düsterer, S; Kazansky, A K; Kabachnik, N M

    2012-02-10

    Two-color (x-ray+infrared) electron spectroscopy is used for investigating laser-assisted KLL Auger decay following 1s photoionization of atomic Ne with few-femtosecond x-ray pulses from the Linac Coherent Light Source. In an angle-resolved experiment, the overall width of the laser-modified Auger-electron spectrum and its structure change significantly as a function of the emission angle. The spectra are characterized by a strong intensity variation of the sidebands revealing a gross structure. This variation is caused, as predicted by theory, by the interference of electrons emitted at different times within the duration of one optical cycle of the infrared dressing laser, which almost coincides with the lifetime of the Ne 1s vacancy.

  12. Low emittance design of the electron gun and the focusing channel of the Compact Linear Collider drive beam

    NASA Astrophysics Data System (ADS)

    Dayyani Kelisani, M.; Doebert, S.; Aslaninejad, M.

    2017-04-01

    For the Compact Linear Collider project at CERN, the power for the main linacs is extracted from a drive beam generated from a high current electron source. The design of the electron source and its subsequent focusing channel has a great impact on the beam dynamic considerations of the drive beam. We report the design of a thermionic electron source and the subsequent focusing channels with the goal of production of a high quality beam with a very small emittance.

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

    NASA Astrophysics Data System (ADS)

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

    2017-05-01

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

  14. NanoSIMS analysis and Auger electron spectroscopy of silicate and oxide stardust from the carbonaceous chondrite Acfer 094

    NASA Astrophysics Data System (ADS)

    Vollmer, Christian; Hoppe, Peter; Stadermann, Frank J.; Floss, Christine; Brenker, Frank E.

    2009-12-01

    We have detected 138 presolar silicate, 20 presolar oxide and three presolar complex grains within the carbonaceous chondrite Acfer 094 by NanoSIMS oxygen isotope mapping. These grains were further investigated by scanning electron microscopy (SEM) and Auger electron spectroscopy for morphological and chemical details and their distribution within the meteorite matrix. The three complex grains consist of Al-rich oxides (grossite and hibonite) attached to non-stoichiometric Si-rich silicates. Refractory Al-rich oxides therefore serve as seed nuclei for silicates to condense onto, which is proposed by condensation theory and astronomical observations. However, in the majority of presolar silicates we did not find any indications for large subgrains. Most of the grains (80%) belong to O isotope Group I ( 17O-enriched) and come from 1 to 2.5 M⊙ asymptotic giant branch (AGB) stars of close-to-solar or slightly lower-than-solar metallicity. About 60% of these grains are irregular in shape; ˜40% display elliptical morphologies together with smooth, platy surfaces. Three grains with large 17O enrichments ( 17O/ 16O > 3 × 10 -3) have highly irregular shapes and are very small (<250 nm); these grains may have formed in binary star systems or around higher mass ( ˜3M⊙) AGB stars. About 10% of the presolar silicates in this study can be assigned to the O isotope Group IV, which most likely originate from type II supernovae (SNeII). These grains are also generally smaller than 300 nm and are often irregular in shape (88%), consistent with the SNII origin scenario. The presolar grains are generally evenly distributed within the matrix on an mm scale, although in one case a statistically significant clustering of five grains in one 10 × 10 μm 2 sized field is observed. This could be an important hint that the distribution of presolar material in the parental molecular cloud was heterogeneous on a very fine scale. The matrix-normalized abundance of silicate stardust in

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. R-matrix electron-impact excitation data for the Li-like iso-electronic sequence including Auger and radiation damping

    NASA Astrophysics Data System (ADS)

    Liang, G. Y.; Badnell, N. R.

    2011-04-01

    We present results for the electron-impact excitation of all Li-like ions from Be+ to Kr33+ which we obtained using the radiation- and Auger-damped intermediate-coupling frame transformation R-matrix approach. We have included both valence- and core-electron excitations up to the 1s25l and 1s2l4l' levels, respectively. A detailed comparison of the target structure and collision data has been made for four specific ions (O5+, Ar15+, Fe23+ and Kr33+) spanning the sequence so as to assess the accuracy for the entire sequence. Effective collision strengths (Υs) are presented at temperatures ranging from 2 × 102(z + 1)2 K to 2 × 106(z + 1)2 K (where z is the residual charge of the ions, i.e. Z - 3). Detailed comparisons for the Υs are made with the results of previous calculations for several ions which span the sequence. The radiation and Auger damping effects were explored for core-excitations along the iso-electronic sequence. Furthermore, we examined the iso-electronic trends of effective collision strengths as a function of temperature. These data are made available in the archives of APAP via http://www.apap-network.org, OPEN-ADAS via http://open.adas.ac.uk, as well as anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/528/A69

  20. The COOLER Code: A Novel Analytical Approach to Calculate Subcellular Energy Deposition by Internal Electron Emitters.

    PubMed

    Siragusa, Mattia; Baiocco, Giorgio; Fredericia, Pil M; Friedland, Werner; Groesser, Torsten; Ottolenghi, Andrea; Jensen, Mikael

    2017-08-01

    activity distribution on the cell surface, MIRD predictions appeared to fail the most. The proposed method is suitable for Auger-cascade electrons, but can be extended to any energy of interest and to beta spectra; as an example, the (3)H case is also discussed. COOLER is intended to be accessible to everyone (preclinical and clinical researchers included), and may provide important information for the selection of radionuclides, the interpretation of radiobiological or preclinical results, and the general establishment of doses in any scenario, e.g., with cultured cells in the laboratory or with therapeutic or diagnostic applications. The software will be made available for download from the DTU-Nutech website: http://www.nutech.dtu.dk/ .

  1. 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.

  2. Mechanism of the activation process for the formation of a surface-conduction electron-emitter

    NASA Astrophysics Data System (ADS)

    Tsukamoto, Takeo; Okuda, Masahiro; Arai, Yutaka; Miyata, Hirokatsu

    2016-01-01

    The major role of the chemical reaction between a silica substrate and deposited carbon in the activation process for the formation of a surface-conduction electron emitter (SCE) is investigated. The SCE emits electrons by the tunneling effect when an electric field is applied across a nanoscale gap. The nanogap is spontaneously formed by the activation process, wherein a pulse voltage is applied between a pair of electrodes, which are separated by a narrow gap inside a vacuum chamber in the presence of hydrocarbons. At the gap, two elemental processes compete; the deposition of carbon by the electron-induced decomposition of hydrocarbons and the consumption of carbon by reaction with the silica substrate. The balance of the dynamics of the two processes, which simply depends on the temperature at the gap, is responsible for the spontaneous determination of the width of the nanogap. The calculation based on the model that involves the two competitive processes agrees with the experimental results on the activation process.

  3. Minimum emittance in electron storage rings with uniform or nonuniform dipoles.

    SciTech Connect

    Wang, C.-x.; Accelerator Systems Division

    2009-06-01

    A simple treatment of minimum emittance theory in storage rings is presented, favoring vector and matrix forms for a more concise picture. Both conventional uniform dipoles and nonuniform dipoles with bending radius variation are treated. Simple formulas are given for computing the minimum emittance, optimal lattice parameters, as well as effects of nonoptimal parameters. For nonuniform dipoles, analytical results are obtained for a three-piece sandwich dipole model. Minimization of the effective emittance for light sources is given in detail. Usefulness of gradient and/or nonuniform dipoles for reducing the effective emittance is addressed.

  4. Temperature dependence of photoluminescence spectra of nondoped and electron-doped SrTiO3: crossover from auger recombination to single-carrier trapping.

    PubMed

    Yamada, Yasuhiro; Yasuda, Hideki; Tayagaki, Takeshi; Kanemitsu, Yoshihiko

    2009-06-19

    We report unusual photoluminescence (PL) behaviors in highly photoexcited SrTiO(3) crystals at low temperatures. The PL spectrum and dynamics show abrupt changes below 150 K in both nondoped and electron-doped SrTiO(3) samples. We clarified that the PL dynamics in both nondoped and electron-doped SrTiO(3) is well described by the same simple model involving single-carrier trapping, radiative bimolecular recombination, and nonradiative Auger recombination. The unusual temperature dependence of PL dynamics is caused by the crossover from Auger recombination at high temperatures to single-carrier trapping at low temperatures. We discuss the temperature-dependent PL dynamics in conjunction with the high carrier mobility of SrTiO(3) at low temperatures.

  5. The effects of gas mixing and plasma electrode position on the emittance of an electron cyclotron resonance ion source

    NASA Astrophysics Data System (ADS)

    Suominen, P.; Tarvainen, O.; Koivisto, H.

    2004-05-01

    Gas mixing is a commonly used method to improve the intensities and the charge state distribution of ion beams extracted from an electron cyclotron resonance ion source (ECRIS). At the same time, the emittance of the ion beam should be as small as possible. In this work we have studied the effect of the gas mixing method on the ion beam quality by measuring the emittance and brightness of different ion beams using helium, oxygen, and argon with several gas feeding ratios. All measurements were performed with the JYFL 6.4 GHz ECRIS. At the second stage of the experiments the emittance and the ion beam brightness were studied as a function of the plasma electrode position. The extraction system constructed for this experiment can be moved online.

  6. 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.

  7. 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.

  8. 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.

  9. Nitrogen adsorption on supported size-selected tungsten nanoclusters as studied by X-ray photoelectron and X-ray excited Auger electron spectroscopies

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Wataru; Murakami, Junichi

    2003-09-01

    Adsorption states of nitrogen on tungsten pentamers supported on a highly oriented pyrolytic graphite surface have been investigated using X-ray photoelectron spectroscopy and X-ray excited Auger electron spectroscopy. An adsorption state that is not seen on a bulk polycrystalline tungsten surface was observed at temperatures below room temperature. It has been found that the adsorption state is a molecular state and is a precursor to dissociation of N 2 on the tungsten nanocluster.

  10. 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.

  11. 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.

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

    SciTech Connect

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

    1986-01-21

    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 lengthe 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.

  13. 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.

  14. Spatial distribution of Auger electrons emitted from internalised radionuclides in cancer cells: the photoresist autoradiography (PAR) method.

    PubMed

    Royle, G; Myhra, S; Chakalova, R; Vallis, K A; Falzone, N

    2015-09-01

    Microdosimetric evaluation of Auger electron-emitting radionuclides involves a detailed evaluation of energy deposition at a nanometre scale. To perform Monte Carlo modelling of such energy deposition, accurate information regarding the spatial distribution of the radionuclide is required. A recent addition to the methods for determining the spatial distribution of cellular internalised radionuclides is based on detection in a polymer photoresist (e.g. polymethyl methacralate), followed by atomic force microscopy analysis of the resultant 3D pattern. In comparison with present practice, the method offers greater spatial resolution and improved quantification. The volume of the pattern is proportional to the total dose, thereby permitting assessment of variability of accumulated activity, while the variation in depth across the pattern reflects the lateral spatial distribution in the local fluence per unit area. An added advantage is the similarity in response to ionising radiation of an organic polymer compared to that of biological material. A pattern in the resist from radiation emitted by a radionuclide treated cell gives additional spatial information about the energy deposited in the resist.

  15. Study on mechanism of selective chemical vapor deposition of tungsten using in situ infrared spectroscopy and Auger electron spectroscopy

    SciTech Connect

    Kobayashi, N.; Goto, H. ); Suzuki, M. )

    1991-01-15

    Selective chemical vapor deposition (CVD) of tungsten (W) using tungsten hexafluoride (WF{sub 6}) and monosilane (SiH{sub 4}) is investigated by {ital in} {ital situ} infrared spectroscopy and Auger electron spectroscopy. The infrared spectra show that trifluorosilane (SiHF{sub 3}) is the main by-product species, and that silicon-tetrafluoride (SiF{sub 4}) is less than 20%--25% of SiHF{sub 3} in partial pressure. The main chemical reaction involved in selective W CVD can be expressed as WF{sub 6}+2SiH{sub 4}{r arrow}W+2SiHF{sub 3}+3H{sub 2}. Based on our experimental results, a new mechanism of selective W CVD, which notes hydrogen dissociation having a central role in this process, is proposed. It disproves the widely accepted model, which is based on the assumption that SiF{sub 4} is the major reaction product.

  16. Auger electron spectroscopy investigation of degradation effect in GaAs metal-insulator-semiconductor solar cells

    SciTech Connect

    Pandelisev, K.A.; Wang, E.Y.

    1982-01-01

    Au-interfacial oxide layer (GeO/sub 2/, Sb/sub 2/O/sub 3/, Bi/sub 2/O/sub 3/, SnO/sub 2/ and native oxide mixture of AS/sub 2/O/sub 3/ and Ga/sub 2/O/sub 3/)-semiconductor (GaAs) structures were investigated by the Auger Electron Spectroscopy Method. The results of depth profiling with Ar/sup +/-ion sputtering are presented for all metal-insulator-semiconductor (MIS) structures. ''Metal'' atoms from deposited interfacial oxide layers (Ge from Ge/sub 2/O/sub 3/, Sb from Sb/sub 2/O/sub 3/, Bi from Bi/sub 2/O/sub 3/, and Sn from SnO/sub 2/) were observed on the surface. Only As atoms were observed for the native oxide mixture of As/sub 2/O/sub 3/ and Ga/sub 2/O/sub 3/ interfacial layer. These findings suggest that As/sub 2/O/sub 3/ is the dominating oxide at the metal-oxide interface for native oxide GaAs MIS solar cells. The interfacial reaction takes place between Au and the interfacial layer at room temperature. The ''diffusion'' of metal atoms from the interfacial layer towards the surface is suspected to play a role in degradation effect in GaAs MIS solar cells.

  17. Photoelectron and Auger electron diffraction studies of a sulfur-terminated GaAs(001)-(2×6) surface

    NASA Astrophysics Data System (ADS)

    Shimoda, M.; Tsukamoto, S.; Koguchi, N.

    1998-01-01

    Core-level X-ray photoelectron diffraction (XPD) and Auger electron diffraction (AED) have been applied to investigate the sulfur-terminated GaAs(001)-(2×6) surface. No forward scattering peaks were found in the XPD pattern of S 2s emission, indicating that adsorbed S atoms form a single layer on the GaAs substrate. In accordance with the zincblende structure of GaAs, the AED patterns of Ga L 3M 45M 45 and As L 3M 45M 45 emission almost coincide with each other, if one of the emissions is rotated by 90° around the [001] direction. This fact suggests that the diffraction patterns mainly reflect the structure of the bulk GaAs crystal. In order to investigate the surface structure, AED patterns in large polar angles were analyzed with single scattering cluster (SSC) calculations. The best result was obtained with a model cluster where the S-S bond length was set at 0.28 nm, 30% shorter than the corresponding length of the ideal (1×1) structure, and the adsorption height was set at 0.12-0.13 nm, 10% shorter than the ideal interlayer distance of GaAs(001) planes. These values are in good agreement with the results of STM measurements. A modulation of the inter-dimer distance was also found, suggesting the existence of missing dimers.

  18. Segregation Study of the β phase on the Al-Li Alloy Surface using Auger Electron Spectroscopy

    NASA Astrophysics Data System (ADS)

    Belkhiat, S.; Keraghel, F.

    2009-11-01

    Auger Electron spectroscopy (AES) has been used to study lithium segregation on Al-3.49wt%-Li alloy surface. In this work, the surface atomic composition as a function of temperature was followed. In our previous works, the activation energy of Li segregation has been determined experimentally being in agreement with the resulted theoretical value. In this paper, one showed that the segregation energy of Li on the surface depends of the crystalline structure and of the Li content in the Al-Li alloy matrix. β-AlLi phase on the alloy surface, used in the power sources for the propulsion of electrical vehicles and for stocking energy, is obtained by progressive heating. We showed that the segregated lithium on the alloy surface is reversible as a function of decreasing temperature and consequently β-AlLi phase is converted in α-AlLi phase. On the other hand, the brutal heating of the sample drives to the conversion of the α-AlLi phase to β-AlLi phase and stabilizes the surface towards other segregation; therefore the conversion of β-AlLi phase to α-AlLi phase is irreversible.

  19. Auger-electron diffraction in the low kinetic-energy range: The Si(111)7×7 surface reconstruction and Ge/Si interface formation

    NASA Astrophysics Data System (ADS)

    de Crescenzi, M.; Gunnella, R.; Bernardini, R.; de Marco, M.; Davoli, I.

    1995-07-01

    We have investigated the Auger-electron diffraction (AED) of the L2,3VV Auger line of the clean 7×7 reconstructed Si(111) surface and the Ge/Si interface formed after a few monolayers (ML) of Ge deposition. The experimental AED in the low kinetic-energy regime has been interpreted within the framework of a multiple-scattering theory. The comparison of the AED data taken using both the x-ray source and an electron source evidences that the incident beam plays a negligible role when the experimental conditions require the use of an angular detector. The evolution of the Ge/Si(111) interface is studied by monitoring the intensity anisotropy of the Auger peaks of the two elements at room temperature (RT) and at 400 °C annealing temperature of the substrate. The evolution of the growth mechanism underlying the Ge/Si interface formation has been studied by exploiting the very low electron escape depth of this technique (<=5 Å). While at RT two monolayers of Ge deposition appear uniform and amorphous, the successive annealing induces an intermixing and a recrystallization only in the first two layers of the interface without any further interdiffusion. Furthermore, a Stranski-Krastanow growth mode has been deduced after deposition of 4 ML of Ge on a clean Si sample kept at 400 °C.

  20. 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)

  1. Self-modulated field electron emitter: Gated device of integrated Si tip-on-nano-channel

    NASA Astrophysics Data System (ADS)

    Huang, Zhijun; Huang, Yifeng; Pan, Zhangxu; She, Juncong; Deng, Shaozhi; Chen, Jun; Xu, Ningsheng

    2016-12-01

    We report the featured gated field electron emission devices of Si nano-tips with individually integrated Si nano-channels and the interpretation of the related physics. A rational procedure was developed to fabricate the uniform integrated devices. The electrical and thermal conduction tests demonstrated that the Si nano-channel can limit both the current and heat flows. The integrated devices showed the specialties of self-enhancement and self-regulation. The heat resistance results in the heat accumulation at the tip-apex, inducing the thermally enhanced field electron emission. The self-regulated effect of the electrical resistance is benefit for impeding the current overloading and prevents the emitters from a catastrophic breakdown. The nano-channel-integrated Si nano-tip array exhibited emission current density up to 24.9 mA/cm2 at a gate voltage of 94 V, much higher than that of the Si nano-tip array without an integrated nano-channel.

  2. Enhanced field emission from compound emitters of carbon nanotubes and ZnO tetrapods by electron beam bombardment.

    PubMed

    Wei, Lei; Zhang, Xiaobing; Lou, Chaogang; Zhao, Zhiwei; Jing, Chen; Wang, Baoping

    2011-06-01

    The enhancement of field emission from compound emitters of carbon nanotubes and ZnO tetrapods by the electron beam bombardment is reported. After 20 minutes electron bombardment with 6 keV energy, a few bird-nest micro structures are formed in the compound emitters array. As the simulation results shown, the electric field and field emission current density at the tip of ZnO tetrapod are increased due to the influences of these bird-nest micro structures. From the measurement of the field emission performance, it can be seen that the turn-on electric field and threshold electric field of the field emitter array decrease to 0.4 V/microm and 2.4 V/microm respectively. They have decreased 62% and 15% after the electron bombardment. After the electron bombardment, the emission sites density is increased. The field emission images show that the uniformity of field emission has been improved obviously after the proper electron bombardment. The methodology proposed in this paper has a promising application in the field emission devices.

  3. 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.

  4. Electronic and geometric structure of thin CoO(100) films studied by angle-resolved photoemission spectroscopy and Auger electron diffraction

    NASA Astrophysics Data System (ADS)

    Heiler, M.; Chassé, A.; Schindler, K.-M.; Hollering, M.; Neddermeyer, H.

    2000-05-01

    We have prepared ordered thin films of CoO by evaporating cobalt in an O 2 atmosphere on to a heated (500 K) Ag(100) substrate. The geometric and electronic structure of the films was characterized by means of Auger electron diffraction (AED) and angle-resolved photoemission spectroscopy (ARUPS), respectively. The experimental AED results were compared with simulated data, which showed that the film grows in (100) orientation on the Ag(100) substrate. Synchrotron-radiation-induced photoemission investigations were performed in the photon energy range from 25 eV to 67 eV. The dispersion of the transitions was found to be similar to that of previous results on a single-crystal CoO(100) surface. The resonance behaviour of the photoemission lines in the valence-band region was investigated by constant-initial-state (CIS) spectroscopy. The implications of this behaviour for assignment of the photoemission lines to specific electronic transitions is discussed and compared with published theoretical models of the electronic structure.

  5. 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.

  6. 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.

  7. Monte Carlo-simulated Auger electron spectra for nuclides of radiobiological and medical interest - a validation with noble gas ionization data.

    PubMed

    Pomplun, Ekkehard

    2012-01-01

    To further validate Monte Carlo calculation codes simulating cascades of Auger electron transitions in radionuclides that decay by electron capture or internal conversion. In particular, the need for an appropriate kinetic energy determination of the Auger electrons emitted from multiple-ionized atoms as well as the consideration of shake-off electrons would be investigated implicitly. Charge distributions of noble gases after photoionization for different photon energies were calculated and compared with experimental data from the literature. In addition, new electron emission spectra were generated for (99m)Tc and (123)I. By including strict energy book-keeping and allowing shake-off electrons, the agreement between experimentally detected charge distributions and Monte Carlo simulations was very good. On this basis, the number of emitted electrons per decay was found to be between 1 and 17 with a mean of 4.0 for (99m)Tc and between 1 and 26 with a mean of 7.4 for (123)I. Because of the good agreement with the experimental findings, the validation can be considered to be successful.

  8. Trace-space reconstruction of low-emittance electron beams through betatron radiation in laser-plasma accelerators

    NASA Astrophysics Data System (ADS)

    Curcio, A.; Anania, M.; Bisesto, F.; Chiadroni, E.; Cianchi, A.; Ferrario, M.; Filippi, F.; Giulietti, D.; Marocchino, A.; Petrarca, M.; Shpakov, V.; Zigler, A.

    2017-01-01

    A new methodology able to model and reconstruct the transverse trace space of low-emittance electron beams accelerated in the bubble regime of laser-plasma interaction is presented. The single-shot measurement of both the electron energy spectrum and the betatron radiation spectrum is shown to allow a complete measurement of the transverse emittance, including the correlation term. A novel technique to directly measure the betatron oscillation amplitude distribution is described and tested at the SPARC-LAB test facility through the interaction of the ultrashort ultraintense Ti:Sa laser FLAME with a He gas-jet target. Via the exposed technique the beam transverse profile is also retrieved. From the study of the electron transverse dynamics inside the plasma bubble, the nonlinear correlation between the betatron amplitude and the divergence, i.e. the angle with respect the acceleration axis, is found. The angular distribution of the electron beam inside the bubble is retrieved. The knowledge of the trace-space density allows a more accurate measurement of the transverse emittance with respect to previous paradigms.

  9. Oxidation of In xGa 1- xAs yP 1- y by NO 2 studied with Auger electron spectroscopy

    NASA Astrophysics Data System (ADS)

    Bahr, C. C.; Paparazzo, E.; Moretto, L.; Lama, F.; Zema, N.

    1994-09-01

    We have studied the oxidation of quaternary InGaAsP materials by NO 2, using Auger electron spectroscopy for both elemental and chemical analysis of the surface. We report that NO 2 induces a preferential oxidation, forming oxides of Ga, In, and P. The As remains unoxidized. From Ar + ion milling we find that the oxide layers are fairly thin (less than 10 Å), even at high exposures (greater than 1000 L) of NO 2, where we obtain a saturation coverage of approximately 0.3 ML (monolayers). We have also measured electron energy loss spectra (EELS) and observe the disappearance of the surface plasmon loss feature upon oxide formation.

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

    SciTech Connect

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

    2016-05-09

    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/cm{sup 2}. 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.

  12. 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.

  13. Absorbed dose evaluation of Auger electron-emitting radionuclides: impact of input decay spectra on dose point kernels and S-values

    NASA Astrophysics Data System (ADS)

    Falzone, Nadia; Lee, Boon Q.; Fernández-Varea, José M.; Kartsonaki, Christiana; Stuchbery, Andrew E.; Kibédi, Tibor; Vallis, Katherine A.

    2017-03-01

    The aim of this study was to investigate the impact of decay data provided by the newly developed stochastic atomic relaxation model BrIccEmis on dose point kernels (DPKs - radial dose distribution around a unit point source) and S-values (absorbed dose per unit cumulated activity) of 14 Auger electron (AE) emitting radionuclides, namely 67Ga, 80mBr, 89Zr, 90Nb, 99mTc, 111In, 117mSn, 119Sb, 123I, 124I, 125I, 135La, 195mPt and 201Tl. Radiation spectra were based on the nuclear decay data from the medical internal radiation dose (MIRD) RADTABS program and the BrIccEmis code, assuming both an isolated-atom and condensed-phase approach. DPKs were simulated with the PENELOPE Monte Carlo (MC) code using event-by-event electron and photon transport. S-values for concentric spherical cells of various sizes were derived from these DPKs using appropriate geometric reduction factors. The number of Auger and Coster–Kronig (CK) electrons and x-ray photons released per nuclear decay (yield) from MIRD-RADTABS were consistently higher than those calculated using BrIccEmis. DPKs for the electron spectra from BrIccEmis were considerably different from MIRD-RADTABS in the first few hundred nanometres from a point source where most of the Auger electrons are stopped. S-values were, however, not significantly impacted as the differences in DPKs in the sub-micrometre dimension were quickly diminished in larger dimensions. Overestimation in the total AE energy output by MIRD-RADTABS leads to higher predicted energy deposition by AE emitting radionuclides, especially in the immediate vicinity of the decaying radionuclides. This should be taken into account when MIRD-RADTABS data are used to simulate biological damage at nanoscale dimensions.

  14. Absorbed dose evaluation of Auger electron-emitting radionuclides: impact of input decay spectra on dose point kernels and S-values.

    PubMed

    Falzone, Nadia; Lee, Boon Q; Fernández-Varea, José M; Kartsonaki, Christiana; Stuchbery, Andrew E; Kibédi, Tibor; Vallis, Katherine A

    2017-03-21

    The aim of this study was to investigate the impact of decay data provided by the newly developed stochastic atomic relaxation model BrIccEmis on dose point kernels (DPKs - radial dose distribution around a unit point source) and S-values (absorbed dose per unit cumulated activity) of 14 Auger electron (AE) emitting radionuclides, namely (67)Ga, (80m)Br, (89)Zr, (90)Nb, (99m)Tc, (111)In, (117m)Sn, (119)Sb, (123)I, (124)I, (125)I, (135)La, (195m)Pt and (201)Tl. Radiation spectra were based on the nuclear decay data from the medical internal radiation dose (MIRD) RADTABS program and the BrIccEmis code, assuming both an isolated-atom and condensed-phase approach. DPKs were simulated with the PENELOPE Monte Carlo (MC) code using event-by-event electron and photon transport. S-values for concentric spherical cells of various sizes were derived from these DPKs using appropriate geometric reduction factors. The number of Auger and Coster-Kronig (CK) electrons and x-ray photons released per nuclear decay (yield) from MIRD-RADTABS were consistently higher than those calculated using BrIccEmis. DPKs for the electron spectra from BrIccEmis were considerably different from MIRD-RADTABS in the first few hundred nanometres from a point source where most of the Auger electrons are stopped. S-values were, however, not significantly impacted as the differences in DPKs in the sub-micrometre dimension were quickly diminished in larger dimensions. Overestimation in the total AE energy output by MIRD-RADTABS leads to higher predicted energy deposition by AE emitting radionuclides, especially in the immediate vicinity of the decaying radionuclides. This should be taken into account when MIRD-RADTABS data are used to simulate biological damage at nanoscale dimensions.

  15. Effects of the electron-hole pair in Auger and X-ray photoemission spectroscopy from surfaces of Fe-Si

    NASA Astrophysics Data System (ADS)

    Gervasoni, J. L.; Jenko, M.; Poniku, B.; Belič, I.; Juan, A.

    2015-07-01

    In this work, we investigate in detail the effects due to the interaction between an electron and a stationary positive ion (or atomic hole) in the neighborhood of a surface of Fe-Si, having a strong plasmon peak in their electron energy loss spectra, when it is excited with synchrotron radiation. We take into account the effects due to the sudden creation of an electron and the residual holes, one in the case of X-ray photoemission spectroscopy (XPS) and two in the case of Auger electron spectroscopy (AES). We use a semi classical dielectric formulation for the photoelectron trajectory, and we estimated the parameter rs, the radius of the sphere occupied by one electron in the solid, which is critical in order to define the electron density of the alloy. With the cited formulation, we have obtained a detailed behavior of the different contributions of the collective excitations in both processes.

  16. Multilayered Thin Metal Film Deposition by Sequential Operation of Nanosilicon Electron Emitter in Metal-Salt Solutions

    NASA Astrophysics Data System (ADS)

    Ohta, Toshiyuki; Gelloz, Bernard; Koshida, Nobuyoshi

    2011-06-01

    The use of a nanocrystalline silicon (nc-Si) ballistic electron emitter in metal-salt solutions induces the deposition of thin metal films. The nc-Si emitter is composed of a thin Au/Ti film, an anodized polycrystalline Si layer, and an n+-Si substrate. When the emitter is driven in NiCl2, CoSO4, and ZnSO4 solutions without using any counter electrodes, thin Ni, Co, and Zn films are deposited on the emission area, respectively, as well as a thin Cu film in CuSO4 solution. According to cyclic voltammogram measurements under a standard three-electrode configuration, the hot electron injection effect into the solution is clearly observed in all cases at potentials within the electrochemical window, in which no electrolytic reactions occur. Energetic electrons injected into the solutions cause the direct reduction of metal ions. As a possible application, the multilayered deposition of different metals is demonstrated by sequential operation in NiCl2 and CuSO4 solutions.

  17. 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.

  18. 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 PAGES

    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

  19. 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.

  20. Observation of degradation processes of Al electrodes in organic electroluminescence devices by electroluminescence microscopy, atomic force microscopy, scanning electron microscopy, and Auger electron spectroscopy

    NASA Astrophysics Data System (ADS)

    Do, L. M.; Han, E. M.; Niidome, Y.; Fujihira, M.; Kanno, T.; Yoshida, S.; Maeda, A.; Ikushima, A. J.

    1994-11-01

    Degradation of top electrodes is one of the most important factors to determine the lifetimes of organic electroluminescence (EL) devices. An organic EL device (indium thin oxide (ITO/N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine (TPD)/tris(8-hydroxy-quinoline)aluminum (Al q(sub 3))/Al) was prepared and a morphological change of the Al top electrode was observed during and/or after applying voltage by atomic force microscopy and scanning electron microscopy (SEM). The change in the electrode surface, i.e., the increase in surface roughness was observed during the current flow. The degradation process started from faint dark core parts and propagated into disks with different rates depending on the magnitude of applied voltage. Degraded sites of the Al electrode, which were analyzed as aluminum oxide by Auger electron spectroscopy, protruded into the air on the organic layers. In SEM images of a life-end electrode, discontinuities due to crevasse formation in the organic layers sandwiched by the ITO base and the metal top electrodes were observed in many places. These results confirm that one of the most crucial factors of the degradation process was deformation of metal and organic layers due to heat, gas evolution, and oxidation caused by applied voltage.

  1. Integrated ZnO Nano-Electron-Emitter with Self-Modulated Parasitic Tunneling Field Effect Transistor at the Surface of the p-Si/ZnO Junction

    NASA Astrophysics Data System (ADS)

    Cao, Tao; Luo, Laitang; Huang, Yifeng; Ye, Bing; She, Juncong; Deng, Shaozhi; Chen, Jun; Xu, Ningsheng

    2016-09-01

    The development of high performance nano-electron-emitter arrays with well reliability still proves challenging. Here, we report a featured integrated nano-electron-emitter. The vertically aligned nano-emitter consists of two segments. The top segment is an intrinsically lightly n-type doped ZnO nano-tip, while the bottom segment is a heavily p-type doped Si nano-pillar (denoted as p-Si/ZnO nano-emitter). The anode voltage not only extracted the electron emission from the emitter apex but also induced the inter-band electron tunneling at the surface of the p-Si/ZnO nano-junction. The designed p-Si/ZnO emitter is equivalent to a ZnO nano-tip individually ballasted by a p-Si/ZnO diode and a parasitic tunneling field effect transistor (TFET) at the surface of the p-Si/ZnO junction. The parasitic TFET provides a channel for the supply of emitting electron, while the p-Si/ZnO diode is benefit for impeding the current overloading and prevent the emitters from a catastrophic breakdown. Well repeatable and stable field emission current were obtained from the p-Si/ZnO nano-emitters. High performance nano-emitters was developed using diamond-like-carbon coated p-Si/ZnO tip array (500 × 500), i.e., 178 μA (4.48 mA/cm2) at 75.7 MV/m.

  2. Integrated ZnO Nano-Electron-Emitter with Self-Modulated Parasitic Tunneling Field Effect Transistor at the Surface of the p-Si/ZnO Junction.

    PubMed

    Cao, Tao; Luo, Laitang; Huang, Yifeng; Ye, Bing; She, Juncong; Deng, Shaozhi; Chen, Jun; Xu, Ningsheng

    2016-09-22

    The development of high performance nano-electron-emitter arrays with well reliability still proves challenging. Here, we report a featured integrated nano-electron-emitter. The vertically aligned nano-emitter consists of two segments. The top segment is an intrinsically lightly n-type doped ZnO nano-tip, while the bottom segment is a heavily p-type doped Si nano-pillar (denoted as p-Si/ZnO nano-emitter). The anode voltage not only extracted the electron emission from the emitter apex but also induced the inter-band electron tunneling at the surface of the p-Si/ZnO nano-junction. The designed p-Si/ZnO emitter is equivalent to a ZnO nano-tip individually ballasted by a p-Si/ZnO diode and a parasitic tunneling field effect transistor (TFET) at the surface of the p-Si/ZnO junction. The parasitic TFET provides a channel for the supply of emitting electron, while the p-Si/ZnO diode is benefit for impeding the current overloading and prevent the emitters from a catastrophic breakdown. Well repeatable and stable field emission current were obtained from the p-Si/ZnO nano-emitters. High performance nano-emitters was developed using diamond-like-carbon coated p-Si/ZnO tip array (500 × 500), i.e., 178 μA (4.48 mA/cm(2)) at 75.7 MV/m.

  3. Integrated ZnO Nano-Electron-Emitter with Self-Modulated Parasitic Tunneling Field Effect Transistor at the Surface of the p-Si/ZnO Junction

    PubMed Central

    Cao, Tao; Luo, Laitang; Huang, Yifeng; Ye, Bing; She, Juncong; Deng, Shaozhi; Chen, Jun; Xu, Ningsheng

    2016-01-01

    The development of high performance nano-electron-emitter arrays with well reliability still proves challenging. Here, we report a featured integrated nano-electron-emitter. The vertically aligned nano-emitter consists of two segments. The top segment is an intrinsically lightly n-type doped ZnO nano-tip, while the bottom segment is a heavily p-type doped Si nano-pillar (denoted as p-Si/ZnO nano-emitter). The anode voltage not only extracted the electron emission from the emitter apex but also induced the inter-band electron tunneling at the surface of the p-Si/ZnO nano-junction. The designed p-Si/ZnO emitter is equivalent to a ZnO nano-tip individually ballasted by a p-Si/ZnO diode and a parasitic tunneling field effect transistor (TFET) at the surface of the p-Si/ZnO junction. The parasitic TFET provides a channel for the supply of emitting electron, while the p-Si/ZnO diode is benefit for impeding the current overloading and prevent the emitters from a catastrophic breakdown. Well repeatable and stable field emission current were obtained from the p-Si/ZnO nano-emitters. High performance nano-emitters was developed using diamond-like-carbon coated p-Si/ZnO tip array (500 × 500), i.e., 178 μA (4.48 mA/cm2) at 75.7 MV/m. PMID:27654068

  4. Study of Submonolayer Films of GOLD/COPPER(100) and PALLADIUM/COPPER(100) Using Positron Annihilation Induced Auger Electron Spectroscopy

    NASA Astrophysics Data System (ADS)

    Lee, Keunho

    Positron Annihilation induced Auger Electron Spectroscopy (PAES), Electron induced Auger Electron Spectroscopy (EAES), and Low Energy Electron Diffraction (LEED) have been used to study the surface composition, surface alloying and overlayer formation of ultrathin films of Au and Pd on Cu(100). This is the first systematic application of PAES to the study of the surface properties of ultrathin layers of metals on metal substrates. Temperature induced changes in the top layer surface compositions in Au/Cu(100) and Pd/Cu(100) are directly observed using PAES, while EAES spectra indicate only minor changes. The surface alloying of the Au/Cu(100) and Pd/Cu(100) systems are demonstrated using PAES in conjunction with LEED. The PAES intensity measurements also provide evidence for positron trapping at surface defects such as steps, kinks and isolated adatoms. The PAES intensity was found to be strongly dependent on surface defects introduced by ion sputtering. The surface defect dependence of the PAES intensity is interpreted in terms of the surface atomic diffusion and positron trapping at surface defects in Au/Cu(100) and Pd/Cu(100). In both systems the shapes of the PAES intensity versus coverage curves for submonolayer coverages at 173K are quite distinct indicating differences in overlayer growth and diffusion behavior of Au and Pd adatoms on the Cu(100) surface. PAES intensities for both Au and Pd are saturated at 1 monolayer demonstrating the extreme surface selectivity of PAES.

  5. Bond breaking, electron pushing, and proton pulling: active and passive roles in the interaction between aqueous ions and water as manifested in the O 1s Auger decay.

    PubMed

    Pokapanich, W; Ottosson, N; Svensson, S; Ohrwall, G; Winter, B; Björneholm, O

    2012-01-12

    A core-ionized H(2)O molecule in liquid water primarily relaxes through normal Auger decay, leading to a two-hole final state in which both valence holes are localized on the same water molecule. Electronic coupling to the environment, however, allows for alternative decays resembling Intermolecular Coulombic Decay (ICD), producing final states with one of the holes delocalized on a neighboring water molecule. Here we present an experimental study of such minority processes, which adds to our understanding of dynamic interactions of electronically excited H(2)O molecules with their local surrounding in liquid water and aqueous solution. We show that the solvation of metal-halide salts considerably influences these minority decay channels from the water O 1s(-1) state. By breaking water-water bonds, both the metal cations and halide anions are found to reduce the decay into water-water delocalized states, thus having a ″passive″ effect on the Auger spectrum. The halide anions also play an ″active″ role by opening a new ICD-like decay pathway into water-halide delocalized states. The importance of this contribution increases from F(-) to I(-), which we suggest to be caused by a directional polarization of the halide anion toward the core-ionized H(2)O(+) cation in the intermediate state of the Auger process. This increases the electronic overlap between the two centers and makes delocalized decays more probable. We furthermore show that F(-), the smallest and most strongly hydrated of the halides, plays an additional role as proton puller during the core-hole lifetime, resulting in proton dynamics on the low femtosecond time scale. Our results represent a step forward toward a better understanding of how aqueous solutions, when exposed to soft X-rays, channel excess energy. This has implications for several aspects of physical and radiation chemistry, as well as biology.

  6. 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.

  7. Double Emittance Exchanger as a Bunch Compressor for the MaRIE XFEL electron beam line at 1GeV

    SciTech Connect

    Malyzhenkov, Alexander; Yampolsky, Nikolai; Carlsten, Bruce Eric

    2016-09-22

    We demonstrate an alternative realization of a bunch compressor (specifically the second bunch compressor for the MaRIE XFEL beamline, 1GeV electron energy) using a double emittance exchanger (EEX) and a telescope in the transverse phase space.We compare our results with a traditional bunch compressor realized via chicane, taking into account the nonlinear dynamics, Coherent Synchrotron Radiation (CSR) and Space Charge (SC) effects. In particular, we use the Elegant code for tracking particles through the beam line and analyze the eigen-emittances evolution to separate the influence of the CSR/SC effects from the nonlinear dynamics effects. We optimize the scheme parameters to reach a desirable compression factor and minimize the emittance growth. We observe dominant CSR-effects in our scheme resulting in critical emittance growth and introduce alternative version of an emittance exchanger with a reduced number of bending magnets to minimize the impact of CSR effects.

  8. Double emittance exchanger as a bunch compressor for the MaRIE XFEL electron beam line at 1 GeV

    NASA Astrophysics Data System (ADS)

    Malyzhenkov, Alexander; Carlsten, Bruce E.; Yampolsky, Nikolai A.

    2017-03-01

    We demonstrate an alternative realization of a bunch compressor (specifically, the second bunch compressor for the MaRIE XFEL beamline, 1GeV electron energy) using a double emittance exchanger (EEX) and a telescope in the transverse phase space. We compare our results with a traditional bunch compressor realized via a chicane, taking into account the nonlinear dynamics, Coherent Synchrotron Radiation (CSR) and Space Charge (SC) effects. In particular, we use the Elegant code for tracking particles through the beamline, and analyze the evolution of the eigen-emittances to separate the influence of the CSR/SC effects from the nonlinear dynamics effects. We optimize the scheme parameters to reach a desirable compression factor and minimize the emittance growth. We observe dominant CSR effects in our scheme, resulting in critical emittance growth, and introduce an alternative version of an emittance exchanger with a reduced number of bending magnets to minimize the impact of CSR effects.

  9. 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.

  10. Structure analysis of the single-domain Si(111)4 × 1-In surface by μ-probe Auger electron diffraction and μ-probe reflection high energy electron diffraction

    NASA Astrophysics Data System (ADS)

    Nakamura, N.; Anno, K.; Kono, S.

    1991-10-01

    A single-domain Si(111)4 × 1-In surface has been studied by μ-probe reflection high-energy electron diffraction (RHEED) to elucidate the symmetry of the 4 × 1 surface. Azimuthal diffraction patterns of In MNN Auger electron have been obtained by a μ-probe Auger electron diffraction (AED) apparatus from the single-domain Si(111)4 × 1-In surface. On the basis of information from scanning tunneling microscopy [J. Microsc. 152 (1988) 727] and under the assumption that the 4 × 1 surface is composed of In-overlayers, the μ-probe AED patterns were kinematically analyzed to reach a concrete model of indium arrangement.

  11. Auger Intensity from Si(001)2×2-Al Surface Excited by Wave-Field in Medium-Energy Electron Diffraction

    NASA Astrophysics Data System (ADS)

    Horio, Yoshimi; Sakai, Daisuke

    2009-06-01

    From dynamical analysis of rocking curves from both reflection high-energy electron diffraction (RHEED) and medium-energy electron diffraction (MEED), the surface of Si(001)2×2-Al was confirmed to have a parallel-dimer structure. Furthermore, dynamical calculation, usually used to determine RHEED intensity, was confirmed to also be effective for the calculation of MEED intensity. The incident electron density distribution, or “wave-field”, was calculated for MEED conditions on the basis of the surface structure model. The wave-field at the surface is very sensitive to changes in diffraction conditions, such as the incident glancing angle. The Al(LMM) Auger electron intensity emitted from the Si(001)2×2-Al surface during MEED correlated to the wave-field intensity on the Al atomic rows relatively well.

  12. 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.

  13. Effect of vacuum annealing on the surface chemistry of electrodeposited copper(I) oxide layers as probed by positron annihilation induced auger electron spectroscopy.

    PubMed

    Nadesalingam, M P; Mukherjee, S; Somasundaram, S; Chenthamarakshan, C R; de Tacconi, Norma R; Rajeshwar, Krishnan; Weiss, A H

    2007-02-13

    Vacuum anneal induced changes in the surface layers of electrodeposited copper(I) oxide (Cu2O) were probed by time-of-flight positron annihilation induced Auger electron spectroscopy (TOF-PAES) and by electron induced Auger electron spectroscopy (EAES). Large changes in the intensity of the Cu PAES intensity resulting from isochronal in situ vacuum anneals made at increasing temperatures indicated that, before thermal treatment, the surface was completely covered by a carbonaceous overlayer and that this layer was removed, starting at a temperature between 100 and 200 degrees C, to expose an increasing amount of Cu in the top layer as the anneal temperature was increased. The thickness of this overlayer was estimated to be approximately 4 A based on analysis of the EAES data, and its variation with the thermal anneal temperature was mapped. This study demonstrated the order-of-magnitude enhancement in the sensitivity of PAES to the topmost surface layer in Cu2O relative to the EAES counterpart; factors underlying this contrast are discussed. Finally, the implications of ultrathin carbon layers on semiconductor surfaces are discussed.

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

    SciTech Connect

    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.

  15. Emittance growth of an electron beam in a periodic focusing channel due to transfer of longitudinal energy to transverse energy

    SciTech Connect

    Carlsten, B.E.

    1998-12-31

    Most discussions about emittance growth and halo production for an intense electron beam in a periodic focusing channel assume that the total transverse energy is constant (or, in other words, that the transverse and longitudinal Hamiltonians are separable). Previous analyses that include variations in the total transverse energy are typically based on a transverse-longitudinal coupling that is either from two-dimensional space-charge modes or particle-particle Coulomb collisions. With the space-charge modes, the energy exchange between the transverse and longitudinal directions is periodic, and of constant magnitude. The total energy transfer for the case of the Coulomb collisions is negligible. This limited increase of energy in the transverse direction from these other effects will limit the amount of transverse emittance growth possible. In this paper, the authors investigate a mechanism in which there is a continual transfer of energy from the longitudinal direction to the transverse direction, leading to essentially unlimited potential transverse emittance growth. This mechanism is caused by an asymmetry of the beam`s betatron motion within the periodic focusing elements. This analysis is based on thermodynamic principles. This mechanism exists for both solenoids and quadrupole focusing, although only solenoid focusing is studied here.

  16. 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.

  17. 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.

  18. Characterization of zirconium carbides using electron microscopy, optical anisotropy, Auger depth profiles, X-ray diffraction, and electron density calculated by charge flipping method

    SciTech Connect

    Chinthaka Silva, G.W.; Kercher, Andrew A.; Hunn, John D.; Martin, Rodger C.; Jellison, Gerald E.; Meyer, Harry M.

    2012-10-15

    Samples with five different zirconium carbide compositions (C/Zr molar ratio=0.84, 0.89, 0.95, 1.05, and 1.17) have been fabricated and studied using a variety of experimental techniques. Each sample was zone refined to ensure that the end product was polycrystalline with a grain size of 10-100 {mu}m. It was found that the lattice parameter was largest for the x=0.89 composition and smallest for the x=1.17 total C/Zr composition, but was not linear; this nonlinearity is possibly explained using electron densities calculated using charge flipping technique. Among the five samples, the unit cell of the ZrC{sub 0.89} sample showed the highest electron density, corresponding to the highest carbon incorporation and the largest lattice parameter. The ZrC{sub 0.84} sample showed the lowest carbon incorporation, resulting in a larger number of carbon vacancies and resultant strain. Samples with larger carbon ratios (x=0.95, 1.05, and 1.17) showed a slight decrease in lattice parameter, due to a decrease in electron density. Optical anisotropy measurements suggest that these three samples contained significant amounts of a graphitic carbon phase, not bonded to the Zr atoms. - Graphical abstract: Characterization of zirconium carbides using electron microscopy, optical anisotropy, Auger depth profiles, X-ray diffraction, and electron density calculated by the charge flipping method. Highlights: Black-Right-Pointing-Pointer The lattice parameter variation: ZrC{sub 0.89}>ZrC{sub 0.84}>ZrC{sub 0.95}>ZrC{sub 1.05}>ZrC{sub 1.17}. Black-Right-Pointing-Pointer Surface oxygen with no correlation to the lattice parameter variation. Black-Right-Pointing-Pointer ZrC{sub 0.89} had highest electron densities correspond to highest carbon incorporation. Black-Right-Pointing-Pointer Second highest lattice parameter in ZrC{sub 0.84} due to strain. Black-Right-Pointing-Pointer Unit cell electron density order: ZrC{sub 0.95}>ZrC{sub 1.05}>ZrC{sub 1.17}.

  19. 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.

  20. Electronic structure studies of Ni-X (X: B, S, P) alloys using x-ray photoelectron spectroscopy, x-ray induced Auger electron spectroscopy and density functional theory calculations.

    PubMed

    Diplas, S; Løvvik, O M

    2009-06-17

    The electronic structure of Ni-X (X = B, S, P) alloys was studied using x-ray photoelectron spectroscopy, x-ray induced Auger electron spectroscopy and density functional theory. The spectroscopic data in the form of the Ni 2p shake-up satellite and the Ni 2p LMM, P 2p KLL and S 2p KLL Auger parameters combined with density of states (DOS) and charge difference plots suggest an overall charge transfer from the Ni sites towards the alloying addition sites. However, this is masked, with intra-atomic charge redistribution leading to an increased occupancy of the Ni 3d states in the alloys. The Ni 3d DOS shows strong similarity to that of Pt which is the best catalyst for hydrogen evolution.

  1. 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.

  2. 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.

  3. Surface-site-selective study of valence electronic states of a clean Si(111)-7x7 surface using Si L{sub 23}VV Auger electron and Si 2p photoelectron coincidence measurements

    SciTech Connect

    Kakiuchi, Takuhiro; Tahara, Masashi; Nagaoka, Shin-ichi; Hashimoto, Shogo; Fujita, Narihiko; Tanaka, Masatoshi; Mase, Kazuhiko

    2011-01-15

    Valence electronic states of a clean Si(111)-7x7 surface are investigated in a surface-site-selective way using high-resolution coincidence measurements of Si pVV Auger electrons and Si 2p photoelectrons. The Si L{sub 23}VV Auger electron spectra measured in coincidence with energy-selected Si 2p photoelectrons show that the valence band at the highest density of states in the vicinity of the rest atoms is shifted by {approx}0.95 eV toward the Fermi level (E{sub F}) relative to that in the vicinity of the pedestal atoms (atoms directly bonded to the adatoms). The valence-band maximum in the vicinity of the rest atoms, on the other hand, is shown to be shifted by {approx}0.53 eV toward E{sub F} relative to that in the vicinity of the pedestal atoms. The Si 2p photoelectron spectra of Si(111)-7x7 measured in coincidence with energy-selected Si L{sub 23}VV Auger electrons identify the topmost surface components, and suggest that the dimers and the rest atoms are negatively charged while the pedestal atoms are positively charged. Furthermore, the Si 2p-Si L{sub 23}VV photoelectron Auger coincidence spectroscopy directly verifies that the adatom Si 2p component (usually denoted by C{sub 3}) is correlated with the surface state just below E{sub F} (usually denoted by S{sub 1}), as has been observed in previous angle-resolved photoelectron spectroscopy studies.

  4. 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.

  5. 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.

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

    SciTech Connect

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

    2016-02-15

    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.

  7. 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.

  8. 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.

  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. 2s photoionization and subsequent Auger cascade in atomic Si

    SciTech Connect

    Partanen, L.; Fritzsche, S.; Jaenkaelae, K.; Huttula, M.; Osmekhin, S.; Aksela, H.; Aksela, S.; Urpelainen, S.

    2010-06-15

    The 2s photoionization and subsequent Auger transition cascade in atomic Si were studied by means of synchrotron-radiation-induced electron spectroscopy. After the 2s photoionization, the core hole states decay predominantly by a two-step Auger transition cascade into the triply ionized [Ne]nl states. The ionization channels of the 2s core-ionized Si{sup +} atoms to Si{sup 3+} ions were observed by measuring the conventional Auger electron spectra of the L{sub 1}-L{sub 2,3}M Coster-Kronig transitions and the L{sub 2,3}M-MMM Auger transitions. The observed L{sub 1}-L{sub 2,3}M and L{sub 2,3}M-MMM Auger spectra were analyzed by means of extensive multiconfiguration Dirac-Fock computations. We found that the electron correlation plays a prominent role in the Auger cascade, especially for the final-step Auger L{sub 2,3}M-MMM spectrum. Additionally, it was seen that the L{sub 2,3}M-MMM Auger spectrum of Si includes more Auger groups than the isoelectronic L{sub 2,3}-MM Auger spectrum of Al. Thus, more information on the intermediate ionic states is obtained if they are produced by Auger cascade rather than by direct photoionization.

  11. 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

  12. Auger Radiopharmaceutical Therapy Targeting Prostate-Specific Membrane Antigen.

    PubMed

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

    2015-09-01

    Auger electron emitters such as (125)I 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 (125)I to prostate cancer cells. The PSMA-targeting Auger emitter 2-[3-[1-carboxy-5-(4-(125)I-iodo-benzoylamino)-pentyl]-ureido]-pentanedioic acid ((125)I-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 (125)I-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 (125)I-DCIBzL, 111 MBq (3 mCi) of (125)I-NaI, an equivalent amount of nonradiolabeled DCIBzL, or saline. After treatment with (125)I-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 (125)I-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). PSMA-targeted radiopharmaceutical therapy with the Auger emitter (125)I-DCIBzL yielded highly specific antitumor efficacy in vivo, suggesting promise for treatment of prostate cancer micrometastases. © 2015 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

  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. Pierre Auger--a life in the service of science.

    PubMed

    Persson, L

    1996-01-01

    A short biography of Pierre Auger, the discoverer of the atomic auger electron effect, is given. Professor Auger's outstanding professional career covered physics, nuclear power and space research, organization and administration of research, diplomatic services and pedagogics but also extended into modern biology, humanistic sciences, poetry and arts. Part of a speech in Paris of professor Auger held in 1989 on the theme 'Research and Creativity' at an international symposium on the auger effect is included in this biography as well as one of his poems.

  15. 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.

  16. Making use of x-ray optical effects in photoelectron-, Auger electron-, and x-ray emission spectroscopies: Total reflection, standing-wave excitation, and resonant effects

    SciTech Connect

    Yang, S.-H.; Gray, A. X.; Kaiser, A. M.; Mun, B. S.; Sell, B. C.; Kortright, J. B.; Fadley, C. S.

    2013-02-21

    We present a general theoretical methodology and related open-access computer program for carrying out the calculation of photoelectron, Auger electron, and x-ray emission intensities in the presence of several x-ray optical effects, including total reflection at grazing incidence, excitation with standing-waves produced by reflection from synthetic multilayers and at core-level resonance conditions, and the use of variable polarization to produce magnetic circular dichroism. Calculations illustrating all of these effects are presented, including in some cases comparisons to experimental results. Sample types include both semi-infinite flat surfaces and arbitrary multilayer configurations, with interdiffusion/roughness at their interfaces. These x-ray optical effects can significantly alter observed photoelectron, Auger, and x-ray intensities, and in fact lead to several generally useful techniques for enhancing surface and buried-layer sensitivity, including layer-resolved densities of states and depth profiles of element-specific magnetization. The computer program used in this study should thus be useful for a broad range of studies in which x-ray optical effects are involved or are to be exploited in next-generation surface and interface studies of nanoscale systems.

  17. Auger electron spectroscopy study of interdiffusion, oxidation and segregation during thermal treatment of NiCr/CuNi(Mn)/NiCr thin films

    NASA Astrophysics Data System (ADS)

    Baunack, S.; Brückner, W.; Pitschke, W.; Thomas, J.

    1999-04-01

    The effect of annealing on sputter deposited thin-films NiCr/CuNi(Mn)/NiCr is studied by Auger electron depth profiling. The samples were annealed to maximum temperatures of 300°C to 550°C and investigated at ambient temperature. Auger transitions of Cu and Ni are separated by target factor analysis, principal component analysis and linear least squares fit to standard spectra. For the CuNi(Mn) layer in the as-received state AES results shows a Cu depletion caused by bombardment induced segregation. After annealing the measured Cu concentration has increased due to Ni diffusion to the interfaces. The NiCr layer is degraded with increasing annealing temperature due to formation of a chromium oxide and diffusion of Ni from the CuNi(Mn) layer. A sequence with nominal compositions near Cr 2Ni, CrNi and CrNi 2 is found. At the NiCr/CuNi(Mn) interface an interdiffusion zone phase Ni 0.6Cr 0.2Cu 0.2 is formed.

  18. Multielectron spectroscopy: the xenon 4d hole double auger decay.

    PubMed

    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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

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

    NASA Astrophysics Data System (ADS)

    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.

  6. Time-Resolved Electron Paramagnetic Resonance and Theoretical Investigations of Metal-Free Room-Temperature Triplet Emitters.

    PubMed

    Matsuoka, Hideto; Retegan, Marius; Schmitt, Lisa; Höger, Sigurd; Neese, Frank; Schiemann, Olav

    2017-09-20

    Utilization of triplets is important for preparing organic light-emitting diodes with high efficiency. Very recently, both electrophosphorescence and electrofluorescence could be observed at room temperature for thienyl-substituted phenazines without any heavy metals ( Ratzke et al. J. Phys. Chem. Lett. , 2016 , 7 , 4802 ). It was found that the phosphorescence efficiency depends on the orientation of fused thiophenes. In this work, the thienyl-substituted phenazines are investigated in more detail by time-resolved electron paramagnetic resonance (EPR) and quantum chemical calculations. Spin dynamics, zero-field splitting constants, and electron-spin structures of the excited triplet states for the metal-free room-temperature triplet emitters are correlated with phosphorescence efficiency. Complete active space self-consistent field (CASSCF) calculations clearly show that the electron spin density distributions of the first excited triplet states are strongly affected by the molecular geometry. For the phosphorescent molecules, the electron spins are localized on the phenazine unit, in which the sulfur atom of the fused thiophene points upward. The electron spins are delocalized onto the thiophene unit just by changing the orientation of the fused thiophenes from upward to downward, resulting in the suppression of phosphorescence. Time-resolved EPR measurements and time-dependent density functional theory (TD-DFT) calculations demonstrate that the electron spins delocalized onto the thiophene unit lead to the acceleration of nonradiative decays, in conjunction with the narrowing of the singlet-triplet energy gap.

  7. 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.

  8. Study of grain boundary segregation using the Auger electron emission technique. Annual Technical Progress Report January 1, 1979-December 31, 1979

    SciTech Connect

    Stein, D. F.; Heldt, L. A.; Funkenbusch, A. W.

    1980-01-01

    The influence of grain boundary chemical composition on hydrogen embrittlement was investigated. Auger electron spectroscopy was employed to determine the grain boundary compositions of nickel-copper alloys containing various concentrations of phosphorus and subjected to various thermal treatments. Phosphorus segregates to grain boundaries during slow cooling, accompanied by reduced concentrations of grain boundary copper. Tensile tests were conducted in air and following cathodic charging with hydrogen. All samples tested in air exhibited a completely ductile fracture; ductility was insensitive to grain boundary composition. Fractures of hydrogen-charged samples were brittle and intergranular; elongation to fracture increased significantly with increasing concentration of grain boundary phosphorus. The influence of phosphorus segregation on embrittlement by hydrogen or by mercury (reported previously) is analyzed in terms of additive and interactive mechanisms. A mechanism based on reduced embrittler concentration at the site of bond rupture due to improved atomic packing is proposed and found to be consistent with the experimental results of this and other investigations.

  9. 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.

  10. Direct observation of the surface segregation of Cu in Pd by time-resolved positron-annihilation-induced Auger electron spectroscopy.

    PubMed

    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 τ=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.

  11. 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.

  12. 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.

  13. 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.

  14. Manipulating the Electronic Excited State Energies of Pyrimidine-Based Thermally Activated Delayed Fluorescence Emitters To Realize Efficient Deep-Blue Emission.

    PubMed

    Komatsu, Ryutaro; Ohsawa, Tatsuya; Sasabe, Hisahiro; Nakao, Kohei; Hayasaka, Yuya; Kido, Junji

    2017-02-08

    The development of efficient and robust deep-blue emitters is one of the key issues in organic light-emitting devices (OLEDs) for environmentally friendly, large-area displays or general lighting. As a promising technology that realizes 100% conversion from electrons to photons, thermally activated delayed fluorescence (TADF) emitters have attracted considerable attention. However, only a handful of examples of deep-blue TADF emitters have been reported to date, and the emitters generally show large efficiency roll-off at practical luminance over several hundreds to thousands of cd m(-2), most likely because of the long delayed fluorescent lifetime (τd). To overcome this problem, we molecularly manipulated the electronic excited state energies of pyrimidine-based TADF emitters to realize deep-blue emission and reduced τd. We then systematically investigated the relationships among the chemical structure, properties, and device performances. The resultant novel pyrimidine emitters, called Ac-XMHPMs (X = 1, 2, and 3), contain different numbers of bulky methyl substituents at acceptor moieties, increasing the excited singlet (ES) and triplet state (ET) energies. Among them, Ac-3MHPM, with a high ET of 2.95 eV, exhibited a high external quantum efficiency (ηext,max) of 18% and an ηext of 10% at 100 cd m(-2) with Commission Internationale de l'Eclairage chromaticity coordinates of (0.16, 0.15). These efficiencies are among the highest values to date for deep-blue TADF OLEDs. Our molecular design strategy provides fundamental guidance to design novel deep-blue TADF emitters.

  15. 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.

  16. 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.

  17. Extraction Simulations and Emittance Measurements of a Holifield Radioactive Ion Beam Facility Electron Beam Plasma Source for Radioactive Ion Beams

    SciTech Connect

    Mendez, II, Anthony J; Liu, Yuan

    2010-01-01

    The Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratory has a variety of ion sources used to produce radioactive ion beams (RIBs). Of these, the workhorse is an electron beam plasma (EBP) ion source. The recent addition of a second RIB injector, the Injector for Radioactive Ion Species 2 (IRIS2), for the HRIBF tandem accelerator prompted new studies of the optics of the beam extraction from the EBP source. The source was modeled using SIMION V8.0, and results will be presented, including comparison of the emittances as predicted by simulation and as measured at the HRIBF offline ion source test facilities. Also presented will be the impact on phase space shape resulting from extraction optics modifications implemented at IRIS2.

  18. The LVV Auger line shape of sulfur on copper studied by Auger photoelectron coincidence spectroscopy.

    PubMed

    Di Filippo, G; Trioni, M I; Fratesi, G; Schumann, F O; Wei, Z; Li, C H; Behnke, L; Patil, S; Kirschner, J; Stefani, G

    2015-03-04

    We have studied the line shapes of Cu(0 0 1)-p (2 × 2)S L2VV and L3VV Auger decay by means of Auger photoelectron coincidence spectroscopy. Measuring the LVV Auger spectrum in coincidence with S 2p1/2 and 2p3/2 photoelectrons respectively, we have been able to separate the two overlapping Auger spectra and determine their intrinsic line shapes. The two Auger transitions, though shifted in energy, display an identical line shape whose main features can be qualitatively understood considering a single particle approximation but are better described within a Cini-Sawatzky (CS) approach. Comparison between the experimental and the CS calculated spectra confirms that a substantial part of the Auger lines (∼20%) can be ascribed to decay events accompanied by the excitation of one additional electron-hole pair in the valence band. For the first time, the locality of the Auger process combined with the surface sensitivity of the APECS technique and its ability to separate overlapping structures are used to study Auger transitions taking place at the the surface states of a S/noble-metal interface.

  19. 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

    2016-07-08

    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.

  20. 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.

  1. 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.

  2. 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.

  3. Controlled growth of carbon nanotube-graphene hybrid materials for flexible and transparent conductors and electron field emitters

    NASA Astrophysics Data System (ADS)

    Nguyen, Duc Dung; Tai, Nyan-Hwa; Chen, Szu-Ying; Chueh, Yu-Lun

    2012-01-01

    We report a versatile synthetic process based on rapid heating and cooling chemical vapor deposition for the growth of carbon nanotube (CNT)-graphene hybrid materials where the thickness of graphene and density of CNTs are properly controlled. Graphene films are demonstrated as an efficient barrier layer for preventing poisoning of iron nanoparticles, which catalyze the growth of CNTs on copper substrates. Based on this method, the opto-electronic and field emission properties of graphene integrated with CNTs can be remarkably tailored. A graphene film exhibits a sheet resistance of 2.15 kΩ sq-1 with a transmittance of 85.6% (at 550 nm), while a CNT-graphene hybrid film shows an improved sheet resistance of 420 Ω sq-1 with an optical transmittance of 72.9%. Moreover, CNT-graphene films are demonstrated as effective electron field emitters with low turn-on and threshold electric fields of 2.9 and 3.3 V μm-1, respectively. The development of CNT-graphene films with a wide range of tunable properties presented in this study shows promising applications in flexible opto-electronic, energy, and sensor devices.

  4. Controlled growth of carbon nanotube-graphene hybrid materials for flexible and transparent conductors and electron field emitters.

    PubMed

    Nguyen, Duc Dung; Tai, Nyan-Hwa; Chen, Szu-Ying; Chueh, Yu-Lun

    2012-01-21

    We report a versatile synthetic process based on rapid heating and cooling chemical vapor deposition for the growth of carbon nanotube (CNT)-graphene hybrid materials where the thickness of graphene and density of CNTs are properly controlled. Graphene films are demonstrated as an efficient barrier layer for preventing poisoning of iron nanoparticles, which catalyze the growth of CNTs on copper substrates. Based on this method, the opto-electronic and field emission properties of graphene integrated with CNTs can be remarkably tailored. A graphene film exhibits a sheet resistance of 2.15 kΩ sq(-1) with a transmittance of 85.6% (at 550 nm), while a CNT-graphene hybrid film shows an improved sheet resistance of 420 Ω sq(-1) with an optical transmittance of 72.9%. Moreover, CNT-graphene films are demonstrated as effective electron field emitters with low turn-on and threshold electric fields of 2.9 and 3.3 V μm(-1), respectively. The development of CNT-graphene films with a wide range of tunable properties presented in this study shows promising applications in flexible opto-electronic, energy, and sensor devices.

  5. 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.

  6. 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.

  7. The characterization of secondary electron emitters for use in large area photo-detectors.

    SciTech Connect

    Jokela, S. J.; Veryovkin, I. V.; Zinovev, A. V.; Frisch, H. J.; Elam, J. W.; Peng, Q.; Mane, A. U.

    2011-06-01

    The Large-Area Picosecond Photo-Detector Project is focused on the development of large-area systems to measure the time-of-arrival of relativistic particles with, ultimately, 1 pico-second resolution, and for signals typical of Positron-Emission Tomography (PET), a resolution of about 30 pico-seconds. Our contribution to this project is to help with identification and efficient fabrication of novel electron emitting materials with properties optimized for use in such detectors. We have assembled several techniques into a single ultra-high vacuum apparatus in order to enable characterization of both photocathode and secondary electron emission (SEE) materials. This apparatus will examine how photocathode quantum efficiency and SEE material electron yield correlate to surface chemical composition, state, and band structure. The techniques employed in this undertaking are X-ray photoelectron spectroscopy (XPS) for surface chemical composition, ultraviolet photoelectron spectroscopy (UPS) for the determination of band structure and surface work function, as well surface cleaning techniques such as argon-ion sputtering. To determine secondary electron emission yields and quantum efficiencies of detector materials, we use electron optics from a low energy electron diffraction (LEED) system whose set of hemispherical electrodes allows for efficient collection of secondary and photo electrons. As we gain a stronger insight into the details of mechanisms of electron emission from photocathodes and SEE materials, we will be able to lay a foundation for the larger collaborative effort to design the next generation of large-area photo-detectors. We present our preliminary results on the SEE materials from our as-yet completed characterization system.

  8. Real-time simulation of finite-frequency noise from a single-electron emitter

    NASA Astrophysics Data System (ADS)

    Jonckheere, T.; Stoll, T.; Rech, J.; Martin, T.

    2012-01-01

    We study the real-time emission of single electrons from a quantum dot coupled to a one dimensional conductor, using exact diagonalization on a discrete tight-binding chain. We show that, from the calculation of the time evolution of the one-electron states, we have simple access to all the relevant physical quantities in the system. In particular, we are able to compute accurately the finite-frequency current autocorrelation noise. The method that we use is general and versatile, allowing us to study the impact of many different parameters, such as the dot transparency or level position. Our results can be directly compared with existing experiments, and can also serve as a basis for future calculations including electronic interactions using the time-dependent density-matrix renormalization group and other techniques based on tight-binding models.

  9. Effect of the gas mixing technique on the plasma potential and emittance of the JYFL 14 GHz electron cyclotron resonance ion source

    NASA Astrophysics Data System (ADS)

    Tarvainen, O.; Suominen, P.; Ropponen, T.; Kalvas, T.; Heikkinen, P.; Koivisto, H.

    2005-09-01

    The effect of the gas mixing technique on the plasma potential, energy spread, and emittance of ion beams extracted from the JYFL 14 GHz electron cyclotron resonance ion source has been studied under various gas mixing conditions. The plasma potential and energy spread of the ion beams were studied with a plasma potential instrument developed at the Department of Physics, University of Jyväskylä (JYFL). With the instrument the effects of the gas mixing on different plasma parameters such as plasma potential and the energy distribution of the ions can be studied. The purpose of this work was to confirm that ion cooling can explain the beneficial effect of the gas mixing on the production of highly charged ion beams. This was done by measuring the ion-beam current as a function of a stopping voltage in conjunction with emittance measurements. It was observed that gas mixing affects the shape of the beam current decay curves measured with low charge-state ion beams indicating that the temperature and/or the spatial distribution of these ions is affected by the mixing gas. The results obtained in the emittance measurements support the conclusion that the ion temperature changes due to the gas mixing. The effect of the energy spread on the emittance of different ion beams was also studied theoretically. It was observed that the emittance depends considerably on the dispersive matrix elements of the beam line transfer matrix. This effect is due to the fact that the dipole magnet is a dispersive ion optical component. The effect of the energy spread on the measured emittance in the bending plane of the magnet can be several tens of percent.

  10. 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

    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

    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. 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. 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). γH2AX-foci formation, triggered by beta- and alpha-irradiation, is an early key

  11. 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

  12. 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.

  13. Quantitative Auger analysis of Nb-Ge superconducting alloys

    SciTech Connect

    Buitrago, R.H.

    1980-01-01

    The feasibility of using Auger electron analysis for quantitative analysis was investigated by studying Nb/sub 3/Ge thin-film Auger data with different approaches. A method base on elemental standards gave consistent quantitative values with reported Nb-Ge data. Alloy sputter yields were also calculated and results were consistent with those for pure elements.

  14. 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.

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

    SciTech Connect

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

    2015-02-02

    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.

  16. Auger electron spectroscopy study of reactor walls in transition from an O{sub 2} to a Cl{sub 2} plasma

    SciTech Connect

    Guha, Joydeep; Donnelly, Vincent M.

    2009-05-15

    In plasma etching processes, the reactor wall conditions can change over time due to a number of intentional and unintentional reasons, leading to a variability in the radical number densities in the plasma, caused by changes in the probabilities for reactions such as recombination at the walls. This leads to loss of reproducibility in the etching process. Here the authors isolated one such effect in which the feed gas was changed in the absence of a substrate. The transient surface composition of an anodized aluminum surface was determined for inductively coupled plasmas as the gas was switched from Cl{sub 2} to O{sub 2} and vice versa. The study was carried out with the spinning wall method and Auger electron spectroscopy. When the surface was first conditioned in an O{sub 2} plasma and then exposed to Cl{sub 2} plasmas, a rapid uptake of Cl was found in the first tens of seconds, followed by a slow approach to a steady-state value within {approx}5 min of plasma exposure. Conversely, when the surface was exposed to a Cl{sub 2} plasma for a long time and then switched to an O{sub 2} plasma, the anodized aluminum surface underwent a rapid dechlorination in the first few seconds and then a slow approach to steady state over {approx}3 min. Throughout these treatments, the coverages of Si (from erosion of the quartz discharge tube) and O were nearly constant.

  17. Influence of the "surface effect" on the segregation parameters of S in Fe(100): A multi-scale modelling and Auger Electron Spectroscopy study

    NASA Astrophysics Data System (ADS)

    Barnard, P. E.; Terblans, J. J.; Swart, H. C.

    2015-12-01

    The article takes a new look at the process of atomic segregation by considering the influence of surface relaxation on the segregation parameters; the activation energy (Q), segregation energy (ΔG), interaction parameter (Ω) and the pre-exponential factor (D0). Computational modelling, namely Density Functional Theory (DFT) and the Modified Darken Model (MDM) in conjunction with Auger Electron Spectroscopy (AES) was utilized to study the variation of the segregation parameters for S in the surface region of Fe(100). Results indicate a variation in each of the segregation parameters as a function of the atomic layer under consideration. Values of the segregation parameters varied more dramatically as the surface layer is approached, with atomic layer 2 having the largest deviations in comparison to the bulk values. This atomic layer had the highest Q value and formed the rate limiting step for the segregation of S towards the Fe(100) surface. It was found that the segregation process is influenced by two sets of segregation parameters, those of the surface region formed by atomic layer 2, and those in the bulk material. This article is the first to conduct a full scale investigation on the influence of surface relaxation on segregation and labelled it the "surface effect".

  18. 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

  19. Experimental Development of Low-emittance Field-emission Electron Sources

    SciTech Connect

    Lueangaranwong, A.; Buzzard, C.; Divan, R.; Korampally, V.; Piot, P.

    2016-10-10

    Field emission electron sources are capable of extreme brightness when excited by static or time-dependent electro- magnetic fields. We are currently developing a cathode test stand operating in DC mode with possibility to trigger the emission using ultra-short (~ 100-fs) laser pulses. This contribution describes the status of an experiment to investigate field-emission using cathodes under development at NIU in collaboration with the Argonne’s Center for Nanoscale Materials.

  20. Viability of Using Diamond Field Emitter Array Cathodes in Free Electron Lasers

    DTIC Science & Technology

    2010-06-01

    that are encountered by solid - state , gas, or chemical lasers. Another benefit of FELs is their inherent flexibility. By varying just a few system...electron lasers (FEL) for shipboard use is of great interest to the United States Navy. This thesis gains insight, through simulation and design...United States Navy B.S., United States Naval Academy, 2001 M.E.M., Old Dominion University, 2006 Submitted in partial fulfillment of the

  1. 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.

  2. Selective emitters

    NASA Astrophysics Data System (ADS)

    Chubb, Donald L.

    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.

  3. Observation of the Auger resonant Raman effect

    SciTech Connect

    Brown, G.S.; Chen, M.H.; Crasemann, B.; Ice, G.E.

    1980-11-01

    Monochromatized synchrotron radiation near the photoionization threshold was used to produce the (2p/sub 3/2/) vacancy state in atomic Xe. Deexcitation of the state through L/sub 3/-M/sub 4/M/sub 5/(/sup 1/G/sub 4/) Auger-electron emission was measured. The 5d spectator-electron Auger satellite was observed. The satellite energy exhibits linear dispersion. The observed width of the /sup 1/G diagram line decreases by approx. 40% when the exciting photon energy reaches the vicinity of the Xe L/sub 3/ binding energy. This radiationless process can thus be construed as the Auger analog of the x-ray resonant Raman effect. The /sup 1/G diagram line is shifted by -+3 eV due to post-collision interaction; this shift varies with excitation energy.

  4. 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

  5. Direct Observations of Correlation between Si-2p Components and Surface States on Si(110)-16 × 2 Single-Domain Surface Using Si-L23VV Auger-Electron and Si-2p Photoelectron Coincidence Measurements

    NASA Astrophysics Data System (ADS)

    Kakiuchi, Takuhiro; Yoshizaki, Yuya; Kubota, Hiroyuki; Sato, Yuki; Nagaoka, Shin-ichi; Mase, Kazuhiko

    2017-05-01

    A Si(110)-16 × 2 single-domain (SD) surface is investigated in a site-selective way using Si L23VV Auger-electron Si-2p photoelectron coincidence spectroscopy (Si-L23VV-Si-2p APECS) and Si-2p photoelectron Si-L23VV Auger-electron coincidence spectroscopy (Si-2p-Si-L23VV PEACS). The Si(110)-16 × 2 SD consists of five Si-2p surface components (SC1-SC5) and has four semiconducting surface states (S1-S4). The Si-L2VV-Si-2p1/2 APECS spectrum of the Si(110)-16 × 2 SD measured in coincidence with Si-2p1/2 photoelectrons of SC3, SC4, and SC5 shows two small shoulders in the higher Auger electron kinetic energy (AeKE) region. These shoulders suggest Auger processes involving the surface states S1 and S3. The spectral weights of SC3, SC4, and SC5 Si-2p components are greatly enhanced in the Si-2p-Si-L23VV PEACS spectrum measured at Auger electrons with an AeKE of +5.0 eV relative to the Si L23VV peak. On the other hand, the spectral weights of SC1 and SC2 Si-2p components in the Si-2p-Si-L23VV PEACS spectrum show a maximum peak at a relative AeKE of +3 eV. These results directly support the correlations between the five surface components (SC1-SC5) and four surface states (S1-S4) in the adatom-buckling model for the Si(110)-16 × 2 SD proposed by Sakamoto et al. [Phys. Rev. B 79, 045304 (2009)].

  6. Automatic emittance measurement at the ATF

    SciTech Connect

    Wang, X.J.; Malone, R.; Batchelor, K.; Ben-Zvi, I.

    1993-07-01

    An automatic emittance measurement system to characterize the transverse emittance of the electron beam produced by the BNL photocathode electron gun is described. The system utilize a VAX workstation and a Spiricon beam analyzer. A operator window (created through the Vista control software package) controls the emittance measurement system and the graphic presentation of the results. Quadrupole variation method is used for the ATF automatic emittance measurement system. A simple emittance formula was derived to study the performance of the quadrupole variation method, and compared with the ATF experimental data is also presented.

  7. 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

  8. Auger spectrometry of atoms and molecules

    SciTech Connect

    Krause, M.O.

    1994-09-01

    The author discusses the importance of Auger spectrometry at synchrotron radiation centers. First, he explains how a high energy photon source such as the APS (Advanced Photon Source) could be used to help provide missing spectral information about the shell structure of some elements. The missing data occurs mainly at higher energies in the 1--10 keV ranges as for the K-shells of Z = 30 to 60 elements and the L-shells for Z = 30 to 100 elements. He explains how even though Auger electron spectrometry does not depend on synchrotron radiation it can greatly benefit from this variable photon source as it allows one to select the Auger line group that is most suitable for a specific purpose. Most significantly, a continuous photon source becomes indispensable when one is interested in threshold effects. Lastly, he discusses coherence effects between different inner-shell vacancy states by way of some recent work done at Daresbury.

  9. 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.

  10. Fundamental study of catalysts using laser Raman, infrared, Auger electron spectroscopy and low energy electron diffraction. Progress report. [Carbon monoxide methanation with nickel catalyst

    SciTech Connect

    Sargent, G.A.; Bradley, E.B.

    1981-03-01

    The fundamantal goal of this project is to develop an understanding of catalytic activity and selectivity with the long-range goal of producing better catalysts. The techniques of LEED, Auger spectroscopy, and laser Raman and infared spectroscopies are being used to study the surface structure and obnding of CO, CH/sub 4/, H/sub 2/ and O/sub 2/ adsorbed on Ni(111) and Ni(100) single crystal surfaces. The surface coverage is controlled by varying the gas pressure and exposure time. Surface dipoles (magitude and orientation) are being measured for spectroscopic techniques. Laser Raman and infrared spectroscopy are used to determine vibrational modes of surface structures of the adsorbed molecules and the polarization of Raman bands and changes in band intensities are used to determine electric dipole orientation and thermal desorption characteristics. Thermal desorption experiments have been undertaken for each gas absorbed on each surface using the linear temperature programming technique. The mass of the desorbed species is determined by means of a precision mass analyzer. The mass analyzer is also used to determine residual gas concentrations in the experimental chamber and to identify the structure of intermediate molecules. A new theory has been developed to explain enhanced Raman scatteirng from surface adsorbed species. The theory explains, with good agrement, the Raman scattered intensities observed from molecules adsorbed on smooth and rough surfaces.

  11. Suppression of Divergence of Low Energy Ion Beams by Space Charge Neutralization with Low Energy Electrons Emitted from Field Emitter Arrays

    SciTech Connect

    Ishikawa, Junzo; Gotoh, Yasuhito; Taguchi, Shuhei; Nicolaescu, Dan; Tsuji, Hiroshi; Kimoto, Tsunenobu; Takeuchi, Mitsuaki; Sakai, Shigeki

    2011-01-07

    Suppression of divergence of low energy neon ion beam was experimentally demonstrated by neutralizing the space charge of ion beam with low energy electrons emitted from silicon field emitter arrays (Si-FEAs). Treatment of the FEAs with trifluoromethane plasma realized surface carbonization which was efficient to elongate the lifetime of the FEA and to improve the electron energy distribution. Together with the improvement of the performance of Si-FEA, we have developed a novel electron deceleration system to produce low energy electrons. A low energy neon ion beam was produced and the beam property was investigated with and without the electron supply from surface carbonized Si-FEA (Si:C-FEA). As a result, the divergence of the neon ion beam was largely suppressed with presence of the electrons.

  12. 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

  13. 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 .

  14. Experimentally accessible signatures of Auger scattering in graphene

    NASA Astrophysics Data System (ADS)

    Winzer, Torben; Jago, Roland; Malic, Ermin

    2016-12-01

    The gapless and linear electronic band structure of graphene opens up Auger scattering channels bridging the valence and the conduction band and changing the charge carrier density. Here, we reveal experimentally accessible signatures of Auger scattering in optically excited graphene. To be able to focus on signatures of Auger scattering, we apply a low excitation energy, weak pump fluences, and a cryostatic temperature, so that all relevant processes lie energetically below the optical phonon threshold. In this regime, carrier-phonon scattering is strongly suppressed and Coulomb processes govern the carrier dynamics. Depending on the excitation regime, we find an accumulation or depletion of the carrier occupation close to the Dirac point. This reflects well the behavior predicted from Auger-dominated carrier dynamics. Based on this observation, we propose a multicolor pump-probe experiment to uncover the extreme importance of Auger channels for the nonequilibrium dynamics in graphene.

  15. 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.

  16. 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.

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

    PubMed

    Baunack, S; Subba Rao, R V; Wolff, U

    2003-04-01

    Amorphous ribbons of Mg-Y-TM-[Ag] (TM: Cu, Ni), prepared by melt spinning, were subjected to electrochemical investigations. Oxide layers formed anodically under potentiostatic control in different electrolytes were investigated by AES and sputter depth profiling. Problems and specific features of characterization of the composition of oxide layers and amorphous ternary or quaternary Mg-based alloys have been investigated. In the alloys the Mg(KL(23)L(23)) peak exhibits a different shape compared to that in the pure element. Analysis of the peak of elastically scattered electrons proved the absence of plasmon loss features, characteristic of pure Mg, in the alloy. A different loss feature emerges in Mg(KL(23)L(23)) and Cu(L(23)VV). The system Mg-Y-TM-[Ag] suffers preferential sputtering. Depletion of Mg and enrichment of TM and Y are found. This is attributed mainly to the preferential sputtering of Mg. Thickness and composition of the formed oxide layer depend on the electrochemical treatment. After removing the oxide by sputtering the concentration of the underlying alloy was found to be affected by the treatment.

  18. 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.

  19. 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.

  20. 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.

  1. Nuclear Excitation via Auger Transitions (NEAT)

    NASA Astrophysics Data System (ADS)

    Ward, Thomas; Emery, Guy; Rasmussen, John; Karwowski, Hugon; Castaneda, Carlos

    2008-10-01

    Triggering (prompt de-excitation) of isomeric states produced in a process of coupling nuclear excitations to atomic shells via Auger transitions (NEAT) is studied. In this resonant process the nuclear transition energy between the two states must be less than the Auger transition energy. This requires the emitted Auger electron energy and the exact on-resonance nuclear excitation share the Auger transition energy. NEAT is compared to other proposed processes of nuclear excitation produced by x-rays (NEET), by electron capture (NEEC) and bound internal conversion (BIC), all of which suffer from off-resonance nuclear excitation except in those accidental cases where the energies may coincide. Estimates of the total resonance strength will be given for the case of ^182mHf which has been extensively studied theoretically. A second case, ^189Os, where NEAT processes may contribute to the nuclear resonance fluorescence (NRF) of the ground state to the 5.8hr isomeric state will also be examined as a good case for experimental verification of the NEAT process.

  2. 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.

  3. Theory and Application of Auger and Photoelectron Diffraction and Holography

    NASA Astrophysics Data System (ADS)

    Chen, Xiang

    This dissertation addresses the theories and applications of three important surface analysis techniques: Auger electron diffraction (AED), x-ray photoelectron diffraction (XPD), and Auger and photoelectron holography. A full multiple-scattering scheme for the calculations of XPD, AED, and Kikuchi electron diffraction pattern from a surface cluster is described. It is used to simulate 64 eV M_{2,3}VV and 913 eV L_3VV AED patterns from Cu(001) surfaces, in order to test assertions in the literature that they are explicable by a classical "blocking" and channeling model. We find that this contention is not valid, and that only a quantum mechanical multiple-scattering calculation is able to simulate these patterns well. The same multiple scattering simulation scheme is also used to investigate the anomalous phenomena of peak shifts off the forward-scattering directions in photo -electron diffraction patterns of Mg KLL (1180 eV) and O 1s (955 eV) from MgO(001) surfaces. These shifts are explained by calculations assuming a short electron mean free path. Similar simulations of XPD from a CoSi_2(111) surface for Co-3p and Si-2p normal emission agree well with experimental diffraction patterns. A filtering process aimed at eliminating the self -interference effect in photoelectron holography is developed. A better reconstructed image from Si-2p XPD from a Si(001) (2 times 1) surface is seen at atomic resolution. A reconstruction algorithm which corrects for the anisotropic emitter waves as well as the anisotropic atomic scattering factors is used for holographic reconstruction from a Co-3p XPD pattern from a CoSi_2 surface. This new algorithm considerably improves the reconstructed image. Finally, a new reconstruction algorithm called "atomic position recovery by iterative optimization of reconstructed intensities" (APRIORI), which takes account of the self-interference terms omitted by the other holographic algorithms, is developed. Tests on a Ni-C-O chain and Si(111

  4. Initial-state-selected M N N Auger spectroscopy of atomic rubidium

    NASA Astrophysics Data System (ADS)

    Keskinen, J.; Lablanquie, P.; Penent, F.; Palaudoux, J.; Andric, L.; Cubaynes, D.; Bizau, J.-M.; Huttula, M.; Jänkälä, K.

    2017-04-01

    The M4 ,5N2 ,3N2 ,3 and M4 ,5N1N2 ,3 Auger decay of atomic Rb have been studied by using photoelectron-Auger electron coincidence measurements that enable initial ionic state selected Auger spectroscopy. The Auger spectra in the present study are separated by the total angular momentum j of the 3 d hole and the orbital of the valence electron n ℓ after photoionization. It is shown that the technique allows isolating overlapping features and the study of otherwise unobservable spectral details, from which the presence of shake-down transitions during normal Auger decay is demonstrated experimentally. The technique allows also probing the effects of initial state parity and electron correlation in Auger electron spectroscopy. The observed spectral features are interpreted with theoretical predictions obtained from configuration interaction Dirac-Fock approach.

  5. 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.

  6. Recombination processes in passivated boron-implanted black silicon emitters

    NASA Astrophysics Data System (ADS)

    von Gastrow, Guillaume; Ortega, Pablo; Alcubilla, Ramon; Husein, Sebastian; Nietzold, Tara; Bertoni, Mariana; Savin, Hele

    2017-05-01

    In this paper, we study the recombination mechanisms in ion-implanted black silicon (bSi) emitters and discuss their advantages over diffused emitters. In the case of diffusion, the large bSi surface area increases emitter doping and consequently Auger recombination compared to a planar surface. The total doping dose is on the contrary independent of the surface area in implanted emitters, and as a result, we show that ion implantation allows control of emitter doping without compromise in the surface aspect ratio. The possibility to control surface doping via implantation anneal becomes highly advantageous in bSi emitters, where surface passivation becomes critical due to the increased surface area. We extract fundamental surface recombination velocities Sn through numerical simulations and obtain the lowest values at the highest anneal temperatures. With these conditions, an excellent emitter saturation current (J0e) is obtained in implanted bSi emitters, reaching 20 fA/cm2 ± 5 fA/cm2 at a sheet resistance of 170 Ω/sq. Finally, we identify the different regimes of recombination in planar and bSi emitters as a function of implantation anneal temperature. Based on experimental data and numerical simulations, we show that surface recombination can be reduced to a negligible contribution in implanted bSi emitters, which explains the low J0e obtained.

  7. 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.

  8. Normal Auger processes with ultrashort x-ray pulses in neon

    NASA Astrophysics Data System (ADS)

    Sullivan, Raymond; Jia, Junteng; Vázquez-Mayagoitia, Álvaro; Picón, Antonio

    2016-10-01

    Modern x-ray sources enable the production of coherent x-ray pulses with a pulse duration in the same order as the characteristic lifetimes of core-hole states of atoms and molecules. These pulses enable the manipulation of the core-hole population during Auger-decay processes, modifying the line shape of the electron spectra. In this work, we present a theoretical model to study those effects in neon. We identify effects in the Auger-electron-photoelectron coincidence spectrum due to the duration and intensity of the pulses. The normal Auger line shape is recovered in Auger-electron spectra integrated over all photoelectron energies.

  9. Dependence of the Light Emission Characteristics on the Ne Gas Pressure in an Electron-beam-pumped Light Source Using a Field Emitter

    NASA Astrophysics Data System (ADS)

    Shiozawa, Kazufumi; Neo, Yoichiro; Okada, Morihiro; Kume, Hiroshi; Matsumoto, Takahiro; Ikedo, Tomoyuki; Takahashi, Masafumi; Hashiguchi, Gen; Mimura, Hidenori

    The dependence of the light intensity on the gas pressure was investigated in an electron-beam-pumped-light source using a graphite nanoneedle field emitter, a Si electron-transparent film and a Ne gas. A spot-like light emission and a background light emission are observed in at a Ne gas pressure less than 0.4 atm, while the back ground light emission disappears and the light emission becomes a completely spot with increasing the gas pressure. These experimental results are explained by the Monte-Calro simulation of electron trajectories inside the gas cell. On the other hand, the light intensity almost saturates at a gas pressure of 0.4 atm and dose not increase with increasing the gas pressure. The Monte-Calro simulation suggests that the saturation of the light intensity is due to the increase of the excited Ne atoms losing their energy without light emission.

  10. The Pierre Auger Observatory

    SciTech Connect

    Hojvat, C.

    1997-03-01

    The Pierre Auger Observatory is an international collaboration for the detailed study of the highest energy cosmic rays. It will operate at two similar sites, one in the northern hemisphere and one in the southern hemisphere. The Observatory is designed to collect a statistically significant data set of events with energies greater than 10{sup 19} eV and with equal exposures for the northern and southern skies.

  11. 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.

  12. 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.

  13. Normal Auger spectra of iodine in gas phase alkali iodide molecules

    NASA Astrophysics Data System (ADS)

    Hu, Zhengfa; Caló, Antonio; Kukk, Edwin; Aksela, Helena; Aksela, Seppo

    2005-06-01

    Molecular normal Auger electron spectra following the iodine 4d ionization in gas-phase alkali iodides were investigated both experimentally and theoretically. The Auger electron spectra for LiI, NaI and KI were recorded using electron impact, and for RbI by using photo-excitation. These Auger spectra were analyzed in detail and compared to the referenced normal Auger spectra of HI [L. Karlsson, S. Svensson, P. Baltzer, M. Carlsson-Göthe, M.P. Keane, A. Naves de Brito, N. Correia, B. Wannberg, J. Phys. B 22 (1989) 3001]. An energy shift toward higher kinetic energy and a narrowing in linewidth are observed in the Auger spectra series revealing the effect of the changing environment from covalently bonded HI to ionic alkali iodide compounds. The experimental results are also compared with the theoretical ab initio calculations and with the Auger spectra of I -, computed with the multiconfiguration Hartree-Fock (MCHF) method.

  14. Auger electron-emitting (111)In-DTPA-NLS-CSL360 radioimmunoconjugates are cytotoxic to human acute myeloid leukemia (AML) cells displaying the CD123(+)/CD131(-) phenotype of leukemia stem cells.

    PubMed

    Gao, Catherine; Leyton, Jeffrey V; Schimmer, Aaron D; Minden, Mark; Reilly, Raymond M

    2016-04-01

    Chimeric IgG1 monoclonal antibody CSL360 recognizes the CD123(+)/CD131(-) phenotype expressed by leukemic stem cells (LSC). Auger electron-emitting (111)In-DTPA-NLS-CSL360 radioimmunoconjugates incorporating nuclear translocation sequence (NLS) peptides bound specifically to Raji cells transfected with CD123 and exhibited a KD of 11nmols/L in a competition receptor-binding assay using CD123-transfected CHO cells. (111)In-DTPA-NLS-CSL360 was bound, internalized and transported to the nucleus of human AML-5 myeloid leukemia cells. The clonogenic survival of AML-5 cells was reduced by (111)In-DTPA-NLS-CSL360 up to 3.7-fold. Isotype control (111)In-DTPA-chIgG1 was 2-fold less cytotoxic, and unlabeled CSL360, DTPA-NLS-CSL360 or free (111)In acetate did not decrease cell survival. These results are promising for further evaluation of (111)In-DTPA-NLS-CSL360 for Auger electron radioimmunotherapy of AML targeting the critical LSC subpopulation. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Brownian Emitters

    NASA Astrophysics Data System (ADS)

    Tsekov, Roumen

    2016-06-01

    A Brownian harmonic oscillator, which dissipates energy either by friction or via emission of electromagnetic radiation, is considered. This Brownian emitter is driven by the surrounding thermo-quantum fluctuations, which are theoretically described by the fluctuation-dissipation theorem. It is shown how the Abraham-Lorentz force leads to dependence of the half-width on the peak frequency of the oscillator amplitude spectral density. It is found that for the case of a charged particle moving in vacuum at zero temperature, its root-mean-square velocity fluctuation is a universal constant, equal to roughly 1/18 of the speed of light. The relevant Fokker-Planck and Smoluchowski equations are also derived.

  16. Transverse Emittance Reduction with Tapered Foil

    SciTech Connect

    Jiao, Yi; Chao, Alex; Cai, Yunhai; /SLAC

    2011-12-09

    The idea of reducing transverse emittance with tapered energy-loss foil is proposed by J.M. Peterson in 1980s and recently by B. Carlsten. In this paper, we present the physical model of tapered energy-loss foil and analyze the emittance reduction using the concept of eigen emittance. The study shows that, to reduce transverse emittance, one should collimate at least 4% of particles which has either much low energy or large transverse divergence. The multiple coulomb scattering is not trivial, leading to a limited emittance reduction ratio. Small transverse emittances are of essential importance for the accelerator facilities generating free electron lasers, especially in hard X-ray region. The idea of reducing transverse emittance with tapered energy-loss foil is recently proposed by B. Carlsten [1], and can be traced back to J.M. Peterson's work in 1980s [2]. Peterson illustrated that a transverse energy gradient can be produced with a tapered energy-loss foil which in turn leads to transverse emittance reduction, and also analyzed the emittance growth from the associated multiple coulomb scattering. However, what Peterson proposed was rather a conceptual than a practical design. In this paper, we build a more complete physical model of the tapered foil based on Ref. [2], including the analysis of the transverse emittance reduction using the concept of eigen emittance and confirming the results by various numerical simulations. The eigen emittance equals to the projected emittance when there is no cross correlation in beam's second order moments matrix [3]. To calculate the eigen emittances, it requires only to know the beam distribution at the foil exit. Thus, the analysis of emittance reduction and the optics design of the subsequent beam line section can be separated. In addition, we can combine the effects of multiple coulomb scattering and transverse energy gradient together in the beam matrix and analyze their net effect. We find that,when applied to an

  17. EMITTANCE CONTROL FOR VERY SHORT BUNCHES

    SciTech Connect

    Bane, K

    2004-07-20

    Many recent accelerator projects call for the production of high energy bunches of electrons or positrons that are simultaneously short, intense, and have small emittances. Examples of such projects are the Self-Amplified Spontaneous Emission (SASE) FEL's, such as the Linac Coherent Light Source (LCLS). A major challenge is keeping in check forces that increase beam emittances in accelerator components, such as: wakefields of accelerator structures and surface roughness, and coherent synchrotron radiation. We describe such forces and discuss emittance control.

  18. Epidermal growth factor receptor inhibition modulates the nuclear localization and cytotoxicity of the Auger electron emitting radiopharmaceutical 111In-DTPA human epidermal growth factor.

    PubMed

    Bailey, Kristy E; Costantini, Danny L; Cai, Zhongli; Scollard, Deborah A; Chen, Zhuo; Reilly, Raymond M; Vallis, Katherine A

    2007-09-01

    (111)In-DTPA-human epidermal growth factor ((111)In-DTPA-hEGF [DTPA is diethylenetriaminepentaacetic acid]) is an Auger electron-emitting radiopharmaceutical that targets EGF receptor (EGFR)-positive cancer. The purpose of this study was to determine the effect of EGFR inhibition by gefitinib on the internalization, nuclear translocation, and cytotoxicity of (111)In-DTPA-hEGF in EGFR-overexpressing MDA-MB-468 human breast cancer cells. Western blot analysis was used to determine the optimum concentration of gefitinib to abolish EGFR activation. Internalization and nuclear translocation of fluorescein isothiocyanate-labeled hEGF were evaluated by confocal microscopy in MDA-MB-468 cells (1.3 x 10(6) EGFRs/cell) in the presence or absence of 1 microM gefitinib. The proportion of radioactivity partitioning into the cytoplasm and nucleus of MDA-MB-468 cells after incubation with (111)In-DTPA-hEGF for 24 h at 37 degrees C in the presence or absence of 1 microM gefitinib was measured by cell fractionation. DNA double-strand breaks caused by (111)In were quantified using the gamma-H2AX assay, and radiation-absorbed doses were estimated. Clonogenic survival assays were used to measure the cytotoxicity of (111)In-DTPA-hEGF alone or in combination with gefitinib. Gefitinib (1 microM) completely abolished EGFR phosphorylation in MDA-MB-468 cells. Internalization and nuclear translocation of fluorescein isothiocyanate-labeled EGF were not diminished in gefitinib-treated cells compared with controls. The proportion of internalized (111)In that localized in the nucleus was statistically significantly greater when (111)In-DTPA-hEGF was combined with gefitinib compared with (111)In-DTPA-hEGF alone (mean +/- SD: 26.0% +/- 5.5% vs. 14.6% +/- 4.0%, respectively; P < 0.05). Induction of gamma-H2AX foci was greater in MDA-MB-468 cells that were treated with (111)In-DTPA-hEGF (250 ng/mL, 1.5 MBq/mL) plus gefitinib (1 microM ) compared with those treated with (111)In-DTPA-hEGF alone (mean

  19. Probing electronic and vibrational dynamics in molecules by time-resolved photoelectron, Auger-electron, and X-ray photon scattering spectroscopy.

    PubMed

    Bennett, Kochise; Kowalewski, Markus; Mukamel, Shaul

    2015-01-01

    We present a unified description for time-resolved electron and photon scattering spectroscopies from molecules prepared in nonstationary states. Signals are expressed in terms of superoperator Green's functions and a systematic procedure for treating various degrees of freedom consistently at different levels of theory is developed. The standard Fermi Golden Rule expressions for photoelectron spectra, which are limited to broad, slowly-varying signals, are obtained as a limiting case of our more general theory that applies to broader parameter regimes.

  20. Triple ionization spectra by coincidence measurements of double Auger decay: The case of OCS.

    PubMed

    Eland, J H D; Hochlaf, M; Linusson, P; Andersson, E; Hedin, L; Feifel, R

    2010-01-07

    By combining multiple electron coincidence detection with ionization by synchrotron radiation, we have obtained resolved spectra of the OCS(3+) ion created through the double Auger effect. The form of the spectra depends critically on the identity of the atom bearing the initial hole. High and intermediate level electron structure calculations lead to an assignment of the resolved spectrum from ionization via the S 2p hole. From the analysis it appears that the double Auger effect from closed shell molecules favors formation of doublet states over quartet states. Molecular field effects in the double Auger effect are similar to those in the single Auger effect in linear molecules.